JPH11190849A - Color liquid crystal element - Google Patents

Abstract

(57) [Problem] To provide a color liquid crystal element realizing excellent viewing angle characteristics and bright display simultaneously. SOLUTION: The inside of a cell is divided into stripes by a partition member 15 for adhering upper and lower substrates 11 and 21 and maintaining a cell gap, and three types of liquid crystals 16a to 16c having different birefringences are sequentially arranged in each region. Thus, color display is performed without using a color filter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device used for a liquid crystal display device or a liquid crystal optical shutter, and more particularly to a color liquid crystal device which performs color display without using a color filter.

[0002]

2. Description of the Related Art As a color liquid crystal display device capable of obtaining a colored display, a type in which light is colored using a color filter is generally used. However, since the color filter absorbs not only the wavelength light outside the wavelength band corresponding to the color but also the light in the wavelength band at a considerably high absorption rate, the colored light passing through the color filter is incident on the color filter. The light is significantly reduced in light quantity as compared with the light in the above wavelength band, and the display becomes dark.

There are two types of liquid crystal display devices: a transmissive type that displays by using light from a backlight disposed on the back side, and a light that passes through the liquid crystal display device by using external light. There is a reflection type in which the light is reflected by a reflected reflector for display. If the color liquid crystal display device is a reflection type, light is incident from the front side (observer side), is reflected by the reflector, and is emitted to the front side. The light passing through the color filter twice reduces the amount of light, so that the display becomes extremely dark and cannot be practically used as a display device.

On the other hand, an EC that does not require a color filter
A B (birefringence effect) type color liquid crystal display device is conventionally known. In this ECB type liquid crystal display device, a pair of polarizing plates are arranged with a liquid crystal cell having a liquid crystal layer provided between a pair of transparent substrates having transparent electrodes formed on inner surfaces (opposing surfaces of the liquid crystal layer). In general, as the liquid crystal cell, a liquid crystal cell in which liquid crystal molecules are aligned in any one of a homogeneous alignment, a homeotropic alignment, and a hybrid alignment is used.

In this ECB type liquid crystal display device, linearly polarized light that has passed through one of the polarizing plates and enters the liquid crystal cell is converted into an elliptic light having different polarization states due to the birefringence effect of the liquid crystal layer in the process of passing through the liquid crystal cell. It becomes polarized light, and the light enters the other polarizing plate, and the light transmitted through the other polarizing plate becomes colored light of a color corresponding to the light amount ratio of each wavelength light constituting the light. .

That is, the above-mentioned ECB type liquid crystal display device uses a birefringence effect of a liquid crystal layer of a liquid crystal cell and a polarizing effect of a pair of polarizing plates to color light without using a color filter. Accordingly, since there is no light absorption by the color filter, a light color display can be obtained by increasing the light transmittance.

However, the liquid crystal display device using the above-mentioned ECB type liquid crystal has a problem that viewing angle characteristics are poor.

[0008]

As described above, in a color liquid crystal display device using a color filter, there is a problem that the transmittance is reduced due to the color filter.
On the other hand, E which can perform color display without using a color filter
The CB-type liquid crystal display device has a display problem of poor viewing angle characteristics, and a liquid crystal display device having good viewing angle characteristics and capable of bright display has been demanded.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a bright color display liquid crystal element having good viewing angle characteristics.

[0010]

SUMMARY OF THE INVENTION The present invention is a liquid crystal element comprising a pair of substrates each having an electrode and having a liquid crystal sandwiched between the substrates. And a plurality of liquid crystals transmitting or reflecting different wavelengths, each of which is partitioned by the partition member so as to have a predetermined pattern arrangement. Is a color liquid crystal element characterized by being injected into a color liquid crystal element.

In the present invention, a plurality of types of liquid crystals transmitting or reflecting different wavelengths are used in combination, and each liquid crystal is injected into a predetermined region partitioned by a partition member, thereby obtaining a birefringence effect of a liquid crystal layer and a liquid crystal. It is to color the light using the polarization action of a pair of polarizing plates disposed outside the element, because the light is not absorbed by the color filter,
Light transmittance is improved, and a bright color display can be obtained.

In the present invention, the birefringence of the liquid crystal layer is determined by the value of the retardation of the liquid crystal. However, since the cell thickness is constant, if a plurality of liquid crystals having different birefringences are separately used in combination, A plurality of colors (R, G, B) can be displayed. In the present invention, a partition member for bonding the upper and lower substrates and maintaining the cell gap is formed in a stripe shape to partition the inside of the cell into stripes, and each liquid crystal is injected into each region partitioned by the partition member. The pixel arrangement can be the same as that of a liquid crystal element using a conventional stripe color filter.

Transmitted light intensity I observed under crossed Nicols
Is: I∝sin ² (2θ _a ) sin ² (π · Δn · d / λ) θ _a : apparent tilt angle of liquid crystal Δn: birefringence of liquid crystal (refractive index of ordinary light−refractive index of extraordinary light) d: cell gap λ: wavelength of light, and as shown in FIG. 4, the relationship between wavelength and transmitted light intensity is different due to the difference in retardation value.

Therefore, for example, in the case of a liquid crystal element having a cell gap of 3 μm, if Δn = 0.066, the integrated transmitted light is white, and if Δn = 0.2, the integrated transmitted light is blue. If Δn = 0.17, the integrated transmitted light becomes red, if Δn = 0.23, the integrated transmitted light becomes green, and Δn = 0.2, 0.17, 0.23 If three types of liquid crystals are arranged in order, full-color display by R, G, and B display is possible.

[0015]

FIG. 1 is a schematic partial sectional view of an embodiment of the liquid crystal device of the present invention. In the figure, 11 and 21 are substrates, 12 and 22 are electrodes, 13 and 23 are insulating layers, and 14 and 2.
4 is an alignment film, 15 is a partition member, 16a to 16c are R,
A liquid crystal layer corresponding to G and B. FIG. 2 schematically shows the relationship between the electrodes 12 and 22 and the partition member 5 of the present embodiment. In the figure, 31 is a sealing material, and 32 is a sealing material. FIG. 3 shows the electrode configuration of each substrate.

Substrates 11 and 21 used in the present invention
In the case of a transmission type, a normal glass substrate is preferably used, and a plastic substrate or the like can be used if necessary characteristics such as strength and transparency are satisfied. When a reflective liquid crystal element is formed, an opaque substrate such as a silicon substrate may be used as one of the substrates. The electrodes 12 and 22 may be made of a transparent conductive material such as tin oxide, indium oxide, or indium tin oxide (ITO), and may be provided with a low-resistance metal layer as needed. In the case of the reflection type, a metal or the like may be used as the reflection plate in some cases. The thickness of the electrodes 12 and 22 is 40 to 200
nm is preferred. In the present embodiment, the electrode 1
2 and 22 are each formed in a stripe shape (FIG. 3) and arranged so as to be orthogonal to each other to form a simple matrix configuration (FIG. 2). Therefore, the area where the upper and lower electrodes 12 and 22 intersect becomes each pixel.

The insulating layers 13 and 23 are formed, if necessary, for the purpose of preventing short circuit between the upper and lower substrates. The insulating layer is an inorganic film of TiSi, SiO ₂ , TiO, Ta ₂ O ₃ or the like, and if necessary, fine particles having an average particle size of about 40 nm are dispersed and subjected to a roughening treatment. The film thickness is preferably 2
0 to 300 nm.

The surface roughening treatment can be carried out by dispersing and applying fine particles in a solution of a component having a ratio of Ti to Si of 1: 1 and then sintering. As for the degree of the surface roughening treatment, a desired rough surface can be obtained by appropriately designing the dispersion density of the fine particles, the average particle diameter, the thickness of the layer provided thereon, and the like.

The alignment films 14, 24 for controlling the alignment of liquid crystal molecules are made of polyimide, polypyrrole, polyvinyl alcohol, polyimide amide, polyester imide,
Polyparaxylene, polyester, polycarbonate,
Polyvinyl acetal, polyvinyl chloride, polyamide,
An organic film such as polystyrene, a cellulose resin, an acrylic resin, or a melamine resin, or an inorganic film such as an oblique vapor deposition film of SiO is appropriately selected and used. The thickness is desirably set to 5 to 100 nm.

In the present invention, the partition member 15 is used for separately injecting a plurality of types of liquid crystals. The partition member 15 is a member originally intended to adhere the upper and lower substrates and maintain the cell gap, and is formed using an adhesive resin or the like. In particular, a photosensitive resin, for example, a commonly used resist is preferably used because of ease of patterning. Specifically, polyimide, polyamide, or PVA is preferably used. In the present embodiment, since the electrodes of the upper and lower substrates are formed in stripes, the cells can be divided into stripes by forming them in the gap between the electrodes 22 (FIG. 3B).

The method of manufacturing the above liquid crystal element is, for example, as follows. First, CVs are respectively placed on the substrates 11 and 21.
Electrodes 12 and 22 are formed by forming a conductive film by a vapor deposition method such as a D method, a sputtering method, or an ion plating method, and patterning the conductive film in a stripe shape. After forming the insulating layers 13 and 23 thereon by a vapor deposition method or a coating method, the alignment films 14 and 24 are formed by spin coating or the like.
A rubbing treatment is performed if necessary. An adhesive resin film is formed on one side (21) of the substrate thus obtained, and is patterned to form a partition member 15 between the electrodes 22. As shown in FIG. Seal material 31
Is drawn, the upper and lower substrates are arranged and stacked so that the electrodes 12 and 22 are orthogonal to each other, and are bonded by applying pressure and heating. The sealing material 31 is drawn except for one side of the substrate, and using this side as a liquid crystal injection port, a predetermined liquid crystal is attached to the opening of each region using a needle or the like, and the steps of injection and sealing are repeated. Liquid crystal is sequentially injected into each region by means of sealing.

The liquid crystal used in the present invention includes:
There is no particular limitation as long as the liquid crystal can utilize the above-described birefringence effect. For example, a chiral smectic liquid crystal such as a ferroelectric liquid crystal or an antiferroelectric liquid crystal is preferably used.

In the above embodiment, the liquid crystal element having the simple matrix structure has been described. However, the present invention is not limited to the liquid crystal element having the electrode structure.
The present invention can be applied to an active matrix type liquid crystal element using a switching element such as T.

It should be noted that the present invention is not limited to the configuration of the above-described embodiment, and that the configuration other than the configuration limited in the first aspect of the present invention is not limited to the conventional liquid crystal element as long as the effects of the present invention can be obtained. Technology can be applied.

[0025]

EXAMPLE As an example of the present invention, a liquid crystal device having the structure shown in FIG. 1 was manufactured.

First, an ITO film having a thickness of 1500 そ れ ぞ れ was formed on each of two glass substrates having a thickness of 1.1 mm by a sputtering method, and was patterned into stripes having a width of 170 μm and an interval of 30 μm to form transparent electrodes.

Further, as an insulating layer for preventing short circuit, T
a ₂ O ₅ is deposited to a thickness of 900 ° by a sputtering method,
Furthermore, a coating type insulating layer (Ti: Si
= 1: 1 (manufactured by Tokyo Ohka Co., Ltd.) so as to have a film thickness of 1200 ° and fired at 300 ° C. Further, Ti:
Fine particles of silica having an average particle diameter of 400 ° are previously dispersed in a 6.0% by weight solution of an insulating layer material having a composition of Si = 1: 1, and the solution is printed on a colored plate having a roughness of 5 μm. It was performed using. Thereafter, pre-baking is performed at 100 ° C. for about 10 minutes, UV irradiation is further performed, and further at 300 ° C. for about 1 minute.
A heat baking treatment was performed for a long time. The thickness of this insulating layer is 20
0 °.

A polyamic acid (“LQ1802” manufactured by Hitachi Chemical Co., Ltd.) is applied as an alignment film on the insulating layer by NMP (N-
Methyl pyrrolidone) / nBC (n-butyl cellosolve)
A solution diluted to 1.5% by weight with a liquid 1/1 was applied by a spinner under application conditions of 2000 rpm and 20 sec, and then baked at 270 ° C. for 1 hour.

The frame portion of the alignment film (the region outside the outermost periphery of the pixel for display) was covered with a metal mask and rubbed. As a result, the frame portion had a vertical orientation and the display portion had a horizontal orientation.

A PVA solution (manufactured by Toyo Gosei Kogyo Co., Ltd., "SPP-776") was applied to only one of the substrates by a spinner for 50 minutes.
Apply under the conditions of 0 rpm and 20 sec.
This was performed at 00 ° C. for 10 minutes, and UV irradiation was performed through a photomask to perform patterning in a stripe shape. Then 1
It was dried by heating at 30 ° C. for 30 minutes, and a partition member made of PVA mixed with conductive fine particles having a height of 3 μm was formed in the electrode gap.

A sealing material made of epoxy resin is drawn on the peripheral edge of the surface of the other substrate by screen printing,
Both substrates were overlapped so that the rubbing directions were substantially parallel, and were pressed, heated and bonded.

As liquid crystals, Δn = 0.17,
A pyrimidine-based ferroelectric liquid crystal exhibiting the following phase transition temperature and physical properties blended so as to be 0.2 or 0.23 is heated to an isotropic phase, and is attached to a predetermined region with a needle tip and sealed with the above liquid crystal. Each time, sealing was performed so that the above three kinds of liquid crystals were repeatedly arranged.

The adjustment of Δn was realized by changing the blend ratio of the pyrimidine-based ferroelectric liquid crystal. Specifically, Δn is increased by increasing the blend ratio of the aromatic three-ring component among the constituent components of the liquid crystal relative to the two-ring component.

[0034]

Embedded image

The above physical properties were measured as follows.

[Tilt angle θ] ± 30 to ± 50 V, 1-1
While applying an AC (alternating current) of 00 Hz through the electrodes between the upper and lower substrates of the liquid crystal element, the liquid crystal element disposed therebetween is rotated in parallel with the polarizing plate under crossed Nicols, and at the same time, the photomultiplier (Hamamatsu Photonics) The second extinction position (the position at which the transmittance becomes lowest) and the second extinction position are determined while detecting the optical response using the method described above. Then, 1/2 of the angle from the first extinction position to the second extinction position at this time is defined as the tilt angle.

[Inclination Angle δ of Liquid Crystal Layer] Basically, a method (Japan) performed by Clark or Lagerwal
Display '86, Sep. 30 to Oct. 2,
1986, 456-458) or the method of Ouchi et al. (JJAP 27 (5) (1988) 725-7).
It was measured by the same method as in 28). As a measuring apparatus, a rotating cathode type X-ray diffractometer (manufactured by MAC Science Co., Ltd.) is used. In order to reduce absorption of X-rays into a glass substrate of a liquid crystal cell, a microsheet (80) manufactured by Corning Inc. is used as a substrate.
μm).

[Spontaneous polarization Ps] Miyasato et al. "Direct measurement method of spontaneous polarization of ferroelectric liquid crystal by triangular wave" (Journal of the Japan Society of Applied Physics, 22, 10 (661))
1983, "Direct Method with
Triangular Waves for Measu
ring Spontaneous Polariza
Tion in Ferroelectric Liq
uid Crystal ”, as desscribed
by K. Miyasato et al. (Ja
p. J. Appl. Phys. 22. No. 10, L6
61 (1983))).

When a driving element was mounted on the above-mentioned liquid crystal element, and the matrix driving was performed while being sandwiched between a pair of polarizing plates, a good color display was realized.

Comparative Example 1 For comparison, a sample having a color filter was prepared, and the transmittance was compared. A comparative sample was prepared in the same manner as in Example 1 except that a color filter was provided under the transparent electrode, a partition member was not formed, and a liquid crystal of Δn = 0.066 was injected.

Hereinafter, a method of forming a color filter will be described.

In this comparative example, the color filters formed green (G), red (R), and blue (B). Examples of the forming method include a dyeing method, a pigment dispersion method, and an electrodeposition method. In this comparative example, the pigment dispersion method was used. A color resist of a photosensitive resin in which a desired pigment was dispersed was applied on a substrate on which a light-shielding layer (black stripe) was formed, leveled at a constant temperature, and prebaked at about 80 ° C. Then 200 ~
Exposure was at 1000 mJ. Since the sensitivity was different for R, G, and B, the exposure time was adjusted by changing the exposure time. After the exposure, the film was developed with a developing solution, method and temperature according to the resist material, and was post-baked and washed. Each color filter was formed with a gap of several μm so as not to be in contact with the previously formed light shielding layer and the adjacent color filter. Further, the whole was formed so as to be wider than the display region and not to be applied to a sealant described later. Further, the above-described forming steps were sequentially performed for each color.

The amount of transmitted light when the sample of the example and the sample of the comparative example were displayed in all white was compared using the same backlight.

[0044]

[Table 1]

From the above results, it was found that the sample of the example can obtain three times or more the amount of transmitted light as compared with the sample of the comparative example having a color filter. This is because in the comparative example sample having a color filter, the transmitted light is cut off by each color filter of the color filter.

[0046]

As described above, according to the present invention, it is possible to provide a color liquid crystal element capable of simultaneously realizing excellent viewing angle characteristics and bright color display, and to be widely applied to various fields as a display device. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional view of one embodiment of a liquid crystal element of the present invention.

FIG. 2 is a schematic plan view showing a configuration of an electrode and a partition member of the liquid crystal element of FIG.

FIG. 3 is a schematic plan view illustrating an electrode configuration of each substrate of the liquid crystal element of FIG. 2;

FIG. 4 is a diagram showing a difference in wavelength-transmitted light characteristic due to a difference in retardation value according to the present invention.

[Explanation of symbols]

 11, 21 Substrate 12, 22 Electrode 13, 23 Insulating layer 14, 24 Alignment film 15 Partition member 16a to 16c Liquid crystal 31 Sealing material 32 Sealing material

Claims (7)

[Claims] 1. A liquid crystal element comprising a pair of substrates each having an electrode, wherein a liquid crystal is sandwiched between said pair of substrates. A plurality of liquid crystals that transmit or reflect different wavelengths are injected into predetermined regions separated by the partition members so as to have a predetermined pattern arrangement. Color liquid crystal element. 2. The color liquid crystal device according to claim 1, wherein the plurality of types of liquid crystals have different birefringences. 3. The color liquid crystal device according to claim 1, wherein the partition member is made of an adhesive resin. 4. The color liquid crystal device according to claim 3, wherein said adhesive resin is polyamide, polyimide or PVA. 5. The color liquid crystal device according to claim 1, wherein the liquid crystal is a chiral smectic liquid crystal. 6. The liquid crystal according to claim 5, wherein said liquid crystal is a ferroelectric liquid crystal.
The color liquid crystal element according to the above. 7. The color liquid crystal device according to claim 5, wherein said liquid crystal is an antiferroelectric liquid crystal.