DETAILED DESCRIPTION

[0064] The system is built around a “digital” light source. That is, the emanating lighting effect is the sum of the characteristics of a multiplicity of discretely controllable “digit” sources. The difference between the individual “digit” light sources and their summation manifests itself in the resultant light characteristic, be in its intensity, spatial intensity distribution, spectral energy content and spectral intensity distribution. All of these characteristics are also variable with time. A light source for this purpose may be electroluminescent such as a Light Emitting Diode (LED) junction, Organic Light Emitting Diode (OLED) or carbon-related field emission devices such as a nanotube-phosphor-combination, HID, fluorescent or even an incandescent source. While a one-source lamp will not have the flexibility to effect the most correct illumination characteristics, such as maintaining correct intensity and color temperature for the lighting task at hand over changing environmental conditions, two or more differentiated sources will have an increased operating range. This flexibility is useful as for example in a multi-source luminaire with spatially differentiated dimming capability used in an office lighting application. In a normal day's operation, such as in a windowed room between peak daylight and nighttime hours, the intensity and color temperature of the light varies greatly over different portions of the room. The smooth variation possible with many light sources (“digits”) vs. one light source offers superior flexibility in providing the actual lighting needs. Therefore, the illuminating device may be described as a “digital” light source or as a Multiple Solid-state Light Source (MSLS), comprising many “digits”, SLSs, and essentially replaces the lamp of present-day luminaires.

[0065] As used herein, the term “light source”, LED or “solid state light source” means any system that is capable of receiving an electrical signal and producing light in response to the signal. Thus, the term “light source” should be understood to include light emitting diodes of all types, light emitting polymers, semiconductor dies that produce or emanate light in response to current, organic LEDs, electro-luminescent strips, and other such systems. Incandescent and discharge light sources are also included and multiples of incandescent and discharge light sources also provide a digital luminaire. In an embodiment, a “light source” may refer to a single light emitting diode package including multiple semiconductor LED dies that are individually controlled.

[0066] The term “illuminate” should be understood to refer to the production of a wavelength of radiation by an illumination source. The term “color” should be understood to refer to any wavelength of radiation within a spectrum; that is, a “color,” as used herein, should be understood to encompass wavelengths not only of the visible spectrum, but also wavelengths in the infrared and ultraviolet areas of the spectrum, and in other areas of the electromagnetic spectrum.

[0067] In designing a multi-light source luminaire the minimum design criterion for intensity and spectrum differs for each application and is related to the end user who is the ultimate measuring instrument and economic consideration of the light provider. The regularity of the changes in effects is derived from the user's perception. It is generally accepted that the eye cannot discern changes in beam intensity that are smaller than a factor of two to ten and color temperature differences of 200 to 300K. Illumination intensity changes are discernable as a logarithmic function and depend on background illumination levels. For example illuminating practice allows for hallway lighting to be 20% of room lighting due to rapid eye adaptation. However the eye is very perceptive of intensity changes when comparing images such as in comparison of gray scales and thus lighting for an art lay-up room must be very even.

[0068] A further improvement is where the lamp and lighting fixture function are carried out in one device. In a typical present-day lighting fixture, a lamp with a symmetrical distribution in placed in a reflector to redirect the light, a requirement involving added cost of the reflector and performance inefficiencies. While PAR and other integral reflector lamps exist, they again have a symmetrical distribution in one of the axes and are large due to the high temperature of operation and requirement to distance reflective surfaces due to heat and large light source dimension consideration. Since the solid state or LED lamp is made of cool operating components which have a mechanical base (versus a 1000K gas discharge which is free floating) the LED allows for an integral small sized optical element near the power source. Where the terms optics or optical are mentioned herein, they refer to redirecting light rays through any of the known phenomenon including: reflection, refraction and diffraction. Typically, an LED will come packaged in an optical assembly consisting of a reflector and lens with 8° to 50° spreads being typical. A Surface Mount Device—SMD LED with no optics will still be limited to 180° due to its construction.

[0069] A power-conditioning device such as a ballast is required to operate efficient fluorescent and HID light sources but is separate therefrom in function and physical construction. In the MSLS the power source is electronic as is the control equipment and thus the electric power conditioning circuitry can be integrated with the light source circuitry and packaged as one on a PC board or integrated circuit manufactured in the same way of the same materials. Chip on board and chip on chip technologies are used as a packaging configuration for LED chips as well as power and logic control transistors and other components. Power transistors come packaged in plastic and so do LED junctions only that the LED package is light transmitting and can be formed into a lens. Transistors, molded in a transparent package together with LEDs, may be shielded from undesirably receiving illumination causing base photocurrent, by providing opaque “junction coat” over the transistor die, as is well known in the semiconductor industry. The packaging also lends itself to the same manufacturing methodology such as soldering elements onto a PC board. Both hole through and SMT configurations are presently available for most of the components. This combined unit of compatible, mass producible, apparatus, including the solid-state lamps, their optical assembly, electronic ballast gear and structural fixture equipment, provides a unique Digital Lighting Fixture (DLF) device.

[0070] In a preferred embodiment the DLF is provided with an onboard controller. The controller may be a computer board, embedded device, a Digital Signal Processor, etc. In general, the term “logical controller, controller or computer” can be broadly defined to encompass any device having control circuitry or a processor which executes instructions from a memory medium.

[0071] A further improvement is the reduction of all electronic and optical components to the chip level. That is, light-emitting junctions may be placed with power electronics in an integrated circuit. For example, combination GaAs LED-JFET technology may be used, the JFETs (junction FETs, acting as control devices for the LEDs. The carrier is made of materials and shaped to carry out optical and or heat transfer functions. Multiple light emitting junctions of similar or differing characteristics, a function of doping and diffusion, are placed with the control circuitry on chips. The VLSI techniques used in digital camera photodiode arrays containing millions of pixels is used to create arrays of light emitting diodes. Actually reversing the current flow on some photodiodes will cause them to emit light. This is how OLEDs were discovered. OLEDs began in the lab as photovoltaic cells until by error they were driven in reverse. Alternately other die bonding techniques are used to create chip on chip assemblies as is known in the art. Sets of chips with similar or differing characteristics may be geometrically arranged to provide a specific light distribution and color mixing. The total envelope is then a combined lamp, power supply and lighting fixture “luminaire”, and is positioned within the room to be illuminated at the design height and position to give a consistent and sufficient lighting to the area under its control. Cooling is effected using natural convection or for air currents from a cooling fan or fluidic cooling using natural or forced circulation.

[0072] On the chip and die level further magnitudes of manufacturing and packaging efficiency are realized. The integration can avail itself of other more compact packaging technologies such as chip on board and chip on chip. Assemblies with conductive and non-conductive diebonding using epoxies and eutectic solders used for a variety of semiconductor die types including ASIC's, MEM's, LED's and Sensor's. These may be used on a variety of substrate materials including FR4, Alumina, Metallised Ceramic, Carbon Fibre and Chip on Flex as single die or multiple die arrays for Chip scale packaging/CSP's. Conductors are attached to the dies via Aluminium and Gold wirebonding using both wedge bonding and ball bonding. The manufacture of Multi chip modules/MCM or Chip scale packages/CSP are also possible and can be ceramic, laminate or PCB based. These assemblies can be single or multiple die assemblies with external components making it possible to manufacture all light, sensor, power and control components as a superior integrated device.

[0073] The present invention provides an illuminating device which serves as a replacement for the lamp, socket, reflector, electric power control gear, dimmer and mechanical structure of a present-day lighting fixture or luminaire. A semiconductor junction packaged integrally with light controlling components provides a Solid-State Light Source SLS and many together form an MSLS, which when combined with power conditioning, and optionally logic control, communications and affixing elements, provides a DLF. The basis of the invention is the use of a multitude of discrete light emitting sources (“digits”) to generate light. The light control elements can be applied on a per junction basis or on a “white” color generating set grouping such as RGB or on a larger set which may be convenient for manufacturing or other color rendering considerations. The requirement for controllability is however, that the SLS output is definitive in relation to spectrum and spatial distribution.

[0074] The discrete light emitting elements by operating and not operating, at full power or at a fraction of, either partially or in unison, generate light with optimal intensity, spectral distribution, and spatial distribution of intensity and spectral distribution for the viewing task at hand. This is accomplished without recourse to separate (exterior to the DLF) reflectors to redirect the light, filters to alter color, shades to control glare or dimmers to control intensity. An example of light source used in a DLF would be an electroluminescent semi-conducting material an example of which is a LED. Such a source is characterized relative to a standard incandescent lamp by its small dimensions, low voltage, low current, monochromatic spectrum, high resistance to physical shock, high directionality of the light output, and at the present, relatively high cost. In addition, the intensity of the light output over a defined range is a function of the current and within limits may be varied by orders of magnitude without deleteriously affecting the efficiency or lifetime of the LED.

[0075] Although the light production of a typical 5 mm, 50 mA maximum rated, LED of between 1 to 2 lumen is much too low to be of any practical use for illumination, the combined output of a few to hundreds to thousands of LED's is quite significant. Higher current LEDs are now being introduced which operate at 350 mA and provide 20 to 30 lumen. This however, is still is highly impractical for use in lighting a room when compared to a 100 watt incandescent lamp of 1700 lumen. Based on progress to date it is expected that LEDs will reach comparative lumen per Watt efficiencies of 60 to 120 I/W as found in gaseous discharge lamps. This invention relates to technologies which are feasible at the present state of the art I/W as well as those which will become feasible in the future.

[0076] A “light bulb” of the present invention is comprised of a multitude of LED's where each LED or group of LED's may be of the same or different wavelength, (color—where said wavelength may be mono or multi-chromatic), light output, spatial distribution and operating frequency (as when an alternating signal is used or it is multiplexed). The light from an LED or group of LED's of red color operating with an LED of blue and green color impinging on an object would appear to the viewer as “white light”. By varying the number and/or light power output of a specific color LED or group of LED's relative to the others, a different intensity and color temperature of light with a “warm” or “cool” appearance may be effected. “White” LEDs can also be used in the invention alone or with other monochromatic LEDs. A white LED comprises an emitter in the blue spectrum covered with a phosphor which fluoresces in yellow such that the combined output appears white. White LEDs come in various angular light distribution patterns and color temperature variations. White LEDs can also be combined to vary intensity and spectrum. In the preferred embodiments, “white” LEDs are not used, as the use of phosphor adds unnecessary conversion inefficiencies and output degradation with time. The ability to correct for color shift over the DLF lifetime with white LEDs is limited. However, the present invention includes the use of white or other multi-spectrum light sources.

[0077] Presently the efficiency of many types of LED's (the chemical make-up of the junction differs between colors) is high relative to incandescent but low relative to discharge lamps. However, the theoretical efficiency is quite high and the inefficiencies have to do with getting the light out between the junction and heat dissipation considerations. Expressed in lumens per watt LED's may produce up to 30 lumen/W versus 100 I/W for a discharge lamp and 18 I/W for an incandescent lamp. In the preferred embodiment, a highly efficient constant current power source is used to drive the LED's where the electronic circuit is a series connection of the discrete LED light sources. The open failure of an LED or series of LEDs which would interrupt the circuit is circumvented by the use of Zener diodes, placed such that the functionality of the lamp would not be seriously affected. The constant current power source has the advantage that different LEDs, of different forward voltage drops, from different manufacturing runs or chemical composition, may be operated together. Alternately, power circuits available in the literature for driving the LEDs are used as published in technical notes by manufactures such as Agilent®.

[0078] The life expectancy of an LED can be expected to be as high as 240,000 hours between failure. Due to light degradation over time average lifetime is normally rated at 100,000 hours. At best an incandescent's rated life may be 2,000 hours and that of a fluorescent, 20,000 hours. However, the LED operated in a circuit would have only the reliability of the circuit and MTBF divided by the number of series connected LED'S. A printed circuit board with the LED's alternately connected to separate circuits with redundant access to the power sources and with the use of Zener diodes every so many LED's to circumvent any failed sections could operate directly off of the 120/240V line. Any voltage AC or DC from 4V up to 480V is practical. The LED's of the hole—thru or SMT type would be soldered in place or the LED's connected leg to leg without using a PC board.

[0079] The LED's are mounted flat in rectangular patterns or in concentric circles or on or within holes situated on geometrically curved surfaces such as on a sphere or hemisphere of round, parabolic or elliptical shape according to the desired candle power distribution pattern. The LEDs can be mounted perpendicularly to the geometric fixture surfaces or at any other angle. When mounted perpendicularly the surface geometry is dictated by the light distribution pattern and the LED photometrics. This is the generally assumed design case in this disclosure. However, any geometry is possible with the non-perpendicular mounting of the light sources. A flexible PC board is manufactured in the flat and then “origami” style cutouts are made allowing the PCB to be bent and shaped into the preferred form. LEDs are insertable into holes made in plastic or metal forms to secure the LEDs in the correct location at the correct aiming.

[0080] For fluorescent lamp retrofit applications, the MSLS “luminaire” would be linear with LED's mounted all around the circumference or predominantly downwards for whichever lighting effect is desired. While a fluorescent's light distribution is usually not controlled in the longitudinal direction (the reflector can't get around the long dimension of the lamp) the LED version would be spatially directed so as to give uniform light. In comparison to a fluorescent lamp, where the light is produced equally in all directions irrespective of the final distribution pattern required in the room, the DLF has the advantage of producing light directed only where it's needed. The number of SLS aimed in a specific direction at the time of manufacture is such that the proportion and angle of the light going to the ceiling and floor are calculated to produce the desired result. Louvers and reflectors are unnecessary to prevent glare or redirect the light. Up to 40% to 60% of the light produced in a fluorescent fixture goes to waste due to these considerations.

[0081] In other embodiments of a linear fluorescent replacement SLS lamp “luminaire”, the position regarding the nadir (floor) of the rows of SLS are adjustable. One or more SLS strips are free to move in an arc about a long axis such that they are aimed for uplight or down light. Apparatus is provided to fix the re-positioned SLS in place. Markers along the arc can delineate the angle. Thus, the installer can adjust the amount of up-light, down-light and floor coverage in the field, (markings on the fixture would indicate standard settings) just as an adjustable reflector changes luminaire light distribution. Here again, the difference is that there are no reflector-induced inefficiencies because of operation away from the ideal design point.

[0082] A pear shaped globe “luminaire” studded with LED's projecting light outward from the surface would give both down-light and up-light with more projection surface towards the down-light side in a typical 1 to 3 recommended ratio. Most buildings, rooms or areas to be illuminated are of a rectangular shape. The LED's on the DLF are concentrated at the 90-degree intervals. This yields a more square lighting pattern to ensure equivalent lighting in all areas of the room including the corners. This is in contrast to the chronic lack of even coverage obtained from the circular light pattern of present day light bulbs or most luminaires. At best these prior-art lamps give a circular light distribution which requires overlapping to ensure complete coverage of the area with the overlap lighting levels in wasteful excess of the requirements. A position oriented MSLS lamp has a greater concentration of LED's aimed at 90° intervals so that more light energy is directed into the far-off corners of a room to give an even illumination throughout the rectangular or square shaped area. A DLF is made with square, rectangular and even rounded light distribution if the application requires.

[0083] Typically, an incandescent or HID lamp is used in conjunction with a reflector to redirect the light to obtain a desired light pattern where more of the light is directed where it is most useful. A luminaire for area lighting will have a “bat wing” candlepower light distribution pattern, which yields equal horizontal illumination on a surface as it compensates for the “inverse square law” (a function of the cosine of the angle and the distance squared from the source). Generally, such an optical assembly has efficiency less than 80% due to losses on the reflector's surfaces. The MSLS needs no reflector to redistribute the light since each discrete SLS “digit” is aimed such that the candle power intensity varies with angle as is needed to give the optimum illumination on the room work surfaces for a given mounting height. The MSLS lamp distribution is pre-designed according to typical house or office settings. Thus, there is no need for a reflector to redirect the light and its consequent inefficiencies in order to obtain a “bat wing” distribution. The present approach by LED manufacturers is to provide single high output LEDs with optics yielding a “batwing” distribution. These batwings are usually less than optimal and are circular. The “digital” approach of this invention would yield a finer control and thus a more accurate batwing, generating a more even distribution in a rectangular/square vs. circular pattern.

[0084] In a DLF it is possible to combine a task light having a very narrow “spot” beam at the correct aiming with a general area lighting “flood” beam into one fixture. The digital lighting fixture is positioned according to recommended lighting practice near a workstation and correctly oriented such that the DLF gives a wide (though still controlled, so as not to cause glare on a computer display) general illumination distribution as well as a narrow distribution aimed at the desktop for high intensity task lighting. In a preferred embodiment a positionable task lighting spotlight located on a section of the DLF can be aimed manually or by servomotor to project onto the work area.

[0085] In another example of prior art practice a table lamp for reading is provided with a shade. The shade is there to partially redirect the light onto the book and also prevent direct, glaring, rays from the lamp used for general lighting from reaching the reader's eyes. According to the present invention, instead of having a glaring lamp producing light which is then made non-glaring by a shade at a loss in excess of 50% the LF is built such the amounts of light directed downward at useful angles and the amount of light directed upward are in the correct ratio. The surface area, from which discomfort-glare causing rays exit, is designed such that the luminous exitance is within recommended UGR levels for home use. The fixture has no need for a shade to protect from glare; the glare was never produced at those angles to begin with due to proper geometric design. To get the desired luminous exitance expressed in terms of lumen per sq. meter or luminance in terms of candela per sq. meter, the light exiting the source of specific intensity at angles which normally reach the room occupant's eyes, is spread over an area such that the exiting light is non-glaring. These lighting design parameters serve as the product specification and are incorporated into the initial design. There is no need to add on components to achieve correct lighting.

[0086] In MSLS technology an antique style table lamp uses a MSLS “bulb” specifically designed for the application, there is no need for an additional shade other than for aesthetics. The shade is a decorative element which diffuses a small amount of light for the rustic effect. The small amount of light which would be directed between 70° to 150° (the glare zone) would cause as little discomfort glare as that which is obtained from a shaded incandescent lamp but without the waste. This is done by sizing the area and intensity of the light source responsible for providing light at those angles such that the luminous exitance from the surface is within acceptable non-glaring luminance values. If desired, uplight to the ceiling above the glare zone is provided with light sources projecting between 150° to 180°. To maintain the aesthetics that people are used to or for the good feeling, a shade may be placed over the “digital” table lamp. A few LEDs can be dedicated for the purpose of illuminating the shade, either by projecting thru the shade and diffusing the light or projecting the LEDs into the shade as in a light guide. Colored LEDs could make the shade look yellow, pink or blue as preferred and programmed by the user.

[0087] The dimming capability of the MSLS is quite dramatic. A typical LED of today such as an Agilent® HLMP25-ED-xxxx will produce light at a tenth of a milli-Ampere and may be operated up to 50 mA. At 0.1 mA it may produce 5 milli-lumen while at 50 mA over 1000 ml. This is a hundredfold range. Another radiation output control technique is to provide pulsed power in place of constant current. LEDS are operated on DC as well as pulse power and current as well as timing in terms of duty cycle, pulse width and other signal modulations are useable by the controller to effect intensity changes.

[0088] Correct lighting doesn't only include an even light distribution and a lack of glare but a list of other factors including intensity, warmth and color rendering. Experiments have shown (IES Lighting Handbook 8th edition p.99) a graph of preferred color temperature of light sources at various illumination levels. The graph specifies a warmer color temperature say 2,500 Kelvin for lighting levels in the 100-lux range and a cooler temperature say 3,500 for 1,000 lux. However, a typical dimming system used in a fluorescent luminaire will lower the lighting level but will not change the color temperature. A DLF of the present invention will change the balance of the different spectrum light sources in order to achieve the correct color temperature for the new lighting level. As far as dimming goes, it possible to get an instantaneous “instant on” from the SLS light source. Thus, with a built in or exterior motion detector, the DLF can be operated at emergency lighting levels, sufficient for orientation, and then immediately power up to full level when someone enters the room. Whereas a fluorescent dimmed to 50% power will give a negative return of only 10% light an LED will generally give a linear if not positive decrease in power with light reduction. Auto-dimming circuits taking sunlight into account have been touted as an energy saving technique.

[0089] In another embodiment, the electronic luminaire has a light level detector and automatically adjusts the output to the required level. If the lighting level on only one side of the room is enhanced by the sunlight, directional luminance meters, external or integral to the DLF, detect the imbalance and the controller dims only those SLS oriented to illuminate in the sunlight illuminated direction. This detailed spatial distribution intensity control is not possible with other lamp types.

[0090] The MSLS lifetime is long such that there is essentially no need for “lamp” replacement over the life of the DLF luminaire. However, power supply circuit and light source characteristics may vary over time and correct lamp color will deviate from the standard. A feedback control loop using sensors would recalibrate color based on daylight readings over the twenty-year lifetime of the fixture. Thus a photodiode with an RGB filter is calibrated under natural light conditions. Alternately, discrete wavelength or alternately stable “white”, or color, LEDs which are used only for calibration or only operated in a regime where their color is known not to shift are used as the recalibration color standard. This basis serves the dimming system in its color temperature control over its lifetime. The controller is programmed over the lifetime to seek possible recalibration opportunities. These may include using daylight or other artificial light sources available when the LSLS is not producing light. The systems can determine the accuracy of this source partially by comparing it to its previous factory or onsite calibration. Time of day analysis and initial small deviations would allow the system to evaluate whether the source was a reliable standard to use over its lifetime to correct for component color shift.

[0091] To ensure higher reliability the MSLS in the preferred embodiment will make use of large-scale integrated circuit technology where the LED junctions, Zeners and other elements are interconnected on, a chip. The chips then mounted into plane surfaces which are flat, rounded or X-hedrons.

[0092] The MSLS lifetime is long such that there is essentially no need for “lamp” replacement over the life of the DLF. This requires that the designs of the other electronic components are similarly reliable. The fixture mechanical design is again a significant departure from prior art. The fixture is sealed for life. There are no openings, gaskets, and sockets and there is no need for a mechanism to open the luminaire. All the components can be encapsulated for life to prevent water and dust ingress and thus provide a reliable, maintenance free, weatherproof and hazardous location ready lighting fixture.

[0093] The small dimensions of the light sources makes them ideal for use in conjunction with fiber optic light transmission systems. One of the primary requirements of such systems is the ability to collect the generated light into the narrow fibers. The excellent controllability of the light beam and the small source size allows for the generation of high-power narrow non-dispersing beams as would be used in flashlight, searchlight and beacons.

[0094] Multiplexing of the lamps is possible for power and lighting effect considerations. Slower duty cycles will reduce energy consumption, increase lifetime and would be used in a number of applications. Aircraft warning beacons which flash is an application, as the on off cycling of an LED is not harmful to lamp life as it is to an incandescent lamp. Disco lighting-effect lamps are another flashing application. Dimming as well as illumination color can be carried out with both the duty cycle and current being altered.

[0095] In summary, as opposed to LED industry trends of going with a single large source, the present invention provides multiple smaller sized sources of differing characteristics such that their combined effect is greater than that which could have been offered by sum of the individual parts operating separately. The added controllability offered by breaking the total light output up into discrete specifically aimable and dimmable elements, “digits”, which can be addressed by control electronics to effect intensity, spectrum and distribution, yields a lighting fixture (vs. lamp) of unparalleled performance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0096] In order to better understand the preferred embodiments and methods of this invention reference is now made to the following figures.

[0097] FIG. 1 is a block diagram of the elements which in combination provide a digital lighting fixture (DLF). The DLF serves as a complete luminaire solution including: power conditioning circuitry, control electronics, sensors, mechanical fixture and light source. The DLF replaces the lighting fixture, ballast, socket, lamp, dimmers, reflector, gaskets and fasteners with a sealed for life electronic assembly. An electric power source 1 , supplies power at line Voltage 110 to 480V or at low Voltage 12-24 Volt to the DLF 2 . The DLF includes more than one light source 3 , which is preferably an electroluminescent solid-state light source but may be any other light source, such as incandescent, high intensity discharge, fluorescent, etc such that the individual characteristics of each lamp's light are combined in operation to achieve a sum of the characteristics presenting a benefit not achievable from a single source alone. The light sources are affixed or contained within a mechanical device 4 , which may serve as containment to all of the components and facilitates affixation to building surfaces. The electric power is received in the correct waveform, voltage and current from the power source 1 , or is conditioned within the DLF 2 , by power conditioning elements and circuitry 5 . The direction of light exiting from the DLF as a whole or from each SLS individually is controllable by optical elements 6 , such as reflective surfaces and or refractors, and may be electronically variable optical elements.

[0098] The separate light sources may be of the same color and intensity characteristic or may have different color and intensity characteristics . Thus for a 3-stage light bulb equivalent, each of three sources can have the same lumen rating or two sources are used where one is twice the output of the other. In a finely variable, digital embodiment the effect of continuous dimming effect is achieved when the differences in the lighting level is imperceptible to the people in the room. Typically a 5% change will not be perceived. Thus with twenty equivalent intensity LEDs as a base (one additional would add less than 5%), additional quanta could be smoothly added, or on the other hand, to in reality perform perceptible dimming (which is the objective) a greater than 5% change should be effected. The same is true for the final spectral color of the light emanating from the DLF to illuminate objects. The eye adds the radiation reaching the eye and cannot perceive the separate components, contrary to the ear's recognition of sounds where each frequency is individually resolved. Therefore, quanta of specific spectral color energy may be added to the mix without perception. For example changes up to 200 degrees Kelvin in HID lamps are not perceived. Thus to effect a noticeable color change, a quanta of spectral color power would need to be added or detracted from the sum.

[0099] In a preferred embodiment the DLF contains logic control electronics unit 7 . Logic control electronics unit, 7 , receives input and/or feedback from motion, intensity and/or spectral sensors 8 , or from manual control button 9 and increases or decreases or turns on or shuts off the power to one or more of the SLS to effect the desired change. That is, the control logic unit 7 has stored parameters for intensity and spectral distribution and operates the MSLS lamp within the predefined range. The control unit may include a DSP or computer with storage media, computer algorithms, signal input and output electronics, analog to digital converters, and communications elements to carry out intensity, distribution, dimming and color balance control. Computer algorithms and instruction sets 7 A are induced by the logical controller to manipulate data, calculate results generate output signals and maintain the operating parameters within the specifications. Measured parameters are checked against the stored parameters and the control circuitry adjusts the power to SLS.

[0100] Sensors 8 include any of the following: light, temperature and motion detection devices. Two types of optical detection sensors may be used: A photo detector with specific spectral sensitivity to detect a specific color. For example a standard red, blue and green set which would then indicate how “white” the light is. Alternately, a wide spectrum photo detector that irrespective of color measures the intensity of each excited die as it is test fired, based on the eye visual sensitivity curve. The optical sensor may be lensed and capable of forming an image, that is a camera and the detector may be a detector array of photodiode pixels. The detector array may be a CMOS or CCD VSLI array and may be monochromatic or color as in a monochromatic or digital camera. Such arrays are readily available in mega-pixel resolution.

[0101] With changes in ambient lighting the light sensors detecting conditions at a specific location receive input. The detector instantaneously reads the ambient during a momentary shut off the artificial light source. The momentary shutoff is of short duration, e.g., less than one millisecond duration, at rates undetectable to the users as the eye does not discern flicker rates above {fraction (1/100)}th of a second. The controller then readjusts the driving circuitry to the correct power level. The sampling of multiple sensors around the DLF can be simultaneous using buffers in the controller to facilitate analysis by methods known in the art. Alternately, the light sources and coordinated detectors at specific locations are turned off, sampled, turned on again and sampled, to verify that the illumination is within recommended specifications. Interaction between DLFs, located in close proximity to each other, is avoided, by the use of the short-duration momentary shutoff controller readjusting time interval. The probability of simultaneous controller readjustment of two adjacent DLFs is very small. Further, the timer which controls the time between the controller readjusting time intervals, is preferably analog, such that there is very low probability of two DLFs having the same time between controller readjusting intervals.

[0102] In a system with feedback, changes in the light source output reflected back to the lamp such as color shift and diminishing flux over time can be compensated for. A typical fluorescent or HID source will experience serious color shift over its 10,000 to 20,000 hour lifetime. It would be a significant advantage to have a 100,000 hour life lamp with color accuracy over the complete lifetime of the lamp.

[0103] In a preferred embodiment a re-calibration system will operate as follows. The DLF is provided with a reflective rod or strip the surface of which has a wide spectrum, non-angle of incidence dependency and stable reflection characteristics over time. The reflective rod or strip is positionable so that the rod or strip can reflect light back to the outward facing photodetector based on the DLF body. In another embodiment the DLF is provided with a calibration wand on which inward facing photodetectors are placed. The calibration wand is capable being positioned such that the detectors can detect SLS performance. Both the reflective rod/strip and calibration wand can be narrow such that they can be permanently deployed about the DLF and not block light. In another embodiment the rod, strip or wand is stored and is only deployed when calibration is required. When called upon, the rod, strip or wand is rotated around the DLF to read SLS intensities. Alternately, the DLF body rotates and the rod, strip or wand remains fixed. The DLF is originally calibrated in the factory using external detectors. The spectral output of each SLS is calibrated with the power supply controller over the range of power outputs and the characteristics are stored in a memory device for recall during operation. The calibration wand or reflective rod or strip is then used by the DLF in an internal calibration where the DLF detector's readings at the initial SLS power settings are recorded. These readings become the standard for future calibrations, where the controller will affect the power to individual junctions such that proper intensity and color is produced.

[0104] The DLF has a clock unit and/or a communication unit capable of receiving signals from the US government operated “atomic clock” which is located in Colorado. The DLF automatically searches for the signal or once a day it automatically recalibrates its time. On a periodic basis after degradation is assumed to be significant, the controller 7 invokes the calibration routine.

[0105] In another preferred embodiment the DLF surroundings are used for calibration in place of the calibration strip. A short time following installation, (after the furniture and decor has settled down), an on site calibration is scheduled and run at the first opportunity. The purpose of this on-site calibration is to have the controller check the spectral characteristics of the illuminated area. A specific die on an SLS is fired on a timed basis and the controller reads the photo detector value. The new site-specific reading is then taken and compared to the original calibration and stored. The site-specific reading will serve as the base for the next calibration, as it is assumed to render the surroundings correctly based on still calibrated light sources. The next calibration may be scheduled for night and holidays to ensure a date when dark conditions prevail. If darkness cannot be ensured, the incremental shift in intensity above the ambient can be measured. Photo diode detectors of known field of view are placed on the DLF such that SLS output is detected. In lights out conditions of darkness the controller takes a base reading sample of a detector. The base reading allows the subtraction of “noise” from further readings. During the calibration the base reading may be repeated to ensure accuracy. Periodically, possibly every half a year, more or less depending on manufacturer data of how much the LEDs drift from their initial performance, a calibration routine is run. If a change in decor has been made, then the drastic change will signal the logic controller to ignore the latest reading and use the present “white” setting to recalibrate the new decor. Although photodetectors are stable devices, over a 30 year DLF lifetime it may be necessary to calibrate the photodetectors as well. Absolute intensity readings can only be recalibrated against a laboratory standard. However, daylight may be used to recalibrate color sensitive photodetectors over the 20-year lifetime. At the post installation calibration session a day reading of photodectors is performed and the readings analyzed for daylight sources. This is done using the clock where daylight will show a predicable spectral shift over the hours of the day. The controller will then compare the readouts of detectors over the day to identify those exposed to daylight. First during the day readings of the photodetectors are taken.

[0106] The detectors facing the daylight are assumed calibrated to read “white light. In darkness SLS units, SLS 1 in view of one calibrated daylight facing detector, detector 1 and one uncalibrated detector, detector 2 , are powered to produce white light as determined by the calibrated detector. Now detector 2 is calibrated. Moving stepwise around the DLF the process is repeated with now calibrated detector 2 used to adjust SLS 2 located between detector 2 and not yet calibrated detector 3 to produce “white” light. SLS 2 's output is then used to calibrate detector 3 . The process continues around the DLF till other daylight-calibrated detectors are reached. For greater accuracy the process can then be preformed in the other direction, moving stepwise until detector 1 is reached again. By using this nodal analysis method discrepancies propagated in the calibration process are reduced.

[0107] A power guide 10 can serve as both a power distribution and mechanical affixation device to the placement of additional DLF units 11 within an expanse. Light output 12 from one DLF may differ in distribution from another 13 , if say one MSLS is in the center of a room and the other is at the edge or one light illuminates steps between the landings and another is the last step before the landing, the last step would be illuminated in a different color.

[0108] Since an LED device is operable over a wide range of currents, when an LED serves as the light source, dimming and color balance are smoothly and infinitesimally variable.

[0109] For the purpose of illustration, a preferred embodiment of the present invention is presented in FIG. 2B juxtaposed with a prior art solution using LEDs shown in FIG. 2A . A typical “bulb” shape with a screw in base is provided for retrofit locations where a socket is available. The prior art design depicts LEDs spread out on the surface of what looks like a reflector lamp. It is evident from the downward facing 5 mm hole-thru type LEDs— 14 that no attempt has been made to extract a “batwing” or any other effective type of light distribution pattern. Upward facing LEDs— 15 seem intended for uplighting and again it is clear from the symmetry that no attempt has been made to provide a rectangular pattern which will give a better use of light for indirect lighting.

[0110] FIG. 2B illustrates the teachings of the present invention. In this case, although packaged to appear as a typical “A” shaped light bulb, the device is actually a DLF and provides a complete lighting solution. Although shaped like a lamp with a screw base to facilitate replacement when the “lamp” burns out, this is not necessarily the intent. Rather, in the present concept, after 100,000 hours (over 30 years in typical use) its time to refurbish the room and change the fixture. The outward design is thus generated by what people expect to purchase and not what a DLF, that is not a lamp should look like. A true DLF design would not include the ceiling mounted socket and would be provided with a wiring connector and accoutrements and fasteners for attachment directly to the ceiling.

[0111] A retrofit MSLS lamp or digital lighting fixture/luminaire 16 intended to replace the lamp, fixture, reflector or shade and control-gear combination of a typical lighting fixture, includes a screw base 17 , which receives line power 18 into the electronic power conditioning circuitry 19 . In a preferred embodiment, control circuitry 20 is provided in the lamp. The input to the control is from an external source or internal logic circuit or both and in a preferred embodiment a sensor pack 21 with one or more radiation and communication sensors capable of detecting motion, day/night, spectrum, luminance etc is provided. In external control, a control signal 22 rides on the power signal 18 and enters via the screw base 17 or an infrared or other radiation detector provided in 21 picks up the control signal. Discrete packaged light sources, e.g. Solid-state Light Source SLS 23 containing one or more junctions are mounted on the DLF lighting fixture body 24 and connected to the controlled power circuitry that determines which of the SLS 23 will operate and at what power. Each SLS with it spectral and distribution characteristic is mounted in a specific location on the surface of the DLF with an angle α, 25 from the nadir. Any angle from the nadir is possible including 180 degrees and the light flux can serve to provide uplight or illuminate a picture on a wall.

[0112] In a position oriented lamp arrangement, that is where the socket has a distinct stop point, detent or pin and is mounted substantially oriented to the room or its contents such as a work desk or wall painting, and also the DLF has a specific mounting orientation relative to the socket, then the light distribution can be nonsymmetrical and tailored to the needs of the room. The screw base 17 has a detent or pin 26 that coincides with the stop point on the socket, which is mounted in a specific location radially around the lamp at an angle β, 27 in reference to pin 26 and a design start point on the circumference of body 24 . The SLS are placed at an angle β horizontally and vertically angled α to illuminate specific areas and also have their own spatial light distribution angle θ ₁ 28 A. An SLS aimed to illuminate an interior area may have a wide distribution or a distribution without a sharp cutoff 28 A while those SLS located at the edge of the area to be illuminated may be of narrow distribution θ ₂ 28 B and have a sharp cutoff. This technique is similar to how a sport playing field is illuminated with multiple floodlights. Floodlights of narrow beam spreads such as a NEMA 2 are used to illuminate at the edge of the illuminated area while wider NEMA 4 beam spreads are used near the center of the playing area. The MSLS lamp will have concentrations of SLS at specific aimings to provide a wide “flood” type distribution to one part of the room and a “spot” type distribution to another such as to a painting on the wall. Each illumination target is at a different light intensity and color temperature or color rendering.

[0113] In another embodiment SLS, which perform an equivalent to a task light function with a very narrow beam, are combined with SLS performing a general background lighting function in one fixture. While general lighting recommendations in an office call for the provision of 300 to 500 lux over the working plane, specific task lighting, for example where copy work is to be illuminated by auxiliary lighting, 1,000 lux is required. To this end a section 29 , containing SLS on the DLF, provides a narrow beam of higher intensity, to provide added light flux to the working surface. In an alternate embodiment section 29 on the DLF is on a swivel and can be manually adjusted to be aimed at the worktable. In an alternate embodiment the swivel is positioned by a servomotor and controlled by a remote control unit. In an alternate embodiment to the fixed task light section 29 , in an attempt to cut down on separate fixture types with left or right handed spot or other asymmetric orientations, the MSLS portion of the DLF body 24 is rotatable in relation to the affixing base 17 . Such an embodiment also obviates the need for a position oriented socket and base pin 26 .

[0114] In another embodiment, modulating the output of wide distribution and narrow distribution LEDs by the controller varies the net resultant beam spread characteristics. The fixture is placed near a workstation and gives a wide distribution general lighting as well as a narrow high intensity beam for increased illumination level task lighting on demand.

[0115] In order to assure an even distribution of light from a point source over an area, it is necessary to take the effects of the angle and distance to the illuminated surfaces into account as stated in the inverse square law. Often a “batwing” type of candlepower light distribution is used. In a prior art luminaries the reflector, which concentrates reflected rays in the higher angles, accomplishes this. In a preferred embodiment of the MSLS there are more, or more powerful, SLS over a range 1 aimed at higher angles to increase light flux at those angles in order to maintain an even light distribution. If the lamp is specifically oriented in relation to the room concentrating more light into the distant corners effects a squared distribution pattern, which would fill in the corners of a square room with equivalent illumination. An added amount of SLS are added on the DLF body 24 at 90 degree angles on β, 27 where SLS aimings will push added light into areas corresponding to the “corners”. To effect uplight towards the ceiling or for indirect lighting SLS 23 A are aimed towards the ceiling such that an optimal utilization of the light is achieved.

[0116] In the preferred embodiment color of light emanating from an SLS 23 is “white” light. This is accomplished by using a “white” light producing arrangement of LEDs that is comprised of two or more spectrally differentiated junctions, which then combine their light output such that the illuminating light appears white. Other white LED technologies use phosphor or other coatings over the junction which causes a shift to longer wavelengths. The separate junctions in an SLS or separate SLS may be independently controlled. In a multi-junction SLS the total color of the illumination may be shifted to “warm” or “cool” light in correct accordance with the illumination level (see FIG. 10 ) or other considerations. In another preferred embodiment, a motion detector is used to conserve energy. The room lamp is dimmable to a lighting level sufficient for safe orientation. A motion sensor 21 picks up activity and increases the illumination level to meet the activity level. This integral placement significantly reduces the wiring from sensor to power supply and again back to lamp in prior-art dimmer—motion sensor applications.

[0117] In alternate embodiment each SLS 23 may have a non-white color. The operation of many SLS in unison of different or similar wavelength may be used to create any color desired from white to monochrome in any specific region to be illuminated. A spectrum sensor 21 inputs data to controller 20 , which maintains color at predefined level. Such a feedback mode allows for the MSLS to maintain constant color over the full lifetime of the lamp even if specific wavelength SLS shift output characteristics such as light flux and spectrum with age within bounds of the sensors calibration over age. Constant color is maintained in a room with an influx of a less desirable color temperature light on one side. Spectrum sensor 21 with a specific orientation would detect a “cool” light reflection emanating from a specific side of the lamp and will increase “warm” e.g. 2000K light to compensate. Over the long lifetime the DLF could recalibrate its spectral sensors 21 to white light based on readings of daylight where such daylight is available and the controller has determined that the room at the time of calibration is being illuminated with white light “daylight” of a specific color temperature per orientation and time of day.

[0118] The same light distribution effect based on light source aimings could have been accomplished as in the prior-art, easy to manufacture flat pc-board confi