JPH0519250A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide the dispersed liquid crystal display element which has a high contrast even in the case of non-parallel rays, is inexpensive and can be made large in size. CONSTITUTION:The liquid crystal display element consists of two pieces of transparent substrates 2a, 2b, and a light controlling layer 5 consisting of a dispersed liquid crystal supported between these substrates 2a, 2b, and on each outside of these two pieces of substrates 2a, 2b, polarization selecting elements 4a, 4b are provided so that the polarization selecting elements 4a, 4b become an orthogonal Nicol prism or a parallel Nicol prism each other, respectively. In this regard, it is also allowable that the polarization selecting element 4b is provided on only the outside of the substrate 2b of at least the emitted light side in these substrates 2a, 2b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersion type liquid crystal display device useful as, for example, a flat panel display device.

[0002]

2. Description of the Related Art Conventionally, liquid crystal display elements of TN type or STN type using nematic liquid crystal have been put into practical use. Also, a liquid crystal device using a ferroelectric liquid crystal has been proposed. These require alignment treatment or the like when they are made into elements, and large-sized elements cannot be easily produced. On the other hand, as a method of manufacturing a large-sized and inexpensive liquid crystal element without requiring such an alignment treatment, a method of dispersing liquid crystal droplets in a polymer by encapsulating a liquid crystal is known (JP-A-58-58). 501632, US Patent Nos. 4,4
35,047). According to the method, a liquid crystal molecule encapsulated with polyvinyl alcohol, if it has a positive dielectric anisotropy in a thin film, the liquid crystal molecule is aligned in the electric field direction in the presence of an electric field, When the refractive index n _{o of the} liquid crystal is equal to the refractive index n _{p of the} polymer, transparency is exhibited.
When an electric field is removed, the liquid crystal array returns to a random sequence, the liquid crystal droplets since the refractive index of the liquid crystal droplets is deviated from n _o scatters light at the boundary surface, Ususotai is cloudy. In addition to the above-mentioned techniques, there are some known liquid crystal display device technologies in which a polymer containing dispersed liquid crystal is used as a thin film. For example, in JP-A-61-250218, the liquid crystal is contained in an epoxy resin. Dispersion, JP-A-2-83534 discloses a dispersion of liquid crystal in a urethane acrylate resin.

As a means for improving the contrast, a capsule type liquid crystal display device having a background supply section and a selective through hole section in an encapsulated liquid crystal section is disclosed in Japanese Patent Laid-Open No. 63-9.
No. 8631.

[0004]

DISCLOSURE OF THE INVENTION The dispersion type liquid crystal display device has various advantages such as a simple structure and easy size increase as compared with a conventional type in which liquid crystal is filled between glass plates and sealed. On the other hand, unlike the sealed type, the presence or absence of voltage application not only causes immediate increase or decrease in background light, but also causes transmission and scattering. Therefore, in the dispersion type liquid crystal display element, black is difficult to display and contrast of non-parallel light is not so good because it changes to white due to scattering when no applied voltage is applied and changes to transparent when a voltage is applied. This becomes a problem especially when the dispersion type liquid crystal is used as a direct view type. Further, in order to provide the encapsulating liquid crystal part with the background light supply part and the selectively transmitted light part, a shutter for forming a converging lens group and an aperture group corresponding to the pixel area is required, so that a large and inexpensive display element Is difficult to create.

Therefore, the present invention has a high contrast even in non-parallel light, can display black even in a direct-view type, and is inexpensive.
It is an object of the present invention to provide a liquid crystal display device that can be upsized.

[0006]

In order to solve the above-mentioned problems, the present invention employs a means of providing a polarization selection element outside a dispersion liquid crystal substrate.

That is, the present invention comprises two substrates, at least one of which is transparent, and a dimming layer made of a dispersion type liquid crystal supported between these substrates. The present invention provides a liquid crystal display element characterized in that a polarization selection element is provided outside a substrate.

When the polarization selecting elements are respectively provided on the outer sides of the two substrates, they can be provided so as to be orthogonal Nicols (cross type) or parallel Nicols (parallel type).

As the polarization selection element used in the present invention, known ones such as a polaroid plate, a Nicol prism, a Glan-Terra prism, and a Glan-Thompson prism can be appropriately selected.

[0010]

In the liquid crystal display element having such a structure, the black level is improved by the extinction ratio of the polarization selection element, and good black display is possible even with the direct-view type.

[0011]

The present invention will be described below with reference to the illustrated embodiments.

First, FIG. 1 shows an example in which polarization selection elements are provided on both sides of a dispersion type liquid crystal substrate so as to be orthogonal Nicols (hereinafter also referred to as cross type), and ITO transparent electrodes 1a and 1b are provided. Two transparent substrates (for example, made of glass) 2a and 2b provided inside, and these substrates 2a and 2b
and a polarization selection element 4a provided on the outside of each of the two substrates 2a and 2b so as to be orthogonal to each other.
(Polarizer) and 4b (analyzer). In addition,
In the figure, A indicates the transmission axis direction of the polarizer, and B indicates the transmission axis direction of the analyzer (the same applies to FIGS. 2 and 3 below).

The structure of the light control layer 3 is not particularly limited, and is composed of a liquid crystal capsule dispersed in a supporting medium made of a photocurable resin such as an acrylic resin as in the conventional case.

As the polarization selecting elements 4a and 4b, known elements such as a polaroid plate, a Nicol prism, and a Glan-teer are used.
A La prism, a Glan-Thompson prism, etc. can be used.

In the liquid crystal display device having such a structure, when a voltage is applied, the dispersion type liquid crystal becomes isotropic (transparent state), so that it passes through the polarization selection element (polarizer) 4a and the dimming layer 3. The linearly polarized light cannot pass through the polarization selection element (analyzer) 4b, so that the liquid crystal display element is in a dark state (black). On the other hand, when no voltage is applied, the incident light is linearly polarized by the polarizer 4a,
Since the light is scattered by the light control layer 3 made of dispersed liquid crystal, the scattered light passes through the analyzer 4b, and the liquid crystal display element is in a bright state (white).
Becomes That is, the black level is improved by the extinction ratio of the polarizer 4a.

FIG. 2 shows an example in which a polarization selection element is provided on both sides of a dispersion type liquid crystal substrate so as to be parallel Nicols (also called parallel type), and the ITO transparent electrodes 1a and 1b are provided.
Two transparent substrates (for example, made of glass) 2a and 2b provided inside, a dimming layer 3 made of a dispersed liquid crystal supported between these substrates 2a and 2b, and these two substrates 2a. Polarization selecting elements 4a (polarizers) provided on the outer sides of 2b so as to be parallel Nicols,
4b (analyzer). That is, the polarizer 4
It is exactly the same as the example of FIG. 1 except that a and the analyzer 4b are provided so as to be parallel Nicols.

In the liquid crystal display device having such a structure, when a voltage is applied, the dispersion type liquid crystal becomes isotropic (transparent state). Therefore, the polarization selection device (also called a polarizer) 4
The linearly polarized light passing through a passes through the analyzer 4b as it is, and the liquid crystal display element is brought into a bright state. On the other hand, when no voltage is applied, the incident light is linearly polarized by the polarizer 4a, but is scattered by the light control layer 3 made of dispersion type liquid crystal in a white turbid state, so that only a part of the scattered light is detected. It can pass through the photons 4b, and becomes a dark state (black) as a liquid crystal display element.

FIG. 3 shows an example of a polarization selection element (analyzer) only on the exit side of the dispersion type liquid crystal substrate.
Two transparent substrates 2a and 2b (for example, made of glass) having transparent electrodes 1a and 1b provided inside thereof, respectively, and these substrates 2
A light control layer 3 composed of a dispersion type liquid crystal supported between a and 2b
And the substrate 2b on the emitting side of the two substrates 2a and 2b
And a polarization selection element (analyzer) 4b provided only in the. That is, it is exactly the same as the example of FIG. 2 except that the polarizer 4a is removed in FIG.

When a voltage is applied to the liquid crystal display device having such a structure, the dispersed liquid crystal becomes isotropic (transparent state), so that the light passing therethrough passes through the analyzer 4b and the liquid crystal display device. Is in a bright state. On the other hand, when no voltage is applied, the incident light is scattered by the light control layer 3 made of the dispersion type liquid crystal in the white turbid state, so that only a part of the scattered light can pass through the analyzer 4b and the liquid crystal The display element is in a dark state (black). In addition, in the above-mentioned embodiment, the transparent substrate provided with the transparent electrode (ITO) has been described, but the transparent electrode may be omitted.

[0020]

【Example】

[Example 1] 11% by weight of butyl acrylate, 8% by weight of acrylic oligomer M-1200 (manufactured by Toagosei Co., Ltd.),
A 13 μm spacer was added to a solution containing 1.0% of Dalocure 1116 manufactured by Merck Ltd. as a photo-curing initiator and 80% by weight of E8 manufactured by BDH as a host liquid crystal and well dispersed. The mixture was applied onto a glass substrate with ITO, the glass substrates with ITO were superposed, and exposed for 2 minutes with an ultraviolet irradiation device (Minicure 450 manufactured by Ushio Inc.) to prepare a dispersion type liquid crystal. Polarizing plates were attached to both sides of this substrate so as to form a crossed Nicols, and a liquid crystal display element as shown in FIG. 1 was produced. Then, using the optical system as shown in FIG. 4, the brightness was measured with and without the voltage applied to the present liquid crystal display element, and the contrast was calculated to be 1: 5.
It was 0.

The optical system shown in FIG. 4 has a flat top surface and a light box 12 in which a fluorescent lamp 11 is disposed, and a column 1.
3 and a color luminance meter (topcon BM manufactured by Topcon Corporation) provided directly above the light box 12 for adjustable vertical movement.
-7) The present liquid crystal display element 1 comprising
5 is placed on the light box 12, and the present liquid crystal display element 1
For 1 to 5 by function generator
The luminance was measured by a color luminance meter 14 when a voltage of 0 to 20 V was applied with and without a voltage of z and a square wave.

[Embodiment 2] A liquid crystal display element manufactured in the same manner as in Embodiment 1 is projected and displayed by a projection optical system as shown in FIG. 5, and the contrast of a projected image is measured by a color luminance meter (BM-7 manufactured by Topcon Corporation). Was calculated in the same manner as in the example, and it was 1: 8.
It was 0.

The optical system of FIG. 5 uses a mercury arc lamp 16 as a light source, to which a lens 17 and a pair of U lamps are provided.
V, IR filter-18, 19, lens 20, shre
The lens stop 21 and the screen 22 are arranged in this order in parallel.
The present liquid crystal display element 15 is interposed between 0 and 0, and the liquid crystal display element 4 is set to 1 k by the function generator.
The luminance was measured with a color luminance meter at a voltage of 0 to 20 V at a voltage of 0 Hz to 20 Hz and when a voltage was not applied.

Example 3 A dispersion type liquid crystal produced in the same manner as in Example 1 was attached with a polarizing plate so as to form parallel Nicols as shown in FIG. 2 to obtain a liquid crystal display element. Then, under the same conditions as in Example 1, the contrast was determined using the optical system shown in FIG. 4, and it was 1:10.

Example 4 A dispersion type liquid crystal produced in the same manner as in Example 1 was laminated with a polarizing plate as shown in FIG. 3 to obtain a liquid crystal display element. Then, under the same conditions as in Example 1, FIG.
When the contrast was obtained using the optical system shown in,
It was 1: 9.

[Comparative Example 1] The dispersion type liquid crystal itself produced in the same manner as in Example 1 was placed in a light box, and the contrast was measured under the same conditions as in Example 1, and it was 1: 3.

Example 5 15% by weight of isododecyl-acrylate, long-chain aliphatic diacrylate (C-200)
0, a trademark, manufactured by SATOMER Co., Ltd.) 10% by weight, a photocuring initiator Darocur 1116 (trademark) manufactured by Merck 1.0%, and a host liquid crystal E7 (trademark) manufactured by BDH 74% by weight in a solution of 10 μm. Spacers were added and well dispersed. The mixture was applied onto a glass substrate with ITO, the glass substrates with ITO were overlapped, and exposed for 90 seconds by an ultraviolet irradiation device (Minicure 450 (trademark) manufactured by Ushio Inc.) to prepare a dispersed liquid crystal.
Using this dispersion type liquid crystal, polarizing plates were attached to both sides of the substrate so as to form a crossed Nicols, and a liquid crystal display element as shown in FIG. 1 was produced. Then, under the same conditions as in Example 1,
When the contrast was measured using the optical system shown in FIG. 4, it was 1:38.

[Embodiment 6] A dispersion type liquid crystal display device manufactured in the same manner as in Embodiment 5 was manufactured under the same conditions as in Embodiment 2.
When the contrast was similarly measured using the optical system shown in, the result was 1:55.

[Embodiment 7] A dispersion type liquid crystal produced in the same manner as in Embodiment 5 was attached with a polarizing plate so as to form parallel Nicols as shown in FIG. 2 to obtain a liquid crystal display element. Then, under the same conditions as in Example 1, the contrast was calculated using the optical system shown in FIG. 4, and it was 1: 6.

[Embodiment 8] A dispersion type liquid crystal prepared in the same manner as in Embodiment 5 was attached with a polarizing plate as shown in FIG. 3 to obtain a liquid crystal display element. Then, under the same conditions as in Example 1, FIG.
When the contrast was obtained using the optical system shown in,
It was 1: 3.

Example 9 Pentyl Glycol / Polypropylene Glycol Modified Diacrylate C-9003
(Trademark, manufactured by SATOMER) 21% by weight, as a photo-curing initiator, a solution of Darocur 1173 (trademark) manufactured by Merck Ltd. 0.8%, and liquid crystal GR-63 (manufactured by Chisso Corporation) 78.2% by weight, A 10 μm spacer was added and well dispersed. The mixture is applied on a glass substrate with ITO, the glass substrates with ITO are overlaid, and an ultraviolet irradiation device (Minicure 450 (trademark) manufactured by Ushio Inc.)
Was exposed for 90 seconds to prepare a dispersion type liquid crystal. Using this dispersion type liquid crystal, polarizing plates were attached to both sides of the substrate so as to form a crossed Nicols, and a liquid crystal display element as shown in FIG. 1 was produced. Then, under the same conditions as in Example 1, the contrast was measured using the optical system shown in FIG.
It was 35.

[Example 10] The contrast of the dispersion type liquid crystal display element produced in the same manner as in Example 9 was similarly measured under the same conditions as in Example 2 using the optical system shown in FIG. It was 1:50.

[Embodiment 11] A dispersion type liquid crystal prepared in the same manner as in Embodiment 9 was attached with a polarizing plate so as to form parallel Nicols as shown in FIG. 2 to obtain a liquid crystal display element. Then, under the same conditions as in Example 1, the contrast was calculated using the optical system shown in FIG. 4, and it was 1: 4.

[Example 12] A dispersion type liquid crystal produced in the same manner as in Example 9 was laminated with a polarizing plate as shown in Fig. 3 to obtain a liquid crystal display element. Then, under the same conditions as in Example 1, the contrast was obtained using the optical system shown in FIG.
It was 1: 2.5.

[0035]

As is clear from the above description, the present invention is the addition of a polarization selection element to a dispersion type liquid crystal, and even a large area can be manufactured extremely easily and inexpensively. Moreover, since the contrast can be improved by this, a complicated optical system etc. is not required,
It is possible to provide a very economical liquid crystal element.

[Brief description of drawings]

FIG. 1 is a perspective view of a liquid crystal display element according to the present invention.

FIG. 2 is a perspective view showing another example of the liquid crystal display element according to the present invention.

FIG. 3 is a perspective view showing still another example of the liquid crystal display element according to the present invention.

FIG. 4 is a schematic diagram showing an example of an optical system for measuring the contrast of a liquid crystal display element.

FIG. 5 is a schematic diagram showing another example of an optical system for measuring the contrast of a liquid crystal display element.

[Explanation of symbols]

A, B ... Light transmission direction 1a ... ITO transparent electrode 1b ... ITO transparent electrode 2a ... substrate 2b ... substrate 3 ... Light control layer 4a ... Polarization selection element 4b ... Polarization selection element 11 ... Fluorescent lamp 12 ... Light Box 13 ... Support 14 ... Color luminance meter 16 ... Mercury arc lamp 17 ... Lens 18 ... UV filter 19 ... IR filter 20 ... Lens 21 ... Shuri Renstop 22 ... Screen

Claims (3)

[Claims] 1. Two substrates, at least one of which is transparent,
A liquid crystal display device comprising a dimming layer made of a dispersion type liquid crystal supported between these substrates, and a polarization selection element provided at least outside the substrate on the side of the emitted light. 2. The liquid crystal display element according to claim 1, wherein polarization selection elements are provided on the respective outer sides of the two substrates so as to be in mutually orthogonal Nicols. 3. The liquid crystal display element according to claim 1, wherein polarization selection elements are provided outside each of the two substrates so as to be in parallel Nicols with each other.