JPH03171117A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To lower the dependency of a contrast on visual fields and the degree of polarization of a display and to improve visibility by providing a diffuser in contact with outer side of an exit light side polarizer. CONSTITUTION:The diffuser 6 is provided in contact with the outer side of the exit light side polarizer 5 of the liquid crystal display element with transmission illumination disposed with the liquid crystal 3 of the optically rotatory power changing with light by a voltage between a pair of the polarizers 2 and 5. The transmission illumination light is projected through the polarizer 2, the liquid crystal 3 and the polarizer 5 to the diffuser 6. The diffuser 6 acts to scatter the polarized light from the exit side polarizer 5 to the light approximate nearly to natural light and to lessen the dependency on visual field angles by isotropic scattering. Thus, the dependency of the contrast on the visual field angles and the degree of polarization of the display are lowered and, therefore, the visibility is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to display elements for small electronic devices such as watches and calculators, and measuring instruments. Character/graphic display devices for OA equipment, etc. It relates to liquid crystal display elements used as in-vehicle display devices such as cars and airplanes, or image display devices such as small televisions.

[Conventional technology]

Conventional. The most popular type of liquid crystal display element is one using a liquid crystal whose optical rotation with respect to light is changed by WEE, such as a twisted nematic type liquid crystal (hereinafter referred to as TN type liquid crystal).

[Problem to be solved by the invention]

Those using conventional TN type liquid crystal [j? In this case, the optical rotation power of light differs depending on the incident and exit angles of the incident light and outgoing light in the line of sight direction, so the dependence of the contrast on the viewing angle is large. In addition, there is a problem in that when the polarized light is passed through elements such as sunglasses, Fi/L/Yuichi, etc., the direction of polarization interferes with the reading of the display. This viewing angle dependence can be improved to some extent by using a liquid crystal display element with transmitted illumination, but it is not sufficient.

The present invention was made in view of these problems. The purpose of this is to provide a liquid crystal display device in which the dependence of the contrast on the viewing field is small and the display Q and polarization degree O are small. In order to achieve this, the liquid crystal display element with the vc button of the present invention uses a polarizer on the outgoing light side of a liquid crystal display element with transmitted illumination, in which a liquid crystal whose optical rotation for light changes depending on voltage is placed between a pair of @photons. (A diffuser metal is provided on the outside of the light source in contact with the VC.) The above-mentioned di7 user has a large loss of energy μ because the emitted light (transmitted light) is divided into scattered light7.For this reason, transmitted illumination is -yt
I7) High brightness is required, and penumbra blur occurs because transmitted illumination light is generally not parallel light, but this can be solved by placing the liquid crystal, polarizer (photon dust), and diffuser close together. can be prevented.

In order to obtain a sharp image (display), the transmitted illumination can be made into a laser and parallel light is incident. It is also possible to use a Q light source other than light. For example, a mercury lamp can be used as the transmitted illumination light, and an ultraviolet light cutting filter (glass) coated with a phosphor can be used as a diffuser.

[Function] The transmitted illumination light is a polarizer and a liquid crystal. The diffuser passes through a polarizer (analyzer) and is projected onto a diffuser. It also works to reduce viewing angle dependence.

〔Example〕

When explaining the embodiment with reference to the drawings, Fig. 1 shows k.
Stay. The light emitted from the high-intensity transmitted illumination light source 1 is. The light passes through two polarizers, is converted into linearly polarized light, and enters the TN liquid crystal 3. For example, in the TN type liquid crystal 3, if the twist angle of the liquid crystal layer is 90°, when a voltage is applied between the t-poles 4,
In this case, the alignment direction of the liquid crystal molecules is such that the long axis of the molecules is almost parallel to the direction of the electric field. On the other hand, in the case of no electric field, the incident light is rotated along the three liquid crystal layers by its polarization plane gold 90' (rotation of light, therefore, polarizer 5l7) @ the direction of light is the same as the direction of polarization of polarizer 2. When it comes to 10,000 directions. [Polarizer 2 for Coining Mi#
The light that has passed remains linearly polarized and passes through the polarizer 5 all the way through. ``j, that is, it becomes a bright state.On the other hand, when no voltage is applied, the light passing through the polarizer 2 has its polarization plane rotated by 90 degrees, and as a result, the polarization direction of the polarizer 5 is perpendicular to this, so Light cannot pass through the polarizer 5, i.e.
Light is blocked and it becomes dark. This bright/dark 0 pattern is used as display information.

The light passing through the polarizer 5 is projected onto a diffuser 6, and the information on the diffuser 6 is scattered in a state almost similar to natural light. Assuming that the light from the diffuser 6 is almost completely scattered light, it follows Rann/Haert's law of cosines, so the viewing angle dependence of the contrast is not steep, and it is possible to display images that are independent of the viewing position. Become. Furthermore, since it is close to natural light, the displayed information can be read even through devices with G4 light characteristics (such as polarized sunglasses).

〔Effect of the invention〕

As explained above, the present invention is configured in the 7t'), and the viewing angle dependence of the contrast and the degree of polarization of the display are small, so visibility is improved. For a wide range of applications such as in-vehicle display devices. Moreover, it can be suitably provided, and a wide range of light sources such as lasers and ultraviolet light sources can be used as the light source for the 2fc transmitted illumination light.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the liquid crystal display element of the present invention. 1... Transmitted illumination light source 2, 5... Polarizer 3...
・TN type liquid crystal 4.4... Electrode 6... Diffuser

Claims (1)

[Claims] A liquid crystal display element with transmitted illumination in which a liquid crystal whose optical rotation for light changes depending on a voltage is arranged between a pair of polarizers, characterized in that a diffuser is provided in contact with the outside of the polarizer on the output light side. display element.