CN112542135A - LED display screen gray scale display driving module and method - Google Patents
LED display screen gray scale display driving module and method Download PDFInfo
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Abstract
The invention relates to a gray scale display driving module and method of an LED display screen, comprising a first PWM generating module 100, a second PWM generating module 200 and a PWM synthesizing module 300 connected with the first PWM generating module 100 and the second PWM generating module 200; in a display frame period, dividing corresponding gray scale data into first gray scale data displayed circularly and second gray scale data with a fixed group number N; the first gray data is high gray data, the second gray data is low gray data, and after all the high gray data and the low gray data of the gray data are displayed in the same video frame, the high gray data and the low gray data are repeatedly displayed in a circulating mode until the next frame arrives, so that the display refresh rate is improved, the visual effect is enhanced, image flicker can be effectively reduced, and the picture stability is improved.
Description
Technical Field
The invention relates to the technical field of LED display screen driving, in particular to a gray scale display driving module and method for an LED display screen.
Background
The gray scale represents an object using black tones, that is, black is a reference color, and black of different saturation is used to display an image. Each gray object has a luminance value from 0% (white) to 100% (black) of the gray bar. For example, the pixel value is quantized and expressed by one byte (8 b). If the gray scale value with continuous black-gray-white change is quantized into 256 gray scales, the range of the gray scale value is 0-255, the brightness is from dark to light, and the corresponding color in the image is from black to white. Black and white photographs contain all shades of gray between black and white, with each pixel value being one of 256 shades of gray between black and white. The refresh rate of the gray-scale display refers to the number of times of refreshing video frames, and for a fixed frame picture, the duration is limited by the refresh frequency of the display to be a fixed value, and taking 60HZ as an example, the display duration of each frame is about 16.7 milliseconds. For the present, in the middle and high-order display panels, constant current source driving chips capable of outputting high-refresh PWM are usually adopted, and they usually display the whole gray data in a fixed number of groups, and the whole refresh rate is limited by the set number of groups, i.e. f × M, where f is the display refresh frequency and M is the number of gray data groups. Filling each set of gray data in a video frame may not occupy exactly the entire video frame, i.e., there is a display space. This makes the number of PWM groups displayed within a display frame period fixed, and the resulting refresh rate is also fixed and limited, thereby making the displayed image susceptible to flicker and affecting picture quality.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a gray scale display driving module and a method for an LED display screen.
The purpose of the invention is realized by the following technical scheme:
a gray scale display driving module of an LED display screen comprises:
the PWM synthesis module is connected with the first PWM generation module and the second PWM generation module;
in a display frame period, dividing corresponding gray scale data into first gray scale data displayed circularly and second gray scale data with a fixed group number N;
the first gray data and the N groups of second gray data are synchronously and respectively input into a first PWM (pulse width modulation) generation module and a second PWM generation module, wherein the first gray data are input circularly for N times to obtain N groups of first PWM data and N groups of second PWM data;
the PWM synthesis module synthesizes N groups of first PWM data and second PWM data into N groups of gray level PWM data and outputs and displays the data;
and in a display frame period, after the N groups of gray PWM data are displayed, sequentially and circularly displaying the first PWM data and the second PWM data until the display frame is finished.
In other words, in the present invention, after the refresh frequency of the display is fixed, for one display frame, the overall refresh rate of the display frame can be increased by infinitely cycling the refreshed first PWM data and second PWM data. In the prior art, one display frame can only display a fixed number of groups of gray scale data, usually, the gray scale data of the fixed groups can not completely fill up the whole display time of the display frame, but in the invention, the first gray scale data and the second gray scale data, namely the first PWM data and the second PWM data, are displayed in a mode of infinitely circulating the part of time without displaying gray scale (actually, only a plurality of times of refreshing can be performed in one display frame, but the infinite circulating can be performed when enough time is available, and the situation can not occur in practice), so that the refresh rate of the gray scale data in the display frame is integrally improved, the improvement of the stability of video display is facilitated, and the flicker of the picture is avoided.
Further, the sequentially and circularly displaying the first PWM data and the second PWM data means that the 1 st group of gray scale PWM data to the nth group of gray scale PWM data in the N groups of gray scale PWM data are sequentially displayed, and each group of gray scale PWM data includes one first PWM data and one second PWM data, so that the sequentially and circularly displaying the first PWM data and the second PWM data is the gray scale PWM data which is circularly displayed in nature, and the sequentially and circularly displaying is performed from the 1 st group of gray scale PWM data to the nth group of gray scale PWM data to realize the circularly displaying of the first PWM data and the second PWM data.
Further, the first gray data is high gray data, and the second gray data is low gray data. It should be noted that the high gray data and the low gray data referred to in the present invention are only relative, and have no practical definition standard, and the high gray data and the low gray data cannot be regarded as fuzzy expressions. The high gray data and the low gray data are obtained by dividing gray data into low bits and high bits, for example, 13-bit data, which is binary data, and the low gray data is data from the first bit to the nth bit, and the high gray data is data from the nth bit to the 13 th bit, where n can be any one number from 1 to 12 in a strict sense, but n is generally 2 to 4 in practical applications. That is, the gradation data is grouped from lower to higher, and when the lower gradation data is determined, the remaining data is the higher gradation data, or when the higher gradation data is determined, the remaining data is the lower gradation data.
Further, the PWM synthesis module is configured with a counter for configuring the first PWM data and the second PWM data to generate different PWM data in different sets.
The invention also provides a gray scale display driving method of the LED display screen, which is realized by using the gray scale display driving module of the LED display screen, and the method comprises the following steps:
step S100: dividing the gray scale data of each display frame into first gray scale data displayed in a circulating way and second gray scale data with a fixed group number N, wherein N is a fixed integer;
step S200: sending the first gray data into a first PWM (pulse-width modulation) generation module to obtain first PWM data;
synchronously sending the second gray data to a second PWM generating module to obtain second PWM data;
step S300: sending the first PWM data and the second PWM data into a PWM synthesis module to obtain 1 group of PWM data;
repeating the steps S200-S300 for N times to obtain N groups of PWM data in one display frame period;
step S400: sequentially displaying the obtained N groups of PWM data in a display frame period T, wherein the display time periods of the N groups of PWM data are T0-Tn, and the residual time periods Tn-Td are not displayed, wherein T0 represents the starting time of the display frame period T, and Td represents the ending time of the display frame period T;
step S500: and circularly displaying the first PWM data and the second PWM data in turn within the residual time period Tn-Td until the display frame is finished.
Further, the first gray data is high gray data, and the second gray data is low gray data;
correspondingly, the first PWM data is high-gray-scale PWM data, and the second PWM data is low-gray-scale PWM data.
Further, the high gray data are completely the same and are displayed by the same high gray PWM data in a circulating mode. That is, in a display frame, all the high gray data are the same, the low gray data are not necessarily the same (either 0 or 1), and in a display frame period, N PWM data are included, each PWM data is composed of one same high gray data + different low gray data, that is, in the whole display frame, the high gray PWM data are cyclically displayed by the same PWM data.
Further, in a complete display frame period T, M sets of first PWM data are included, and N +
And a set of second PWM data, wherein the first PWM data and the second PWM data are sequentially displayed cyclically,
the number of times of circular display after the second gray scale data is displayed for N times is shown, and M is larger than N.
Furthermore, the invention also comprises a method for switching the transition of adjacent display frames, which uses a VSYNC instruction to switch the display frames, and comprises the following scenes:
1) the VSYNC command arrives in the middle of a first PWM data frame or a second PWM data frame, and is switched to the next display frame in the middle of the first PWM data frame or the second PWM data frame; or, in order to ensure the display effect, the gray data is updated after the current first PWM data frame or the second PWM data frame is displayed, and the display frame is switched to the next display frame;
2) and switching to the next display frame at the end point of the first PWM data frame or the second PWM data frame when the VSYNC command arrives at the end point of the first PWM data frame or the second PWM data frame.
Further, when a VSYNC instruction arrives, the method also comprises two conditions of resetting and not resetting the counter;
under the condition that the counter is reset, the next frame starts to display from the 1 st group of gray PWM data of the N groups of gray PWM data of the frame, and after the N groups of gray PWM data are displayed, the cyclic display is started from the 1 st group of gray PWM data of the N groups of gray PWM data of the frame;
under the condition that the counter is not reset, assuming that the current frame displays N groups of gray-scale PWM data and then displays the N groups of gray-scale PWM data until the x-1 group of the N groups of gray-scale PWM data of the frame is finished, the next frame starts to display from the x group of gray-scale PWM data in the N groups of gray-scale PWM data of the frame, wherein the value of x is [1, N ], and after the x-N groups of gray-scale PWM data are displayed, the 1 group of gray-scale PWM data of the N groups of gray-scale PWM data of the frame starts to display circularly until the frame is displayed.
Furthermore, for 1 PWM channel to control multiple rows of LED lamps, a first PWM data frame should include all rows of first PWM data PWM, and a second PWM data frame should also include all rows of second PWM data PWM.
The invention has the beneficial effects that: compared with the traditional gray scale display, the scheme also divides the gray scale data into the first gray scale data and the second gray scale data of the fixed group to be displayed in one display frame, but also increases the filling of the first gray scale data and the second gray scale data which are circularly displayed for the display frame, so that the whole refresh rate of the display frame is improved.
Drawings
FIG. 1 is a schematic block diagram of a display driver module according to the present invention;
FIG. 2 is a diagram of an embodiment of a display driving module according to the present invention;
FIG. 3 is a schematic diagram of the connection of the counter of the present invention;
FIG. 4 is a schematic diagram of a PWM synthesis module;
FIG. 5 is a schematic illustration of the display of a high gray frame and a low gray frame of the present invention;
FIG. 6 is a schematic diagram of a handover frame of the present invention;
FIG. 7 is a schematic diagram of high and low gray scale display of the present invention with a 4-line example.
Detailed Description
The technical solution of the present invention is further described in detail with reference to the following specific examples, but the scope of the present invention is not limited to the following.
A gray scale display driving module of an LED display screen comprises: a first PWM generation module 100 and a second PWM generation module 200, and a PWM synthesis module 300 connected to the first PWM generation module 100 and the second PWM generation module 200. The structure of which can be seen in figure 1. Specifically, the input terminals of the first PWM generating module 100 and the second PWM generating module 200 are used to input gray data, the output terminals of the first PWM generating module 100 and the second PWM generating module 200 are connected to the input terminal of the PWM synthesizing module 300, and the gray data is changed into PWM data corresponding to the gray in the first PWM generating module 100 and the second PWM generating module 200, wherein the first PWM generating module 100 and the second PWM generating module 200 respectively output one PWM data, and the two PWM data are input to the PWM synthesizing module 300 to synthesize one PWM data.
In a display frame period, dividing corresponding gray scale data into first gray scale data displayed circularly and second gray scale data with a fixed group number N; it can be considered that the complete gradation data in one display frame period is composed of the first gradation data including the cyclic display and the second gradation data of the fixed number N of sets. That is, the gray data is divided into a plurality of cyclically displayed first gray data and N sets of second gray data, wherein the number of cyclically displaying the first gray data in the complete gray data is as follows.
Then there are:
where D is the full gray scale data in the display frame period, D1 is the first gray scale data, and D2 is the second gray scale data.
The first gray data and N sets of second gray data are synchronously and respectively input to the first PWM generating module 100 and the second PWM generating module 200, wherein the first gray data is input N times in a cycle to obtain N sets of first PWM data and N sets of second PWM data. Here, the first gray data and the N sets of second gray data are synchronously input to the first PWM generating module 100 and the second PWM generating module 200, respectively, that is, the first gray data is input repeatedly, 1 time of first gray data is input synchronously every time 1 set of second gray data is input, and the N sets of second gray data are input sequentially, that is, the N times of first gray data are input synchronously, that is, the N times of first gray data are input cyclically, so that the first gray data and the second gray data are combined to obtain N sets of first PWM data and N sets of second PWM data, which are combined to form a complete PWM data.
Specifically, the PWM synthesis module 300 synthesizes N sets of first PWM data and second PWM data into N sets of grayscale PWM data, and outputs and displays the data; and in a display frame period, after the N groups of gray PWM data are displayed, sequentially and circularly displaying the first PWM data and the second PWM data until the display frame is finished. The ending of the display frame in the scheme means that a frame changing instruction of the next display frame comes.
The sequential cyclic display of the first PWM data and the second PWM data in the scheme means that the 1 st group of gray level PWM data and the Nth group of gray level PWM data in the N groups of gray level PWM data are sequentially displayed, each group of gray level PWM data comprises the first PWM data and the second PWM data, so that the sequential cyclic display of the first PWM data and the second PWM data is the cyclic display gray level PWM data essentially, and the sequential display of the first PWM data and the second PWM data is realized by starting from the 1 st group of gray level PWM data and the Nth group of gray level PWM data. That is, N sets of gray PWM data, for example, 16 sets of gray PWM data, are displayed cyclically in the whole display frame period, and the display mode is 1-2-3-4-5-6-7 … … -16-1-2-3 … … in the whole display frame period, that is, a closed loop cycle of N sets of gray PWM data is formed.
Optionally, in an LED display screen gray scale display driving module, the grouping manner of the gray scale data may adopt various grouping manners known in the art, and the grouping principle satisfies that the gray scale value of each group of gray scale data after being accumulated is unchanged, for example, an 8-bit gray scale data, the gray scale value of which is 0-255, that is, the gray scale data is divided into 256 intensity values, the gray scale data may be divided into 32 groups, and each group corresponds to 8 gray scale value intensities (one group of which is maximum 7 gray scale values), that is, 31 × 8+7= 255. That is, to satisfy the first gray data + second gray data =8 (the maximum value is 8), wherein a set of the first gray data + second gray data =7 (the maximum value is 7), as to how the first gray data and the second gray data are distributed, they may be randomly distributed. Likewise, if they are divided into 64 groups, each group corresponds to 4 gray values. There is the first gray data + the second gray data =4 (maximum value is 4), wherein a group of the first gray data + the second gray data =3 (maximum value is 3), that is, the case of gray value 0 is considered separately as a group, and actually the second gray data is not included in the group, that is, in the above example, N takes on values of 32 and 64, respectively, wherein one of the second gray data has 1 gray intensity less than the rest of the group of the second gray data.
The second gray scale data is exemplified by the case that the gray scale data in the field is not scattered and is completely scattered, and when 4 gray scale data are not scattered, the corresponding second gray scale data is 0 to 4, wherein one group of the second gray scale data is 0 to 3. Under the condition that the gray data are scattered completely, the second gray data take values of 0-1, one group of the second gray data is fixed to 0, the value of N in the condition can be considered to be less than 1, namely 1 group of gray PWM data in the N groups of gray PWM data only contains the first gray data, and in order to ensure the consistency of N, the second gray data of the group of gray PWM data can be defaulted to 0.
As a preferred embodiment, in the LED display panel gray scale display driving module of the present invention, the first gray scale data is high gray scale data, and the second gray scale data is low gray scale data. It is to be emphasized that the high gray data and the low gray data referred to in the present invention are relative concepts, not absolute concepts, that is, there is no fixed boundary value between the high gray data and the low gray data. For 8-bit gray data, the gray value is represented by 00000000-8-1= 255. The high gradation data is divided into these 8-bit binary values. Assuming that this gray-scale data is 11111111, if the lower four bits are defined as the low gray-scale data, the high gray-scale data is 11110000, the low gray-scale data is 1111, that is, the first gray-scale data is 11110000, and the second gray-scale data is 1111, that is, the gray-scale data is divided into a set of the gray-scale data of 11110000 and the gray-scale data of 1111. It is obvious that this grouping is not beneficial to increase the refresh rate of the display frames, and for this purpose, grouping is performed using low gray data as a standard, for example, 0-1111 can be divided into 15 (2) by 1 as the low gray data0+21+22+23If the group of = 15) and 1 group of low gradation data fixed to 0 (all-scattered case), that is, if the group is divided into 16 groups, the coefficient of the first gradation data of each group is (2)4+25+26+27) 16=15, i.e. the gray scale value 15 of the first gray scale data, each set of gray scale PWM data is 15+, wherein 1 set is 15+0, i.e. the second gray scale data defaults to 0, i.e =0 (actually, the set does not include the second gray scale data), i.e. in this example, N is 16, i.e. the gray scale PWM data 15+ starts to be repeatedly displayed after the 16 sets of gray scale PWM data 15+ are displayed, so as to enhance the refresh rate of the display frame.
Optionally, in a gray scale display driving module of an LED display panel, in a display frame period, the number of low gray scale data groups is fixed, as described above, after displaying N groups of gray scale PWM data, sequentially and cyclically displaying a first PWM data and a second PWM data until the display frame is finished, that is, in a display frame, the number of groups of actually displayed first gray scale data and second gray scale data is greater than N, where the first gray scale data is high gray scale data, and the second gray scale data is low gray scale data.
Then there are:
Wherein,
the value is 1 in general, and as shown in fig. 3, only one complete low gray frame is included in one display frame period in general, and the complete low gray frame includes N sets of low gray data. But not exclusively
The integer greater than 1 is the case, for example, several groups of gray data are displayed in one display frame period, each group of gray data includes N groups of low gray data, and in practical situations, this situation does not occur generally.
Optionally, in an LED display panel grayscale display driving module, the PWM combining module 300 is configured with a counter, configured to configure the first PWM data and the second PWM data to generate different PWM data in different groups. The gradation data is divided into first gradation data (high gradation portion) and second gradation data (low gradation portion), and the first gradation data directly generates first PWM data from the data. The second gray scale data is combined with the group counter to generate different second PWM data in different groups. The first PWM data generated by the first gray scale data and the second PWM data generated by the second gray scale data jointly form complete PWM data. The PWM synthesis module 300 in the present embodiment may be implemented by using any PWM chip known in the art, and is a schematic diagram of the internal structure of a common PWM chip, as shown in fig. 4. In this chip, the function of the counters is implemented by the row/bank controllers.
Besides, as shown in fig. 3, the counter here may be a counter that is independent from the PWM combining module 300 and is connected to the PWM combining module 300, or may be a clock counter that is built in the PWM combining module 300, and generally, the counter is selected to be configured in the PWM combining module 300, which is also a conventional design manner of the current PWM chip.
The embodiment also provides a driving method for gray scale display of an LED display screen, which is implemented by using the driving module for gray scale display of an LED display screen, and the method includes:
step S100: dividing the gray scale data of each display frame into first gray scale data displayed in a circulating way and second gray scale data with a fixed group number N, wherein N is a fixed integer;
step S200: sending the first gray data into a first PWM generating module 100 to obtain first PWM data;
synchronously sending the second gray data to a second PWM generating module 200 to obtain second PWM data;
step S300: sending the first PWM data and the second PWM data into a PWM synthesis module 300 to obtain 1 group of PWM data;
repeating the steps S200-S300 for N times to obtain N groups of PWM data in one display frame period; the N times of repetition here means that the first gray data are circularly sent to the first PWM generating module 100N times to obtain N identical first PWM data, and the second gray data are sequentially sent to N groups (in principle, each group is not identical), that is, the second gray data are not the same second gray data that are circularly sent repeatedly, but the N groups of second gray data are divided into N times to be sent to the second PWM generating module 200, a group of second gray data are sent at a time, and each group of second gray data are synchronously circularly sent to the first gray data one time, so that each group of obtained PWM data is composed of the first PWM data + the second PWM data.
Step S400: sequentially displaying the obtained N groups of PWM data in a display frame period T, wherein the display time periods of the N groups of PWM data are T0-Tn, and the residual time periods Tn-Td are not displayed, wherein T0 represents the starting time of the display frame period T, and Td represents the ending time of the display frame period T;
step S500: and circularly displaying the first PWM data and the second PWM data in turn in the residual time period Tn-Td until the display frame is finished, wherein the display frequency of the first PWM data in a circular mode is M-N times and the display frequency of the second PWM data in a circular mode is M-N times in the time period Tn-Td according to the formula
Next, the process is carried out.
Optionally, as an optimal implementation, the gray scale display driving method for the LED display panel includes that the first gray scale data is high gray scale data, and the second gray scale data is low gray scale data; correspondingly, the first PWM data is high gray PWM data, and the second PWM data is low gray PWM data. The definition of the high gray data and the low gray data may refer to the related description in the LED display panel gray display driving module, and besides, the grouping manner of the first gray data and the second gray data is also the same as that of the LED display panel gray display driving module, which is not described herein again.
Optionally, in the method for driving the gray scale display of the LED display panel, the high gray data are completely the same, that is, the first gray data are completely the same, and the generated first PWM data are also completely the same, that is, the same high gray data are cyclically displayed in the method, and the same high gray PWM data are cyclically displayed. Referring to fig. 5, in a specific display aspect, in a display period of one display frame, a cyclic display manner of high gray data and low gray data is adopted, that is, high gray data + low gray data + high gray data + low gray data + … … + high gray data … …, and after N (N = N) cycles, that is, after the display of a fixed number N of sets of low gray data is completed, the cyclic display of the high gray data and the low gray data is repeated until the end of the current display frame and the next display frame come.
Optionally, a method for driving gray scale display of LED display panel includes M sets of first PWM data and N + during a complete display frame period T
And a set of second PWM data, wherein the first PWM data and the second PWM data are sequentially displayed cyclically,
the number of times of circular display after the second gray scale data is displayed for N times is shown, and M is larger than N. Referring to FIG. 5, the value of M depends on the number of groups N of the second gray data, the length of the time period Tn-Td, and the location of the transition frame command, for example, in FIG. 5, the transition frame command arrives in the middle of the high gray data display, in which case M is not an integer but a decimal, and may be a value such as 67.4, and similarly, when the transition frame arrives in the low gray display frame, there are 1 incompletely displayed groups corresponding to gray values
。
Optionally, the present invention further includes a method for switching between adjacent display frames, where the method uses VSYNC commands to switch the display frames, and includes the following scenarios:
1) the VSYNC instruction arrives in the middle of a first PWM data frame, the VSYNC instruction is switched to the next 1 in the middle of the first PWM data frame, the VSYNC instruction arrives in the middle of the first PWM data frame or a second PWM data frame, and the VSYNC instruction is switched to the next display frame in the middle of the first PWM data frame or the second PWM data frame; or, in order to ensure the display effect, the gray data is updated after the current first PWM data frame or the second PWM data frame is displayed, and the display frame is switched to the next display frame;
2) and switching to the next display frame at the end point of the first PWM data frame or the second PWM data frame when the VSYNC command arrives at the end point of the first PWM data frame or the second PWM data frame.
Referring to fig. 5-6, each of which includes a transition frame command, as shown in fig. 5, two transition frame commands respectively appear in the middle of a high gray display frame (i.e., the display frame corresponding to the first gray data) and a low gray display frame, in which case M is not an integer but a decimal, i.e., a case where transition is directly performed in the middle of displaying the high gray display frame, i.e., the above-mentioned scene 1). In this case, the transition frame may be extended until the display of the high-gray display frame is completed, in which case M is an integer. Referring to fig. 6, the transition frame command is exactly in the middle of a high gray display frame, and the frame is changed after the high gray display frame is displayed, for which case M is an integer.
The principle is the same as described above for the transition frame command in the middle of the second gray data (i.e., the low gray data), which in this case results in
There is, and thus contains, a second gray scale data set that is not fully displayed.
Optionally, in the LED display screen grayscale display driving method, when a VSYNC instruction arrives, the method further includes two cases of resetting and not resetting the counter;
under the condition that the counter is reset, the next frame starts to display from the 1 st group of gray PWM data of the N groups of gray PWM data of the frame, and after the N groups of gray PWM data are displayed, the cyclic display is started from the 1 st group of gray PWM data of the N groups of gray PWM data of the frame;
under the condition that the counter is not reset, assuming that the current frame displays N groups of gray-scale PWM data and then displays the N groups of gray-scale PWM data until the x-1 group of the N groups of gray-scale PWM data of the frame is finished, the next frame starts to display from the x group of gray-scale PWM data in the N groups of gray-scale PWM data of the frame, wherein the value of x is [1, N ], and after the x-N groups of gray-scale PWM data are displayed, the 1 group of gray-scale PWM data of the N groups of gray-scale PWM data of the frame starts to display circularly until the frame is displayed. For example, in the case of taking N to 16, including 16 sets of gray PWM data, assuming that the display data of the current frame is 1-2-3 … … 16-1-2-3, i.e. 3 sets of gray PWM data (1, 2, 3) are additionally displayed, the gray data displayed in the next frame is displayed starting from the 4 th set of gray data of the next frame, i.e. 4-5-6-7 … … 16-1-2-3-4-5-6-7, i.e. the number of additionally displayed sets in the next frame is 4, 5, 6, 7.
In the above situation, no matter the counter is reset or not reset, a complete N groups of gray scale PWM data are necessarily displayed within one display frame period.
Optionally, in the case that 1 PWM channel controls a plurality of rows of LED lamps, one first PWM data frame includes first PWM data PWM of all rows, and one second PWM data frame also includes second PWM data PWM of all rows. Referring to fig. 7, with a 4-row example, the PWM for each row is determined by the data for each row. In this case, one high gray frame should include all 4 rows of high gray PWMs, and all 4 rows of low gray PWMs corresponding to the mth group of low gray. When only the high-gradation PWM is left after the low-gradation display is completed, the case is similar and only the low-gradation PWM is not included. Although there are several lines, for each LED lamp, in one display frame, the high gray frame and the low gray frame are continuously and repeatedly cycled at intervals in sequence until the next display frame comes.
The foregoing is illustrative of the preferred embodiments of this invention, and it is to be understood that the invention is not limited to the precise form disclosed herein and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the concept as disclosed herein, either as described above or as apparent to those skilled in the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (11)
1. The utility model provides a LED display screen grey scale display driver module which characterized in that includes:
a first PWM generating module (100) and a second PWM generating module (200), and a PWM synthesizing module (300) connected with the first PWM generating module (100) and the second PWM generating module (200);
in a display frame period, dividing corresponding gray scale data into first gray scale data displayed circularly and second gray scale data with a fixed group number N;
the first gray data and the N groups of second gray data are synchronously and respectively input into a first PWM (pulse width modulation) generation module (100) and a second PWM generation module (200), wherein the first gray data are input for N times in a circulating mode to obtain N groups of first PWM data and N groups of second PWM data;
the PWM synthesis module (300) synthesizes N groups of first PWM data and second PWM data into N groups of gray level PWM data and outputs and displays the data;
and in a display frame period, after the N groups of gray PWM data are displayed, sequentially and circularly displaying the first PWM data and the second PWM data until the display frame is finished.
2. The gray scale display driving module of claim 1, wherein the sequential cyclic display of the first PWM data and the second PWM data means sequential display from the 1 st gray scale PWM data to the nth gray scale PWM data of the N sets of gray scale PWM data.
3. The gray scale display driving module of claim 1 or 2, wherein the first gray scale data is high gray scale data, and the second gray scale data is low gray scale data.
4. The LED display screen gray scale display driving module according to any one of claims 1-3, wherein the PWM combining module (300) is configured with a counter for configuring the first PWM data and the second PWM data to generate different PWM data in different groups.
5. An LED display screen gray scale display driving method, which is implemented by using the LED display screen gray scale display driving module as claimed in any one of claims 1-4, wherein the method comprises:
step S100: dividing the gray scale data of each display frame into first gray scale data displayed in a circulating way and second gray scale data with a fixed group number N, wherein N is a fixed integer;
step S200: sending the first gray data into a first PWM (pulse-width modulation) generation module (100) to obtain first PWM data;
synchronously sending the second gray data to a second PWM generating module (200) to obtain second PWM data;
step S300: sending the first PWM data and the second PWM data into a PWM synthesis module (300) to obtain 1 group of PWM data;
repeating the steps S200-S300 for N times to obtain N groups of PWM data in one display frame period;
step S400: sequentially displaying the obtained N groups of PWM data in a display frame period T, wherein the display time periods of the N groups of PWM data are T0-Tn, and the residual time periods Tn-Td are not displayed, wherein T0 represents the starting time of the display frame period T, and Td represents the ending time of the display frame period T;
step S500: and circularly displaying the first PWM data and the second PWM data in turn within the residual time period Tn-Td until the display frame is finished.
6. The gray scale display driving method for the LED display screen according to claim 5, wherein the first gray scale data is high gray scale data, and the second gray scale data is low gray scale data;
correspondingly, the first PWM data is high-gray-scale PWM data, and the second PWM data is low-gray-scale PWM data.
7. The gray scale display driving method for the LED display screen according to claim 6, wherein the high gray scale data are identical and are cyclically displayed by the same high gray scale PWM data.
8. The method for driving grayscale display of LED display screen according to any one of claims 4-7, wherein the display frame period T includes M sets of first PWM data, and N + C
And a set of second PWM data, wherein the first PWM data and the second PWM data are sequentially displayed cyclically,
the number of times of circular display after the second gray scale data is displayed for N times is shown, and M is larger than N.
9. The method of claim 8, further comprising a method of switching between adjacent display frames, using VSYNC commands to switch the display frames, which comprises the following scenarios:
1) the VSYNC command arrives in the middle of a first PWM data frame or a second PWM data frame, and is switched to the next display frame in the middle of the first PWM data frame or the second PWM data frame; or, in order to ensure the display effect, the gray data is updated after the current first PWM data frame or the second PWM data frame is displayed, and the display frame is switched to the next display frame;
2) and switching to the next display frame at the end point of the first PWM data frame or the second PWM data frame when the VSYNC command arrives at the end point of the first PWM data frame or the second PWM data frame.
10. The method of claim 9, further comprising resetting and not resetting the counter when the VSYNC command arrives;
under the condition that the counter is reset, the next frame starts to display from the 1 st group of gray PWM data of the N groups of gray PWM data of the frame, and after the N groups of gray PWM data are displayed, the cyclic display is started from the 1 st group of gray PWM data of the N groups of gray PWM data of the frame;
under the condition that the counter is not reset, assuming that the current frame displays N groups of gray-scale PWM data and then displays the N groups of gray-scale PWM data until the x-1 group of the N groups of gray-scale PWM data of the frame is finished, the next frame starts to display from the x group of gray-scale PWM data in the N groups of gray-scale PWM data of the frame, wherein the value of x is [1, N ], and after the x-N groups of gray-scale PWM data are displayed, the 1 group of gray-scale PWM data of the N groups of gray-scale PWM data of the frame starts to display circularly until the frame is displayed.
11. The method for driving gray-scale display of LED display screen according to any one of claims 4-10, wherein for 1 PWM channel to control multiple rows of LED lamps, a first PWM data frame should contain all rows of first PWM data PWM, and a second PWM data frame should also contain all rows of second PWM data PWM.
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