JPH0784552A - Driving circuit for display device - Google Patents

Abstract

PURPOSE:To provide the driving circuit for the display device which eliminates unequal display in a gate line direction and is capable of making good display CONSTITUTION:This driving circuit for the display device has a liquid crystal display panel 1 having plural gate lines 9 and data lines 8, gate drivers 3-1 to 3-m for selecting the arbitrary pixel rows of this liquid crystal display panel 1 and data drivers 2-1 to 2-n for applying the voltages to be applied the pixel rows selected by these gate drivers 3-1 to 3-m to the data lines 8 and makes display of inputted video signals DATA by controlling the gate drivers 3-1 to 3-m and the data drivers 2-1 to 2-n. The driving circuit described above has a central voltage correction section 5 for conversion to AC which changes the central potential in the conversion of the voltages to be applied to the data lines 8 with respect to the pixel row direction of the liquid crystal display panel 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit of a matrix type display device, and more particularly to a drive circuit of a display device which is free from display unevenness and can display favorably.

In recent years, the liquid crystal display device, which is one of the matrix type display devices, has been attracting attention as a display device to replace the CRT because the device can be made thinner.
Various technical developments have been made to improve the display quality.

[0003]

2. Description of the Related Art FIG. 7 shows a configuration diagram of a drive circuit of a conventional liquid crystal display device. In the same figure, the drive circuit of the liquid crystal display device of this conventional example includes a liquid crystal display panel 1 to be driven, data drivers 2-1 to 2-n that drive data lines 8, and a gate driver that drives gate lines 9. 3-1 to 3-m and R
Data drivers 2-1 to 2-from the GB video signal DATA
and an image signal processing unit 4 for generating an analog image signal data supplied to n.

Serially input analog video signal da
ta is fetched by the data drivers 2-1 to 2-n corresponding to each data line 8 based on the data synchronization signal D _sync ,
The data drivers 2-1 to 2-n output the voltage corresponding to the data data to each data line 8 at the same time based on the line synchronization signal L _sync .

At this time, the gate drivers 3-1 to 3-m
Line sync signal L _sync and frame sync signal F _sync
According to the above, an arbitrary gate line 9 is selected, and the voltage of the data line 8 is applied to the pixel electrode corresponding to the intersection of the gate line 9 and the data line 8 via a TFT (thin film transistor).

Each pixel electrode performs display by applying a voltage according to the analog video signal data to the liquid crystal between the common electrode, which is a common electrode common to all pixel electrodes. An alternating voltage is applied to the voltage applied to the liquid crystal in order to prevent deterioration of the liquid crystal. Therefore, even if the same display is performed, the voltage applied to the pixel electrode is opposite in polarity to the common electrode every frame.

Data driver 2 for driving data line 8
-1 to 2-n include an analog driver whose input video signal is an analog signal data and a digital signal d.
There is a digital driver that is ata '. The data drivers 2-1 to 2-n of this conventional example are configured as analog drivers.

The analog video signal data input to the analog driver is generated by the analog video signal processing unit 4 having the circuit configuration shown in FIG. A general RGB image signal DATA and the amplifying unit 31 for changing to the appropriate amplitude for driving the liquid crystal, the AC unit 3 for alternating the amplified signal A _{ou t}
2, and the generated analog video signal data is
The voltage is taken into the analog driver and applied to the data line 8.

On the other hand, in the case of the digital driver, a plurality of voltage levels are input to the digital driver as liquid crystal drive voltages, and these voltage levels are selected or the voltage levels are calculated according to the digital video signal data 'and the data is calculated. Apply voltage to the wire.

[0010]

Therefore, in the drive circuit of the conventional liquid crystal display device, the voltage written to the pixel electrode of the liquid crystal display panel 1 is the parasitic capacitance inside the liquid crystal display panel 1, the gate line 9 and the data line 8. Due to the resistance distribution and the like, the voltage applied to the data line 8 from outside the liquid crystal display panel 1 is displaced. If this deviation is constant inside the liquid crystal display panel 1, it can be corrected by adjusting the potential of the common electrode which is the counter electrode.

However, due to the rounding of the waveform of the voltage of the gate line due to the resistance distribution of the gate line 9, there is a difference in this deviation along the gate line 9. Therefore, in the gate line direction of the liquid crystal display panel 1, as shown in FIG. 4A, the common electrode potential is inclined, but since the common electrode is an electrode common to all pixel electrodes, a constant voltage is applied. Can only be given. As a result, there is a problem in that a portion where the voltage applied to the liquid crystal is not appropriate occurs on the liquid crystal display panel 1 and display unevenness occurs.

Further, although this display unevenness is already remarkable in the liquid crystal display panel, it is a phenomenon generally occurring not only in the liquid crystal display panel but also in a matrix type display device. The present invention solves the above problems, and an object of the present invention is to provide a drive circuit for a matrix-type display device that eliminates display unevenness in the gate line direction and enables good display.

[0013]

In order to solve the above-mentioned problems, the driving circuit of the matrix type display device of the first feature of the present invention has a plurality of gate lines 9 and data lines 8 as shown in FIG. And a gate driver 3-1 to 3-m for selecting an arbitrary pixel row of the display panel 1.
And the data drivers 2-1 to 2-n for applying the voltage to be applied to the pixels of the pixel row selected by the gate drivers 3-1 to 3-m to the data line 8, the gate driver 3-1. To 3-m and data drivers 2-1 to 2-
In the drive circuit of the matrix type display device which controls n to display the input video signal DATA, the center potential in the alternating current of the voltage applied to the data line 8 is
The display panel 1 is configured to have an AC center voltage correction unit 5 that changes in the pixel row direction.

The drive circuit of the matrix type display device according to the second aspect of the present invention is the drive circuit of the display device according to claim 1, wherein the data driver 2-is provided as shown in FIGS. 1 and 2. 1 to 2-n are analog video signals da
An analog driver for sample-holding ta and applying the voltage level to the data line 8, wherein the AC center voltage correcting unit 5 AC-converts the video signal DATA to generate an analog video signal data. By changing the reference voltage of the amplifying section in accordance with the data stored in the storage means 22 in advance, the center potential in alternating current is changed.

Further, the drive circuit of the display device according to the third aspect of the present invention is the drive circuit of the display device according to claim 1, wherein the data driver 2-is provided as shown in FIGS. 1 and 5.
Reference numerals 1 to 2-n are analog drivers that sample and hold the analog video signal data and apply the voltage level to the data line 8. The AC central voltage correction unit 5 converts the video signal DATA into an AC voltage. By changing the reference voltage of the amplifying unit for generating the analog video signal data according to the integral waveform generated by the resistor and the capacitor, the center potential in the AC conversion is changed.

Further, the drive circuit of the display device according to the fourth aspect of the present invention is the drive circuit of the display device according to claim 1, wherein the data drivers 2-1 to 2- are as shown in FIG.
n is a digital driver for applying a voltage corresponding to the digital video signal data ′ to the data line 8.
By adding correction data previously stored in the storage means 22 to the digitalized signal of TA to form the digital video signal data ', the central potential in the AC conversion is changed.

[0017]

FIG. 4 is a diagram for explaining the principle of the present invention, taking a liquid crystal display device as an example. In the figure, the voltage range of the data line 8 is
4A and 4B show potential distributions of the pixel electrode voltage range, the AC central potential, and the common electrode potential with respect to the gate line direction of the liquid crystal display panel 1. FIG. 4A shows a conventional example, and FIG. In the drive circuit of the liquid crystal display device.

As shown in FIG. 4 (a), the fact that the common electrode potential has a gradient means that in other words, the range of the voltage written in the pixel electrode is a potential distribution as shown by the solid line in FIG. It means that. Therefore, in the present invention, the alternating current central potential is set to a potential distribution having a slope as shown in FIG. 4B in advance, and the voltage applied to the data line 8 has a slope in the gate line direction as shown by a broken line in FIG. Have it,
As a result, the common electrode potential is uniformly distributed in the gate line direction as shown by the solid line in the figure. That is, by changing the AC central potential, the common electrode potential is made uniform in the gate line direction, display unevenness on the liquid crystal display panel 1 is eliminated, and good liquid crystal display is possible.

In order to make the common electrode potential uniform in the gate line direction, a method of changing the alternating current central potential is as follows.
The following can be considered. First and second aspects of the present invention
In the drive circuit of the liquid crystal display device having the above feature, as shown in FIGS. 1 and 2, the data drivers 2-1 to 2-n are analog drivers, and the AC central voltage correcting unit 5 converts the video signal DATA to AC. By changing the reference voltage of the amplification unit for generating the analog video signal data according to the data stored in the storage unit 22 in advance, the center potential in AC conversion is changed.

Further, in the drive circuit of the liquid crystal display device having the first and third features of the present invention, as shown in FIGS. 1 and 5, the data drivers 2-1 to 2-n are analog drivers, and the alternating current is used. In the center voltage correction unit 5, the video signal DATA
By changing the reference voltage of the amplification unit for generating the analog video signal data by alternating current in accordance with the integral waveform generated by the resistor and the capacitor.

Further, in the drive circuit of the liquid crystal display device having the first and fourth characteristics of the present invention, as shown in FIG. 6, the data drivers 2-1 to 2-n are digital drivers,
In the AC center voltage correction unit 5, the digital video signal data ′ is added to the digitalized signal of the video signal DATA with the correction data stored in the storage unit 22 in advance.
By doing so, the central potential in alternating current is changed.

[0022]

Embodiments of the present invention will now be described with reference to the drawings. First Embodiment FIG. 1 shows a block diagram of a drive circuit of a liquid crystal display device according to a first embodiment of the present invention. In FIG. 1, the same parts as those in FIG. 7 (conventional example) are designated by the same reference numerals.

In the figure, the drive circuit of the liquid crystal display device of this embodiment includes a plurality of gate lines 9 and data lines 8.
Liquid crystal display panel 1 to be driven, and liquid crystal display panel 1
Of the gate drivers 3-1 to 3-3-for selecting an arbitrary pixel row of
m, a data driver 2-1 to 2-n for applying a voltage to be applied to the pixel electrode of the pixel row selected by the gate driver 3-1 to 3-m to the data line 8, and the RGB video signal D.
A video signal processing unit 4 that uses ATA as an analog video signal data converted into an alternating current having an amplitude suitable for driving the liquid crystal display panel 1 and the center potential of the voltage applied to the data line 8 in the alternating current are set to the center potential of the liquid crystal display panel 1. And a gate driver 3-1 to 3-m and a data driver 2-1 to 2-2.
By controlling -n, the input RGB video signal DATA is displayed.

The data drivers 2-1 to 2-n are analog drivers that sample and hold the analog video signal data and apply the voltage level to the data line 8. As shown in FIG. 3A, the video signal processing unit 4 includes an amplification unit 31 that changes the general RGB video signal DATA into an amplitude suitable for driving the liquid crystal display panel 1 based on the reference potential V _L ′. The amplified signal A _out is converted into an alternating center potential V
AC unit 3 for AC based on _M ', and alternating signal ac
2, and the generated analog video signal data is
The voltage is taken into the analog driver and applied to the data line 8. The voltage waveform of each part is shown in FIG. still,
The amplification unit 31 includes an operational amplifier Am1 and resistors R1 and R2, and the AC conversion unit 32 includes an operational amplifier Am2,
And resistors R3 and R4.

Further, FIG. 2 shows a detailed configuration diagram of the AC center voltage correcting section 5. Alternating center voltage correction unit 5 of this embodiment
Is an analog video signal d obtained by converting the video signal DATA into an alternating current.
By changing the reference voltage of the amplification unit for generating ata according to the data held in advance in the correction table (storage means) 22, the central potential in AC conversion is changed.

The AC centralized voltage correction unit 5 uses the line synchronization signal L _sync as a reset input RST, and the data synchronization signal D
A counter 21 that uses _sync as a clock input CLK, a correction table 22 that holds the correction value of the AC conversion center potential with the output of the counter 21, that is, the position of the liquid crystal display panel 1 in the gate line direction as an address, and the corrected AC conversion A D / A converter 23 that converts the value of the central potential into an analog amount is provided.

A data synchronization signal D _{sync is generated} by the counter 21.
Is counted, and the output signal of the counter 21 is input to the correction table 22 as an address. The correction table 22 holds a previously acquired correction value of the AC conversion center potential in the gate line direction of the liquid crystal display panel 1, and the AC conversion center corrected by the D / A converter 23 based on the correction value. Generate a potential V _M '.

The reference potential V _L 'supplied to the amplifying section 31 has the same structure as in FIG. 2 (that is, the correction table 22L for correcting the reference potential and the D / A converter 23).
Comprising a L), added corrected AC central potential V _M 'and the reference potential V _L', the AC portion 32 and amplification section 31 as the V _M 'and V _L' in the circuit of each shown in FIG. 3 (a) As a result, it becomes possible to change the central voltage of alternating current. Second Embodiment FIG. 5 shows a circuit configuration diagram and a voltage waveform diagram of each portion of the AC center voltage correction unit 5 in the drive circuit of the liquid crystal display device according to the second embodiment of the present invention. The overall configuration of the drive circuit of the liquid crystal display device of this embodiment and the configuration of the video signal processing unit 4 are as follows.
Same as the embodiment, shown in FIGS. 1 and 3, respectively.

The alternating-current central voltage correcting unit 5 of this embodiment converts the video signal DATA into an alternating current to convert the analog video signal data.
By changing the reference voltage of the amplifying unit for generating the signal in accordance with the integral waveform generated by the resistor and the capacitor, the central potential in alternating current is changed.

In FIG. 5, the AC conversion center voltage correction unit 5
Includes buffer amplifiers Bu1, Bu2, and Bu3, resistors R5, R6, R7, and R8, a capacitor C1, and a switch SW1.

When the CR circuit is used as described above, the power supply voltage V _DD is divided by the resistors R5, R6 and R7 to obtain the voltage V _A (potential of the contact A) and the voltage V _B (potential of the contact B). )
And switch SW using the line synchronization signal L _sync
1 is controlled by switching.

First, the switch SW1 is connected to the contact A side, and the capacitor C1 is charged to the voltage V _A. Next, when the connection is switched to the contact B side, the output V _M 'approaches the potential of the voltage V _B according to the time constant determined by the capacitance value of the capacitor C1 and the resistance value of the resistor R8. A waveform diagram showing the state of the voltage change is shown in FIG.

Further, the reference potential V _L 'supplied to the amplifying section 31 also has the same configuration as that shown in FIG. 5A, and the corrected AC central potential V _M ' and the reference potential V _L '
By adding V _M 'and V _L ' in the circuit of FIG. 3A to the AC conversion unit 32 and the amplification unit 31, respectively,
It is possible to change the central voltage of alternating current. Third Embodiment FIG. 6 shows a configuration diagram of a drive circuit of a liquid crystal display device according to a third embodiment of the present invention.

In the figure, the drive circuit of the liquid crystal display device of this embodiment is provided with a plurality of gate lines 19 and data lines 18, and the liquid crystal display panel 11 to be driven and any pixel row of the liquid crystal display panel 11. Gate driver 13 to select
A data driver 12 for applying a voltage to be applied to the pixel electrode of the pixel row selected by the gate driver 13 to the data line 18, and a video signal processing unit 14 for generating the RGB video signal DATA into a digital video signal data ″ (see FIG. (Not shown) and the digital video signal data ″ to which the correction data previously stored in the correction table (storage means) 22 is added to form the digital video signal data ′, thereby changing the center potential in the AC conversion. The center voltage correction unit 5 and the gradation voltage generation unit 41 that generates the gradation voltage
And the gate driver 13 and the data driver 12 to control the input RGB video signal DATA.
Is displayed.

The data driver 12 is a digital driver for applying a voltage corresponding to the digital video signal data 'to the data line 8. The AC center voltage correction unit 5 is similar to the AC center voltage correction unit 5 of the first embodiment (see FIG. 2) in that the line synchronization signal Lsy is used.
A counter 21 that uses nc as a reset input RST and a data synchronization signal Dsync as a clock input CLK, and a counter 2
A correction table 22 for holding the correction value of the alternating central potential in the gate line direction of the liquid crystal display panel 11 with the output of 1 as an address.

The counter 21 outputs the data synchronization signal Dsync.
Is counted, and the output signal of the counter 21 is input to the correction table 22 as an address. In the correction table 22, a previously acquired correction value of the alternating current central potential in the gate line direction of the liquid crystal display panel 11 is held, the correction data is used as the lower bit, and the digital video signal from the video signal processing unit 14 is stored. The generated digital video signal data ′ is used as the data driver 12 with “data” as the upper bit.
The central electric potential in alternating current is changed by supplying the electric potential to

The data driver 12 includes the shift register 4
2, a data latch 43, and an analog switch 44. The analog switch 44 takes into account the correction data (lower bits) in the digital video signal data ′, and the gradation based on the digital video signal data ″ (upper bits). A voltage is selected and applied to the data line 18.

Further, although the liquid crystal display device has been described in the present embodiment, the present invention is not limited to this and can be used in a matrix type display device such as a plasma display and the same effect can be obtained. It is a thing.

[0039]

As described above, according to the present invention,
Since the central potential in alternating current has a gradient potential distribution and the voltage applied to the data line has a gradient in the gate line direction, the common electrode potential should be a uniform distribution in the gate line direction. Therefore, it is possible to provide a drive circuit of a display device capable of eliminating uneven display on the display panel and performing good display.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a drive circuit of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a detailed configuration diagram of an AC center voltage correcting unit in the first embodiment.

3A is a circuit configuration diagram of a video signal processing unit, FIG. 3B is a voltage waveform diagram of each unit, FIG. 3B-A is an RGB video signal, and FIG. (B) is an output signal of the amplifier, and FIG. 3 (b-c) is an analog video signal.

4A and 4B are explanatory views of the principle of the present invention, in which FIG. 4A is a conventional example and FIG. 4B is a voltage range of a data line and a voltage of a pixel electrode in a drive circuit of a liquid crystal display device of the present invention. Is a potential distribution in the direction of the gate line of the liquid crystal display panel of the range, the AC central potential, and the common electrode potential.

FIG. 5A is a circuit configuration diagram of an AC center voltage correction unit in a drive circuit of a liquid crystal display device according to a second embodiment of the present invention, and FIG. 5B is a voltage waveform diagram of each unit.

FIG. 6 is a configuration diagram of a drive circuit of a liquid crystal display device according to a third embodiment of the present invention.

FIG. 7 is a configuration diagram of a drive circuit of a conventional liquid crystal display device.

[Explanation of symbols]

1, 11 ... Liquid crystal display panel 2-1 to 2-n, 12 ... Data driver 3-1 to 3-m, 13 ... Gate driver 4, 14 ... Video signal processing unit 5, 15 ... Alternating center voltage correction unit 8 , 18 ... Data line 9, 19 ... Gate line 21 ... Counter 22, 22L ... Correction table (storage means) 23, 23L ... D / A converter 31 ... Amplifying section 32 ... Alternating section 41 ... Gradation voltage generating section 42 ... Shift register 43 ... Data latch 44 ... Analog switch DATA ... RGB video signal F _sync ... Frame sync signal L _sync ... Line sync signal D _sync ... Data sync signal data ... Analog video signals _VL , _VL '... Reference potential A _out ... the output signal V _M of the amplification unit, V _M '... AC central potential ac ... AC signal Am1, Am2 ... op R1 to R8 ... resistor RST ... reset input CLK Clock input Bu1～Bu3 ... buffer amplifier C1 ... capacitor SW1 ... switch A, B ... contact V _DD ... power supply voltage data ", data '... digital video signal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuhiko Kishida 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (4)

[Claims] 1. A display panel (1) having a plurality of gate lines (9) and data lines (8) and a gate driver (3-) for selecting an arbitrary pixel row of the display panel (1).
1-3-m) and the gate driver (3-1-
data driver (2-1 to 2-) that applies a voltage to be applied to the pixel of the pixel row selected by m) to the data line (8).
n) and a matrix type display for controlling the gate drivers (3-1 to 3-m) and the data drivers (2-1 to 2-n) to display the input video signal (DATA). In the drive circuit of the device, there is provided an AC center voltage correcting section (5) for changing the center potential of the voltage applied to the data line (8) in the AC direction in the pixel row direction of the display panel (1). A drive circuit of a display device characterized by the above. 2. The data driver (2-1 to 2-n)
Is an analog driver for sampling and holding an analog video signal (data) and applying it to a voltage of a level corresponding to the analog video signal (data) and the data line (8). (5) is the video signal (D
The storage unit (22) stores the reference voltage of the amplifier for converting the ATA) into an alternating current to generate an analog video signal (data).
The drive circuit of the display device according to claim 1, wherein the center potential in the alternating current is changed by changing the correction potential according to the correction data held in advance. 3. The data driver (2-1 to 2-n)
Is an analog driver for sampling and holding an analog video signal (data) and applying it to a voltage of a level corresponding to the analog video signal (data) and the data line (8). (5) is the video signal (D
ATA) is converted into an alternating current to generate an analog video signal (data), and a reference voltage of an amplification unit is changed according to an integral waveform generated by a resistor and a capacitor, thereby changing a center potential in the alternating current. The drive circuit for the display device according to claim 1. 4. The data driver (2-1 to 2-n)
Is a digital driver for applying a voltage corresponding to a digital video signal (data ') to the data line (8), and the AC centralized voltage correcting unit (5) is for the video signal (D).
ATA) digitized signal, storage means (22)
2. The drive circuit for a display device according to claim 1, wherein the center potential in the alternating current is changed by adding correction data stored in advance to the digital video signal (data ').