EP3729912A1

EP3729912A1 - Illumination system including tunable light engine

Info

Publication number: EP3729912A1
Application number: EP18830992.6A
Authority: EP
Inventors: Yifeng QIU
Original assignee: Lumileds LLC
Current assignee: Lumileds LLC
Priority date: 2017-12-20
Filing date: 2018-12-20
Publication date: 2020-10-28
Anticipated expiration: 2038-12-20
Also published as: CN111713180A; CN115297587B; TW201933644A; KR20200098660A; TWI704707B; JP6942257B2; TWI764228B; CN111713180B; EP3729912B1; WO2019126583A1; JP2021507473A; KR102501197B1; CN115297587A; TW202044923A

Abstract

An illumination system is disclosed that provides a control signal interface configured to provide a voltage control signal via a control channel. A light engine is provided and includes a first signal generator configured to provide a first pulse-width modulated (PWM) signal based on the control signal, via a first channel, a second signal generator configured to provide a second PWM signal based on the control signal, via a second channel, and a third signal generator configured to provide a third PWM signal based on the first PWM signal and the second PWM signal, via a third channel.

Description

ILLUMINATION SYSTEM INCLUDING TUNABLE LIGHT ENGINE

FIELD

[0001] The present disclosure relates to light emitting devices in general, and more particularly, to an illumination system including a light engine.

BACKGROUND

[0002] Light emitting diodes (“LEDs”) are commonly used as light sources in various applications. LEDs are more energy-efficient than traditional light sources, providing much higher energy conversion efficiency than incandescent lamps and fluorescent light, for example. Furthermore, LEDs radiate less heat into illuminated regions and afford a greater breadth of control over brightness, emission color and spectrum than traditional light sources. These characteristics make LEDs an excellent choice for various lighting applications ranging from indoor illumination to automotive lighting.

SUMMARY

[0003] An illumination system is disclosed that provides a control signal interface configured to provide a voltage control signal via a control channel. A light engine is provided and includes a first signal generator configured to provide a first pulse-width modulated (PWM) signal based on the control signal, via a first channel, a second signal generator configured to provide a second PWM signal based on the control signal, via a second channel, and a third signal generator configured to provide a third PWM signal based on the first PWM signal and the second PWM signal, via a third channel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The drawings described below are for illustration purposes only. The drawings are not intended to limit the scope of the present disclosure. Like reference characters shown in the figures designate the same parts in the various embodiments.

[0005] FIG. 1 is a schematic diagram of an illumination system, according to aspects of the disclosure;

[0006] FIG. 2 is a schematic diagram of an example of a PWM signal generator, according to aspects of the disclosure;

[0007] FIG. 3 is a diagram of an example of a PWM signal that is generated by the PWM signal generator of FIG. 2, according to aspects of the disclosure; [0008] FIG. 4 is a graph illustrating the response of the PWM generator of FIG. 2 to changes in control voltage, according to aspects of the disclosure;

[0009] FIG. 5 is a diagram of an example of an illumination system, according to aspects of the disclosure;

[0010] FIG. 6A is a plot illustrating the relationship between different PWM signals, according to aspects of the disclosure, according to aspects of the disclosure;

[001 1] FIG. 6B is a plot illustrating the relationship between different PWM signals, according to aspects of the disclosure, according to aspects of the disclosure, according to aspects of the disclosure;

[0012] FIG. 7 is a plot illustrating the operation of the illumination system of FIG. 5, in accordance with one possible configuration;

[0013] FIG. 8 is a plot illustrating the operation of the illumination system of FIG. 5, in accordance with another possible configuration;

[0014] FIG. 9 is a plot illustrating the relationship between different control signals in the illumination system of FIG. 5, according to aspects of the disclosure;

[0015] FIG. 10 is a flowchart of an example of a process, according to aspects of the disclosure;

[0016] Fig. 1 1 is a top view of an electronics board for an integrated LED lighting system according to one embodiment;

[0017] Fig. 12A is a top view of the electronics board with LED array attached to the substrate at the LED device attach region in one embodiment;

[0018] Fig. 12B is a diagram of one embodiment of a two channel integrated LED lighting system with electronic components mounted on two surfaces of a circuit board;

[0019] FIG. 12C is a diagram of an embodiment of an LED lighting system where the LED array is on a separate electronics board from the driver and control circuitry;

[0020] FIG. 12D is a block diagram of an LED lighting system having the LED array together with some of the electronics on an electronics board separate from the driver circuit;

[0021] FIG. 12E is a diagram of example LED lighting system showing a multi-channel LED driver circuit;

[0022] Fig. 13 is a diagram of an example application system;

[0023] FIG. 14A is a diagram showing an LED device; and

[0024] FIG. 14B is a diagram showing multiple LED devices. DETAILED DESCRIPTION

[0025] Examples of different light illumination systems and/or light emitting diode (“LED”) implementations will be described more fully hereinafter with reference to the accompanying drawings. These examples are not mutually exclusive, and features found in one example may be combined with features found in one or more other examples to achieve additional implementations. Accordingly, it will be understood that the examples shown in the accompanying drawings are provided for illustrative purposes only and they are not intended to limit the disclosure in any way. Like numbers refer to like elements throughout.

[0026] It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms may be used to distinguish one element from another. For example, a first element may be termed a second element and a second element may be termed a first element without departing from the scope of the present invention. As used herein, the term "and/or" may include any and all combinations of one or more of the associated listed items.

[0027] It will be understood that when an element such as a layer, region, or substrate is referred to as being "on" or extending "onto" another element, it may be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" or extending "directly onto" another element, there may be no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element and/or connected or coupled to the other element via one or more intervening elements. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present between the element and the other element. It will be understood that these terms are intended to encompass different orientations of the element in addition to any orientation depicted in the figures.

[0028] Relative terms such as "below," "above," "upper,", "lower," "horizontal" or "vertical" may be used herein to describe a relationship of one element, layer, or region to another element, layer, or region as illustrated in the figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0029] Further, whether the LEDs, LED arrays, electrical components and/or electronic components are housed on one, two or more electronics boards may also depend on design constraints and/or application. [0030] Semiconductor light emitting devices (LEDs) or optical power emitting devices, such as devices that emit ultraviolet (UV) or infrared (IR) optical power, are among the most efficient light sources currently available. These devices (hereinafter“LEDs”), may include light emitting diodes, resonant cavity light emitting diodes, vertical cavity laser diodes, edge emitting lasers, or the like. Due to their compact size and lower power requirements, for example, LEDs may be attractive candidates for many different applications. For example, they may be used as light sources (e.g., flash lights and camera flashes) for hand-held battery-powered devices, such as cameras and cell phones. They may also be used, for example, for automotive lighting, heads up display (HUD) lighting, horticultural lighting, street lighting, torch for video, general illumination (e.g., home, shop, office and studio lighting, theater/stage lighting and architectural lighting), augmented reality (AR) lighting, virtual reality (VR) lighting, as back lights for displays, and IR spectroscopy. A single LED may provide light that is less bright than an incandescent light source, and, therefore, multi-junction devices or arrays of LEDs (such as monolithic LED arrays, micro LED arrays, etc.) may be used for applications where more brightness is desired or required.

[0031] Tunable illumination is highly desirable in consumer and commercial lighting. A tunable illumination system is usually able to change its color and brightness independently of one another. According to aspects of the disclosure, a tunable illumination system is disclosed which splits a single channel output into three by means of current steering and/or time division and multiplexing techniques. More particularly, the tunable light system may split the input current into three pulse- width modulated (PWM) channels. The individual duty cycles of the PWM channels may be adjusted based on a control signal that is received via a control signal interface. The control signal interface may include a switch and/or other circuity that is manipulated by the user when the user wants to change the color of light that is output by the illumination system.

[0032] According to aspects of the disclosure, an illumination system is disclosed, comprising: a first signal generator configured to generate a first pulse-width modulated (PWM) signal based on a first control signal; a second signal generator configured to generate a second PWM signal based on a difference in voltage between a reference signal and the first control signal; a third signal generator configured to generate a third PWM signal based on the first PWM signal and the second PWM signal, the third PWM signal having a different duty cycle than at least one of the first PWM signal and the second PWM signal; a first light emitting diode (LED) that is powered using the first PWM signal, the first LED being configured to emit a first type of light; a second LED that is powered using the second PWM signal, the second LED having a second CCT, the second LED being configured to emit a second type of light; and a third LED that is powered using the third PWM signal, the third LED being configured to emit a third type of light. [0033] According to aspects of the disclosure, a method is disclosed for operating an illumination system, comprising: generating a first pulse-width modulated (PWM) signal based on a first control signal; generating a second PWM signal based on a difference between a reference signal and the first control signal; generating a third PWM signal based on the first PWM signal and the second PWM signal, the third PWM signal having a different duty cycle than at least one of the first PWM signal and the second PWM signal; controlling a first light emitting diode (LED) based on the first PWM signal, the first LED being configured to output a first type of light; controlling a second LED based on the second PWM signal, the second LED being configured to output a second type of light; and controlling a third LED based on the third PWM signal, the third LED being configured to output a third type of light.

[0034] FIG. 1 is a diagram of an example of an illumination system 100, according to aspects of the disclosure. The illumination system 100 may include a control signal interface 110, a light fixture 120, and a light engine 130. In operation, the illumination system 100 may receive a user input via the control signal interface 1 10 and change the color of light that is output by the light fixture 120 based on the input. For example, if a first user input is received, the light fixture 120 may output light having a first color. By contrast, if a second user input is received, the light fixture 120 may output light having a second color that is different from the first color. In some implementations, the user may provide input to the illumination system by turning a knob or moving a slider that is part of the control signal interface 1 10. Additionally or alternatively, in some implementations, the user may provide input to the illumination system by using his or her smartphone, and/or another electronic device to transmit an indication of a desired color to the control signal interface 1 10.

[0035] The control signal interface 110 may include any suitable type of circuit or a device that is configured to generate a voltage signal CTRL and provide the voltage signal CTRL to the light engine 130. Although in the present example the control signal interface 110 and the light engine 130 are depicted as separate devices, alternative implementations are possible in which the control signal interface 110 and the light engine 130 are integrated together in the same device. For example, in some implementations, the control signal interface 1 10 may include a potentiometer coupled to a knob or slider, which is operable to generate the control signal CTRL based on the position of the knob (or slider). As another example, the control signal interface may include a wireless receiver {e.g., a Bluetooth receiver, a Zigbee receiver, a WiFi receiver, etc.) which is operable to receive one or more data items from a remote device {e.g., a smartphone or a Zigbee gateway) and output the control signal CTRL based on the data items. In some implementations, the one or more data items may include a number identifying a desired correlated color temperature (CCT) to be output by the light fixture 120. [0036] The light fixture 120 may include a light source 122 (e.g., warm-white), a light source 124 (e.g., cool-white) , and a light source 126 (e.g., neutral-white). The light source 122 (e.g., warm- white) may include one or more LEDs that are configured to output white light having a CCT of approximately 2700K. The light source 124 (e.g., cool-white) may include one or more LEDs that are configured to output white light having a CCT of approximately 6500K. The light source 126 (e.g., neutral-white) may include one or more LEDs that are configured to output white light having a CCT of approximately 4000K.

[0037] The light engine 130 may be configured to supply power to the light fixture 120 over three different channels. More particularly, the light engine 130 may be configured to: supply a first PWM signal PWR1 to the light source 122 (e.g., warm-white) over a first channel; supply a second PWM signal PWR2 to the light source 124 (e.g., cool-white) over a second channel; and supply a third PWM signal PWR3 to the light source 126 (e.g., neutral-white) over a third channel. The signal PWR1 may be used to power the warm-white light source, and its duty cycle may determine the brightness of the warm-white light source. The signal PWR2 may be used to power the cool-white light source, and its duty cycle may determine the brightness of the cool-white light source. The signal PWR3 may be used to power the neutral-white light source, and its duty cycle may determine the brightness of the neutral-white light source. In operation, the tunable light engine may change the relative magnitude of the duty cycles of the signals PWR1 , PWR2, and PWR3, to adjust the respective brightness of each one of light sources 122-126. As can be readily appreciated, varying the individual brightness of the light sources 122-126 may cause the output of the light fixture 120 to change color (and/or CCT). As noted above, the light output of the light fixture 120 may be the combination {e.g., a mix) of the light emissions produced by the light sources 122-126.

[0038] According to aspects of the disclosure, the light engine 130 may include any suitable type of electronic device and/or electronic circuitry that is configured to generate the signals PWR1 , PWR2, and PWR3. Although in the present examples, the signals PWR1 -PWR3 are PWM signals, alternative implementations are possible in which the signals PWR1 are current signals, voltage signals, and/or any other suitable type of signal. Furthermore, although in the present example the light sources 122-126 are white light sources, alternative implementations are possible in which the light sources 122-126 are each configured to emit a different color of light. For example, the light source 122 may be configured to emit red light, the light source 126 may be configured to emit green light, and the light source 124 may be configured to emit blue light.

[0039] FIG. 2 is a schematic diagram of an example of a PWM generator 200, according to aspects of the disclosure. The PWM generator 200 may include any suitable type of PWM generator. In some implementations, the PWM generator 200 may include a power-in terminal 210, a ground terminal 220, control terminal 230, and an output terminal 240. In operation, the PWM generator 200 may receive power at the power-in terminal 210 and a voltage control signal VCTRL at the control terminal 230. Based on the control signal VCTRL, the PWM generator 200 may generate a PWM signal and output the PWM signal from the output terminal 240.

[0040] FIG. 3 is graph illustrating an example of a PWM signal which may be generated by the PWM generator 200. The PWM signal may have a period P and a pulse width W. The duty cycle of the PWM signal may be the proportion of each period P for which the PWM signal is on {e.g., high), and it may be described by Equation 1 below:

PULSE WIDTH W

DUTY CYCLE OF PWM SIGNAL = -———— - X 100 Equation 1

PERIOD P

[0041] FIG. 4 is a graph illustrating the response of the PWM generator 200, according to aspects of the disclosure. As illustrated, when the control signal VCTRL has a first value {e.g., approximately 0V), the duty cycle of the PWM signal that is generated by the PWM generator 200 may be 100%, and when the control signal VCTRL has a second value Vc, the PWM generator 200 may be deactivated. Although not shown in FIG. 4, in some implementations, the PWM generator 200 may be configured to set the duty cycle of the PWM signal at 100% when the value of the control signal VCTRL is in a predetermined range (e.g., 0V-0.4V). Configuring the PWM generator 200 in this manner may ensure that outputting a PWM signal having a 100% duty cycle is always possible, as obtaining a control signal that is exactly 0V may not always be feasible in analog circuits. According to aspects of the disclosure, when the PWM generator is deactivated, it may be regarded as producing a PWM signal having a duty cycle of 0%. According to the present disclosure, the value Vc may be referred to as the cutoff voltage of the PWM generator. The value Vc may depend on the internal design of the PWM generator 200. Depending on design specifications, any suitable value for Vc may be achieved by those of ordinary skill in the art.

[0042] FIG. 5 is a circuit diagram of an example of an illumination system 500, which uses PWM generators, such as the PWM generator 200 as one of its building blocks. As illustrated, the illumination system 500 may include a light fixture 510, a control signal interface 520, and a light engine 530.

[0043] The light fixture 510 may include a light source 512, a light source 514, and a light source 516. Each light source may include one or more respective LEDs. For example, the light source 512 may include one or more light emitting diodes (LEDs) that are configured to produce a first type of light. The light source 514 may include one or more LEDs that are configured to produce a second type of light. The light source 516 may include one or more LEDs that are configured to produce a third type of light. The three types of light may differ from one another in one or more of wavelength, color rendering index (CRI), correlated color temperature (CCT), and/or color. In some implementations, the first type of light may be a warm-white light, the second type of light may be a cool-white light, and the third type of light may be a neutral-white light. Additionally or alternatively, in some implementations, the first type of light may be a red light, the second type of light may be a green light, and the third type of light may be a blue light.

[0044] According to the present example, the light fixture 510 may be arranged to produce tunable white light by mixing the respective outputs of each of the light sources 512-516. In such instances, the light source 512 may be configured to emit warm-white light having CCT of approximately 2700K; the light source 514 may be configured to emit cool-white light having a CCT of approximately 6500K; and the light source 516 may be configured to emit neutral-white light having a CCT of approximately 4000 CCT. As noted above, the output of the light fixture 510 may be a composite light output that is produced as a result of the emissions from the light sources 512-516 mixing with one another. The CCT of the composite light output may be varied by changing the respective brightness of each of light sources based on a control signal VCRL1 , which is generated by the control signal interface 520 and is provided via a first channel 521.

[0045] The control signal interface 520 may include any suitable type of circuit or a device that is configured to generate a voltage control signal VCTRL1 and provide the control signal VCTRL1 to the light engine 530. Although in the present example the control signal interface 520 and the light engine 530 are depicted as separate devices, alternative implementations are possible in which the control signal interface 520 and the light engine 530 are integrated together in the same device. For example, in some implementations, the control signal interface 520 may include a potentiometer coupled to a knob or slider, which is operable to generate the control signal VCTRL1 based on the position of the knob (or slider). As another example, the control signal interface may include a wireless receiver {e.g., a Bluetooth receiver, a Zigbee receiver, a WiFi receiver, etc.) which is operable to receive one or more data items from a remote device {e.g., a smartphone or a Zigbee gateway) and output the control signal VCTRL1 based on the data items. As another example, the control signal interface 520 may include an autonomous or semi-autonomous controller which is configured to generate the control signal VCTRL1 based on various control criteria. Those control criteria may include one or more of time of day, current date, current month, current season, etc.

[0046] The light engine 530 may be a three-channel light engine. The light engine 530 may be configured to supply power to each of the light sources 512-516 over different respective channels 522, 523, and 524. The light engine 530 may include a current source 532, a voltage regulator 534, and a reference voltage generator 536. The voltage regulator 534 may be configured to generate a voltage VDD that is used for powering various components of the light engine 530, as shown. The reference voltage generator 536 may be configured to generate a reference voltage signal VREF. The impact of the signal VREF on the operation of the light engine 530 is discussed further below.

[0047] The light engine 530 may be operable to drive the light source 512 by using a first PWM signal PWR1 which is supplied to the light source 512 over a first channel 522. The signal PWR1 may be generated by using a first signal generator GEN 1 525 and a first switch SW1. The generator GEN 1 525 may be the same or similar to the PWM generator 200 which is discussed with respect to FIG. 2, and it may have a cutoff voltage Vci . The switch SW1 may be a MOSFET transistor. The light source 512 may be connected to the current source 532 across the drain- source of the MOSFET transistor SW1 , and the gate of the MOSFET transistor SW1 may be arranged to receive a PWM signal VGATE1 which is generated by the signal generator GEN 1 525. As can be readily appreciated, this arrangement may result in the switch SW1 imparting on the signal PWR1 a duty cycle that is the same or similar to that of the signal VGATE1. The duty cycle of the signal VGATE1 may be dependent on the magnitude {e.g., level) of the control signal VCTRL1 , as shown in FIG. 3.

[0048] The light engine 530 may be operable to drive the light source 514 by using a second PWM signal PWR2 which is supplied to the light source 514 over a second channel 523. The signal PWR2 may be generated by using a second signal generator GEN 2 526 and a second switch SW2. The generator GEN 2 526 may be the same or similar to the PWM generator 200 which is discussed with respect to FIG. 2, and it may have a cutoff voltage Vc₂. The cutoff voltage Vc₂ of the signal generator GEN 2 526 may be the same or different from the cutoff voltage Vci of the signal generator GEN 1 525. The switch SW2 may be a MOSFET transistor. The light source 514 may be connected to the current source 532 across the drain-source of the MOSFET transistor SW2, and the gate of the MOSFET transistor SW2 may be arranged to receive a PWM signal VGATE2 which is generated by the signal generator GEN 2 526. As can be readily appreciated, this arrangement may result in the switch SW2 imparting on the signal PWR2 a duty cycle that is the same or similar to that of the signal VGATE2. The duty cycle of the signal VGATE2 may be dependent on the magnitude {e.g., level) of a voltage control signal VCTRL2, as shown in FIG. 3.

[0049] The control signal VCTRL2 may be a voltage signal. Furthermore, as noted above, the signals VCTRL1 and VREF may also be voltage signals. In this regards, the control signal VCTRL2 may be generated by subtracting the voltage of first control signal VCTRL1 from the voltage of the reference signal VREF. For example, when the reference signal VREF is 10V and the control signal VCTRL1 is 3V, the control signal VCTRL2 may equal 7V. The control signal VCTRL2 may be generated using a voltage subtracting circuit SUB1. The subtracting circuit SUB1 may include an operational amplifier (opamp) 540 configured to operate as a voltage subtractor. Furthermore, the subtracting circuit SUB1 may include resistors 552, 554, 556, and 558. Resistors 552 and 554 may both have a resistance R2. Resistors 556 and 558 may both have a resistance R1. Resistance R2 may be the same or different from resistance R1. Resistor 552 may be disposed between the output terminal and the inverting input terminal of the opamp 540, as shown. Resistor 554 may be coupled between the non-inverting input terminal of the opamp 540 and Ground. Resistor 556 may be coupled between the inverting terminal of the opamp 540 and the control signal interface 520. Resistor 558 may be coupled between the non-inverting terminal of the opamp 540 and the control reference voltage generator 536. In operation, the opamp 540 may: (i) receive the control signal VCTRL1 as a first input, (ii) receive the reference signal VREF as a second input, and generate the control signal VCTRL2 based on the control signal VCTRL1 and the reference signal VREF. The magnitude of the control signal VCTRL2 may be described by Equation 2 below:

[0050] The light engine 530 may be operable to drive the light source 516 by using a third PWM signal PWR3 which is supplied to the light source 516 over a third channel 524. The signal PWR3 may be generated by using a third signal generator GEN3 and a third switch SW3. The switch SW2 may be a MOSFET transistor. The light source 516 may be connected to the current source 532 across the drain-source of the MOSFET transistor SW3, and the gate of the MOSFET transistor SW3 may be arranged to receive a PWM signal VGATE3 which is generated by the signal generator GEN3. As can be readily appreciated, this arrangement may result in the switch SW3 imparting on the signal PWR3 a duty cycle that is the same or similar to that of the signal VGATE3. The signal VGATE3 may be generated by the generator GEN3 based on the signals VGATE1 and VGATE2. In some implementations, the signal generator GEN3 may include a NOR gate. As illustrated in FIG. 5, the NOR gate may receive the signals VGATE1 and VGATE2 as inputs and generate the signal VGATE3 by performing a NOR operation on the signals VGATE1 and VGATE2.

[0051] As illustrated in FIGS 6A-B, one or more of: (i) the value {e.g., level) of the voltage signal VREF, (ii) the value {e.g., level) of the cutoff voltage Vc1 of the signal generator GEN 1 525, and (iii) the value (e.g., level) of the cutoff voltage Vc2 of the signal generator GEN 2 526 may be selected such that only one of the signals VGATE1 and VGATE2 is at a logic high at any given time. This may be needed so that current from the current source 532 can be diverted to only one channel (e.g., only one of the light-sources 512-516) at any given time. In some implementations, diverting current from the current source 532 to only one channel at any given time may be advantageous as it may permit a more precise control over the brightness of the light sources 512-516. [0052] In some implementations, as illustrated in FIGS. 6A-B, one of the signals VGATE1 and VGATE2 may always have a duty cycle of 0%, while the other may have a duty cycle that is greater than 0%. In such instances, the signal VGATE3 may be generated by inverting a given one of the signals VGATE1 and VGATE2 which has the greater duty cycle. As a result, the sum of the duty cycles of the given one of the signals VGATE1 and VGATE2 which has the greater duty cycle, and the signal VGATE3 may equal 100%. Stated succinctly, in the example of FIGS. 6A-B, the signal VGATE3 is the inverse of one of the signals VGATE1 and VGATE2. According to aspects of the disclosure, one PWM signal is the inverse of another PWM signal when the value of the former signal is the opposite of the latter. For instance, as shown in FIG. 6A, the signal VGATE3 may be considered to be the inverse of the signal VGATE1 because the signal VGATE3 is at a logic high at all times when the signal VGATE1 is at a logic low, and vice versa.

[0053] Stated succinctly, in some implementations, the light engine 530 may steer the current generated by the current source 532 into three pulse-width modulated channels {e.g., PWR1 , PWR2, PWR3) with the sum of their duty cycles being unity. This effect may be achieved by: (i) ensuring that only one of the signals VGATE1 and VGATE2 is at a logic high value at any given time, (ii) and ensuring that the signal VGATE3 is the inverse of one of the signals VGATE1 and VGATE2 that has the greater duty cycle. Diverting the current from current source 532 in this manner may help achieve a more precise control over the brightness of the light output from the light sources 512-516.

[0054] As noted above, the operation of the light engine 530 may be dependent on one or more of the magnitude of the reference signal VREF, the cutoff voltage Vci of the signal generator GEN 1 525, the cutoff voltage Vc2 0f the signal generator GEN 2 526, and the ratio R2/R1. The present disclosure is not limited to any specific value for the reference signal VREF, the cutoff voltage Vci of the signal generator GEN 1 525, the cutoff voltage Vc₂ of the signal generator GEN 2 526, and the ratio R2/R1. The value of any of these variables may vary in different configurations of the illumination system 500, and it may be selected in accordance with desired design specifications.

[0055] The control signal VCTRL1 , as discussed above, may be generated by the control signal interface 520 in response to a user input indicating a desired CCT (and/or color) for the light that is output by the light fixture 510. The control signal VCTRL1 may thus be a voltage signal indicating a desired CCT (and/or color) for the light that is emitted from the light fixture 510.

[0056] The control signal VCTRL1 may determine when the light source 512 will be switched off. More particularly, when the magnitude of the control signal VCTRL1 exceeds the cutoff voltage Vci of the signal generator GEN 1 525, the light source 512 may be switched off. The reference signal

VREF may determine when the light source 516 will be switched on. If the value of the reference signal VREF is lower than double the cutoff voltage Vci of the signal generator GEN 1 525, the light source 514 may be switched on before the light source 512 is switched off. By contrast, if the value of the reference signal VREF is higher than double the cutoff voltage Vci of the signal generator GEN 1 525, the light source 514 may be switched on before the light source 512 is switched off. Similarly, when the signal VREF is equal to double the cutoff voltage Vci of the signal generator GEN 1 525, the light source 514 may be switched at the same time when the light source 512 is switched off.

[0057] The ratio R2/R1 may determine the rate at which the brightness of the light source 514 changes in response to changes in the signal VCTRL1. This, in turn, may affect the responsiveness of the illumination system 500 to user input. As noted above, in some implementations, the light source 514 may be a cool-white light source and the control signal VCRL1 may be generated by the control signal interface 520 in response to the user turning a knob. In such instances, when the ratio R2/R1 is high, the light output of the illumination system 500 will turn cool more abruptly when the knob is turned. By contrast, when the ratio R2/R1 is low, the light output of the illumination system 500 may turn cool more slowly when the knob is actuated.

[0058] FIG. 7 shows a plot 700 illustrating the operation of the illumination system 500, in accordance with one possible configuration of the light engine 530. In this configuration, the cutoff voltage Vci of the signal generator GEN 1 525 is the same as the cutoff voltage Vc₂ of the signal generator GEN 2 526, and the magnitude of the reference signal VREF equals double the cutoff voltage Vci. The plot 700 shows the relationship between the respective duty cycle of each of the signals PWR1 , PWR2, and PWR3 and the control signal VCTRL1. Furthermore, the plot 700 illustrates that the illumination system 500 may have at least five operational states, which are herein enumerated as states S0-S4.

[0059] The illumination system 500 may be in the state SO when the control signal VCTRL1 is equal to 0V (VCTRL1 =0V). When the illumination system 500 is in the state SO, the light source 512 may be switched on (at maximum capacity), and the light sources 514 and 516 may be switched off.

[0060] The illumination system 500 may be in the state S1 when the control signal VCTRL1 is greater than 0V and less than the cutoff voltage Vci of the signal generator GEN 1 525 (0<VCTRL1 <Vci). When the illumination system 500 is in the state S1 , the light sources 512 and 516 may be switched on, and the light source 514 may be switched off.

[0061] The illumination system 500 may be in the state S2 when the control signal VCTRL1 is equal to the cutoff voltage Vci of the signal generator GEN 1 525 (VCTRL1 =Vci). When the illumination system 500 is in the state S2, the light source 516 may be switched on (at maximum capacity), and the light sources 512 and 514 may be switched off. [0062] The illumination system 500 may be in the state S3 when the control signal VCTRL1 is greater than the cutoff voltage Vci of the signal generator GEN 1 525 and less than the reference signal VREF (Vci<VCTRL1 <VREF). When the illumination system 500 is in the state S3, the light sources 514 and 516 may be switched on, and the light source 512 may be switched off.

[0063] The illumination system 500 may be in the state S4 when the control signal VCTRL1 is greater than or equal to VREF (VCTRL1 >VREF). When the illumination system 500 is in the state S4, the light source 514 may be switched on (at maximum capacity), and the light sources 512 and 516 may be switched off.

[0064] FIG. 8 shows a plot 800 illustrating the operation of the illumination system 500, in accordance with another possible configuration of the light engine 530. In this configuration, the cutoff voltage Vci of the signal generator GEN 1 525 is the same as the cutoff voltage Vc₂ of the signal generator GEN 2 526, and the magnitude of the reference signal VREF is greater than double the magnitude cutoff voltage Vci . The plot 800 shows the relationship between respective duty cycle of each of the signals PWR1 , PWR2, and PWR3 and the control signal VCTRL1. Furthermore, the plot 800 illustrates that the illumination system 500 may have at least five operational states, which are herein enumerated as states S0-S4.

[0065] The illumination system 500 may be in the state SO when the control signal VCTRL1 is equal to 0V (VCTRL1 =0V). When the illumination system 500 is in the state SO, the light source 512 may be switched on (at maximum capacity), and the light sources 514 and 516 may be switched off.

[0066] The illumination system 500 may be in the state S1 when the control signal VCTRL1 is greater than 0V and less than the cutoff voltage Vci of the signal generator GEN 1 525 (0<VCTRL1 <Vci). When the illumination system 500 is in the state S1 , the light sources 512 and 516 may be switched on, and the light source 514 may be switched off.

[0067] The illumination system 500 may be in the state S2 when the control signal VCTRL1 is greater than or equal to the cutoff voltage Vci of the signal generator GEN 1 525 and less than or equal to Vm (Vci<VCTRL1 <Vm). When the illumination system 500 is in the state S2, the light source 516 may be switched on (at maximum capacity), and the light sources 512 and 514 may be switched off. In some implementation, the value Vm may be defined by Equation 3 below:

[0068] The illumination system 500 may be in the state S3 when the control signal VCTRL1 is greater than Vm and less than the reference signal VREF (Vm<VCTRL1 <VREF). When the illumination system 500 is in the state S3, the light sources 514 and 516 may be switched on, and the light source 512 may be switched off. Accordingly, Vm may be the value for the control signal VCTRL1 at which the light source 514 is switched on.

[0069] The illumination system 500 may be in the state S4 when the control signal VCTRL1 is greater than or equal to the reference signal VREF (VCTRL1 >VREF). When the illumination system 500 is in the state S4, the light source 514 may be switched on (at maximum capacity), and the light sources 512 and 516 may be switched off.

[0070] FIG. 9 shows a plot 900 which illustrates the relationship between the control signals VCTRL1 and VCTRL2, in accordance with the configuration of the illumination system 500 that is discussed with respect to FIG. 8. As shown, when the control signal VCTRL1 reaches the value of the cutoff voltage Vci of the signal generator GEN 1 525, the light source 512 may be switched off and the light source 516 may reach 100% brightness. When the control signal VCTRL1 surpasses the value Vm, the brightness of the light source 516 may start to decrease. Furthermore, for values between of VCTRL1 between Vci and Vm, the light source 516 may operate at maximum brightness and the light sources 512 and 514 may be switched off.

[0071] The plots 700 and 800 illustrate that the illumination system 500 may permit the user to change the color and/or CCT of the light output produced by the illumination system 500, without affecting the total brightness of the light that is emitted from the illumination system 500. This concept is illustrated in the plots 700 and 800. As illustrated in the plots 700 and 800, the lines representing the signals PWR1 and PWR2 may have slopes that are equal in magnitude, but opposite in sign, to the slope of the line representing the signal PWR3. This implies that any decrease in brightness of one of the light source 512 and the light source 514 may be matched by an equal increase in brightness of the light source 516, and vice versa. Thus, in some implementations, when the CCT (or color) of the light output of the illumination system 500 is changed (as a result of the control signal VCTRL1 changing), that change may take place without any increase or decrease in brightness of the illumination system’s 500 light output.

[0072] FIG. 10 is a flowchart of an example of the process, according to aspects of the disclosure. In some implementations, all steps in the process 1000 may be performed concurrently based on the sequencing of the reference numbers provided in Fig. 10. Alternatively, in some implementations, some or all steps in the process 1000 may be performed sequentially, for example, as outlined by the flow arrows provided in Fig. 10. The process 1000 may be performed by the illumination system 100, the illumination system 500, and/or any other suitable type of electronic device. For example, in some implementations, at least some of the steps in the process 1000 may be performed using processing circuitry, such as a microprocessor {e.g., an ARM-based processor, an Arduino-based processor, etc.) Additionally or alternatively, in some implementations, at least some of the steps in the process 1000 may be performed by using an electronic circuit, such as the one shown in FIG. 5.

[0073] At step 1010, a first control signal is received which indicates a desired CCT and/or a desired color for a light output. The control signal may be received from a control signal interface, such as the control signal interface 1 10 or 520. In some implementations, the control signal may be a voltage signal, such as the control signal VCTRL1. In some implementations, the control signal may be a digital representation of a number or an alphanumerical string which indicates a desired CCT and/or color. At step 1020, a reference signal is generated. In some implementations, the reference signal may be a voltage signal, such as the signal VREF. Additionally or alternatively, in some implementations, the reference signal may be a digital representation of a number and/or an alphanumerical string. At step 1030, a second control signal is generated based on at least one of the reference signal and the first control signal. In some implementations, the second control signal may be generated by subtracting the first control signal from the reference signal.

[0074] At step 1040, a first PWM signal is generated based on the first control signal. In some implementations, the first PWM signal may have a duty cycle that is based on the first control signal. In some implementations, the duty cycle of the first PWM signal may be proportional to the magnitude of the first control signal {e.g., proportional to a level of the first control signal).

[0075] At step 1050, a second PWM signal is generated. In some implementations, the duty cycle of the second PWM signal may be generated based on at least one of the first control signal and the reference signal. Additionally or alternatively, in some implementations, the second control signal may be generated based on the second control signal. Additionally or alternatively, in some implementations, the second PWM signal may have a duty cycle that is proportional to the magnitude of the second control signal.

[0076] At step 1060 a third PWM signal is generated based on at least one of the first PWM signal and the second PWM signal. In some implementations, the third PWM signal may have a duty cycle that is different from each of the first PWM signal and the second PWM signal. In some implementations, the third PWM signal may be generated by inverting one of the first PWM signal and the second PWM signal which has the greater duty cycle. Additionally or alternatively, in some implementations, the third PWM signal may be generated by performing a NOR operation on the first PWM signal and the second PWM signal.

[0077] At step 1070 a first light source is controlled based on the first PWM signal. The first light source may include one or more LEDs and/or any other suitable type of light source. In some implementations, controlling the first light source may include switching on and/or switching off the first light source based on the first PWM signal. Additionally or alternatively, in some implementations, controlling the first light source may include increasing and/or decreasing the brightness of the first light source. Additionally or alternatively, in some implementations, controlling the first light source may include changing the state of a switch, which controls the flow of current across the first light source, based on the first PWM signal.

[0078] At step 1080 a second light source is controlled based on the second PWM signal. The second light source may include one or more LEDs and/or any other suitable type of light source. In some implementations, controlling the second light source may include switching on and/or switching off the second light source based on the second PWM signal. Additionally or alternatively, in some implementations, controlling the second light source may include increasing and/or decreasing the brightness of the second light source. Additionally or alternatively, in some implementations, controlling the second light source may include changing the state of a switch, which controls the flow of current across the second light source, based on the second PWM signal.

[0079] At step 1090 a third light source is controlled based on the third PWM signal. The third light source may include one or more LEDs and/or any other suitable type of light source. In some implementations, controlling the third light source may include switching on and/or switching off the third light source based on the third PWM signal. Additionally or alternatively, in some implementations, controlling the third light source may include increasing and/or decreasing the brightness of the third light source. Additionally or alternatively, in some implementations, controlling the third light source may include changing the state of a switch, which controls the flow of current across the third light source, based on the third PWM signal.

[0080] FIGS. 1 -10 are provided as an example only. Although in the example of FIG. 5, the switches SW1 and SW2 are implemented as MOSFET transistors, any suitable type of switch may be used instead, such as a solid-state relay, a PMOS transistor, etc. Although in the example of FIG. 5, the subtractor SUB1 is implemented using an opamp, any suitable type of electronic circuitry may be used instead to implement the subtractor. Although in the example of FIG. 3, the generator GEN3 is implemented using a NOR gate, any other suitable type of circuitry can be used instead. For example, the signal generator GEN3 may be implemented by using an OR gate and one or more inverters, etc. At least some of the elements discussed with respect to these figures can be arranged in different order, combined, and/or altogether omitted.

[0081] Fig. 1 1 is a top view of an electronics board 310 for an integrated LED lighting system according to one embodiment. In alternative embodiments, two or more electronics boards may be used for the LED lighting system. For example, the LED array may be on a separate electronics board, or the sensor module may be on a separate electronics board. In the illustrated example, the electronics board 310 includes a power module 312, a sensor module 314, a connectivity and control module 316 and an LED attach region 318 reserved for attachment of an LED array to a substrate 320. The power module 312 of Fig. 1 1 may include the light engine (e.g., light engine 530 of Fig. 5) disclosed herein.

[0082] The substrate 320 may be any board capable of mechanically supporting, and providing electrical coupling to, electrical components, electronic components and/or electronic modules using conductive connecters, such as tracks, traces, pads, vias, and/or wires. The substrate 320 may include one or more metallization layers disposed between, or on, one or more layers of non- conductive material, such as a dielectric composite material. The power module 312 may include electrical and/or electronic elements. In an example embodiment, the power module 312 includes an AC/DC conversion circuit, a DC/DC conversion circuit, a dimming circuit, and an LED driver circuit.

[0083] The sensor module 314 may include sensors needed for an application in which the LED array is to be implemented. Example sensors may include optical sensors (e.g., IR sensors and image sensors), motion sensors, thermal sensors, mechanical sensors, proximity sensors, or even timers. By way of example, LEDs in street lighting, general illumination, and horticultural lighting applications may be turned off/on and/or adjusted based on a number of different sensor inputs, such as a detected presence of a user, detected ambient lighting conditions, detected weather conditions, or based on time of day/night. This may include, for example, adjusting the intensity of light output, the shape of light output, the color of light output, and/or turning the lights on or off to conserve energy. For AR/VR applications, motion sensors may be used to detect user movement. The motion sensors themselves may be LEDs, such as IR detector LEDs. By way of another example, for camera flash applications, image and/or other optical sensors or pixels may be used to measure lighting for a scene to be captured so that the flash lighting color, intensity illumination pattern, and/or shape may be optimally calibrated. In alternative embodiments, the electronics board 310 does not include a sensor module.

[0084] The connectivity and control module 316 may include the system microcontroller and any type of wired or wireless module configured to receive a control input from an external device. By way of example, a wireless module may include blue tooth, Zigbee, Z-wave, mesh, WiFi, near field communication (NFC) and/or peer to peer modules may be used. The microcontroller may be any type of special purpose computer or processor that may be embedded in an LED lighting system and configured or configurable to receive inputs from the wired or wireless module or other modules in the LED system (such as sensor data and data fed back from the LED module) and provide control signals to other modules based thereon. The control signal interface 1 10 disclosed herein may be part of the microcontroller or may receive input or provide output to the microcontroller. Algorithms implemented by the special purpose processor may be implemented in a computer program, software, or firmware incorporated in a non-transitory computer-readable storage medium for execution by the special purpose processor. Examples of non-transitory computer-readable storage mediums include a read only memory (ROM), a random access memory (RAM), a register, cache memory, and semiconductor memory devices. The memory may be included as part of the microcontroller or may be implemented elsewhere, either on or off the electronics board 310.

[0085] The term module, as used herein, may refer to electrical and/or electronic components disposed on individual circuit boards that may be soldered to one or more electronics boards 310. The term module may, however, also refer to electrical and/or electronic components that provide similar functionality, but which may be individually soldered to one or more circuit boards in a same region or in different regions.

[0086] FIG. 12a is a top view of the electronics board 310 with an LED array 410 attached to the substrate 320 at the LED device attach region 318 in one embodiment. The electronics board 310 together with the LED array 410 represents an LED lighting system 400A. Additionally, the power module 312 receives a voltage input at Vin 497 and control signals from the connectivity and control module 316 over traces 418B, and provides drive signals to the LED array 410 over traces 418A. The LED array 410 is turned on and off via the drive signals from the power module 312. In the embodiment shown in Fig. 12, the connectivity and control module 316 receives sensor signals from the sensor module 314 over traces 418. The power module 312 of FIG. 12 may include the light engine (e.g., light engine 530 of Fig. 5) disclosed herein and the may provide the PWM signals disclosed herein to LEDs in the LED array 410.

[0087] FIG. 12b illustrates one embodiment of a two channel integrated LED lighting system with electronic components mounted on two surfaces of a circuit board 499. As shown in FIG. 12b, an LED lighting system 400B includes a first surface 445A having inputs to receive dimmer signals and AC power signals and an AC/DC converter circuit 412 mounted on it. The LED system 400B includes a second surface 445B with the dimmer interface circuit 415, DC-DC converter circuits 440A and 440B, a connectivity and control module 416 (a wireless module in this example) having a microcontroller 472, and an LED array 410 mounted on it. The LED array 410 is driven by two independent channels 41 1 A and 41 1 B. In alternative embodiments, a single channel may be used to provide the drive signals to an LED array, or any number of multiple channels may be used to provide the drive signals to an LED array. For example, FIG. 12E illustrates an LED lighting system 400D having 3 channels (e.g., channels 522, 523 and 524 of Fig. 5, as disclosed herein) and is described in further detail below. [0088] The LED array 410 may include two or more groups of LED devices. In an example embodiment, the LED devices of group A are electrically coupled to a first channel 41 1 A and the LED devices of group B are electrically coupled to a second channel 41 1 B. Each of the two DC-DC converters 440A and 440B may provide a respective drive current via single channels 41 1 A and 41 1 B, respectively, for driving a respective group of LEDs A and B in the LED array 410. The LEDs in one of the groups of LEDs may be configured to emit light having a different color point than the LEDs in the second group of LEDs. Control of the composite color point of light emitted by the LED array 410 may be tuned within a range by controlling the current and/or duty cycle applied by the individual DC/DC converter circuits 440A and 440B via a single channel 41 1 A and 41 1 B, respectively. Although the embodiment shown n FIG. 12B does not include a sensor module (as described in Fig. 1 1 and Fig. 12), an alternative embodiment may include a sensor module.

[0089] The illustrated LED lighting system 400B is an integrated system in which the LED array 410 and the circuitry for operating the LED array 410 are provided on a single electronics board. Connections between modules on the same surface of the circuit board 499 may be electrically coupled for exchanging, for example, voltages, currents, and control signals between modules, by surface or sub-surface interconnections, such as traces 431 , 432, 433, 434 and 435 or metallizations (not shown). Connections between modules on opposite surfaces of the circuit board 499 may be electrically coupled by through board interconnections, such as vias and metallizations (not shown).

[0090] Fig. 12c illustrates an embodiment of an LED lighting system where the LED array is on a separate electronics board from the driver and control circuitry. The LED lighting system 400C includes a power module 452 that is on a separate electronics board than an LED module 490. The power module 452 may include, on a first electronics board, an AC/DC converter circuit 412, a sensor module 414, a connectivity and control module 416, a dimmer interface circuit 415 and a DC/DC converter 440. The LED module 490 may include, on a second electronics board, embedded LED calibration and setting data 493 and the LED array 410. Data, control signals and/or LED driver input signals 485 may be exchanged between the power module 452 and the LED module 490 via wires that may electrically and communicatively couple the two modules. The embedded LED calibration and setting data 493 may include any data needed by other modules within a given LED lighting system to control how the LEDs in the LED array are driven. In one embodiment, the embedded calibration and setting data 493 may include data needed by the microcontroller to generate or modify a control signal that instructs the driver to provide power to each group of LEDs A and B using, for example, pulse width modulated (PWM) signals. In this example, the calibration and setting data 493 may inform the microcontroller 472 as to, for example, the number of power channels to be used, a desired color point of the composite light to be provided by the entire LED array 410, and/or a percentage of the power provided by the AC/DC converter circuit 412 to provide to each channel.

[0091] Fig. 12d illustrates a block diagram of an LED lighting system having the LED array together with some of the electronics on an electronics board separate from the driver circuit. An LED system 400D includes a power conversion module 483 and an LED module 481 located on a separate electronics board. The power conversion module 483 may include the AC/DC converter circuit 412, the dimmer interface circuit 415 and the DC-DC converter circuit 440, and the LED module 481 may include the embedded LED calibration and setting data 493, LED array 410, sensor module 414 and connectivity and control module 416. The power conversion module 483 may provide LED driver input signals 485 to the LED array 410 via a wired connection between the two electronics boards.

[0092] Fig. 12e is a diagram of an example LED lighting system 400D showing a multi-channel LED driver circuit. In the illustrated example, the system 400D includes a power module 452 and an LED module 491 that includes the embedded LED calibration and setting data 493 and three groups of LEDs 494A, 494B and 494C. The power module 452 may include the light engine 530, as disclosed herein, such that the power module 542 may receive a control signal via a control channel and may generate three PWM signals to provide power to LEDs/LED groups. While three groups of LEDs are shown in Fig. 12e, one of ordinary skill in the art will recognize that any number of groups of LEDs may be used consistent with the embodiments described herein. Further, while the individual LEDs within each group are arranged in series, they may be arranged in parallel in some embodiments.

[0093] The LED array 491 may include groups of LEDs that provide light having different color points. For example, the LED array 491 may include a warm white light source via a first group of LEDs 494A, a cool white light source via a second group of LEDs 494B and a neutral while light source via a third group of LEDs 494C. The warm white light source via the first group of LEDs 494A may include one or more LEDs that are configured to provide white light having a correlated color temperature (CCT) of approximately 2700K. The cool white light source via the second group of LEDs 494B may include one or more LEDs that are configured to provide white light having a CCT of approximately 6500K. The neutral white light source via the third group of LEDs 494C may include one or more LEDs configured to provide light having a CCT of approximately 4000K. While various white colored LEDs are described in this example, one of ordinary skill in the art will recognize that other color combinations are possible consistent with the embodiments described herein to provide a composite light output from the LED array 491 that has various overall colors. [0094] The power module 452 may include a tunable light engine (not shown), which may be configured to supply power to the LED array 491 over three separate channels (indicated as LED1 +, LED2+ and LED3+ in Fig. 12e). More particularly, the tunable light engine may be configured to supply a first PWM signal to the first group of LEDs 494A such as warm white light source via a first channel, a second PWM signal to the second group of LEDs 494B via a second channel, and a third PWM signal to the third group of LEDs 494C via a third channel. Each signal provided via a respective channel may be used to power the corresponding LED or group of LEDs, and the duty cycle of the signal may determine the overall duration of on and off states of each respective LED. The duration of the on and off states may result in an overall light effect which may have light properties (e.g., correlated color temperature (CCT), color point or brightness) based on the duration. In operation, the tunable light engine may change the relative magnitude of the duty cycles of the first, second and third signals to adjust the respective light properties of each of the groups of LEDs to provide a composite light with the desired emission from the LED array 491. As noted above, the light output of the LED array 491 may have a color point that is based on the combination (e.g., mix) of the light emissions from each of the groups of LEDs 494A, 494B and 494C.

[0095] In operation, the power module 452 may receive a control input generated based on user and/or sensor input and provide signals via the individual channels to control the composite color of light output by the LED array 491 based on the control input. In some embodiments, a user may provide input to the LED system for control of the DC/DC converter circuit by turning a knob or moving a slider that may be part of, for example, a sensor module (not shown). Additionally or alternatively, in some embodiments, a user may provide input to the LED lighting system 400D using a smartphone and/or other electronic device to transmit an indication of a desired color to a wireless module (not shown).

[0096] Fig. 13 shows an example system 950 which includes an application platform 960, LED lighting systems 952 and 956, and secondary optics 954 and 958. The LED lighting system 952 produces light beams 961 shown between arrows 961 a and 961 b. The LED lighting system 956 may produce light beams 962 between arrows 962a and 962b. In the embodiment shown in FIG. 13, the light emitted from LED lighting system 952 passes through secondary optics 954, and the light emitted from the LED lighting system 956 passes through secondary optics 958. In alternative embodiments, the light beams 961 and 962 do not pass through any secondary optics. The secondary optics may be or may include one or more light guides. The one or more light guides may be edge lit or may have an interior opening that defines an interior edge of the light guide. LED lighting systems 952 and/or 956 may be inserted in the interior openings of the one or more light guides such that they inject light into the interior edge (interior opening light guide) or exterior edge (edge lit light guide) of the one or more light guides. LEDs in LED lighting systems 952 and/or 956 may be arranged around the circumference of a base that is part of the light guide. According to an implementation, the base may be thermally conductive. According to an implementation, the base may be coupled to a heat-dissipating element that is disposed over the light guide. The heat- dissipating element may be arranged to receive heat generated by the LEDs via the thermally conductive base and dissipate the received heat. The one or more light guides may allow light emitted by LED lighting systems 952 and 956 to be shaped in a desired manner such as, for example, with a gradient, a chamfered distribution, a narrow distribution, a wide distribution, an angular distribution, or the like.

[0097] In example embodiments, the system 950 may be a mobile phone of a camera flash system, indoor residential or commercial lighting, outdoor light such as street lighting, an automobile, a medical device, ARA/R devices, and robotic devices. The integrated LED lighting system 400A shown in Fig. 12, the integrated LED lighting system 400B shown in Fig. 12b, the LED lighting system 400C shown in Fig. 12c, and the LED lighting system 400D shown in FIG. 12D illustrate LED lighting systems 952 and 956 in example embodiments.

[0098] In example embodiments, the system 950 may be a mobile phone of a camera flash system, indoor residential or commercial lighting, outdoor light such as street lighting, an automobile, a medical device, AR/VR devices, and robotic devices. The integrated LED lighting system 400A shown in Fig. 12, the integrated LED lighting system 400B shown in Fig. 12b, the LED lighting system 400C shown in Fig. 12c, and the LED lighting system 400D shown in FIG. 12D illustrate LED lighting systems 952 and 956 in example embodiments.

[0099] The application platform 960 may provide power to the LED lighting systems 952 and/or 956 via a power bus via line 965 or other applicable input, as discussed herein. Further, application platform 960 may provide input signals via line 965 for the operation of the LED lighting system 952 and LED lighting system 956, which input may be based on a user input/preference, a sensed reading, a pre-programmed or autonomously determined output, or the like. One or more sensors may be internal or external to the housing of the application platform 960.

[00100] In various embodiments, application platform 960 sensors and/or LED lighting system 952 and/or 956 sensors may collect data such as visual data (e.g., LIDAR data, IR data, data collected via a camera, etc.), audio data, distance based data, movement data, environmental data, or the like or a combination thereof. The data may be related a physical item or entity such as an object, an individual, a vehicle, etc. For example, sensing equipment may collect object proximity data for an ADAS/AV based application, which may prioritize the detection and subsequent action based on the detection of a physical item or entity. The data may be collected based on emitting an optical signal by, for example, LED lighting system 952 and/or 956, such as an IR signal and collecting data based on the emitted optical signal. The data may be collected by a different component than the component that emits the optical signal for the data collection. Continuing the example, sensing equipment may be located on an automobile and may emit a beam using a vertical-cavity surface- emitting laser (VCSEL). The one or more sensors may sense a response to the emitted beam or any other applicable input.

[00101] In example embodiment, application platform 960 may represent an automobile and LED lighting system 952 and LED lighting system 956 may represent automobile headlights. In various embodiments, the system 950 may represent an automobile with steerable light beams where LEDs may be selectively activated to provide steerable light. For example, an array of LEDs may be used to define or project a shape or pattern or illuminate only selected sections of a roadway. In an example embodiment, Infrared cameras or detector pixels within LED lighting systems 952 and/or 956 may be sensors that identify portions of a scene (roadway, pedestrian crossing, etc.) that require illumination.

[00102] FIG. 14A is a diagram of an LED device 201 in an example embodiment. The LED device 201 may include a substrate 202, an active layer 204, a wavelength converting layer 206, and primary optic 208. In other embodiments, an LED device may not include a wavelength converter layer and/or primary optics. Individual LED devices 201 may be included in an LED array in an LED lighting system, such as any of the LED lighting systems described above.

[00103] As shown in Fig. 14A, the active layer 204 may be adjacent to the substrate 202 and emits light when excited. Suitable materials used to form the substrate 202 and the active layer 204 include sapphire, SiC, GaN, Silicone and may more specifically be formed from a lll-V semiconductors including, but not limited to, AIN, AIP, AIAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, ll-VI semiconductors including, but not limited to, ZnS, ZnSe, CdSe, CdTe, group IV semiconductors including, but not limited to Ge, Si, SiC, and mixtures or alloys thereof.

[00104] The wavelength converting layer 206 may be remote from, proximal to, or directly above active layer 204. The active layer 204 emits light into the wavelength converting layer 206. The wavelength converting layer 206 acts to further modify wavelength of the emitted light by the active layer 204. LED devices that include a wavelength converting layer are often referred to as phosphor converted LEDs (“PCLED”). The wavelength converting layer 206 may include any luminescent material, such as, for example, phosphor particles in a transparent or translucent binder or matrix, or a ceramic phosphor element, which absorbs light of one wavelength and emits light of a different wavelength. [00105] The primary optic 208 may be on or over one or more layers of the LED device 201 and allow light to pass from the active layer 204 and/or the wavelength converting layer 206 through the primary optic 208. The primary optic 208 may be a lens or encapsulate configured to protect the one or more layers and to, at least in part, shape the output of the LED device 201. Primary optic 208 may include transparent and/or semi-transparent material. In example embodiments, light via the primary optic may be emitted based on a Lambertian distribution pattern. It will be understood that one or more properties of the primary optic 208 may be modified to produce a light distribution pattern that is different than the Lambertian distribution pattern.

[00106] Fig. 14b shows a cross-sectional view of a lighting system 221 including an LED array 21 1 with pixels 201 A, 201 B, and 201 C, as well as secondary optics 212 in an example embodiment. The LED array 211 includes pixels 201 A, 201 B, and 201 C each including a respective wavelength converting layer 206B active layer 204B and a substrate 202B. The LED array 21 1 may be a monolithic LED array manufactured using wafer level processing techniques, a micro LED with sub- 500 micron dimensions, or the like. Pixels 201 A, 201 B, and 201 C, in the LED array 21 1 may be formed using array segmentation, or alternatively using pick and place techniques.

[00107] The spaces 203 shown between one or more pixels 201 A, 201 B, and 201 C of the LED devices 200B may include an air gap or may be filled by a material such as a metal material which may be a contact (e.g., n-contact).

[00108] The secondary optics 212 may include one or both of the lens 209 and waveguide 207. It will be understood that although secondary optics are discussed in accordance with the example shown, in example embodiments, the secondary optics 212 may be used to spread the incoming light (diverging optics), or to gather incoming light into a collimated beam (collimating optics). In example embodiments, the waveguide 207 may be a concentrator and may have any applicable shape to concentrate light such as a parabolic shape, cone shape, beveled shape, or the like. The waveguide 207 may be coated with a dielectric material, a metallization layer, or the like used to reflect or redirect incident light. In alternative embodiments, a lighting system may not include one or more of the following: the converting layer 206B, the primary optics 208B, the waveguide 207 and the lens 209.

[00109] Lens 209 may be formed form any applicable transparent material such as, but not limited to SiC, aluminum oxide, diamond, or the like or a combination thereof. Lens 209 may be used to modify the a beam of light input into the lens 209 such that an output beam from the lens 209 will efficiently meet a desired photometric specification. Additionally, lens 209 may serve one or more aesthetic purpose, such as by determining a lit and/or unlit appearance of the pixels 201 A, 201 B and/or 201 C of the LED array 21 1. [001 10] Having described the embodiments in detail, those skilled in the art will appreciate that, given the present description, modifications may be made to the embodiments described herein without departing from the spirit of the inventive concept. Therefore, it is not intended that the scope of the invention be limited to the specific embodiments illustrated and described.

Claims

1. A system comprising:

a control signal interface configured to provide a voltage control signal via a control channel; and

a light engine comprising:

a first signal generator configured to provide a first pulse-width modulated (PWM) signal based on the control signal, via a first channel;

a second signal generator configured to provide a second PWM signal based on the control signal, via a second channel; and

a third signal generator configured to provide a third PWM signal based on the first PWM signal and the second PWM signal, via a third channel.

2. The system of claim 1 , further comprising:

a light fixture comprising:

a first light emitting diode (LED) electrically coupled to receive the first PWM signal provided via the first channel, and configured to emit light with a first property;

a second LED powered using the first PWM signal provided via the second channel, and configured to emit light with a second property; and

a third LED powered using the first PWM signal provided via the third channel, and configured to emit light with a third property.

3. The system of claim 1 , wherein the voltage control signal is provided based on a user input received at the control signal interface.

4. The system of claim 2, wherein the first LED is configured to emit warm-white light, the second LED is configured to emit cool-white light, and the third LED is configured to emit neutral- white light.

5. The system of claim 2, wherein the first LED is configured to emit red light, the second LED is configured to emit blue light, and the third LED is configured to emit green light.

6. The system of claim 1 , wherein:

the first control signal is a voltage signal having a first magnitude,

the first signal generator is configured to turn off the first LED when the first control signal exceeds a cutoff voltage of the first signal generator, and

a reference signal is a voltage signal having a second magnitude that is greater than or equal to the cutoff voltage of the first signal generator such that the second PWM signal is further based on the reference signal.

7. The system of claim 1 , wherein the third signal generator includes a NOR gate arranged to receive the first PWM signal and the second PWM signal as inputs.

8. The system of claim 1 , further comprising:

a first switch configured to control a flow of current across the first LED based on the first PWM signal;

a second switch configured to control a flow of current across the second LED based on the second PWM signal; and

a third switch configured to control a flow of current across the third LED based on the third PWM signal.

9. A device comprising:

a first signal generator configured to provide a first PWM signal based on a control signal; a second signal generator configured to provide a second PWM signal based on the first PWM signal; and

a third signal generator configured to provide a third PWM signal based on the first PWM signal and the second PWM signal.

10. The device of claim 9, further comprising:

a first light emitting diode (LED) powered using the first PWM, the first LED configured to emit light with a first property;

a second LED powered using the second PWM signal, the second LED configured to emit light with a second property; and

a third LED powered using the third PWM signal, the third LED configured to emit light with a third property.

1 1. The device of claim 10, wherein the first LED is configured to emit warm-white light, the second LED is configured to emit cool-white light, and the third LED is configured to emit neutral- white light.

12. The device of claim 10, wherein the first LED is configured to emit red light, the second LED is configured to emit blue light, and the third LED is configured to emit green light.

13. The device of claim 9, wherein:

the first control signal is a voltage signal having a first magnitude,

14. The device of claim 9, wherein the third signal generator includes a NOR gate arranged to receive the first PWM signal and the second PWM signal as inputs.

15. The device of claim 9, further comprising:

16. A method comprising:

receiving a voltage control signal via a control channel;

providing, via a first channel, a first PWM signal based on the voltage control signal;

providing, via a second channel, a second PWM signal based on a reference signal and the voltage control signal;

providing, via a third channel, a third PWM signal based on the first PWM signal and the second PWM signal, the third PWM signal having a different duty cycle than at least one of the first PWM signal and the second PWM signal;

controlling a first LED based on the first PWM signal provided via the first channel, the first LED being configured to output a light with a first property;

controlling a second LED based on the second PWM signal provided via the second channel, the second LED being configured to output a light with a second property; and

controlling a third LED based on the third PWM signal provided via the third channel, the third LED being configured to output a light with a third property.

17. The method of claim 16, wherein the first LED is configured to emit warm-white light, the second LED is configured to emit cool-white light, and the third LED is configured to emit neutral-white light.

18. The method of claim 16, wherein the first LED is configured to emit red light, the second LED is configured to emit blue light, and the third LED is configured to emit green light.

19. The method of claim 16, wherein the first control is generated based on a user input received at a control signal interface.

20. The method of claim 16, wherein:

when the first PWM signal has a larger duty cycle than the second PWM signal, the third PWM signal is generated by inverting the first PWM signal, and if the second PWM signal has a larger duty cycle than the first PWM signal, the third PWM signal is generated by inverting the second PWM signal.