JP5961003B2 - Voyeurism prevention sheet - Google Patents

Description

  The present invention relates to a voyeurism prevention sheet.

  In recent years, small-sized imaging devices have become widespread, and due to their simplicity, there has been a problem that voyeurism is easily performed even in places where photographing is prohibited. For this reason, there is a problem that an image such as confidential information displayed on a display screen of a display device such as a liquid crystal display or a CRT (CRT) display is easily voyeurized.

  As a technique for preventing the sneak shot of the image displayed on the display screen of the display device, there is a technology for projecting infrared light from the display device side toward the imaging device that is trying to voyeur (see, for example, Patent Document 1). Are known.

  In Patent Document 1, a device that irradiates infrared light toward an imaging device that is about to voyeur from the screen side is provided to reduce the focus adjustment function and the exposure adjustment function of the imaging device.

  However, in the technique of Patent Document 1, it is necessary to separately install a dedicated device for irradiating infrared light toward the image pickup device that is about to voyeurize on the screen side, which increases the size and complexity of the device. It was difficult to prevent voyeurism with a simple structure.

  On the other hand, a technique for arranging a voyeurism prevention base material on a display screen has also been proposed (see, for example, Patent Document 2).

  Patent Document 2 describes that a voyeurism prevention base material is arranged so as to cover a display screen of an automatic cash dispenser. This voyeurism prevention substrate is adjusted so that the transmittance is high for light traveling at an angle within a preset viewing angle range, and the transmittance is low for light traveling at an angle outside the viewing angle range. Yes. Specifically, by using a functional film provided with a louver for viewing angle control in the voyeurism prevention substrate, information on the display screen is visible only when the user is located in front of the display screen, When the user is located at a position deviating from the front, the information on the display screen is not visually recognized. With this configuration, it is possible to prevent voyeurism from an angle deviated from the front of the display screen.

JP 2010-20263 A JP 2007-156683 A

  However, in the technique disclosed in Patent Document 2, voyeurism can be prevented when imaging is performed from an angle deviated from the front of the display screen, but voyeurism is prevented when imaging is performed from the front. I couldn't.

  For this reason, in the prior art, it has been difficult to prevent the sneak shot of an image with a simple configuration.

  The present invention has been made in view of the above, and an object thereof is to provide a voyeurism prevention sheet that can prevent voyeurism of an image with a simple configuration.

  In order to solve the above-described problems and achieve the object, the present invention is a transparent anti-voyeurism sheet including infrared phosphor particles that emit infrared light when excited by visible light.

  According to the present invention, it is possible to prevent voyeurism of an image with a simple configuration.

FIG. 1 is a cross-sectional view schematically illustrating an example of a voyeurism prevention sheet according to the present embodiment, and FIG. 1A is a cross-sectional view schematically illustrating an example of a voyeurism prevention sheet according to the present embodiment. (B) is a cross-sectional view schematically showing an enlarged example of a voyeurism prevention sheet according to the present embodiment. FIG. 2 is a diagram showing an example of an emission spectrum of infrared phosphor particles. FIG. 3 is a diagram showing an example of the production result of infrared phosphor particles. FIG. 4 is a diagram showing an emission spectrum of the infrared phosphor particles. FIG. 5 is a schematic diagram showing a display device on which a voyeurism prevention sheet according to the present embodiment is installed. FIG. 5A is a schematic diagram showing a case where the voyeurism prevention sheet is installed on a liquid crystal monitor. These are the schematic diagrams which show the case where a voyeurism prevention sheet is installed in the CRT monitor. FIG. 6 is a schematic diagram showing a form different from FIG. 5 of the voyeurism prevention sheet according to the present embodiment.

  Hereinafter, an embodiment of a voyeurism prevention sheet according to the present invention will be described in detail with reference to the accompanying drawings.

  The voyeurism prevention sheet 10 of the present embodiment is a transparent (visible light transmittance of 60% or more, the same shall apply hereinafter) sheet-like member. The voyeurism prevention sheet 10 of the present embodiment functions as a voyeurism prevention sheet by being placed on a voyeurism prevention object. For this reason, it is possible to prevent the sneak shot of the image with a simple configuration.

  In the present embodiment, the voyeurism prevention sheet 10 is a laminate in which a transparent infrared light emitting layer 14 is laminated on a transparent support 12 as shown in FIGS. 1 (A) and 1 (B). The infrared light emitting layer 14 is a layer in which infrared phosphor particles 14B are dispersed in a transparent substrate 14A.

  The infrared phosphor particles 14B are transparent particles that are excited by visible light and emit infrared light. Specifically, the infrared phosphor particle 14B emits infrared light having a wavelength longer than that of the excitation light when the irradiated visible light is used as excitation light to excite electrons in the luminescent center element (so-called down-lighting). Conversion luminescence). In addition, the infrared phosphor particles 14B are transparent particles in any state when emitting infrared light by excitation and when not emitting light.

  The infrared phosphor particles 14B may be any particles as long as they have the above-described emission characteristics (transparency and characteristics that emit infrared light when excited by visible light). As the infrared phosphor particle 14B, for example, a particle including the element having the above-described light emission characteristics and a base material supporting the element can be cited.

  Examples of the element having the above light emission characteristics include rare earth elements.

  Examples of the rare earth elements include erbium (Er), holmium (Ho), praseodymium (Pr), thulium (Tm), neodymium (Nd), europium (Eu), ytterbium (Yb), samarium (Sm), and cerium (Ce). And at least one element selected from the group consisting of:

  Among these, as rare earth elements, it emits infrared light of about 850 nm to 950 nm, which is excited by visible light and has low sensitivity to the human eye and high sensitivity to general image sensors. In order to obtain high luminous efficiency, it is preferable to use at least one selected from the group consisting of neodymium (Nd), ytterbium (Yb), samarium (Sm), and praseodymium (Pr), and neodymium (Nd) is used. More preferably.

  As a rare earth element, while emitting infrared light of about 850 nm to 950 nm and using a phosphor containing a rare earth element with high luminous efficiency, while further improving the voyeurism suppression function of the voyeurism prevention sheet 10, and It can suppress that the external appearance of the voyeurism prevention sheet 10 is impaired.

  Further, when the infrared phosphor particles 14B have a configuration in which two or more kinds of rare earth elements are co-added, it is particularly preferable to co-add ytterbium (Yb) and neodymium (Nd) as the rare earth elements. By co-addition of ytterbium (Yb) and neodymium (Nd), ytterbium ions emit light upon receiving energy transfer from excited neodymium ions, compared to the case where no neodymium ions are co-added, a red having a higher photoconversion efficiency. Light emission from outside light can be realized.

The base material may be any base material that can support the rare earth element, and examples thereof include oxide glass. Examples of the oxide glass include boron oxide (B ₂ O ₅ ), phosphoric acid (P ₂ O ₅ ), and anhydrous boric acid (B ₂ O ₃ ). Among these, it is preferable to use a boric anhydride (B ₂ O ₃ ) system.

In addition to the oxide, a halide or sulfide may be used as the base material. The halides, for example, lanthanum chloride _{(LaC l3),} yttrium chloride _{(YC l3),} barium chloride _{(Bac l2),} chlorides and lead chlorides _{(PBC l2),} lead fluoride _(PbF 2), fluoride cadmium Examples thereof include fluorides such as (CdF ₂ ), lanthanum fluoride (LaF ₃ ), and yttrium fluoride (YF ₃ ). As the base material, a halide containing a different element such as yttrium lanthanum fluoride can also be used.

  Here, from the viewpoint of further suppressing the appearance of the voyeurism prevention sheet 10 from being damaged, the base material of the infrared phosphor particles 14B preferably has a basic absorption edge in the ultraviolet region. That is, colorless and transparent means that the visible color region such as yellow or red is not visually recognized and is transparent. In the infrared phosphor particles 14B and the infrared light emitting layer 14, the color of the oxide glass contained in the infrared phosphor particles 14B is the same as that of the infrared phosphor particles 14B and the infrared light emitting layer 14. Contribute. For this reason, it is preferable that the oxide glass as the base material supporting the rare earth element has the following configuration.

  Specifically, the oxide glass is preferably composed of a colorless and transparent glass-forming oxide and a modified oxide that is colorless and transparent and defines the characteristics of the oxide glass.

The glass-forming oxide can be amorphized by itself to form a network network structure. Specific examples of the colorless and transparent glass-forming oxide include phosphoric acid (P ₂ O ₅ ), germanium dioxide (GeO ₂ ), boron oxide (B ₂ O ₅ ), and silicon dioxide (SiO ₂ ). .

  The modified oxide cannot be amorphized by itself, but is an oxide that can be amorphized within the network structure formed by the glass-forming oxide. Therefore, the modified oxide is added to the glass-forming oxide, thereby defining the characteristics of the oxide glass such as refractive index, mechanical properties (hardness, viscosity, etc.) and density.

Examples of the colorless and transparent modified oxide include zinc oxide (ZnO), calcium oxide (CaO), aluminum oxide (Al ₂ O ₃ ), lead oxide (PbO), sodium oxide (Na ₂ O), and potassium oxide (K ₂ ). O).

  The combination of the glass-forming oxide and the modified oxide in the oxide glass as the base material supporting the rare earth element includes at least one of the colorless and transparent glass-forming oxides listed above, and the above. In addition, at least one of the colorless and transparent modified oxides may be used in appropriate combination depending on the properties of the target oxide glass (that is, the infrared phosphor particles 14B and the infrared light emitting layer 14). That's fine.

In addition, in the oxide glass as a base material supporting a rare earth element, as a combination of the glass forming oxide and the modified oxide, B ₂ O ₃ is used as the glass forming oxide and ZnO is used as the modified oxide. This combination is preferable because the mechanical strength of the infrared phosphor particles 14B is good.

  The specific composition of the infrared phosphor particles 14B may be selected from an optimal combination of the constituent materials listed above according to the purpose.

  For example, preferable combinations of the base material and the rare earth element in the infrared phosphor particles 14B include Nd and boric acid-oxidized Bi-based glass, Nd-Yb and boric acid-oxidized Bi-based glass, Yb and oxidized Bi-based glass, and Nd. And boric acid-zinc oxide glass, Nd, boric acid-calcium oxide glass, Yb, phosphate glass, and the like.

  By making the preferred combination of the base material and the rare earth element in the infrared phosphor particles 14B the above combination, it is excited by visible light, and emits light in the wavelength region of 900 nm to 1100 nm, among infrared wavelengths, and Infrared phosphor particles 14B having high light conversion efficiency (luminous efficiency) can be obtained.

  The infrared phosphor particles 14B can be produced by pulverizing a crystal (or amorphous) obtained after mixing and melting the constituent components constituting the infrared phosphor particles 14B using a pulverization method or the like. . Examples of this pulverization include a method of pulverizing by ball mill pulverization using a zirconia reinforced ball or jet mill pulverization.

  Hereinafter, specific examples of the infrared phosphor particles 14B having the above-described emission characteristics are listed.

  As specific examples of Nd—Yb and boric acid-oxide Bi glass as the infrared phosphor particles 14B, neodymium oxide, ytterbium oxide, boric acid, and bismuth oxide are respectively 3 mol% and 1 mol%. , 91 mol%, 5 mol%, and particles obtained by pulverizing after mixing, melting and mixing.

In addition, by mixing and melting at the composition and composition ratio, and adjusting the molding and pulverization conditions, infrared phosphor particles 14B (infrared phosphor particles 14B ₁ having a particle size of 5 mm and a shape factor SF1 of 0.125) ) Was produced. When an emission spectrum obtained by irradiating the infrared phosphor particles 14B ₁ with visible light having a wavelength of 590 nm was measured, a Gaussian-like shape having a central emission wavelength of 1000 nm, a half-value width of 86 nm, and a band of 900 nm to 1100 nm was obtained. Was obtained (see FIG. 2). In addition, clear light emission was not obtained in the visible region. Therefore, the infrared phosphor particles 14B ₁ is excited by irradiation with visible light and emits infrared light, it can be confirmed that the and transparent particles (not shown).

Specific examples of Yb and oxidized Bi-based glass as the infrared phosphor particles 14B include Yb ₂ O ₃ , Bi ₂ O ₃ , and B ₂ O ₃ , 5.1 mol% and 47.5 mol, respectively. %, And particles obtained by weighing, mixing, melting, and pulverizing to 47.4 mol%.

Infrared phosphor particles 14B (infrared phosphor particles) having an average particle size of 0.1 mm and a shape factor SF1 of 1.05 by mixing and melting at the composition and composition ratio and adjusting the molding and grinding conditions. to prepare a 14B ₂ to). When an emission spectrum obtained by irradiating the infrared phosphor particles 14B ₂ with visible light having a wavelength of 590 nm was measured, clear emission within a range of a central emission wavelength of 910 nm, a half width of 50 nm, and a band of 800 to 1000 nm was obtained. Was not obtained. Therefore, the infrared phosphor particles 14B ₂ is excited by irradiation with visible light and emits infrared light, it can be confirmed that the and transparent particles. (Not shown).

Further, specific examples of Nd—Yb and boric acid-oxidized Bi-based glass as the infrared phosphor particles 14B may include the following compositions and ratios. Specifically, Yb ₂ O ₃ , Nd ₂ O ₃ , Bi ₂ O ₃ , and B ₂ O ₃ were mixed with 5.0 mol%, 2.0 mol%, 44.4 mol%, and 48.6 mol, respectively. %, And particles obtained by weighing, mixing, melting and pulverizing.

Incidentally, melt mixing with the composition and composition ratio, by adjusting the molding and milling conditions, particle size 5 mm, the shape factor SF1 of the infrared phosphor particles 14B (infrared phosphor particles 14B ₃ 1.05 ) Was produced. When an emission spectrum obtained by irradiating the infrared phosphor particles 14B ₃ with visible light having a wavelength of 590 nm was measured, a Gaussian-like shape having a central emission wavelength of 1000 nm, a half-value width of 86 nm, and a band of 900 to 1100 nm was obtained. Was obtained (see FIG. 2). In the visible region, clear light emission was not obtained. Therefore, the infrared phosphor particles 14B ₃ is excited by irradiation with visible light and emits infrared light, it can be confirmed that the and transparent particles. (Not shown).

Further, specific examples of Nd—Yb and boric acid-oxidized Bi-based glass as the infrared phosphor particles 14B include Yb ₂ O ₃ , Nd ₂ O ₃ , Bi ₂ O ₃ , and B ₂ O _3. And particles obtained by weighing, mixing, melting, and pulverizing to 5.0 mol%, 2.9 mol%, 43.9 mol%, and 48.1 mol%, respectively (infrared phosphor particles 14B ₄ and Yb ₂ O ₃ and Nd ₂ O ₃ are fixed at 5.0 mol% and 2.9 mol%, respectively, and the ratio of Bi ₂ O ₃ and B ₂ O ₃ is set to “91.9 mol%. "0 mol%", "82.4 mol% and 9.5 mol%", "73.2 mol% and 18.8 mol%", "64.5 mol% and 27.3 mol%", "55.2 mol% and 33.7 mol" % "," 36.6 mol% and 55.4 The same results as above were obtained for particles (infrared phosphor particles 14B ₅ to 14B ₇ ) obtained by weighing, mixing, melting, and pulverizing while changing to “mol%”. That is, these infrared phosphor particles 14B ₄ to 14B ₇ are also particles (infrared phosphor particles 14B) that are excited by visible light irradiation to selectively emit infrared light. This was confirmed (not shown).

Further, as the infrared phosphor particles 14B, Nd and boric acid (glass forming oxide) -zinc oxide (modified oxide) -based glass include neodymium oxide (Nd ₂ O ₃ ) and zinc oxide (ZnO). And boric anhydride (B ₂ O ₃ ). The infrared phosphor particles 14B _can be represented as _{xNd 2 O 3 -yZnO-zB 2} O 3.

“X” is a coefficient indicating the ratio (mol%) of neodymium oxide (Nd ₂ O ₃ ) contained in the infrared phosphor particles 14B, and “y” is contained in the infrared phosphor particles 14B. It is a coefficient indicating the ratio (mol%) of zinc oxide (ZnO), and “z” is a coefficient indicating the ratio (mol%) of boric anhydride (B ₂ O ₃ ) contained in the infrared phosphor particles 14B. is there.

  FIG. 3 is a diagram illustrating an example of a result of producing the infrared phosphor particles 14B by changing the x, y, and z. In this example, each unit of x, y, and z is mol%. The vertical axis in FIG. 3 indicates the value of x, and the horizontal axis in FIG. 3 indicates the ratio of y and z. The combination of x, y, and z corresponding to the position of “◯” in FIG. 3 indicates a combination that can be vitrified, and the combination of x, y, and z corresponding to the position of “x” in FIG. A combination that could not be vitrified was shown.

As shown in FIG. 3, the infrared phosphor particles 14B are composed of neodymium oxide, zinc oxide, and boric anhydride, and the proportion of neodymium oxide contained in the infrared phosphor particles 14B is 0 mol% or more and 5 mol. %, The proportion of zinc oxide contained in the infrared phosphor particles 14B is in the range of 45 mol% to 65 mol%, and the proportion of boric anhydride contained in the infrared phosphor particles 14B is in the range of 35 mol% to 55 mol%. Is preferred.

  Particularly preferably, the ratio of neodymium oxide contained in the infrared phosphor particles 14B is 0.5 mol% to 1.5 mol%, and the ratio of zinc oxide contained in the infrared phosphor particles 14B is 45 mol% to 65 mol%. Hereinafter, the ratio of boric anhydride contained in the infrared phosphor particles 14B is in the range of 35 mol% to 55 mol%.

  More preferably, the proportion of neodymium oxide contained in the infrared phosphor particles 14B is 1.5 mol%, the proportion of zinc oxide contained in the infrared phosphor particles 14B is 55 mol%, and contained in the infrared phosphor particles 14B. The ratio of boric anhydride to be obtained is 43.5 mol%.

Specifically, Nd ₂ O ₃ is 1.5 mol%, ZnO is 55 mol%, and B ₂ O ₃ is 43.5 mol%. Infrared phosphor particles 14B having a diameter of 6 mm and a cylindrical shape were produced. When an emission spectrum obtained by irradiating the infrared phosphor particles 14B with visible light having a wavelength of 590 nm was measured, as shown in FIG. 4, the center emission wavelength was 870 nm, the half-value width was 40 nm, and the band was 850 nm to 950 nm. An emission spectrum within the range was obtained. Further, when the emission intensity is measured by setting the thickness of the infrared phosphor particles 14B made of a combination of Nd ³⁺ and ZnO—B ₂ O ₃ glass to 2 mm, the above-mentioned 1.5Nd ₂ O ₃ —55ZnO is used. The emission intensity of the infrared phosphor particles 14B represented by −43.5B ₂ O ₃ was maximized.

In addition, when made with a stainless steel mold at room temperature, Bi ₂ O ₃ —B ₂ O ₃ system glass often had cracks inside, but ZnO—B ₂ O ₃ system glass hardly cracked. . For this reason, it is considered that ZnO—B ₂ O ₃ -based glass is suitable as an oxide glass as a base material combined with a rare earth element.

Further, Nd and boric acid (glass forming oxide) -calcium oxide (modified oxide) glass as the infrared phosphor particles 14B include neodymium oxide (Nd ₂ O ₃ ) and calcium oxide (CaO). And boric anhydride (B ₂ O ₃ ).

  In addition, as a preferable combination of the rare earth element and the oxide glass as the base material in the infrared phosphor particles 14B, Nd and boric acid (glass forming oxide) − are particularly preferable among the specific examples listed above. Zinc oxide (modified oxide) glass or Nd and boric acid (glass forming oxide) -calcium oxide (modified oxide) glass is preferable. The combination of the rare earth element and the base oxide glass in the infrared phosphor particles 14B is more preferably Nd and boric acid (glass forming oxide) -zinc oxide (modified oxide) glass. .

  By using Nd and boric acid (glass forming oxide) -zinc oxide (modified oxide) glass as the infrared phosphor particles 14B, the infrared phosphor particles 14B are excited by visible light and have low sensitivity to the human eye. In addition, it is possible to achieve infrared phosphor particles 14B that emit infrared light having a high sensitivity with respect to a general imaging device and emit light of about 850 nm to 950 nm and exhibit high luminous efficiency and are colorless and transparent.

  In addition, you may add another component to the infrared fluorescent substance particle 14B in the range which does not impair the said luminescent property of the infrared fluorescent substance particle 14B. Examples of the other components include samarium oxide.

  The infrared phosphor particles 14B may be in the form of particles and may be spherical or polygonal, but the shape factor SF1 is preferably 100 or more and 106 or less. The shape factor SF1 can be expressed by the following formula (1).

Formula (1) SF1 = ((Absolute maximum length of diameter of infrared phosphor particle 14B) ² / Projected area of infrared phosphor particle 14B) × (π / 4) × 100

  The particle diameter of the infrared phosphor particles 14B may be appropriately adjusted according to the content of the infrared phosphor particles 14B in the infrared light emitting layer 14, the composition of the infrared phosphor particles 14B, and the like. Examples of the particle diameter (volume average particle diameter) of the infrared phosphor particles 14B include a range of 1 μm to 6 mm.

  The particle size and shape factor SF1 of the infrared phosphor particles 14B are the same as those obtained by mixing and melting the constituent components of the infrared phosphor particles 14B when the infrared phosphor particles 14B are produced. ) By adjusting the grinding conditions.

  The content of the infrared phosphor particles 14B contained in the infrared light emitting layer 14 depends on the thickness of the infrared light emitting layer 14, the distribution of the infrared phosphor particles 14B (whether they are unevenly distributed, which of the infrared light emitting layers 14). Depending on the intensity of visible light emitted from the display screen of the target display device on which the voyeurism prevention sheet 10 is placed, the combination with the constituent material of the transparent base material 14A) Adjust. For example, as content of the infrared fluorescent substance particle 14B in the infrared light emitting layer 14, 10 mass parts or more and 95 mass parts or less are mentioned with respect to 100 mass parts of transparent base materials 14A.

  As described above, the infrared phosphor particles 14B are dispersed in the transparent substrate 14A. It should be noted that the fact that the infrared phosphor particles 14B are “dispersed” in the transparent base material 14A means that the infrared phosphor particles 14B per unit volume of the transparent base material 14A have two primary particles (unaggregated particles). The ratio (number%) of the secondary particles (aggregated particles) is 5% or less. The state in which the infrared phosphor particles 14B are “dispersed” in the transparent base material 14A, that is, the infrared light emitting layer 14, is prepared by, for example, preparing a section of the cross section of the infrared light emitting layer 14 using a microtome or the like. This can be confirmed by directly observing the infrared phosphor particles 14B with a scanning electron microscope.

  The infrared phosphor particles 14B may be dispersed throughout the infrared light emitting layer 14 (transparent substrate 14A) or may be unevenly distributed in the infrared light emitting layer 14. Also good. It should be noted that the requirements defined in the definition of “dispersion” in any state of “dispersed over the entire infrared light emitting layer 14 (transparent substrate 14A)” and “distributed state”. It is preferable that each infrared phosphor particle 14B exists within a range satisfying the above.

  In addition, the state where the infrared phosphor particles 14B are unevenly distributed in the infrared light emitting layer 14 means that when the infrared light emitting layer 14 is divided into a plurality of regions along the surface of the layer, in some regions. The state is shown in which the density of the infrared phosphor particles 14B is higher than in other regions. In the case where the infrared phosphor particles 14B are unevenly distributed in the infrared light emitting layer 14, when the visible image on the anti-voyeurism target object on which the anti-voyeurism sheet 10 is placed is imaged by the imaging device, the infrared fluorescence is emitted. It is preferable to make it unevenly distributed so that it becomes difficult to distinguish the visible image by the infrared light irradiated from the body particles 14B.

  By making the infrared phosphor particles 14B unevenly distributed in a partial region in the plane direction of the infrared light emitting layer 14, the amount of addition of the infrared phosphor particles 14B is reduced, and voyeurism is effectively suppressed. be able to. For example, the infrared phosphor particles 14B may be unevenly distributed only in the center portion in the surface direction of the infrared light emitting layer 14, or the infrared phosphor particles 14B in a pattern indicating characters or figures such as “photographing prohibited”. May be unevenly distributed.

  Next, the transparent substrate 14A will be described. 14 A of transparent base materials should just be comprised from the transparent material which can disperse | distribute the infrared fluorescent substance particle 14B in a base material.

  As this transparent base material 14A, what hardened transparent resin and transparent liquid can be used, for example.

  The transparent resin and the transparent liquid are not particularly limited as long as the infrared phosphor particles 14B can be dispersed at the time of producing the infrared light emitting layer 14, but the dispersibility of the infrared phosphor particles 14B is not limited. It is preferable that it is good and does not significantly reduce the emission intensity due to excitation of the infrared phosphor particles 14B.

  Examples of the transparent resin include polyvinyl chloride (PVC), polystyrene (PS), polymethacrylic acid ester, polysulfone (PSU), and polydimethylsiloxy acid (PDMS). In addition, as transparent resin, you may comprise from 1 type of these resin, and you may comprise from 2 or more types of resin.

  An example of the transparent liquid is a non-aqueous solvent. Examples of non-aqueous solvents include ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol solvents such as methanol, ethanol, n-propanol, isopropanol, and n-butanol; dichloroethyl ether, isopropyl ether, and n-butyl ether. Ether solvents such as toluene and xylene; hydrocarbon solvents such as toluene and xylene; ester solvents such as ethyl acetate, n-propyl acetate, isopropyl acetate and n-butyl acetate; ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether, Polyhydric alcohol solvents such as propylene glycol monoethyl ether; HFE-7100 (trade name, manufactured by Sumitomo 3M Limited), HFE-7200 (trade name, manufactured by Sumitomo 3M Limited), etc. Tsu Motokei solvent; and the like. These non-aqueous solvents may be used alone or in combination of two or more.

  As the transparent resin or transparent liquid, it is preferable to use a resin having a refractive index difference of 0.4 or less with respect to the infrared phosphor particles 14B when configured as the transparent substrate 14A. When the refractive index difference between the transparent substrate 14A and the infrared phosphor particles 14B is 0.4 or less, it is possible to suppress a decrease in the visible light transmittance of the infrared light emitting layer 14, that is, a decrease in transparency.

  The difference in refractive index between the transparent substrate 14A and the infrared phosphor particles 14B can be measured, for example, using a refractometer KRP-30V manufactured by Kalnew Optical Co., Ltd. under natural light.

  The thickness of the infrared light emitting layer 14 is appropriately adjusted depending on the type of infrared phosphor particles 14B included in the infrared light emitting layer 14, the shape factor SF1, the particle size, the configuration of the monitor on which the anti-voyeurism sheet 10 is placed, and the like. do it. Examples of the thickness of the infrared light emitting layer 14 include 0.2 mm or more and 10 mm or less.

  The support 12 is a layer that supports the infrared light emitting layer 14. For example, a substrate made of a transparent resin, a glass substrate, or the like is used as the support 12.

  Examples of the transparent resin include polyvinyl chloride (PVC), polystyrene (PS), polymethacrylic acid ester, polysulfone (PSU), and polydimethylsiloxy acid (PDMS).

  As a constituent material of the support 12, the adhesiveness with the infrared light emitting layer 14 is improved, and the visibility of visible light is prevented from being lowered due to the refractive index difference with the infrared light emitting layer 14. It is preferable to use a material having the same refractive index as the transparent substrate 14A used for the infrared light emitting layer 14, and it is more preferable to use the same material as the transparent substrate 14A.

  In addition, the thickness of the infrared light emitting layer 14 and the support body 12 should just be the thickness according to the form of the display apparatus of the object which mounts the voyeurism prevention sheet 10 of this Embodiment, and if it selects suitably by application object. Good.

  In the voyeurism prevention sheet 10, for example, first, the infrared phosphor particles 14B are dispersed in a solution in which the constituent material of the transparent base material 14A is dissolved in a solvent or the like to prepare a coating solution. And it can produce by forming this coating solution on the support body 12 by the well-known film-forming method.

  The voyeurism prevention sheet 10 of the present embodiment configured as described above functions as a voyeurism prevention sheet by being placed on a voyeurism prevention target object.

  For example, a display screen of a liquid crystal monitor 16 as shown in FIG. 5A, a display device such as a CRT (Cathode Ray Tube) or a liquid crystal monitor 18 as shown in FIG. ) The voyeurism prevention sheet 10 is placed thereon. The voyeurism prevention sheet 10 may be installed by a known method. For example, a fixing member (not shown) for fixing the voyeurism prevention sheet 10 is provided on these various display screens. 10 may be installed on the display screen (image display side). Moreover, a transparent adhesive sheet (not shown) may be attached to the surface of various display screens, and the anti-voyeurism sheet 10 may be placed through the adhesive sheet.

  And the voyeurism prevention sheet 10 of this Embodiment is provided with the infrared light emitting layer 14 containing the infrared fluorescent substance particle 14B which has the said light emission characteristic as mentioned above. For this reason, when the voyeurism prevention sheet 10 provided with the infrared light emitting layer 14 containing the infrared phosphor particles 14B is placed on a voyeurism prevention object such as a display screen of a display device or the like, visible light emitted from the display screen In addition, the infrared phosphor particles 14B in the infrared light emitting layer 14 emit infrared light by visible light included in natural light. For this reason, when an image displayed on the display screen is imaged by an imaging apparatus equipped with a CCD (Charge Coupled Device Image Sensor) via the voyeurism prevention sheet 10, the CCD is also in the infrared wavelength region. Since it has sensitivity, infrared light from the infrared phosphor particles 14B is imaged. For this reason, it is obstructed that the image displayed on the display screen is captured by the imaging device by the infrared light generated by the emission of the infrared phosphor particles 14B, and voyeurism can be prevented.

  Further, since the voyeurism prevention sheet 10 has a sheet shape, the voyeurism prevention sheet 10 can be easily prevented by installing the sheet-like voyeurism prevention sheet 10 on a display screen that is a target for preventing voyeurism.

  Therefore, it is possible to prevent voyeurism of images with a simple configuration.

  The voyeurism prevention sheet 10 is transparent, and the light emitted by the excitation of the infrared phosphor particles 14B is invisible infrared light. For this reason, the sneak shot of the image displayed on the display screen can be prevented without impairing the visibility of the visible image such as characters and pictures displayed on the display screen.

  Note that the object for preventing voyeurism on which the voyeurism prevention sheet 10 is placed is not limited to the display screen of the surface device such as the liquid crystal monitor 16 or the CRT monitor 18 described above. For example, by placing the voyeurism prevention sheet 10 on a recording sheet on which a visible image is formed, it is possible to suppress the voyeurism of the visible image formed on the recording sheet.

  In the present embodiment, the case where the voyeurism prevention sheet 10 is a laminated body in which the infrared light emitting layer 14 is laminated on the support 12 has been described. However, the voyeurism prevention sheet 10 may be configured to have at least the infrared light emitting layer 14, may have a single layer structure including only the infrared light emitting layer 14, or may be three or more layers including the infrared light emitting layer 14. It is good also as a laminated body.

  Further, in order to further improve the light emission efficiency of the infrared phosphor particles 14B in the voyeurism prevention sheet 10, an auxiliary light source 30 may be provided at the end of the voyeurism prevention sheet 10 as shown in FIG. 6 (see voyeurism prevention sheet 10A). Examples of the auxiliary light source 30 include an LED light source that emits visible light (for example, light having a wavelength of 810 nm) toward the infrared light emitting layer 14 of the anti-voyeurism sheet 10.

10, 10A Voyeurism prevention sheet 14 Infrared light emitting layer 14B Infrared phosphor particles

Claims (10)

  A transparent anti-voyeurism sheet containing infrared phosphor particles that emit infrared light when excited by visible light.   The voyeurism prevention sheet according to claim 1, wherein the infrared phosphor particles include a rare earth element and an oxide glass. The oxide glass is colorless and transparent, and is composed of a modified oxide for defining properties including refractive index, mechanical properties, and density of the oxide glass, and a colorless and transparent glass-forming oxide. , preventing sheet spy according to 請 Motomeko 2.   The anti-voyeurism sheet according to claim 3, wherein the modified oxide is zinc oxide.   The voyeurism prevention sheet according to any one of claims 1 to 4, wherein the infrared phosphor particles have a shape factor SF1 of 100 to 106. The rare earth elements include erbium (Er), holmium (Ho), praseodymium (Pr), thulium (Tm), neodymium (Nd), europium (Eu), ytterbium (Yb), samarium (Sm), and cerium (Ce). The voyeurism prevention sheet according to claim 2, which is at least one element selected from the group consisting of: The anti-voyeurism sheet according to claim 2 , wherein the rare earth element is neodymium (Nd). The infrared phosphor particles are composed of neodymium oxide, zinc oxide, and boric anhydride, and the proportion of neodymium oxide contained in the infrared phosphor particles is 0 mol% or more and 5 mol% or less, and the infrared fluorescence. The proportion of zinc oxide contained in the body particles is 45 mol% or more and 65 mol% or less, and the proportion of boric anhydride contained in the infrared phosphor particles is in the range of 35 mol% or more and 55 mol% or less. A voyeurism prevention sheet according to any one of the above. The infrared phosphor particles are composed of neodymium oxide, zinc oxide, and boric anhydride, and the ratio of neodymium oxide contained in the infrared phosphor particles is 1.5 mol%. The anti-voyeurism prevention according to any one of claims 1 to 7, wherein a proportion of zinc oxide contained is 55 mol%, and a proportion of boric anhydride contained in the infrared phosphor particles is 43.5 mol%. Sheet. Further comprising a transparent substrate,
The infrared phosphor particles are dispersed in the transparent substrate;
The voyeurism prevention sheet according to any one of claims 1 to 9, wherein a difference in refractive index between the infrared phosphor particles and the transparent substrate is 0.4 or less.

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