JPH0850273A - Color liquid crystal display device - Google Patents

Abstract

PURPOSE:To make transmissivity coincident and to realize accurate color expression by correcting driving voltage impressed on respective picture elements R, G and B for every color. CONSTITUTION:This color liquid crystal display device having plural picture elements for red, green and blue is provided with a driving voltage circuit 8 generating signal voltage or scanning voltage different by every color, and drivers 2 to 5 receiving the voltage for each color from the driving voltage circuit 8 and impressing the signal voltage or the scanning voltage on the plural picture elements for red, green and blue. The signal voltage for respective colors or the scanning voltage for respective colors at the time of obtaining nearly the same transmissivity at the positions of the picture elements for red, green and blue in the color liquid crystal display device is made different from each other based on the wavelength dependency in the transmissivity characteristic of the picture element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal color display device, and more particularly to a method of driving a pixel in which scanning (X) electrodes and signal (Y) electrodes are arranged in a matrix.

[0002]

2. Description of the Related Art A color liquid crystal display panel arranged in a matrix is provided with RGB three primary color filters in each pixel, and by controlling the liquid crystal voltage by the X and Y electrode signals for the pixel, the transmittance is changed to change the color. The display is performed. A specific configuration of such a color liquid crystal display panel is shown, for example, in FIGS. 1 and 2 of JP-A-58-156995.

[0003]

When a twisted nematic (hereinafter abbreviated as TN) liquid crystal is used as the liquid crystal, optical rotation dispersion occurs in which the relationship between the driving voltage and the transmittance differs for each of the three primary colors. FIG. 1A shows this phenomenon. The figure shows the relationship between the liquid crystal drive voltage and the transmittance measured through each color filter. In this example, a Pch system is used as the liquid crystal, the cell thickness is 8 μm, and the upper and lower polarizing plates are substantially orthogonal to each other. As can be seen from the figure, the drive voltage increases as the wavelength becomes shorter in the order of R, G, and B. This phenomenon is due to the wavelength dependence of the refractive index anisotropy (Δn) of the TN liquid crystal, and the T
The N liquid crystal can be completely eliminated in principle. When the cell thickness d is increased, {n. By setting d> 1.0, it is possible to slightly reduce the difference in drive voltage.
On the other hand, it has drawbacks such as a narrow viewing angle and a slow response speed of liquid crystal.

In a conventional black-and-white display panel, such dispersion is not a problem and is a phenomenon unique to a color display panel.

When the conventional time-division driving is applied to such a color display panel as it is and the same voltage is applied to each pixel of the three primary colors, the transmittance of each pixel of the three primary colors is not equal, which causes a problem. FIG. 1B shows R, G, and R of this color panel.
B is represented on a chromaticity diagram. In the figure, the dotted triangle indicates the color coordinates of the color filter, and the solid line indicates the color coordinates when the panel is driven. When the same voltage is applied to the corresponding pixels of R, G, and B, the transmissivity of each color is different, so that the expression color of the panel becomes bluish, and accurate color reproduction cannot be performed.

[0006] The present invention relates to a color liquid crystal display device, and more particularly, to enabling accurate color expression.

[0007]

SOLUTION: A scanning electrode, a signal electrode, a color filter of three primary colors aligned along the scanning electrode or the signal electrode, and three signal electrode drives for driving a signal electrode corresponding to the color of the color filter. Equipped with a circuit,
The three signal electrode driving circuits generate driving voltages different from each other.

[0008]

As described above, for the optical rotation dispersion of the liquid crystal. When the same voltage is applied to each of the three primary color pixels, the range of colors that can be expressed is biased due to the different transmittance, and an accurate color table cannot be obtained. In order to solve this drawback, in the present invention, R, G, B
By correcting the drive voltage applied to each pixel for each color, the transmittances are matched and the color expression of the color liquid crystal panel is made accurate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail based on embodiments.

FIG. 2 is a block diagram of a driving circuit of the color liquid crystal display device. The display panel 1 forms a matrix composed of N X (scanning) electrodes and M Y (signal) electrodes. In this case, the color filters are aligned along the Y electrodes, and the Y electrodes for R, G, and B colors are connected to Y drivers 2, 3, and 4 which are independent for each color. The image signal is A / D-converted by 6, and the data is latched by the Y driver 2, 3, 4 of the corresponding color by the timing signal from the control circuit 7. The driver 2,
3 and 4 are connected to a drive voltage circuit 8 that generates a signal voltage different for each color. On the other hand, the scan electrodes are driven by the X driver 5. By applying different Y (signal) voltages to R, G, and B in this way, it is possible to correct the difference in transmittance for R, G, and B.

FIG. 3 shows the drive voltage waveform described above. (A) is a voltage waveform corresponding to R, G, and B of Y (signal), and according to (a) of FIG. 1, the voltage V _{XR of} each color,
V _XG and V _XB are V _XR <V _XG <V _XB . (B) is a waveform of the X (scanning) electrode, and shows a case where the i-th scanning line is selected. (C) shows a voltage waveform applied to the liquid crystal by the Y electrode voltage and the X electrode voltage. By correcting the drive voltages for R, G, and B in this way, it is possible to realize an accurate color expression without color deviation.

The second embodiment will be described with reference to the block diagram of FIG. The display panel 1 forms a matrix including N X (scanning) electrodes and M Y (signal) electrodes. The color filters are aligned along the X electrodes, and the scan electrodes of the same color are connected to the same scan electrode drive drivers 12, 13, 14. The drivers 12, 13, 14 are connected to a drive circuit 8 that generates different scanning voltages for each color, and the scanning voltage can be changed according to the corresponding color to correct the difference in liquid crystal transmittance for each color. Becomes The A / D and the signal drive circuit have been described in the above-mentioned embodiment and will not be described. The drive voltage waveform diagram of this embodiment is omitted because it can be easily inferred from FIG.

[0013]

As described above, according to the present invention, it is possible to solve the color deviation due to the optical rotatory dispersion of the liquid crystal without sacrificing the viewing angle characteristics and the response speed which are important requirements of the liquid crystal panel. , More accurate color expression is possible. Further, according to the present invention, since the driving voltage for each of R, G, and B can be set independently, in addition to the correction of the optical rotation dispersion described above, for example, the correction of the deviation of the color specification based on the imbalance of the color filter can be performed. Is also effective.

Although the above description has been made with reference to the case of the vague display (transmission state in the absence of an electric field), the present invention can be applied to the negative display in the same manner.

[Brief description of drawings]

FIG. 1A is a diagram showing wavelength dependence of a drive voltage due to optical rotation dispersion of liquid crystal, FIG. 1B is a chromaticity diagram, a dotted line is a chromaticity coordinate of a color filter, and a solid line is a diagram in FIG. The chromaticity coordinates of a color liquid crystal display panel having characteristics are shown.

FIG. 2 is a circuit block diagram showing a first embodiment of the present invention.

FIGS. 3A to 3C are drive voltage waveform diagrams of the embodiment.

FIG. 4 is a circuit block diagram showing a second embodiment of the present invention.

[Explanation of symbols]

 1 ・ ・ ・ ・ ・ Color liquid crystal display panel 2,3,4,15 ・ ・ ・ ・ Y driver 5,12,13,14 ・ ・ X driver 6 ・ ・ ・ ・・ ・ A / D 7 ・ ・ ・ ・ ・ ・ ・ ・ Control circuit 8 ・ ・ ・ ・ ・ ・ Drive voltage circuit

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] September 11, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

[Correction content]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal color display device, and more particularly to a color liquid crystal display capable of accurate color expression.
Regarding the device.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

[0003]

When a twisted nematic (hereinafter abbreviated as TN) liquid crystal is used as the liquid crystal, optical rotation dispersion occurs in which the relationship between the driving voltage and the transmittance differs for each of the three primary colors. FIG. 1A shows this phenomenon. The figure shows the relationship between the liquid crystal drive voltage and the transmittance measured through each color filter. In this example, a Pch system is used as the liquid crystal, the cell thickness is 8 μm, and the upper and lower polarizing plates are substantially orthogonal to each other. As can be seen from the figure, the drive voltage increases as the wavelength becomes shorter in the order of R, G, and B. This phenomenon is due to the wavelength dependence of the refractive index anisotropy (Δn) of the TN liquid crystal, and the T
In principle, N liquid crystals cannot be completely eliminated .
When the cell thickness d is increased, {n. By setting d> 1.0, it is possible to slightly reduce the difference between the driving voltages, but on the other hand, there are disadvantages such as a decrease in the viewing angle and a reduction in the response speed of the liquid crystal.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

[0007]

The present invention achieves the above object.
Therefore, first, multiple images for red, green, and blue
Color-based liquid crystal display devices that have different colors
A drive voltage circuit for generating a signal voltage and the drive voltage circuit
Receive the signal voltage for each color from the above, red, green, blue
Driver for applying signal voltage to multiple pixels for
E, for red, green, and
Obtain substantially the same transmittance at the position of the pixel for blue color
Signal voltage for each color depending on the wavelength of the transmittance characteristics of the pixel.
It is characterized by being different from each other based on the existence.
Secondly, it has a plurality of pixels for red, green and blue.
In a color liquid crystal display device, different scanning voltage is applied for each color.
Generated drive voltage circuit, and for each color from the drive voltage circuit
Upon receiving the scanning voltage, a plurality of red, green and blue
A driver for applying a scanning voltage to the pixel is provided,
For red, green, and blue in a color LCD device
For each color when obtaining almost the same transmittance at the pixel position
The scanning voltage is based on the wavelength dependence of the transmittance characteristics of the pixel.
The feature is that they are different from each other.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

[0013]

Industrial Applicability As described above, according to the present invention, it is possible to solve the color deviation due to the optical rotatory dispersion of the liquid crystal without sacrificing the viewing angle characteristics and the response speed which are important requirements of the liquid crystal panel. , More accurate color expression is possible. Further, according to the present invention, the drive voltage for each of R, G, and B can be independently set by the drive voltage circuit, so that in addition to the above-described correction of optical rotation dispersion,
For example, it is also effective for correction of color deviation due to color filter imbalance.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

In the above description, the positive display (transmissive state in the absence of an electric field) has been described as an example. However, the present invention can be applied to negative display in the same manner.

Claims (1)

[Claims] 1. A scanning electrode, a signal electrode, three primary color filters aligned along the scanning electrode or the signal electrode, and three signal electrode driving circuits for driving signal electrodes corresponding to the color filters, The color liquid crystal display device, wherein the three signal electrode driving circuits generate driving voltages different from each other.