JPH02205825A - Variable light passing area type liquid crystal optical shutter - Google Patents

Abstract

PURPOSE:To obtain an image display device using liquid crystal which provides picture quality equivalent to that of a cathode-ray tube in terms of easiness to see, definition, etc., by varying the area of light passage in one picture element like the stop of a camera and making a gradational display. CONSTITUTION:Grooves are formed in a V or corrugated shape in either or both of picture element electrodes E and a common electrode in one picture element of an active TN type dot matrix liquid crystal optical shutter which uses MIM instead of TFT. Then the differences between electrodes are made different and the intensity of an electric field is varied with the place; and the area of the phase shift of liquid crystal is increased or decreased by varying an effective voltage applied between the electrodes by vary the area of light passage. Namely, when the voltage between the electrodes is varied, the TN liquid crystal shifts in phase from the place where the distance between the electrodes is short (the electric field intensity is large) to pass or cut off light, and the area of light passage varies to make the gradational display. Consequently, visual angle dependency is small, so an image is seen sharply in any direction.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to image display devices for TVs, computers, and the like.

(b) Conventional technology TFT+M currently used in small TVs and computers
An active type TN dot matrix liquid crystal optical shutter using IM uniformly changes the amount of light passing within one pixel by changing the angle at which the light is twisted111
m is displayed. As a result, the LCD has viewing angle dependence, and the contrast and brightness change depending on the viewing angle, making it never easy to see.Many efforts have been made to improve display image quality, but none are yet satisfactory. A liquid crystal display device has not been obtained.

Also, if there is even one defect in TFT or MIM, the product cannot be manufactured, so if you increase the number of pixels by 10, the yield will increase from 1 to 100.
Since it would be 1/2 the worse, mass production of 1-megapixel liquid crystal optical shutters was considered impossible to achieve at a higher interest rate.

(c) Problems to be Solved by the Invention The object of the present invention is to obtain an image display device using a liquid crystal whose image quality is comparable to that of a cathode ray tube in terms of visibility and definition.

(d) Means for solving the problem Instead of displaying gradation by changing the angle of optical rotation of light by changing the phase transition ratio of the liquid crystal between the electrodes, as with conventional TN liquid crystals, We decided to display gradations by changing the area through which light passes within a single pixel, similar to a squeezer. This is because viewing angle effects are unlikely to occur even in TN liquid crystals when the maximum amount of light passes through them.

To achieve this, by creating peaks and valleys in either or both of the pixel electrode or the common electrode within one pixel, the distance between the electrodes can be varied, and the electric field strength can vary depending on the location, even within the same pixel. By changing the effective voltage applied between the electrodes, the area where the liquid crystal undergoes phase transition can be increased or decreased.
This can be done by changing the area through which light passes and displaying gradations.Use a liquid crystal with a steep threshold characteristic.

To create peaks and valleys in the electrodes, the substrate is embossed or machined, or transparent electrodes are coated with varying thicknesses. Possible methods include applying it thickly and etching it.

Also, 1'FTJ due to ultra-high pixel count? ? MIM
To cope with the increase in the incidence of defects, it is possible to compensate for device defects by superimposing two variable area liquid crystals in which the positions of defective pixels do not overlap.

(e) When a voltage is applied between the working electrodes, a phase transition occurs in the TNfi crystal from a place where the distance between the electrodes is close (a place where the electric field strength is large), and light passes or is blocked, and the area through which light passes increases. You can display different gradations.

By adopting the structure as claimed in claim 2, it will be similar to stacking two camera apertures, and even if the two apertures work, only one will work due to a defect in the TFT or MIM. Almost the same intermediate gradation can be obtained without it.

(f) Examples Example 1 FIG. 1 is a principle diagram showing a first embodiment of claim 1.

This is a cross section of a pixel electrode in which a transparent conductive film is applied to a thickness of several microns and etched to form conical peaks.

Half of the graph shows a state where a voltage is applied that is sufficient to allow light to pass through.

FIG. 2 is a principle diagram showing a second embodiment of claim 2. TL on the glass substrate! [This is a V-shaped groove several microns deep.

It has a normally white operation mode, and when the voltage applied between the tvfi and the tvfi terminals is increased, light gradually stops passing from the ends.

The image above shows a state in which both liquid crystals are operating when a medium voltage is not applied.

Below is the case when the same voltage is applied, but the first liquid crystal does not operate and only the second liquid crystal operates, but the light is blocked almost as much as if the two liquid crystals were operated at the same time. It represents having quantity.

This allows compensation for pixel defects.

It is better to place the two overlapping liquid crystal parts as close as possible compared to the width of the pixel.

Each part of the diagram is separated to make it easier to understand. Furthermore, the proportions of the sizes of each part are exaggerated and do not represent the actual size.The dotted lines between the electrodes represent the alignment direction of liquid crystal molecules.

(G) Effects of the Invention Unlike image display devices using conventional TN liquid crystal optical shutters, the present invention has less viewing angle dependence, so it can be seen clearly from any direction, and even if the number of pixels is increased, there is no yield limit. Since there is little deterioration in image quality, a large, high-definition liquid crystal image display device can be realized.

As described above, it is possible to eliminate the drawbacks of conventional liquid crystal display devices without significantly increasing the number of man-hours, so it is possible to realize an image display device that has both the Fi[2 of a liquid crystal and the ease of viewing of a cathode ray tube. , and it is not impossible for it to replace the cathode ray tube.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are principle diagrams showing a first embodiment and a second embodiment of this invention, respectively. A - Light source C - Vertical polarizing plate E - Pixel electrode G - Incident light light shielding film B - Glass substrate Horizontal polarizing plate F - Common electrode H - Passing light

Claims (1)

[Scope of Claims] Claim 1: In an active type TN dot matrix liquid crystal optical shutter using TFT or MIM, in one pixel, there are peaks, valleys, or valleys on either or both of the pixel electrode or the common electrode. By creating V-shaped or wave-shaped grooves, the distance between the electrodes is varied to change the electric field strength depending on the location, and by changing the effective voltage applied between the electrodes, the area where the liquid crystal undergoes phase transition can be increased or decreased (variable area liquid crystal A liquid crystal optical shutter that displays gradations by changing the area through which light passes. Claim 2: A TN type variable area liquid crystal obtained in claim 1, in which three polarizing filters are stacked so that the polarization directions of the light are alternately orthogonal, and the two filters have the same electrode pattern and phase transition area change characteristics between them. In the liquid crystal optical shutter, which has a structure in which plates are aligned and sandwiched one by one, even if there is a defect in either the TFT or MIM element that drives the stacked pixels, a single sheet of defect-free dot matrix light is generated. A transmissive liquid crystal optical shutter intended to function as a shutter.