JPH03197923A - Color liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain the display device of high luminance by making multicolor displaying without using color filters. CONSTITUTION:The data electrodes of an STN type liquid crystal layer 23 of the 1st layer are connected to a data electrode driver 28 and the STN type liquid crystal layer 24 of the 2nd layer are connected to another data electrode driver 29. The scanning electrodes of the STN type liquid crystal layer 23 of the 1st layer and the STN type liquid crystal layer 24 of the 2nd layer are both connected respectively to the same scanning electrode driver 27. The picture elements existing in the same positions of the scanning electrodes of the STN type liquid crystal layer 23 of the 1st layer and the STN type liquid crystal layer 24 of the 2nd layer are simultaneously scanned and voltages can be independently impressed to the respective data electrodes by the data electrode drivers 28, 29. The spectra of desired transmittance are obtd. by changing double refraction quantities DELTAn.d for each of the picture elements, by which the multicolor displaying is executed. The high luminance is obtd. in this way and the number of driving circuits is decreased and, therefore, the cost is reduced.

Description

[Detailed Description of the Invention] [Summary] Regarding a color liquid crystal display device capable of displaying multiple colors, the purpose of this invention is to perform a multicolor display with high brightness without using a color filter in a DSTN type liquid crystal display device. At least two liquid crystal layers whose birefringence changes depending on applied voltage and a polarizing plate whose total transmission spectrum is the product of the transmission spectra of each liquid crystal layer are laminated between the analyzer and the analyzer. A liquid crystal panel, a scan electrode driver that commonly controls the voltage applied to the scan electrodes of each of the liquid crystal layers, and data provided for each liquid crystal layer that independently controls the voltage applied to the data electrodes of each of the liquid crystal layers. Using an electrode driver,
It is configured to display multiple colors by changing the amount of birefringence for each pixel to obtain a desired transmittance spectrum.

[Industrial Field of Application] The present invention relates to a liquid crystal panel, and particularly to a color liquid crystal display device capable of displaying multiple colors.

Conventionally, in color liquid crystal display devices that perform multicolor display, the liquid crystal layer is used as an optical switch to turn on and off transmitted light, and three color filters of red, green, and blue are used for each pixel. It is provided.

By turning on and off each liquid crystal optical switch corresponding to each color filter, transmitted light is controlled to perform multicolor display. However, conventional color liquid crystal display devices have a problem in that light transmittance decreases depending on the color filter used, and a color liquid crystal display device with high brightness is desired.

(Prior technology) Conventional twisted nematic liquid crystals (TN liquid crystals), in which the molecular axes of liquid crystal molecules are twisted 90 degrees along the cell layer, have a low contrast ratio (and were not capable of large-capacity display); A super-twisted nematic liquid crystal (STN liquid crystal) has been put into practical use in which the angle of the liquid crystal cell is significantly increased to within the range of 180 degrees to 270 degrees, and the optical characteristics of the liquid crystal cell change sharply with respect to applied voltage. The number of pixels in the liquid crystal is 1, and due to the display method using its birefringence effect, the number of pixels in the liquid crystal is 10.
Large-capacity color liquid crystal display devices capable of displaying 4 to 10' lines in a simple matrix format using such STN liquid crystals have been commercialized for word processors, liquid crystal televisions, and the like.

When performing color display using this STN type liquid crystal, S
It is an essential requirement to perform white/black display using a TN type liquid crystal. This means that when displaying in color using this STN type liquid crystal, if the display color is not white/black, it will be red,
This is because color unevenness occurs between the three primary colors of green and blue. Therefore, in the past, various technologies were used to convert the STN liquid crystal into a white/black display, which was then used for ON/OFF switching, and color filters of the three primary colors of red, green, and blue were placed in front of the STN liquid crystal. are arranged to provide multicolor display.

Figure 11 shows a two-layer liquid crystal display panel called DSTN, in which two layers of conventional STN liquid crystal are laminated, and an optical STN liquid crystal panel without an electrode structure is superimposed as a compensation plate to eliminate display coloration. FIG. 2 is a cross-sectional view showing an example of the structure of FIG.

A two-layer liquid crystal display panel has a polarizing filter 10 called an analyzer and a polarizing filter 20 called a polarizer, and a first layer STN liquid crystal (driving panel) 30 for display and color compensation. It is formed by laminating a second layer STN type liquid crystal (compensation panel) 40. The display drive panel 30 includes two glass substrates 31.
．． 32 and ITO in an orthogonal relationship provided inside it.
Transparent electrodes 33.34 made of a transparent conductive material such as, and alignment films 35.36 provided inside the transparent electrodes 33.34.
and the driving liquid crystal 3 sealed between the alignment films 35 and 36.
7, and transparent electrodes 33 and 34 are connected to the driver 38. Furthermore, between the transparent electrode 34 and the glass substrate 32, three colors (red (R), green (G), blue (B)
)) The color filter 39 of the transparent electrode 3 of the drive panel 3
Laminated according to 3. Further, the compensation panel 40 includes two glass substrates 41 and 42, and these substrates 41 and 42.
The alignment films 43 and 44 provided inside the
3.44 and a liquid crystal 45 for color compensation sandwiched between 3.44 and 3.44 cm. Note that the positions of the drive panel 30 and the compensation panel 40 may be reversed, and the thickness dl of the liquid crystal 37 of the drive panel 30 and the thickness d2 of the liquid crystal 45 of the compensation panel 40 are the same value. .

[Problems to be Solved by the Invention] However, in a conventional two-layer color liquid crystal display device in which a color filter is laminated on a two-layer liquid crystal display panel having the above structure, it is difficult to display only each primary color (red, green, blue). At the time, the transmittance was theoretically reduced to 1/3 or less, resulting in a problem of darkness. . Furthermore, three drive circuits (drivers) are required for each pixel, which poses a problem of high cost.

An object of the present invention is to provide multicolor display without using a color filter in a two-layer STN type (DSTN type) liquid crystal display device, thereby achieving high brightness and reducing the number of drive circuits. An object of the present invention is to provide a color liquid crystal display device that can suppress the noise.

[Means to solve the problem]

The structure of a color liquid crystal display device of the present invention that achieves the above object is shown in FIG. The color liquid crystal display device of the present invention includes:
Between the analyzer 1 and the polarizer 2, there are at least two liquid crystal layers 3.4 whose birefringence changes depending on the applied voltage, and polarized light whose entire transmission spectrum is the product of the transmission spectra of each liquid crystal layer. A liquid crystal panel 6 in which a plate 5 is laminated, a scan electrode driver 7 that commonly controls the voltage applied to the scan electrodes of each liquid crystal layer 3.4, and a scan electrode driver 7 that commonly controls the voltage applied to the data electrodes of each liquid crystal layer 3, 4. The data electrode driver 8 is provided for each liquid crystal layer and is controlled independently. Multicolor display is performed by changing the amount of birefringence Δn−d for each pixel to obtain a desired transmittance spectrum.

[Effect]

In the color liquid crystal display device of the present invention, for example, when there are two liquid crystal layers, the voltage applied to each liquid crystal layer is adjusted so that the retardation ΔL·d of one liquid crystal is 0.70 μm and the retardation of the other liquid crystal is 0.70 μm. Blue color is displayed by setting ΔL・d to 1.10 μm, and setting the retardation Δn−d of one liquid crystal to 0.35 μm and the retardation ΔL・d of the other liquid crystal to 1.35 μm. If green is displayed, the retardation string d on one of the LCDs is 0.40.
μm, the retardation ΔL・d of the other liquid crystal is 1.65
If it is set to μm, red will be displayed.

(Examples) Examples of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 2 is an exploded perspective view showing the structure of an embodiment of the color liquid crystal display device of the present invention. In the figure, 21 is an analyzer (polarizing filter), 22 is a polarizer (polarizing filter), 23 is the first layer STN type liquid crystal layer, 24 is the second layer STN type liquid crystal layer,
25 indicates an analyzer (polarizing filter) laminated between the 11th STN type liquid crystal layer 23 and the second STN type liquid crystal layer 24, and these are laminated to form a DSTN type liquid crystal panel 2.
6. In this embodiment, a data electrode is provided at the upper bottom of the liquid crystal layer, a scanning electrode is provided at the lower bottom, and the first layer ST
The data electrode of the N-type liquid crystal layer 23 is connected to the data electrode driver 28.
The data electrodes of the second layer STN type liquid crystal layer 24 are connected to another data electrode driver 29, and the data electrodes of the second layer STN type liquid crystal layer 24 are connected to another data electrode driver 29.
The scan electrodes of the type liquid crystal layer 23 and the second STN type liquid crystal layer 24 are both connected to the same scan electrode driver 27. Therefore, pixels located at the same position in the first STN liquid crystal layer 23 and the second STN liquid crystal layer 24 are simultaneously scanned, but each data electrode has a data electrode driver 28.
Voltage can be applied independently by

FIG. 3 is a cross-sectional view of one pixel of the liquid crystal panel 26 shown in FIG. The first STN liquid crystal layer 23 and the second STN liquid crystal layer 24 are made of glass substrates 231, 241 and ITO, respectively.
Data electrodes 232°242 made of transparent conductive materials such as
, liquid crystals 233 and 243, scan electrodes 234 and 244 made of a transparent conductive material such as ITO, and glass substrates 235 and 245 are laminated in this order.

The data electrodes 232, 242 having the same width and the scanning electrodes 234, 244 having the same width are orthogonal to each other, and one pixel is formed at the intersection.

FIG. 4 shows the analyzer 21 of the liquid crystal panel 26 shown in FIG.
25 and the direction of the absorption axis of the polarizer 22 and the liquid crystal layer 23
．． 24 shows the orientation direction of liquid crystals in No. 24. As can be seen from this figure, the absorption axes of the analyzer 21 and the polarizer 22 are 0°, and the absorption axis direction of the analyzer 25 is 90'.

Furthermore, the orientation direction of the liquid crystal 1i23 and the liquid crystal layer 24 is 45°.
The liquid crystal layer has a homogeneous alignment. A desired transmittance spectrum can be obtained by independently changing the driving voltages of the two liquid crystal layers 23 and 24 described above.

In a color liquid crystal display device equipped with a liquid crystal panel configured as described above, blue (B) is shown in FIG.

A method for producing transmitted light having green (G) and red (R) spectra will be explained.

FIG. 6 shows an operation for changing the spectrum of transmitted light to red in order to display red.

In order to make the transmitted light red, the voltage applied to each liquid crystal layer 23 and 24 is adjusted to adjust the retardation ΔL of one liquid crystal layer.
d is 0.40 μm, and the other retardation ΔL・d is 1
．． The thickness should be 65 μm. Δle・d=0.40μm
The broken line shows the transmittance spectrum for the wavelength when .
The dotted line shows the transmittance spectrum with respect to the wavelength when Δn-d=1.65 μm. Since the overall transmittance of the liquid crystal panel 26 is the product of both transmission spectra, red transmitted light shown by the solid line is obtained.

FIG. 7 shows an operation for changing the spectrum of transmitted light to green in order to display green.

In order to make the transmitted light green, each liquid crystal layer 23°24
By adjusting the voltage applied to the liquid crystal layer, the retardation Δn-d of one liquid crystal layer was 0.35 μm, and the retardation Δn-d of the other liquid crystal layer was 0.35 μm.
Set d to be 1.35 μm. Δle・d=0.3
The dotted line shows the transmittance spectrum for the wavelength when 5 μm, and the dotted line shows the transmittance spectrum for the wavelength when Δyr−d=1.35 μm. The overall transmittance of the liquid crystal panel 26, which is the product of these two transmission spectra, is as shown by the solid line, and green transmitted light is obtained.

FIG. 8 shows an operation for displaying a blue color.

In order to make the transmitted light blue, the voltages applied to each liquid crystal layer 23 and 24 are adjusted so that the retardation Δn-d of one liquid crystal layer is 0.70 μm1, and the retardation Δn-d of the other liquid crystal layer is 1.1.
When it is 0 μm, Δn−d=0. The transmittance spectrum for the wavelength at '70 um is as shown by the broken line,
The spectrum of transmittance with respect to wavelength when string d = 1.10 μm is as shown by a dotted line. The overall transmittance of the liquid crystal panel 26, which is the product of these two transmission spectra, is as shown by the solid line, and blue transmitted light is obtained.

Further, as shown in FIG. 9, when the retardation ΔL·d of both liquid crystal layers is set to 0.01 μm, no light is transmitted and a black display is obtained. Furthermore, by setting the retardation ΔL·d of both liquid crystal layers to 0.27 μm,
A white display is obtained. (2) Also, Δle・d of both liquid crystals
A black display can be obtained by setting the value to 0.01 μm.

As described above, in the color liquid crystal display device of the present invention, by independently changing the retardation ΔL·d of each liquid crystal layer stacked in two layers without using a color filter, blue (B), green ( Multi-color display of red (R), black (BL), and white (W) can be realized.

In addition, in the above-mentioned example, a liquid crystal panel using a homogeneously oriented liquid crystal as the liquid crystal layer was used, but a liquid crystal panel using a twisted liquid crystal as the liquid crystal layer, a liquid crystal that is homogeneously oriented as the liquid crystal layer, and a twisted liquid crystal. It is also possible to use a liquid crystal panel that uses a combination of both types of liquid crystals.

Further, the color liquid crystal display device of the present invention can also be used as a projection type liquid crystal display. Further, in the above embodiment, the liquid crystal layer is described as having two layers, but if the number of liquid crystal layers to be stacked is further increased, it is possible to add a brightness modulation layer.

〔Effect of the invention〕

As explained above, according to the present invention, in a two-layer STN type (DSTN type) liquid crystal display device, by performing multicolor display without using a color filter, the brightness is high and the driving circuit is Reducing the number has the effect of reducing costs.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the basic configuration of the present invention, Fig. 2 is an exploded perspective view showing the structure of an embodiment of the color liquid crystal display device of the present invention, and Fig. 3 is a partial cross-section showing the structure of one pixel in Fig. 2. Figure 4 is an explanatory diagram showing the light absorption axis of each layer in Figure 2 and the alignment direction of liquid crystal. Figure 5 is a diagram showing the spectrum of light in each color of red, green, and blue. Figure 6 is red. Figure 7 is a spectrum diagram showing the coloring process of green, Figure 8 is a spectrum diagram showing the blue coloring process, Figure 9 is a spectrum diagram showing the black coloring process, Figure 10 is a spectrum diagram showing the coloring process of black. 11 is a spectral diagram showing the white coloring process, and FIG. 11 is a sectional view showing the structure of a conventional color liquid crystal display device. DESCRIPTION OF SYMBOLS 1... Analyzer, 2... Polarizer, 3.4... Liquid crystal layer, 5... Analyzer, 6... Liquid crystal panel, 7... Operating electrode driver, 8.9...・Data electrode driver, 21
．． 25... Analyzer, 22... Polarizer, 23.24.
...Liquid crystal layer, 25...Analyzer, 26...Liquid crystal panel of one embodiment of the present invention, 27...Operation electrode driver, 2
8.29...Data electrode driver, 231, 235.
241.245...Glass substrate, 232.242...
・Data electrode, 233.243...Liquid crystal, 234,
244...Scanning electrode.

Claims (1)

[Claims] Between the analyzer (1) and the polarizer (2), there are at least two liquid crystal layers (3) whose birefringence changes depending on the applied voltage.
4) and a polarizing plate (5) such that the entire transmission spectrum is the product of the transmission spectra of each liquid crystal layer (6); and each of the liquid crystal layers (3) and (4). A scan electrode driver (7) that commonly controls the voltage applied to the scan electrodes, and a scan electrode driver (7) provided for each liquid crystal layer to independently control the voltage applied to the data electrodes of each of the liquid crystal layers (3) and (4). data electrode drivers (8) and (9), and the amount of birefringence (Δ
A color liquid crystal display device characterized by displaying multiple colors by changing n.d) to obtain a desired transmittance spectrum.