JPH04178625A - Reflection type liquid crystal electrooptical device - Google Patents

Abstract

PURPOSE:To obtain the reflection type liquid crystal electrooptical device having high performance by providing a dielectric mirror between electrodes existing on a high-reflectivity side and a liquid crystal. CONSTITUTION:The light entering from the side of a glass substrate 102 is reflected by the dielectric mirror 107 and is emitted from the side of the glass substrate 102 by tracing the optical path reverse from the incident optical path. The polarization state of the light is changed by the liquid crystal 105 controlled in orientation by the impressed voltage during this time. The orientation of the liquid crystal molecules is changed by the electric field generated between the matrix electrodes 108 and a counter electrode 103 when the voltage is impressed to the matrix electrodes and the polarizing state of the exit light is changed. While a protective film is heretofore required in order to prevent an electrochemical reaction in the case of use of aluminum for the electrodes 108, the need for this protective film is eliminated by disposing the dielectric mirror. The homogeneous display state is obtd. in the state of not impressing the voltage by the disposition of the seamless dielectric mirror. The higher- quality display with the lessened joints is obtd. when the voltage is impressed.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a reflective liquid crystal electro-optical device.

[Prior Art] A conventional reflective liquid crystal electro-optical device is as described in Nikkei Electronics (1981) February 16 issue, p. 164.
The liquid crystal drive electrode was used as a reflective surface.

[Problems and Objectives to be Solved by the Invention] However, in conventional reflective liquid crystal electro-optical devices, it is necessary to use a material with high reflectivity for the liquid crystal drive electrode used for the reflective surface, so there are limited materials that can be used for the electrode. limited (aluminum and silver);
There was a problem in that there were large restrictions on device design. The present invention is intended to solve these problems, and its purpose is to provide a high-performance reflective liquid crystal electro-optical device.

[Means for Solving the Problems] A reflective liquid crystal electro-optical device of the present invention is characterized in that a dielectric mirror is provided between an electrode on the side with a higher reflectance and a liquid crystal.

[Example] Hereinafter, the details of the present invention will be shown by examples.

FIG. 1 shows the configuration of a reflective liquid crystal electro-optical device of the present invention. This is an application of the present invention to a TN (twisted nematic) mode active matrix reflective liquid crystal display device.

A transistor-type active collector 111 and a matrix electrode 108 were formed on a silicon substrate 110 and filled with an insulating material 109, and then the surface was etched to obtain a flat surface. A dielectric mirror 107 was deposited and formed thereon.

Next, diagonal vapor deposition was performed on the surface of the dielectric mirror 107 to form an orientation surface 106. Further, a liquid crystal 105 was sealed between the dielectric mirror 107 having the alignment surface 106 and the glass substrate 102 on which the transparent counter electrode 103 was formed. Further, a polarizing plate 101 was arranged outside the glass substrate 102.

Here, the display principle of this device will be explained.

The light incident from the glass substrate 102 side is reflected by the dielectric mirror 107, follows the optical path in the opposite direction to that of the incident light, and exits from the glass substrate 102 side.

During this time, the liquid crystal 10 whose alignment is controlled by the applied voltage
5 changes the polarization state of the light. When a voltage is applied to the matrix electrode 108, the orientation of the liquid crystal molecules changes due to the electric field generated between the matrix electrode 108 and the counter electrode 103, thereby changing the polarization state of the emitted light.

In this example, aluminum was used for the matrix electrode 108. 59 cases that use aluminum for electrodes conventionally required a protective film to prevent electrochemical reactions, but now a dielectric mirror has been placed.

There is no longer a need for that.

Furthermore, by arranging seamless dielectric mirrors, a homogeneous display state can be obtained even when no voltage is applied, and even when a voltage is applied, a high-quality display with fewer seams than before can be obtained.

The second embodiment also has exactly the same configuration as FIG. 1. However, chromium was used for the matrix electrode 108. The electrochemical stability of the electrode was improved because chromium, which could not be used in the past due to its low reflectance, was used for the electrode.

The dielectric mirrors in the above two embodiments are formed by stacking 5 in 2 and amorphous silicon thin films alternately by electron beam evaporation, and have a reflectance of 90% or more at the center wavelength.

The oblique evaporation method used to align the liquid crystal aligns the liquid crystal using crystals grown obliquely to the normal direction of the substrate. In this example, during oblique vapor deposition, the substrate was set at an angle of 85 degrees with respect to the normal direction of the substrate, and SiO2 was vapor deposited.

Note that it is also possible to align the liquid crystal molecules by a rubbing method after applying an alignment film on the dielectric mirror. At this time, the dielectric mirror is designed taking into consideration the thickness and refractive index of the alignment film so that the reflectance does not decrease.

Although the embodiments of the present invention have been described above, the present invention can be widely applied to other applications such as liquid crystal display devices and liquid crystal spatial modulators.

[Effects of invention According to the present invention, the following effects can be obtained.

(2) By using a dielectric mirror formed on the liquid crystal drive electrode as a reflector, there is no need to consider the reflectance of the liquid crystal drive electrode. Therefore, a wide variety of materials can be used for the electrodes, increasing the degree of freedom in device design.

(M) Since it acts as a protective film for the dielectric mirror electrode, materials with low electrochemical stability can be used for the electrode, increasing the degree of freedom in device design.

■By arranging seamless dielectric mirrors, a homogeneous display can be obtained when no voltage is applied to the electrodes, and even when voltage is applied, a high-quality display with fewer seams than before can be obtained.

■Since there is a reflective film on the liquid crystal drive electrode, no special treatment such as light shielding is required in the gap between the electrodes.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a reflective liquid crystal electro-optical device of the present invention. FIG. 2 is a sectional view showing the configuration of a conventional reflective liquid crystal electro-optical device. 101 ... polarizing plate 102 ... glass substrate 103 ... counter electrode 104 ... alignment film 105 ... liquid crystal 106 ... alignment surface 107 ... dielectric mirror] 08 ... matrix electrode 109 ... Insulating material 11,0 ... Silicon substrate 111 ... Active element 112 ... 5i02 201 ... Alignment film 202 ... Protective film 203 ... Aluminum electrode and above Applicant Seiko Epson Corporation Agent Patent Attorney Kizobe Suzuki (f!'!! 1 person)'+2
SrQ, Figure 1, Bottom of Figure 2

Claims (1)

[Claims] Regarding a reflective liquid crystal electro-optical device having a liquid crystal sandwiched between a high transmittance substrate and a high reflectance substrate, and a plurality of separated electrodes on at least one side, the electrode on the high reflectance substrate side and the liquid crystal A reflective liquid crystal electro-optical device comprising: a dielectric mirror;