JPS60213924A - Electrooptical light valve - Google Patents

Abstract

PURPOSE:To attain display having fine contrast even if multiplex driving having high multiplexed degree is executed by forming specific parmanent magnet thin films on the surface of at least one substrate out of a pair of substrates forming transparent electrodes on their opposed surfaces and orienting and sealing prescribed liquid crystals. CONSTITUTION:The Nd-Fe-B group parmanent magnet thin films 1 are formed like a matrix on the surface of at least one substrate out of a pair of glass substrates forming the ITO transparent electrodes 2 on their opposed surfaces by a sputtering method. The liquid crystal having positive permittivity anisotropy and positive susceptibility anisotropy is oriented and sealed between the substrates so that its molecular long axes form 45 deg. with a magnetic field and rotate by 90 deg. between the substrates to execute multiplex driving. Thus, display having fine contrast is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an electro-optic light valve, and more particularly to a liquid crystal electro-optic light valve.

[Prior art]

Electro-optical light valves using liquid crystals are widely used as display elements in watches, calculators, measuring instruments, etc., and have recently been used in applications such as botapure computer viewers, office automation equipment (0, Aa devices), and televisions. It has come to be used as a video display instead of cathode ray tube (CRT). These applications are possible because liquid crystal displays can be driven with low power consumption and have the advantage of being thinner than CRTI/c. Video displays for computers, OA equipment, televisions, etc. require a large number of pixels, but in the conventional method of liquid crystal multiplex driving, in which the intersection of two X electrodes is used as a pixel, the number of pixels, i.e. This has the problem that as the number of electrodes increases, the display contrast decreases, making it impossible to obtain a good display. Quantitatively, when ideal driving is performed with a multiplicity N, the ratio of the voltage van applied to a lit pixel to the voltage Voff applied to a non-light pixel is as follows, and as the multiplicity N increases, Therefore, the voltage ratio becomes smaller.

In other words, the contrast is reduced.

In order to prevent the decrease in contrast (crosstalk effect) that accompanies this increase in multiplicity, conventional techniques have been used to improve liquid crystals by sharpening the rise steepness of the electro-optical characteristics. Ratio of elastic constants K
This is accomplished by improving the properties of the liquid crystal material itself, including reducing ss/K tt. On the other hand, in the active matrix method in which a switching element is arranged for each pixel and driven independently, the display contrast is independent of the number of pixels, so the number of pixels can theoretically be increased as desired.

Currently, the liquid crystal matrix published for televisions is a simple matrix of 122 x 148. 12 in double matrix
0X160. The active matrix is up to 240x240. At present, TVs require a minimum of 525 horizontal lines, but we have only achieved a fraction of that. It seems quite difficult to achieve this with simple matrix driving due to the limitation on the number of divisions. In addition, in the active matrix method, 5
What used to be 7600 transistors is now 500x50
In order to achieve a 0 display, the scale of transistors will be dramatically increased, and the number of intersections between X lines and Y lines will also increase, increasing the probability of short circuits and disconnections, and increasing the size of the panel. Accordingly, there is also a problem in the uniformity of transistor characteristics. A breakthrough is also required in terms of connection between the panel and peripheral circuits.

〔the purpose〕

The present invention solves the problems of the conventional liquid crystal light pulp described above, and its purpose is to realize a liquid crystal light pulp that can be displayed with good contrast even when multiplex driving with a high degree of multiplication is performed. It is to be.

〔overview〕

The electro-optic light pulp of the present invention is provided on at least one substrate surface of a pair of substrates on which transparent electrodes are formed on opposing surfaces.
A Nd-F, B-based permanent magnet thin film having in-plane magnetization is formed, and a liquid crystal having a positive dielectric constant anisotropy and a positive magnetic susceptibility anisotropy is oriented and sealed.

In general, liquid crystal molecules have anisotropy in magnetic susceptibility, and in a magnetic field, liquid crystal molecules receive magnetic torque and tend to align their long axes in a direction parallel to the magnetic field. On the other hand, Hd-F6-B alloys have extremely excellent properties as permanent magnet materials when their saturation magnetization is large, and these properties are also observed in thin films.

The present invention applies the above properties of liquid crystal to the improvement of the electro-optical properties of light pulp using a Hd-F, -B permanent magnet thin film as a magnetic field generation source.

〔Example〕

Hereinafter, the present invention will be described in detail based on Examples. Thin film magnets were fabricated on glass substrates by sputtering. Using a sputtering target with the composition of each sample, the supplied power was 200.
~400W, using argon gas as sputtering gas, 2
Under the pressure of X l (J mtorr, the substrate temperature
After RF-sputtering under 200°C condition, 200~4
Samples were prepared by heat treatment at 00°C. The film thickness of each sample is 8 μm. Table 1 shows the magnetic properties and compositional formula of each sample measured with the moving sample magnetometer.

Table 1, FIG. 1 is a plan view of a substrate used on at least one side of a pair of substrates used in the liquid crystal light pulp of the present invention. Nd-FB-B permanent magnet thin films 1 are arranged in a matrix on a glass substrate, and transparent electrodes 2 made of indium oxide and tin oxide, called To, are formed.

Note that portions 8 separated by broken lines on the transparent electrode 2 are pixels.

The substrate in Figure 1 and a normal substrate, that is, a glass substrate with a transparent electrode provided on it, are placed facing each other, and the long axis of the liquid crystal molecules forms an angle of 45 degrees with the magnetic field on the substrate surface, and between each substrate. 9
The liquid crystal was oriented and sealed so that it would rotate at zero, and multiplex driving was performed. Table 2 shows the threshold voltage and saturation voltage of each sample at this time.

For comparison, the value of b for a normal cell using a normal substrate is also shown.

In all samples in Table 2, the threshold voltage and saturation voltage are higher than those of the conventional structure, and the value of saturation voltage/threshold voltage, which is a measure of the steepness of the rise, is smaller, and the steepness of the rise is improved. Can be seen. This is particularly noticeable for sample 1.4, and even if multiplex driving is performed at approximately twice the multiplicity, the same level of contrast can be obtained.

〔effect〕

As described above, according to the present invention, Nd −7,− has in-plane magnetization on at least one side of the substrate surface in the liquid crystal cell.
By providing a B-based permanent magnet thin film, a strong magnetic field is formed within the liquid crystal layer, and the torque exerted by this magnetic field on the liquid crystal molecules is reduced, thereby making it possible to improve the steepness of the electro-optical characteristics, that is, to improve the multiplex characteristics.

According to the present invention, it is possible to produce a liquid crystal display without deterioration in contrast even when performing multiplex driving with a high degree of multiplicity.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a liquid crystal light pulp substrate used in an example of the present invention. 1: Nd-Fg-B permanent magnet thin film 2: Transparent electrode 8: Pixel

Claims (1)

[Claims] Nd-F6 having in-plane magnetization on at least one substrate surface of a pair of substrates with transparent electrodes formed on opposing surfaces
- An electro-optical light valve characterized in that a B-based permanent magnet thin film is formed and a liquid crystal having a positive dielectric anisotropy and a positive magnetic susceptibility anisotropy is oriented and sealed.