JP2004086093A - Liquid crystal driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal driving device which improves unevenness of luminance of a liquid crystal display device, which is caused by change of a source line impedance. <P>SOLUTION: The liquid crystal driving device has a compensation data storage means wherein impedance-to-distance characteristics from a first driving means of a first signal line and/or impedance-to-distance characteristics from a second driving means of a second signal line are stored as compensation data and a video signal correction means which superposes the correction data on a video signal, and the corrected video signal is inputted to the first driving means. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal driving device, and particularly to a liquid crystal driving device in a large-sized liquid crystal display device.
[0002]
[Prior art]
In the liquid crystal display device, specific pixels in the horizontal and vertical directions on the screen are driven through signal lines stretched in a matrix in the horizontal and vertical directions by a source driver and a gate driver, and an image is displayed on the screen. You.
[0003]
In recent years, the size of the liquid crystal display device has been increased, and accordingly, a source line and a gate line which are signal lines from a source driver and a gate driver have become longer.
[0004]
By the way, when the source line and the gate line (that is, the wiring extending in the horizontal and vertical directions of the liquid crystal display device) become long, the impedance of the line becomes large, and a difference occurs in the voltage drop between the start end and the end. . This difference in voltage drop appears as uneven brightness on the screen.
[0005]
A method for improving such luminance unevenness is disclosed in Japanese Patent Application Laid-Open No. 4-237003. Hereinafter, the technology described in the above publication will be described.
[0006]
FIG. 11 is a configuration diagram described in the above publication. In FIG. 1A, 1101 is a liquid crystal display device, 1102 is a gate line, 1103 is a source line, and 1104 is a backlight.
[0007]
Here, the backlight 1104 is provided with a luminance distribution having a characteristic of offsetting a decrease in luminance level caused by a voltage drop of the source line 1103.
[0008]
This situation is shown in FIG. In FIG. 13B, reference numeral 1105 denotes the luminance level of the source line 1103, 1106 denotes the luminance level distribution of the backlight 1104, and 1107 denotes the luminance distribution obtained by adding the luminance level distribution 1105 of the source line 1103 and the luminance level distribution 1106 of the backlight 1104. It is.
[0009]
As described above, the luminance unevenness on the screen is improved by setting the luminance distribution of the backlight so as to cancel the decrease in the luminance level of the source line.
[0010]
[Problems to be solved by the invention]
In the above-described conventional techniques, since the luminance characteristics of the liquid crystal display device are offset by the luminance characteristics of the backlight, there is a problem that it takes time to adjust the luminance characteristics. In addition, there is also a concern that the luminance characteristics shift with the use period due to the temporal change of the respective luminance characteristics.
[0011]
In view of the above, an object of the present invention is to provide a liquid crystal driving device in which the luminance unevenness of a liquid crystal display device is improved.
[0012]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has taken the following measures.
[0013]
That is, the liquid crystal driving device according to the present invention includes: first driving means for driving a liquid crystal display element by at least a video signal and a synchronization signal; and second driving means for selecting at least a liquid crystal display element by a synchronization signal. A liquid crystal drive device comprising: a first signal line driven by the first driving means; and a second signal line driven by the second driving means, arranged in a matrix. The distance-to-impedance characteristic of one signal line from the first driving means or the distance-to-impedance characteristic of the second signal line from the second driving means, or the first signal line to the first signal line. Correction data storage means storing, as correction data, a distance-to-impedance characteristic of the distance from the second driving means and a distance-to-impedance characteristic of the second signal line from the second driving means; Comprising a video signal correction means for superimposing the correction data, and the corrected video signal is intended to be input to said first driving means.
[0014]
In this way, by superimposing the voltage drop due to the increase in the impedance of the signal line on the video signal in advance, it is possible to improve the luminance unevenness.
[0015]
A first driving unit for driving the liquid crystal display element by at least a video signal and a synchronization signal; and a second driving unit for selecting the liquid crystal display element by at least the synchronization signal, wherein the first driving unit In a liquid crystal driving device in which a first signal line driven by a first signal line and a second signal line driven by a second driving means are wired in a matrix, the first signal line of the first signal line The image processing apparatus may further include a correction data storage unit that stores, as correction data, a distance from a driving unit versus a gradation characteristic of the video signal, and a gradation control unit that controls gradation using the correction data.
[0016]
When the driving means is of a digital type, since the video signal level can take only discrete values, the luminance unevenness can be improved by correcting the video signal level so as to fall within the same gradation.
[0017]
A first driving unit that drives the liquid crystal display element by at least the video signal and the synchronization signal; a second driving unit that selects the liquid crystal display element by at least the synchronization signal; and the first driving unit and the second driving unit. A first signal line driven by the first driving means, the first signal line having a counter electrode for applying a counter voltage to the liquid crystal display element opposite to a driving voltage inputted from the driving means, and a second driving means A liquid crystal drive device in which the second signal line driven by the above is wired in a matrix, between the liquid crystal display element and the first signal line or between the liquid crystal display element and the counter electrode, or A resistance component according to a distance from the first driving unit may be provided between the liquid crystal display element and the first signal line and between the liquid crystal display element and the counter electrode.
[0018]
This makes it possible to correct the impedance change of the signal line for each liquid crystal element.
[0019]
A first driving unit that drives the liquid crystal display element by at least the video signal and the synchronization signal; a second driving unit that selects the liquid crystal display element by at least the synchronization signal; and the first driving unit and the second driving unit. A first signal line driven by the first driving means, the first signal line having a counter electrode for applying a counter voltage to the liquid crystal display element opposite to a driving voltage inputted from the driving means, and a second driving means And a second signal line driven in a matrix-like manner in a liquid crystal drive device, wherein a distance-to-impedance characteristic of the first signal line from the first driving means or a second signal line of the second signal line is provided. A distance-to-impedance characteristic from the second driving means, or a distance-to-impedance characteristic of the first signal line from the first driving means and a distance of the second signal line from the second driving means. A correction data storage means for storing pairs impedance characteristics as correction data, and the counter voltage control means for correcting the counter voltage applied to the counter electrode in said correction data, it may be provided with a.
[0020]
Here, a common voltage generating means for generating a plurality of common electrode voltages from the correction data, and a common voltage switching means for selecting the plurality of common electrode voltages generated according to a distance from the first driving means. And may be provided.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
First, a first embodiment of the present invention will be described.
[0022]
FIG. 1 is a block diagram of a liquid crystal driving device according to the present invention.
[0023]
In FIG. 1, reference numeral 101 denotes a video / chroma processing unit for adjusting the luminance level and color tone of an input video signal; 102, an analog / digital conversion unit for converting the video signal into a digital signal; An LCD (liquid crystal) controller unit for displaying, a correction data memory unit 104 for storing correction data described below, a control microcomputer 105 for controlling the operation of the liquid crystal driving device, and a backlight 106 for controlling a backlight A light power supply unit 107 is a gradation control unit that controls the gradation on the liquid crystal screen, 108 is a fluorescent tube as a backlight, and 109 is a driver unit that drives a liquid crystal panel.
[0024]
Here, the configuration other than the correction data memory unit 104 is the same as that of the conventional liquid crystal display device, and the description is omitted. Hereinafter, the operation of the correction data memory unit 104, which is a feature of the present invention, will be described.
[0025]
First, a configuration around the liquid crystal panel and the driver unit 109 is shown in FIG.
[0026]
2, reference numeral 201 denotes a video signal correction unit, 202 denotes a source driver, 203 denotes a gate driver, and 204 denotes a liquid crystal panel.
[0027]
The input video signal is output as a video signal in which the video signal correction unit 201 has corrected the voltage drop in the source line. The correction data for this is input from the correction data memory unit 104. By correcting the voltage drop in the video signal in this way, the luminance unevenness is improved.
[0028]
This will be described with reference to FIG. FIG. 3 shows the signal level distribution of the source line.
[0029]
FIG. 7A is a diagram showing a voltage drop due to an increase in the impedance of the source line. In this way, the source line voltage decreases as the distance from the source driver increases. FIG. 2B shows a correction signal to be corrected by the video signal correction unit 201 (that is, correction data stored in the correction data memory 104). FIG. 3C shows a video signal input to the video signal correction unit 201. A correction signal is added to this video signal. FIG. 3D shows the corrected video signal. FIG. 5E shows a video signal displayed on the liquid crystal panel as a luminance signal. As described above, by correcting the voltage drop due to the impedance of the source line in the video signal in advance, the video signal is offset each other, and a video signal without luminance unevenness is displayed on the liquid crystal panel.
[0030]
Next, a modification of the first embodiment of the present invention will be described.
[0031]
FIG. 4 shows an example of a liquid crystal display device in which source drivers are provided on both sides. In the figure, the same components as those in FIG. 1 are denoted by the same reference numerals.
[0032]
When there are source drivers on both sides, the voltage drop due to the line impedance becomes maximum at the center of the screen as shown in FIG. Therefore, the voltage drop becomes minimum at the center of the screen as shown in FIG. Therefore, the correction voltage should be maximized at the center of the screen as shown in FIG.
[0033]
Next, a second embodiment of the present invention will be described.
[0034]
The second embodiment is a case where the source driver is a digital driver. In the case of a digital driver, the gradation can take only discrete levels, so that the correction of the voltage drop due to the line impedance should be within the same gradation.
[0035]
This is shown in FIG. FIG. 6A is a diagram illustrating a decrease in the luminance level due to the influence of the line impedance. Lines A, B, and C are lines indicating the grayscale level. FIG. 7B is a diagram showing the correction voltage in this case. By storing such a correction voltage in the correction data memory unit 104 of FIG. 1 and controlling the gradation control unit 107 of FIG. 1 based on the correction voltage, the luminance signal level becomes the same level as shown in FIG. It falls within the range of the key.
[0036]
Next, a third embodiment of the present invention will be described.
[0037]
First, FIG. 7A shows a pixel structure of a liquid crystal panel.
[0038]
The liquid crystal panel realizes gradation display by controlling the amount of transmitted light of each pixel. The pixel controls the amount of transmitted light by controlling how the liquid crystal is twisted by a voltage applied to the liquid crystal due to a difference between a voltage from the source driver and a counter voltage.
[0039]
Therefore, as shown in FIG. 3B, one or both of the source electrode and the counter electrode have a resistance component, and the resistance component is changed depending on the distance from the driver, thereby compensating for the voltage drop due to the impedance of the source line. Can be.
[0040]
Next, a fourth embodiment of the present invention will be described.
[0041]
In the fourth embodiment, a voltage drop due to line impedance is absorbed by changing the voltage of the counter electrode.
[0042]
That is, as shown in FIG. 8A, the voltage applied to the liquid crystal unit shown in FIG. 7 changes due to the voltage drop due to the line impedance because the voltage applied to the counter electrode is constant as shown in FIG. As shown in FIG. 8 (b), if the opposing voltage applied to the opposing electrode also has a characteristic of dropping according to the voltage drop due to the line impedance, the voltage applied to the liquid crystal unit becomes constant and the luminance unevenness is improved.
[0043]
FIGS. 9 and 10 show a configuration for varying the counter voltage.
[0044]
9, reference numeral 901 denotes a correction data memory unit; 902, a counter voltage control unit; 903, an LCD (liquid crystal) controller unit; 904, a driver unit; and 905, a liquid crystal panel.
[0045]
Here, the correction data memory unit 901 has a coefficient or data in consideration of the drive line impedance, and the opposing voltage control unit uses the coefficient or data of the correction data memory unit 901 to perform opposition depending on the position of the pixel to be driven. Generate voltage.
[0046]
In FIG. 10, reference numeral 1001 denotes an opposing voltage generator, 1002 denotes an opposing voltage switching unit, 1003 denotes an LCD (liquid crystal) controller, 1004 denotes a driver, and 1005 denotes a liquid crystal panel.
[0047]
Here, the opposing voltage generation unit 1001 generates a plurality of types of opposing voltages, and the opposing voltage switching unit 1002 receives a plurality of types of the opposing voltages. The opposing voltage switching unit 1002 selects an appropriate one of a plurality of input opposing voltages depending on the position of the pixel to be driven, and outputs the selected opposing voltage to the driver unit 1004.
[0048]
【The invention's effect】
According to the present invention, it is possible to effectively improve luminance unevenness on a liquid crystal display screen due to a change in line impedance.
[Brief description of the drawings]
FIG. 1 is a block diagram of a liquid crystal driving device according to the present invention.
FIG. 2 is a block diagram around a liquid crystal panel and a driver section of the liquid crystal driving device according to the present invention.
FIG. 3 is an explanatory diagram of luminance correction in the liquid crystal driving device according to the present invention.
FIG. 4 is another block diagram of a liquid crystal panel and a driver section of the liquid crystal driving device according to the present invention.
FIG. 5 is another explanatory diagram of luminance correction in the liquid crystal driving device according to the present invention.
FIG. 6 is another explanatory diagram of luminance correction in the liquid crystal driving device according to the present invention.
FIG. 7 is a structural diagram of a liquid crystal pixel of the liquid crystal driving device according to the present invention.
FIG. 8 is another explanatory diagram of luminance correction in the liquid crystal driving device according to the present invention.
FIG. 9 is a block diagram for controlling a common electrode voltage in the liquid crystal driving device according to the present invention.
FIG. 10 is a block diagram for controlling a common electrode voltage in the liquid crystal driving device according to the present invention.
FIG. 11 is a block diagram of a conventional liquid crystal driving device.
[Explanation of symbols]
101: video / chroma processing unit, 102: A / D conversion unit, 103: LCD controller unit, 104: correction data memory unit, 105: microcomputer unit, 106: backlight Power supply unit, 107: gradation power supply unit, 108: fluorescent tube, 109: driver unit, 201: video signal correction unit, 202: source driver, 203: gate driver, 204: liquid crystal panel, 901: correction data memory section, 902: counter voltage control section, 903: LCD controller section, 904: driver section, 905: liquid crystal panel, 1001 ... Counter voltage generator, 1002 Counter voltage switching unit, 1003 LCD controller, 1004 Driver unit, 1005 Liquid crystal panel, 1101 Liquid Panel, 1102 ... gate driver, 1103 ... source driver, 1104 ... backlight, 1105 ... source driver luminance characteristics, 1106 ... backlight luminance characteristics, 1107 ... screen brightness characteristic

Claims (5)

A first driving unit that drives the liquid crystal display element by at least a video signal and a synchronization signal; and a second driving unit that selects the liquid crystal display element by at least the synchronization signal, and is driven by the first driving unit. In a liquid crystal driving device in which a first signal line to be driven and a second signal line driven by a second driving unit are wired in a matrix,
The distance-to-impedance characteristic of the first signal line from the first driving means or the distance-to-impedance characteristic of the second signal line from the second driving means, or the first signal line Correction data storage means for storing distance-impedance characteristics from the first drive means and distance-impedance characteristics of the second signal line from the second drive means as correction data;
Video signal correction means for superimposing the correction data on the video signal,
Wherein the corrected video signal is input to the first driving means. A first driving unit that drives the liquid crystal display element by at least a video signal and a synchronization signal; and a second driving unit that selects the liquid crystal display element by at least the synchronization signal, and is driven by the first driving unit. In a liquid crystal driving device in which a first signal line to be driven and a second signal line driven by a second driving unit are wired in a matrix,
Correction data storage means for storing distance of the first signal line from the first drive means versus gradation characteristics of the video signal as correction data;
Gradation control means for controlling gradation by the correction data,
A liquid crystal driving device comprising: First driving means for driving a liquid crystal display element by at least a video signal and a synchronizing signal; second driving means for selecting a liquid crystal display element by at least a synchronizing signal; and the first driving means and the second driving means An opposing electrode for applying an opposing voltage to the liquid crystal display element opposing the driving voltage input from the first driving means, a first signal line driven by the first driving means, and a driving means driven by the second driving means. And a second signal line to be wired in a matrix,
Between the liquid crystal display element and the first signal line or between the liquid crystal display element and the counter electrode, or between the liquid crystal display element and the first signal line and between the liquid crystal display element and the counter electrode. A liquid crystal driving device, wherein a resistance component according to a distance from the first driving means is provided between the first and second driving means. First driving means for driving a liquid crystal display element by at least a video signal and a synchronizing signal; second driving means for selecting a liquid crystal display element by at least a synchronizing signal; and the first driving means and the second driving means An opposing electrode for applying an opposing voltage to the liquid crystal display element opposing the driving voltage input from the first driving means, a first signal line driven by the first driving means, and a driving means driven by the second driving means. And a second signal line to be wired in a matrix,
The distance-to-impedance characteristic of the first signal line from the first driving means or the distance-to-impedance characteristic of the second signal line from the second driving means, or the first signal line Correction data storage means for storing distance-impedance characteristics from the first drive means and distance-impedance characteristics of the second signal line from the second drive means as correction data;
Counter voltage control means for correcting a counter voltage applied to the counter electrode with the correction data,
A liquid crystal driving device comprising: The liquid crystal driving device according to claim 4,
A common voltage generation unit configured to generate a plurality of common electrode voltages from the correction data;
Opposing voltage switching means for selecting the generated plurality of opposing electrode voltages according to a distance from the first driving means;
A liquid crystal display device comprising:

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