JP2002296583A - Light scattering type liquid crystal element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light scattering type liquid crystal element by which bright white display is made possible without using a backlight and which is free from character blur and double image by the parallax even in fine characters and figures and has high visibility. SOLUTION: The light scattering type liquid crystal element having two transparent substrates each having an electrode layer, a light controlling layer consisting of a liquid crystal and a transparent solid substance between the substrates, a reflection layer and a light absorbing layer both provided in this order on the back side of the light controlling layer when viewed from an observer and an air layer between the transparent substrate on the back side and the reflection layer is characterized in that the interval between the light controlling layer and the reflection layer is four times as long as the shorter side of a pixel electrode or less and the light controlling layer and the reflection layer have <=0.8 mm interval therebetween.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light scattering type liquid crystal device having a light control layer containing a liquid crystal and a transparent solid substance without using a polarizing plate. The present invention relates to a light-scattering type liquid crystal element capable of electrically scanning transmission at low voltage. The light-scattering type liquid crystal element of the present invention displays characters and figures, and by electrically switching the display, is particularly excellent in visibility, digital paper and electronic newspaper,
E-books, display devices for computer terminals with low power consumption, decorative display boards and clocks for advertising boards, etc., display devices for calculators,
It can be used as a display device requiring a bright screen.

[0002]

2. Description of the Related Art As a display element using liquid crystal, a polarizing plate, an alignment film, and a TN liquid crystal element and an STN liquid crystal element requiring an alignment treatment are widely used. Such a liquid crystal display element is a reflection type liquid crystal display element that reflects and uses external natural light or light from an indoor light source, and a transmission type that uses and transmits light from a light source provided on the back side of a liquid crystal layer. There is a liquid crystal display element.

[0003] A transmissive type having a backlight on the back side can provide a bright display, but has a problem that the backlight is large in volume and consumes a large amount of power. On the other hand, the reflection type does not have such a problem, but has a problem that the display itself is dark and the display contrast is low because the light absorption by the polarizing plate or the like is large.

[0004] As a method of solving such a problem, Japanese Patent Publication No. 58-501631 and Japanese Patent Publication No. 63-501 are disclosed.
No. 512 proposes some light-scattering liquid crystal elements utilizing light scattering by dispersing liquid crystal in a polymer resin.

When a light-scattering type liquid crystal element is used as a reflection type, when no voltage is applied, light from the outside is scattered to obtain a white display, and a black body or the like is formed on the back side of the liquid crystal film as viewed by an observer. When the voltage is applied, the light absorbing film becomes transparent so that the light absorbing film such as a black body can be seen and a black display can be obtained. In this method, a display image is bright because a polarizing plate having a large absorption is not required, and a display that does not require a backlight can be performed.

In order to further improve the brightness of the light-scattering type liquid crystal element, an air layer or a dielectric layer is provided behind the element as disclosed in Japanese Patent Application Laid-Open No. Sho 59-178428, and a certain angle or more is provided. In order to improve the display contrast, the light incident on the above-mentioned layer is totally reflected and only the light incident at an angle smaller than that is transmitted. However, this method does not reach a level that enables bright white display.

Also, as disclosed in Japanese Patent Application Laid-Open No. 9-133917, behind a light-scattering type liquid crystal element, the refractive index is smaller than the transparent substrate by 0.4 or more and the thickness is 1 μm or less.
A low-refractive-index layer of 1 mm is provided, and the light reflectance of light having a wavelength of 550 nm incident on the back surface at an incident angle of 5 degrees is 5 to 5.
A method of providing a transflective layer having a light absorption of 40% or less and 20% or less has been proposed.

According to this method, a bright white display is possible. However, when displaying fine characters and figures, light is reflected by the semi-transmissive reflection layer. There are problems such as heavy visibility and poor visibility.

Further, a method has been proposed in which a semi-transmissive reflection layer is directly provided on the inside or outside of the rear substrate of the light scattering type liquid crystal element. In this method, parallax can be prevented by reducing the thickness of the rear substrate, but there is a problem that the transflective layer is seen through and the white display is different.

[0010]

The problem to be solved by the present invention is that bright white display is possible without a backlight, and even fine characters and figures are blurred due to parallax or appear double. An object of the present invention is to provide a light-scattering type liquid crystal element having high visibility without any problem.

[0011]

Means for Solving the Problems As a result of intensive studies to solve the problems, the present inventors have found that the above problems can be solved if the distance between the light control layer and the reflection layer is a specific distance. As a result, the present invention has been completed.

That is, the present invention relates to a transparent transparent electrode having an electrode layer.
A substrate and a dimming layer composed of a liquid crystal and a transparent solid substance between these substrates, and a reflection layer and a light absorbing layer are provided in this order on the back side of the dimming layer as viewed from an observer, Further, in a light scattering type liquid crystal device having an air layer between the transparent substrate on the back side and the reflective layer, the distance between the dimming layer and the reflective layer is four times or less the short side of the pixel electrode, and 0.8 between reflective layers
mm or less, which is a light scattering type liquid crystal element.

Further, according to the present invention, the reflectance of the reflection layer is 4
A light-scattering liquid crystal element characterized by being 5 to 60% of light having a wavelength of 00 to 650 nm, and in particular, a light wherein the thickness of the rear transparent substrate is 0.7 mm or less. It also includes a scattering type liquid crystal element.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic diagram of a cross section of a light scattering type liquid crystal device of the present invention. In FIG. 1, 1 indicates a transparent substrate, 2 indicates a transparent electrode, 3 indicates a dimming layer composed of a liquid crystal and a transparent solid substance, 5 indicates a reflective layer, 6 indicates a light absorbing layer, and is observed. From the viewpoint of the user, there are four air layers between the transparent substrate and the reflective layer on the back side of the light control layer.

In the present invention, the distance between the reflective layer and the light control layer means the total distance of the thickness of the transparent electrode, the transparent substrate, and the air layer on the back side of the light control layer. Also,
The pixel electrode means a minimum unit of the liquid crystal element in which the transmittance and the reflectance change electro-optically among the electrodes formed in a matrix. In an active drive or passive drive liquid crystal element or the like, a pixel electrode has a shape approximating a rectangle, and the short side of the pixel electrode means a short side when approximating the rectangle.

In general, a light-scattering type liquid crystal element having a dimming layer composed of a liquid crystal and a transparent solid substance and controlling the transmission and scattering of light by an electric field effect is a liquid crystal in contact with the transparent solid substance when no voltage is applied. Since the alignment state is parallel to the transparent solid substance interface or has a tilt angle, the alignment state is random as a whole. Therefore, a refractive index difference occurs between the liquid crystal domains. Further, there is a refractive index difference between the liquid crystal and the transparent solid substance. Due to the effect of the difference between the two refractive indices, the light control layer scatters light when no voltage is applied, and a white display is obtained.

On the other hand, when a sufficiently high voltage is applied to the light control layer, the liquid crystal in the light control layer is uniformly aligned in the direction of the electric field, so that the difference in the refractive index between the liquid crystal domains disappears. Further, if the refractive index of the transparent solid substance is made to match the ordinary light refractive index (n ₀ ) of the liquid crystal, the difference in the refractive index between the liquid crystal and the transparent solid substance also disappears. Thus, when a sufficiently high voltage is applied, the refractive index in the light control layer becomes substantially the same, and the light control layer becomes transparent. Thereby, black display can be achieved by providing the light absorbing layer as a black body on the back side of the liquid crystal film as viewed from the observer. Thus, in the case of a light scattering type liquid crystal element,
Black-and-white display is possible by applying no voltage.

FIG. 2 is a schematic diagram showing paths of incident light and scattered light when a voltage is applied to one pixel electrode in the light scattering type liquid crystal element of FIG. In a portion where no voltage is applied, light incident on the light control layer is scattered, and forward scattered light (9) (light scattered to the side opposite to the observer side) and back scattered light (10) (observer side) Scattered light).

Among the forward scattered light (9), a part of the light transmitted through the transparent substrate is reflected by the reflection layer, enters the light control layer again, and is scattered again. Then, there is light (11) emitted to the observer side. The light emitted to the observer side is (1)
The light is the sum of (0) and (11), and this light-scattering type liquid crystal element can perform bright white display. Further, of the light of (11), since the distance between the reflection layer and the light control layer is small, the light incident on the voltage application portion is very small.

Light incident on the portion to which the voltage is applied is partially reflected (12) by the reflection layer. Since the distance between the light control layer and the reflective layer is small, the light of (12) passes through the portion where the voltage is applied and returns to the observer side. Therefore, even when fine characters, figures, and the like are displayed, the characters and figures hardly appear blurred or doubled. As described above, the light-scattering type liquid crystal element of the present invention is a light-scattering type liquid crystal element capable of bright white when no voltage is applied and having good visibility.

FIG. 3 is a schematic diagram showing the paths of incident light and scattered light when a voltage is applied to one pixel electrode when the distance between the light control layer and the reflective layer is large. In the portion where the voltage is not applied in FIG. 3, the light incident on the light control layer is divided into forward scattered light (9) and back scattered light (10) by the light control layer. Of the forward scattered light (9), a part of the light transmitted through the transparent substrate is reflected by the reflective layer, enters the light control layer again, and is scattered again. And it becomes the light (11) emitted to the observer side.

However, since the distance between the light control layer and the reflective layer is large, a part of (11) transmits through a part to which a voltage is applied. Therefore, when displaying fine characters and figures,
The outline of a character or figure is blurred or appears double.
The light incident on the portion to which the voltage is applied is partially reflected (12) by the reflection layer. Since the distance between the light control layer and the reflective film is large, the light of (12) is not transmitted through the portion where the voltage is applied, but is incident on the portion where no voltage is applied.

Therefore, when a black body is provided as a light absorbing layer on the back side of the light control layer as viewed from the observer, the observer has a portion where black display on the back cannot be seen. Therefore, when displaying fine characters, figures, and the like, the outline of the characters and figures looks blurred, and the visibility is very poor.

When displaying fine characters and figures, the smaller the distance between the light control layer and the reflective layer, the higher the visibility. However, if the thickness of the rear-side transparent substrate is too small, problems arise in strength and uniformity of the interval between the glass substrates. Further, in the case where there is a gap between the rear transparent substrate and the reflective layer, if the gap is too thin, it becomes difficult to maintain the gap over a large area.

Furthermore, the smaller the size of the pixel electrode, the greater the effect of parallax. Therefore, the smaller the size of the pixel electrode, the smaller the distance between the light control layer and the reflective layer. Examples of the liquid crystal element having a small pixel electrode include an active driving liquid crystal element. In the case of the active driving liquid crystal element, the short side of the pixel electrode is generally 200 μm or less.

When the size of the short side of the pixel electrode is 200 μm or less, for example, in the experiment by the inventors when the short side of the pixel electrode is about 100 μm, dimming is performed on the short side of the pixel electrode. When the distance between the layer and the reflective layer was about 3.5 times, the visibility was hardly reduced due to parallax. However, when the distance between the light control layer and the reflective layer was 7.5 times, the parallax was low. Clearly reduced the visibility.

Further, when the short side of the pixel electrode is about 200 μm,
When the distance between the light control layer and the reflective layer was set to about 3.75 times the short side of the pixel electrode, almost no decrease in visibility due to parallax was observed. 5.75 spacing
When the magnification was doubled, the visibility was clearly reduced due to the parallax.

The size of the short side of the pixel electrode is 200 μm.
If it is larger, for example, the short side of the pixel electrode is about 400 μm
When the distance between the light control layer and the reflective layer is about 0.8 mm,
Although almost no decrease in visibility due to parallax was observed, when the distance between the light control layer and the reflective layer was about 1.2 mm, the visibility was clearly reduced due to parallax. For this reason, the distance between the light control layer and the reflective layer is four times or less the short side of the pixel electrode,
Further, it is desirable that the distance between the light control layer and the reflective layer is 0.8 mm or less.

Further, it is desirable that the reflection layer used has a reflectance of 5 to 60% with respect to light of 400 to 650 nm incident on the reflection layer. If the reflectance is higher than 60%, the colored display of the light absorbing layer may be difficult to see in the transparent state, and if it is lower than 5%, it is difficult to obtain sufficient luminance for bright white display.

In order to reflect the scattering component of the light in the light control layer more efficiently, the reflection layer is formed such that the value of the light reflectance increases as the angle of incidence on the layer increases. The refractive index of the layer,
Optical design generally performed, such as adjustment of the film thickness and formation of a multilayer film, may be performed.

These reflective layers are made of Ag, Al, AlSi formed by vapor deposition, sputtering, coating or the like.
_{N, TiO 2, Al 2 O} 3, ZnO 2, Ta 2 O 5, S
A single-layer film of a metal such as nO ₂ or SiO ₂ or a metal oxide, a thin film of a multilayer film, a polymer resin film, or the like can be used. These reflective layers may be formed directly on the light absorbing layer, or may be formed on another transparent substrate and used as the reflective layer.

In order to control the distance between the substrate on the rear side and the reflective layer as viewed from the observer, spacers made of plastic or glass may be appropriately dispersed between the substrate on the rear side and the reflective layer. As the light absorbing layer, a black plate, a color coloring plate, a color coloring film, or the like can be used, and it is desirable that the light absorption rate in a necessary absorption wavelength region is high.

Further, a glass, plastic, metal substrate or the like having a surface coated or printed with a light absorbing agent, a color paint or the like can be used. Note that the absorption wavelength range of the light absorbing layer may be changed, such as blue, red, and green, based on the necessity of display.

The transparent substrate used for the liquid crystal element in the present invention may be a rigid material, for example, glass or the like, or a flexible material, for example, a plastic film. The two substrates are to be obtained facing each other at an appropriate distance. They must be transparent and allow the multilayer structure sandwiched between the two to be visible from the outside world, but this does not require complete transparency.

The thickness of the transparent substrate on the back side is preferably 0.7 mm or less so as not to lower the visibility, and the thinner is desirable. However, if the rear substrate is too thin, problems occur in strength and uniformity of the interval between the two substrates. Therefore, the thickness of the rear substrate may be selected as appropriate depending on its material or the like. ,
A PET film is used.

In order to suppress the reflection of external light on the element surface, which is a factor of deteriorating the display contrast, the light incident surface of the transparent substrate on the observer side, that is, on the light incident side,
An antireflection layer may be laminated. A transparent electrode may be disposed on the entire surface or a part of the substrate depending on the purpose.
In addition, for each pixel electrode, a thin film transistor (TFT), a thin film diode, a metal insulator, a metal non-linear resistance element (MIM)
An active matrix substrate provided with an active element such as the above may be used.

In order to control the thickness of the light control layer composed of the liquid crystal and the transparent solid substance, a spacer for maintaining a space may be interposed between the two substrates in the same manner as in a known liquid crystal device. Good. The spacer may be mixed with a solution of a polymerizable composition comprising a liquid crystal material, a polymerizable compound, and a photopolymerization initiator, or may be applied on a substrate. As the spacer, for example, those for various liquid crystal cells such as silica, alumina, rod-type glass fiber, glass beads, and polymer beads can be used without any particular limitation.

The liquid crystal material used in the present invention does not need to be a single liquid crystal compound. Characteristics of liquid crystal materials, that is, phase transition temperature, melting point, viscosity, Δ of isotropic liquid and liquid crystal
For the purpose of improving n, Δε, solubility with a polymerizable compound, and the like, a composition of two or more liquid crystal compounds may be used, and may be appropriately selected and blended. Usually, any material may be used as long as it is recognized as a liquid crystal material in this technical field, and it is sufficient if the manufactured optical element is a liquid crystal capable of obtaining good characteristics.

As the liquid crystal material used in the present invention, a nematic liquid crystal, a smectic liquid crystal, a cholesteric liquid crystal and the like are preferable, and a nematic liquid crystal is particularly preferable. In order to improve the performance, a cholesteric liquid crystal, a chiral nematic liquid crystal, a chiral smectic liquid crystal, a chiral compound, or the like may be included.

These liquid crystal materials include benzoic acid ester type, cyclohexanecarboxylic acid ester type, biphenyl type, terphenyl type, phenylcyclohexanoic acid type, pyrimidine type, pyridine type, dioxane type, cyclohexanecyclohexane ester type, tolan type, and the like. A liquid crystal compound represented by the following general formula (1) such as an alkenyl type, a fluoro type, a cyano type, and a naphthalene type can be used. General formula (1)

[0041]

Embedded image

(Wherein, rings A, B and C each independently represent any one of the rings shown in Chemical formula 2)

[0043]

Embedded image

N is an integer of 0 to 2; m is an integer of 1 to 4;
1 and Y2 are, each independently, a single bond, -CH ₂ C
H ₂ —, —CH ₂ O—, —COO—, —OCO—, —C}
C-, -CH = CH-, -CF = CF-,-(-C
_{H 2) 4 -, - CH} 2 CH 2 CH 2 O-, or -CH ₂ = CH
Represents CH ₂ —, and Y 3 represents a single bond, —COO—, or —
Represents OCO-, and R independently represents a hydrogen atom, a halogen atom, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group, an alkenyl group, an alkenyloxy group, a fluoroalkyl group, or a fluoroalkoxy group. It is preferable to use a liquid crystal material including a tolan liquid crystal and a cyano liquid crystal.

The polymerizable compound used in the present invention includes
For example, ethyl (meth) acrylate, butyl (meth)
Acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate,
Isomiristyl (meth) acrylate, isostearyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, methyl carbitol (meth) acrylate, ethyl carbitol (meth) acrylate, cyclohexyl (meth) acrylate,

Isobornyl (meth) acrylate, 2-
Hydroxyethyl (meth) acrylate, phenoxy (meth) acrylate, methoxydipropylene glycol (meth) acrylate, trifluoroethyl (meth)
Acrylate, dimethylamino (meth) acrylate,
Morpholinoethyl (meth) acrylate, perfluoroalkyl (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate,

Polybutylene glycol di (meth) acrylate, aliphatic di (meth) acrylate, epichlorohydrin-modified 1,6-hexanediol di (meth) acrylate, dicyclopentenyl di (meth) acrylate,
Bisphenol A di (meth) acrylate, epichlorohydrin-modified bisphenol A di (meth) acrylate, ethylene oxide-modified bisphenol A di (meth) acrylate, propylene oxide-modified bisphenol A di (meth) acrylate,

Butylene oxide-modified bisphenol A
Di (meth) acrylate, 3,3-dimethylolpentanedi (meth) acrylate, 3,3-dimethylolheptanedi (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, pentaerythritol tri (meth) acrylate Acrylic ester monomers such as pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate;

N, N-dimethylacrylamide, N, N
Acrylamide compounds such as dimethylaminopropylacrylamide, urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, oligoester acrylate, hydroxybivalate neopentylglycol di (meth) acrylate, caprolactone-modified hydroxyviva Phosphate ester neopentyl glycol di (meth) acrylate,

Trimethylolpropane tri (meth) acrylate, ethylene oxide-modified trimethylolpropane tri (meth) acrylate, propylene oxide-modified trimethylolpropane tri (meth) acrylate, fluorinated alkyldi (meth) acrylate, (Meth) acrylate having an alkyl group in a side chain,

As the maleimide compound, a compound in which a maleimide group is bonded by an aliphatic group is preferable. Specifically, N-hexylmaleimide or N, N'-4,9-
Alkyl or alkyl ether maleimides such as dioxa-1,12-bismaleimide dodecane, ethylene glycol bis (maleimide acetate), poly (tetramethylene glycol) bis (maleimido acetate),
Maleimide carboxylic acid (poly) alkylene glycol esters such as tetra (ethylene glycol-modified) pentaerythritol tetra (maleimido acetate);

Examples thereof include carbonate maleimides such as bis (2-maleimidoethyl) carbonate and urethane maleimides such as isophoronebisurethanebis (N-ethylmaleimide), but are not particularly limited thereto.

Among the polymerizable compounds used in the present invention, (meth) acrylates having an alkyl group having 5 to 25 carbon atoms in the side chain are particularly preferably used. Here, carbon number 5
The main chain structure of the (meth) acrylate having 25 alkyl groups in the side chain is not particularly limited as long as it is a structure used as a normal acrylate. The number of side chain groups may be one or more per one molecule of (meth) acrylate having an alkyl group having 5 to 25 carbon atoms in the side chain.

The number of functional groups in one molecule of the (meth) acrylate having an alkyl group having 5 to 25 carbon atoms in the side chain may be two or more, and the number is not particularly limited. When increasing the polymerization rate of a polymerizable composition comprising a material, a polymerizable compound, and a photopolymerization initiator, the number of functional groups may be increased, and a light-scattering type liquid crystal device after production can obtain favorable characteristics. You can select it as appropriate.

As the polymerizable compound used in the present invention, one type of polymerizable compound may be used as long as the effects of the present invention are not impaired, or two or more types of polymerizable compounds may be used in combination. And may further contain known and commonly used monofunctional (meth) acrylates. The polymerizable compound may be a uniform solution or may be non-uniform, but preferably a uniform solution. It is also possible to mix the liquid crystal with the liquid crystal in an uncured state, and the mixture mixed with the liquid crystal is preferably a uniform solution.

The mixing ratio of the liquid crystal and the polymerizable compound forming the transparent solid substance is an important factor in controlling the average gap in the light control layer. : 1, preferably in the range of 6: 4 to 8: 2.

As means for polymerizing the polymerizable compound,
Energy rays such as heat and ultraviolet rays can be used.
In the case of thermal polymerization, a thermal polymerization initiator is required as a polymerization initiator, for example, benzoyl peroxide, 2,4-
Dichlorobenzoyl peroxide, 1,1-di (tert-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4′-di (tert-butylperoxy) valerate, dicumyl peroxide Peroxides; azo compounds such as 7-azobisisobutylnitrile; and tetramethylthiuram disulfide.

When an ultraviolet ray is used as an active energy ray, a photopolymerization initiator is usually required as a polymerization initiator. However, when maleimide is used for the polymerizable functional group of the polymerizable compound, a photopolymerization initiator is not particularly required.

Photopolymerization initiators can be broadly classified into two types: an intramolecular bond cleavage type and an intramolecular hydrogen abstraction type. Examples of the former include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1 -One, 4- (2-hydroxyethoxy) phenyl- (2-
(Hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1- (4- Acetophenones such as morpholinophenyl) -butanone;

Benzoin such as benzoin, benzoin isopropyl ether and benzoin isobutyl ether; acyl phosphine oxide such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide; benzyl and methylphenylglyoxyester.

On the other hand, examples of the latter include benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4,4'-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenylsulfide, acrylated Benzophenone, 3,3 ', 4,4'-tetra (t-butylperoxycarbonyl) benzophenone, 3,3'-dimethyl-
Benzophenones such as 4-methoxybenzophenone;

2-isopropylthioxanthone, 2,4
Thioxanthones such as dimethylthioxanthone, 2,4-diethylthioxanthone and 2,4-dichlorothioxanthone; aminobenzophenones such as Michler's ketone and 4,4'-diethylaminobenzophenone;
-Butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, camphorquinone and the like.

The amount of the polymerization initiator to be added is preferably in the range of 0.01 to 10% by weight, particularly preferably in the range of 0.5 to 5% by weight in the polymerizable compound. In addition, the energy rays referred to here include ultraviolet rays, electron beams, ionizing radiation such as α-rays, β-rays, and γ-rays, visible rays, microwaves, high frequencies, and the like.
In particular, a photopolymerization method using ultraviolet light is preferable, and further, while maintaining the light modulating layer forming material in an isotropic liquid state, it is possible to instantaneously irradiate strong ultraviolet light to promote polymerization of the transparent solid substance. This is effective in forming a uniform size of the average gap space in the light control layer.

[0064]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. However, the invention is not limited to these examples. In the following examples, “%” and “parts” represent “% by weight” and “parts by weight”, respectively, unless otherwise specified.

The voltage-reflectance characteristics are determined by using Display Measuring
Using the diffuse light source of System DMS501 (manufactured by AUTONIC),
The reflectance of the standard white plate is set to 100%, the reflectance of the standard black plate is set to 0%, and the standard black plate is installed on the back of the light scattering type liquid crystal element to receive light in the direction of 0 ° with respect to the normal line of the cell. did. The applied voltage was measured by applying a voltage of 0 to 45 V in 0.15 V steps. Each of the evaluation characteristics means the following symbols and contents.

L0: White turbidity-reflectance when no voltage is applied (%) L100: Transparency-reflectance (%) when a voltage at which the liquid crystal is sufficiently oriented in the electric field direction is applied. V90: Drive voltage-L0 is 100 % And L100 is 0
%, The applied voltage value when the reflectance becomes 10% (vrms)

Example 1 A short side of about 10 was formed on a glass substrate.
The 0 μm ITO pixel electrode was arranged in a character shape. The two glass substrates (thickness about 0.7 mm on the observer side and about 0.3 mm on the back side) are positioned so that the positions of the character-shaped ITO pixel electrodes are almost the same, and the distance between the glasses using a spacer. Was about 11 μm.

70% of a liquid crystal material (manufactured by Dainippon Ink and Chemicals, Inc.) having a tran skeleton between glass substrates, an ECH-modified 1,6-hexanediol diacrylate having a main chain skeleton of 70%,
29.4% of an acrylate having 2 side chain groups and 11 alkyl side chain groups (Dainippon Ink & Chemicals, Inc.) and "C101" (manufactured by Toagosei Co., Ltd.) as a polymerization initiator.
6% of a polymerizable composition was injected, and the entire substrate was
It was kept at 5 ° C.

An ultraviolet ray of 400 W / m ² was irradiated through a UV cut filter, UV 35 (manufactured by Toshiba Glass Co., Ltd.) for 60 seconds to cure the polymerizable composition and obtain a light control layer sandwiched between glass substrates.

Aluminum is vacuum-deposited on a glass substrate having a thickness of 0.5 mm to form a reflective layer having a reflectance of about 50% with respect to light of 400 to 650 nm, and a light absorbing layer is formed on the opposite surface. A substrate on which a reflection layer and an absorption layer were formed was obtained. After dispersing the spacers so that the distance between the rear glass substrate and the reflective layer was about 50 μm, they were bonded together to obtain a light-scattering liquid crystal element in which the distance between the light control layer and the reflective layer was about 350 μm.

The electro-optical characteristic of this optical element is L0 = 4
2.7 (%), L100 = 1.08 (%), V90 = 7.3
It was 2 Vrms. Further, when a voltage of V90 was applied and the display was observed, clear characters were observed and the visibility was high.

Example 2 A short side of about 20 was formed on a glass substrate.
The 0 μm ITO pixel electrode was arranged in a character shape. The two glass substrates (thickness about 0.7 mm on the observer side and about 0.7 mm on the back side) are positioned so that the positions of the character-shaped ITO pixel electrodes are almost the same, and the distance between the glasses using a spacer. Was about 11 μm. A light control layer was formed between the glass substrates in the same manner as in Example 1.

Further, using the same substrate on which the reflecting layer and the absorbing layer were formed as in Example 1, spacers were dispersed so that the distance between the rear glass substrate and the reflecting layer was about 50 μm.
By sticking together, a light scattering type liquid crystal element having a distance between the light control layer and the reflection layer of about 750 μm was obtained. The electro-optical characteristics of this optical element are as follows: L0 = 43.3 (%), L100 = 1.17 (%),
V90 = 7.14 Vrms. Further, when a voltage of V90 was applied and the display was observed, clear characters were observed and the visibility was high.

(Embodiment 3) A short side of about 40 on a glass substrate
The 0 μm ITO pixel electrode was arranged in a character shape. The two glass substrates (thickness about 0.7 mm on the observer side and about 0.7 mm on the back side) are positioned so that the positions of the character-shaped ITO pixel electrodes are almost the same, and the distance between the glasses using a spacer. Was about 11 μm. A light control layer was formed between the glass substrates in the same manner as in Example 1.

Further, using the same substrate on which the reflection layer and the absorption layer were formed as in Example 1, spacers were dispersed so that the distance between the rear glass substrate and the reflection layer was about 100 μm, and the substrates were adhered together. The distance between the optical layer and the reflective layer is about 800μ
m light-scattering type liquid crystal element was obtained. The electro-optical characteristics of this optical element are as follows: L0 = 40.3 (%), L100 = 0.98
(%), V90 = 6.95 Vrms. Further, when a voltage of V90 was applied and the display was observed, clear characters were observed and the visibility was high.

Example 4 A short side of about 20 was formed on a glass substrate.
0 μm ITO pixel electrodes were arranged in a character shape. The two glass substrates (thickness about 0.7 mm on the observer side and about 0.7 mm on the back side) are positioned so that the positions of the character-shaped ITO pixel electrodes are almost the same, and the distance between the glasses using a spacer. Was about 11 μm. A light control layer was formed between the glass substrates in the same manner as in Example 1.

Aluminum is vacuum-deposited on a glass substrate having a thickness of 0.5 mm to form a reflective layer having a reflectance of about 25% with respect to light of 400 to 650 nm, and a light absorbing layer is formed on the opposing surface to form a reflective layer. And a substrate on which an absorption layer was formed. After dispersing the spacers so that the distance between the back glass substrate and the reflective layer was about 50 μm, they were laminated to obtain a light-scattering liquid crystal element in which the distance between the light control layer and the reflective layer was about 750 μm. The electro-optical characteristic of this optical element is L0 = 26.1.
9 (%), L100 = 0.71 (%), V90 = 6.79V
rms. Further, when a voltage of V90 was applied and the display was observed, clear characters were observed and the visibility was high.

(Example 5) On a glass substrate having a thickness of about 0.7 mm and a plastic film substrate having a thickness of about 0.2 mm, ITO pixel electrodes having a short side of about 70 μm were arranged in a character shape. Two substrates (thickness of about 0.7 mm on the observer side and about 0.2 mm on the back side) were adhered so that the positions of the character-shaped ITO electrodes were almost the same, and the interval was about 11 μm. . A light control layer was formed between the substrates in the same manner as in Example 1.

Further, using the same substrate on which the reflection layer and the absorption layer were formed as in Example 1, spacers were dispersed so that the distance between the rear glass substrate and the reflection layer was about 50 μm.
By laminating, a light scattering type liquid crystal element having a distance between the light control layer and the reflection layer of about 250 μm was obtained. The electro-optical characteristics of this optical element are as follows: L0 = 38.2 (%), L100 = 1.21 (%),
V90 was 7.89 Vrms. Further, when a voltage of V90 was applied and the display was observed, clear characters were observed and the visibility was high.

Comparative Example 1 A short side of about 10 was formed on a glass substrate.
The 0 μm ITO pixel electrode was arranged in a character shape. The positions of the character-shaped ITO pixel electrodes of the two glass substrates (about 0.7 mm thick on the observer side and about 0.7 mm thick on the back side) almost coincide with each other. About 1
Lamination was performed so as to be 1 μm. A light control layer was formed between the glass substrates in the same manner as in Example 1.

Further, using the same substrate on which the reflection layer and the absorption layer were formed as in Example 1, spacers were dispersed so that the distance between the rear glass substrate and the reflection layer was about 50 μm, and the substrates were stuck together to adjust the light. A light-scattering type liquid crystal device in which the distance between the layer and the reflective layer was about 750 μm was obtained. The electro-optical characteristics of this optical element are as follows: L0 = 42.5 (%), L100 = 1.13 (%),
V90 = 7.23 Vrms. Further, when a voltage of V90 was applied and the display was observed, the outline of the character was blurred or doubled, resulting in low visibility.

Comparative Example 2 A short side of about 20 was formed on a glass substrate.
The 0 μm ITO pixel electrode was arranged in a character shape. The two glass substrates (thickness on the observer side, about 0.7 mm, thickness on the back side, about 1.1 mm) are almost coincident with the positions of the character-shaped ITO pixel electrodes. About 1
Lamination was performed so as to be 1 μm. A light control layer was formed between the glass substrates in the same manner as in Example 1.

Further, using the same substrate on which the reflection layer and the absorption layer were formed as in Example 1, spacers were dispersed so that the distance between the rear glass substrate and the reflection layer was about 50 μm, and the substrates were stuck together. A light-scattering type liquid crystal device in which the distance between the layer and the reflective layer was about 1150 μm was obtained. The electro-optical characteristics of this optical element are as follows: L0 = 42.3 (%), L100 = 1.01 (%),
V90 = 7.02 Vrms. Further, when a voltage of V90 was applied and the display was observed, the outline of the character was blurred or doubled, resulting in low visibility.

(Comparative Example 3) A short side of about 40 was formed on a glass substrate.
The 0 μm ITO pixel electrode was arranged in a character shape. The two glass substrates (thickness on the observer side, about 0.7 mm, thickness on the back side, about 1.1 mm) are almost coincident with the positions of the character-shaped ITO pixel electrodes. About 1
Lamination was performed so as to be 1 μm. A light control layer was formed between the glass substrates in the same manner as in Example 1.

Further, using the same substrate on which the reflection layer and the absorption layer were formed as in Example 1, spacers were dispersed so that the distance between the rear glass substrate and the reflection layer was about 100 μm.
The distance between the light control layer and the reflective layer is about 1200μm
Was obtained. The electro-optical characteristics of this optical element are as follows: L0 = 39.9 (%), L100 = 1.20
(%), V90 = 6.98 Vrms. Further, when a voltage of V90 was applied and the display was observed, the outline of the character was blurred or doubled, resulting in low visibility.

Comparative Example 4 A short side of about 20 was formed on a glass substrate.
The 0 μm ITO pixel electrode was arranged in a character shape. The positions of the character-shaped ITO electrodes on the two glass substrates (about 0.7 mm thick on the observer side and about 0.7 mm thick on the back side) almost match, and the distance between the glasses is about 11 μm. It was stuck to. Aluminum is vacuum-deposited directly on the back side glass substrate, and about 25% in light of 400 to 650 nm.
And a light absorbing layer was further formed.

A liquid crystal material having a tran skeleton between glass substrates (manufactured by Dainippon Ink and Chemicals, Inc.) 70%, a main chain skeleton of which is ECH-modified 1,6-hexanediol diacrylate;
29.4% of an acrylate having two side chain groups and 11 side chain alkyl groups (Dainippon Ink and Chemicals)
And "C101" (manufactured by Toagosei Co., Ltd.) as a polymerization initiator
A polymerizable composition of 0.6% was injected and the entire substrate was kept at about 25 ° C.

From the glass substrate side on the observer side, 400 W /
The polymerizable composition was cured by irradiating ultraviolet rays of m ² through a UV cut filter: UV35 (manufactured by Toshiba Glass Co., Ltd.) for 60 seconds to obtain a light scattering type liquid crystal device. The electro-optical characteristics of this optical element are as follows: L0 = 20.3 (%), L100 = 0.
86 (%), V90 = 6.74 Vrms. V90
When the voltage was applied and the display was observed, the visibility did not decrease due to parallax, but the reflectance when no voltage was applied was
It was lower than that of Example 4.

[0089]

As described above, according to the present invention, a light having a high visibility, which enables a bright white display without a backlight, and which does not cause blurring of characters due to parallax or double appearance even for fine characters and figures. A scattering type liquid crystal element can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view of a cross-sectional view of a light-scattering type liquid crystal element of the present invention.

FIG. 2 is a schematic diagram of paths of incident light and scattered light when a voltage is applied to one pixel electrode in the light scattering type liquid crystal element of the present invention.

FIG. 3 is a schematic view of a path of incident light and scattered light when a voltage is applied to one pixel electrode in an element having a large distance between a light control layer and a reflective layer, unlike the light scattering type liquid crystal element of the present invention. is there.

[Explanation of Signs] 1: Transparent substrate 2: Transparent electrode 3: Light control layer 4: Air layer 5: Reflective layer 6: Light absorbing layer 7: Voltage applied portion 8: No voltage applied portion 9: Forward scattered light 10 : Back scattered light 11: Of forward scattered light (9), reflected by the reflective layer,
Light emitted to the observer side 12: Light incident on the portion to which the voltage is applied, reflected by the reflective layer, and emitted to the observer side

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H089 HA04 LA03 MA01X NA09 QA16 TA01 TA13 TA17 TA18 2H091 FA14Z FA16Z FA34Z FA41Z FB02 FC01 FC02 GA01 GA03 GA08 JA02 KA10 LA16 LA30

Claims (3)

[Claims] A transparent substrate having an electrode layer and a dimming layer made of a liquid crystal and a transparent solid substance between the substrates, and a back surface of the dimming layer viewed from an observer, In a light scattering type liquid crystal device having a reflective layer and a light absorbing layer in this order, and further having an air layer between the transparent substrate on the back side and the reflective layer, the distance between the dimming layer and the reflective layer is short side of the pixel electrode. A light scattering type liquid crystal element, wherein the distance is 4 times or less, and the distance between the light control layer and the reflection layer is 0.8 mm or less. 2. The reflection layer has a reflectance of 400 to 650 nm.
The light-scattering liquid crystal device according to claim 1, wherein the light-scattering liquid crystal element is 5 to 60% of the light. 3. The light-scattering type liquid crystal device according to claim 1, wherein the thickness of the rear transparent substrate is 0.7 mm or less.