Intelligent flicker-free PWM generation for multi-channel LED drivers

Abstract

Embodiments of the present disclosure relate to intelligent flicker-free PWM generation for multi-channel LED drivers. This disclosure describes techniques for driving multiple light-emitting diodes (LEDs) arranged in parallel using PWM (pulse width modulation) dimming. The disclosed techniques describe the generation and application of a fixed phase shift mapping to a driver matrix based on pixel position. Each pixel corresponds to an LED light source. In the fixed phase shift mapping, each pixel will have a predefined phase shift calculated to cause a determined change in the on-time of geometrically adjacent pixels to spread the current demand over time during PWM dimming.

Description

Technical Field

[0001] The present disclosure relates to circuits for powering and controlling an array of light emitting diodes. Background Art

[0002] Driver circuits can be used to control the voltage, current, or power at a load. For example, a light-emitting diode (LED) driver can control the power provided to a string of LEDs. Some drivers may include a DC-DC power converter, such as a buck-boost, step-down, boost, or other DC-DC converter. Such a DC-DC power converter can be used to control and potentially vary the power at the load based on the characteristics of the load. A DC-DC power converter can be used in an LED driver to regulate the current through the LED string.

[0003] Some LED lighting circuits may include many individually controllable LEDs arranged in a two-dimensional matrix, similar to the arrangement of LEDs in LED display monitors. Individually controllable LEDs in an LED matrix can be controlled to provide advanced lighting effects, for example in vehicle headlight systems. Some headlight systems may have multiple and pixelated light sources, allowing individual brightness control for each pixel or group of pixels. Individual pixel control can enable new lighting functions, such as glare-free high-beam systems, ADB (adaptive high-beam), and symbol projection. To provide such functionality, dynamic high-resolution light that is projected onto the driver's entire field of view can be used. Advanced lighting effects associated with vehicle operation can be used to improve the driving experience and increase vehicle safety. These functions can use matrix beams with a large number of LEDs and fine pixel pitch. Summary of the Invention

[0004] In general, this disclosure describes techniques for driving multiple light-emitting diodes (LEDs) arranged in parallel using pulse modulation dimming. The disclosed techniques describe the generation and application of a fixed phase shift mapping for a driver matrix based on pixel position. Each pixel corresponds to an LED light source. In the fixed phase shift mapping, each pixel will have a predefined phase shift calculated to cause a determined change in the on-time of geometrically adjacent pixels to spread the current demand over time during PWM dimming.

[0005] In one example, the present disclosure relates to a system comprising: a controller unit configured to output a signal comprising a light pattern; an LED unit comprising a plurality of pixel driver circuits, wherein each pixel driver circuit is associated with a corresponding pixel in a pixel matrix; and an LED control circuit device comprising: an input interface configured to receive a signal comprising a light pattern, wherein the light pattern comprises a pixel matrix duty cycle map having a plurality of first duty cycle values; and a processing circuit device configured to apply a fixed phase shift map to each first duty cycle value of the plurality of first duty cycle values. Each entry in the fixed phase shift map is associated with each corresponding pixel in the LED pixel matrix according to a geometric position of each corresponding pixel in the LED pixel matrix. The processing circuit device is further configured to generate a pixel drive matrix comprising a plurality of shifted duty cycle values, wherein each shifted duty cycle value is based on each first duty cycle value and the fixed phase shift map, and output the pixel drive matrix to the plurality of pixel driver circuits.

[0006] In another example, a circuit includes an input interface configured to receive a signal including a light pattern, wherein the light pattern includes a pixel matrix duty cycle map for an LED pixel matrix, the pixel matrix duty cycle map including a plurality of first duty cycle values; a plurality of pixel driver circuits, wherein each pixel driver circuit is associated with a corresponding pixel in the pixel matrix; and a processing circuit device configured to apply a fixed phase shift map to the received pixel matrix duty cycle map. Each entry in the fixed phase shift map is associated with each corresponding pixel in the LED pixel matrix based on a geometric position of each corresponding pixel in the LED pixel matrix. The processing circuit device is further configured to generate a pixel drive matrix including a plurality of shifted duty cycle values, wherein each shifted duty cycle value is based on each first duty cycle value and the fixed phase shift map, and output the pixel drive matrix to the plurality of pixel driver circuits.

[0007] In another example, the present disclosure relates to a method comprising: receiving, by an LED control circuit device, a light pattern, wherein the light pattern comprises a pixel matrix duty cycle map, the pixel matrix duty cycle map comprising a plurality of first duty cycle values; and applying, by the LED control circuit device, a fixed phase shift map to the pixel matrix duty cycle map. Each entry in the fixed phase shift map is associated with a corresponding pixel in an LED pixel matrix, and wherein each corresponding pixel is associated with a corresponding pixel driver circuit. The method further comprises generating, by the LED control circuit device, a pixel drive matrix comprising a plurality of shifted duty cycle values, wherein each shifted duty cycle value is based on each of the first duty cycle values and the applied fixed phase shift map.

[0008] The details of one or more examples of the present disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the present disclosure will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a block diagram illustrating an example system including circuitry for driving a plurality of LEDs, in accordance with one or more techniques of this disclosure.

[0010] Figure 2A This is a conceptual illustration of a road curving to the left.

[0011] Figure 2B The output light pattern is shown to conform to Figure 2A Conceptual illustration of a top view of a vehicle on a road that curves to the left.

[0012] Figure 2C is a conceptual diagram illustrating example light patterns that may be output by a pixel matrix including a plurality of LED pixels.

[0013] Figure 2D It is shown that a Figure 2B and Figure 2C Table of example pixel matrix duty cycle mappings for multiple duty cycle values for the light pattern shown in .

[0014] Figure 3 is a table illustrating example fixed phase shift mappings based on pixel geometry of a pixel matrix, in accordance with one or more techniques of this disclosure.

[0015] Figure 4 is a timing diagram showing the voltage offset caused by a PWM scheme without additional phase shift.

[0016] Figure 5A and Figure 5B is a timing diagram illustrating a technique for applying a fixed phase shift, in accordance with one or more techniques of this disclosure.

[0017] Figure 6A and Figure 6B is a timing diagram illustrating the effect on current over time based on applying a fixed phase shift map, in accordance with one or more techniques of this disclosure.

[0018] Figure 7 is a flow chart illustrating example operation of an LED driver circuit arrangement, in accordance with one or more techniques of this disclosure. DETAILED DESCRIPTION

[0019] This disclosure describes techniques for driving multiple light-emitting diodes (LEDs) arranged in parallel using pulse modulation dimming. The disclosed techniques describe the calculation of a fixed phase shift mapping for a driver matrix based on pixel position. Each pixel corresponds to an LED light source. In the fixed phase shift mapping technique, each pixel can have a predefined phase shift that is calculated to cause a determined change in the on-time of geometrically adjacent pixels to avoid large current load steps by spreading the current demand over time during pulse modulation dimming.

[0020] Some LED lighting applications may include a large number of pixels and the spatial continuity characteristics of the projected image, which may result in adjacent pixels generally having similar duty cycles. An example application area may include modern vehicle LED front lighting, which may have multiple and pixelated light sources, allowing individual brightness control of each pixel or group of pixels. In these or other applications, a large number of parallel LEDs may result in large load steps in current demand when a large number of pixels are turned on or off at the same time. A DC-DC power converter may power a driver matrix for the pixelated light sources. Large load steps in current may result in high ripple voltage, output voltage drop, electromagnetic interference (EMI) caused by the fast slew rate of the load step, and increased cost of providing a DC-DC converter (which is capable of providing such large load steps in current). The technology disclosed herein spreads the current demand over time to reduce large load steps, and in addition may avoid flicker and other undesirable effects that may be caused by other techniques for spreading the current demand over time.

[0021] Figure 1 is a block diagram illustrating an example system including circuitry for driving a plurality of LEDs according to one or more techniques of this disclosure. The plurality of LEDs may be arranged in a pixel matrix and configured to project a selected image formed by a pattern of light. The system 100 may be configured to receive an image from a controller unit and adjust the amount of power provided to each LED pixel in the pixel matrix so that the pixel matrix projects the desired light pattern. The system 100 may adjust the amount of power to each LED pixel by performing PWM dimming on each LED pixel, thereby controlling its brightness. A longer duty cycle for one LED pixel may produce a brighter output for that LED pixel compared to a shorter duty cycle that produces a less bright output.

[0022] exist Figure 1In some examples, the system 100 includes a controller unit (such as a body control unit BCM 150) that is connected to the input of the LED unit 101. The LED unit 101 receives power from the power supply VDDP 130 via a connector 132 and is connected to the system ground via a connector 136. The LED unit 101 includes an LED control circuit device 102 and an LED driver unit 140. In some examples, the LED unit 101 is a single circuit that includes the LED control circuit device 102 and the LED driver unit 140. In some examples, the LED unit 101 can be a single integrated circuit (IC) having the LED control circuit device 102 and the LED driver unit 140, as well as connectors 132 and 136, and a video interface 106 to couple to other components of the system 100. In other examples, the LED control circuit device 102 and the LED driver unit 140 can be separate circuits that include separate integrated circuits that, when connected together, can form the LED unit 101.

[0023] In addition, despite Figure 1 The example of FIG. 1 depicts various blocks within the LED control circuit device 102, such as the signal processing 104 and the pixel signal generator 112, but depicting these blocks is for convenience and to simplify the explanation of the disclosed techniques. However, in other examples, the functions of the LED control circuit device 102 may be combined or separated into Figure 1 Other blocks not shown in FIG. Furthermore, to simplify the description, the present disclosure may focus on pulse width modulation (PWM) as a modulation scheme for controlling LED dimming. However, any pulse modulation technique, such as pulse frequency modulation (PFM) and pulse density modulation (PDM), may be used with the techniques of the present disclosure.

[0024] The BCM 150 is one example of a controller unit in a vehicle that can be configured to output signals including light patterns to the video interface 106. In other examples, the vehicle can have a controller unit separate from the body control unit to provide light patterns to the LED units 101. In other systems, such as buildings, which can include emergency lighting, display lighting, and other lighting systems, the controller unit that can provide lighting patterns to the LED units 101 can be implemented as a central building controller and communicate with the LED units 101 via wired or wireless signals.

[0025] exist Figure 1In the example of , the LED driver unit 140 can be configured to be connected to the LED matrix 142 via the connector 134. In the present disclosure, the LED matrix 142 can also be referred to as a pixel matrix or an LED pixel matrix. Each pixel in the LED matrix 142 can be implemented by an LED. The LED driver unit 140 can include a plurality of pixel driver circuits, wherein each pixel driver circuit is associated with a corresponding pixel in the pixel matrix. Figure 1 In the example of FIG1 , each pixel driver circuit of the plurality of pixel driver circuits is implemented by a switch 144, a current driver circuit 146, and one or more connectors 134. In other examples, the pixel driver circuits in the LED driver unit 140 may include more or fewer components, such as temperature sensors, current or voltage sensors, protection circuits such as for overvoltage and overcurrent protection, and Figure 1 In some examples, the connector 134 can be configured to electrically and mechanically connect to the LED matrix 142. In this regard, the LED unit 101 can be configured to operate a variety of different types of LED matrices 142, which can provide the advantage of a single model of LED unit 101 that can be used in a variety of different applications and configured to work with a specific load driving application.

[0026] The system 100 may further include an LED control circuit device 102 including an input interface at the video interface 106 configured to receive a signal including a light pattern. The light pattern may include a pixel matrix duty cycle map having a plurality of duty cycle values that, when applied to the LED matrix 142, output a desired light pattern. The LED control circuit device 102 may include one or more sets of processing circuit devices, including a signal processing circuit device 104, a PWM engine 110, and one or more processors 120.

[0027] The processor 120 can be operably coupled to the memory 122. In some examples, the processor 120 can receive input signals and send control signals to perform operations of the LEDs, such as communicating with the BCM 150. In other examples, the LED control circuitry 102 can include only the signal processing 104 and the PWM 110, without the processor 120.

[0028] Examples of processing circuitry (such as the processor 120, signal processing 104, rising edge calculator 114, and pixel signal generator 112 in the LED control circuitry 102) may include any one or more of the following: a microcontroller (MCU) (e.g., a computer on a single integrated circuit containing a processor core, memory, and programmable input / output peripherals), a microprocessor (μP) (e.g., a central processing unit (CPU) on a single integrated circuit (IC)), a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a system on a chip (SoC), or equivalent discrete or integrated logic circuitry. The processor may be an integrated circuit, i.e., an integrated processing circuitry, and the integrated processing circuitry may be implemented as fixed hardware processing circuitry, programmable processing circuitry, and / or a combination of both fixed and programmable processing circuitry. Therefore, as used herein, the terms "processing circuitry," "processor," or "controller" may refer to any one or more of the above structures or any other structure operable to perform the techniques described herein.

[0029] Examples of memory 122 may include any type of computer-readable storage medium. Computer-readable storage media may include random access memory (RAM) (e.g., SRAM, DRAM, etc.), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), flash memory, and similar devices. In some examples, the computer-readable storage medium may store instructions that cause the processing circuitry to perform the functions described herein. In some examples, the computer-readable storage medium may store data, such as configuration information, temporary values, and other types of data used to perform the functions of the present disclosure.

[0030] The processing circuitry of LED control circuitry 102 can be configured to apply a fixed phase-shift mapping to the pixel matrix duty cycle map received from BCM 150 at video interface 106 . The fixed phase-shift mapping can shift each duty cycle value in the pixel matrix duty cycle map. This shift in duty cycle can change the start time of the duty cycle for a particular pixel, but does not change the duty cycle length and, therefore, the pixel brightness. As described above, in systems where all pixels of the pixel matrix are simultaneously on, power supply VDDP 130 may be required to provide a large current surge at the beginning of each PWM cycle. Providing a large current surge can cause a voltage drop at the beginning of each PWM cycle. In some examples, the voltage drop on the DC / DC output may be caused by limited bandwidth, preventing the power supply from returning to the target regulation voltage in time before the next PWM cycle. To avoid voltage drop, VDDP 130 may be sized to minimize the voltage drop, which may require a large and expensive power supply to manage the rapid current transients, as well as wiring and connectors sized to handle the current surge. Other issues caused by large load steps in each PWM cycle can include high ripple voltage caused by parasitic resistance and inductance of the wiring harness connecting the printed circuit board (PCB), or by high equivalent series resistance (ESR) of the filter capacitors. In some examples, transients can also cause electromagnetic emissions due to the fast slew rate of the load step, leading to electromagnetic compatibility (EMC) issues with other parts of the system 100. Applying the fixed phase shift mapping of the present disclosure to the received pixel matrix duty cycle mapping that defines the light pattern can spread the on-time of the pixels over time to avoid large load steps at a single time.

[0031] According to the technology of the present disclosure, each entry in the fixed phase shift map can be associated with each corresponding pixel in the LED pixel matrix based on the geometric position of each corresponding pixel in the LED pixel matrix. Due to the large number of pixels in the pixel matrix and the spatial continuity characteristics of the projected image, the technology of the present disclosure generates a fixed phase shift map based on geometric position. In the present disclosure, spatial continuity refers to the characteristic that adjacent pixels generally have similar duty cycles. In some examples, a small number of LEDs describing the boundary of the projected shape may not have similar duty cycles, but other than the image boundary, adjacent pixels may have similar brightness and therefore similar duty cycle values.

[0032] The PWM engine 110 can apply the phase shift map to the received pixel matrix duty cycle map to generate the pixel drive matrix 108. The pixel drive matrix 108 can include a plurality of shifted duty cycle values. Each shifted duty cycle value can be based on each received duty cycle value shifted by a value in the fixed phase shift map. In other words, each shifted duty cycle value in the pixel drive matrix 108 is based on the map received by the PWM engine 110 and each duty cycle value in the fixed phase shift map. The PWM engine 110 can output the pixel drive matrix 108 to a plurality of pixel driver circuits of the LED driver unit 140. In turn, the LED driver unit 140 can open and close switches 144 as directed by the pixel drive matrix 108 so that each LED pixel in the LED matrix 142 outputs a desired brightness while spreading the on-time of each duty cycle over the PWM period to avoid large load steps. In other words, the plurality of pixel driver circuits of the LED driver unit 140 having the plurality of switches 144 are configured such that corresponding switches are electrically coupled to corresponding pixels of the pixel matrix (LED matrix 142), and the luminance output of each corresponding pixel of the pixel matrix is based on the shifted duty cycle value associated with each pixel defined by the pixel drive matrix 108. As described above, the functionality of the PWM engine 110 can be applied to other pulse modulation schemes and is not limited to pulse width modulation.

[0033] The phase shift mapping of the present disclosure can be based on the arrangement of pixels in the pixel matrix. In some examples, the phase shift map can be generated once and stored in the LED control circuit device 102, for example, during the manufacturing process. In other examples, the phase shift map can be fixed based on the arrangement of pixels, and the phase shift map can be dynamically corrected for each PWM cycle. In some examples, the phase shift map can be stored in the memory 122 and applied to the received image pattern through communication between the processor 120 and the PWM engine 110. In other examples, the phase shift map can be stored in the PWM engine 110 (such as in the rising edge calculator 114 or the pixel signal generator 112) and applied by the processing circuit device of either the rising edge calculator 114 or the pixel signal generator 112 to the received duty cycle entries of the pixel matrix duty cycle map that defines the light pattern.

[0034] In some examples, the LED control circuitry 102 can generate a fixed phase shift map for a particular pixel matrix based on, for example, the number of rows and columns of pixels, the number of pixel segments within the pixel matrix, and other characteristics of the pixel matrix. In other examples, some other processing circuitry within the system 100 or during manufacturing can generate the fixed phase shift map. One example technique for generating a fixed phase shift map can include generating the fixed phase shift map by calculating a phase shift for each pixel geometric location in the LED pixel matrix according to the following formula:

[0035]

[0036] In equation [1], for each pixel geometric position (x, y):

[0037] x indicates the row of pixel geometry,

[0038] y indicates the column of the pixel's geometric position,

[0039] F1(x) comprises a first function based on the pixel row position,

[0040] F2(y) comprises a second function based on pixel column position, and

[0041] F3[…] comprises a third function, such as a square root, a modulus, a sum, or some other function.

[0042] An example technique for generating a phase shift map that is fixed based on pixel geometry and dynamically adjusted may include generating each entry in the fixed phase shift map according to the following formula:

[0043]

[0044] In equation [2], for each pixel geometric position (x, y):

[0045] x indicates the row of pixel geometry,

[0046] y indicates the column of the pixel's geometric position,

[0047] ΔPScycle is the dynamic correction of the phase shift for each PWM cycle.

[0048] ΔPSx includes a constant phase shift change for each row,

[0049] ΔPSy includes a constant phase shift change for each column,

[0050] mod(M; N) involves computing the modulus of M divided by N.

[0051] 2 A Indicates the number of pixels in the row, and

[0052] 2 B Indicates the number of pixels in the column. Furthermore, F3[…] described above for equation [1] is the modulus, ie, mod[…] for equation [2]. In some examples, there may be no dynamic adjustment, so ΔPScycle=0.

[0053] In operation, the BCM 150 can send a signal including an image at each refresh cycle to the LED unit 101 via the video interface 106. The refresh cycle can be defined based on the characteristics of the system 100. The refresh cycle can be based on 60 Hz, 75 Hz, 144 Hz, or some other periodic interval. In some examples, the BCM 150 can repeatedly send the same image for multiple refresh cycles. For example, for a car driving on a straight road for several minutes without oncoming vehicles, the BCM 150 can repeatedly send the same image to illuminate the scene. If the car system detects an oncoming vehicle, the BCM 150 can send a different image to change the light pattern to avoid illuminating the oncoming vehicle.

[0054] In some examples, the LED control circuitry can perform additional signal processing on the received pixel matrix duty cycle map. For example, the signal processing circuitry 104 can apply one or more corrections to each of the plurality of raw duty cycle values received from the BCM 150. Example corrections can include gamma correction to account for the eye's nonlinear brightness perception, which includes a higher sensitivity to relative differences between darker tones than to relative differences between lighter tones. In some examples, the gamma correction can be implemented using a lookup table (LUT).

[0055] In some examples, signal processing circuit device 104 may also convert each raw duty cycle value in the received pixel matrix duty cycle map into a second duty cycle value, where the second duty cycle value may have a different resolution than the raw duty cycle value. For example, BCM 150 may output the raw duty cycle values based on 8-bit values, and signal processing circuit device 104 may output the matrix of higher or lower resolution duty cycle values 116 to PWM engine 110. For example, duty cycle values 116 may be output to PWM engine 110 as 10-bit values. Signal processing circuit device 104 may also include a frame buffer or other signal processing functionality.

[0056] The LED control circuit device 102 can be configured to drive the LED matrix 142 based on the same duty cycle received from the BCM 150 without corrupting or changing the duty cycle input from the video interface 106. For example, when converting the original duty cycle value from 8 bits to 6 bits or to 10 bits, the duty cycle and resulting brightness of the pixels in the LED matrix 142 can be approximately the same as the original (8-bit) value. That is, the amount of on and off time for each entry should remain approximately constant between the original duty cycle value and the value output 116 to the PWM engine 110, but the resolution can be changed, i.e., increased (10 bits) or decreased (6 bits).

[0057] The disclosed techniques may provide several advantages over other techniques for spreading the on-time of each pixel over time to avoid high load steps. For example, a center-based PWM scheme may use a method that centers all active periods (duty cycles) within a PWM period (T PWM ) to manage pixels using a drive scheme around the midpoint of the PWM. A center-based PWM scheme can avoid turning a large number of pixels on and off simultaneously, thereby producing a gradual current ramp. However, the total current is not averaged during the PWM cycle and always reaches a maximum value in the interval close to the center of each PWM. In addition, with the center-based PWM scheme, there is no control during the PWM cycle to avoid large differences between the minimum and maximum supply currents.

[0058] In other examples, such as for a multi-channel LED driver with approximately uniform load, i.e., with approximately the same typical drive current I LED Another technique for balancing the supply current for all pixels of a light pattern may include an adaptive phase-shift PWM scheme. In some examples of the adaptive phase-shift scheme, an algorithm that arranges the pixel activation delays (i.e., PWM phase shift) can result in a nearly constant and average current consumption throughout the PWM cycle for each requested light pattern. In such a scheme, the technique causes the driver to dynamically rearrange the phase shift of a single pixel for each refresh cycle with a new light pattern. The result includes activating each pixel when the previous pixel is deactivated. The adaptive phase-shift PWM scheme can produce a power supply that will output a total average supply current that corresponds to the average DC current of the light pattern being executed, multiplied by the total number of pixels in the pixel matrix and the selected drive current I LED The adaptive phase-shift PWM scheme can avoid current overshoot by extracting only the average current desired over the entire PWM cycle. By avoiding overshoot, the adaptive phase-shift PWM scheme can avoid the need for expensive, high-capacity external components of the DC / DC converter, as well as provide predictable and manageable current steps for each new light pattern refresh and improved EMC performance when compared to the high load steps (dI / dt) of other schemes. However, in some examples, the adaptive phase-shift PWM scheme may result in optically visible flickering of some pixels at lower PWM frequencies and larger phase shift variations (ΔPS).

[0059] In contrast, the fixed phase shift mapping based on pixel geometry of the present disclosure can avoid optically visible flicker because each pixel has a controlled phase shift even during dynamic adjustment (ΔPScycle≠0). Other advantages of the disclosed technique can include the ability to achieve a fixed phase shift for a given PWM period (T PWM) can approximate the average current of various commonly used light patterns. As described above, when compared to techniques requiring large load steps, fixed phase shift mapping can optimize the external components of the power supply DC / DC (e.g., VDDP 130) by reducing size, capacity, and cost. Furthermore, compared to other techniques, the disclosed techniques can involve lower computational complexity and can achieve lower power consumption for systems capable of regulating power supplies because the maximum current demand of system 100 can be close to the expected average current of the system.

[0060] The techniques of the present disclosure may also result in simplified thermal management control for system 100, since the system's junction temperature may only experience modest variations over time during a PWM cycle. Managing the duty cycle start time may result in a reduction in average current, thereby reducing current and power peaks. Peaks in power consumed by the system may result in temperature peaks, which may require complex and expensive thermal management, such as heat sinks, fans, and similar components to protect the system. However, the techniques of the present disclosure may result in reduced temperature peaks, thereby enabling the use of less expensive thermal management, as well as improved reliability due to reduced failures and fewer automatic system safety shutdowns in the event that temperature exceeds a temperature threshold. Furthermore, the techniques of the present disclosure may result in improved EMC performance, with dI / dt generally being lower, compared to other techniques.

[0061] Figure 2A This is a conceptual illustration of a road that curves to the left. A vehicle with standard headlights that don't adapt to changing conditions might illuminate most of the right side of the road, leaving the curved portion of the road in darkness.

[0062] Figure 2B The output light pattern is shown to conform to Figure 2A , a conceptual illustration of a top view of a vehicle on a road that curves to the left as shown in FIG. In contrast, a vehicle with automotive LED front lighting (which has multiple and pixelated light sources that allow individual brightness control of each pixel or control of groups of pixels) can implement light functions such as a glare-free high beam system, ADB (adaptive high beam), and symbol projection. To provide such functionality, the technology of the present disclosure can allow for the generation of dynamic, high-resolution light that is projected onto the driver's entire field of view. For example, one or more pixel matrices of LEDs on a vehicle 204 can project a light pattern 202 that illuminates the road along a curve. Figure 2A The portion of the road in the center of the road does not need to be illuminated, while the portion on the right that leaves the road does not need to be illuminated.

[0063] Figure 2C is a conceptual diagram illustrating example light patterns that may be output by a pixel matrix including a plurality of LED pixels. Figure 2CThe example of may show a light pattern from a pixel matrix, or from a group of pixels within a larger pixel matrix, which may include a bright area 206, a slightly brighter area 208, and a darker area 209. Figure 2C The light pattern of can be combined with light patterns from other pixel matrices on vehicle 204 to form light pattern 202, as described above with respect to Figure 2B As stated.

[0064] Figure 2D is a table showing an example pixel matrix duty cycle map 210 having a plurality of duty cycle values 212 that may be used to generate a pixel matrix duty cycle map 210 as shown in FIG. Figure 2B and Figure 2C The duty cycle map 210 may be sent to the LED unit 101 via the video interface 106 via the BCM 150, as described above with respect to Figure 1 The example of duty cycle map 210 may output the above Figure 2C The duty cycle map 210 may include ten columns 214 and eight rows 216 of duty cycle values 212. Each duty cycle value may correspond to a pixel of a pixel matrix of the vehicle 204 or a group of pixels of a larger pixel matrix. The duty cycle map 210 includes a 10-bit resolution PWM cycle (2 10 Around the edges of the duty cycle map 210, the duty cycle is zero or other low duty cycle values, which indicate that the duty cycle is Figure 2C The darker regions correspond to the darker regions 209 depicted in FIG. The brighter regions 206 may correspond to higher duty cycle values, such as 900 and 1020, which may cause the switches controlling the associated LED pixels to turn on for 900 or 1020 of the 1024 counts within a 10-bit PWM period.

[0065] Figure 3 is a table illustrating an example fixed phase shift map 300 based on the geometric position of pixels in a pixel matrix according to one or more techniques of this disclosure. Each entry 302 in the fixed phase shift map 300 may be associated with the LED pixel matrix ( Figure 3 (not shown in FIG) is associated with each corresponding pixel. Figure 3 In the example of FIG. 3 , the fixed phase shift map 300 has sixteen columns 306 (numbered 0 to 15) and eight rows 304 (numbered 0 to 7).

[0066] The phase shift values 302 in the fixed phase shift map 300 can be obtained by, for example, Figure 1The fixed phase shift map 300 is generated using equations [1] and [2] as described above. However, equations [1] and [2] are only one example technique for generating values for the fixed phase shift map 300. Equations [1] and [2] may be desirable for generating a fixed phase shift map for vehicle headlights. However, in other examples, such as for architectural lighting, display lighting, stage lighting, and other applications, other techniques may be needed to generate the fixed phase shift map.

[0067] In some examples, processing circuitry (e.g., processing circuitry included in PWM engine 110) may apply fixed phase shift map 300 to a pixel matrix duty cycle map received from BCM 150, as described above with respect to FIG. Figure 1 For example, the PWM engine 110 may apply a fixed phase shift map (e.g., fixed phase shift map 300) to the received pixel matrix duty cycle map (similar to the above description of the fixed phase shift map 300). Figure 2D The duty cycle map 210 described above is used to generate a pixel drive matrix, such as the one described above with respect to Figure 1 The pixel driving matrix 108. In practical applications, the fixed phase shift map and the pixel matrix duty cycle map should have the same number of rows and columns to generate a pixel driving matrix with shifted duty cycle values.

[0068] Figure 4 is a timing diagram showing the voltage offset caused by a PWM scheme without additional phase shift. Compared with the technology of the present disclosure, Figure 4 The timing diagram depicts three channels of the driver circuit, where the on-time of each pixel driven by a channel begins approximately at the same time.

[0069] exist Figure 4 In the example shown, the duty cycle for channel 0 404 and channel 2 408 is approximately 50%, or approximately 8-bit PWM period (T PWM 412). Channel 1 406 is about 30% or 85 counts. When all three channels are on, and when Channel 0 404 and Channel 2 408 are off at approximately the same time, the power supply's voltage Vdd 430 may experience a voltage transient (402) as the power supply attempts to handle a large and rapid load step (dI / dt) at the point indicated by 410. As discussed above with respect to Figure 1 As mentioned, transients can cause voltage and current ripples, which can introduce electromagnetic interference (EMI) and other undesirable effects.

[0070] Figure 5A and Figure 5B is a timing diagram illustrating a technique for applying a fixed phase shift according to one or more techniques of this disclosure. The technique applied may depend on whether the length of the phase shift plus the duty cycle is greater than or less than the PWM period (T PWM 502).

[0071] exist Figure 5A and Figure 5B In FIG. 5 , PSi 504 and PSi 506 may be the calculated phase shifts for the selected pixel geometric position. In other words, PSi 504 and PSi 506 may be corresponding entries in the fixed phase shift map associated with the corresponding pixel in the LED pixel matrix, based on the geometric position of the corresponding pixel in the LED pixel matrix. PSi 504 and PSi 506 are equivalent to entry 302 in the fixed phase shift map 300, as described above. Figure 3 In addition, PSi 504 and PSi 506 can be, for example, Figure 1 It is generated by equations [1] and [2] as described.

[0072] In addition, Figure 5A and Figure 5B In FIG. 5 , DCi 508 and DCi 510 may be the corresponding duty cycle durations for the selected pixel geometry. DCi 508 and DCi 510 are equivalent to the duty cycle value 212 in the duty cycle map 210, as described above. Figure 2D In addition, as mentioned above about Figure 1 As described above, DCi 508 and DCi 510 may be corrected, for example, by gamma correction and converted to a higher resolution (eg, 8 bits to 10 bits) by the signal processing circuit device 104 .

[0073] Figure 5A Depicts applying a fixed phase shift map to a pixel matrix duty cycle map, where for corresponding duty cycle values, (PSi+DCi) <T PWM In response to determining (PSi+DCi) <T PWM , Figure 1 The LED control circuit device 102 depicted in FIG can phase shift PSi 504 to a corresponding duty cycle value DCi 508 to produce a corresponding shifted duty cycle value. Figure 1 As described above, the corresponding shifted duty cycle value can be output to the LED driver unit 140 as the pixel driving matrix 108.

[0074] Figure 5A Depicts applying a fixed phase shift mapping to the pixel matrix duty cycle, where (PSi 506 + DCi 510) > T for the corresponding duty cycle value. PWM 502. In response to (PSi+DCi)>T PWM , the LED control circuit device 102 can apply a phase shift to the corresponding duty cycle value of the received image by applying the phase shift in two segments. The LED control circuit device can apply the phase shift to the first segment 512 of the duty cycle value, where the first segment 512 is: T PWM502-PSi506. The LED control circuit device can apply a zero phase shift to a second segment 514 of duty cycle values, wherein the second segment includes: DCi 510-(T PWM 502-PSi 506). The two segments 512 and 514 of corresponding shifted duty cycle values can be output to the LED driver unit 140 as entries in the pixel drive matrix. In this way, the disclosed techniques can apply phase shifting to level the current demand within a PWM cycle without corrupting or changing the duty cycle of each pixel of the received image.

[0075] Figure 6A and Figure 6B is a timing diagram illustrating the effect on current over time based on applying a fixed phase shift map, in accordance with one or more techniques of this disclosure. Figure 6A and Figure 6B Depicts a PWM cycle (T PWM ) current, as mentioned above Figure 4 As stated.

[0076] Figure 6A The example of FIG shows an example of the resulting supply current for a matrix segment considering a 64 x 64 LED driver located in the center right position of a larger LED pixel matrix on a vehicle. Figure 6A and Figure 6B In the example of , the larger pixel matrix on the vehicle is in high resolution high beam headlight mode. Figure 6A and Figure 6B In the example of a 10-bit PWM cycle, the Vddpx supply current 604 shows some ripple over the PWM cycle 608, but no large current offset (dI / dt).

[0077] Figure 6B The example of FIG shows an example of the resulting supply current for a matrix segment of a 64x64 LED driver located in the right position of a larger LED pixel matrix on the same vehicle. In the high-beam headlight mode, the right matrix segment can output a portion of the darker area of the light pattern, similar to the above description of Figure 2C The darker region 209 depicted. The Vddpx supply current 610 also does not include larger current excursions, such as at the beginning of the PWM cycle 612, nor in the middle, as can be seen in a center-based PWM scheme. Figure 6A Vddpx supply current 610 also exhibits a lower magnitude as clock counts 602 through PWM period 612 when compared to Vddpx supply current 604 depicted in FIG.

[0078] Figure 7is a flow chart illustrating an example operation of an LED driver circuit according to one or more techniques of this disclosure. Figure 1 To describe Figure 7 of blocks.

[0079] The processing circuitry may generate a fixed phase shift map (90) based on the geometric position of each pixel in the pixel matrix. In some examples, such as for vehicle headlight applications, the processing circuitry may be used in a manufacturing setting to generate a fixed phase shift map, such as described above with respect to FIG. Figure 3 Each entry in the fixed phase shift map is based on a phase shift associated with each pixel geometric position, for example, according to the above description of the fixed phase shift map 300. Figure 1 [1] and [2] described above. In other examples, such as building lighting, the processing circuitry may generate a fixed phase shift map based in part on the type of light pattern expected and the size and arrangement of the pixel matrix. In other examples, the processing circuitry within LED control circuitry 102 (such as PWM engine 110 or processor 120) may generate the pixel matrix. For example, in Figure 1 In the example of , the fixed phase shift map can be stored in the memory 122.

[0080] The LED control circuit device 102 can receive a light pattern, for example, from the BCM 150 via the video interface 106. The signal from the BCM 150 can include a light pattern defined by a pixel matrix duty cycle map, the pixel matrix duty cycle map including a plurality of duty cycle values 116 (92). In some examples, the duty cycle values in the pixel matrix duty cycle map can first be corrected, for example, by gamma correction, before being sent to the PWM engine 110. In addition to correction, in some examples, the received pixel matrix duty cycle map can be converted to a different resolution. Figure 1 In the example of FIG. 5 , the signal processing 104 may perform any corrections and conversions before the PWM engine 110 receives the pixel matrix duty cycle map.

[0081] The PWM engine 110 may apply a fixed phase shift map to the pixel matrix duty cycle map (94). Figure 1 In the example of , the PWM engine 110 may apply a fixed phase shift map to the corrected and converted duty cycle values in the pixel matrix duty cycle map received from the BCM 150. Figure 1 and Figure 3 As described above, each entry 302 in the fixed phase shift map can be associated with a corresponding pixel in the LED pixel matrix. In addition, each corresponding pixel is associated with a corresponding pixel driver circuit, such as described above with respect to Figure 1 The pixel driver circuit of the LED driver unit 140 is described.

[0082] The PWM engine 110 of the LED control circuit device 102 can generate a pixel drive matrix 108, which can include a plurality of shifted duty cycle values (96). Each shifted duty cycle value pixel drive matrix 108 can be based on each corrected and converted duty cycle 116 value and the applied fixed phase shift map 300. Even without the LED matrix 142, the technology of the present disclosure can also be applied Figure 1 In other words, regardless of whether the driver circuit of the LED driver unit 140 is connected to the LED matrix 142, the pixel driving matrix 108 can cause the switch 144 to open and close with the phase-shift timing of the present disclosure.

[0083] In one or more examples, the above functions can be implemented in hardware, software, firmware, or any combination thereof. For example, Figure 1 The various components of the PWM engine 110, signal processing circuitry 104, and processor 120 may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, these functions may be stored on a tangible computer-readable storage medium (such as memory 122) and executed by a processor or hardware-based processing unit.

[0084] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Thus, as used herein, the terms "processor" and "processing circuitry" may refer to, for example, any of the aforementioned structures or any other structure suitable for implementing the techniques described herein. Furthermore, these techniques may be fully implemented in one or more circuits or logic elements.

[0085] The techniques of this disclosure can be implemented in a variety of devices or apparatuses, including wireless handsets, ICs, or a set of ICs (e.g., a chipset). Various components, modules, or units are described in this disclosure to emphasize functional aspects of devices configured to perform the disclosed techniques, but they do not necessarily need to be implemented by different hardware units. Instead, as described above, the various units can be combined in hardware units or provided by a collection of interoperable hardware units including one or more processors described.

[0086] The technology of this disclosure can also be described in the following examples.

[0087] Example 1. A method comprising: receiving, by light emitting diode (LED) control circuitry, a light pattern, wherein the light pattern comprises a pixel matrix duty cycle map comprising a plurality of first duty cycle values; and applying, by the LED control circuitry, a fixed phase shift map to the pixel matrix duty cycle map. Each entry in the fixed phase shift map is associated with a corresponding pixel in an LED pixel matrix, and wherein each corresponding pixel is associated with a corresponding pixel driver circuit. The method further comprises: generating, by the LED control circuitry, a pixel drive matrix comprising a plurality of shifted duty cycle values, wherein each shifted duty cycle value is based on each first duty cycle value and the applied fixed phase shift map.

[0088] Example 2. The method of Example 1, further comprising generating a fixed phase shift map by calculating a phase shift for each pixel geometric position in the LED pixel matrix according to the following equation:

[0089] Phase_Shift x，y =F3[F1(x)+F2(y)]

[0090] Where for each pixel geometric position (x, y):

[0091] x indicates the row of pixel geometry,

[0092] y indicates the column of the pixel's geometric position,

[0093] F1(x) comprises a first function based on the pixel row position,

[0094] F2(y) comprises a second function based on pixel column position, and

[0095] F3[…] includes the third function.

[0096] Example 3. The method of any combination of Examples 1-2, wherein generating the fixed phase shift map comprises calculating the phase shift for each pixel geometric position according to the following equation:

[0097]

[0098] Where for each pixel geometric position (x, y):

[0099] ΔPScycle is the dynamic correction of the phase shift for each PWM cycle...

[0100] ΔPSx indicates the constant phase shift change for each row,

[0101] ΔPSy indicates the constant phase shift change for each column,

[0102] mod(M, N) includes the modulus of M divided by N,

[0103] 2 A Indicates the number of pixels in the row, and

[0104] 2 B Indicates the number of pixels in the column.

[0105] Example 4. The method of any combination of Examples 1 to 3, wherein ΔPScycle=0.

[0106] Example 5. The method of any combination of Examples 1 to 4, wherein the pixel matrix duty cycle mapping is based on a pulse width modulation (PWM) period (T PWM ).

[0107] Example 6. The method of any combination of Examples 1 to 5, wherein applying the fixed phase shift mapping to the pixel matrix duty cycle mapping comprises: for each corresponding first duty cycle value, in response to (PSi+DCi) <T PWM , applying the phase shift to the corresponding first duty cycle value to produce a corresponding shifted duty cycle value, where: PSi comprises the calculated phase shift for the selected pixel geometric position, and DCi comprises the first duty cycle duration for the selected pixel geometric position.

[0108] Example 7. The method of any combination of Examples 1 to 6, wherein applying the fixed phase shift map to the pixel matrix duty cycle map comprises: for each corresponding first duty cycle value, in response to (PSi+DCi)>T PWM , where PSi is the calculated phase shift for the selected pixel geometry and DCi is the first duty cycle duration for the selected pixel geometry: the phase shift is applied to a first segment of the first duty cycle value, where the first segment includes T PWM -PSi, and applying a zero phase shift to a second segment of the first duty cycle value, wherein the second segment comprises: DCi-(T PWM -PSi).

[0109] Example 8. The method of any combination of Examples 1 to 7, wherein the LED control circuitry receives the light pattern at each refresh cycle.

[0110] Example 9. A method according to any combination of Examples 1 to 8, further comprising: processing each raw duty cycle value in the received pixel matrix duty cycle map by an LED control circuit device, wherein the processing includes adding one or more corrections to each raw duty cycle value in the multiple raw duty cycle values.

[0111] Example 10. A method according to any combination of Examples 1 to 9, further comprising: converting (104) each original duty cycle value in the received pixel matrix duty cycle map to a second duty cycle value, wherein the second duty cycle value has a higher resolution than the original duty cycle value.

[0112] Example 11. A circuit comprising: an input interface configured to receive a signal comprising a light pattern, wherein the light pattern comprises a pixel matrix duty cycle map for an LED pixel matrix, the pixel matrix duty cycle map comprising a plurality of first duty cycle values; a plurality of pixel driver circuits, wherein each pixel driver circuit is associated with a corresponding pixel in the pixel matrix; a processing circuit device configured to: apply a fixed phase shift map to the received pixel matrix duty cycle map. Each entry in the fixed phase shift map is associated with each corresponding pixel in the LED pixel matrix according to a geometric position of each corresponding pixel in the LED pixel matrix. The processing circuit device is further configured to generate a pixel drive matrix comprising a plurality of shifted duty cycle values, wherein each shifted duty cycle value is based on each first duty cycle value and the fixed phase shift map; and output (108) the pixel drive matrix to the plurality of pixel driver circuits.

[0113] Example 12. The circuit of Example 11, wherein each entry in the fixed phase shift map is based on a phase shift associated with each pixel geometric position according to the following equation:

[0114]

[0115] Where for each pixel geometric position (x, y):

[0116] x indicates the row of pixel geometry,

[0117] y indicates the column of the pixel's geometric position,

[0118] ΔPScycle is the dynamic correction of the phase shift for each PWM cycle.

[0119] ΔPSx indicates the constant phase shift change for each row,

[0120] ΔPSy indicates the constant phase shift change for each column,

[0121] mod(M, N) includes the modulus of M divided by N,

[0122] 2 A Indicates the number of pixels in the row, and

[0123] 2 B Indicates the number of pixels in the column.

[0124] Example 13. The circuit of any combination of Examples 11-12, wherein ΔPScycle=0.

[0125] Example 14. The circuit of any combination of Examples 11 to 14, wherein the pixel matrix duty cycle mapping is based on a pulse width modulation (PWM) period (T PWM ).

[0126] Example 15. The circuit of any combination of Examples 11 to 15, wherein applying the fixed phase shift map to the pixel matrix duty cycle map comprises: for each corresponding first duty cycle value, in response to (PSi+DCi) <T PWM , applying the phase shift to the corresponding first duty cycle value to produce a corresponding shifted duty cycle value, where: PSi comprises the calculated phase shift for the selected pixel geometric position, and DCi comprises the first duty cycle duration for the selected pixel geometric position.

[0127] Example 16. The circuit of any combination of Examples 11 to 15, wherein applying the fixed phase shift map to the pixel matrix duty cycle map comprises: for each corresponding first duty cycle value, in response to (PSi+DCi)>T PWM , where PSi is the calculated phase shift for the selected pixel geometry and DCi is the corresponding first duty cycle duration for the selected pixel geometry: the phase shift is applied to a first portion of the first duty cycle value, where the first portion includes T PWM -PSi, and applying a zero phase shift to a second portion of the first duty cycle value, wherein the second portion comprises: DCi-(T PWM -PSi).

[0128] Example 17. The circuit of any combination of Examples 11 to 16, further comprising: a signal processing circuit device (104) configured to: add one or more corrections to each first duty cycle value, and convert each first duty cycle value to a second duty cycle value, wherein the second duty cycle value has a higher resolution than the first duty cycle value.

[0129] Example 18. A system comprising: a controller unit (BCM 150) configured to output a signal comprising a light pattern; a light emitting diode (LED) unit comprising a plurality of pixel driver circuits, wherein each pixel driver circuit is associated with a corresponding pixel in a pixel matrix; and an LED control circuit device comprising: an input interface configured to receive the signal comprising the light pattern, wherein the light pattern comprises a pixel matrix duty cycle map having a plurality of first duty cycle values; and a processing circuit device configured to: apply a fixed phase shift map to each first duty cycle value of the plurality of first duty cycle values. Each entry in the fixed phase shift map is associated with each corresponding pixel in the LED pixel matrix according to a geometric position of each corresponding pixel in the LED pixel matrix. The processing circuit device is further configured to generate a pixel drive matrix comprising a plurality of shifted duty cycle values, wherein each shifted duty cycle value is based on each first duty cycle value and the fixed phase shift map; and output the pixel drive matrix to the plurality of pixel driver circuits.

[0130] Example 19. The system of Example 18, wherein each entry in the fixed phase shift map is based on a phase shift associated with each pixel geometric position according to the following equation:

[0131]

[0132] Where for each pixel geometric position (x, y):

[0133] x indicates the row of pixel geometry,

[0134] y indicates the column of the pixel's geometric position,

[0135] ΔPScycle is the dynamic correction of the phase shift for each PWM cycle.

[0136] ΔPSx includes a constant phase shift change for each row,

[0137] ΔPSy includes a constant phase shift change for each column,

[0138] mod(M, N) involves calculating the modulus of M divided by N.

[0139] 2 A Indicates the number of pixels in the row, and

[0140] 2 B Indicates the number of pixels in the column.

[0141] Example 20. A system according to any combination of Examples 18 to 19, wherein the LED control circuit device includes a pulse width modulation (PWM) engine, wherein the PWM engine is configured to: store a fixed phase shift map; apply the fixed phase shift map to a pixel matrix duty cycle map to generate a pixel drive matrix including multiple shifted duty cycle values.

[0142] Example 21. A system according to any combination of Examples 18 to 20, wherein the plurality of pixel driver circuits of the LED unit comprises a plurality of switches, wherein: the respective switches are electrically coupled to respective pixels of a pixel matrix; and the brightness output of each respective pixel of the pixel matrix is based on a shift duty cycle value associated with each pixel defined by the pixel driver matrix.

[0143] Various examples of the disclosure have been described. These and other examples are within the scope of the following claims.

Claims

1. A method for an electronic circuit, comprising: receiving a light pattern via a light emitting diode (LED) control circuit arrangement, wherein the light pattern comprises a pixel matrix duty cycle map including a plurality of first duty cycle values; applying a fixed phase shift map to the pixel matrix duty cycle map via the LED control circuit arrangement, wherein each entry in the fixed phase shift map is associated with a corresponding pixel in the LED pixel matrix, and wherein each respective pixel is associated with a respective pixel driver circuit; as well as A pixel drive matrix is generated by the LED control circuit arrangement, the pixel drive matrix comprising a plurality of shifted duty cycle values, wherein each shifted duty cycle value is based on each first duty cycle value and the applied fixed phase shift map.

2. The method according to claim 1, further comprising: The fixed phase shift map is generated by calculating the phase shift for each pixel geometric position in the LED pixel matrix according to the following equation: Phase_Shift x，y =F3[F1(x)+F2(y)] Where for each pixel geometric position (x, y): x indicates the row of the pixel's geometric location, y indicates the column of the pixel's geometric position, F1(x) comprises a first function based on the pixel row position, F2(y) comprises a second function based on pixel column position, and F3[…] includes the third function.

3. The method of claim 2 , wherein generating the fixed phase shift map comprises: The phase shift for each pixel geometric position is calculated according to the following equation: Where for each pixel geometric position (x, y): ΔPScycle is the dynamic correction of the phase shift for each PWM cycle. ΔPSx indicates the constant phase shift change for each row, ΔPSy indicates the constant phase shift change for each column, mod(M;N) includes the modulus of M divided by N, 2 A Indicates the number of pixels in the row, and 2 B Indicates the number of pixels in the column. The method according to claim 3 , wherein ΔPScycle=0.

5. The method according to claim 1, wherein the pixel matrix duty cycle mapping is based on a pulse width modulation (PWM) period T PWM .

6. The method of claim 5, wherein applying the fixed phase shift map to the pixel matrix duty cycle map comprises: For each corresponding first duty cycle value, Response to (PSi+DCi) <T PWM , applying a phase shift to the corresponding first duty cycle value to produce a corresponding shifted duty cycle value, wherein: PSi comprises said calculated phase shift for the selected pixel geometry, and DCi comprises a first duty cycle duration for the selected pixel geometry.

7. The method of claim 5, wherein applying the fixed phase shift map to the pixel matrix duty cycle map comprises: For each corresponding first duty cycle value, In response to (PSi+DCi)>T PWM , where PSi is the calculated phase shift for the selected pixel geometry and DCi is the first duty cycle duration for the selected pixel geometry: The phase shift is applied to a first segment of the first duty cycle value, wherein the first segment includes T PWM -PSi, and Applying a zero phase shift to a second segment of the first duty cycle value, wherein the second segment comprises: DCi-(T PWM -PSi).

8. The method of claim 1, wherein the LED control circuitry receives the light pattern at each refresh cycle.

9. The method according to claim 1, further comprising: Each raw duty cycle value in the received pixel matrix duty cycle map is processed by the LED control circuitry, wherein the processing includes adding one or more corrections to each raw duty cycle value in the plurality of raw duty cycle values.

10. The method according to claim 1, further comprising: Each raw duty cycle value in the received pixel matrix duty cycle map is converted to a second duty cycle value, wherein the second duty cycle value has a higher resolution than the raw duty cycle value.

11. An electronic circuit comprising: an input interface configured to receive a signal comprising a light pattern, wherein the light pattern comprises a pixel matrix duty cycle map for a matrix of LED pixels, the pixel matrix duty cycle map comprising a plurality of first duty cycle values; a plurality of pixel driver circuits, wherein each pixel driver circuit is associated with a respective pixel in the pixel matrix; A processing circuit device configured to: applying a fixed phase shift map to the received pixel matrix duty cycle map, wherein each entry in the fixed phase shift map is associated with each corresponding pixel in the LED pixel matrix based on the geometric position of each corresponding pixel in the LED pixel matrix; generating a pixel drive matrix comprising a plurality of shifted duty cycle values, wherein each shifted duty cycle value is based on each first duty cycle value and the fixed phase shift map; as well as The pixel driving matrix is output to the plurality of pixel driver circuits.

12. The electronic circuit of claim 11 , wherein each entry in the fixed phase shift map is based on a phase shift associated with each pixel geometric position according to the following equation: Where for each pixel geometric position (x, y): x indicates the row of the pixel's geometric location, y indicates the column of the pixel's geometric position, ΔPScycle is the dynamic correction of the phase shift for each PWM cycle. ΔPSx indicates the constant phase shift change for each row, ΔPSy indicates the constant phase shift change for each column, mod(M;N) includes the modulus of M divided by N, 2 A Indicates the number of pixels in the row, and 2 B Indicates the number of pixels in the column. The electronic circuit according to claim 12 , wherein ΔPScycle=0.

14. The electronic circuit of claim 11 , wherein the pixel matrix duty cycle mapping is based on a pulse width modulation (PWM) period T PWM .

15. The electronic circuit of claim 14 , wherein applying the fixed phase shift map to the pixel matrix duty cycle map comprises: For each corresponding first duty cycle value, Response to (PSi+DCi) <T PWM , applying a phase shift to the corresponding first duty cycle value to produce a corresponding shifted duty cycle value, wherein: PSi comprises said calculated phase shift for the selected pixel geometry, and DCi comprises a first duty cycle duration for the selected pixel geometry.

16. The electronic circuit of claim 14, wherein applying the fixed phase shift map to the pixel matrix duty cycle map comprises: For each corresponding first duty cycle value, In response to (PSi+DCi)>T PWM , where PSi is the calculated phase shift for the selected pixel geometry and DCi is the corresponding first duty cycle duration for the selected pixel geometry: The phase shift is applied to a first portion of the first duty cycle value, wherein the first portion includes T PWM -PSi, and Applying a zero phase shift to a second portion of the first duty cycle value, wherein the second portion comprises: DCi-(T PWM -PSi).

17. The electronic circuit according to claim 11, further comprising: The signal processing circuit device (104) is configured to: adding one or more corrections to each first duty cycle value, and Each first duty cycle value is converted to a second duty cycle value, wherein the second duty cycle value has a higher resolution than the first duty cycle value.

18. An electronic system comprising: a controller unit configured to output a signal including a light pattern; a light emitting diode (LED) unit comprising a plurality of pixel driver circuits, wherein each pixel driver circuit is associated with a respective pixel in a pixel matrix; as well as An LED control circuit device comprising: an input interface configured to receive the signal comprising the light pattern, wherein the light pattern comprises a pixel matrix duty cycle map having a plurality of first duty cycle values; and A processing circuit device configured to: applying a fixed phase shift map to each first duty cycle value of the plurality of first duty cycle values, wherein each entry in the fixed phase shift map is associated with each corresponding pixel in the LED pixel matrix based on a geometric position of each corresponding pixel in the LED pixel matrix; generating a pixel drive matrix comprising a plurality of shifted duty cycle values, wherein each shifted duty cycle value is based on each first duty cycle value and the fixed phase shift map; and The pixel driving matrix is output to the plurality of pixel driver circuits.

19. The electronic system of claim 18, wherein each entry in the fixed phase shift map is based on a phase shift associated with each pixel geometric position according to the following equation: Where for each pixel geometric position (x, y): x indicates the row of the pixel's geometric location, y indicates the column of the pixel's geometric position, ΔPScycle is the dynamic correction of the phase shift for each PWM cycle. ΔPSx includes a constant phase shift change for each row, ΔPSy includes a constant phase shift change for each column, mod(M;N) includes the modulus of M divided by N, 2 A Indicates the number of pixels in the row, and 2 B Indicates the number of pixels in the column.

20. The electronic system of claim 18, wherein the LED control circuit arrangement comprises a pulse width modulation (PWM) engine, wherein the PWM engine is configured to: storing the fixed phase shift map; The fixed phase shift map is applied to the pixel matrix duty cycle map to generate the pixel drive matrix including the plurality of shifted duty cycle values.

21. The electronic system of claim 18, wherein the plurality of pixel driver circuits of the LED unit comprises a plurality of switches, wherein: Respective switches are electrically coupled to respective pixels of the pixel matrix; The luminance output of each corresponding pixel of the pixel matrix is based on the shift duty cycle value associated with each pixel as defined by the pixel drive matrix.

Images