WO1999057945A1

WO1999057945A1 - A lamp employing a monolithic led device

Info

Publication number: WO1999057945A1
Application number: PCT/US1999/009723
Authority: WO
Inventors: Mark R. Allen
Original assignee: Fiber Optic Designs, Inc.
Priority date: 1998-05-04
Filing date: 1999-05-04
Publication date: 1999-11-11

Abstract

A lamp including one or more monolithic LED devices, each having an array of LED dies (104) rather than pre-packaged, discrete LEDs providing light sources. Each monolithic LED device may have the LED dies wired in block series-parallel form in order to optimize size and cost of voltage converter (204), if employed. The LED dies are coupled as the array on the substrate and then encapsulated in a light conducting medium to form a lens (106) on the array of LED dies. LED dies may be controlled such that its individual color components, e.g., red, green, and blue when employed are either variable or fixed.

Description

A LAMP EMPLOYING A MONOLITHIC LED DEVICE

BACKGROUND OF THE fiWENTION Field of the Invention The present invention relates to a lamp having an array of LED dies, and, in particular, to a lamp employing a monolithic LED device.

Cross-Reference to Related Applications

This application claims the benefit of the filing date of U.S. provisional application no. 60/084,172, filed on May 4, 1998 as attorney docket no. 1009.001PROV.

Description of the Related Art

Employing light emitting diodes (LEDs) as a basic lighting source is increasingly attractive for applications such as complex backlighting, outdoor signage and signaling, and even simple replacement light bulbs or lamps. Lamps employing LEDs have the following advantages: (1) as a device, LEDs have much longer lifespan than other standard light sources, such as fluorescent and incandescent light sources, with typical LED lifespan being at least 200,000 hours as measured by 30% loss of light output degradation over time; (2) LEDs have several favorable physical properties, including ruggedness, low operating temperature, ability to operate under a wide temperature variation, and safe low-voltage power requirements; (3) LEDs are increasingly more efficient, as measured by light output versus power consumed, with newer, more sophisticated doping technologies, allowing typical power efficiencies for LEDs to be better by a factor of ten than power efficiencies of comparable incandescent lighting sources; (4) increased consumer demand, costs of LEDs are reduced and, therefore, LEDs are becoming increasingly cost effective for many applications; (5) new blue LEDs allow color and adjustable color lighting from a red/green/blue (RGB) combination; (6) new wideband "white" LEDs and related phosphoring technologies allow white light of good color rendering index without having to use an RGB mixture; and (7) recent invention of multilayer, multicolor LED die-on-substrate growing techniques enables fabrication of full color (RGB) monolithic LED devices at increasingly low cost.

LEDs are commonly provided as prepackaged dies, known as a "bulb" form or as a "discrete LED." Discrete LED packages include a tiny LED die, often called a LED "chip", a wire frame, and leads soldered between the wire frame and the LED. The die, wire frame and part of the leads are encapsulated in a light conducting medium, typically an epoxy compound, via injection molding into the shape of a tiny bulb. This manufacturing process accounts for much of the cost associated with a discrete LED. For example, a discrete LED that costs several cents each (in large quantity) may incorporate a LED die that costs a fraction of a cent.

- 1 LEDs as a light source for lamps are known in the art. For example, U.S. Patent 4,21 1,955 to Ray describes using discrete LEDs mounted in a transparent or translucent case. Further, US Patent number 5,726,535 to Yan for "LED Retrofit Lamp for Exit Signs," and US patent number 5,640,792 to Smith et al. for "Lighting Fixtures" are examples of LED light sources for particular types of applications. In these and all other related patents, a colored light bulb is described using prepackaged, discrete LEDs, and the equivalent-light incandescent power requirement is limited to a maximum of approximately 20 Watts. Three characteristics of these LED light bulbs of the prior art limit light or LED output power: (1) a large number of discretely packaged LEDs must be used to achieve practical light output, which may not be practical for certain common lamp package types due to the size of the discrete LEDs; (2) these lamps of the prior art may be expensive to manufacture due to the large number of prepackaged discrete LEDs required and due to high individual cost of the discrete LEDs; and (3) the typical application of the prior art, such as for exit signs or backlighting, requires only a relatively low light output power.

More recently, several LED sub-dies have been grown together on a substrate for the purpose of providing multiple color combinations of Red, Green, and Blue (RGB) LED light. These RGB sub-die combinations are described in, for example, U.S. Patent 5,459,337 to Ito et al for SEMICONDUCTOR DISPLAY DEVICE WITH RED, GREEN, AND BLUE EMISSION, and U.S. Patent 5,424,560 to Norman et al for INTEGRATED MULTICOLOR ORGANIC LED ARRAY, and these patents are incorporated herein by reference for their teachings of RGB die combinations grown on silicon substrates, as well as for their teachings of control of individual RGB sub-dies for adjusting output light color.

SUMMARY OF THE INVENTION

A lamp comprising a lamp body; an electrical interface mounted in the lamp body and adapted to interface with a standard voltage supply; and a monolithic LED device electrically coupled to the electrical interface and comprising: i) an array of electrically coupled LED dies mounted on a substrate, and ii) a package having a lens, the substrate encapsulated in the package with the lens over the array.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will become more fully apparent from the following detailed description, the appended claims, and the accompanying drawings in which: FIG. 1A shows a top view of a monolithic LED device in accordance with the present invention having block series-parallel wiring.

FIG. IB shows a side view of a monolithic LED device in accordance with the present invention having block series-parallel wiring. FIG.2 shows an exemplary wiring diagram for a monolithic LED device in accordance with the present invention constructed of individual red, green, and blue sub-die arrays coupled in a block series-parallel configuration.

FIG. 3 A shows a top view of an exemplary embodiment of the present invention employed in a "R-type" lamp configuration.

FIG. 3B shows a side view of an exemplary embodiment of the present invention employed in a "R-type" lamp configuration.

FIG. 4A shows one exemplary circuit for the voltage converter of FIGs. 2A and 2B having a step-down transformer in accordance with the present invention to convert power and effect control of the monolithic LED device.

FIG. 4B shows another exemplary circuit for the voltage converter of FIGs. 2A and 2B having a low-pass capacitor followed by a step-down resistor to convert power and effect control of the monolithic LED device.

FIG. 5 shows a block diagram of an exemplary controller that receives an output signal of the voltage converter of FIGs. 4A and 4B and controls each variable resistor and so effects control of each color component.

FIG. 6A shows a top view of an exemplary embodiment of the present invention employed in an "A-type" screw-in hemispherical lamp configuration.

FIG. 6B shows a side view of an exemplary embodiment of the present invention employed in an "A-type" screw-in hemispherical lamp configuration.

FIG. 7A shows a top view of an exemplary embodiment of the present invention employed in a low- voltage, push/screw type lamp configuration.

FIG. 7B shows a bottom view of an exemplary embodiment of the present invention employed in a low-voltage, push/screw type lamp configuration. FIG. 7C shows a side view of an exemplary embodiment of the present invention employed in a low- voltage, push/screw type lamp configuration.

FIG. 8 A shows a top view of an exemplary embodiment of the present invention employed in a 110 VAC fluorescent-type, plug-in tube lamp configuration having two transformer-based power supplies.

FIG. 8B shows a side view of an exemplary embodiment of the present invention employed in a 110 VAC fluorescent-type, plug-in tube lamp configuration having two transformer-based power supplies. DETAILED DESCRIPTION

In accordance with the present invention, a lamp includes one or more monolithic LED devices, each LED device having an array of LED dies rather than prepackaged discrete LEDs. The monolithic LED de ice may be formed using multilayer crystal fabrication, or assembled by soldering together or otherwise connecting individual prefabricated LED dies, onto a substrate. The array of LED dies of the monolithic LED device may be wired in a block series-parallel fashion to optimize, for example, either the size and cost of the step-down transformer or the efficiency of the step-down resistor, of exemplary embodiments of lamps in accordance with the present invention including a voltage converter. The array of LED dies may comprise a mixture of RGB sub-dies or "white dies" or a mixture of both types of dies. Intermediate colors in addition to RGB (e.g. yellow) may also be used to obtain better color rendering index. White dies may be, for example, blue dies with phosphorescent coating to produce a wideband spectrum. Wiring in such embodiments may be such that the output is either adjustable or fixed.

A monolithic LED device employed in a lamp in accordance with the present invention may allow: (1) much greater light density than lamps of the prior art; (2) much lower production cost when an array of LED dies is employed when compared to arrays of discrete LEDs as employed in the art; (3) more efficient heat dissipation; and (4) greater design freedom for covering geometric surfaces with light output power. A monolithic LED device employing numerous, for example hundreds, of dies wired in an array on a substrate may form a lamp component of a predetermined light output power, and different lamps may be constructed employing multiple lamp components.

Referring to FIGs. 1A and IB, there are shown top and side views, respectively, of an exemplary monolithic LED device 100 having an array of LED dies, as may be wired for a light source or lamp in accordance with the present invention. FIGs. 1A and IB show five series blocks 108, each block 108 consisting of six LED dies 104. However, the configuration of FIGs. 1A and IB is exemplary only and does not imply that the invention is so limited to such configuration. The monolithic LED device 100 consists of a substrate 102, such as rigid printed circuit board (PCB) or silicon, a plurality of LED dies 104, and a lens 106 formed over the array of LED dies 104. An encapsulation, using a light conducting medium, such as epoxy, for example, may be used as a package for lens 106 as well as for a body of monolithic LED device 100. Lens 106, as shown in FIG. IB is planar, but other shapes may be employed. Each LED die 104 may be a set of RGB sub-dies, where the red, green, and blue sub-die components form adjacent linear subarrays along the monolitiiic LED device 100 in, for example, an alternating order to balance the resulting light such that a desired color, for example, a white color temperature, is achieved.

In accordance with one embodiment of the present invention, the monolithic LED device 100 may either be constructed by growing LED dies 104 on the substrate 102, such as silicon, where electrical

- 4 - coupling of internal LED dies in a block series-parallel configuration is incorporated into a semiconductor chip making process. In accordance with another embodiment, the monolithic LED device may be constructed by mounting individual, prefabricated LED dies 104, which also may emit having more than one color, on the substrate 102, such as PCB or silicon, where the LED dies 104 are then electrically coupled together in block series-parallel on the monolithic LED device 100 through a standard process, such as wave soldering. For either of these cases, the monolithic LED device 100 is then encapsulated as described previously, generally using an injection molding process similar to that used for individual LED packaging, with a light-conducting material, so as to form lens 106 on front of device 100 to having one of many possible specific focusing properties. The monolithic LED device 100 may be formed having various shapes and sizes. A light output power of the LED dies 104 of the monolithic LED device 100 may be operated by individually controlling each RGB sub-die LED die 104; operated by controlling each subarray of LED dies individually, such as by control of the individual RGB sub-die color components together; or operated by controlling the entire monolithic LED device 100 at once. Moreover, multiple monolithic LED devices 100 may be coupled in parallel to produce geometric configurations: for example, a hemispherical radiation pattern may be constructed by employing planar-shapes for monolithic LED device 100 which are oriented along each geometric axis of a lamp. For typical lamp applications, control of the array of LED dies 104 is normally achieved so as to cause the light output power to have either a variable color component or fixed color component. For a monolithic LED device 100 of a lamp in accordance with the present invention, the preferred embodiment includes block series-parallel coupling of LED dies 104. Block series-parallel coupling of LED dies 104 allows a maximal number of dies to be wired in series so as to matching the maximum input voltage of the monolithic LED device 100. Each series set is then wired in parallel to provide a desired lumens, electroluminescent, or light output power for the desired input voltage. Block series-parallel coupling allows for matching of input voltage of LED device 100 with the supply voltage to minimize the size and cost of a voltage converter described subsequently with respect to FIG. 3B. For common lamps with a low-voltage DC supply voltage, such as 12 VDC commonly used in outdoor lighting or automobiles; block series-parallel coupling may also be used to eliminate the voltage converter converting between different DC voltage levels. Note that the series block in the block series-parallel wiring may be as small as one die, resulting in a pure parallel circuit, in which case series wiring is not necessary.

A monolithic LED device 100 in accordance with the present invention may have several advantages in heat dissipation. Each LED die 104 is mounted directly on substrate 102 and substrate 102 may, in turn, typically be mounted on a heat sink to dissipate heat generated by monolithic LED device 100. Since a path of heat conduction to the heat sink is only through substrate 102, rather than through additional packaging for each discrete LED as in the prior art, more heat may be dissipated through a heat sink than discrete LED

- 5 - arrays. Operating monolithic LED device 100 with such a heat sink may extend an operating life of each LED die 104.

FIG. 2 shows an exemplary wiring diagram for a monolithic LED device 100 in accordance with the present invention constructed of individual red, green and blue sub-die arrays coupled in a block series-parallel configuration. As shown in FIG. 2, each block 302, 304 and 306 may be connected in parallel for each block 310, 320 and 330, with each sub-array controlled by respective voltage applied across RED,

BLU and GRN rails to ground potential GND.

In FIGs. 3 A and 3B there are shown top and side views, respectively, of an exemplary embodiment of a lamp 200 in accordance with the present invention as may be employed in, for example, a standard 1 10 VAC "R-type" floodlight or spotlight configuration. Lamp 200 includes monolithic LED device 100 as shown in FIG. 1, lamp housing 207 including front face 206, mounting brackets 212 and side 208, voltage converter 204 and base 210.

Lens 106 may be employed to provide focusing properties. In alternative embodiments, focusing of light from monolithic LED device 100 may either be performed by lens 106, or by a front face 206 of the lamp housing 207, or by both. Monolithic LED device 100 is electrically coupled to a supply voltage by a voltage converter 204, which may be a transformer, such as step-down transformer, series resistor, or other type of voltage converter employed in the art to convert from a supply voltage such as an AC or DC supply followed by a bridge rectifier circuit. A voltage regulator (not shown) following the bridge rectifier may also be employed, but for preferred embodiments, the voltage regulator is not necessarily employed since it is desired for the lamp 200 to be dimmable and since common power surges may be handled by a simple varistor. The supply voltage is electrically coupled to the lamp 200 by an electrical interface shown as base 210 and optional voltage converter 204. Base 210 may be formed as a screw-in plug for a candelabra, an intermediate, or medium base, for example.

The voltage converter 204 of FIGs. 3A and 3B is employed to connect the supply voltage to a desired input voltage to the monolithic LED device 100. For a case having equivalent supply voltage and input voltage, the voltage converter 204 may be omitted.

Lamp housing 207 may be manufactured so as to appear in any standard configuration, such as an ordinary R-type lamp configuration shown in FIG. 2, as may be desired for audience appeal in mass marketing. The electrical interface in accordance with the present invention, having base 210 and optional voltage converter 204, provides the monolithic LED device 100 with an input voltage from the supply voltage. Lamp housing 207 may be constructed from several parts, with some parts being opaque, such as the funnel-shaped side 208, and other parts being transparent or frosted, such as the front face 206. In all the implementations shown in FIGs. 3A and 3B and FIGs. 6A through 8B, these parts may desirably be fastened or glued togetfier in a hermetically sealed fashion to prevent moisture damage. T e monolithic LED

- 6 - device 100 and voltage converter 204 are supported in the housing by means of internal mounting supports

212, which may be either opaque or transparent, and may be, for example, either separate glued-in components or molded as a part of other components of bulb housing 207. In both cases, for the exemplary embodiments shown in FIGs. 3A and 3B and FIGs. 6A-8B, the housing may be made using a rigid, durable plastic such as polycarbonate.

For embodiments of the present invention adapted to interface a monolithic LED device 100 with a high AC supply voltage, such as 100/220 VAC, the voltage converter 204 (FIG. 3B) may employ the exemplary embodiments as shown in FIGs. 4A and 4B. FIG. 4A shows a first embodiment of voltage converter 204 comprising step-down transformer 407 and FIG. 4B shows a second embodiment which includes a low-pass capacitor 406 followed by a step-down resistor 407. Both voltage converters as shown in FIGs. 4A and 4B employ an optional varistor 403 for surge protection, a bridge rectifier 404 for full-wave conversion of the AC supply voltage to a DC voltage and an optional variable resistor 405 for each positive output lead. FIGs. 4A and 4B show three output of supply leads, one for each of the RGB sub-die color components. More leads may be required if intermediate colors are used, for example, to increase color rendering index (CRI). If only white dies or dies of a single color are employed, the variable resistor may not be necessary, and the output may have one lead.

Variable resistors) 405 in the voltage converter of FIGs. 4A and 4B may be employed to regulate power available for each sub-die color component. Variable resistors 405 may be controlled by a variety of activators, such as a simple set of external slides or knobs that the user may manually adjust to a sophisticated controller having a processor that may blink, change color, or adjust color in a continuous, a periodic, or a random way, depending on specific desired applications. FIG. 5 shows color adjustment controller 500 as employed in accordance with the present invention that may adjust color emitted by LED die 104 in a continuous fashion, or to maintain approximately the same color, for example, white color temperature when the lamp 200 is dimmed. Color adjustment controller 500 includes an analog-to-digital converter (A/D) 501 Read Only Memory (ROM) 502 and Switching Network (SW-NET) 503.

Referring to FIG. 5, for each color component, the positive output of the bridge rectifier 404 (FIGs. 4A and 4B) is provided to A/D 501 as well as into SW-NET 503. The A/D 501 converts the voltage level into a digital signal, shown in FIG. 5 as a 3-bit digital value yielding eight discrete values. These voltage values are converted by ROM 502 into signals that actuate the SW-NET 503 in a predefined way. The SW- NET 503 controls the variable resistor 405 (FIGs. 4A and 4B) through a set of internal taps, not shown, corresponding to minimal, maximal, and intermediate levels of resistance, or equivalently, attenuation to the sub-die color component output of LED die 104.

Providing a maximum voltage input to the monolithic LED device 100 minimizes the required current, allowing a reduction of wire gauge in the step-down transformer of voltage converter 204 and, more

- 7 desirably, a turn-ratio in a step-down transformer for transformer 407 may be minimized. For example, using a 1 10 VAC supply voltage and a monolithic LED device 100 having one hundred LED dies 104 and each LED die 104 drawing 20 mA at 2 VDC, if LED dies 104 are wired in parallel such that an input voltage to device 100 is 2 VDC, a total current drawn by the monolithic LED device may be approximately 2 Amperes and a turn ratio of the step-down transformer may be approximately 55: 1. With one hundred LED dies 104 in the device 100 wired in accordance with a block series-parallel configuration, each block comprising five LED dies 104, the input voltage provided to device 100 is 10 VDC, the total current is 0.4 Amperes, and a turn-ratio of the step-down transformer of voltage converter 204 is 1 1 :1. In either case the total power consumption is the same at 4 Watts, with 100% efficiency, but the block series-parallel configuration results in a lamp 200 which is smaller and less costly to produce.

For an alternative embodiment, the voltage converter 204 employs a step-down resistor 407 and step- down capacitor 406 as shown in FIG. 4B, as may be most useful for very small light bulbs where size limitations are severe, instead of a step-down transformer 402 as shown in FIG. 4A. The use of a maximum voltage input to the monolithic LED device 100 not only minimizes the monolithic LED device current requirement, hence minimizing the size and cost of the step-down resistor 407, but also maximizes the efficiency of the lamp by minimizing power loss through the step-down resistor 407. For example, using, as above, a 110 VAC supply voltage and a monolithic LED device 100 consisting of one hundred LED dies 104, each LED die 104 drawing 20 mA at 2 VDC, if the array of LED dies 104 were wired purely in parallel such that its input voltage is 2 VDC, the total current drawn by the monolithic LED device 100 would be 2 Amperes and its resistance would be 100 Ohms. The step-down resistor 407 for this case would be 5,500 Ohms and the total power consumed would be 220 Watts, which compared with 4 Watts of the example described results in only 1.8% efficiency and considerable heat dissipation through the step-down resistor 407. With the same number of dies in the monolithic LED device 100 wired with a block series-parallel configuration, where each block consists of, for example, five dies 104, the resulting input voltage of monolithic LED device 100 may be 10 VDC, the total current may be reduced to only 0.4 Amperes and the monolithic LED device resistance may be 500 Ohms. The step-down resistor 407 in this case would be reduce to 1,100 Ohms and the total power consumed would be reduced to 44 Watts, which compared with 4 Watts of the example above results in 9% efficiency which is a five-fold increase in efficiency over the purely parallel wiring case with five- fold less heat generated. With recent introduction of 1 10 VDC LEDs, voltage conversion other than from AC to DC (using bridge rectifier) may not be necessary.

FIGs. 3 A and 3B and the following FIGs. 6A-8B illustrate exemplary embodiments of the present invention as used in typical light bulb configurations. The preferred embodiment spans any light bulb application involving the use of one or more monolithic LED devices 100, and the exemplary embodiments of FIGs. 3 A and 3B and FIGs. 6A-8B may be a set of common lamp configurations for 1 10 VAC screw-in, 12 VDC (low voltage) push/screw, and 110 VAC fluorescent-type, plug-in applications, respectively. As such, lamps employing the monolithic LED device 100 described for these applications preferably include either a set of white dies or a set of colored RGB dies for LED dies 104 that produce light output power of desired color temperature. These sets of dies are wired together in a block series-parallel configuration described previously with either maximum series block size or a size of block 108 having the input voltage matched to a low-voltage supply voltage, such as 12 VDC. With a typical drive voltage of 2V for each LED die 104, these two requirements may be the same or similar; i.e., the maximal block size, which may be six, may result in a 12 V monolithic LED device 100.

For example, for the four exemplary lamp embodiments described with respect to FIG. 3A and 3B and FIGs. 6A to 8B, it may be desirable to form monolithic LED device 100 as a lamp component for the purpose of convenience and low manufacturing costs. The light output power of the monolithic LED device 100 constructed as a lamp component may have light output power equivalent to an incandescent power of 20 Watts, or approximately 200 lumens. Using such a component monolithic LED device 100, five monolithic LED devices 100 may be wired together in parallel, for example, to form a lamp equivalent to a 100 Watt lamp having approximately 1000 lumen light output. In the preferred exemplary embodiments shown in FIGs. 3A-3B and FIGs. 6A-8B, the lamps are shown having array of LED dies 104 controlled either through its primary RGB sub-die color components or all at once, resulting in a reduced number of possible leads to the monolithic LED device. These exemplary embodiments are so shown for clarity only and the invention herein is not so limited, encompassing much general approach of all possible sizes of monolithic LED devices 100, array dies of LED dies 104, and sets wiring variations as described previously. For a monochromatic or white light bulb using monochromatic or white dies for LED dies 104, the preferred embodiment would involve only two leads, whereas if white light is produced using a RGB monolithic LED die array device, up to four leads may be required, particularly if a variable resistor is used to vary the current to each color as a function of applied input voltage, to account for differences between each of the three color components light output versus power characteristic curve, in order for the output light to maintain the same whiteness characteristic; i.e., color temperature, when dimmed, or for the user to produce a desired continuous color or color sequence. In addition, intermediate color LED dies 104 may be employed to better match the spectrum of daylight, as commonly indicated by color rendering index, with CRI = 100 being a "perfect" match.

FIGs. 6A and 6B show top and side views of a standard 1 10 VAC "A-type" hemispherical lamp configuration based on a set of five planar monolithic LED devices 100. For this embodiment, each monolithic LED device 100 may have an equivalent light output incandescent power requirement of 20 Watts (200 lumens), forming a replacement for an equivalent 100 Watt incandescent bulb. The mounting 212 supporting the five monolithic LED devices 100 is preferably transparent or translucent, whereas the mounting 212 that supports the voltage converter 204 is preferably opaque. Accordingly, the parts of the bulb housing 207 forming the globular front face 206 and form the sides up to the mounting support for the

- 9 - power supply is likely to be transparent or frosted, whereas the remaining parts of the housing 207 forming the base 210 are preferably opaque. Variations of this lamp configuration employed with dies providing red, green or yellow may be preferred for traffic light applications.

In FIGs. 7A, 7B and 7C, there are shown conceptual top, bottom and side views of a low- voltage (e.g., 12 VDC input) lamp configuration based on a single monolithic LED device 100 with light output equivalent to an output of incandescent power 20 Watts (200 lumens). Low-voltage supply voltage such as 12 VDC may be common for outdoor safety/decorative lighting or automotive lighting. Base 210 may be a push/screw connector as is^' employed in a standard outdoor low-voltage lamps, as is the shape of the housing 207. Since the monolithic LED device is wired in block series-parallel form such that its operating voltage is matched to the supply voltage (e.g., 12 VDC), the monolithic LED device 100 may be coupled to the base 210, eliminating the need for voltage manipulation or regulation, and so eliminating voltage converter 204, thereby reducing manufacturing cost. In this embodiment of FIGs. 7A-7C, the front face 206 of the housing 207 would be either transparent or frosted, and possibly have a focusing lens molded in, whereas an area from the mounting support 212 to base 210 is preferably opaque. In the exemplary embodiment as shown in FIGs. 8A and 8B, the lamp 200 may be formed as a 1 10

VAC fluorescent-type tube lamp configuration based on, for example, a set often monolithic LED devices

100 arranged along a line and spaced evenly across a, for example, four foot long mounting support 212.

With ten such monolithic LED devices 100, each having light output equivalent to an incandescent output of 20 Watts (200 lumens), the total light output may be equivalent to a 40 Watt fluorescent bulb (2000 lumens). The plug-in connector for bases 210 is purposely drawn to duplicate that of a fluorescent-type tube bulb, as is the shape of the housing 207. In this case, the housing 207 may be such that an area from front face 206 to the mounting support 212 is either transparent or frosted, and the remaining areas may be opaque. Depending on a size and cost of voltage converter 204, it may be desirable to use two power supplies, with one at either end directly connected to the respective base 710, and with each transformer and bridge rectifier of voltage converter 204 supplying half of the monolithic LED devices 100, for example, wired in parallel. In this embodiment, it may also be desirable to mould the mounting support 212 into a bottom portion of housing 207.

These embodiments shown in FIGs. 3 A and 3B and FIGs. 6A through 8B are exemplary only, and do not comprise the totality of possible implementations claimed herein. Many other forms of lighting fixtures may be constructed employing the monolithic LED device in accordance with the present invention, including low-voltage lighting, automotive lighting, street lighting, emergency lighting, flashlights, and decorative lights such as track lights, for example. In addition, embodiments having various forms of die array control wiring for the monolithic LED device to control and adjust light intensity, as described previously. More sophisticated control features may also be included for decorative lighting designs, such as random or periodic or random blinking and/or color changing.

- 10 - It will be further understood that various changes in the details, materials, and arrangements of the parts which have been described and illustrated in order to explain the nature of this invention may be made by those skilled in the art without departing from the principle and scope of the invention as expressed in the following claims.

11

Claims

CLAIMSWhat is claimed is:

1. A lamp comprising: a lamp body; an electrical interface mounted in the lamp body and adapted to interface with a standard voltage supply; a monolithic LED device electrically coupled to the electrical interface and comprising: i) an array of electrically-coupled LED dies mounted on a substrate, and ii) a package having a lens, the substrate encapsulated in the package with the lens over the array.

2. The invention as recited in claim 1, wherein the electrical interface comprises a voltage converter, the voltage converter adapted to convert a first voltage potential of the standard voltage supply to a second voltage potential, and the electrical interface couples the array of electrically-coupled LEDs across the second voltage potential of the voltage converter.

3. The invention as recited in claim 2, wherein the voltage converter is a transformer, the voltage transformer being either a step-down transformer or a low-pass capacitor with step-down resistor circuit.

4. The invention as recited in claim 1, wherein the monolithic LED device includes at least one set of at least two arrays of electrically-coupled LED dies, each array having series-connected LED dies, and the at least two arrays coupled in parallel forming a discrete block.

5. The invention as recited in claim 4, wherein each array of series-connected LED dies is voltage- matched to a predetermined voltage potential.

6. The invention as recited in claim 5, wherein sets of one or more discrete blocks are coupled in parallel, thereby to form the monolithic LED device having a standard light output power.

7. The invention as recited in claim 2, wherein at least one LED die of the array of electrically- coupled LED dies is a white die.

8. The invention as recited in claim 7, wherein the electrical interface includes an actuator, each array of electrically coupled LED dies includes a variable resistor having a resistance responsive to the actuator, thereby to adjust a luminance of each LED die.

9. The invention as recited in claim 8, wherein the actuator is manually adjusted.

- 12

10. The invention as recited in claim 8, wherein the actuator includes a controller, the controller adjusting the resistance of the variable resistor to provide a predetermined luminance sequence of the lamp.

1 1. The invention as recited in claim 8, wherein the electrical interface comprises a voltage converter, the converter adapted to convert a first voltage potential of the standard voltage supply to a second voltage potential, and the actuator includes a bridge rectifier coupled in parallel across the second voltage potential, an output signal of the bridge rectifier related to at least one stored value, the stored value employed to adjust the resistance of the variable resistor.

12. The invention as recited in claim 2, wherein at least one LED die of the array of electrically- coupled LED dies is a multi-color die having at least two of a red sub-die, a green sub-die and a blue sub-die.

13. The invention as recited in claim 12, wherein the electrical interface includes an actuator, each array of electrically-coupled LEDs includes a separate set of series-connected red sub-dies, series-connected green sub-dies and series-connected blue sub-dies, each separate set having a variable resistor having a resistance responsive to the actuator, thereby to adjust a luminance of each sub-die of the set.

14. The invention as recited in claim 12, the multi-color die further comprising at least one intermediate color die, the intermediate color die operated so as to adjust a color rendering index of the multi-color die.

15. The invention as recited in claim 1, wherein the array of electrically-coupled LEDs emit a light output having a single color.

16. The invention as recited in claim 1, wherein the array of electrically-coupled LED dies is mounted on the substrate by either growing each LED die on the substrate or mounting pre-fabricated dies on the substrate.

17. The invention as recited in claim 14, wherein the substrate is either a printed circuit board, ceramic substrate or a silicon-based crystal.

- 13 -