JPH04214532A - liquid crystal display device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 with constant RGB brightness.

0002

[Background Art] In recent years, in the field of information equipment centered on computers, liquid crystal display devices using field-effect thin film transistors (hereinafter referred to as "TFTs") formed on insulating substrates such as glass are capable of full-color display. Demand is increasing because it provides high image quality.

A conventional liquid crystal display device will be explained below with reference to the drawings. FIG. 5 is a configuration diagram of a conventional liquid crystal display device. In FIG. 5, 41 is a color filter;
2G is a liquid crystal layer, 43G is a liquid crystal molecule, 44G, 44B are T
FT, 45G is a pixel electrode, and 46 is a backlight. This liquid crystal display device combines a liquid crystal cell with color filters 41 for three primary colors, R (red), G (green), and B (blue), and displays full color by controlling the amount of light transmitted through a light valve using an image signal. Colorization is performed using an optical shutter method that enables.

The operation of the liquid crystal display device configured as described above will be explained below. As shown in Figure 5, G
When the TFT 44G in the pixel section is turned on, the liquid crystal molecules 43G in the liquid crystal layer 42G of the pixel electrode 45G, which corresponds to the G filter section of the color filter 41, are aligned in the direction of the electric field, and the backlight light 46 passes through the G filter of the color filter 41. This emits a green light.

[0005] Also, like the B pixel part, TFT44B
When turned off, the backlight light 46 will be blocked.

[0006]

[Problems to be Solved by the Invention] Figure 6 shows the spectral transmission characteristics of a color filter produced by a certain dyeing method.
According to the above conventional configuration, as shown in Figure 6, the transmittance of each of the three primary colors of R (red), G (green), and B (blue) is different, so the original color display is different. There was a problem in that the images were displayed differently, resulting in color shift.

An object of the present invention is to provide a liquid crystal display device that can eliminate color shift in display colors.

[0008]

[Means for Solving the Problem] A liquid crystal display device according to claim 1 comprises a liquid crystal, a thin film transistor connected to a pixel electrode, R (red), G (green), and B (blue) color filters, and a back panel. Equipped with lights. The backlight is a three-wavelength fluorescent lamp whose peak wavelengths correspond to the respective transmittances of the R (red), G (green), and B (blue) color filters.

[0009] The liquid crystal display device according to claim 2 includes a liquid crystal;
Thin film transistor connected to pixel electrode, R (red), G
(green), B (blue) color filters, and a backlight. And R (red), G (green), B (blue)
m given to each of the liquid crystals corresponding to the color filter of
The bit (m is a natural number) signal is R (red), G (green),
N different voltages (n is an even number of 2 or more) and R (red), G are applied to each of the liquid crystals corresponding to the B (blue) color filter.
(2m - n) voltages common to each of the liquid crystals corresponding to the (green) and B (blue) color filters.

[0010] The liquid crystal display device according to claim 3 includes a liquid crystal;
Thin film transistor connected to pixel electrode, R (red), G
(green), B (blue) color filters, and a backlight. Further, an R (red) driver, a G (green) driver, and a B (blue) driver with different voltage magnifications are provided.

[0011]

[Operation] According to the structure of claim 1, the backlight is a three-wavelength fluorescent lamp that arbitrarily sets the peak wavelength corresponding to the transmittance of each of the R, G, and B color filters. , the backlight light can be adjusted,
Differences in transmittance among the R, G, and B color filters can be made uniform.

According to the structure of claim 2, R, G, B
m given to each of the liquid crystals corresponding to the color filter of
A signal of bits (m is a natural number) is transmitted to each of the liquid crystals corresponding to R, G, and B color filters by n different bits (n is 2).
The arrangement of the liquid crystal molecules can be controlled by selecting from the (2m - n) voltages common to each of the liquid crystals corresponding to the R, G, and B color filters. Backlight can be adjusted, R, G, B
The difference in transmittance of each color filter can be made uniform.

According to the third aspect of the present invention, the alignment of liquid crystal molecules is controlled by providing an R (red) driver, a G (green) driver, and a B (blue) driver with different voltage multipliers. You can adjust the backlight by pressing R,
The difference in transmittance between the G and B color filters can be made uniform.

[0014]

【Example】

First Embodiment A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a CIE chromaticity diagram showing the chromaticity of backlight light of a liquid crystal display device according to a first embodiment of the present invention. This CI
The E chromaticity diagram associates a color with a certain hue and color saturation with one coordinate point (chromaticity point) on the xy plane, and shows the hue and color saturation of that color depending on the position of this coordinate point. It is something to express.

The liquid crystal display device of this embodiment has three peak wavelengths of R (red), G (green), and B (blue) in the spectral energy distribution using a conventional three-wavelength fluorescent lamp as the backlight light source. Some λR (610nm), λG (550n
m), λB (470 nm), the peak wavelength of G and the peak wavelength of B, λB, are corrected based on the longest wavelength, λR, of the peak wavelength of R.

That is, in FIG. 1, a color located within a range whose chromaticity indicates white at a distance close to the chromaticity point PG of G and the chromaticity point PB of B from the chromaticity point PO of the conventional backlight light source. By using a backlight source close to the degree point PX, the difference in transmittance between the R, G, and B color filters is corrected and becomes constant. However, in this case, the chromaticity point PX of the backlight light source (three-wavelength fluorescent lamp) to be corrected differs depending on the refractive index anisotropy of the filter material and liquid crystal material, the liquid crystal layer thickness of the liquid crystal cell, and the like.

As described above, according to this embodiment, R, G
By using a backlight light source (three-wavelength fluorescent lamp) that can correct the difference in transmittance between the R, G, and B color filters, the transmittance of each of the R, G, and B color filters can be made uniform, and color shift in displayed colors can be corrected. can be eliminated. Second Embodiment A second embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a diagram showing the structure of a liquid crystal display device according to a second embodiment of the invention. In FIG. 2, 21 is a common selection voltage, 22 is an R selector, 23 is a G selector,
24 is a selector for B, 25 is a data bus for R, 26 is a G
27 is a B data bus. The operation of the liquid crystal display device configured as described above will be described below.

As shown in FIG. 2, R, G, and B are each m
There are (2m −2) types of common selection voltages 21 selected by the bit data buses 25, 26, and 27, and the remaining 2
The type of voltage is the selector 22 for R, the selector 23 for G,
The voltages are selected by the B selector 24 as different voltages (correction voltages). These correction voltages (VRX, VRY)
, (VGX, VGY), (VBX, VBY) are (VR
X<VRY)<(VGX<VGY)<(VBX<VBY
).

By setting in this manner, the applied voltage applied to the liquid crystal is controlled by the R selector 22 and the G selector 23.
, B selector 24 is provided with two types of correction voltages (VRX, VRY), (VGX, VGY), (VB
By selecting X, VBY), the arrangement of liquid crystal molecules can be controlled and the backlight light can be adjusted. As described above, according to this embodiment, the applied voltage applied to the liquid crystal is adjusted to two types of correction voltages (VRX, VRY
), (VGX, VGY), and (VBX, VBY), the arrangement of liquid crystal molecules is controlled and the backlight light can be adjusted. By adjusting the backlight light, it is possible to equalize the difference in transmittance of each of the R, G, and B color filters, and eliminate color shift in displayed colors.

Third Embodiment A third embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a diagram showing the configuration of a liquid crystal display device according to a third embodiment of the present invention. In FIG. 3, 31 is a Y driver;
32 is the XO output driver for R, 33 is the XO output driver for G, 34 is the XO output driver for B, 35
is an LCD panel, and 36 is a color filter.

The operation of the liquid crystal display device constructed as described above will be explained below. FIG. 4 is a diagram showing the application of transmittance to an LCD. Taking advantage of the characteristic that the transmittance changes due to the alignment of liquid crystal molecules as voltage is applied,
Output driver 33 and XO for B Output driver 3
The respective output voltages of R and G in the LCD panel 35 are
, B so that the difference in transmittance between the color filters 36 is uniform, it is possible to adjust the backlight light by the slight inclination of the orientation of the liquid crystal molecules.

As described above, according to this embodiment, the voltage applied to the liquid crystal is controlled by the R XO output driver 32, the G
The XO output driver 33 for XO and the XO output driver 34 for B control the arrangement of liquid crystal molecules by correcting the difference in transmittance of the R, G, and B color filters 36 to be uniform. Light can be adjusted, R, G, B color filters 36
It is possible to make the difference in transmittance uniform and eliminate color shift in displayed colors.

[0024]

[Effects of the Invention] In the liquid crystal display device according to claim 1, the backlight is a three-wavelength fluorescent lamp in which the peak wavelengths corresponding to the respective transmittances of the R, G, and B color filters are arbitrarily set. As a result, backlight light can be adjusted, the difference in transmittance of each of the R, G, and B color filters can be made uniform, and color shift in displayed colors can be eliminated.

[0025] The liquid crystal display device according to claim 2 has R, G,
An m-bit (m is a natural number) signal to be given to each of the liquid crystals corresponding to the B color filter is applied to different n (n is an even number of 2 or more) signals to each of the liquid crystals corresponding to the R, G, and B color filters. By selecting from the voltage and (2m - n) voltages common to each of the liquid crystals corresponding to R, G, and B color filters, it is possible to control the arrangement of liquid crystal molecules and adjust the backlight light. is completed, R, G,
Make the difference in transmittance of each color filter of B uniform,
Color shift in display colors can be eliminated.

The liquid crystal display device according to claim 3 controls the arrangement of liquid crystal molecules by providing an R (red) driver, a G (green) driver, and a B (blue) driver with different voltage magnifications. You can adjust the backlight by
, G, and B color filters can be made uniform, and color shift in displayed colors can be eliminated.

[Brief explanation of the drawing]

FIG. 1 is a CIE chromaticity diagram showing the chromaticity of backlight light of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the configuration of a liquid crystal display device according to a second embodiment of the invention.

FIG. 3 is a diagram showing the configuration of a liquid crystal display device according to a third embodiment of the invention.

FIG. 4 is a diagram showing the application of transmittance of an LCD.

FIG. 5 is a configuration diagram of a conventional liquid crystal display device.

FIG. 6 is a spectral transmission characteristic diagram of a color filter obtained by a certain dyeing method.

[Explanation of symbols]

21 Common selection voltage 22 R selector 23 G selector 24 B selector 25 R data bus 26 G data bus 27 B data bus 32 R XO output driver 33 G
XO output driver 34 for B XO output driver 36 Color filter

Claims (3)

[Claims] 1. A liquid crystal, a thin film transistor connected to a pixel electrode, R (red), G (green), B (blue) color filters, and a backlight, the backlight being connected to the R (red). ), G (green), and B (blue) color filters, each of which has a peak wavelength corresponding to its respective transmittance. 2. A display device comprising a liquid crystal, a thin film transistor connected to a pixel electrode, R (red), G (green), and B (blue) color filters, and a backlight, the R (red), G (
The m-bit (m is a natural number) signal given to each of the liquid crystals corresponding to the green) and B (blue) color filters is
(red), G (green), and B (blue) color filters. Common to each liquid crystal corresponding to the color filter of blue) (2m - n
) liquid crystal display device with voltages to choose from. 3. A liquid crystal display device comprising a liquid crystal, a thin film transistor connected to a pixel electrode, R (red), G (green), and B (blue) color filters, and a backlight, with different voltage magnifications.
(red) screwdriver, G (green) screwdriver and B (
LCD display device with a driver for blue).