JP2008250541A - Infrared-reflective-pattern-printed transparent sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an infrared-reflective-pattern-printed transparent sheet that implements a wide reading angle and thus increased reading performance. <P>SOLUTION: The transparent sheet 1 is printed with an infrared-reflective transparent pattern on a surface of a transparent substrate. The transparent ink that forms the transparent pattern includes an infrared-reflective material. The transparent pattern enables an input terminal capable of radiating and detecting infrared rays to read infrared reflection patterns and provide position information about the input terminal on the transparent sheet. The infrared-reflective material is made flakes by cutting or grinding of a liquid crystal film including a liquid crystal material having a fixed cholesteric structure having wavelength-selective reflectivity to the infrared region of wavelengths. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an infrared reflection pattern printed transparent sheet.

  A liquid crystal having a cholesteric structure has a regular periodic spiral structure (cholesteric structure) in which the liquid crystal molecules are multilayered in the direction normal to the surface of the transparent substrate. It has a wavelength selective reflectivity that reflects circularly polarized light having a wavelength corresponding to the direction of the helix and corresponding to the helix pitch. Liquid crystals having a cholesteric structure have such wavelength selective reflectivity, are easy to handle, and are excellent in processability, and thus are widely applicable industrially.

  Patent Document 1 discloses a method for producing a film using a liquid crystal having a cholesteric structure as one using such characteristics of a liquid crystal having a cholesteric structure. In such a film, the cholesteric structure is uniformly oriented in the normal direction with respect to the surface of the substrate, and the brightness of reflected light due to specular reflection with respect to incident light from a certain direction is very large and excellent. However, there is a problem that the brightness rapidly decreases outside the specular reflection region.

In recent years, there has been an increasing need to convert handwritten characters, pictures, symbols, and the like into electronic data that can be handled by an information processing device. In particular, handwritten information can be converted in real time without using a reading device such as a scanner. Therefore, there is an increasing demand for a method for inputting to a computer or the like.
For example, there has been a demand for an input device that can input handwritten contents directly on the display surface of a display device into an information processing device and can be manufactured in a compact and inexpensive manner.

As a transparent sheet that satisfies such a requirement, for example, Patent Document 2 discloses a transparent sheet that is attached to the front or front of a display device, and indicates position information for indicating the position of an input locus by an input electronic pen or the like. Is printed using ink that emits light that can be read by the input locus reading means when irradiated with light of a predetermined wavelength. However, Patent Document 2 does not describe the type of ink that embodies such a transparent sheet, merely describes the idea or desire of the transparent sheet, and is a specific example of a transparent sheet. There is no.
Further, Patent Document 3 discloses a coordinate input device using a transparent member on which special ink that reflects an infrared region is printed. However, Patent Document 3 also discloses a type of ink that realizes such a device. Etc. are not described, only ideas or desires are described, and there is no specific example of the transparent sheet.

When such a transparent sheet is practically used, as can be seen from FIG. 5 of Patent Document 2, the reading electronic pen is brought into contact with the dot pattern for reading. It is preferable that it can cope with the environment. However, in the present situation where a transparent sheet that can be practically used is not yet realized as described above, there are various methods for realizing a method of inputting handwritten information to a computer or the like in real time without going through a reading device such as a scanner. Therefore, it is desired to develop a transparent sheet having a wide reading angle and excellent reading performance that can cope with various use environments.
JP-A-6-186534 Japanese Patent Laid-Open No. 2003-256137 JP-A-2001-243006

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an infrared reflection pattern printed transparent sheet having a wide reading angle and excellent reading performance.

As a result of intensive research to achieve the above object, the present inventors cut or pulverized a liquid crystal film having a cholesteric structure having a cholesteric structure fixed as an infrared reflecting material on a transparent substrate to obtain flakes. The present invention has been completed by finding that the above object can be achieved by forming a transparent pattern using a transparent ink containing the above.
That is, the present invention
(1) A transparent sheet in which an infrared reflective transparent pattern is printed on the surface of a transparent substrate, wherein the transparent ink constituting the transparent pattern contains an infrared reflective material, and the transparent pattern is irradiated with infrared rays and detected. The input terminal can read the infrared reflection pattern and provide position information of the input terminal on the transparent sheet, and the infrared reflection material has wavelength selective reflectivity with respect to the wavelength in the infrared region. Infrared reflective pattern printed transparent sheet, which is a flake obtained by cutting or pulverizing a liquid crystal film containing a liquid crystal having a fixed cholesteric structure,
(2) The infrared reflective pattern-printed transparent sheet according to (1) or (2), wherein the transparent pattern is a dot pattern,
(3) The infrared reflective pattern printed transparent sheet according to (1) or (2), wherein a primer layer is provided between the transparent substrate and the transparent pattern.
(4) The infrared reflection pattern printed transparent sheet according to any one of (1) to (3), wherein the transparent pattern has a selective reflection peak wavelength at 800 nm to 950 nm,
(5) The infrared reflection pattern printed transparent sheet according to any one of (1) to (4), which is mounted to face the front surface of a display device capable of displaying an image, and (6) the detachable one (1) to the infrared reflection pattern printed transparent sheet according to any one of (5),
Is to provide.

  ADVANTAGE OF THE INVENTION According to this invention, the infrared reflective pattern printing transparent sheet excellent in the reading performance which has a wide reading angle can be provided. The infrared reflective pattern-printed transparent sheet of the present invention can be suitably used particularly for a data input system in which handwriting is directly performed on the screen of a display device, and the work space can be reduced.

  As shown in FIGS. 1 and 2, the infrared reflective pattern-printed transparent sheet 1 (hereinafter, also referred to as a transparent sheet) of the present invention has a primer layer 4 laminated on the surface of a transparent substrate 2 as necessary. It is a sheet in which a transparent pattern 3 having infrared reflectivity is printed on the surface of the layer 4. The transparent ink constituting the transparent pattern 3 includes flakes 5 obtained by cutting or pulverizing a liquid crystal film 11 containing a liquid crystal having a fixed cholesteric structure having wavelength selective reflectivity with respect to wavelengths in the infrared region. Is included. Moreover, the preferable one aspect | mode of the liquid crystal film 11 is a sheet | seat by which the liquid crystal layer 13 is laminated | stacked on the surface of the transparent base material 12, as FIG. 3 shows.

[Liquid crystal having a cholesteric structure]
In the infrared reflection pattern printed transparent sheet of the present invention, a liquid crystal having a cholesteric structure is used as an infrared reflecting material. A liquid crystal having a cholesteric (chiral nematic) structure has a helical structure with a constant period in which the liquid crystal molecules are in a multilayer structure in the direction normal to the surface of the transparent substrate (the incident angle θ of light below is 0 °). It has a (cholesteric structure) and expresses characteristic optical properties resulting therefrom. The feature of the cholesteric structure is that it has wavelength selective reflectivity that reflects circularly polarized light having a wavelength corresponding to the direction of the helix and corresponding to the helix pitch. The selective reflection wavelength λ (peak wavelength λ nm) is generally given by the following equation.
λ = p · n · cos θ
p: helical pitch of cholesteric liquid crystal (nm)
n: average refractive index in the plane perpendicular to the helical axis of the liquid crystal
θ: Incident angle of light (angle from surface normal)
The bandwidth Δλ (nm) of the selective reflection wavelength λ (peak wavelength λ) is generally given by the following equation.
λ = p · Δn · cos θ
p: helical pitch of cholesteric liquid crystal (nm)
Δn: Birefringence index in the plane perpendicular to the helical axis of the liquid crystal
θ: Incident angle of light (angle from surface normal)
A liquid crystal having a cholesteric structure has such selective reflection performance, is easy to handle, and is excellent in workability, so that it can be widely applied industrially. However, from the above formula regarding the selective reflection wavelength λ, the liquid crystal having a cholesteric structure decreases the wavelength of the reflected light as the incident angle increases, so that the reflection wavelength deviates from a predetermined wavelength, that is, the reading angle is limited. I understand that

One pitch of the cholesteric structure is the length of an axis in which elongated liquid crystal molecules rotate in a spiral by rotating 360 °. However, when the cross section is actually observed, a repeated layer structure can be seen every 180 ° (see FIG. 5). reference). Therefore, the apparent interlayer pitch when the cross section is observed is ½ of the helical pitch of the liquid crystal. For example, if the apparent interlayer pitch when the cross section is observed is 250 nm, the pitch of the liquid crystal is 500 nm. Become.
When circularly polarized light is incident, the rotation direction of the circularly polarized component of the light reflected on the surface of the transparent substrate made of a material generally used as a substrate such as resin or glass is reversed. On the other hand, on the surface of the cholesteric liquid crystal, the rotation direction of the circularly polarized component of the light reflected on the surface remains unchanged. Therefore, if this property is used, it is possible to improve the SN ratio of the reflected light from the infrared reflective transparent pattern and the background light (reflected light other than from the pattern portion) by combining with a circular polarizing filter or the like. is there.

As described above, in a normal cholesteric liquid crystal coating film, the helical axis of the cholesteric structure is substantially uniformly oriented in the normal direction of the substrate (see FIG. 5). In other words, the Bragg reflecting surface formed by the cholesteric structure forms a parallel plane group. In that case, since there is only one specific reflection angle with respect to a specific incident angle, the amount of light returning to the input terminal increases or decreases according to the inclination of the input terminal (input pen) at the time of writing. (Acceptable input terminal tilt angle) becomes narrower.
On the other hand, in the transparent sheet of the present invention, the transparent pattern is formed of a transparent ink containing flakes 5 obtained by cutting or pulverizing a liquid crystal sheet containing a liquid crystal material having a cholesteric structure fixed as an infrared reflecting material. Since the flakes 5 are irregularly present in the transparent pattern, it has a characteristic of generating reflected light beams having a plurality of reflection angles with respect to an incident light beam having a specific incident angle. ) Even if it is tilted within a certain range, it is possible to detect a transparent pattern if any light ray enters the input terminal. Because of this characteristic, the transparent sheet of the present invention has less variation in the amount of light returning to the input terminal, and the amount of light can be kept above a certain amount within a certain angle range, and the reading is as wide as 0 to 40 °. Can have an angle (acceptable input terminal tilt angle).

[Transparent ink]
The infrared reflective transparent pattern used in the present invention (hereinafter sometimes simply referred to as a transparent pattern) includes a flake 5 obtained by cutting or pulverizing a liquid crystal sheet 11 containing a liquid crystal having a fixed cholesteric structure. It is formed with transparent ink.
Hereinafter, the transparent ink will be described from the liquid crystal sheet 11.

[Transparent ink: Liquid crystal sheet 11]
The liquid crystal sheet 11 used in the present invention is cut to give infrared reflection performance to the transparent pattern of the present invention as flakes 5. The liquid crystal sheet 11 may be composed of a liquid crystal layer 13 containing liquid crystal, or may be composed of a liquid crystal layer 13 containing liquid crystal and a transparent substrate 12 such as polyethylene terephthalate.

[Liquid Crystal Sheet 11: Liquid Crystal Layer 13]
The liquid crystal layer 13 constituting the liquid crystal sheet 11 includes a liquid crystal exhibiting a cholesteric structure having wavelength selective reflectivity with respect to the wavelength in the infrared region, and a part on the transparent substrate 12 described later as shown in FIG. However, it is preferable to exist over the entire surface from the viewpoint of obtaining sufficient selective reflection performance and a wide reading angle. In the present invention, the wavelength in the infrared region is not particularly limited. However, light in the near-infrared region of 800 to 2500 nm is usually preferably used, and the explanation will be focused on infrared rays in the wavelength region.
In general, the term “liquid crystal” refers to a liquid state in a narrow sense, but in the specification of the present invention, the liquid crystal having fluidity is cross-linked, cooled by means such as cooling, and the like. A liquid crystal that has been solidified and maintained in a non-flowing state while maintaining desired performance such as refractive index and anisotropy is also referred to as “liquid crystal”.

Since the liquid crystal sheet 11 used in the present invention is cut or pulverized to obtain the flakes 5, before the liquid crystal sheet 11 is cut or pulverized, the liquid crystal is fixed so as not to exhibit fluidity. There is a need. Therefore, the liquid crystal used for the liquid crystal layer 13 is preferably a polymerizable chiral nematic liquid crystal (polymerizable monomer or polymerizable oligomer) obtained by mixing a polymerizable chiral agent with a polymerizable nematic liquid crystal, or a polymer cholesteric liquid crystal. be able to.
In the present invention, among the polymerizable liquid crystals, it is preferable to use a crosslinkable polymerizable monomer or polymerizable oligomer, and it is more preferable that the polymerizable functional group has an acrylate structure.

  In addition, as the liquid crystal exhibiting the cholesteric structure, a liquid crystal having a high reflectance (usually about 5 to 50%) at least in a part of the wavelength in the infrared region is not necessarily high in the wavelength in the visible light region. Does not require transparency. Even if the liquid crystal that expresses the cholesteric structure is completely opaque, if the area of the non-formation part (margin part) of the liquid crystal is appropriately increased and the transmitted light from the area is used, the transparent pattern It is because it is possible to obtain desired transparency as a whole. However, it is needless to say that the liquid crystal itself has a higher visible light transmittance. In general, a liquid crystal exhibiting such a cholesteric structure has a visible light transmittance of about 70% or more in a visible light region with a thickness of about several μm when a high reflection wavelength region is brought into the infrared region. obtain. On the other hand, in the infrared region, it is common to obtain a high reflectance of about 5 to 50%. The temperature range in which the polymerizable liquid crystal exhibits a cholesteric structure is not particularly limited as long as it can be fixed by crosslinking in a state having a cholesteric structure, but the temperature at which the cholesteric structure is expressed is in the range of 30 to 140 ° C. The material is preferably used because it can simultaneously perform the drying process during pattern printing and the phase transition of the liquid crystal.

With such a material, since the liquid crystal molecules can be optically fixed while having a cholesteric structure, the liquid crystal sheet 11 including the liquid crystal molecules can be stably cut or pulverized to form the flakes 5. And a stable pattern can be formed.
Alternatively, a liquid crystal polymer (polymer cholesteric liquid crystal) that has a high glass transition point and can be solidified into a glass state at room temperature by cooling after heating can be used. Similarly, these materials are also optically fixed while the liquid crystal molecules remain in a liquid crystal state having a cholesteric structure, so that a pattern that is easy to handle as an optical sheet and stable at room temperature can be formed. Because.

  The crosslinkable polymerizable monomer is disclosed in JP-A-7-258638, JP-A-11-513019, JP-A-9-506088 and JP-A-10-5088822. In addition, a mixture of a liquid crystalline monomer and a chiral compound can be used. For example, a chiral nematic liquid crystal (cholesteric liquid crystal) can be obtained by adding a chiral agent to nematic liquid crystal molecules (liquid crystal monomer) expressing a nematic structure. A method for forming a cholesteric liquid crystal is also described in JP-A Nos. 2001-5684 and 2001-110045.

  Examples of nematic liquid crystal molecules (liquid crystalline monomers) that can be used in the present invention include compounds represented by the following formulas (1) to (11). The compounds exemplified here have an acrylate structure and can be polymerized by ultraviolet irradiation or the like.

［化合物（１１）において、Ｘ¹は２〜５(整数）である。］

[In the compound (11), X ¹ is 2 to 5 (integer). ]

As the crosslinkable polymerizable oligomer, a cyclic organopolysiloxane compound having a cholesteric structure as disclosed in JP-A-57-165480 can be used.
Further, the liquid crystal polymer includes a polymer in which a mesogenic group exhibiting liquid crystal is introduced into the main chain, a side chain, or both positions of the main chain and the side chain, a polymer cholesteric liquid crystal in which a cholesteryl group is introduced into the side chain, A liquid crystalline polymer as disclosed in Kaihei 9-133810, a liquid crystalline polymer as disclosed in JP-A-11-293252, or the like can be used.

  A chiral agent preferably used for a liquid crystal exhibiting a cholesteric structure applicable to the liquid crystal layer 13 is a material having an asymmetric carbon atom and forming a chiral nematic structure by mixing with a nematic liquid crystal molecule. The material having an acrylate structure as exemplified in Formula (12) is preferable because it can be polymerized by ultraviolet irradiation.

［Ｘは２〜５（整数）である。］

[X is 2 to 5 (integer). ]

  The infrared reflection performance of the transparent sheet of the present invention utilizes the wavelength selective reflectivity (the same principle as Bragg reflection in X-ray diffraction) of a liquid crystal having a cholesteric structure. The selective reflection peak wavelength (wavelength satisfying the Bragg reflection condition) is determined by the pitch length of the cholesteric structure contained in the pattern. When nematic liquid crystal molecules and a chiral agent are used, the addition amount of the chiral agent is adjusted. By doing so, the pitch length can be controlled. The amount of chiral agent added to obtain the target selective reflection peak wavelength in the infrared region varies depending on the type of liquid crystal material used and the type of chiral agent. For example, the liquid crystal molecules of formula (11) and the chiral of formula (12) When the agent is used, a cholesteric structure having a reflection peak in the infrared region is formed by adding about 3 parts by mass of the chiral agent to 100 parts by mass of the liquid crystal molecules. When polymer cholesteric liquid crystal is used as the liquid crystal, a polymer material having a target pitch length may be selected.

A polymer of a nematic liquid crystal molecule and a chiral agent can be obtained, for example, by adding a known photopolymerization initiator or the like to a polymerizable nematic liquid crystal and a polymerizable chiral agent and irradiating with ultraviolet rays for radical polymerization.
In addition, when the liquid crystal layer 13 is printed, a liquid crystal such as a polymerizable monomer or a polymerizable oligomer and a chiral agent are preferably used as a coating liquid obtained by dissolving in a solvent from the viewpoint of coating properties.
The solvent is not particularly limited as long as it has sufficient solubility in the material, and a known one may be used. For example, anone (cyclohexanone), cyclopentanone, toluene, acetone, MEK (methyl ethyl ketone), MIBK (methyl) Common solvents such as isobutyl ketone), DMF (N, N-dimethylformamide), DMA (N, N-dimethylacetamide), methyl acetate, ethyl acetate, n-butyl acetate, 3-methoxybutyl acetate, A mixed solvent is mentioned.

Further, the liquid crystal used for the liquid crystal layer 13 can be blended with a leveling agent, fine particles and the like for the purpose of obtaining a wide reading angle and coating property. The leveling agent and fine particles can be used without particular limitation as long as they do not disturb the alignment of the liquid crystal more than necessary (more than giving a desired angle (distribution) to the helical axis of the liquid crystal material).
As the leveling agent, those usually used can be used without particular limitation, and examples thereof include various surfactants such as fluorine-based, silicone-based, and acrylic acid copolymer-based ones, depending on the desired reading angle. Can be added as appropriate.
As the fine particles, those usually used can be added in an appropriate amount without any particular limitation. For example, inorganic particles include spherical particles such as α-alumina, silica, kaolinite, iron oxide, diamond, and silicon carbide. Examples of the particle shape include a sphere, an ellipsoid, a polyhedron, a scale shape, and the like. Although there is no particular limitation, a spherical shape is preferable. Organic materials include synthetic resin beads such as cross-linked acrylic resin and polycarbonate resin. Among these, α-alumina and silica are preferable and spherical ones are particularly preferable because they are high in hardness and have a large effect on improving wear resistance, and are easy to obtain spherical particles. The particle diameter of the fine particles may be appropriately selected according to the thickness of the liquid crystal layer 13, and is usually about 0.01 to 15 μm, preferably 0.1 to 5 μm.
The addition amount of the leveling agent and fine particles is usually about 0.01 to 10 parts by mass with respect to 100 parts by mass of the liquid crystal material.

A method for forming the liquid crystal layer 13 is not particularly limited, and a known method can be used. A coating liquid containing liquid crystal, a chiral agent, and the like is applied on the transparent substrate 12, for example, a flexographic printing method or a gravure printing method. It can be formed by printing by a printing method such as stencil printing or ink jet printing.
The thickness of the liquid crystal layer 13 is usually about 1 to 20 μm, preferably 3 to 15 μm.

[Liquid crystal sheet 11: transparent substrate 12]
Although it will not specifically limit as the transparent base material 12 used for the liquid crystal sheet 11 if it is a material which permeate | transmits visible light, The thing formed with the material with few optical malfunctions is preferable. What is called a film, a sheet | seat, or the form of a board is used suitably. In addition to a flat surface, a curved surface may be used so as to match the curved surface of the display surface. As the material for the transparent substrate, for example, glass, TAC (triacetyl cellulose), PET (polyethylene terephthalate), polycarbonate, polyvinyl chloride, acrylic, polyolefin, and the like are preferably used.
The thickness of the transparent substrate 12 is appropriately selected from the range of 20 to 100 μm, preferably 30 to 80 μm, according to the material, required performance, and usage pattern. Moreover, if the thickness of the transparent base material 12 exists in the said range, the transparent base material 12 will not fracture | rupture by the tension | tensile_strength applied when applying the coating liquid containing a liquid crystal, a chiral agent, etc.

  When using a material that easily dissolves or swells in a solvent, such as a polymer film such as a TAC film, as the transparent substrate 12, so that the substrate is not attacked by the solvent in the coating liquid used at the time of transparent pattern printing, A barrier layer may be provided on the substrate. For example, a water-soluble substance such as PVA (polyvinyl alcohol) or HEC (hydroxyethyl cellulose) may be used as the barrier layer.

  The liquid crystal sheet 11 used in the present invention may be composed of the liquid crystal layer 13 as described above, or may be composed of the liquid crystal layer 13 and the transparent substrate 12. When the liquid crystal sheet 11 is composed of the liquid crystal layer 13, the liquid crystal sheet 11 can be obtained by, for example, forming the liquid crystal layer 13 on the transparent substrate 12 and then peeling the liquid crystal layer 13 from the transparent substrate 12. it can.

[Transparent ink: Flakes 5]
The flakes 5 contained in the transparent ink of the present invention are obtained by cutting or pulverizing the liquid crystal sheet 11 containing the liquid crystal material having the fixed cholesteric structure described above. The shape of the flake 5 is not particularly limited, and the size of the flake 5 is preferably 0.1 to 10 μm and more preferably 1 to 7 μm in terms of the diameter of its circumscribed circle from the viewpoint of obtaining a wider reading angle. Further, the cutting or pulverizing method is not particularly limited as long as it can be cut or pulverized so as to have the above-mentioned size, for example, a method using a media mill such as a ball mill, a bead mill, a sand grinder, a blade, a laser, a mortar or the like. It is done. Further, the flakes 5 may be obtained by cutting or pulverizing to the above-mentioned preferable size in one stage. For example, the diameter of the circumscribed circle of the flakes is about 100 μm in the first stage and about 5 μm in the second stage. It may be obtained by cutting or pulverizing to the above preferred size in a plurality of stages.
The content of the flake 5 in the transparent ink is preferably 5 to 95% by mass, and more preferably 10 to 80% by mass. Within this range, the flakes 5 can maintain a good dispersion state in the transparent ink, and a wide reading angle can be obtained.

[Transparent ink: Binder resin]
The transparent ink used in the present invention preferably contains a binder resin.
Examples of the binder resin include curable resins such as acrylic resins, diene resins, polyester resins, and silicone resins, and ionizing radiation curable resins. Among these, ionizing radiation curable resins are preferable.

Examples of the ionizing radiation curable resin include those having a (meth) acrylate functional group that is cured by ionizing radiation such as ultraviolet rays and electron beams, such as relatively low molecular weight polyester resins, polyether resins, acrylic resins, and epoxy resins. , Urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, oligomers or prepolymers such as (meth) allylates of polyfunctional compounds such as polyhydric alcohols, monomers, and specific examples thereof include Monofunctional monomers such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N-vinylpyrrolidone and polyfunctional monomers such as polymethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate Tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol Examples include di (meth) acrylate. Here, (meth) acrylate is a notation meaning acrylate or methacrylate.
In addition, a resin having a cationic polymerizable functional group such as an epoxy resin can be used.

  Moreover, when using an ultraviolet curable resin as said ionizing radiation curable resin, it is preferable to use a photoinitiator together. As specific examples of the photopolymerization initiator, for radical polymerizable resins such as (meth) acrylate, acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, tetramethylchuram monosulfide, Examples of thioxanthones and the like, and cationically polymerizable resins such as epoxy resins include aromatic iodonium salts, aromatic sulfonium salts, aromatic diazonium salts, metallocenes, and the like. Moreover, it is preferable to mix and use a photosensitizer, and specific examples thereof include n-butylamine, triethylamine, tri-n-butylphosphine and the like.

[Transparent ink: solvent]
The transparent ink used in the present invention preferably contains a solvent from the viewpoint of coatability.
The solvent is not particularly limited as long as it has sufficient solubility in the material, and a known one may be used. For example, anone (cyclohexanone), cyclopentanone, toluene, acetone, MEK (methyl ethyl ketone), MIBK (methyl isobutyl) Ketones), DMF (N, N-dimethylformamide), DMA (N, N-dimethylacetamide), methyl acetate, ethyl acetate, n-butyl acetate, 3-methoxybutyl acetate, and other common solvents and mixtures thereof Mention may be made of solvents.
The content of the solvent in the transparent ink is usually 20 to 80% by mass, and preferably 30 to 70% by mass from the viewpoint of coatability.

[Transparent substrate 2]
Although it will not specifically limit as the transparent substrate 2 in the transparent sheet of this invention if it is a material which permeate | transmits visible light, The thing formed with the material with few optical malfunctions is preferable. Specifically, the same ones as those used for the transparent substrate 12 of the liquid crystal film 11 described above can be preferably used. Further, the thickness is appropriately selected from the range of 20 to 5000 μm, preferably from the range of 100 to 5000 μm from the viewpoint of curling properties, according to the material, required performance, and usage pattern.

  Further, for the purpose of obtaining a wide reading angle, an uneven layer can be preferably provided on the surface of the transparent substrate 2 (the side on which the transparent pattern is printed). The method for forming the uneven layer is not particularly limited as long as unevenness can be formed on the surface of the transparent substrate, but a dry process and a wet process can be preferably used.

  As a dry process, there are a method of forming fine irregularities on the surface by hot pressing using an embossed plate, a method of forming minute irregularities on the surface by a sandblasting method, and the like. As a wet process, for example, silica particles having an average particle diameter of 30 μm or less, preferably about 2 to 15 μm, in a curable resin such as an acrylic resin, a diene resin, a polyester resin, and a silicone resin are used in a resin of 100 mass. The coating composition is dried by gravure coating, reverse roll coating, die coating, etc., so that the thickness after drying is about 5 to 30 μm. If necessary, there is a method of curing by irradiation with ionizing radiation such as heat or ultraviolet rays or electron beams.

  In addition, as a wet process, an ionizing radiation curable resin and, if desired, a coating liquid containing a photopolymerization initiator is applied to an uneven plate cylinder, and the coating film and the PET base film are in contact with each other. After curing by irradiating with ionizing radiation, the plate cylinder is peeled off, and the coating liquid is applied to a molding film having unevenness or a method of transferring unevenness to the PET base film surface. It is also possible to use a method of irradiating and curing ionizing radiation in a state where the PET-based substrate film is brought into contact, and then peeling the shaped film and transferring irregularities to the surface of the PET-based substrate film. As the ionizing radiation curable resin, those similar to those used as the binder resin of the transparent ink described above can be preferably used.

[Primer layer 4]
In the transparent sheet of the present invention, providing the primer layer 4 on the surface of the transparent substrate 2 and further providing the surface of the primer layer with a micro uneven shape or adding a liquid repellent material provides a wide reading angle. More preferable from the viewpoint. The material constituting the primer layer 4 is preferably a transparent resin using an organic resin, an inorganic resin, or the like, particularly in that a layer can be formed by coating. As the resin used for the primer layer, the difference in refractive index from the dot pattern is sufficiently small, and the reflectance and absorption rate of infrared rays used for reading are sufficiently low compared to the dot pattern, visible light and infrared rays used for reading. If it is transparent resin, there will be no limitation in particular, For example, a thermoplastic resin, a thermosetting resin, an ionizing radiation curable resin etc. are mentioned. Among these, from the viewpoint of obtaining durability, solvent resistance, and a wide reading angle, a resin of a type that is cured by crosslinking is preferable, and further, an ionizing radiation curable resin that can be crosslinked in a short time by ionizing radiation. preferable. This ionizing radiation curable resin is advantageous because it can be coated and formed in a solvent-free or solvent-free state in that it easily fills the unevenness caused by the transparent pattern. As the ionizing radiation curable resin, those used in the uneven layer can be preferably used.

Examples of the thermoplastic resin include an acrylic resin, a polyester resin, a thermoplastic urethane resin, a vinyl acetate resin, a cellulose resin, and the like, and a material for the transparent substrate is a cellulose resin such as TAC (triacetyl cellulose). In this case, as the thermoplastic resin, for example, a cellulose resin such as nitrocellulose, acetylcellulose, cellulose acetate propionate, and ethylhydroxyethylcellulose is preferable.
Examples of the thermosetting resin include phenol resin, urea resin, diallyl phthalate resin, melanin resin, guanamine resin, unsaturated polyester resin, urethane resin, epoxy resin, aminoalkyd resin, melamine-urea cocondensation resin, silicon resin. , Polysiloxane resin, curable acrylic resin, and the like. When a thermosetting resin is used, a curing agent such as a crosslinking agent and a polymerization initiator, a polymerization accelerator, a solvent, a viscosity modifier and the like can be further added as necessary.

From the viewpoint of obtaining a wide reading angle, the primer layer 4 is added with a leveling agent (liquid repellent material) so that the surface of the transparent pattern is curved upwardly curved (for example, a curved surface such as a hemispherical surface). In addition, it is preferable to add fine particles.
As the leveling agent, those usually used can be used without particular limitation, and examples thereof include various surfactants such as fluorine-based, silicone-based, and acrylic acid copolymer-based ones, depending on the desired reading angle. Can be added as appropriate.
As the fine particles, those usually used can be added in an appropriate amount without any particular limitation. For example, inorganic particles include spherical particles such as α-alumina, silica, kaolinite, iron oxide, diamond, and silicon carbide. Examples of the particle shape include a sphere, an ellipsoid, a polyhedron, a scale shape, and the like. Although there is no particular limitation, a spherical shape is preferable. Organic materials include synthetic resin beads such as cross-linked acrylic resin and polycarbonate resin. Among these, α-alumina and silica are preferable and spherical ones are particularly preferable because they are high in hardness and have a large effect on improving wear resistance, and are easy to obtain spherical particles. The particle diameter of the fine particles is about 50 μm to 5 mm.

  In addition, the primer layer 4 is appropriately coated with various known additives and various coating liquids and inks as necessary within a range that does not interfere with the infrared reflection function and moire prevention effect of the transparent pattern according to the present invention. You may add a pigment | dye suitably. Examples of the additive include a light stabilizer such as an ultraviolet absorber, a dispersion stabilizer, and the like, and examples of the dye include known dyes in display filters such as an external light antireflection dye.

The primer layer 4 is a layer formed by using a composition containing, in addition to the resin, usually a solvent and, if necessary, various additives, pigments and the like as a coating liquid or ink. As the solvent, the same solvents as those used for the transparent ink are used.
The primer layer 4 can be formed of the ink thus obtained by a known layer forming method such as a coating method or a printing method. Specifically, the transparent pattern may be formed on the printed surface of the printed transparent substrate by a coating method such as roll coating, comma coating, or die coating, or a printing method such as screen printing or gravure printing. In the printing method, partial formation in an arbitrary shape is easy, but even in the coating method, partial formation can be performed by intermittent coating.

The thickness of the primer layer 4 is usually about 0.1 to 10 μm, and is preferably 0.1 to 5 μm from the viewpoint of producing a thinner film and obtaining a wider reading angle.
The liquid crystal sheet 11 can be provided with such a primer layer as necessary.

[Other layers]
Moreover, the transparent sheet of the present invention can be provided with an overcoat layer (surface protective layer made of a hard coating film) on the transparent substrate 2. The transparent sheet of the present invention is provided with such a layer, so that when the transparent sheet of the present invention is used for handwriting input with a pen-type input terminal, it can withstand repeated contact with the input terminal. Is given. The material for the overcoat layer is not particularly limited, and those used in the field of ordinary transparent sheets and lenses can be used. For example, acrylic resin, silicon-based resin, and the like that are crosslinked and cured by ultraviolet rays, electron beams, heat, and the like are representative. In order to reduce moire, a material having a refractive index close to that of the liquid crystal used for the transparent ink can be preferably used.
Furthermore, in order to ensure the visibility of the display device behind the transparent sheet of the present invention, an antireflection film or the like may be provided on the surface or inside of the sheet. The material of the antireflection film is not particularly limited, and those used in the field of normal display transparent sheets and lenses can be used. For example, a dielectric in which a thin film of a low refractive index material such as magnesium fluoride or fluorine resin and a thin film of a high refractive index material such as zirconium oxide or titanium oxide are laminated so that the thin film with a low refractive index is the outermost surface. A body multilayer film is a typical one.

[Application to display devices]
The infrared reflection pattern printed transparent sheet of the present invention can be preferably used for a display device such as one connected to an information processing device that processes handwritten input data. A preferred embodiment when the transparent sheet 1 of the present invention is used in the display device 9 is shown in FIG.
In FIG. 4, the transparent sheet 1 of the present invention is mounted facing the front surface of a display device 9 capable of displaying an image. Here, “attached to the front surface of the display device 9” means, for example, a case where the transparent sheet 1 is disposed in direct contact with the surface of the display device 9, or a pressure-sensitive adhesive layer or an adhesive layer. It is a concept that includes a case where the display device 9 is disposed in front of the display device 9 in a non-contact state via a gap. The transparent ink constituting the transparent pattern 3 includes an infrared reflective material, reads the infrared reflection pattern by the input terminal 6 capable of irradiating and detecting infrared rays, and position information (position coordinates) of the input terminal on the transparent sheet 1. ) Can be provided. The infrared reflective material is obtained by cutting or pulverizing a liquid crystal sheet containing a liquid crystal material having a fixed cholesteric structure and having wavelength selective reflectivity with respect to wavelengths in the infrared region. The transparent sheet of the present invention has a wide reading angle of 0 to 40 ° by using such an infrared reflecting material.

In the infrared reflective pattern printed transparent sheet of the present invention, the pattern is set so that position information of the input terminal on the sheet surface can be derived from a partial pattern read by the input terminal equipped with the sensor. It is.
Such patterns are also exemplified in Patent Documents 2 and 3, for example, by setting a plurality of dot shapes and patterning a combination of these multiple-shaped dots arranged within a predetermined range in a plane. Such as a pattern in which the size of the overlapping portion of the ruled lines within a predetermined range is changed by changing the thickness of the ruled lines arranged in the vertical and horizontal directions, and the x and y coordinate values are directly set in the vertical and horizontal directions of the dots. However, as a particularly simple and preferable one, set reference points arranged at equal intervals in the vertical and horizontal directions, and arrange dots displaced vertically and horizontally with respect to this reference point. There is a dot pattern method that uses the relative positional relationship of these dots from the reference point. This method is advantageous in increasing the resolution of the input device because the dot size can be made small and constant, and is also preferable from the viewpoint of obtaining a wider reading angle. Also, from the viewpoint of obtaining a wider reading angle, after forming a transparent pattern with transparent ink, it is possible to mechanically perform an unevenness process using an embossed plate or the like. The unevenness treatment can be performed by ordinary means.

In the infrared reflection pattern printed transparent sheet of the present invention, it is preferable that the infrared reflectance at the selective reflection peak wavelength is large in order to detect the reflection pattern by the infrared sensor provided in the input terminal. Usually, the reflectivity is about 5 to 50% at the selective reflection peak wavelength, and preferably 20% or more. The reflection by the cholesteric structure has a property of reflecting only circularly polarized light in the same direction as the cholesteric spiral, and therefore reaches only about 50% at the maximum.
In the case of reflection by a cholesteric structure, the reflection intensity generally increases as the printing thickness increases, but if it is too thick, the liquid crystal orientation is unnecessarily disturbed, the transparency decreases, and the drying load increases. The thickness is usually about 1 to 20 μm, preferably about 3 to 15 μm. The cholesteric liquid crystal structure has a helical pitch of about 10 to 20 pitches, and the reflectance is said to be saturated. However, if the liquid crystal composition and the solidification conditions are determined, the film thickness at which the reflection intensity is saturated in actual manufacturing is determined. It may be obtained experimentally to optimize the reflectance. If the film thickness (or the number of pitches) is within the above range, it is possible to prevent the printed pattern from being worn and damaged, and to suppress an unnecessarily high manufacturing cost.
When the print pattern is a dot pattern, the dot shape is not particularly limited as long as it can be easily distinguished from adjacent dots, and usually, the shape in plan view is a circle, an ellipse, a polygon, or the like. The three-dimensional shape of the dot is not particularly limited and is usually a disc shape, but may be a hemispherical shape or a concave shape.

[Display device]
The display device to which the infrared reflective pattern-printed transparent sheet of the present invention can be suitably attached may be connected to an information processing device that processes handwritten input data, or may be independent, but the former Is preferable because the locus during handwriting input can be displayed on the screen and intuitive input is possible.
Examples of the information processing apparatus that handles handwritten input information include various portable terminals such as mobile phones and PDAs, personal computers, videophones, televisions having an intercommunication function, Internet terminals, and the like.

As shown in FIG. 4, the input terminal 6 that can be used in the present invention is not particularly limited as long as it emits infrared rays i and can detect the reflected light r of the pattern, and a known sensor may be used. For example, as an example in which the pen-type input terminal 6 also includes the read data processing device 7, as disclosed in Japanese Patent Application Laid-Open No. 2003-256137, a pen tip that does not include ink, graphite, or the like, and a CMOS that includes an infrared irradiation unit Examples include a camera, a processor, a memory, a communication interface such as a wireless transceiver using a Bluetooth technology, and a built-in battery.
As an operation of the pen-type input terminal 6, when the pen tip is drawn so as to be brought into contact with the front surface of the transparent sheet 1 on which the transparent pattern 3 (dot pattern) shown in FIG. 5 is printed, the pen-type input is performed. The terminal 6 detects the pen pressure applied to the pen tip, and the CMOS camera operates to irradiate a predetermined range in the vicinity of the pen tip with an infrared ray having a predetermined wavelength emitted from the infrared irradiation unit and to pick up a pattern (pattern imaging). Is performed, for example, several tens to 100 times per second). When the pen-type input terminal 6 includes the read data processing device 7, the input trace associated with the movement of the pen tip during handwriting is digitized and converted into data by analyzing the captured pattern with a processor. The input trajectory data is generated and transmitted to the information processing apparatus.
Note that a communication interface such as a processor, a memory, a wireless transceiver using Bluetooth technology, and a member such as a battery are provided outside the pen-type input terminal 6 as a read data processing device 7 as shown in FIG. May be. In this case, the pen-type input terminal 6 may be connected to the read data processing device 7 with the code 8 or may transmit the read data wirelessly using radio waves, infrared rays or the like.
In addition, the input terminal 6 may be a reader as described in JP-A-2001-243006.

The read data processing device 7 applicable in the present invention has a function of calculating position information from continuous imaging data read by the input terminal 6, combining it with time information, and providing it as input trajectory data that can be handled by the information processing device. If it has, it will not specifically limit, What is necessary is just to comprise members, such as a processor, memory, a communication interface, and a battery.
Further, the read data processing device 7 may be built in the input terminal 6 as disclosed in JP 2003-256137 A, or may be built in an information processing device including a display device. Further, the read data processing device 7 may transmit the position information wirelessly to an information processing device provided with a display device, or may transmit it by a wired connection connected by a code or the like.
The information processing apparatus connected to the display device 5 sequentially updates the images displayed on the display device 5 based on the locus information transmitted from the read data processing device 7, thereby obtaining the locus input by handwriting on the input terminal 6. It can be displayed on the display device in real time (or with a time delay as appropriate) as if it were written with a pen on paper.

As described above, the infrared reflective pattern-printed transparent sheet of the present invention can be mounted on an existing display device as it is, and is manufactured more easily than a position input device such as an electrostatic type or a pressure-sensitive type incorporated in a display device. It is possible to easily reduce the weight, reduce the cost, and increase the size. In addition, even if the function of providing position information is reduced because the pattern that can provide printed position information becomes thin or scratched, it is only necessary to replace the transparent sheet, It is easy for the user to handle.
The infrared reflective pattern-printed transparent sheet of the present invention can be used as a liquid crystal protective sheet when mounted on a liquid crystal display.

The infrared reflective pattern printed transparent sheet of the present invention can be detachably mounted so as to face the front surface of the display device. In this way, not only one display device but also another display device can be attached. Further, it is preferable that the transparent sheet itself is provided with a mounting means for the display device so that the transparent sheet can be mounted on the display device side without performing processing for mounting. The mounting means may be provided integrally with the transparent sheet or may be provided separately.
Examples of such mounting means include a device that hooks a buckle-shaped object on a corner portion of the display device, a device that sandwiches an end portion of the display device, and the like. In the case of mounting on the front surface of the display device, there is a sticking tool that is provided on the contact surface side that comes into contact with the display device and has adhesiveness or adhesiveness for sticking to the display device. Moreover, as a sticking tool, what has the adhesiveness or adhesiveness integrally attached to the transparent sheet, and the thing containing the adhesive agent, adhesive agent, etc. which were directly coated on the contact surface are mentioned.

In order to improve the convenience of manufacturing the infrared reflective pattern printed transparent sheet of the present invention, it is preferable that the transparent sheet is separable. Specifically, those that can be separated with a cutting tool such as a scissors or a dedicated cutting tool, perforations, half-cut (a means often used in the field of packaging materials, and less than the full thickness in the thickness direction) And a method that can be cut by hand by inserting a cut of a depth of about. If this is the case, the user can cut according to the size of the display device owned by each user, so the manufacturer has set several predetermined sizes. This is because a sheet may be manufactured. Further, a perforation may be made in the standard size of a general-purpose display device.
Also, if such usage is possible, it is possible to divide one sheet on which a pattern providing position information is printed, and to indicate different coordinate ranges for each sheet. When such a sheet is used, for example, if a sheet indicating continuous coordinates is applied to an adjacent display device, continuity can be given to input data. Further, by using a plurality of transparent sheets having different coordinate ranges for one input device, different meanings can be given to the respective transparent sheets.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
Example 1
A monomer having a polymerizable acrylate group at both ends, a mesogenic group at the center, and a spacer between the acrylate group and a nematic-isotropic transition temperature of around 110 ° C. (a molecule represented by the compound (9)) 100 parts by mass of a compound having a structure) and 3.3 parts by mass of a chiral agent having a polymerizable acrylate group at both ends (having a molecular structure represented by the chemical formula (12)) are dissolved in cyclopentanone. A cyclopentanone solution was prepared. The cyclopentanone solution was added with 4 parts by mass of a photopolymerization initiator (manufactured by BASF Japan Ltd., Lucillin (registered trademark) TPO).
The obtained cyclopentanone solution was coated on a transparent substrate made of a transparent PET (polyethylene terephthalate) substrate having a thickness of 38 μm so that the layer thickness would be 4 μm, dried at 90 ° C. for 2 minutes, and then irradiated with ultraviolet rays. Thus, the coating layer was crosslinked and cured to obtain a liquid crystal film comprising a liquid crystal layer and a transparent substrate.
Next, using MEK (methyl ethyl ketone) as a solvent, 100 parts by mass of pentaerythritol triacrylate, a leveling agent (manufactured by Big Chemie, trade name: BYK361), 0.03 parts by weight, and a polymerization initiator (manufactured by BASF, trade name: To the solution in which 4 parts by mass of lucillin TPO) was dissolved, flakes 5 obtained by cutting or pulverizing the liquid crystal film to an average of 5 μm × 5 μm (square) using a blade were added so as to be 60% by mass. The ink was stirred well to obtain a transparent ink containing flakes 5.
The transparent ink obtained was printed by a gravure printing method on a transparent substrate made of a transparent PET (polyethylene terephthalate) substrate having a thickness of 125 μm to form a transparent pattern made of circular dots having a particle size of 100 μm in plan view. . Next, simultaneously with drying by heating, the cholesteric phase transition of the liquid crystal was advanced. This was irradiated with ultraviolet rays, and pentaerythritol triacrylate was crosslinked and polymerized by radicals generated from the photopolymerization initiator in the coating film to produce a transparent sheet. When the cross section of the produced transparent sheet perpendicular to the transparent substrate was observed with an SEM, the cross-sectional shape of the printed dots was substantially semicircular, and the helical axis of the cholesteric liquid crystal in the substantially semicircular printed dots Was confirmed to be inclined in all directions. When the transparent sheet was irradiated with infrared rays and the reflected light was detected as an image, it was possible to read up to 40 °, and a transparent sheet having a wide reading angle was obtained.

Comparative Example 1
A transparent sheet was produced in the same manner as in Example 1 except that the cyclopentanone solution prepared in Example 1 was used as a transparent ink. When the transparent sheet was irradiated with infrared rays and the reflected light was detected as an image, it could not be read up to 5 °.

  The infrared reflective pattern-printed transparent sheet of the present invention is excellent in reading performance having a wide reading angle. For this reason, it can be suitably used for a data input system in which handwriting is directly performed on the screen of the display device, has high practical performance, various mobile terminals such as mobile phones and PDAs, personal computers, video phones, and mutual communication functions. It can be used for various information processing apparatuses such as televisions and Internet terminals equipped with the above.

It is sectional drawing cut | disconnected by the surface orthogonal to a transparent substrate which shows one preferable embodiment of the infrared reflective pattern printing transparent sheet of this invention. It is sectional drawing cut | disconnected by the surface orthogonal to a transparent substrate which shows one preferable embodiment of the infrared reflective pattern printing transparent sheet of this invention. It is sectional drawing cut | disconnected by the surface orthogonal to a transparent substrate which shows one preferable embodiment of the liquid crystal film used by this invention. It is the schematic of the whole system using the infrared reflective pattern printing transparent sheet of this invention. It is a principal part enlarged plan view which shows the example in which the dot pattern was irregularly arranged in the infrared reflective pattern printing transparent sheet of this invention.

Explanation of symbols

1: Infrared reflective pattern printing transparent sheet (transparent sheet)
2: Transparent substrate 3: Transparent pattern 4: Primer layer 5: Flakes 6: Input terminal (pen type)
7: Reading data processing device 8: Code 9: Display device 11: Liquid crystal sheet 12: Transparent substrate 13: Liquid crystal layer i: Infrared ray r: Reflected light

Claims (13)

  A transparent sheet in which an infrared reflective transparent pattern is printed on the surface of a transparent substrate, wherein the transparent ink constituting the transparent pattern contains an infrared reflective material, and the transparent pattern can be irradiated and detected with infrared rays. It is a pattern that can provide the position information of the input terminal on the transparent sheet by reading the infrared reflection pattern with the input terminal, and the infrared reflective material is fixed with wavelength selective reflectivity with respect to the wavelength in the infrared region. A transparent sheet printed with an infrared reflection pattern, which is obtained by cutting or crushing a liquid crystal film containing a liquid crystal having a cholesteric structure into flakes.   The infrared reflective pattern-printed transparent sheet according to claim 1, wherein a diameter of a circumscribed circle of the flakes is 0.1 to 10 μm.   The infrared reflection pattern printed transparent sheet according to claim 1, wherein the transparent pattern is a dot pattern.   The infrared reflective pattern printed transparent sheet according to any one of claims 1 to 3, wherein the liquid crystal having a cholesteric structure is a chiral nematic liquid crystal in which a nematic liquid crystal is mixed with a chiral agent.   The infrared reflective pattern-printed transparent sheet according to claim 4, wherein the nematic liquid crystal and the chiral agent each have a functional group capable of crosslinking, and the cholesteric structure is fixed by crosslinking the functional groups.   The infrared reflective pattern printed transparent sheet according to claim 4, wherein the nematic liquid crystal and / or the chiral agent is a compound having an acrylate structure.   The infrared reflective pattern printing transparent sheet in any one of Claims 1-6 which has a primer layer between the said transparent substrate and a transparent pattern.   The infrared reflection pattern printed transparent sheet according to any one of claims 1 to 7, wherein the transparent pattern has a selective reflection peak wavelength at 800 nm to 950 nm.   The infrared reflective pattern printed transparent sheet according to any one of claims 1 to 8, wherein a printing thickness of the transparent pattern is 1 to 20 µm.   The infrared reflective pattern printed transparent sheet according to claim 1, which is mounted to face a front surface of a display device capable of displaying an image.   The infrared reflection pattern printed transparent sheet according to claim 10, further comprising mounting means for mounting on the display device.   The infrared reflective pattern printing transparent sheet according to claim 10 or 11, wherein the mounting means is a sticking tool that is provided on a contact surface side that comes into contact with the display device and has adhesiveness or adhesiveness for sticking to the display device. .   The infrared reflective pattern printed transparent sheet according to any one of claims 1 to 12, which is separable.

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