JP2013231800A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption when a specified pattern is to be displayed on a liquid crystal panel having a specified driving system, by converting image data without substantially influencing visible brightness.SOLUTION: A liquid crystal display device 10 includes: a pattern detecting unit 6 for detecting coincidence between a display pattern when input image data is displayed on a liquid crystal panel and a predetermined display pattern; and a pattern converting unit 5 for converting a display pattern of the input image data when the pattern detecting unit 6 determines coincidence of the display pattern of the image data and the predetermined display pattern. Upon converting the display pattern, the pattern converting unit 5 converts the display pattern in such a manner that changes in a gradation voltage of each sub pixel connected to one data signal line from a source driver 3 are reduced.

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device that performs display by driving liquid crystal display elements arranged in a matrix by polarity inversion driving.

  In recent years, liquid crystal display devices using a liquid crystal panel have been increased in size and definition, and for example, a 4k2k panel, which is a moving image format panel having a resolution of around 4000 horizontal pixels × 2000 vertical pixels, A liquid crystal display device using an 8k4k panel, which is a moving image format panel having a resolution of about 8000 pixels × vertical pixels 4000, has been announced. With such an increase in size and definition, an increase in power consumption of the liquid crystal display device has become a problem. In particular, since the liquid crystal display device employs polarity inversion driving when driving the liquid crystal, there is a problem that power consumption increases when displaying a specific pattern.

  With regard to a technique for reducing power consumption of a liquid crystal panel operated by polarity inversion driving, for example, in Patent Document 1, a display control signal including image data and a horizontal synchronization signal is supplied to a data driver and a gate driver, In a liquid crystal display device that controls image data to be displayed and generates a reference voltage to be applied to display pixels of a predetermined polarity of a liquid crystal panel based on the image data, the change cycle of the display pattern of the image data and the polarity of the reference voltage There is disclosed a device that monitors the correlation with the inversion period and arbitrarily switches and sets the polarity inversion period when it is determined that the change period and the polarity inversion period are synchronized.

  According to this liquid crystal display device, when image data that causes flickering on the display screen or displays a specific pattern that increases power consumption can be switched to a different polarity inversion period, The synchronization between the voltage inversion period and the display pattern can be avoided, and the flicker specific to the liquid crystal display device and the increase in power consumption can be suppressed.

Japanese Patent No. 03504512

FIG. 12 is a diagram illustrating an example of the gradation voltage when the polarity inversion driving is performed.
In the liquid crystal modulation element constituting the liquid crystal panel, an ionic substance existing in the liquid crystal layer moves by applying an electric field to the liquid crystal layer. If a direct current electric field is continuously applied to the liquid crystal layer, an ionic substance is attracted to one of the two opposing electrodes, and even if the voltage applied to the electrode is constant, the electric field applied to the liquid crystal layer is offset by the charge of the ions, The electric field applied to the liquid crystal layer is substantially attenuated. In order to avoid such a phenomenon, in general, polarity inversion driving is employed in which the polarity of the applied electric field is inverted for each line of the array pixels and the polarity is switched at a predetermined cycle such as 60 Hz. Further, a driving method in which the positive and negative polarity of the electric field applied to all the array pixels is reversed at a predetermined period is also used.

  The drive voltage (gray scale voltage) when the polarity inversion drive is performed is as shown in FIG. 12, for example. The horizontal axis represents the gradation of the image data, and the vertical axis represents the gradation voltage. Here, a level obtained by quantizing a gradation voltage of 0-15V into 256 levels on the positive polarity side and 256 levels on the negative polarity side is shown. For example, when positive polarity (+) is given when polarity inversion driving is performed, image data supplied to the highest gradation (for example, image data supplied to R, G, B subpixels has 255 gradations (8-bit quantized data). In the case)), the gradation voltage is 15 V, and the gradation voltage is 8 V when the image data has the lowest gradation (the image data supplied to the R, G, and B sub-pixels is 0 gradation). On the other hand, when the negative polarity (−) is given when the polarity inversion drive is performed, the gradation voltage is 0 V when the image data is the highest gradation, and the gradation voltage is 7 V when the image data is the lowest gradation.

FIG. 13 is a diagram for explaining an example of a driving method of the liquid crystal panel. In this example, subpixels arranged in the vertical direction are connected to every other data signal line (source line), and the remaining subpixels are connected to other adjacent data signal lines. That is, the sub-pixels in each column arranged in the direction in which one data signal line extends are connected to one of the two data signal lines connected to the source driver and connected to one data signal line. The subpixels connected to the other data signal line are alternately arranged. A positive or negative gradation voltage is applied to each data signal line, and adjacent data signal lines are alternately given positive and negative polarities. The positive and negative polarities for each data signal line are inverted at a period of, for example, 60 Hz.
Hereinafter, this configuration will be described as a double source dot inversion panel.

  FIG. 14 is a diagram for explaining the state of the sub-pixel when a specific pattern is displayed on the double source dot inversion panel. FIG. 14A shows the entire screen of the liquid crystal panel. Then, as shown in FIG. 14B, as a specific display pattern on at least a part of the screen, black and white is inverted every two vertical dots (for two pixels in the vertical direction), and every pixel in the horizontal direction. It is assumed that a black and white checkered pattern in which black and white are reversed (hereinafter referred to as a 2-dot checkered pattern) is displayed.

  The positive and negative polarities when driving the sub-pixel at this time are as shown in FIG. In this case, if a line inversion drive method is used as the polarity inversion drive to invert the positive / negative polarity of the gradation voltage applied to each data signal line of the array pixels, the vertical pixel column has positive and negative polarity levels. A regulated voltage is applied alternately.

  FIG. 15A shows the state of the sub-pixel connected to each data signal line when the sub-pixel is driven in the state of FIG. Here, the sub-pixels arranged in the vertical direction are set as one of RGB sub-pixels for each column. A subpixel connected to one data signal line is given either positive polarity or negative polarity in the vertical direction. Adjacent data signal lines are alternately given positive polarity and negative polarity. Therefore, in the sub-pixel column arranged in the vertical direction, positive-polarity subpixels and negative-polarity subpixels are alternately arranged.

  FIG. 15B shows the value of the gradation voltage output from the source driver when the subpixel is driven in the state of FIG. As described above, a positive or negative gradation voltage is applied to the data signal line from the source driver. When a two-dot checkerboard is displayed, the gradation voltage is switched for each sub-pixel with respect to the sub-pixels arranged in the vertical direction on one data signal line.

  For example, the leftmost data signal line (No. 1) shown in FIG. 15B is driven with a positive polarity. Therefore, according to the example of FIG. 12, the floor of 15 V with respect to the first sub-pixel in the vertical direction. A regulated voltage is applied, and a gradation voltage of 8 V is applied to the next subpixel. Since the adjacent second data signal line (No. 2) is driven with a negative polarity, a gradation voltage of 0V is applied to the first sub-pixel in the vertical direction, and the next sub-pixel is applied to the next sub-pixel. A gradation voltage of 7V is applied. Thus, 15V and 8V are alternately applied to the data signal line in the vertical direction (subpixel arrangement direction), or 0V and 7V are alternately applied.

Next, an example will be described in which a one-dot checkered pattern in which black and white is reversed for each dot (sub-pixel) is displayed on the double source dot inversion panel instead of the two-dot checkered pattern.
FIG. 16 is another diagram for explaining the state of the sub-pixel when a specific pattern is displayed. FIG. 16A shows the entire screen of the liquid crystal panel. Then, as shown in FIG. 16B, at least a part of the screen, as another specific display pattern, black and white is inverted every vertical dot (one pixel in the vertical direction), and in the horizontal direction It is assumed that a black and white checkered pattern in which black and white are reversed for each pixel (hereinafter referred to as a 1-dot checkered pattern) is displayed.

  The positive and negative polarities when driving the sub-pixel at this time are as shown in FIG. In this case, if a line inversion drive method is used as the polarity inversion drive to invert the positive / negative polarity of the gradation voltage applied to each data signal line of the array pixels, the vertical pixel column has positive and negative polarity levels. A regulated voltage is applied alternately.

  FIG. 17A shows the state of the sub-pixel connected to each data signal line when the sub-pixel is driven in the state of FIG. Here, the sub-pixels arranged in the vertical direction are set as one of RGB sub-pixels for each column. A subpixel connected to one data signal line is given either positive polarity or negative polarity in the vertical direction. Adjacent data signal lines are alternately given positive polarity and negative polarity. Therefore, in the sub-pixel column arranged in the vertical direction, positive-polarity subpixels and negative-polarity subpixels are alternately arranged.

FIG. 17B shows the value of the gradation voltage output from the source driver when the subpixel is driven in the state of FIG. As described above, a positive or negative gradation voltage is applied to the data signal line from the source driver. When a 1-dot checkerboard is displayed, the same gradation voltage is applied to the sub-pixels arranged in the vertical direction on one data signal line.
For example, since the leftmost data signal line (No. 1) shown in FIG. 17A is driven with positive polarity, according to the example of FIG. 12, all the vertical signal lines connected to the data signal line are connected. A gradation voltage of 15 V is applied to the subpixel. Since the adjacent second data signal line (No. 2) is driven with negative polarity, a gradation voltage of 7 V is applied to all the sub-pixels in the vertical direction.

  Further, since the third data signal line (No. 3) from the left is driven with a positive polarity, a gradation voltage of 8 V is applied to all the vertical sub-pixels connected to the data signal line. The Since the adjacent fourth data signal line (No. 4) is driven with a negative polarity, a gradation voltage of 0 V is applied to all the sub-pixels in the vertical direction.

FIG. 18 is a diagram for explaining drive voltage fluctuations when a 2-dot checkerboard and a 1-dot checkerboard are displayed on the double source dot inversion panel.
The horizontal axis indicates the position of the scanning signal line selected by the drive line, that is, the gate driver, and the vertical axis indicates the drive voltage value (grayscale voltage value) for the drive line. That is, a change in gradation voltage that is sequentially passed through subpixels arranged in the vertical direction with respect to one data signal line is shown.

As shown in FIG. 18, when a 1-dot checker is displayed, even when the drive lines are sequentially switched, the drive voltage does not change and is constant, and since there is no switching, power consumption is small. On the other hand, when the 2-dot checkerboard is displayed, since the drive voltage fluctuation (switching) is repeated every time the drive line is switched, the power consumption increases.
The 2-dot checkered pattern and the 1-dot checkered pattern are substantially similar except that the arrangement of the pixel values in the screen is slightly different, but the power consumption when the display is driven is greatly different. That is, in the configuration of the double source dot inversion panel, there arises a problem that power consumption increases when a specific pattern such as a 2-dot checkerboard is displayed.

  FIG. 19 is a diagram for explaining another example of the driving method of the liquid crystal panel. In this example, all the sub-pixels arranged in the vertical direction are connected to one data signal line, and the gradation voltage from one data signal line is sequentially sub-corresponding to the selection of the scanning signal line by the gate driver. It is applied to the pixel and driven. As the polarity inversion drive, a line inversion drive method for inverting the positive / negative polarity of the applied gradation voltage for each data signal line (source line) of the array pixels is used. Hereinafter, the liquid crystal panel having this configuration is referred to as a single source line inversion panel.

FIG. 20 is a diagram for explaining the state of the sub-pixel when a specific pattern is displayed on the single source line inversion panel. FIG. 20A shows the entire screen of the liquid crystal panel. Then, as shown in FIG. 20B, it is assumed that a 2-dot checkerboard is displayed as a specific display pattern on at least a part of the screen.
The positive and negative polarities when driving the sub-pixel at this time are as shown in FIG. In this case, as the polarity inversion drive, when a line inversion drive method for inverting the positive / negative polarity of the gradation voltage applied to each data signal line of the array pixels is used, either positive polarity or negative polarity is provided for each vertical pixel column. Such a gradation voltage is applied.

  FIG. 21A shows the state of the sub-pixel connected to each data signal line when the sub-pixel is driven in the state of FIG. Here, the sub-pixels arranged in the vertical direction are set as one of RGB sub-pixels for each column. The sub-pixel connected to one data signal line is given either positive polarity or negative polarity for each pixel column in the vertical direction. Adjacent data signal lines are alternately given positive polarity and negative polarity.

  FIG. 21B shows the value of the gradation voltage output from the source driver when the subpixel is driven in the state of FIG. As described above, a positive or negative gradation voltage is applied to each data signal line from the source driver. When a 2-dot checkerboard is displayed, the gradation voltage is switched every two sub-pixels with respect to the sub-pixels arranged in the vertical direction on one data signal line. According to the example of FIG. 12, for example, the leftmost data signal line (No. 1) shown in FIG. 21B is driven with a positive polarity, so that it is 15 V with respect to the first two sub-pixels in the vertical direction. And a gradation voltage of 8V is applied to the next two sub-pixels. Since the adjacent second source line (No. 2) is driven with a negative polarity, a gradation voltage of 0 V is applied to the first two sub-pixels in the vertical direction, and the next two sub-pixels are applied. Is applied with a gradation voltage of 7V.

Next, an example will be described in which a 1-dot checkered pattern in which black and white is inverted for each dot (sub-pixel) is displayed on the source inversion panel instead of the 2-dot checkered pattern.
FIG. 22 is still another diagram illustrating the state of the sub-pixel when a specific pattern is displayed. FIG. 22A shows the entire screen of the liquid crystal panel. Then, as shown in FIG. 22B, it is assumed that 1-dot checkerboard is displayed as a specific display pattern on at least a part of the screen.

  At this time, the positive and negative polarities when driving the sub-pixels are as shown in FIG. In this case, as the polarity inversion drive, if a line inversion drive method for inverting the positive / negative polarity of the gradation voltage applied to each data signal line of the array pixel is used, either positive polarity or negative polarity is provided for each data signal line. A gradation voltage is applied.

  FIG. 23A shows the state of the sub-pixel connected to each data signal line when the sub-pixel is driven in the state of FIG. Here, the sub-pixels arranged in the vertical direction are set as one of RGB sub-pixels for each column. The sub-pixel connected to one data signal line is applied with either a positive or negative gradation voltage for each data signal line.

FIG. 23B shows the value of the gradation voltage output from the source driver when the subpixel is driven in the state of FIG. As described above, a positive or negative gradation voltage is applied to each data signal line from the source driver.
When 1-dot checkerboard is displayed, the gradation voltage is switched for each sub-pixel with respect to the sub-pixels arranged in the vertical direction on one data signal line. According to the example of FIG. 12, for example, the leftmost source line (No. 1) shown in FIG. 23B is driven with a positive polarity, so that the gradation of 15 V with respect to the first sub-pixel in the vertical direction. A voltage is applied, and a gradation voltage of 8 V is applied to the next subpixel. Since the adjacent second data signal line (No. 2) is driven with a negative polarity, a gradation voltage of 0V is applied to the first sub-pixel in the vertical direction, and the next sub-pixel is applied to the next sub-pixel. A gradation voltage of 7V is applied.

FIG. 24 is a diagram for explaining drive voltage fluctuations when a 2-dot checkerboard and a 1-dot checkerboard are displayed on the single source line inversion panel.
The horizontal axis indicates the position of the scanning signal line selected by the drive line, that is, the gate driver, and the vertical axis indicates the drive voltage value (grayscale voltage value) for the drive line. That is, a change in gradation voltage that is sequentially passed through subpixels arranged in the vertical direction with respect to one data signal line is shown.

As shown in FIG. 24, the number of drive voltage fluctuations (switching) is less when the 2-dot checker is displayed than when the 1-dot checker is displayed, and the power consumption is lower when the 2-dot checker is displayed. .
The 2-dot checkered pattern and the 1-dot checkered pattern differ in the power consumption when the display is driven, although they are almost similar patterns with a slightly different arrangement of pixel values in the screen. That is, there is a problem that power consumption increases when a specific pattern such as a one-dot checkerboard is displayed.

  In the case of Patent Document 1, a specific pattern of a display image is detected, and the polarity inversion period is changed according to the detection result. For this reason, power consumption cannot be reduced depending on the display pattern. For example, when a two-dot checkerboard is displayed on the double source dot inversion panel described above, if the polarity inversion period is changed by the method described in Patent Document 1, the subpixel connected to one data signal line What is applied with gradation voltages in the order of 15V, 8V, 15V, and 8V only changes to 15V, 7V, 15V, and 7V, the number of switching does not change, and power consumption hardly changes.

  Although the present invention has been made in view of the above circumstances, image data can be obtained without substantially affecting the apparent luminance when a specific pattern is displayed on a liquid crystal panel of a specific driving method. An object of the present invention is to provide a liquid crystal display device that reduces power consumption by conversion.

  In order to solve the above problems, a first technical means of the present invention has subpixels arranged in a matrix at intersections of a plurality of data signal lines and gate lines, and the plurality of subpixels 1 A liquid crystal display having a liquid crystal panel having two pixels and a source driver that supplies gradation voltages for driving the liquid crystal of the sub-pixels by polarity inversion driving to the data signal lines based on input image data In the apparatus, a pattern detection unit that detects a match between a display pattern when the input image data is displayed on the liquid crystal panel and a predetermined display pattern, and the pattern detection unit detects a display pattern of the image data and the predetermined display A pattern conversion unit that converts the display pattern of the input image data when it is determined that the pattern matches, the pattern conversion unit, When converting the display pattern, the display pattern is converted so that a change in the gradation voltage of each sub-pixel connected to the one data signal line during sequential scanning is reduced. Is.

  According to a second technical means, in the first technical means, when the pattern conversion unit converts the display pattern, the pixel value for each pixel of the image data to be supplied to the pixels constituting the display pattern to be converted The display pattern is converted by changing the pixel to which the image display data is supplied while maintaining the above.

  According to a third technical means, in the first or second technical means, the pattern detection unit determines the predetermined display pattern based on a luminance value for each pixel, and sets a luminance value for each pixel of the input image data. The brightness value of the predetermined display pattern is compared to detect a match between the display pattern of the input image data and the predetermined display pattern.

  According to a fourth technical means, in the first or second technical means, the pattern detection unit determines the predetermined display pattern based on pixel values of sub-pixels for displaying a specific color, and inputs the input image. Comparing a pixel value for displaying the specific color in the data with a pixel value of the predetermined display pattern to detect a match between the display pattern of the input image data and the predetermined display pattern It is characterized by.

  According to a fifth technical means, in the third or fourth technical means, the pattern detection unit provides a threshold value for determining the specific display pattern, and the display pattern of the input image data is within a threshold value range. When it matches the specific display pattern, it is determined that the display pattern of the input image data matches the specific display pattern.

  According to the present invention, although the present invention has been made in view of the above circumstances, when the specific pattern is to be displayed on the liquid crystal panel of the specific driving method, it almost affects the apparent luminance. Therefore, it is possible to provide a liquid crystal display device that reduces power consumption by converting image data.

It is a block diagram which shows the structure of one Embodiment of the liquid crystal display device by this invention. It is a flowchart for demonstrating the process example of the pattern detection in a pattern detection part. It is a figure explaining the input image data and predetermined display pattern which are used in a pattern detection part. It is a figure explaining the process example in a pattern detection part and a pattern conversion part. It is a figure explaining the other process example in a pattern detection part and a pattern conversion part. It is a figure which shows the example when changing and displaying the image data of 2 dot checkers to the image data of 1 dot checkers. It is a figure explaining the other process example in a pattern detection part and a pattern conversion part. It is a figure explaining the example of further another process in a pattern detection part and a pattern conversion part. It is a figure explaining the example of further another process in a pattern detection part and a pattern conversion part. It is a figure explaining the example of further another process in a pattern detection part and a pattern conversion part. It is a figure which shows the example when changing the image data of 1 dot checkered into image data of 2 dot checkered, and displaying it. It is a figure which shows an example of the gradation voltage when performing polarity inversion drive. It is a figure explaining an example of the drive system of a liquid crystal panel. It is a figure explaining the state of a sub pixel when a specific pattern is displayed on a liquid crystal panel. FIG. 15 is a diagram illustrating a state of a subpixel connected to each data signal line when the subpixel is driven in the state of FIG. 14 and a value of a gradation voltage output from a source driver. It is another figure explaining the state of a sub pixel when a specific pattern is displayed on a liquid crystal panel. FIG. 17 is a diagram illustrating a state of a subpixel connected to each data signal line when the subpixel is driven in the state of FIG. 16 and a value of a gradation voltage output from a source driver. It is a figure for demonstrating the drive voltage fluctuation | variation when displaying 2 dot checkers and 1 dot checkers on a liquid crystal panel. It is a figure explaining the other example of the drive method of a liquid crystal panel. FIG. 10 is another diagram for explaining the state of the sub-pixel when a specific pattern is displayed on the liquid crystal panel. FIG. 21 is a diagram showing the state of subpixels connected to each data signal line when the subpixel is driven in the state of FIG. 20 and the value of the gradation voltage output from the source driver. It is another figure explaining the state of a sub pixel when a specific pattern is displayed. FIG. 23 is a diagram showing the state of subpixels connected to each data signal line when the subpixel is driven in the state of FIG. 22 and the value of the gradation voltage output from the source driver. It is another figure for demonstrating the drive voltage fluctuation | variation when displaying a 2-dot checkerboard and a 1-dot checkerboard on a liquid crystal panel.

FIG. 1 is a block diagram showing a configuration of an embodiment of a liquid crystal display device according to the present invention. The liquid crystal display device 10 includes a liquid crystal panel 1, a gate driver 2, a source driver 3, a display controller 4, a pattern conversion unit 5, and a pattern detection unit 6.
The liquid crystal panel 1 includes a screen composed of sub-pixels arranged in a matrix, a plurality of gate lines (scanning signal lines) for selecting and scanning the sub-pixels line-sequentially, and data in the sub-pixels of the selected line. And a plurality of data signal lines for supplying signals. The sub-pixel is disposed at the intersection of the data signal line and the gate line.
The sub-pixel is for displaying one of RGB colors, for example, and one pixel is constituted by the RGB sub-pixels. Also, a pixel configuration with four colors such as RGBY (yellow) or other multi-color pixel configuration can be applied.

  The scanning signal line and the data signal line are orthogonal to each other. The gate driver 2 is a scanning signal line driver, and outputs a voltage corresponding to each of the selection period and the non-selection period to each scanning signal line of the liquid crystal panel 1. The source driver 3 is a data signal line driver, outputs a data signal to each data signal line (source line) of the liquid crystal panel 1, and supplies image data to each of the sub-pixels on the selected scanning signal line. .

  The display controller 4 receives the input image data, distributes the gate start pulse signal GSP and the gate clock signal to the gate driver 2, and supplies RGB tone data, source start pulse signal, source latch strobe signal to the source driver 3, and Distribute the source clock signal. All these signals are synchronized. Image data includes image data acquired from broadcast waves received by a liquid crystal display device configured as a broadcast receiving device, image data input via a network, image data output from a computer or an external recording medium, and the like. Applicable.

  The gate driver 2 starts scanning the liquid crystal panel 1 with the gate start pulse signal received from the display controller 4 as a cue, and sequentially applies a selection voltage to each scanning signal line according to the gate clock signal. Based on the source start pulse signal received from the display controller 4, the source driver 3 stores the received gradation data of each pixel in a register according to the source clock signal, and each of the liquid crystal panel 1 according to the next source latch strobe signal. Write gradation data to the data signal line.

  In the source driver 3, polarity inversion driving is performed to invert the polarity of the gradation voltage applied to each sub-pixel of the liquid crystal panel 1 at a constant period based on the inversion period of the reference voltage supplied from the reference power source to the source driver 3. Is called. The gradation voltage in the polarity inversion driving is controlled by a voltage value as shown in FIG.

The pattern detection unit 6 holds information on a predetermined display pattern in advance, and detects a match between the display pattern when the input image data is displayed on the liquid crystal panel 1 and the predetermined display pattern.
The pattern conversion unit 5 converts the display pattern of the input image data when the pattern detection unit 6 determines that the display pattern of the image data matches a predetermined display pattern. At this time, the pattern conversion unit 5 changes the gradation voltage in each sub-pixel connected to one data signal line for supplying a data signal from the source driver 3 to the liquid crystal panel 1 when converting the display pattern. The display pattern is changed so that there is less.

More specifically, when image data is written by sequentially applying gradation voltages to sub-pixels connected to one data signal line, the image data is converted so as to reduce voltage fluctuation (switching). To do. At this time, the pattern conversion unit 5 converts the display pattern by changing the pixel to which the image display data is supplied while maintaining the image data for each pixel constituting the display area for converting the display pattern. .
As a result, the power consumption can be reduced by converting the image data with little influence on the apparent luminance on the screen.
In the following, embodiments of the present invention will be described more specifically while explaining specific operation examples of pattern detection and pattern conversion.

FIG. 2 is a flowchart for explaining an example of pattern detection processing in the pattern detection unit 6. As described above, the pattern detection unit 6 detects a match with a predetermined pattern when the input image data is displayed on the liquid crystal panel 1.
Here, first, image data is input to the pattern detection unit 6 (step S1), the horizontal coordinate x = 0 is set, and the vertical coordinate y = 0 is set (step S2). Then, the following formula (1) is calculated, and it is determined whether or not the formula (1) is satisfied (step S3). In Expression (1), whether or not the input image data includes a predetermined display pattern by comparing the luminance value for each pixel of the input image data with the luminance value for each pixel of the predetermined display pattern. Is judged.

  Here, as shown in FIG. 3A, the luminance value of the input image data is I (x, y), the horizontal coordinate x of the image data is 0 to m-1, and the vertical direction of the image data is The coordinate y is set to 0 to n-1. Further, as shown in FIG. 3B, the luminance value of a predetermined display pattern for detection prepared in advance is D (i, j), and the horizontal coordinate x of the image data is 0 to p-1. The vertical coordinate y of the image data is set to 0 to q-1.

  Returning to FIG. When Expression (1) is satisfied in step S3, since the predetermined display pattern is included in the input image data, the pattern conversion unit 5 converts the display pattern (step S9). The conversion of the display pattern is to convert the position of the pixel to be displayed by the input image data, and basically by changing the display position without changing the value of the image data for each pixel in the screen, Reduce power consumption without changing the brightness on the screen.

If the expression (1) is not satisfied in step S3, or if the display pattern is converted in step S9, x is updated to x + 1 (step S4). Then, it is determined whether x <m is satisfied (step S5). If x <m, the process returns to step S3 to determine whether the display pattern matches at the next coordinate position.
If x <m is not satisfied in step S5, x = 0 and y = y + 1 are set (step S6), and if y <n (step S7-Yes), the process returns to step S3 to match the display pattern at the next coordinate position. Determine whether or not. If y <n is not satisfied in step S <b> 7, the pattern detection unit 6 determines whether the pattern display unit 6 matches or does not match with a predetermined display pattern in the region starting from all coordinates in the input image data. Then, the image data is sent to the display controller 4 (step S8), and the detection process is terminated. The detection result of the predetermined display pattern is sent to the pattern conversion unit 5.

  In the above example, a pattern whose luminance value completely matches a predetermined display pattern is detected according to the equation (1). However, as shown in the following equation (2), a predetermined threshold (Th ) Is set, and if the degree of matching is within a predetermined range, the input image data may be regarded as matching a predetermined pattern, and the image data conversion process may be performed.

  In the above example, when the brightness of each pixel of the input image data matches or is considered to match the brightness of the predetermined display pattern, the image data conversion process is performed. When the display pattern of a predetermined percentage of the entire display screen using the image data matches the predetermined display pattern, the display pattern of the input image data is considered to match the predetermined display pattern, and the display pattern is converted. May be performed. This is because the effect of reducing power consumption may not appear clearly when the display pattern does not match a predetermined area.

FIG. 4 is a diagram illustrating an example of processing in the pattern detection unit and the pattern conversion unit.
When polarity inversion driving is performed with a double source dot inversion panel, a display pattern as shown in FIG. 4A is set as a predetermined display pattern for detection. Here, each rectangle represents one pixel. In this example, a display pattern in which four pixels are arranged in the vertical direction is assumed, and among the four pixels, the upper two pixels display black and the lower two pixels display white. The luminance value Y of each pixel is the lowest gradation (Y = 0) in the case of black, and the highest gradation (Y = 255 (in the case of 8-bit representation)) in the case of white.

The pattern detection unit 6 compares the luminance value of the input image data with the luminance value of a predetermined display pattern as shown in FIG. 4A, and the input image data has a portion that matches the predetermined display pattern. Detect whether or not there is.
If there is a matching part, the pattern conversion unit 5 converts the image data having the display pattern as shown in FIG. 4A into the display pattern as shown in FIG. That is, the image data is converted and displayed so that pixels arranged in the vertical direction are black, white, black, and white from the top. Here, since the number of black pixels and the number of white pixels do not change before and after the conversion, the image data is converted without changing the luminance on the screen.

In this case, the display pattern in FIG. 4A corresponds to the above-described 2-dot checkered pattern, and the display pattern in FIG. 4B corresponds to a 1-dot checkered pattern. That is, in this example, when image data for displaying a 2-dot checker is input, this means that the portion is converted to a 1-dot checker.
When displaying a 2-dot checker on a double source dot inversion panel that performs polarity inversion drive for each data signal line, it is better to display a 1-dot checker than when displaying a 2-dot checker as described above. Low drive voltage fluctuation (switching) and low power consumption. Therefore, in this example, by converting the image data corresponding to the 2-dot checkered image into the image data corresponding to the 1-dot checkered state, it is possible to reduce the power consumption when displaying on the double source dot inversion panel.

  That is, in the present invention, when converting the display pattern of the input image data, the pattern conversion unit 5 converts the display pattern so that the change in the gradation voltage of each sub-pixel connected to one data signal line is reduced. To do. At this time, the display pattern is converted by changing the pixel to which the image display data is supplied while maintaining the value of each pixel of the image data to be supplied to the pixels constituting the display pattern to be converted.

The predetermined display pattern detected by the pattern detection unit 6 and the converted display pattern for converting the display pattern may be set as shown in FIG. In the predetermined display pattern shown in FIG. 5A, among the display patterns in which four pixels are arranged in the vertical direction, white with the highest luminance is displayed on the upper two pixels, and the lowest luminance is displayed on the lower two pixels. Black shall be displayed.
If the input image data includes a portion that matches a predetermined display pattern as shown in FIG. 5A, the pattern converter 5 displays the image data having the display pattern as shown in FIG. The display pattern is converted to a display pattern such as 5 (B). That is, the image data is converted and displayed so that the pixels arranged in the vertical direction are white, black, white, and black from the top. Also in this case, the image data for displaying the 2-dot checker is converted to the 1-dot checker, and the power consumption when displayed on the double source dot inversion panel can be reduced.

  FIG. 6 is a diagram illustrating an example when image data of 2-dot checker is changed to image data of 1-dot checker and displayed. Image data for displaying a 2-dot checkered pattern as shown in FIG. 6A on the entire screen is input to the liquid crystal display device, and the image data is converted into image data of a 1-dot checkered pattern as shown in FIG. Display. Before and after conversion, the entire screen is a gray screen with a luminance of 50% (gradation), but power consumption can be reduced by converting the image data. On the liquid crystal panel, even if the image data is converted, the change in appearance is small, and a sense of incongruity does not occur. In particular, when a high-definition panel is used, a change in appearance is felt less and power consumption can be effectively reduced.

FIG. 7 is a diagram illustrating another example of processing in the pattern detection unit and the pattern conversion unit.
When polarity inversion driving is performed with a double source dot inversion panel, in the example of FIG. 4, as the predetermined display pattern for detection, white of the lowest luminance gradation and black of the highest luminance gradation are displayed in a two-dot checkered pattern. Sometimes, it was determined to match a predetermined display pattern. In this example, a threshold value is provided for the luminance value, and whether or not there is a match is determined based on the threshold value.

For example, when a black and white two-dot checkerboard is set as the predetermined display pattern, a threshold value is provided for the luminance value on the black side, and pixels whose luminance is lower than the threshold value are displayed, as shown in FIG. The image data to be processed is determined to be black. In this case, a predetermined level of dark ash is also determined to be black.
Similarly, a threshold value can be provided on the white side. It is determined that the image data for displaying pixels having a luminance higher than the predetermined threshold value on the white side is white.

  When it is determined that the input image data includes a portion that matches a predetermined display pattern as shown in FIG. 7A, the pattern conversion unit 5 has a display pattern as shown in FIG. The image data is converted into a display pattern as shown in FIG. That is, the image data is converted and displayed so that pixels arranged in the vertical direction are gray, white, gray, and white from the top. Here, the number of gray pixels and the number of white pixels do not change before and after the conversion, so that the image data is converted without changing the luminance on the screen.

  In this case, the display pattern of FIG. 7A does not completely match the above-described 2-dot checkerboard, but the drive voltage fluctuation is reduced by converting the image data, and the image is displayed on the double source dot inversion panel. Power consumption can be reduced.

FIG. 8 is a diagram for explaining still another processing example in the pattern detection unit and the pattern conversion unit.
When polarity inversion driving is performed with a double source dot inversion panel, in the above example, when a predetermined display pattern is detected from input image data, the luminance value for each pixel is used to determine whether or not there is a match. . In this example, a predetermined display pattern is detected using the respective RGB gradation values instead of the luminance values for each pixel of the image data.

  For example, as shown in FIG. 8A, R (red) gradation values arranged in a two-dot checkered form are set as a predetermined display pattern. Here, the display pattern has a configuration in which four red sub-pixels are arranged in the vertical direction, and among the four red sub-pixels, the upper two sub-pixels display black with the lowest gradation, Assume that two sub-pixels display the highest gradation red.

The pattern detection unit 6 compares the red gradation value of the input image data with the gradation value of a predetermined display pattern as shown in FIG. 8A, and converts the input image data into a predetermined display pattern. Detect whether there is a matching part.
If there is a matching part, the pattern conversion unit 5 converts the image data having the display pattern as shown in FIG. 8A into the display pattern as shown in FIG. That is, the image data is converted and displayed so that the red sub-pixels arranged in the vertical direction are black, red, black, and red from the top. At this time, the display position of the entire pixel including each red sub-pixel is converted so that the luminance of each pixel does not change. Therefore, the number of black pixels with the lowest gradation and the number of red pixels with the highest gradation do not change before and after conversion, and the brightness of each pixel also does not change, so image data can be converted without changing the brightness on the screen. Is made.

  In this case, the display pattern of FIG. 8A corresponds to one data signal line of the above-described 2-dot checkerboard, and the data signal is converted by converting the image data as shown in FIG. 8B. With respect to the lines, fluctuations in the driving voltage are reduced, and power consumption when displaying on the double source dot inversion panel can be reduced.

  In the above example, the predetermined display pattern is configured by the highest gradation of red and the lowest gradation of red, but other gradation values such as G (green) and B (blue) are used. Also good. Further, in addition to the maximum gradation and the minimum gradation, a threshold value is provided for the gradation value so that a sub-pixel having a pixel value within the predetermined threshold value is determined to match the sub-pixel of the predetermined display pattern. Also good.

FIG. 9 is a diagram for explaining still another processing example in the pattern detection unit and the pattern conversion unit. This example is applied to a single source line inversion panel in which all subpixels arranged in the vertical direction are connected to one data signal line, and the polarity of the applied gradation voltage is inverted for each data signal line of the arranged pixels. It is what is done.
When polarity inversion driving is performed with a single source line inversion panel, a pattern as shown in FIG. 9A is used as a predetermined display pattern for detection. Here, each rectangle represents one pixel. In this example, a display pattern in which four pixels are arranged in the vertical direction is assumed, and four pixels are arranged in black and white alternately. The luminance value Y of each pixel is the lowest gradation (Y = 0) in the case of black, and the highest gradation (Y = 255 (in the case of 8-bit representation)) in the case of white.

The pattern detection unit 6 compares the luminance value of the input image data with the luminance value of the predetermined display pattern as shown in FIG. 9A, and the input image data has a portion that matches the predetermined display pattern. Detect whether or not there is.
When there is a matching portion, the pattern conversion unit 5 converts the image data having the display pattern as shown in FIG. 9A into the display pattern as shown in FIG. 9B. That is, the pixels arranged in the vertical direction are displayed by converting the image data so that the upper two are black and the lower two are white. Here, since the number of black pixels and the number of white pixels do not change before and after the conversion, the image data is converted without changing the luminance on the screen.

In this case, the display pattern in FIG. 9A corresponds to the above-described 1-dot checkered pattern, and the display pattern in FIG. 9B corresponds to a 2-dot checkered pattern. That is, in this example, when image data for displaying a 1-dot checker is input, this means that the portion is converted to a 2-dot checker.
When displaying a 2-dot checkerboard on a single source line reversal panel, the number of drive voltage fluctuations (switching) is less when the 2-dot checker is displayed than when the 1-dot checker is displayed as described above. , Less power consumption. Therefore, in this example, by converting image data corresponding to 1 dot checker into image data corresponding to 2 dot checker, it is possible to reduce power consumption when displaying on the source inversion panel.

  That is, in the present invention, when converting the display pattern of the input image data, the pattern conversion unit 5 converts the display pattern so that the change in the gradation voltage of each sub-pixel connected to one data signal line is reduced. To do. At this time, the display pattern is converted by changing the pixel to which the image display data is supplied while maintaining the value of each pixel of the image data to be supplied to the pixels constituting the display pattern to be converted.

The predetermined display pattern detected by the pattern detection unit 6 and the converted display pattern for converting the display pattern may be set as shown in FIG. Also in this case, the predetermined display pattern shown in FIG. 10A displays white, black, white, and black from the top among the display patterns in which four pixels are arranged in the vertical direction.
When the input image data includes a portion that matches a predetermined display pattern as shown in FIG. 10A, the pattern conversion unit 5 displays the image data having the display pattern as shown in FIG. The display pattern is converted to a display pattern such as 10 (B). That is, the image data is converted and displayed so that the pixels arranged in the vertical direction are white in the upper two pixels and black in the lower two pixels. Also in this case, the image data for displaying the 1-dot checker is converted to the 2-dot checker, and the power consumption when displaying on the source inversion panel can be reduced.

  In the above example, a match between a predetermined display pattern consisting of white with the highest luminance value and black with the optimum luminance value is detected. May be judged. For example, when a black and white one-dot checkered pattern is set as a predetermined display pattern, a threshold value is provided for the luminance value on the black side, the white side, or both, and pixels having a luminance lower than the threshold value on the black side are displayed. The image data may be determined to be black, and the image data that displays a pixel having a higher luminance than the white threshold may be determined to be white.

  Further, when a predetermined display pattern is detected from the input image data, the predetermined display pattern may be detected using the respective RGB gradation values instead of the luminance value for each pixel of the image data. Good. At this time, in addition to the maximum gradation and the minimum gradation, a threshold value is provided for the gradation value, and a sub-pixel having a pixel value within the predetermined threshold value is determined to match the sub-pixel of the predetermined display pattern. You may do it.

  FIG. 11 is a diagram illustrating an example when image data of 1 dot checker is changed to image data of 2 dot checker and displayed. Image data for displaying a 1-dot checkered pattern as shown in FIG. 11A on the entire screen is input to the liquid crystal display device, and the image data is converted into 2-dot checkered image data as shown in FIG. Display. Before and after conversion, the entire screen is a gray screen with a luminance of 50% (gradation), but power consumption can be reduced by converting the image data. On the liquid crystal panel, even when the image data was converted, the visual change was small and no sense of incongruity occurred. In particular, when a high-definition panel is used, a change in appearance is felt less and power consumption can be effectively reduced.

  The pattern detection processing and pattern conversion processing described above may be turned off for specific image data so that pattern conversion is not performed. For example, when displaying image data output from a personal computer (PC), the pattern detection process and the pattern conversion process can be turned off. This is because an image output from a PC often includes character information, and may be affected by appearance by converting the pixel position in a predetermined display pattern. In addition, when text information is displayed by OSD (on screen display), settings such as not performing pattern detection processing and pattern conversion processing for the OSD display area can be appropriately performed.

DESCRIPTION OF SYMBOLS 1 ... Liquid crystal panel, 2 ... Gate driver, 3 ... Source driver, 4 ... Display controller, 5 ... Pattern conversion part, 6 ... Pattern detection part.

Claims (5)

A liquid crystal panel having sub-pixels arranged in a matrix at intersections of a plurality of data signal lines and gate lines, wherein one pixel is constituted by the plurality of sub-pixels;
In a liquid crystal display device having a source driver that supplies gradation voltages for driving the liquid crystal of the sub-pixels by polarity inversion driving to each of the data signal lines based on the input image data.
A pattern detection unit that detects a match between a display pattern when the input image data is displayed on the liquid crystal panel and a predetermined display pattern;
A pattern conversion unit that converts the display pattern of the input image data when the pattern detection unit determines that the display pattern of the image data matches the predetermined display pattern;
When converting the display pattern, the pattern conversion unit converts the display pattern so that a change in the gradation voltage of each sub-pixel connected to the one data signal line during sequential scanning is reduced. A liquid crystal display device. The liquid crystal display device according to claim 1.
When converting the display pattern, the pattern conversion unit maintains the pixel value for each pixel of the image data to be supplied to the pixels constituting the display pattern to be converted, and the pixel to which the image display data is supplied The liquid crystal display device is characterized in that the display pattern is converted by changing. The liquid crystal display device according to claim 1 or 2,
The pattern detection unit determines the predetermined display pattern based on a luminance value for each pixel, compares the luminance value for each pixel of the input image data with the luminance value of the predetermined display pattern, and inputs the input A liquid crystal display device, wherein a match between the display pattern of the image data and the predetermined display pattern is detected. The liquid crystal display device according to claim 1 or 2,
The pattern detection unit determines the predetermined display pattern by a pixel value of a sub-pixel for displaying a specific color, a pixel value for displaying the specific color in the input image data, A liquid crystal display device, wherein a pixel value of a predetermined display pattern is compared to detect a match between the display pattern of the input image data and the predetermined display pattern. The liquid crystal display device according to claim 3 or 4,
The pattern detection unit provides a threshold value for determining the specific display pattern. When the display pattern of the input image data matches the specific display pattern within the threshold value range, the input is performed. A liquid crystal display device, characterized in that it is determined that a display pattern of image data matches the specific display pattern.

Images