JPS59132A - Electrooptic device - Google Patents

Abstract

PURPOSE:To obtain a positive guest-host type liquid crystal display superior in display performance in spite of using Np type liquid crystals, by forming an insulating film subjected to homogeneous orientation treatment in accordance with a display pattern on a display electrode. CONSTITUTION:An insulating film 6 subjected to homogeneous orientation treatment in accordance with a pattern form is formed on an electrode 4 in the display pattern type formed on the prescribed position of a lower substrate 2. Said lower substrate 2 and an upper substrate 1 with electrodes 3 attached are stuck by the medium of a seal spacer 7 by the conventional method, and a liquid crystal compsn. consisting on an Np type liquid crystal (nematic liquid crystals having positive dielectric anisotropy) and a dichroic dye is sealed in to form a liquid crystal layer 5, thus obtaining an electrooptical guest-host liquid crystal display.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electro-optical device that utilizes the guest-host effect, and more specifically, a positive type electro-optical device that uses a nematic liquid crystal (hereinafter referred to as SL-Np liquid crystal) having positive dielectric anisotropy. The present invention relates to a guest-host liquid crystal display device.

Conventional positive type guest-host liquid crystal display devices use a nematic liquid crystal (hereinafter referred to as "Nn liquid crystal") with negative dielectric anisotropy as a host, which is homeotropically aligned between a pair of electrode plates, and a two-color liquid crystal display. A method has been adopted in which a coloring agent is placed as a guest and colored by applying a voltage between the electrodes of the electrode plate.However, compared to Np liquid crystal, the host Nn liquid crystal has lower driving voltage, viscosity,
It has the disadvantage that it is inferior in properties such as temperature range, and the order parameters of the dichroic dye are also poor, making it impossible to obtain high coloring contrast.

For this reason, attempts have been made to perform positive type display using Np liquid crystals. At this time, by homogeneously aligning the display portion and homeotropically aligning the other non-display portions, the voltage application portion can be changed from colored to decolored.

However, this positive type method has the drawback that it cannot completely erase color when voltage is applied.

An object of the present invention is to solve these drawbacks and provide a positive type guest-host liquid crystal display device using Np liquid crystal, which has display recognition comparable to that of a positive type guest-host liquid crystal display device using Nn liquid crystal. There is a particular thing.

The object of the present invention is to provide %NPNp liquid crystal among the electrode plates constituting the guest-host liquid crystal display device of Bositaig.
This is achieved by providing an insulating film on which at least one electrode plate is formed in the shape of a display pattern and subjected to a homogeneous alignment process to follow the shape of the display pattern.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a plan view of a liquid crystal display device of the present invention used for superimposing in a camera finder, and FIG. 2 is a sectional view taken along line A-A'.

In Figures 1 and 2, there is a gap between the electrode plate with the electrode 3 formed on the upper substrate l (glass, plastic plate, etc.) and the lower electrode plate with the electrode 4 formed on the lower substrate 2 (glass, plastic plate, etc.). This shows how the liquid crystal layer 5 is arranged.

The liquid crystal layer 5 is made of Np liquid crystal to which a dichroic dye is added.

Preferred Np liquid crystals used in the present invention include thick-based liquid crystals, ester-based liquid crystals, azo-based liquid crystals, and azoxy-based liquid crystals.

Selected from biphenyl-based liquid crystals. The representative ones are listed below.

However, R1: CnH2r+-+-t COO-2≦n≦
8CnH2n+t -1≦n<8 CnH2n+t O-3≦n≦8 However, R,: CnH2n+t -1≦n≦8Cn-H2
n+10-1,, n≦8, but Rs
: CnH, 2n+1-4s, n<,
9CnH2n+t 0
5 ≦4 n ≦ 9CnHzn+t C
OO-4≦n≦7Cnl(2n+t0COO-
5≦n≦7 but R4: CnH2n+t −4≦n<8
C+tTT2n←t O−' 5 ”5; n≦8
However, R,: Cn112n+t'≦n
≦9 However, Rlo: CnH2n+t 4
≦n≦8 However, Ru' CnH2n+t 4
≦n<8 These liquid crystals may not only be used alone, but may also be appropriately selected and mixed in order to obtain desired electro-optic characteristics, nematic liquid crystal temperature range, life span, etc. Nn liquid crystals may also be added. .

Further, typical examples of dichroic dyes that can be used in the device of the present invention are as follows.

c, F+.

0 The lower electrode plate used in the liquid crystal display device of the present invention has an electrode 4 in the form of a display pattern formed at a predetermined position on the lower substrate 2, and a transparent insulating film formed on it in the shape of the display pattern. 6 is formed.

This lower electrode plate is placed on the electrode-patterned substrate, for example 1.
-675, 1 of 1 ≠ isoglobil alcohol liquid) 60
After applying with a spinner for 10 seconds at 0 Or, p, m, 1
Vertical alignment treatment is performed by heating at 50° C. for 3 minutes. At this time, if a fluorine-based silane agent is used as a vertical alignment treatment agent, the insulating film 6 will not be able to be fixed on the electrode, so it is desirable not to use a fluorine-based silane agent. (After applying an ultraviolet curable resin liquid such as FVR-15 (manufactured by Fuji Yakuhin ■) on top of the resin using a spinner for 20 seconds at 100 Orp and pom, dry it at 60°C to 100°C for 10 minutes to a film thickness of 2 to
A 3 μm photosensitive layer is formed. fj) Next, the photosensitive layer is irradiated with ultraviolet rays for 5 seconds at an intensity of 15 to 20 mw/α through a predetermined exposure mask (the photosensitive layer coated on areas other than the electrode 4 is masked). Lightly cure the areas marked with ■
Then, after developing with FVR developer (same as above), FVRIJ
By cleaning with a solution (same as above), an insulating film 6 subjected to homogeneous alignment treatment by rubbing or the like is formed on the electrode 4.

After creating the lower electrode plate having the structure shown in FIG. 2 in this way,
Bonding with the upper electrode plate via the seal spacer 7
After the above-mentioned liquid crystal is injected into the gap formed through the injection port 8, the gap is sealed with a suitable sealant 9 to obtain the desired liquid crystal display device.

At this time, the cell thickness between the electrodes is preferably about 6 to 15 microns.

Figure 3 shows the relationship between cell thickness and transmittance (coloring degree) in a guest-host liquid crystal display device using Np liquid crystal. For example, in a guest-host liquid crystal display device with a cell thickness of 8μ, homogeneous alignment Between the electrodes, when no voltage is applied, the transmittance curve 11 is about 42 inches, and when a voltage of 6 V is applied, the transmittance curve 12 is about 58 inches, whereas the t/% electrode is The transmittance curve lO in the non-display area that has been subjected to homeotropic alignment treatment other than that formed is approximately 65
%, the colored display pattern becomes completely decolored by the voltage application and cannot be discerned by the observer. The reason for this is presumed to be that the liquid crystal molecules on the wall surface of the substrate are still not homeotropically aligned even when a voltage is applied. Therefore %NP
The transmittance of the Np liquid crystal in the meotropic alignment region becomes small.

In the liquid crystal display device of the present invention, an insulating film is formed on the electrodes in advance so that the display area has the same transmittance as the surrounding area (non-display area) when a voltage is applied, and the cell thickness of the display area is It is characterized in that it is made thinner than the cell thickness of the non-display area.

That is, since the cell thickness at which the transmittance is approximately 65 μm in the transmittance curve 12 is approximately 5.5 μm, an insulating film is placed on the electrode 4 so that the cell thickness in the display area is approximately 5.5 μm. 6 (that is, the film thickness is 2.5 μm), it is possible to make the transmittance of the display area and the transmittance of the non-display area comparable when voltage is applied.

With this device, when no voltage is applied, the display area has a transmittance of about 40%, and the surrounding area has a transmittance of about 7.0%, so the observer can distinguish the positive display, and also When the voltage is applied, the transmittance of the display area is about 70%, so that the positive display can be seen by the viewer as a completely erased state.

In addition to the above-mentioned cured resin film, the insulating film 6 in the liquid crystal display device of the present invention may be made of, for example, a photosensitive liquid containing gelatin, polyvinyl alcohol, KicroA III 7y, polyvinyl cinnamate, cyclized polyisoprene, or neoprene. P-phenylene bisazide, 4,4'-diazidebenzophenono, 4,4'-diazide diphenylmethane, 4,4'-diazide diphenyl sulfide, etc. on resin such as rubber or cyclized rubber and photosensitive component. 4.4'
- An oil-based photosensitive resin liquid mixed with an azide compound such as diazidostilbene can be used.
R120'', r0DUR1otoj manufactured by the same company, r manufactured by the same company
01) UR1013J or rODURt manufactured by the same company
Far-UV curable resin liquid such as oxJ, rOMR- manufactured by the company
The liquid crystal display device of the present invention may be of a static drive type or a dynamic drive type, and is not limited to a segment display type, but may also be of a -7 trix display type. can do.

According to the present invention, it is possible to make the transmittance of the display area and the transmittance of the non-display area at the same level when a voltage is applied, so that the viewer sees the positive display as having been completely erased by the voltage application. It has the advantage of being able to

[Brief explanation of drawings]

FIG. 1 is a plan view of a liquid crystal display device of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA'. FIG. 3 is an explanatory diagram showing the relationship between cell thickness and transmittance in a liquid crystal display device. 1. Upper substrate 2. Lower substrate 3. 4. Electrode 5. Liquid crystal layer 6. Absolute film 7. Seal spacer 8. Inlet 9 Sealing LJ agent IO. Transmittance of homeotropic alignment region 11. Transmittance of homogeneous orientation region Transmittance of homogeneous orientation region when voltage of 12...6■ is applied

Claims (1)

[Claims] In an electro-optical device having a dichroic dye and a nematic liquid crystal having positive dielectric anisotropy between a pair of electrode plates, at least one of the pair of electrode plates is placed on an electrode formed in a display pattern shape. An electro-optical device comprising an insulating film subjected to a homogeneous alignment process that follows the shape of a display pattern.