This application claims the priority benefit of Taiwan application serial no. 101110610, filed on Mar. 27, 2012. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
1. Field of the Invention
The invention relates to a display. Particularly, the invention relates to a display driving optimization method and a display driver.
2. Description of Related Art
Due to advantages of low energy consumption and a smaller size compared to a conventional cathode ray tube (CRT) display, current flat panel displays (for example, liquid crystal displays (LCDs)) have been widely used in various image display devices such as computer systems, mobile phones, personal digital assistants (PDAs), etc. A data voltage can control a gray level of a pixel. A display driver has to write different data voltages into corresponding pixels of the display panel through data lines. In order to decrease power consumption of the display driver, a charge-sharing method is provided.
In
In the conventional charge-sharing method, before the source driver 102 outputs the data voltages of a next scan line, the adjacent data lines are first short-circuited to reduce the power consumption of the display driver. For example, when the gate driving signal VG_2 activates the TFTs 112 of the second row, the source driver 102 first short-circuits the data line 108 used for transmitting the data voltage VS_1 with the data line 108 used for transmitting the data voltage VS_2. Here, it is assumed that a voltage level of the data voltage VS_1 after the short-circuit operation is V3. After the charge-sharing operation is completed, the source driver 102 cuts off the short circuit connection between the adjacent data lines , and outputs the data voltages of the next scan line (for example, the scan line of the second row). Since the LCD 10 has the charge-sharing function, the source driver 102 only transits the data voltage VS_1 from the voltage level V3 to the voltage level V2, as that shown in
However, regardless of the driving waveform, the conventional charge-sharing method keeps performing the aforementioned charge-sharing operation. Under other operation conditions, the conventional charge-sharing method probably increases the power consumption of the display driver. For example,
The invention is directed to a display driving optimization method and a display driver, which dynamically determines to enable or disable a pre-charge operation or a charge-sharing operation.
An embodiment of the disclosure provides a display driving optimization method including following steps. Previous data and current data of at least one data line of a display panel are estimated to obtain an estimation result. It is determined to enable or disable a pre-charge operation or a charge-sharing operation of the data line according to the estimation result.
Another embodiment of the invention provides a display driver. The display driver includes a data driving unit, a pre-charge or charge-sharing circuit and a detection logic unit. The data driving unit includes at least one data channel for correspondingly coupling to at least one data line of a display panel. The data driving unit transmits previous data to the data line, and receives current data. The pre-charge or charge-sharing circuit is coupled to the data line. The detection logic unit is coupled to the data driving unit and the pre-charge or charge-sharing circuit. The detection logic unit records the previous data and receives the current data. The detection logic unit estimates the previous data and the current data of the data line to obtain an estimation result. The detection logic unit determines to enable or disable the pre-charge or charge-sharing circuit to perform a pre-charge operation or a charge-sharing operation on the data line according to the estimation result.
According to the above descriptions, the previous data and the current data of the display panel are estimated to dynamically determine whether or not to enable (or disable) the pre-charge operation (or the charge-sharing operation) of the display panel. Therefore, the embodiment of the invention can implement optimization in allusion to different driving waveforms.
In order to make the aforementioned and other features and advantages of the invention comprehensible, several exemplary embodiments accompanied with figures are described in detail below.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Following exemplary embodiments of the invention can be applied to a flat panel display (for example, a liquid crystal display, etc.). By estimating a difference of two tandem groups of image data, it is dynamically determined whether or not to enable (or disable) a pre-charge operation (or a charge-sharing operation) of a display panel, so as to achieve driving optimization and a powering-saving effect. Embodiments are provided below for descriptions, though the invention is not limited to the provided embodiments, and the provided embodiments can be suitably combined.
In the present embodiment, the data driving unit 410 includes a latch 411 and an output buffer 412. The latch 411 is controlled by the control logic unit 440. Under control of the control logic unit 440, the latch 411 receives and latches the display data DATA output by the control logic unit 440, and transmits the latched display data DATA to the data lines of the display panel 100 through the output buffer 412. In some embodiments, the latch 411 or the output buffer 412 can convert digital display data into analog display data.
The pre-charge or charge-sharing circuit 420 is coupled to the data lines of the display panel 100. The pre-charge or charge-sharing circuit 420 can perform a pre-charge operation and/or a charge-sharing operation to the data lines of the display panel 100. In the present embodiment, the pre-charge or charge-sharing circuit 420 includes a pre-charge circuit 421 and a charge-sharing circuit 422. The pre-charge circuit 421, the charge-sharing circuit 422 and the data driving unit 410 are all controlled by the control logic unit 440.
The charge-sharing circuit 422 can perform the charge-sharing operation. For example, before the data driving unit 410 outputs the data voltage of a next scan line, the charge-sharing circuit 422 first short-circuits the adjacent data lines to reduce power consumption of the data driving unit 410. After the charge-sharing operation is completed, the charge-sharing circuit 422 cuts off the short circuit connection between the adjacent data lines, and then the data driving unit 410 outputs the data voltages of the next scan line.
The pre-charge circuit 421 can perform the pre-charge operation. The pre-charge circuit 421 is coupled to a reference voltage source for receiving a pre-charge voltage V_EQ. Before the data driving unit 410 outputs the data voltages of the next scan line, the pre-charge circuit 421 outputs the pre-charge voltage V_EQ to the data lines of the display panel 100, so as to reduce the power consumption of the data driving unit 410. After the pre-charge operation is completed, electrical paths between the pre-charge circuit 421 and the data lines are cut off, and then the data driving unit 410 outputs the data voltages of the next scan line.
In the present embodiment, although the pre-charge or charge-sharing circuit 420 includes both of the pre-charge circuit 421 and the charge-sharing circuit 422, the invention is not limited thereto. For example, the pre-charge circuit 421 and the charge-sharing circuit 422 can be omitted according to an actual design requirement.
The detection logic unit 430 is coupled to the data driving unit 410 and the pre-charge or charge-sharing circuit 420. The control logic unit 440 outputs the display data DATA to the detection logic unit 430. The detection logic unit 430 records the previous data and receives the current data.
The aforementioned “previous data” and the “current data” can be different pixel data of a same data line, or can be different pixel data of a plurality of data lines. In some embodiments, when the previous data and the current data are different pixel data of the same data line, in the step S510, a difference between the previous data and the current data is compared, and the difference is taken as the estimation result. For example, a first data line of the display panel 100 is taken as an example, and it is assumed that the display data transmitted to the pixel of the first scan line by the first data line is the previous data, and the display data transmitted to the pixel of the second scan line by the first data line is the current data. If a difference between the previous data and the current data of the first data line is smaller than a predetermined threshold, i.e. gray levels of the previous data and the current data are rather close, the detection logic unit 430 can disable the pre-charge circuit 421 and/or the charge-sharing circuit 422.
In another embodiment, the previous data can be a plurality of pixel data on a previous scan line, and the current data can be a plurality of pixel data on a current scan line.
In the step S511, the detection logic unit 430 inspects each pixel data of the previous scan line. If data of a certain pixel of the previous scan line is greater than a white pixel limit D_white_limit, such pixel is defined as a white pixel. If data of a certain pixel of the previous scan line is smaller than a black pixel limit D_black_limit, such pixel is defined as a black pixel. If data of a certain pixel of the previous scan line is between the black pixel limit D_black_limit and the white pixel limit D_white limit, such pixel is defined as a gray pixel. Namely, the detection logic unit 430 defines the pixel having the pixel data greater than the white pixel limit D_white_limit in a plurality of pixels of the previous scan line as the white pixel, and defines the pixel having the pixel data smaller than the black pixel limit D_black_limit as the black pixel. The detection logic unit 430 counts the number of the white pixels on the previous scan line to obtain the white pixel rate of the previous scan line. For example, if the previous scan line has x pixels, and y pixels in the x pixels are white pixels, the white pixel rate of the previous scan line is y/x. Similarly, the detection logic unit 430 counts the number of the black pixels on the previous scan line to obtain the black pixel rate of the previous scan line.
After the step S511 is completed, the detection logic unit 430 executes the step S512. In the step S512, the detection logic unit 430 determines whether the previous scan line is a white line or a black line. If the white pixel rate of the previous scan line is greater than a white line limit R_white_limit, the previous scan line is defined as the white line. If the black pixel rate of the previous scan line is greater than a black line limit R_black_limit, the previous scan line is defined as the black line. If the white pixel rate of the previous scan line is smaller than the white line limit R_white_limit and the black pixel rate is smaller than the black line limit R_black_limit, the previous scan line is defined as a gray line. The white line limit R_white_limit and the black line limit R_black_limit can be determined according to an actual design requirement of the product.
After the step S512 is completed, the detection logic unit 430 executes the step S513. In the step S513, the detection logic unit 430 counts the pixel data on the current scan line (for example, the second scan line of the display panel 100) to obtain a white pixel rate and a black pixel rate of the current scan line. Implementation details of the step S513 can be deduced according to related descriptions of the step S511. After the step S513 is completed, the detection logic unit 430 executes the step S514. In the step S514, the detection logic unit 430 determines whether the current scan line is a white line or a black line. If the white pixel rate of the current scan line is greater than the white line limit R_white_limit, the current scan line is defined as the white line. If the black pixel rate of the current scan line is greater than the black line limit R_black_limit, the current scan line is defined as the black line.
In the embodiment of
If a determination result of the step S522 is negative, the detection logic unit 430 executes the step S524 to enable the pre-charge operation (and/or the charge-sharing operation) of the data line of the display panel 100, i.e. enable the pre-charge circuit 421 and/or the charge-sharing circuit 422. For example, if the previous scan line is the white line and the current scan line is the black line, the detection logic unit 430 enables the pre-charge operation (or the charge-sharing operation) of the data line of the display panel 100. For another example, if the previous scan line is the black line and the current scan line is the white line, the detection logic unit 430 enables the pre-charge operation (or the charge-sharing operation) of the data line of the display panel 100.
Implementations of the invention are not limited to the aforementioned embodiments. For example, the previous data can be a plurality of pixel data of a previous scan line group (a plurality of previous scan lines), and the current data can be a plurality of pixel data of a current scan line group (a plurality of current scan lines). Therefore, the step S510 may include following steps. The detection logic unit 430 counts the pixel data on the previous scan line group to obtain a white pixel rate and a black pixel rate of the previous scan line group. The detection logic unit 430 counts the pixel data on the current scan line group to obtain a white pixel rate and a black pixel rate of the current scan line group. Implementation details of analysing the white pixel rate and the black pixel rate of the previous scan line group can be deduced according to related descriptions of the step S511 of
In the present embodiment, the step S520 includes following steps. The detection logic unit 430 compares the previous scan line group and the current scan line group, and determines to enable or disable the pre-charge operation (or the charge-sharing operation) performed on the data line of the display panel 100 by the pre-charge or charge-sharing circuit 420. For example, if the previous scan line group and the current scan line group are all white line groups, the detection logic unit 430 disables the pre-charge operation (or the charge-sharing operation) of the data line of the display panel 100. If the previous scan line group and the current scan line group are all black line groups, the detection logic unit 430 disables the pre-charge operation (or the charge-sharing operation) of the data line of the display panel 100. If the previous scan line group is the white line group and the current scan line group is the black line group, the detection logic unit 430 enables the pre-charge operation (or the charge-sharing operation) of the data line of the display panel 100. If the previous scan line group is the black line group and the current scan line group is the white line group, the detection logic unit 430 enables the pre-charge operation (or the charge-sharing operation) of the data line of the display panel 100.
In other embodiments, the previous data can be a plurality of pixel data in a previous frame, and the current data can be a plurality of pixel data in a current frame. The previous frame can be an nth frame, and the current frame can be an (n+1)th frame. In this way, the step S510 may include following steps. The detection logic unit 430 counts the pixel data in the previous frame to obtain a white pixel rate and a black pixel rate of the previous frame. The detection logic unit 430 counts the pixel data in the current frame to obtain a white pixel rate and a black pixel rate of the current frame. Implementation details of analysing the white pixel rate and the black pixel rate of the previous frame can be deduced according to related descriptions of the step S511 of
In the present embodiment, the step S520 includes following steps. The detection logic unit 430 compares the previous frame and the current frame, and determines to enable or disable the pre-charge operation (or the charge-sharing operation) performed on the data line of the display panel 100 by the pre-charge or charge-sharing circuit 420. For example, if the previous frame and the current frame are all white frames, the detection logic unit 430 disables the pre-charge operation (or the charge-sharing operation) of the data line of the display panel 100. If the previous frame and the current frame are all black frames, the detection logic unit 430 disables the pre-charge operation (or the charge-sharing operation) of the data line of the display panel 100. If the previous frame is the white frame and the current frame is the black frame, the detection logic unit 430 enables the pre-charge operation (or the charge-sharing operation) of the data line of the display panel 100. If the previous frame is the black frame and the current frame is the white frame, the detection logic unit 430 enables the pre-charge operation (or the charge-sharing operation) of the data line of the display panel 100.
In summary, in the display driving optimization method and the display driver of the invention, the previous data and the current data of the display panel are estimated to dynamically determine whether or not to enable (or disable) the pre-charge operation (or the charge-sharing operation) of the display panel. Therefore, the embodiment of the invention can implement optimization in allusion to different driving waveforms, so as to achieve an effect of saving power consumption.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
Number | Date | Country | Kind |
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101110610 | Mar 2012 | TW | national |