JPS62204230A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain a transparent liquid crystal display device excellent in display quality under high time division driving by using a polarizing plate having polarizing characteristics only for light in a specific wavelength area for one polarizing plate out of plural ones. CONSTITUTION:Nematic liquid crystal having positive dielectric anisotropy and added by the prescribed quantity of a optical rotation substance is held between a pair of upper and lower electrode bases 11a, 11b opposed to each each other and spiral structure 15 twisted within the range of 180-270 deg. in the thickness direction is formed. The other pair of polarizing plates 18a, 18b having transmitting axes or absorbing axes shifted from the liquid crystal molecule array directions 16a, 16b of the upper and lower electrode bases 11a, 11b by the angles within the range of 30-60 deg. are arranged on the outsides of the bases 11a, 11b and the product n.d of the thickness d (mum) of the liquid crystal layer 14 and the refractive index anisotropy n of the liquid crystal is set up to the range of 0.7-1.2mum. Since the polarizing plates 18a, 18b having polarizing characteristics only for the light included in the specific wavelength range are used for one polarizing plates, excellent display characteristics can be obtained under high time-division driving, and since the background is not colored, visibility can be sharply improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device, and particularly to a large-sized liquid crystal device used in personal computers, word processors, and the like.

[Summary of the invention]

In the present invention, a nematic liquid crystal having positive dielectric anisotropy and added with a predetermined amount of optically active substance, which is used as a large display terminal device, is sandwiched between a pair of upper and lower electrode substrates arranged oppositely, and the thickness of the nematic liquid crystal is A twisted helical structure is formed in the range of 180 degrees to 270 degrees in the direction, and the transmission axis or absorption axis is shifted by an angle in the range of 30 degrees to 60 degrees in the direction in which the liquid crystal molecules of the pair of upper and lower electrode substrates are aligned. A liquid crystal display in which a pair of polarizing plates with a polarizing plate is provided on the outside of an electrode substrate, and the product Δn-d of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn of the liquid crystal is in the range of 0.7 μm to 1.2 μm. In the device, by using a polarizing plate that has polarization characteristics only for light in a specific wavelength range as one of the polarizing plates, display characteristics are good under high time division driving, and visibility is improved because the background is not colored. [Prior art] In recent years, with the increase in the amount of displayed information, so-called don-matrix display devices, in which electrodes are arranged in an x-y matrix, have been developed. Liquid crystal display devices are attracting attention as thin, lightweight, and compact display terminals.

Twisted nematic liquid crystal display devices with a 90° helical structure as shown in Figure 5 have poor time division characteristics because the change in light transmittance (reflectance) with respect to the voltage applied to the liquid crystal molecules is not steep. It has serious drawbacks as a large display terminal device, such as poor contrast and narrow viewing angle due to crosstalk.

Recently, as shown in FIG.
A pair of transparent electrode substrates 61a and 61b are arranged facing each other so as to form a large spiral structure of 80 degrees to 270 degrees.
The transmission or absorption axes of the polarizing plates 64a and 64b provided on the outside of the pair of electrode substrates are held at an angle of 30 degrees to 60 degrees with respect to the liquid crystal molecule alignment directions 63a and 63b near the interface. The product Δn of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn of the liquid crystal
The field-controlled birefringence effect (R,^, 5oref
and M, J, Rafuse.

J, Appl, Phys, 43.2029 (19
It has been confirmed that a liquid crystal display device (NevTN display device) to which 72)) is applied has significantly superior display characteristics to the conventional 90-degree TN display device, and its application to large-capacity liquid crystal display devices is expected. .

[Problem that the invention seeks to solve]

Figure 7 shows NewT that applies the electric field controlled birefringence effect.
3 shows the relationship between the light transmittance and the wavelength of incident light of the N display device. As we will see, the background of the NewTN display device is colored yellow or green, so although the display contrast is good, it is not widely accepted by the general public due to design limitations and taste issues when used as a display. The drawback was that it was not possible to enter.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention uses one of the polarizing plates used as a polarizing plate that has polarizing properties only for light in a specific wavelength range, so that it can be used in a colored display device such as a 90 degree TN display device. Ne with no neutral gray hue
It has become possible to use it as a wTN display device.

〔Example〕

Embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a liquid crystal display device according to the present invention, in which a pair of upper and lower transparent substrates 11a and 11b are arranged at a constant interval, transparent electrodes 12a and 12b are provided on the substrates, and the surface is coated with printing, dipping, etc. An insulating thin film of polyimide, Teflon, or the like is formed by vapor deposition or the like, and uniaxially oriented films 13a and 13b are provided in one direction by rubbing or the like.

A liquid crystal layer 14 to which a certain amount of Merck's 3811 as an optically active substance is added is sealed in the gap between the substrates 11a and llb, forming a helical structure twisted approximately 200 degrees in the thickness direction. The product Δn-d of the thickness d (μm) and the refractive index anisotropy Δn of the liquid crystal is 0.7 μm to 1.2 μm
It is configured to be within the range of A pair of polarizing plates 18a and 18b are installed on the outside of the two upper and lower substrates so that the angle between the transmission axis or absorption axis and the liquid crystal molecule alignment directions 16a and 16b is 45 degrees.
8a has polarization characteristics only for light in the wavelength range of approximately 500 nm to 600 nm.

FIG. 2 is a view of the liquid crystal display device of FIG. 1 viewed from above, and the rubbing direction of the upper substrate and the lower substrate is 21a,
21b, and the transmission or absorption axes of the polarizing plates in contact with the upper and lower substrates are 22a and 22b. 23 is the twist and rotation angle of the liquid crystal molecules, which has a value of about 200 degrees, and 24 is the angle formed by the transmission axis or absorption axis of the polarizing plate and the alignment direction of the liquid crystal molecules, which has a value of about 45 degrees.

FIG. 3 shows the relationship between the wavelength of incident light and the intensity of transmitted light in the liquid crystal display device according to the present invention.

The measuring device used was Canon LC-3P model.

As for the polarizing plate, the polarizer is manufactured by Royal Electric LLC LLC2-82-1.
83, and the analyzer is 5CC21"l manufactured by Sanritsu Electric.
8S was used.

5CC2P-183 has the spectral characteristics shown in FIG. 4, and exhibits polarization characteristics only for light having a wavelength in the range of approximately 500 nm to 600 nm.

Now, as shown in FIG. 3, the amount of light transmission does not depend much on the wavelength of incident light and has a fairly flat spectral characteristic, and the liquid crystal display device according to the present invention does not have a specific color. The display quality has been significantly improved due to the neutral gray color.

In addition, when the display contrast of this liquid crystal display device was measured, it was 1:6.1 when driven with 100 divisions, and 1:4.2 when driven with 200 divisions, showing that the visibility characteristics were greatly improved and
Practical use has become possible even with split drive.

In the example shown in Fig. 3, 5CC2P-183 was used as the analyzer, but even if 5CC2P-18 was used as the polarizer and LLC2-82-183 as the analyzer, almost the same results could be obtained. Obtained.

〔Effect of the invention〕

As described above, by using the present invention, it is possible to obtain a transparent liquid crystal display device with extremely excellent display quality under high time division driving.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional perspective view showing the structure of a liquid crystal display device of the present invention, and FIG. 2 is a structure showing the relationship between the alignment direction of liquid crystal molecules and the direction of the transmission axis or absorption axis of the polarizing plate of the liquid crystal display device of the present invention. Figure 3 shows the relationship between the light transmittance and the incident light wavelength of the liquid crystal display device of the present invention. Figure 4 shows the polarizing plate 5CC2P-1BS.
FIG. 5 is a perspective view showing the configuration of a 90 degree TN display device in the prior art, and FIG. 6 is a cross-sectional perspective view of a New TN display device in the prior art. , Figure 7 shows the New in the prior art.
FIG. 2 is a diagram showing the relationship between light transmittance and incident light wavelength of a TN display device. 14...Liquid crystal molecules 15...Twisted spiral structure 16a, 16b...Liquid crystal molecule alignment direction 22a, 22b
... Axial direction of the polarizing plate 23 ... Twisted helical angle of the liquid crystal 24 ... The angle formed by the liquid crystal molecular alignment direction and the axial direction of the polarizing plate Applicant: Seiko Electronic Industries Co., Ltd. Mohozu suitability chart? 711!1 jf220 liquid cruel tongue tongue self? 1-way polarization, axial direction, 2-wavelength (nm) 5-skin length (rtm) 4-Figure
XJ A
+ Infarct Diagram 6

Claims (1)

[Claims] A nematic liquid crystal having positive dielectric anisotropy and doped with a predetermined amount of optically active substance is sandwiched between a pair of upper and lower electrode substrates arranged opposite each other, and is twisted in the thickness direction in the range of 180 degrees to 270 degrees. A pair of polarizing plates forming a helical structure and having transmission or absorption axes shifted by an angle in the range of 30 degrees to 60 degrees in the liquid crystal molecule alignment direction of the pair of upper and lower electrode substrates are attached to the outside of the electrode substrates. and the thickness d of the liquid crystal layer
(μm) and the refractive index anisotropy Δn of the liquid crystal, the product Δn・d is 0.
1. A liquid crystal display device having a wavelength in the range of 7 μm to 1.2 μm, characterized in that one of the polarizing plates is a polarizing plate having polarization characteristics only for light in a specific wavelength range.