JPS6019489B2 - LCD color display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal color display device using a dichroic dye, a liquid crystal, and a dichroic mirror.

The molecular arrangement of liquid crystals is easily deformed under low electric fields, and their optical properties change.

Liquid crystal display devices that utilize this electro-optic effect and are characterized by low voltage and low power have been put into practical use. However, it is being put into practice. However, liquid crystal display devices display black and white, and color display has not yet been put to practical use. As a color display method using liquid crystals, the guest-host method is known, in which a dichroic dye is mixed into the liquid crystal, and by applying a voltage, the molecular axis of the dye is rotated to change the absorption wavelength of light, thereby producing a display. It is being The guest-host method has good viewing angle characteristics and is suitable for display devices, but the display color is determined by the dichroic dye mixed into the liquid crystal, so it has the disadvantage that it can only display the determined monochrome color. . The present invention aims to improve the above-mentioned drawbacks of monochromatic color display, and provides a liquid crystal color display device capable of displaying multiple colors.

In the present invention, two color birch dyes and liquid crystal or dichroic liquid crystal are sealed between two substrates that have been subjected to alignment treatment, and a voltage is applied between transparent electrodes formed on the substrates to optically control the liquid crystal. A device that displays information by changing properties is characterized in that a dichroic mirror is interposed between a liquid crystal enclosure and a diffused reflection plate. A detailed explanation will be given below using the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

Reference numerals 1 and 6 denote transparent substrates, which may be made of, for example, glass plates.

2 is a transparent electrode formed of, for example, indium oxide or tin oxide by vacuum evaporation, sputtering, or the like.

3 is an n-type nematic liquid crystal molecule, and 4 is a dichroic dye or a dichroic nematic liquid crystal as in the examples described later.

The long axis of the liquid crystal molecules is perpendicular to the substrate. 5 is a dichroic mirror that transmits light within a certain wavelength range and reflects light other than the transmitted wavelength.

The dichroic mirror 5 is composed of, for example, a dielectric multilayer film of magnesium fluoride and titanium oxide. 7 is a diffused reflection plate, which is made by honing brass or stainless steel to make the surface uneven, then silver-plating, and coating the surface with a transparent protective film such as lacquer.

Next, the operating principle is entrusted to the following.

When a low voltage of about 3V is applied to the liquid crystal layer, the liquid crystal molecules 3 rotate and change their molecular alignment, and the dichroic dye molecules 4 are attached to the substrate 1.
, 6, the incident light 8a is absorbed by the dichroic dye molecules 4, and after passing through the liquid crystal layer, it has a spectrum as shown in FIG. 2, so it appears light blue. That is, the absorption color resulting in this clear color depends on the type of 28-color dye molecule 4. This light reaches the dichroic mirror 5.
The dichroic mirror 5 has, for example, optical characteristics as shown in FIG.
The light shown in 14 is selectively transmitted, and the light that is not transmitted is selectively reflected according to the reflection characteristics shown by the dotted line 14. A portion of the incident light 8a is selectively reflected by the dichroic mirror 5, but there is no component in the direction of the eye 12. On the other hand, the light transmitted through the dichroic mirror 5 is transmitted according to the selective transmission characteristics of the dichroic mirror 5, and therefore has a spectrum as shown in FIG. 4, and exhibits a red color. This red light is reflected by the diffused reflection plate 7
Furthermore, because it is diffused, it has a component 9 in the direction of the eye 12, so it enters the eye 12, creating a back shadow color. When a low frequency AC or DC voltage of about 15 V is applied to the transparent electrode 2, a turbulent flow 15 is generated in the liquid crystal, and the incident light 8c is scattered in the liquid crystal. Selective reflection is performed according to the reflection characteristics 14 of the microchroic mirror 5. Moreover, since the reflected light has a directional component 10 of the eye 12 due to diffusion, it reaches the eye 12, and the reflection characteristic 14 of the dichroic mirror 5 is
It looks yellow-green. When the voltage applied to the liquid crystal layer changes the alignment, the molecular alignment is perpendicular to the substrates 1 and 6. In the case of such a molecular arrangement state 16, the vibration direction of the incident light 8b and the molecular long axis of the dichroic dye molecule 4 are perpendicular to each other, so that the dichroic dye molecule 4 does not absorb light. The incident light 8b reaches the dichroic mirror 5 without being absorbed by the liquid crystal layer, where it is partially selectively reflected, but there is no component in the direction of the eye 12. On the other hand, the light of the transmitted wavelength castle 13 in FIG.
1, light enters the eye 12, and the vertical molecular alignment state 16
In this example, the portion appears purple. As described above, in this example, the color is purple when no voltage is applied, yellow-green when a voltage of about 15V is applied, and red when a voltage of about 5V is applied, and information is displayed by using transparent electrodes with a desired pattern. can be displayed.

The color of the displayed star can be arbitrarily selected by combining the dichroic dye used and a dichroic mirror with appropriate optical characteristics. In the present invention, by using a dichroic dye and a liquid crystal together with a dichroic mirror, it is possible to display three or more colors.

Compared to the conventional single-color display using the guest-host effect, the number of display colors is three times greater, making it possible to display diverse information. In addition, since color display is performed using the absorption of dyes, unlike color display that uses voltage changes due to birefringence of liquid crystals, there is no change in the displayed color depending on the viewing angle.
It is possible to view the display from a wide angle. Therefore, according to the present invention, a high quality liquid crystal color display device is possible.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing an example of the present invention, Figure 2 is a graph showing the transmission spectrum of a dichroic dye, Figure 3 is a graph of the optical characteristics of a dichroic mirror, and Figure 4 is a reflected light spectrum. This is a graph showing. 1, 6...Transparent substrate, 2...Transparent electrode, 3...Liquid crystal molecule, 4...Dichroic dye molecule or dichroic nematic liquid crystal Molecule, 5... Dichroic mirror, 7... Diffuse reflector. Figure 1 Figure 2 Figure 3 Figure 4 Figure 4

Claims (1)

[Claims] 1 A means for applying a voltage between two aligned substrates, a dichroic dye and a liquid crystal sealed between the substrates, or a dichroic liquid crystal and a transparent electrode formed on the substrates, and In the display device, a dichroic mirror is interposed between the liquid crystal enclosure and the diffused reflection plate, and the liquid crystal and the dichroic liquid crystal are n-type and aligned perpendicularly to the substrate. , the optical state of the liquid crystal enclosing portion exhibits any of a transparent state in which the liquid crystal is almost transparent, a color absorption state in which the absorption color of the dichroic dye or the dichroic liquid crystal is absorbed, and a light scattering state in which light is scattered. A liquid crystal color display device characterized by displaying a color by: