JPH02204726A - Reflection type liquid crystal display device - Google Patents

Abstract

PURPOSE:To evade the contrast drop of a display screen by forming a reflection preventing film consisting of a substance for preventing the generation of light reflection on the rear face of a transparent insulating base on which reflecting picture element electrodes are formed. CONSTITUTION:In a reflection type liquid crystal display device holding a liquid crystal layer 16 between two opposed glass bases 11, 18, the reflection preventing film 19 consisting of a substance, e.g. magnesium florine (MgF2), for preventing light reflection is formed on the rear face of the glass base 11 on which the reflecting picture element electrodes 15, TFTs auxiliary capacitors 13, and wiring electrodes 12 are formed. Light entering from the side of the liquid crystal 16 through a gap between the electrodes 15 is transmitted into the glass base 11 due to the existence of the film 19. Thereby, the generation of leaked current due to the optical conduction of the TFTs to be switching elements and the auxiliary capacitors 13 can be prevented and the reflection type liquid crystal display device excellent in contrast can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a reflective liquid crystal display device having an active element used in a projection display device.

2. Description of the Related Art In recent years, liquid crystal display devices using active elements have come to be used as pocket televisions or information terminals.

A conventional reflective liquid crystal display device will be explained below.

FIG. 2 is a cross-sectional view of a conventional reflective liquid crystal display device, where I is a transparent insulating substrate, 2 is a wiring electrode, 3 is a switching element, 4 is an insulator layer, 5 is a reflective pixel electrode, 6 is a liquid crystal layer,
7 is a counter common electrode, and 8 is a counter transparent substrate.

The operation of the reflective liquid crystal display device configured as described above will be described below.

First, when the switching element 3 is turned on, a current flows through the reflective pixel electrode 5. As a result, a voltage is applied to the liquid crystal layer 6 sandwiched between the reflective pixel electrode 5 and the opposing common electrode 7.
LCD works. At this time, light for making the display easier to see is emitted from the opposite transparent electrode side, and the incident light is reflected by the reflective pixel electrode 5. Here, the light is polarized when passing through the liquid crystal layer 6, and is not polarized. A difference in contrast occurs between the pixels, and an image is obtained.

Problems to be Solved by the Invention However, in the above conventional configuration, light passes from the liquid crystal layer side through the insulating layer between the reflective electrodes and the insulating substrate, is reflected at the interface A between the insulating substrate and the external atmosphere, and is re-injected into the TPT. enter in. FIG. 3 is an explanatory diagram of the entrance path of light. Therefore, light acts on the switching element, reducing the electrical resistance of the semiconductor layer that constitutes the switching element (photoconduction).

This has the disadvantage that the charge stored in the pixel electrode and the opposing common electrode leaks through the switching element, resulting in a change in the orientation of the liquid crystal, resulting in a decrease in contrast.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reflective liquid crystal display device that solves the above-mentioned conventional problems and can eliminate the decrease in contrast of a display screen.

Means for Solving the Problems To achieve this object, the reflective liquid crystal display device of the present invention comprises an anti-reflection film made of a substance with a high light transmission coefficient provided on the back surface of a transparent insulating substrate provided with switching elements. It is configured.

Effect: With this configuration, light entering the array from the insulating layer between the reflective electrodes is not reflected at the interface between the transparent insulating substrate and the external atmosphere, but is transmitted to the external atmosphere.

Therefore, leakage current caused by photoconduction of the switching element can be prevented.

EXAMPLE Hereinafter, a reflective liquid crystal display device according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a cross-sectional structure of a reflective liquid crystal display device according to an embodiment of the present invention. In Figure 1, 1
) is a glass substrate as a transparent insulating substrate, 12 is a wiring electrode,
13 is a TPT and an auxiliary capacitor as a switching element;
14 is an amorphous silicon nitride film as an insulator layer, 15 is a reflective pixel electrode, 16 is a liquid crystal layer, 17 is a counter common electrode,
It is an ITO film formed by sputtering, I8 is a glass substrate as a counter transparent substrate, and 19 is a magnesium fluoride (hereinafter referred to as MgF2) film layer formed by electron beam evaporation.

Further, an auxiliary capacitor is formed on the wiring electrode 12.

The operation of the reflective liquid crystal display device configured as described above is similar to that of the conventional example.

As described above, according to this embodiment, M is provided on the back surface of the glass substrate.
By providing the gF2 layer, light that enters from the gap between the reflective pixel electrodes passes through the amorphous silicon nitride film and enters the inside of the glass substrate. It is possible to prevent light from passing into the atmosphere, that is, from re-entering the inside of the TFT, and to prevent leakage current due to photoconduction in the switching element.

Effects of the Invention As described above, the present invention provides a reflective liquid crystal display device in which an antireflection film made of a substance for preventing light reflection is formed on the back surface of a transparent insulating substrate on which reflective pixel electrodes are formed. , light entering the array from the liquid crystal layer side through the insulating layer is not reflected at the interface between the insulating substrate and the outside atmosphere, but is transmitted to the outside of the insulating substrate, and therefore the switching element is activated by photoconduction. Leakage current due to a decrease in resistance can be prevented, and a reflective liquid crystal display device with excellent contrast can be realized.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a reflective liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a conventional reflective liquid crystal display device, and FIG. 3 is a cross-sectional view of a conventional reflective liquid crystal display device. It is an explanatory diagram about a route. 1)...Glass substrate, 12...Wiring electrode, 13...TFT, 14...Amorphous silicon nitride film layer, 15... ...Reflective pixel electrode, 16
...Liquid crystal layer, 17...Counter common electrode,
18...Counter glass substrate, 19...M
gF2 membrane layer. Name of agent: Patent attorney Shigetaka Awano 1 person Figure 1: 1) - Ichino Lass =- Momme crystal bottle IT-1 chou 0 size

Claims (4)

[Claims] (1) A transparent substrate equipped with a group of reflective pixel electrodes arranged in a matrix for displaying liquid crystal, and a group of switching elements for supplying signals to the pixel electrodes, and a transparent substrate arranged at a constant interval through the liquid crystal. facing the substrate,
a transparent substrate having a common electrode, and an antireflection film made of a substance for preventing light reflection on the back surface of the transparent insulating substrate on which the reflective pixel electrode is formed. A reflective liquid crystal display device featuring: (2) The reflective liquid crystal display device according to claim (1), wherein the switching element is formed of a thin film transistor, a diode, or a nonlinear switching element. (3) The reflective liquid crystal display device according to claim (2), wherein a plurality of switching elements are formed in each pixel. (4) The reflective liquid crystal display device according to claim (1), wherein an auxiliary capacitor is formed in each display pixel of the reflective pixel electrode group.