KR20080062473A - Liquid crystal display device and method of driving the same - Google Patents

Abstract

A liquid crystal display device and a driving method thereof are provided to improve image quality by compensating for a common voltage using digital pixel data for respective frames. An LCD(Liquid Crystal Display) device includes an LCD panel(102), an input portion, driving portions(104,106), and an adaptive common voltage generator(110). The LCD panel includes data lines, pixel regions, and a common voltage supply line, which supplies a common voltage to the pixel region. The input portion receives input data. The driving portions drive the LCD panel by using the pixel data from the input portion. The adaptive common voltage generator supplies the common voltage, which is changed according to APL(Average Picture Level) data of the pixel data by using the pixel data from the input portion.

Description

Liquid crystal display device and method of driving the same

1 is a view showing a conventional liquid crystal display device.

2 is a view showing a liquid crystal display device according to the present invention.

<Brief description of the main parts of the drawing>

102: liquid crystal panel 104: gate driver

106: data driver 108: timing controller

110: common voltage generator 112: data analysis unit

114: memory element 116: digital-to-analog converter

118: frame delay

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device and a driving method thereof capable of improving image quality.

Liquid crystal display device (Liquid crystal display device) is a trend that the application range is gradually widened due to the characteristics such as light weight, thin, low power consumption. In accordance with this trend, the liquid crystal display device is used for office automation equipment, audio / video equipment, and the like. On the other hand, the liquid crystal display device displays the desired image on the screen by adjusting the transmission amount of the light beam according to the image signal applied to the plurality of control switches arranged in a matrix form.

The liquid crystal display device includes a liquid crystal panel in which a liquid crystal layer is adjusted according to a transmission amount of the light beam, and a driving unit for driving the liquid crystal layer.

1 is a view showing a conventional liquid crystal display device.

As shown in FIG. 1, a conventional liquid crystal display device includes a liquid crystal panel 2 for displaying a predetermined image, a gate driver 4 and a data driver 6 for driving the liquid crystal panel 2, and A timing controller 8 controlling the gate driver 4 and the data driver 6, and a common voltage generator 10 supplying the common voltage Vcom to the liquid crystal panel 2.

The liquid crystal panel 2 includes a plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm, and a thin film transistor TFT, which is a switching element, and a thin film transistor TFT at an intersection thereof. A first substrate having an electrically connected pixel electrode formed thereon, a second substrate facing the first substrate and having a color filter and a common electrode formed thereon, and a liquid crystal layer formed between the first and second substrates.

The liquid crystal of the liquid crystal layer is driven at different angles according to a potential difference between the data voltage supplied from the data lines DL1 to DLm of the first substrate and the common voltage Vcom supplied to the common electrode of the second substrate. do.

The liquid crystal is turned at different angles according to the potential difference, and a predetermined image is displayed on the liquid crystal panel 2 according to the amount of light transmitted through the twisted angle.

The gate driver 4 sequentially supplies gate scan signals to the plurality of gate lines GL1 to GLn according to the gate control signal supplied from the timing controller 8.

The data driver 6 supplies a data voltage to the plurality of data lines DL1 to DLm according to a data control signal supplied from the timing controller 8.

The timing controller 8 generates the gate control signal and the data control signal using a vertical / horizontal synchronization signal (Vsync / Hsync) and a clock signal supplied from a system (not shown).

In addition, the timing controller 8 supplies the data driver 6 with the data supplied from the system properly aligned to match the mode of the liquid crystal panel 2.

The common voltage generator 10 supplies a common voltage Vcom having a constant voltage level to the common electrode formed on the second substrate of the liquid crystal panel 2. As described above, the common voltage Vcom serves to drive the liquid crystal layer of the liquid crystal panel 2 together with the data voltage.

The liquid crystal layer of the liquid crystal panel 2 is driven based on the potential difference between the common voltage Vcom and the data voltage based on the common voltage Vcom.

The common voltage Vcom generated by the common voltage generator 10 is a value set by an engineer in an optimal state in a manufacturing process. If the engineer incorrectly sets the common voltage Vcom in the manufacturing process, the image quality deterioration of the liquid crystal panel 2 occurs.

The liquid crystal of the liquid crystal layer is turned in accordance with the potential difference between the common voltage Vcom and the data voltage generated from the common voltage generator 10, and depends on the amount of light transmitted from a lamp (not shown) according to the degree of the twist. As a result, an image is displayed on the liquid crystal panel 2.

Since the common voltage Vcom is a reference voltage, when the common voltage Vcom is set incorrectly in the manufacturing process, defects such as deterioration in image quality may occur because the degree of distortion of the liquid crystal is different from the desired degree of distortion.

The common voltage Vcom is generally set using a plurality of resistors. When the common voltage Vcom is incorrectly set, it takes time to set the incorrectly set common voltage Vcom back to an optimal state. Work efficiency is reduced.

An object of the present invention is to provide a liquid crystal display device and a driving method thereof capable of improving image quality.

In addition, an object of the present invention is to provide a liquid crystal display device and a driving method thereof that can improve the work efficiency.

According to an exemplary embodiment of the present invention, a liquid crystal display device includes a plurality of pixel regions defined by a plurality of gate lines and a plurality of data lines, and a common voltage that is a reference voltage connected to each of the plurality of pixel regions. The pixel using a liquid crystal panel having a common voltage supply line to be supplied thereto, an input unit for inputting pixel data, a driver for driving the liquid crystal panel using pixel data from the input unit, and pixel data from the input unit. And an adaptive common voltage generator supplying a common voltage to the liquid crystal panel according to average luminance data of the data.

A driving method of a liquid crystal display device according to the present invention for achieving the above object is a method of driving a liquid crystal display device including a liquid crystal panel, including at least a predetermined level among the gray scale levels that the input pixel data may have Dividing two or more gray areas, and analyzing an average brightness value of the input pixel data to determine which one of the at least two gray areas corresponds to one of the at least two gray areas; If the average luminance value of the input pixel data corresponds to any one of the at least two gradation regions, outputting luminance data of the gradation region, and outputting digital common voltage data according to the luminance data. And converting the output digital common voltage data into an analog voltage. It is characterized in that it comprises a step of supplying to the liquid crystal panel by converting to and driving in response to the common voltage supplied to the liquid crystal panel.

Hereinafter, with reference to the accompanying drawings will be described an embodiment according to the present invention.

2 is a view showing a liquid crystal display device according to the present invention.

As shown in FIG. 2, the LCD according to the present invention includes a plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm to define a pixel area and display an image. 102, a gate driver 104 for driving the plurality of gate lines GL1 to GLn, a data driver 106 for driving the plurality of data lines DL1 to DLm, and the gate driver 104 ) And a timing controller 108 for controlling the data driver 106, and a common voltage generator 110 for supplying a common voltage Vcom to the liquid crystal panel 102.

In addition, the liquid crystal display according to the present invention further includes a frame delay unit 118 for delaying the digital pixel data Data supplied from a system (not shown) for one frame to the timing controller 108.

A plurality of gate lines GL1 to GLn and a plurality of data lines DL1 to DLm are arranged in the liquid crystal panel 102, and a thin film transistor TFT and a thin film transistor TFT, which are switching elements, An electrically connected pixel electrode is formed.

The liquid crystal panel 102 includes a first substrate on which the plurality of gate lines GL1 to GLn and the plurality of data lines DL1 to DLm are arranged, a color filter having red, green and blue colors, and a common electrode. And a liquid crystal layer formed between the second substrate and the first and second substrates.

The liquid crystal of the liquid crystal layer is between the pixel data voltage supplied to the pixel electrode through the plurality of data lines DL1 to DLm on the first substrate and the common voltage Vcom supplied to the common electrode of the second substrate. It is distorted at different angles according to the potential difference of.

The gate driver 104 may include a gate scan signal, ie, a gate high voltage VGH and a gate low voltage VGL, in the gate lines GL1 to GLn according to a gate control signal supplied from the timing controller 108. Supply sequentially. The thin film transistor TFT is controlled by the gate scan signal.

When the gate high voltage VGH is supplied to the plurality of gate lines GL1 to GLn, the thin film transistor TFT is turned on and gates to the plurality of gate lines GL1 to GLn. When the low voltage VGL is supplied, the thin film transistor TFT is turned off.

The data driver 106 supplies pixel data voltages to the plurality of data lines DL1 to DLm according to a data control signal supplied from the timing controller 108. The data driver 106 converts the digital pixel data supplied from the timing controller 108 into a pixel data voltage, which is an analog voltage corresponding to the digital pixel data, and supplies the same to the plurality of data lines DL1 to DLm.

The pixel data voltages supplied to the plurality of data lines DL1 to DLm are supplied to the pixel electrode through the thin film transistor TFT when the thin film transistor TFT is turned on. The pixel data voltage supplied to the pixel electrode becomes one driving voltage for driving the liquid crystal molecules of the liquid crystal layer.

The frame delay unit 118 delays the digital pixel data Data supplied from a system not shown for one frame to the timing controller 108. The frame delay unit 118 is used for the timing controller 110 and the timing controller for generating the common voltage using the digital pixel data Data supplied from the system (not shown). This is to adjust the progress timing at which the pixel data Data is supplied to 108.

The timing controller 108 controls the gate driver 104 and the data driver 106 by using a vertical / horizontal synchronization signal (Vsync / Hsync) supplied from a system (not shown) and a predetermined clock signal. Generates a data control signal to control

In addition, the timing controller 108 properly supplies the digital pixel data delayed by the frame delay unit 118 to the data driver 106 in accordance with the mode of the liquid crystal panel 102. In addition, the digital pixel data arranged from the timing controller 108 is supplied to the common voltage generator 110.

The common voltage generator 110 supplies different or the same common voltage Vcom for each frame to the liquid crystal panel 102 by using the digital pixel data Data for each frame supplied from a system (not shown).

Specifically, the operation of the common voltage generator 110 is as follows.

The common voltage generator 110 analyzes the brightness information of the digital pixel data supplied from a system (not shown) for each frame and outputs brightness data of the analyzed brightness information, and the brightness information of the brightness information. The memory device 114 storing the optimal digital common voltage data preset according to the luminance data, and the digital device converting the digital common voltage data output from the memory device 114 into analog and supplying the analog data to the liquid crystal panel 102. An analog converter 116.

The data analyzer 112 divides the gray level region into at least two gray levels to include a predetermined level among the gray-scale levels that the digital pixel data of each frame may have. In addition, the data analyzer 112 counts brightness information of the digital pixel data for each frame supplied from the system to determine whether the average brightness value of the brightness information corresponds to any one of the at least two gray areas. To judge.

When the average luminance value of the brightness information corresponds to one of the at least two gray areas, the data analyzer 112 outputs the luminance data set in the corresponding gray area to the memory device 114. Supply.

The memory device 114 previously stores digital common voltage data different from each other in correspondence with at least two gray level areas, including a predetermined level among gray-scale levels that the digital pixel data may have.

The memory device 114 outputs digital common voltage data corresponding to the luminance data by using the luminance data output from the data analyzer 112 as an address.

The memory device 114 outputs digital common voltage data corresponding to luminance data output from the data analyzer 112 and supplies the digital common voltage data to the digital-analog converter 116.

In this case, the memory device 114 may include a nonvolatile memory. For example, the memory device 114 may include any one of a ROM, an EEPROM, and a flash memory.

The digital-analog converter 116 converts the digital common voltage data output from the memory device 114 into a common voltage Vcom which is an analog voltage. The converted common voltage Vcom is supplied to the liquid crystal panel 102 during the frame analyzed by the data analyzer 112.

The common voltage Vcom serves to drive the liquid crystal layer formed on the liquid crystal panel 102. The common voltage Vcom may be different or the same for each frame.

As described above, the data analyzing unit 112 counts brightness information of digital pixel data supplied from the system during the first frame, for example, analyzes the average brightness value of the counted brightness information, and analyzes the average brightness. It is determined whether a value corresponds to the at least two gradation regions.

When the average luminance value corresponds to any one of the at least two gray areas, the data analyzer 112 outputs the luminance data of the corresponding gray area to the memory device 114.

The memory device 114 outputs digital common voltage data corresponding to luminance data supplied from the data analyzer 112 and supplies the digital common voltage data to the digital-analog converter 116. The digital-analog converter 116 converts digital common voltage data output from the memory device 114 into a common voltage Vcom, which is an analog voltage, and supplies the same to the liquid crystal panel 102 during the first frame.

The liquid crystal layer formed on the liquid crystal panel 102 is driven by the common voltage Vcom during the first frame.

Subsequently, the data analyzer 112 receives digital pixel data to be displayed on the liquid crystal panel 102 from a system in a second frame, which is a next frame, counts brightness information of the digital pixel data, and counts the brightness. Analyze the information. The data analyzer 112 determines which gray area on the at least two gray areas corresponds to the average brightness value of the analyzed brightness information.

The data analyzer 112 outputs the luminance data of the corresponding grayscale area to the memory device 114 when the average brightness value of the brightness information corresponds to any one grayscale area on the at least two grayscale areas. do.

The memory device 114 outputs digital common voltage data corresponding to luminance data supplied from the data analyzer 112 and supplies the digital common voltage data to the digital-analog converter 116. The digital-analog converter 116 converts the digital common voltage data output from the memory device 114 into a common voltage Vcom, which is an analog voltage, and supplies the same to the liquid crystal panel 102 during the second frame.

When the data to be displayed on the liquid crystal panel 102 is the same during the first and second frames, the data analyzer 112 outputs the same luminance data during the first and second frames, and the memory device 114 The digital common voltage data corresponding to the luminance data is output. The digital common voltage data is converted into the same common voltage Vcom during the first and second frames through the digital-analog converter and supplied to the liquid crystal panel 102.

As described above, the common voltage generator 110 supplies the compensated common voltage Vcom to the liquid crystal panel 102 for each frame by using digital pixel data to be displayed on the liquid crystal panel 102 for each frame. .

The common voltage generator 110 generates the compensated common voltage Vcom for each frame by using the digital pixel data to be displayed for each frame on the liquid crystal panel 102. ), You can improve the efficiency of your work.

In addition, since the common voltage generator 110 supplies the common voltage Vcom compensated for each frame to the liquid crystal panel 102, the image quality may be improved.

As mentioned above, the liquid crystal display according to the present invention generates a common voltage compensated for each frame by using digital common voltage data compensated for each luminance data and digital pixel data to be displayed on the liquid crystal panel for each frame. Can improve.

As described above, the LCD according to the present invention can improve image quality by outputting a common voltage compensated for each frame and supplying it to the liquid crystal panel using digital pixel data for each frame.

In addition, in the liquid crystal display according to the present invention, since the engineer does not set the common voltage Vcom in the mass production process, the work efficiency may be improved.

Although the present invention has been described with reference to the embodiments, those skilled in the art may variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that.

Claims (7)

A liquid crystal panel in which a plurality of pixel regions defined by a plurality of gate lines and a plurality of data lines and a common voltage supply line connected to each of the plurality of pixel regions and supplying a common voltage as a reference voltage to the pixel region are arranged; An input unit for inputting pixel data; A driving unit driving the liquid crystal panel using pixel data from the input unit; And And an adaptive common voltage generator for supplying a common voltage to the liquid crystal panel based on the average luminance data of the pixel data using the pixel data from the input unit. The method of claim 1, And a frame delay unit for delaying the pixel data from the input unit by one frame. The method of claim 1, The adaptive common voltage generator, A memory device configured to store different digital common voltage data corresponding to at least two gray level areas divided to include a predetermined level among gray scale levels of the pixel data; And The grayscale level may be divided into two or more grayscale levels, and the average luminance value of the pixel data input from the input unit may be analyzed to determine the analyzed average luminance value. A data analyzer configured to output luminance data of the corresponding area to the memory device when it corresponds to any one of the above grayscale areas; The luminance data output from the data analyzer is used as an address for reading digital common voltage data from the memory device. The method of claim 3, wherein The adaptive common voltage generator further comprises a digital analog converter for converting the digital common voltage data output from the memory device into a common voltage, which is an analog voltage, and supplying the common voltage to the liquid crystal panel. The method of claim 2, And the memory device comprises a nonvolatile memory. The method of claim 5, The memory device comprises any one of a ROM, EEPROM and Flash memory. In the driving method of a liquid crystal display device comprising a liquid crystal panel, Dividing at least two gray level areas to include a predetermined level among gray scale levels that the input pixel data may have; Analyzing an average luminance value of the input pixel data to determine whether the analyzed average luminance value corresponds to any one of the at least two gray level regions; Outputting luminance data of the gradation region when the average luminance value of the input pixel data corresponds to any one of the at least two gradation regions; Outputting digital common voltage data according to the luminance data; Converting the output digital common voltage data into a common voltage which is an analog voltage and supplying the converted common voltage data to the liquid crystal panel; And And driving in response to a common voltage supplied to the liquid crystal panel.

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