Multi-power supply circuit for LED arrays

Abstract

The power supply system for the LED pixel array includes at least two power supplies connectable to respective sub-arrays in the LED pixel array and providing adjustable power. A controller is connected to the at least two power supplies and is capable of adjusting the supplied power based on measured requirements of the sub-arrays in the LED pixel array. In one embodiment, the LED pixel array is a micro LED array.

Description

[Technical field]

[0001] Related Applications This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 089,653, filed October 9, 2020, entitled “Multiple Power Supply Circuit for a Micro-LED Array,” the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates generally to a power supply for monolithic or segmented light emitting diode (LED) dies. The power supply can be used for general lighting or display systems based on micro LED pixel arrays. [Background technology]

[0003] The use of micro LED displays or projectors is an emerging technology in the lighting and display industry. Micro LEDs can contain an array of thousands to millions of tiny LED pixels that emit light and are individually controlled. Compared to other display technologies, micro LEDs can have higher brightness and better energy efficiency, making them attractive for a variety of applications such as television displays and backlights, automotive lights, and mobile phones. Summary of the Invention

[0004] In some embodiments, a power supply system for the LED pixel array includes at least two power supplies connectable respectively to sub-arrays in the LED pixel array and providing adjustable power, and a controller is connected to the at least two power supplies and is capable of adjusting the power provided based on measured requirements of the sub-arrays in the LED pixel array.

[0005] In some embodiments, the LED pixel array comprises a micro LED pixel array.

[0006] In some embodiments, the settings of at least two of the power supplies are factory set.

[0007] In some embodiments, the settings of at least two of the power supplies are dynamically set.

[0008] In some embodiments, at least two of the power supplies are buck converters.

[0009] In some embodiments, at least two power supplies are connected to a positive power supply voltage and share a common ground.

[0010] In some embodiments, at least two power supplies are each connectable in parallel to a respective sub-array within the LED pixel array.

[0011] In some embodiments, a micro LED pixel array system includes a plurality of micro LED pixels supporting independently powered sub-arrays. At least two power sources are respectively connected to each of the sub-arrays of the plurality of micro LED pixels to provide adjustable power. A controller is connected to the at least two power sources, the controller being capable of adjusting the supplied power based on measured requirements of the sub-arrays of the plurality of micro LED pixels.

[0012] In some embodiments, each pixel in the plurality of micro LED pixels is independently addressable to enable on / off operation.

[0013] In some embodiments, a method of controlling an LED array includes providing a plurality of micro LED pixels arranged to have at least two independently powered sub-arrays, each of the LED sub-arrays being provided with power suitable for efficient forward voltage shift matching, power usage can be measured for at least some of the plurality of micro LED pixels, and power provided to the independently powered sub-arrays is dynamically adjusted based on the measured power usage. [Brief description of the drawings]

[0014] [Figure 1] 1 illustrates an LED display system including an LED array that supports multiple power sources. [Diagram 2] 1 illustrates an embodiment including power supplies to multiple sub-arrays. [Figure 3A] 1 illustrates an embodiment of a power supply that uses multiple buck converters to power LEDs in an array. [Figure 3B] 1 illustrates an embodiment of a power supply that uses multiple buck converters to power LEDs in an array. [Figure 4] 1 illustrates the operation of an embodiment of a micro LED control module supporting multiple dynamically regulated power sources. [Diagram 5] An example of a system with a micro LED control module supporting multiple power sources is shown. [Figure 6] It shows a detailed chip-level implementation of a system with a microLED control module supporting multiple power sources. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] In an LED array, the luminous color or intensity of the LEDs in the array is a function of the LED current supplied. Small variations in current across the die or substrate supporting the micro-LEDs can result in undesirable color or intensity changes. Undesirable color or intensity changes are those that are inconsistent with the image provided by the array. Furthermore, traditional power supply schemes are relatively electrically inefficient due to variations in LED forward voltage across the micro-LEDs. When all pixels are connected in parallel and share the same power supply, the supply voltage is designed for the maximum LED forward voltage in the array. However, pixels with lower LED forward voltages inevitably experience higher voltage drops and losses in the pixel drivers, reducing system efficiency.

[0016] FIG. 1 illustrates an LED display system 100 that includes an LED array 110. As shown, each box in the LED array 110 defines a pixel 102 that can be controlled using a system controller 120. The system controller 120 can include connections to or incorporation of multiple power supplies, one or more power drivers, and control software. The multiple power supplies, one or more power drivers, and control software allow for measurement and control of the current and voltage provided by the multiple power supplies to the LED array 110. The control can be dynamically adjusted after deployment or set during calibration. The system controller 120 can be used to adjust the power provided to the LED array 110 to change pixel intensity, color, and on / off state for individual pixels or selected groups of pixels.

[0017] In some embodiments, the LED array 110 can be formed from an array of micro-LEDs (sometimes referred to as "μLEDs" or "uLEDs"). Micro-LEDs can support high density pixels with lateral dimensions of less than 100 micrometers (μm) by 100 μm. In some embodiments, micro-LEDs with dimensions of about 50 μm or less in diameter or width can be used. Such micro-LEDs can be used for color displays by closely aligning micro-LEDs containing red, blue, and green wavelengths. In other embodiments, the micro-LEDs can be defined on a monolithic gallium nitride (GaN) or other semiconductor substrate, and can be formed on a segmented, partially, or fully partitioned semiconductor substrate, or can be formed individually or into panels assembled as groups of micro-LEDs. In some embodiments, the LED array 110 can include a small number of micro-LEDs arranged on a substrate with an area on the centimeter scale or greater. In some embodiments, the LED array 110 can support a micro-LED pixel array including hundreds, thousands, or millions of LEDs arranged together on a substrate with an area on the centimeter scale or less. In some embodiments, the micro-LEDs can include light emitting diodes with sizes between 30 microns and 500 microns. In some embodiments, micro LED pixel arrays can be formed from light emitting elements of various types, sizes, and layouts. In some embodiments, one-dimensional or two-dimensional matrix arrays of individually addressable light emitting diodes (LEDs) can be used. A typical NxM array can be used, where N and M are each between 2 and 1000. Individual LED structures can have square, rectangular, hexagonal, polygonal, circular, arc, or other surface shapes. Arrays of LED assemblies or structures can be geometrically arranged in straight rows and columns, staggered rows and columns, curved, or semi-random or random layouts. LED assemblies can include multiple LEDs formed, with individually addressable pixel arrays also supported.In some embodiments, a radial or other non-rectangular grid arrangement of conductive lines to the LEDs can be used, while other embodiments can use curved, wound, serpentine, and / or other suitable non-linear arrangements of conductive lines to the LEDs.

[0018] FIG. 2 illustrates an embodiment 200 showing n power sources 220, 222, 224 providing independent power to n sub-arrays 226, 228, 230 of the entire LED array 210. Instead of using a common power source to power all pixels in the LED array 210 (which can be, for example, a micro LED matrix or similar LED display / light projector), each power source 220, 222, 224 is connected to a respective sub-array n. Advantageously, the size of each power source 220, 222, 224 can be much smaller than the size of a single power source for the micro LED array 210, since each individual power source 220, 222, 224 can reduce the amount of power rather than providing the total power for the entire LED array 210. Furthermore, the configuration illustrated in FIG. 2 allows more flexibility in the configuration of the power sources 220, 222, 224, since there are more options for power components that form the power sources 220, 222, 224 to operate at relatively low power levels.

[0019] In some embodiments, each power supply voltage may be fixed or dynamically adjusted to regulate the LED forward voltages of individual LED subarrays in the LED array 210 based on the determined LED forward voltages. 226,228,230 A fixed supply voltage can be calibrated and set at the factory or after deployment. A dynamically regulated supply can be factory calibrated or dynamically set at power up of the LED array, intermittently during operation, or automatically adjusted by direct measurement of power usage or by tuning each sub-array. 226,228,230It can also be continuously scheduled to adjust the voltage supply based on a simulation or estimate of the power used by the subarrays. For example, where energy efficiency is more important, continuous scheduling can be used. Where energy efficiency is less important, less power measurements and less voltage supply adjustments can be made. This allows, for example, subarray 1 to be powered using a voltage that efficiently matches the LED forward voltage used, which is different from the voltage used by subarray 2. The supply voltage can be adjusted based on the power used by the subarrays. 226,228,230 The forward voltage of the LEDs in the LED array can be set based on the maximum value, average value, etc.

[0020] 3A and 3B together illustrate an embodiment of a power supply system 300 that uses multiple buck converters 330, 332, and 334. The buck converters 330, 332, and 334 can provide digitally controlled output voltages. The output voltages can be set by the controller 120 (see FIG. 1) based on the maximum forward voltage of the subarray that the buck converters 330, 332, and 334 power. Thus, each buck converter 330, 332, and 334 can provide a different positive power. The illustrated buck converters 330, 332, and 334 include output ports, one of which provides a common negative voltage to all buck converters 330, 332, and 334, and another of which provides a positive voltage that depends on the electrical characteristics of the subarray.

[0021] The power supply system 300 is connected to an LED array 210 (at least as shown in FIG. 3B) that includes n (e.g., 10,000) pixels 336, 338, 340 and partially represents an LED array divided into m (e.g., 10) segments of 1000 pixels. The segments can have different numbers of pixels. Each of the pixels 336, 338, 340 is part of a different segment of pixels of the array 210. Each segment is powered by a separate positive voltage from the system 300. In FIGS. 3A and 3B, there are m power supplies 220, 222, 224 including respective buck converters 330, 332, 334 bases that convert a 12V input voltage from Vout1+ to Vout10+ to a 3.5V output voltage. The power supplies 220, 222, 224 share a common ground Vout-. In FIG. 3B, all micro LED sub-arrays share a common ground Vout- and each sub-array is connected to its own positive power supply voltage from Vout1+ to Vout10+. Within each segment, all pixels are connected in parallel and share the same power supply 220, 222, 224. Each pixel contains a current source, a pulse-width modulation (PWM) switch, and a micro LED.

[0022] FIG. 4 illustrates a micro LED control module supporting multiple dynamically regulated power sources 220, 222, 224 (e.g., local control Module502 and / or command and control module 616). In operation 402, a calibration is performed, such as at the factory, at turn on of the LED array, intermittently during operation, or continuously scheduled. In some embodiments, the calibration includes determining operational dependencies based on at least one of LED design, manufacturing factors, or supply current. Based at least in part on the calibration measurements, in operation 404, each LED sub-array power supply 220, 222, 224 provides power suitable for efficient forward voltage shift matching. In operation 406, power usage is measured for each pixel or sub-array of selected pixels. The measurements can be set once, intermittently during operation, or continuously scheduled. In operation 408, dynamically adjusted power is provided, and the process can be repeated as necessary. The power can be adjusted based on the power usage measured in operation 406.

[0023] FIG. 5 shows an example of a lighting matrix control system 500 with appropriate lighting logic and control modules and / or pulse width modulation modules that allow for individually controlled and adjusted pixel intensity by setting appropriate lamp times and pulse widths. Addressable LED pixel activation can be used to provide patterned lighting, reduce color or intensity variations, and provide various pixel diagnostic features. As discussed with respect to FIG. 1, a micro LED array such as that shown in FIG. 5 can include an array of thousands to millions of tiny LED pixels that actively emit light and are individually controlled. To emit light in a pattern or sequence that displays an image, the current levels of micro LED pixels at different locations on the array are individually adjusted according to a particular image. This may include pulse width modulation (PWM) to turn pixels on or off at a particular frequency. During PWM operation, the average direct current (DC) through a pixel is the product of the current amplitude and the PWM duty cycle, the latter being the ratio of conduction time to period or cycle time.

[0024] Processing modules that facilitate efficient use of the system 500 are shown in FIG. 5. The system 500 includes a control module 502 that can implement pixel-level control of pixels or groups of amplitude and duty cycle of the micro LED array. In some embodiments, the system further includes an image processing module 504 for generating, processing, or transmitting images, and an inter-integrated circuit (IIC) configured to transmit necessary control data or instructions. 2 C)(I 2 The digital control interface 506 includes a digital control interface such as a DMA controller (DMAC), where C is a synchronous, multi-reader, multi-follower, packet-switched, single-ended, serial communication bus). The digital control interface 506 and the control module 502 can include a system microcontroller and any type of wired or wireless module configured to receive control inputs from an external device. By way of example, the wireless module can include a bluetooth, Zigbee, Z-wave, mesh, WiFi, near field communication (NFC), and / or peer-to-peer module. The microcontroller can be any type of special purpose computer or processor that is incorporated into the LED lighting system and configured or configurable to receive inputs from the wired or wireless module or other modules in the LED system and provide control signals to other modules based thereon. The algorithms implemented by the microcontroller or other suitable control module 502 can be implemented in a computer program, software, or firmware embodied in a non-transitory computer-readable storage medium for execution by the special purpose processor. Examples of non-transitory computer-readable storage media include read-only memory (ROM), random access memory (RAM), registers, cache memory, and semiconductor memory devices. The memory may be included as part of the microcontroller, or it may be implemented elsewhere on or off the printed circuit or electronic board.

[0025] As used herein, the term module may refer to electrical and / or electronic components located on individual circuit boards that may be soldered to one or more electronic substrates, although the term module may also refer to electrical and / or electronic components that serve a similar function but are individually soldered to one or more circuit boards in the same or different areas.

[0026] As previously mentioned, the local control module 502 further includes an image processing module 504 and an I 2 A digital control interface 506 such as a Serial Peripheral Interface (SPI), Controller Area Network (CAN), Universal Asynchronous Receiver Transmitter (UART), Universal Serial Bus (USB), etc., may be included. In some embodiments, image processing calculations may be performed by the control module 502 by directly generating a modulated image. Alternatively, standard image files may be processed or converted to provide modulation to match the image. Image data, mainly including PWM duty cycle values, may be processed for every pixel in the image processing module 504. Since the amplitude is a fixed or rarely changed value, amplitude related commands may be given individually through a digital interface as mentioned herein. The control module 502 interprets all the digital data, which is then used by the PWM generator to generate the pixel's PWM signal 510 and the digital-to-analog converter (DAC) signal 512 to generate the control signal to obtain the required current source amplitude. In some embodiments, discrete temperature sensors (T1-T4) may be used for temperature monitoring, which may complement or provide calibration for the pixel-level temperature monitoring system and method described. In one embodiment, the pixel matrix 520 of Figure 5 can include m pixels capable of supporting pixel-level temperature measurement, in one embodiment, the pixels are connected to multiple current sources and PWM switches as described above with respect to Figure 4.

[0027] FIG. 6 shows in more detail a one-chip level implementation of a system 600 supporting functionality as discussed with respect to FIGS. 3A-B, 4 and 5. The system 600 includes a command & control module 616 that can calibrate and provide individual power levels to the LED sub-arrays, control monitoring and control, as well as implement pixel level control of pixels or groups of circuit amplitude and duty cycle. In some embodiments, the system 600 further includes a frame buffer 610 for holding a generated or processed image that can be fed to an active LED matrix 620. Other modules include an I / O module 620 configured to transmit necessary control data or instructions. 2 A digital control interface such as a C serial bus 612 or a SPI 614 may be included.

[0028] During operation, the system 600 I6 14. Continuous image or video data may be stored in image frame buffer 610. When image data is not available, one or more standby images held in standby image buffer 611 may be transferred to image frame buffer 610. Such standby images may include, for example, an intensity and spatial pattern that matches a legally permitted low beam headlamp radiation pattern of a vehicle, or a default light radiation pattern of architectural lighting or a display.

[0029] In operation, pixels in an image are used to define the response of corresponding LED pixels in the active, and the intensity and spatial modulation of the LED pixels is based on the image. To mitigate data rate issues, in some embodiments, a group of pixels (e.g., a 5x5 block) can be controlled as a single block. In some embodiments, high and fast data rate operation is supported, and pixel values ​​from successive images can be loaded as successive frames of an image sequence at a rate between 30Hz and 100Hz, with 60Hz being typical. Using PWM, each pixel can be controlled to emit light in a pattern, the intensity of which depends at least in part on the image held in the image frame buffer 610.

[0030] In some embodiments, the system 600 can receive logic power via Vdd and Vss pins. The active matrix receives power for LED array control through multiple VLED and VCathode pins. The SPI 614 can provide full duplex mode communication using a leader-follower architecture with a single leader. The leader device originates frames for reading and writing. Multiple follower devices are supported with selection on individual slave select (SS) lines. Input pins can include leader-out follower-in (MOSI), leader-in follower-out (MISO), chip select (SC), and clock (CLK), all connected to the SP. I6 Connected to 14. SP I6 14 connects to the address generator, frame buffer, and standby frame buffer. The pixels can set parameters and change signals or power (e.g., by power gating before entering the frame buffer, or after output from the frame buffer via pulse width modulation or power gating) by the command and control module. I614 may be connected to an address generation module 618, which provides row and address information to the active matrix 620. The address generation module 618 may provide frame buffer addresses to the frame buffer 610.

[0031] In some embodiments, I 2 The command and control module 616 can be externally controlled via a 3.3-V serial bus 612. It can support 7-bit addressing on the clock (SCL) and data (SDA) pins. The command and control module 616 can include a DAC and two analog-to-digital converters (ADCs), which respectively control the V of the connected active matrix. bias Setting the maximum V f , to help determine the system temperature, or to set the power supplied to each LED pixel sub-array. Also connected is an oscillator (OSC) that sets the pulse width modulated oscillation (PWMOSC) frequency of the active matrix 620. In one embodiment, there are also bypass lines to allow addressing of individual pixels or blocks of pixels within the active matrix for diagnostic, calibration, or test purposes. The active matrix 620 can be further supported by row and column selection used to address individual pixels to which data lines, bypass lines, PWMOSC lines, Vbias lines, and Vf lines are provided.

[0032] As will be appreciated, in some embodiments, the described circuitry and active LED matrix 620 can be packaged and, if necessary, can include a submount or printed circuit board connected for powering and controlling light generation by the semiconductor LEDs. In certain embodiments, the printed circuit board can also include electrical vias, heat sinks, ground planes, electrical traces, and flip chip or other mounting systems. The submount or printed circuit board can be formed of a suitable material, such as ceramic, silicon, aluminum, etc., and if the submount material is conductive, an insulating layer is formed over the substrate material, and a metal electrode pattern is formed over the insulating layer. The submount can act as a mechanical support that provides an electrical interface between the electrodes on the LEDs and a power source, and also provides thermal sinking.

[0033] More generally, emissive active matrix pixel arrays as described herein may support applications that benefit from fine-grained intensity, spatial and temporal control of light distribution. This may include, but is not limited to, precise spatial patterning of emitted light from pixel blocks or individual pixels. Depending on the application, the emitted light may be spectrally differentiated, adaptive over time, and / or responsive to the environment. The emissive pixel array may provide pre-programmed distributions of light with different intensity, spatial, or temporal patterns. The emitted light may be based, at least in part, on received sensor data and may be used for optical wireless communication. The associated optics may vary at the pixel, pixel block, or device level. An example of an emissive pixel array may include a device with a commonly controlled central block of high brightness pixels with associated common optics, while edge pixels may have separate optics. Common applications supported by emissive pixel arrays include video lighting, automotive headlights, architectural and area lighting, street lighting, and information displays.

[0034] Illuminant matrix pixel arrays may be used to selectively and adaptively illuminate buildings or areas to improve visual displays or to reduce lighting costs. Additionally, emissive pixel arrays may 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 may be possible. Spectrally distinct pixels may be used to adjust the color temperature of the lighting or to support wavelength-specific horticultural lighting.

[0035] Street lighting is an application that can greatly benefit from the use of emissive pixel arrays. A single type of emissive array can be used to mimic different street light types, for example, switching between a Type I linear street light and a Type IV semicircular street light by appropriate activation or deactivation of selected pixels. Also, the cost of street lighting can be lowered by adjusting the light intensity or distribution according to environmental conditions or time of use. For example, the light intensity and area of ​​distribution 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 may be adjusted according to the respective daylight, twilight, or nighttime conditions.

[0036] Light emitting arrays are also suitable to support applications requiring a direct or projected display. For example, warning, emergency, or information signs may all be displayed or projected using light emitting arrays. This allows, for example, the projection of color changing or flashing exit signs. If the light emitting array is composed of many pixels, textual or numerical information may be displayed. Directional arrows or similar indicators may also be provided.

[0037] Vehicle headlamps are emissive array applications that require large pixel counts and high data refresh rates. Automotive headlights that actively illuminate only selected sections of the road can be used to mitigate problems associated with glare and glare for oncoming drivers. Using an infrared camera as the sensor, the emissive pixel array activates only the pixels required to illuminate the road and deactivates pixels that may dazzle pedestrians or oncoming drivers. Additionally, off-road pedestrians, animals, or signs may be selectively illuminated to improve the driver's environmental awareness. If the pixels of the emissive pixel array are spectrally distinct, the color temperature of the light may be adjusted according to the respective daylight, twilight, or nighttime conditions. Some pixels may be used for optical wireless vehicle-to-vehicle communication.

[0038] Other notes and examples

[0039] Example 1 can include a power system for a light emitting diode (LED) pixel array including at least two power supplies, each configured to provide adjustable power to a respective LED subarray in the LED pixel array; and a controller for the at least two power supplies, the controller configured to: measure a forward voltage of each LED pixel of the LED subarray; and adjust power provided by the at least two power supplies based on the measured forward voltage of each LED pixel of the LED subarray.

[0040] In Example 2, Example 1 can further include, where the LED pixel array includes a micro LED pixel array.

[0041] In Example 3, at least one of Examples 1-2 can further include, where the settings of the at least two power supplies are factory set.

[0042] In Example 4, at least one of Examples 1-3 can further include, where the settings of the at least two power supplies are dynamically set.

[0043] In Example 5, at least one of Examples 1-4 can further include, where the at least two power supplies include a buck converter.

[0044] In Example 6, at least one of Examples 1-5 can further include, where the at least two power supplies include a plurality of ports, a first port of the plurality of ports supplying an independent positive power, and a second port of the plurality of ports supplying a common ground voltage to all subarrays of the LED pixel array.

[0045] In Example 7, at least one of Examples 1-6 can further include, where the at least two power supplies are respectively connectable in parallel to respective sub-arrays of the LED pixel array.

[0046] Example 8 includes a micro light emitting diode (LED) pixel array system that includes a plurality of micro LED pixels arranged in independently powered subarrays, at least two power sources coupled to each of the subarrays and configured to provide adjustable power to the subarrays, and a controller for the at least two power sources, measuring an electrical characteristic of each LED pixel in the subarray, and adjusting the power provided by the at least two power sources based on the measured electrical characteristic.

[0047] In Example 9, example 8 can further include, each pixel of the plurality of micro LED pixels being independently addressable.

[0048] In Example 10, at least one of Examples 8-9 can further include the settings of the at least two power supplies being factory set or dynamically set after deployment.

[0049] In Example 11, at least one of Examples 8-10 can further include, wherein the measured electrical characteristic includes a forward voltage of a pixel of the LED subarray.

[0050] In Example 12, at least one of Examples 8-11 can further include, wherein the at least two power sources include a buck converter.

[0051] In Example 13, at least one of Examples 8-12 can further include, wherein the at least two power sources provide independent positive power supply voltages and provide a shared common ground voltage.

[0052] In Example 14, at least one of Examples 8-13 can further include, wherein the at least two power sources are each electrically connected in parallel with each other, and each of the at least two power sources is electrically connected to a respective subarray of a respective subarray in the LED pixel array.

[0053] Example 15 includes a method of controlling a light emitting diode (LED) array, the method including providing a plurality of micro LED pixels arranged to include at least two independently powered sub-arrays, each sub-array including a respective micro LED pixel of the plurality of micro LED pixels, providing power to each sub-array based on forward voltage shift matching, measuring power usage of at least some of the plurality of micro LED pixels, and dynamically adjusting power provided to the independently powered sub-arrays based on the measured power and the forward voltage shift.

[0054] Example 16 can further include example 15, where the power supply includes a separate positive power supply and a shared common ground supply.

[0055] Example 17 can further include at least one of Examples 15-16, where each pixel of the plurality of micro LED pixels includes a current source, a pulse width modulated switch, and an LED connected in series.

[0056] In Example 18, at least one of Examples 15-17 can further include a configuration of at least two power sources at the manufacturing facility that provide power.

[0057] In Example 19, at least one of Examples 15-18 can further include an independent modifying operation of each pixel in the plurality of micro LED pixels.

[0058] Example 20 can further include at least one of Examples 15-19, where at least two power sources each providing power include a buck converter.

[0059] Many modifications and other embodiments of the invention will come to mind to one skilled in the art having the benefit of the teachings presented in the foregoing description and the associated drawings. It is therefore understood that the invention is not limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims. It is also understood that other embodiments of the invention may be practiced in the absence of elements / steps not specifically disclosed herein. In those embodiments supporting software controlled hardware, the methods, procedures, and implementations described herein may be realized in a computer program, software, or firmware embodied in a computer readable medium for execution by a computer or processor. Examples of computer readable media include electronic signals (transmitted over wired or wireless connections) and computer readable storage media. Examples of computer readable storage media include, but are not limited to, read only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, optical media such as CD-ROM disks, digital versatile disks (DVDs), and the like.

Claims

1. 1. A power supply system for a light emitting diode (LED) pixel array, comprising: at least two power sources each configured to provide adjustable power to a respective LED subarray in the LED pixel array, each LED pixel of the LED subarray including a current source and an LED; A controller for the at least two power sources, the controller comprising: measuring a forward voltage of each LED pixel of the LED subarray; and a controller configured to adjust power provided by the at least two power sources based on the measured forward voltage of each LED pixel of the LED subarray, and for each power source of the at least two power sources, the power provided by the power source is either set once upon power-up of the LED subarray supplied by the power source, adjusted intermittently during operation of the LED subarray, or scheduled continuously.

2. the power provided by each of the at least two power sources is adjusted from a calibration performed prior to installation; 2. The power supply system for an LED pixel array of claim 1, wherein the controller is configured to independently control the at least two power supplies.

3. 3. The power supply system for an LED pixel array of claim 2, wherein the controller is configured to control the power provided by each of the at least two power supplies to regulate the power at a time upon power-up of the LED sub-array powered by the power supplies.

4. 3. The power supply system for an LED pixel array of claim 2, wherein the controller is configured to control the power provided by each of the at least two power sources to adjust the power intermittently during operation of the LED sub-array.

5. 3. The power supply system for an LED pixel array of claim 2, wherein the controller is configured to control the power provided by each of the at least two power sources to adjust the power continuously based on a schedule.

6. 6. The power supply system for an LED pixel array of claim 1, wherein, for each power supply of the at least two power supplies, the controller is configured to control the power provided by the power supply to supply a voltage based on a maximum forward voltage for the LEDs in the LED sub-array.

7. 6. The power supply system for an LED pixel array of claim 1, wherein, for each power supply of the at least two power supplies, the controller is configured to control the power provided by the power supply to supply a voltage based on an average forward voltage for the LEDs in the LED sub-array.

8. 8. The power supply system for an LED pixel array of claim 1, wherein the at least two power sources include a plurality of ports, a first port of the plurality of ports providing an independent positive power, and a second port of the plurality of ports providing a ground voltage common to all sub-arrays in the LED pixel array.

9. 9. The power supply system for an LED pixel array according to claim 1, wherein each of the at least two power supplies is connectable in parallel to a respective sub-array of the LED pixel array.

10. 1. A micro light emitting diode (LED) pixel array system, comprising: a plurality of micro LED pixels organized into an independently powered LED pixel sub-array, each of the micro LED pixels including a current source and a micro LED; at least two power sources, each connected to one of the LED pixel subarrays and configured to provide adjustable power to the LED pixel subarray; A controller for the at least two power sources, the controller comprising: measuring an electrical characteristic of each micro LED pixel of each LED pixel sub-array of the LED pixel sub-arrays; and a controller configured to adjust power provided by the at least two power sources based on the measured electrical characteristics, and for each power source of the at least two power sources, the power provided by the power source is either set once upon power-up of the LED pixel sub-array supplied by the power source, adjusted intermittently during operation of the LED pixel sub-array, or scheduled continuously.

11. 11. The micro LED pixel array system of claim 10, wherein each pixel of the plurality of micro LED pixels is independently addressable.

12. the power provided by each of the at least two power sources is adjusted from a calibration performed prior to installation; 12. The micro LED pixel array system of claim 10 or 11, wherein the controller is configured to independently control the at least two power sources.

13. 13. The micro LED pixel array system of claim 10, wherein the controller is configured to control the power provided by each of the at least two power sources to regulate the power at a time upon power-up of the LED pixel sub-array powered by the power sources.

14. 13. The micro LED pixel array system of claim 10, wherein the controller is configured to control the power provided by each of the at least two power sources to adjust the power intermittently during operation of the LED pixel sub-array.

15. 13. The micro LED pixel array system of claim 10, wherein the controller is configured to control the power provided by each of the at least two power sources to adjust the power continuously based on a schedule.

16. the measured electrical characteristics include forward voltages of pixels of the LED pixel sub-array; 16. The micro LED pixel array system of claim 10, wherein for each power supply of the at least two power supplies, the controller is configured to control the power provided by the power supply to supply a voltage based on a maximum forward voltage for the micro LEDs in the LED pixel sub-array.

17. the measured electrical characteristics include forward voltages of pixels of the LED pixel sub-array; 16. The micro LED pixel array system of claim 10, wherein for each power supply of the at least two power supplies, the controller is configured to control the power provided by the power supply to supply a voltage based on an average forward voltage for the micro LEDs in the LED pixel sub-array.

18. 18. The micro LED pixel array system of claim 10, wherein the at least two power sources provide independent positive power supply voltages and a shared common ground voltage.

19. 19. The micro LED pixel array system of claim 10, wherein the at least two power sources are electrically connected in parallel with each other, and each of the at least two power sources is electrically connected to a respective sub-array within the LED pixel sub-array.

20. 1. A method for controlling a light emitting diode (LED) array, comprising: providing a plurality of micro LED pixels organized to include at least two independently powered micro LED pixel sub-arrays, each of the micro LED pixel sub-arrays including a separate micro LED pixel of the plurality of micro LED pixels, each of the micro LED pixels including a current source and a micro LED; providing power to each micro LED pixel sub-array from a respective dedicated power source based on forward voltage shift matching; measuring power usage and forward voltage shift for at least a portion of the micro LED pixels of each of the micro LED pixel sub-arrays; and dynamically adjusting power supplied to the at least two independently powered micro LED pixel sub-arrays based on the measured power and the forward voltage shift, wherein the power is adjusted based on one of an average or a maximum forward voltage for the micro LEDs in the micro LED pixel sub-arrays.

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