HK1167202B - Reconfigurable led array and use in lighting system - Google Patents

Abstract

A light-emitting device capable of being powered by an AC power supply or an unregulated DC power supply is disclosed. The light-emitting device, in an aspect, is coupled to a controller, a light-emitting diode ("LED") array, and a power supply, wherein the power supply can be an AC power source or an unregulated DC power source. While the power supply provides electrical power, the controller generates various LED control signals in response to power fluctuation of the electrical power. The LED array allows at least a portion of LEDs to be activated in accordance with the logic states of the LED control signals.

Description

Reconfigurable LED array and use in lighting systems

Cross Reference to Related Applications

This application claims priority from U.S. patent application No. 12/504,994, filed earlier on 7/17/2009, which is incorporated herein by reference.

Technical Field

Example aspects of the invention relate to a lighting device. More particularly, aspects of the present invention relate to a light emitting apparatus generating light using an AC power source or an unregulated DC power source.

Background

Solid state light emitting devices, such as light emitting diodes ("LEDs"), are attractive candidates for replacing conventional light sources, such as incandescent and fluorescent lamps. LEDs generally have significantly higher light conversion efficiency than incandescent lamps and have longer lifetimes than conventional light sources. Some types of LEDs have higher conversion efficiencies than fluorescent light sources, and even higher conversion efficiencies have been demonstrated in the laboratory. In order for LEDs to be accepted in various lighting applications, it is important to optimize each step of the process and achieve the highest possible efficiency.

Since conventional LEDs use regulated DC power, a problem associated with conventional LEDs or LED lighting systems is the power conversion from AC power to DC power. LEDs typically operate with a constant DC current and a constant DC voltage. Electric utility companies, on the other hand, deliver AC current and/or AC voltage. A conventional power source, such as power at an electrical outlet, is AC power. Currently available lighting systems on the market, such as incandescent light bulbs and/or halogen lamps, are powered by AC power.

One conventional way to address the DC power requirements for LED lighting systems is to provide AC to DC power conversion. Power conversion from AC to unregulated DC, and then from unregulated DC to regulated DC is often cumbersome and expensive. In particular, capacitive elements used in AC to DC converters generally have a shorter lifetime, which will affect the overall lifetime of the LED lighting system.

Disclosure of Invention

A light emitting device is disclosed that uses a reconfigurable light emitting diode ("LED") array that can be powered by either an AC power source or an unregulated DC power source. The light emitting device is coupled in one aspect to a controller, an LED array, and a power source, wherein the power source can be an AC power source or an unregulated DC power source. Although the power supply provides electrical power, the controller generates various LED control signals in response to fluctuations in the electrical power. The LED array allows at least some of the LEDs to be activated according to the logic state of the LED control signal.

It is to be understood that other aspects of the present invention will become readily apparent to those skilled in the art from the following detailed description, wherein only an exemplary configuration of LEDs is shown and described by way of example. As will be realized, the invention is capable of other and different aspects and its several details are capable of modification in various other respects, all without departing from the spirit and scope of the present invention. The drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.

Drawings

Example aspects of the present invention will become more fully understood from the detailed description given below and from the accompanying drawings of various aspects of the invention, which, however, should not be construed as limiting the invention to the specific aspects but are for explanation and understanding only.

FIG. 1 is a block diagram illustrating a reconfigurable LED array having a controller capable of controlling LEDs in accordance with an aspect of the present invention;

FIG. 2 is a block diagram illustrating a lighting system having a reconfigurable LED array with a controller in accordance with an aspect of the present invention;

FIG. 3 is a block diagram illustrating another topology or layout of a reconfigurable LED array having a controller in accordance with an aspect of the present invention;

4A-4D are block diagrams illustrating a reconfigurable LED array with H-bridge operation according to an aspect of the present invention;

5-9 illustrate example AC LED topologies showing a reconfigurable LED array in accordance with an aspect of the present invention;

FIG. 10 is a graph showing a set of graphs illustrating the performance of delivering power to a lighting system using a reconfigurable LED array according to an aspect of the present invention;

FIG. 11 is a block diagram illustrating a control circuit for controlling a reconfigurable LED array in accordance with an aspect of the present invention;

FIG. 12 is a flow chart illustrating a process for reconfiguring an LED array using a controller in accordance with an aspect of the present invention;

FIG. 13 is a conceptual cross-sectional view illustrating an example of an LED;

FIG. 14 is a conceptual cross-sectional view illustrating an example of an LED with a phosphor layer;

FIG. 15A is a conceptual top view illustrating an example of an LED array;

FIG. 15B is a conceptual cross-sectional view of the LED array of FIG. 15A;

FIG. 16A is a conceptual top view illustrating an example of an alternative configuration of an LED array;

FIG. 16B is a conceptual cross-sectional view of the LED array of FIG. 16A; and is

Fig. 17 illustrates an example apparatus including an LED or LED device fabricated by laser scribing in accordance with some aspects of the present invention.

Detailed Description

Aspects of the present invention are described herein in the context of a method, apparatus, and device for reconfiguring a light emitting diode ("LED") array capable of using AC power.

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which various aspects of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the various aspects of the invention presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. The various aspects of the invention illustrated in the drawings may not be drawn to scale. In fact, the dimensions of the various features may be exaggerated or reduced for clarity. In addition, some of the drawings may be simplified for clarity. Accordingly, the drawings may not depict all of the components of a given apparatus (e.g., device) or method.

Various aspects of the invention will be described herein with reference to the accompanying drawings, which are schematic illustrations of idealized configurations of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, the various aspects of the invention presented throughout this disclosure should not be construed as limited to the particular shapes of elements (e.g., regions, layers, segments, substrates, etc.) illustrated and described herein, but are to include deviations in shapes that result, for example, from manufacturing. For example, an element illustrated or described as a rectangle may have rounded or curved features and/or gradient concentrations at its edges rather than discrete changes from one element to another. Thus, the elements illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of an element and are not intended to limit the scope of the present invention.

It will be understood that when an element such as a region, layer, section, substrate, etc., is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. It will also be understood that when an element is referred to as being "formed on" another element, it can be grown, deposited, etched, attached, connected, coupled, or otherwise prepared or fabricated on the other element or intervening elements.

In addition, relative terms (such as "lower" or "bottom" and "upper" or "top") may be used herein to describe one element's relationship to another element as illustrated in the figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as being on the "lower" side of other elements would then be oriented on "upper" sides of the other elements. The term "lower" may therefore encompass both an orientation of "lower" and "upper," depending on the particular orientation of the device. Similarly, if the device in the figures is inverted, elements described as "below" or "beneath" other elements would then be oriented "above" the other elements. The terms "below … …" or "below … …" may thus encompass orientations of "above … …" and "below … …".

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure.

As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The term "and/or" includes any and all combinations of one or more of the associated listed items.

Various aspects of LED luminaries will be presented. However, as those skilled in the art will readily appreciate, these aspects may be extended to aspects of LED luminaries without departing from the present invention. The LED luminary can be configured as a direct replacement for conventional luminaries (including, for example, recessed lights, surface mount lights, pendant lights, wall candlelight lights, recessed lights, track lighting, under counter lights, landscape or outdoor lights, floodlights, searchlights, street lights, flashlights, industrial lights, strip lights, industrial lights, emergency lights, arm lights, eye-catching lights, background lights, and other light fixtures).

As used herein, the term "luminaire" shall mean the housing or cover of a luminaire. The term "luminaire" shall mean a luminaire that is complete with the light source and other components (e.g., a fan for cooling the light source, a reflector for directing light, etc.), if desired. The term "LED luminary" shall mean a luminary having a light source comprising one or more LEDs. LEDs are well known in the art and will therefore only be discussed briefly to provide a complete description of the present invention.

It is also understood that aspects of the invention may comprise integrated circuits that may be readily fabricated using conventional semiconductor technology, such as CMOS ("complementary metal oxide semiconductor") technology or other semiconductor fabrication processes. In addition, aspects of the present invention may be implemented in other manufacturing processes for making optical as well as electrical devices. Reference will now be made in detail to embodiments of the exemplary aspects as illustrated in the accompanying drawings. The same reference indicators will be used throughout the drawings and the following detailed description to refer to the same or like parts.

A light emitting device is coupled in one aspect to a controller, a light emitting diode ("LED") array, and a power source, where the power source may be an alternating current ("AC") power source or an unregulated direct current ("DC") power source. Although the power supply provides electrical power, the controller generates various LED control signals in response to fluctuations in the electrical power. The LED array allows at least some of the LEDs to be activated according to the logic state of the LED control signal. LED reconfiguration within the LED array allows the LED system to draw power directly from the unregulated DC and/or AC power source.

FIG. 1 is a block diagram illustrating a lighting system 100 having a controller capable of controlling LEDs in accordance with an aspect of the present invention. The lighting system 100 includes a controller 102, an LED reconfiguration device 104, an LED array 106, and a power supply 108. The power supply 108 in one aspect is an AC, rectified AC, and/or unregulated DC power supply. It should be noted that the underlying concepts of the exemplary aspects of the present invention may not be changed if one or more elements (or devices) are added or removed from system 100.

The LED array 106 includes four (4) LEDs 120-126 coupled in series and capable of generating light. One or more of the LEDs 120 and 124 may be turned on and/or off based on the logic value (or logic state) of the LED control signal. For example, if a switch in the LED reconfiguration device 104 is turned off, the current 116 traveling from the controller 102 to the LED array 106 via the bus 132 is turned on. Additional LEDs may be added or removed from the LED array 106 depending on the application. In an alternative aspect, the LEDs in the LED array 106 may be organized in parallel or in a combination of series and parallel configurations.

The LED reconfiguration device 104 is a switching device capable of turning on or off individual LEDs within the LED array 106 depending on the logic state of the LED control signal. The device 104, in one aspect, includes three (3) switches 110 and 114, where each switch is controlled by an LED control signal. The LED control signal is generated by the controller 102. The LED control signal controls the switches 110 and 114 through the control terminals of the switches 110 and 114 via the switch control bus 134. As shown in FIG. 1, switches 110 and 114 are used to control LEDs 120 and 124, respectively. For example, if switch 110, which may include one or more transistors, is activated, switch 110 redirects current 116 from bus 132 to bus 138. When power travels from bus 132 to bus 138, bypassing LED120, LED 122 will be activated and LED120 will not be activated. In this way, the LED120 can be effectively turned on or off depending on the logic state of the LED control signal for the switch 110. It should be noted that the LED reconfiguration device 104 and the LED array 106 may be combined into a single device.

The controller 102 is a control circuit capable of performing various signal management functions such as current regulation, switching management, power monitoring, and the like. The controller 102, in one aspect, receives power from the power supply 108 via the bus 130, where the power may be AC power, unregulated DC power, or regulated DC power. After receiving power from bus 130, the power is forwarded to LED array 106 via bus 132 and/or bus 138. Power or electrical power is electrical energy that provides an electrical current and/or a potential difference. Upon detection of the electrical power, the controller 102 generates an LED control signal according to the potential fluctuation. In one aspect, the controller 102 selectively activates additional LEDs in the LED array 106 as the potential level increases. Similarly, the controller 102 selectively deactivates one or more LEDs when the potential level decreases. It should be noted that AC power delivers electrical power as a sine wave with fluctuating potential levels over time.

During operation, the controller 102 allows one (1), two (2), three (3), or four (4) LEDs to be turned on independently or simultaneously based on fluctuations in AC power. Note that the concept of having four (4) LEDs in an LED array can be extended to more individual LEDs or each LED comprising a plurality of sub-LEDs in series, parallel or a combination of series and parallel. Referring back to fig. 1, LED 126 (the last LED in the series) is normally on as long as current 116 flows through bus 132 to bus 136.

An advantage of using the reconfigurable LED array shown in diagram 100 is to allow the LED lighting fixture to draw AC power directly or unregulated DC power to generate light more efficiently and for a greater portion of the time without having a conventional AC to DC converter. To provide LEDs that can operate with unregulated DC or AC power, a controller of the reconfigurable LED array turns on and off a plurality of LEDs according to an applied voltage.

Fig. 2 is a block diagram illustrating a lighting system 200 having a reconfigurable LED array with a controller in accordance with an aspect of the present invention. The lighting system 200 includes a controller 202, a lighting component 240, and a power supply 208. Note that power supply 208 may be a device similar to power supply 108 as described in fig. 1. It should be noted that the basic concepts of the exemplary aspects of the present invention do not change if one or more elements (or layers) are added or removed from system 200.

The power supply 208 in one aspect is AC power provided by a utility company via conventional power transmission lines. Instead, the power source 208 is unregulated DC power provided by a generator. The power supply 208 supplies power (e.g., current 116) to the circuit. Power may be interpreted as a voltage, a potential difference, a current, or a combination of a current and a voltage. The terms "power", "electrical power", "current", "voltage" and "potential difference" are used interchangeably hereinafter. When the power 116 reaches the controller 202, it is then forwarded to the lighting device 240 via the bus 232.

A controller 202, capable of performing similar functions as the controller 102 described in fig. 1, monitors fluctuations in the power 116 and updates the LED control signal in response to the fluctuations in the power 116. The fluctuations in power or power fluctuations are, for example, power rises and falls as in the waves or sine waves conveyed on the bus 130. Upon detecting a power fluctuation, the LED control signal is adjusted in accordance with the power fluctuation. For example, controller 202 turns on more LEDs as the power level rises and it turns off one or more LEDs as the power level falls. Note that AC power delivers electrical power as a sine wave that fluctuates over time.

The LED control signal controls the switch through its control terminal via bus 234, where the switch controls the state of each LED in lighting component 240. The control terminal for each switch is for example the gate terminal of a transistor. To simplify diagram 200, switch control bus 234, which carries LED control signals, is not shown. The controller 202 is able to individually access and/or control each LED, whereby the on-time or activation period for the LEDs may be more evenly distributed.

The lighting component 240 in one aspect includes an array of LEDs 242 and a switch 210 and 226, where the switch is used to control the on or off state of each LED in the LED array 242. The LED array 242 includes a plurality of LEDs 202 and 208, wherein the LEDs 202 and 208 are connected in series. Each LED within LED array 242 is controlled by a pair of switches. For example, LED202 is controlled by switches 210 and 218. Since the switch is governed by the LED control signal, the LEDs 202 and 208 may be turned on and/or off based on the logic value of the LED control signal. When switches 210 and 218 are on (or active), LED202 will be turned off, for example, because the voltage difference across LED202 drops to zero. Instead, when switches 210 and 220 are turned on and switches 218 and 212 are turned off, current 116 flows from switch 210 to LED 204 and then to switch 220, thereby activating and/or illuminating LED 204.

Additional LEDs may be added or removed from LED array 242 depending on the application. The LEDs 202-208 may be organized in parallel or in a combination of series and parallel configurations. The lighting component 240 (which may be a device similar to the LED reconfigurable device 104 shown in fig. 1) includes a set of switching devices and LEDs for reconfiguring the LEDs according to power fluctuations. During operation, the controller 202 allows one (1), two (2), three (3), four (4), etc. to be turned on or off independently of each other based on fluctuations in the AC power.

An advantage of using the reconfigured device described in fig. 200 when compared to fig. 100 is to improve reliability by more evenly distributing the time for any particular LED to turn on or be active. Instead, a similar topology using fewer switches at the expense of voltage loss in the switches may be instantiated in the discussion below.

Fig. 3 is a block diagram illustrating another topology or layout of a lighting system 300 having a reconfigurable LED array with a controller in accordance with an aspect of the present invention. The lighting system 300 includes a controller 202, an LED reconfigurable device 304, an LED array 342, and a power supply 108, wherein the LED array 242 includes a plurality of LEDs 302 and 308. The power supply 108 in one aspect is an AC, rectified AC, and/or unregulated DC power supply. It should be noted that the basic concepts of the exemplary aspects of the present invention do not change if one or more elements (or LEDs) are added or removed from or in diagram 300.

The LED reconfiguration device 304 includes a plurality of switches 318 and 326, where each switch includes one or more transistors. The gate or control terminal of the switch is coupled with an LED control signal via bus 234 for controlling the logic state of each switch. Each switch is associated with an LED, wherein an LED is turned off when its associated switch is on or active. For example, if switch 318 is turned on, the voltage difference across LED 302 drops to zero, thereby turning off LED 302. Instead, when switches 318 and 324 are on and switch 320 is off, current 116 flows from switch 318 to LED 304 and then from LED 304 to switch 324, thereby activating LED 304. Note that current 116 needs to pass through the switch chain from switch 318 to switch 316 to reach the negative terminal of power supply 108. It should be noted that power losses may occur in the lighting system 300 as the current 116 travels through each switch.

Fig. 4A is a block diagram illustrating a lighting system 400 using a reconfigurable LED array having H-bridge operation in accordance with an aspect of the present invention. Lighting system 400 includes controller 202, lighting component 401, and power supply 108. Lighting system 400 is similar to lighting system 200 shown in fig. 2, except that lighting component 401 is different from lighting component 240 shown in fig. 2. It should be noted that the basic concepts of the exemplary aspects of the present invention do not change if one or more elements (or LEDs) are added or removed from the lighting system 400.

The lighting component 401 includes a plurality of LEDs 402 and switches 412 and 436, where the switches 412 and 416 perform similar functions as the switches 210 and 226. In one aspect, the LEDs are coupled in series, with a switch between every two series-connected LEDs. Such as switch 430, is placed between LEDs 402 and 404. Having a switch placed between every two LEDs enables the controller 202 to reconfigure the LEDs in parallel as well as in series. The added switches (such as switch 430) along with 436 facilitate H-bridge operation and allow the circuit to run on AC power.

Although the reconfigured circuitry including switch 412 and 436 is more complex than that shown in fig. 2-3, it allows the LEDs to be operated in series (or series) or in parallel. For an array of four (4) LEDs using the circuit layout shown in FIG. 4A, the reconfigured circuitry allows the LEDs to be reconfigured into the following configuration: a string of four (4) LEDs; a string of three (3) LEDs in two different ways; a string of two (2) LEDs in three different ways; connecting two strings of two (2) LEDs in parallel in a manner; and from one to four individual LEDs connected in parallel. If lighting component 401 is configured as four LEDs, two strings of two (2) LEDs in parallel may be configured and formed. For example, when the switches 430, 422, 414, 434, and 426 are closed (or on) and the switches 412, 420, 432, 416, 424, and 436 are open (off), the first string of LEDs 402 and 404 is connected in parallel with the second string of LEDs 406 and 408. The first way of a string of three LEDs 402 and 406 may also be formed when the switches 430, 432, and 424 are closed (or on) and the open tubes 412, 414, 434, 420, and 422 are open (or off). Alternatively, a second way of a string of three LEDs 404 and 408 may be formed when switches 412, 432, 434, and 426 are closed (or on) and switches 430, 414, 416, 436, and 420 and 424 are open (or off).

4B-4D illustrate three (3) lighting systems with four (4) LEDs, showing different LED configurations 460 and 480 in response to fluctuations in electrical power, according to an aspect of the present invention. Switches or switching devices organized in an H-bridge topology as shown in fig. 4A may be used to generate various LED configurations. While configuration 460 illustrates, for example, four strings of one LED in parallel, configuration 470 illustrates two strings of two LEDs in parallel. Configuration 480, on the other hand, depicts a configuration of one string of four LEDs.

The configuration 460 and 480 shown in fig. 4B-4D enables efficient operation of the LED array and allows the LED array to deliver the same amount of light at various input voltages. Fig. 4B-4D schematically illustrate a circuit arrangement with an array of four LEDs. Fig. 4B shows an LED array configured with four (4) individual LEDs in parallel. During periods of low voltage (i.e., 3.2V for blue LEDs), configuration 460 may draw a high current (i.e., 1.4A) and each LED will consume a constant power (i.e., 1.2W) and deliver an associated amount of light. When the power supply is at a moderate voltage (i.e., 6.4V), the LED array is reconfigured into two (2) strings of two (2) LEDs in parallel and draws half the current (i.e., 0.7A) of the configuration 470 shown in fig. 4C. Configuration 470 still delivers the same power (i.e., 1.2W) to each LED and will provide the same amount of light with the same efficiency as configuration 460 shown in fig. 4B. Instead, when the power supply reaches a high voltage (i.e., 13.2V), the LED array is reconfigured into a string of four (4) LEDs as shown in fig. 4D and draws a quarter current (i.e., 0.35A) of the configuration 460 shown in fig. 4B. Configuration 480 also delivers the same or similar power (i.e., 1.2W) to each LED and provides the same amount of light with the same efficiency as configurations 460-470 shown in fig. 4B-4C. It should be noted that as the potential ("voltage") increases, the number of active LEDs remains the same and the delivered electrical power is the same while the LED configuration changes according to the output of the potential. In some applications, it is beneficial to turn off the LED when the electrical power is rising and turn on the LED when the electrical power is decreasing.

The reconfigured circuitry shown in fig. 4 allows for an LED array and/or LED system that is compatible with the applied voltage with dynamic real-time control (which is facilitated by controller 202). The controller 202, which may be an external circuit, is integrated into the LED module. The advantage of using such an LED module is to allow the LED array to operate without the need for an AC to DC converter. Another advantage of using an LED module is the elimination of electrolytic capacitors from the system, as electrolytic capacitors tend to reduce the lifetime of the system.

FIG. 5 illustrates an example AC LED topology 550 showing a reconfigurable LED array in accordance with an aspect of the present invention. Topology 550 includes power supply 552, rectifier 554, controller 556, and reconfigurable LED array 558. The controller 556, in one aspect, comprises a switch controller and a current controller, wherein the switch controller is capable of managing the switches. The current controller is capable of forwarding current from rectifier 554 to reconfigurable LED array 558. It should be noted that the basic concepts of the exemplary aspects of the present invention do not change if one or more elements (or LEDs) are added or removed from or from diagram 550.

Rectifier 554 includes four (4) diodes capable of blocking the negative and/or positive portions of the waveform. Any other type of power rectifier may be used in place of rectifier 554. The power supply 552 may be an AC power source supplied by a utility company via a power cable. Instead, the power source 552 is unregulated DC power provided by a generator.

Reconfigurable LED array 558 includes three (3) switches 570-. Note that switches 570-574 are similar to switches 110-114 shown in FIG. 1 and LEDs 560-568 are similar to LEDs 120-126 shown in FIG. 1. The LEDs 568 are turned on most of the time, and the LEDs 560-. The logic states of switches 570-576 are controlled by LED control signals that are controlled and/or managed by controller 556.

An advantage of using topology 550 is to allow the LEDs to draw power directly from an AC or unregulated power source without AC to DC conversion.

To measure the performance of an LED lighting system, the measurement covers various parameters (such as flux, power factor and efficiency). The ideal flux rate is approximately 880lm, while the required power factor is greater than 0.9. For example, if an individual LED produces 75lm/W of cool white light with a current of 700mA and a forward voltage of 3.2V, it may produce a flux of approximately 175 lm. If the flux and efficiency are maintained within a predefined range, the forward voltage (in increments of 3.2V) and current are reshaped, whereby the power density remains approximately constant. Thus, an LED can produce 175lm of flux with a forward voltage of 6.4V and 350mA, or 9.6V and 267mA, or 12.8V and 175mA, etc.

In one example, the efficiencies include LED efficiency, system efficiency, and AC to DC efficiency. The following lists the definitions of efficiency.

To achieve a high power factor, the delivered line current should be, for example, in phase with the line voltage. The power delivered to the system will then be approximated as the square of a sine function with a mean peak ratio of 0.5. To obtain 880lm average flux, the LEDs need to produce 1760lm at peak, for example, which means that the lighting system may need to have at least ten (10) LEDs to meet the flux requirement. For example, at a peak AC line voltage of 170V, an LED or group of LEDs should have a forward voltage of 16V at a current of 140 milliamps ("mA"). Note that if the circuit includes an inline resistor, the difference between the LED voltage and the line voltage should be kept low to improve system efficiency.

FIG. 6 is a block diagram illustrating an example implementation of an AC LED topology 650 with a reconfigurable LED array in accordance with an aspect of the present invention. Similar to topology 550 shown in fig. 5, topology 650 includes a power supply 652, a rectifier 554, a controller 556, and a reconfigurable LED array 558. Note that additional LEDs and switches may be added to reconfigurable LED array 558. It should be noted that the basic concepts of the exemplary aspects of the present invention do not change if one or more elements (or LEDs) are added or removed from or from diagram 650.

When power supply 652 increases the voltage from 0 volts ("V") to 3-6V, a variable forwarding current is forwarded from rectifier 554 to controller 556. Upon detection of a forward voltage of 3-6V, the switch controller sends an LED control signal to activate switch 572. When switches 570-572 are not activated but switch 574 is activated, the forward current bypasses LEDs 560-564 and reaches LED 568 directly through switch 574 via connection 656. Luminaires employing variable voltage forward LED packages can maintain a minimum voltage difference between the power supply and the LEDs by activating or deactivating the LEDs as needed. Depending on the application, more complex switching circuits may be used to provide additional flexibility for LED reconfiguration.

FIG. 7 is a block diagram illustrating an example implementation of an AC LED topology 750 with reconfigurable LED arrays in accordance with an aspect of the present invention. Similar to topology 550 shown in fig. 5, topology 750 includes power supply 752, rectifier 554, controller 556, and reconfigurable LED array 558. Note that additional LEDs and switches may be added to reconfigurable LED array 558. It should be noted that the basic concepts of the exemplary aspects of the present invention will not change if one or more elements (or LEDs) are added or removed from diagram 750.

When power supply 752 increases the voltage from 3-6V to 6-9V, the variable forwarding voltage is forwarded from power rectifier 554 to controller 556. Upon detection of a forward voltage of 6-9V, the switch controller sends an LED control signal that activates switch 572. When switches 570 and 574 are not activated but switch 572 is active, the forwarded voltage or current bypasses LEDs 560-. Luminaires employing variable voltage forwarding LED packages can maintain a minimum voltage difference between the power supply and the LEDs by activating or deactivating the LEDs as needed.

FIG. 8 is a block diagram illustrating an example implementation of an AC LED topology 850 with a reconfigurable LED array in accordance with an aspect of the present invention. Similar to topology 550 shown in fig. 5, topology 850 includes a power supply 852, a rectifier 554, a controller 556, and a reconfigurable LED array 558. Note that additional LEDs and switches may be added to reconfigurable LED array 558. It should be noted that the basic concepts of the exemplary aspects of the present invention do not change if one or more elements (or LEDs) are added or removed from or in diagram 850.

When the power supply 852 increases the voltage from 6-9V to 9-12V, the variable forwarding voltage is forwarded from the power rectifier 554 to the controller 556. Upon detection of the 9-12V forward voltage, the switch controller sends an LED control signal that activates switch 570. When switches 572-574 are not activated but switch 570 is activated, the forward current bypasses LED 560 and passes through switch 570 via connection 856 to LED 562-568.

Another application of reconfigurable LED arrays is to provide an alternative to dimming via current modulation. Conventional LED dimming approaches focus on modulating the current through the LED in time or in amplitude. In general, voltage dimming for conventional LEDs is not preferred, since only a small voltage change causes a large light output change. With a reconfigurable LED array, stepped voltage dimming can be performed by turning on the LEDs when the electrical power increases and turning off the LEDs when the electrical power decreases.

FIG. 9 is a block diagram illustrating an example implementation of an AC LED topology 950 having a reconfigurable LED array in accordance with an aspect of the present invention. Similar to topology 550 shown in fig. 5, topology 950 includes a power supply 952, a rectifier 554, a controller 556, and a reconfigurable LED array 558. Note that additional LEDs and switches may be added to reconfigurable LED array 558. It should be noted that the basic concepts of the exemplary aspects of the present invention do not change if one or more elements (or LEDs) are added or removed from diagram 950.

When power supply 952 increases the voltage from 9-12V to greater than 12V, the variable forwarding voltage is forwarded from rectifier 554 to controller 556. Upon detecting a voltage greater than the 12V forwarding voltage, the switch controller turns off all switches 570-574 via the LED control signals. When the switches 570-574 are not activated, the forward current reaches the LEDs 560-568 via connection 956. It should be noted that additional switches and LEDs may be included if higher forward voltages are present.

FIG. 10 is a graph 1006 showing a set of graphs illustrating the performance of delivering power to a lighting system using a reconfigurable LED array according to an aspect of the present invention. The graph 1006 includes a voltage graph 1000, a current graph 1002, and a power graph 1004. The data collected and plotted on graph 1000 and 1004 is based on a set of predefined parameters such as power factor and flicker index. The flicker index measures the amount of light above the average amount of light. The power factor provides the ratio of the actual power applied to the load to the apparent power. The graph 100-104 is drawn under the following conditions: the power factor is equal to 0.995; flicker index is equal to 0.34; there are 50 junctions above 160V.

Graph 1000 illustrates in the time domain a line voltage curve 1010, a voltage curve 1012 across the LEDs, and a voltage loss curve 1014. The curves 1010-1014 plotted in the graph 1000 demonstrate that the lighting system is quite efficient because the voltage curve 1012 across the LED is similar to the line voltage curve 1010. Also, the voltage loss curve 1014 is relatively small compared to the voltage curve 1012 across the LED.

Graph 1002 illustrates a plot showing a line current curve 1020 in the time domain. Note that voltage loss 1014 represents the unrecoverable approximate power loss of the circuitry somewhere in the system. The power delivered to the LEDs plotted over a period is shown in graph 1004. Graph 1004 shows a line power curve 1030, a power delivered to the LED curve 1032, and a power loss curve 1034. Graph 1004 illustrates that the power delivered to the system is relatively efficient because the power curve 1032 delivered is very close to the line power curve 1030. Also, the power loss curve 1034 is relatively small compared to the delivered power curve 1032. Thus, an advantage of using a reconfigurable LED array is to provide an LED system that can be operated with AC, rectified AC, and/or unregulated DC power.

Fig. 11 is a block diagram 1100 illustrating a control circuit (such as the controller 202 shown in fig. 2) for controlling a reconfigurable LED array in accordance with an aspect of the present invention. Diagram 1100 includes an AC power source, a wave rectifier 1102, resistors R1-R2, LED1, LED2, transistors U1-U5, and a reference LED. It should be noted that the underlying principles of the exemplary aspects of the present invention do not change if one or more elements (or devices) are added or removed from or in diagram 1100.

Diagram 1100 is a circuit capable of performing tasks on a dual LED system. The wave rectifier 1102 is for AC line voltage. R1 and R2 facilitate current flow through transistor U2 and the current is in phase with the line voltage. Transistor U1 mirrors the current through U2 in a standard current mirror topology. The transistor U3 is capable of shorting across the LED2 when the drain voltage of U5 is greater than the voltage set by the voltage divider made up of R1 and R2. The comparator U4, also referred to as a differential amplifier, becomes active and pulls down the U3 before the U1 and LED1 turn on. In one example, it may be advantageous to have a large forward voltage for the LED 1. To provide a suitable voltage for switching, a small reference LED is placed at the drain of U5. It should be noted that the switching circuit comprising U3, U4 and the resistor network may be repeated for LED arrays having more than two (2) LEDs. Note that the requirement may be that any comparator must operate over a significant range of supply voltages.

Example aspects of the invention include various processing steps that will be described below. The steps of this aspect may be embodied in machine or computer executable instructions. The instructions may be used to cause a general-purpose or special-purpose system, which is programmed with the instructions to perform the steps of the exemplary aspects of the present invention. Alternatively, the steps of the exemplary aspects of the present invention may be performed by specific hardware components that contain hardwired logic for performing the steps, or by any combination of programmed computer components and custom hardware components.

FIG. 12 is a flow chart 1200 illustrating a process for reconfiguring an LED array using a controller in accordance with an aspect of the present invention. At block 1202, a process for generating light receives electrical power from a power source. The process in one aspect can receive power from an AC power source.

At block 1204, the process can monitor fluctuations in the electrical power. Voltage fluctuations and/or current fluctuations of the AC power source may be detected.

At block 1206, the process generates an LED control signal in response to power fluctuations in the electrical power. In one aspect, the process can reconfigure the LED array according to a plurality of LED control signals.

At block 1208, the process activates at least some of the LEDs of the LED array according to the logic state of the LED control signal. After dynamically updating the logic state of the LED control signal in accordance with the dynamic fluctuations in electrical power, the process dynamically activates and/or deactivates the LEDs of the LED array in response to the logic state of the LED control signal. Depending on the application, some switches are positively enabled and others are negatively enabled. Positive enable means that the switch is triggered or switched on (or closed), e.g. by an active state of the control signal, whereas negative enable means that the switch is triggered and switched on by an inactive state of the control signal. The active and/or inactive states of the control signals may be implemented by digital processing circuitry, analog processing circuitry, or fixed signal processing circuitry.

The active and inactive states are also referred to in some digital processing applications as logical "1" and logical "0" states, respectively. In one aspect, an active state or logic "1" state means a high voltage state, and an inactive state or logic "0" state means a low voltage state. Depending on the application, the active state or logic "1" state may instead be configured as a low voltage state, while the inactive state or logic "0" state may be configured as a high voltage state. For example, the process can set an additional active state of the LED control signal when the electrical power is increased. On the other hand, the process can also set an additional inactive state of the LED control signal when the electrical power is reduced.

Having briefly described aspects of lighting systems capable of directly extracting AC and/or unregulated DC power using a reconfigurable LED array in which the present invention operates, the following figures illustrate example processes and/or methods for fabricating and packaging LED dies, chips, devices, and/or luminaires.

Fig. 13 is a conceptual cross-sectional view illustrating an example fabrication process of an LED or LED device. LEDs are semiconductor materials that are impregnated or doped with impurities. These impurities add "electrons" or "holes" to the semiconductor that can move relatively freely in the material. Depending on the impurity species, the doped regions of the semiconductor may have mainly electrons or holes and are referred to as n-type or p-type semiconductor regions, respectively. Referring to fig. 13, the LED 500 includes an n-type semiconductor region 504 and a p-type semiconductor region 508. The junction between the two regions creates a reverse electric field that moves electrons and holes away from the junction to form active region 506. When a forward voltage sufficient to overcome a reverse electric field is applied across the p-n junction through a pair of electrodes 510, 512, electrons and holes are forced into the active region 506 and recombine. When electrons recombine with holes, they drop to a lower energy level and release energy in the form of light.

In this example, an n-type semiconductor region 504 is formed on the substrate 502 and a p-type semiconductor region 508 is formed on the active layer 506, although the regions may be reversed. That is, the p-type semiconductor region 508 may be formed on the substrate 502, and the n-type semiconductor region 504 may be formed on the active layer 506. As those skilled in the art will readily appreciate, the various concepts described throughout this disclosure may be extended to any suitable hierarchical structure. Additional layers or regions (not shown) including, but not limited to, buffer, nucleation, contact and current spreading layers or regions and light extraction layers may also be included in the LED 500.

The p-type semiconductor region 508 is exposed at the top surface, and thus the p-type electrode 512 can be easily formed thereon. Whereas the n-type semiconductor region 504 is buried under the p-type semiconductor layer 508 and the active layer 506. Thus, to form the n-type electrode 510 on the n-type semiconductor region 504, a cut-out region or "mesa" (mesa) is formed by removing portions of the active layer 506 and the p-type semiconductor region 508 by means well known in the art to expose the n-type semiconductor layer 504 thereunder. After removing this portion, an n-type electrode 510 may be formed.

Fig. 14 is a conceptual cross-sectional view illustrating an example of an LED having a phosphor layer. In this example, a phosphor layer 602 is formed on the top surface of the LED 500 by means well known in the art. The phosphor layer 602 converts a portion of the light emitted by the LED 500 into light having a different spectrum than the spectrum of the light emitted from the LED 500. A white LED light source may be constructed by using an LED that emits light in the blue region of the spectrum and a phosphor that converts blue light to yellow light. White light sources are well suited as replacement lamps for conventional luminaries; however, the invention can be implemented with other LED and phosphor combinations to produce different colors of light. The phosphor layer 602 may, for example, comprise phosphor particles suspended in a carrier or be constructed from soluble phosphor dissolved in a carrier.

In the configuration of LED luminaries, an array of LEDs may be used to provide increased luminosity. Fig. 15A is a conceptual top view illustrating an example of an LED array, and fig. 15B is a conceptual cross-sectional view of the LED array of fig. 15A. In this example, a plurality of phosphor coated LEDs 600 may be formed on a substrate 702. Bond wires (not shown) extending from the LEDs 600 may be connected to traces (not shown) on the surface of the substrate 702 that connect the LEDs 600 in parallel and/or series. In general, the LEDs 600 may be connected in parallel streams of series LEDs with a current limiting resistor (not shown) in each stream. Substrate 702 can be any suitable material that can provide support to LED 600 and that can fit within a luminaire (not shown).

Fig. 16A is a conceptual top view illustrating an example of an alternative configuration of an LED array, and fig. 16B is a conceptual cross-sectional view of the LED array of fig. 16A. In a manner similar to that described in connection with fig. 15A and 15B, a substrate 702 designed for assembly in a luminaire (not shown) may be used to support an array of LEDs 500. In this configuration, however, a phosphor layer is not formed over each individual LED. Instead, the phosphor 806 is deposited within the cavity 802 defined by an annular ring 804 extending circumferentially around the outer surface of the substrate 702. The annular ring 804 may be formed by drilling a cylindrical hole in the material forming the substrate 702. Alternatively, the substrate 702 and annular ring 804 may be formed with suitable molds, or the annular ring 804 may be formed separately from the substrate 702 and attached to the substrate using an adhesive or other suitable means. In the latter configuration, the annular ring 804 is generally attached to the base 702 before the LED 500; however, in some configurations, the LEDs may be attached first. Once the LED 500 and annular ring 804 are attached to the substrate 702, a suspension of phosphor particles in a carrier may be introduced into the cavity 802. The carrier material may be an epoxy or silicone; however, carriers based on other materials may also be used. The carrier material may be cured to produce a solid material in which the phosphor particles are fixed.

Fig. 17 illustrates an example apparatus including an LED or LED device fabricated by laser scribing in accordance with some aspects of the present invention. The device 900 includes a light 902, a lighting device 904, and a street light 906. Each of the devices shown in fig. 17 includes at least LEDs or LED devices separated via laser scribing techniques as described herein. For example, the lamp 902 includes a package 916 and LEDs 908, where the LEDs 908 are separated using laser scribing at a location toward the back side of the device. The lamp 902 may be used for any type of general lighting. For example, the lamp 902 may be used in a headlamp, a street light, a dome light, or any other general lighting application. Lighting device 904 includes a power supply 910 electrically coupled to a lamp 912 (which may be configured as lamp 902). In one aspect, the power supply 910 may be a battery or any other suitable type of power supply (such as a solar cell). The street light 906 includes a power supply connected to a lamp 914 (which may be configured as the lamp 902). It should be noted that the aspects of the LEDs described herein are suitable for use with virtually any type of LED assembly, which in turn can be used in any type of lighting device and are not limited to the device shown in fig. 17.

Various aspects of the disclosure are provided to enable one of ordinary skill in the art to practice the invention. Various modifications to the aspects presented throughout this disclosure will be readily apparent to those skilled in the art, and the concepts disclosed herein may be extended to other LED lamp configurations regardless of the shape or diameter of the glass cover and base, and the arrangement of electrical contacts on the lamp. Thus, the claims are not intended to be limited to the various aspects of the disclosure, but are to be accorded the full scope consistent with the language of the claims. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. Unless a claim element is explicitly recited using the phrase "… … means for" or in the case of method claims, the element is not to be construed as specified in 35 u.s.c. § 112 sixth paragraph unless the element is recited using the phrase "step for … …".

Claims (11)

1. A light emitting device comprising:

a controller configured to simultaneously generate a plurality of Light Emitting Diode (LED) control signals in response to electrical power; and

an LED array comprising a plurality of LEDs coupled to the controller and configured to selectively activate or deactivate each of the plurality of LEDs according to a logic state of a control signal for the plurality of LEDs.

2. The apparatus of claim 1, further comprising: an LED reconfigurable device coupled to the controller and configured to include a plurality of switches capable of selectively activating at least one LED of the LED array in response to an active state of one of the plurality of LED control signals.

3. The apparatus of claim 1, further comprising: an LED reconfigurable apparatus coupled to the controller and configured to include a plurality of switches capable of selectively deactivating at least one LED of the LED array in response to an inactive state of the plurality of LED control signals.

4. The apparatus of claim 1, further comprising a power supply configured to provide the electrical power and a power monitor to detect fluctuations in the electrical power, the controller activating or deactivating the LED in response to the fluctuations in the electrical power.

5. The apparatus of claim 4, wherein the power source provides Alternating Current (AC) electrical power.

6. The apparatus of claim 4, wherein the power supply is an unregulated Direct Current (DC) power supply.

7. A method of generating light with a light source having an LED array comprising a plurality of LEDs powered by a power source, the method comprising:

monitoring power fluctuations of the electrical power of the power source;

simultaneously generating a plurality of Light Emitting Diode (LED) control signals in response to power fluctuations of the electrical power; and

selectively activating or deactivating each LED of the plurality of LEDs in the LED array according to a logic state of the plurality of LED control signals in response to the dynamic fluctuation of electrical power.

8. The method of claim 7, wherein monitoring the power fluctuations of the electrical power comprises: voltage fluctuations generated by an Alternating Current (AC) power source are detected.

9. The method of claim 7, wherein generating a plurality of LED control signals in response to power fluctuations of the electrical power further comprises: reconfiguring the LED array according to the power fluctuation.

10. A Light Emitting Diode (LED) lamp comprising:

packaging; and

an LED device coupled to the package and comprising:

a controller configured to simultaneously generate a plurality of Light Emitting Diode (LED) control signals in response to electrical power; and

an LED array coupled to the controller and configured to allow at least some of the LEDs to be activated according to a logic state of the plurality of LED control signals.

11. The lamp of claim 10, wherein the LED arrangement is coupled to the package and further comprising an LED reconfigurable device coupled to the controller and configured to include a plurality of switches configured to activate at least one LED of the LED array in response to an active state of one of the plurality of LED control signals.