CN111261075A

CN111261075A - Pixel driving method

Info

Publication number: CN111261075A
Application number: CN202010106947.6A
Authority: CN
Inventors: 谢建峰; 熊克
Original assignee: Fujian Huajiacai Co Ltd
Current assignee: Fujian Huajiacai Co Ltd
Priority date: 2020-02-20
Filing date: 2020-02-20
Publication date: 2020-06-09
Anticipated expiration: 2040-02-20
Also published as: CN111261075B

Abstract

A pixel driving method comprises the following steps of detecting the Data signal change condition of a Data line of a panel, and increasing the voltage value of a high absolute value gray scale signal of a sub-pixel with negative polarity if the Data signal is changed from a low absolute value signal to a high absolute value signal when the Data signal is detected to be changed; when the data signal is changed from a high absolute value signal to a low absolute value signal, the voltage value of the low absolute value gray scale signal of the sub-pixel with the negative polarity is reduced. The Data lines are Data signal lines, and different from the prior art, the technical scheme improves the coupling phenomenon of positive and negative Data to VCOM by adjusting the gamma values of RGB sub-pixels, improves the horizontal crosstalk phenomenon, and enables the display effect of the Demux liquid crystal display screen to be better.

Description

Pixel driving method

Technical Field

The invention relates to the field of pixel driving, in particular to a pixel driving method design.

Background

For the Demux lcd, due to the manufacturing problem of Demux TFT, the on-current of Demux TFT may be different, and the conventional lcd may cause some abnormal phenomena in the display of Demux lcd. The phenomenon of abnormal display shown in fig. 1 is referred to as a problem of horizontal crosstalk.

Disclosure of Invention

Therefore, it is desirable to provide a new pixel driving method to achieve the technical effect of solving the horizontal crosstalk problem.

In order to achieve the above object, the present invention provides a pixel driving method, including the steps of detecting a change in a Data signal of a Data line of a panel, and increasing a voltage value of a high absolute value gray scale signal of a sub-pixel having a negative polarity when the change in the Data signal is detected and the Data signal is changed from a low absolute value signal to a high absolute value signal or the Data signal is changed from a high absolute value signal to a low absolute value signal.

Specifically, when a change in the data signal is detected, the voltage value of the high absolute value gray scale signal of the R, B sub-pixel having negative polarity is increased when the data signal is changed from the low absolute value signal to the high absolute value signal or when the data signal is changed from the high absolute value signal to the low absolute value signal.

The Data lines are Data signal lines, and different from the prior art, the technical scheme improves the coupling phenomenon of positive and negative Data to VCOM by adjusting the voltage values of RGB sub-pixels, improves the horizontal crosstalk phenomenon, and enables the display effect of the Demux liquid crystal display screen to be better.

Drawings

FIG. 1 is a diagram illustrating a diagram for detecting a display screen according to an embodiment;

FIG. 2 is a schematic diagram of an NMOS type according to an embodiment;

FIG. 3 is a diagram of a demux architecture according to an embodiment;

FIG. 4 is a schematic diagram illustrating a relationship between current and voltage of a TFT according to an embodiment;

FIG. 5 is a schematic diagram of the bright line 1 according to an embodiment;

FIG. 6 is a schematic diagram of the bright line 2 according to an embodiment;

FIG. 7 shows an example of eliminating bright line 1 according to an embodiment;

fig. 8 shows an example of eliminating the bright line 2 according to the embodiment.

Detailed Description

To explain technical contents, structural features, and objects and effects of the technical solutions in detail, the following detailed description is given with reference to the accompanying drawings in conjunction with the embodiments.

Referring to fig. 1, this figure is a diagram commonly used for performance testing of display screens. The normal display case includes a 127 gray portion at the periphery and a 255 white portion in the middle. For the Demux lcd panel, due to the manufacturing problem of the Demux TFT, the on-current of the Demux TFT may be different, so that the display of the Demux lcd panel may have some abnormal phenomena. In the case of anomalous displays, we call horizontal crosstalk.

In the embodiment shown in fig. 2, the Source/Drain determination of the NMOS type TFT is described, where current flows from high voltage to low voltage, the NMOS carriers are electrons, and the electron flow is opposite to the current direction, i.e. the high voltage side is Drain and the low voltage side is Source.

FIG. 3 is a schematic diagram of charging a Demux, in which a Source Line is connected to an IC (main control chip) to transmit a voltage signal from the IC to a Demux LCD, the voltage of 127 gray scales is generally + -2.6V, the voltage of 255 gray scales is generally + -5V, the on-voltage of the Demux is VGH (generally 15V), and a parasitic capacitor C exists between the Data Line and the voltage on the VCOM chip_{Parasitic element}。

In the case of fig. 3(a), when the Source Line (Source signal Line) is initially charged to the Data Line (Data signal Line) and the Data Line cannot be charged to the +255 gray level, it can be determined from fig. 1 that the Source and the drain are the Source of the TFT and the Source Line is the drain of the TFT, then Vgs in the case of (a) is first Vgs ═ VGH-2.6V, and finally the Data Line is gradually charged, and the voltage of the Data Line gradually increases and Vgs ═ VGH-5V when the maximum voltage of the Data Line reaches +255 gray level.

In the case of fig. 3(b), since the Data Line voltage is greater than the Source Line voltage, the Source Line voltage is always charged to the Data Line, and during the charging process, the Source Line voltage is the minimum, the Source Line end is the Source of the TFT, the Data Line end is the drain of the TFT, and Vgs ═ VGH- (-5) V in the case of (b); .

In the case of fig. 3(c), since the voltage on the Source Line is to be charged to the Data Line, the voltage on the Source Line is originally lower than the Data Line, the Source Line charges the Data Line, the voltage of the Source Line is the minimum during the charging process, the Source Line end is the Source of the TFT, the Data Line end is the drain of the TFT, and Vgs in the case of (c) is VGH- (2.6) V.

In the case of (3d), when the Data Line is initially charged to the Data Line and the Data Line cannot be charged to the gray level of-127, the Data Line voltage is lower than the Data Line voltage, the end of the Data Line is the drain of the TFT, the end of the Data Line is the Source of the TFT, Vgs in the case of (3d) is Vgs ═ VGH- (-5) V, and finally the Data Line is gradually charged, the Data Line voltage gradually increases, and when the Data Line voltage reaches the gray level of-127, Vgs ═ VGH- (-2.6) V.

In view of the above, it is desirable to provide,

in fig. 3(a), Vgs ═ VGH-2.6V → Vgs ═ VGH-5V;

vgs ═ VGH- (-5) V in fig. 3 (b);

vgs ═ VGH- (2.6) V in fig. 3 (c);

in fig. 3(d), Vgs ═ VGH- (-5) V → Vgs ═ VGH- (-2.6) V;

as can be seen from the schematic diagram of the relationship between the TFT current and the voltage in FIG. 4, the larger Vgs, the larger Ion, and therefore I_(b)>I_(d)>I_(c)>I_(a)。

Referring to fig. 5, the principle of bright line 1 generation is shown, wherein the Demux TFT is turned off at time t1 based on Column Inversion (a display driving mode), the vertical axis represents gray scale voltage, the horizontal axis represents time, and VCOM is ideally a stable dc voltage. Referring to (c) and (d) in FIG. 3, I can be understood_(3d)>I_(3c)In FIG. 5, when the voltage on the positive polarity Data Line is to be changed from +255 gray scale to +127 gray scale, the on-state current I of the TFT of the Demux subpixel of the positive polarity Data Line is controlled at this time₊on＝I_(c)When the negative polarity Data Line is changed from-127 gray scale to-255 gray scale, the on-state current I-on-I of the TFT controlling the Demux of the negative polarity Data Line_(d)Then I + on<And I-on. Therefore, when the TFT of the Demux is turned off, the positive voltage is charged without reaching the required voltage levelBit and a negative voltage can be charged to the required voltage. For example, the Data Line is to be changed from +127 gray level (generally +2.6V) to +255 gray level (generally +5V), and finally the Data Line cannot be charged to +255 gray level (generally +5V) because I + on is small; the Data Line needs to be changed from-127 gray scale (generally-2.6V) to-255 gray scale (generally-5V), and finally the Data Line can be filled to-255 gray scale due to the fact that I-on is large; thus, there will be d1<d2 (i.e. | V2>I.e., the voltage variation amount when the Data Line is changed from the +127 gray scale voltage to the +255 gray scale voltage is smaller than the voltage variation amount when the Data Line is changed from the-127 gray scale voltage to the-255 gray scale voltage.

In summary, the Data Line with negative polarity can be charged to the required voltage level, the Data Line with positive polarity and the Data Line with negative polarity can not be charged to the required voltage level, and therefore, the voltage changes of the Data Line voltages with positive polarity and negative polarity during charging can not be mutually offset, and therefore the Data Line passes through C_{Parasitic element}The coupling of parasitic capacitances to the VCOM cannot cancel each other out either, and generally speaking, the VCOM will be coupled down by the negative polarity Data Line, and thus the final voltage of the VCOM will be generally biased down. Thus, the voltage difference between the positive polarity Pixel electrode and the VCOM is larger than the voltage difference between the negative polarity Pixel electrode and the VCOM, i.e. the actual VCOM voltage ≠ ideal VCOM voltage, and a bright line is generated on the display screen.

The principle of the generation of the bright line 2 is explained in the embodiment of fig. 6, which is explained according to the principle explained in fig. 5, when d3 is present<d4 (i.e. | V2>V1|), as in the principle generated by the bright Line 1 in fig. 5, the negative polarity Data Line can be charged to the required voltage level, the positive polarity Data Line cannot be charged to the required voltage level, the voltage changes of the positive and negative polarity Data Line voltages during charging cannot be mutually offset, and the Data Line is charged through C_{Parasitic element}The coupling effect of the parasitic capacitances to VCOM cannot cancel each other out, and in the case of fig. 6, the VCOM voltage is coupled up (with the negative polarity Data Line voltage up), thereby causing the voltage difference between the voltage of the positive polarity Pixel electrode and VCOM to be smaller than that between the voltage of the negative polarity Pixel electrode and VCOM, i.e., the actual VCOM voltage ≠ ideal VCOM voltage, thereby causing display of bright Line 2.

After the above analysis, a method of driving a pixel is performed, in which a change in a Data signal of a Data line of a panel is detected, and when the change in the Data signal is detected, the voltage value of a high absolute value gray-scale signal of a sub-pixel having a negative polarity is increased when the Data signal is changed from a low absolute value signal to a high absolute value signal or when the Data signal is changed from a high absolute value signal to a low absolute value signal.

The sub-pixel here may be any one of RGB type sub-pixels, and in some display panels, whether the sub-pixel is positive or negative is determined by the voltage of a signal line connected to the sub-pixel. Therefore, different types of sub-pixel adjustment can be performed based on the above scheme. Specifically, when a change in the data signal is detected, the voltage value of the high absolute value gray scale signal of the R, B sub-pixel having negative polarity is increased when the data signal is changed from the low absolute value signal to the high absolute value signal or when the data signal is changed from the high absolute value signal to the low absolute value signal. For sub-pixels of a particular type only

In the embodiment shown in FIG. 7, which shows the embodiment of eliminating the bright line 1, in FIG. 7(a), when the 127 gray scale is transited to the 255 gray scale (refer to FIG. 1), the absolute value voltage difference between the 127 gray scale and the 255 gray scale of the negative polarity R/B is d2 ', the absolute value voltage difference between the 127 gray scale and the 255 gray scale of the positive polarity R/G/B is d1, the absolute value voltage difference between the 127 gray scale and the 255 gray scale of the negative polarity G is d2, and there are d2> d1> d 2'.

In fig. 7(B), Demux R is turned on when the Data voltage Data is transited from 127 gray to 255 gray, the VCOM voltage is coupled upward and then slowly approaches to the vicinity of bestmom because d1> d 2', that is, the absolute value of the voltage change when the positive polarity R/G/BData voltage is changed from 127 gray to 255 gray is greater than the absolute value of the voltage change when the negative polarity R/G/B Data voltage is changed from-127 gray to-255 gray, when Demux G is turned on, the VCOM voltage is not adjusted because the sub-pixel voltage 255 gray, that is, d1< d2, the absolute value of the voltage change of negative polarity is greater than the absolute value of the voltage change of positive polarity G pixel Data, so that the VCOM deviates downward from the bezt VCOM as a whole and then slowly approaches to the vicinity of bestmom when Demux G is turned on, and when Demux is turned on (as when Demux R is turned on), the VCOM voltage change is not coupled upward and thus the VCOM voltage is not gradually approaches to the vicinity of bestmom when Demux G Data is turned on, when Demux R is turned on (when Demux R is turned on), the VCOM voltage change is again coupled to the vicinity of bezom, and when Demux R is turned on, the VCOM voltage change is again coupled to the voltage change of the voltage of the VCOM < 76, thus the VCOM, whereby the VCOM voltage is not generated gradually coupling is again, whereby the VCOM line is not generated and thus the voltage of the.

In the embodiment shown in fig. 8, which shows the embodiment of eliminating the bright line 2, in fig. 8(a), when the 255 gray scale is transited to the 127 gray scale (refer to fig. 1), the absolute value voltage difference between the 255 gray scale and the 127 gray scale of the negative polarity R/B is d4 ', the absolute value voltage difference between the 255 gray scale and the 127 gray scale of the positive polarity R/B is d3, the absolute value voltage difference between the 255 gray scale and the 127 gray scale of the negative polarity G is d4, and there are d4> d3> d 4'.

Numerically, d1 ═ d3, d2 ═ d4, and d2 ═ d 4'.

In fig. 8(B), when the Data voltage is transited from 255 gray to 127 gray, the Demux R is turned on, so that the VCOM voltage is coupled downward and then slowly approaches to the vicinity of Best VCOM (ideal on-chip voltage) because d3> d4 'is larger than the absolute value of the voltage change from-255 gray to-127 gray when the positive R/G/B Data voltage changes from 255 gray to 127 gray, and when Demux G is turned on, because d2 < d4, the absolute value of the voltage change of negative G Data is larger than the absolute value of the voltage change of positive G sub-pixel Data, so that the VCOM voltage is not wholly shifted upward and then gradually deviates from the vicinity of Best 3875 when the negative Data voltage changes to be upward, so that VCOM is not coupled downward and is not particularly close to VCOM 48364 when VCOM', so that VCOM is gradually opened again when VCOM is shifted to the vicinity of Best line 3664, so that VCOM is not coupled downward and is gradually closed when VCOM Data voltage is not opened before Demux G9 '< d, so that VCOM voltage is gradually returns to the vicinity of VCOM 4836'.

Therefore, the scheme can improve the horizontal crosstalk phenomenon of the liquid crystal display screen of the Demux by independently adjusting the gray scale voltage values of the sub-pixels. In the embodiments shown in fig. 7 and 8, the embodiment in which only the R sub-pixel and the B sub-pixel are changed is described, but the reader will understand that the horizontal crosstalk problem of the liquid crystal display panel can be solved by adjusting the voltage values of the RGB sub-pixels in the same determination manner. On the other hand, the advantage of adjusting the gray scale voltage values of different types of sub-pixels individually is that more display modes can be provided. For example, in the preferred embodiment, as in the previous example, making only the R, B sub-pixels change in absolute value helps to ensure that the panel's penetration and contrast index are not affected. This is because human eyes are most sensitive to green light, and the G pixel has the largest contribution to the transmittance and contrast of the panel, so in terms of improving the bright line display problem, R, B sub-pixels with the smallest influence are sacrificed to solve the problem, so as to ensure the comprehensive display performance of the panel.

After the above example is understood and explained, the gray scale signal of 127 represents a type of data line signal with a relatively low absolute value, and the gray scale signal of 255 represents a type of data line signal with a relatively high absolute value. If the data signal is changed from a low absolute value signal to a high absolute value signal, the voltage value of a high absolute value gray scale signal of the sub-pixel with the negative polarity is increased; when the data signal is changed from a high absolute value signal to a low absolute value signal, the voltage value of the low absolute value gray scale signal of the sub-pixel with the negative polarity is reduced. When the data signal is changed into a data line signal, the signal values input sequentially in time sequence change when the data line signal is driven row by row. The voltage value of the high absolute value gray scale signal of the sub-pixel for improving the negative polarity is controlled to be pulled up by a first preset value before the high absolute value gray scale of the negative polarity acts, and the pulled-up value is kept in the light-emitting stage. And is maintained during the subsequent light emission period. The first and second preset values can be set according to actual conditions, the high absolute value and the low absolute value are fixed under the same batch of panels, the first and second preset values are corresponding to each other, the preset value table can be established, the preset values are stored in an IC register, and the specific voltage offset is controlled by looking up the table during actual use, specifically, the high absolute value and the low absolute value are input to look up the table.

Finally, as described above, the various embodiments adopted in the foregoing embodiments can achieve the purpose of improving the coupling phenomenon of the positive and negative Data lines to the VCOM and improving the horizontal crosstalk phenomenon by respectively adjusting the voltage values of the RGB sub-pixels, so that the display effect of the Demux lcd is better.

It should be noted that, although the above embodiments have been described herein, the invention is not limited thereto. Therefore, based on the innovative concepts of the present invention, the technical solutions of the present invention can be directly or indirectly applied to other related technical fields by making changes and modifications to the embodiments described herein, or by using equivalent structures or equivalent processes performed in the content of the present specification and the attached drawings, which are included in the scope of the present invention.

Claims

1. A pixel driving method is characterized by comprising the following steps of detecting the change condition of a Data signal of a Data line of a panel, and increasing the voltage value of a high absolute value gray scale signal of a sub-pixel with negative polarity when the change condition of the Data signal is detected, and the Data signal is changed from a low absolute value signal to a high absolute value signal or the Data signal is changed from the high absolute value signal to the low absolute value signal.

2. The pixel driving method according to claim 1, wherein when the data signal is changed from a low absolute value signal to a high absolute value signal or when the data signal is changed from a high absolute value signal to a low absolute value signal, the voltage value of the high absolute value gray scale signal of the R, B sub-pixel with negative polarity is increased.