A method and system for displaying high refresh rate at low grayscale in LED

Abstract

The present invention discloses a method and system for displaying a high refresh rate at low grayscale of an LED. It is a display method based on PWM to improve the refresh rate of an LED screen, and belongs to the field of LED display technology. In order to solve the problems of insufficient refresh rate of the LED screen and display effect at low grayscale, the prior art breaks up the display cycle and distributes the lighting cycle as evenly as possible in one frame. However, when the grayscale is high, the original PWM pulse width is wide enough to allocate partial pulses to each broken up group; when the grayscale is low, the original PWM pulse width is short, which is not enough to allocate pulses to each broken up group. The present invention does not change the clock frequency and the total brightness, but reduces the on-current of the LED to the original #imgabs0# and increases the number of pulses to the original 2. P times, that is, the total pulse width becomes twice the previous P times, accordingly, when the LED screen displays in low grayscale, the pulse width can be fully dispersed and increased, ultimately improving the display refresh rate of the LED screen at low grayscale levels.

Description

Technical Field

[0001] The present invention belongs to the technical field of LED display, and in particular, relates to a method and system for displaying an LED with a high refresh rate at low grayscale. Background Art

[0002] When using a mobile phone or other camera device to take photos of LED display devices such as cinema screens, stripes may appear in the photos, making the photos blurry. This is mainly caused by the difference between the camera's shutter frequency and the LED display refresh rate. The common cinema LED screen refresh rate is 24 Hz. If the camera's shutter frequency is higher than the LED display refresh rate, some bright spots and bright lines will be captured, causing stripes to appear in the photos. In order to improve the photo effect of the LED screen, the refresh rate of the LED display needs to be increased.

[0003] The current mainstream LED brightness control method is PWM (Pulse Width Modulation), which controls the brightness by controlling the duration of the LED conduction. Within a period of time, the wider the PWM pulse width, the longer the LED lamp bead is on, and the higher the brightness of the lamp bead. The brightness of LED lamp beads is generally expressed in grayscale, which divides a certain level between the brightest and darkest LED light, expressed in grayscale. The higher the grayscale level, the wider the PWM pulse width, and the brighter the LED. In order to increase the screen refresh rate, the PWM pulse is generally broken up, and a wide pulse is divided into multiple groups.

[0004] Chinese patent application, application number CN202010074883.6, publication date August 4, 2020, discloses a multi-line scanning LED grayscale switching display method and system, belonging to the field of LED display technology. In view of the problems existing in the prior art of insufficient refresh rate, low grayscale level, poor low gray effect, etc. for multi-line scanning constant current source chips, the invention provides a multi-line scanning LED grayscale switching display method and system. When displaying a higher grayscale, the method breaks up the display cycle so that the lighting cycle is distributed as evenly as possible to each frame of the picture, merges the grayscale when displaying a lower grayscale, and compensates for the grayscale loss caused by the response time of the analog circuit through a grayscale compensation method. The invention can still ensure a higher refresh rate and grayscale level when there are more line scans, and solve the problems of low gray spots, low gray dimming and poor low gray linearity in the case of low gray display, so as to improve the display effect.

[0005] However, in high grayscale, the original PWM pulse width is wide enough to allow each group to be assigned a partial pulse; in low grayscale, the original PWM pulse width is short and cannot allow each group to be assigned a partial pulse. Figure 1As shown, assuming that the maximum grayscale level in the system is 16, the number of broken groups is 4, the interval between every two adjacent dotted lines in the figure is one clock cycle, and the LED is turned on and emits light when the PWM pulse is at a high level. Figure 1 101, 103, and 105 represent PWM waveforms with grayscale values ​​of 16, 6, and 2, respectively, and their high-level pulse widths are 16, 6, and 2 clock cycles, respectively. 102 is the waveform after 101 is broken up, and 16 clock cycles are evenly divided into 4 groups, each with 4 clock cycles. After breaking up, the refresh rate becomes 4 times the frame rate; 104 is the waveform after 103 is broken up, and each group is first allocated one clock cycle, and the remaining 2 clock cycles are inserted into groups 1 and 3, and the refresh rate becomes 4 times the frame rate; 106 is the waveform after 105 is broken up, because at this time the grayscale level is less than the number of broken groups, it is not possible to allocate a high-level pulse to each group, and groups 1 and 3 are each allocated a high-level pulse, and groups 2 and 4 have no pulses. At this time, the refresh rate is only 2 times the frame rate. It can be seen that the refresh rate is low under low grayscale (grayscale level is less than the number of broken groups). The key to improving the refresh rate is to increase the refresh rate under low grayscale. To improve the refresh rate under low grayscale display, the fundamental thing is to increase the number of conduction times per unit time. Because the pulse width cannot become smaller after it equals the unit clock period, the pulse width cannot be fully dispersed during low grayscale display, resulting in a low refresh rate. Summary of the invention

[0006] 1. Technical issues to be solved

[0007] In view of the problem existing in the prior art, in the field of LED display technology, the pulse width cannot be further reduced after it is equal to the unit clock period, and the pulse width cannot be fully dispersed under low grayscale display, resulting in a low display refresh rate. The present invention provides a high refresh rate display method under low grayscale based on PWM LED display control, which can fully disperse the pulse width during low grayscale display to improve the display refresh rate under low grayscale.

[0008] 2. Technical solution

[0009] The purpose of the present invention is achieved through the following technical solutions.

[0010] The present invention provides a method for displaying LED with high refresh rate under low grayscale. The LED brightness control method is PWM method. The system frame frequency is F. The specific method steps are as follows:

[0011] Get the number of grayscale digits and grayscale data of the LED: Assume the number of grayscale digits of the system is L; the corresponding maximum grayscale level of the system is 2 L -1, the value of the grayscale data is K.

[0012] Grayscale data compensation: add the compensation value to the grayscale data K to obtain the compensated grayscale data K'; the compensation value is used to offset the brightness loss caused by the actual circuit response time; judge the size of the compensated grayscale data K', if K' is greater than the maximum grayscale level of the system 2 L -1, then the value of the compensated grayscale data K' is set to 2 L -1.

[0013] Determine the number of groups to be broken up: Divide the target refresh rate by the system frame rate F to get the number of groups to be broken up2 N , N is less than the number of gray levels L; according to the number of scattered groups 2 N The L-bit compensated grayscale data K' is divided into M-bit high-bit valid data K MSB and N bits of low-order valid data K LSB , M and N are both positive integers, and M plus N equals L; the high-order valid data K MSB After grouping, each group contains K MSB The pulse width of the clock cycle, the low-order effective data width N represents the compensation grayscale data K' is divided into 2 N Group.

[0014] Break up the pulse width: Determine whether the grayscale data K' after compensation is greater than or equal to 2 N , if K' is greater than or equal to 2 N , the compensated grayscale data K' is conventionally scattered and displayed; if K' is less than 2 N , then set the pulse number multiplication factor P, and adjust the corresponding LED conduction current to the normal The total pulse width is expanded to 2 P times; the compensated grayscale data K' is displayed in a scattered manner by doubling the number of pulses and reducing the LED conduction current.

[0015] According to the number of rows R and channels C displayed by the LED constant current driver chip, repeat the above steps R*C times to form a complete display output.

[0016] In the step of breaking up the pulse width, the method of conventionally breaking up the compensated grayscale data K' for display is as follows:

[0017] First, the high-order valid data K MSB In 2 N Display in group, each group displays K MSB A pulse.

[0018] Then, the remaining low-order valid data K LSB Divide into 2 NDisplay in group: Step 1, generate an N-bit counter CNT to record the number of groups initially divided; Step 2, swap the high and low bits of the counter CNT to generate a new binary group number; Step 3, determine whether the binary group number CNT[0:N-1] is less than the low-bit valid data K LSB , if it is less than , then a PWM pulse with an additional lighting time is displayed in the group, otherwise the group does not display a PWM pulse with an additional lighting time.

[0019] In the step of breaking up the pulse width, the method of breaking up the display by multiplying the number of pulses and reducing the LED conduction current of the compensated grayscale data K' is as follows:

[0020] If K' is less than or equal to 2 N-P , then K' scattered groups contain pulses, and the scattered groups containing pulses are determined by binary division: generate an N-bit counter CNT to record the number of groups initially divided, 0 to 2 N -1, swap the high and low bits of the counter CNT to generate a new binary group number, and determine whether the binary group number CNT[0:N-1] is less than K'. If it is, the PWM pulse is displayed in this group, otherwise the PWM pulse is not displayed in this group. The width of a single pulse in each scattered group is equal to the pulse width of each scattered group in the conventional scattered method, and the number of pulses in each scattered group is expanded to 2 of the original P times.

[0021] When K' is greater than 2 N-P At the same time less than 2 N When K' is equal to 2 N-P The new pulse width in the original PWM waveform is calculated by binary division when K' is equal to 2. N-P The waveform is extended in the existing scattered groups; the width of a single pulse in each scattered group is equal to the width of the extended pulse.

[0022] According to the number of rows R and channels C displayed by the LED constant current driver chip, repeat the above steps of obtaining the LED grayscale level and grayscale data, grayscale data compensation, determining the number of scattered groups and scattered pulse width R*C times to form a complete display output. Therefore, K' is less than 2 N-P When the display refresh rate is 2 times the normal dispersion method of the same gray level P times; K' is greater than or equal to 2 N-P When the corresponding display refresh rate is constant at 2 N ×F.

[0023] 3. Beneficial effects

[0024] Compared with the prior art, the advantages of the present invention are: by reducing the LED conduction current, the pulse width under low grayscale display is correspondingly doubled. At this time, without changing the clock frequency, the pulse width that can be used to distribute the scattered pulses is increased, and in the case of low grayscale (grayscale level is less than the number of scattered groups), the pulse width can also be fully scattered, thereby increasing the refresh rate of the LED screen under low grayscale display, which is conducive to eliminating the bright lines on the photos taken by the camera when taking photos of the LED screen, and improving the photo effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a waveform diagram of breaking up the PWM pulses to increase the display refresh rate under normal circumstances;

[0026] Figure 2 This is a schematic diagram of the relationship between LED brightness, PWM pulse width, and LED conduction current;

[0027] Figure 3 This is a schematic diagram of the PWM waveform of the system using the conventional scattered method at low grayscale;

[0028] Figure 4 for Figure 3 The system shown is a schematic diagram of PWM waveform in which the pulse quantity is multiplied and scattered at low gray scale;

[0029] Figure 5 This is a schematic diagram of the binary allocation principle;

[0030] Figure 6 It is a curve diagram of the corresponding relationship between the grayscale level and the display refresh rate of the conventional dispersion method and the pulse number doubling dispersion method at low grayscale. DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] The present invention provides a method for displaying LED at a high refresh rate under low grayscale. The LED brightness control method is a PWM method. The specific method steps are as follows:

[0034] Get the number of grayscale bits and grayscale data of the LED: Assume that the number of grayscale bits is L, and the corresponding maximum grayscale level set by the system is 2 L -1, the value of grayscale data is K. Grayscale level refers to the number of changes from the darkest to the brightest on the LED screen, representing the bit width of grayscale data, and grayscale data K is the binary value corresponding to the grayscale level, which is any specific value included in the grayscale level range, representing a certain brightness. The larger the value, the higher the brightness. If the grayscale level has L bits, then the LED screen has 2 LThe grayscale data is 2 L A specific value within the range, L-bit grayscale data {D L-1 ,D L-2 ...D1, D0} are sent by the sending card to the chip, and the displayed grayscale range is 0 to 2 L -1.

[0035] Grayscale data compensation: add a compensation value to the grayscale data K to get the compensated grayscale data K'. The compensation value offsets the brightness loss caused by the actual circuit response time. The brightness loss is caused by the actual analog circuit switch requiring a certain response time. The specific value is the difference between the corresponding grayscale theoretical display time and the actual display time. Determine the size of the compensated grayscale data K'. If the compensated grayscale data K' is greater than the maximum grayscale level set by the system, L -1, the value of the compensated grayscale data K' is set to the maximum value 2 L -1.

[0036] Determine the number of groups to be broken up: Based on the frame rate F in the system and the target refresh rate you want to get, divide the target refresh rate by the system frame rate F to get the number of groups to be broken up. N ; N is less than the number of gray levels L; according to the number of scattered groups 2 N The L-bit compensated grayscale data K' is divided into M-bit high-bit valid data K MSB and N bits of low-order valid data K LSB , M and N are both positive integers, and M plus N equals L; the high-order valid data K MSB After grouping, each group contains K MSB The pulse width of the clock cycle, the low-order effective data width N represents the compensation grayscale data K' is divided into 2 N Group.

[0037] Break up the pulse width: Determine whether the grayscale data K' after compensation is greater than or equal to 2 N , if greater than or equal to 2 N , the compensated grayscale data K' is conventionally scattered and displayed; if it is less than 2 N , then set the pulse number multiplication factor P, and adjust the corresponding LED conduction current to the normal The total pulse width is expanded to 2 P times; the compensated grayscale data K' is displayed by multiplying the number of pulses and reducing the LED conduction current. In the step of dispersing the pulse width, if K' is greater than or equal to 2 N , which means that each group has a sufficiently wide pulse width. The following method is used to display the compensated grayscale data K' in a conventional manner:

[0038] First, the high-order valid data K MSBRespectively in 2 N Display in group, each group displays K MSB A pulse.

[0039] Then, if Figure 5 As shown, the remaining low-order valid data K LSB Divide into 2 N Display in group: Step 1, generate an N-bit counter CNT to record the number of groups initially divided; Step 2, swap the high and low bits of the counter CNT to generate a new binary group number; Step 3, determine whether the binary group number CNT[0:N-1] is less than the low-bit valid data K LSB , if it is less than , then a PWM pulse with an additional lighting time is displayed in the group, otherwise the group does not display a PWM pulse with an additional lighting time.

[0040] In the step of breaking up the pulse width, if K' is less than 2 N , which means that the pulse width in some groups is insufficient, the conventional dispersion method is not sufficient, and the refresh rate after dispersion cannot reach the expected refresh rate. It is necessary to multiply the number of pulses of the compensated grayscale data K' and reduce the LED conduction current to disperse the display. The specific method is as follows:

[0041] If K' is less than or equal to 2 N-P , then K' scattered groups contain pulses, and the scattered groups containing pulses are determined by binary division: generate an N-bit counter CNT to record the number of groups initially divided, 0 to 2 N -1, swap the high and low bits of the counter CNT to generate a new binary group number, and determine whether the binary group number CNT[0:N-1] is less than K'. If it is, the PWM pulse is displayed in this group, otherwise the PWM pulse is not displayed in this group. The width of a single pulse in each scattered group is equal to the pulse width of each scattered group in the conventional scattered method, and the number of pulses in each scattered group is expanded to 2 of the original P times.

[0042] When K' is greater than 2 N-P At the same time less than 2 N When K' is equal to 2 N-P The new pulse width in the original PWM waveform is calculated by binary division when K' is equal to 2. N-P The waveform is extended in the existing scattered groups; the width of a single pulse in each scattered group is equal to the width of the extended pulse.

[0043] According to the number of rows R and channels C displayed by the LED constant current driver chip, repeat the above steps of obtaining the LED grayscale level and grayscale data, grayscale data compensation, determining the number of scattered groups and scattered pulse width R*C times to form a complete display output. Therefore, K' is less than 2 N-P When the display refresh rate is 2 times the normal dispersion method of the same gray levelP times; K' is greater than or equal to 2 N-P When the corresponding display refresh rate is constant at 2 N ×F.

[0044] Preferably, the LED display system can use the method disclosed in patent application number CN202010074883.6, published on August 4, 2020, to obtain grayscale levels and grayscale data, compensate grayscale data, determine the number of scattered groups and conventional scattered pulse width, etc. The method is described in detail in the patent and will not be repeated here.

[0045] This embodiment focuses on the solution to the problem of low refresh rate under low grayscale. The present invention proposes a scattered display method for doubling the number of pulses and reducing the LED conduction current.

[0046] In the PWM control mode, there are two ways to adjust the brightness of LED lights. One is to adjust the PWM pulse width, that is, the conduction time of the LED lights, and the other is to adjust the current flowing through the LED lights. After the display refresh rate of the LED is improved by technical means, in order to keep the brightness consistent with the original brightness, the total conduction time remains unchanged and the LED conduction current remains unchanged; when the total conduction time increases, the conduction current needs to be reduced accordingly.

[0047] like Figure 2 As shown in the figure, 201 and 202 are two PWM waveforms. The amplitude of 201 is four times that of 202, which means that the conduction current of the LED lamp controlled by 201 is four times that of the LED lamp controlled by 202; the pulse width of 202 is four times that of 201, which means that the conduction time of the LED lamp controlled by 202 is four times that of the LED lamp controlled by 201. The brightness of the LED lamp is equal to the "product" of the conduction time and the conduction current, which can be Figure 2 The area of ​​the shaded part in 201 and 202 is the same, and the LED lights controlled by 201 and 202 have the same luminous brightness.

[0048] Without changing the brightness of the LED lamp beads, the LED conduction current is reduced to the original Then we can get 2 P times the number of pulses, and the total pulse width becomes twice the previous P At this time, without changing the clock frequency, it can be used to distribute the number of scattered pulses to double, and in the case of low grayscale (grayscale level is less than the number of scattered groups), it helps to fully disperse the pulse width, thereby improving the refresh rate.

[0049] You can use a LED display driver chip and application such as the Chinese patent application, application number CN202210042638.6, this method reduces the LED conduction current to the original The DAC small current precision control circuit is used to obtain more accurate current output, which can achieve smaller and more accurate driving current.

[0050] Example 2

[0051] An LED low grayscale high refresh rate display system, characterized in that it is used to perform the method steps described in Example 1, including:

[0052] A shift register receives grayscale data input from the outside and stores the grayscale data in SRAM;

[0053] SRAM, receives and stores grayscale data, and sends the grayscale data to the data processing module;

[0054] A data processing module receives grayscale data, processes the grayscale data, and sends the processed data value to the comparator;

[0055] The clock cycle counter records the number of clock cycles currently displayed and sends the number of clock cycles to the comparator;

[0056] The comparator receives the data value from the data processing module and the number of clock cycles in the counter, compares the two, and outputs a PWM pulse.

[0057] Example 3

[0058] Based on the system provided in Example 2, a method for displaying a high refresh rate at low grayscale of an LED in Example 1 is executed to adjust the refresh rate under different grayscale data. For simplicity, the number of groups of the LED display system is set to 8, that is, the parameter N is 3; the multiplication factor of the number of pulses at low grayscale is 2, that is, the parameter P is 1.

[0059] Figure 3 This is the waveform obtained by using the conventional breaking up method described in patent application number CN202010074883.6 when the grayscale level is 1 to 8. The number of groups is 8, and the PWM pulse width is placed in each breaking up group according to the dichotomy method. It can be seen that when the grayscale level is 8, the display refresh rate is 8 times the frame rate, and when the grayscale level is less than 8, the display refresh rate is lower, and the pulse width of a single clock cycle cannot be divided any more, so a pulse number doubling method is proposed to solve this problem.

[0060] Figure 4The scattered waveform is obtained by reducing the LED on-current and doubling the number of pulses when the grayscale level is 1 to 8. The brightness of the LED is determined by the on-time and the size of the on-current. When the on-current is reduced and the on-time is increased, the brightness of the LED remains unchanged. If the number of pulses is doubled at low grayscale, in order to keep the screen display brightness unchanged, the corresponding LED on-current needs to be reduced to half of the original. Compared with waveforms 301 to 304, waveforms 401 to 404 add a pulse of the same width in the corresponding group, and the waveform amplitude of waveforms 401 to 404 is half of that of 301 to 304, which means that the LED on-current in the control system is half of the original. Compared with waveforms 301 to 304, waveforms 401 to 404 use the pulse number doubling method to achieve a refresh rate that is twice that of the conventional dispersion method at the same grayscale. When the grayscale level is 4, the display refresh rate can reach 8 times the frame rate. When the grayscale level is 5 to 7, in order to keep the display refresh rate consistent, the newly added pulse width is no longer as Figure 3 As shown, it is not placed in the second, fourth, and sixth groups, but the pulse width is extended in the existing first, third, fifth, and seventh groups. For example, waveform 405 has two pulses with a width of 2 clock cycles in the first group, and two pulses with a width of 1 clock cycle in the third, fifth, and seventh groups, and the corresponding LED conduction current is half of the original scattered solution; waveforms 406-407 are similar, and similarly, the corresponding LED conduction current is half of the original scattered solution. When the grayscale level is greater than or equal to 8, the original scattered solution has reached a display refresh rate of 8 times the frame rate, and the display refresh rate reaches the target refresh rate, so the original scattered solution remains unchanged.

[0061] Figure 6 The figure is a schematic diagram of the corresponding relationship between the grayscale level and the display refresh rate in the conventional scattering method and the pulse number doubling scattering method at low grayscale. The horizontal axis is the grayscale level, ranging from 0 to the maximum grayscale level 2 M+N ; The vertical axis is the display refresh rate. In the conventional scattering mode, when the gray level is less than the number of groups 2 N When the display refresh rate is the current gray level multiplied by the frame rate, the turning point of the curve is when the gray level is equal to 2 N , gray level 2 N To the maximum gray level 2 M+N Within the range, the display refresh rate remains unchanged and the number of groups is always 2 N Multiply by the frame rate.

[0062] In the pulse number doubling and LED conduction current dispersion mode, the gray level is less than 2 N-P (Number of scattered groups divided by multiplication factor), the display refresh rate is twice that of the original scattered mode at the same grayscale level. P The turning point is 2 N-P , that is, the turning point of the original scattering method At this time, the display refresh rate reaches group number 2N Multiply by the frame rate. Grayscale level 2 N-P To the maximum gray level 2 M +N Within the range, the display refresh rate maintains group number 2 N The multiplication of the number of pulses and the dispersion of current regulation under low grayscale display make the display refresh rate become 2 times of the original at lower grayscale. P times, at gray level 2 N-P The desired display refresh rate can be achieved by multiplying the number of broken groups by the frame rate.

[0063] The overall process of the display system is as follows: first, all grayscale display data of multi-line scan and multi-channel input from the outside are stored in SRAM through the shift register; when performing line scan display, all the data required for a certain line scan are taken out from SRAM and input into the data processing module, and the data is processed by grayscale compensation, determination of scattered groups, scattered pulse width and other algorithms in the data processing module; the number of clock cycles currently displayed is recorded through a clock cycle counter; the data value processed by the data processing module is compared with the data in the counter through a comparator, and the PWM pulse of each channel is output.

[0064] Grayscale data represents the time required for the number of clock cycles to light up, so it is necessary to compare the number of clocks in the clock cycle counter with the grayscale data. If the value of the clock cycle counter is smaller than the grayscale data, it means that the display is not complete and the display continues; when the value of the clock cycle counter is larger than the grayscale data, it means that the display is complete. The channels will not interfere with each other and will display simultaneously until all data are displayed.

[0065] The above schematically describes the invention and its implementation methods, which is not restrictive. Without departing from the spirit or basic features of the invention, the invention can be implemented in other specific forms. What is shown in the accompanying drawings is only one of the implementation methods of the invention. The actual structure is not limited to this, and any figure mark in the claims should not limit the claims involved. Therefore, if a person of ordinary skill in the art is inspired by it, without departing from the purpose of the invention, a structural method and an embodiment similar to the technical solution are designed without creativity, which should all fall within the scope of protection of this patent. In addition, the word "including" does not exclude other elements or steps, and the word "one" before the element does not exclude the inclusion of "multiple" elements. The multiple elements stated in the product claim can also be implemented by one element through software or hardware. The words first, second, etc. are used to indicate names, and do not indicate any specific order.

Claims

1. A method for high refresh rate display under low grayscale of LED, the steps are as follows: Get the number of grayscale digits and grayscale data of the LED: Assume the number of grayscale digits of the system is L; the corresponding maximum grayscale level of the system is 2 L -1, the value of grayscale data is K; Grayscale data compensation: add the compensation value to the grayscale data K to obtain the compensated grayscale data K'; The compensation value is used to offset the brightness loss caused by the actual circuit response time; the size of the compensated grayscale data K' is determined, if K' is greater than the maximum grayscale level of the system 2 L -1, then the value of the compensated grayscale data K' is set to 2 L -1; Determine the number of groups to be broken up: Divide the target refresh rate by the system frame rate F to get the number of groups to be broken up2 N , N is less than the number of gray levels L; according to the number of scattered groups 2 N The L-bit compensated grayscale data K' is divided into M-bit high-bit valid data K MSB and N bits of low-order valid data K LSB , M and N are both positive integers, and M plus N equals L; the high-order valid data K MSB After grouping, each group contains K MSB The pulse width of the clock cycle, the low-order effective data width N represents the compensation grayscale data K' is divided into 2 N Group; Break up the pulse width: Determine whether the grayscale data K' after compensation is greater than or equal to 2 N , if K' is greater than or equal to 2 N , the compensated grayscale data K' is conventionally scattered and displayed; if K' is less than 2 N , then set the pulse number multiplication factor P, and adjust the corresponding LED conduction current to the normal The total pulse width is expanded to 2 P times; performing a scattered display by doubling the number of pulses of the compensated grayscale data K' and reducing the LED conduction current; According to the number of rows R and channels C displayed by the LED constant current driver chip, repeat the above steps R*C times to form a complete display output.

2. The LED low grayscale high refresh rate display method according to claim 1, characterized in that: The conventional scattered display of the compensated grayscale data K' specifically includes the following steps: The high-order valid data K MSB In 2 N Display in group, each group displays K MSB Pulses; The remaining low-order valid data K LSB Divide into 2 N Displayed in group.

3. The LED low grayscale high refresh rate display method according to claim 1, characterized in that: The method for doubling the number of pulses and reducing the LED conduction current is specifically as follows: If K' is less than or equal to 2 N-P , then K' scattered groups contain pulses, and the scattered groups containing pulses are determined by binary division; the width of a single pulse in each scattered group is equal to the pulse width of each scattered group in the conventional scattered method, and the number of pulses in each scattered group is expanded to the original 2 P times; When K' is greater than 2 N-P At the same time less than 2 N When K' is equal to 2 N-P The new pulse width in the original PWM waveform is calculated by binary division when K' is equal to 2. N-P The waveform is extended in the existing scattered groups; the width of a single pulse in each scattered group is equal to the width of the extended pulse.

4. The LED low grayscale high refresh rate display method according to claim 2, characterized in that: K' is less than 2 N-P When the display refresh rate is 2 times the normal dispersion method of the same gray level P times; K' is greater than or equal to 2 N-P When the corresponding display refresh rate is constant at 2 N ×F, where F is the system frame rate.

5. The LED low grayscale high refresh rate display method according to claim 2, characterized in that: The remaining low-order valid data K LSB Divide into 2 N The display in the group includes the following steps: Generate an N-bit counter CNT to record the number of binary groups; Determine whether CNT[0:N-1] is less than the low-order valid data K LSB , if it is less than , then a PWM pulse with an additional lighting time is displayed in the group, otherwise the group does not display a PWM pulse with an additional lighting time.

6. The LED low grayscale high refresh rate display method according to claim 3, characterized in that: The specific method of determining the pulse-containing scattered group by dichotomy is: Generate an N-bit counter CNT to record the number of binary groups; It is determined whether CNT[0:N-1] is less than K'. If so, PWM pulses are displayed in this group. Otherwise, PWM pulses are not displayed in this group.

7. A method for displaying LED at a high refresh rate under low grayscale according to claim 5 or 6, characterized in that: Generating an N-bit counter CNT to record the number of binary groups specifically includes the following steps: Counter CNT records the number of groups initially divided 0 to 2 N-1 ; Swap the high and low bits of the counter CNT to generate a new binary group number.

8. An LED low grayscale high refresh rate display system, characterized in that: Used to perform the method steps described in any one of claims 1 to 7.

9. The LED low grayscale high refresh rate display system according to claim 8, characterized in that: include: A shift register receives grayscale data input from the outside and stores the grayscale data in SRAM; SRAM, receives and stores grayscale data, and sends the grayscale data to the data processing module; A data processing module receives grayscale data, processes the grayscale data, and sends the processed data value to the comparator; The clock cycle counter records the number of clock cycles currently displayed and sends the number of clock cycles to the comparator; The comparator receives the data value from the data processing module and the number of clock cycles in the counter, compares the two, and outputs a PWM pulse.

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