DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0048] FIG. 1 is a perspective view of a high luminance light emitting element according to a first embodiment of the present invention, FIG. 2 is a sectional view taken along a line II-II of FIG. 1 .

[0049] The high luminance light emitting element 20 comprises a base 21 having a rectangular parallelepiped and made of a metal core material of copper alloy having high thermal conductivity, and a wire plate 22 secured to the upper surface of the base by adhesives 22 a opposite an underside heat radiation surface 21 a. The wire plate is prepreg and has an insulation quality.

[0050] A pair of conductive patterns 23 and 24 are formed on the wire plate 22 by copper foil. The conductive patterns 23 and 24 have terminal portions 23 a, 23 b, 24 a and 24 b at respective corners as connecting surfaces. The terminal portions 23 a, 23 b, 24 a and 24 b are disposed opposite the heat radiation surface 21 a of the base 21 , interposing the wire plate 22 and the base 21 .

[0051] Amounting opening 22 b having a circular shape is formed in the wire plate 22 to expose a mounting area 21 c of the upper surface of the base 21 . An LED 25 as a light emitting chip is mounted on the mounting area 21 c and secured to the area by a silver paste 25 a having thermal conductivity. Thus, the LED 25 is thermally connected to the base 21 through the silver paste 25 a.

[0052] A pair of anodes and a pair of cathodes (not shown) are electrically connected to the conductive patterns 23 , 24 by four lead wires 26 a, 26 b, 26 c and 26 d. In order to realize a high luminance light emitting element, a large driving current is necessary. To this end, it is preferable to apply a high current to the anodes and cathodes of the LED by two wires respectively. The LED 25 , lead wires 26 a - 26 d and a part of the wire plate 22 are encapsulated by an encapsulating member 27 to protect these members.

[0053] When driving voltage is applied to the conductive patterns 23 and 24 , the voltage is applied to the LED 25 through the wires 26 a - 26 d. Thus, the LED 25 is driven to consume the power to generate energy. A part of the energy becomes light which is discharged passing through the encapsulating member 27 , and a large part of the energy becomes heat which is discharged from the LED. The heat of the LED is transmitted to the base 21 having excellent thermal conductivity through the silver paste 25 a. Thus, the heat is efficiently transmitted to the base 21 .

[0054] If a heat radiation member having a large heat capacity is adhered to the heat radiation surface 21 a of the underside of the base 21 , the heat of the base 21 is transferred to the heat radiation member, thereby realizing efficient heat radiation.

[0055] In this embodiment, although one LED is provided, the base 21 is made into an elongated plate, a plurality of LEDs may be mounted on the base. Furthermore, a plurality of wire plates 22 may be secured to the upper surface of the base 21 so as to form the mounting area 21 c.

[0056] FIG. 3 is a perspective view of a high luminance light emitting element according to a second embodiment of the present invention.

[0057] The same parts as the first embodiment are identified by the same reference numerals as those of FIGS. 1 and 2 .

[0058] The high luminance light emitting element 30 has a base 31 having a rectangular parallelepiped and made of a metal core material of copper alloy having high thermal conductivity. A wire plate 22 is secured to the upper surface of the base 31 by adhesives. Since the wire plate 22 , LED 25 and encapsulating member 27 are the same as the first embodiment, explanation thereof is omitted hereinafter.

[0059] There is formed a plurality of parallel cooling fins 31 a on the underside of the base 31 to increase the heat radiation area.

[0060] When the driving voltage is applied to the LED 25 , the LED 25 is driven to consume the power to generate energy. A part of the energy becomes light which is discharged passing through the member 27 , and a large part of the energy becomes heat which is discharged from the LED. The heat of the LED is effectively transmitted to the base 31 . Since there is provided a plurality of cooling fins 31 a on the underside of the base 31 , the heat is effectively radiated to cool the LED 25 . If there is provided a cooling fan to cool the LED 25 , the heat radiation is more effectively performed. The cooling fins may be formed on side walls of the base 31 .

[0061] FIG. 4 is a perspective view of a high luminance light emitting element according to a third embodiment of the present invention.

[0062] The same parts as the first embodiment are identified by the same reference numerals as those of FIGS. 1 and 2 , and explanation thereof is omitted.

[0063] The high luminance light emitting element 40 has a base 41 having a rectangular parallelepiped and made of a metal core material of copper alloy having high thermal conductivity.

[0064] There is formed a plurality of heat radiation cylindrical holes 41 a in one of sides of the base 41 in parallel with the underside of the base. It is preferable that the hole 41 a is perforated. If a heat conductive material is inserted in the hole, the heat radiation effect increases.

[0065] FIG. 5 is a perspective view of a high luminance light emitting element according to a fourth embodiment of the present invention, and FIG. 6 is a sectional view taken along a line VI-VI of FIG. 5 .

[0066] The same parts as the first embodiment are identified by the same reference numerals as those of FIGS. 1 and 2 , and explanation about a part thereof is omitted.

[0067] The high luminance light emitting element 50 has a base 51 having a rectangular parallelepiped and made of a metal core material of copper alloy having high thermal conductivity.

[0068] There is formed a cylindrical projection 51 a on the base 51 at a corner. On the projection, a terminal portion 51 b is provided as a terminal electrode. The wire plate 22 is recessed for the projection 51 a. The height of the terminal portion 51 b is equal to that of the terminal portion 23 a, 23 b.

[0069] An LED 52 has an anode 52 a on the upper surface thereof and a cathode 52 b on the underside. The anode 52 a is connected to the terminal portion 23 a by the wire 26 a and the cathode 52 b is electrically connected to the terminal portion 51 b of the projection 51 a through the base 51 .

[0070] When the driving voltage is applied to the LED 52 from terminal portions 23 a and 51 b, the LED 52 is driven to consume the power to generate energy. A part of the energy becomes light, and a large part of the energy becomes heat which is discharged from the LED. The heat of the LED is effectively transmitted to the base 51 to cool the LED 52 .

[0071] In accordance with the fourth embodiment, the base 51 is used as a lead member. Therefore, the LED having electrodes on the upper surface and underside can be used.

[0072] FIG. 7 is a sectional view of a light emitting device according to a fifth embodiment of the present invention.

[0073] The same parts as the first embodiment are identified by the same reference numerals as those of FIGS. 1 and 2 .

[0074] The light emitting device 60 comprises the high luminance light emitting element 20 of the first embodiment, a print substrate 61 as a substrate, and a heat radiation member 62 having thermal conductivity.

[0075] The print substrate 61 has conductive patterns 61 a of copper foil on the underside thereof and a perforated hole 61 b having a circular shape. The encapsulating member 27 is projected from the hole 61 b and discharges the light emitted from the LED 25 as discharge light 63 . The conductive patterns 61 a are electrically and mechanically connected to the terminal portions 23 a, 23 b, 24 a and 24 b with solders 61 c. The heat radiation member 62 is secured to the heat radiation surface 21 a of the base 21 to be thermally connected thereto.

[0076] When the driving voltage is applied to the terminal portions 23 a, 23 b, 24 a and 24 b through the conductive patterns 61 a to supply driving current to the LED 25 , the LED 25 is driven to emit light. The light is discharged as the discharge light 63 passing through the encapsulating member 27 . Heat discharged from the LED is effectively transmitted to the base 21 and to the heat radiation member 62 .

[0077] In accordance with the fifth embodiment, the heat discharged from the LED 25 is effectively transmitted to the heat radiation member 62 through the base 21 to radiate the heat to the atmosphere. Thus, the heat rise in the LED is held to a minimum limit. Consequently, it is possible to provide a light emitting device withstanding large current driving to emit high luminance light. Further, by virtue of the heat radiation effect, the deterioration of junctions in the LED and luminance decrease caused by color change of the encapsulating member 27 due to high heat can be prevented, thereby realizing a light emitting device having a high reliability and a long life.

[0078] The print substrate 61 connected to the terminal portions 23 a, 23 b, 24 a and 24 b is disposed apart from the heat radiation surface 21 a of the base 21 . Consequently, the print substrate 61 is not necessary to have heat radiation role, and hence it is not necessary to make the substrate with expensive material having high thermal conductivity such as metal core. Thus, it is possible to freely select a cheap material such as glass epoxy resin.

[0079] In order to increase the heat radiation effect of the heat radiation member 62 , it is preferable to increase area of the member or to form a plurality of projections on surfaces of the member. Although the light emitting element 20 of the first embodiment is used in the fifth embodiment, another element of any embodiment may be used. In the case using the second embodiment, since the base 31 has a high heat radiation effect, the heat radiation member 62 is not necessary to be used.

[0080] FIG. 8 is a perspective view showing a sixth embodiment of the present invention. The same parts as the third embodiment shown in FIG. 4 are identified with the same reference numerals. A light emitting device 70 comprises the high luminance light emitting elements 40 of the third embodiment, a pair of heat pipes 71 as a thermal conductive member and a heat radiation plate 72 made of material having thermal conductivity. In the heat pipe 71 , a liquid having thermal conductivity is charged.

[0081] An end of each heat pipe 71 is inserted in the heat radiation hole 41 a of the base 41 , and the other end of the heat pipe 71 is secured to the heat radiation plate 72 so that the base 41 is thermally connected to the heat radiation plate 72 .

[0082] When the driving voltage is applied to the LED 25 , the LED 25 is driven to emit light. The light is discharged as discharge light. Heat discharged from the LED is effectively transmitted to the base 41 and to the heat radiation plate 72 passing through the heat pipes 71 .

[0083] In accordance with the sixth embodiment, the LED 25 is mounted on the base 41 having thermal conductivity to be thermally connected, the base 41 is thermally connected to heat pipes 71 , the heat pipes are thermally connected to the heat radiation plate 72 . The heat radiation plate 72 effectively radiates the transmitted heat to the atmosphere. Thus, the heat rise in the LED is held to a minimum limit. Consequently, it is possible to provide a light emitting device withstanding large current driving to emit high luminance light.

[0084] Since the heat emitting element 40 and the heat radiation plate 72 can be separated from each other by the heat pipes 71 , it is possible to provide a heat emitting device which is easily assembled in a system.

[0085] As the fifth embodiment, a print substrate (not shown) is not necessary to have heat radiation role, and hence it is not necessary to make the substrate with expensive material having high thermal conductivity such as metal core.

[0086] In order to increase the heat radiation effect of the heat radiation plate 72 , it is preferable to change the shape of the plate, and the number of the heat pipes 71 may be increased. The base 41 and the heat pipes 71 may be connected by adhesives having thermal conductivity.

[0087] FIG. 9 is a side view showing a seventh embodiment of the present invention. The same parts as the first embodiment are identified with the same reference numerals. A light emitting device 80 comprises a plurality of high luminance light emitting elements 20 of the first embodiment, a flexible print substrate 81 and an arcuated heat radiating member 82 .

[0088] The flexible print substrate 81 has three perforated holes 81 a, 81 b and 81 c in which encapsulating members 27 of the light emitting element 20 are inserted. Conductive patterns on the print substrate 81 are connected to terminal portions of the light emitting element 20 by solders 83 . The heat radiation member 82 has three recesses 82 a, 82 b and 82 c, in each of which the base 21 of the light emitting element 20 is inserted and secured thereto to be thermally connected thereto.

[0089] When driving current is supplied to the high luminance light emitting elements 20 through the print substrate 81 , the LEDs 25 emit lights 84 a, 84 b and 84 c. Heats discharged from the LEDs 25 are transmitted to the heat radiation member 82 through the bases 21 to be radiated.

[0090] In accordance with the seventh embodiment, the bases 21 of the LEDs 25 are mounted on the heat radiation member 82 to be thermally connected. The heat radiation member 82 effectively radiates the transmitted heat to the atmosphere. Thus, the heat rise in the LED is held to a minimum limit. Consequently, it is possible to provide a light emitting device withstanding large current driving to emit high luminance light.

[0091] As the fifth embodiment, a print substrate 81 is not necessary to have heat radiation role, and hence it is not necessary to make the substrate with expensive material having high thermal conductivity such as metal core.

[0092] In the light emitting device 80 , a plurality of high luminance light emitting elements 20 are provided. Therefore, for example, when high luminance light emitting elements of red, yellow and green are disposed, it is possible to provide a light emitting device for emitting lights of various colors.

[0093] Since high luminance light emitting elements 20 are mounted on the flexible heat radiation member 82 , discharge lights can be concentrated as shown in FIG. 9 , or diffused by bending the heat radiation member 82 into a convex shape.

[0094] Hereinafter, a method for manufacturing a plurality of high luminance light emitting elements at the same time will be described with reference to FIGS. 10-15 .

[0095] FIG. 10 is a perspective view showing a wire plate aggregation 90 and a base aggregation 91 . The wire plate aggregation 90 is made of an insulating material and has four divisions. In each division, a conductive pattern 91 a is formed by etching of copper and a mounting hole 90 b is formed. The base aggregation 91 is made of a metal core having thermal conductivity.

[0096] FIG. 11 is a perspective view showing a combination step of the wire plate aggregation 90 and the base aggregation 91 . The wire plate aggregation 90 is secured to the surface of the base aggregation 91 by an adhesive to form a wire-plate-combined base aggregation 92 .

[0097] FIG. 12 is a perspective view showing a mounting step of an LED. An LED 93 is mounted on the wire-plate-combined base aggregation 92 at an exposed portion in the mounting hole 90 b and secured thereto by a silver paste.

[0098] FIG. 13 is a perspective view showing a wire bonding step. The electrodes of the LED 93 are connected to the conductive patterns 90 a by four wires 94 .

[0099] FIG. 14 is a perspective view showing an encapsulating step. The LED 93 in each division and wires 94 are encapsulated by an encapsulating member 95 of a transparent resin. Thus, each of the light emitting element is completed on the wire-plate-combined base aggregation 92 .

[0100] The wire-plate-combined base aggregation 92 is diced at boundaries between divisions as shown in FIG. 16 so that a single light emitting element 96 is completed.

[0101] Thus, in accordance with the present invention, a large number of light emitting elements can be manufactured at the same time at a low cost.

[0102] If light scattering agents, fluorescent substances or beam attenuating agents are included in the encapsulating member 27 , various high luminance light emitting elements and devices which are different in directivity and wavelength of the discharge light can be provided.

[0103] In accordance with the present invention, the LED is mounted on the base having high thermal conductivity. Therefore, the heat generated in the LED is effectively conducted to the base, so that a high luminance light emitting element having excellent heat radiation effects can be provided.

[0104] While the invention has been described in conjunction with preferred specific embodiment thereof, it will be understood that this description is intended to illustrate and not limit the scope of the invention, which is defined by the following claims.