CN113711694B

CN113711694B - Hybrid driving scheme for RGB color adjustment

Info

Publication number: CN113711694B
Application number: CN202080024081.2A
Authority: CN
Inventors: 邱怡峰; J·格兰特
Original assignee: Koninklijke Philips NV
Current assignee: Koninklijke Philips NV
Priority date: 2019-01-25
Filing date: 2020-01-23
Publication date: 2023-08-18
Anticipated expiration: 2040-01-23
Also published as: WO2020154547A1; JP2022510040A; JP7089123B2; KR20210112391A; CN113711694A; EP3915335A1; TW202036532A; KR102434290B1

Abstract

An apparatus, comprising: an analog current distribution circuit configured to divide an input current into a first current and a second current; and a multiplexer array including a plurality of switches to provide a first current to a first one of the three color LEDs and a second current to a second one of the three color LEDs simultaneously during a first portion of the cycle, to provide the first current to the second one of the three color LEDs and the second current to a third one of the three color LEDs simultaneously during a second portion of the cycle, and to provide the first current to the first one of the three color LEDs and the second current to the third one of the three color LEDs simultaneously during a third portion of the cycle.

Description

Hybrid driving scheme for RGB color adjustment

Priority claim

The present application claims the benefit of priority from U.S. patent application Ser. No. 16/543230 filed 8, 16, 2019, which claims the benefit of priority from U.S. patent application Ser. No. 16/258193 filed 1, 25, and claims the benefit of European patent application Ser. No. 19165527.3 filed 3, 27, 2019, each of which is incorporated herein by reference in its entirety.

Background

A Light Emitting Diode (LED) is a semiconductor light source that emits light when current flows through it. When a suitable current is applied to the LED, the electrons are able to recombine with electron holes within the LED, releasing energy in the form of photons. This effect is known as electroluminescence. The color of the emitted light corresponding to the photon energy is determined by the energy bandgap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of wavelength converting material on a semiconductor device.

An LED circuit, also called LED driver, is a circuit for powering an LED by supplying a suitable current. The circuit must provide enough current to illuminate the LED at the desired brightness, but must limit the current to prevent damage to the LED. A balance needs to be made between supplying sufficient current to the LEDs and limiting the current to prevent damage, as the voltage drop across the LEDs is approximately constant over a wide operating current interval. This results in a small increase in applied voltage that greatly increases current.

Combinations of LEDs are often used in red-green-blue (RGB) color adjustment schemes. The addition of additional LEDs and the requirement to power each LED within the RGB color adjustment add complexity to the RGB LED driving scheme.

Disclosure of Invention

Drawings

A more detailed understanding can be obtained from the following description, given by way of example in connection with the accompanying drawings, in which:

FIG. 1A illustrates a CIE chromaticity diagram representing a color space;

FIG. 1B illustrates a diagram illustrating different CCTs and their relationship to the BBL;

FIG. 1C illustrates an example circuit of a hybrid drive circuit for RGB adjustment;

FIG. 1D illustrates a microcontroller for a computing device to handle complex signal processing with fewer PCB resources than analog circuitry;

FIG. 1E illustrates a color diagram of the circuit of FIG. 1C with a red LED (or red LED array) in a center position;

FIG. 1F illustrates a color diagram of the circuit of FIG. 1C with a green LED (or green LED array) in a center position;

FIG. 1G illustrates a color plot of the circuit of FIG. 1C, with a blue LED (or blue LED array) in a center position;

FIG. 1H illustrates another hybrid drive circuit;

FIG. 1I illustrates a color diagram of the circuit of FIG. 1H, wherein the red and blue LEDs (or red LED array and blue LED array) are driven by an analog current;

FIG. 1J illustrates a color diagram of the circuit of FIG. 1H, wherein the red and green LEDs (or red and green LED arrays) are driven by an analog current;

FIG. 1K illustrates a color diagram of the circuit of FIG. 1H, wherein the blue and green LEDs (or blue LED array and green LED array) are driven by an analog current;

FIG. 1L illustrates another hybrid drive circuit;

FIG. 1M illustrates a color diagram of the circuit of FIG. 1L providing full color gamut coverage;

fig. 1N illustrates a method of hybrid driving for RGB color adjustment driving;

FIG. 2 is a top view of an electronic board of an integrated LED lighting system according to one embodiment;

FIG. 3A is a top view of an electronic board with an LED array attached to a substrate at an LED device attachment area in one embodiment;

FIG. 3B is an illustration of one embodiment of a dual channel integrated LED lighting system with electronic components mounted on both surfaces of a circuit board;

FIG. 3C is an illustration of an embodiment of an LED lighting system in which the LED array is on an electronic board separate from the driver and control circuitry;

FIG. 3D is a block diagram of an LED lighting system having an LED array and some electronics on an electronic board separate from the driver circuit;

FIG. 3E is a diagram of an example LED lighting system showing a multi-channel LED driver circuit;

FIG. 4 is an illustration of an example application system;

fig. 5A is a diagram showing an LED device; and

fig. 5B is a diagram showing a plurality of LED devices.

Detailed Description

Examples of different light illumination systems and/or light emitting diode ("LED") implementations are described more fully below with reference to the accompanying drawings. The examples are not mutually exclusive and features found in one example may be combined with features found in one or more other examples to implement further embodiments. Accordingly, it will be understood that the examples shown in the drawings are provided for illustrative purposes only and are not intended to limit the present disclosure in any way. Like numbers refer to like elements throughout.

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 element. For example, a first element could be termed a second element and a second element could 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.

It will be understood that when an element such as a layer, region or substrate is referred to as being "on" or "extending" another element, it can 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 "directly extending 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 can be directly connected or coupled to the other element and/or be 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.

Relative terms such as "lower," "upper," "lower," "horizontal" or "vertical" may be used herein to describe one element, layer or region's relationship 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.

Further, whether an LED, LED array, electrical component, and/or electronic component is housed on one, two, or more electronic boards may also depend on design constraints and/or applications.

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 may include light emitting diodes, resonant cavity light emitting diodes, vertical cavity laser diodes, or edge emitting lasers, among others. For example, LEDs may be attractive candidates for many different applications due to their compact size and lower power requirements. For example, they may be used as light sources (e.g., flash and camera flash) for handheld battery powered devices such as cameras and cell phones. For example, they may also be used for automotive lighting, heads-up display (HUD) lighting, gardening lighting, street lighting, video lighting, general lighting (e.g., home, store, office and studio lighting, theatre/stage lighting and architectural lighting), augmented Reality (AR) lighting, virtual Reality (VR) lighting, display backlighting, and IR spectroscopy. A single LED may provide light that is less bright than an incandescent light source, and thus, a multi-junction device or LED array (such as a monolithic LED array, micro LED array, etc.) may be used for applications where higher brightness is desired or required.

The present specification is directed to a hybrid driving scheme for driving desaturated RGB color LEDs to produce white with high Color Rendering Index (CRI) and high efficiency, particularly color LEDs that use phosphor conversion to address color mixing. The forward voltage of a direct color LED decreases with increasing dominant wavelength. The LEDs are preferably driven with a multi-channel DC/DC converter. New phosphor-converted color LEDs targeting high efficacy (efficiency) and CRI have been created, providing new possibilities for Correlated Color Temperature (CCT) tuning applications. The new color LED has a desaturated (soft) color point and can be mixed to achieve a white color with 90+ CRI over a wide CCT interval. Other LEDs may have an 80 CRI embodiment, or even 70 CRI embodiments may be used. These possibilities require LED circuits to achieve and maximize this potential. Meanwhile, the control circuit can be compatible with a single-channel constant-current driver so as to be convenient for market adoption.

In general, the LED driving circuit is formed using an analog method or a Pulse Width Modulation (PWM) method. In an analog driver, all colors are driven simultaneously. Each LED is driven independently by providing a different current to each LED. Analog drivers cause color shift and there is currently no way to change the current three-way approach. Analog driving often results in LEDs of certain colors being driven to a low current mode and at other times to a very high current mode. Such a wide dynamic range presents challenges to the sensing and control hardware.

In PWM, each color is turned on in a high-speed sequence. Each color is driven with the same current. The mixed colors are controlled by varying the duty cycle of each color. That is, one color may be driven twice as long as the other color to add to the mixed color. Since human vision is unable to perceive very rapidly changing colors, light appears to have a single color.

For example, a first LED is driven with a current for a certain amount of time, then a second LED is driven with the same current for a certain amount of time, and then a third LED is driven with the current for a certain amount of time. The mixed colors are controlled by varying the duty cycle of each color. For example, if you have one RGB LED and desire a particular output, based on the perception of the human eye, red may be driven for one part of the period, green may be driven for a different part of the period, and blue driven for yet another part of the period. Instead of driving the red LED at a lower current, the red LED is driven at the same current for a shorter time. This example demonstrates the disadvantage of PWM, where the underutilization of LEDs results in inefficiency.

A comparison of the two driving schemes is summarized in table 1 below, table 1 illustrating the advantages and disadvantages of each driving technique. As shown, analog driving provides good LED utilization, sharing peak current for all colors, and generally good LED efficacy and overall efficacy. PWM provides good color point predictability because all LEDs are driven by peak currents and a relatively simple and efficient controller.

Table 1: advantages and disadvantages of analog and PWM drive schemes

	Simulation	PWM
			LED utilization rate	+	-
Color point predictability	Some colors may require only a few mA	+all LEDs conduct peak current
			Rated current	+sharing peak current for all colors	All LEDs conduct peak current
Controller complexity	-complexity	+simple
			Controller efficiency	-	+
LED efficacy	+	-
			Overall efficacy	+	-

The present driving scheme includes a hybrid scheme to achieve the combined advantages of the analog and PWM methods described above. The hybrid system distributes the input current between the two colors at a time while treating the set of two colors as virtual LEDs to overlap PWM time slices. This driving scheme achieves the same level of overall efficacy as analog driving using the same number of LEDs, while maintaining good color predictability. Compared to the hybrid driving scheme, the PWM driving scheme may require 50% more LEDs to achieve the same efficacy. The advantages of the present hybrid drive scheme are added to table 1 and presented in table 2 below. Hybrid driving achieves advantages in the utilization of the LEDs, current rating, LED efficacy, and overall efficacy of the analog driver, as well as in color point predictability and controller complexity of using the included PWM driver.

Table 2: advantages and disadvantages of analog, PWM and hybrid drive schemes

	Simulation	PWM	Mixing
				LED utilization rate	+	-	+
Color point predictability	Some colors may require only a few mA	+all LEDs conduct peak current	+
				Rated current	+sharing peak current for all colors	All LEDs conduct peak current	+
Controller complexity	-complexity	+simple	+
				Controller efficiency	-	+	-
LED efficacy	+	-	+
				Overall efficacy	+	-	+
Compatibility with drivers using PWM dimming	Whether or not	Is that	Depending on PWM frequency

Fig. 1A illustrates CIE chromaticity diagram 1 representing a color space. The color space is a three-dimensional space; that is, one color is specified by a set of three numbers that specify the color and brightness of a particular uniform visual stimulus. These three numbers may be the International Commission on illumination (CIE) coordinates X, Y and Z, or other values such as hue, color, and brightness. Based on the fact that the human eye has three different types of color-sensitive cones, the eye's response is best described by these three "tristimulus values".

Chromaticity diagram 1 is a color space projected into a two-dimensional space, ignoring luminance. For example, the standard CIE XYZ color space corresponds to the chromaticity space specified by two chromaticity coordinates x, y. Chromaticity is an objective specification of color quality, independent of its brightness. Chromaticity consists of two independent parameters, often designated hue and color. Colors may alternatively be referred to as saturation, chromaticity, intensity, or excitation purity. Chromaticity diagram 1 includes colors that are perceivable by the human eye. Chromaticity diagram 1 uses parameters based on the Spectral Power Distribution (SPD) of light emitted from a colored object and is factored by a sensitivity curve that has been measured for the human eye. Any color can be accurately expressed with two color coordinates x and y. By combining a given set of three primary colors (i.e., blue, green, and red), the color that can be matched is represented on the chromaticity diagram by triangle 2, which connects the coordinates of the three colors, namely red coordinate 3, green coordinate 4, and blue coordinate 5. Triangle 2 represents the color gamut.

Chromaticity diagram 1 includes the planckian locus, or Black Body Line (BBL) 6.BBL 6 is the path or locus that the color of an incandescent blackbody will take in a particular chromaticity space when the temperature of the blackbody changes. It ranges from dark red to orange, yellow-white, white at low temperatures, and finally blue-white at very high temperatures. In general, the human eye prefers white points that are not too far from BBL 6. The color dots above BBL 6 will look too green, while the color dots below will look too pink.

Fig. 1B illustrates a diagram 10, the diagram 10 illustrating different CCTs and their relationship to BBL 6. Three primary colors (R, G, B) are used and two colors are driven simultaneously creating three virtual color points (R-G, R-B, G-B), which creates a color gamut 2.1 for the present driving scheme. The new gamut 2.1 is smaller than the old gamut 2. Between 2700K and 4000K, the color line extends within 3 steps below BBL 6. For warm color CCT, this deviation is within human viewing preferences slightly below BBL 6. As will be appreciated by one of ordinary skill in the art, the primary color point may be adjusted such that the color gamut 2.1 completely encloses the adjustable wavelength band of interest. By forcing the current to be split between the two colors, efficiency and utilization are improved.

FIG. 1C illustrates mixing for RGB adjustmentAn example circuit 20 of the drive circuit. The circuit 20 includes an LED driver 25 electrically connected to a voltage regulator 24, both of which together generate a regulated current I ₀ -and analog current distribution circuit 21, multiplexer array 22, and LED array 23.

The LED array 23 may include one or more LEDs of a first color (color 1) 26, one or more LEDs of a second color (color 2) 27, and one or more LEDs of a third color (color 3) 28, which are designed to be tuned using a hybrid drive circuit. In one embodiment of circuit 20, color 1 is green, color 2 is red, and color 3 is blue, although any set of colors may be used for color 1, color 2, and color 3. As will be appreciated, assigning colors to particular channels is merely a design choice, and the current description uses color 1 LED 26, color 2 LED 27, and color 3 LED 28, and embodiments in which color 1 is described as green, color 2 as red, and color 3 as blue may also be described in order to provide a complete understanding of the hybrid drive circuits described herein, although other designs may be envisaged.

The circuit 20 comprises an analog current distribution circuit 21 to distribute the incoming current I ₀ Divided into two currents I ₁ 、I ₂ . Such an analog current distribution circuit 21 is described in U.S. patent application No. 16/145053 entitled "any ratio analog current distribution circuit", which is incorporated herein by reference as if set forth in its entirety. The analog current distribution circuit 21 may take the form of a drive circuit to provide equal current for each of the two colors. The analog current distribution circuit 21 can address any mismatch in forward voltages between different color LEDs while allowing accurate control of the drive current for each color. Alternatively, the analog current distribution circuit 21 may allow unequal current distribution, which may not be achieved by simply switching on two strings. As will be appreciated, other analog current distribution circuits may be utilized without departing from the spirit of the present invention. For a complete understanding of the hybrid drive circuit described herein, an analog current distribution circuit 21 is provided as an exemplary divider.

The analog current distribution circuit 21 may be mounted on a Printed Circuit Board (PCB) to operate with the LED driver 25 and the LED array 23. The LED driver 25 may be a conventional LED driver known in the art. The analog current distribution circuit 21 may allow the LED driver 25 to be used in applications that utilize two or more LED arrays 23.

Each current channel of the analog current distribution circuit 21 may include a sense resistor. For example, in an embodiment having two current channels, the analog current distribution circuit 21 includes: a first sense resistor (Rs 1) 29 to sense a first voltage of the first current path 31 at Vsense 1; and a second sense resistor (Rs 2) 30 to sense a second voltage at Vsense2 for a second current path 32. The voltage at Vsense1 represents the current flowing through the first sense resistor (Rs 1) 29, and the voltage at Vsense2 represents the current flowing through the second sense resistor (Rs 2) 30.

The analog current distribution circuit 21 includes a computing device 37. The computing device 37 is configured to compare the first sense voltage Vsense1 and the second sense voltage Vsense2 to determine the set voltage Vset. If the first sense voltage Vsense1 is lower than the second sense voltage Vsense2, the computing device 37 is configured to increase Vset. If the first sense voltage Vsense1 is greater than the second sense voltage Vsense2, the computing device 37 is configured to decrease the set voltage Vset.

In particular, the computing device 37 may include an operational amplifier (op amp) 38, a capacitor 39 between the location of the set voltage Vset and ground, and a resistor 41 in parallel with the capacitor 39. The first sense voltage Vsense1 and the second sense voltage Vsense2 are fed to the op amp 38. The computing device 37 may be configured to compare the first sense voltage Vsense1 with the second sense voltage Vsense2 by subtracting the first sense voltage Vsense1 from the second sense voltage Vsense2. When op amp 38 is in regulation, computing device 37 may be configured to convert the difference between first sense voltage Vsense1 and second sense voltage Vsense2 into a charging current to charge capacitor 39 to increase set voltage Vset when first sense voltage Vsense1 is less than second sense voltage Vsense2. The computing device 37 may be configured to convert the difference between the first sense voltage Vsense1 and the second sense voltage Vsense2 into the discharge resistor 41 to decrease the set voltage Vset when the first sense voltage Vsense1 is greater than the second sense voltage Vsense2.

Thus, if the first sense voltage Vsense1 is higher than the second sense voltage Vsense2, the computing device 37 may decrease the set voltage Vset, which in turn decreases the first gate voltage Vgate1 that supplies power to the first current channel 31. Stated another way, when the op amp 38 is regulating, the first sense voltage Vsense1 is approximately equal to the second sense voltage Vsense2. Thus, during steady state, the ratio of the current of the first current channel 31 to the current of the second current channel 32 is equal to the ratio of the value of the second sense resistor Rs2 to the value of the first sense resistor Rs1, and the following equation is satisfied:

i_r1=v_set/r_s1; in the equation 1,

i_r2=v_set/r_s2, equation 2.

Thus, when the value of the first sense resistor Rs1 is equal to the value of the second sense resistor Rs2, the current I_Rs1 flowing through the first resistor is equal to the current I_Rs2 flowing through the second resistor, and the current distribution circuit 20 divides the current into two equal parts, assuming that the current drawn by the auxiliary circuit (such as supply voltage generation) is negligible. It should be noted that the computing device 37 illustrated in fig. 1C is one of many possible implementations, as will be appreciated by one of ordinary skill in the art.

The set voltage Vset may be fed to a voltage controlled current source, which may be implemented with a first op amp 33. The first op amp 30 may provide a first gate voltage Vgate1. A first gate voltage Vgate1 can be input to supply a driving current I ₁ Is provided, the first transistor 34 of (a). The first transistor 34 may be a conventional Metal Oxide Semiconductor Field Effect Transistor (MOSFET). The first transistor 34 may be an n-channel MOSFET.

The second transistor 35 may provide a drive current I ₂ . The second transistor 35 may be a conventional MOSFET. The second transistor 35 may be an n-channel MOSFET. The second transistor may be turned on only when the first current path 31 is in regulation. Second gate voltageVgate2 can flow through the second transistor 35.

The second gate voltage Vgate2 may be fed to the REF input of the shunt regulator 36. In an embodiment, shunt regulator 36 has an internal reference voltage of 2.5V. Shunt regulator 36 may sink large currents when the voltage applied at the REF node is greater than 2.5V. Shunt regulator 36 may sink very little quiescent current when the voltage applied at the REF node is below 2.5V.

The large sink current may pull the gate voltage of the second transistor 35 down to a level below its threshold, which may turn off the second transistor 35. Shunt regulator 36 may not be able to pull the cathode to a forward voltage (Vf) greater than the diode below its REF node. Accordingly, the second transistor 35 may have a threshold voltage higher than 2.5V. Alternatively, a shunt regulator with a lower internal reference voltage (such as 1.24V) may be used.

The circuit 20 comprises a multiplexer array 22 electrically connecting two of the three LEDs 26, 27, 28 to two current sources I created with an analog current distribution circuit 21 ₁ 、I ₂ . As illustrated in circuit 20, multiplexer array 22 may include four MOSFETs S1 (11), S2 (12), S3 (13), S4 (14), also referred to as switches. Multiplexer array 22 will I at a time ₁ And I ₂ Two colors are introduced into the LED array 23. As indicated in the following table, it is necessary to control MOSFET S1 and MOSFET S4 14 because MOSFET S2 and MOSFET S3 13 are inverted values of MOSFET S1 11 and MOSFET S4 14 (i.e., s2=inverted S1 and s3=inverted S4). As defined in the following equation,

R _{s 1} * I ₁ = R _{s 2} * I ₂ equation 3,

I ₀ = I ₁ + I ₂ equation 4.

In operation, the hybrid drive scheme utilizes the analog current distribution circuit 21 to drive two colors in the LED array 23 simultaneously, and then overlaps the PWM time slices with a third color in the LED array 23. The utilization of the LEDs in array 23 in embodiments where color 1 is green, color 2 is red, and color 3 is blue is shown in table 3.

Table 3: operating values of four switches

Color of	S1（RA0）	S2（= INV S1）	S3（= INV S4）	S4（RA1）
					R-G	Opening device	Switch for closing	Opening device	Switch for closing
G-B	Opening device	Switch for closing	Switch for closing	Opening device
					R-B	Switch for closing	Opening device	Switch for closing	Opening device
R	Switch for closing	Opening device	Opening device	Switch for closing

When two colors are driven simultaneously, a virtual color point is created. Current I ₁ And I ₂ The ratio between may be predefined (i.e., 1:1 or slightly different to maximize efficiency, although any ratio may be used). Using three colors in the LED array 23, three virtual color points (R-G, R-B, G-B) plus the primary color R/G/B (fourth color point for mixing) can be created. The triangle formed by the three virtual color points (R-G, R-B, G-B) defines the color gamut of the new driving scheme.

Table 4 summarizes the timing of the operation of the 3-channel LED driven hybrid drive scheme. As will be appreciated by one of ordinary skill in the relevant art, the particular order of colors is not necessarily important. In an embodiment of the hybrid drive scheme, the color pairs may be arranged or rearranged in a manner that minimizes the complexity of the PWM logic embodiment. To provide sample (sample) timing, table 4 is shown below. During subinterval T1, the red-green color pair may be powered. During the sub-interval T2, the green-blue color pair may be powered. During subinterval T3, the red-blue color pair may be powered. The sum of the sub-intervals T1, T2 and T3 in combination substantially covers the switching period T.

Table 4: timing sequence

Fig. 1D illustrates a microcontroller 40 that may be used with the computing device 37 to handle complex signal processing with fewer PCB resources than the analog circuitry described above. The microcontroller 40 handles the input signals and the operation of S1 and S4. The microcontroller 40 can monitor the absolute value of the input current by sensing VSENSE1 at input 15 and sensing the board temperature with NTC 17. The two readings VSENSE1, NTC 17 at input 15 can be used to compensate for color shift due to drive current and temperature. 0-10V represents the control input 16. The microcontroller 40 may be mapped to a CCT adjustment curve. The microcontroller 40 translates the incoming instruction into operation of the multiplexer array 23. Specifically, the microcontroller 40 may provide the first output signal 11 to control the switch S1 and the second output signal 14 to control the switch S4.

Fig. 1E illustrates a color map 42 of the circuit 20 with a red LED (or red LED array) in a center position. The color chart 42 is superimposed on the color chart of fig. 1B. Color chart 42 depicts the achievable color gamut 43 using RB-RG-BG in circuit 20 for 2700K to 6000K (matching color gamut 2.1 from FIG. 1B), and the RG-RB-R in circuit 20 for 2500K and below color gamut 44. The color gamut 43 can be provided efficiently. The color gamut 44 may be provided with reduced efficiency. The combination of gamut 43 and gamut 44 from circuit 20 approximates gamut 2 described above with respect to fig. 1A. Although the combination of gamut 43 and gamut 44 does not fully cover the entirety of gamut 2, the combination of gamut 43 and gamut 44 may be sufficient for many applications and may be a reasonable compromise for the increased efficiency achieved by hybrid circuit 20.

Fig. 1F illustrates a color map 45 of the circuit 20 with the green LED (or green LED array) in a centered position. The color chart 45 is superimposed on the color chart of fig. 1B. Color chart 45 depicts the use of RB-RG-BG in circuit 20 for a reachable color gamut 43 of 2700K to 6000K (matching color gamut 2.1 from FIG. 1B), and RG-GB-G in circuit 20 for a color gamut 46 above BBL 6. The color gamut 43 can be provided efficiently. The color gamut 46 may be provided with reduced efficiency. The combination of gamut 43 and gamut 46 from circuit 20 approximates gamut 2 described above with respect to fig. 1A. Although the combination of gamut 43 and gamut 46 does not fully cover the entirety of gamut 2, the combination of gamut 43 and gamut 46 may be sufficient for many applications and may be a reasonable compromise for the increased efficiency achieved by hybrid circuit 20.

Fig. 1G illustrates a color map 47 of the circuit 20 with a blue LED (or blue LED array) in a central position. The color chart 47 is superimposed on the color chart of fig. 1B. Color chart 47 depicts the use of RB-RG-BG in circuit 20 for a reachable color gamut 43 of 2700K to 6000K (matching color gamut 2.1 from B of FIG. 1), and the use of GB-RB-B in circuit 20 for a color gamut 48 exceeding 6500K. The color gamut 43 can be provided efficiently. The color gamut 48 may be provided with reduced efficiency. The combination of gamut 43 and gamut 48 from circuit 20 approximates gamut 2 described above with respect to fig. 1A. Although the combination of gamut 43 and gamut 48 does not fully cover the entirety of gamut 2, the combination of gamut 43 and gamut 48 may be sufficient for many applications and may be a reasonable compromise for the increased efficiency achieved by hybrid circuit 20.

From fig. 1E, 1F, 1G, it is evident that by simply varying the LED in the center of the circuit 20, all parts of the color gamut 2 can be reached. In each LED configuration, the color gamut 2.1 is covered, with the addition of an additional part of the color gamut 2. Such coverage may be adequate for many applications and may be a compromise for increased efficiency.

Fig. 1H illustrates another hybrid drive circuit 50. The circuit 50 may provide an increased color gamut from the circuit 20. The circuit 50 includes the analog current distribution circuit 21, the LED array 23, the voltage regulator 24, and the LED driver 25, as described above with respect to fig. 1C. As in fig. 1C, the LED array 23 may include one or more color 1 LEDs 26, one or more color 2 LEDs 27, and one or more color 3 LEDs 28, which are designed to be tuned using a hybrid drive circuit. A multiplexer array 52 is utilized in the circuit 50. In one embodiment of circuit 50, color 1 is green, color 2 is red, and color 3 is blue, although any set of colors may be used for color 1, color 2, and color 3. As will be appreciated, assigning colors to particular channels is merely a design choice, and the current description uses color 1 LED 26, color 2 LED 27, and color 3 LED 28, and embodiments in which color 1 is described as green, color 2 as red, and color 3 as blue may also be described in order to provide a complete understanding of the hybrid drive circuits described herein, although other designs may be envisaged.

Multiplexer array52 electrically connecting two of the three LEDs 26, 27, 28 to two current sources I created by the analog current distribution circuit 21 ₁ 、I ₂ . As illustrated in circuit 50, multiplexer array 52 may include five MOSFETs S1 (51), S2 (53), S3 (54), S4 (56), S5 (57), also referred to as switches. Multiplexer array 52 will I each time ₁ And I ₂ Two colors are introduced into the LED array 23. Control of MOSFET S1, MOSFET S4, and X is required because MOSFET S2 and MOSFET S3, 53 are inverted values of MOSFET S1 and MOSFET S4, 56, and MOSFET S5, 57 is an inverted combination of MOSFET S1 and MOSFET S2, 53. In particular, the method comprises the steps of,

S2 = equation 5,

S3 = equation 6,

S5 = equation 7.

Table 5 illustrates possible combinations provided by circuit 50. The utilization of the LEDs in array 23 in embodiments where color 1 is green, color 2 is red, and color 3 is blue is shown in table 5.

Table 5: operating values of five switches

Color I ₁	Color I ₂	S1	S2	S3	S4	S5
							R	R	0	1	1	0	0
R	B	0	1	0	1	0
							R	G	1	0	1	0	0
G	B	1	0	0	1	0
							B	R	0	0	1	0	1
B	B	0	0	0	1	1

Fig. 1I shows a color chart 55 of the circuit 50, wherein the red and blue LEDs (or red and blue LED arrays) are driven by an analog current. The color chart 55 is superimposed on the color chart of fig. 1B. Color map 55 depicts reachable color gamut 43 (matching color gamut 2.1 from fig. 1B), color gamut 44, and color gamut 48. The color gamut 43 can be provided efficiently. The color gamuts 44, 48 may be provided with reduced efficiency. The combination of gamuts 43, 44, 48 from circuit 50 approximates gamut 2 described above with respect to fig. 1A. Although the combination of gamuts 43, 44, 48 does not fully cover the entirety of gamut 2, the combination of gamuts 43, 44, 48 may be sufficient for many applications and may be a reasonable compromise for the increased efficiency achieved by hybrid circuit 50.

Fig. 1J illustrates a color chart 60 of the circuit 50 in which the red and green LEDs (or red and green LED arrays) are driven by an analog current. The color chart 60 is superimposed on the color chart of fig. 1B. Color map 60 depicts reachable color gamut 43 (matching color gamut 2.1 from FIG. 1B), color gamut 44, and color gamut 46. The color gamut 43 can be provided efficiently. The color gamuts 44, 46 may be provided with reduced efficiency. The combination of gamuts 43, 44, 46 from circuit 50 approximates the gamuts described above with respect to fig. 1A. Although the combination of gamuts 43, 44, 46 does not fully cover the entirety of gamut 2, the combination of gamuts 43, 44, 46 may be sufficient for many applications and may be a reasonable compromise for the increased efficiency achieved by hybrid circuit 50.

Fig. 1K illustrates a color plot 65 of circuit 50 in which blue and green LEDs (or blue LED array and green LED array) are driven by an analog current. The color chart 65 is superimposed on the color chart of fig. 1B. Color map 65 depicts reachable color gamut 43 (matching color gamut 2.1 from FIG. 1B), color gamut 46, and color gamut 48. The color gamut 43 can be provided efficiently. The color gamuts 46, 48 may be provided with reduced efficiency. The combination of gamuts 43, 46, 48 from circuit 50 approximates gamut 2 described above with respect to fig. 1A. Although the combination of gamuts 43, 46, 48 does not fully cover the entirety of gamut 2, the combination of gamuts 43, 46, 48 may be sufficient for many applications and may be a reasonable compromise for the increased efficiency achieved by hybrid circuit 50.

Fig. 1L illustrates another hybrid drive circuit 70. The circuit 70 may provide an increased color gamut from the circuits 20, 50. The circuit 70 includes the analog current distribution circuit 21, the LED array 23, the voltage regulator 24, and the LED driver 25, as described above with respect to fig. 1C. As in fig. 1C, the LED array 23 may include one or more color 1 LEDs 26, one or more color 2 LEDs 27, and one or more color 3 LEDs 28, which are designed to be tuned using a hybrid drive circuit. A multiplexer array 72 is utilized in the circuit 70. In one embodiment of circuit 70, color 1 is green, color 2 is red, and color 3 is blue, although any set of colors may be used for color 1, color 2, and color 3. As will be appreciated, assigning colors to particular channels is merely a design choice, and the current description uses color 1 LED 26, color 2 LED 27, and color 3 LED 28, and embodiments in which color 1 is described as green, color 2 as red, and color 3 as blue may also be described in order to provide a complete understanding of the hybrid drive circuits described herein, although other designs may be envisaged.

A multiplexer array 72 that will be three Two of the LEDs 26, 27, 28 are electrically connected to two current sources I created by the analog current distribution circuit 21 ₁ 、I ₂ . As illustrated in circuit 70, multiplexer array 72 may include six MOSFETs S1, S2, S3, S4, S5, S6, also referred to as switches. Multiplexer array 72 will I at a time ₁ And I ₂ Two colors are introduced into the LED array 23. Control of the MOSFETs S1, MOSFETs S4 and X1, X2 is required because MOSFETs S2, MOSFETs S3 and MOSFETs S5 are inverted values of MOSFETs S1 and MOSFETs S4 and MOSFET S6 is an inverted combination of MOSFETs S4 and MOSFETs S5. In particular, the method comprises the steps of,

S2 = equation 8,

S3 = equation 9,

S5 = equation 10,

S6 = equation 11.

Table 6 illustrates possible combinations provided by circuit 70. The utilization of the LEDs in array 23 in embodiments where color 1 is green, color 2 is red, and color 3 is blue is shown in table 6.

Table 6: operating values of six switches

Color I ₁	Color I ₂	S1	S2	S3	S4	S5	S6
								R	R	1	0	0	1	0	0
R	G	1	0	0	0	1	0
								R	B	1	0	0	0	0	1
G	R	0	1	0	1	0	0
								G	G	0	1	0	0	1	0
G	B	0	1	0	0	0	1
								B	R	0	0	1	1	0	0
B	G	0	0	1	0	1	0
								B	B	0	0	1	0	0	1

For example, by the method of the first embodiment in I ₁ And I ₂ Alternate the same color, I ₁ And I ₂ Any mismatch between them can be averaged out, such as by chopping.

Fig. 1M illustrates a color map 75 of the circuit 70 providing full gamut 2 coverage. The color chart 75 is superimposed on the color chart of fig. 1B. The color map 75 depicts fully reachable color gamuts 43, 44, 46, 48 that match the color gamuts described above with respect to fig. 1A.

Fig. 1N illustrates a method 80 for hybrid driving of RGB color adjustment driving. Method 80 may be used with circuit 20, circuit 50, or circuit 70 to produce 1/2 gamut, 3/4 gamut, and full gamut outputs as described herein. At step 82, the method 80 splits an input current into a first current and a second current via an analog current splitting circuit. At step 84, the method 80 provides a first current to a first one of the three color LEDs and simultaneously provides a second current to a second one of the three color LEDs during a first portion of the cycle via the multiplexer array. At step 86, the method 80 provides a first current to a second one of the three color LEDs and simultaneously provides a second current to a third one of the three color LEDs during a second portion of the cycle via the multiplexer array. At step 88, the method 80 provides a first current to a first one of the three color LEDs and simultaneously provides a second current to a third one of the three color LEDs during a third portion of the cycle via the multiplexer array. In method 80, the splicing of the first current and the second current into different pairs of LEDs may occur using Pulse Width Modulation (PWM) time slicing to provide drive to a third of the three color LEDs. In method 80, the PWM between the first of the three color LEDs and the combination of the second of the three color LEDs and the third of the three color LEDs may be substantially equal or different depending on the desired driving characteristics of the LEDs.

Fig. 2 is a top view of an electronic board 310 of an integrated LED lighting system according to one embodiment. In alternative embodiments, two or more electronic boards may be used for the LED lighting system. For example, the LED arrays may be on separate electronic boards, or the sensor modules may be on separate electronic boards. In the illustrated example, the electronic board 310 includes a power module 312, a sensor module 314, a connection and control module 316, and an LED attachment area 318 reserved for attaching an LED array to a substrate 320.

Substrate 320 can be any board capable of mechanically supporting and providing electrical coupling to electrical components, electronic components, and/or electronic modules using conductive connectors, such as tracks, traces, pads, vias, and/or wires. Substrate 320 may include one or more metallization layers disposed between or over one or more layers of non-conductive material, such as a dielectric composite material. The power module 312 may include electrical and/or electronic components. 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. One of the circuits 20, 50, 70 may be included within the power module 312.

The sensor module 314 may include sensors required for the 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 lighting, and gardening lighting applications may be turned off/on and/or adjusted based on several different sensor inputs, such as the presence of a detected user, a detected ambient lighting condition, a detected weather condition, or based on time of day/night. This may include, for example, adjusting the intensity of the light output, the shape of the light output, the color of the 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 sensor itself may be an LED, such as an IR detector LED. By way of another example, for camera flash applications, images and/or other optical sensors or pixels may be used to measure the illumination of the scene to be acquired such that flash illumination color, intensity illumination pattern, and/or shape may be optimally calibrated. In an alternative embodiment, the electronic board 310 does not include a sensor module.

The connection and control module 316 may include a system microcontroller and any type of wired or wireless module configured to receive control inputs from external devices. By way of example, wireless modules may include bluetooth, 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 the LED lighting system and configured or configurable to receive input (such as sensor data and data fed back from the LED modules) from the wired or wireless modules or other modules in the LED system and provide control signals to the other modules based thereon. The 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 media include Read Only Memory (ROM), random Access Memory (RAM), registers, cache memory, and semiconductor memory devices. The memory may be included as part of the microcontroller or may be implemented on or elsewhere than on the electronic circuit board 310. One of the circuits 20, 50, 70 may be included within the connection and control module 316.

The term module, as used herein, may refer to electrical and/or electronic components disposed on a separate circuit board that may be soldered to one or more electronic boards 310. However, the term module may also refer to electrical and/or electronic components that provide similar functionality, but which may be soldered separately to one or more circuit boards in the same area or in different areas.

Fig. 3A is a top view of an electronic board 310 with an LED array 410 attached to a substrate 320 at an LED device attachment region 318 in one embodiment. The electronic board 310, together with the LED array 410, represents an LED lighting system 400A. Additionally, power module 312 receives a voltage input at Vin 497 and a control signal from connection and control module 316 via trace 418B and provides a drive signal to LED array 410 via trace 418A. The LED array 410 is turned on and off via a drive signal from the power module 312. In the embodiment shown in fig. 3A, the connection and control module 316 receives sensor signals from the sensor module 314 via traces 418. One of the circuits 20, 50, 70 may be included within the power module 312 and/or the connection and control module 316.

Fig. 3B illustrates one embodiment of a dual channel integrated LED lighting system with electronic components mounted on both surfaces of a circuit board 499. As shown in fig. 3B, the LED lighting system 400B includes a first surface 445A having an input that receives a dimmer signal and an AC power signal, and an AC/DC converter circuit 412 mounted thereon. LED system 400B includes a second surface 445B having a dimmer interface circuit 415, DC-DC converter circuits 440A and 440B, a connection and control module 416 (in this example a wireless module) having a microcontroller 472, and an LED array 410 mounted thereon. LED array 410 is driven by two independent channels 411A and 411B. In alternative embodiments, a single channel may be used to provide the drive signal to the LED array, or any number of multiple channels may be used to provide the drive signal to the LED array. For example, fig. 3E illustrates an LED lighting system 400D having 3 channels, and is described in further detail below.

LED array 410 may include two sets of LED devices. In an example embodiment, the LED devices of group a are electrically coupled to the first channel 411A and the LED devices of group B are electrically coupled to the second channel 411B. Each of the two DC-DC converter circuits 440A and 440B may provide a respective drive current via a single channel 411A and 411B, respectively, for driving a respective LED group a and B in the LED array 410. The LEDs of one of the LED groups may be configured to emit light having a different color point than the LEDs of the second group of LEDs. By controlling the current and/or duty cycle applied by the individual DC/DC converter circuits 440A and 440B via the individual channels 411A and 411B, respectively, the control of the composite color point of the light emitted by the LED array 410 can be adjusted within one interval. Although the embodiment shown in fig. 3B does not include a sensor module (as described in fig. 2 and 3A), alternative embodiments may include a sensor module.

The illustrated LED lighting system 400B is an integrated system in which the LED array 410 and circuitry for operating the LED array 410 are disposed on a single electronic board. Connections between modules on the same surface of circuit board 499 may be electrically coupled through surface or subsurface interconnections, such as traces 431, 432, 433, 434, and 435, or metallization (not shown), for exchanging, for example, voltage, current, and control signals between modules. The connections between modules on opposite surfaces of circuit board 499 may be electrically coupled through board interconnects such as vias and metallization (not shown).

Fig. 3C illustrates an embodiment of an LED lighting system in which the LED array is on an electronic board separate from the driver and control circuitry. The LED lighting system 400C includes a power module 452 on a separate electronic board from the LED module 490. One of the circuits 20, 50, 70 may be included within the power module 452. The power module 452 may include the AC/DC converter circuit 412, the sensor module 414, the connection and control module 416, the dimmer interface circuit 415, and the DC/DC converter circuit 440 on a first electronic board. The LED module 490 may include embedded LED calibration and setup data 493, and the LED array 410 on a second electronic board. 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, which may electrically and communicatively couple the two modules. The embedded LED calibration and setup data 493 may include any data needed by other modules within a given LED lighting system to control how LEDs in an LED array are driven. In one embodiment, the embedded calibration and setup data 493 may include data required by the microcontroller to generate or modify control signals that instruct the driver to provide power to each group of LEDs a and B using, for example, pulse Width Modulation (PWM) signals. In this example, the calibration and setup data 493 may inform the microcontroller 472 regarding, for example, the number of power channels to be used, the desired color point of the composite light to be provided by the entire LED array 410, and/or the percentage of power provided to each channel by the AC/DC converter circuit 412.

Fig. 3D illustrates a block diagram of an LED lighting system having an LED array and some electronics on an electronic board separate from the driver circuit. LED system 400D includes power conversion module 483 and LED module 481 on separate electronic boards. One of the circuits 20, 50, 70 may be included within the power conversion module 483. The power conversion module 483 may include an AC/DC converter circuit 412, a dimmer interface circuit 415, and a DC-DC converter circuit 440, and the LED module 481 may include embedded LED calibration and setup data 493, an LED array 410, a sensor module 414, and a connection and control module 416. The power conversion module 483 may provide the LED driver input signal 485 to the LED array 410 via a wired connection between two electronic boards.

Fig. 3E is a diagram of an example LED lighting system 400D showing a multi-channel LED driver circuit. In the illustrated example, system 400D includes a power module 452 and an LED module 481, the LED module 481 including embedded LED calibration and setting data 493 and three sets of LEDs 494A, 494B, and 494C. Although three groups of LEDs are shown in fig. 3E, one of ordinary skill in the art will recognize that any number of LED groups may be used consistent with the embodiments described herein. Further, while the individual LEDs within each group are arranged in series, in some embodiments they may be arranged in parallel.

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 set of LEDs 494A, a cold white light source via a second set of LEDs 494B, and a neutral white light source via a third set of LEDs 494C. The warm white light source via the first set of LEDs 494A may include one or more LEDs configured to provide white light having a CCT of approximately 2700K. The cold white light source via the second set of LEDs 494B may include one or more LEDs configured to provide white light having a CCT of approximately 6500K. The neutral white light source via the third set of LEDs 494C may include one or more LEDs configured to provide light having a CCT of about 4000K. While various white 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 having various overall colors.

The power module 452 may include a dimmable engine (not shown) that may be configured to supply power to the LED array 491 through three separate channels (indicated in fig. 3E as LED1+, LED2+, and LED 3+). More particularly, the dimmable engine may be configured to supply a first PWM signal to a first set of LEDs 494A (such as a warm white light source) via a first channel, a second PWM signal to a second set of LEDs 494B via a second channel, and a third PWM signal to a third set of LEDs 494C via a third channel. Each signal provided via a respective channel may be used to power a corresponding LED or group of LEDs, and the duty cycle of the signal may determine the total duration of the on and off states of each respective LED. The duration of the on and off states may result in an overall light effect that may have a duration-based light property (e.g., correlated Color Temperature (CCT), color point, or brightness). In operation, the dimmable engine may vary the relative magnitudes of the duty cycles of the first, second, and third signals to adjust the respective light attributes of each group of LEDs to provide the composite light having the desired emission from the LED array 491. As described above, the light output of LED array 491 may have a color point based on a combination (e.g., mixture) of light emissions from each set of LEDs 494A, 494B, and 494C.

In operation, the power module 452 may receive control inputs generated based on user and/or sensor inputs and provide signals via separate channels to control the composite color of light output by the LED array 491 based on the control inputs. In some embodiments, a user may provide input to the LED system for controlling the DC/DC converter circuit by turning a knob or moving a slider, which may be part of a sensor module (not shown), for example. 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 communicate an indication of a desired color to a wireless module (not shown).

Fig. 4 shows an example system 550 that includes an application platform 560, LED lighting systems 552 and 556, and secondary optics 554 and 558.LED illumination system 552 generates a light beam 561 shown between arrows 561a and 561 b. LED illumination system 556 can generate light beam 562 between arrows 562a and 562 b. In the embodiment shown in fig. 4, light emitted from LED illumination system 552 passes through secondary optic 554, and light emitted from LED illumination system 556 passes through secondary optic 558. In alternative embodiments, beams 561 and 562 do not pass through any secondary optics. The secondary optic may be or may include one or more light guides. One or more of the light guides may be edge-lit or may have an internal opening defining an internal edge of the light guide. LED illumination systems 552 and/or 556 may be inserted into the interior opening of one or more light guides such that they inject light into the interior edge (interior opening light guide) or the exterior edge (edge illumination light guide) of one or more light guides. The LEDs in LED illumination systems 552 and/or 556 may be arranged around the circumference of a base that is part of a light guide. According to one embodiment, the base may be thermally conductive. According to one embodiment, the base may be coupled to a heat dissipating element disposed over the light guide. The heat dissipating element may be arranged to receive heat generated by the LED via the thermally conductive base and dissipate the received heat. One or more light guides may allow the light emitted by the LED illumination systems 552 and 556 to be shaped in a desired manner, such as, for example, having a gradient, a chamfer distribution, a narrow distribution, a broad distribution, an angular distribution, or the like.

In an example embodiment, the system 550 may be a mobile phone of a camera flash system, an indoor residential or commercial lighting, an outdoor light such as street lighting, an automobile, a medical device, an AR/VR device, and a robotic device. The integrated LED lighting system 400A shown in fig. 3A, the integrated LED lighting system 400B shown in fig. 3B, the LED lighting system 400C shown in fig. 3C, and the LED lighting system 400D shown in fig. 3D illustrate LED lighting systems 552 and 556 in example embodiments.

The application platform 560 may provide power to the LED lighting systems 552 and/or 556 via a power bus via line 565 or other suitable input, as discussed herein. Further, the application platform 560 may provide input signals for operation of the LED lighting system 552 and the LED lighting system 556 via line 565, which may be based on user inputs/preferences, sensed readings, preprogrammed or autonomously determined outputs, and the like. The one or more sensors may be internal or external to the housing of the application platform 560.

In various embodiments, the application platform 560 sensors and/or the LED lighting systems 552 and/or 556 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, etc., or a combination thereof. The data may be related to a physical item or entity, such as an object, person, vehicle, etc. For example, the sensing equipment may collect object proximity data for ADAS/AV-based applications, which may prioritize detection and subsequent actions based on detection of physical items or entities. The data may be collected based on the emission of optical signals (such as IR signals) by, for example, LED illumination systems 552 and/or 556 and the collection of data based on the emitted optical signals. The data may be collected by a component that is different from the component that emits the optical signal used for data collection. Continuing with this example, the sensing equipment may be located on an automobile and a Vertical Cavity Surface Emitting Laser (VCSEL) may be used to emit a beam. One or more sensors may sense a response to the emitted light beam or any other suitable input.

In an example embodiment, the application platform 560 may represent an automobile and the LED lighting system 552 and the LED lighting system 556 may represent automotive headlamps. In various embodiments, system 550 may represent an automobile having a steerable light beam, wherein LEDs may be selectively activated to provide the steerable light. For example, an array of LEDs may be used to define or project a shape or pattern, or to illuminate only selected portions of a roadway. In an example embodiment, the infrared camera or detector pixels within the LED illumination systems 552 and/or 556 may be sensors that identify portions of the scene requiring illumination (roads, crosswalks, etc.).

Fig. 5A is an illustration of an LED device 200 in an example embodiment. LED device 200 may include a substrate 202, an active layer 204, a wavelength conversion layer 206, and primary optics 208. In other embodiments, the LED device may not include a wavelength converter layer and/or primary optics. The individual LED devices 200 may be included in an LED array in an LED lighting system, such as any of the LED lighting systems described above.

As shown in fig. 5A, the active layer 204 may be adjacent to the substrate 202 and emit light when excited. Suitable materials for forming the substrate 202 and the active layer 204 include sapphire, siC, gaN, silicone, and may more particularly be formed from: group III-V semiconductors, including but not limited to AlN, alP, alAs, alSb, gaN, gaP, gaAs, gaSb, inN, inP, inAs, inSb; group II-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.

Wavelength-converting layer 206 may be remote, adjacent, or directly over active layer 204. The active layer 204 emits light into the wavelength converting layer 206. The wavelength conversion layer 206 is used to further modify the wavelength of light emitted by the active layer 204. LED devices that include a wavelength-converting layer are commonly referred to as phosphor-converted LEDs ("PCLEDs"). The wavelength converting layer 206 may comprise any luminescent material such as, for example, transparent or translucent binder or phosphor particles in a matrix, or ceramic phosphor elements that absorb light of one wavelength and emit light of a different wavelength.

The primary optic 208 may be on one or more layers of the LED device 200 or over one or more layers of the LED device 200 and allow light to pass from the active layer 204 and/or the wavelength conversion layer 206 through the primary optic 208. The primary optic 208 may be a lens or package configured to protect one or more layers and at least partially shape the output of the LED device 200. The primary optic 208 may comprise a transparent and/or translucent material. In an example embodiment, light via the primary optic may be emitted based on a lambertian distribution pattern. It will be appreciated that one or more properties of the primary optic 208 may be modified to produce a light distribution pattern other than a lambertian distribution pattern.

Fig. 5B shows a cross-sectional view of an illumination system 220 in an example embodiment, the illumination system 220 including an LED array 210 having pixels 201A, 201B, and 201C, and secondary optics 212.LED array 210 includes pixels 201A, 201B, and 201C, each of which includes a respective wavelength conversion layer 206B, active layer 204B, and substrate 202B. The LED array 210 may be a monolithic LED array fabricated using wafer-level processing techniques, micro LEDs having sub-500 micron dimensions, or the like. Pixels 201A, 201B, and 201C in LED array 210 may be formed using array segmentation or alternatively using pick and place techniques.

The space 203 shown between one or more pixels 201A, 201B, and 201C of the LED device 200B may include an air gap or may be filled with a material (such as a metallic material) that may be a contact (e.g., an n-contact).

Secondary optics 212 may include one or both of lens 209 and waveguide 207. It will be appreciated that although secondary optics are discussed in terms of the illustrated example, in example embodiments secondary optics 212 may be used to spread the incoming light (diverging optics) or to concentrate the incoming light into a collimated beam (collimating optics). In an example embodiment, the waveguide 207 may be a concentrator and may have any suitable shape, such as parabolic, conical, beveled, etc., to concentrate light. The waveguide 207 may be coated with a dielectric material, a metallization layer, etc. for reflecting or redirecting incident light. In alternative embodiments, the lighting system may not include one or more of the following: conversion layer 206B, primary optics 208B, waveguide 207, and lens 209.

The lens 209 may be formed of any suitable transparent material such as, but not limited to, siC, alumina, diamond, and the like, or combinations thereof. The lens 209 may be used to modify the light beam input into the lens 209 such that the output light beam from the lens 209 will effectively meet the desired photometric specification. Additionally, the lens 209 may serve one or more aesthetic purposes, such as by determining the illuminated and/or non-illuminated appearance of the LED devices 201A, 201B, and/or 201C of the LED array 210.

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 intended that the scope of the invention not be limited to the specific embodiments illustrated and described.

Claims

1. A Light Emitting Diode (LED) color adjustment device, comprising:

a hybrid drive circuit coupled to a multi-color LED array, the hybrid drive circuit comprising:

an analog current distribution circuit for generating currents for at least two LED current driving sources; and

a switch array coupled between the analog current distribution circuit and the multicolor LED array, the switch array configured to: periodically supplying current from one of the at least two LED current drive sources to one color of the multi-color LED array and simultaneously supplying current from the other of the at least two LED current drive sources to the other color of the multi-color LED array for a predetermined amount of time to provide color adjustment of the multi-color LED array.

2. The LED color adjustment apparatus of claim 1, further comprising:

a voltage regulator coupled to the multicolor LED array; and

An LED driver electrically coupled to the voltage regulator,

wherein the voltage regulator provides a voltage signal to the multi-color LED array, the combination of the LED driver and the voltage regulator providing a stable current as an input to the analog current distribution circuit.

3. The LED color adjustment apparatus of claim 1, wherein the switch array comprises a multiplexer array.

4. The LED color adjustment apparatus of claim 1, further comprising a voltage controlled current source configured to supply current to the analog current distribution circuit to generate current for the at least two LED current drive sources.

5. The LED color adjustment apparatus of claim 1, wherein the switch array is configured to:

during a first portion of the time period, providing a first current from a first one of the at least two LED current drive sources to a first one of the three colors of the multi-color LED array and simultaneously providing a second current from a second one of the at least two LED current drive sources to a second one of the three colors of the multi-color LED array,

during a second portion of the time period, providing the first current to a second of the three colors in the multi-color LED array and simultaneously providing the second current to a third of the three colors in the multi-color LED array, and

During a third portion of the time period, the first current is provided to a first one of the three colors in the multi-color LED array and the second current is simultaneously provided to a third one of the three colors in the multi-color LED array.

6. The LED color adjustment apparatus of claim 5, wherein the first, second, and third portions of the time period are selectable using Pulse Width Modulation (PWM) time slices.

7. The LED color adjustment apparatus of claim 5, wherein a sum of the first current and the second current is equal to an input current supplied from an LED driver to the analog current distribution circuit.

8. The LED color adjustment apparatus of claim 5, wherein each of the at least two LED current drive sources is configured to supply equal amounts of current to the multicolor LED array.

9. The LED color adjustment apparatus of claim 5, wherein each of the at least two LED current drive sources is configured to supply unequal amounts of current to the multicolor LED array.

10. The LED color adjustment apparatus of claim 1, wherein the multi-color LED array comprises at least one red LED, at least one green LED, and at least one blue LED.

11. The LED color adjustment apparatus of claim 1, wherein the multicolor LED array comprises at least one desaturated red LED, at least one desaturated green LED, and at least one desaturated blue LED.

12. The LED color adjustment apparatus of claim 1, wherein the switch array comprises at least four switching devices.

13. The LED color adjustment apparatus of claim 1, wherein the hybrid drive circuit is further configured to supply a Pulse Width Modulation (PWM) time slice signal to a selected one of the multi-color LED arrays.

14. The LED color adjustment apparatus of claim 4, further comprising a computing device configured to compare the first sensed voltage V _SENSE1 And a second sense voltage V _SENSE2 To determine and supply the set voltage V _SET The set voltage is an input voltage of the voltage controlled current source.

15. A method for adjusting a multi-color Light Emitting Diode (LED) array, the method comprising:

determining and supplying a set voltage as an input voltage of the voltage-controlled current source;

dividing an input current into a first current and a second current; and

based on the color temperature, color adjustment of the multicolor LED array is provided by:

During a first portion of the time period, providing the first current to a first one of the three colors in the multi-color LED array, and simultaneously providing the second current to a second one of the three colors in the multi-color LED array,

16. The method for adjusting a multi-color LED array of claim 15, wherein providing the first current and providing the second current to different color pairs in the multi-color LED array during different portions of the time period occurs using Pulse Width Modulation (PWM) time slicing.