JP2005215299A - Display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display element, which is bright, which has excellent visibility and precision and of which the problem of crystallization and deposition of a fluorescence dye mixed in a liquid crystal is solved, in the display element having a liquid crystal/polymer layer comprising the liquid crystal and the polymer dispersed in each other and disposed between two sheets of electrodes. <P>SOLUTION: The display element having the liquid crystal/polymer layer in which the liquid crystal and the polymer are mutually dispersed disposed between two sheets of the electrodes, contains a liquid crystal compound exhibiting a fluorescence spectrum in the visible region in the liquid crystal/polymer layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a display element used for a reflective or transmissive liquid crystal display.

In recent years, polymer-dispersed liquid crystal display elements have attracted attention as display elements that do not use polarizing plates. Since this method does not use a polarizing plate, incident light can be used more efficiently than a twisted nematic liquid crystal display device using two conventional polarizing plates. Examples thereof include R.I. A. M.M. Hikmet et al. Can mention a polymer-dispersed liquid crystal display element in which a liquid crystal is dispersed in a polymer gel network and the polymer and the liquid crystal are aligned (for example, Non-Patent Document 1). However, visibility and / or fineness existed as a fundamental problem of this method. Therefore, for the purpose of improving the visibility of the display element, in a polymer dispersed liquid crystal display element, a liquid crystal / polymer layer is mixed with a fluorescent dye (for example, see Patent Documents 1 and 2).
JP-A-5-142582 JP-A-5-224181 “Liquid Crystal (Liq. Cryst.)”, 1991, Vol. 9, p. 405

However, fluorescent dyes such as coumarins and cyanines that have been used in conventional display elements generally have low solubility in liquid crystal materials, and the fluorescent dye mixed in the liquid crystal may crystallize and precipitate. In addition, the emission dichroism of the fluorescence is low, and it is difficult to ensure a sufficient contrast during display.
The object of the present invention is to solve the problem that the fluorescent dye mixed in the liquid crystal is crystallized and deposited in a display element in which a liquid crystal / polymer layer in which liquid crystal and polymer are dispersed is disposed between two electrodes. And, it is to provide a display element that is bright and has good visibility and fineness.

The above problem is solved by the following means. That is, the present invention
<1> A display device in which a liquid crystal / polymer layer in which liquid crystal and a polymer are dispersed between each other is disposed between two electrodes, and the liquid crystal / polymer layer includes a liquid crystal compound exhibiting a fluorescence spectrum in the visible region. A display element.
<2> The display element according to <1>, wherein the liquid crystal / polymer layer is subjected to orientation treatment and dispersed.

<3> The display element according to <1> or <2>, wherein the display element is a reflective display element.
<4> The display element according to <1> or <2>, wherein the display element is a transmissive display element.
<5> The display element according to any one of <1> to <4>, wherein the liquid crystal compound exhibiting a fluorescence spectrum in the visible region is a compound represented by the following general formula (I).

（式中、Ａは−Ｎ＝、あるいは−ＣＨ＝を示す。Ａｒ¹、Ａｒ²は独立して環員数５乃至１０の芳香環を示し、Ｂは単結合、あるいは環員数５乃至１０の芳香環を示し、Ａｒ¹、Ａｒ²、Ｂは環上に置換基を有していてもよい。Ｘ¹は単結合、−Ｏ−、−Ｓ−、−ＮＨ−、−ＮＲ¹−、−ＣＯＯ−、−ＯＣＯ−、−ＣＯＮＨ−、又は−ＮＨＣＯ−を示し、Ｒ¹は炭素数１〜４のアルキル基を示す。Ｘ²は電子求引性基、あるいは−Ｘ³−Ｌ²を示す。Ｘ³は単結合、−Ｏ−、−Ｓ−、−ＮＨ−、−ＮＲ²−、−ＣＯＯ−、−ＯＣＯ−、−ＣＯＮＨ−、−ＮＨＣＯ−を示し、Ｒ²は炭素数１〜４のアルキル基を示す。Ｌ¹、Ｌ²は独立して水素原子、あるいは炭素数１乃至２０のアルキル基を示す。Ｓを含む５員環は置換基を有していてもよい。）

(In the formula, A represents —N═ or —CH═. Ar ¹ and Ar ² independently represent an aromatic ring having 5 to 10 ring members, and B represents a single bond or an aromatic ring having 5 to 10 ring members. A ring, Ar ¹ , Ar ² , B may have a substituent on the ring, X ¹ is a single bond, —O—, —S—, —NH—, —NR ¹ —, —COO; -, -OCO-, -CONH-, or -NHCO-, wherein R ¹ represents an alkyl group having 1 to 4 carbon atoms, X ² represents an electron-withdrawing group or -X ³ -L ² . X ³ represents a single bond, —O—, —S—, —NH—, —NR ² —, —COO—, —OCO—, —CONH—, —NHCO—, and R ² has 1 to 4 carbon atoms. L ¹ and L ^{2 each} independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and the 5-membered ring containing S may have a substituent.

  According to the present invention, a crystal of a fluorescent dye mixed in a liquid crystal is used by using a liquid crystal compound exhibiting a fluorescence spectrum in the visible region in a liquid crystal / polymer layer in which a liquid crystal and a polymer are dispersed between two electrodes. It is an object of the present invention to provide a display device that can improve the yield by improving the yield, and can obtain high contrast based on high dichroism based on the structural characteristics of the liquid crystal compound, and is bright and has high visibility.

  The present invention relates to a display device in which a liquid crystal / polymer layer is dispersed between two electrodes, preferably a liquid crystal / polymer layer in which the liquid crystal and the polymer are phase-separated, and a fluorescence spectrum in the visible region. And a liquid crystal / polymer layer. In addition, an alignment film, an alignment layer, and the like can be provided between the electrode and the liquid crystal / polymer layer of the display element of the present invention.

Below, the display element of this invention is demonstrated in detail using FIG. 1 and 2 are examples of the display element of the present invention, but the present invention is not limited to this.
The display element (10) of the present invention has a liquid crystal / polymer layer (4) sandwiched between a pair of electrodes (2) in FIG. 1, and the liquid crystal / polymer layer exhibits a fluorescence spectrum in the visible region. It contains a liquid crystal compound.

The pair of electrodes in the present invention is not particularly limited, but may be provided on a substrate such as glass or polymer.
At least one of the two electrodes in the form of the reflective display element is preferably a transparent electrode. In the form of a transmissive display element that does not use a reflector, it is preferable that both of the two electrodes are transparent electrodes. Examples of preferable transparent electrodes include indium tin oxide (ITO), fluorine-doped tin oxide (FTO), and antimony-doped tin oxide.
The ITO transparent electrode portion (2) can be formed on the two glass substrates (1) by a known method. As the electrode forming method, a sputtering method, a vapor deposition method, a coating method, or the like can be appropriately employed and is not particularly limited.

In the present invention, the liquid crystal / polymer layer in which the liquid crystal and the polymer are dispersed with each other is preferably subjected to orientation treatment and dispersed. Here, the alignment treatment and dispersion means that liquid crystal and polymer are dispersed and aligned.
As a method of aligning the liquid crystal / polymer layer, various known methods can be adopted, but a method of aligning the electrode surface is preferable.
As a method for the orientation treatment, a method such as a vertical orientation treatment, a horizontal orientation treatment, and a SiO oblique deposition treatment is adopted as necessary.
As examples of the vertical alignment treatment method, a quaternary ammonium salt dipping treatment, a method using a vertical alignment film such as a polymerized film, an alignment layer by chemical bonding, or the like can be employed. Here, a preferable example of the quaternary ammonium salt includes cetyltrimethylammonium bromide.
The vertical alignment film is not particularly limited, and a known film such as hexamethyldisiloxane can be used.
The alignment layer by chemical bonding is not particularly limited, and a known method such as treatment with an organic silane coupling agent or a monobasic chromium complex can be employed.
Regarding the horizontal alignment treatment method, for example, a method of rubbing a known horizontal alignment film such as polyvinyl alcohol (PVA) or polyimide (PI), or a method of aligning with polarization using a photo-alignment film can be adopted. It is not particularly limited. Further, as the SiO oblique vapor deposition method, a method of vapor deposition by tilting the substrate with respect to the vapor deposition beam in a vacuum chamber can be employed.

  The display element of the present invention can use an excitation light source. The excitation light source can be disposed around the background plate by disposing a background plate on the back of one electrode of the display element of the present invention. Alternatively, a reflecting plate may be disposed between the back electrode and the back substrate, and an excitation light source may be disposed on the light irradiation surface side.

The wavelength of the excitation light source is preferably one corresponding to the excitation wavelength of a liquid crystal compound exhibiting a fluorescence spectrum in the visible region to be used, and the excitation light source may be an ultraviolet light source.
The excitation light source may be any light source that can irradiate the excitation wavelength. For example, a laser, an LED, an ultraviolet lamp, or the like can be used. Further, light may be irradiated from the back using a waveguide plate or the like.

  Furthermore, in the present invention, it is also possible to perform multicolor display by combining the display elements having different fluorescence wavelengths. At this time, a shading process can be performed between the pixels. As a specific method for multicolor display, for example, a method can be used in which pixels corresponding to the three primary colors are created and arranged on a grid, and each pixel is switched by a color display signal to perform color display. .

  In the present invention, disposing a liquid crystal / polymer layer in which liquid crystal and polymer are dispersed between two electrodes is arranged between the electrodes disposed in parallel on a single substrate. A structure in which layers are arranged is also included.

The formation of the liquid crystal / polymer layer will be described below.
The liquid crystal / polymer layer is a layer in which liquid crystal and polymer are mixed and dispersed with each other, and the liquid crystal needs to contain a liquid crystal compound exhibiting a fluorescence spectrum in the visible region. However, it is preferable to further contain a liquid crystal.
The liquid crystal / polymer layer includes a liquid crystal compound exhibiting a fluorescence spectrum in the visible region (400 to 800 nm), a mixture of monomers that form a polymer, and, if necessary, the liquid crystal, and is formed between two electrodes. It can be formed by enclosing in a cell and polymerizing the monomer.

The liquid crystal is made of a substance that forms a liquid crystal, and an ordinary known liquid crystal can be adopted as the liquid crystal, and it may be a single substance or a mixture. Specifically, E7 (made by Merck), ZLI-2806 (made by Merck), etc. are mentioned.
With respect to the dielectric anisotropy of the liquid crystal, a liquid crystal having a positive or negative dielectric anisotropy is appropriately employed according to the configuration of the target element.
The content of the liquid crystal is preferably 30 to 95% by mass, more preferably 50 to 95% by mass, and 70 to 95% by mass with respect to the total solid mass of the liquid crystal / polymer layer. It is particularly preferred that By setting the content to 30 to 95% by mass, the visibility and fineness of the display element tend to be good.
The content of the liquid crystal compound exhibiting a fluorescence spectrum in the visible region is preferably 0.5 to 50% by mass, and preferably 1 to 25% by mass with respect to the total liquid crystal of the liquid crystal / polymer layer. Further preferred. These liquid crystal compounds can be used alone or in combination of two or more. In the present invention, a dichroic dye can be appropriately added to the liquid crystal compound in the liquid crystal phase of the liquid crystal / polymer layer.

As the monomer for forming the polymer, any monomer that can be polymerized can be used. For example, a photopolymerizable, thermal polymerizable, or electron beam polymerizable monomer can be used. Preferred examples thereof include acrylic monomers (for example, paraphenylphenol acrylate), methacrylic monomers (for example, paraphenylphenol methacrylate), and the like. The monomer herein is meant to include polymerizable oligomers.
The content of the polymer obtained from the monomer that forms the polymer is preferably 0.1 to 50% by mass, and preferably 1 to 50% by mass, based on the total solid mass of the liquid crystal / polymer layer. It is more preferable that it is 5-30 mass%. By setting the content to 0.1 to 50% by mass, the visibility and fineness of the display element tend to be good.
Furthermore, you may add additives, such as a crosslinking agent, a polymerization initiator, a polymerization inhibitor, a viscosity modifier, a liquid crystal transition temperature lowering agent, and a liquid crystal transition temperature increasing agent as needed.

  The method for forming the liquid crystal / polymer layer is not limited to the above method, and for example, a liquid crystal compound or a liquid crystal exhibiting a fluorescence spectrum in the visible region for forming a liquid crystal phase can be dissolved in a thermoplastic polymer or a solvent. A method of adding to and dispersing in a high polymer can also be employed.

The liquid crystal compound in which the mother nucleus used in the present invention exhibits a fluorescence spectrum in the visible region will be described below.
As a preferred example of the liquid crystal compound, the liquid crystal compound preferably has a structure represented by the following general formula (I).

（式中、Ａは−Ｎ＝、あるいは−ＣＨ＝を示す。Ａｒ¹、Ａｒ²は独立して環員数５乃至１０の芳香環を示し、Ｂは単結合、あるいは環員数５乃至１０の芳香環を示し、Ａｒ¹、Ａｒ²、Ｂは環上に置換基を有していてもよい。Ｘ¹は単結合、−Ｏ−、−Ｓ−、−ＮＨ−、−ＮＲ¹−、−ＣＯＯ−、−ＯＣＯ−、−ＣＯＮＨ−、又は−ＮＨＣＯ−を示し、Ｒ¹は炭素数１〜４のアルキル基を示す。Ｘ²は電子求引性基、あるいは−Ｘ³−Ｌ²を示す。Ｘ³は単結合、−Ｏ−、−Ｓ−、−ＮＨ−、−ＮＲ²−、−ＣＯＯ−、−ＯＣＯ−、−ＣＯＮＨ−、又は−ＮＨＣＯ−を示し、Ｒ²は炭素数１〜４のアルキル基を示す。Ｌ¹、Ｌ²は独立して水素原子、あるいは炭素数１乃至２０のアルキル基を示す。Ｓを含む５員環は置換基を有していてもよい。）

(In the formula, A represents —N═ or —CH═. Ar ¹ and Ar ² independently represent an aromatic ring having 5 to 10 ring members, and B represents a single bond or an aromatic ring having 5 to 10 ring members. A ring, Ar ¹ , Ar ² , B may have a substituent on the ring, X ¹ is a single bond, —O—, —S—, —NH—, —NR ¹ —, —COO; -, -OCO-, -CONH-, or -NHCO-, wherein R ¹ represents an alkyl group having 1 to 4 carbon atoms, X ² represents an electron-withdrawing group or -X ³ -L ² . X ³ represents a single bond, —O—, —S—, —NH—, —NR ² —, —COO—, —OCO—, —CONH—, or —NHCO—, and R ² represents 1 to 4 carbon atoms. L ¹ and L ^{2 each} independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and the 5-membered ring containing S may have a substituent. )

Here, A represents -N = or -CH =, but is preferably -N =. Ar ¹ and Ar ² independently represent an aromatic ring having 5 to 10 ring members. Examples of the aromatic ring having 5 to 10 ring members include benzene ring, naphthalene ring, thiophene ring, thiazole ring, benzofuran ring, benzo ring, Examples include a thiophene ring and a benzothiazole ring. Preferable examples of Ar ¹ and Ar ² include a benzene ring, a naphthalene ring, and a thiophene ring, and a benzene ring and a naphthalene ring are particularly preferable.

B represents a single bond or an aromatic ring having 5 to 10 ring members. Examples of the aromatic ring having 5 to 10 ring members include benzene ring, naphthalene ring, thiophene ring, thiazole ring, benzofuran ring, benzothiophene ring, benzo Examples include a thiazole ring. Examples of preferable B include a single bond, a thiazole ring, and a thiophene ring, and a single bond and a thiazole ring are particularly preferable.
Note that the 5-membered ring containing Ar ¹ , Ar ² , B, and S in the formula may have a substituent, and examples of the substituent include an alkyl group having 1 to 4 carbon atoms, 4 alkoxy groups, halogen atoms, cyano groups, and nitro groups. Preferred examples of the substituent include an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms, and a methyl group, an ethyl group, and a methoxy group are particularly preferable.

X ¹ is a single bond, -O -, - S -, - NH -, - NR 1 -, - COO -, - OCO -, - CONH -, - NHCO- and shows, -O -, - NR ¹ -, -COO-, and -OCO- are preferred. R ¹ represents an alkyl group having 1 to 4 carbon atoms, preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

X ² represents an electron withdrawing group or —X ³ -L ² . Here, the electron withdrawing group refers to a substituent having a positive Hammett's rule substituent constant σp value. For the Hammett's σp value, see Chem. Rev. Journal, Vol. 91, pages 165-195 (1991) can be applied. Specific preferred examples include a cyano group and a nitro group. When X ² represents a -X ³ -L ^2, X ³ is ^{-O -, - NR 2 -,} - COO -, - OCO- is preferred. R ² represents an alkyl group having 1 to 4 carbon atoms, preferably a methyl group or an ethyl group, and particularly preferably a methyl group.

L ¹ and L ^{2 each} independently represents an alkyl group having 1 to 20 carbon atoms, preferably 2 to 14 carbon atoms, particularly preferably 2 to 10 carbon atoms.
Further, the alkyl group may have one or more substituents. At this time, preferred examples of the substituent include a methyl group and an ethyl group. At this time, the configuration may be any of R, S and any mixture.

  Preferred specific examples of the liquid crystal compound exhibiting a fluorescence spectrum in the visible region of the present invention include the following compounds, but are not limited thereto.

In the following, the liquid crystal transition temperature is shown as the phase behavior of the liquid crystal compound, and the liquid crystal phase transition temperature in the temperature lowering process is shown in parentheses. Further, the following S _A phase smectic A phase,
The S _C phase represents a smectic C phase, the S _X2 phase represents a smectic X ₂ phase, the S _X1 phase represents a smectic X ₁ phase, and the N phase represents a nematic phase.

(Liquid crystal phase transition temperature)
Compound 1-1 Crystal 174 ° C. (163 ° C.) S _A Phase 212 ° C. (207 ° C.) Isotropic Compound 1-2 Crystal 167 ° C. (154 ° C.) S _C Phase 177 ° C. (173 ° C.) S _A Phase 192 ° C. (189 ° C) Isotropic phase compound 1-3 crystals 30 ° C (<25 ° C) S _C phase 62 ° C (46 ° C) S _A phase 90 ° C (87 ° C) Isotropic phase compound 1-4 crystals 66 ° C (<50 ° C) S _C phase 72 ° C (53 ° C) S _A phase 96 ° C (90 ° C) Isotropic phase

(Liquid crystal phase transition temperature)
Compound 2-1 Crystal 76 ° C. (64 ° C.) S _C phase (72 ° C.) S _A phase 89 ° C. (85 ° C.) Isotropic phase compound 2-2 Crystal 71 ° C. (66 ° C.) S _C phase 80 ° C. (77 ° C.) S _A phase 87 ° C (83 ° C) Isotropic compound 2-3 Crystals 79 ° C (<65 ° C) (S _X2 phase 65 ° C) (S _X1 phase 71.5 ° C) Isotropic phase (monotropic)
Compound 2-4 Crystal 74 ° C (59 ° C) S _m phase 79 ° C (67 ° C) Isotropic phase

(Liquid crystal phase transition temperature)
Compound 3-1 Crystal 181 ° C N phase 342 ° C Isotropic compound 3-2 Crystal 190 ° N phase 326 ° C Isotropic phase

  As described above, the manufactured display element can be used for a reflective or transmissive display.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, it is not limited to these.

(Example 1)
In this embodiment, an example in which the liquid crystal / polymer layer (4) shown in FIG. 1 is horizontally aligned and dispersed will be described.
In FIG. 1, a liquid crystal cell (E-etch eye) having a 10 μm gap composed of a glass substrate (1) having an ITO transparent electrode portion (2) on which a polyimide alignment film (3) subjected to horizontal alignment treatment by rubbing is formed. A mixture of room temperature liquid crystal E7 (Merck) (5), compound 2-3 (6), and paraphenylphenol methacrylate (precursor of 7) having a positive dielectric anisotropy (mixing ratio, 70) : 5: 25) was encapsulated under heating at 110 ° C. and gradually cooled to horizontally align the liquid crystal / polymer layer (4).
Next, ultraviolet rays (maximum emission wavelength: 360 nm) were irradiated at room temperature using an ultraviolet irradiator (EXECULE 3000, manufactured by HOYA-SCOTT) to produce a display element. A display element could be obtained without crystallizing the liquid crystal.
The fluorescence spectrum characteristics of the compound 2-3 (6) exemplified above in a chloroform solution were a fluorescence peak wavelength: 525 nm and an excitation wavelength: 378 nm.
When a black background plate (not shown) is placed on the back surface of the display element, the background black can be seen when no electric field is applied (FIG. 1A), and when an electric field is applied (FIG. 1B), it becomes fluorescent due to scattering. The corresponding color was visible. This display element was able to show an electro-optic response with high contrast and good visibility.
Furthermore, when an ultraviolet lamp was disposed in the display element and an electric field was applied, the fluorescent color excited by the ultraviolet light was scattered and observed, and the user was able to see a very bright display. In this case, the ultraviolet light was not visible to the user, and the user was able to observe the display with a high color purity of only the fluorescent color.

(Example 2)
In FIG. 1, a liquid crystal cell (E-etch eye) having a 10 μm gap composed of a glass substrate (1) having an ITO transparent electrode portion (2) on which a polyimide alignment film (3) subjected to horizontal alignment treatment by rubbing is formed. A room temperature liquid crystal E7 (Merck) (5), compound 3-2 (6), paraphenylphenol methacrylate (precursor 7), polymerization inhibitor hydroquinone monomethyl ether having positive dielectric anisotropy The mixture (mixing ratio, 75: 3: 22) was sealed under heating at 220 ° C. and gradually cooled to horizontally align the liquid crystal / polymer layer (4).
Next, ultraviolet rays (maximum emission wavelength: 360 nm) were irradiated at room temperature using an ultraviolet irradiator (EXECULE 3000, manufactured by HOYA-SCOTT) to produce a display element. The display element could be obtained without crystallizing the liquid crystal.
The fluorescence spectrum characteristics of the compound 3-2 (6) exemplified above in a chloroform solution were a fluorescence peak wavelength: 483 nm and an excitation wavelength: 395 nm.
When a black background plate was placed on the back of the display element, the background black was seen when no electric field was applied, and a color corresponding to the fluorescent color was seen by scattering when an electric field was applied. This display element was able to show an electro-optic response with high contrast and good visibility.
Furthermore, when an ultraviolet lamp was disposed in the display element, when an electric field was applied, the fluorescent color excited by the ultraviolet light was scattered and observed, and the user was able to see a very bright display. In this case, the ultraviolet light was not visible to the user, and the user was able to observe the display with a high color purity of only the fluorescent color.

(Example 3)
An ITO transparent electrode part (2) was formed on a pair of polycarbonate substrates (1) by sputtering. A coating film was formed by spin coating on the electrode side of the pair of substrates (1) on which the ITO transparent electrode part (2) was formed, and a rubbing treatment was performed to form a polyvinyl alcohol alignment film (3).
Next, room temperature having positive dielectric anisotropy between the polycarbonate substrate (1) having a pair of ITO transparent electrode portions (2) on which the obtained polyvinyl alcohol alignment film (3) subjected to the horizontal alignment treatment is formed. A mixture (mixing ratio, 70: 5) of liquid crystal E7 (Merck) (5), compound 2-3 (6), paraphenylphenol methacrylate (precursor of 7), and true sphere (diameter 8 μm, manufactured by Catalyst Chemical Industries). : 25: 0.01), and a flat copper plate was placed on the substrate opposite to the electrode part, and the temperature was changed to 110 ° C. Then, the liquid crystal / polymer layer (4) was horizontally aligned by gradually cooling. .
Next, the copper plate was removed, and ultraviolet rays (maximum emission wavelength 360 nm) were irradiated using an ultraviolet irradiator (EXECULE 3000, manufactured by HOYA-SCOTT) to produce a display element. The display element could be obtained without crystallizing the liquid crystal.
The fluorescence spectrum characteristics of the compound 2-3 (6) exemplified above in a chloroform solution were a fluorescence peak wavelength: 525 nm and an excitation wavelength: 378 nm.
It was confirmed that the brightness of the display element can be adjusted by changing the scattering state of the display element by changing the electric field application state of the obtained display element.

Example 4
In this embodiment, an example in which the liquid crystal / polymer layer (4) shown in FIG. 2 is vertically aligned and dispersed will be described.
In FIG. 2, in a liquid crystal cell (manufactured by E-etch Eye Co., Ltd.) having a gap of 10 μm composed of a glass substrate (1) having an ITO transparent electrode portion (2) vertically aligned with cetyltrimethylammonium bromide, Room temperature liquid crystal ZLI-2806 (manufactured by Merck) having dielectric anisotropy (5), compound 2-3 (6), and a mixture of p-phenylphenol methacrylate (precursor of 7) (mixing ratio, 70: 5: 25) ) Was sealed under heating at 110 ° C., and was gradually cooled to vertically align the liquid crystal / polymer layer (4).
Next, a display element was produced by irradiating ultraviolet rays at room temperature using an ultraviolet irradiator (EXECULE 3000, manufactured by HOYA-SCOTT). The display element could be obtained without crystallizing the liquid crystal.
The fluorescence spectrum characteristics of the compound 2-3 (6) exemplified above in a chloroform solution were a fluorescence peak wavelength: 525 nm and an excitation wavelength: 378 nm.
When a black background plate (not shown) is placed on the back of the display element, the background black appears when no electric field is applied (FIG. 2 (A)), and when fluorescent is applied due to scattering when an electric field is applied (FIG. 2 (B)). The corresponding color was visible.
This display element was able to show an electro-optic response with high contrast and good visibility.
Furthermore, when an ultraviolet lamp was disposed in the display element, when an electric field was applied, the fluorescent color excited by the ultraviolet light was scattered and observed, and the user was able to see a very bright display. In this case, the ultraviolet light was not visible to the user, and the user was able to observe the display with a high color purity of only the fluorescent color.

  The display element of the present invention can be used as an electronic paper or a flexible display element as a bright reflective or transmissive display element.

BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram ((A) No voltage application state, (B) Voltage application state) which shows an example of the typical display element of this invention. It is a conceptual diagram ((A) voltage non-application state, (B) voltage application state) which shows another example of the typical display element of this invention.

Explanation of symbols

1 Substrate 2 Electrode (electrode part)
3 Alignment film or alignment layer (may be omitted)
4 Liquid Crystal / Polymer Layer 5 Liquid Crystal 6 Liquid Crystal Compound Showing Fluorescence Spectrum in Visible Region 7 Polymer 8 Liquid Crystal Alignment Direction 9 Polymer Alignment Direction 10 Display Element

Claims (5)

A display device in which a liquid crystal / polymer layer in which liquid crystal and polymer are dispersed between each other is disposed between two electrodes, and the liquid crystal / polymer layer includes a liquid crystal compound exhibiting a fluorescence spectrum in the visible region. element. The display device according to claim 1, wherein the liquid crystal / polymer layer is dispersed after being subjected to an alignment treatment. The display element according to claim 1, wherein the display element is a reflective display element. The display element according to claim 1, wherein the display element is a transmissive display element. The display device according to claim 1, wherein the liquid crystal compound exhibiting a fluorescence spectrum in the visible region is a compound represented by the following general formula (I).

(In the formula, A represents —N═ or —CH═. Ar ¹ and Ar ² independently represent an aromatic ring having 5 to 10 ring members, and B represents a single bond or an aromatic ring having 5 to 10 ring members. A ring, Ar ¹ , Ar ² , B may have a substituent on the ring, X ¹ is a single bond, —O—, —S—, —NH—, —NR ¹ —, —COO; -, -OCO-, -CONH-, or -NHCO-, wherein R ¹ represents an alkyl group having 1 to 4 carbon atoms, X ² represents an electron-withdrawing group or -X ³ -L ² . X ³ represents a single bond, —O—, —S—, —NH—, —NR ² —, —COO—, —OCO—, —CONH—, —NHCO—, and R ² has 1 to 4 carbon atoms. L ¹ and L ^{2 each} independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and the 5-membered ring containing S may have a substituent.

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