JPH06167699A - Display element and display device - Google Patents

Abstract

PURPOSE:To reduce the film thickness of a display layer and to increase a contrast even if a driving voltage drops by inclining the display element for which a high polymer dispersion type liquid crystal is used with the normal of the optical axis of its incident light. CONSTITUTION:The display element for which the high polymer dispersion type liquid crystal is used is constituted by installing the display element at 30 to 70 deg. swing and tilt angle with the normal of the optical axis of the incident light used for making display. Glass, plastic, etc., are used for substrates 101, 101' of such display element. Electrodes 102, 102' are formed thereon and further, a display layer 103 is formed thereon. The formation of the display layer 103 is executed by laminating a porous polymer matrix 104 via an adhesive layer or directly, then dispersing low-polymer liquid crystals 105 therein. The incident light 110 is made incident on the display layer 103 at a certain angle with the electric field to be impressed thereto. This angle is nearly equal to the swing and tilt angle 111 formed by the normal 109 of the display element and the incident light 110 and is used at 30 to 70 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The first invention of the present invention relates to a display device using thermo-optic and electro-optic display elements using transmitted light and scattered light.

A second invention of the present invention relates to a display element and a display device for controlling the presence or absence of diffraction due to the response of liquid crystal using a diffraction grating, and more particularly to a display element and a display device in which the diffraction grating forms a lens. .

[0003]

[Prior art]

O Prior art of the first invention of the present invention Liquid crystal elements have been used in the past in various applications such as thermo-optic and electro-optic displays. Since these displays have low driving voltage and low energy consumption, active research is still ongoing.

As a conventional liquid crystal element, for example, "Applied Physics" by M. Schadt and W. Helfrich.
Letters ") Volume 18, Issue 4 (1971, February 2)
Issued on the 15th of the month) Pages 127-128, "Voltage
Dependant optical activity
Of A Twisted Nematic Liquid Crystal "(" Voltage Dependent O
optical Activity of a Twis
ted Nematic liquid Crystal
l ”) shown in twisted nematic (twis)
A liquid crystal using a ted nematic liquid crystal is known. This TN liquid crystal has a problem in that it causes crosstalk during time-division driving using a matrix electrode structure having a high pixel density, and thus the number of pixels is limited.

As an amelioration of the drawbacks of the conventional liquid crystal device, the use of a liquid crystal device having bistability is disclosed by Clark and Lagerw.
all) (JP-A-56-1072).
16 publication, US Pat. No. 4,367,924, etc.).
As the liquid crystal having bistability, a ferroelectric liquid crystal having a chiral smectic C phase (Sm ^* C) or H phase (Sm ^* H) is generally used.

Since this ferroelectric liquid crystal (FLC) has spontaneous polarization, it has a very fast response speed and can exhibit a bistable state having a memory property. Furthermore, since it has excellent viewing angle characteristics, it is considered to be suitable as a material for a large-capacity, large-area display. However, when actually forming a liquid crystal cell, it is difficult to form a monodomain over a wide area, and there is a technical problem in producing a display device having a large screen.

Examples of liquid crystal display devices using polymer liquid crystals that are considered to be suitable for increasing the area include, for example, V. Shibaev, S. Kostromin, and N. Plate ( NP'late, S. Ivanov
ov), V. Vestrov,
"Polymer Communications" by I. Yakovlev ("Polymer C")
ommunications ") 24, pp. 364-365," Thermotropic Liquid Crystalline Polymers. 14 "(" Thermo-tropi
c Liquid CrystallinePolym
ers. 14 ").

However, this method requires high energy for writing, and there is a problem in speeding up. Further, in the case of displaying using an electric field, it has not been put to practical use due to the problem of delay in response speed due to polymerization.

In addition to the above-mentioned examples, attempts have been made to easily manufacture a liquid crystal element and increase its size. As one of them, there is one in which a low-molecular liquid crystal is used by being held in various polymer matrices. As a specific example thereof, the one filed by Manchester R & D Partnership is known as one in which a low molecular weight liquid crystal is used by being encapsulated in a polyvinyl alcohol matrix (US Pat. No. 4,435,047). Further, U.S. Pat. No. 4,707,080 is known as one in which a low-molecular liquid crystal is held in a connected tubular shape.

Further, as a method of dispersing a low molecular weight liquid crystal in a polymer matrix by mixing and dispersing a polymerizable monomer and a low molecular weight liquid crystal, and then polymerizing the mixture, a method described in JP-A-63-
No. 271233, JP-A No. 61-502128, JP-A No. 1-1198725 and the like are known.

As another method, a method in which a polymer compound and a liquid crystal are dissolved in a common solvent and cast on a substrate has been reported. (T. Kajiyama, Y. Naga
ta, S.S. Washizu and M.M. Takaya
nagi; J. Membrace Sci. , 11 ,
39 (1982)) It is relatively easy to increase the area, and the response speed is better than that of the polymer liquid crystal of the manetic cholesteric. A display device using such a polymer-dispersed liquid crystal as a display element is disclosed in US Pat.
No. 613207 and the like are known, and the possibility as a bright display device that does not require depolarization is disclosed.

Conventional Technology of the Second Invention of the Present Invention Liquid crystal elements have been used in the past in various applications such as thermo-optic and electro-optic displays. Since these displays have low driving voltage and low energy consumption, active research is still ongoing.

As a conventional liquid crystal device, for example, "Applied Physics Letters" by M. Schatt and W. Helfrich.
Letters ") Volume 18, Issue 4 (1971, February 2)
Issued on the 15th of the month) Pages 127-128, "Voltage
Dependant optical activity
Of A Twisted Nematic Liquid Crystal "(" Voltage Dependent O
optical Activity of a Twis
ted Nematic liquid Crystal
l ”) shown in twisted nematic (twis)
A liquid crystal using a ted nematic liquid crystal is known. This TN liquid crystal has a problem in that it causes crosstalk during time-division driving using a matrix electrode structure having a high pixel density, and thus the number of pixels is limited.

In order to solve such problems, it has been considered to provide an active element for each pixel, and high quality display can be realized by using a thin film transistor, a thin film diode, or a non-linear element.

Such a method has an advantage that it can be used with a low electric power because it is driven by an electric field, but it requires a polarizing plate and has a problem that the light utilization rate is low. In addition, the response time when the voltage is off is determined by the interface control force of the substrate surface and the physical properties of the liquid crystal, and there is a problem that the response time cannot be improved unless the liquid crystal cell thickness is reduced. At this time, if the thickness of the liquid crystal cell is made thin, a problem such as a short circuit occurs, and there is an unfavorable problem that the fractionation is reduced.

To solve the above problem, a method using a diffraction grating as proposed in US Pat. No. 4,251,137 has been proposed as a method without using a polarizing plate. This means that when the liquid crystal filled in the diffraction grating and the compound forming the diffraction grating have the same refractive index, the diffraction effect does not appear, and diffraction occurs only when there is a difference in refractive index between the two. It is used, and has the characteristics that it can be driven at low voltage and has a short response time.

[0017]

[Problems to be Solved by the Invention]

The problem to be solved by the first invention of the present invention However, in the above conventional example, in order to obtain a high contrast, it is necessary to thicken the display layer using the polymer-dispersed liquid crystal in the display element, There is a drawback that the driving voltage becomes high. Improvements such as increasing the liquid crystal content have been attempted in order to satisfy both requirements, but the response speed (especially during voltage drop) and hysteresis (transmittance in the step of increasing and decreasing the applied voltage) Phenomenon that there is a difference)
There was a problem that the increase of

The present invention has been made in order to improve the drawbacks of the prior art, and a good contrast can be obtained even if the driving voltage is reduced by reducing the thickness of the display layer. It is intended to provide a display device.

Further, according to the present invention, when a display element is formed by using an active matrix, the display element can be made large even with a light projection surface of the same size, and the number of pixels can be increased for high definition. It is an object of the present invention to provide a display device having a high light utilization rate, which is capable of maintaining a high aperture ratio even when the aperture ratio is increased.

The problem to be solved by the second invention of the present invention. However, in the above-mentioned conventional example, two diffraction gratings that are orthogonal to each other are required, and there is a problem that the manufacturing cost increases. In addition, when the liquid crystal layer is shared and vertical diffraction gratings are provided, the orientation of the filled liquid crystal is disturbed,
There is a problem that the refractive index cannot be controlled sufficiently.

The present invention has been made in order to solve the problems of the prior art, and it is possible to perform a high-contrast display with a high light utilization rate without using a polarizing plate. An object of the present invention is to provide a display element and a display device.

[0022]

[Means for Solving the Problems]

○ Means for Solving the Problem of the First Invention of the Present Invention That is, the first invention of the present invention is a display device comprising a display element using a polymer dispersed liquid crystal, the polymer dispersed liquid crystal The display device is characterized in that it is installed so as to incline at a tilt angle of 30 ° to 70 ° with respect to the normal line of the optical axis of incident light used for displaying. .

Further, according to the present invention, light from a light source is separated into three primary colors, and a display device using a polymer-dispersed liquid crystal is provided at an angle of 30 ° to 70 ° with respect to a normal line of an optical axis of incident light. Means for projecting, means for driving by applying a voltage to the display element, means for separating transmitted light and scattered light from the light projected on the display element,
A display device comprising means for projecting the transmitted light of the three primary colors on the same screen and means for correcting an optical path length difference between the display element and the screen.

The present invention will be described in detail below. According to the present invention, a display element using a polymer dispersed liquid crystal is 30 ° to the normal line of the incident optical axis used for displaying.
By arranging so as to incline at a tilt angle of 70 °, it is possible to display a good contrast even when the film thickness of the display layer is reduced and the driving voltage is lowered.

Further, according to the present invention, when an active element such as a TFT is used, the shape of the silicon portion, which serves as a light shielding portion, the gate, the storage capacitor portion, etc., is made long in the azimuth direction so that the breakdown voltage is high. Even in the case of a display element having a large storage capacity, it is possible to maintain a high aperture ratio, which enables display with a high light utilization rate.

The present invention will be described in more detail below with reference to the drawings. FIG. 2 is a sectional view showing an example of a display element used in the present invention. In the figure, substrates 101, 10
1'may be glass, plastic, or the like.
The polymer film that can be used as the substrate includes
Examples thereof include, but are not limited to, those shown below.

That is, a low density polyethylene film,
High-density polyethylene film (Mitsui Toatsu Kagaku Hibron, etc.), polypropylene film (Toray Trefan, etc.), polyester film (DuPont Mylar, etc.), polyvinyl alcohol film (Nippon Gosei Kagaku Co., Ltd. Hyselon, etc.), polyamide film (Toyo Gosei film Reifan, etc.) Etc.), polycarbonate film (Teijin Teijin Panlite etc.), polyimide film (DuPont KAPTON etc.), polyvinyl chloride film (Mitsubishi resin Hishirex etc.), polytetrafluoride ethylene film (Mitsui Fluorochemical Teflon etc.), polyacrylic film (Sumitomo Bakelite Sumilite), polystyrene film (Asahi Dow Styro sheet), polyvinylidene chloride film (Asahi Dow Saran film), cellulose film, polyvinyl fluoride film ( Yupon Tedlar), and the like.

Electrodes 102 and 102 'are formed on the substrate, and transparent electrodes such as ITO and SnO ₂ and metal films such as Al, Au, Ag, Cu and Cr are used for the electrodes. The reflective display element may also serve as an electrode and a reflective layer.

Further, the display layer 103 is formed on the electrodes. To form the display layer 103, an adhesive layer is used, or
Alternatively, it can be performed by directly laminating the porous polymer matrix 104 and then dispersing the low-molecular liquid crystal 105.

The thickness of the display layer used is usually 0.5 to
When the thickness is less than 0.5 μm, the contrast is not sufficient, and when the thickness exceeds 100 μm, the driving voltage is large and high-speed driving becomes difficult. More preferably, 1 to 50
A thickness of μm is used.

In the display element of the present invention, the display layer 10
3 is a low-molecular liquid crystal 1 on a porous polymer matrix 104.
A display material impregnated with 05 is used. At this time, in the display layer, the porous film forms a continuous matrix, and the low-molecular liquid crystals are dispersed in the form of islands or tubes. The diameter of the island or pipe is 0.1
10 μm is preferable. The diameter of the island or pipe is 0.1-10
Outside the range of μm, the scattering efficiency is poor and sufficient contrast cannot be obtained. More preferably 0.5-5 μ
used in m.

As the polymer film made porous by stretching in the present invention, for example, polyethylene, polypropylene, polycarbonate, polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc. are used, but they are made sufficiently porous. For this purpose, those having a weight average molecular weight of 50,000 or more are usually used. 5000
If it is less than 0, the strength is not sufficient when it is made porous to a state of high porosity, and stable characteristics cannot be obtained, which is not preferable.

In the present invention, at the interface with the low-molecular-weight liquid crystal, a film-like porous material having a surface energy of pores of 20 dyn / cm or less is used, so that the low-molecular-weight liquid crystal has a good vertical alignment property with respect to the interface. It is also possible to indicate. In a non-electric field state, the low-molecular liquid crystal is distorted in orientation because it is vertically aligned with respect to a spherical or tubular interface, and as a result, a good scattering state can be realized. When a voltage is applied to the liquid crystal in this state, the low molecular weight liquid crystal is uniformly oriented with respect to the substrate and becomes transparent.

Further, when the voltage is removed, the interface of the film-like porous material has a good vertical alignment control force, so that the initial scattering state is promptly restored. At this time, since the vertical alignment force is good and stable, it is possible to exhibit good threshold characteristics without hysteresis.
In addition, it is possible to make the high molecular compound fine by stretching, induce a sufficient alignment disorder in the low molecular weight liquid crystal, and impart good transparency when a voltage is applied.

Next, the structure of the low-molecular liquid crystal and the name of the low-molecular liquid crystal composition that are specifically used are shown below, but the present invention is not limited thereto.

[0036]

[Chemical 1]

[0037]

[Chemical 2]

[0038]

[Chemical 3]

[0039]

[Chemical 4]

[0040]

[Chemical 5]

[0041]

[Chemical 6]

[0042]

[Chemical 7]

[0043]

[Chemical 8]

[0044]

[Chemical 9]

[0045]

[Chemical 10]

[0046]

[Chemical 11]

[0047]

[Chemical 12]

The low molecular weight liquid crystal and the composition thereof can be used in various combinations. It is preferably used as a composition exhibiting a nematic phase.

In the display element of the present invention, a thermal head or a laser beam can be used when displaying is performed by utilizing the effect of heating. As the laser light, He-Ne gas laser, Ar ²⁺ gas laser, N
Gas lasers such as ₂ gas lasers, ruby lasers,
Solid-state laser such as glass laser, YAG laser,
It is desirable to use a semiconductor laser or the like. Also, 60
A semiconductor laser having a wavelength range of 0 nm to 1600 nm is preferably used. Particularly preferably 600 to 900 nm
A semiconductor laser in the wavelength range of is used. Further, the wavelength can be shortened by using the second and third harmonics of these laser lights.

When laser light is used, a light absorbing layer is separately provided, or a laser light absorbing compound is dispersed / dissolved in the display layer. When the display surface is affected by the light absorbing layer or the light absorbing compound, it is desirable that the material does not absorb in the visible light region.

Examples of the laser light absorbing compound added to the display layer include azo compounds, bisazo compounds, trisazo compounds, anthraquinone compounds, naphthoquinone compounds, phthalocyanine compounds, naphthalocyanine compounds and tetrabenzoporphyrins. System compounds, aminium salt compounds, diimonium salt compounds, metal chelate compounds and the like.

Of the above-mentioned laser light absorbing compounds, the compounds for semiconductor lasers have absorption in the near infrared region, are useful as stable light absorbing dyes, and have good compatibility or dispersibility with low molecular weight liquid crystals. In addition, some of them have dichroism, and by mixing these dichroic compounds in a low-molecular liquid crystal, a thermally stable host-guest type memory and display medium can be obtained. . Further, the low-molecular liquid crystal may contain two or more kinds of the above compounds.

Further, the above compounds may be combined with other near infrared absorbing dyes or dichroic dyes. Representative examples of near-infrared absorbing dyes that can be suitably combined are cyanine, merocyanine, phthalocyanine, tetrahydrocholine, dioxazine, anthraquinone, triphenodithiazine, xanthene, triphenylmethane, pyrylium, croconium, azulene and triphenylamine. And the like.

The amount of the above compound added to the low molecular weight liquid crystal is about 0.1 to 20% by weight, and preferably about 0.1 to 20%.
0.5-10% is good.

As the porous film forming the display layer of the display element used in the present invention, ceramics, glass or the like can be used as an inorganic material, but a high molecular weight compound is more preferably used.

As a method of making the polymer compound porous, a method of dispersing it in a liquid or the like, a method of performing polymerization phase separation from a prepolymer / monomer, or another polymer compound / inorganic substance / liquid is dispersed. There are a method of making a film and then extracting and removing it to make it porous, a method of making it porous by a mechanical method such as stretching, a method of forming a fibrous or particulate polymer compound to make it porous. Among them, the method of making it porous by a mechanical method such as stretching is preferable because it has high strength and contains few impurities.

In FIG. 2, in the display element used in the present invention, incident light 110 is incident at an angle with the electric field applied in the display layer. This angle is a tilt angle 1 formed by the normal line 109 of the display element and the incident light 110.
Approximately 11 and is used at angles ranging from 30 ° to 70 °.

When the angle is less than 30 °, the effect of reducing the film thickness and the effect of improving the contrast are not sufficient, and when the angle exceeds 70 °, the reflection at the interface and the TFT1 in the display element.
The effect of unevenness such as 08 is large, which is not preferable. More preferably, it is used in the range of 35 ° to 60 °.

At this time, it is desirable that the incident light 110 has the same refractive index with respect to the polymer matrix of the porous polymer 104 and the low-molecular liquid crystal 105 that responds to the electric field in the transmission state by the voltage application. Average refractive index of low-molecular liquid crystals sensed by incident light

[0060]

[Equation 1] When the flapping angle is θ, it is expressed by the following equation.

[0061]

[Equation 2] n ⊥ is the refractive index of the liquid crystal when it is vertically aligned. Δn is the birefringence of the liquid crystal.

However, since the matching of the refractive indexes is not so important when the porosity of the polymer matrix is high, it is possible to freely select the types of the polymer matrix and the liquid crystal.

As a method for producing such a polymer matrix having a high porosity, making it porous by stretching is suitable. When a low molecular weight liquid crystal is impregnated into a polymer matrix with a porosity of 85% or more, most of the scattering effect is due to the disorder of the orientation of the low molecular weight liquid crystal itself, and the difference in the refractive index between the polymer matrix and the liquid crystal is not so important. In addition, even when the display element is tilted, it is possible to provide good light transmittance when a voltage is applied.

3 (a) and 3 (b) show another example of the display element used in the present invention. FIG. 3 (a) is a plan view of the display element, and FIG. 3 (b) is a cross section taken along the line AA '. It is a figure. FIG. 3
In the display element used in the present invention, a pair of substrates 1 and 1 ′ (at least one of which has birefringence) made of a glass plate or a plastic plate is held by a spacer 4 at a predetermined interval. Has a cell structure adhered with an adhesive 6 to seal the substrates 1 and 1'of the substrate 1, 1 ', and further, an electrode group (for example, a matrix electrode structure having a plurality of transparent electrodes 2'is formed on the substrate 1'. The scanning voltage applying electrode group) is formed in a predetermined pattern such as a strip pattern. Further, on the substrate 1, an electrode group (for example, a signal voltage applying electrode group in the matrix electrode structure) including a plurality of reflective layer electrodes 2 intersecting the transparent electrode 2'is formed.

Substrates 1 and 1'provided with such transparent electrodes 2 and 2'are, for example, silicon monoxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride and silicon nitride. Substances, inorganic insulating materials such as silicon carbide and boron nitride, polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylelline, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin It is possible to provide an orientation control film formed by using an organic insulating material such as urea resin or acrylic resin.

This orientation control film is obtained by forming a film of the above-mentioned inorganic insulating material or organic insulating material and then rubbing the surface in one direction with velvet, cloth or paper. In another preferred embodiment of the invention, S
An orientation control film can be obtained by forming a film of an inorganic insulating material such as iO or SiO ₂ on the substrates 1 and 1 ′ by the oblique vapor deposition method.

In another embodiment, the surface of the substrate 1, 1'made of glass or plastic or the substrate 1, 1 '.
After the above-mentioned inorganic insulating material or organic insulating material is formed as a film on the surface of the film, the surface of the film is etched by the oblique etching method, whereby the orientation control effect can be imparted to the surface.

It is preferable that the above-mentioned orientation control film also functions as an insulating film at the same time. Therefore, the thickness of the orientation control film is generally 100Å to 1 μm, preferably 500.
It can be set in the range of Å to 5000Å. This insulating layer also has an advantage that it can prevent the generation of a current caused by a slight amount of impurities contained in the display layer 3, so that the liquid crystal compound is not deteriorated even if the operation is repeated. Further, in the display element of the present invention, an alignment control film may be provided on both sides of the surface of the substrate 1 or the substrate 1'that is in contact with the display layer 3.

In the present invention, the reflective layer is made of Al,
A metal film of Au, Ag, or the like, a dielectric mirror, or the like can be used, and the film thickness is 0.01 to 100 μm, preferably 0.05 to 10 μm. Further, in the present invention, a substrate on which a thin film transistor is formed can be used.

Next, FIG. 1 is an explanatory view showing an example of a display device using the display element of the present invention. The figure shows a full-color projection display device using a Schlieren optical system.

In the figure, the white light from the light source unit 301 is the dichroic mirrors 302, 302 ', 3
02 ″ is classified into three primary colors of R, G, B. The separated light is Schlieren optical system 304, 304 ′, 30
4 ″ is projected onto the display elements 303, 303 ′, 303 ″. At this time, the display element is the display element driving device 307.
A voltage is applied and driven by. This display element may use a simple matrix or a non-linear element, but more preferably a TFT having a switch for each pixel.
The type is superior in display contrast, response speed, and gradation display.

Here, the non-selected pixels are opaque and scatter incident light, and the selected points are transparent to transmit the incident light. The transmitted light is combined by the dichroic prism 305, and the optical path length correction lens 30 for correcting the optical path difference due to the inclination of the display elements 303, 303 ′, 303 ″.
After passing 9, the image was projected onto the screen by the projection lens 306, and a good full-color image was obtained.

Means for Solving the Problem of the Second Invention of the Present Invention That is, the second invention of the present invention comprises sandwiching a liquid crystal between substrates having transparent electrodes on at least one substrate. In the display element, a microlens array made of a diffraction grating is formed on at least one substrate.

Further, according to the present invention, a display element in which light from a light source is separated into three primary colors, and a microlens array made of a diffraction grating is formed between substrates having electrodes for the three primary colors and a liquid crystal is sandwiched therebetween. A means for projecting a voltage to the display element, a means for driving the display element, a means for separating the light condensed by the microlens of the display element, and a means for projecting the transmitted light of the three primary colors on the same screen. Is a display device.

The present invention will be described in detail below. The display element of the present invention is a display element in which a liquid crystal is sandwiched between substrates having a transparent electrode on at least one substrate, and a microlens array composed of a diffraction grating is formed on at least one substrate. It is possible to perform high-contrast display without using a polarizing plate.

The present invention will be described in more detail below with reference to the drawings. FIG. 5 is a sectional view showing an example of a display element used in the present invention. In the figure, substrates 201, 20
1'may be glass, plastic, or the like.
The polymer film that can be used as the substrate includes
Examples thereof include, but are not limited to, those shown below.

That is, a low density polyethylene film,
High-density polyethylene film (Mitsui Toatsu Kagaku Hibron, etc.), polypropylene film (Toray Trefan, etc.), polyester film (DuPont Mylar, etc.), polyvinyl alcohol film (Nippon Gosei Kagaku Co., Ltd. Hyselon, etc.), polyamide film (Toyo Gosei film Reifan, etc.) Etc.), polycarbonate film (Teijin Teijin Panlite etc.), polyimide film (DuPont KAPTON etc.), polyvinyl chloride film (Mitsubishi resin Hishirex etc.), polytetrafluoride ethylene film (Mitsui Fluorochemical Teflon etc.), polyacrylic film (Sumitomo Bakelite Sumilite), polystyrene film (Asahi Dow Styro sheet), polyvinylidene chloride film (Asahi Dow Saran film), cellulose film, polyvinyl fluoride film ( Yupon Tedlar), and the like.

Electrodes 202 and 202 'are formed on the substrate, and transparent electrodes such as ITO and SnO ₂ or metal films such as Al, Au, Ag, Cu and Cr are used for the electrodes. The reflective display element may also serve as an electrode and a reflective layer.

The substrates 201, 201 'provided with such transparent electrodes 202, 202' are, for example, silicon monoxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride. Substances, inorganic insulating materials such as silicon carbide and boron nitride, polyvinyl alcohol, polyimide, polyamide imide, polyester imide, polyparaxylelline, polyester, polycarbonate, polyvinyl acetal,
An orientation control film formed by using an organic insulating material such as polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin, urea resin or acrylic resin can be provided.

This orientation control film is obtained by forming a film of the above-mentioned inorganic insulating material or organic insulating material and then rubbing the surface in one direction with velvet, cloth or paper. In another preferred embodiment of the invention, S
An inorganic insulating material such as iO or SiO _{2 is used} as the substrate 201, 20.
An orientation control film can be obtained by forming a film on 1'by an oblique vapor deposition method.

In another embodiment, the surface of the substrate 201, 201 'made of glass or plastic or the surface of the film after the above-mentioned inorganic insulating material or organic insulating material is formed on the substrate 201, 201'. By etching the film by the oblique etching method, an orientation control effect can be imparted to the surface.

It is preferable that the above-mentioned orientation control film also functions as an insulating film at the same time. For this reason, the thickness of this orientation control film is generally 100 Å to 1 μm, preferably 500.
It can be set in the range of Å to 5000Å. This insulating layer also has an advantage of being able to prevent the generation of a current caused by impurities contained in the display layer 210 in a trace amount.
Therefore, even if the operation is repeated, the liquid crystal compound is not deteriorated. Further, in the display element of the present invention, the substrate 201
Alternatively, an orientation control film may be provided on both sides of the surface of the substrate 201 'which is in contact with the display layer 210.

A microlens 103 made of a diffraction grating is formed on the electrode 102 or 102 '. Cross-sectional views of the diffraction grating used in the present invention are shown in FIGS. 9A to 9C are of the phase modulation type and do not absorb light, so that it is desirable because the diffraction efficiency can be made higher than that of the amplitude modulation type diffraction grating using absorption.

The diffraction efficiency is controlled by selecting the filled liquid crystal, the refractive index difference of the diffraction grating, and the thickness of the diffraction grating, and is set so as to reduce the 0th-order light. The desirable refractive index difference is 0.01 or more, and if it is less than 0.01, the thickness of the diffraction grating becomes too large, which is not preferable. The thickness of the diffraction grating is 0.1 to 20 μm. 0.
If it is less than 1 μm, it is impossible to obtain sufficient diffraction efficiency,
If it exceeds 20 μm, it is difficult to process the element.

The refractive index of the convex portion of the diffraction grating is larger than the ordinary ray refractive index of the liquid crystal used, and is preferably smaller than the extraordinary ray refractive index.

Microlens 20 composed of the diffraction grating
3 and the low-molecular liquid crystal 205 injected into the microlens
In the display layer 210 made of, the low-molecular liquid crystal 205 is arranged by applying an electric field to the electrodes 202 and 202 ′,
A difference between the ordinary refractive index and the refractive index of the diffraction grating is generated, and the incident light is condensed by functioning as a Fresnel lens.

The condensed light passes through the opening 211 provided in the light shielding layer 204 and is displayed. When there is no electric field,
Since the orientation is disturbed, the average value of the refractive index of the liquid crystal does not differ from the refractive index of the convex portion of the diffraction grating, or the refractive index difference opposite to that when the voltage is applied causes no incident light to be condensed. The light blocking layer 204 blocks the light.

The light shielding layer 204 is preferably provided at the focal position of the microlens. When the active element 208 is used, the light-shielding layer also serves as the active element,
Light utilization efficiency is improved, which is desirable.

The light shielding layer 204 is provided with an opening 211 through which incident light is condensed. The smaller the aperture, the higher the contrast of the display element, but the ratio of the emitted light to the incident light decreases, and the light utilization ratio decreases.

The size of the opening portion 211 is 0.1 to 20% with respect to the pixel area. If it is less than 0.1%, the light utilization ratio is too low to be dark, and if it exceeds 20%, the contrast is insufficient. More preferably, it is used at 0.5 to 10%.

Microlens 20 composed of the diffraction grating
As shown in FIG. 6, 3 is formed in a concentric circle shape, and the period of the diffraction grating is set according to the numerical aperture of the lens, and the period becomes shorter toward the outer circumference of the concentric circle.

The period of the diffraction grating is 0.5 to 50 μm.
Used in. If it is less than 0.5 μm, there is no effect because diffraction itself does not occur, and if it exceeds 50 μm, the focal length of the microlens becomes too long, and it becomes difficult to obtain sufficient contrast. It is more preferably used in the range of 1 to 30 μm.

Regarding the method for producing a microlens composed of such a diffraction grating, J. A. Jordan (J.
A. Jordan Jr. ) Et al. (“Applied Optics (Appl. Opt.)”), 9 , 1833 (19).
70)), and the production by photolithography is proposed.

On the other hand, it can also be created by using an electron beam drawing apparatus, as described in T. Fujita et al. (“Optics Letter (Opt. Lett.)”,
6 , 613 (1981)). The diffraction grating used in the present invention may be prepared according to the above method, or may be prepared by a 2P method or an injection molding method using a mold.

As the material for forming the microlens 203 composed of the diffraction grating, organic materials such as photoresist, thermoplastic resin and thermopolymerizable resin, SiO ₂ , glass, Mg
An inorganic substance such as F ₂ is used. Specific photoresists include novolac-based, acrylate-based, chlorinated polystyrene-based, polysiloxane-based, polyimide-based, and polyvinyl alcohol-based photoresists, and negative and positive photoresists are used. More specific examples include ODUR series and OEBR series manufactured by Tokyo Ohka Kogyo Co., Ltd.

From the manufacturing process of the display device, the diffraction grating may be made of an inorganic material such as SiO ₂ . At this time, it is possible to form a predetermined pattern with a photoresist or the like on a film uniformly formed to have a thickness of 0.1 μm to 5 μm, and form a diffraction grating by etching.

The thickness of the display layer used is usually 0.5 to
When the thickness is less than 0.5 μm, the contrast is not sufficient, and when the thickness exceeds 100 μm, the driving voltage is large and high-speed driving becomes difficult. More preferably, 1 to 50
A thickness of μm is used. FIG. 7 is a sectional view showing another example of the display element of the present invention.

Next, the structure of the low-molecular liquid crystal used concretely and the name of the low-molecular liquid crystal composition are as described in the first invention.

[Chemical 1] ~

Examples thereof include, but are not limited to, those shown in. The low molecular weight liquid crystal and the composition thereof can be used in various combinations. It is preferably used as a composition exhibiting a nematic phase.

In the display element of the present invention, when the effect of heating is used for display, a thermal head or laser light can be used. As the laser light, He-Ne gas laser, Ar ²⁺ gas laser, N
Gas lasers such as ₂ gas lasers, ruby lasers,
Solid-state laser such as glass laser, YAG laser,
It is desirable to use a semiconductor laser or the like. Also, 60
A semiconductor laser having a wavelength range of 0 nm to 1600 nm is preferably used. Particularly preferably 600 to 900 nm
A semiconductor laser in the wavelength range of is used. Further, the wavelength can be shortened by using the second and third harmonics of these laser lights.

When laser light is used, a light absorption layer is separately provided, or a laser light absorption compound is dispersed and dissolved in the display layer. When the display surface is affected by the light absorbing layer or the light absorbing compound, it is desirable that the material does not absorb in the visible light region.

Examples of the laser light absorbing compound added to the display layer include azo compounds, bisazo compounds, trisazo compounds, anthraquinone compounds, naphthoquinone compounds, phthalocyanine compounds, naphthalocyanine compounds and tetrabenzoporphyrins. System compounds, aminium salt compounds, diimonium salt compounds, metal chelate compounds and the like.

Of the above laser light absorbing compounds, the compounds for semiconductor lasers have absorption in the near infrared region, are useful as stable light absorbing dyes, and have good compatibility or dispersibility with low molecular weight liquid crystals. In addition, some of them have dichroism, and by mixing these dichroic compounds in a low-molecular liquid crystal, a thermally stable host-guest type memory and display medium can be obtained. . Further, the low-molecular liquid crystal may contain two or more kinds of the above compounds.

Further, the above compounds may be combined with other near infrared absorbing dyes or dichroic dyes. Representative examples of near-infrared absorbing dyes that can be suitably combined are cyanine, merocyanine, phthalocyanine, tetrahydrocholine, dioxazine, anthraquinone, triphenodithiazine, xanthene, triphenylmethane, pyrylium, croconium, azulene and triphenylamine. And the like.

The amount of the above compound added to the low molecular weight liquid crystal is about 0.1 to 20% by weight, preferably,
0.5-10% is good.

Next, FIG. 8 is an explanatory view showing an example of a display device using the display element of the present invention. The figure shows a full-color projection display device using a Schlieren optical system.

In the figure, the white light from the light source unit 301 is the dichroic mirrors 302, 302 ', 3
02 ″ is classified into three primary colors of R, G, B. The separated light is Schlieren optical system 304, 304 ′, 30
4 ″ is projected onto the display elements 303, 303 ′, 303 ″. At this time, the display element is the display element driving device 307.
A voltage is applied and driven by. This display element may use a simple matrix or a non-linear element, but more preferably a TFT having a switch for each pixel.
The type is superior in display contrast, response speed, and gradation display.

Here, the non-selected pixel is in a state in which the non-light cannot be focused on the opening, blocks the incident light, and allows the selected point to transmit the incident light. This transmitted light is converted into a dichroic prism 305.
When combined with each other and projected onto a screen by the projection lens 306, a good full-color image was obtained.

[0108]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example of the First Invention of the Present Invention Example 1 A substrate (made by Matsuzaki Vacuum Co., Ltd.) in which ITO (indium tin oxide) was vapor-deposited to a thickness of 2000 Å on a glass substrate having a thickness of 1.1 mm. Epoxy adhesive (Mitsui Toatsu Co., Ltd.)
(Manufactured by: Struct Bond XN-21-F), and further applied by Asahi Chemical Industry Co., Ltd .: Hiapo 3000.
(A film thickness of 50 μm and a porosity of 90%) were laminated and bonded by thermosetting.

Next, polystyrene (made by Aldrich, M
A benzene solution (w = 280,000, Tg = 100 ° C.) was impregnated, dried and cured, and then polished by a grinder to have a thickness of 5 μm. Then, polystyrene was removed by ultrasonic cleaning with benzene. Next, a 2000 Å-thick glass substrate with ITO was bonded using an adhesive containing a glass fiber spacer (manufactured by Nippon Electric Glass Co., Ltd., 5 μmφ) and cured to form a cell structure.

The cell was decompressed and the capillary method was used to produce ZLI2008 (nematic composition T _NI = 64) manufactured by E-Merck.
C) was impregnated and injected. ± 20 between the upper and lower substrates of this cell
When a rectangular wave of V, 60 Hz was applied, the voltage turned on, the state became transparent, and the voltage turned off, the state became cloudy. The threshold voltage for 10% light transmission was as low as 4V.

Examples 2 to 4 and Comparative Examples 1 to 2 With respect to the display elements prepared in Example 1, when the apparatus shown in FIG. Was rotated, and the contrast and light transmittance due to on-off when the tilt angle θ was changed were measured. The results are shown in Table 1.

[0113]

[Table 1]

Example of the Second Invention of the Present Invention Example 5 ITO was vapor-deposited on a 1.1 mm thick glass substrate to a thickness of 500 Å, and an insulating layer (SiO ₂ ) was further vapor-deposited to a thickness of 1000 Å. Positive photoresist (TSMR-8
900, manufactured by Tokyo Ohka Co., Ltd., refractive index = 1.64) was applied by a spinner method and prebaked at 90 ° C. to obtain a film having a thickness of 5 μm. This substrate was exposed with Nikon NSR-1505G using a photomask with a microlens having an outer diameter of 500 μm and a focal length of 1.1 mm, developed with a developer (Tokyo Oka, NMD-3), and then with pure water. After rinsing, a microlens composed of a diffraction grating was obtained.

The substrate which had been post-baked at 120 ° C. for 20 minutes was transferred to a glass substrate having a thickness of 1.1 mm and an I having a thickness of 500Å.
A substrate with a deposit of SiO ₂ of the TO and thickness 1000 Å, 5
Lamination was performed using an epoxy adhesive containing a glass fiber spacer of μmφ. After vacuum degassing this cell, low molecular weight nematic liquid crystal BL006 (manufactured by Merck & Co., Inc., n
₀ = 1.530, and the n _e = 1.816) was injected by capillary method.

A pinhole plate having a hole diameter of 50 μm was bonded to the microlens side substrate of this cell by aligning the position of the hole and the center of the microlens. When white light of 50 μW was incident on the microlens of this display element, the amount of light passing through the pinhole was 0.3 μW. Next, when a voltage of 60 Hz and 30 V was applied to the electrodes on the upper and lower substrates, the amount of light passing through was increased to 23 μW. This was good with a contrast of 77 and a light utilization rate of 46%.

Comparative Example 3 A polarizing plate (manufactured by Nitto Denko KK: NPF-1100) was orthogonally attached to a TN type liquid crystal element (a liquid crystal ZLI2008 manufactured by Merck Co., Ltd. was injected into a 10 μm cell manufactured by ECH Co., Ltd.)
When white light of 50 μW was incident simultaneously with Example 5,
The amount of light passing through at the voltage OV was 14 μW.

Next, when a voltage of 60 Hz and 20 V was applied to this liquid crystal element, the amount of light passing through was 0.6 μW. This has a low contrast of 23 and a light utilization rate of 28.
% Was insufficient.

Comparative Example 4 ITO500Å, SiO ₂ on a 1.1 mm thick glass substrate
Negative electron beam resist (OEBR-100, manufactured by Tokyo Ohka Co., Ltd., refractive index =
1.49) was applied by a spinner method and prebaked at 80 ° C. for 10 minutes to obtain a film having a thickness of 1 μm. Electron beam drawing device (E, manufactured by Elionix Co., Ltd., E
LS-3300) was used to draw the same pattern as the photomask used in Example 5. Next, it was developed with a developing solution for OEBR, rinsed with a rinse solution, and post-baked at 130 ° C. to form a microlens composed of a diffraction grating.

This substrate was attached to a 1.1 mm thick glass substrate on which a 500 Å-thick ITO film and a 1000 Å-thick SiO ₂ film were vapor-deposited using an epoxy resin containing a 5 μmφ glass fiber spacer. After vacuum degassing the cell, low molecular weight nematic liquid crystal BL006 (manufactured by Merck & Co., n ₀ = 1.530, n _e = 1.816) was injected by a capillary method.

A pinhole plate having a hole diameter of 50 μm was attached to the microlens side substrate of this cell by aligning the position of the hole and the center of the microlens. When white light of 50 μW was incident on the microlens of this display element, the amount of light passing through the pinhole was 1.4 μW. next,
When a voltage of 60Hz, 30V was applied to the upper and lower substrates,
The amount of light passing through was 2.5 μW. This was insufficient at a contrast of 2 and a light utilization rate of 5%.

[0122]

【The invention's effect】

Effect of the first invention of the present invention As described above, according to the first invention of the present invention, a display element using a polymer-dispersed liquid crystal is provided with respect to the normal line of the optical axis of the incident light. By tilting, the thickness of the display layer is thin,
Even if the driving voltage is lowered, the effect of displaying good contrast can be obtained.

Effect of the Second Invention of the Present Invention As described above, according to the second invention of the present invention, by using the display element in which the liquid crystal is injected into the microlens array composed of the diffraction grating, the polarized light is It became possible to perform high-contrast display with a high light utilization rate that does not require a plate.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a display device of the present invention.

FIG. 2 is a cross-sectional view showing an example of a display element used in the present invention.

FIG. 3 shows another example of the display element used in the present invention.
FIG. 3A is a plan view of the display element, and FIG. 3B is a sectional view taken along the line AA ′.

FIG. 4 is an explanatory diagram of an apparatus for measuring contrast and light transmittance when the tilt angle θ of a display element is changed in Example 2.

FIG. 5 is a cross-sectional view showing an example of a display element of the present invention.

FIG. 6 is a plan view showing an example of a display element of the present invention.

FIG. 7 is a cross-sectional view showing another example of the display element of the present invention.

FIG. 8 is an explanatory diagram showing an example of a display device using the display element of the present invention.

FIG. 9 is a sectional view showing a diffraction grating that can be used in the present invention.

[Explanation of symbols]

 1, 1 ', 101, 101' Substrate 2, 2 'Transparent electrode 3, 103 Display layer 4 Spacer 5, 106 Adhesive layer 6 Adhesive 102, 102' Electrode 104 Porous film 105 Low-molecular liquid crystal 107 Insulating layer 108 TFT 109 Normal line of display element 110 Incident light θ, 111 Swing angle 112 Display element 113 Pinhole 114 W lamp 115 Optical axis 201,201 ′ Substrate 202,202 ′ Electrode 203 Microlens composed of diffraction grating 204 Light-shielding layer 205 Low-molecular liquid crystal 206 Signal line 207 Insulating film 208 Active element 209 Scan line 210 Display layer 211 Opening portion 301 Light source unit 302, 302 ', 302 "Dichroic mirror 303, 303', 303" Display element 304, 304 ', 304 "Schlieren optical system 305 Dichroic Zum 306 projection lens 307 display element driving device 309 the optical path length compensation lens

 ─────────────────────────────────────────────────── --Continued front page (72) Inventor Toshikazu Onishi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (8)

[Claims] 1. A display device including a display element using polymer dispersed liquid crystal, wherein the display element using the polymer dispersed liquid crystal is a normal line of an optical axis of incident light used for displaying. A display device, which is installed so as to be inclined at a tilt angle of 30 ° to 70 °. 2. The display device according to claim 1, wherein the polymer-dispersed liquid crystal has a stretched and porous polymer matrix. 3. The liquid crystal content of the polymer-dispersed liquid crystal is 8
The display device according to claim 1, which is 5% or more. 4. A means for separating light from a light source into three primary colors and projecting the light on a display element using a polymer dispersed liquid crystal at an angle of 30 ° to 70 ° with respect to a normal line of an optical axis of incident light, Means for applying a voltage to the display element to drive it, means for separating transmitted light and scattered light from the light projected on the display element, means for projecting the transmitted light of the three primary colors on the same screen, between the display element and the screen A display device comprising means for correcting the optical path length difference of the display device. 5. A display element having a liquid crystal sandwiched between substrates having transparent electrodes on at least one substrate, wherein a microlens array made of a diffraction grating is formed on at least one substrate. Display element. 6. The display element according to claim 5, wherein the refractive index of the substance forming the diffraction grating is between the extraordinary ray refractive index and the ordinary ray refractive index of the liquid crystal. 7. The display element according to claim 5, further comprising a light shielding portion that separates the light condensed by the microlens. 8. A means for separating light from a light source into three primary colors and projecting the three primary colors onto a display element formed by sandwiching a liquid crystal in which a microlens array made of a diffraction grating is formed between substrates having electrodes. A means for applying and driving a voltage to the display element, a means for separating the light condensed by the microlenses of the display element, and a means for projecting the transmitted light of the three primary colors on the same screen. Display device.