TW201430813A - Method of dynamic charge sharing for a display device - Google Patents

Abstract

In a method of dynamic charge sharing for a display device, it is determined whether a current line of a data driver has polarity inverted from a preceding line. Charge sharing is performed globally, if it is determined that the current line is polarity inverted from the preceding line. It is further determined whether the current line and the preceding line are substantially different, if it is determined that the current line is not polarity inverted from the preceding line. Charge sharing is performed in groups if it is determined that the current line and the preceding line are substantially different; otherwise, no charge sharing is performed.

Description

Dynamic charge sharing method of display device

The present invention relates to charge sharing, and more particularly to a dynamic charge sharing method for a liquid crystal display panel.

As the resolution of the liquid crystal display becomes higher and the panel size becomes larger, the driver of the liquid crystal display will consume more power. In addition, the AC current consumption of the liquid crystal display is also affected by the capacitive load. In view of this, a charge sharing mechanism is proposed to form an electrical short between the channels of the source driver before the output level of the pixel data is generated to obtain an average output level. With charge sharing, some power is saved.

The charge sharing used by the liquid crystal display is performed globally. In other words, all channels perform charge sharing. However, for some pixel patterns, using traditional charge sharing will not only save power, but will increase power consumption. In addition, for these pixel patterns, power consumption is increased even if charge sharing is not performed.

Therefore, it is urgent to propose a novel method to effectively perform charge sharing.

In view of the above, one of the objects of embodiments of the present invention is to provide a dynamic charge sharing method for dynamically determining whether a charge sharing is performed globally or in a group, or not performing charge sharing, thereby greatly reducing power consumption.

According to an embodiment of the present invention, a dynamic charge sharing method of a display device includes the following steps. It is determined whether the current column of pixel data to be output from the data driver channel is opposite to the polarity of the pixel data of the previous column. If the polarity of the current column and the previous column are reversed, the charge sharing is performed globally. If the polarity of the current column and the previous column are not inverted, it is determined whether the pixel data of the current column to be output from the channel is substantially different from the pixel data of the previous column. If the current column is substantially different from the previous column, then group sharing performs charge sharing; otherwise, charge sharing is not performed.

The first to first C diagrams illustrate the polarity inversion pattern of the liquid crystal display panel, which will be used in subsequent embodiments of the present invention. The first A picture shows the dot inversion pattern of the stripe liquid crystal display panel, and the pixel data of each line (or stripe) is sequentially outputted by each channel s1~s6. In the stripe panel shown in Figure A, the polarity of each pixel data (or "point") (labeled "+" or "-") is opposite to the polarity of adjacent pixel data in the same row or column.

The first B diagram shows the 1+2 line reversal pattern of the striped liquid crystal display panel. In the stripe panel shown in FIG. B, the polarity of each pixel data is opposite to the polarity of adjacent pixel data of the same column, but not necessarily opposite to the polarity of adjacent pixel data of the same row. As illustrated in FIG. B, the first column and the second column (labeled as type 1) have opposite polarities, while the fourth column and fifth column (labeled as type 2) have the same polarity. For Type 1, when charge sharing is performed on the striped panel shown in Figure B, the power consumed will be less than the charge sharing is not performed. However, for Type 2, when charge sharing is performed on the stripe panel shown in Figure B, the power consumed may be much more than the charge sharing is not performed.

The first C picture shows a zigzag liquid crystal display panel, and each channel s0~s6 sequentially outputs pixel data of two adjacent lines in sequence. Thereby, the polarity of the output pixel data of each channel s0~s6 is opposite to the polarity of the adjacent channel. Similar to Type 2 of Figure B, when charge sharing is performed on the zigzag panel shown in Figure C, the power consumed may be much more than the charge sharing is not performed. [00010] In view of the polarity inversion type described above, in order to enhance the performance of charge sharing of the liquid crystal display panel, a dynamic charge sharing method is proposed, such as the flow chart shown in the second figure. In step 21, it is determined whether the current column of pixel data to be output from the channel of the data driver (eg, the source driver) is opposite to the polarity of the previous column. If the decision result of step 21 indicates a polarity inversion (as type 1 shown in the first B diagram), then charge sharing is performed globally in step 22 (i.e., for all channels), and the flow proceeds to step 23 to process the next column. [00011] If the result of the decision in step 21 indicates that the polarity is not inverted (as in type 2 shown in FIG. B), then in step 24, it is further determined whether the pixel data of the current column to be output from the channel is the same as the pixel data of the previous column. Substantially different. In this embodiment, when a majority (for example, more than half) of the pixel data of the current column and the pixel data of the previous column are greater than a preset threshold, it indicates that the pixel data of the current column is substantially different from the pixel data of the previous column. . In this embodiment, the difference of the pixel data is determined in a digital manner. For example, before the pixel data is converted into an analog pattern in the source driver, the equivalent digit value of the pixel data is compared to obtain a difference. Taking the six-bit system as an example, when the difference between the two-pixel data is greater than 32 gray levels, the two-pixel data is substantially different. Taking the octet system as an example, when the difference of the two-pixel data is greater than 64 gray scales, the two-pixel data is substantially different. According to another feature of this embodiment, only a portion of the channel (but not all channels) of the source driver is sampled, for example, all 1/10 or 1/100, and in step 24, it is determined whether the pixel data of the portion of the channel is Substantially different. Thereby, the storage space required for storing the pixel data for comparison can be greatly reduced, and the execution speed can be greatly improved. [00013] If the result of the decision in step 24 indicates that the pixel data of the current column to be output from the channel is substantially different from the pixel data of the previous column, the charge sharing is performed in groups (step 25); otherwise, charge sharing is not performed. Next, the flow proceeds to step 23 to process the next column. In this embodiment, the charge sharing of step 25 is divided into two groups of execution - an odd group including an odd channel and a double group including a double channel. Taking the first B diagram as an example, the odd group includes channels s1, s3, and s5; and the double group includes channels s2, s4, and s6. [00014] Performing the charge sharing method of the present embodiment to improve the charge sharing efficiency of the liquid crystal display panel can be further appreciated from the following examples. The third figure shows the 1+2 line reversal pattern of the striped liquid crystal display panel, which has a pixel on/off pattern, that is, bright red/green/blue in the same column (R/G/B). Pixel data is repeated with dark red/green/blue (R/G/B) pixels. For the type 2 indicated in the third figure, it is determined in step 24 that the pixel data indicating the two columns is substantially different, so the charge sharing of step 25 is performed. Precisely, the uncharged AC current can be 20mA, and the charge sharing AC current is reduced to 15.56mA (=20mA/2+20mA/2*(1/2)/0.9), of which 1/2 The ideal voltage changes, and 0.9 represents the charge sharing efficiency. [00015] The fourth figure shows a 1+2 line inverted pattern of a striped liquid crystal display panel having an on/off pattern, that is, a bright red/green/blue color (R/G/B). The pixel data line and the dark red/green/blue (R/G/B) pixel data line are repeated. For the type 2 indicated in the fourth figure, it is determined by step 24 that the pixel data indicating the two columns is not substantially different, so the charge sharing of step 25 is not performed. Step 24 determines that the pixel data representing the two columns is substantially different, so the charge sharing of step 25 is performed. [00016] The fifth figure shows the line inversion pattern of the zigzag liquid crystal display panel, which has a red pattern, that is, a bright red (R) pixel data line and a dark green (G) and blue (B) pixel data. The line repeats. Precisely, the uncharged AC current can be 30mA, while the charge sharing AC current drops to 22.22mA (=30mA*(2/3)/0.9), where 2/3 represents the ideal voltage change, and 0.9 Indicates charge sharing efficiency. [00017] 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 included in the spirit of the invention should be included. It is within the scope of the following patent application.

twenty one. . . Whether the polarity is reversed

twenty two. . . Global charge sharing

twenty three. . . Next column

twenty four. . . Whether the pixel data is substantially different

25. . . Group charge sharing

The first to first C diagrams illustrate the polarity inversion pattern of the liquid crystal display panel. The second figure shows a flow chart of a dynamic charge sharing method of a liquid crystal display panel according to an embodiment of the present invention. The third figure shows a 1+2 line reversal pattern of a striped liquid crystal display panel with a pixel on/off pattern. The fourth figure shows a 1+2 line reversal pattern of a striped liquid crystal display panel having a line on/off pattern. The fifth figure shows the line inversion pattern of the zigzag liquid crystal display panel, which has a red pattern.

twenty one. . . Whether the polarity is reversed

twenty two. . . Global charge sharing

twenty three. . . Next column

twenty four. . . Whether the pixel data is substantially different

25. . . Group charge sharing

Claims (8)

A dynamic charge sharing method for a display device, comprising: determining whether a pixel data of a current column to be outputted from a channel of a data driver is opposite to a polarity of pixel data of a previous column; if the pixel data of the current column and the polarity of the pixel data of the previous column are Inversion, the charge sharing is performed globally; if the pixel data of the current column and the polarity of the pixel data of the previous column are not inverted, it is determined whether the pixel data of the current column to be outputted from the channel is substantially different from the pixel data of the previous column. And if the currently listed pixel data is substantially different from the pixel data in the previous column, the charge sharing is performed in groups; otherwise, charge sharing is not performed. The dynamic charge sharing method of a display device according to claim 1, wherein the display device comprises a liquid crystal display. A dynamic charge sharing method for a display device according to claim 1, wherein the data driver comprises a source driver. According to the dynamic charge sharing method of the display device according to the first aspect of the patent application, when the difference between the pixel data of the current column and the pixel data of the previous column is greater than a preset threshold, the pixel data of the current column and the previous column are indicated. The pixel data is substantially different. According to the dynamic charge sharing method of the display device according to claim 4, wherein the difference of the pixel data is determined in a digital manner, and the pixel data is not converted into an analog pattern in the data driver, and the pixel data is compared. The bit value is used to get the difference. The dynamic charge sharing method of the display device according to claim 4, wherein all channels of the data driver are sampled and compared to determine whether the currently listed pixel data is substantially different from the pixel data of the previous column. The dynamic charge sharing method of the display device according to claim 4, wherein a part of the channels of the data driver are sampled and compared to determine whether the currently listed pixel data is substantially different from the pixel data of the previous column. The dynamic charge sharing method of the display device according to claim 1, wherein the group performing the charge sharing step is divided into two groups, an odd group including odd channels and a double group including double channels.