JPH0718996B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Use of the Invention" The present invention provides a display panel using a ferroelectric liquid crystal (hereinafter referred to as FLC) to reduce the thickness of a display portion of a microcomputer, a word processor, a television, or the like. The present invention relates to a liquid crystal display device.

“Prior Art” In a solid-state display panel, a method of independently controlling each pixel is effective for a large area. Conventionally, as such a panel, a dual-frequency liquid crystal, for example, a twisty nematic liquid crystal (hereinafter referred to as TN liquid crystal) is used, and a multiplexing driving method is applied to a simple matrix configuration of A4 size with 400 elements in the horizontal direction or 200 elements in the vertical direction. A display device using is known.

However, it has been found that it is impossible to use a TN liquid crystal to make a large-area display device having more pixels than this due to the limit of frequency characteristics. In addition, even if the pixels are arranged in a matrix with a predetermined distance therebetween, crosstalk (a phenomenon in which electrical conduction is weak and weak) between adjacent pixels is likely to occur. Therefore one side
Even if the ON function and the other function are turned off, each pixel has enough
I could not turn it on or off, and the contrast was insufficient.

In order to eliminate such a defect, a method of connecting an active element to each pixel is known. A typical example thereof uses a TFT (thin film insulating gate field effect semiconductor device) as an element.

Further, a method using a non-linear element is known.

Further, in the passive type configuration (simple matrix type), it has been attempted to use FLC instead of the conventionally known TN type liquid crystal as a liquid crystal.
Having a talk, not the best.

This FLC is a bistable liquid crystal with a memory function,
Particularly excellent in frequency characteristics.

As described above, when a method combining these methods, that is, a method using a passive method (hereinafter referred to as P) or a method using a TFT, a method using a TN for a liquid crystal or a method using an FLC, is as shown in Table 1 below. .

However, ⊚ indicates very good, ∘ indicates good, Δ indicates slightly unsatisfactory, and x indicates unsatisfactory.

When considering the above four methods, it was found that there is always an X mark in any method, and there is no final answer in any of these methods.

As a result, methods other than these four methods are required.

In order to solve such a problem, the applicant has combined a bidirectional nonlinear element (hereinafter referred to as NE) and an FLC as an active element. (Japanese Patent Application Sho 59-183347,59-183348,59-
183349, 60-10299, etc.) Below, an ideal structure as a non-linear element and a particularly known MIM (conductor-insulating film-
(Conductor) structure and SCLAD (complex diode using space charge limited current) structure.

Table 2 shows the outline.

As is clear from the above, the present invention can be applied to non-linear elements and FL
Since C and C are used, both work synergistically and cross
No talk, the process isn't too complicated and the FLC
It was found that the configuration is very close to ideal because the angle of view can be improved by using.

Therefore, as described in the present invention, it has been found that a large-sized large-area liquid crystal display can be manufactured for the first time by using pixels provided by connecting a non-linear element and a ferroelectric liquid crystal in series.

On the other hand, in the case of industrially manufacturing a large-sized display using these configurations, it has been a very difficult technique to arrange FLCs in parallel with the liquid crystal cell, which is a serious problem. In particular, various efforts have been made to obtain a uniform orientation in the case of a large area.

"Object of the Invention" The present invention aims to realize a domain having a large area and a uniform molecular arrangement by a simple method.

“Structure of the Invention” The present invention relates to a solid-state display device in which pixels using a ferroelectric liquid crystal having a plurality of active elements on a substrate are connected in series and arranged in a matrix. The inside of the electrode is subjected to an asymmetric alignment treatment in which the electrode on the side of the active element is not rubbed, and the electrode on the side of the active element is coated with a surfactant consisting of 1.1.1.trimethylsilazane. It has a feature.

That is, the present invention is a liquid crystal display device using a ferroelectric liquid crystal (FLC), in which an active element is connected to an electrode forming each pixel, and a substrate side provided with an active element among a pair of substrates sandwiching a liquid crystal. The electrode is not rubbed, but the opposite one of the electrodes on the substrate side is rubbed, in the so-called asymmetric alignment treatment, the electrode on the substrate side on which the active element is provided is Known as a surfactant, 1.1.1. Trimethylsilazane is applied.

In the liquid crystal display device that has been subjected to the asymmetric alignment treatment, the present invention corrects the difference in the pretilt angle of the liquid crystal molecules in contact with each substrate, which is caused by the treatment.
It is possible to realize a domain having a uniform arrangement of liquid crystal molecules in a large area.

Example 1 FIG. 2 shows a circuit diagram using the liquid crystal display device of the present invention.

In the drawing, the pixel is the electrode (21) of the SCLAD (2) (first
Electrode) (In the drawing, the numbers are surrounded by rectangles.)
It is connected to one electrode (23) (third electrode) of the ferroelectric liquid crystal (3). The SCLAD is connected to the Y wirings (4) and (5) by the second electrode (22). On the other hand, FLC
The fourth electrode (24) (counter electrode) of (3) is connected to the X wirings (6) and (7). The X-wiring corresponds to the third electrode (23) of the FLC (3) and is closely attached to another translucent insulating substrate, typically a glass substrate ((20 ') in FIG. 1C). It is provided ((6) or (24) in FIGS. 2 and 1C).

An example of the manufacturing process of the non-linear element which is a part of the pixel using such a composite diode and its characteristics are shown in FIGS.
Shown in the figure.

In the manufacturing process of FIG. 3, the area (1) surrounded by the broken line in FIG. 1 is shown in FIG. 1 (A), but the area (40) in FIG. It corresponds to when.

3 (A), (B), (C), and (D) are shown in FIG. 1 (D).
It corresponds to.

In FIG. 3 (A), Corning 7059 glass (20) was used as the translucent insulating substrate. Molybdenum, which is a conductive film (22), was formed to a thickness of 0.1 to 0.5 μm on the upper surface by a sputtering method or an electron beam evaporation method.

After that, a non-single-crystal semiconductor film was formed over these entire surfaces by a photo CVD method or a plasma CVD method. The thickness is N type semiconductor (13) (0.1μ) -I type semiconductor (14) (0.3μ) -N
SCLAD with NIN junction of type semiconductor (15) (500Å).

Then, chromium (21) was laminated on the upper surface by electron beam evaporation or sputtering to a thickness of 0.1 to 0.2 μm.

Further, as shown in FIG. 3 (B), anisotropic plasma etching was performed with the first photomask so that the peripheral portion was vertical, and the laminate (50) was provided.

Next, a photosensitive polyimide resin (27) was formed on the entire surfaces of these by a coating method to a thickness of about 1 μm.

Thus, the upper surface of the electrode (21) of the laminate (50) and the upper surface (39) of the polyimide resin (27) have a structure in which the surface of the insulator and the surface of the laminate are smoothly continuous after curing except for the convex portions of the laminate. I was made to become. That is, ultraviolet light was exposed from the back surface side of the glass substrate (20) side from the glass surface side by using a known mask aligner without using a mask. For example, an aligner manufactured by Cobilt Co., Ltd. was exposed for about 2 minutes. Its strength is 30
15 to 30 for ultraviolet light (19 mW / cm ² ) with a wavelength of 0 to 400 nm
Seconds are enough.

Then, a laminate having a side surface (26) (thickness of about 1 μ) (5
In contrast to 0), the convex area above it, which is shaded, is not exposed, and only the periphery of that side is exposed. After further development, the non-photosensitive protrusions were removed by a rinse liquid.

Then, all of these were heated at 180 ° C. for 30 minutes + 300 ° C. for 30 minutes + 400 ° C. for 30 minutes in nitrogen to be cured. Thus, in addition to exposing the second electrode of the non-linear element, which is the upper surface of the laminated body, without using a photomask, the upper surface and the peripheral surface of the polyimide resin insulator are smoothly continuous to form a third electrode. It is possible to obtain the figure (C).

Next, on the entire upper surface of FIG. 3 (C), ITO was formed as a FLC electrode (third electrode) to a thickness of 0.1 to 0.3 .mu. By sputtering or electron beam evaporation. Further, this electrode is formed into a predetermined shape, for example, a second pixel electrode of 120 μ × 420 μ
Selective etching was performed using the photomask ().
Further, on this upper surface, alumina as one non-rubbing layer (layer not subjected to rubbing treatment) (25) of the asymmetric alignment layer,
An inorganic material such as silicon oxide or magnesium fluoride was used and formed by electron beam evaporation to a thickness of 50 to 300 Å.

Thus, the second electrode (22) connected to the lead (6) in the Y direction, the SCLAD (2) on the second electrode (22) and the laminated body (50) of the upper first electrode (21) are provided. A third electrode (23) of the FLC may be provided close to the electrode. For this purpose, it is possible to provide an active element corresponding to each pixel by two photomasks, that is, one mask alignment. The symbol of this SCLAD structure is marked as (2) in FIG.

As a result, the non-linear characteristic (electrode area 120 μ × 420 μ) as shown in FIG. 4 (A) can be provided corresponding to FIG. 3 (the vertical axis shows the absolute value on a log scale). It was

In order to form a pixel as a liquid crystal display element, as shown in FIGS. 1 (C) and (D), the X-direction lead and the counter electrode (24), which have been subjected to the rubbing alignment treatment, are provided on the inside of the substrates facing each other. It is provided. Then, inside the pair of electrodes (23) and the counter electrode (24), the asymmetric alignment film (2
5) and (25 ') are provided to sandwich the FLC (thickness 2μ). After the diluted 1.1.1.trimethylsilazane was applied to the counter electrode (24), nylon was provided to a thickness of 0.1 μ by a spin method and a known rubbing treatment was performed. As an example of the rubbing treatment, nylon was rotated in a rubbing apparatus at 900 PPM, and the surface was formed by moving the substrate several times, for example, 5 times at a speed of 2 m / min. Also on one electrode (23)
1.1.1. After applying trimethylsilazane, the solvent is removed to form an alignment film without rubbing treatment, and the alignment film is placed on the counter electrode (24).
1.1.1. After coating trimethylsilazane, a film of organic compound is formed, and rubbing treatment is performed to form an alignment film.FlC, for example, DOBAMBC and MBRA blended, is injected.The cell size is 100 mm × 300 mm. However, a good uniform orientation was obtained over this size.

An example of the threshold characteristic of this pixel is shown in FIG. Also in the drawing, it was found that curves (29) and (29) can be obtained by adding ± 5 V, and transmission and non-transmission can be performed, sufficient inversion can be performed, and hysteresis showing a memory effect can be obtained. Third
In FIG. (4), the vertical axis is the transmittance.

[Effect] As described above, the present invention uses the same material as the untreated side as the base of the rubbing-treated alignment film, which further promotes asymmetry and facilitates good uniform alignment even in a large area. Was obtained. Also in the 2 × 2 matrix configuration shown in the figure, when the non-linear element and (1,1) shown in FIG. 1 are turned on, (1,2), (2,2), (2,1 The current value of the OV of the non-linear element is sufficiently low with respect to the voltage applied simultaneously via (1), and does not flow out. As a result, (1,1) becomes O
When N was set, it was possible for the first time to turn off other addresses at the same time using a non-linear element, and crosstalk could be completely prevented. The manufacturing process was also extremely simple in the structure shown in the embodiment.

[Brief description of drawings]

FIG. 1 shows a plan view and a vertical sectional view of a display panel of the present invention. FIG. 2 shows a circuit diagram of the liquid crystal display panel of the present invention. FIG. 3 is one longitudinal sectional view showing a manufacturing process of the space charge limited current type composite diode of the present invention. FIG. 4 shows operating characteristics of the nonlinear element and the ferroelectric liquid crystal of the space charge limited current type composite diode of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsunori Sakama 7-21-21 Kitakarasuyama, Setagaya-ku, Tokyo Inside Semiconductor Energy Laboratory Co., Ltd. (72) Inventor Toshiji Hamaya 7-21 Kitakarasuyama, Setagaya-ku, Tokyo No. 21 Incorporated Semiconductor Energy Laboratory (72) Inventor Minoru Miyazaki 7-21-21 Kitakarasuyama, Setagaya-ku, Tokyo Incorporated Semiconductor Energy Laboratory (72) Inventor Kaoru Koyanagi 7 Kitakarasuyama, Setagaya-ku, Tokyo 21-21 21 Semiconductor Energy Laboratory Co., Ltd. (72) Inventor Toshiharu Yamaguchi 7-21-21 Kitakarasyama, Setagaya-ku, Tokyo Ritsumasa Kobashi (56) References Examiner, Semiconductor Energy Laboratory Co. Ltd. Flat 5-2129 (JP, B2)

Claims (1)

[Claims] 1. In a liquid crystal display device in which pixels using a ferroelectric liquid crystal having a plurality of active elements on a substrate are connected in series and arranged in a matrix, the inside of a pair of electrodes formed by the pixels is The liquid crystal is characterized in that the electrode on the active element side is subjected to an asymmetric alignment treatment without rubbing treatment, and the electrode on the active element side is coated with a surfactant composed of 1.1.1.trimethylsilazane. Display device.