CN111028803A

CN111028803A - Demux driving method

Info

Publication number: CN111028803A
Application number: CN201911308589.0A
Authority: CN
Inventors: 谢建峰; 熊克
Original assignee: Fujian Huajiacai Co Ltd
Current assignee: Fujian Huajiacai Co Ltd
Priority date: 2019-12-18
Filing date: 2019-12-18
Publication date: 2020-04-17
Anticipated expiration: 2039-12-18
Also published as: CN111028803B

Abstract

A Demux driving method is characterized in that in an enabling time domain of a Demux sub-pixel driving signal, the step of reducing a Demux voltage signal from an on-state high voltage to a second voltage value, wherein the second voltage value is lower than a normal low voltage, so that a thin film transistor corresponding to the Demux sub-pixel is closed in an enabling time domain, and the Demux voltage signal is increased from the lower than the normal low voltage to the normal low voltage. Different from the prior art, the technical scheme pulls the low voltage of the waveform of the Demux _ R/Demux _ G/Demux _ B lower, improves the waveform tailing phenomenon of the Demux _ R/Demux _ G/Demux _ B, and then raises the lower voltage to the normal low voltage, so that the trailing color mixing is avoided. A better display effect is achieved.

Description

Demux driving method

Technical Field

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

Background

For the Demux liquid crystal display screen, because of some defects of the liquid crystal display screen, the phenomenon of color mixing appears when pictures are displayed, and the display effect of the liquid crystal display screen is influenced. This patent avoids this condition to take place through special time sequence design.

In the Demux lcd, because the lcd itself has RC Loading, the waveform of Demux _ R/Demux _ G/Demux _ B will be smeared (see the example of fig. 1), and when the smear will make the TFT of the previous Demux not be completely turned off, the TFT of the next Demux is turned on. Due to the special structure of Demux (see the example of fig. 2), when the TFT of the second Demux is turned on, the Source Line controlled by the TFT of the second Demux receives the second data, but at the same time, the second transmitted data is also transmitted to the Source Line controlled by the TFT of the first Demux (circle 1), and the same problem occurs at circle 2. Therefore, the color mixing phenomenon of the panel occurs (for example, only red pixels are displayed, but green pixels or blue pixels are also lighted due to trailing of the waveform), and the display effect of the liquid crystal display screen is affected.

Disclosure of Invention

Therefore, it is desirable to provide a new Demux specific timing sequence to avoid the color mixing problem.

In order to achieve the above object, the inventor provides a Demux driving method, which performs, in an enable time domain of a Demux subpixel driving signal, a step of down-regulating a Demux voltage signal from an on-state high voltage to a second voltage value, where the second voltage value is lower than a normal low voltage, so that a thin film transistor corresponding to the Demux subpixel is turned off in the enable time domain, and the Demux voltage signal is increased from the lower than the normal low voltage to the normal low voltage.

Further, in the enabling time domain of the Demux sub-pixel driving signal, the step of raising the Demux voltage signal from the normal low voltage to a first voltage value is further performed, wherein the first voltage value is higher than the on-state high voltage, and the step of lowering the Demux voltage signal from the first voltage value to the on-state high voltage is further performed.

Specifically, the action time of the first voltage value is equal to the action time of the on-state high voltage.

Different from the prior art, the technical scheme pulls the low voltage of the waveform of the Demux _ R/Demux _ G/Demux _ B lower, improves the waveform tailing phenomenon of the Demux _ R/Demux _ G/Demux _ B, and then raises the lower voltage to the normal low voltage, so that the trailing color mixing is avoided. A better display effect is achieved.

Drawings

FIG. 1 is a schematic illustration of the tailing phenomenon according to an embodiment;

FIG. 2 is a schematic diagram of a Demux architecture according to an embodiment;

FIG. 3 is a schematic timing diagram of the Demux according to an embodiment;

FIG. 4 is a graph of voltage versus time according to an 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.

Please refer to fig. 1, which is a schematic diagram illustrating the tailing phenomenon. For the Demux lcd, due to the characteristics of the Demux structure, as shown in fig. 2, it is assumed that the current point purple picture (R and B sub-pixels are both bright, G sub-pixel is not bright, or other pictures such as green picture): looking at the data transmission relationship in S1, Demux _ R is turned on first, S1 transmits + -5V voltage (to make R sub-pixel bright) to D1, Demux _ G is turned on again, S1 transmits 0V voltage (to make G sub-pixel bright) to D5, and finally Demux _ B is turned on, S1 transmits + -5V voltage to D3. This allows for the possibility of a trailing edge in the waveform of Demux _ R, Demux _ G, Demux _ B as in the embodiment shown in figure 1.

For S1, since the waveform of Demux is trailing, the original voltage transmitted on D1 is + -5V, when the TFT of Demux _ R is not completely turned off, Demux _ G is turned on, S1 transmits the voltage of 0V to Demux _ R, and Demux _ R is transmitted to D1, which results in the voltage level of D1 being insufficient for + -5V, so that the brightness of the sub-pixel R is reduced. The Demux _ G also has a tailing phenomenon, and the voltage on the D5 is 0V originally, so that the G sub-pixel is not bright, because Demux _ B is turned on when the tailing of Demux _ G is not completely turned off, the voltage of ± 5V is sent to the D3 on the S1, and the voltage is transmitted to the D5, so that the G pixel which is not bright originally is also bright, and a color mixing phenomenon is caused. For S2, the principle of color mixing is the same as S1, and will not be described here.

Referring to the schematic diagram of the trailing relationship of the Demux waveform shown in fig. 1, as shown in fig. 1, a black circle ① indicates that the TFT switch of Demux _ R/Demux _ G/Demux _ B is not turned off, the low voltage of Demux _ R/Demux _ G/Demux _ B is VGL1, i.e. normally low voltage, typically about-10V, ② when Demux _ R is not turned off completely, Demux _ G is turned on to transmit G data to Demux _ R, which results in incorrect display of data on Demux _ R, Demux _ G is not turned off completely, Demux _ B is turned on to transmit B data to Demux _ G, which results in incorrect display of data on Demux _ G, ③, B sub-pixel data have a wrapped gate, and the next data R does not affect the B data.

FIG. 3 is a timing diagram illustrating the design of the present embodiment, wherein the low voltage of Demux _ R/Demux _ G/Demux _ B is first reduced to VGL2 (i.e., the second voltage value), and then the low voltage of Demux _ R/Demux _ G/Demux _ B is increased to VGL1 (which is the same as the normal Demux low voltage, and may be referred to as normal low voltage, on-chip low voltage, low level, etc.). According to the principle of fig. 4 (described in detail below), when the low voltage of Demux _ R/Demux _ G/Demux _ B is designed to be a more negative second voltage value, the more negative Demux waveform of V2 can turn off Demux more quickly at the same time, so that the tailing phenomenon is significantly reduced, and thus it is ensured that the falling edge of Demux _ R/Demux _ G/Demux _ B does not generate the tailing delay phenomenon, and other data are not charged to the current in-plane Source Line controlled by Demux TFT (e.g., D1/D2, etc.) when the falling edge of Demux _ R/Demux _ G/Demux _ B is not completely turned off. Therefore, the display effect of the Demux liquid crystal display screen can be optimized. Because the problem of power consumption is considered, when the minimum value of the falling edge of the Demux _ R/Demux _ G/Demux _ B reaches V2, the TFT of the Demux _ R/Demux _ G/Demux _ B is completely turned off, and then the minimum value of the falling edge of the Demux _ R/Demux _ G/Demux _ B is raised to VGL1 (the minimum negative value of normal Demux), such a design can save power consumption and make the display effect of Demux be the best.

In summary, we provide a Demux driving method, in the enabling time domain of the Demux sub-pixel driving signal, performing the following steps to adjust the Demux voltage signal from the high voltage in the on state to a second voltage value, where the second voltage value is lower than the normal low voltage, so that the thin film transistor corresponding to the Demux sub-pixel is turned off in the enabling time domain, and the Demux voltage signal is increased from the low voltage lower than the normal low voltage to the normal low voltage. The Demux sub-pixel driving signal, i.e. the above-mentioned drive signal of Demux _ R, Demux _ G or Demux _ B sub-pixel, means de-interleaving, and is a common function of processing on the display screen. And designing the second voltage value to be lower than the normal low voltage, so that the thin film transistor corresponding to the Demux sub-pixel is turned off in the enabling time domain, and whether the Demux voltage signal needs to be increased from the lower voltage than the normal low voltage to the normal low voltage after the TFT is turned off is a two-way operation mode.

In order to better solve the problem of display of the display screen, the problems of Demux energy consumption and charging rate can be further solved besides the phenomenon of Demux waveform trailing. In the embodiment shown in fig. 3, the High voltage of Demux _ R/Demux _ G/Demux _ B is first raised to a first voltage value V0(V0> V1, V1 is the on-state High voltage on Demux, which is a High level voltage capable of making Demux operate normally, typically 15V), and the first voltage value of Demux _ R/Demux _ G/Demux _ B is increased to increase the on-current Ion of Demux _ R/Demux _ G/Demux _ B TFT, so that the charging rate of Demux _ R/Demux _ G/Demux _ B is increased, and in consideration of power consumption, the High voltage of Demux _ R/Demux _ G/Demux _ B is only half of the time that the TFT of Demux _ R/Demux _ G/Demux _ B is turned on, and then is lowered to V1 (the High voltage of Demux _ R/Demux _ G/Demux _ B, i.e. the High voltage of Demux _ R/Demux _ G/Demux _ B is increased, but also saves power consumption. In the enabling time domain of the Demux sub-pixel driving signal, the method further comprises the step of raising the Demux voltage signal from a normal low voltage to a first voltage value, wherein the first voltage value is higher than the on-state high voltage, and the method further comprises the step of lowering the Demux voltage signal from the first voltage value to the on-state high voltage. In a preferred embodiment, the first voltage value has an action time equal to the action time of the on-state high voltage.

Meanwhile, for better assistance, a voltage-time curve diagram is shown in the embodiment shown in fig. 4. According to the charging and discharging formula of the RC circuit, V (t) ═ V2- (V2-V1) exp (-t/RC) ═ V2 (1-exp (-t/RC)) + V1exp (-t/RC), the voltage-time curve relationship in fig. 4 is obtained, V1 represents the starting voltage before the voltage is about to change, V2 represents the last input voltage, and the schematic diagram can refer to fig. 4.

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 Demux driving method is characterized in that in an enabling time domain of a Demux sub-pixel driving signal, the step of reducing a Demux voltage signal from an on-state high voltage to a second voltage value, wherein the second voltage value is lower than a normal low voltage, so that a thin film transistor corresponding to the Demux sub-pixel is turned off in the enabling time domain, and the Demux voltage signal is increased from the lower than the normal low voltage to the normal low voltage is carried out.

2. The Demux driving method according to claim 1, wherein in the enable time domain of the Demux sub-pixel driving signal, the step of raising the Demux voltage signal from a normal low voltage to a first voltage value, the first voltage value being higher than the on-state high voltage, further comprises the step of lowering the Demux voltage signal from the first voltage value to the on-state high voltage.

3. The Demux driving method according to claim 2, wherein the first voltage value has an active time equal to an active time of the on-state high voltage.