JPH02294685A - Electrooptical device for projection - Google Patents

Abstract

PURPOSE:To obtain an electrooptical device for projection without flicker in display by using a device in a memory mode as the electrooptical device for projection. CONSTITUTION:The liquid crystal electrooptical device 102 for projection in a hysterisis type SBE mode whose number of picture elements is 1,120X750 is driven in the memory mode in which rewrite is not performed as long as the content is not changed after performing write. In the case of driving the electrooptical device 102 in the memory mode, scanning is not performed as long as the content of display is not changed. Whatever projecting device 101 is used, the electrooptical device 102 in which the lowering of display quality caused by the flicker does not occur is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electro-optical device, particularly an electro-optical device for projection.

[Conventional technology]

Currently, electro-optical devices for projection using an STN mode have been put into practical use and are commercially available.

[Problem to be solved by the invention]

However, in conventional electro-optical devices using STN mode, it is extremely difficult to increase the number of scanning signal lines to 5 to 600 or more due to electro-optic performance limitations such as mode-dependent contrast ratio. .

Furthermore, if an active matrix method is used in which the number of scanning signal lines can be increased, the electro-optical device becomes extremely expensive.

Generally, in a driving method that does not use a memory mode in an electro-optical device, driving is performed by repeatedly performing scanning. At this time, if the projection light source changes its brightness regularly depending on the frequency of the commercial AC, the discrepancy between the frequency of the brightness change and the scanning frequency will cause beats (display flickering), making the display difficult to see. .

In order to solve the above problems, it is an object of the present invention to provide an electro-optical device for projection that does not display flickering by using a memory mode electro-optical device for projection. Furthermore, it is also possible to provide an electro-optical device for projection in which display performance does not deteriorate even when the number of scanning lines is increased.

[Means to solve the problem]

The electro-optical device for projection according to the present invention is characterized in that: (1) it uses a memory mode electro-optical device;

(2) A hysteresis type SBE mode liquid crystal electro-optical device is used as the memory mode electro-optical device.

(3) A chiral smectic C-mode liquid crystal electro-optical device is used as the memory-mode electro-optical device.

〔Example〕

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

(Example 1) A 9-inch hysteresis type SBE mode liquid crystal electro-optical device with a pixel count of 1120 x 750 was prototyped. After writing, this liquid crystal electro-optical device is driven in a memory mode in which rewriting is not performed unless there is a change in the content, and it is used, for example, as an electro-optical device for projection as shown in the concept in Figure 1. I tried it.

When used as a projection electro-optical device for a conventional liquid crystal electro-optical device using STN mode, the light intensity of the light source changes periodically due to regional differences in the frequency of commercial power, which causes flickering due to beats. It is necessary to adjust the scanning frequency so that it does not occur. Further, even when the adjustment is made, some flickering will occur unless the power source for the light source is completely DC. Using a power source that provides complete direct current would make the device expensive and impractical.

Furthermore, in a conventional liquid crystal electro-optical device for projection using the STN mode, when the number of scanning lines exceeds 5 to 600, the contrast decreases and the display becomes difficult to see. In addition, the response speed is extremely low, taking several hundred milliseconds or more.

On the other hand, the hysteresis type S prototyped in this example
When a BE mode liquid crystal electro-optical device is driven in memory mode, scanning is not performed unless there is a change in the displayed content, so no matter what kind of projection device is used, there will be no deterioration in display quality due to flickering etc. Does not occur. Furthermore, since the display contents are written sequentially, it is sufficiently practical even if the response speed to writing is not extremely fast. moreover,
No matter how much the number of scanning lines is increased, display performance such as contrast does not deteriorate, and there is no limit to the number of scanning lines in principle. For hysteresis type SBE mode, please refer to J, App.
l. Phys. , 59, 3087. '86 provides a basic explanation.

When the electro-optical projection device with a resolution of 1120 x 750 prototyped in this example is used in combination with a projection device,
Compared to the case using a conventional electro-optical projection device, the display was very clear, had high quality, and had high definition.

(Example 2) Chiral Smectic C with a pixel count of 1120 (X3)X750 and a built-in color filter for the three primary colors of RGB
We prototyped a mode electro-optical device and used it as a projection electro-optical device. It was confirmed that the chiral smectic C mode can be used in exactly the same way as the memory type electro-optical device using the hysteresis type SBE mode used in Example 1, except that no holding voltage is required for holding after writing.

Although the embodiments have been described above, the present invention is not limited to the above embodiments, and can be applied to other types of projection devices. For example, even if the number of scanning lines is 1000 or more, a sufficiently practical electro-optical device for projection can be obtained.

It was also confirmed that similar effects can be obtained using other memory mode liquid crystal electro-optical devices such as cholesteric-nematic phase transition, and memory mode electro-optical devices other than liquid crystal such as electrochromic.

〔Effect of the invention〕

As described above, according to the present invention, by using a memory mode electro-optical device for projection, it is possible to provide an electro-optical device for projection that does not display flickering. Furthermore, it is possible to provide a device in which display performance does not deteriorate even when the number of scanning lines is increased.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the concept of the usage state of the electro-optical device for projection according to the present invention. 101 φ 102・ ・ 103 Dispute φ ・Projection device, electro-optical device for projection, data control device Applicant: Seiko Epson Corporation

Claims (3)

[Claims] (1) An electro-optical device for projection characterized by using a memory mode electro-optical device. (2) The electro-optical device for projection according to claim 1, wherein a hysteresis type SBE mode liquid crystal electro-optical device is used as the memory mode electro-optical device. (3) The electro-optical device for projection according to claim 1, wherein a chiral smectic C-mode liquid crystal electro-optical device is used as the memory mode electro-optical device.