JPH04118635A - Display element - Google Patents

Abstract

PURPOSE:To improve a transmitted light quantity and contrast with just one sheet of polarizing plate by providing a display layer which is uniaxially oriented and is specific in retardation to visible light. CONSTITUTION:This element is constituted by providing the display layer 3 contg. a high-polymer liquid crystal compd. between the polarizing plate 7 and a reflecting layer 2 and the layer 3 is uniaxially oriented. The retardation thereof is set at lambda(m+ or -1/4) with respect to the visible light, where m is an integer including 0, only +1/4 when m=0, lambda denotes a visible light wavelength (mum). The axis of polarization of the plate 7 and the orientation axis of the layer 3 are preferably so set as to have 35 to 55 deg. angle. The provision of a function as an electrode on the layer 3 is also preferable. The high-polymer compd. consisting of the unit of formula, etc., are usable as the above-mentioned compd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a display element using a polymeric liquid crystal compound,
In particular, the present invention relates to a reflective display element having a reflective layer.

[Prior Art] As a conventional liquid crystal element, for example, M-Shut (M,
5chadt) and Doublenie Helfrich (W.

“Applied Physics Letters” by He1frich
ers”) Volume 18, No. 4 (February 15, 1971
Voltage Dependant Optical Activities of Voltage Dependant Optical Activity
“A Twisted Nematic Liquid Crystal” (“Voltage Dependent 0pti
cal Activity of a Twisted
Nematic 1quid Crystal”)
The twisted nematic shown in
A device using a nematic liquid crystal is known.

This TN liquid crystal has a problem in that crosstalk occurs during time-division driving using a matrix electrode structure with high pixel density, so the number of pixels is limited.

Furthermore, its use as a display has been limited due to its slow electric field response and poor viewing angle characteristics. Further, there are problems in that the process of forming a thin film transistor in each pixel is extremely complicated, and it is difficult to create a large-area display element.

To improve the drawbacks of conventional liquid crystal devices, the use of bistable liquid crystal devices is proposed by Clark (C1
ark) and Lagerwall (Japanese Unexamined Patent Publication No. 56-107216,
(U.S. Pat. No. 4,367,924, etc.). As a liquid crystal having bistability, a ferroelectric liquid crystal having a chiral smectic C phase (Sm''C) or H phase (Sm'' old) is generally used.

This ferroelectric liquid crystal (FLC) has a very fast response speed because it has spontaneous polarization, and can also develop a bistable state with memory properties. Furthermore, since it has excellent viewing angle characteristics, it is thought to be suitable as a material for large-capacity, large-area displays. but,
When actually forming a liquid crystal cell, it is difficult to form a monodomain over a wide area, and there are technical problems in producing a large screen display element.

To solve this problem, it has been reported that a ferroelectric smectic liquid crystal monodomain is created by an epitaxial method using interfacial energy. (U.S. Pat. No. 4,561,726) However, the monodomains obtained in this way are not inherently stable and are easily converted into multidomains by pressure or thermal stimulation, making it difficult to increase the area.

On the other hand, polymer liquid crystal devices have been proposed as devices that are easy to fabricate and suitable for large-area displays. As a device driven by an electric field, US Pat. No. 4,239,435 and the like are known.

Further, British Patent No. 2146787 is known as a method for addressing using heat, typically laser light, and Japanese Patent Application Laid-open No. 14114/1989 is a method for addressing using a thermal head or the like.

Although devices using these polymer liquid crystal devices are suitable for large-area, high-definition displays, they have a drawback in that they have slow response speeds, making them unsuitable for applications that require moving images or high-speed rewriting.

Various studies have been made to eliminate the above drawbacks. One of them is N. Brate et al., "Polymer Bulletin," p. 299, (1984) [
N, A, Plate etal, Polymer B
ulletin, 12° 299 (1984)], a ferroelectric polymer liquid crystal has been reported. This ferroelectric polymer liquid crystal is easy to form into devices such as film formation, making it suitable for large-area displays, and its response speed is greatly improved compared to conventional polymer liquid crystals, so it is expected to be put into practical use. .

Among them, a method using two polarizing plates using the electric field birefringence effect has also been proposed. (Japanese Unexamined Patent Publication No. 63-153520) Also, a method using a multiple reflection effect due to a change in refractive index has been proposed. (Japanese Unexamined Patent Publication No. 63-271228) [Problems to be Solved by the Invention] However, in the conventional example described above, two or more polarizing plates are required, and when the reflective type is used, the amount of light is greatly reduced, making it difficult to see. There was a drawback of reduced contrast.

In addition, since the driving voltage of polymer liquid crystals is high, it is necessary to reduce the film thickness, but even in the electric field birefringence mode, which has the potential to be made thinnest, its retardation is less than 1/2 wavelength. As the size becomes smaller, there is a drawback that the contrast decreases.

The present invention was made in order to improve the drawbacks of the conventional technology, and it is possible to use only one polarizing plate in a reflective display element, and to obtain high reflectance and good contrast. The object is to provide a display element with improved response speed.

[Means for Solving the Problems] That is, the present invention provides a display element having a display layer containing a polymeric liquid crystal compound between a polarizing plate and a reflective layer, in which the display layer is uniaxially aligned and the return dation (Δn
d) is λ(m±l/4) for visible light (m is an integer including 0, when m=o, only +174, and the visible light wavelength (
IJ, m). ).

The present invention will be explained in detail below.

The display element of the present invention has a display layer containing a polymeric liquid crystal compound between a polarizing plate and a reflective layer, the display layer is uniaxially aligned, and its retardation is λ(m±1) with respect to visible light. /
4) (m: an integer including 0, λ: visible light wavelength), so that in a reflective display element, a good amount of transmitted light and a good contrast can be obtained with a single polarizing plate.

1(a) and 1(b) show an example of the display element of the present invention, FIG. 1(a) is a plan view of the display element of the present invention, and FIG.
b) is a cross-sectional view taken along line AA'.

In FIG. 1, a display element using the polymeric liquid crystal compound of the present invention includes a pair of substrates 1.1' (at least one of which has birefringence) made of a glass plate or a plastic plate, and a spacer 4. It has a cell structure bonded with an adhesive 6 to hold the pair of substrates l and 1' at a predetermined distance and seal them, and furthermore, a plurality of transparent electrodes 2' are formed on the substrate 1'. An electrode group (for example, an electrode group for applying a scanning voltage in a matrix electrode structure) is formed in a predetermined pattern such as a strip pattern. Further, on the substrate 1, there is formed an electrode group (for example, a signal voltage application electrode group of a matrix electrode structure) consisting of a plurality of reflective layer electrodes 2 intersecting with the above-mentioned transparent electrode 2'.

A substrate 1' provided with such a transparent electrode 2'1 and a reflective layer electrode 2.
, l include, for example, inorganic insulating materials such as silicon oxide, silicon dioxide, aluminum oxide, zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, and boron nitride, polyvinyl alcohol, and polyimide. Oriented films formed using organic insulating materials such as , polyamideimide, polyesterimide, polyparaxylerin, polyester, polycarbonate, polyvinyl acetal, polyvinyl chloride, polyamide, polystyrene, cellulose resin, melamine resin, urea resin, and acrylic resin. Control membranes 5, 5' can be provided.

The orientation control film 5.5' is obtained by forming a film of the above-mentioned inorganic or organic insulating material and then rubbing the surface in one direction with velvet, cloth, or paper.

In another preferred embodiment of the present invention, the alignment control film 5.5' can be obtained by forming a film of an inorganic insulating material such as SiO or SiO□ on the substrates 1 and 1' by oblique vapor deposition. .

In another specific example, after forming a film of the above-mentioned inorganic insulating material or organic insulating material on the surface of the substrate l, 1' made of glass or plastic or on the substrate 1.1', the surface of the film is diagonally shaped. By etching using an etching method, an orientation control effect can be imparted to the surface.

The above-mentioned alignment control films 5, 5' preferably function as insulating films at the same time, and for this purpose, the thickness of the alignment control films is generally 100 to 1 μm, preferably 500 to 1 μm.
It can be set to a range of 5,000 people. This insulating layer also has the advantage of being able to prevent the generation of current caused by trace amounts of impurities contained in the display layer 3 containing a polymeric liquid crystal compound. It will not deteriorate.

Further, in the display element of the present invention, the substrate 1 or the substrate 1'
The alignment control film may be provided only on one side of the surface in contact with the display layer 3 containing the polymeric liquid crystal compound.

In the present invention, the reflective layer has a function as an electrode and is used as a reflective layer electrode.
, Au, Ag, etc., or a dielectric mirror, etc., can be used, and the film thickness thereof is 0.25 mm. O1 to 100 m, preferably 0.05 to lO m.

Further, as the substrate, a glass substrate, a plastic substrate, etc. can be used.

In the present invention, the polymeric liquid crystal compound used for the display layer has a high birefringence (Δn), which is compared to the thickness required to obtain λ/4 retardation with conventional stretched polymers, etc. Therefore, a thickness of 1/10 to 1/1000 has sufficient advantages. Furthermore, by using the glass transition point or viscosity effect, it is possible to change and fix the orientation state or birefringence.

The birefringence of the polymeric liquid crystal compound used in the present invention is usually 0.01 to 2.0, preferably 0.05 to 1.0.
Desirably, if it is less than 0.01, the thickness of the display layer required to obtain the necessary tarpaulin becomes too large, making it difficult to manufacture the display layer and reducing the display speed.

If it exceeds 2.0, the thickness of the display layer that provides the lowest order of density becomes too small, making it difficult to form it uniformly and making it impossible to obtain good optical properties.

The thickness of the display layer is usually 0.05 to 10 μm, preferably 0.05 to 10 μm.
．． 1 to 81LIII is desirable. Further, the display layer can be easily formed on the substrate by a dipping method, a bar code method, a spin code method, or the like.

In addition, the thickness of the above display layer is determined by the retardation (Δnd
) (Δn is the birefringence index, and d is the film thickness.

) is λ (1/4 on m) (m is an integer including 0, when m = 0, only +1/4, λ indicates visible light wavelength (gm).)
It is appropriately selected and created within the above range so that it becomes . The visible light wavelength λ is the display light wavelength, and it is sufficient that it satisfies the above conditions in the visible light range of 400 to 700 nm.

Further, m is an integer including O, and is usually 0 to 3, preferably 0 to 1.

When m>1, the display element of the present invention has strong display color selectivity, making it difficult to display over the entire visible light range. Note that if the display wavelength is corrected for each display pixel at a visible light wavelength of 400 nm to 700 nm or monochromatic display is performed, it is not necessary to limit the range to the above range.

More preferably, m=0, and by making the film thinner, high-speed response is possible and good contrast can be obtained in the entire visible light wavelength range.

Such a thickness of the display layer could not be created with high precision using conventional liquid crystals or birefringent materials, but in the display element of the present invention, it is possible to achieve this thickness by using a polymeric liquid crystal compound as the display layer. became.

Next, FIG. 2 shows the relative positions of the incident linearly polarized light, the alignment axis of the display layer containing a polymeric liquid crystal compound, and the output linearly polarized light in the display element of the present invention.

In the present invention, it is preferable that the polarization axis of the polarizing plate and the orientation axis of the display layer have an angle of 35 to 55 degrees. 351
Outside the range of ~551, the incident linearly polarized light does not become perfectly circularly polarized light, and leakage light occurs, resulting in a decrease in contrast, which is not preferable. More preferably, it is used at 45°.

In Figure 2, when linearly polarized light is incident on the display layer at an angle θ between the polarization axis of the polarizing plate and the orientation axis of the display layer, it becomes elliptically polarized light due to its birefringence, and the retardation is λ (m
fl/4), the light becomes circularly polarized. When this circularly polarized light is reflected by the reflective layer, the rotation direction of the circularly polarized light is reversed. When this counter-rotating circularly polarized light enters the display layer again, it is emitted as outgoing linearly polarized light 1o orthogonal to the incoming linearly polarized light 8 through the reverse process. This cannot be transmitted through the polarizing plate.

If θ is Oo or 90e, that is, the incident linearly polarized light 8 is parallel or perpendicular to the display layer alignment axis 9 of the polymeric liquid crystal compound, the incident linearly polarized light will not become circularly polarized light (while maintaining its polarization direction). In order to emit the light, all the incident light passes through the polarizing plate and is emitted. Alternatively, if the display layer does not exhibit birefringence with respect to the incident linearly polarized light, the incident light is similarly emitted as is.

Due to the above effects, good contrast can be obtained with a single polarizing plate. Further, even with a reflective configuration, the amount of reflected light is large, and there is an effect that visual contrast does not decrease even when no strong light is incident.

In the present invention, the display portion and the non-display portion of the display layer are in the following states: ■ Isotropic phase ■ Nematic phase vertical alignment ■ Nematic phase horizontal alignment ■ Smectic phase vertical alignment ■ Smectic phase horizontal alignment ■ Chiral smectic synergistic orthogonal alignment ■ The horizontal orientation of the chiral smectic phase is selected, and a display or non-display state is formed by heating with an electric field, magnetic field, laser irradiation, etc. according to the horizontal orientation. The above-mentioned external field and heating may be used alone or in combination, and states with different orientation axes and different birefringences are selected.

Furthermore, by using the glass transition point, viscosity effect, surface stabilization effect, etc. of a polymeric liquid crystal compound, it is also possible to perform a display with memory properties.

Examples of polymeric liquid crystal compounds that can be used in the display layer of the display element of the present invention include the following.

(In the following formulas (1) to (13), p=5 to 1000.
1≦n, <15. ) CH3 (lO) (In the following formulas (14) to (17), p=5 to 1000°p++p2=5 to 1000°q=l to 16°=1 to 16°qi=1 to 16.

(In the formula, R=-CH□ -H or -C1! shows.

(In the formula, R=-CH,.

-H or -CI! shows.

(In the following formulas (18) to (37), * indicates optically active carbon atom shows, n=5 to 1000.

(m, = 2~10) (+o, = 2~10) (-yo=2~15) (■, = 2-15) (ms=2~15) P (+m-=2~15) (112=2~15) (x+y=1゜ q=l~10° p2=1~15) →CH2−CH← n=l7 (R=-CH,,-H or-CI!.

= 1-10) CH.

(p4=1 to 15) (ms=o to 5) The polymeric liquid crystal compounds can be used alone, or two or more kinds can be mixed or copolymerized.

Furthermore, in order to control the refractive index, it is also preferable to use it in combination with a low-molecular liquid crystal within a range that does not impair memory stability.

Furthermore, as the polymeric liquid crystal compound used in the display layer of the display element of the present invention, ferroelectric polymeric liquid crystal is preferable because it has a fast response speed and excellent phase stability and memory properties.

The ferroelectric polymer liquid crystal that can be used in the present invention preferably has a chiral smectic phase. More preferably, it has a SmC'' phase, an SmH'' phase, an SmI'' phase, an SmJ'' phase, and an SmG'' phase.

Also, main chain type ferroelectric polymer liquid crystal.

Those having a side chain type or main chain-side chain type structure are used, and main chain type ferroelectric polymer liquid crystals include polyester, polyether, polyazomethine, polythioester, and polythioether. system.

Polysiloxane-based, polyamide-based, polyimide-based, etc. can be used. As the side chain type ferroelectric polymer liquid crystal, polymethacrylic, polyacrylic, polychloroacrylic, polyether, etc. can be used.

The above-mentioned main chain type, side chain type, and main chain-side chain type ferroelectric liquid crystal compounds may be used alone (or two or more of the same or different types of polymer liquid crystal compounds may be used). They may be mixed or copolymerized.

Next, some specific examples of ferroelectric polymer liquid crystals that can be used in the present invention are shown below, but the invention is not limited thereto.

m=5゜ n=4-18 +C)lz-CHl-r- ρ=1~2° k=1~2 n=4-1g.

m=5 1+-CH--CH)y-- J=1-2. ni = 1~2° j=0 or l.

n=4-18 m=5 1+-cH, ~CH transport- 2=1~2. ni = 1~2° j=0 or l.

n=4 to 18゜m=5 j=0 or 1゜m=5 j=O or 1゜m=5 x = 0.1 to 1.0 m=4 to 12゜n≧3 Also, by blending etc. Optically active polymer liquid crystals that can exhibit ferroelectricity can also be used.

Specifically, the following can be mentioned.

(m-=2~15°x+y=1) (X+y=1, m*=2~15)(x+
y = 1, all: 2-15) (x + 3'
= 1, @, = 2 to 15) (layer, = 1 to 5) (x + y = 1) (qs = 1 to 10 ° x + y = 1) In the present invention, the ferroelectric polymer liquid crystals may be used alone or in combination. It can be used by

In the present invention, a liquid crystal composition containing a ferroelectric polymer liquid crystal and a low molecular liquid crystal can be used in the ferroelectric polymer liquid crystal layer, but a ferroelectric liquid crystal is preferably used as the low molecular liquid crystal. However, it does not need to be a ferroelectric liquid crystal as long as the characteristics of the ferroelectric polymer liquid crystal are not impaired. The content of low-molecular liquid crystal in the mixture of ferroelectric polymer liquid crystal and low-molecular liquid crystal is 40% by weight or less, and if it exceeds 40% by weight, film strength and film formability are impaired, which is not preferable. More preferably, it is 20% by weight or less.

Next, the structure of a specifically used low molecular weight liquid crystal is shown below, but it is not limited thereto.

(2-Methylbutyl)esteroxybiphenyl-4-carboxylate 4-hexyloxyphenyl-4-(2''-methylbutyl)biphenyl-4'-carboxylatebutyl) biphenyl-4'-carboxylate 4-hexyloxyphenyl- 4-(2″-methylbutyl)biphenyl-4′-carboxylate 4-(2″-
Methylbutyl)phenyl-4-(4''-methylhexyl)biphenyl-4'-carboxylate\74.3℃ SmC''〈- Add'81.0℃ (I-9) a=6゜b=12 a=8 ．． b=10 33℃ 43℃ 46℃
48℃ crystal←SmC”←SmA←Cholesteric phase←−
Isotropic phase (I-11) 58℃ 120℃ 146℃ crystal-m
-→SmC"--→SmA ---→4'-n-nonyloxy-4-biphenylyl-4-cyanobenzoate isotropic phase → nematic → smectic C (I-13) 4 -n-hebutylphenyl-4-(4'-nitrobenzoyloxy)benzoate (DByNOx) isotropic phase→
Nematic → Smectic A 4-n-octylphenyl-4-(4'-nitrobenzoyloxy)benzoate (DB, N02) etc. →
Nematic → Smectic A + Smectic C (I-1
5) Benzoate (DB,, N021 Tokichi compatible nematic smectic A → smectic C
C) 14'-cyanostilbene (T8) Iso-yoshi phase → nematic → smectic A → smectic A2 → nematic (I-17) 4-n-pentylphenyl-4-(4'-cyanobenzoyloxy) benzoate (DBsCN1 isotropic Phase → Nematic → Smectic A (■ 1g+ 4-n-/Nyloxyphenyl-4-(4-nitrobenzoyloxy)benzoate (DB, 0N02) etc. Phase → Nematic → Smectic A + Smectic C (■ 2-(4'- n-pentylphenyl)-5pentyloxyphenyl)pyrimidine (4'' Tokichi phase → Smectic A → Smectic C → Smectic F → Smectic G C, H,, Obe) HN 4-cyano-4'-n-octyl Oxybiphenyl (8
0CB) Tokichi phase → Nematic → Smectic A (I-21) Ethyl-4-azobenzoate Tokichi phase → Smectic A fI-22) n-CaHt s O+sH+ 5-n4-n-hexyl-4'-〇-hexyloxybiphenyl Tokichi phase → Smectic B + Smectic E (I-231 4-n-hexyloxyphenyl-4'-〇-octyloxybiphenyl-4-carboxylate Tokichi phase → Nematic → Smectic A → Smectic C → Smectic B (I-241 Di-n-octyl-4 sylate 4″-terphenyldicarphoki etc. → Smectic A → Smectic C (I-25) n-hexyl-4′-1-pentyloxybiphenyl-
4-carboxylate (6508C) and other lucky phases → smectic A → smectic B → smectic E 4-n-hexyl-4'-n-decyloxybiphenyl-4-carboxylate and other lucky phases → smectic A → smectic C (I-27 ) 4-n-hebutyloxyphenyl-4-n-decyloxybenzoate, etc. Yoshi phase → Smectic A → Smectic C Good alignment can also be obtained by the alignment method. Methods that ensure molecular alignment include -axial stretching;
Stretching methods such as biaxial stretching and inflation stretching, and rearrangement by shearing are preferred. Those that do not have film properties and are difficult to stretch when used alone can be co-stretched by sandwiching them into a film to obtain a desired orientation.

Next, polymer films that can be used as a substrate include, but are not limited to, those shown below.

In other words, low-density polyethylene film, high-density polyethylene film (Mitsui Toatsu Chemical Co., Ltd. Hybron, etc.), polypropylene film (Toshi Torefane, etc.), polyester film (DuPont Mylar, etc.), polyvinyl alcohol film (Nippon Gosei Kagaku Kogyo Hi-Selon, etc.),
Polyamide film (Toyo Gosei Film Rayfan, etc.), polycarbonate film (Music University Tijinpan Light, etc.), polyimide film (DuPont KAPTON, etc.), polyvinyl chloride film (Mitsubishi Plastics Hisilex, etc.), polyethylene fluoride film (Mitsui Plastics, etc.) Fluorochemicals (Teflon, etc.), polyacrylic film (Sumitomo Bakelite, Sumilite), polystyrene film (Asahi Dow Stylosheet), polyvinylidene chloride film (Asahi Dowsaran Film), cellulose film, polyvinyl fluoride film (DuPont Tetra), etc. It will be done.

In the present invention, a polarizing film, a polarizing beam splitter, etc. can be used as the polarizing plate.

In the display element of the present invention, when displaying using the effect of heating, a thermal head or laser light can be used.

As the laser light, He-Ne gas laser Ar2"
Gas lasers Gas lasers such as N2 gas lasers,
It is desirable to use a solid laser such as a ruby laser, a glass laser, or a YAG laser, or a semiconductor laser. Further, a semiconductor laser having a wavelength range of 600 nm to 1600 nm is preferably used. Particularly preferably, a semiconductor laser having a wavelength in the range of 600 to 900 nm is used. Further, by using the second and third harmonics of these laser beams, it is possible to shorten the wavelength.

When using laser light, either provide a separate light absorption layer or
Alternatively, it is used after being dispersed and dissolved in the display layer. If the display surface is affected by a light absorbing layer or light absorbing agent, it is desirable that the display surface has no absorption in the visible light region.

Examples of laser light absorbing compounds added to the polymer liquid crystal layer include azo compounds, bisazo compounds, trisazo compounds, anthraquinone compounds, naphthoquinone compounds, phthalocyanine compounds, naphthalocyanine compounds, and tetrabenzoporphyrin compounds. compounds, aminium salt compounds, diimonium salt compounds, metal chelate compounds, etc.

Among the above laser light absorbing compounds, 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 polymeric liquid crystal compounds. In addition, some compounds have dichroism, and if these dichroism compounds are mixed into polymer liquid crystals, thermally stable host-guest memory and display media can be obtained. .

Further, the polymeric liquid crystal compound may contain two or more types of the above-mentioned compounds.

Further, the above compound may be combined with other near-infrared absorbing dyes or dichroic dyes. Representative examples of near-infrared absorbing dyes that may be suitably combined include cyanine, merocyanine, phthalocyanine, tetrahydrocholine, dioxazine, anthraquinone, triphuedithiazine, xanthine, triphenylmethane, biryllium, croconium, azulene, and triphenylamine. Examples include dyes such as.

The amount of the above compound added to the polymeric liquid crystal compound is about 0.1 to 20% by weight, preferably 0.5 to 20%.
lO% is good. The polymeric liquid crystal compound used in the present invention is a polymeric thermotropic liquid crystal, and uses a nematic, smectic, chiral smectic, or cholesteric phase as an intermediate phase.

As more specific light-absorbing dyes, the following can be used.

Direct Red 28 Direct Violet 12 Direct Blue 1 Direct Blue 15 Direct Blue 98 Direct Blue 151 Direct Red 81 Direct Yellow 44 Direct Yellow 12 Direct Orange 39 υ NI'I2 ONl(.

Disperse Blue 214 Disperse Red 60 　0H Disperse Yellow 56AsFs” Cj! O4゜ [Example code] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 A polymeric liquid crystal compound represented by the following structural formula (I) was dissolved in cyclohexanone to prepare a 20 wt % solution.

+CH-CH2)- A polyimide alignment film (high purity polyimide alignment film (Sunever 100) manufactured by Nissan Chemical Industries, Ltd.) was coated with a spinner on a glass substrate on which 3000 Cr thick was deposited as a reflective layer electrode, and then baked. It was formed by Thereafter, uniaxial orientation was imparted by a rubbing method.

The polymer liquid crystal solution was applied to this substrate using a spinner at 3000 rpm, and the thickness after drying was 0.81 J.m.

Good uniaxial orientation was obtained by heat treatment at 105° C. for 3 hours. The retardation Δnd of the portion where Cr was not deposited was measured using a polarizing microscope with a Berek compensator (visible light wavelength λ: 500 to 600 nm) and found to be 140 nm.

Next, a display element was fabricated by pressure-bonding a glass substrate on which an ITO transparent electrode with a thickness of 2,000 wafers was deposited, and a substrate on which an SiO2 insulating film was further deposited with a thickness of 2,000 wafers on the alignment-treated substrate.

When the reflectance at 550 nm was measured with the polarization plane of the polarizing plate at an angle of 45° with the polymer liquid crystal alignment axis, it was 2%.

Next, an 8-inch tube was placed between the upper and lower substrates of the display element heated to 100°C.
When a voltage of 0 V was applied, the -axis orientation disappeared.

Similarly, when the reflectance at 550 nm was measured with the polarizing plate at an angle of 45°, it was 40%.

Furthermore, when the same reflectance measurement as above was carried out using a xenon lamp, good contrast with high reflectance was obtained, with a reflectance of 4% for the -axis orientation substrate and 39% for the voltage applied substrate.

Example 2 An IR absorbing dye represented by the following structural formula (n) was added to the polymer liquid crystal cyclohexanone solution used in Example 1 in an amount of 1.0 wt % based on the polymer liquid crystal compound.

(C2Hri2N is)' Meeting N(C+)js)zC
j) O,'' (n) This solution was applied to a Cr-coated substrate in the same manner as in Example 1 and subjected to alignment treatment.The retardation was measured using a polarizing microscope using a polarizing microscope. When measured with a compensator (visible light wavelength λ = 500 to 600 nm), it was 141 nm.

Next, an ITO transparent polarized lath substrate similar to that in Example 1 was pressure-bonded to obtain a display element.

A display section was created by focusing an 830 nm, 50 mW semiconductor laser onto this display element at room temperature to a diameter of about 104+ m and scanning it. When the polarization plane of the polarizing plate was set at 45'' with respect to the alignment axis, the reflectance by xenon lamp irradiation was measured, and the reflectance of the display area was 35% and the reflectance of the non-display area was 3%, which was a high reflectance and good contrast. was gotten.

Example 3 Polyethersulfone (PES) with a thickness of 1100p
After depositing Aj) on the film to a thickness of 1000 mm, an aqueous polyvinyl alcohol solution was applied thereon by dipping, and after drying, a film thickness of 5 mm was formed. Next, after heat treatment at 120°C, uniaxial orientation was imparted by rubbing.

The polymer liquid crystal cyclohexanone solution prepared in Example 1 was applied to this film substrate by a barcode method, and the film thickness after drying was 0.9 gm. When this substrate was heat treated, good uniaxial orientation was obtained. The retardation Δnd (visible light wavelength =
500-600 nm) was measured and found to be 135 nm. After applying a heat pulse to this film substrate using a thermal head, we measured the reflectance by xenon lamp irradiation with the polarization plane of the polarizing plate set at 45 degrees with respect to the alignment axis.The reflectance of the heat pulse application part was 42%. A high reflectance of 4% in the non-applied area and good contrast were obtained.

Example 4 0.63 g and 0.67 g of monomers of the following structural formulas (III) and (IV), respectively, were dissolved in dry toluene, 3 moj)% AIBN was added, and the mixture was frozen and degassed at 60°C. The reaction was allowed to proceed for 24 hours. Reprecipitation in methanol (repeatedly.

0.68 g of polymer was obtained. (Yield 52%) (II
I) (IV) Number average molecular weight Weight average molecular weight Phase transition temperature ("C) Optical rotation [cxl2'=+8.9° (CHCj'a)
Dissolve the above polymer liquid crystal copolymer in chloroform and
It was set as wt%.

Next, a polyimide alignment film (high purity polyimide varnish Sunever 100, manufactured by Nissan Chemical Industries, Ltd.) was formed on a card-shaped glass substrate on which AP was deposited to a thickness of 3000 mm, and uniaxial alignment was imparted by a rubbing method. A similar process was applied to a glass substrate on which ITO was deposited to a thickness of 1000 nm.

The above liquid crystal copolymer solution was applied onto the ITO glass substrate using a spinner, and after drying, the glass substrate with AiJ was pressure-bonded to a film thickness of 0.81 J, m, heated and cooled, and sealed. Orientation was performed by

Next, +40V was applied between the upper and lower substrates, and uniaxial orientation was achieved by cooling from 90°C. The retardation measured using a polarizing microscope was 140 nm.

When the reflectance by xenon lamp irradiation was measured with the initial orientation axis aligned with the polarization plane of the polarizing plate, it was 39%. Next, when the reflectance was measured by applying 140 cm between the upper and lower substrates at 70° C., it was 5%, and a high reflectance and good contrast were obtained.

When +40V was applied to a polymer liquid crystal copolymer film with a thickness of 104m, the response speed was 20m5ec at 70°C.
In the above example, the speed was 2 m5ec.

[Effects of the Invention] As explained above, according to the present invention, by using a display layer containing a uniaxially aligned polymer liquid crystal on a reflective layer, a high reflectance can be achieved with only one polarizing plate. A display element with good contrast could be obtained.

Furthermore, it became possible to reduce the thickness of the display layer, resulting in the effect of improving response speed.

[Brief explanation of drawings]

1(a) and 1(b) show an example of the display element of the present invention, FIG. 1(a) is a plan view of the display element of the present invention, and FIG.
b) is a cross-sectional view taken along the line AA', and FIG. 2 is an explanatory diagram showing the relationship between the incident linearly polarized light, the outgoing linearly polarized light, and the alignment axis of the display layer containing a polymeric liquid crystal compound in the display element of the present invention. 1.1'...Substrate 2...Reflection layer electrode 2'...
・Transparent electrode 3...Display layer 4...Spacer
5, 5'... Orientation control film 6... Adhesive 7... Polarizing plate 8... Incident linearly polarized light 9... Display layer alignment axis 10... Outgoing linearly polarized light

Claims (3)

[Claims] (1) In a display element having a display layer containing a polymeric liquid crystal compound between a polarizing plate and a reflective layer, the display layer is uniaxially aligned and its retardation is λ(m± 1/4) (m is an integer including 0, when m = 0 +
Only 1/4, λ indicates visible light wavelength (μm). ) A display element characterized by: (2) The polarization axis of the polarizing plate and the orientation axis of the display layer are 35 to 5.
2. A display element according to claim 1, having an angle of 5[deg.]. (3) The display element according to claim 1, wherein the reflective layer has a function as an electrode.