JP2001100665A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display images of bright display with a good contrast without depending upon visual field angles by allowing high-polymer gels to exist stably in a display layer. SOLUTION: This display device 10 has an exothermic layer 14, the display layer 16 and a filter layer 18 at need on a substrate 12. The display layer 16 has a binder resin 20, porous particles which are dispersed in the binder resin and the high-polymer gels which are fixed to the holes on the surfaces of the porous particles and are reversibly changed in volume by temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a novel image display device.

[0002]

2. Description of the Related Art Conventionally, as a display device of information equipment, C
RT (cathode ray tube) display monitor,
Liquid crystal displays, plasma displays, EL (electroluminescent) displays, field emission displays, and the like have been put to practical use.

[0003] Among these display devices, display monitors of desktop computers and notebook computers and display devices of personal digital assistants (PDAs) include:
There is a demand for thinner, lighter, and more diversified devices, and currently, liquid crystal display devices are used as display devices most suitable for such specifications.

[0004]

However, due to its structure, the liquid crystal display device has drawbacks related to the viewing angle, such as a change in contrast depending on the viewing angle and the occurrence of color inversion.
Furthermore, it has drawbacks such as darkness of display, complexity of the manufacturing process, and high cost.

As a display device which does not use liquid crystal having such a drawback, Japanese Patent Application Laid-Open No. 5-173190 discloses a display device using a gel polymer. This device is a non-light-emitting device in which a gel polymer that swells or shrinks depending on the presence or absence of electricity between a pair of substrates on which electrodes are arranged, swells the gel polymer, and transmits light. Alternatively, a voltage is applied to the gel to cause the gel to shrink, to generate irregularities on the surface, and to scatter light to perform light modulation. However, the size and shape of the irregularities generated by the contraction of the gel are irregular. Therefore, when a display device is formed by arraying elements, it is difficult to control light modulation with different scattering characteristics or reproducibility for each element. In addition, since the polymerization reaction is performed on the electrodes on the substrate, the electrodes may be deteriorated.

As a display device using a gel polymer, Japanese Patent Application Laid-Open No. Hei 5-188354 discloses a method in which gel polymer particles which swell or contract depending on the presence or absence of electricity between a pair of substrates on which electrodes are arranged. A non-emissive display device is disclosed. In this device, light modulation is performed by changing the size of gel-like polymer particles to change the state of light transmission or scattering. However, since the gel particles are only dispersed in the liquid in the cell, the gel particles precipitate or accumulate over time, and the dispersion state is biased.

Further, Japanese Patent Application Laid-Open No. Hei 9-160081 discloses a tuning method including a pair of substrates, an electrode provided between the substrates, and a functional gel disposed between the electrodes and deformed by an electric field applied between the electrodes. A light layer is provided, and by adjusting the amount of light incident on the light control layer by deformation of the functional gel, high contrast, high reflectance, and high light use efficiency are achieved without depending on the viewing angle. A novel display device suitable for a portable display device is disclosed. However, these gel particles are only dispersed in the cell, and have the same problems as the above, such as sedimentation, deposition, and uneven dispersion of the gel particles over time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a display device which does not depend on a viewing angle, has good contrast, is bright, and has stable gel particles.

[0009]

According to the present invention, there is provided a heat generating layer on a substrate, and a display layer provided on the heat generating layer. The display layer is dispersed in a binder resin. Porous particles, and fixed to the pores on the surface of the porous particles,
Provided is an image display device including a polymer gel having a color different from the color of a porous particle and having a volume that reversibly changes with temperature.

In this image display device, since the polymer gel is fixed to the pores on the surface of the porous particles dispersed in the binder resin, the polymer precipitates or accumulates over time. I will not do it. Also, since the polymer gel is polymerized before forming the display layer on the heat generating layer,
The electrode does not deteriorate as in the case where the polymer gel is directly polymerized on the electrode.

In this image display device, by swelling the polymer gel, the area occupied by the polymer gel on the surface of the porous particles increases, whereby the color of the polymer gel is displayed. On the other hand, by shrinking the polymer gel, the occupied area on the surface of the porous particles is reduced, and the color of the porous particles is displayed. An image is displayed by this contrast. Each of the porous particles and the polymer gel can be colored in an arbitrary color, and various colors can be displayed. As a result, the contrast is good regardless of the viewing angle,
A bright image can be displayed.

An ultraviolet-curable resin can be used as the binder resin. Further, it is preferable that the diameter of the porous particles is smaller than the heat generation range of one pixel of the heat generation layer. A filter layer may be provided on the display layer.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The image display device of the present invention includes a heat generating layer and a display layer on a substrate in this order.

As the material of the substrate, any material having a certain degree of heat resistance can be used, and examples thereof include glass, plastic, and ceramics.

The material of the heat generating layer is tantalum-SiO.
_2, a mixture of tantalum nitride, nichrome, silver-palladium alloy, silicon semiconductor, zirconium, titanium, tungsten, molybdenum, niobium, vanadium, and other metal borides can be used. A heating layer can be formed by applying these materials to a substrate by an electron beam method, an evaporation method, a sputtering method, or the like.
The thickness of the heat generating layer may be set so that the amount of heat generated per unit time becomes a desired value, and is usually 0.01 μm to 5 μm.
m. When the heat generating layer is formed in a matrix, an arbitrary heat generating pattern can be prepared according to image information. When a heat conductive pin formed of the above-described material is embedded in a resin or the like so that the head of the pin is exposed as a heat generating layer, an image formed by lateral heat diffusion is used. Can be prevented from decreasing.

The display layer used in the present invention comprises a binder resin, porous particles dispersed in the binder resin,
And a polymer gel fixed to pores on the surface of the porous particles.

As the binder resin, fluorine resin, acrylic resin, polyester resin, vinyl acetate resin,
Vinyl chloride resin, styrene-butadiene polymer, polyurethane resin, polystyrene resin, vinyl acetate-acryl copolymer, vinyl acetate-acrylamide copolymer, ethylene-vinyl acetate copolymer, epoxy resin, polyamide resin, and Silicone resin and the like can be mentioned. Further, an ultraviolet curable resin can also be used. Examples of the ultraviolet curable resin include urethane acrylate resins, epoxy acrylate resins, polyoxymethylene acrylate / hydrophilic vinyl monomer resins, acrylate group-containing polyurethane resins, and carboxyl group-containing unsaturated resins. These binder resins can be used alone or in combination.

Examples of the material of the porous particles include polyolefin, fluorine polymer, polysulfone, polyester, polyvinyl acetal, polyvinyl alcohol, polyamide, polyimide, polyurethane, polyacryl, polystyrene, polyketone, and the like. Silicone-based, polylactic acid-based, cellulose-based, chitosan-based and the like can be mentioned. These porous particles can be used alone or in combination.

As a method for producing porous particles, for example,
Emulsion solvent evaporation, microphase separation, spray drying, and the like can be mentioned. In addition, particles can be obtained by filtering the obtained slurry after decantation or treatment with a stabilizer.

The particle size of the porous particles is preferably smaller than the heating range of one pixel in the heating element, more preferably less than half, more preferably 20 to 50 μm. This eliminates the need for alignment between the pixels and the porous particles, and enables image display with excellent resolution.

The polymer gel changes its volume reversibly depending on the temperature. Examples of the material include polyethylene oxide, copolymers of ethylene oxide and propylene oxide, ether polymers such as polyvinyl methyl ether, polyhydroxypropyl alcohol, and hydroxy. Propylmethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, methylcellulose,
Alcohol polymers such as poly-vinyl alcohol and derivatives thereof, poly-N-substituted acrylamide, poly-cyclopropylacrylamide, poly-N-acryloylpyrrolidone, poly-N-acryloylpiperidine, poly-acryloyl-L-aminoacid ester, poly And amide-substituted polymers such as -ethyloxazoline.

At a low temperature, it is dissolved in water, becomes transparent,
A high-temperature hydrophobic group-type thermoreversible polymer compound obtained by polymerizing a monomer that insolubilizes and becomes cloudy when the temperature rises, for example, a thermoresponsive hydrogel that swells below the transition temperature and discontinuously shrinks in volume above the transition temperature Can also be used.
The transition temperature, gel strength, water absorption, water absorption rate, thermal stability, acid / base of these polymer gels depend on the type of substituent, copolymer composition, organic salt, inorganic salt, and addition of surfactant. It is preferable because the stability, ionicity, transition temperature and the like can be controlled.

Examples of the method for producing the polymer gel include a radical polymerization method and a redox polymerization method. Although the phase transition temperature of such a material depends on the structure of the material, it is generally zero.
~ 80 ° C. The transition temperature can be adjusted by a known method, and specifically, a method of designing a chemical structure such as a substituent or the like, adding an organic salt, an inorganic salt, or a surfactant is known.

In order to obtain a desired color, a coloring material such as a dye or a pigment may be added to the polymer gel or the porous particles.

The coloring material used is not particularly limited, and examples thereof include carbon black, nigrosine dye, aniline blue, calcoil blue, chrome yellow, ultramarine blue, Dupont oil red, and quinoline yellow.
Methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal, C.I. I. Pigment Red 48: 1, C.I.
I. Pigment Red 122, C.I. I. Pigment
Red 57: 1, C.I. I. Pigment Yellow 97,
C. I. Pigment Yellow 12, C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 1
5: 3, magnetite, ferrite and the like.

In order to fix the polymer gel in the pores on the surface of the porous particles, first, porous particles are prepared, and the obtained porous particles are impregnated with the monomer of the thermoresponsive gel and a crosslinking material. After the particles are taken out and washed, a method of performing polymerization by adding an accelerator and a polymerization initiator, or a method of simultaneously performing polymerization of a thermosensitive gel when preparing porous particles can be used. The slurry obtained by these methods is
Decant or treat with stabilizer. Further, in order to remove unreacted substances such as residues of an antioxidant which cause deterioration of the display layer, it is preferable to dialyze porous particles having a polymer gel fixed to pores on the surface.

As a method of manufacturing the display layer, porous particles having a polymer gel fixed in the pores on the surface are dispersed in a binder resin, and these are dissolved in a solvent, and the resulting solution is coated on the heat generating layer. Then, a method of evaporating a solvent, or a method of dispersing porous particles in which a polymer gel is fixed in an ultraviolet curable resin, applying the dispersion on a heating layer, and irradiating ultraviolet rays to cure the resin. Can be used.

Examples of usable solvents include, for example, ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl Examples include acetate, dimethoxyethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethylsulfoxide, sulfolane, γ-butyrolactone, toluene and the like.

The thickness of the display layer is preferably from 30 to 200 μm, more preferably from 50 to 100 μm. The porous particles are preferably monodispersed.

On the display layer, a filter for preventing scratches and stains and a filter for preventing reflection can be provided. In addition, an arbitrary color may be displayed by forming a light-transmitting color filter of an arbitrary color on the display layer by setting the porous particles to white and the polymer gel to black, or vice versa.

FIG. 3 shows an image display device 10 according to the present invention. A heat generating layer 14 is provided on the substrate 12, a display layer 16 is provided thereon, and a filter layer 18 is provided as necessary.
Is provided. The display layer 16 includes a binder resin 20,
Porous particles 22 dispersed in binder resin (FIG. 1)
And a polymer gel 24 (FIG. 1) fixed to pores on the surface of the porous particles 22. For example, the polymer gel 24 contracts due to heating (FIG. 2), and an image is displayed by contrast between a region where the polymer gel 24 contracts and a region where the polymer gel 24 swells (FIG. 3). .

[0033]

Example 1 An aqueous solution of dextran (molecular weight 70000) was added to a chloroform solution (8% by weight) of polylactic acid (molecular weight 60000) containing sorbitan monolaurate (0.5% by weight) as a surfactant. 3% by weight), and a W / O emulsion was prepared by Vortex Mixing. Next, this dispersion was poured into a large amount of an aqueous PVA solution (1% by weight) to prepare a W / O / W emulsion, and chloroform was evaporated to obtain white porous particles.

Next, N-isopropylacrylamide (0.0125 mol / l) containing N, N'-methylenebisacrylamide (1 mol / l) as a cross-linking agent was prepared in a pregel solution dissolved in ion-exchanged water. The porous particles were impregnated for 24 hours. Next, the porous particles were washed with ion-exchanged water to wash off the pregel solution attached to the surface of the porous particles. Next, N, N, N ′, N′-tetramethylethylenediamine (0.0116 mol / l) was added to the dispersion liquid in which the porous particles were dispersed, as an accelerator.
Ammonium persulfate (0.0025m
ol / l) and the polymerization was carried out while maintaining the reaction temperature at 35 ° C. while stirring with a stirrer for 24 hours. The color of the polymerized polymer gel was black.

The obtained reaction solution was dialyzed against water for 2 days to remove unreacted substances. Further, using a centrifugal separator manufactured by Shimadzu Corporation, centrifugal separation was performed for 30 minutes at a centrifugal force of 1.4 × 10 ³ g to remove large aggregates, thereby obtaining thermosensitive particles having an average particle size of about 30 μm. The phase transition temperature of the obtained particles is
When using a differential scanning calorimeter manufactured by Shimadzu Corporation, it was 3
4.4 ° C.

Nichrome was vapor-deposited on the glass substrate by a vapor deposition method to form a heating layer having a thickness of 4 μm.

Next, the heat-responsive particles were dispersed in a urethane-based UV-curable resin at 40% by weight, applied to the heat-generating layer in a thickness of 40 μm by spin coating, and irradiated with UV light manufactured by Ushio Electric Co., Ltd. The device was irradiated with ultraviolet light having an intensity of 10 mWcm ^-2 for about 60 seconds to cure the resin and form a display layer.

When a voltage of about 2.5 V is applied to the heating layer of the image display device manufactured as described above to generate heat, and when the thermosensitive particles on the heating layer reach the transition temperature, a desired image is formed on the substrate. Was displayed. (Example 2) An image display device was manufactured by forming three color filter layers of C, M, and Y on the display layer of the image display device manufactured in Example 1.

A voltage of about 2.5 V was applied to the heat generating layer of this image display device to generate heat. When the thermosensitive particles on the heat generating layer reached the transition temperature, a desired color image was displayed on the substrate. Comparative Example 1 On a substrate on which an ITO electrode was formed, acrylamide, acrylic acid, vinyl alcohol, and ammonium persulfate as an initiator in a molar ratio of 659: 40: 1: 2.
A pre-gel solution obtained by passing dry nitrogen through the liquid mixed for 20 minutes to sufficiently dissolve dissolved oxygen is applied by a spin coating method to a thickness of about 1 μm, and the coating film is heated at 50 ° C. for 4 hours.
Polymerization was performed to form an acrylic acid-acrylamide copolymer gel. Furthermore, 40 μm of non-conductive particles are sandwiched between the ITO substrate on which the gel is formed and the ITO substrate on which the gel is not formed as a spacer, and the periphery thereof is sealed with an epoxy-based adhesive. A liquid in which water and acetone were mixed at a volume ratio of 1: 1 was sealed in the gap between the gel and the gel to produce an image display device. Comparative Example 2 N-acryloxysuccinimide, N-isopropylacrylamide, ammonium persulfate as an initiator, and sorbitan monolaurate as a surfactant in a molar ratio of 1: 1: 0.005: 0.01 in ion-exchanged water. , And a pregel solution was prepared, and dry nitrogen was passed through for 20 minutes to sufficiently dissolve dissolved oxygen. This pregel solution is heated to 50 ° C. while gently stirring under a nitrogen atmosphere.
For 4 hours, exposed to ion-exchanged water, and allowed to sufficiently diffuse unreacted substances for one day to obtain gel fine particles. Further, 40 μm of non-conductive particles are interposed between the ITO substrate and the ITO substrate as a spacer, and the periphery is sealed with an epoxy-based adhesive. The contained ethanol was sealed therein to produce an image display device.

For the display devices manufactured in Examples and Comparative Examples, display and non-display were switched at an interval of 5 seconds and about 120,000 times for about one week, and (1) the display layer (gel) was deterioration,
Three points of (2) precipitation, deposition and aggregation of gel particles, and (3) deterioration of the electrode were evaluated. Table 1 shows the results.

[0041]

[Table 1]

In the deterioration of the display layer in Table 1, X indicates that the reproducibility of the swelling and shrinking of the gel was deteriorated, and that the display layer had a remarkable change before and after the test such as cloudiness, deformation, or pattern formation on the surface.・ Indicates that switching of non-display was hindered, Δ indicates that the gel was changed before and after the test, but had little effect on the display performance, and ○ indicates no change in the gel before and after the test Indicates that In addition, those which could not cause gel degradation in principle were designated as-.

In the precipitation, sedimentation and aggregation of gel particles, ○ indicates that no aggregation, sedimentation and deposition of gel particles were observed, and Δ indicates that aggregation, sedimentation and deposition of gel particles were slightly observed. The symbol x indicates that aggregation, sedimentation, and deposition of the gel particles occurred over the entire surface. In principle, a sample in which precipitation of gel particles and the like cannot occur was designated as-.

In the electrode deterioration, ○ indicates that no deterioration was observed on the electrode, Δ indicates that the electrode surface was discolored, but hardly any deterioration was observed, and x indicates not only the electrode surface but also the inside. It indicated that corrosion was in progress.

As can be seen from Table 1, in both Examples 1 and 2, no deterioration of the gel and no deterioration of the electrode were observed, and good results were obtained. In Comparative Example 1, a fine pattern was slightly observed on the gel surface even during swelling, and the electrode was significantly deteriorated by the oxidizing agent as the polymerization initiator. In Comparative Example 2, although no electrode deterioration was observed, gel particles precipitated at the bottom of the cell.

[0046]

According to the image display device of the present invention, the polymer gel is fixed on the surface of the porous particles dispersed in the binder resin, so that the polymer gel is higher than when the polymer gel is dispersed in the liquid. The molecular gel is stably present in the display layer, has good contrast, and does not depend on the viewing angle, and can display a bright image.

[Brief description of the drawings]

FIG. 1 is a view showing a configuration of a porous particle having a polymer gel fixed in a hole on a surface used in an image display device of the present invention.

FIG. 2 is an explanatory diagram showing the operation principle of a polymer gel fixed to pores on the surface of porous particles used in the image display device of the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration of the image display device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image display apparatus 12 Substrate 14 Heat generation layer 16 Display layer 18 Filter layer 20 Binder resin 22 Porous particle 24 Polymer gel

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C060 AA01 BA03 BA09 BB01 BB13 BB18 BB19 BD02 BE00 HA02 HA10 HB07 5C094 AA06 AA12 AA31 AA47 AA54 BA11 BA51 BA99 CA19 CA23 DA11 EA10 ED02 ED13 FA01 FA02 FA04 FB01 FB01FB01

Claims (4)

[Claims] 1. A heat generating layer on a substrate, and a display layer provided on the heat generating layer, wherein the display layer comprises a binder resin,
An image containing a porous particle dispersed in a binder resin, and a polymer gel fixed to pores on the surface of the porous particle and having a color different from the color of the porous particle and having a volume that reversibly changes with temperature. Display device. 2. The image display device according to claim 1, wherein the binder resin is an ultraviolet curable resin. 3. The image display device according to claim 1, wherein a diameter of the porous particles is smaller than a heating range of one pixel of the heating layer. 4. The image display device according to claim 1, further comprising a filter layer on the display layer.