TW202326680A - Display driving circuit and method of brightness compensation thereof - Google Patents

Abstract

A display driving circuit configured to control a display panel is provided, which includes a memory and a processor. The display panel includes multiple pixel circuits forming multiple blocks. Each of the multiple blocks includes a part of pixel circuits of the multiple pixel circuits. The memory is configured to store multiple compensation data of the multiple blocks. The processor is configured to read the multiple compensation data to compensate the brightness of the multiple blocks, respectively. The processor is also configured to calculate a global loading according to grayscale values of the multiple pixel circuits; calculate a local loading according to grayscale values of the part of the pixel circuits in a first block of the multiple blocks; and adjust an original slope of a control signal received by the first block to an adjusted slope according to the local loading and the global loading to control the light-emitting time length of the first block.

Description

Display driving circuit and its method of compensating brightness

This disclosed document relates to brightness control technology of a display device, especially a display driving circuit capable of avoiding brightness error compensation and a method for compensating brightness thereof.

Sub-millimeter light-emitting diodes (Mini Light-Emitting Diode) refer to light-emitting diodes with a grain size of about 100 microns, while Micro Light-Emitting Diodes (Micro Light-Emitting Diode) are light-emitting diodes with a grain size of less than 50 microns. diode. When submillimeter light-emitting diodes and micro light-emitting diodes are applied to displays, because of the large driving current when emitting light, the voltage drop (IR drop) generated by the system impedance is relatively large, making the driving current between different pixels There will be differences and thus make the luminous brightness of the display uneven.

The brightness test and calibration process of the traditional display panel before leaving the factory will write the compensation data into the memory to compensate for the uneven brightness of the display panel that may occur due to voltage drop. However, as the overall current drawn by the display panel is different when the display panel emits light, the voltage drop of different blocks will also change accordingly. Therefore, the fixed compensation data at the factory may cause over-compensation or under-compensation, that is, some areas of the display panel are too bright or some areas are too dark.

The disclosed document provides a display driving circuit for controlling a display panel. The display panel includes a plurality of pixel circuits forming a plurality of partitions. Each partition includes a plurality of pixel circuits and a part of the pixel circuits. The display driver circuit includes memory and processor. The memory is used to store multiple compensation data of multiple partitions. The processor is used to read a plurality of compensation data to respectively compensate the brightness of a plurality of partitions, and the voltage correction amounts represented by different compensation data are positively related to the voltage drop of different partitions. The processor is also used to calculate the global load based on the grayscale values of multiple pixel circuits; calculate the local load based on the grayscale values of some pixel circuits in the first partition of the multiple partitions; and calculate the local load according to the global load and the local load. The original slope of the control signal received by the first subregion is adjusted to the adjusted slope, so as to control the lighting time length of the first subregion.

This disclosure provides a method for compensating brightness, which is suitable for display driving circuits. The display driving circuit is used to control the display panel. The display panel includes a plurality of pixel circuits forming a plurality of partitions. Each partition includes a part of pixel circuits of the plurality of pixel circuits. The display driving circuit is also used for accessing a plurality of compensation data to respectively compensate the brightness of a plurality of partitions. The voltage correction amount represented by different compensation data is directly related to the voltage drop of different partitions. The method includes calculating the global load based on the gray scale values of multiple pixels; according to the gray scale of some pixel circuits in the first partition of the multiple partitions Calculate the partial load; obtain the current load current and the heaviest load current of the first partition from the lookup table according to the global load and partial load; calculate the load current difference based on the current load current and the heaviest load current; The original slope of the control signal received by the first subregion is adjusted to the adjusted slope, so as to control the lighting time length of the first subregion.

This disclosure provides a method for compensating brightness, which is suitable for display driving circuits. The display driving circuit is used to control the display panel. The display panel includes a plurality of pixel circuits forming a plurality of partitions. Each partition includes a part of pixel circuits of the plurality of pixel circuits. The display driving circuit is also used for accessing a plurality of compensation data to respectively compensate the brightness of a plurality of partitions. The voltage correction amount represented by different compensation data is directly related to the voltage drop of different partitions. The method includes calculating the global load based on the gray scale values of multiple pixels; according to the gray scale of some pixel circuits in the first partition of the multiple partitions Calculate the partial load; obtain the current load current and the heaviest load current of the first partition from the lookup table according to the global load and partial load; calculate the load current difference based on the current load current and the heaviest load current; The original frequency of the control signal received by the first subregion is adjusted to the adjusted frequency, so as to control the light-emitting time length of the first subregion.

Embodiments of the disclosed document will be described below in conjunction with related figures. In the drawings, the same reference numerals indicate the same or similar elements or method flows.

FIG. 1A is a simplified functional block diagram of a display panel 100 according to an embodiment of the disclosure. The display panel 100 includes a plurality of pixel circuits 150 forming a plurality of partitions 140 , that is, each partition 140 includes a part of the pixel circuits 150 of the plurality of pixel circuits 150 . The display panel 100 further includes a display driving circuit 110 , a source driver 120 and a gate driver 130 . The display driving circuit 110 is used for providing display data Data_d to the source driver 120 according to the image data Data_v, providing a control clock signal GS to the gate driver 130 , and providing control signals S11˜Sij to a plurality of partitions 140 . In some embodiments, the image data Data_v may come from a graphics processing unit (GPU) or a central processing unit (CPU). The display data Data_d is used to designate the grayscale values of the plurality of pixel circuits 150 . The source driver 120 is used for providing a plurality of data voltages V _data (only one of them is shown for brevity) to the plurality of pixel circuits 150 according to the display data Data_d. The gate driver 130 is used to provide multiple scanning signals V _scan (For the sake of brevity, only one of them is shown as a representative) to a plurality of pixel circuits 150 to drive the plurality of pixel circuits 150 to receive the data voltage V _data .

In an embodiment, the display driving circuit 110 may be implemented by a display driver IC (DDIC for short). In one embodiment, the display driving circuit 110 may be composed of a timing controller (timing controller, TCON for short), a field programmable gate array (field programmable gate array, FPGA for short), or an application specific integrated circuit (application specific integrated circuit). , referred to as ASIC) to achieve. The timing controller can be used to control the timing actions of the display panel 100, such as adjusting the frequency of the clock signal GS to control the update rate of the display panel 100 to achieve power saving; the timing controller can also process the image data Data_v, such as decoding image data Data_v, change the resolution (Scaling) of the image data Data_v, perform analog to digital conversion on the image data Data_v when the image data Data_v is in analog form, and so on.

The multiple partitions 140 are arranged as a matrix with i rows and j columns, that is, there are i*j partitions 140 in total, where i and j are positive integers. The control signals S11˜Sij are sent to the aforementioned i*j partitions 140 respectively, and the index in each label of the control signals S11˜Sij represents the corresponding partition 140 . For example, the control signal S11 is sent to all the pixel circuits 150 in the partition 140 located in the upper left corner of FIG. 1A ; the control signal Sij is sent to all the pixel circuits 150 in the partition 140 located in the lower right corner of FIG. 1A , and so on.

FIG. 1B is a simplified schematic diagram of a pixel circuit 150 according to an embodiment of the disclosure. FIG. 1B shows the pixel circuits 150 in the partition 140 receiving the control signal Sij. It can be understood that the pixel circuits 150 in different partitions 140 may have the same circuit structure but receive different control signals. The pixel circuit 150 includes transistors 151 , 152 and 153 , a pulse width modulation (PWM) signal generator 154 and a light emitting element 155 . The control terminal of the transistor 151 is used for receiving the scan signal V _scan , the first terminal is used for receiving the data voltage V _data , and the second terminal is coupled to the PWM signal generator 154 . The control end of the transistor 152 receives the light emitting signal V _EM , the first end is used to receive the first working voltage V _DD , and the second end is coupled to the first end of the transistor 153 , wherein the light emitting signal V _EM can be controlled by the gate drive circuit 130 or generated by additional gate drive circuitry. The control terminal of the transistor 153 receives the output signal V _out output by the PWM signal generator 154 , the first terminal is coupled to the second terminal of the transistor 152 , and the second terminal is coupled to the first terminal of the light emitting element 155 .

In this embodiment, the control signals S11˜Sij are ramp signals. The PWM signal generator 154 is used for receiving the control signal Sij, and is used for determining the pulse width of the output signal V _out according to the slope of the control signal Sij and the data voltage V _data , wherein the output signal V _out is used to turn on the transistor T153. Therefore, the light-emitting time length of the pixel circuit 150 is related to the slope of the control signal Sij, the magnitude of the data voltage V _data , and the pulse width of the output signal V _out .

FIG. 2 is a simplified functional block diagram of the display driving circuit 110 according to an embodiment of the disclosure. The display driving circuit 110 includes a memory 210 and a processor 220 . The memory 210 is used to store a plurality of compensation data Cm_11 ˜ Cm_ij of a plurality of partitions 140 , and the index in each label of the compensation data Cm_11 ˜ Cm_ij represents the corresponding partition 140 . The processor 220 is used for reading a plurality of compensation data Cm_11˜Cm_ij to compensate brightness of the plurality of partitions 140 respectively. For example, the processor 220 can adjust the display data Data_d according to the compensation data Cm_11, so that the multiple data voltages V _data provided to the upper left corner region 140 in FIG. 1A have a common voltage correction value. For another example, the processor 220 may adjust the display data Data_d according to the compensation data Cm_ij, so that the plurality of data voltages V _data provided to the lower right corner region 140 in FIG. 1A have another common voltage correction value.

The voltage correction amounts represented by different compensation data are directly related to the voltage drop (IR drop) of different partitions 140 . The voltage drop refers to the voltage drop (or rise) caused by the impedance of the power line when the first working voltage V _DD (or the second working voltage V _SS ) is transmitted on the power line. In some embodiments, the lower section 140 in FIG. 1A has a larger voltage drop. For example, the voltage drop of the subregion 140 corresponding to the compensation data Cm_ij is greater than the voltage drop of the subregion 140 corresponding to the compensation data Cm_1j, so the voltage correction amount represented by the compensation data Cm_ij is greater than the voltage correction amount represented by the compensation data Cm_1j, and so on. The brightness unevenness (mura) phenomenon of the display panel 100 is eliminated. However, the disclosed document is not limited thereto, and the voltage drop of each partition 140 will be different due to the actual layout of the power lines.

In some embodiments, the compensation data Cm_11˜Cm_ij are written into the memory 210 during the brightness test and calibration process before the display panel 100 leaves the factory. However, as the overall current drawn by the display panel 100 is different, the voltage drop of the block 140 will also change accordingly. Therefore, the fixed compensation data Cm_11˜Cm_ij may cause over-compensation or under-compensation, that is, the brightness of some blocks 140 is too bright or too dark. Therefore, this disclosure provides two brightness compensation methods 400 and 600 to improve this problem. The brightness compensation methods 400 and 600 will be described in the following paragraphs with reference to FIG. 4 and FIG. 6 . In order to facilitate the understanding of the brightness compensation method 400 , the control signal provided by the display panel 100 to the pixel circuit 150 in FIG. 2 and the operation of the pixel circuit 150 in FIG. 2 will be described below with reference to FIG. 3 .

FIG. 3 is a simplified waveform diagram of the signal input to the pixel circuit 150 in FIG. 2 . In the embodiment of FIG. 3, transistors 151, 152 and 153 are P-type transistors. The operation of the pixel circuit 150 in one frame can be divided into three stages, which are the reset stage, the scan stage and the light emitting stage _{TEM_Stage} . In FIG. 3, the waveform of the control signal Sij shown by the dotted line is the default waveform of the control signal Sij, and the waveform marked by the solid line is the waveform adjusted by the brightness compensation method 400, which is actually output to the control of the pixel circuit 150. The signal Sij will have a waveform marked with a dotted line.

Please refer to FIG. 2 and FIG. 3 at the same time. In the reset phase, the data signal V _data with added voltage correction is input to the PWM signal generator 154 .

In the scanning phase, the pixel circuit 150 can detect and compensate the variation of the threshold voltage of the transistor 153 , so that the driving current I _LED generated by the transistor 153 is not affected by the threshold voltage of the transistor 153 . The method of compensating the variation of the threshold voltage is well known to those skilled in the art, so the related description is omitted here.

In the light-emitting stage, the control signal Sij will start to drop from the initial voltage value V _original , and when the control signal Sij drops below the data voltage V _data , the PWM signal generator 154 will make the output signal V _out have a pulse wave to turn on the transistor 153 And a driving current I _LED is generated. It can be seen from FIG. 3 that the adjusted waveform of the control signal Sij will reduce the pulse width of the output signal V _out by a time difference Δt, that is, the light emitting time of the pixel circuit 150 will be shortened by a time difference Δt. By controlling the time difference Δt by adjusting the slope of the control signal Sij, the aforementioned problems of over-compensation or under-compensation can be improved. The steps of adjusting the slope of the control signal Sij in the brightness compensation method 400 will be described in detail below with reference to FIG. 4 .

FIG. 4 is a flowchart of a method 400 for compensating brightness according to an embodiment of the disclosure. The method 400 will be described below with reference to FIGS. 2 to 4 . The method 400 adjusts the slope of a control signal (such as the control signal Sij exemplified below) to avoid brightness overcompensation or undercompensation of the block 140 corresponding to the control signal. However, the method 400 can be executed multiple times to adjust the slopes of all the control signals S11˜Sij. Any combination of features of method 400 or other methods described herein may be implemented by a plurality of instructions stored on a non-transitory computer readable medium or in memory 210 as described above. These instructions, when executed, cause the processor 220 to perform part or all of any of the aforementioned methods. It should be understood that any method described herein may contain more or fewer steps than shown in the flowcharts, and that steps in the method may be performed in any suitable order.

Step S410 is to calculate the global load based on the grayscale values of all pixel circuits 150 in the display panel 100 (which can be understood as the average grayscale value of all pixel circuits 150 in the display panel 100), wherein the global load L _g is calculated as in <Formula 1 ": "Formula 1"

In "Formula 1", n _pixel represents the number of multiple pixel circuits 150, g _i represents the grayscale value of each pixel circuit 150, g _max represents the maximum grayscale value of the display panel 100, and i is a positive integer.

In one embodiment, the resolution of the display panel 100 is 800x600 (that is, the number of pixels is 480,000), and the gray scale value ranges from 0 to 255. If the grayscale value of each pixel circuit 150 is 100, the global load L _g is 39.2%.

Step S420 is to calculate the local load _L1 according to the grayscale values of all pixel circuits 150 in a subregion 140 (the average grayscale value of all pixel circuits 150 in the subregion 140 can be understood), wherein the local load _L1 is calculated as "formula 2": "Formula 2"

In "Formula 2", n _{part_pixel} represents the number of pixel circuits 150 in the partition 140, and j is a positive integer.

In one embodiment, the number of pixel circuits 150 in a partition 140 is 1000, and the grayscale value range of the display panel 100 is 0~255. If the grayscale value of each pixel circuit 150 in the partition 140 is 150, then The local load L _l is 58.8%.

Step S430 is to obtain the current load current I _present and the heaviest load current I _max of a subregion 140 from the lookup table according to the global load L _g and the local load L _l of the subregion 140 . In one embodiment, the look-up table can be stored in the memory 210 of FIG. 2 . The current load current I _present can be understood as the average value of the current driving current I _LED of all the pixel circuits 150 in the partition 140 . The heaviest load current I _max can be understood as the driving current I _LED of the pixel circuits 150 in the subregion 140 when all the pixel circuits 150 in the display device 100 display the highest gray scale.

Step S440 is to calculate the load current difference ΔI based on the current load current L _l and the heaviest load current I _max , as shown in "Formula 3": "Formula 3"

Step S450 is to adjust the slope of the control signal Sij according to the load current difference ΔI. The relationship between the slope of the control signal Sij before and after adjustment will be described through formula derivation below.

First, after considering the voltage drop of the subregion 140, a representative data voltage V _data of the subregion 140 can be expressed by "Equation 4", wherein the initial voltage V _original represents the voltage value of the control signal Sij at the beginning of the light-emitting phase: "Formula 4"

Please refer to FIG. 3 again, when the control signal Sij drops below the data voltage _Vdata , the pixel circuit 150 will start to emit light. Therefore, by virtue of the similar triangle relationship, when the slope of the control signal Sij is not adjusted, the original light-emitting time length of the pixel circuit 150 can be expressed by <Formula 5>:

In the above formula, T _{EM_original_on} represents the original light-emitting time length of the pixel circuit 150, and T _{EM_stage} represents the total time length of the light-emitting stage,

As mentioned above, the adjustment of the slope of the control signal Sij will cause the light-emitting time of the pixel circuit 150 to be shortened by a time difference Δt. This time difference Δt can be represented by the current load current I _present and the heaviest load current I _max , as shown in "Formula 6 "shown:

Then, after the slope of the control signal Sij is adjusted, a representative light-emitting time length of all pixel circuits 150 in the partition 140 can be expressed by "Formula 7":

Therefore, the slope of the control signal Sij before adjustment can be expressed as "Formula 8", where slope _original represents the slope of the control signal Sij before adjustment:

The adjusted slope of the control signal S_ij can be expressed as "Formula 9", where slopeafter represents the adjusted slope of the control signal Sij:

When the global load L _g is small, the voltage drop of the entire panel is small, so that the driving current I _LED flowing through the pixel circuit 150 increases, and an overcompensation phenomenon may occur. However, it can be known from "Equation 9" that the rising driving current I _LED will increase the load current difference ΔI, which will increase the slope of the control signal Sij (because the slope of the control signal Sij is negative), thereby making the pixel circuit 150 The light emitting time is shortened to reduce its brightness, thus avoiding overcompensation phenomenon. On the other hand, when the global load L _g is large, the voltage drop across the entire panel is large, so that the driving current I _LED flowing through the pixel circuit 150 is low, and the load current difference ΔI will decrease at this time, so that the control signal Sij The slope of is reduced moderately, thereby avoiding the phenomenon of undercompensation. That is, the load current difference ΔI is positively correlated with the slope of the control signal Sij.

FIG. 5 is a simplified waveform diagram of the control signal of the pixel circuit 150 in FIG. 2 . In the embodiment of FIG. 5 , the transistors 151 , 152 and 153 are P-type transistors, and the control signals S11˜Sij are clock signals. The operation area of the pixel circuit 150 is divided into three stages, which are respectively a reset stage, a scan stage and a light emitting stage _{TEM_Stage} . The waveform of the control signal Sij shown by a dotted line in FIG. 5 is the default waveform of the control signal Sij, and the waveform marked by a solid line is the waveform adjusted by the brightness compensation method 600, which is actually output to the pixel circuit 150. The control signal Sij will have a waveform marked with a solid line. The operation contents of the reset stage and the scan stage in Fig. 5 are the same as those described in Fig. 3, and will not be repeated here.

In the lighting phase, when the control signal Sij has continuous pulses, the PWM signal generator 154 will make the output signal V _out have pulses and turn on the transistor 153 to generate the driving current I _LED . It can be seen from FIG. 5 that the control signal Sij has a predetermined number (for example, 4) of pulses in the light-emitting phase, and the frequency of the adjusted waveform of the control signal Sij is relatively high, thus reducing the pulse width of the output signal V _out The time difference Δt, that is, shortens the light emitting time of the pixel circuit 150 by a time difference Δt.

In other words, if the frequency of the control signal Sij becomes higher, the light-emitting time of the pixel circuit 150 will be shortened, and if the frequency of the control signal Sij is lower, the light-emitting time of the pixel circuit 150 will be extended. By adjusting the frequency of the control signal Sij to control the time difference Δt, the aforementioned problems of over-compensation or under-compensation can be improved. The steps of adjusting the frequency of the control signal Sij in the brightness compensation method 600 will be described in detail below with reference to FIG. 6 .

FIG. 6 is a flowchart of a method 600 for compensating brightness according to an embodiment of the disclosure. The method 600 adjusts the frequency of the control signal Sij to improve the brightness over-compensation or under-compensation phenomenon. However, the method 600 can be executed multiple times to adjust the slopes of all the control signals S11˜Sij. Any combination of features of method 600 or other methods described herein may be implemented by a plurality of instructions stored on a non-transitory computer readable medium or in memory 210 as described above. These instructions, when executed, cause the processor 220 to perform part or all of any of the aforementioned methods. It should be understood that any method described herein may contain more or fewer steps than shown in the flowcharts, and that steps in the method may be performed in any suitable order.

Step S610 is to calculate the global load L _g according to the gray scale values of all the pixel circuits 150 in the display panel 100 , wherein the calculation method of the global load is the same as step S410 , and will not be repeated here.

Step S620 is to calculate the local load according to the grayscale values of all the pixel circuits 150 in a partition 140 , wherein the calculation method of the local load is the same as that of step S420 , and will not be repeated here.

Step S630 is to obtain the present load current I _present and the heaviest load current I _max of a partition 140 from the lookup table according to the global load and the local load.

Step S640 is to calculate the load current difference ΔI according to the current load current I _present and the heaviest load current I _max , wherein the calculation method of the load current difference ΔI is the same as step S440 , and will not be repeated here.

Step S650 is to adjust the frequency of the control signal Sij according to the load current difference ΔI. The relationship between the frequency of the control signal Sij before and after adjustment will be described through formula derivation below.

The adjusted light-emitting time length of the pixel circuit 150 can be calculated by the current load current I _present and the heaviest load current I _max , as shown in "Formula 10": "Formula 10"

The frequency of the control signal Sij is inversely proportional to the length of the light emitting time, as shown in "Formula 11": "Formula 11"

In "Formula 11", freq _original represents the frequency of the control signal Sij before adjustment, and freq _after represents the frequency of the control signal Sij after adjustment.

It can be seen from "Formula 11" that the rising driving current I _LED will increase the load current difference ΔI, which will increase the frequency of the control signal Sij, thereby shortening the light-emitting time of the pixel circuit 150 to reduce its brightness, thereby avoiding overcompensation Phenomenon. On the other hand, when the global load L _g is large, the voltage drop across the entire panel is large, so that the driving current I _LED flowing through the pixel circuit 150 is low, and the load current difference ΔI will decrease at this time, so that the control signal Sij The frequency is reduced moderately, thereby avoiding the phenomenon of undercompensation. That is, the load current difference ΔI is positively correlated with the frequency of the control signal Sij.

FIG. 7 is a schematic diagram of simplified waveforms of signals input to the pixel circuit 150 . The signal waveform in FIG. 7 is applicable to the embodiment in which the transistors 151 , 152 and 153 of the pixel circuit 150 are realized by N-type transistors. Therefore, the data voltage V _data , the control signal Sij, the scan signal V _scan and the light emitting signal V _EM have waveforms opposite to those of the corresponding signals in FIG. 4 .

In the embodiment of FIG. 7, the waveform indicated by the solid line of the control signal Sij is the default waveform of the control signal Sij, and the waveform indicated by the dotted line is the waveform adjusted by the aforementioned method 400, which is actually output to the pixel circuit. The control signal Sij of 150 will have a waveform marked with a dotted line. It can be seen from FIG. 7 that if the current difference ΔI increases, the slope of the control signal Sij should decrease (the slope of the control signal Sij is positive) to reduce the lighting time of the pixel circuit 150, and if the current difference ΔI decreases, then The slope of the control signal Sij should increase. That is, when the method 400 is applied to the pixel circuit 150 made of N-type transistors, the method 400 can be adaptively modified so that the current difference ΔI and the slope of the control signal Sij are negatively correlated.

On the other hand, when the method 600 is applied to the pixel circuit 150 made of N-type transistors, the relationship between the current difference ΔI and the frequency of the control signal Sij can still maintain a positive correlation, so details will not be repeated.

Certain terms are used in the specification and claims to refer to particular elements. However, those skilled in the art should understand that the same element may be called by different terms. The description and the scope of the patent application do not use the difference in the name as the way to distinguish the components, but the difference in the function of the components as the basis for the distinction. The term "comprising" mentioned in the specification and scope of patent application is an open term, so it should be interpreted as "including but not limited to". In addition, "coupling" here includes any direct and indirect connection means. Therefore, if it is described that the first element is coupled to the second element, it means that the first element can be directly connected to the second element through electrical connection or signal connection means such as wireless transmission or optical transmission, or through other elements or connections. The means are indirectly electrically or signally connected to the second element.

The description of "and/or" used herein includes any combination of one or more of the listed items. In addition, unless otherwise specified in the specification, any singular term also includes plural meanings.

The above are only preferred embodiments of this disclosure document, and all equivalent changes and modifications made according to the requirements of this disclosure document shall fall within the scope of this disclosure document.

Data_v: image data Data_d: display data 100: display panel 110: display drive circuit 120: source driver 130: gate driver 140: partition 150: pixel circuit GS: control clock signal V _data : data voltage V _scan : scan Signal V _EM : light emitting signal S11~Sij: control signal 151, 152, 153: transistor 154: pulse width modulation signal generator 155: light emitting element V _DD : first operating voltage V _SS : second operating voltage I _LED : driving current 210: Memory 220: processors Cm_11~Cm_ij: compensation data V _out : output signal V _original : initial voltage value 400,600: method S410, S420, S430, S440, S450, S610, S620, S630, S640, S650: step Δt: time difference T _{EM_stage} : the total time length of the light-emitting stage T _{EM_original_on} : the original light-emitting time length of the pixel circuit T _{EM_after_on} : the light-emitting time length

FIG. 1A is a simplified functional block diagram of a display panel according to an embodiment of the disclosure. FIG. 1B is a simplified schematic diagram of a pixel circuit according to an embodiment of the disclosure. FIG. 2 is a simplified functional block diagram of a display driving circuit according to an embodiment of the disclosure. FIG. 3 is a simplified waveform diagram of a signal input to the pixel circuit in FIG. 2 . FIG. 4 is a flowchart of a method for compensating brightness according to an embodiment of the disclosure. FIG. 5 is a simplified waveform diagram of the control signal of the pixel circuit in FIG. 2 . FIG. 6 is a flowchart of a method for compensating brightness according to an embodiment of the disclosure. FIG. 7 is a schematic diagram of simplified waveforms of signals input to the pixel circuit.

Data_v: image data

Data_d: display data

100: display panel

110: Display drive circuit

120: source driver

130: Gate driver

140: partition

150: Pixel circuit

V _data : data voltage

V _scan : scan signal

S11~Sij: control signal

Claims (10)

A display driving circuit for controlling a display panel, wherein the display panel includes a plurality of pixel circuits forming a plurality of partitions, each partition includes a part of the pixel circuits of the plurality of pixel circuits, and the display driving circuit includes: a memory for storing multiple compensation data of the multiple partitions; and A processor for reading a plurality of compensation data to respectively compensate the brightness of the plurality of subregions, and the voltage correction amounts represented by different compensation data are positively related to the voltage drop of different subregions; Among other things, the processor is also used for: calculating a global load according to the grayscale values of the plurality of pixel circuits; calculating a local load according to the gray scale value of the part of the pixel circuit in a first partition of the plurality of partitions; and According to the global load and the local load, an original slope of a control signal received by the first subregion is adjusted to an adjusted slope, so as to control a light-emitting time length of the first subregion. The display driving circuit as described in Claim 1, wherein the global load is obtained by the following equation: Where L _g represents the global load, n _pixel represents the number of the multiple pixel circuits, g _i represents the gray scale value of each pixel circuit in the display panel, g _max represents the maximum gray scale value of the display panel, i is a positive integer; and where the partial load is obtained by the following equation: Where L _l represents the partial load, n _{part_pixel} represents the number of pixel circuits in this part, g _j represents the grayscale value of each pixel circuit in the first partition, and j is a positive integer. The display driving circuit as described in claim 1, wherein the processor is also used for: Obtaining a current load current and a heaviest load current of the first partition from a lookup table according to the global load and the local load, and calculating a load current difference according to the current load current and the heaviest load current, and according to The load current difference adjusts the slope of the control signal. The display driving circuit as described in claim 3, wherein the adjusted slope of the control signal is obtained by the following equation: Among them, slope _original represents the original slope, slope _after represents the adjusted slope, ΔI represents the load current difference, I _present represents the current load current, L _g represents the global load, and L _l represents the local load. A method for compensating brightness, suitable for a display driving circuit, wherein the display driving circuit is used to control a display panel, the display panel includes a plurality of pixel circuits forming a plurality of partitions, each partition includes the plurality of pixel circuits A part of the pixel circuit, the display driving circuit is also used to access a plurality of compensation data to respectively compensate the brightness of the plurality of partitions, the voltage correction amount represented by different compensation data is positively related to the voltage drop of different partitions, the method includes: calculating a global load according to the grayscale values of the plurality of pixels; calculating a local load according to the gray scale value of the part of the pixel circuit in a first partition of the plurality of partitions; Obtain a current load current and a heaviest load current of the first partition from a lookup table according to the global load and the local load; calculating a load current difference according to the current load current and the heaviest load current; and According to the load current difference, an original slope of a control signal received by the first subregion is adjusted to an adjusted slope, so as to control a light-emitting time length of the first subregion. The method as described in claim item 5, wherein the global load is obtained by the following equation: Wherein L _g represents the global load, n _pixel represents the number of the plurality of pixel circuits, g _i represents the gray scale value of each pixel circuit in the display panel, g _max represents the maximum gray scale value of the display panel, i is a positive integer; and where the partial load is obtained by the following equation: Where L _l represents the partial load, n _{part_pixel} represents the number of pixel circuits in this part, g _j represents the grayscale value of each pixel circuit in the first partition, and j is a positive integer. The method as described in claim 5, wherein the adjusted slope of the control signal is obtained by the following equation: Among them, slope _original represents the original slope, slope _after represents the adjusted slope, ΔI represents the load current difference, I _present represents the current load current, L _g represents the global load, and L _l represents the local load. A method for compensating brightness, suitable for a display driving circuit, the display driving circuit is used to control a display panel, the display panel includes a plurality of pixel circuits forming a plurality of partitions, each partition includes a plurality of pixel circuits A part of the pixel circuit, the display driving circuit is also used to access a plurality of compensation data to respectively compensate the brightness of the plurality of partitions, and the voltage correction amount represented by different compensation data is positively related to the voltage drop of different partitions, the method includes: calculating a global load according to the grayscale values of the plurality of pixel circuits; calculating a local load according to the gray scale value of the part of the pixel circuit in a first partition of the plurality of partitions; Obtain a current load current and a heaviest load current of the first partition from a lookup table according to the global load and the local load; calculating a load current difference according to the current load current and the heaviest load current; and According to the load current difference, an original frequency of a control signal received by the first subregion is adjusted to an adjusted frequency, so as to control a light-emitting time length of the first subregion. The method as described in claim item 8, wherein the global load is obtained by the following equation: Where L _g represents the global load, n _pixel represents the number of the multiple pixel circuits, g _i represents the gray scale value of each pixel circuit in the display panel, g _max represents the maximum gray scale value of the display panel, i is a positive integer; and where the partial load is obtained by the following equation: Where L _l represents the partial load, n _{part_pixel} represents the number of pixel circuits in this part, g _j represents the grayscale value of each pixel circuit in the first partition, and j is a positive integer. The method as claimed in claim 8, wherein the adjusted frequency of the control signal is obtained by the following equation: Among them, ΔI represents the load current difference, I _present represents the current load current, freq _original represents the original frequency, and freq _after represents the adjusted frequency.

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