Active matrix hybrid micro LED display

Abstract

A driver system controls a plurality of light emitting diodes (LEDs). The driver system includes a first driver that provides an LED current to each of the plurality of LEDs. The first driver includes a current mirror for the LED current provided to the plurality of LEDs. The driver system also includes a second driver that modulates the LED current provided to the plurality of LEDs.

Description

[Technical Field]

[0001] This application claims the benefit of priority to U.S. Patent Application No. 17 / 326,531, filed May 21, 2021, which is incorporated herein by reference in its entirety.

[0002] This application is related to co-pending U.S. patent application Ser. No. 17 / 326,494, entitled "System with Adaptive Light Source and Neuromorphic Vision Sensor," filed May 21, 2021, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] This disclosure relates to supplying current to an array of light emitting diodes (LEDs), and in particular to providing such current through thin film transistors and driving such an array with a digital driver. Summary of the Invention [Problem to be solved by the invention]

[0004] One conventional device includes an LED display and an active matrix backplane that drives the LEDs of the LED display with analog currents.

[0005] Another conventional device includes an LED display and a digitally controlled driver that modulates the LED, for example, by pulse width modulation (PWM). [Means for solving the problem]

[0006] In some embodiments of the present disclosure, both an active matrix backplane for analog current and a driver for digital modulation are used.

[0007] In one embodiment, a driver system for controlling a plurality of light emitting diodes (LEDs) includes a first driver for providing an LED current to each of the plurality of LEDs, the first driver having a current mirror for the LED current provided to the plurality of LEDs, and a second driver for modulating the LED current provided to the plurality of LEDs.

[0008] In another embodiment, a method implemented by a driver system includes providing a light emitting diode (LED) current to each of a plurality of LEDs using a first driver, the first driver having a current mirror for the LED current, and modulating the LED current provided to the plurality of LEDs using a second driver.

[0009] In another embodiment, a light emitting diode (LED) matrix has a plurality of LEDs arranged in rows and columns, a first driver that provides an LED current to each of the plurality of LEDs, the first driver including a current mirror for the LED current provided to the plurality of LEDs, and a second driver that modulates the LED current provided to the plurality of LEDs. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 illustrates a functional system level diagram of one embodiment of the present disclosure. [Figure 2] FIG. 1 illustrates an active display panel including an LED array on a thin film substrate in accordance with one embodiment of the present disclosure. [Figure 3] 1A and 1B are diagrams illustrating a thin film transistor according to an embodiment of the present disclosure. [Figure 4] FIG. 1 is a diagram illustrating a driver system according to an embodiment of the present disclosure. [Figure 5A] FIG. 1 shows a driver system in which an analog IC sets a reference current for a digital driver IC that modulates the current of multiple LEDs. [Figure 5B]FIG. 1 illustrates a driver system in which an analog IC sets the reference current for multiple digital driver ICs that modulate the current for multiple LEDs. [Figure 6] FIG. 1 illustrates a driver system in which a current source is implemented with a mixed-signal IC that modulates the current of multiple LEDs. [Figure 7A] FIG. 1 shows a driver system for different colored LEDs, where an analog current source sets the reference current for each color group of LEDs. [Figure 7B] FIG. 1 shows a driver system for different colored LEDs, where separate analog IC current sources set the reference current for each color group of LEDs. [Figure 8] FIG. 1 illustrates a driver system for different colored LEDs, where a mixed-signal IC sets a reference current for each color group of LEDs and modulates the current for individual LEDs within that group. [Figure 9] FIG. 1 illustrates a driver system including stacked transistors in one embodiment. [Figure 10] 1 illustrates a potential application of an active matrix display having a driver system according to an embodiment of the present disclosure. [Figure 11] FIG. 1 illustrates a system having a neuromorphic vision unit and an adaptive light source array in accordance with an embodiment of the present disclosure. [Figure 12] FIG. 10 is a diagram illustrating an algorithm of an overall flow according to an embodiment of the present disclosure. [Figure 13A] FIG. 1 illustrates an example of a scene illuminated according to an embodiment of the present disclosure. [Figure 13B] FIG. 13B shows an example of a light source intensity profile for the scene shown in FIG. 13A. DETAILED DESCRIPTION OF THE INVENTION

[0011] Light-emitting pixel arrays support applications that benefit from fine intensity, spatial, and temporal control of light distribution. This control can include, but is not limited to, precise spatial patterning of light emitted from pixel blocks or individual pixels. Depending on the application, the emitted light can be spectrally distinct, adaptive over time, and / or environmentally responsive. Light-emitting pixel arrays can provide pre-programmed light distributions in various intensity, spatial, or temporal patterns. The emitted light can be based, at least in part, on received sensor data and can be utilized for optical wireless communication. The associated electronics and optics can be differentiated at the pixel, pixel block, or device level.

[0012] Light-emitting pixel arrays can be formed from one-, two-, or three-dimensional arrays of LEDs, VCSELs, OLEDs, or other controllable light-emitting systems. Light-emitting pixel arrays can be formed as pixel arrays on a monolithic substrate, by partial or complete segmentation of the substrate, formed using photolithography, additive or subtractive processes, or via assembly using pick-and-place or other suitable mechanical placement. Light-emitting pixel arrays can be uniformly laid out in a grid pattern, or can be arranged to define a geometric, curvilinear, random, or irregular layout.

[0013] In some embodiments, the light-emitting pixel array can be an LED pixel array. In some embodiments, the LED pixel array can be a micro LED (μLED) pixel array having hundreds, thousands, or millions of light-emitting diodes (LEDs) arranged together on a substrate with an area on the centimeter scale or smaller. In some implementations, μLEDs can include light-emitting diodes sized between 30 microns and 500 microns. In various embodiments, the light-emitting pixels are spaced less than one millimeter apart, typically at a distance ranging from 30 microns to 500 microns. The pixels can be embedded in a solid or flexible substrate, which can be at least partially transparent. For example, the light-emitting pixel array can be at least partially embedded in a glass, ceramic, or polymer material.

[0014] The controller may be connected to selectively power subgroups of light-emitting pixels in the light-emitting pixel array to provide different light beam patterns. At least some of the light-emitting pixels in the light-emitting pixel array may be individually controlled via connected electrical traces. In other embodiments, groups or subgroups of the light-emitting pixel array may be controlled together. In some implementations, the plurality of light-emitting diodes may have distinct non-white colors. For example, at least four of the plurality of light-emitting diodes may be RGBY groups of light-emitting diodes.

[0015] Light-emitting pixel array luminaires have light-emitting devices that can be programmed to project different lighting patterns based on selective pixel activation and intensity control. Such luminaires can provide multiple controllable beam patterns from a single lighting device without moving parts. Providing such beam patterns is typically achieved by adjusting the brightness of individual LEDs in a 1D or 2D array. Optics, either shared or individual, can direct the light to specific target areas as needed. In some implementations, the height of the light-emitting diodes, their supporting substrate, electrical traces, and associated micro-optics can be less than 5 millimeters.

[0016] Light-emitting pixel arrays, including LED or μLED pixel arrays, can be used to selectively and adaptively illuminate buildings or areas for improved visual display or to reduce lighting costs. Light-emitting pixel arrays can also be used to project media facades for decorative motion or video effects. In combination with tracking sensors and / or cameras, selective illumination of areas around pedestrians is possible. Spectrally distinct pixels can be used to adjust the color temperature of lighting and to support wavelength-specific horticultural lighting.

[0017] Street lighting is one application that can benefit greatly from the use of emissive pixel arrays. A single type of emissive pixel array can simulate various street light types, for example, switching between a Type I linear street light and a Type IV semicircular street light by appropriately activating or deactivating selected pixels. Also, adjusting the light intensity or distribution depending on environmental conditions or time of use can reduce street lighting costs. For example, the light intensity and distribution area can be reduced when there are no pedestrians. If the pixels of the emissive pixel array are spectrally distinct, the color temperature of the light can be adjusted according to the respective daylight, twilight, or nighttime conditions.

[0018] Light-emitting pixel arrays are also suitable for supporting applications including direct or projected displays. For example, warning, emergency, or informational signs can all be displayed or projected using light-emitting pixel arrays. Arrays can be used in this manner to project, for example, color-changing or flashing exit signs. When light-emitting pixel arrays are composed of many pixels, they can present textual or numerical information. Directional arrows or similar indicators can also be provided.

[0019] Vehicle headlamps are an application of light-emitting pixel arrays that include a large pixel count and a high data refresh rate. Automotive headlights that actively illuminate selected sections of the road can be used to mitigate glare or dazzle problems for oncoming drivers. Using an infrared camera as a sensor, the light-emitting pixel array activates those pixels that illuminate the road while deactivating pixels that may dazzle pedestrians or oncoming drivers. Also, off-road pedestrians, animals, or signs can be selectively illuminated to improve the driver's environmental awareness. If the pixels in the light-emitting pixel array are spectrally distinguishable, the color temperature of the light can be adjusted according to the respective daylight, twilight, or nighttime conditions. Some pixels can be used for optical wireless vehicle-to-vehicle communication.

[0020] Some of the drawings described throughout this disclosure are shown with the whole drawing separated among multiple drawings to meet drawing requirements.

[0021] A functional system level diagram of one embodiment of the present disclosure is shown in Figure 1. As shown in Figure 1, an electronic device has a driver system 100, which includes a current source 110, a transistor 120, an array of LEDs 130, and a digital driver 140.

[0022] The current source 110 is connected to a high rail, such as a power signal. The current source 110 is an analog current source and sets a reference current for one or more LEDs in the array 130. The current source 110 may be implemented, for example, by discrete components, an analog integrated circuit (IC), or a mixed-signal IC. In some embodiments, the current source 110 is programmable. The output of the current source 110 may be connected to a low rail, such as a ground ring.

[0023] Transistor 120 is connected to the high rail and may be contained in a transistor backplane. Transistor 120 generates a current based on a reference current set by current source 110. In one embodiment, transistor 120 is part of a current mirror, where the reference current set by current source 110 is mirrored. Transistor 120 uses the mirrored current to drive the LEDs in array 130.

[0024] Thus, transistor 120 can be considered to provide an analog drive for the LEDs of array 130 .

[0025] In one embodiment, the transistor backplane is a thin-film backplane and the transistors 120 are thin-film transistors. The thin-film backplane also connects the driver ICs.

[0026] The driver 140 is connected between the array 130 and the row rail. The driver 140 modulates the current received by the array 130. In one embodiment, the driver 140 provides pulse width modulation (PWM). Because of the binary operation of this modulation, the driver 140 can be considered to digitally drive the LEDs of the array 130. In one embodiment, the driver 140 is a micro-driver.

[0027] Therefore, between the analog drive of current source 110 and the digital drive of driver 140, driver unit 100 can be thought of as providing a hybrid drive for the LEDs of array 130. Thus, analog currents for multiple pixels can be easily set.

[0028] 2 illustrates an active display panel including an LED array on a thin-film substrate in one embodiment of the present disclosure. The display panel 200 generally includes a thin-film transistor (TFT) substrate 202 that supports a pixel region 204 and a non-pixel region outside the pixel region 204. The TFT substrate 202 is also referred to as a backplane or transistor backplane. As shown, the pixel region 204 includes pixels, such as pixel 220, arranged in a matrix. In other implementations, the pixel region 204 is arranged in a vector or matrix of different sizes.

[0029] The pixel 220 may include multiple sub-pixels, each emitting a different color of light, and may include a current source 110 and a transistor 120.

[0030] The subpixels can be formed from micro LED devices. In one such embodiment, the micro LED device of the first subpixel is a diode that emits red light, the micro LED device of the second subpixel is a diode that emits green light, and the micro LED device of the third subpixel is a diode that emits blue light. Each micro LED device can be a thin film transistor.

[0031] Thus, pixel 220 can be considered to emit, for example, white light. Other embodiments will readily suggest themselves to those skilled in the art. The sub-pixels can be arranged in rows, columns, or matrices.

[0032] Also, pixel 220 may have a TFT that implements current source 110, transistor 120, and driver 140. Pixel 220 may include three current controllers, one for each subpixel of a different color, and pixel 220 may include any number of digital controllers, depending on the number of inputs.

[0033] The pixel area 204 may also include capacitors for driving and switching the pixels.

[0034] The non-pixel area includes a data driver circuit 210, a scan driver circuit 212, a power supply line, and a ground ring. The data driver circuit 210 is connected to the data line of each pixel, allowing a data signal (e.g., Vdata) to be sent to the pixel.

[0035] The scan driver circuit 212 connects to the scan (or enable) lines of the pixels and sends scan signals (e.g., Vscan) to the pixels. The power lines send power signals (e.g., Vdd) to the transistors. The ground ring provides a ground signal (e.g., Vss) to the array of pixels.

[0036] The display panel 200 also includes a flexible circuit board 213. The flexible circuit board 213 is connected to the data driver circuit 210, the scan driver circuit 212, the power supply line, and the ground ring. The flexible circuit board 213 includes a power supply that supplies a power signal to the power supply line, and a power ground line that is electrically connected to the ground ring.

[0037] FIG. 3 shows a thin film transistor 300 according to one embodiment of the present disclosure.

[0038] During fabrication, the gate 380 of the thin film transistor 300 is deposited on glass 370. A silicon nitride (SiNx) layer 360 is then deposited on top of the gate 380. A hydrogenated amorphous silicon layer 320 is then deposited on top of the silicon nitride layer 360. A chlorine-doped amorphous silicon layer 310 is then deposited on top of the hydrogenated amorphous silicon layer 320. The hydrogenated amorphous silicon layer is then deposited and doped to form an N+ hydrogenated amorphous silicon layer 330.

[0039] The hydrogenated amorphous silicon layer 320, the chlorine-doped amorphous silicon layer 310, and portions of the N+ hydrogenated amorphous silicon layer 330 are removed. Next, the source 340 and the drain 350 are deposited in contact with the silicon nitride layer 360.

[0040] In the example of FIG. 3, an amorphous silicon bottom-gate thin-film transistor is formed. Alternatively, other thin-film transistors can be used for transistor 120. For example, transistor 120 may be or include an indium gallium zinc oxide (IGZO) thin-film transistor. Thus, hydrogenated amorphous silicon layer 320 may instead be an amorphous IGZO material. These IGZO transistors may be dual-gate and have improved mobility. Transistor 120 may also be or include a low-temperature polycrystalline silicon (LIPS) transistor. Thus, hydrogenated amorphous silicon layer 320 may instead be an LTPS material.

[0041] 4 shows a driver system 400 according to an embodiment of the present disclosure. The driver system 400 includes a mirror transistor 410, a current source 420, a driving transistor 430, and an LED 440. The driving unit 400 also includes a backplane (not shown).

[0042] As shown in Figure 4, mirror transistor 410 is a PMOS transistor including a first terminal connected to a power signal, such as Vdd. The gate of mirror transistor 410 is connected to the second terminal of mirror transistor 410. In the embodiment of Figure 4, the first terminal of mirror transistor 410 is the source and the second terminal of mirror transistor 410 is the drain. Thus, mirror transistor 410 is a diode-connected transistor. Mirror transistor 410 may also be a thin-film transistor mounted on a transistor backplane.

[0043] The mirror transistor 410 is not limited to such an embodiment. For example, the mirror transistor 410 can be implemented as an NMOS transistor. Other modifications will be familiar to those skilled in the art.

[0044] Current source 420 sets a reference current that flows through mirror transistor 410. In many embodiments, current source 420 is a variable current source. In some embodiments, current source 420 can be a fixed current source. In the embodiment of FIG. 4, current source 420 is a separate component, such as a resistor, diode, or another transistor. Mirror transistor 410 and current source 420 are embodiments of current source 110.

[0045] The gate of the drive transistor 430 is connected to the gate of the mirror transistor 410. The first terminal of the drive transistor 430 is connected to the power signal Vdd. The second terminal of the drive transistor 430 is connected to the input of the LED 440. In the embodiment shown in Figure 4, the drive transistor 430 is a PMOS transistor. Thus, the first terminal of the drive transistor 430 is the source, and the second terminal of the drive transistor 430 is the drain.

[0046] Thus, drive transistor 430 forms a current mirror with mirror transistor 410. Thus, the reference current set by current source 420 also flows through drive transistor 430.

[0047] The drive transistor 430 can be one of the transistors 120. The drive transistor 430 is, for example, a thin film transistor implemented on a backplane.

[0048] The driving unit 400 may include multiple driving transistors 430 arranged similarly to the driving transistor 430. Therefore, the driving transistors 430 are generally of the same type, for example, PMOS. The same first terminals (for example, sources) of the driving transistors 430 are connected to a power signal. Similarly, the same second terminals (for example, drains) of the driving transistors 430 are connected to an LED 440. The gates of the driving transistors 430 are connected to each other.

[0049] The LED 440 includes a first terminal connected to the second terminal of the drive transistor 430. Thus, the LED 440 receives a reference current that is driven by the drive transistor 430. Upon receiving an electrical signal, the LED 440 emits light. The second terminal of the LED 440 can be connected to a low rail, such as a ground ring.

[0050] Thus, the LED 440 may be implemented within the array 130 or may be one of the sub-pixels of the pixel 220 .

[0051] FIG. 5A shows a driver system 500A. An analog IC 520 sets a reference current for a digital driver IC 550, which modulates the current of multiple LEDs 540. The driver system 500A includes a mirror transistor 510, an analog IC 520, a drive transistor 530, LEDs 540, and a digital driver IC 550. The mirror transistor 510, the drive transistor 530, and the LEDs 540 are structurally similar to the mirror transistor 410, the drive transistor 430, and the LEDs 440. Therefore, further description of the mirror transistor 510, the drive transistor 530, and the LEDs 540 will be omitted.

[0052] 4, the driving system 500A does not necessarily include a separate component as the current source 420. Thus, the driver system 500A has an analog IC 520 and a digital driver IC 550.

[0053] The second terminal of mirror transistor 510 is connected to a pin or other input of analog IC 520. Similar to current source 420, analog IC 520 sets the current to flow through mirror transistor 510. In many embodiments, analog IC 520 includes a variable current source. In some embodiments, analog IC 520 can be a fixed current source. Drive transistor 530 forms a current mirror with mirror transistor 510, so that the reference current set by analog IC 520 flows through drive transistor 530 to LED 540.

[0054] A pin or other output of the analog IC 520 is connected to a low rail such as a ground ring.

[0055] A second terminal of the LED 540 is connected to a pin or other input of the digital driver IC 550 .

[0056] The digital driver IC 550 includes a modulator that modulates a signal (e.g., a current) through the LED 540. For example, the modulator of the digital driver IC 550 may perform pulse width modulation (PWM) on the signal. Thus, the digital driver IC 550 may include or otherwise implement a pulse width modulator. In one embodiment, the modulator is implemented using a switch.

[0057] The signal from each of the LEDs 540 passes through a respective pulse width modulator of the digital driver IC 550. When the respective pulse width modulator is off (e.g., when the switch is open), no current passes through the respective LED 540. Thus, when the respective pulse width modulator is off, the respective LED 540 does not emit light.

[0058] When the respective pulse width modulator is on (e.g., the switch is closed), current passes through the respective LED 540. Thus, when the respective pulse width modulator is on, the respective LED 540 emits light.

[0059] Thus, the drive transistor 530 uses an analog signal, such as a current, to drive the LED 540, while the digital drive IC 550 uses a digital signal, such as a pulse-width modulated signal, to drive the LED 540. Due to this combination of analog and digital drive, the LED 540 can be considered a hybrid drive.

[0060] A pin or other output of the digital driver IC 550 is connected to a low rail such as a ground ring.

[0061] Therefore, in FIG. 5A, no mixed-signal IC design is required.

[0062] As shown in Figure 5A, the digital driver IC 550 has one output. In this case, a single micro-driver drives a large number of LEDs. For a given number of LEDs, using fewer micro-drivers results in lower cost and higher yield.

[0063] It also gives designers greater flexibility by allowing them to optimize the number of analog and digital drivers independently.

[0064] 5B shows a driver system 500B in which an analog IC 520 sets a reference current for multiple digital driver ICs 550 that modulate the current of multiple LEDs 540. Driver system 500B differs from driver system 500A in that an analog IC 520 sets a reference current for multiple digital driver ICs 550, each of which modulates multiple LEDs 540.

[0065] Conventionally, an IC drives 12 sub-pixels for a total of three or four pixels, depending on whether the pixel is defined by three colors (e.g., red, green, and blue) or four colors (e.g., red, green, blue, cyan, or white). Driver system 500B is enhanced so that analog IC 520 can control the current for any number of digital driver ICs 550. In practice, the number of pixels controlled by analog IC 520 is based on the uniformity of the backplane.

[0066] 5A and 5B are intended to illustrate a pixel, not to limit it, and the inputs of the digital driver IC 550 need not be on the same side of the digital driver IC 550. Similarly, the input of the digital driver IC 550 to which the second terminal of the LED 540 is connected can be connected and located on any side of the digital driver IC 550, as is well known. The input and output of the analog IC 520 need not be on opposite sides.

[0067] 6 shows an embodiment of a driver system 600. A current source 620 is implemented with a mixed-signal IC 650, which modulates current for a plurality of LEDs 640. The driver system 600 includes a mirror transistor 610, a current source 620, a drive transistor 630, an LED 640, and the mixed-signal IC 650. The mirror transistor 610, the drive transistor 630, and the LED 640 are structurally similar to the mirror transistor 410, the drive transistor 430, and the LED 440. Therefore, further description of the mirror transistor 610, the drive transistor 630, and the LED 640 is omitted.

[0068] The driver system 600 of Figure 6 differs from the driver system 500A of Figure 5. In Figure 5, an analog IC 520 sets the current, and a digital driver IC 550 modulates the current passing through the LED 540. In the embodiment shown in Figure 6, the driver system 600 has a mixed-signal IC 650 that includes the analog current source 620. The mixed-signal IC 650 also includes a modulator that can modulate the signal (e.g., current) passing through the LED 640. For example, the modulator of the mixed-signal IC 650 can perform pulse-width modulation (PWM) on the signal.

[0069] Thus, the second terminal of drive transistor 610 is connected to a first pin or other input of mixed signal IC 650. Like Figure 5, Figure 6 shows an exemplary, not limiting, chip layout. Thus, in this description, the term "first pin" merely serves to identify one of the pins and is not intended to be limited to pin 1 of mixed signal IC 650 (e.g., the pin closest to the notch or dot, proceeding counterclockwise).

[0070] A first pin of mixed signal IC 650 is connected within mixed signal IC 650 to the input of analog current source 620. Analog current source 620 sets the current that drives transistor 630. The output of analog current source 620 is connected within mixed signal IC 650 to a second pin (again, not necessarily pin 2) of mixed signal IC 650. The second pin of mixed signal IC 650 is connected to a low rail, such as a ground ring.

[0071] The second terminal of the LED 640 is connected to a pin or other input of the mixed signal IC 650. Needless to say, the inputs of the mixed signal IC 650 do not have to be on the same side of the mixed signal IC 650. Similarly, the input to which the second terminal of the LED 640 is connected does not have to be on the same side of the mixed signal IC 650 as the first pin to which the second terminal of the drive transistor 610 is connected. The input of the mixed signal IC 650 to which the second terminal of the LED 640 is connected is connected to the mixed signal IC 650 as is well known and can be flexibly specified.

[0072] The pin or other input of the mixed signal IC 650 to which the second terminal of the LED 640 is connected is connected to a modulator within the mixed signal IC 650. The modulator may be, for example, a pulse width modulator. The pulse width modulator is structurally similar to the pulse width modulator of the digital driver IC 550. Therefore, further discussion of the pulse width modulator is omitted.

[0073] The output of the pulse width modulator is connected to a third pin or other output of the mixed signal IC 650. Of course, other embodiments are possible and the mixed signal IC 650 can have one or more additional outputs to which the output of the pulse width modulator is connected.

[0074] In Figure 6, the mixed signal IC 650 drives four LEDs. In other embodiments, a different number of LEDs can be driven, such as 32 LEDs. In high-resolution applications such as smartphones, the number of pixels per mixed signal IC is often higher. There may also be a single microdriver, as shown in Figure 5.

[0075] Drive transistors that are physically close to each other have similar characteristics and therefore similar performance. Manufacturing defects cause large variations in characteristics across the plate. Therefore, the number of pixels per driver IC depends on the uniformity of the TFT array.

[0076] 7A shows a driver system 700A for different colored LEDs. Separate current sources set the reference current for each color group of LEDs.

[0077] 2, the plurality of LEDs may include a red LED 740R, a green LED 740G, and a blue LED 740B. The red LED 740R, the green LED 740G, and the blue LED 740B may have different characteristics. Thus, in certain applications, different reference currents are provided for the red LED 740R, the green LED 740G, and the blue LED 740B.

[0078] 7A thus includes independent current sources 720R, 720G, and 720B. In one embodiment, current sources 720R, 720G, and 720B are separate components.

[0079] Each of current sources 720R, 720G, and 720B sets a reference current for a mirror transistor. Thus, current source 720R sets the reference current for mirror transistor 710R, analog power supply 720G sets the reference current for mirror transistor 710G, and analog power supply 720B sets the reference current for mirror transistor 720B. While each of these reference currents may be the same, in many embodiments these currents are different.

[0080] Each of the mirror transistors 710R, 710G, and 710B is structurally similar to the mirror transistor 510. Therefore, further description of the mirror transistors 710R, 710G, and 710B will be omitted.

[0081] Additionally, each of drive transistors 730R, 730G, and 730B is structurally similar to drive transistor 530. Accordingly, further discussion of each of drive transistors 730R, 730G, and 730B will be omitted.

[0082] LEDs 740R, 740G, and 740B differ from one another in that they emit light of different colors. In particular, LED 740R emits red light, LED 740G emits green light, and LED 740B emits blue light. Otherwise, each of LEDs 740R, 740G, and 740B is structurally similar to LED 540. Accordingly, further description of LEDs 740R, 740G, and 740B will be omitted.

[0083] To avoid overcomplicating FIG. 7A , one drive transistor 730R, one drive transistor 730G, and one drive transistor 730B are labeled. Furthermore, in FIG. 7A , two transistors 730R are connected to the gate of mirror transistor 710R, two transistors 730G are connected to the gate of mirror transistor 710G, and two transistors 730B are connected to the gate of mirror transistor 710B. Naturally, additional drive transistors 730R, 730G, and 730B can be so connected. Also, the number of drive transistors 730R may differ from the number of drive transistors 730G or the number of drive transistors 730B, and the number of drive transistors 730G may differ from the number of drive transistors 730B.

[0084] The driving system 700A also includes a modulator that can modulate a signal (e.g., a current) passing through the LEDs 740R, 740G, and 740B. The modulator is, for example, a pulse width modulator. The pulse width modulator is structurally similar to the pulse width modulator of the digital driver IC 550. Therefore, further discussion of the modulator will be omitted.

[0085] In some embodiments, LEDs 740R, 740G, and 740B form pixels. In other embodiments, LEDs 740R, 740G, and 740B are individually addressed as pixels themselves.

[0086] FIG. 7B shows a driver system 700B for different colored LEDs, where a separate analog IC sets the reference current for each color group of LEDs.

[0087] That is, Figure 7B differs from Figure 7A in that in Figure 7A, analog power supplies 720R, 720G, and 720B are separate elements, such as separate components. In contrast, Figure 7B shows analog power supplies 720R, 720G, and 720B contained in separate analog ICs.

[0088] Thus, the second terminals of mirror transistors 710R, 710G, and 710B are connected to pins or other inputs of an analog IC that are communicated within the analog IC to respective analog power supplies 720R, 720G, or 720B.

[0089] Analog power supplies 720R, 720G, and 720B set the reference current. The output of each analog power supply 720R, 720G, or 720B is routed to a pin or other output of the analog IC within the respective analog IC. This pin or other output of the analog IC is then routed to a low rail, such as a ground ring.

[0090] In drive system 700B, analog power supplies 720R, 720G, and 720B are shown as being included in three separate analog ICs. In some embodiments, these analog ICs may be combined into fewer analog ICs, such as one analog IC.

[0091] Therefore, no mixed-signal IC design is required for the drive systems 700A, 700B.

[0092] A driver system 800 for different colored LEDs is shown in Figure 8. A mixed signal IC 860 sets a reference current for each color group of LEDs 840R, 840G, 840B and modulates the current for the individual LEDs within the group.

[0093] Figure 8 is generally similar to Figures 7A and 7B. Figure 8 differs from Figure 7B in that analog power supplies 820R, 820B, and 820G are not included in separate analog ICs. In the embodiment of Figure 8, analog power supplies 820R, 820B, and 820G are included in a single mixed-signal IC 860. Modulators 850R, 850G, and 850B are also included in mixed-signal IC 860.

[0094] Mirror transistors 810R, 810G, and 810B are structurally similar to mirror transistors 710R, 710G, and 710B, and therefore further description of mirror transistors 810R, 810G, and 810B will be omitted.

[0095] The second terminals of mirror transistors 810R, 810G, and 810B are connected to pins or other inputs of mixed signal IC 860. These pins or other inputs are internally connected to analog power supplies 820R, 820G, and 820B. Analog power supplies 820R, 820G, and 820B set reference currents. Analog power supplies 820R, 820G, and 820B can be set to have the same or different reference currents. The outputs of analog power supplies 820R, 820G, and 820B are internally connected to one or more pins or other outputs of mixed signal IC 860.

[0096] Similarly, drive transistors 830R, 830G, and 830B are similar to drive transistors 730R, 730G, and 730B, and therefore further description of drive transistors 830R, 830G, and 830B will be omitted.

[0097] LEDs 840R, 840G, and 840B are structurally similar to LEDs 740R, 740G, and 740B. The second terminals of LEDs 840R, 840G, and 840B are connected to pins or other inputs of mixed-signal IC 860. These pins or other inputs are internally connected to the inputs of modulators 850R, 850G, and 850B.

[0098] The modulators 850R, 850G, and 850B are structurally similar to the modulators 750R, 750G, and 750B. Therefore, the modulators 850R, 850G, and 850B may be pulse width modulators. Further description of the modulators 850R, 850G, and 850B is omitted.

[0099] The outputs of modulators 850R, 850G, and 850B are connected to at least one pin or other output of mixed signal IC 860. As shown, mixed signal IC 860 has multiple outputs. In another embodiment, mixed signal IC 860 has a single output. This embodiment can reduce the designer's circuit design concerns.

[0100] 8, driver system 800 includes a single mixed-signal IC 860. Driver system 800 is not limited to a single mixed-signal IC 860. In some implementations, driver system 800 has multiple mixed-signal ICs 860, such as one mixed-signal IC 860 for each color group of LEDs 840R, 840G, and 840B.

[0101] FIG. 9 illustrates a driver system 900 including stacked transistors. The driver system 900 is similar to the driver system 500A. In the embodiment of FIG. 9, the driver system 900 illustrates an IC-free modulator 950. The driver system 900 also includes two mirror transistors 910 and 915. A first terminal of the mirror transistor 910 is connected to a high rail, such as a power signal. A second terminal of the mirror transistor 910 is connected to a first terminal of the mirror transistor 915. A gate of the mirror transistor 910 is connected to the second terminal of the mirror transistor 915 at a node .

[0102] The gate of mirror transistor 915 is connected to node 916. The input of analog power supply 920 is also connected to node 916.

[0103] The analog power supply 920 sets the reference current. The analog power supply 920 is similar to the analog power supply 520. Therefore, further description of the analog power supply 920 is omitted. The output of the analog power supply 920 is connected to a low rail, such as a ground ring.

[0104] A first terminal of the drive transistor 930 is connected to a high rail such as a power signal. A second terminal of the drive transistor 930 is connected to a first terminal of the drive transistor 935. A gate of the drive transistor 930 is connected to a node. A gate of the drive transistor 935 is also connected to the node.

[0105] The second terminal of the drive transistor 935 is connected to the input of the LED device 940 .

[0106] The LED device 940 emits light. The LED device 940 is structurally similar to the LED device 540. Therefore, further description of the LED device 940 will be omitted. The output of the LED device 940 is connected to the input of the modulator 950.

[0107] The modulator 950 is, for example, a pulse width modulator. The modulator 950 is structurally similar to the modulator 550. Therefore, further description of the modulator 950 is omitted.

[0108] In the diagram of drive system 900, the first terminals of mirror transistors 910, 915 are sources and the second terminals of mirror transistors 910, 915 are drains. Similarly, the first terminals of drive transistors 930, 935 are sources and the second terminals of drive transistors 930, 935 are drains. Thus, in the diagram of drive system 900, mirror transistors 910, 915 and drive transistors 930, 935 are all PMOS transistors. In other embodiments, mirror transistors 910, 915 and drive transistors 930, 935 are NMOS transistors, with attendant modifications.

[0109] In driver system 900, analog power supply 920 is shown as a separate component. In other embodiments, analog power supply 920 is included within an analog or mixed-signal IC, for example, as discussed with reference to Figures 5, 6, 7B, and 8. Driver system 900 can also include multiple analog power supplies 920, such as, but not limited to, embodiments in which different currents are set for different colors of LEDs (discussed with respect to Figure 8).

[0110] By using two mirror transistors and two drive transistors in a current mirror, the driver system is more stable when changing the forward voltage (Vf).

[0111] FIG. 10 shows a possible application of an active matrix 1000 display including a driver system according to one embodiment of the present disclosure.

[0112] In one embodiment, the active matrix display 1000 is housed in a vehicle 1020. The vehicle 1020 may be any type of vehicle, such as a motorcycle, a car, a truck, or a work vehicle. The active matrix display 1000 may be incorporated into any feature within the vehicle, such as a dashboard, a rearview camera, an entertainment console (such as a radio tuner or CD player), a global positioning system (GPS), or in-car entertainment (such as a rear passenger television). The active matrix display 1000 may also be incorporated into an augmented reality device, such as a smart windshield.

[0113] In another embodiment, the active matrix display 1000 is included in a wearable device 1040. The wearable device 1040 may be any such wearable device, such as glasses, goggles, headphones, a wig, clothing, or a watch. In the case of goggles or glasses, the wearable device 1040 may use the active matrix display 1000 to provide an augmented reality or virtual reality experience.

[0114] In yet another embodiment, the active matrix display 1000 is included in a portable electronic device 1060, such as a mobile phone, smartphone, tablet computer, or portable gaming system. These devices generally have at least one primary screen that covers most of the planar surface of the portable electronic device. The primary screen may be realized by the active matrix display 1000.

[0115] In some implementations, the portable electronic device 1060 does not have a primary screen, such as a Moving Picture Experts Group (MPEG) Audio Layer III (MP3) player. Such a portable electronic device 1060 may still have an active matrix display 1000 as its screen, if available. Some portable electronic devices may also have secondary screens that complement the primary screen, for example, in a clamshell or on the side or back of the device. These secondary screens may also be realized by the active matrix display 1000.

[0116] In an additional embodiment, the active matrix display 1000 is housed in a laptop computer 1070. The laptop computer 1070 can be a notebook, sub-notebook, ultraportable, netbook, ultrabook, hybrid, convertible, or 2-in-1 laptop.

[0117] In yet another embodiment, the active matrix display 1000 may be implemented within a television 1080. One example of such a television 1080 is a flat panel display.

[0118] Other embodiments are possible as well: for example, the active matrix display 1000 can be housed within an illuminated sign or traffic signal.

[0119] Micro LEDs are LED devices with a maximum width of 1 μm to 100 μm. Micro LED displays can have relatively few LED devices, such as when the display is a 2×3 matrix LED device. Micro LED displays can also have a large number of devices, such as between 2000 and 1,000,000 micro LED pixels. Often, the micro LED pixels are individually addressable.

[0120] In some implementations, driver systems 400, 500A, 500B, 600, 700A, 700B, 800, and 900 can be implemented in light source array 150. Light source array 150 can be an adaptive light source in a system with a neuromorphic vision unit.

[0121] 11 illustrates a system 1100 having a neuromorphic vision unit 1110 and an adaptive light source array 1150 in accordance with one embodiment of the present disclosure. The system 1100 includes a neuromorphic vision unit 1110, a host device system controller 1130, a light source array controller 1140, and a light source array 1150.

[0122] The neuromorphic vision unit 1110 includes neuromorphic pixels that receive light reflected or generated by one or more objects in a scene. The neuromorphic pixels use the photoelectric effect to generate data based on the light received from one or more objects in the scene. Thus, the neuromorphic vision unit 1110 collects data from the scene.

[0123] 11, one or more neuromorphic algorithms may be run on the neuromorphic vision unit 1110. The neuromorphic vision unit 1110 may use the neuromorphic algorithms to perform determination of attributes of one or more objects in a scene. These attributes may include primary attributes such as position, velocity, and previous position, secondary attributes such as acceleration and previous velocity, and / or brightness of one or more objects in the scene.

[0124] Thus, the neuromorphic vision unit 1110 can determine multiple regions in a scene based on one or more objects, and each of the multiple regions can contain one or more objects.

[0125] The neuromorphic vision unit 1110 makes this determination based, at least in part, on the generated data. In one embodiment, the neuromorphic vision unit 1110 makes this determination based on complementary position data.

[0126] For example, in some embodiments, system 1100 may have one or more additional sensors (not shown), such as radar, lidar, or cameras, that can generate supplemental location data. For example, the supplemental data may be or include, for example, location data generated by the one or more additional sensors.

[0127] The neuromorphic vision unit 1110 can determine an exposure time for a pixel of the neuromorphic vision unit 1110. The neuromorphic vision unit 1110 can determine an exposure time for a pixel based, at least in part, on a region of the scene and attributes of one or more objects.

[0128] In some implementations, the neuromorphic vision unit 1110 can additionally or alternatively determine exposure settings for the pixels of the neuromorphic vision unit 1110 or the pixels of the camera based, at least in part, on attributes of the region and objects in the scene. In this disclosure, the term "exposure settings" refers to both exposure times and sensitivity settings.

[0129] The neuromorphic vision unit 1110 may also determine the current and / or pulse width settings (e.g., duty cycle of a single pulse or pulse cycle) for the segments or pixels of the light source array 1150. In one embodiment, the neuromorphic vision unit 1110 may determine these current and / or PWM settings based on calculations performed on the neuromorphic vision unit 1110 or on the host device system controller 1130. This selection may be made based, for example, on the application type.

[0130] Thus, the neuromorphic vision unit 1110 can determine the light source and pixel configuration based on the position and / or velocity determined by the neuromorphic algorithm.

[0131] The host device system controller 1130 can accept the light source and pixel configurations generated by the neuromorphic vision unit 1110.

[0132] The host device system controller 1130 can send the configuration of light sources, neuromorphic and sensor pixels to the light source array controller 1140 to control the light source array 1150. Thus, the host device system controller 1130 can be a relatively simple processor.

[0133] In other embodiments, the host device system controller 1130 can itself translate the light source and pixel configurations into settings for controlling the light source array 1150. Alternatively, the host device system controller 1130 can take raw data from the neuromorphic vision unit 1110 and generate the light source and neuromorphic pixel configurations itself. In embodiments including a sensor system such as a camera, the host device system controller 1130 can generate camera settings based on the raw data. Thus, the host device system controller 1130 may be a more complex device and execute some (or all) of the algorithms itself.

[0134] The light source array controller 1140 receives configurations or generated settings sent from the host device system controller 1130. The light source array controller 1140 can determine or generate signals to modulate the pixels or segments of the light source array 1150. In some embodiments, these signals are analog currents. In other embodiments, these signals are digital signals, such as pulse or pulse-width modulated signals. In other embodiments, these signals are hybrid, i.e., analog currents with modulated pulse widths.

[0135] The light source array 1150 receives the signals output by the light source array controller 1140. The light source array 1150 has an array of light sources, such as LEDs or vertical cavity surface emitting lasers (NCSELs), as pixels. The light sources can produce light in the infrared spectrum, the visible spectrum, and / or the ultraviolet spectrum.

[0136] In most embodiments, the array of light sources is a matrix or one-dimensional vector. Thus, the array is generally arranged in a square or rectangular shape. The scope of this disclosure includes other embodiments, such as a disk or diamond shape.

[0137] The light source array 1150 can be an adaptive LED display. The light source array 1150 includes several segments of one or more light sources in a matrix or vector. Each of the segments can be individually controlled by the light source array controller 1140. For example, each segment can have its own setting (e.g., current, PWM) to illuminate the scene.

[0138] System 1100 can also include optics for directional illumination of the scene by light source array 1150. In some implementations, the display is projected using a projection lens. System 1100 can take a photograph of the display with the light source as a direct view.

[0139] Similar to a conventional LED array, the light source array controller 1140 can drive all segments of the light source array 1150 with the same signal. For example, the light source array controller 1140 can turn off all segments simultaneously. Alternatively, the light source array controller 1140 can turn on all segments, causing all light sources to emit light simultaneously.

[0140] Also, the light source array controller 1140 can control a single segment. Similarly, the light source array controller 140 can control multiple segments simultaneously and independently.

[0141] Generally, all of the light sources in light source array 1150 are included in at least one segment, although embodiments are possible in which one or more light sources are not controlled as part of a segment.

[0142] Additionally, the light sources of light source array 1150 may be included in multiple segments. For example, in an embodiment in which light source array 1150 is a rectangular matrix, a light source may be part of a column segment and part of a row segment.

[0143] The segments of the light source array 1150 can be matrices or vectors. For example, a light source array in a 4x4 matrix can include four 2x2 segments.

[0144] Thus, the light source array controller 1140 can control the entire light source array 1150 individually or as multiple segments simultaneously and in different shapes (e.g., vector or sub-matrix). Thus, the light source array 1150 can be controlled by the light source array controller 1140 with multiple degrees of precision.

[0145] Specifically, the light source array controller 1140 can cause a first segment of the light source array 1150 to illuminate differently than a second segment of the light source array 1150. For example, the first segment can dimly illuminate a first region of a scene, and the second segment can brightly illuminate a second region of the scene.

[0146] If this illumination difference is dictated by the neuromorphic vision unit 1110 rather than from more complex processing or a more powerful processor, differential illumination can be achieved with lower processor power consumption and / or lower latency. Also, the position sensors of conventional adaptive LED systems can be augmented by the neuromorphic vision unit 1110 to detect velocity, acceleration, and brightness.

[0147] Thus, in some embodiments of the system 1100, the programmed neuromorphic vision unit 1110 and the light source array 1150 are combined in a self-adaptive concept: the neuromorphic vision unit 1110 can adjust the exposure time and sensitivity of the pixel regions of the programmable sensor (e.g., the neuromorphic vision unit 1110 or the camera) as well as the configuration of the light sources in the light source array 1150.

[0148] Depending on the application, the neuromorphic vision unit 1110 can co-adjust the current or PWM values ​​of each segment of the light source array 1150 with the exposure time of pixels in the spatial domain (at the accuracy of a single pixel or region of the sensor). For example, a portion of a scene illuminated by a segment of the light source array 1150, and the region of the sensor sensing that portion, can have different local settings (e.g., pixel exposure or sensitivity, LED current / PWM) than segments and regions in other parts of the scene. For example, in certain embodiments, pixel exposure time can be adjusted for each region / pixel of the neuromorphic vision unit 1110. Local adjustment of exposure time and other settings for the various pixels (e.g., neuromorphic, light source, camera sensor) corresponding to each region of the scene results in a set of locally optimal settings. Dynamic scenes in which a first object moves at a different speed than a second object can benefit from local sensor and light source settings.

[0149] Additionally, the first sensor region 1 of the neuromorphic vision unit 1110 can sense a first moving object against a dark background. Based on the neuromorphic vision unit 1110 sensing the first moving object, the light source array controller 1140 can be instructed to control a corresponding first region, LED segment 1, of the light source array 1150. As a result, the light source array controller 1140 can output a minimum pulse width, PWM duty cycle, or LED current to the LED segment 1 that sufficiently illuminates the first moving object.

[0150] Thus, for the system to provide sufficient LED peak illuminance, the neuromorphic vision unit 1110 can reduce the exposure setting (e.g., exposure time or sensitivity) of the local sensor region 1 to a value that minimizes motion blur of the first moving object. Similarly, in embodiments that include a camera, the neuromorphic vision unit 1110 can set the exposure time of the corresponding first region of the camera to a value that minimizes motion blur of the first moving object.

[0151] A second region, sensor region 2, of neuromorphic vision unit 1110 can sense a second moving object moving at a different speed in the foreground of the scene. Thus, light source array controller 1140 can control the PWM duty cycle (or LED current) of LED segment 2 independently of the PWM duty cycle (or LED current) of LED segment 1. Thus, illumination of the second moving object can be optimized independently of illumination of the first moving object.

[0152] Additionally, neuromorphic vision unit 1110 can set the exposure setting for sensor region 2 independently of the exposure setting for sensor region 1. Thus, sensor region 2 of neuromorphic vision unit 1110 can be optimized to reduce or eliminate motion blur of the second moving object. Similarly, in embodiments including a camera, neuromorphic vision unit 1110 can set the exposure setting (e.g., exposure time) of the corresponding second region of the camera to a value that does not result in motion blur of the second moving object.

[0153] Thus, the neuromorphic vision unit 1110 can balance scene illumination and overcome under- and / or over-exposure problems by issuing commands to the light source array controller 1140, and can overcome motion blur by controlling the area of ​​the neuromorphic vision unit 1110 (and camera).

[0154] Similarly, the neuromorphic vision unit 1110 can reduce integration times in the darkest parts of a scene as the light source array 1150 illuminates the scene. Thus, the adaptive illumination of the light source array 1150 can illuminate low-light (or dark) areas of the scene, particularly for objects far away from the sensor. In some embodiments, this illumination can be provided in combination with another software application running on the neuromorphic vision unit 1110. Thus, the applicability and distance range of the system 100 can be enhanced.

[0155] FIG. 12 illustrates an overall flow algorithm 1200 in accordance with one embodiment of the present disclosure.

[0156] The algorithm begins at S1210 and proceeds to S1220.

[0157] At S1220, pixels of an imager of the neuromorphic vision unit 1110 photoelectrically collect light received from an object in the scene. In particular, a computational module of the neuromorphic vision unit can determine a coordinate region of an object in the scene based on the light received from the object by the imager. The computational module can determine the region of the object based, at least in part, on the region of pixels in the imager that receive the light. In many embodiments, the region of coordinates of an object in the scene has two-dimensional coordinates (e.g., (X, Y)) referenced to horizontal and vertical axes. In some embodiments, the region of coordinates can also include a third coordinate referenced to a depth axis (e.g., Z in a three-axis (X, Y, Z)). The coordinates can be based on any reference point.

[0158] In some embodiments, the neuromorphic vision unit 1110 can receive position data from a radar or lidar sensor. Thus, the neuromorphic vision unit 1110 can determine the coordinate region of an object in the scene based on the position data. In many such embodiments, a third coordinate corresponding to a depth axis can be based on this position data.

[0159] The neuromorphic vision unit 1110 can also generate or receive timestamps of the times when the pixels of the imager capture light from the object.

[0160] Based on changes in coordinate areas of similar or similar amounts of light over time and / or changes in the amount of light received in the same coordinate areas, the calculation module can detect movement of objects within the scene.

[0161] For example, Figure 13A shows a scene. Specifically, Figure 13A shows an example of a scene that may be illuminated according to one embodiment of the present disclosure. Figure 13A shows a table and chairs 1320 and a balloon 1340. The table and chairs 1320 are stationary and in the foreground of the scene, while the balloon 1340 is moving and in the background of the scene.

[0162] Table and chair 1320 and balloon 1340 reflect ambient light toward pixels of the imaging device. Thus, in the example of S1220 of FIG. 12, the pixels of the imaging device capture this light at time T1. Based on the light captured by the imaging device from table and chair 1320, the computation module determines that table and chair 1320 is in a region bounded by (0,0), (0,2), (2,2), and (2,0), as shown in FIG. 13B. Similarly, based on the light from balloon 1340 captured by pixels of the imaging device, the computation module can determine that balloon 1340 is in a first region bounded by (3,4), (3,5), (4,5), and (4,4). The computation module can timestamp these regions with time T1.

[0163] Subsequently, the imager's pixels capture reflected ambient light from table and chair 1320 and balloon 1340 at time T2. The computation module again determines that table and chair 1320 is within the region bounded by (0,0), (0,2), (2,2), and (2,0). Meanwhile, balloon 1340 has fallen. Therefore, now the computation module determines, based on the light from balloon 1340 captured by the imager's pixels, that balloon 1340 is within a second region bounded by (3,3), (3,4), (4,4), and (4,3). The computation module can timestamp these regions at time T2.

[0164] The calculation module compares the area of ​​the table and chair 1320 at time T1 with the area of ​​the table and chair 1320 at time T2. Similarly, the brightness of the table and chair 1320 has not changed between time T1 and time T2. Therefore, the calculation module determines that the attributes of the table and chair 1320 have not changed.

[0165] The computational module compares a first area of ​​the balloon 1340 at time T1 with a second area of ​​the balloon 1340 at time T2. Regardless of the change in brightness of the balloon 1340, the neuromorphic vision unit determines that the balloon 1340 is moving. The neuromorphic vision unit 1110 can determine one or more updated attributes of the balloon 1340. These attributes may include the position of the balloon 1340, the velocity (including the direction and magnitude of the velocity) of the balloon 1340, the acceleration (including the direction and magnitude of the acceleration) of the balloon 1340, and, if relevant, the change in brightness of the balloon 1340.

[0166] The computation module can determine the velocity of the balloon 1340 by dividing the difference in position between the first region of the balloon 1340 and the second region of the balloon 1340 by the difference between timestamp T1 and timestamp T2. The difference in position preferably, but not necessarily, corresponds to a difference in real-world position and not just a difference in position between pixels of the neuromorphic vision unit 1110. Thus, the computation module can supplement this difference in position with additional position data from a sensor (e.g., a radar sensor, a lidar sensor, or a camera) that detects the balloon 1340. The computation module can then calculate the difference in position of the balloon 1340 based, at least in part, on the data received from the sensor.

[0167] In some embodiments, the additional position data from the sensors includes a timestamp at which the sensors sensed the data. The calculation module can calculate the velocity of the balloon 1340 based, at least in part, on the timestamp from the sensors.

[0168] The calculation module can also determine the acceleration of the balloon 1340 by dividing the difference between the velocity of the balloon 1340 at time T1 and the velocity of the balloon 1340 at time T2 by the difference between timestamp T1 and timestamp T2.

[0169] Again, the computation module may supplement the calculation of acceleration based, at least in part, on additional position data from sensors, and those skilled in the art will understand how to perform this additional calculation based on the teachings of this disclosure.

[0170] In some embodiments, the computing module may send data indicative of attributes within the system 1100, for example, to the host device system controller 1130. The algorithm then proceeds to S1230.

[0171] In S1230, the neuromorphic vision unit 1110 determines one or more regions of pixels in the light source array 1150 based, at least in part, on the attributes detected in S1220.

[0172] In particular, the one or more regions are based, at least in part, on the position of the object within the scene. For example, if the pixels of the light source array 1150 are mapped one-to-one to the pixels of the imager, the computation module determines a first region bounded by (0,0), (0,2), (2,2), and (2,0), and a second region bounded by (3,4), (3,5), (4,5), and (4,4).

[0173] The computation module can determine additional pixel regions of the light source array 1150 based, at least in part, on the direction of the object's velocity. For example, the computation module can determine that the balloon 1340 is falling. In such a situation, the computation module can determine pixel regions that include (3,3) and (4,3), as well as (3,5) and (4,5). Thus, the computation module can predict the continuity of the object's motion.

[0174] Further, based on a determination that the balloon 1340 is falling at a velocity that exceeds a threshold, the computation module may determine that the region includes additional rows, for example, (3,2) and (4,2). The threshold may be predetermined or dynamically determined based on object and scene attributes (e.g., acceleration or size).

[0175] Additionally, the computation module can determine additional portions of the pixel region of the light source array 1150 based, at least in part, on the acceleration of the object. For example, in an example not shown, based on a determination that the balloon has a downward velocity and is accelerating downward, the computation module can determine that the region includes additional rows, e.g., (3,2) and (4,2), in addition to velocities (3,3) and (4,3). Based on a determination that the balloon 1340 has an upward velocity and is accelerating downward (e.g., being bumped upward and pulled downward by gravity), the computation module can determine that the region includes fewer rows (e.g., only (3,6) and (4,6) instead of (3,7) and (4,7)).

[0176] The use of the same region of coordinates for the imager relative to the coordinate region of the light source array 1150 in FIG. 13B is for illustrative purposes and is not limiting. In many embodiments, the light source array 1150 and the imager have different sizes and / or resolutions. Thus, the region of the light source array 1150 and the region of the imager may be different. Thus, the light source array 1150 and the imager may use different coordinate systems, and the computation module may achieve compatibility by converting between the different coordinate systems.

[0177] Additionally, pixels in the imager are typically offset relative to the object from corresponding pixels in the light source array 1150. Thus, there is an angular difference between the location of a pixel in the light source array 1150 relative to the object and the location of a pixel in the imager relative to the object. Also, because the surface of the object may be textured or curved, the light emitted by a pixel in the light source array 1150 and reflected by the object does not necessarily return to the corresponding pixel in the imager. Thus, the computation module can be compensated. In some embodiments, at least some of the light sources themselves may emit light at an angle.

[0178] For example, many embodiments of system 1100 include optics, such as lenses, for directional illumination of a scene, because a classical array of widely emitting (i.e., Lambertian) LEDs cannot illuminate only a subpart or region of a scene.

[0179] If the calculation module determines that the object is moving closer to the camera (e.g., a change in Z coordinate), the calculation module can determine that the region includes pixels of the light source array 1150 that surround the object's position (e.g., above, below, left, right).

[0180] Similarly, if the computation module determines that an object is receding from the camera, the computation module may determine that a region includes pixels of light source array 1150 around the object's location (e.g., immediately inside the current boundary of the light source pixels corresponding to the object). For example, if a user holds system 1100 and takes a step back from table and chair 1320, the computation module may determine a region that includes (0,0), (0,1), (0,2), (1,0), (1,2), (2,0), (2,1), and (2,2).

[0181] The algorithm 1200 then proceeds to S1240.

[0182] In S1240, the computation module instructs the light source array controller 1140 to adjust the current and / or modulation of the regions of the light source array 1150 determined in S1230. The current and / or modulation is based, at least in part, on attributes of the object (e.g., the table and chair 1320 and / or the balloon 1340).

[0183] Thus, the computation module can improve the brightness provided to the object by an area of ​​the light source array 1150 by increasing the current or, for example, by increasing the duty cycle driving the area of ​​the light source array 1150. The computation module can also decrease the brightness by decreasing the current or, for example, by decreasing the duty cycle driving the area of ​​the pixels of the light source array 1150.

[0184] Also, for example, Figure 13B may show an example of a light source intensity profile for the scene shown in Figure 13A. As can be seen, the region bounded by (3,4), (3,5), (4,5), and (4,4) contains brighter pixels, and the pixels of light source array 1150 corresponding to that region produce more illumination. Thus, light source array 1150 may illuminate balloon 1340 more brightly. For objects in the background or moving objects, a higher level of illumination may be more appropriate.

[0185] The area bounded by (0,0), (0,2), (2,2), and (2,0) contains darker pixels, illustrating that the pixels of light source array 1150 produce less illumination. Thus, light source array 1150 can illuminate table and chair 1320 at a lower level. For objects in the foreground or that are stationary, a lower level of illumination is preferred.

[0186] Pixels outside the two boxes have darker pixels, indicating that the background receives little or no additional illumination. This lack of illumination is appropriate for stationary background objects.

[0187] Thus, adaptive illumination allows the neuromorphic vision unit 1110 to better detect the table and chairs 1320 and the balloon 1340 in the scene. In embodiments that include a camera, the camera can better capture an image of the scene.

[0188] Additionally or alternatively, the computing module may adjust the brightness provided by a region of pixels of the light source array 1150 based, at least in part, on a primary attribute such as the object's velocity. For example, based on a determination that the balloon 1340 is moving downward at a velocity below a threshold, the computing module may increase the illumination slightly. Further, based on a determination that the balloon 1340 is moving downward at a velocity above a threshold, the computing module may increase the illumination of a region of the light source array 1150 by a greater amount.

[0189] Similarly, the neuromorphic vision unit 1110 can adjust the illumination provided by pixel regions of the light source array 1150 based, at least in part, on secondary attributes such as the acceleration of the object. For example, based on a determination that the balloon 1340 has an upward velocity and is accelerating downward, the computational module can slightly increase the illumination of pixels in a region of the light source array 1150. Based on a determination that the balloon 1340 has a downward velocity and is accelerating downward, the computational module can increase the brightness of a region of pixels in the light source array 1150 by a greater amount.

[0190] The computation module can weight the illumination provided by pixels of the light source array 1150 based, at least in part, on a degree of certainty regarding the relevance of the pixels of the light source array 1150. For example, the computation module can illuminate an area according to a gradient. In some embodiments, the gradient can be based, at least in part, on attributes of the object. For example, if the computation module determines a first portion of an area of ​​the light source array 1150 based on the position of the object, the computation module can illuminate the light sources in the first portion of the area more highly. If the computation module determines a second portion of the area based on the velocity of the object, the computation module can illuminate the light sources in the second portion of the area (e.g., (3,3) and (4,3)) more dimly. The computation module can make more sophisticated decisions based on the previous attributes and other attributes, particularly related to the velocity of the object, such as the acceleration of the object.

[0191] If the computation module determines that an object is approaching the camera, the computation module may darken pixels surrounding (e.g., above, below, left, right) an area of ​​the light source array 1150. Similarly, if the computation module determines that an object is receding from the imaging device, the computation module may brighten pixels within an area of ​​the light source array 1150 (e.g., around the object's location).

[0192] Next, algorithm 1200 proceeds to S1250. In S1250, neuromorphic vision unit 1110 determines the region of neuromorphic pixels of the imager based on attributes of the object. These attributes may include the object's position, primary attributes (e.g., the direction and / or magnitude of the object's velocity, position history), and secondary attributes (e.g., the direction and / or magnitude of the object's acceleration, velocity history).

[0193] The neuromorphic vision unit 1110 determines the region of the neuromorphic pixels of the imager based, at least in part, on the neuromorphic pixels that sense the position of the object. The neuromorphic vision unit 1110 can determine the additional region of the pixels of the imager based on the primary and secondary attributes in a manner similar to how the neuromorphic vision unit 1110 determines the additional portion of the region of the pixels of the light source array 11150 in S1230. For example, the additional region can include pixels in the direction of the object's velocity. Therefore, further description will be omitted to avoid obscuring the advantages of the present invention. The algorithm then proceeds to S1260.

[0194] In S1260, the computation module adjusts the region of neuromorphic pixels of the imager based on the attributes of the object. For example, the computation module adjusts the exposure settings of the neuromorphic pixels of the region of the imager. If the computation module determines that the object has a non-zero velocity or positive acceleration, the computation module can reduce the exposure time of the pixels of the region of the imager. If the computation module determines that the object has a negative acceleration, the computation module can increase the exposure time of the pixels of the region of the imager. The algorithm then proceeds to S1270.

[0195] In S1270, the computation module determines and adjusts the pixels of the sensor, as needed. An example of such a sensor is a camera, whether infrared, monochrome, or RGB (red, green, blue). The computation module can determine the areas of the sensor pixels based on attributes of the object. For example, the computation module can determine that the pixels of the sensor photoelectrically capture light from the same object from which the imager captures light.

[0196] The calculation module can then determine the additional area of ​​the sensor's pixels based on the primary and secondary attributes in a manner similar to how the calculation module determines the additional portion of the pixel area of ​​the light source array 1150 in S1230.

[0197] The algorithm ends at S1280.

[0198] (change) 1, driver 140 follows array 130. In one possible modification, driver 140 is between the high rail and transistor 120. In another possible modification, driver 140 is between transistor 120 and array 130.

[0199] Figure 5B shows an example where a single analog IC 520 can set the reference current for multiple digital driver ICs 550. The analog power supply of the other figures can drive multiple digital drivers, as in Figure 5B, so that the teachings of Figure 9 are applicable to the examples of Figures 4-8.

[0200] FIG. 6 was conceived to suggest digital control of modulation. In some embodiments, the switches in FIG. 6 are implemented with analog switches. In such cases, driver system 600 may be implemented with analog IC 650 rather than a mixed-signal IC. These analog switches may also be implemented in other diagrams, such as FIG. 5.

[0201] FIG. 7 (and others) shows one IC for all pixels of a particular color. This depiction is for illustrative purposes only. In some embodiments, there are multiple ICs of a particular color. Indeed, some such embodiments significantly allow the analog power supply to be more precisely adjusted for substrate-to-substrate variations in transistor characteristics.

[0202] As used herein, the terms "storage medium," "computer-readable storage medium," or "computer-readable storage media" refer to non-transitory storage media such as hard drives, memory chips, and cache memory, as well as transient storage media such as carrier waves or propagated signals.

[0203] Aspects of the driver system may be embodied in various forms (e.g., as a method, a system, a computer program product, or one or more computer-readable storage media). Accordingly, aspects of the present disclosure may take the form of a hardware implementation, a software implementation (including firmware, resident software, or microcode), or an embodiment combining software and hardware aspects, generally referred to herein as a “circuit,” “module,” or “system.” Functionality described in this disclosure may be implemented as an algorithm executed by one or more hardware processing units, e.g., one or more microprocessors of one or more computers. In various embodiments, different operations, and some of the operations of the described methods, may be performed by different processing units. Furthermore, aspects of the present disclosure may take the form of a computer program product, e.g., embodied in one or more computer-readable media having computer-readable program code encoded thereon or stored thereon. In various embodiments, such computer programs may be, for example, downloaded (or uploaded) to existing devices and systems or stored in these devices and systems during manufacture.

[0204] The detailed description presents various descriptions of specific embodiments. The described innovations can be implemented in numerous different ways, as defined and covered, for example, by the claims and / or selected examples. In the description, reference may be made to the drawings. In the drawings, like reference numbers may indicate like or functionally similar elements. The elements shown in the drawings are not necessarily drawn to scale. Also, particular embodiments may include more than the elements shown in the drawings and / or a subset of the elements shown in the drawings. Furthermore, some embodiments may incorporate suitable combinations of features from two or more drawings.

[0205] This disclosure describes various exemplary embodiments and examples for implementing the features and functionality of the present disclosure. While components, arrangements, and / or features have been described in connection with various exemplary embodiments, these are merely examples to simplify the disclosure and are not intended to be limiting. In developing any actual implementation, many implementation-specific decisions will be made to achieve the developer's specific goals, including compliance with system, business, and / or legal constraints, which may vary from embodiment to embodiment. Moreover, such a development effort may be complex and time-consuming, but would be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0206] Reference is made herein to spatial relationships between various elements and the spatial orientation of various aspects of elements as shown in the accompanying drawings. The described apparatus, components, members, and devices may be positioned in any orientation. Thus, the use of terms such as "upper," "lower," "upper," "lower," "top," "lower," or other similar terms to describe spatial relationships between various elements or to describe the spatial orientation of such elements, respectively, describes the relative relationships between elements or the spatial orientation of such elements, such that the described elements may be oriented in any direction. When used to describe a range of dimensions or other characteristics (e.g., time, pressure, temperature, length, width, etc.) of an element, operation, and / or condition, the term "between X and Y" refers to a range that includes X and Y. The systems, methods, and devices of the present disclosure have several innovative aspects, none of which is solely responsible for the attributes disclosed herein. Some objectives or advantages may not be achieved by the described embodiments. Thus, for example, a particular embodiment may operate in a manner that achieves or optimizes one suggested advantage or group of advantages, while other objectives or advantages taught or suggested herein may not be achieved or optimized.

[0207] In one embodiment, any number of the electrical circuits in the figures may be implemented on a board of the associated electronic device. The board may be a general circuit board, which holds various components of the electronic device's internal electronic system and may further provide connectors for other peripheral devices. More specifically, the board provides electrical connections by which other components of the system can communicate electrically. Optional processors (including digital signal processors, microprocessors, supporting chipsets, etc.) and computer-readable, non-transitory memory elements may be coupled to the board based on configuration, processing requirements, computer design, etc. Other elements, such as external storage devices, additional sensors, controllers for audio / video displays, and peripherals, may be attached as plug-in cards, via cables, or integrated into the board itself. In various embodiments, the functionality described herein may be implemented in an emulated form as software or firmware operating within one or more configurable (e.g., programmable) elements located within a structure that supports these functions. The software or firmware providing the emulation may be provided on one or more non-transitory computer-readable storage media, which include instructions that enable one or more processors to perform these functions.

[0208] In another exemplary embodiment, the electrical circuits of the figures may be implemented as stand-alone modules (e.g., devices having associated components and circuits configured to perform a specific application or function) or as plug-in modules to application-specific hardware in an electronic device. An embodiment of the present disclosure may be readily included in a system-on-chip (SOC) package. SOC refers to an integrated circuit (IC) that integrates components of a computer or other electronic system onto a single chip. SOCs can include digital, analog, mixed-signal, and often radio frequency functions, which can be provided on a single chip substrate. Other embodiments may include multi-chip modules (MCMs), in which multiple separate ICs are placed within and interact through a single electronic package. In various other embodiments, the processor may be implemented within one or more silicon cores in application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), and other semiconductor chips.

[0209] The specifications, dimensions, and relationships (e.g., number of processors and logic operations) set forth herein are provided for illustrative and suggestive, non-limiting purposes. Such information may vary accordingly. For example, various modifications and changes may be made to the arrangement of components. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense.

[0210] In many of the examples provided herein, interactions are described with respect to two, three, four, or more electrical components for clarity and illustrative purposes. Systems may be integrated in any manner. Along similar design alternatives, the illustrated components, modules, and elements of the drawings may be combined in a variety of possible configurations that are clearly within the scope of this disclosure. In some cases, it may be easier to explain one or more functions of a given set of flows by referencing a limited number of electrical components. The electrical circuits of the drawings and their suggestions can be readily scaled to accommodate many components and more complex / sophisticated arrangements and configurations. Thus, the examples provided are not intended to limit the scope or suggest any limitation to the scope of the electrical circuits, which may potentially be applied to many other architectures.

[0211] In this disclosure, reference to various features (e.g., elements, structures, modules, members, steps, operations, characteristics, etc.) in "one embodiment," "an example embodiment," "an embodiment," "another embodiment," "another example," "various embodiments," "other embodiments," "alternative embodiments," etc. is intended to mean that any such feature is included in one or more embodiments of the disclosure and may or may not be combined in the same embodiment.

[0212] Some of the operations of the present disclosure may be eliminated or omitted where appropriate, or these operations may be modified or significantly altered. Also, the timing of these operations may be significantly altered. The foregoing operational flow is provided for purposes of illustration and discussion. The embodiments described herein provide flexibility in that any suitable arrangement, timeline, configuration, and timing mechanism may be provided.

[0213] (example) In Example 1, a driver system for controlling a plurality of light emitting diodes (LEDs) is provided, the driver system including: a first driver configured to provide an LED current to each of the plurality of LEDs, the first driver including a current mirror for the LED current provided to the plurality of LEDs; and a second driver configured to modulate the LED current provided to the plurality of LEDs.

[0214] Example 2 is the driver system of Example 1, where the current mirror of the first driver has multiple transistors.

[0215] Example 3 is the driver system according to any one of Examples 1 to 2, wherein the plurality of transistors are thin film transistors.

[0216] Example 4 is the driver system of any of Examples 1-3, wherein the first driver has two transistors in the path of the LED current.

[0217] Example 5 is the driver system of any of Examples 1-4, wherein the first driver comprises a first controller that sets a reference current that is mirrored to the LED current.

[0218] Example 6 is the driver system of any of Examples 1-5, wherein the second driver comprises a plurality of pulse width modulation (PWM) drivers.

[0219] Example 7 is the driver system of any of Examples 1-6, wherein the second driver comprises a second controller configured to modulate the LED current.

[0220] Example 8 is the driver system of any of Examples 1-7, wherein the first controller and the second controller are included in a hybrid analog and digital controller.

[0221] Example 9 is the driving system of any of Examples 1-8, wherein the plurality of LEDs are micro LEDs.

[0222] Example 10 is the driving system of any of Examples 1 to 9, wherein the plurality of LEDs includes a first LED and a second LED of a first color, a first LED and a second LED of a second color, a first pixel having the first LED of the first color and the first LED of the second color, and a second pixel having a second LED of the first color and a second LED of the second color, wherein a first LED current is provided to the first and second LEDs of the first color, and a second LED current is provided to the first and second LEDs of the second color.

[0223] Example 11 is a method implemented by a driver system, the method including: providing, using a first driver, an LED current to each of a plurality of light emitting diodes (LEDs), the first driver including a current mirror for the LED current; and modulating, using a second driver, the LED current provided to the plurality of LEDs.

[0224] Example 12 is the method of example 11, wherein the current mirror includes a plurality of transistors, and the plurality of transistors are thin film transistors.

[0225] Example 13 is the method of any of Examples 11-12, wherein the first driver includes a first controller that sets a reference current that is mirrored to the LED current.

[0226] Example 14 is the method of any of Examples 11-13, wherein the second driver includes a plurality of pulse width modulation (PWM) drivers.

[0227] Example 15 is the method of any of Examples 11-14, wherein the second driver includes a second controller configured to modulate the LED current.

[0228] Example 16 is the method of any of Examples 11-15, wherein the first controller and the second controller are included in a hybrid analog and digital controller.

[0229] Example 17 is the method of any of Examples 11-16, wherein the plurality of LEDs are micro LEDs.

[0230] Example 18 is the method of any of Examples 11-17, wherein the plurality of LEDs includes a first LED and a second LED of a first color, a first LED and a second LED of a second color, a first pixel having the first LED of the first color and the first LED of the second color, and a second pixel having the second LED of the first color and the second LED of the second color, wherein a first LED current is provided to the first LED and the second LED of the first color, and a second LED current is provided to the first LED and the second LED of the second color.

[0231] Example 19 is a light emitting diode (LED) matrix having a plurality of LEDs arranged in rows and columns, a first driver configured to provide an LED current to each of the plurality of LEDs, the first driver including a current mirror for the LED current provided to the plurality of LEDs, and a second driver configured to modulate the LED current provided to the plurality of LEDs.

Claims

1. 1. A driver system for controlling a plurality of light emitting diodes (LEDs), comprising: the plurality of LEDs includes a first pixel and a second pixel; the first pixel has a first LED of a first color and a first LED of a second color, the second pixel has a second LED of the first color and a second LED of the second color; The driver system a first driver configured to provide a first LED current to the first and second LEDs of the first color, the first driver having a current mirror for the first LED current including a first transistor and a second transistor arranged in parallel with each other; a second driver configured to supply a second LED current to the first and second LEDs of the second color; a modulation driver configured to modulate the first LED current, the modulation driver having a first modulator connected in series with the first LED of the first color and a second modulator connected in series with the second LED of the first color; and the first LED of the first color has one end coupled to the first end of the first transistor and the other end coupled to the first end of the first modulator, the second end of the first transistor coupled to the high rail, and the second end of the first modulator coupled to the low rail; a second LED of the first color having one end coupled to a first end of the second transistor and another end coupled to a first end of the second modulator, a second end of the second transistor coupled to the high rail, and a second end of the second modulator coupled to the low rail;

2. 2. The driver system of claim 1, wherein the current mirror of the first driver has a plurality of transistors including the first transistor and the second transistor.

3. The driver system of claim 2 , wherein the plurality of transistors are thin film transistors.

4. 3. The driver system of claim 2, wherein the first driver includes two transistors in a path of the first LED current.

5. 2. The driver system of claim 1, wherein the first driver comprises a first controller that sets a reference current that is mirrored to the first LED current.

6. The driver system of claim 1 , wherein the modulation driver comprises a plurality of pulse width modulation (PWM) drivers.

7. 6. The driver system of claim 5, wherein the modulation driver comprises a second controller configured to modulate the first LED current.

8. The driver system of claim 7 , wherein the first controller and the second controller are included in a hybrid analog and digital controller.

9. The driver system of claim 1 , wherein the plurality of LEDs are micro LEDs.

10. 1. A method for controlling a plurality of light emitting diodes (LEDs), comprising: the plurality of LEDs includes a first pixel and a second pixel, the first pixel includes a first LED of a first color and a first LED of a second color, and the second pixel includes a second LED of the first color and a second LED of the second color; The method comprises: providing a first LED current to the first and second LEDs of the first color using a first driver, the first driver having a current mirror for the first LED current including a first transistor and a second transistor arranged in parallel with each other; providing a second LED current to the first and second LEDs of the second color with a second driver; modulating the first LED current with a first modulator in a modulation driver connected in series with the first LED of the first color and a second modulator in a modulation driver connected in series with the second LED of the first color; and the first LED of the first color has one end coupled to the first end of the first transistor and the other end coupled to the first end of the first modulator, the second end of the first transistor coupled to the high rail, and the second end of the first modulator coupled to the low rail; the second LED of the first color has one end coupled to a first end of the second transistor and the other end coupled to a first end of the second modulator, the second end of the second transistor coupled to the high rail, and the second end of the second modulator coupled to the low rail.

11. the current mirror has a plurality of transistors including the first transistor and the second transistor; The method of claim 10 , wherein the plurality of transistors are thin film transistors.

12. 11. The method of claim 10, wherein the first driver comprises a first controller that sets a reference current that is mirrored to the first LED current.

13. The method of claim 10 , wherein the modulation driver comprises a plurality of pulse-width modulation (PWM) drivers.

14. The method of claim 12 , wherein the modulation driver comprises a second controller configured to modulate the first LED current.

15. The method of claim 14 , wherein the first controller and the second controller are included in a hybrid analog and digital controller.

16. The method of claim 10 , wherein the plurality of LEDs are micro LEDs.

17. A light emitting diode (LED) matrix comprising: a plurality of LEDs arranged in rows and columns, the plurality of LEDs includes a first LED and a second LED of a first color, and a first LED and a second LED of a second color; a first pixel having the first LED of the first color and the first LED of the second color; a second pixel including a plurality of LEDs, the second LED being of the first color and a second LED being of the second color; a first driver configured to provide a first LED current to the first and second LEDs of the first color, the first driver having a current mirror for the first LED current including a first transistor and a second transistor arranged in parallel with each other; a second driver configured to provide a second LED current to the first and second LEDs of the second color; a modulation driver configured to modulate the first LED current, the modulation driver having a first modulator connected in series with the first LED of the first color and a second modulator connected in series with the second LED of the first color; and the first LED of the first color has one end coupled to the first end of the first transistor and the other end coupled to the first end of the first modulator, the second end of the first transistor coupled to the high rail, and the second end of the first modulator coupled to the low rail; The second LED of the first color has one end coupled to a first end of the second transistor and the other end coupled to a first end of the second modulator, a second end of the second transistor coupled to the high rail, and a second end of the second modulator coupled to the low rail, an LED matrix.

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