KR101277875B1 - Liquid Crystal Display Device Responsive to Position of User and Driving Method thereof - Google Patents

Abstract

A user position sensitive liquid crystal display device capable of controlling the viewing angle of an image is disclosed.

The above liquid crystal The display device includes a liquid crystal panel including liquid crystal cells arranged in a matrix; A gate driver for driving the liquid crystal cells by one line; A data driver converting pixel data of each line into a pixel driving signal required by the liquid crystal cells using a gamma voltage set and supplying the pixel data to the liquid crystal cells; An adaptive gamma voltage generator configured to generate the gamma voltage set; And a position sensitive controller for dividing the front of the liquid crystal panel into a plurality of viewing angle regions and adjusting a range of occupied voltage levels of the gamma voltage set to be output from the adaptive gamma voltage generator according to the viewing angle region in which the user is located.

By such a configuration, the liquid crystal display device provides the user with the best image quality regardless of the position of the user.

User, Location, Gamma Voltage, LCD, Camera, Select, Data Driver.

Description

Liquid crystal display device responsive to position of user and driving method

1 is a block diagram schematically illustrating a user position sensitive liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 2 is a detailed circuit diagram illustrating a pixel on the liquid crystal panel in FIG. 1.

FIG. 3 is a detailed block diagram illustrating in detail an embodiment of the position-adaptive gamma voltage generator shown in FIG. 1.

FIG. 4 is a detailed circuit diagram illustrating another embodiment of the position-adaptive gamma voltage generator shown in FIG. 1 in detail.

≪A brief description of the main parts of the drawings≫

10: liquid crystal panel

12: gate driver

14: data driver

16: timing controller

18: observer detector

20: position detection unit

22: position adaptive gamma voltage generator

30: look-up table

32: D-A Converter Array

40A to 40E: first to fifth gamma voltage generators

42: selector

The present invention relates to a liquid crystal display device for displaying an image on a liquid crystal panel, and more particularly, to a liquid crystal display device for controlling an angle at which an image can be viewed and a driving method thereof.

An ordinary liquid crystal display device displays an image corresponding to video data by adjusting a light transmittance of a liquid crystal in accordance with video data. Such a liquid crystal display device can make the size of the screen larger than the limit while reducing the thickness. Further, the liquid crystal display device can be made slimmer and lighter. In view of this, the liquid crystal display device is used as a display device of a computer or a display device of a television receiver instead of a cathode ray tube (Cathode Ray Tube) display device.

In order to display an image corresponding to video data, the liquid crystal display includes drive circuits for driving the liquid crystal panel. The liquid crystal panel includes liquid crystal cells arranged in a matrix form. Each of the liquid crystal cells responds to a pixel drive signal from the drive circuit. The driving circuits convert the pixel data included in the video data into a pixel driving signal in an analog form required by liquid crystal cells. In addition, the driving circuits supply the converted pixel driving signal to each of the liquid crystal cells on the liquid crystal panel. Each of the liquid crystal cells orientates liquid crystal molecules in a direction corresponding to the voltage level (ie, potential difference) of the pixel driving signal. The amount of light passing through the liquid crystal cell is adjusted in accordance with the alignment direction of the liquid crystal molecules, so that an image is displayed.

As described above, the liquid crystal display device displays an image by adjusting the alignment direction of the liquid crystal molecules, so that the advancing direction of the light passing through the liquid crystal panel is biased in a specific direction. For this reason, in the liquid crystal display, the angle at which the image can be viewed (that is, the viewing angle) is limited. As a result, the liquid crystal display has no choice but to provide an image of color inversion and / or distorted picture quality to a user (or viewer) at a position outside the limited viewing angle.

It is an object of the present invention to provide a liquid crystal display and a driving method capable of controlling the viewing angle of an image.

Another object of the present invention is to provide a liquid crystal display device and a driving method thereof suitable for providing an image of the best image quality to a user regardless of the position of the user.

According to an aspect of the present invention, a liquid crystal display device includes: a liquid crystal panel including liquid crystal cells arranged in a matrix; A gate driver for driving the liquid crystal cells by one line; A data driver converting pixel data of each line into a pixel driving signal required by the liquid crystal cells using a gamma voltage set and supplying the pixel data to the liquid crystal cells; An adaptive gamma voltage generator configured to generate the gamma voltage set; And a position sensitive control unit for dividing the front of the liquid crystal panel into a plurality of viewing angle regions and adjusting a range of occupied voltage levels of the gamma voltage set to be output from the adaptive gamma voltage generator according to the viewing angle region in which the user is located.

The adaptive gamma voltage generator comprises: a plurality of gamma voltage generators for generating a gamma voltage set occupying different voltage level ranges; And a selector for allowing a plurality of gamma voltage sets from the plurality of gamma voltage generators to be selectively supplied to the data driver under control of the position sensitive control.

The plurality of gamma voltage sets partially overlap with an adjacent gamma voltage set in the range of occupied voltage levels.

Some of the plurality of gamma voltage sets are set to have a voltage level of a negative region based on a common voltage supplied to the liquid crystal cell, while others are set to have a voltage level of a positive region based on the common voltage. It is preferable.

The adaptive gamma voltage generator comprises: a look-up table for selectively reading gamma voltage data sets each having gamma voltage data specifying voltage levels of different voltage level ranges under the control of the position sensitive controller; And a D-A converter array for converting the gamma voltage data set from the look-up table into the gamma voltage set in analog form.

The position sensitive control unit may include a detector configured to detect a user in front of the liquid crystal panel; And a position detector configured to detect a viewing angle region in which the user is located from the signal sensed by the detector, and to change a voltage level range of the gamma voltage set to be output from the adaptive gamma voltage generator according to the detected viewing angle region. do.

The sensing unit may include one of a video camera and a still video camera.

According to another aspect of the present invention, there is provided a method of driving a liquid crystal display device, comprising: a liquid crystal panel including liquid crystal cells arranged in a matrix form, wherein the liquid crystal cells require pixel data for each line using a gamma voltage set; The present invention relates to a liquid crystal display device including a data driver for converting a pixel driving signal into a liquid crystal cell. The method of driving the liquid crystal display includes: detecting a user who is in front of the liquid crystal panel; Detecting which area of the plurality of viewing angle areas the detected user is located in advance; And causing any one of a plurality of preset gamma voltage sets to be supplied to the data driver according to the detected viewing angle region of the user.

Other objects, other features, and other advantages of the present invention in addition to the above objects will become apparent from the detailed description of the embodiments associated with the accompanying drawings.

Best Mode for Carrying Out the Invention Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically illustrating a liquid crystal display according to an exemplary embodiment of the present invention. Referring to FIG. 1, in the user position sensitive liquid crystal display according to the exemplary embodiment, the gate driver 12 and the liquid crystal panel 10 connected to a plurality of gate lines GL1 to GLn on the liquid crystal panel 10 may be described. The data driver 14 is connected to a plurality of data lines DL1 to DLm. The plurality of gate lines GL1 to GLn and the plurality of data lines DL1 to DLm are formed on the liquid crystal panel 10 so as to intersect with each other to divide a plurality of pixel regions. Pixels as shown in FIG. 2 are formed in each of the plurality of pixel regions.

As shown in FIG. 2, the pixel includes a thin film transistor MT and a liquid crystal cell CLC connected in series between a corresponding data line DL and a common voltage line Vcom. The thin film transistor MT switches the pixel driving signal to be supplied to the corresponding liquid crystal cell CLC from the corresponding data line DL in response to a scan signal on the corresponding gate line GL. When the corresponding thin film transistor MT is turned on, the liquid crystal cell CLC charges the pixel driving signal from the corresponding data line DL. The liquid crystal cell CLC maintains the charged pixel driving signal until the corresponding thin film transistor MT is turned on again. By the pixel driving signal charged in the liquid crystal cell CLC, the liquid crystal molecules included in the liquid crystal cell CLC are aligned in a direction corresponding to a potential difference between the charged pixel driving signal and the common voltage Vcom on the common voltage line. The amount of light passing through the liquid crystal cell CLC is adjusted. As described above, the liquid crystal panel 10 of FIG. 1 displays an image by the liquid crystal cell CLC that adjusts the light transmission amount according to the potential difference between the pixel driving signal and the common voltage Vcom.

Referring back to FIG. 1, the gate driver 12 sequentially enables a plurality of gate lines GL1 to GLn by a predetermined period (for example, one horizontal synchronization signal) for one frame. Let's do it. To this end, the gate driver 12 generates a plurality of scan signals exclusively having enable pulses sequentially shifted for each period of the horizontal synchronization signal. The gate enable pulse included in each of the plurality of scan signals has the same width as the period of the horizontal synchronization signal. The enable pulses included in each of the plurality of scan signals are generated once per frame period. To generate these multiple scan signals, gate driver 12 responds to gate control signals GCS from timing controller 16. The gate control signals GCS include a gate start pulse GSP and a gate clock GSC. The gate start pulse GSP has a pulse that maintains a specific logic (eg, high logic) for the duration of one horizontal sync signal from the start of the frame period. The gate clock GSC has the same period as the horizontal synchronization signal.

The data driver 14 corresponds to the number of data lines DL1 to DLm (ie, the number of pixels arranged in one gate line each time one of the plurality of gate lines GL1 to GLn is enabled). To generate pixel driving signals. Each pixel driving signal corresponding to one line is supplied to a corresponding pixel (ie, a liquid crystal cell) on the liquid crystal panel 10 via a corresponding data line DL. Each of the pixels arranged on the gate line GL passes an amount of light corresponding to a voltage level of the pixel driving signal. In order to generate pixel drive signals for one line, the data driver 14 sequentially inputs one line of pixel data for each period of the enable pulse included in the scan signal. The data driver 14 converts the sequentially input pixel data of one line into a pixel drive signal in analog form using a gamma voltage set including gamma voltages. The gamma voltages included in the gamma voltage set determine a voltage difference between gray levels of the pixel driving signal and a swing width of the pixel driving signal.

The gate driver 12 and the data driver 14 are controlled by the timing controller 16. The timing controller 16 inputs the synchronization signals SYNC from an external video data source (for example, an image signal demodulator included in a television receiver or a graphics card included in a computer system). The synchronization signals SYNC supplied from an external video data source include a data clock Dclk, a horizontal synchronization signal Hsync, a vertical synchronization signal Vsync, and the like. The timing controller 16 uses the sync signals SYNC to generate a plurality of scan signals for the gate driver 12 to sequentially scan the plurality of gate lines GL1 to GLn on the liquid crystal panel 10 every frame. Generate gate control signals GCS necessary to generate. The gate control signals GCS include a gate start pulse GSP and a gate clock GSC. In addition, the timing controller 16 causes the data driver 12 to sequentially input pixel data for one line for each cycle in which the gate line GL is enabled, and sequentially input the pixel data for one line. The data control signals DCS are required to be converted and output into a pixel driving signal in a form. Further, the timing controller 16 inputs a pixel data stream VDi divided in frame units (one image unit) from the video data source. The timing controller 16 divides the pixel data stream VDi into pixel data for each line and supplies the pixel data stream VDi to the data driver 14.

The liquid crystal display of FIG. 1 includes a position detector 20 and a position adaptive gamma voltage generator 22 connected in series between the observer detector 18 and the data driver 14. The observer detector 18 photographs the front direction of the liquid crystal panel 10 at a predetermined period (for example, 1/30 sec or 1/60 sec) and supplies the captured video signal to the position detector 20. The observer detector 18 may be a video camera or a still video camera.

The position detector 20 detects the position of an observer (ie, a user or a viewer) by comparing the current video signal from the observer detector 18 with the previous video signal. Based on the detected observer's position, the position detector 18 detects how many degrees the observer's position is with respect to the surface of the liquid crystal panel 10, and the detected observer's angle is a predetermined number of preset points. Which of the viewing angle regions belongs to the viewing angle region. The position detector 20 supplies the viewing angle address PDC corresponding to the determined viewing angle region to the position adaptive gamma voltage generator 22.

The position-adaptive gamma voltage generator 22 supplies the data driver 14 with a gamma voltage set corresponding to a logic value of the viewing angle address PDC from the position detector 20 among a predetermined number of gamma voltage sets. Half of a certain number of gamma voltage sets are located in the negative region relative to the common voltage (Vcom) (that is, have a lower voltage level than the common voltage (Vcom)), while the other half is the common voltage (Vcom). It is located in the positive region as a reference (ie, has a voltage level higher than the common voltage Vcom). The voltage level range occupied by each of the gamma voltage sets belonging to the positive region with respect to the common voltage Vcom is set to partially overlap with the voltage level range of the adjacent gamma voltage set. Similarly, gamma voltage sets belonging to the negative polarity region based on the common voltage Vcom are also set to partially overlap with the adjacent gamma voltage set in the voltage level range occupying.

Thus, the gamma voltage set whose voltage level range changes according to the viewing angle at which the user is located is supplied to the data driver 14, thereby providing the pixel driving signal supplied from the data driver 14 to the liquid crystal cell CLC on the liquid crystal panel 10. The voltage swing is also moved. Accordingly, the range of the orientation angle of the liquid crystal molecules included in the liquid crystal cell CLC is shifted so that the image displayed on the liquid crystal panel 10 has the best image quality at a constant angle with respect to the position of the observer (ie, the user or the viewer). Will have For example, when the observer moves at a large angle to the right in a direction perpendicular to the surface of the liquid crystal panel 10, the gamma voltage set supplied to the data driver 14 by the position-adaptive gamma voltage generator 22 The voltage range of may have a negative constant range voltage level away from the common voltage Vcom. On the contrary, when the observer moves at a large angle to the left in a direction perpendicular to the surface of the liquid crystal panel 10, the voltage of the gamma voltage set supplied to the data driver 14 by the position-adaptive gamma voltage generator 22 The range may have a constant range voltage level of positive polarity away from the common voltage Vcom.

The liquid crystal display of FIG. 1 includes a common voltage generator not shown. The common voltage generator supplies the common voltage Vcom to the liquid crystal cells CLC on the liquid crystal panel 10.

FIG. 3 is a detailed block diagram illustrating an example of the position-adaptive gamma voltage generator 22 shown in FIG. 1 in detail. The position-adaptive gamma voltage generator 22 of FIG. 3 includes a D-A converter array 32 connected to the look-up table 30. The look-up table 30 converts the gamma voltage data set stored in the storage area corresponding to the logic value of the viewing angle address PDC from the position detector 20 shown in FIG. 32). To this end, a gamma voltage data set having grayscale values representing voltage levels in a voltage level range is stored in each of the storage areas of the look-up table 30 according to logic values that the viewing angle address PCD may have. Half of a certain number of gamma voltage data sets stored in the look-up table 30 specify voltage levels in the negative region relative to the common voltage Vcom (ie, lower voltage levels than the common voltage Vcom). While the other half specifies the voltage levels of the positive region relative to the common voltage Vcom (i.e., specifies a voltage level higher than the common voltage Vcom). Some of the gamma voltage data included in each of the gamma voltage data sets specifying voltage levels of the positive region with respect to the common voltage Vcom is set to have the same logic value as those of the adjacent gamma voltage data set. Similarly, some of the gamma voltage data included in each of the gamma voltage data sets specifying voltage levels of the negative region with respect to the common voltage Vcom may have the same logic value as those of the adjacent gamma voltage data set. have.

The D-A converter array 32 includes D-A converters corresponding to the number of gamma voltage data included in the gamma voltage set. This D-A converter array 32 converts the gamma voltage data set from the look-up table 30 into an analog form to generate gamma voltage sets with different occupied voltage level ranges depending on the viewing angle region. The gamma voltage set generated in this D-A converter array 32 is supplied to the data driver 14 shown in FIG.

4 is a detailed block diagram illustrating another embodiment of the position-adaptive gamma voltage generator 22 shown in FIG. 1 in detail. The position-adaptive gamma voltage generator 22 of FIG. 4 will be described on the assumption that the region where the observer is located on the front side of the liquid crystal panel 10 is divided into five viewing angle regions.

Referring to FIG. 4, the position adaptive gamma voltage generator 22 includes a selector 42 connected to the first to fifth gamma voltage generators 40A to 40E. Each of the first to fifth gamma voltage generators 40A to 40E generates a set of gamma voltages that differ in the range of voltage levels they occupy. The first gamma voltage set generated at the first gamma voltage generator 40A includes gamma voltages lower than the second gamma voltage set generated at the second gamma voltage generator 40B. The second gamma voltage set generated by the second gamma voltage generator 40B includes gamma voltages lower than the third gamma voltage set generated by the third gamma voltage generator 40C. The first to third gamma voltage sets occupy a negative voltage level region shifted by a predetermined voltage level based on the common voltage Vcom. The fourth gamma voltage set generated by the fourth gamma voltage generator 40D includes gamma voltages lower than the fifth gamma voltage set generated by the fourth gamma voltage generator 40E. The fifth gamma voltage set is set to have a voltage level range shifted higher by a predetermined voltage level from the occupation voltage level range of the fourth gamma voltage set in the positive voltage level region based on the common voltage Vcom.

The selector 42 selects any one of the first to fifth gamma voltage sets from the first to fifth gamma voltage generators 40A to 40E according to the logic value of the viewing angle address from the position detector 20 shown in FIG. 1. Choose one. The gamma voltage set selected by the selector 42 is supplied to the data driver 14 shown in FIG.

As described above, in the user position-sensitive liquid crystal display device and the driving method thereof, the voltage level range of the gamma voltage set is varied according to the viewing angle at which the observer or the user is positioned to supply the pixel to the liquid crystal cell on the liquid crystal panel. The swing voltage range of the drive signal is also shifted. Accordingly, the range of the orientation angle of the liquid crystal molecules included in the liquid crystal cell is shifted. As a result, the image displayed on the liquid crystal panel has the best image quality at a constant angle with respect to the position of the observer (ie, the user or the viewer).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It will be apparent that various modifications, alterations, and other equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the technical idea and scope of the present invention to be protected must be determined by the appended claims.

Claims (10)

A liquid crystal panel including liquid crystal cells arranged in a matrix form; A gate driver for driving the liquid crystal cells line by line: A data driver converting pixel data of each line into a pixel driving signal required by the liquid crystal cells using a gamma voltage set and supplying the pixel data to the liquid crystal cells; An adaptive gamma voltage generator configured to generate the gamma voltage set; And And a position sensitive controller for dividing the front of the liquid crystal panel into a plurality of viewing angle regions and adjusting a range of occupied voltage levels of the gamma voltage set to be output from the adaptive gamma voltage generator according to the viewing angle region at which the user is located. The position sensitive control unit may include a detection unit for detecting a user in front of the liquid crystal panel; And a position detector configured to detect a viewing angle region in which the user is located from the signal sensed by the detector, and to change a voltage level range of the gamma voltage set to be output from the adaptive gamma voltage generator according to the detected viewing angle region. A user position-sensitive liquid crystal display device, characterized in that. The method of claim 1, wherein the adaptive gamma voltage generator A plurality of gamma voltage generators for generating gamma voltage sets occupying different voltage level ranges; And And a selector for selectively supplying a plurality of gamma voltage sets from the plurality of gamma voltage generators to the data driver under the control of the position sensitive control unit. The liquid crystal display of claim 2, wherein the plurality of gamma voltage sets partially overlap with an adjacent gamma voltage set in an occupied voltage level range. The method of claim 3, wherein some of the plurality of gamma voltage sets are set to have a voltage level of a negative region based on a common voltage supplied to the liquid crystal cell, while the rest of the plurality of gamma voltage sets are defined in the positive region based on the common voltage. A user-sensitive liquid crystal display device, characterized in that it is set to have a voltage level. The method of claim 1, wherein the adaptive gamma voltage generator A look-up table for selectively reading gamma voltage data sets each having gamma voltage data designating voltage levels in a different voltage level range under the control of the position sensitive control; And And a D-A converter array for converting the gamma voltage data set from the look-up table into the gamma voltage set in analog form. delete The liquid crystal display of claim 1, wherein the sensing unit comprises one of a video camera and a still video camera. A liquid crystal panel including a liquid crystal panel including liquid crystal cells arranged in a matrix form, and a data driver for converting pixel data for each line into pixel driving signals required by the liquid crystal cells using a gamma voltage set and supplying the liquid crystal cells to the liquid crystal cells. In the method of driving a display device, Detecting a user in front of the liquid crystal panel: Detecting which area of the plurality of viewing angle areas the detected user is located in advance; And Causing any one of a plurality of preset gamma voltage sets to be supplied to the data driver according to the detected viewing angle region of the user, And the plurality of gamma voltage sets partially overlap with an adjacent gamma voltage set in an occupied voltage level range. delete The method of claim 8, wherein some of the plurality of gamma voltage sets are set to have a voltage level of a negative region based on a common voltage supplied to the liquid crystal cell, while the rest of the plurality of gamma voltage sets are arranged in the positive region based on the common voltage. A driving method of a user-sensitive liquid crystal display device, characterized in that it is set to have a voltage level.

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