CN113711694A

CN113711694A - Hybrid driving scheme for RGB color adjustment

Info

Publication number: CN113711694A
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: 2021-11-26
Anticipated expiration: 2040-01-23
Also published as: JP7089123B2; TW202036532A; KR20210112391A; EP3915335A1; JP2022510040A; WO2020154547A1; KR102434290B1; CN113711694B

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 supply a first current to a first one of the three color LEDs and simultaneously supply a second current to a second one of the three color LEDs during a first portion of a cycle, to supply the first current to the second one of the three color LEDs and simultaneously supply the second current to a third one of the three color LEDs during a second portion of the cycle, and to supply the first current to the first one of the three color LEDs and simultaneously supply the second current to the third one of the three color LEDs during a third portion of the cycle.

Description

Hybrid driving scheme for RGB color adjustment

Priority requirement

This application claims the benefit of priority from U.S. patent application serial No. 16/543230 filed on

day

8, 16, 2019, which claims the benefit of priority from U.S. patent application serial No. 16/258193 filed on

day

1, 25, 2019, and claims the benefit of european patent application serial No. 19165527.3 filed on

day

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 can 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 band gap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of wavelength converting material on the semiconductor device.

An LED circuit, also referred to as an LED driver, is a circuit for powering an LED by providing a suitable current. The circuit must provide enough current to light the LED at the required brightness, but must limit the current to prevent damage to the LED. A balance between supplying sufficient current to power the LED and limiting the current to prevent damage is required because the voltage drop across the LED is approximately constant over a wide operating current interval. This results in a small increase in applied voltage which greatly increases current.

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

Disclosure of Invention

Drawings

A more detailed understanding can be obtained from the following description, given by way of example, in conjunction 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 less PCB resources than analog circuitry;

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

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

FIG. 1G illustrates a color diagram of the circuit of FIG. 1C with a blue LED (or array of blue LEDs) 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 analog currents;

FIG. 1J illustrates a color diagram of the circuit of FIG. 1H in which the red and green LEDs (or red LED array and green LED array) are driven by analog currents;

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

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 electronics board with an array of LEDs 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 illumination 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 with an array of LEDs on an electronic board separate from the driver and control circuitry;

fig. 3D is a block diagram of an LED lighting system with an array of LEDs 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 system and/or light emitting diode ("LED") embodiments are described more fully below 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 further embodiments. Thus, 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. 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" can 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" onto 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" to 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 intermediate 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 elements 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 the LEDs, LED arrays, electrical components, and/or electronic components are 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 lights and camera flashes) for handheld battery-powered devices, such as cameras and cell phones. For example, they may also be used for automotive lighting, head-up display (HUD) lighting, horticulture lighting, street lighting, video lighting, general lighting (e.g., home, shop, office and studio lighting, theater/stage lighting, and architectural lighting), Augmented Reality (AR) lighting, Virtual Reality (VR) lighting, display backlighting, and IR spectroscopy. A single LED may provide less bright light than an incandescent light source, and thus, a multi-junction device or an LED array (such as a monolithic LED array, a micro LED array, etc.) may be used in applications where higher brightness is desired or required.

The present description 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, and in particular to address color mixing using phosphor converted color LEDs. The forward voltage of a direct color LED decreases as the dominant wavelength increases. The LEDs are preferably driven by a multi-channel DC/DC converter. New phosphor converted color LEDs have been created targeting high efficacy (efficacy) and CRI, providing new possibilities for Correlated Color Temperature (CCT) tuning applications. The new color LEDs have desaturated (soft) color points and can be mixed to achieve a white color with 90+ CRI over a wide CCT interval. Other LEDs may have an 80 CRI implementation, or even a 70 CRI implementation may be used. These possibilities require LED circuits to realize and maximize this potential. Meanwhile, the control circuit can be compatible with a single-channel constant-current driver, so that the control circuit is convenient to adopt in the market.

Generally, 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 currently there is no way to change the current three way approach. Analog driving often results in certain color LEDs 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 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 another color to add to the mixed color. Since human vision is not able to perceive very rapidly changing colors, light appears to have one 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 an RGB LED and a particular output is desired, based on the perception of the human eye, red may be driven during one part of the cycle, green may be driven during a different part of the cycle, and blue may be driven during another part of the cycle. 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 disadvantages of PWM, where LED under-utilization results in inefficiency.

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

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

	Simulation of	PWM
			Utilization ratio of LED	+	-
Color point predictability	Some colors may require only a few mA	+ all LEDs conduct peak current
			Rated current	+ all colors share the peak current	All LEDs conduct peak currents
Controller complexity	-complexity of	+ simple
			Controller efficiency	-	+
Efficacy of LED	+	-
			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 divides the input current between the two colors at a time, while treating the set of two colors as virtual LEDs to overlap the PWM time slices. This driving scheme achieves the same level of overall efficacy as an analog drive using the same number of LEDs, while maintaining good color predictability. Compared to a hybrid driving scheme, a 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. The hybrid drive gains the advantages of an analog driver in the utilization, current rating, LED efficacy and overall efficacy of the LEDs, and the advantages of using an included PWM driver in color point predictability and controller complexity.

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

	Simulation of	PWM	Mixing
				Utilization ratio of LED	+	-	+
Color point predictability	Some colors may require only a few mA	+ all LEDs conduct peak current	+
				Rated current	+ all colors share the peak current	All LEDs conduct peak currents	+
Controller complexity	-complexity of	+ simple	+
				Controller efficiency	-	+	-
Efficacy of LED	+	-	+
				Overall efficacy	+	-	+
And dimming using PWM Driver compatibility of	Whether or not	Is that	Is dependent on PWM frequency

Fig. 1A illustrates a CIE chromaticity diagram 1 representing a color space. The color space is a three-dimensional space; that is, a color is specified by a set of three numbers that specify the color and intensity 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 lightness. The eye's response is best described by these three "tristimulus values" based on the fact that the human eye has three different types of color sensitive cones.

The 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 a chromaticity space specified by two chromaticity coordinates x, y. Chroma is an objective specification of color quality, independent of its lightness. Chroma consists of two separate parameters, often designated hue and color. Color may alternatively be referred to as saturation, chromaticity, intensity, or excitation purity. The chromaticity diagram 1 includes colors perceivable by the human eye. The colorimetric illustration 1 uses parameters based on the Spectral Power Distribution (SPD) of the light emitted from colored objects and is factorized in the sensitivity curve that has been measured for the human eye. Any color can be accurately expressed in two color coordinates x and y. By combining a given set of three primary colors, i.e. blue, green and red, the colors that can be matched are represented on the chromaticity diagram by a triangle 2, which triangle 2 connects the coordinates of the three colors, i.e. the red coordinate 3, the green coordinate 4 and the blue coordinate 5. Triangle 2 represents the color gamut.

The 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 black body will take in a particular chromaticity space as the temperature of the black body changes. It goes from deep red to orange, yellow-white, white at low temperatures and finally blue-white at very high temperatures. In general, the human eye prefers a white point that is not too far from the BBL 6. The color dots above the BBL 6 will look too green, while the color dots below will look too pink.

FIG. 1B illustrates a diagram 10, which diagram 10 illustrates different CCTs and their relationship to the BBL 6. Using the three primary colors (R, G, B), and driving two colors simultaneously, three virtual color points (R-G, R-B, G-B) are created, which creates the color gamut 2.1 of the present driving scheme. The new color gamut 2.1 is smaller than the old color gamut 2. Between 2700K and 4000K, the color line runs within 3 steps below BBL 6. For warm color CCT, this deviation is within the human viewing preference for slightly below BBL 6. As will be appreciated by those skilled in the art, the primary color points may be adjusted such that the color gamut 2.1 completely surrounds the tunable band of interest. By forcing the current to be divided between the two colors, efficiency and utilization are improved.

Fig. 1C illustrates an example circuit 20 of a hybrid drive circuit for RGB adjustment. Circuit 20 includes an LED driver 25 electrically connected to a voltage regulator 24, both of which together produce a steady current I₀And 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, 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 is understood, assigning colors to particular channels is merely a design choice, and although other designs may be contemplated, the present description uses color 1 LEDs 26, color 2 LEDs 27, and color 3 LEDs 28, and may also describe embodiments in which color 1 is described as green, color 2 is described as red, and color 3 is described as blue, in order to provide a complete understanding of the hybrid drive circuit described herein.

The circuit 20 comprises an analog current distribution circuit 21 to distribute the incoming current I₀Divided into two currents I₁、I₂. Such an analog current distribution circuit 21 is described in U.S. patent application No. 16/145053 entitled "arbitrary ratio analog current distribution circuit," which is incorporated by reference herein as if set forth in its entirety herein. 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 account for any mismatch in forward voltage between LEDs of different colors while allowing precise 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 both 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 driving circuit described herein, the analog current distribution circuit 21 is provided as an exemplary distributor.

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 for applications utilizing two or more LED arrays 23.

Each current channel of 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 of the second current path 32 at Vsense 2. The voltage at Vsense1 represents the current through the first sense resistor (Rs 1) 29, and the voltage at Vsense2 represents the current 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 a 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 to the second sense voltage Vsense2 by subtracting the first sense voltage Vsense1 from the second sense voltage Vsense 2. When the op amp 38 is in regulation, the computing device 37 may be configured to convert the difference of the first sense voltage Vsense1 and the second sense voltage Vsense2 into a charging current to charge the capacitor 39 to increase the set voltage Vset when the first sense voltage Vsense1 is less than the second sense voltage Vsense 2. The computing device 37 may be configured to convert the difference of the first sense voltage Vsense1 and the second sense voltage Vsense2 into the discharge resistor 41 to lower the set voltage Vset when the first sense voltage Vsense1 is greater than the second sense voltage Vsense 2.

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 supplying power to the first current path 31. Stated another way, when the op amp 38 is in regulation, the first sense voltage Vsense1 is approximately equal to the second sense voltage Vsense 2. Thus, during steady state, the ratio of the current of the first current path 31 to the current of the second current path 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 satisfies the following equation:

i _ Rs1= V _ set/R _ s 1; in the case of equation 1,

i _ Rs2= 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 splitting circuit 20 splits the current into two equal portions assuming negligible current drawn by the auxiliary circuitry (such as the supply voltage generation). 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 Vgate 1. The first gate voltage Vgate1 may be input to a current source for providing a driving current I₁The first transistor 34. 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 driving current I₂. 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. The second gate voltage Vgate2 may 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, the shunt regulator 36 has an internal reference voltage of 2.5V. The shunt regulator 36 may absorb large currents when the voltage applied at the REF node is above 2.5V. When the voltage applied at the REF node is below 2.5V, the shunt regulator 36 may sink very little quiescent current.

The large sinking 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. The shunt regulator 36 may not be able to pull the cathode to a voltage greater than the forward voltage (Vf) of 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 the analog current distribution circuit 21₁、I₂. 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. The multiplexer array 22 switches I each time₁And I₂Two colors are introduced into the LED array 23. The following table indicates that the MOSFET S111 and MOSFET S414 need to be controlled because the MOSFET S212 and MOSFET S313 are inverted values of the MOSFET S111 and MOSFET S414 (i.e., S2= inverted S1 and S3 = inverted S4). As defined in the following equation,

R _{s 1} * I ₁ = R _{s 2} * I ₂the results of, in equation 3,

I ₀= I ₁+ I ₂ equation 4.

In operation, the hybrid driving scheme simultaneously drives two colors in the LED array 23 with the analog current distribution circuit 21, 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 an embodiment 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

Colour(s)	S1（RA0）	S2（= INV S1）	S3（= INV S4）	S4（RA1）
					R-G	Opening device	Closing device	Opening device	Closing device
G-B	Opening device	Closing device	Closing device	Opening device
					R-B	Closing device	Opening device	Closing device	Opening device
R	Closing device	Opening device	Opening device	Closing device

When two colors are driven simultaneously, a virtual color point is created. Current I₁And I₂The ratio between can be predefined (i.e., 1:1 or slightly different to maximize efficiency, although any ratio can be used). Using the 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 new driving directionThe color gamut of the scheme.

Table 4 summarizes the timing of the operation of the hybrid driving scheme for 3-channel LED driving. As will be appreciated by one of ordinary skill in the relevant art, the particular order of the colors is not necessarily important. In an implementation of the hybrid driving scheme, the color pairs may be arranged or rearranged in a manner that minimizes the complexity of the PWM logic implementation. Table 4 is shown below to provide a sample timing. During sub-interval T1, the red-green color pair may be powered. During sub-interval T2, the green-blue color pair may be powered. During sub-interval 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: time sequence

Fig. 1D illustrates a microcontroller 40 that may be used in the computing device 37 to handle complex signal processing with less PCB resources than the analog circuitry described above. The microcontroller 40 handles the input signal and the operations 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 plate temperature with NTC 17. The two readings of 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 a first output signal 11 to control the switch S1 and a second output signal 14 to control the switch S4.

Fig. 1E illustrates a color map 42 of the circuit 20 with the red LED (or array of red LEDs) in a central position. The color map 42 is superimposed on the color map of fig. 1B. Color map 42 depicts the use of RB-RG-BG in circuit 20 for gamut 43 that is reachable from 2700K to 6000K (matching gamut 2.1 from fig. 1B), and RG-RB-R in circuit 20 for gamut 44 that is 2500K and below. The color gamut 43 can be provided with high efficiency. 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 all 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 circuit 20 with a green LED (or array of green LEDs) in a central location. The color map 45 is superimposed on the color map of fig. 1B. Color diagram 45 depicts the use of RB-RG-BG in circuit 20 for reachable color gamut 43 from 2700K to 6000K (matching color gamut 2.1 from fig. 1B), and RG-GB-G in circuit 20 for color gamut 46 above BBL 6. The color gamut 43 can be provided with high efficiency. 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 all 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 array of blue LEDs) in a central position. The color map 47 is superimposed on the color map of fig. 1B. Color map 47 depicts the use of RB-RG-BG in circuit 20 for reachable color gamut 43 of 2700K to 6000K (matching color gamut 2.1 from FIG. 1B), and GB-RB-B in circuit 20 for color gamut 48 beyond 6500K. The color gamut 43 can be provided with high efficiency. 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 all 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 all parts of the color gamut 2 can be reached by simply varying the LEDs located in the center of the circuit 20. In each LED configuration, the color gamut 2.1 is covered, plus an additional portion of the color gamut 2. This coverage may be sufficient for many applications and may be a compromise for increased efficiency.

Fig. 1H illustrates another hybrid driving circuit 50. Circuit 50 may provide an increased color gamut from circuit 20. The circuit 50 includes an analog current distribution circuit 21, an LED array 23, a voltage regulator 24, and an 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 adjusted 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 is understood, assigning colors to particular channels is merely a design choice, and although other designs may be contemplated, the present description uses color 1 LEDs 26, color 2 LEDs 27, and color 3 LEDs 28, and may also describe embodiments in which color 1 is described as green, color 2 is described as red, and color 3 is described as blue, in order to provide a complete understanding of the hybrid drive circuit described herein.

A multiplexer array 52 electrically connecting two of the three

LEDs

26, 27, 28 to the two current sources I created by the analog current distribution circuit 21₁、I₂. 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. The multiplexer array 52 will I each time₁And I₂Two colors are introduced into the LED array 23. It is necessary to control the MOSFETs S151, S456 and X because the MOSFETs S253 and S354 are the inverse values of the MOSFETs S151 and S456, and the MOSFET S557 is the inverse combination of the MOSFETs S151 and S253. In particular, the amount of the solvent to be used,

S2 =

the results of, in equation 5,

S3 =

the results of, in equation 6,

S5 =

equation 7.

Table 5 illustrates possible combinations provided by circuit 50. The utilization of the LEDs in array 23 in an embodiment 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 I₁	Color I₂	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 diagram 55 of the circuit 50, where the red and blue LEDs (or red LED array and blue LED array) are driven by analog currents. The color map 55 is superimposed on the color map 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 with high efficiency. 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 color gamuts 43, 44, 48 does not fully cover all of color gamut 2, the combination of color 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 diagram 60 of the circuit 50 in which the red and green LEDs (or red LED array and green LED array) are driven by analog currents. The color map 60 is superimposed on the color map 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 with high efficiency. The color gamuts 44, 46 may be provided with reduced efficiency. The combination of gamuts 43, 44, 46 from circuit 50 approximates the gamut described above with respect to fig. 1A. Although the combination of color gamuts 43, 44, 46 does not fully cover all of color gamut 2, the combination of color 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 diagram 65 of the circuit 50 in which the blue and green LEDs (or the blue LED array and the green LED array) are driven by analog currents. The color map 65 is superimposed on the color map 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 with high efficiency. 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 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 driving circuit 70. The circuit 70 may provide an increased color gamut from the

circuits

20, 50. Circuit 70 includes analog current distribution circuit 21, LED array 23, voltage regulator 24, and 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 adjusted 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 is understood, assigning colors to particular channels is merely a design choice, and although other designs may be contemplated, the present description uses color 1 LEDs 26, color 2 LEDs 27, and color 3 LEDs 28, and may also describe embodiments in which color 1 is described as green, color 2 is described as red, and color 3 is described as blue, in order to provide a complete understanding of the hybrid drive circuit described herein.

A multiplexer array 72 electrically connecting two of the three

LEDs

26, 27, 28 to the two current sources I created by the analog current distribution circuit 21₁、I₂. As illustrated in circuit 70, multiplexer array 72 may include six MOSFETs S1, S2, S3, S4, S5, S6, also referred to as switches. The multiplexer array 72 will I each time₁And I₂Two colors are introduced into the LED array 23. It is desirable to control the MOSFETs S1, S4 and X1, X2 because the MOSFETs S2, S3 and S5 are the inverse values of the MOSFETs S1 and S4, and the MOSFET S6 is the inverse combination of the MOSFETs S4 and S5. In particular, the amount of the solvent to be used,

S2 =

the results of, in equation 8,

S3 =

the results of, in equation 9,

S5 =

the results of, in equation 10,

S6 =

equation 11.

Table 6 illustrates possible combinations provided by circuit 70. The utilization of the LEDs in array 23 in an embodiment 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 I₁	Color I₂	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 following the general scheme I₁And I₂Alternating the same color between them, I₁And I₂Any mismatch between can be averaged out, such as by chopping.

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

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

Fig. 2 is a top view of an electronic board 310 of an integrated LED lighting system according to an embodiment. In alternative embodiments, two or more electronic boards may be used for the LED lighting system. For example, the LED array may be on a separate electronic board, or the sensor module may be on a separate electronic board. 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 may be any board capable of mechanically supporting and providing electrical coupling to electrical components, electronic components, and/or electronic modules using electrically conductive connectors, such as rails, traces, pads, vias, and/or wires. The 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 as needed for the application for 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 horticulture lighting applications may be turned off/on and/or adjusted based on several different sensor inputs, such as 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 the light output, the shape of the light output, the color of the light output, and/or turning the light on or off to conserve energy. For AR/VR applications, a motion sensor 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 a scene to be acquired such that the flash illumination color, intensity illumination pattern, and/or shape may be optimally calibrated. In an alternative embodiment, the electronics 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, the wireless module may include bluetooth, Zigbee, Z-wave, mesh, WiFi, Near Field Communication (NFC), and/or may use a peer-to-peer module. 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 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 elsewhere on or off the electronics 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 individually soldered 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 its LED array 410 attached to a substrate 320 at LED device attachment regions 318, in one embodiment. The electronic board 310 together with the LED array 410 represents the LED lighting system 400A. Additionally, the power module 312 receives a voltage input at Vin 497 and receives control signals from the connection and control module 316 through trace 418B and provides drive signals to the LED array 410 through 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 through 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.

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

The LED array 410 may include two sets of LED devices. In an example embodiment, the LED devices of group a are electrically coupled to first lane 411A, and the LED devices of group B are electrically coupled to second lane 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 in one of the LED groups may be configured to emit light having a different color point than the LEDs in 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 an 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 sub-surface interconnects, such as

traces

431, 432, 433, 434, and 435, or metallization (not shown), for exchanging, for example, voltage, current, and control signals between modules. Connections between modules on opposite surfaces of circuit board 499 may be electrically coupled by 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 an electronic board separate 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 the first electronic board. The LED module 490 may include embedded LED calibration and setting data 493, as well as 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 that may electrically and communicatively couple the two modules. 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 required by the microcontroller to generate or modify control signals instructing the driver to provide power to each set of LEDs a and B using, for example, Pulse Width Modulation (PWM) signals. In this example, the calibration and setting data 493 may inform the microcontroller 472 about, 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 the provided power provided by the AC/DC converter circuit 412 to each channel.

Fig. 3D illustrates a block diagram of an LED lighting system having an array of LEDs and some electronics on an electronic board separate from the driver circuit. The LED system 400D includes a power conversion module 483 and an 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 can include the AC/DC converter circuit 412, the dimmer interface circuit 415, and the DC-DC converter circuit 440, and the LED module 481 can include embedded LED calibration and setting data 493, the LED array 410, the sensor module 414, and the connection and control module 416. The power conversion module 483 can provide the LED driver input signal 485 to the LED array 410 via a wired connection between the 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, the system 400D includes a power module 452 and an LED module 481 that includes embedded LED calibration and setting data 493 and three sets of

LEDs

494A, 494B, and 494C. Although three sets of LEDs are shown in FIG. 3E, one of ordinary skill in the art will recognize that any number of sets 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.

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 the first set of LEDs 494A, a cool white light source via the second set of LEDs 494B, and a neutral white light source via the 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 about 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 about 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. Although 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 composite light outputs 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 as LED1+, LED2+, and LED3+ in fig. 3E). 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, which may have light properties (e.g., Correlated Color Temperature (CCT), color point, or brightness) based on the duration. In operation, the dimmable engine may change the relative amplitudes of the duty cycles of the first, second, and third signals to adjust the respective light properties of each group of LEDs to provide composite light having the desired emission from the LED array 491. As described above, the light output of the LED array 491 can have a color point that is based on a combination (e.g., a mixture) of the 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 lighting system 552 generates a light beam 561 shown between arrows 561a and 561 b. The LED lighting system 556 may produce a beam 562 between arrows 562a and 562 b. In the embodiment shown in fig. 4, light emitted from LED lighting system 552 passes through secondary optic 554, and light emitted from LED lighting system 556 passes through secondary optic 558. In an alternative embodiment,

light 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 interior opening defining an interior edge of the light guide. The LED illumination systems 552 and/or 556 may be inserted into the interior opening of the one or more light guides such that they inject light into the interior edge (interior opening light guide) or the exterior edge (edge-lit light guide) of the one or more light guides. The LEDs in LED lighting systems 552 and/or 556 can 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 an 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. The one or more light guides can allow the light emitted by the LED illumination systems 552 and 556 to be shaped in a desired manner, such as, for example, with a gradient, a chamfered distribution, a narrow distribution, a wide distribution, or an angular distribution, etc.

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

Application platform 560 may provide power to LED lighting systems 552 and/or 556 via line 565 or other suitable input via a power bus, as discussed herein. Further, application platform 560 may provide input signals via line 565 for the operation of LED lighting system 552 and LED lighting system 556, which may be based on user input/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 relate to physical items or entities, such as objects, individuals, vehicles, and the like. For example, sensing equipment may collect object proximity data for ADAS/AV based applications, which may prioritize detection and follow-up actions based on detection of physical items or entities. Data may be collected based on the emission of optical signals (such as IR signals) by, for example, LED lighting systems 552 and/or 556 and the collection of data based on the emitted optical signals. Data may be collected by a component other than 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 may emit a light beam using a Vertical Cavity Surface Emitting Laser (VCSEL). One or more sensors may sense a response to the emitted light beam or any other suitable input.

In an example embodiment, application platform 560 may represent an automobile, and LED lighting system 552 and LED lighting system 556 may represent automobile headlights. In various embodiments, system 550 may represent a car with a directable light beam, where the LEDs may be selectively activated to provide directable 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, infrared camera or detector pixels within LED lighting systems 552 and/or 556 may be sensors that identify portions of a scene (roads, crosswalks, etc.) that require illumination.

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 converting layer 206, and a primary optic 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 be more specifically formed of: 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.

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

Primary optic 208 may be on one or more layers of LED device 200 or over one or more layers of LED device 200 and allow light from active layer 204 and/or wavelength conversion layer 206 to pass through 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 that is different from a lambertian distribution pattern.

Fig. 5B shows a cross-sectional view of the illumination system 220 in an example embodiment, the illumination system 220 comprising an LED array 210 having pixels 201A, 201B, and 201C, and a secondary optic 212. The LED array 210 includes pixels 201A, 201B, and 201C, each pixel including a respective wavelength converting 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. The pixels 201A, 201B, and 201C in the 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, which may be a contact (e.g., an n-contact).

Secondary optic 212 may include one or both of lens 209 and waveguide 207. It will be appreciated that although secondary optics are discussed in accordance with the illustrated example, in an example embodiment, secondary optics 212 may be used to expand incoming light (diverging optics) or to condense incoming light into a collimated beam (collimating optics). In an example embodiment, the waveguide 207 may be a light concentrator and may have any suitable shape, such as a parabolic shape, a conical shape, a beveled shape, and the like, to concentrate light. Waveguide 207 may be coated with a dielectric material, a metallization layer, or the like 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 optic 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, etc., or combinations thereof. The lens 209 may be used to modify the light beam input into the lens 209 so that the output beam from the lens 209 will effectively meet the desired photometric specifications. 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 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 apparatus, comprising:

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

the analog current distribution circuit is used for generating currents for at least two LED current driving sources; and

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

2. The LED color adjustment apparatus of claim 1, further comprising an LED driver electrically coupled to a voltage regulator, the voltage regulator providing a voltage signal for the multi-color LED array, the combination of the LED driver and the voltage regulator providing a steady 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:

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 in the multi-color LED array and substantially 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 in the multi-color LED array during a first portion of a time period,

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

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 provided to a third one of the three colors in the multi-color LED array substantially simultaneously.

6. The LED color adjustment apparatus of claim 5, wherein a Pulse Width Modulation (PWM) time slice is used to select the first, second, and third portions of the time period.

7. The LED color adjustment apparatus of claim 5, wherein a sum of the first current and the second current is substantially 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 a substantially equal amount of current to the multi-color 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 multi-color 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 arrangement of claim 1, wherein the multi-color 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 selected ones of the multi-color LED arrays.

14. A Light Emitting Diode (LED) color adjustment apparatus, comprising:

a multi-color LED array comprising at least one desaturated red LED, at least one desaturated green LED, and at least one desaturated blue LED; and

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

15. The LED color adjustment apparatus of claim 14, 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.

16. The LED color adjustment apparatus of claim 15, further comprising a computing device configured to compare the first sensing voltage V_SENSE1And a second sensing voltage V_SENSE2To determine and supply a set voltage V_SETThe set voltage is an input voltage of the voltage controlled current source.

17. The LED color adjustment apparatus of claim 14, wherein the hybrid drive circuit is further configured to supply a Pulse Width Modulation (PWM) time slice signal to selected ones of the multi-color LED arrays.

18. The LED color adjustment apparatus of claim 14, further comprising an LED driver electrically coupled to a voltage regulator, the voltage regulator providing a voltage signal for the multi-color LED array, the combination of the LED driver and the voltage regulator providing a steady current as an input to the analog current distribution circuit.

19. 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 a voltage controlled current source;

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

determination based on color temperature:

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

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

20. The method for adjusting a multi-color LED array of claim 19, wherein providing the first current and providing the second current to different pairs of the multi-color LED array occurs using Pulse Width Modulation (PWM) time slicing.