JP2000310977A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving power supply device of a liquid crystal display device using a dot inversion driving method that prevents the occurrence of flicker and improves uniformness of the display. SOLUTION: A driving power supply device 18 supplies driving voltages to a liquid crystal panel 15, signal lines, scanning line driving circuits 16 and 17 and a γ compensation circuit 19. The device 18 generates and outputs a gate on voltage Vgon and a gate off voltage Vgoff of TFTs, a common voltage Vcom1 for common wiring 10, a counter voltage Vcom2 for counter electrodes 14 which are made by adding or subtracting a flicker control voltage Vf, that minimizes flicker, to or from an ideal reference voltage Vref to make variable, and a signal line driving power supply voltage Vso which makes the difference between one half of a signal line driving power supply voltage Vso to the circuit 16 and the voltage Vref to be not larger than 0.2 volt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device useful as a display of an information device such as a video device or a computer, and more particularly to a liquid crystal display device using a TFT as a switching element in a pixel.

[0002]

2. Description of the Related Art As shown in FIG. 25, a conventional liquid crystal display device has a pixel 103 and a counter electrode 104 provided at each intersection where a plurality of scanning lines 101 and signal lines 102 are arranged in a matrix. The liquid crystal panel 105 and the signal line 10
2, a signal line driving circuit 106 for applying a signal line driving voltage to
A scanning line driving circuit 107 for applying a signal line driving voltage to the scanning line 101, a γ correction circuit 112 for outputting a γ (gamma) correction voltage, a liquid crystal panel 105, a signal line driving circuit 106, a scanning line driving circuit 107, and γ correction A driving power supply device 111 for supplying a driving voltage to the circuit 112.

The signal line driving circuit 106 and the scanning line driving circuit 1
07 is often composed of a plurality of drive LSIs. The signal line driving circuit 106 has a logic power supply voltage Vdd
, A γ correction voltage, an image signal and a control signal Data, and an input terminal for a signal line driving power supply voltage Vadd. The scanning line driving circuit 107 is provided with input terminals for the logic power supply voltage Vdd, the image signal and the control signal Data, the scanning line driving power supply voltage Vgon, and Vgoff. The scanning line driving circuit 107 drives the scanning lines 107 by a scanning line driving voltage of Vgon level, and the signal line driving circuit 106 synchronizes with the scanning line driving voltage by a signal line driving voltage corresponding to an image signal. Drive. Vgon is a thin film transistor (hereinafter abbreviated as TFT) arranged in the pixel 103 of the liquid crystal panel 105.
Represents the gate voltage at which the switch is turned on.

If one horizontal scanning period is 1H, a scanning line driving voltage of Vgon level is output to the scanning line 101 within 1H, and all the signal lines 10 of the liquid crystal panel 105 are synchronized with this operation.
2 to output the signal line drive voltage. This operation is performed for each scanning line 1
01 is sequentially repeated to display an image on the liquid crystal panel 105. Thus, the liquid crystal display device shown in FIG. 25 displays an image by line-sequential driving.

The signal line driving circuit 106 and the scanning line driving circuit 1
A driving power supply device 111 for outputting a driving power supply voltage of a driving circuit is provided in the liquid crystal display device in order to output a driving voltage of a voltage level determined at 07 to the signal line 101 and the scanning line 102. The drive power supply device 111 outputs DC voltages Vgon, Vgoff, and Vadd as shown in FIG. 25, and supplies them to the signal line drive circuit 106 and the scan line drive circuit 107. Vgoff is a gate voltage for turning off the TFT. The signal line driving circuit 106 generates a signal line driving voltage corresponding to the image signal by using Vadd and the γ correction voltage, and drives the signal line 102. Each output circuit of the signal line driving circuit 106 has a digital / analog (hereinafter abbreviated as D / A).
A converter circuit is built in, and converts an image signal into a signal line drive voltage using the γ correction voltage as a reference voltage. The image signal of the signal line driving circuit incorporating such a D / A converter is a digital signal. A method of converting an image signal of an analog signal into a signal line driving voltage by a sample-and-hold circuit (S / H) built in the signal line driving circuit is also used, but hereinafter, a liquid crystal display for OA is used. It is assumed that a signal line driving circuit with a built-in D / A converter, which is widely used in the apparatus, is used, and the image signal is digital. The S / H method described above is a relatively small TF
T-type LCD panel (screen diagonal size is 7 inches or less)
Mainly used for television monitors, portable T
V, often used for monitors of navigation systems. The system with a built-in D / A converter is often used for a notebook personal computer or a monitor that handles image signals requiring high definition and high image quality.

[0006] The γ correction circuit 112 outputs a γ correction voltage 113. The γ correction voltage 113 is for improving the gradation display characteristics of the liquid crystal display device. The plurality of γ correction voltages 113 are used as a reference voltage of the D / A converter built in the signal line driving circuit 106 as described above. The drive power supply device 111 includes a switching (hereinafter abbreviated as “SW”) power supply circuit 116 and a counter voltage output circuit 117. The SW power supply circuit 116 receives the input voltage Vin of the liquid crystal display device and outputs Vgon, Vgoff, and Vadd. This input voltage Vin is used as a logic power supply voltage Vdd for the signal line and scanning line driving circuits 106 and 107. In many cases, the logic power supply voltage Vdd is generated by the SW power supply circuit 116.

The counter voltage generating circuit 117 generates a counter voltage Vco
m is generated to drive the counter electrode 104 of the liquid crystal panel 105, and the counter voltage Vcom determines an operating point in driving the liquid crystal panel. The control circuit 114 is based on an image signal and a clock signal input to the liquid crystal display device and control signals for a horizontal scanning period, a vertical scanning period, and the like (in FIG. 25, it is described as Signal in. ), An image signal and a control signal 115 suitable for the signal line driving circuit 106 or the scanning line driving circuit 107 are generated.

An equivalent circuit of each pixel 103 of the liquid crystal panel 105 is represented as shown in FIG. A TFT is a thin film transistor, and G, S, and D represent a gate, a source, and a drain, respectively. The drain is connected to the pixel electrode.
Clc is a storage capacitor formed at the drain, and one terminal is connected to the counter electrode 104. LC is a liquid crystal cell, and T
Liquid crystal is sealed between the pixel electrode of the FT and the counter electrode 104. The gate is connected to the scanning line 101, and the source is connected to the signal line 102.

Here, an example of the driving voltage waveform of the liquid crystal display device will be described for the case of displaying an image in which the entire screen is uniform such as white and black. As shown in FIG. 28, the waveform 121 of the signal line driving voltage is a pulse waveform having the voltage levels Vsu and Vsd of the signal line driving voltage. The waveform 122 of the counter voltage Vcom is a pulse waveform having voltage levels of V1 and V2. The V center represents the midpoint between V1 and V2. The waveform 122 of the counter voltage Vcom shows the case of the 1H counter voltage inversion drive system in which the polarity is inverted every 1H. Since Vcom determines the operating point of the liquid crystal panel 105, the voltage applied to the liquid crystal cell LC is the difference between the signal line drive voltage and Vcom (the symbol V in FIG.
su-V2 or V1-Vsd), and a voltage whose polarity is inverted is applied to the liquid crystal cell LC every vertical scanning period (1V) (also referred to as AC driving). The voltage level applied to the liquid crystal cell LC is theoretically Vsu-V2 = V1-Vsd. However, in practice, a voltage (also referred to as a penetration voltage) generated when a gate-on voltage is applied to a scanning line is capacitively coupled. As a result, an unbalanced voltage δV is applied to the liquid crystal cell LC (δV shown in the waveform 122 of the counter voltage Vcom). The unbalanced voltage δV has an adverse effect such as deterioration of the life of the liquid crystal cell and generation of flicker on the display screen, so that Vcom is adjusted to minimize δV. In FIG. 25, the adjustment is made by the semi-fixed resistor VR of the counter voltage output circuit. VR is often referred to as flicker adjustment VR.

As an example of the driving voltage waveform of the scanning line driving circuit 107, the driving voltage waveform 12 of the (n-1) th scanning line is used.
FIG. 28 shows the third, n-th scanning voltage waveform 124, and (n + 1) -th scanning line driving voltage waveform 125. Thus, the scanning lines 101 are sequentially driven. The voltage levels of the scanning line driving voltage are Vgon and Vgoff described above. FIG.
8 shows a 1H opposing voltage inversion driving method, but in addition to this, an opposing voltage inversion driving method for one vertical scanning period (1 V), a driving method for keeping the opposing voltage constant, and the like have been put to practical use.

[0011]

However, the conventional driving power supply device 111 for a liquid crystal display device has a high output voltage due to the function of adjusting the level of the counter voltage Vcom, which is a pulse, to control flicker, and a high output voltage. Due to the complexity of the structure at cost, quality problems often occur.

Further, in the conventional liquid crystal display device, the driving voltages applied to the liquid crystal cells LC arranged on an arbitrary scanning line 101 (in the direction of the scanning line 101) have the same polarity (the polarity is based on the opposite voltage). ). LCD panel 1
FIG. 27 shows the polarity of the drive voltage applied to the liquid crystal cell LC of the pixel 103 adjacent to the pixel 05. The (n-1, n, n + 1) th scanning line 101 is defined as Xn-1, Xn, Xn + 1, and m
−1, m, and m + 1th signal line 102 are connected to Ym−1, Ym
m, Ym + 1, the signal line 102 and the scanning line 101
The polarity of the drive voltage of each of the liquid crystal cells LC at the position where the intersections are indicated by “+” or “−”. The f-frame represents the f-th screen, and the f + 1-frame represents the f + 1-th screen. In the opposite voltage inversion driving as shown in FIG. 27, since the polarities of the liquid crystal cells LC on each scanning line are the same (the direction in which the scanning line 101 is wired), the scanning line wiring direction by the above-described unbalanced voltage δV is used. Flicker is noticeable. In particular, in a large-screen liquid crystal display device requiring high image quality, the occurrence of flicker is a fatal problem. If the unbalanced voltage δV is uniform in one screen, the counter voltage can be adjusted to minimize the flicker level at the center of the screen, but there is variation in the plane,
It is difficult to adjust the entire screen to a uniform minimum flicker level, and this flicker is visually recognized by human eyes.

Therefore, in place of the conventional 1H opposing voltage inversion driving method, as shown in FIG. 3, a dot inversion driving method for inverting the polarity of the driving voltage of the adjacent pixels of the liquid crystal panel to each other is used. Although it is conceivable that flicker due to the voltage δV is reduced to make it less visible, it is difficult because there is no configuration for realizing the dot inversion driving method, particularly, a configuration for realizing a driving power supply device and a γ correction circuit for a liquid crystal display device. There's a problem.

An object of the present invention is to provide a liquid crystal display device which realizes a dot inversion driving method for preventing flicker and improving display uniformity.

[0015]

A liquid crystal display device according to the present invention comprises a driving power supply for supplying a driving voltage to a liquid crystal panel, a signal line, a scanning line driving circuit and a gamma correction circuit. The gate-on voltage and the gate-off voltage of the thin film transistor as the driving power supply voltage, the first common voltage as the driving power supply voltage to the common wiring, and the flicker control voltage for minimizing flicker can be added to or subtracted from the ideal reference voltage and can be varied. A difference between a second common voltage that is a drive power supply voltage to the counter electrode, a signal line drive power supply voltage that is a drive power supply voltage to the signal line drive circuit in half, and the ideal reference voltage is 0.2. The signal line driving power supply voltage which is set to be equal to or less than volt is generated and output.

According to the present invention, it is possible to obtain a liquid crystal display device which realizes a dot inversion driving method for preventing flicker and improving display uniformity.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, a thin film transistor is provided at each intersection where a plurality of signal lines and scanning lines are arranged in a matrix, and a pixel electrode connected to a drain electrode of the thin film transistor is provided. A common line having a storage capacitor between the pixel electrode and a counter electrode facing the pixel electrode; a liquid crystal panel in which liquid crystal is sealed between the pixel electrode and the counter electrode to form a pixel; and a signal for driving the signal line. A line driving circuit, a scanning line driving circuit for driving the scanning line,
A liquid crystal display device comprising: a gamma correction circuit that outputs a gamma correction voltage; and a driving power supply device that supplies a driving voltage to the liquid crystal panel and each of the circuits. A gate power-on voltage and a gate-off voltage of the thin film transistor, which are drive power supply voltages to a circuit, a first common voltage, which is a drive power supply voltage to the common wiring, and a flicker control voltage that minimizes flicker to an ideal reference voltage or A second common voltage that is a drive power supply voltage to the counter electrode that can be subtracted and changed, a signal line drive power supply voltage that is a drive power supply voltage to the signal line drive circuit halved, and the ideal reference voltage. And a liquid crystal display device configured to generate and output the signal line driving power supply voltage having a difference of 0.2 volts or less. Dot inversion driving method for improving the uniformity of indicates it is possible to obtain a liquid crystal display device that realizes. In particular, a rational configuration of a driving power supply device used in a liquid crystal display device driven by dot inversion can be realized, and high display quality can be realized even in a large-screen liquid crystal display device.

According to a second aspect of the present invention, in the liquid crystal display device, a thin film transistor is provided at each intersection where a plurality of signal lines and scanning lines are arranged in a matrix, and a pixel electrode connected to a drain electrode of the thin film transistor. A liquid crystal panel provided with a common wiring for connecting the storage capacitor and the liquid crystal layer in parallel between the liquid crystal panel and a signal line driving circuit for driving the signal line;
A liquid crystal display device comprising: a scanning line driving circuit that drives the scanning lines; a gamma correction circuit that outputs a gamma correction voltage; and a driving power supply that supplies a driving voltage to the liquid crystal panel and each of the circuits. The drive power supply device can be varied by adding or subtracting a gate-on voltage and a gate-off voltage of the thin film transistor, which are drive power supply voltages to the scanning line drive circuit, and a flicker control voltage that minimizes flicker to an ideal reference voltage. A difference between a third common voltage which is a drive power supply voltage for the common wiring, a signal line drive power supply voltage which is a drive power supply voltage for the signal line drive circuit in half, and the ideal reference voltage is 0. A liquid crystal display device configured to generate and output the signal line driving power supply voltage set to 2 volts or less, and a liquid crystal panel having no counter electrode. The configuration of the drive power supply of the dot inversion driving liquid crystal display device had concretely be realized, it is possible to realize a high quality at low cost with a small liquid crystal display device of a large screen in order to use a switching power supply.

According to a third aspect of the present invention, there is provided a liquid crystal display device according to the first aspect, wherein the first common voltage is the same as the second common voltage. The power supply device can have a simple configuration. Further, in the liquid crystal display device according to a fourth aspect of the present invention, the drive power supply device may further include a reference voltage of a gamma correction circuit obtained by dividing the voltage from the signal line drive power supply voltage by using an output circuit for generating and outputting the signal line drive power supply voltage. 3. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is configured to generate and output the signal line drive power supply voltage by feeding back to a control circuit, and to provide a highly accurate signal line drive power supply voltage and a gamma correction circuit. And the reference voltage can be output.

In a liquid crystal display device according to a fifth aspect of the present invention, the drive power supply device is generated by dividing at least one of the first to third common voltages from the signal line drive power supply voltage. The liquid crystal display device according to claim 1 or 2, wherein the first to third common voltages can be obtained from a signal line driving power supply voltage. The liquid crystal display device according to claim 6 of the present invention is configured such that an ideal reference voltage is generated and output to a gamma correction circuit or input from the gamma correction circuit. Liquid crystal display device,
A rational configuration of a drive power supply device used in a liquid crystal display device driven by dot inversion can be realized.

According to a seventh aspect of the present invention, in the liquid crystal display device, the drive power supply device includes a switching power supply circuit for generating a signal line drive power supply voltage, a gate-on voltage, and a gate-off voltage in a single module. The liquid crystal display device according to claim 1 or 2 is constituted by a power supply module. The number of components of the liquid crystal display device can be reduced, and the reliability can be improved.

In the liquid crystal display device according to the present invention, the driving power supply device may include a switching power supply circuit for generating a signal line driving power supply voltage, a gate-on voltage, and a gate-off voltage, and a second common voltage. 2. The liquid crystal display device according to claim 1, wherein the output circuit for generating and outputting is configured as a single module, and the power supply module is provided with a control terminal for changing the second common voltage from outside. The number of components of the liquid crystal display device can be reduced, and the reliability can be improved.

In the liquid crystal display device according to a ninth aspect of the present invention, the driving power supply device includes a switching power supply circuit for generating a signal line driving power supply voltage, a gate on voltage, and a gate off voltage, and a third common voltage. 3. The liquid crystal display device according to claim 2, wherein the output circuit for generating and outputting is configured in a single module, and the power supply module is provided with a control terminal for changing the third common voltage from outside. The number of components can be reduced, and the reliability can be improved.

In a liquid crystal display device according to a tenth aspect of the present invention, the power supply module includes an output circuit for generating and outputting a first common voltage. Therefore, the number of components of the liquid crystal display device can be reduced, and the reliability can be improved. The liquid crystal display device according to claim 11 of the present invention, wherein the power supply module is provided with a control terminal for controlling the output on / off by a control pulse. It is a device that can remotely control the power supply module.

According to a twelfth aspect of the present invention, in the liquid crystal display device according to the twelfth aspect, the gamma correction circuit converts the ideal reference voltage to a voltage obtained by dividing a difference between a signal line drive power supply voltage and an ideal reference voltage into a plurality of voltages. A first correction voltage composed of a plurality of added voltages and a second correction voltage composed of a plurality of voltages obtained by dividing the ideal reference voltage and the ground into a plurality of voltages are output to a signal line driving circuit. A digital-to-analog converter for converting the image signal into a signal line driving voltage, wherein the signal line driving circuit switches between the first and second correction voltages every horizontal scanning period in synchronization with a scanning line driving voltage 7. The liquid crystal display device according to claim 6, wherein the reference voltage of the digital / analog converter is used as a reference voltage, and a driving voltage whose polarity is inverted with respect to an ideal reference voltage is applied to adjacent pixels. The liquid crystal display device of the dot inversion driving can be realized by.

In a liquid crystal display device according to a thirteenth aspect of the present invention, the gamma correction circuit is connected in series from the first resistor to the n-th resistor between the signal line drive power supply voltage and the ideal reference voltage. A first voltage-dividing resistor group, and a second voltage-dividing resistor group connected in series in order from the nth resistor to the first resistor between the ideal reference voltage and ground. A voltage between adjacent resistors of the voltage-dividing resistor group is output as a first correction voltage, and a voltage between adjacent resistors of the second voltage-dividing resistor group is output as a second correction voltage. A liquid crystal display device according to claim 12,
The resistance values of the first voltage dividing resistor and the second voltage dividing resistor are independently determined, and a highly accurate γ correction voltage can be obtained with a simple configuration in dot inversion driving.

According to a fourteenth aspect of the present invention, in the liquid crystal display device, a gamma correction circuit is connected in series from the first resistor to the n-th resistor between the signal line driving power supply voltage and the ground. And a second voltage dividing resistor group connected in series from the nth resistor to the first resistor following the first voltage dividing resistor group.
And a voltage between adjacent resistors of the first voltage-dividing resistor group as a first correction voltage, and a voltage between adjacent resistors of the second voltage-dividing resistor group. Is output to the signal line drive circuit as a second correction voltage, and a voltage between the n-th resistor of the first voltage-dividing resistor group and the n-th resistor of the second voltage-dividing resistor group is output. And a digital-to-analog converter that converts an image signal into a signal line drive voltage. The first signal line drive circuit is provided for every horizontal scanning period in synchronization with a scan line drive voltage. 3. The method according to claim 1, wherein the first and second correction voltages are switched to be a reference voltage of the digital-to-analog converter, and a driving voltage whose polarity is inverted with respect to an ideal reference voltage is applied to adjacent pixels. 4. Liquid crystal display device It can be obtained from the voltage dividing resistors connected in series a correction voltage of the dot inversion driving.

Hereinafter, the liquid crystal display device of the present invention will be described based on specific embodiments. (Embodiment 1) In a liquid crystal display device according to Embodiment 1 of the present invention, as shown in FIGS. 1 and 2, a TFT is provided at each intersection where a plurality of scanning lines 11 and signal lines 12 are arranged in a matrix. A common line 10 having a storage capacitance Clc between a pixel electrode connected to the drain electrode of the TFT and a counter electrode 14 facing the pixel electrode, and a liquid crystal between the pixel electrode and the counter electrode 14. And a signal line driving circuit 1 for driving the signal lines 12
6, a scanning line driving circuit 17 for driving the scanning lines 11, a gamma correction circuit 19 for outputting a gamma correction voltage, and a driving power supply 18 for supplying a driving voltage to the liquid crystal panel 15 and each of the above circuits. A liquid crystal display device, wherein a driving power supply device 18 is provided with a gate-on voltage Vgon and a gate-off voltage Vgo of the TFT, which are driving power supply voltages to a scanning line driving circuit 17
ff, a first common voltage Vcom1, which is a drive power supply voltage for the common wiring 10, and a flicker control voltage Vf for minimizing flicker, added to or subtracted from the ideal reference voltage Vref. The difference between the counter voltage Vcom2 as the second common voltage, the voltage obtained by halving the signal line driving power supply voltage Vso as the driving power supply voltage to the signal line driving circuit 16, and the ideal reference voltage Vref is 0.2. It is configured to generate and output a signal line drive power supply voltage Vso set to be equal to or less than volts. Here, the drive power supply 18 has, for example, a Vref output circuit that generates and outputs an ideal reference voltage Vref, and is configured to output the ideal reference voltage Vref to the γ correction circuit 19.

As shown in FIG. 3, the signal line drive circuit 16 includes a control circuit 16a, a register group 16b, a D / A converter 16c, and an output circuit 16d, and includes a logic power supply voltage Vdd, an image signal, It has input terminals for a control signal Data, a γ correction voltage 20, and a signal line drive power supply voltage Vso. The D / A converters 16c and the output circuits 16d are provided by the number corresponding to the output terminals. The register group 16b sequentially transfers the data signals (image signals) to the next stage. The control circuit 16a controls the operation of the signal line driving circuit 16. The signal line drive power supply voltage Vso is output from the output circuit 16d.
And the logic power supply voltage Vdd is used as a power supply for the logic circuit. The D / A converter 16c receives the digitized image signal and uses the γ correction voltage as a reference voltage.

As shown in FIG. 4, the scanning line driving circuit 17 comprises an input circuit 17a, a shift register 17b, a control circuit 17c, and an output circuit 17d, and includes a logic power supply voltage Vdd, a gate on voltage Vgon, and a gate off. It has input terminals for a voltage Vgoff, an image signal, and a control signal Data. Gate-on voltage Vgon and gate-off voltage Vgoff
Are added to the output circuit 17d, and the output circuits 17d are provided in a number corresponding to the number of output terminals. The data signal shown in FIG. 4 is transfer data of the shift register 17b of the scanning line drive circuit 17, and sequentially outputs Vgon to the output terminal. The control circuit 17c is an output circuit 17d
Control. Note that the signal line driving circuit 16 and the scanning line driving circuit 17 are composed of a plurality of large-scale integrated circuits (LSI) having several hundreds or more output terminals, and the input voltage Vin of the liquid crystal display device.
Are used for the power supply voltages of the logic circuits of the signal line driving circuit 16 and the scanning line driving circuit 17.

The scanning line driving circuit 17 performs one horizontal scanning period (1
In (H), the scanning line driving voltage is applied to the scanning lines 12, and the signal line driving circuit 16 applies the signal line driving voltage to the signal lines 11 in synchronization with the 1H. This operation is sequentially repeated from the first scanning line 11 to the last scanning line 11, and an image is displayed on the liquid crystal panel 15. This driving is generally called line-sequential driving. One vertical scanning period (1V) is defined as a vertical scanning period (1V) until scanning from the first scanning line 11 to the last scanning line 11 is completed, and immediately before scanning the first scanning line 11 is completed.
Is displayed as one frame.

As shown in FIG. 1, the driving power supply 18
A Vg output circuit that outputs a gate-on voltage Vgon and a gate-off voltage Vgoff, a Vso output circuit that outputs a signal line drive power supply voltage Vso, and a Vre that outputs an ideal reference voltage Vref
f An output circuit, a Vcom1 output circuit that outputs a first common voltage Vcom1 applied to the common wiring 10, and a Vcom2 output circuit that outputs a common voltage Vcom2 applied to the common electrode 14. Note that the Vref output circuit, the Vcom1 output circuit, and the Vcom2 output circuit use the gate-off voltage Vgoff and the signal line drive power supply voltage Vso as power supply voltages. The drive power supply 18 receives the input voltage Vin of the liquid crystal display device, and outputs a signal line drive power supply voltage Vso and a gate-on voltage Vgo.
n, gate-off voltage Vgoff, ideal reference voltage Vref and first
, A common voltage Vcom1 and a common voltage Vcom2, and a signal line driving circuit 16, a scanning line driving circuit 17, and a γ correction circuit 1.
9. Supply the liquid crystal panel 15 as drive power.

First common voltage V applied to common line 10
com1 is for maintaining the drive voltage applied to the liquid crystal panel 15 stably. The opposing voltage Vcom2 determines the operating point of the liquid crystal panel 15. The flicker adjusting semi-fixed resistor VR is for changing the counter voltage Vcom2 so as to minimize the flicker (flicker) of the image. As described above, the liquid crystal display device shown in FIG. 1 operates with a single input voltage Vin.

The γ correction circuit 19 generates a plurality of γ correction voltages 20 based on the ideal reference voltage Vref and the signal line drive power supply voltage Vso, and outputs them to the signal line drive circuit 16. γ
The correction voltage 20 is for improving the gradation display characteristics of the liquid crystal display device. The control circuit 21 is based on an image signal and a clock signal input to the liquid crystal display device, a control signal for a horizontal scanning period, a vertical scanning period, and the like, and a data signal (in FIG. 1, denoted as Signal in). ), Signal line,
Data signals, control signals, etc. of the scanning line driving circuits 16 and 17 2
2 and the signal line driving circuit 16 and the scanning line driving circuit 1
7 and the like.

Here, regarding the principle of the dot inversion drive,
This will be briefly described with reference to FIGS. However, FIGS. 5 and 6
Is a condition for displaying the entire screen in white or black. The dot inversion driving is performed in the liquid crystal cell L of the adjacent pixel 13.
Liquid crystal panel 1 such that the driving voltages of C
5 for reducing the flicker of the image to make it easier to see. This is a driving method in which flicker is not noticeable as compared with the conventional counter voltage inversion driving.

FIG. 5 shows the polarity of the drive voltage applied to the liquid crystal cells LC of the adjacent pixels 13 of the liquid crystal panel 15.
This polarity is the polarity of the drive voltage applied to the liquid crystal cell LC with respect to the ideal reference voltage Vref. If it is larger than Vref, it is described as "+", and if it is smaller, it is described as "-". Note that the (n-1, n, n + 1) th scanning lines 11 are represented by Xn-1,
Xn, Xn + 1, and the (m-1, m, m + 1) th signal lines 12 are represented as Ym-1, Ym, Ym + 1, where n and m indicate addresses, respectively (the same applies to FIG. 6). The f-frame represents the f-th screen, and the f + 1-frame represents the f + 1-th screen.

Here, the liquid crystal cell LC in the dot inversion drive
Will be described. (Xn, Ym-1), (X
n, Ym), pixel 13 at address (Xn, Ym + 1)
4 (a) to 4 (c) show the driving voltage of the liquid crystal cell LC in FIG. Vc1 and Vc2 are the voltage levels of the drive voltage of the liquid crystal cell LC. The voltage at the midpoint between Vc1 and Vc2 is theoretically the ideal reference voltage Vref, but the unbalanced voltage is superimposed on the liquid crystal cell LC. It deviates from the theoretical value. In order to correct this shift, the flicker control voltage Vf shown in FIG.
superimposed on com2. Therefore, Vcom2 deviates from Vref by this control voltage Vf. Visually check the image pattern in which flicker is emphasized, and set V so that flicker is minimized.
The optimum flicker control voltage Vf is obtained by varying R, and adjusted optimally for each liquid crystal display device. Therefore, Vcom2 = Vref
It is expressed as ± Vf.

Here, the luminance versus drive voltage characteristics of the liquid crystal panel 15 and the γ correction will be briefly described. LCD panel 15
FIG. 7 shows the luminance vs. drive voltage characteristics of FIG. LCD panel 15
7A and 7B respectively show normally white (NW) and normally black (NB) having different characteristics depending on the configuration of the polarizing plate. In FIG. 7A, the voltage at which the NW liquid crystal panel 15 turns off is VWa, and the voltage at which it turns on is VWb. In FIG. 7B, the voltage at which the NB liquid crystal panel 15 turns off is VBa, and the voltage at which it turns on is VBb. And V
lc is an operating voltage range indicating a range in which the liquid crystal panel 15 can display an image. If the liquid crystal material is the same, Vlc is almost the same value for both NW and NB. That is, the drive voltage needs to be in the range of VWb to VWb + Vlc or VBa to Vba + Vlc.

As shown in FIG. 7, since the luminance versus driving voltage characteristic is not linear, when a driving voltage proportional to the luminance of the image signal is applied to the liquid crystal cell LC, an appropriate gradation display is not obtained. For this purpose, correction is made when a drive voltage is generated from an image signal, and an appropriate gradation display is performed. This correction is performed when the D / A converter 16c of the signal line drive circuit 16 converts an image signal, which is a digital signal, into a signal line drive voltage, which is an analog voltage. It often employs a method of changing the level of the reference voltage in accordance with the luminance of the image signal so that the luminance-to-drive voltage characteristic becomes appropriate with the reference voltage of the D / A converter 16c so that the gradation display characteristic becomes appropriate. A reference voltage created for any purpose is called a γ correction voltage.

FIG. 8 shows an example of the relationship between the γ correction voltage used for the dot inversion drive and the luminance of the image signal (in FIG. 8, referred to as input data). The input data representing the luminance of the image signal is represented by a binary number. Note that FIG. 8A shows the characteristic A and FIG. 8B shows the characteristic B. However, the dot inversion drive requires a correction voltage corresponding to the “+” polarity and the “−” polarity. It is. Further, the relationship between the input data and the output of the signal line driving circuit 16 is determined by FIG. In this way, the relationship between the image signal and the luminance of the liquid crystal panel 15 is set to an appropriate gradation display, which is called γ correction.

Here, the theoretical equations of the voltage described so far are shown in the following (Equation 1) to (Equation 3). Vcom1 = Vref ± Δ (Equation 1) Vcom2 = Vref ± Vf (Equation 2) Vc2−Vref = Vref−Vc1 (Equation 3) where (Equation 3) It is emphasized that 1) to (Equation 3) are theoretical equations and do not include errors. Vcom1 is a constant uniquely determined by the design value of the liquid crystal panel 15 as described above, but is expressed using the difference Δ to indicate the difference from Vref. | Δ | and | Vf | are in the range of 2-3 volts.

Here, the signal line drive power supply voltage Vso will be described. The signal line driving power supply voltage Vso is a power supply voltage for generating a signal line driving voltage, and takes about twice the value of the ideal reference voltage Vref in dot inversion driving. This is because the polarity of the signal line drive voltage must be determined based on the ideal reference voltage, and a symmetric drive voltage must be applied to the liquid crystal cell.

Here, the relationship between the output voltages of the driving power supply device 18 is summarized in the following (Equation 4) to (Equation 11). Vref ≒ Vso / 2 (Equation 4) Vcom1 = Vref ± Δ (Δ is fixed) (Equation 5) Vcom2 = Vref ± Vf (Vf is variable) (Equation 5) (Equation 6) | Vf | ≦ 2 volts, | Δ | ≦ 3 volts (Equation 7) | Vref−Vso / 2 | ≦ 100 millivolts (Equation 8) 5 volts ≦ Vgon ≦ 25 Bolt (Equation 9) -20 volts ≦ Vgoff ≦ 0 volts (Equation 10) 5 volts ≦ Vso ≦ 20 volts (Equation 11) Vcom1 is uniquely defined by the liquid crystal panel 15 This is a design value of the liquid crystal panel 15 at a voltage determined in a specific manner. Therefore, Vref
What is necessary is just to generate the voltage which shifted more. The sign “±” indicates that the shift occurs in either “+” or “−”. Δ is 0 if the liquid crystal panel 15 is ideal.
It is a value close to.

Vcom2 must change the flicker control voltage Vf to minimize flicker. | Vref -V
The value of so / 2 | is desirably as small as possible, but generally the level that can be visually observed may be 200 millivolts or less, more preferably 100 millivolts or less. With this configuration, it is possible to obtain a liquid crystal display device that realizes a dot inversion driving method for preventing flicker and improving display uniformity. In particular, by generating each output voltage of the driving power supply device 18 so as to satisfy the above-described (Equation 4) to (Equation 11), a rational configuration of the driving power supply device used in the liquid crystal display device of the dot inversion drive can be obtained. And a liquid crystal display device with a large screen and high display quality can be realized.

When the Vg output circuit and the Vso output circuit of the drive power supply 18 are switching regulators, the input voltage of the drive power supply 18 can be made single. In the first embodiment, the driving power supply device 18 includes:
A Vref output circuit for generating and outputting the ideal reference voltage Vref is provided to output the ideal reference voltage Vref to the γ correction circuit 19. However, the drive power supply device 18 does not have a Vref output circuit and is ideal for the γ correction circuit 19. A configuration (not shown) may be employed so as not to output the reference voltage Vref. In this case, γ obtained from a predetermined calculation formula based on the ideal reference voltage
A gamma correction circuit that outputs a correction voltage must be used. The above predetermined formula is determined by the D / A converter of the signal line driving circuit. According to such a gamma correction circuit, it is possible to output the ideal reference voltage as described later, and the drive power supply device can output the voltage such as Vcom2 from the ideal reference voltage. .
When not outputting the ideal reference voltage from the γ correction circuit,
The ideal reference voltage is a design parameter of the liquid crystal display device,
It is an indispensable value used when designing circuits such as a drive power supply device and a gamma correction circuit. Note that the ideal reference voltage is obtained from the liquid crystal panel.

(Embodiment 2) The drive power supply device according to Embodiment 2 of the present invention is the drive power supply device 1 according to Embodiment 1 described above.
8 shows an example of a specific circuit configuration of FIG. As shown in FIG. 9, the drive power supply device 18 according to the second embodiment includes a Vgon output circuit 40 that outputs a gate-on voltage Vgon,
Vgoff output circuit 41 that outputs gate-off voltage Vgoff
And a Vso output circuit 4 for outputting a signal line drive power supply voltage Vso
2 and a Vcom2 output circuit 43 for outputting a counter voltage Vcom2
And a Vref output circuit 44 for outputting an ideal reference voltage Vref.
And a Vcom1 output circuit 45 for outputting a common voltage Vcom1.

Vgon output circuit 40 and Vgoff output circuit 4
1 and the Vso output circuit 42 are switching power supplies, and the input voltage Vin is used as the power supply voltage. Note that T1, T2, and T3 are switching transformers, D1 and D2 are diodes, C1
C3 is a smoothing capacitor. The resistors R1 to R6 are used in a voltage dividing circuit for detecting an error voltage of each output circuit. The control circuits 1 to 3 are control circuits for keeping the output of each switching power supply at a constant voltage. A dedicated LSI can be used for this circuit. Operational amplifier (hereinafter abbreviated as Op) 30 to
Vso and Vgoff are used as the power source of the power supply 33. Capacitor C
4 to C6 are inserted to stabilize the output voltage.

The Vcom2 output circuit 43 outputs R9, R10, V
R, Op30, and C4, and Vref is Vf
Is added or subtracted to output Vcom2. Vcom2 is
Since the voltage follower is based on Op30, the output resistance can be reduced. Since | Vf | ≦ about 2 to 3 volts, the values of R9, R10 and VR can be easily obtained based on Vref.

The ideal reference voltage Vref is obtained by connecting Vso to R11 and R11.
In order to divide the voltage at 12 and obtain the voltage via the voltage follower of Op32, the output resistance of the Vref output circuit 44 can be regarded as 0 if the voltage is within the maximum output current of the voltage follower (the same applies to Vvom2). If R11 = R12, Vre
f fVso / 2 is obtained. ≒ indicates a case including an error and a variation of the offset voltage of Op31, etc., and theoretically V
ref = Vso / 2. The accuracy of Vref is mainly R11 and R
12 and the Op offset voltage. Assuming that the offset voltage is 0 and Vso is 10 volts, the accuracy of Vref is calculated. Here, the input resistance of the voltage follower by Op32 is very large and R1
The effect on 2 is small and ignored. Assuming that the error between R11 and R12 is 1%, when R11 = R12, 4.95V ≦
Vref ≤ 5.05 volts. Therefore, | V
ref−Vso / 2 | ≦ 50 millivolts can be realized. If a resistor having an error of 0.5% is used, it can be reduced to 25 millivolts or less. (The general Op offset voltage is 10 millivolts or less.) The above description can be applied to Vcom1 as well.

When the accuracy of Vref is deteriorated, it is visually recognized as flicker. Since this can be adjusted by varying Vcom2 by VR, it is not necessary to extremely increase the accuracy of the resistance value. In the first and second embodiments, | Vref−Vso / 2
| ≦ 200 millivolts, more preferably | Vref−
Vso / 2 | ≦ 100 millivolts. Vso to Vref
Since Vref, Vcom1 and Vcom2 are generated in conjunction with Vso and Vcom1 and Vcom2, Vref and Vcom1 and Vcom2 are also linked to fluctuations in Vso.

As described above, the driving power supply device 18 is adjusted so as to satisfy (Equation 4) to (Equation 11) of the first embodiment described above with reference to FIG.
With the circuit configuration shown in (1), the driving power supply device 18 for dot inversion driving can be specifically realized, and a small-sized, low-cost, and high-quality liquid crystal display device can be realized by using a switching power supply. Can be. The circuit configuration of the driving power supply device 18 shown in FIG. 9 is an example, and is based on (Equations 4) to (Equation 11) of the first embodiment and the circuit configuration shown in FIG. Many types of circuit configurations other than the driving power supply device 18 shown can be realized.

For example, a transformer is not used for the switching power supply, a charge pump system using a capacitor, a transformer that does not completely separate the primary and secondary sides from the transformer, or a choke coil is used instead of some or all of the transformers There are ways. Also, a method is conceivable in which the Vgon output circuit 40, the Vgoff output circuit 41, and the Vso output circuit 42 use a series regulator without using a switching power supply. In this case, the conversion efficiency becomes poor.
Further, a Vcom2 output circuit 43 and a Vref output circuit 44
And Vcom 145 may be of a switching power supply type. These selections may be made according to the outer shape and price of the display device or the use conditions.

In the second embodiment, the driving power supply 18
Is provided with the Vref output circuit 44, but the Vref output circuit 44 may not be provided. (Embodiment 3) As shown in FIG. 10, the drive power supply device according to Embodiment 3 has a function of controlling the output on / off by a control pulse to the drive power supply device 18 of Embodiment 2 described above. It was done.

More specifically, the Vgon output circuit 40, Vgoff output circuit 41 and Vso output shown in FIG.
An on / off control terminal is provided in each of the control circuits 1 to 3 of the output circuit 42 so that the Vgon output circuit 40a and Vgo
ff Each control circuit 1 of the output circuit 41a and the Vso output circuit 42a
a to 3a, and the drive power supply 18 is externally turned on / off.
Each of the control circuits 1a to 3a is turned ON / OFF so that the OFF control can be performed.
It is configured to operate based on a control signal from an OFF signal input circuit.

With this configuration, in addition to the effects of the first and second embodiments, the liquid crystal display device can be remotely controlled from outside. (Embodiment 4) As shown in FIG. 11, the drive power supply according to Embodiment 4 is obtained by dividing the drive power supply 18 of Embodiment 3 from the signal line drive power supply voltage Vso by an ideal reference voltage. Vref is fed back to the control circuit 3b of the Vso output circuit 42b to generate and output the signal line drive power supply voltage Vso.

With this configuration, a voltage obtained by dividing the signal line driving power supply voltage Vso is applied to the control circuit 3b, and the ideal reference voltage Vref is fed back to the control circuit 3b, so that the output voltage is stabilized. A highly accurate signal line drive power supply can be realized. In the fourth embodiment, Vref is fed back to the control circuit 3b having an on / off control terminal. However, the control circuit 3 having no on / off control terminal shown in FIG. The same effect is obtained even when Vref is fed back to.

(Fifth Embodiment) The drive power supply of the fifth embodiment is the same as the Vcom1 output circuit 4 of the second to fourth embodiments.
5 instead of the first common voltage Vco as shown in FIG.
Vco generated by dividing m1 from the signal line driving power supply voltage Vso
An m1 output circuit 45a is provided. As shown in FIG. 12, the Vcom1 output circuit 45a is obtained by removing Op32 from the circuit configuration of the Vcom1 output circuit 45 shown in FIGS.

This configuration is very useful when the input resistance of the common electrode is high and the effect of the output resistance of Vcom1 can be neglected. In the fifth embodiment, Op32 of the Vcom1 output circuit 45 of the second to fourth embodiments is deleted, but as shown in FIG.
a is the O of the Vref output circuit 44 of the second to fourth embodiments.
The configuration in which p31 is omitted is useful when the Vref input resistance of the γ correction circuit 19 is high and the Vref output resistance can be ignored.

Further, although not shown, the counter electrode and γ
If the input resistance of the correction circuit is high, an output circuit in which Ops 31 and 32 are omitted may be used. In the fifth embodiment, Op32 of the common voltage Vcom1 output circuit 45 of the second to fourth embodiments is used.
, The common voltage Vcom2 output circuit is replaced by the Op3 of the common voltage Vcom2 output circuit 43 of the second to fourth embodiments.
0 may be deleted.

(Embodiment 6) As shown in FIG. 14, the drive power supply device of Embodiment 6 has a signal line drive power supply voltage V
The switching power supply circuit for generating the so, the gate-on voltage Vgon, and the gate-off voltage Vgoff is constituted by a power supply module 51 incorporated in a single module.

More specifically, the Vgon output circuit, the Vgoff output circuit, and the Vso output circuit of the drive power supply device 18 are combined into a single module to form a power supply module 51. The power supply module 51 is composed of a printed circuit board such as glass epoxy or an insulator such as ceramic as a substrate, and forms a wiring pattern and an output terminal of a metal such as a copper foil to form main circuit components of Vgon, Vgoff and Vso output circuits. Is implemented.

With this configuration, a part of the driving power supply device can be modularized in the liquid crystal display device, so that the cost can be reduced, the quality can be improved, or the components can be shared between different liquid crystal display devices. In addition, the power supply module 5
15, an output circuit for generating and outputting the ideal reference voltage Vref of the gamma correction circuit 19 and the counter voltage Vcom2 is further incorporated in the power supply module 51 shown in FIG. A Vcom2 control terminal for changing the voltage Vcom2 may be provided. In this case, the Vcom2 control terminal for connecting the flicker control VR and Vref
And the output terminal of Vcom2. Although illustration is omitted, a configuration in which an ideal reference voltage Vref output circuit is not incorporated may be employed.

Although not shown, a power supply module may be formed by additionally forming a Vcom1 output circuit, a Vref output circuit, and the like on the power supply module 51 shown in FIG.
Further, as shown in FIG.
n, Vgoff, Vso, Vref, Vcom1 and Vcom2 output circuits are integrated into a single module.
May be configured. Of course, a configuration in which the ideal reference voltage Vref output circuit is not incorporated may be adopted.

Power supply module 5 shown in FIGS.
1 to 53 have on / off control terminals,
If not necessary, the configuration may be omitted. 15 and FIG.
The flicker control V is applied to the power supply modules 51 and 52 shown in FIG.
R may be incorporated. 14 to FIG.
The output circuits of the power supply modules 51 to 53 shown in FIG.
The circuit configurations shown in FIGS. 9 to 13 in Embodiments 2 to 5 described above can be used.

(Seventh Embodiment) As shown in FIG. 17, the liquid crystal display device of the seventh embodiment includes a liquid crystal panel 15a.
In the first embodiment, the counter electrode 14 of the liquid crystal panel 15 shown in FIG.
The Vcom1 output circuit of the drive power supply device 18 of the first embodiment is deleted, and a Vcom3 output circuit is provided in place of the Vcom2 output circuit, and the common wiring voltage V as a third common voltage is provided.
com3 is connected and supplied to the common wiring 10 of the liquid crystal panel 15a.

FIG. 18 shows an equivalent circuit of each pixel 13 of the liquid crystal panel 15a. Between the pixel electrode connected to the drain of the TFT and the common line 10, a storage capacitor Clc and a liquid crystal cell LC are connected in parallel. As shown in FIG. 19, the driving power supply 18a includes a Vgon output circuit 40a, a Vgoff output circuit 41a, and a Vso output circuit 42.
a, a Vref output circuit 44 and a Vcom3 output circuit 46. The Vcom3 output circuit 46 is the same as the Vcom2 output circuit 43 shown in FIG.

The drive power supply 18a has a gate-on voltage Vgo satisfying the following (Equation 12) to (Equation 17).
n, the gate-off voltage Vgoff, and the ideal reference voltage Vref
And a signal line driving power supply voltage Vso and a common wiring voltage Vcom3. Vref ≒ Vso / 2 (Equation 12) Vcom3 = Vref ± Vf (Vf is variable) (Equation 13) | Vf | ≦ 3 volts (Equation 14) | Vref−Vso / 2 | ≦ 100 millivolts (Equation 15) 5 volts ≦ Vgon ≦ 25 volts, -20 volts ≦ Vgoff ≦ 0 volts (Equation 16) 5 volts ≦ Vso ≦ 20 volts (Equation 17) The common wiring voltage Vcom3 plays the same role as the counter voltage Vcom2 in the first embodiment, and setting Vf to an optimum voltage by the flicker control VR is the same as in the above-described embodiment. Form 1
This is the same as in the case of the liquid crystal display device.

Due to such a configuration, even in the case of the liquid crystal display device in which the opposing electrode 14 of the liquid crystal panel 15 of the first embodiment is omitted, the dot inversion driving for preventing the flicker and improving the uniformity of the display. The method can be realized. In particular, by generating each output voltage of the driving power supply device 18a so as to satisfy the above (Equation 12) to (Equation 17), a rational configuration of the driving power supply device used in the liquid crystal display device of the dot inversion drive can be obtained. And a liquid crystal display device with a large screen and high display quality can be realized.

In the seventh embodiment, the drive power supply device 18a is configured by changing the circuit configuration of the drive power supply device shown in FIG. 10 in the aforementioned third embodiment as shown in FIG. 9, 11 to 13 of the above-described second, fourth, and fifth embodiments.
May be changed in the same manner as described above. Also, the power supply module shown in FIGS. 14 to 16 in the above-described sixth embodiment is different from the power supply module shown in FIGS.
If the com2 output circuit is changed to the Vcom3 output circuit, the drive power supply device 18a of the seventh embodiment can be used as a power supply module, and the same effects as in the sixth embodiment can be obtained.

In the seventh embodiment, the drive power supply 18a shown in FIG. 19 is provided with an on / off control terminal for inputting a control signal from an on / off signal input circuit. The on / off control terminal need not be provided when it is not necessary to perform remote control from the remote controller. In the above-described second to seventh embodiments, it is also possible to reduce the number of circuit components by integrating the control circuit and the operational amplifier of the driving power supply device.

(Embodiment 8) The gamma correction circuit 19 of the eighth embodiment shows an example of a specific circuit configuration of the gamma correction circuit 19 of the liquid crystal display device of the first and seventh embodiments. is there. As shown in FIG. 20, the γ correction circuit 19 includes a first voltage dividing resistor Rc0, a first voltage dividing resistor Rc0 as an nth resistor between the signal line driving power supply voltage Vso and the ideal reference voltage Vref.
A first voltage-dividing resistor group connected in series in the order of Rc1, Rc2, Rc3, and Rc4, and an n-th voltage dividing resistor between the ideal reference voltage Vref and the ground.
To the second voltage dividing resistors Rc4 and Rc4 as the first resistors.
a second voltage-dividing resistor group connected in series in the order of c3, Rc2, Rc1, and Rc0. Each voltage between adjacent resistors of the first voltage-dividing resistor group is converted to a first correction voltage Vcp1 to Vcp1. Vcp4, and outputs respective voltages between adjacent resistors of the second voltage-dividing resistor group as second correction voltages Vcm4 to Vcm1.

The γ correction circuit 19 includes a Vref output circuit 44
Is input. Op50-5
7 is used as a buffer that can be regarded as having an amplification factor of 1.
As described in the first embodiment, the γ correction circuit 19 outputs Vcp1, Vcp2, and Vcp used for the image signal at the “+” polarity.
A first correction voltage consisting of cp3 and Vcp4 and a second correction voltage consisting of Vcm4, Vcm3, Vcm2 and Vcm1 used for the image signal at the "-" polarity are output. The first correction voltage is obtained by buffering a divided voltage obtained by inserting first voltage dividing resistors Rc0, Rc1, Rc2, Rc3, and Rc4 in series between the signal line driving power supply voltage Vso and the ideal reference voltage Vref in order. The second correction voltage is obtained by inserting the second voltage-dividing resistors Rc4, Rc3, Rc2, Rc1, and Rc0 in series between the ideal reference voltage Vref and the ground in order. The voltage is output via a buffer.

Therefore, ΔR = (Rc0 + Rc1 + Rc2 + Rc3
+ Rc4), the theoretical values of the first and second correction voltages are as follows: Vcp1 = {(Rc1 + Rc2 + Rc3 + Rc4) / {R}. (Vso−Vref) + Vref (Equation 18) Vcp2 = ｛(Rc2 + Rc3 + Rc4) / ΣR ｝ · (Vso−Vref) + Vref (19) Vcp3 = cp (Rc3 + Rc4) / {R} · (Vso−Vref) + Vref (20) Vcp4 = ｛(Rc4) / ΣR ｝ · (Vso−Vref) + Vref (Equation 21) Vcm4 = Σ (Rc3 + Rc2 + Rc1 + Rc0) / ΣR｝ · Vref (Equation 22) Vcm3 = ｛(Rc2 + Rc1 + Rc0) / ΣR｝ · Vref (Equation 23) Vcm2 = {(Rc1 + Rc0) / {R} .Vref... (Equation 24) Vcm1 = {(Rc0) / {R} .Vref... Become. Naturally, the error of the voltage dividing resistor, the input resistance of Op, etc. are set to 0. Also, theoretically, (Vso-Vre
f) = Vref, Vcp1 + Vcm1-2Vref = Vcp2 + Vcm2-2Vref = Vcp3 + Vcm3-2Vref = 0 (Equation 26) Vcp4 + Vcm4-2Vref = 0 (Equation 27)

By inserting the first and second voltage-dividing resistors in this way, the first and second correction voltages can be obtained accurately and simply. For the sake of simplicity, the first and second voltage-dividing resistors have the same value.
Is characterized in that the first voltage dividing resistor and the second voltage dividing resistor can be determined independently of each other.
There is no need to use a resistor having the same value as the first voltage dividing resistor and the second voltage dividing resistor. Further, the fact that the first voltage dividing resistor and the second voltage dividing resistor can be determined independently of each other means that the design flexibility of the γ correction circuit 19 can be increased and the accuracy of the first and second voltage dividing resistors can be improved. This means that they do not affect each other, and the accuracy of the correction voltage can be increased.

An important point in the γ correction circuit 19 shown in FIG. 20 is that the output resistance of the Vref output circuit 44 is set to a value that can be ignored compared to ΔR. This is because if the output resistance is large, an error that cannot be ignored from the above theoretical value occurs. ΣR is 0.1% above 10kΩ
If it is less than 1Ω, the output resistance can be ignored.

This is an example of the γ correction circuit 19 shown in FIG. 20, and the number of correction voltages is generally not limited to four for the “+” polarity and the “−” polarity shown in FIG. The higher the resolution of the signal line driving circuit 16 and the larger the displayable gradation, the larger the number of correction voltages. This is because γ correction of the liquid crystal panel can be accurately performed. Actually, a device capable of displaying 256 gradations for R, G, and B is called full color, and the practical gradation is 2 colors.
56 is sufficient, and 64 normally used gradations are common. 1/256 ≒ for display performance of 256 gradations
The value of the output resistance was determined based on the fact that an image signal having a luminance difference of 0.4% or less cannot be identified on the screen.

As described above, the numbers of the first and second correction voltages are the same, but are not constant. Therefore, the expansion is performed when the number of the first and second correction voltages is n. .., Rcpn are connected in series between Vso and Vref in order, and Rcmn,... Rcm1,.
The voltages shown in (Equation 28) to (Equation 29) obtained by sequentially inserting Rcm0 in series may be used as the first and second correction voltages.

ΣRp = Rcp (0) + Rcp (1) +... + Rcp (n),
ΣRm = Rcm (0) + Rcm (1) +... + Rcm (n), the first correction voltage is from k = 1 to n, and Vcpk = [｛Rcp (k) + Rcp (k + 1) +. n)｝ / ΣRp] · (Vso−Vref) + Vref (28), the second correction voltage is from k = 1 to n, and Vcmk = [｛Rcm (k−1) ) +... + Rcm (1) + Rcm (0)｝ / ΣRm] · Vref (Equation 29) Rc (0) = Rcp, except in special cases
(1),..., Rc (n) = Rcp (n) = Rcm (n), and ΣR = ΣRp
= ΣRm is reasonable.

With this configuration, a dot inversion driving liquid crystal display device can be realized with a simple configuration by using the γ correction circuit 19 using Vref as a reference voltage. The resistance values of the first voltage dividing resistor and the second voltage dividing resistor are independently determined, and a highly accurate γ correction voltage can be obtained with a simple configuration in dot inversion driving. The value of the effect of the output resistance of the Vref output circuit 44 can be ignored.

In the eighth embodiment, Ops 50 to 57 are provided in the gamma correction circuit 19, but as shown in FIG.
When the correction circuit 19 is configured to directly output the divided voltage by the resistance without the Ops 50 to 57, the input resistance of the γ correction terminal of the signal line driving circuit 16 is relatively large, and the influence of the input resistance is small. Very useful in case. The gamma correction circuit 19 can be realized with a very simple circuit at low cost.

Although the drawing is omitted, if the input resistance is small among the γ input terminals of the signal line drive circuit 16 and affects the γ correction voltage, a method of inserting a buffer only at the input terminal may be used. . (Embodiment 9) As shown in FIG. 22, in the liquid crystal display device of the ninth embodiment, the drive power supply device 18b is replaced with the drive power supply device 1 of the liquid crystal display device shown in FIG.
8, the Vref output circuit 44 is deleted to provide a Vref input terminal, and the gamma correction circuit 19a is configured by providing the Vref output circuit 61 in the gamma correction circuit 19 of the first embodiment.

As shown in FIG. 23, the γ correction circuit 19a is connected in series in the order of the first to n-th resistors Rcp0 to Rcp4 between the signal line drive power supply voltage Vso and the ground. A first voltage-dividing resistor group connected to the first voltage-dividing resistor group and a second resistor as a first resistor from the n-th resistor.
And a second voltage-dividing resistor group connected in series in the order of the voltage-dividing resistors Rcm4 to Rcm0, and each of the voltages between adjacent resistors of the first voltage-dividing resistor group is converted to a first correction voltage Vcp1 to Vcp
2 and the respective voltages between adjacent resistors of the second voltage dividing resistor group are set as second correction voltages Vcm4 to Vcm0 in FIG.
2 to the signal line drive circuit 16 shown in FIG.
The voltage between the voltage dividing resistor Rcp4 and the second voltage dividing resistor Rcm4 is set as an ideal reference voltage Vref by the Vref output circuit 61 in FIG.
This is configured to output to the drive power supply device 18b shown in FIG. The Vref output circuit 61 is provided with Op60.

With this configuration, determining the first and second voltage dividing resistors is the same as that of the eighth embodiment described above with reference to FIGS.
Although it is more complicated than the case shown in FIG. 21, the ideal reference voltage Vref can be obtained by the first and second voltage dividing resistors. In the ninth embodiment, the drive power supply device 18 and the gamma correction circuit 19 of the liquid crystal display device shown in FIG. 1 in the first embodiment are changed.
The drive power supply device 18a and the γ correction circuit 19a of the liquid crystal display device shown in FIG. 7 may be modified in the same manner as described above to form the drive power supply device 18c and the γ correction circuit 19a as shown in FIG.

The γ correction circuit 19a may have a configuration in which a voltage divided by a resistor is interposed through a buffer as in the γ correction circuit shown in FIG. 20 in the eighth embodiment. In this case, the Vref output circuits 44 and 44a shown in FIGS. 9 to 13 and FIG. 19 in the second to fifth and seventh embodiments can be omitted, and the same effect can be obtained. In the ninth embodiment, the ideal reference voltage Vref is input to the drive power supply 18b.
If it is not necessary to input Vref, the Vref output circuit 61 may be deleted.

[0085]

As described above, according to the liquid crystal display device of the first aspect of the present invention, a thin film transistor is provided at each intersection where a plurality of signal lines and scanning lines are arranged in a matrix, and the drain of the thin film transistor is provided. A common line having a storage capacitor between the pixel electrode connected to the electrode and a counter electrode facing the pixel electrode, a liquid crystal panel in which liquid crystal is sealed between the pixel electrode and the counter electrode to form a pixel, A driving power supply device that supplies a driving voltage to a signal line driving circuit that drives a signal line, a scanning line driving circuit that drives the scanning line, and a gamma correction circuit that outputs a gamma correction voltage, to the scanning line driving circuit. Flickers between the gate-on voltage and the gate-off voltage of the thin film transistor, which are the drive power supply voltages of the thin film transistor, the first common voltage, which is the drive power supply voltage to the common wiring, and the ideal reference voltage A second common voltage that is a drive power supply voltage to the counter electrode that can be changed by adding or subtracting a flicker control voltage to be reduced, and a signal line drive power supply voltage that is a drive power supply voltage to the signal line drive circuit are halved. And generating and outputting the signal line driving power supply voltage in which the difference between the adjusted voltage and the ideal reference voltage is 0.2 V or less, thereby preventing flicker and uniformity of display. , A liquid crystal display device that realizes a dot inversion driving method that improves the display quality can be obtained. In particular, a rational configuration of a driving power supply device used in a liquid crystal display device driven by dot inversion can be realized, and high display quality can be realized even in a large-screen liquid crystal display device.

According to the liquid crystal display device of the second aspect of the present invention, the drive power supply of the liquid crystal display device of the dot inversion drive using the liquid crystal panel having no counter electrode is connected to the scanning line drive circuit. A third drive power supply voltage to a common line that can be changed by adding or subtracting a gate on voltage and a gate off voltage of the thin film transistor that is a drive power supply voltage and a flicker control voltage that minimizes flicker to an ideal reference voltage.
And a difference between the ideal reference voltage and a voltage obtained by halving the signal line driving power supply voltage, which is a driving power supply voltage to the signal line driving circuit, is 0.2 V or less. By generating and outputting a voltage, it is possible to specifically realize a configuration of a drive power supply of a liquid crystal display device of a dot inversion drive using a liquid crystal panel without a counter electrode, and to use a switching power supply. Even in a large-screen liquid crystal display device, high quality can be realized at a low cost at a small size.

According to the liquid crystal display device of the third aspect of the present invention, the drive power supply device of the first aspect has the first common voltage and the second common voltage set to the same voltage. Thereby, the driving power supply device can be simplified in configuration. Further, according to the liquid crystal display device of the present invention, the drive power supply device of the above-described claim 1 or 2 is divided from the signal line drive power supply voltage by the reference voltage of the gamma correction circuit. Is fed back to a control circuit of an output circuit that generates and outputs the signal line drive power supply voltage, and the signal line drive power supply voltage is generated and output. And output voltage.

According to the liquid crystal display device of the fifth aspect of the present invention, the drive power supply device of the first or second aspect is provided with at least one of the first to third common voltages. Since the first to third common voltages are generated by dividing one from the signal line drive power supply voltage, the first to third common voltages can be obtained from the signal line drive power supply voltage. According to the liquid crystal display device of the present invention, the driving power supply device of the above-described claim 1 or 2 generates an ideal reference voltage and outputs the ideal reference voltage to the gamma correction circuit. 2. The apparatus according to claim 1, wherein the input is made from the gamma correction circuit.
Alternatively, the liquid crystal display device according to the second aspect can realize a rational configuration of a drive power supply device used in a liquid crystal display device driven by dot inversion.

Further, according to the liquid crystal display device of the present invention, the driving power supply device of the above-mentioned claim 1 or 2 is replaced with a signal line driving power supply voltage, a gate-on voltage and a gate-off voltage. Since the switching power supply circuit for generating the power supply is constituted by a power supply module incorporated in a single module, the number of components of the liquid crystal display device can be reduced and the reliability can be improved.

Further, according to the liquid crystal display device of the present invention, the driving power supply device of the above-mentioned claim 1 is replaced with a switching device for generating a signal line driving power supply voltage, a gate-on voltage and a gate-off voltage. A liquid crystal display comprising: a power supply circuit and an output circuit for generating and outputting a second common voltage incorporated in a single module; and a power supply module provided with a control terminal for changing the second common voltage from outside. The number of components of the display device can be reduced, and the reliability can be improved.

According to a ninth aspect of the present invention, there is provided a liquid crystal display device according to the first or second aspect, wherein the driving power supply device according to the first or second aspect includes a signal line driving power supply voltage, a gate-on voltage, a gate-off voltage, , And an output circuit for generating and outputting a third common voltage are incorporated in a single module, and the power supply module is provided with a control terminal for externally changing the third common voltage. Thus, the number of components can be reduced, and the reliability can be improved.

According to the liquid crystal display device of the present invention, an output circuit for generating and outputting the first common voltage is incorporated in the power supply module of the present invention. In addition, the number of components of the liquid crystal display device can be reduced, and the reliability can be improved. According to the liquid crystal display device of the present invention, the power supply module according to any one of claims 7 to 10 is provided with a control terminal for controlling the output on / off by a control pulse. Thus, the power supply module can be remotely controlled.

According to a twelfth aspect of the present invention, the gamma correction circuit according to the first or second aspect of the present invention includes a gamma correction circuit for calculating a difference between a signal line driving power supply voltage and an ideal reference voltage. A first correction voltage composed of a plurality of voltages obtained by adding the ideal reference voltage to a voltage obtained by dividing the
Outputting a second correction voltage composed of a plurality of voltages obtained by dividing the ideal reference voltage and the ground to a plurality of signals to a signal line driving circuit; A digital-to-analog converter that converts the voltage into a voltage, switches between the first and second correction voltages every horizontal scanning period in synchronization with a scanning line drive voltage, and sets the voltage as a reference voltage for the digital-to-analog converter. In addition, by providing a drive voltage whose polarity is inverted with respect to the ideal reference voltage, a liquid crystal display device of dot inversion drive can be realized with a simple configuration.

According to a thirteenth aspect of the present invention, the gamma correction circuit according to the twelfth aspect is configured such that the gamma correction circuit is provided between the signal line driving power supply voltage and the ideal reference voltage from the first resistor. a first voltage dividing resistor group connected in series in the order of n resistors, and a second voltage dividing resistor group connected in series in the order of the nth resistor to the first resistor between the ideal reference voltage and the ground. Wherein each voltage between adjacent resistors of the first voltage dividing resistor group is a first correction voltage, and each voltage between adjacent resistors of the second voltage dividing resistor group is a second correction voltage. , The first and second voltage-dividing resistors can have independent resistance values determined, and a highly accurate γ-correction voltage can be obtained with a simple configuration in dot inversion driving. Obtainable.

According to a fourteenth aspect of the present invention, the gamma correction circuit according to the first or second aspect is provided by connecting the gamma correction circuit between the signal line drive power supply voltage and the ground. A first voltage-dividing resistor group connected in series in the order from the first resistor to the n-th resistor;
And a second voltage-dividing resistor group connected in series from the first resistor to the first resistor, wherein each voltage between adjacent resistors of the first voltage-dividing resistor group is a first correction voltage, Each voltage between adjacent resistors of the second voltage-dividing resistor group is output to the signal line drive circuit as a second correction voltage, and the n-th resistor of the first voltage-dividing resistor group and the second A voltage between the nth resistor of the voltage-dividing resistor group and an ideal reference voltage, wherein the signal line drive circuit has a digital-to-analog converter for converting an image signal into a signal line drive voltage, The first and second correction voltages are switched every horizontal scanning period in synchronization with a line driving voltage to be a reference voltage of the digital-to-analog converter, and a driving voltage whose polarity is inverted with respect to the reference voltage is applied to adjacent pixels. By configuring to give Correction voltage of Tsu preparative reverse driving can be obtained from the voltage dividing resistors connected in series.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a liquid crystal display device according to Embodiment 1 of the present invention.

FIG. 2 is a circuit diagram showing an equivalent circuit of a pixel of the liquid crystal panel of Embodiment 1.

FIG. 3 is a block diagram showing a configuration of a signal line driver circuit according to the first embodiment;

FIG. 4 is a block diagram showing a configuration of a scanning line driving circuit according to the first embodiment;

FIG. 5 is an explanatory diagram showing drive voltage polarities of respective pixels in the dot inversion drive according to the first embodiment;

FIG. 6 is a waveform chart showing a drive voltage waveform applied to a pixel of the liquid crystal panel according to the first embodiment.

FIG. 7 is a characteristic diagram showing luminance versus drive voltage characteristics of the liquid crystal panel of Embodiment 1.

FIG. 8 is a correspondence diagram showing a relationship between a γ correction voltage and input data according to the first embodiment;

FIG. 9 is a circuit diagram showing a configuration of a drive power supply device according to Embodiment 2 of the present invention.

FIG. 10 is a circuit diagram showing a configuration of a driving power supply device according to Embodiment 3 of the present invention.

FIG. 11 is a circuit diagram showing a configuration of a drive power supply device according to Embodiment 4 of the present invention.

FIG. 12 is a circuit diagram showing a configuration of a drive power supply device according to a fifth embodiment of the present invention.

FIG. 13 is a circuit diagram showing a configuration of a drive power supply device different from that of the fifth embodiment of the present invention;

FIG. 14 is a schematic external view showing a power supply module according to a sixth embodiment of the present invention.

FIG. 15 is a schematic external view showing a power supply module different from the sixth embodiment of the present invention.

FIG. 16 is a schematic external view showing a power supply module different from Embodiment 6 of the present invention.

FIG. 17 is a block diagram illustrating a configuration of a liquid crystal display device according to a seventh embodiment of the present invention.

FIG. 18 is a circuit diagram showing an equivalent circuit of a pixel of the liquid crystal panel of Embodiment 7;

FIG. 19 is a circuit diagram showing a configuration of a drive power supply device according to Embodiment 7.

FIG. 20 is a circuit diagram showing a configuration of a gamma correction circuit according to an eighth embodiment of the present invention.

FIG. 21 is a circuit diagram showing a configuration of a γ correction circuit different from the eighth embodiment of the present invention.

FIG. 22 is a block diagram illustrating a configuration of a liquid crystal display device according to a ninth embodiment of the present invention.

FIG. 23 is a circuit diagram showing a configuration of a gamma correction circuit according to the ninth embodiment.

FIG. 24 is a block diagram showing a structure of a liquid crystal display device different from that of Embodiment 9;

FIG. 25 is a block diagram showing a configuration of a conventional liquid crystal display device.

FIG. 26 is a circuit diagram showing an equivalent circuit of a pixel of a conventional liquid crystal panel.

FIG. 27 is an explanatory diagram showing a driving voltage polarity of each pixel of the related art.

FIG. 28 is a waveform diagram showing a conventional signal line driving voltage and scanning line driving voltage waveform.

[Explanation of symbols]

 1, 1a control circuit 2, 2a control circuit 3, 3a, 3b control circuit 10 common wiring 11 signal line 12 scanning line 13 pixel 14 counter electrode 15, 15b liquid crystal panel 16 signal line driving circuit 16a control circuit 16b register group 16c D / A converter 16d Output circuit 17 Scan line drive circuit 17a Input circuit 17b Shift register 17c Control circuit 17d Output circuit 18, 18a, 18b, 18c Drive power supply 19, 19a γ correction circuit 20 γ correction voltage 21 control circuit 22 image and control signal 30-32 Operational amplifiers 40, 40a Vgon output circuit 41, 41a Vgoff output circuit 42, 42a, 42b Vso output circuit 43 Vcom2 output circuit 44, 44a, 61 Vref output circuit 45, 45a Vcom1 output circuit 46 Vcom3 output circuit 50-57 , 60 operational amplifier

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hideki Yamauchi 1006 Kazuma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 2H093 NC03 NC09 NC11 NC21 NC24 NC34 ND10 ND54 ND55 ND60 5C006 AC25 AC26 AF46 AF54 BB16 BC11 BF42 BF43 FA23 FA41 FA51 GA02 GA04 5C080 AA10 BB05 DD06 EE29 FF07 FF11 JJ02 JJ03 JJ04 JJ05

Claims (14)

[Claims] A thin film transistor is provided at each intersection where a plurality of signal lines and scanning lines are arranged in a matrix, and a common wiring having a storage capacitance between a pixel electrode connected to a drain electrode of the thin film transistor and the pixel electrode. A liquid crystal panel in which liquid crystal is sealed between the pixel electrode and the counter electrode to form a pixel, a signal line driving circuit for driving the signal line, and a scanning line driving for driving the scanning line A gamma correction circuit that outputs a gamma correction voltage;
A liquid crystal display device comprising: a drive power supply device that supplies a drive voltage to the liquid crystal panel and each of the circuits; wherein the drive power supply device is a drive power supply voltage to the scan line drive circuit; Driving to the opposing electrode which can be changed by adding or subtracting a gate on voltage, a gate off voltage, a first common voltage which is a drive power supply voltage for the common wiring, and a flicker control voltage for minimizing flicker to an ideal reference voltage. The difference between the second common voltage, which is a power supply voltage, the voltage obtained by halving the signal line drive power supply voltage, which is the drive power supply voltage for the signal line drive circuit, and the ideal reference voltage is 0.2 volt or less. A liquid crystal display device configured to generate and output the signal line driving power supply voltage described above. 2. A thin film transistor is provided at each intersection where a plurality of signal lines and scanning lines are arranged in a matrix, and a storage capacitor and a liquid crystal layer are connected in parallel between a pixel electrode connected to a drain electrode of the thin film transistor. A liquid crystal panel provided with a common line, a signal line driving circuit for driving the signal line, a scanning line driving circuit for driving the scanning line, a gamma correction circuit for outputting a gamma correction voltage, the liquid crystal panel and the liquid crystal panel. And a driving power supply device for supplying a driving voltage to each of the circuits, wherein the driving power supply device comprises: a gate-on voltage and a gate-off voltage of the thin film transistor, which are driving power supply voltages to the scanning line driving circuit. And a third common power supply voltage to the common wiring, which is variable by adding or subtracting a flicker control voltage for minimizing flicker to the ideal reference voltage. The signal line drive power supply voltage, wherein a difference between a voltage, a voltage obtained by halving a signal line drive power supply voltage which is a drive power supply voltage to the signal line drive circuit, and the ideal reference voltage is 0.2 volt or less. And a liquid crystal display device configured to generate and output the same. 3. The liquid crystal display device according to claim 1, wherein the first common voltage is the same as the second common voltage. 4. A signal line driving power supply, wherein a reference voltage of a gamma correction circuit obtained by dividing a driving power supply voltage from a signal line driving power supply voltage is fed back to a control circuit of an output circuit for generating and outputting the signal line driving power supply voltage. 3. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is configured to generate and output a voltage. 5. The liquid crystal according to claim 1, wherein the drive power supply device is configured to generate at least one of the first to third common voltages by dividing the at least one of the first to third common voltages from the signal line drive power supply voltage. Display device. 6. The liquid crystal display device according to claim 1, wherein an ideal reference voltage is generated and output to a gamma correction circuit or input from the gamma correction circuit. 7. The driving power supply device according to claim 1, wherein a switching power supply circuit for generating a signal line driving power supply voltage, a gate-on voltage, and a gate-off voltage is incorporated in a single module. Liquid crystal display device. 8. A drive power supply device comprising a switching power supply circuit for generating a signal line drive power supply voltage, a gate-on voltage and a gate-off voltage, and an output circuit for generating and outputting a second common voltage in a single module. 2. The liquid crystal display device according to claim 1, comprising a power supply module provided with a control terminal for changing the second common voltage from outside. 9. A drive power supply device comprising: a switching power supply circuit for generating a signal line drive power supply voltage, a gate-on voltage, and a gate-off voltage; and an output circuit for generating and outputting a third common voltage in a single module. 3. The liquid crystal display device according to claim 2, comprising a power supply module provided with a control terminal for changing said third common voltage from outside. 10. The power supply module according to claim 7, further comprising an output circuit for generating and outputting the first common voltage.
3. The liquid crystal display device according to 1. 11. The liquid crystal display device according to claim 7, wherein the power supply module is provided with a control terminal for controlling output on / off by a control pulse. 12. A gamma correction circuit comprising: a first correction voltage comprising a plurality of voltages obtained by adding a plurality of voltages obtained by dividing a difference between a signal line driving power supply voltage and an ideal reference voltage to a plurality of voltages; Outputting a second correction voltage composed of a plurality of voltages obtained by dividing the ideal reference voltage and the ground to a plurality of voltages to a signal line driving circuit, the signal line driving circuit driving an image signal to a signal line; A digital-to-analog converter that converts the voltage into a voltage, switches between the first and second correction voltages every horizontal scanning period in synchronization with a scanning line drive voltage, and sets the voltage as a reference voltage for the digital-to-analog converter. 7. The liquid crystal display device according to claim 6, wherein a driving voltage whose polarity is inverted with respect to an ideal reference voltage is applied. 13. A first voltage-dividing resistor group in which a gamma correction circuit is connected in series from a signal line driving power supply voltage to an ideal reference voltage in order from a first resistor to an n-th resistor; And a second voltage-dividing resistor group connected in series from the n-th resistor to the first resistor between the first and second voltage-dividing resistor groups, and each voltage between adjacent resistors of the first voltage-dividing resistor group. 13. The liquid crystal display device according to claim 12, wherein the first correction voltage is used as a first correction voltage, and each voltage between adjacent resistors of the second voltage-dividing resistor group is output as a second correction voltage. 14. A gamma correction circuit, comprising: a signal line driving power supply voltage and a ground;
And a second voltage-dividing resistor group connected in series from the n-th resistor to the first resistor following the first voltage-dividing resistor group. Wherein each voltage between adjacent resistors of the first voltage dividing resistor group is a first correction voltage, and each voltage between adjacent resistors of the second voltage dividing resistor group is a second correction voltage. To the signal line drive circuit as a correction voltage, and a voltage between the n-th resistor of the first voltage-dividing resistor group and the n-th resistor of the second voltage-dividing resistor group is referred to as an ideal reference voltage. And a digital-to-analog converter for converting the image signal into a signal line driving voltage, wherein the first and second corrections are performed every horizontal scanning period in synchronization with a scanning line driving voltage. And the reference voltage of the digital-to-analog converter by switching the voltage between adjacent pixels. The liquid crystal display device according to claim 1 or claim 2 polarity ideal reference voltage as a reference is configured to provide a driving voltage inverted.