JPS59189317A - Color liquid-crystal display device - Google Patents

Abstract

PURPOSE:To improve transmittivity and contrast by laminating a liquid-crystal cell which has light shutter effect and TN type liquid crystal which has a polychromatic polarizing plate, and arranging electrodes corresponding to them respectively. CONSTITUTION:A cell A is a TN type cell sandwiched between a couple of polarizing plates 1 and 8, and a cell B is a TN type cell having the polychromatic polarizing plate 7 of, for example, red R, green G, and blue B; and transparent electrodes 11 and 12, and 13 and 16 of the cells A and B have picture elements corresponding to each other. When the polarizing plates 1 and 8, and polarizing plate 8 and polychromatic polarizing plate 7 are made to have their axes of polarization crossing at right angle, incident light is consequently white by being absorbed by none of the polarizing plates when no voltage is applied. When a voltage is applied only to the cell B, thin red display is obtained by the additive mixing of red of a red color polarizing plate part R applied with the voltage, and white of a green part G and white of a blue part which are not applied with the voltage, and when voltages are applied to both cells A and B, dark red display and intermediate display of thin red and dark red are realized. Further, when a voltage is applied only to the cell A, black-and-white display is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color liquid crystal display device in which a first liquid crystal cell having a light-shuttering effect and a second liquid crystal cell having a multicolor polarizing plate are layered.

Conventional technology Display devices using liquid crystals are superior in terms of low power consumption, thinness, and long life, and their applications are extremely wide ranging from digital clocks, calculators, and measuring instruments to, more recently, automobile instruments and LCD televisions. It extends to

As colorization becomes more widespread, the demand for colorization increases year by year, and various methods have already been devised. However, in terms of practical application, it has its advantages and disadvantages.

Two typical examples will be briefly described below.

The first method is to use a color filter and a TN type liquid crystal cell. FIG. 1 shows a schematic cross-sectional view. A pair of polarizing plates 1 and 2 are arranged so that their polarization axes are in the same direction, and a nematic liquid crystal composition is screwed between them.
An N-type liquid crystal cell is inserted. ′=! In addition, the three primary colors of light, red (6) and green (G), are arranged on one substrate 4 of the liquid crystal cell.
), blue) filters 5 are provided. Therefore, in a state where no voltage is applied, no light is transmitted and the color becomes black, but in a state where a voltage is applied, the color becomes the color of the filter at the point where f' is applied.

That is, if the filter pattern (two-electrode pattern) is fine and strong, it is in principle the same as a color CRT, and full color can be achieved by additive color mixture. However, with this method, even when the color is white, it is absorbed by the filter, resulting in a display with extremely low transmittance. For example, even when displaying red, other green and blue pixels are black, so
In the case of a reflective display, the color becomes dark red. Therefore, it is a transmissive type, and if you do not use a high-brightness backlight,
It has the disadvantage that sufficient color display is not possible. This results in the loss of low power consumption, which is an advantage of liquid crystal display devices, and the range of applications is extremely limited.

The second option is to use a multicolor polarizing plate and a TN type liquid crystal cell. FIG. 2 shows a schematic cross-sectional view. A multicolor color polarizing plate is one in which multiple color polarizing plates are arranged in a single polarizing plate. The color polarizing plates are arranged in stripes.

Furthermore, transparent electrodes 6 are provided corresponding to the stripes of the multicolor polarizing plate. If the polarization axes of the polarizing plate 1 and the polychromatic polarizing plate 7 are perpendicular to each other, when no voltage is applied, the light passes through and becomes white, and when a voltage is applied, the light is absorbed by the color polarizing plate at the point where the voltage is applied. 1) The color of the color polarizing plate. Furthermore, if the pitch of the stripes of the color polarizing plate is small, it is possible to produce mixed colors. For example, by applying a voltage to red (G) and the edge (G), yellow can be displayed. However, for example, when displaying red, the other green and blue pixels are white, so even a reflective type that uses a color filter will not produce a dark red color, but on the contrary, it will become a pale red color, and when a color filter is used, the color will not be dark red. Although it provides a display with high transmittance compared to the previous method,
It has the disadvantage that there is not enough female contrast.

Purpose of the Invention The present invention has been made in view of the drawbacks of the above two examples, and
The purpose is to improve the need for a backlight due to the low transmittance, which is a drawback of the single-filter method, and the low contrast, which is a drawback of the color polarizing plate method. For this purpose, a first liquid crystal cell having a light-shutter effect and a second TN type liquid crystal cell having a multicolor polarizing plate were constructed in a laminated structure.

Composition of the invention Hereinafter, the present invention will be explained in detail based on examples.

FIG. 3 shows a schematic sectional view of one embodiment of the present invention. Cell A
is a TN type cell narrowed by a pair of polarizing plates 1 and 8, and cell B is a TN type cell having a multicolor polarizing plate 7 of, for example, red (0), green (G), and blue (B). . In addition, the transparent electrodes 11, 12 and 13.6 of cell A and cell B are the same.
pixels correspond.

If the polarizing axes of the polarizing plates 1 and 8, and of the polarizing plate 8 and the multicolor polarizing plate 7 are made to intersect with each other by nM, the incident light will be absorbed by the polarizing plates and become white when no voltage is applied. The display color when a voltage is applied to the A cell or the B cell will be described below using a red display as an example.

Firstly, if voltage is applied only to the B cell, it is obvious that the second
It is the same as the conventional example shown in the figure, and in the case of red display, the red color of the part (6) of the red color polarizing plate 5 to which voltage is applied f' and the white color of the edge (G) to which no voltage is applied. By additive color mixing with the white color of the back), a light red color is displayed.

Second, if voltage is applied to both A cell and B cell, the first
It is possible to display the same dark red as in the conventional example using the color filter shown in the figure, and to display an intermediate color between the above-mentioned light red and this dark red, which is a feature of the present invention. In the former case, a voltage is applied to the red color polarizing plate portion (6) of the B cell or the entire surface of the B cell, and then the green (G) and blue color polarizing plate portions CB of the B cell are applied.
) can be obtained by applying a voltage to the electrode of the A cell corresponding to . At this time, the cell serves as a light shutter.

A voltage is applied only to the latter +d, the red color polarizing plate part of the B cell), and the electrode of the A cell corresponding to the green color polarizing plate part (G) (or the blue color polarizing plate part (E)) of the B cell. is obtained by applying a voltage to n. In this case, the red color of the red color polarizing plate part (6) and the green color polarizing plate part (G
) (The black color of the blue color polarizing plate part (B)) is mixed with the white color of the blue color polarizing plate part (E) (green color polarizing plate part (G)), which makes it difficult to use the method using multicolor color polarizing plates. By using a light red color and a color filter, the color became an intermediate color between the dark red color and the reflective type, and a display with high brightness and sufficient contrast was obtained.

Another method for obtaining this intermediate color is to apply voltage only to the red color polarizing plate section (5) of the B cell, and to
This is also possible by applying an intermediate voltage between the threshold voltages of the TN liquid crystal of the A cell to the electrodes of the A cell corresponding to the blue color polarizing plate section). In this case, 1 is an additive color mixture of the red of the red color polarizing plate part (6) and the gray part of the green part (G) and the blue color polarizing plate part (B), and similarly an intermediate color between light red and dark red is obtained. It was. In particular, with this method, it is possible to freely change the saturation and brightness of the red color by changing the mark 7ID voltage to the cell A.

Third, if voltage is applied only to the A cell, the conventional TN
It is possible to display the same black and white display as a type liquid crystal display.

FIG. 4.5.6 shows a schematic cross-sectional view of an example in which a GH type liquid crystal cell is used as the first liquid crystal cell having a light shutter effect. All of them use a P-type nematic liquid crystal composition (GH liquid crystal) 14 to which a black dichroic dye is added, and the examples shown in FIGS. 4 and 5 have a parallel arrangement,
In the embodiment shown in FIG. 6, a screw hole is provided. Furthermore, the transmission axes of the polarizing plate 1 in FIG. 4 and the polarizing plate 8 in FIG. Make them orthogonal. In the case of the embodiment shown in FIG. 6, the transmission axes of the polarizing plate 8 and the multicolor polarizing plate 7 are perpendicular to each other, but the transmission axis of the polarizing plate 8 is in the same direction as the orientation of the GH liquid crystal on the transparent substrate 4. shall be. The driving method is the above-mentioned TN
The same method can be used as when a type liquid crystal cell is used as a light shutter, and the same display can be obtained. However, although the contrast is somewhat lower than in the case of a TN type liquid crystal cell, the viewing angle dependence is small due to the characteristics of the GH type liquid crystal cell, and a sufficient display as a color liquid crystal display device can be obtained.

As the GH type liquid crystal, an Nff1 nematic liquid crystal may be used and vertically arranged.

Effects of the Invention As described above, according to the present invention, although the conventional method using a multicolor polarizing plate has high transmittance and enables reflective display, it has the drawbacks of low contrast, and By making it possible to display colors intermediate between the two, we were able to eliminate the disadvantage that the method using color filters had high contrast but low transmittance, requiring a backlight. Further, by adjusting the voltage applied to cell A, the brightness and saturation of the displayed color can be easily changed, and it is possible to obtain an appropriate display color depending on the brightness of the figure, for example. Furthermore, even in black and white display, by applying voltage only to cell A and displaying,
It is possible to display exactly the same as a conventional TN type liquid crystal display or GH type liquid crystal display, and it is possible to realize a reflective color liquid crystal display device or a color liquid crystal display device that requires only a low-luminance backlight.

In the example, the polarizing plate 8 is used as the FI plate between the A cell and the B cell by being sandwiched between the transparent substrates 4 and 9, but the transparent electrodes 12 and 13 may be formed directly on the polarizing plate 8. Alternatively, a polarizing film may be produced on one transparent substrate, and a transparent electrode may be produced thereon. Further, the polarizing plate 1 may be provided on the liquid crystal side of the transparent substrate 3, or it is also possible to cover the elemental plate and the multicolor polarizing plate with a thin film and fabricate the transparent electrode thereon. .

[Brief explanation of the drawing]

1 and 2 show schematic cross-sectional views of conventional color liquid crystal display devices, and FIGS. 3.4 and 5.6 show schematic cross-sectional views of embodiments of the present invention. 1.2,8°, polarizing plate, 3,4,9. io. . Transparent substrate, 5°, color filter, 6, 11, 12, 13. transparent electrode, 71. Multicolor polarizing plate, 14°. GH liquid crystal. Applicant Daini Seikosha Co., Ltd. 10- Figure 1 Figure 2 Figure 3r2J Figure 40 Funeral Figure 5 Figure 6

Claims (1)

[Claims] (1) A first liquid crystal cell having a light shutter effect;
(1) TN-type liquid crystals having multicolor polarizing plates are stacked, and the electrodes of the first liquid crystal cell and the second TN-type liquid crystal cell are arranged so as to correspond to each other. A color LCD display bag featuring (2. In the color liquid crystal display device according to claim 1, the first liquid crystal cell having a light shutter effect is
A color liquid crystal display device characterized in that it is a TN type liquid crystal cell having a pair of polarizing plates. (3) In the color liquid crystal display device according to claim 1, the first liquid crystal cell having a light shutter effect is a GI (type liquid crystal cell) having one polarizing plate.
fr, a color liquid crystal display device featuring features.