Title:

RECORDING MEDIUM, RECORDING METHOD, REPRODUCTION METHOD, RECORDING APPARATUS AND REPRODUCTION APPARATUS

Document Type and Number:

United States Patent Application 20080212438

Kind Code:

Abstract:

A recording medium comprising a recording area, the recording area includes a first area and a second area, the first area includes a frame area, the frame area includes an area in which a second synchronization code sequence and at least a portion of data are to be recorded, and the second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are to be recorded.

Inventors:

Gushima, Toyoji (Osaka, JP)
Furumiya, Shigeru (Hyogo, JP)
Ishida, Takashi (Kyoto, JP)
Ishibashi, Hiromichi (Osaka, JP)
Deguchi, Hironori (Osaka, JP)
Nakamura, Atsushi (Osaka, JP)
Minamino, Junichi (Nara, JP)
Usui, Makoto (Osaka, JP)
Nakajima, Takeshi (Nara, JP)

Plaque It!

TECHNICAL FIELD

The present invention relates to an optical disc medium allowing high density data recording, and a method and apparatus for recording data on or reproducing data from the optical disc medium.

BACKGROUND ART

Recently, the recording density of optical disc media has been rapidly increasing. In the case of optical disc media allowing digital data recording, data recording, reproduction and management are generally performed in units of blocks, each block having a prescribed byte length. (Such a block will be referred to as a “data block”.) Each data block is given address information. Data recording and reproduction are performed with reference to the address information.

For recording data on an optical disc medium, user data such as, for example, audio, video and computer data to be stored is provided with redundant data such as, for example, an error correction code (parity code) used for detecting or correcting a data error when the stored data is read. The user data provided with the redundant data is transformed in accordance with a modulation code system suitable to the characteristics of recording and reproduction signals for the optical disc medium. On the optical disc medium, the post-transformation data bit stream is recorded. One known modulation code system which is often used for optical disc media is run length limited code.

A run length limited code determines the post-transformation data bit stream so that the number of “0” bits interposed between two “1” bits in a bit sequence is limited to a prescribed number. The number of “0” bits interposed between “1” bits will be referred to as a “zero run”. An interval (length) between one “1” bit to the next “1” bit in a data bit stream (code sequence) will be referred to as an “inversion interval”. The limitation of the zero run determines the limits, i.e., the maximum value and the minimum value, of the inversion interval of a data bit stream. The maximum value will be referred to as a “maximum inversion interval k” and a “minimum inversion interval d”.

In the case where a data bit stream is recorded on an optical disc medium by mark position recording (PPM: Pit Position Modulation), bit “1” of the data bit stream corresponds to a recording mark, and a zero run “0”s corresponds to a space. In the case where a data bit stream is recorded on an optical disc medium by mark length recording (PWM: Pulse Width Modulation), the recording state, i.e., whether a recording mark is to be recorded on the optical disc medium or a space is to be recorded, is switched when a “1” bit of the data bit stream occurs. In the case of mark length recording, the inversion interval corresponds to the length of a recording mark or the length of a space.

Accordingly, when, for example, the minimum value of the physical size of marks which can be formed on an optical disc medium (such a minimum value will be referred to as a “mark unit”) is equal in the mark position recording and the mark length recording, mark position recording requires 3 mark units in order to record data of a minimum code length (3 bits “100” of a data bit stream), but the mark length recording requires only one mark unit.

When a run length limited code having a minimum inversion interval d=2 is used, the number of bits per unit length of track of the optical disc medium is larger in the case of the mark length recording than in the case of the mark position recording. Namely, the recording density is higher by the mark length recording than by the mark position recording.

In general, when a data bit stream transformed into a modulation code is recorded on an optical disc medium, a synchronization pattern is often inserted into the data bit stream at every prescribed cycle of the data bit stream. Such a synchronization pattern performs proper data synchronization when the data bit stream is read. According to one known technique for inserting the synchronization pattern, a synchronization pattern including a sequence which does not exist in a modulation code sequence is inserted at the start of an area, referred to as a frame area, having a prescribed byte length.

Among some data formats for recording-type optical disc media which have recently been put into practice, the DVD-RW data format will be briefly described.

In the DVD-RW data format, address information is arranged by pre-pits which are located in a land between two adjacent groove tracks in which data is to be recorded. Data is continuously recorded on the groove tracks. An ECC block, which is a minimum unit for data recording and reproduction, includes a plurality of areas, referred to as data frame areas, each having a fixed byte length. A data frame area includes a synchronization information area provided at the start thereof and a data area. Data recording or reproduction is begun and terminated in the data area in the data frame area which is located at the start of each ECC block. An operation for additionally recording data in an ECC block next to the ECC block which has data already recorded therein is referred to as “linking” A data frame area corresponding to a position at which data recording is begun and terminated is referred to as a “linking frame area”.

FIG. 44 shows a data format of a linking position and the vicinity thereof of a conventional DVD-RW. In a DVD-RW, one ECC block includes 16 sectors, and one sector includes 26 frame areas. The minimum unit for data recording is one ECC block. Data recording is begun and terminated at a data area DATA of a leading frame area (linking frame area) of a leading sector S 0 of one ECC block. FIG. 44 shows the position at which data recording is begun and terminated as “start position of data recording”. In the example shown in FIG. 44, linking is performed so that the data recording is terminated at the 16th byte from the start of the linking frame area and the data recording is begun between the 15th byte and the 17th byte from the start of the linking frame area.

In the linking frame area in which the data recording is begun and terminated, data is recorded in a discontinuous manner. Therefore, data recorded from the linking beginning position (start position) to the next frame area cannot be read since accurate bit synchronization cannot be realized. Furthermore, when the low precision of linking causes the length of the frame area to be larger or smaller than the prescribed length, or when repeated linking recording in the same frame area degrades the signal in the frame area, signal reproduction systems for level-slicing, PLL or the like become unstable when the data recorded in and in the vicinity of the linking position is reproduced. In the worst case, there is a possibility that data cannot be read in several frame areas after the linking position. In such a case, error correction cannot be performed, which possibly generates a reading error. When the positioning accuracy when performing linking is less than one bit, the possibility of accurate data reading is increased. However, the tolerance of less than one bit is difficult to realize and thus is impractical as the recording density of data is increased.

The present invention, in light of the above-described problems, has an objective of providing a recording medium, a recording method, a reproduction method, a recording apparatus and a reproduction apparatus for allowing stable data recording and reproduction even at a beginning position and termination position of data recording.

DISCLOSURE OF THE INVENTION

According to one aspect of the invention, a recording medium comprising a recording area is provided. The recording area includes a first area and a second area. The first area includes a frame area. The frame area includes an area in which a second synchronization code sequence and at least a portion of data are to be recorded. The second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are to be recorded.

In one embodiment of the invention, the second synchronization code sequence represents the start of the frame area, the third synchronization code sequence represents the start of the second area, and at least a portion of the fourth synchronization code sequence is used for stably reproducing data.

In one embodiment of the invention, the first area is provided rearward with respect to the third area. The second area is provided rearward with respect to the first area. The third area includes an area in which a first synchronization code sequence is to be recorded.

In one embodiment of the invention, at least a portion of the first synchronization code sequence is used for stably reproducing data.

In one embodiment of the invention, the third area includes an area in which a fifth synchronization code sequence is to be recorded.

In one embodiment of the invention, the fifth synchronization code sequence is used for specifying the start of the first area rearward thereto.

In one embodiment of the invention, the first area includes a plurality of frame areas, the first area is divided into fourth areas each including a prescribed number of frame areas, the second synchronization code sequence recorded in the frame area located at the start of the fourth area is different from the second synchronization code sequence recorded in any of the frame areas other than the frame area located at the start of the fourth area.

In one embodiment of the invention, the second synchronization code sequence recorded in the frame area located at the start of the fourth area is different by a code distance equal to or greater than 2 from the second synchronization code sequence recorded in any of the frame areas other than the frame area located at the start of the fourth area.

In one embodiment of the invention, a length of the fourth synchronization code sequence is randomly set each time data is recorded on the recording medium.

In one embodiment of the invention, a length of the first synchronization code sequence is randomly set each time data is recorded on the recording medium.

In one embodiment of the invention, at least a portion of the fourth synchronization code sequence is overwritten by a first synchronization code sequence recorded when additional data is recorded on the recording medium.

According to another aspect of the invention, a method for recording information on a recording medium having a recording area is provided. The method includes the steps of receiving data; recording a first synchronization code sequence in the recording area, recording a frame in a first area located rearward with respect to the area of the recording area having the first synchronization code sequence recorded therein, wherein the frame includes a second synchronization code sequence and at least a portion of the received data; recording a third synchronization code sequence in an area rearward with respect to the first area; and recording a fourth synchronization code sequence in an area rearward with respect to the area of the recording area having the third synchronization code sequence recorded therein.

In one embodiment of the invention, the method further includes the step of recording a fifth synchronization code sequence in an area of the recording area which is rearward with respect to the area in which the first synchronization code sequence is recorded and is forward with respect to the first area.

In one embodiment of the invention, the step of recording the first synchronization code sequence includes the step of randomly setting a length of the first synchronization code sequence.

In one embodiment of the invention, the step of recording the fourth synchronization code sequence includes the step of randomly setting a length of the fourth synchronization code sequence.

In one embodiment of the invention, at least a portion of the first synchronization code sequence is used for stably reproducing the data. The second synchronization code sequence represents the start of the frame area. The third synchronization code sequence represents the start of a second area including the third synchronization code sequence and the fourth synchronization code sequence. At least a portion of the fourth synchronization code sequence is used for stably reproducing the data. The fifth synchronization code sequence is used for specifying the start of the first area.

In one embodiment of the invention, at least a portion of the fourth synchronization code sequence is overwritten by the first synchronization code sequence, which is recorded when additional data is recorded on the recording medium.

According to still another aspect of the invention, a method for recording additional information on a recording medium having a recording area having information recorded therein is provided. The recording area includes a first area and a second area. The first area includes a frame area. The frame area includes an area in which a second synchronization code sequence and at least a portion of data are recorded. The second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are recorded. The method includes the steps of receiving the additional data; detecting the third synchronization code sequence; determining a recording beginning position in the recording area based on the position of the detected third synchronization code sequence; recording a first additional synchronization code sequence at the recording beginning position; recording additional first area data including an additional frame in an area of the recording area rearward with respect to the area having the first additional synchronization code sequence recorded therein, wherein the additional frame includes a second additional synchronization code sequence for identifying the start of the additional frame and at least a portion of the received additional data; recording a third additional synchronization code sequence in an area rearward with respect to an additional first area having the additional first area data recorded therein; and recording a fourth additional synchronization code sequence in an area rearward with respect to the area having the third additional synchronization code sequence recorded therein.

In one embodiment of the invention, the method further includes the step of recording a fifth additional synchronization code sequence in an area of the recording area which is rearward with respect to the area in which the first additional synchronization code sequence is recorded and is forward with respect to the additional first area.

In one embodiment of the invention, at least a portion of the first additional synchronization code sequence is used for stably reproducing the data. The second additional synchronization code sequence represents the start of the frame area. The third additional synchronization code sequence represents the start of a second area including the third additional synchronization code sequence and the fourth additional synchronization code sequence. At least a portion of the fourth additional synchronization code sequence is used for stably reproducing the data. The fifth additional synchronization code sequence is used for specifying the start of the additional first area.

In one embodiment of the invention, the plurality of additional frames are grouped into a plurality of sector data each including a prescribed number of additional frames, and the second additional synchronization code sequence of the additional frame, among the prescribed number of additional frames, at the start of each sector data, is different from the second additional synchronization code sequence of any of the additional frames other than the additional frame at the start of each sector data.

In one embodiment of the invention, the second additional synchronization code sequence of the additional frame, among the prescribed number of additional frames, at the start of each sector data is different by a code distance equal to or greater than 2 from the second additional synchronization code sequences of any of the additional frames other than the additional frame at the start of each sector data.

In one embodiment of the invention, the step of determining the recording beginning position in the recording area includes the step of randomly determining the recording beginning position.

In one embodiment of the invention, the step of recording the first additional synchronization code sequence includes the step of randomly setting a length of the first additional synchronization code sequence.

In one embodiment of the invention, the step of recording the fourth additional synchronization code sequence includes the step of randomly setting a length of the fourth additional synchronization code sequence.

In one embodiment of the invention, the step of determining the recording beginning position in the recording area includes the step of determining the recording beginning position so that at least a portion of the fourth synchronization code sequence is overwritten by the first additional synchronization code sequence.

According to still another aspect of the invention, a recording apparatus for recording information on a recording medium having a recording area is provided. The recording apparatus includes a receiving section for receiving data; and a recording section for recording a first synchronization code sequence in the recording area. The recording section records a frame in a first area located rearward with respect to the area of the recording area having the first synchronization code sequence recorded therein. The frame includes a second synchronization code sequence and at least a portion of the received data. The recording section records a third synchronization code sequence in an area rearward with respect to a first area. The recording section records a fourth synchronization code sequence in an area rearward with respect to the area of the recording area having the third synchronization code sequence recorded therein.

In one embodiment of the invention, the recording apparatus records a fifth synchronization code sequence in an area of the recording area which is rearward with respect to the area in which the first synchronization code sequence is recorded and is forward with respect to the first area.

In one embodiment of the invention, the recording section randomly sets a length of the first synchronization code sequence.

In one embodiment of the invention, the recording section randomly sets a length of the fourth synchronization code sequence.

According to still another aspect of the invention, a recording apparatus for recording additional information on a recording medium having a recording area having information recorded therein is provided. The recording area includes a first area and a second area. The first area includes a frame area. The frame area includes an area in which a second synchronization code sequence and at least a portion of data are recorded. The second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are recorded. The recording apparatus includes a recording section for receiving the additional data; a detection section for detecting the third synchronization code sequence; a determination section for determining a recording beginning position in the recording area based on the position of the detected third synchronization code sequence; and a recording section for recording a first additional synchronization code sequence at the recording beginning position. The recording section records additional first area data including an additional frame in an area of the recording area rearward with respect to the area having the first additional synchronization code sequence recorded therein, wherein the additional frame includes a second additional synchronization code sequence for identifying the start of the additional frame and at least a portion of the received additional data. The recording section records a third additional synchronization code sequence in an area rearward with respect to an additional first area having the additional first area data recorded therein. The recording section records a fourth additional synchronization code sequence in an area rearward with respect to the area having the third additional synchronization code sequence recorded therein.

In one embodiment of the invention, the recording section records a fifth additional synchronization code sequence in an area of the recording area which is rearward with respect to the area in which the first additional synchronization code sequence is recorded and is forward with respect to the additional first area.

In one embodiment of the invention, the determination section randomly determines the recording beginning position.

In one embodiment of the invention, the recording section randomly sets a length of the first additional synchronization code sequence.

In one embodiment of the invention, the recording section randomly sets a length of the fourth additional synchronization code sequence.

In one embodiment of the invention, the determination section determines the recording beginning position so that at least a portion of the fourth synchronization code sequence is overwritten by the first synchronization code sequence.

According to still another aspect of the invention, a method for reproducing information recorded on a recording medium having a recording area is provided. The recording area includes a first area and a second area. The first area includes a frame area. The frame area includes an area in which a second synchronization code sequence and at least a portion of data are recorded. The second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are recorded. The method includes the steps of reproducing the third synchronization code sequence; reproducing the fourth synchronization code sequence; reproducing the second synchronization code sequence; and reproducing the at least a portion of the data.

In one embodiment of the invention, the first area is provided rearward with respect to the third area, and the second area is provided rearward with respect to the first area. The third area includes an area in which a first synchronization code sequence is recorded. The method further includes the step of reproducing the first synchronization code sequence.

In one embodiment of the invention, at least a portion of the first synchronization code sequence is used for stably reproducing data.

In one embodiment of the invention, the third area includes an area in which a fifth synchronization code sequence is to be recorded.

In one embodiment of the invention, the fifth synchronization code sequence is used for specifying the start of the first area rearward thereto.

In one embodiment of the invention, a length of the fourth synchronization code sequence is randomly set each time data is recorded on the recording medium.

In one embodiment of the invention, a length of the first synchronization code sequence is randomly set each time data is recorded on the recording medium.

In one embodiment of the invention, at least a portion of the fourth synchronization code sequence is overwritten by the first synchronization code sequence recorded when additional data is recorded on the recording medium.

According to still another aspect of the invention, a reproduction apparatus for reproducing information recorded on a recording medium having a recording area is provided. The recording area includes a first area and a second area. The first area includes a frame area. The frame area includes an area in which a second synchronization code sequence and at least a portion of data are recorded. The second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are recorded. The reproduction apparatus includes a section for reproducing the third synchronization code sequence; a section for reproducing the fourth synchronization code sequence; a section for reproducing the second synchronization code sequence; and a section for reproducing the at least a portion of the data.

In one embodiment of the invention, the second synchronization code sequence represents the start of the is frame area, the third synchronization code sequence represents the start of the second area, and at least a portion of the fourth synchronization code sequence is used for stably reproducing the data.

In one embodiment of the invention, at least a portion of the first synchronization code sequence is used for stably reproducing data.

In one embodiment of the invention, the third area includes an area in which a fifth synchronization code sequence is recorded.

In one embodiment of the invention, the fifth synchronization code sequence is used for specifying the start of the first area rearward thereto.

In one embodiment of the invention, a length of the fourth synchronization code sequence is randomly set each time data is recorded on the recording medium.

In one embodiment of the invention, a length of the first synchronization code sequence is randomly set each time data is recorded on the recording medium.

According to still another aspect of the invention, a recording medium includes a rewritable recording area for recording data; and a recording area exclusively used for reproduction, which has user data and specific purpose data different from the user data recorded therein. The rewritable recording area includes a first area and a second area. The first area includes a frame area. The frame area includes an area in which a second synchronization code sequence and at least a portion of data are to be recorded. The second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are to be recorded. The recording area exclusively used for reproduction includes a plurality of further frame areas, each of which includes, recorded therein, a further second synchronization code sequence for identifying the start of the respective further frame area and at least a portion of the user data, and an area having a further third synchronization code sequence and the specific purpose data recorded therein. The further third synchronization code sequence identifies the start of the specific purpose data.

According to still another aspect of the invention, a method for reproducing specific purpose data recorded on a recording medium is provided. The recording medium includes a rewritable recording area for recording data, and a recording area exclusively used for reproduction, which has user data and specific purpose data different from the user data recorded therein. The rewritable recording area includes a first area and a second area. The first area includes a frame area. The frame area includes an area in which a second synchronization code sequence and at least a portion of data are to be recorded. The second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are to be recorded. The recording area exclusively used for reproduction includes a plurality of further frame areas, each of which includes, recorded therein, a further second synchronization code sequence for identifying the start of the respective further frame area and at least a portion of the user data, and an area having a further third synchronization code sequence and the specific purpose data recorded therein. The further third synchronization code sequence identifies the start of the specific purpose data. The method includes the steps of detecting the further third synchronization code sequence, and reproducing the specific purpose data in response to the detection of the further third synchronization code sequence.

According to still another aspect of the invention, a reproduction apparatus for reproducing specific purpose data recorded on a recording medium is provided. The recording medium includes a rewritable recording area for recording data, and a recording area exclusively used for reproduction, which has user data and specific purpose data different from the user data recorded therein. The rewritable recording area includes a first area and a second area. The first area includes a frame area. The frame area includes an area in which a second synchronization code sequence and at least a portion of data are to be recorded. The second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence are to be recorded. The recording area exclusively used for reproduction includes a plurality of further frame areas, each of which includes, recorded therein, a further second synchronization code sequence for identifying the start of the respective further frame area and at least a portion of the user data, and an area having a further third synchronization code sequence and the specific purpose data recorded therein. The further third synchronization code sequence identifies the start of the specific purpose data. The reproduction apparatus includes a detection section for detecting the further third synchronization code sequence, and a reproduction section for reproducing the specific purpose data in response to the detection of the further third synchronization code sequence.

According to still another aspect of the invention, a recording medium includes a recording area exclusively used for reproduction, which has user data and specific purpose data different from the user data recorded therein. The recording area exclusively used for reproduction includes a plurality of frame areas, each of which includes, recorded therein, a second synchronization code sequence for identifying the start of the respective frame area and at least a portion of the user data, and an area having a third synchronization code sequence and the specific purpose data recorded therein. The third synchronization code sequence identifies the start of the specific purpose data.

According to still another aspect of the invention, a method for reproducing specific purpose data recorded on a recording medium is provided. The recording medium includes a recording area exclusively used for reproduction, which has user data and specific purpose data different from the user data recorded therein. The recording area exclusively used for reproduction includes a plurality of frame areas, each of which includes, recorded therein, a second synchronization code sequence for identifying the start of the respective frame area and at least a portion of the user data, and an area having a third synchronization code sequence and the specific purpose data recorded therein. The third synchronization code sequence identifies the start of the specific purpose data. The method includes the steps of detecting the third synchronization code sequence, and reproducing the specific purpose data in response to the detection of the third synchronization code sequence.

According to still another aspect of the invention, a reproduction apparatus for reproducing specific purpose data recorded on a recording medium is provided. The recording medium includes a recording area exclusively used for reproduction, which has user data and specific purpose data different from the user data recorded therein. The recording area exclusively used for reproduction includes a plurality of frame areas, each of which includes, recorded therein, a second synchronization code sequence for identifying the start of the respective frame area and at least a portion of the user data, and an area having a third synchronization code sequence and the specific purpose data recorded therein. The third synchronization code sequence identifies the start of the specific purpose data. The reproduction apparatus includes a detection section for detecting the third synchronization code sequence, and a reproduction section for reproducing the specific purpose data in response to the detection of the third synchronization code sequence.

According to still another aspect of the invention, a recording apparatus for additionally recording information on a recording medium having information recorded thereon or for overwriting information recorded on the recording medium is provided. The recording medium includes at least one second data unit, each of the at least one second data unit includes a prescribed number of first data units, each of the prescribed number of first data units includes a plurality of frame areas having a prescribed byte length, a second synchronization code sequence is recorded at the start of at least one frame area among the plurality of frame areas, the recording medium further includes at least one first frame area for each second data unit, and a third synchronization code sequence is recorded at the start of each of the at least one first frame area. The recording apparatus includes a first detection section for detecting the second synchronization code sequence from the second data unit; a third detection section for detecting the third synchronization code sequence from the second data unit; and a recording beginning timing determination section for determining a timing for beginning the additional recording or the overwriting, using a detection result obtained by the first detection section and/or a detection result obtained by the third detection section.

According to still another aspect of the invention, a reproduction apparatus for reading information from a recording medium having information recorded thereon is provided. The recording medium includes at least one second data unit, each of the at least one second data unit includes a prescribed number of first data units, each of the prescribed number of first data units includes a plurality of frame areas having a prescribed byte length, a second synchronization code sequence is recorded at the start of at least one frame area among the plurality of frame areas, the recording medium further includes at least one first frame area for each second data unit, and a third synchronization code sequence is recorded at the start of each of the at least one first frame area. The reproduction apparatus includes a level-slicing section for generating level-sliced data by level-slicing a reading signal from the recording medium; a first detection section for detecting the second synchronization code sequence from the level-sliced data level-sliced by the level-slicing section; a third detection section for detecting the third synchronization code sequence from the level-sliced data; and a level-slicing mode switching section for switching the mode of level-slicing of the level-slicing section at a prescribed position in the at least one first frame area, using a detection result of the first synchronization code sequence obtained by the first detection section from a second data unit, which is located forward with respect to a second data unit from which the information is to be read; and/or a detection result of the third synchronization code sequence obtained by the third detection section from a second data unit, which is located forward with respect to a second data unit from which the information is to be read.

According to still another aspect of the invention, a reproduction apparatus for reading information from a recording medium having information recorded thereon is provided. The recording medium includes at least one second data unit, each of the at least one second data unit includes a prescribed number of first data units, each of the prescribed number of first data units includes a plurality of frame areas having a prescribed byte length, a second synchronization code sequence is recorded at the start of at least one frame area among the plurality of frame areas, the recording medium further includes at least one first frame area for each second data unit, and a third synchronization code sequence is recorded at the start of each of the at least one first frame area. The reproduction apparatus includes a clock generation section for generating a bit synchronization clock using a signal read from the recording medium; a first detection section for detecting the second synchronization code sequence using the bit synchronization clock; a third detection section for detecting the third synchronization code sequence using the bit synchronization clock; and a clock reproduction mode switching section for switching the mode of clock reproduction of the clock generation section at a prescribed position in the at least one first frame area, using a detection result of the first synchronization code sequence obtained by the first detection section from a second data unit, which is located forward with respect to a second data unit from which the information is to be read; and/or a detection result of the third synchronization code sequence obtained by the third detection section from a second data unit, which is located forward with respect to a second data unit from which the information is to be read.

According to still another aspect of the invention, a recording apparatus for additionally recording information on a recording medium having information recorded thereon or for overwriting information recorded on the recording medium is provided. The recording medium includes at least one second data unit, each of the at least one second data unit includes a prescribed number of first data units, each of the prescribed number of first data units includes a plurality of frame areas having a prescribed byte length, a second synchronization code sequence is recorded at the start of at least one frame area among the plurality of frame areas, the recording medium further includes at least one first frame area for each second data unit, a third synchronization code sequence is recorded at the start of each of the at least one first frame area, and a fifth synchronization code sequence is recorded at the end of each of the at least one first frame area. The recording apparatus includes a first detection section for detecting the second synchronization code sequence from the second data unit; a third detection section for detecting the third synchronization code sequence from the second data unit; a fourth detection section for detecting the fifth synchronization code sequence from the second data unit; and a recording beginning timing determination section for determining a timing for beginning the additional recording or the overwriting, using at least one of a detection result obtained by the first detection section, a detection result obtained by the third detection section, and a detection result obtained by the fourth detection section.

According to still another aspect of the invention, a reproduction apparatus for reading information from a recording medium having information recorded thereon is provided. The recording medium includes at least one second data unit, each of the at least one second data unit includes a prescribed number of first data units, each of the prescribed number of first data units includes a plurality of frame areas having a prescribed byte length, a second synchronization code sequence is recorded at the start of at least one frame area among the plurality of frame areas, the recording medium further includes at least one first frame area for each second data unit, a third synchronization code sequence is recorded at the start of each of the at least one first frame area, and a fifth synchronization code sequence is recorded at the end of each of the at least one first frame area. The reproduction apparatus includes a first detection section for detecting the second synchronization code sequence; a third detection section for detecting the third synchronization code sequence; a fourth detection section for detecting the fifth synchronization code sequence; and a reproduction beginning timing determination section for determining a timing for beginning the reproduction, using at least one of a detection result of the first synchronization code sequence obtained by the first detection section from a second data unit, which is located forward with respect to a second data unit from which the information is to be read; a detection result of the third synchronization code sequence obtained by the third detection section from a second data unit, which is located forward with respect to a second data unit from which the information is to be read; and a detection result of the fourth synchronization code sequence obtained by the fourth detection section from a the second data unit, which is located forward with respect to a second data unit from which the information is to be read.

According to still another aspect of the invention, a reproduction apparatus for reading information from a recording medium having information recorded thereon is provided. The recording medium includes at least one second data unit, each of the at least one second data unit includes a prescribed number of first data units, each of the prescribed number of first data units includes a plurality of frame areas having a prescribed byte length, a second synchronization code sequence is recorded at the start of at least one frame area among the plurality of frame areas, the recording medium further includes at least one first frame area for each second data unit, a third synchronization code sequence is recorded at the start of each of the at least one first frame area, and a fifth synchronization code sequence is recorded at the end of each of the at least one first frame area. The reproduction apparatus includes a level-slicing section for generating level-sliced data by level-slicing a reading signal from the recording medium; a first detection section for detecting the second synchronization code sequence from the level-sliced data level-sliced by the level-slicing section; a third detection section for detecting the third synchronization code sequence from the level-sliced data; a fourth detection section for detecting the fifth synchronization code sequence from the level-sliced data; and a level-slicing mode switching section for switching the mode of level-slicing of the level-slicing section at a prescribed position in the at least one first frame area, using at least one of a detection result of the first synchronization code sequence obtained by the first detection section from a second data unit, which is located forward with respect to a second data unit from which the information is to be read; a detection result of the third synchronization code sequence obtained by the third detection section from a second data unit, which is located forward with respect to a second data unit from which the information is to be read; and a detection result of the fourth synchronization code sequence obtained by the fourth detection section from a second data unit, which is located forward with respect to a second data unit from which the information is to be read.

According to still another aspect of the invention, a reproduction apparatus for reading information from a recording medium having information recorded thereon is provided. The recording medium includes at least one second data unit, each of the at least one second data unit includes a prescribed number of first data units, each of the prescribed number of first data units includes a plurality of frame areas having a prescribed byte length, a second synchronization code sequence is recorded at the start of at least one frame area among the plurality of frame areas, the recording medium further includes at least one first frame area for each second data unit, a third synchronization code sequence is recorded at the start of each of the at least one first frame area, and a fifth synchronization code sequence is recorded at the end of each of the at least one first frame area. The reproduction apparatus includes a clock generation section for generating a bit synchronization clock using a signal read from the recording medium; a first detection section for detecting the second synchronization code sequence using the bit synchronization clock; a third detection section for detecting the third synchronization code sequence using the bit synchronization clock; a fourth detection section for detecting the fifth synchronization code sequence using the bit synchronization clock; and a reproduction mode switching section for switching the mode of clock reproduction of the clock generation section at a prescribed position in the at least one first frame area, using at least one of a detection result of the first synchronization code sequence obtained by the first detection section from a second data unit, which is located forward with respect to a second data unit from which the information is to be read; a detection result of the third synchronization code sequence obtained by the third detection section from a second data unit, which is located forward with respect to a second data unit from which the information is to be read; and a detection result of the fourth synchronization code sequence obtained by the fourth detection section from a second data unit, which is located forward with respect to a second data unit from which the information is to be read.

Hereinafter, a function of the present invention will be described.

In a recording medium according to the present invention, a recording area includes a first area and a second area. The first area includes a frame area. In the frame area, a second synchronization code sequence and at least a portion of data are recorded. The second area includes an area in which a third synchronization code sequence and a fourth synchronization code sequence area to be recorded. On such a recording medium, additional data recording (linking) can be begun, regarding a position in the fourth synchronization code sequence as the beginning position. Thus, additional data recording is not performed in the frame area in which data is recorded. Therefore, data recording and reproduction can be stably performed even at the beginning position and the termination position of the data recording.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top view of a recordable optical disc medium (recording medium) 101 according to a first example of the present invention.

FIG. 2 shows a data format of a data blocks 103 of the optical disc medium 101 .

FIG. 3 shows an example of a pattern to be recorded in a first synchronization area PA (PA pattern), which is especially preferable in the first example of the present invention.

FIG. 4 shows an example of a pattern to be recorded in a second synchronization area VFO (VFO pattern), which is especially preferable in the first example of the present invention.

FIG. 5 shows an exemplary pattern to be recorded in the second synchronization area VFO when Tmin=3 and Tmin=2.

FIG. 6 shows an example of a pattern to be recorded in a third synchronization area SY (SY pattern), which is especially preferable in the first example of the present invention.

FIG. 7A shows an exemplary recording pattern of a beginning position of a usual frame area (i.e., second frame area) in the first example of the present invention.

FIG. 7B shows an exemplary recording pattern of a beginning position of a linking frame area (i.e., first frame area) in the first example of the present invention.

FIG. 8 shows a top view of a recordable optical disc medium (recording medium) 3101 according to a second example of the present invention.

FIG. 9 shows an example of a data format of the optical disc medium 3101 in the second example of the present invention.

FIG. 10 shows an example of synchronization code sequences located at the start of each of the 26 frame areas included in a sector 3103 (FIG. 9).

FIG. 11 shows an example of a pattern preferably used as a synchronization code sequence in the second example of the present invention.

FIG. 12 shows a specific example of an SY 0 pattern and an SY pattern in the second example of the present invention.

FIG. 13 schematically shows code distances between various types of synchronization code sequences (patterns).

FIG. 14 shows an exemplary internal structure of a frame area F 0 .

FIG. 15 shows specific examples of an SY 0 pattern, an SY pattern, and a PA pattern in the second example of the present invention.

FIG. 16 shows other specific examples of an SY 0 pattern, an SY pattern, and a PA pattern in the second example of the present invention.

FIG. 17 shows another example of synchronization code sequences located at the start of each of the 26 frame areas included in a sector 3103 (FIG. 9).

FIGS. 18A through 18D show examples in which synchronization code sequences to be recorded in second frame areas included in one sector are arranged in the order in which the synchronization code sequences are recorded on an optical disc medium.

FIGS. 19A through 19C show examples in which synchronization code sequences to be recorded in second frame areas included in one sector are arranged in the order in which the synchronization code sequences are recorded on an optical disc medium.

FIG. 20 shows still another example in which synchronization code sequences to be recorded in second frame areas included in one sector are arranged in the order in which the synchronization code sequences are recorded on an optical disc medium.

FIG. 21 shows still another example of synchronization code sequences located at the start of each of the 26 frame areas included in a sector 3103 (FIG. 9).

FIGS. 22A through 22C show examples in which synchronization code sequences to be recorded in second frame areas included in one sector are arranged in the order in which the synchronization code sequences are recorded on an optical disc medium, when four types of patterns SY 0 , SY 1 , SY 2 and SY 3 are used.

FIG. 23 shows a top view of a recordable optical disc medium 401 according to a third example of the present invention.

FIG. 24 shows a data format of the data blocks 403 of the optical disc medium 401 (FIG. 23) according to the third example of the present invention.

FIG. 25 shows an example of a pattern to be recorded in the fourth synchronization area PS (PS pattern), which is especially preferable in the third example of the present invention.

FIG. 26 shows another example of a pattern to be recorded in the fourth synchronization area PS (PS pattern), which is especially preferable in the third example of the present invention.

FIG. 27 shows still another example of a pattern to be recorded in the fourth synchronization area PS (PS pattern), which is especially preferable in the third example of the present invention.

FIG. 28 shows still another example of a pattern to be recorded in the fourth synchronization area PS (PS pattern), which is especially preferable in the third example of the present invention.

FIG. 29 shows still another example of a pattern to be recorded in the fourth synchronization area PS (PS pattern), which is especially preferable in the third example of the present invention.

FIG. 30 shows still another example of a pattern to be recorded in the fourth synchronization area PS (PS pattern).

FIG. 31 shows still another example of a pattern to be recorded in the fourth synchronization area PS (PS pattern).

FIG. 32 shows a top view of a recordable optical disc medium 701 according to a fourth example of the present invention.

FIG. 33 shows a data format of data blocks 703 of the optical disc medium 701 according to the fourth example of the present invention.

FIGS. 34A and 34B show other examples of the structure of a first frame area 801 a in the fourth example of the present invention.

FIG. 35 shows a top view of a recordable optical disc medium 1001 according to a fifth example of the present invention.

FIG. 36 shows a data format of data blocks 1003 a included in a reproduction only area 1004 of the optical disc medium 1001 in the fifth example of the present invention.

FIG. 37 shows a data format of data blocks 1003 b included in a rewritable area 1005 of the optical disc medium 1001 in the fifth example of the present invention.

FIG. 38 shows a structure of an information recording apparatus (recording apparatus) 1710 according to a sixth example of the present invention.

FIG. 39 shows an example of an internal structure of a pattern detection and synchronization section 1703 .

FIG. 40 shows another example of an internal structure of a pattern detection and synchronization section 1703 .

FIG. 41 shows the relationship between a data format of the optical disc medium 3101 and the position information.

FIG. 42 shows a structure of an information reproduction apparatus (reproduction apparatus) 1810 according to a seventh example of the present invention.

FIG. 43 shows operating waveforms of various timing signals used for reproducing data recorded in and in the vicinity of the first frame area LF corresponding to the linking frame.

FIG. 44 shows a data format of a linking position and the vicinity thereof of a conventional DVD-RW.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described by way of illustrative examples with reference to the attached drawings. In this specification, the terms “start” and “end” refer to the relative positions along information tracks of an optical disc medium. A position at which data is first recorded or reproduced in a zone along an information track will be referred to as the “start” of the zone (or the start of the data recorded in the zone), and a position at which data is last recorded or reproduced in a zone along an information track will be referred to as the “end” of the zone (or the end of the data recorded in the zone). In the case where there are area A and area B along an information track and data recording or reproduction is performed in area A after area B, area A is expressed as being “rearward” with respect to area B, and area B is expressed as being “forward” with respect to area A. The expression that one area is “rearward” or “forward” with respect to the other area does not necessarily mean that the two areas are adjacent to each other. When area A is rearward with respect to area B and the area A is adjacent to area B, area A is expressed as being an area immediately subsequent to area B.

In this specification, the term “frame area” represents a specific area on an information track of an optical disc medium. In the frame area, a prescribed amount of data and/or a prescribed amount of code sequence is recorded. Data or a code sequence recorded in the frame area is referred to as a “frame”. In this specification, the term “sector” also represents a specific area on an information track of an optical disc medium, and includes a plurality of frame areas mentioned above.

EXAMPLE 1

FIG. 1 shows a top view of a recordable optical disc medium (recording medium) 101 according to a first example of the present invention. On a recording surface of the optical disc medium 101 , a recording track 102 (recording area) is formed in a spiral manner. The recording track 102 is divided into data blocks 103 . In other words, on the recording surface of the optical disc medium 101 , the data blocks 103 are continuously arranged in a circumferential direction to form the information track 102 .

FIG. 2 shows a data format of the data blocks 103 of the optical disc medium 101 . As shown in FIG. 2, each data block 103 includes a first frame area 201 at the start thereof and then a plurality of second frame areas 202 thereafter. The first frame area 201 and the second frame areas 202 form one data block 103 . In FIG. 2, an area shown in the right is rearward to an area shown in the left.

Thus, the information track 102 of the optical disc medium 101 includes a plurality of second frame areas 202 (collectively referred to as a first area) and a first frame area 201 (second area) which are included in one data block.

The first frame area 201 includes a first synchronization area PA at the start thereof and then a second synchronization area VFO thereafter.

The second frame area 202 (frame area) includes a third synchronization area SY at the start thereof and then a data area DATA thereafter. A third synchronization area SY is an area in which an SY pattern (second synchronization code sequence) is to be recorded. A data area DATA is an area in which at least a portion of user data to be recorded in the recording medium is to be recorded. In other words, the second frame area 202 (frame area) includes an area in which an SY pattern (second synchronization code sequence) and at least a portion of the user data are to be recorded.

The role of each area will be described. First, the data area DATA is for recording a data bit stream including user data. The data bit stream includes a parity code used for detecting or correcting a data error when the data is read. The parity code is included in an area other than the user data. The data bit stream is not recorded as binary data itself, but is transformed by a modulation system matching the characteristics of a recording and reproduction signal of the optical disc medium before being recorded.

Here, it is assumed that a post-transformation data bit stream is a code sequence limited to the minimum run (minimum inversion interval) d and the maximum run (maximum inversion interval) k, and the code sequence is obtained by dividing the input data bit stream into blocks each having units of (m×i) bits and then transforming each block of the input data into a code sequence having units of (n×i) bits. In this case, d and k are each a natural number fulfilling d<k, m and n are each a natural number fulfilling m<n, and i is a natural number fulfilling 1≦i≦r. Especially when r=1, this transformation system is referred to as a fixed length code system, and when r≧1 (i can be a plurality of values), this transformation system is referred to as a variable length code system.

When a code sequence is recorded by the NRZ (Non Return to Zero) format, bit “1” of the code sequence corresponds to a recording mark and a zero run “0”s corresponds to a space. In an optical disc medium, recording marks and spaces are distinguished from each other by whether the pits are convex or concave or by a difference in reflectance which is caused by a phase change in a recording layer. When the code sequence is recorded by the NRZI (Non Return to Zero Inverted) format, the recording state, i.e., whether a recording mark is to be recorded or a space is to be recorded, is switched when a “1” bit of the data bit stream occurs. In the case of mark length recording, the inversion interval corresponds to the length of a recording mark or the length of a space.

Assuming that the minimum value of the size of marks which can be formed on a recording layer of an optical disc medium (such a minimum value will be referred to as a “mark unit”) is equal in the NRZ recording and the NRZI recording, the NRZ recording requires 3 mark units in order to record data of a minimum code length (3 bits “100” of a data bit stream), but the NRZI recording requires only one mark unit. Accordingly, when a run length limited code having a minimum inversion interval d=2 is used, the number of bits per unit length of track of the optical disc medium is larger in the case of the NRZI recording than in the case of the NRZ mark recording. Namely, the recording density is higher by the NRZI recording than by the NRZ recording.

In the first example of the present invention, mark length recording is performed using a run length limited code having parameters of d=2, k=10, m=8, n=16, and r=1 for modulation. In other words, the data bit stream recorded in the data area DATA of the optical disc medium 101 (FIG. 1) includes recording marks and recording spaces having a minimum length Tmin=3 bits and a maximum length Tmax=11 bits.

The first synchronization area PA is provided for identifying the start of the first frame area 201 , and preferably has a pattern recorded which does not occur in a data bit stream to be recorded in at least the data area DATA. By recording a pattern in the first synchronization area PA, which does not occur in the data area DATA, the first synchronization area PA can be easily distinguished from the data area DATA when the data bit stream is read.

The second synchronization area VFO is provided for realizing stable operations of data reproduction systems when each data block 103 is read. The data reproduction systems refers to, for example, a section for level-slicing a reproduction signal RF (Radio Frequency) read from the data block 103 and a PLL (Phase Locked Loop) section for extracting a bit synchronization clock from the level-sliced data. In order to realize stable operations of the data reproduction systems, the patterns recorded in the second synchronization area VFO preferably fulfill conditions 1 through 3 given below.

(Condition 1) A sufficient amplitude and a sufficient S/N ratio (Signal to Noise Ratio) of the reproduction signal RF are guaranteed.

(Condition 2) The number of times of recording mark/space switching is sufficient.

(Condition 3) The DSV value (Digital Sum Value) of the pattern is as close to 0 as possible.

Condition 1 is for properly obtaining level-sliced data from the reproduction signal RF. When the amplitude of the reproduction signal RF is too small or the S/N ratio thereof is too low, the signal is not accurately level-sliced or the signal is level-sliced into wrong data due to the influence of the noise of the data reproduction systems.

Condition 2 is for obtaining a bit synchronization clock from the level-sliced data at a high speed and stably. When the clock frequency/phase is locked by the PLL section in the second synchronization area VFO, the information for frequency/phase comparison can be obtained more frequently as the number of times of recording mark/space switching is larger. Thus, the clock frequency/phase can be locked more quickly. When the number of times of recording mark/space switching is too small, the information for frequency/phase comparison cannot be obtained. As a result, clock frequency/phase is locked more slowly or unstably.

Condition 3 is for stably level-slicing the reproduction signal RF. In the case where a DC feedback system (for performing feedback control of slicing level by a DC component of the post-level-slicing data), which is generally used as a level-slicing system, is used, when the DSV value of the pattern significantly fluctuates or disperses, the slicing level significantly fluctuates or significantly shifts from the center of the reproduction signal RF. As a result, the level-sliced data cannot be stably obtained. A DSV value of the pattern which is as close as possible to 0 is preferable to the DC feedback system.

The third synchronization area SY is provided for identifying the start of each second frame area 202 . Like the first synchronization area PA for identifying the start of the first frame area 201 , it is preferable to record a pattern, in the third synchronization area SY, which does not occur in at least a data bit stream to be recorded in the data area DATA. By recording a pattern, in the third synchronization area SY, which does not occur in the data area DATA, the third synchronization area SY can be easily distinguished from the data area DATA when the data bit stream is read.

FIG. 3 shows an example of a pattern to be recorded in the first synchronization area PA (PA pattern), the example being especially preferable in the first example of the present invention. A feature of the PA pattern shown in FIG. 3 is that the pattern includes a recording mark or a space having a length of 14 channel bits (14T), which is a (Tmax+3) channel bit length. In the first example, as described above, the maximum mark/space length Tmax of a data bit stream to be recorded in the data area DATA is 11 channel bits (11T), which is different, by 3 bits, from 14T included in the first synchronization area PA. Even when a 1 channel bit edge shift occurs due to the influence of noise generated during reproduction, and as a result, the 14T mark (or the 14T space) in the first synchronization area shortens to 13 channel bits and the 11T mark (or the 11T space) in the data area DATA lengthens to 12 channel bits, there is still a 1 channel bit difference between the mark (or space) in the first synchronization area and the mark (or space) in the data area DATA. Thus, against an edge shift of about one bit, a sufficient error margin is provided for preventing the 11T pattern in the data area DATA from being incorrectly detected as the pattern in the first synchronization area PA. In this manner, the PA pattern is used for identifying the start of the subsequent VFO pattern.

In the example shown in FIG. 3, a 4T space/mark is located immediately after the 14T mark/space. By using (14T+4T) as the detection pattern when the data in the data block 103 is read, the possibility of incorrect detection can be reduced compared to using only 14T as the detection pattern. By adding (15T+3T) or (13T+5T) to the detection pattern, not only (14T+4T), 14T can be avoided from being undetected even when an edge shift occurs at the rear end of the 14T, and still the possibility of incorrect detection can be kept as low as possible.

Thus, a PA pattern can be easily distinguished from the VFO pattern rearward thereto or any other pattern recorded in the data area DATA. By the reproduction apparatus or the recording apparatus detecting the PA pattern, it becomes possible to determine the termination of the data area DATA in a data block forward with respect to the PA pattern, or to predict the start of the second synchronization area VFO subsequent to the PA pattern or the start of the data block rearward to the second synchronization area VFO. Specific examples in which the PA pattern recorded in the first synchronization area is used for reproduction control or recording control will be described later in sixth and seventh examples. The PA pattern represents the start of the first frame area (second area).

In FIG. 3, the pattern in the first synchronization area PA is represented by the NRZ format as {1001001001000100000000000010001}. By adding, to immediately before (14T+4T), the sequence (3T+3T+3T+4T) fulfilling the run length limitation of d=2 and k=10 (limitation on the zero run, i.e., the number of continuous “0” bits) as in the case of the modulation code, a pattern of having a total of 32 channel bits (i.e., 2 bytes) is formed. It is preferable that the sequence located immediately before 14T fulfills the same run length limitation as that of the modulation code, but the present invention is not limited to this. The pattern of the first synchronization area PA is not limited to one pattern, but can be selected from a plurality of patterns. For example, a plurality of patterns having different zero runs (the number of continuous “0” bits) at the start of the pattern is prepared. From the plurality of patterns, one pattern is selected so that the selected pattern fulfills the same run length limitation as that of the modulation code when being connected to the zero run resulted from the modulation of the immediately preceding byte (final zero run). Alternatively, a plurality of patterns having different DSV values, and one pattern is selected so that the post-selection DSV value is minimum. The post-selection DSV value is a sum of the DSV value of the sequence immediately preceding the selected pattern and the DSV value of the selected pattern.

FIG. 4 shows an example of a pattern to be recorded in the second synchronization area VFO (VFO pattern), the example being especially preferable in the first example of the present invention. A feature of the VFO pattern shown in FIG. 4 is that the pattern includes repeated 4 channel bit recording marks and spaces. The pattern shown in FIG. 4 fulfills conditions 1 through 3 as described above.

The pattern having a single length of 4T guarantees a sufficient amplitude of the reproduction signal RF (condition 1). A pattern which provides the largest number of times of mark/space switching is a pattern having a single length of 3 channel bits (minimum length), but a pattern having a single length of 4T is considered as preferable for the following reason. In the recording and reproduction characteristics of an optical disc medium realizing high density recording, the amplitude of a reproduction signal RF having a minimum length bit is generally significantly shorter than the longer mark/space. Therefore, with the length of 3 channel bits, a reproduction signal RF to be stably level-sliced may not be obtained. Therefore, a pattern having a single length of 4T is considered as preferable in order to fulfill both conditions 1 and 2. Since the pattern having a single length of 4T can have the DSV=0, the pattern also fulfills condition 3.

The pattern to be recorded in the second synchronization area VFO is not limited to a pattern having a single length of 4T. It is preferable to record a pattern fulfilling all the conditions 1 through 3, but the conditions can be provided with priority levels in accordance with the recording and reproduction characteristics of the optical disc medium. For example, in the case of an optical disc medium which provides a sufficient amplitude of a reproduction signal RF (condition 1) with a recording mark or space having a minimum length of 3T, a pattern having repeated 3T recording marks or spaces can be used. Thus, the number of times of mark/space switching can be increased (condition 2) as compared to a pattern having a single length of 4T. In this manner, condition 2 obtains a higher priority level than condition 1, and the data PLL can be locked more quickly. Alternatively, in the case of an optical disc medium which does not provide a sufficient amplitude of a reproduction signal RF even with a pattern having a single length of 4T, a pattern having repeated 5T recording marks or spaces can be used. In this case, condition 1 obtains a higher priority level than condition 2; i.e., although the number of times of mark/space switching is decreased as compared to a pattern having a single length of 4T, the precision of data level-slicing can be improved.

FIG. 5 shows an exemplary pattern to be recorded in the second synchronization area VFO when Tmin=3 and Tmin=2. In the example shown in FIG. 5, when Tmin=3, a pattern having repeated 4T recording marks and spaces is used; and when Tmin=2, a pattern having repeated 3T recording marks and spaces is used.

Thus, a pattern having a single length of (Tmin+1) channel bits provides a sufficient amplitude of a reproduction signal RF and thus fulfills condition 1.

When an 8/16 modulation system is used, Tmin=3 and 1 byte=16 channel bits. Therefore, 4T marks or spaces are repeated 4 times per byte. Since the length of the second synchronization area VFO in the first example is 91 bytes, 4T marks or spaces are repeated 364 times (=91×4).

The 8/16 modulation system is one system for transforming 8 bit binary data into a code word having 16 channel bits. The 8/16 modulation system is disclosed in detail in, for example, Japanese Laid-Open Publication No. 8-31100. In the 8/16 modulation system, a plurality of transformation tables are allocated to 8 bit pre-modulation data, and the transformation tables are switched to transform the 8 bit pre-modulation data into a code so that the post-modulation code sequence has as few low frequency components as possible. The transformation tables are switched so that the conditions of the minimum inversion interval d=2 and the maximum inversion interval k=11 are fulfilled while minimizing the absolute value of the DSV in the code sequence.

FIG. 6 shows an example of a pattern to be recorded in the third synchronization area SY (SY pattern), the example being especially preferable in the first example of the present invention. A feature of the SY pattern shown in FIG. 6 is that the pattern includes a recording mark or a space having a length of 14 channel bits (14T), which is a (Tmax+3) channel bit length. The length of 14T is different by 3 channel bits from the maximum mark/space length Tmax of 11 (11T) of a data bit stream to be recorded in the data area DATA. Therefore, against an edge shift of about one bit, a sufficient error margin is provided for preventing the 11T pattern in the data area DATA from being incorrectly detected as the pattern in the third synchronization area SY, as described above regarding the pattern to be recorded in the first synchronization area PA with reference to FIG. 3. In this manner, the SY pattern is used for identifying (or representing) the start of the second frame area 202 (frame area).

A method for recognizing an absolute position (hereinafter, referred to as an “address”) in the information track 102 from the optical disc medium 101 in the first example of the present invention will be described. In order to record data at a prescribed address on a recordable optical disc medium, a recording apparatus needs to read information on the prescribed address before data recording and search for the position at which the data is to be recorded. In order to obtain address information in an area where no data has been recorded, the address information needs to be pre-formatted. According to an exemplary pre-formatting technique, the address information is represented by pre-pits defined using the convex and concave portions at the recording surface, or the address information is represented by the manner of meandering in which grooves for forming the information track 102 are formed.

In the present invention, any technique can be used for obtaining the address information in the optical disc medium 101 . Unless specifically described in this specification, each data block is given inherent address information, and the address information of each data block is obtained by accessing a prescribed portion of the information track 102 .

With reference to FIG. 2 again, a method for recording data on the optical disc medium 101 (FIG. 1) having the above-described data format will be described. On the optical disc medium 101 , data is recorded using the data block 103 as a minimum unit. A series of data recording is begun and terminated in the second synchronization area VFO of the first frame area 201 . Herein, the first frame area 201 including a position at which data is additionally recorded is referred to as a “linking frame area”.

When additional data is recorded from the termination position of a series of data recording, the beginning position of the additional data recording and the termination position of the additional data recording are determined so that the relationship S≦E is always fulfilled with the following conditions. The beginning position of the additional data recording is an Sth byte of the second synchronization area VFO of the first frame area 201 , which is a linking frame area (“S” is a rational number which is smaller than the number of bytes representing the length of the second synchronization area VFO). The termination position of the additional data recording is an Eth byte of the second synchronization area VFO (“E” is a rational number which is smaller than the number of bytes representing the length of the second synchronization area VFO). By thus determining the beginning position and termination position of the additional data recording, the portion in which the data is additionally recorded includes no area which is left without any pattern (VFO pattern) recorded. When an area is left without any VFO pattern recorded, there is an undesirable possibility that the reproduction systems are not accurately locked.

The difference between S and E is preferably determined in consideration of various fluctuation error factors of a driving apparatus. In an ideal state where the fluctuation error is zero, the number of bytes given by (S−E) is recorded in the same area when recording of data is terminated and also when recording is begun. Therefore, the data previously recorded in this area is overwritten by data currently recorded. Accordingly, it is preferable to set the number of bytes given by (S−E) to be the upper limit of the fluctuation error factors or higher. In this case, even when the fluctuation error is maximum, additional data recording can be performed without leaving any area without any VFO pattern recorded.

When the optical disc medium 101 is a rewritable optical disc medium formed using a phase change recording material or the like, repeating additional data recording a great number of times at the same position may cause degradation of the recording layer. In order to minimize the degradation of the recording layer and still improve overwritability (increase the number of times data can be recorded on the same track), the beginning position and the termination position of data recording can be randomly changed within a prescribed range each time data is recorded. In such a case, the length of the first frame area 201 is not necessarily a fixed byte length. The reason is that the length of the second synchronization area VFO varies due to the change of the beginning position and the termination position of data recording. How much the beginning position and the termination position of data recording should be changed is preferably determined in consideration of the length of the second synchronization area VFO, the time period required for locking the reproduction systems, the degradation characteristics of the recording layer, and the like.

According to the present invention, the frame area in which additional data recording is begun, i.e., the linking frame area, is the first frame area 201 which does not include a data area DATA. Therefore, even additional data recording is not performed discontinuously. Accordingly, the undesirable possibility is eliminated that additionally recorded data is not read and as a result, data recorded in one frame area is lost. As compared to the conventional optical disc medium in which linking is performed in a data area DATA (additional data is recorded in the data area DATA), the reading error margin in the additionally recorded data can be significantly improved. As a result, data recording and reproduction can be stably performed even at the beginning position and the termination position of data recording.

As can be appreciated from FIG. 2, a recording apparatus records data on the optical disc medium 101 as follows. First, a record start VFO portion 2102 (first synchronization code sequence provided for stably reproducing data) shown in FIG. 2 is first recorded in the first frame area 201 (third area) on the information track 102 , and then the at least one second frame area 202 is recorded. Accordingly, the area (first area) in which at least one second frame is rearward to the first frame area 201 (third area). The first frame area 201 (third area) includes an area in which a record start VFO portion 2102 (first synchronization code sequence) is to be recorded.

The second frame area 202 includes the SY pattern (second synchronization code sequence) for identifying the start of the second frame area 202 and at least a portion of the data to be recorded (data to be recorded in the data area DATA). In the case where the data to be recorded on the optical disc medium 101 corresponds to a plurality of data blocks 103 , the first frame area 201 is provided at the border of two adjacent data blocks 103 so that the PA pattern and the VFO pattern are recorded. When the data recording on the optical disc medium 101 is terminated, a PA pattern (third synchronization code sequence) is recorded after the at least one second frame area 202 . Then, a record finish VFO portion 2101 (fourth synchronization code sequence provided for stably reproducing data) shown in FIG. 2 is recorded. The PA pattern and the record finish VFO portion 2101 are recorded in a first frame area 201 (second area). This first frame area 201 (second area) is different from the first frame area 201 (third area) in which the record start VFO portion 2102 was recorded when the recording was begun, and is provided rearward to the first area. The first frame area 201 (second area) includes an area in which the PA pattern (third synchronization code sequence) and the record finish VFO portion 2101 (fourth area) are to be recorded.

In order to randomly change the beginning position of the additional recording, the length of the record start VFO portion 2102 (the first synchronization code sequence provided for stably reproducing data) shown in FIG. 2 in the VFO pattern may be randomly set. In order to randomly change the termination position of the additional recording, the length of the record finish VFO portion 2101 (the fourth synchronization code sequence provided for stably reproducing data) shown in FIG. 2 in the VFO pattern may be randomly set. When the beginning position or the termination position of recording is randomly changed, it is not indispensable that the length of the record finish VFO portion 2101 or the record start VFO portion 2102 is randomly changed. As described above, the position at which data is to be recorded can be obtained by pre-formatted address information, regardless of whether the data has already been recorded or not. Accordingly, the beginning position or the termination position of recording can be randomly changed with respect to the absolute position on the optical disc medium 101 which is obtained by reproducing the address information. In this case, it is preferable that the end of the record finish VFO portion 2101 is positioned rearward with respect to the start of the record start VFO portion 2102 .

As described above, the beginning position and the termination position of additional data recording are set so that the relationship S≦E is always fulfilled. Therefore, at least a portion of the record finish VFO portion 2101 (the fourth synchronization code sequence already recorded on the optical disc medium 101 is overwritten by the record start VFO portion 2102 (the first synchronization code sequence of the VFO pattern recorded when additional data recording is performed.

As described above, in the first example of the present invention, a data block which is the minimum unit of recording and reproduction includes a first frame area at the start and a frame area located subsequent to the first frame area. The first frame area includes a first synchronization area (PA) and a second synchronization area (VFO). The second frame area includes a third synchronization area (SY) and a data area (DATA) for recording data. Due to such a structure, the beginning/termination of data recording (linking) can be performed in the second synchronization area (VFO) in the first frame area (linking frame area). Various fluctuation factors in the data recording can be absorbed within the second synchronization area VFO, and thus stable data recording and reproduction can always be provided. Overhead is kept small at slightly more than one frame per data block.

According to the present invention, it is not necessary to precisely set the positioning accuracy to less than one channel bit. Accordingly, a driving apparatus can be designed with a simple structure, thus reducing the production cost of the driving apparatus.

FIG. 7A shows an exemplary recording pattern of a beginning position of a usual frame area (i.e., the second frame area 202 ) and FIG. 7B shows an exemplary recording pattern of a beginning position of a linking frame area (i.e., the first frame area 201 ) both in the first example of the present invention. The examples shown in FIGS. 7A and 7B are obtained when a run length limited code having parameters of d=1, k=9, and n/m=1.5 is used for modulation of the data area.

In FIG. 7A, the beginning position of the usual frame area refers to the start of the second frame area 202 (FIG. 2) in conformity of the data format of the first example of the present invention. At the start of the second frame area 202 , the third synchronization area SY is provided having a length of two bytes (i.e., 24 channel bits). The data area DATA is provided from the third byte. In the SY pattern of the third synchronization area SY, the underlined partial pattern “10000000000001001” corresponds to the pattern of (Tmax+3)·(Tmin+1) in a run length limited code having parameters of d=1 and k=9. “YYYYYY” at the start of the SY pattern (left of FIG. 7A) is preferably determined so as to fulfill the run length limitation of d=1 and k=9 in consideration of the connection with the immediately preceding data area DATA.

In FIG. 7B, the beginning position of the linking frame area refers to the start of the first frame area 201 in conformity of the data format of the first example of the present invention. At the start of the first frame area 201 , the first synchronization area PA is provided having a length of two bytes (i.e., 24 channel bits). The second synchronization area VFO is provided from the third byte. The underlined partial pattern “10000000000001000001” in the first synchronization area PA and the second synchronization area VFO corresponds to the pattern of (Tmax+3)·(Tmin+4) in a run length limited code having parameters of d=1 and k=9. The unique pattern of the linking frame area, i.e., the pattern of ((Tmax+3)·(Tmin+4)) and the unique pattern of the usual frame area, i.e., the pattern of ((Tmax+3)·(Tmin+1)) have the relationship that the length from the beginning position to the beginning position of (Tmax+3) is the same (8 channel bits) and the termination position of (Tmax+3) is the same.

In FIG. 7B, “YYYYYY” at the start is preferably determined so as to fulfill the run length limitation of d=1 and k=9 in consideration of the connection with the immediately preceding data area DATA. “YYYYYY” in FIG. 7B can be exactly the same as the “YYYYYY” in the SY pattern in FIG. 7A. Even in this case, the code distance between the PA pattern and the SY pattern can be still 3 since the pattern immediately after (Tmax+3) in the SY pattern is (Tmin+1) whereas the pattern immediately after (Tmax+3) in the PA pattern is (Tmin+4).

Accordingly, even when, for example, the SY pattern and the PA pattern each have a length of 2 bytes and thus many types patterns cannot be formed when (Tmax+3) is included in the 2-byte length, the number of types of patterns which can be distinguished by the length of the pattern immediately after (Tmax+3) can be increased. Thus, the degree of freedom of use of patterns is increased.

When the degree of freedom of use of patterns is increased, it is also possible to increase the number of types of patterns usable as an SY pattern or a PA pattern while maintaining the code distance at 2 or more, or conversely to increase the code distance to 3 or more while maintaining the number of types of patterns usable as an SY pattern or a PA pattern.

The byte length of the first frame area 201 and the second frame area 202 , and the number of the second frame areas 202 in each data block 103 in this example will be described.

It is preferable that the byte length of the first frame area 201 and the byte length of the second frame area 202 are preferably substantially identical to each other, or the byte length of one of the areas is substantially integral times the byte length of the other. By making the byte length of one of the first frame area 201 and the second frame area 202 substantially integral times the byte length of the other, it becomes possible to use the same circuits (timing generation circuit and the like) of a recording/reproduction apparatus, for example, for data generation in both of the frame areas when recording data and for frame interpolation in both of the frame areas when reproducing data. Thus, the scale of the recording/reproduction apparatus can be reduced, and thus the cost can be reduced. In the first example of the present invention, the first frame area 201 and the second frame area 202 both have a length of 93 bytes. Alternatively, the byte length of the first frame area 201 can be about an integer times the byte length of the second frame area 202 .

In the case where the first frame area 201 has a length of 93 bytes, the pattern shown in FIG. 3 is located in the first synchronization area PA, and the pattern shown in FIG. 4 is located in the second synchronization area VFO, the first synchronization area PA has a length of 2 bytes and the second synchronization area VFO has a length of 91 bytes. In this case, the pattern in the second synchronization area VFO includes 4T recording marks or spaces repeated 182 times.

In the first example of the present invention, the number of the second frame areas 202 in each data block 103 is 208 . This number determines the frequency at which the first frame area 201 is inserted and the data size of the data block 103 . When this number is large, the overhead (redundant portion of the format) caused by the first frame area 201 which does not have the data area DATA is small and thus the effect of increasing the storage capacity of the optical disc medium 101 is obtained. However, such a large number is disadvantageous when handling small size data since the data size of the data block 103 is increased.

As shown in FIG. 2, an ECC block includes 4 continuous data blocks 103 . In this case, the number of the second frame areas 202 per ECC block is 208×4=832. The ECC block is defined as a coding unit of an error correction code. For example, in the case where a known product code is formed using a known Reed-Solomon code two-dimensionally as an error correction code, the ECC block is the unit of the product code. Where the third synchronization area SY has a length of 2 bytes, the total size of all the data areas DATA per ECC block is 91×832=75712 bytes. In the first example of the present invention, 65536 bytes of the 75712 bytes are used for user data, and the remaining bytes are allocated to redundant data such as an error correction, block identification ID and the like.

By forming an ECC block forming an error correction code of an integer number of data blocks, each of which is the minimum unit of a series of data recording, an effect of facilitating the management of the recording data in a driving apparatus (recording apparatus or reproduction apparatus) is provided. In the first example of the present invention, 1 ECC block=4 data blocks, but the present invention is not limited to this. A similar effect is provided even when the number of data blocks included in one ECC block is changed. For example, 1 ECC block can include one data block. However, in the first example, the number of the data blocks included in one ECC block inevitably has an upper limit since the leading frame area of each data block is the first frame area 201 (i.e., redundant data) which does not include a data area DATA. The number of data blocks included in one ECC block is preferably determined to be a value suitable to the use of the optical disc apparatus 101 , the performance of the driving apparatus and the like in consideration of the error correction capability of the driving apparatus and the overhead.

The pattern recorded in the third synchronization area SY need not be identical regardless of the second frame area 202 . For example, the second frame area 202 subsequent to the first frame area 201 in each data block 103 can have a specific pattern which is different from the pattern recorded in the other second frame area 202 . In this manner, the above-mentioned specific pattern can be identified by the driving apparatus. Therefore, the first data area DATA in each data block 103 can be detected at a higher accuracy, which raises the reliability of the driving apparatus. In a second example described below, the SY pattern recorded at the start of one of a plurality of second frame areas 202 is different from the SY pattern recorded at the start of the other second frame areas 202 .

In the first example, the first frame area (first area and third area) includes a first synchronization area PA and a second synchronization area VFO, but can include other synchronization code sequences or data bit streams.

EXAMPLE 2

FIG. 8 shows a top view of a recordable optical disc medium (recording medium) 3101 according to a second example of the present invention. As shown in FIG. 8, on a recording surface of the optical disc medium 3101 , a recording track 3102 (recording area) is formed in a spiral manner. The recording track 3102 is divided into data blocks 301 . In other words, on the recording surface of the optical disc medium 3101 , the data blocks 301 are continuously arranged in a circumferential direction to form the information track 3102 .

FIG. 9 shows an example of a data format of the optical disc medium 3101 in the second example of the present invention. In FIG. 9, identical elements as those described above with reference to FIG. 2 bear identical reference numeral therewith and will not be described in detail. In FIG. 9, an area shown in the right is rearward to an area shown in the left.

As shown in FIG. 9, each data block 301 includes a first frame area 201 and 8 sectors 3103 . Four data blocks 301 form one ECC block 302 . Accordingly, one ECC block includes 32 sectors.

A plurality of second frame areas included in each data block 301 are grouped into a plurality of sectors 3103 each including 26 second frame areas.

Each sector 3103 (fourth area) includes 26 second frame areas. Each frame area has a length of 93 bytes. The frame area positioned at the start of the sector 3103 is represented by reference numeral F 0 , and the remaining 25 frame areas are represented by reference numerals F 1 , F 2 , . . . F 24 and F 25 .

The frame area F 0 includes a synchronization area SY 0 (third synchronization area) at the start thereof and then a data area DATA subsequent thereto. The frame areas F 1 through F 25 each include a synchronization area SY (the third synchronization area) at the start thereof and then a data area DATA subsequent thereto. The synchronization area SY 0 and the synchronization area SY both have a length of 2 bytes. Accordingly, the length of each of all the data areas DATA in the frame area F 0 and the frame areas F 1 through F 25 is 91 bytes.

The total number of bytes of all the data areas DATA in each sector 3103 is 91×26=2366 bytes. User data to be recorded in each sector has a length of 2048 bytes, and redundant data such as address information for identifying the recording position of the data, a parity code used for detecting or correcting an error and the like has a length of 318 bytes. The total of the user data and the redundant data is 2366 bytes.

The data bit stream to be recorded in the data area DATA is not recorded as binary data itself, but is transformed by a modulation system matching the characteristics of a recording and reproduction signal of the optical disc medium before being recorded. It is assumed here that NRZI recording is performed using an 8/16 modulation system. The data bit stream to be recorded in each data area DATA has a length of 91×16=1456 channel bits, and includes recording marks or spaces having a minimum length Tmin of 3 bits and a maximum length Tmax of 11 bits.

The synchronization area SY 0 is provided for identifying the start of the frame area F 0 , and preferably has a pattern recorded which does not occur in at least a data bit stream to be recorded in the data area DATA. By recording a pattern, in the synchronization area SY 0 , which does not occur in the data area DATA, the synchronization area SY 0 can be easily distinguished from the data area DATA when the data bit stream is read.

Each synchronization area SY is provided for identifying the start of the respective second frame of the second frame areas F 1 through F 25 . Each synchronization area SY preferably has a pattern recorded which does not occur in at least a data bit stream to be recorded in the data area DATA, like the synchronization area SY 0 in the frame area F 0 . By recording a pattern, in the synchronization area SY, which does not occur in the data area DATA, the synchronization area SY can be easily distinguished from the data area DATA when the data bit stream is read. Hereinafter, the pattern recorded in the synchronization area SY or the synchronization area SY 0 will also be referred to as a “synchronization code sequence”.

FIG. 10 shows an example of synchronization code sequences located at the start of each of the 26 frame areas included in the sector 3103 (FIG. 9). The synchronization code sequences are classified into two types, the SY 0 pattern and the SY pattern. The SY pattern is located in the second through the 26th frame areas.

FIG. 11 shows an example of a pattern preferably used as a synchronization code sequence in the second example of the present invention. The pattern shown in FIG. 11 includes a recording mark or space having a length of 14 channel bits (14T), which is a (Tmax+3) channel bit length. In the second example, as described above, the maximum mark/space length Tmax of a data bit stream to be recorded in the data area DATA is 11 channel bits (11T), which is different, by 3 bits, from 14T included in the synchronization code sequence. Even when a 1 channel bit edge shift occurs due to the influence of noise generated during reproduction, and as a result, the 14T mark (or the 14T space) in the synchronization code sequence shortens to 13 channel bits and the 11T mark (or the 11T space) in the data area DATA lengthens to 12 channel bits, there is still a 1 channel bit difference between the mark (or space) in the synchronization code sequence and the mark (or space) in the data area DATA. Thus, against an edge shift of about one bit, a sufficient error margin is provided for preventing the 11T pattern in the data area DATA from being incorrectly detected as the pattern in the synchronization code sequence.

In order to distinguish the SY 0 pattern and the SY pattern from each other, it is preferable to provide a code distance therebetween of 2 or more. Herein, the code distance refers to the number of bits which are different between the two data bit streams. In the case of the NRZ recording, the code distance is given by the data bit stream in the NRZ representation. In the case of the NRZI recording, the code distance is given by the data bit stream in the NRZI representation. When the code distance between the SY 0 pattern and the SY pattern is equal to or greater than 2, one pattern is not incorrectly identified as the other pattern even when a 1 bit shift error occurs in reading one of the patterns.

When the code distance is equal to or greater than 3, the identification capability is further improved. For example, with the code distance of 2, when the SY 0 pattern and the SY pattern shift by one bit in the direction of approaching each other, the two patterns become identical and cannot be distinguished from each other. With the code distance equal to or greater than 3, by contrast, when the SY 0 pattern and the SY pattern shift by one bit in the direction of approaching each other, there is still a difference equal to or greater than one bit, and the two patterns can be distinguished from each other. Therefore, the SY 0 pattern and the SY pattern can always be distinguished from each other while keeping the tolerance of a 1 bit error. A plurality of types of SY patterns can be used as long as the code distance between the SY 0 pattern and each of the SY patterns is equal to or greater than 2.

FIG. 12 shows a specific example of the SY 0 pattern and the SY pattern in the second example of the present invention. The SY 0 pattern and the SY pattern both have a length of 2 bytes (i.e., 32 channel bits) and both include a common unique pattern of (14T+4T). One advantage of matching the length of the two patterns and causing the two patterns to include a common unique pattern is that a device for detecting the patterns can be simplified since the device can include a common pattern detection system for the two patterns.

The unique pattern corresponds to the pattern of (Tmax+3) (Tmin+1) in the 8/16 modulation system. The detection capability of the pattern itself is improved by locating a space (or mark) having (Tmin+1) bits immediately after a mark (or space) having (Tmax+3) bits