TWI581245B - Polarity inversion driving method and source driver of lcd - Google Patents

Description

Polarity inversion driving method of liquid crystal display and source driver

The present invention relates to a polarity inversion driving method for a liquid crystal display, and more particularly to a polarity inversion driving method for spatial domain and time domain equalization distribution.

Liquid crystal displays (LCDs) have the advantages of light weight, low power consumption, and no radiation, so they are commonly used in various electronic products, such as desktop computers, tablet computers, mobile phones, etc., as output displays.

The first figure shows a system block diagram of the liquid crystal display 100. The gate lines GL1 to GLn and the data lines DL1 to DLm cross each other, and the liquid crystal panel 11 defines a plurality of pixels arranged in a matrix form. A thin film transistor TFT and a liquid crystal capacitor Clc are formed for each pixel as a switch and a liquid crystal cell, respectively. The voltage difference between the pixel electrode and the common voltage (Vcom) electrode of the liquid crystal capacitor Clc generates an electric field to control the liquid crystal molecules to change the intensity of the passing light. The gate driving signal is turned on by the gate lines GL1 GL GLn to turn on the thin film transistor TFT, so that the data driving signals are electrically connected to the pixel electrodes through the corresponding data lines DL1 DL DLm.

The liquid crystal display 100 includes a gate driver 13 to drive the gate lines GL1 GL GLn, and includes a source (or data) driver 15 to drive the data lines DL1 DL DLm. During the frame display, the gate driver 13 sequentially supplies the gate driving signals to the gate lines GL1 GL GLn, and the source driver 15 provides the data driving signals to the data lines DL1 DL DLm for the liquid crystal capacitors. The pixel electrode of Clc is charged.

The liquid crystal display 100 further includes a timing controller (Tcon) 17 for controlling the gate driver 13 and the source driver 15 and providing image signals to the source driver 15.

If a voltage of the same polarity is continuously applied to the pixel electrode, damage of the liquid crystal molecules is caused, and the image is flickered or darkened. In order to avoid damage of liquid crystal molecules, a polarity inversion driving method is usually used to periodically change the polarity of the data driving signal.

The second figure shows a simplified schematic of a line inversion driving method for driving the liquid crystal display 100 to illustrate the polarity of the data driving signals of two consecutive frames. In the line inversion driving method, adjacent gate lines and adjacent frames perform polarity inversion of the data driving signal. The line inversion driving method is liable to cause crosstalk of horizontal pixels, thus causing image flicker.

The third figure shows a simplified schematic of a dot inversion driving method for driving the liquid crystal display 100 to illustrate the polarity of the data driving signals of two consecutive frames. In the dot inversion driving method, adjacent pixels in the horizontal direction and the vertical direction and the adjacent frame perform polarity inversion of the data driving signal. The dot inversion driving method changes the charging of the pixel electrode much more than the line inversion driving method, and thus consumes a large power.

The fourth figure shows a simplified schematic of an N-line inversion driving method for driving the liquid crystal display 100 to illustrate the polarity of the data driving signals of two consecutive frames. In the N-line inversion driving method, the polarity of the data driving signal is inverted every N consecutive gate lines and adjacent frames. Although the dot inversion driving method consumes less power, the N-line inversion driving method tends to cause horizontal dark lines, thereby degrading image quality.

In addition, for some image patterns, such as white block patterns, it is easy to generate vertical interference noise at the top and bottom of the pattern.

Therefore, it is urgent to propose a novel polarity inversion driving method to avoid some side effects (such as horizontal dark lines or vertical interference noise).

In view of the above, an object of the embodiments of the present invention is to provide a polarity inversion driving method for a liquid crystal display, in which the polarity order of the pixels in the reverse direction is such that the spatial and temporal domains are evenly distributed to avoid horizontal dark lines or vertical directions. Interference with the occurrence of noise.

According to one embodiment of the present invention, the channel of the liquid crystal panel is divided into a plurality of channel groups, and one channel group is divided into a plurality of channel groups. For each gate line, a plurality of pixels of one channel group correspond to one pixel group. Set the initial polarity inversion method of the LCD panel. During the display of the same frame, the polarity order of one of the plurality of gate lines is reversed, so that the positions of the groups of pixels reversed in polarity order are evenly distributed over the entire frame in the spatial domain. Every other frame, the positions of the pixel groups reversed in the polarity order are changed, so that the positions of the pixel groups are evenly distributed in the time domain.

In accordance with another embodiment of the present invention, a source driver for a liquid crystal display includes a counter and polarity control logic. The counter receives the frame control signal and the gate line control signal from the timing controller, wherein the frame control signal indicates the start of the frame, and the gate line control signal indicates the start of each gate line. Accordingly, the counter generates a count value indicating the location of the currently displayed pixel. The polarity control logic device includes a polarity sequence reverse setting look-up table of the pixel group, and generates a channel group control signal according to the count value to indicate that the corresponding pixel group of each channel group reverses the polarity order.

The fifth figure shows a flow chart of a polarity inversion driving method of the liquid crystal display device 100 of the embodiment of the present invention. The system architecture of the liquid crystal display device 100 follows the system block diagram of the first figure. 6 to 9 are simplified diagrams showing a polarity inversion driving method of the liquid crystal display device 100 of the embodiment of the present invention, respectively illustrating pixel polarities of the first, third, fifth, and seventh frames. The pixel polarities of the second, fourth, sixth and eighth frames are omitted, wherein the pixel polarity of the second frame is opposite to the first frame (sixth image), and the pixel polarity of the fourth frame is opposite to the first In the three-frame (seventh figure), the pixel polarity of the sixth frame is opposite to the fifth frame (eighth figure), and the pixel polarity of the eighth frame is opposite to the seventh frame (the ninth figure). The sixth to ninth figures only illustrate the pixel polarities of the matrix 8x8 arrangement, and the pixels arranged in a matrix of the illustration can be repeated to form the entire liquid crystal panel 11. The sixth to ninth figures only illustrate the pixel polarities of the first, third, fifth, and seventh frames, and the frames can be repeated to obtain the pixel polarities of other subsequent frames. This embodiment can be applied to various display specifications, such as a compact low-voltage differential signal (mini-LVDS) interface or a point-to-point (PSP) interface.

First, in step 51 (fifth diagram), the channels (or data lines DL1 to DLm) of the liquid crystal panel 11 are divided into a plurality of channel groups. As illustrated in the sixth figure, each of the eight channels is divided into a channel group, for example, CH8n+1~CH8n+8 is a channel group. In addition, a channel group is divided into a plurality of channel groups. For example, two adjacent channels in the channel group are set as one channel group, for example, CH8n+1~CH8n+2 is a channel group. In the present embodiment, one channel group includes four channel groups, but is not limited thereto. For each gate line GL1 GL GLn, a pixel of a channel group (for example, channel group CH8n+1~CH8n+2 of gate line 1) corresponds to a pixel group.

Next, in step 52, the initial polarity inversion mode of the liquid crystal panel 11 is set. In the present embodiment, the dot inversion driving method is used for the gate lines GL1 to GLn (horizontal) directions. In the first half channel group (for example, CH8n+1~CH8n+4), the polarity is sequentially alternating between positive polarity (+) and negative polarity (-), for example, +-+-. In the latter half channel group (for example, CH8n+5~CH8n+8), the polarity order is opposite to that of the first half channel group, for example, the order of -+-+. In another embodiment, the polarity of the front half channel group may be the same as the latter half channel group. In the present embodiment, as illustrated in the sixth figure, the polarity inversion is not used in the data lines DL1 to DLm (vertical) directions, that is, the polarities thereof are the same. In other embodiments, the polarities of the data lines DL1~DLm (vertical) directions may be different.

According to one of the features of the embodiment (step 53), at least one of the plurality of gate lines GL1 GLGLn is respectively displayed during the display of the same frame (for example, the first frame shown in FIG. 6). The polarity order is reversed, and the positions of the groups of pixels reversed in polarity order are substantially evenly distributed throughout the frame. As illustrated in the sixth figure, during the display of the first frame, the polarity order of one of the gate groups 1 to 8 (shown by oblique lines) is reversed, for example, the first of the gate lines 1 is The channel group (CH8n+1~CH8n+2) is reversed in the order of the polarity of the corresponding pixel group, so that it is reversed from the polarity order of +- to the polarity order of -+; for example, the third channel group of the gate line 3 (CH8n+5~CH8n+6) The polarity order of the corresponding pixel group is reversed so that the polarity order of -+ is reversed to the polarity order of +-.

In an example, the positions of the groups of pixels that are reversed in polarity order may be a random distribution. In another example, the positions of the pixel groups reversed in polarity order may be sequentially distributed, as illustrated in the sixth figure, according to the first channel group, the second channel group, the third channel group, and the fourth channel. The groups are distributed sequentially. As illustrated in the sixth figure, the positions of the pixel groups reversed by the polarity order (as indicated by oblique lines) are substantially evenly distributed over the entire frame, such that the inverted pixel groups reach the space domain. Balanced distribution. In an embodiment, the pixel groups reversed in polarity order are not adjacent to each other for the same channel group of the same frame. As exemplified in the sixth figure, for the first channel group (CH8n+1~CH8n+2), the pixel groups reversed in polarity order (as indicated by oblique lines) are spaced apart from each other by three gate lines.

Next, according to another feature of the embodiment (step 54), the aforementioned polarity is changed every other frame (for example, the first, third, fifth, and seventh frames shown in the sixth to ninth figures). The positions of the groups of pixels that are reversed in sequence are such that the positions of the groups of pixels are substantially evenly distributed over a time domain. As illustrated in the sixth to ninth figures, the first pixel group (CH8n+1~CH8n+2) corresponds to the first pixel group (shown by oblique lines) at the positions of the first, third, fifth, and seventh frames. They are gate line 1&5, gate line 3&7, gate line 2&6, and gate line 4&8. Thereby, the positions of the pixel groups reversed in polarity order are substantially evenly distributed in the time domain.

In an example, the change in position of the set of pixels in the time domain can be a random distribution. In another example, the positional changes of the groups of pixels in the time domain may be in a particular order. As illustrated in the sixth to ninth diagrams, the position of the first pixel group corresponding to the first channel group (CH8n+1~CH8n+2) (as indicated by the slanted line) changes in the time domain as the gate line 1&5 à 3&7 à 2&6 à 4&8.

The tenth diagram shows a system block diagram of the source driver 15 and the timing controller 17 of the liquid crystal display device 100 of the embodiment of the present invention. In the present embodiment, the source driver 15 includes a counter 151 that receives the frame control signal STV and the gate line control signal TP1 from the timing controller 17. Wherein, the frame control signal STV indicates the start of the frame, and the gate line control signal TP1 indicates the start of each gate line. Thereby, the counter 151 generates a count value indicating the position of the currently displayed pixel. The source driver 15 of the present embodiment also receives at least one polarity inversion control signal from the timing controller 17. This embodiment uses the two polarity inversion control signals POL and POL2, however, in other embodiments, only a single polarity inversion control signal can be used.

The source driver 15 includes a determination logic device 152 that receives the polarity inversion control signals POL and POL2. When the polarity inversion control signals POL and POL2 meet a predetermined state, the determination logic device 152 generates an enable signal. The counter 151 is given to start the counter 151. In the present embodiment, the decision logic 152 checks whether the polarity inversion control signals POL and POL2 are mutually inverted, for example using exclusive or logical gates. When the two are mutually inverted, the decision logic 152 generates an enable signal to activate the counter 151.

The source driver 15 also includes polarity control logic 153, which contains a polarity order reverse lookup table of pixel groups, as indicated by the slanted lines in the sixth to ninth figures. The polarity control logic 153 receives the count value generated by the counter 151, thereby generating a channel group control signal for indicating whether the corresponding pixel group of each channel group is to be reversed in polarity order.

The sixth to ninth figures illustrate a polarity inversion method of the present embodiment. However, in this embodiment, a plurality of polarity inversion modes can be set in advance. The source driver 15 can dynamically select one of the polarity inversion modes by receiving a selection signal to perform polarity inversion.

The above description is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention; all other equivalent changes or modifications which are not departing from the spirit of the invention should be included in the following Within the scope of the patent application.

100‧‧‧LCD display
11‧‧‧LCD panel
13‧‧ ‧ gate driver
15‧‧‧Source Driver
151‧‧‧ counter
152‧‧‧Judgement logic device
153‧‧‧Polar control logic device
17‧‧‧Timing controller
51‧‧‧Distribute channels into channel groups and channel groups
52‧‧‧Set initial polarity reversal mode
53‧‧‧ Reverse the polarity order of one of the gate groups of the gate lines in the spatial domain
54‧‧‧Change the position of the pixel group reversed by the polarity order in the time domain
TFT‧‧‧thin film transistor
Clc‧‧ liquid crystal capacitor
Vcom‧‧‧Common voltage
GL1~GLn‧‧‧ gate line
DL1~DLm‧‧‧ data line
STV‧‧‧ frame control signal
TP1‧‧‧ gate line control signal
POL, POL2‧‧‧ polarity reversal control signal

The first figure shows a system block diagram of a liquid crystal display. The second figure shows a simplified schematic of the line inversion driving method. The third figure shows a simplified schematic of the point inversion driving method. The fourth figure shows a simplified schematic of the N-line inversion driving method. The fifth figure shows a flow chart of the polarity inversion driving method of the liquid crystal display of the embodiment of the present invention. 6 to 9 are simplified diagrams showing a polarity inversion driving method of a liquid crystal display according to an embodiment of the present invention. FIG. 10 is a system block diagram showing a source driver and a timing controller of a liquid crystal display according to an embodiment of the present invention.

100‧‧‧LCD display

15‧‧‧Source Driver

151‧‧‧ counter

152‧‧‧Judgement logic device

153‧‧‧Polar control logic device

17‧‧‧Timing controller

STV‧‧‧ frame control signal

TP1‧‧‧ gate line control signal

POL, POL2‧‧‧ polarity reversal control signal

Claims (14)

A polarity inversion driving method for a liquid crystal display, comprising: dividing a channel of a liquid crystal panel into a plurality of channel groups, and grouping one channel group into a plurality of channel groups, and for each gate line, a plurality of pixels of one channel group corresponding to each a pixel group; setting an initial polarity inversion mode of the liquid crystal panel; during the display of the same frame, sequentially inverting polarity order of one pixel group of the plurality of gate lines, so that the pixel groups reversed in polarity order The positions are uniformly distributed in the entire frame in the spatial domain; and every other frame, the positions of the pixel groups reversed in the polarity order are changed, so that the positions of the pixel groups are evenly distributed in the time domain. The method of polarity inversion driving of a liquid crystal display according to claim 1, wherein each channel group comprises a four channel group, and each channel group comprises two channels. The polarity inversion driving method of the liquid crystal display according to the first aspect of the invention, wherein the liquid crystal panel uses a dot inversion driving method in the gate line direction, and the polarity of the rear half channel group is opposite to the polarity order of the front half channel group. The polarity inversion driving method of the liquid crystal display according to claim 3, wherein the liquid crystal panel has the same polarity in the direction of the data line. The polarity inversion driving method of the liquid crystal display according to Item 1, wherein the positions of the pixel groups reversed in polarity order are randomly distributed. The polarity inversion driving method of the liquid crystal display according to claim 1, wherein the positions of the pixel groups reversed in polarity order are sequentially distributed. According to the polarity inversion driving method of the liquid crystal display according to claim 1, in the same channel group of the same frame, the pixel groups reversed in polarity order are not adjacent to each other. According to the polarity inversion driving method of the liquid crystal display according to claim 1, the position of the pixel groups in the time domain is changed to a random distribution. According to the polarity inversion driving method of the liquid crystal display according to claim 1, the positional change of the pixel groups in the time domain is in a specific order. According to the polarity inversion driving method of the liquid crystal display of claim 1, the respective steps are performed by a source driver of the liquid crystal display. A source driver of a liquid crystal display, comprising: a counter, receiving a frame control signal and a gate line control signal from a timing controller, wherein the frame control signal indicates a start of the frame, and the gate line control signal indicates The start of each gate line, according to which the counter generates a count value for indicating the position of the currently displayed pixel; and a polarity control logic device having a polarity sequence reverse setting table of the pixel group, according to the meter The value is used to generate a channel group control signal for indicating the polarity order of the corresponding pixel group of each channel group; The channel of the liquid crystal panel of the liquid crystal display is divided into a plurality of channel groups, and one channel group is divided into a plurality of channel groups. For each gate line, a plurality of pixels of one channel group correspond to one pixel group; in the same frame During the display period, according to the channel group control signal, the polarity order of one of the plurality of gate lines is reversed, so that the positions of the pixel groups reversed in polarity order are uniformly distributed in the entire frame in the spatial domain; And every other frame, according to the channel group control signal, changing the positions of the pixel groups reversed in the polarity order, so that the positions of the pixel groups are evenly distributed in the time domain. The source driver of the liquid crystal display according to claim 11, further comprising a determining logic device, receiving at least one polarity inversion control signal from the timing controller, when the at least one polarity inversion control signal conforms to a preset In the state, the determination logic device generates a coincidence signal to the counter to activate the counter. The source driver of the liquid crystal display according to claim 12, wherein the at least one polarity inversion control signal comprises a polarity inversion control signal, and when the two are opposite to each other, the determining logic device generates the Can signal. According to the source driver of the liquid crystal display according to Item 11 of the patent application, a selection signal is further received, and one of a plurality of polarity inversion modes is dynamically selected to perform polarity inversion.