CN116597774A - LED driving chip, LED display screen and display data compensation method - Google Patents

LED driving chip, LED display screen and display data compensation method Download PDF

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Publication number
CN116597774A
CN116597774A CN202310875142.1A CN202310875142A CN116597774A CN 116597774 A CN116597774 A CN 116597774A CN 202310875142 A CN202310875142 A CN 202310875142A CN 116597774 A CN116597774 A CN 116597774A
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display
gray
pwm
display data
value
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CN116597774B (en
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唐永生
黄立
申石林
刘阿强
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Chengdu Lipson Microelectronics Co ltd
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Chengdu Lipson Microelectronics Co ltd
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0271—Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)

Abstract

The application relates to an LED driving chip, an LED display screen and a display data compensation method, belongs to the field of LED display, and solves the problem of poor display effect caused by ash jump of the LED driving chip in the prior art. The LED driving chip is used for realizing PWM wave modulation of display data: the display data are distributed into M PWM display groups; the gray compensation value of one PWM display group in the M PWM display groups is W, W is not equal to 0, and the gray compensation values of the rest PWM display groups are D k ，k∈{1,2，……,M‑1}，D k >=0. The LED driving chip can solve the problem of ash jump and remarkably improve the display effect.

Description

LED driving chip, LED display screen and display data compensation method
Technical Field
The application relates to the field of LED display, in particular to an LED driving chip, an LED display screen and a display data compensation method.
Background
As shown in fig. 1, for the minimum display unit, the PWM rise and fall time is very large, and there is a difference between chips (and between channels), and the rise and fall times are not completely uniform, which results in different brightness of LED lamps driven by different chips when the gray value is small. In order to improve the display effect, the display data is usually subjected to equivalent compensation. The equivalent compensation is to compensate the gray scale values equally for all the display data assigned to the display groups, and as shown in fig. 2, the gray scale values for all the display groups assigned to the display data are compensated by 3 (hatched). However, this way of equivalent compensation will exacerbate the problem of gray jump during display.
The human eye's perceived characteristics of brightness conform to gamma curves, i.e., are more sensitive to changes in dark areas and less sensitive to changes in bright areas. For LED display, gamma correction is usually carried out on display data in an upper computer/control card, the mapped display data is obtained and then sent to an LED driving chip, and the LED driving chip generates PWM signals according to the mapped display data so as to control the display of an LED display screen. For gamma correction, when the gray value of the original display data is low, the size of the chip-level display data obtained after correction is basically consistent with that of the original display data, but when the gray value of the display data is high, the difference between the mapped display data and the original display data is large. For example, when the gray value of the original display data is less than 60, the gray value of the mapped display data is equal to the gray value of the original display data, when the gray value of the original display data is 100, the gray value of the mapped display data is 120, and when the gray value of the original display data is 101, the gray value of the mapped display data is 124. At this time, the gray values of the original display data differ by 1, but the gray values of the mapped display data differ by 3. When all display groups are compensated for the same gray compensation value, high gray is not sensitive to the increased gray value and therefore, the jump of gray will be more pronounced at low gray.
The above problems are to be solved.
Disclosure of Invention
The application aims to overcome the defects of the prior art and provides an LED driving chip, an LED display screen and a display data compensation method, so that the serious ash jump phenomenon during low ash is overcome, and the display effect of the display screen is improved.
The first aspect of the present application provides an LED driving chip for implementing PWM wave modulation of display data: the display data are distributed into M PWM display groups;
of the M PWM display groupsThe gray level compensation value of one PWM display group is W, W is not equal to 0, and the gray level compensation value of the kth PWM display group of the rest PWM display groups is D k ，k∈{1,2，……,M-1}，D k >=0。
Optionally, the gray compensation value W is a first fixed constant, and the gray compensation value D k Is a second fixed constant or adjustable;
or alternatively, the first and second heat exchangers may be,
the gray compensation value W is adjustable, and the gray compensation value D k Is a third fixed constant or adjustable.
Alternatively, when displaying the gray value T of the data<When=q, the gray compensation value W is a first fixed constant, the gray compensation value D k Is a second fixed constant or adjustable; wherein Q is a first gray threshold.
Optionally, when the gray value T > Q of the display data, the gray compensation values of the M PWM display groups are all adjustable;
wherein Q is a first gray threshold.
Alternatively, when the gray value T of the display data is >0, the gray compensation value of the first PWM display set is W;
the first PWM display group is a PWM display group with a fixed position, and the fixed position refers to that the PWM display group is a row display group corresponding to a fixed m-th subframe.
Alternatively, when the gray value T < = L of the display data, the display data is allocated into the first PWM display group;
when the gray value T > L of the display data, the display data is allocated to one or more display groups including the first PWM display group, and the gray value of the display data allocated to the PWM display group to which the display data is allocated is greater than or equal to L;
wherein L is a second gray level threshold.
Optionally, when the gray value L < T < n×l of the display data, the display data is allocated to the C1 PWM display groups;
when the gray value T > =N×L of the display data, the display data are distributed to N PWM display groups, and the gray value of the display data distributed by each display group in the N PWM display groups is larger than or equal to Z;
wherein C1 is an integer part of T/L, Z is an integer part of T/N, and N is the number of subframes of one frame of image.
Alternatively, when the gray value T < =q0 of the display data, the display data is allocated into the first PWM display group;
when the gray value T of the display data is more than Q0, the gray value of the display data of the first PWM display group is at least Q0; wherein Q0 is a centralized display threshold.
In a second aspect, the application provides an LED display screen comprising a display panel, and the LED display screen comprises an LED driving chip as described above.
A third aspect of the present application provides a display data compensation method, the method comprising:
distributing the display data into M PWM display groups;
the gray compensation value of one PWM display group in the M PWM display groups is W, and the gray compensation value of the kth PWM display group in the rest PWM display groups is D k ，k∈{1,2，……,M-1}，D k >=0。
Optionally, the gray compensation value W is a first fixed constant, and the gray compensation value Dk is a second fixed constant or adjustable; or, the gray compensation value W is adjustable, and the gray compensation value Dk is a third fixed constant or adjustable.
Optionally, when the gray value T < = Q of the display data, the gray compensation value of one of the M PWM display groups is a first fixed constant, and the gray compensation values of the remaining PWM display groups are a second fixed constant or adjustable;
when the gray level T > Q of the display data, the gray level compensation values of the M PWM display groups are adjustable.
The beneficial effects of the application are as follows:
compared with the prior art, the application provides the LED driving chip, the LED display screen and the display data compensation method, which are different from the same gray value compensation for each display group in the prior art, and the gray value of each display group allocated with display data is controllably compensated, so that the influence of ash jump can be reduced, particularly the problem of serious ash jump during low ash is avoided, and the display effect is remarkably improved.
Drawings
FIG. 1 is a schematic diagram of an ideal PWM versus an actual PWM;
FIG. 2 is a schematic diagram of gray value compensation for each display group in the prior art;
fig. 3 is a schematic diagram of gray value compensation for each display group according to an embodiment of the present application.
Detailed Description
The technical scheme of the present application is described in further detail below with reference to specific embodiments, but the scope of the present application is not limited to the following description.
Fig. 2 shows a schematic diagram of gray value compensation for each display group in the prior art. For different gray values, each PWM display Group to which display data is allocated compensates for the same gray value regardless of how many PWM (pulse width modulation-pulse width modulation) display groups (how many subframes) are actually divided, for example, as shown in fig. 2, one complete display frame is divided into four subframes (fig. 1 is only a row example, and groups 1 to 4 in fig. 1 refer to display groups in which a row is located on different subframes, in actual display, one complete subframe is composed of m display groups corresponding to m rows). Each PWM display Group (Group 1-Group 3) to which display data is allocated is additionally compensated for a gray value (hatched portion) of size 3. The gray value allocated to the first PWM display set (Group 1) is 4, the actual gray value is 7 after compensation, the gray value allocated to the second PWM display set is 3, the actual gray value is 6 after compensation, the gray value allocated to the third PWM display set is 4, and the actual gray value is 7 after compensation. Referring to fig. 1, in the actual display, the gray value is 1, the luminance may be only 0.2, the luminance may be only 0.6 when the gray value is 2, and the luminance may be only 1.6 when the gray value is 3. Taking the example of compensating the gradation value 3 for each display group to which the display data is assigned, when the gradation value of the display data is 11, the 3 display groups are assigned in a 4/4/3 manner, at this time, there is actually 15.8 luminance, when the gradation value of the display data is 12, the 3 display groups are assigned in a 4/4/4 manner, at this time, there is actually 16.8 luminance, and when the gradation value of the display data is 13, the 4 display groups are assigned in a 4/4/4/1 manner, at this time, there is actually 19.4 luminance, and the 4 display groups are assigned in a 4/4/4/2 manner, at this time, there is actually 20.4 luminance. It can be seen that 4/4/4 to 4/4/4/1, ash jump will be severe.
For this purpose, as shown in table 1, the present application proposes an LED driving chip for implementing PWM wave modulation of display data. The LED driving chip can receive the display data sent by the control card, generate PWM waves corresponding to the gray value of the display data according to the display data, and output constant current according to the PWM waves for lighting the corresponding lamp beads. The high level width of the PWM wave represents the lighting duration of the lamp bead.
As shown in fig. 3, the PWM wave modulation of the LED driving chip of the present application includes:
the display data are allocated into M PWM display groups (m=4 in table 1, fig. 3);
the gray compensation value of one PWM display group in the M PWM display groups is W, W is not equal to 0, and the gray compensation value of the kth PWM display group in the rest PWM display groups is D k ，k∈{1,2，……,M-1}，D k >=0。
Here, it can be understood that when m=1, the gray compensation value of the display group is W (where W may be a fixed constant or may be adjustable according to the display effect), and there is no other PWM display group, i.e., D k Is not present. When M>When=2, the gray compensation value of the kth display group of the rest PWM display groups (the number of groups is greater than or equal to 1) is D k . That is, at this time, the k-th display group of the M-1 PWM display groups other than the display group having the compensation value W among the M display groups to which the display data is assigned has the gradation compensation value D k ，k∈{1,2，……,M-1}，D k >=0。
In the present application, the display data may be display data obtained by gamma mapping the original data. Meanwhile, in the present application, M PWM display groups refer to the number of display groups of PWM display groups to which display data (for example, the total gray-scale value of the mapped display data is T) is actually allocated.
TABLE 1
Referring to table 1, taking t=15 as an example, the PWM display groups to which the display data are allocated are Group1, group3, group5, group6, that is, m=4. One skilled in the art will appreciate that in LED display, a frame of image is divided into a subframes (a=6 in table 1), and the display is performed on a subframe-by-subframe basis to complete the display of the entire frame of image. And each subframe comprises a plurality of PWM display groups, each PWM display group corresponds to part of display data of one row, and the sum of the display data corresponding to a certain row in all A subframes is equal to the total gray value of the row. The sum of the gray values of the M PWM display groups actually refers to the sum of the gray values of the display data of a certain line. Referring to fig. 2, fig. 2 includes 4 subframes (i.e., a=4), M PWM display groups refer to three display groups of groups 1-3, the three display groups are selected from the a display groups, display data are allocated to the three PWM display groups, that is, each of the three PWM display groups has a gray value different from 0, and the sum of gray values is T before compensation. In table 1, 6 subframes are divided. In the present application, the display data is preferably expressed by an integer, that is, the minimum unit of the display data is 1, regardless of the total gradation data, the gradation data allocated to each group, or the compensated gradation data.
For the M PWM display groups allocated with display data, gray value compensation is performed on the M PWM display groups in this embodiment to avoid the influence of gray jump on the display effect, thereby improving the display effect.
Specifically, for M PWM display groups, the gray-scale compensation value of 1 display group is set to W, and the other display groups (if any, i.e., if M>1, note that M is necessarily an integer) has no correlation with W, i.e., D k Independent of W, D k Is not affected by the value of W. Taking Table 1 as an example, in this case, the Group1 gray scaleThe compensation value is W, and other group gradation compensation values to which display data is assigned are independent of W and are not affected by it. The embodiment is different from the condition that the compensation values of the PWM display groups are equal and are not independent of each other in the prior art, so that the problem of ash jump caused by equivalent compensation can be avoided, and particularly the influence on low ash is avoided.
In the present application, the number of groups to which display data is assigned is not fixed. That is, the aforementioned M is not fixed for display data of different gradation values. For example, assuming that the gradation value of the display data is 20, m may be selected to be 4, and each group is assigned a gradation value of 5; while the gray value of the display data is 25, m is optionally 5, and the gray value assigned to each group is also 5. In the application, the selectable A display groups are named as a first display Group (Group 1), a second display Group (Group 2), … … and an A display Group (Group A) from left to right. The M display groups may be any M display groups out of the a display groups, or may be fixed M display groups, which means that if m=2, the first display group, the second display group, or the first display group and the third display group are fixedly selected. Correspondingly, if m=3, those two groups when m=2 must be included in the 3 groups. The specific groups that are fixed in the present application are not limited herein.
In some embodiments, the gray scale compensation values in the remaining M-1 PWM display groups, except for the display group having compensation value W, are equal, i.e., D 1 =D 2 =D 3 。
In some embodiments, the gray compensation value W is a first fixed constant, and the gray compensation value D k Is a second fixed constant or adjustable; or, the gray compensation value W is adjustable, the gray compensation value D k Is a third fixed constant or adjustable.
In this embodiment, when M is greater than or equal to 2 (when m=1, the gray-scale compensation value is W, W may be a first fixed constant set in advance, or may be adjusted according to the display effect), there are several possibilities:
the gray compensation value of one display group is W, and is a first fixed constant F1, and the gray compensation values of other PWM display groups are second fixed constantsF2. Namely D k =f2, in table 1, D 1 =D 2 =D 3 。
For different display data, as shown in table 2, when the allocated gray values are respectively 4, 4 and 3, respectively 3, 1 and 1 are compensated; or the distribution data is 4, 4 and 4, and 3, 1 and 1 are respectively compensated; or the allocation data is 4, 1, 4, respectively compensating 3, 1. It is obvious that, here, no matter how many gray values of the display data are input by the driving chip receiving the control card, no matter how many display groups are allocated to the display data, after the display data are allocated to M groups, the compensation value of 1 display Group (Group 1 here) is necessarily W (3 here), the compensation value of the other display groups is constant 1, and if the other display groups exceed 2 groups, the compensation value of the other display groups is equal to 1. The fixed constant here may be pre-configured.
TABLE 2
(2) The gray scale compensation value of one display set is W, which is a first fixed constant, and the gray scale compensation values of the other PWM display sets are adjustable.
That is, the gray value of one of the display groups (Group 1 in table 3) is a fixed value, for example, W is 3, which is configured in advance, and the gray compensation values of the other display groups can be adjusted according to the display effect. In other display groups, the gray values of the respective display groups may be independently adjusted according to the display effect, for example, in fig. 3 or table 1, D2, and D3 may be independently adjustable, or D1, D2, and D3 may be equal and may be adjustable in size. As another example, in Table 3, D 15,1 、D 15,2 、D 15,3 、D 16,1 、D 16,2 、D 16,3 、D 17,1 、D 17,2 、D 17,3 、D 17,4 Are independently adjustable; as shown in table 4, the gray scale values of the other display groups may be D and D may be adjusted. Regardless of whether the compensation values between other display groups are independent or not, the implementationIn this way, the gray value of one display group is a fixed value W, which means that, regardless of the gray value of the display data received by the driving chip, the gray compensation value of one display group must be equal to a first fixed constant, for example, 3, which is configured in advance, among the M display groups to which it is allocated. While the gray-scale compensation values of the other display sets are independent of the first fixed constant and are adjusted according to the display effect.
TABLE 3 Table 3
TABLE 4 Table 4
The gray scale compensation value W of one display group is adjustable, and the gray scale compensation values of the other display groups are third fixed constants F3. In this way, for example, group1 adjusts the compensation value according to the display effect, and the gray values of the other display groups are all set to 5 in advance. Of course, similarly, the gray scale compensation value of one display Group may be adjustable, regardless of the gray scale value, wherein the compensation value of one display Group, for example, group1, is equal and the value is adjustable, or the compensation value of Group1 may be unequal and the value is adjustable. For other display groups, the gray values of other display groups are shown in table 4, and the compensation values of all display groups are D, which is a fixed constant configured in advance.
The gray-scale compensation value W of one display set is adjustable, and the gray-scale compensation values of the other display sets are also adjustable.
That is, the gray compensation value of any one display group is not fixed in advance, and all the gray compensation values of the display groups can be adjusted according to the display effect. The mode has the greatest flexibility and can obtain the best display effect. But the adjustment requirements are high. For example, in table 4, the compensation values of Group1 are all W, the compensation values of the other groups are all D, and W and D are adjusted according to the display effect.
In some embodiments, when displaying the gray value T of the data<When=q, the gray compensation value W is a first fixed constant, the gray compensation value D k Is a second fixed constant or adjustable; wherein Q is a first gray threshold.
In this embodiment, the case of low ash is particularly pointed out. When the gray value of the display data received by the driving chip belongs to low gray, namely the gray value is not larger than a preset first gray threshold value, at the moment, M PWM display groups are limited to adopt the 1 st to 2 nd schemes. That is, for low gray data, there are 1 display groups among the M PWM display groups, and the gray compensation value thereof is necessarily the aforementioned first fixed constant. The compensation values of other display groups are independent of the gray compensation values of the display groups, and the mode can ensure that no jump gray exists basically when the gray is low.
Further, when the gray value T > Q of the display data, the gray compensation values of the M PWM display groups are all adjustable; wherein Q is a first gray threshold.
When the gray value of the display data is larger than a certain threshold value, the gray compensation value of one display group is not limited to be fixed. In this scheme, when the gray value T is less than or equal to Q, there must be a display set gray compensation value of a first constant (i.e. Wfixed, D k Adjustable or fixed), when the gray value T is greater than Q, the gray compensation values of the respective display groups are adjusted according to the display effect (i.e., W and D regardless of the value of M k Are all adjustable). Of course, the gray compensation values of the display groups may be the same and adjustable, or may be adjusted independently of each other.
In some embodiments, when the gray value T of the display data is >0, the first PWM display group is assigned display data and has a gray compensation value W; the first PWM display group is a PWM display group at a fixed position, and the PWM display group at the fixed position refers to a row display group corresponding to a subframe at the fixed position. For example, in tables 2-7, the first PWM display Group is Group1 in the 1 st fixed subframe (here, group2 is in the 2 nd subframe).
As previously described, the alternative A display sets (6 display sets in tables 1-6) are designated from left to right as Group1, group2, group3, group4, group5, group6. In the present embodiment, a certain display Group is fixedly selected, for example, the 1 st display Group1 in table 2 to table 6, the display Group is necessarily allocated with display data regardless of the display data gradation value T, and the gradation compensation value of the display Group is necessarily W. At this time, the compensation values of all the first PWM display sets are the same whether they are adjustable or not. In this case, alternatively, for a display groups to which data can be allocated, each of the display groups (Group 2, group3, group4, group5, group6 in table 4) other than the first PWM display Group is selected as d_i as long as the display Group has allocated data, regardless of the gray-scale value of the display data. For example, in Table 4, for data 15 through 17, group3 always takes the value D_2, e.g., 2, while Group5 always takes the value D_4, e.g., 3.
For the gray value T of the display data<When=q, the gray compensation value W is a first fixed constant, the gray compensation value D k For a second fixed constant or adjustable, when displaying the gray value T of the data>In Q, the gray compensation values of the M PWM display groups are adjustable, which is equivalent to T<When=q, W is a fixed constant, when T>At Q, W is adjustable. Meanwhile, here, the first PWM display Group (e.g., group 1) may also be set to have a gray-scale value of W. That is, T<When=q, group1 distributes display data and the gray compensation value is a fixed constant F1, T>Group1 is assigned display data at Q and the gray scale compensation value is adjustable.
In some embodiments, when the gray value T < = L of the display data, the display data is assigned into the first PWM display set;
when the gray value T > L of the display data, the display data is allocated to one or more display groups including the first PWM display group, and the gray value of the display data allocated to the PWM display group to which the display data is allocated is greater than or equal to L; wherein L is a second gray level threshold.
The present embodiment relates to how display data is allocated to the M display groups. First, a threshold value L is preset, and when the display data T is not greater than the threshold value, the display data are all allocated to the first PWM display group. At this time, m=1. The gray scale compensation value of the first PWM display set is W. When the gradation value T of the display data is greater than the threshold value L, the display data may be allocated to one or more display groups, and at this time, it is necessary to allocate in such a manner that the gradation value of the allocated display data (excluding the compensation value) is not less than L among the display groups to which the display data is allocated.
As shown in table 5, taking l=4 as an example, if T is in the range of 1 to 4, the display data is uniformly allocated to the first PWM display Group (Group 1). If t=5 to 7, in order to ensure that the gradation value of the display data allocated to the display group to which the display data is allocated is not less than 4, the display data can be allocated only to the first PWM display group. If t=8, the display data may be allocated to only the first PWM display group or to two PWM display groups (including the first PWM display group), and the gradation value of each PWM display group is 4 (excluding the compensation value). In general, for the display effect, the distribution is selected to be performed in a more uniform manner, and thus the display data is selected to be distributed to two PWM display groups, each of which is distributed 4.
TABLE 5
In some embodiments, when the gray scale value L < T < n×l of the display data, the display data is allocated to the C1 PWM display groups;
when the gray value T > =N×L of the display data, the display data are distributed to N PWM display groups, and the gray value of the display data distributed by each display group in the N PWM display groups is larger than or equal to Z;
where C1 is the integer part (quotient) of T/L, Z is the integer part (quotient) of T/N, and N is the number of subframes of a frame of image. Here, T/l=c1 … C2, i.e. c1×l+c2=t. T/n=z … K.
In order to achieve the display effect, the present embodiment provides a display data allocation principle, which can ensure that no display group is allocated with a gray value smaller than a threshold L (except that the total gray value of the display data is smaller than or equal to L), and ensure the uniformity of allocation. Here, the number of subframes of one frame image is N, and is actually a.
The gray scale value L < T < n×l of the display data, which is larger than the threshold value L, is not enough to make the gray scale values of the display data allocated to the N display groups at least L. At this time, a partial display group may be selected from the N display groups, and the gray value of the display data allocated to the partial display group is not smaller than L. For example, as shown in table 5, when l=4 and n=6, 1 display group is selected and the gradation value of the display data allocated thereto is 6 if the gradation value t=6. If the gray value t=9, 2 display groups are selected, the gray value of the display data allocated to 1 display group is 5, and the gray value of the display data allocated to the other display group is 4. If the gray value t=12, 3 display groups are selected, and each display group is assigned a gray value of 4.
When the gray level T > =n×l of the display data, the gray level of the display data is large enough to ensure that the gray level of the display data allocated to each display group is at least L. In practice, the gray scale value of the display data assigned to each display group may be at least Z, Z being an integer fraction of T/N. Let K be the remainder of T/N, i.e., T/n=z … K. Display data with the gray value of Z can be allocated to each display group, and the remaining display data with the gray value of K can be uniformly allocated to one display group or a plurality of display groups can be selected for random allocation.
Still taking l=4 and n=6 as an example, as in table 6, when t=26, z=4 and k=2, the gray values of the display data in Group1 and Group2 are both 4+1, and of course, the gray values of the display data in Group1 may be 4+2=6, and the gray values of the other 5 display groups are all 4.
TABLE 6
In some embodiments, when the gray value T < = Q0 of the display data, the display data is assigned to the first PWM display group;
when the gray value T of the display data is more than Q0, the gray value of the display data of the first PWM display group is at least Q0;
wherein Q0 is a centralized display threshold.
The present embodiment proposes another allocation principle of display data. And setting a centralized display threshold Q0, and uniformly distributing display data to the first PWM display group when the gray-scale value is not greater than the centralized display threshold. When the gray value is greater than the centralized display threshold, then the display data may be allocated to one or more PWM display groups, and it is necessary to ensure that the display data allocated to the first PWM display group is not less than Q0. For example, as shown in table 7, if t0=8, if T falls within the range of 1 to 8, the display data is assigned to the first PWM display Group (for example, group 1), and if t=9, the display data assigned to the first PWM display Group may be 9, or the display data assigned to the first PWM display Group may be 8, and the gradation value of the display data assigned to one display Group (for example, group 3) may be 1. If t=10, the display data allocated to the first PWM display Group may be 10, the display data allocated to the first PWM display Group may be 8, the gradation value of the display data allocated to one display Group (for example, group 3) may be 2, the display data allocated to the first PWM display Group may be 8, and the gradation values of the display data allocated to the two display groups (for example, group3 and Group 5) may be 1.
TABLE 7
Also, further, in some embodiments of the present application, for display uniformity, when judging the gray value of the display data, when 0<T-q0< = L (N-1), the x represents the multiplier, then V1 display groups are selected from N-1 display groups (excluding the first PWM display Group to which the initial display data of the size Q0 is allocated, group1 in table 7), and the initial display data is allocated to each of these V1 display groups, where the gray value of the initial display data is L, and L is a second gray threshold value set in advance, which is smaller than Q0. Where V1 is the integer part (quotient) of (T-Q0)/L. If (T-Q0)/L has a remainder portion denoted by V2, the display data (gradation value size V2) of the portion can be uniformly distributed to any one or more of the N display groups. For example, the remainder portion is directly assigned to the first PWM display group. The total gray value of the first PWM display set will be equal to q0+v2 (compensation values are not considered). When T-Q0> L (N-1) and T < Q0 x N (i.e., T-Q0< Q0 x (N-1)), then initial display data of size V3 is allocated to each of N-1 display groups other than the first PWM display group to which initial display data of size Q0 is allocated, where v3= (T-Q0)/(N-1) quotient (integer part). If (T-Q0)/(N-1) has a remainder portion denoted by V4, the display data of the portion (gradation value size V4) can be uniformly distributed to any one or more of the N display groups. For example, the remainder portion is directly assigned to the first PWM display group.
In some embodiments, when T > =q0×n, the following manner may be selected for display data allocation: the gray scale value of the display data allocated in the N-1 display groups is X, and the gray scale value of the display data allocated in the 1 display groups is X+Y. Where T/n=x … Y.
In some embodiments, the display data with the size Y is not directly allocated to 1 group, but is scattered and allocated to a plurality of display groups.
In a second aspect of the application, an LED display screen is provided. The LED display screen comprises a display panel and further comprises the LED driving chip in the first aspect.
In a third aspect of the present application, there is provided a display data compensation method comprising:
distributing the display data into M PWM display groups;
the gray compensation value of one PWM display group in the M PWM display groups is W, and the gray compensation value of the kth PWM display group in the rest PWM display groups is D k ，k∈{1,2，……,M-1}，D k >=0。
Similarly, when m=1, the group compensation value is W, and when M is greater than 1, the other display group compensation values are D k . The functions/descriptions of the present embodiment corresponding to the LED driving chip portion described in the first aspect are the same, and are not described in detail herein.
In some embodiments, the gray compensation value W is a first fixed constant, and the gray compensation value D k Is a second fixed constant or adjustable;
or alternatively, the first and second heat exchangers may be,
the gray compensation value W is adjustable, and the gray compensation value D k Is a third fixed constant or adjustable.
The LED driving chip according to the present embodiment and the first aspect described above relates to the gray scale compensation value W and the gray scale compensation value D k The corresponding functions/descriptions are the same and are not described in detail herein.
In some embodiments, when the gray value T < = Q of the display data, the gray compensation value of one of the M PWM display groups is a first fixed constant, and the gray compensation values of the remaining PWM display groups are a second fixed constant or adjustable;
when the gray level T > Q of the display data, the gray level compensation values of the M PWM display groups are adjustable.
That is, when the display data belongs to low gray, then the compensation value of one of the display groups may be set to be fixed (the display group may be one of the display groups of the fixed positions as described above). While the compensation values of the other display sets (if any) are either another fixed constant or are adjustable. When the number of the other display sets is greater than 1, the compensation values of the other display sets may be selected to be the same. When the gradation value of the display data is slightly high, at this time, the gradation compensation values of the display groups to which the display data is assigned are adjustable independently of each other, and it is no longer necessary to set a certain group to be a fixed constant.
As described in the foregoing first aspect, the display Group whose compensation value is set to the fixed value W may be one display Group of a fixed position, such as Group1 is selected so that its gradation compensation value is the first fixed constant W, regardless of the gradation value.
The foregoing is merely a preferred embodiment of the application, and it is to be understood that the application is not limited to the form disclosed herein but is not to be construed as excluding other embodiments, but is capable of numerous other combinations, modifications and environments and is capable of modifications within the scope of the inventive concept, either as taught or as a matter of routine skill or knowledge in the relevant art. And that modifications and variations which do not depart from the spirit and scope of the application are intended to be within the scope of the appended claims.

Claims (12)

1. An LED driving chip, characterized by PWM wave modulation for realizing display data:
the display data are distributed into M PWM display groups;
the gray compensation value of one PWM display group in the M PWM display groups is W, W is not equal to 0, and the gray compensation value of the kth PWM display group in the rest PWM display groups is D k ，k∈{1,2，……,M-1}，D k >=0。
2. The LED driver chip of claim 1, wherein,
the gray compensation value W is a first fixed constant, and the gray compensation value D k Is a second fixed constant or adjustable;
or alternatively, the first and second heat exchangers may be,
the gray compensation value W is adjustable, and the gray compensation value D k Is a third fixed constant or adjustable.
3. The LED driver chip of claim 1, wherein,
when displaying the gray value T of the data<When=q, the gray compensation value W is a first fixed constant, the gray compensation value D k Is a second fixed constant or adjustable; wherein Q is a first gray threshold.
4. An LED driver chip according to claim 3, wherein,
when the gray level T > Q of the display data, the gray level compensation values of the M PWM display groups are adjustable.
5. An LED driver chip according to any of claims 1-3, wherein,
when the gray value T of the display data is more than 0, the gray compensation value of the first PWM display group is W;
the first PWM display group is a PWM display group at a fixed position, and the PWM display group at the fixed position refers to a row display group corresponding to a subframe at the fixed position.
6. The LED driver chip of claim 5, wherein the LED driver chip comprises a plurality of LED driver chips,
when the gray value T < = L of the display data, the display data is allocated into the first PWM display group;
when the gray value T of the display data is greater than L, the display data is distributed to one or more PWM display groups including a first PWM display group, and the gray value of the display data distributed by the PWM display group distributed with the display data is greater than or equal to L; wherein L is a second gray level threshold.
7. The LED driver chip of claim 6, wherein:
when the gray value L < T < N x L of the display data, the display data is distributed into C1 PWM display groups;
when the gray value T > =N×L of the display data, the display data are distributed to N PWM display groups, and the gray value of the display data distributed by each display group in the N PWM display groups is larger than or equal to Z;
wherein C1 is an integer part of T/L, Z is an integer part of T/N, and N is the number of subframes of one frame of image.
8. The LED driver chip of claim 5, wherein:
when the gray value T < = Q0 of the display data, the display data is allocated to the first PWM display group;
when the gray value T of the display data is more than Q0, the gray value of the display data of the first PWM display group is at least Q0; wherein Q0 is a centralized display threshold.
9. An LED display screen comprising a display panel, characterized in that the LED display screen comprises an LED driving chip according to any of claims 1-8.
10. A display data compensation method, comprising:
distributing the display data into M PWM display groups;
the gray compensation value of one PWM display group in the M PWM display groups is W, and the gray compensation value of the kth PWM display group in the rest PWM display groups is D k ，k∈{1,2，……,M-1}，D k >=0。
11. The method for compensating display data according to claim 10, wherein,
the gray compensation value W is a first fixed constant, and the gray compensation value D k Is a second fixed constant or adjustable;
or alternatively, the first and second heat exchangers may be,
the gray compensation value W is adjustable, and the gray compensation value D k Is a third fixed constant or adjustable.
12. The method for compensating display data according to any of claims 10 to 11,
when the gray level value T < = Q of the display data, the gray level compensation value of one display set in the M PWM display sets is a first fixed constant, and the gray level compensation values of the other PWM display sets are a second fixed constant or adjustable;
when the gray level T > Q of the display data, the gray level compensation values of the M PWM display groups are adjustable.
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