Aerial imaging device

Abstract

An aerial imaging device (10) is provided with: a display unit (1) which has a display surface and which emits light from the display surface; a light diffusion control unit (2) that is disposed on the display surface side of the display unit (1) and that diffuses or transmits the light in accordance with the incident angle thereof; and a light-transmitting image forming unit (3) that is laminated on the surface side of the light diffusion control unit (2) opposite the display unit (1), transmits the light that has passed through the light diffusion control unit (2), and forms an image at a position on the surface side opposite the light diffusion control unit (2), the light diffusion control unit (2) having a shutter-shaped regular internal structure. The shutter-like regular internal structure is provided with a plurality of plate-like regions having a relatively high refractive index in a region having a relatively low refractive index. The aerial imaging device can well suppress the generation of ghosting while maintaining sufficient brightness.

Description

Technical Field

[0001] The present invention relates to an aerial imaging device. Background Art

[0002] Aerial images are images formed by reflecting and refracting light emitted from a light source through optical elements, etc., and then forming an image at an arbitrary position in space. There is no screen or display configured at the position where the aerial image is displayed, and the observer who watches the aerial image will have an incredible feeling. Therefore, in recent years, aerial images have been fully utilized in various applications represented by virtual reality.

[0003] For example, Patent Document 1 discloses an aerial imaging device having at least a display unit and a light-transmitting imaging unit, wherein an image (real image) displayed on the display unit is displayed as an aerial image mainly through the action of the light-transmitting imaging unit.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-060752 Summary of the invention

[0007] 1. Technical issues to be resolved

[0008] When the aerial imaging device is activated, an unexpected image called a ghost image may be displayed along with the aerial image. The ghost image is an unintentional image that does not accurately reflect the real image. In addition, the ghost image may overlap with the aerial image, making it difficult to observe the aerial image properly.

[0009] From the perspective of suppressing the occurrence of the above-mentioned ghosting, an optical element (also called a viewing angle control element, a privacy film, etc.) that transmits only the light entering at a specified incident angle and shields other light will be provided in the aerial imaging device. By using this optical element, the light used to form the ghosting can be shielded, thereby suppressing the occurrence of the ghosting. However, the optical element acts in a manner that shields part of the light emitted by the display unit. Therefore, the overall brightness will be reduced, making it difficult to observe the aerial image brightly, and the contrast of the aerial image will also be reduced.

[0010] The present invention has been made in view of the above-mentioned actual situation, and an object of the present invention is to provide an aerial imaging device that can well suppress the occurrence of ghosting while maintaining sufficient brightness.

[0011] (II) Technical solution

[0012] In order to achieve the above-mentioned purpose, first, the present invention provides an aerial imaging device, characterized in that it comprises: a display unit, which has a display surface and emits light from the display surface; a light diffusion control unit, which is arranged on the display surface side of the display unit and causes the light to diffuse or transmit according to its incident angle; and a translucent imaging unit, which is stacked on the surface side of the light diffusion control unit opposite to the display unit and causes the light penetrating the light diffusion control unit to transmit and form an image at a position on the surface side opposite to the light diffusion control unit, the light diffusion control unit having a regular internal structure in the shape of a louver, and the regular internal structure in the shape of a louver has a plurality of plate-like areas with a relatively high refractive index in an area with a relatively low refractive index (Invention 1).

[0013] In the above invention (Invention 1), it is preferred that the display portion is configured with respect to the light diffusion control portion and the light-transmitting imaging portion in such a manner that the display surface is not parallel to the surface of the light diffusion control portion on the opposite side to the light-transmitting imaging portion (Invention 2).

[0014] In the above invention (Invention 2), it is preferred that: when a direction perpendicular to the long side direction of the plate-shaped area and existing in a plane of the light diffusion control unit on the opposite side to the translucent imaging unit is set as a first direction, and a direction parallel to a plane perpendicular to both the display surface and one surface of the light diffusion control unit and existing in a plane of the light diffusion control unit on the opposite side to the translucent imaging unit is set as a second direction, the acute angle formed by the first direction and the second direction is greater than 0° and less than 90° (Invention 3).

[0015] In the above invention (Invention 1), it is preferred that: when a direction perpendicular to the long side direction of the plate-like region and existing within a plane of the light diffusion control portion on the opposite side to the light-transmitting imaging portion is set as a first direction, each of the plate-like regions is inclined toward the first direction within the light diffusion control portion (Invention 4).

[0016] In the above invention (Invention 4), it is preferable that the angle of inclination of the plate-like region is not less than 0° and not more than 30° with respect to the thickness direction of the light diffusion control section (Invention 5).

[0017] In the above invention (Invention 1), preferably, the light-transmitting imaging section includes a reverse transmission optical element that reversely transmits incident light (Invention 6).

[0018] In the above invention (Invention 6), it is preferred that: the reverse transmission optical element is an element formed by stacking two layers having multiple reflection surfaces, in each of the two layers, the multiple reflection surfaces are perpendicular to one surface of the reverse transmission optical element and are arranged at a predetermined interval from each other, and the two layers are stacked in a manner such that the reflection surface of one of the two layers is orthogonal to the reflection surface of the other layer (Invention 7).

[0019] In the above invention (Invention 7), it is preferred that: assuming that a plane F is perpendicular to the surface of the light-transmitting imaging portion on the opposite side to the light diffusion control portion and the display surface and passes through the center point of the light-transmitting imaging portion, and the width of the light-transmitting imaging portion in a cross section formed by cutting the light-transmitting imaging portion with the plane F is set to width W, when observing the aerial imaging device from an observation point that exists in the plane F and satisfies the following two conditions, Condition A and Condition B,

[0020] The light diffusion control unit has a haze value of 60% or less for light reflected in the two layers constituting the reverse transmission optical element among the light irradiated from any point of the display unit and reaching the observation point,

[0021] The light diffusion control unit has a haze value of 60% or more for light reflected only in one of the two layers constituting the reverse transmission optical element, among the light irradiated from any point of the display unit and reaching the observation point.

[0022] (Condition A)

[0023] When the angle formed by the line segment connecting the observation point and the center point and the surface of the light-transmitting imaging portion on the opposite side to the light diffusion control portion is set as angle α, and the angle formed by the plane including the display surface of the display portion and the plane including the surface of the light-transmitting imaging portion on the opposite side to the light diffusion control portion is set as angle β, the total of the angle α and the angle β is 90°,

[0024] (Condition B)

[0025] The distance between the observation point and the center point is 3.5 times the length of the width W (Invention 8).

[0026] (III) Beneficial effects

[0027] The aerial imaging device of the present invention can effectively suppress the occurrence of ghosting while maintaining sufficient brightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A cross-sectional view schematically showing an example of an aerial imaging device according to an embodiment of the present invention.

[0029] Figure 2 It is a perspective view schematically showing the internal structure of the light diffusion control unit.

[0030] Figure 3 This is a diagram for explaining the relationship between the optical characteristics of the light diffusion control unit and the light forming the aerial image and the light forming the double image.

[0031] Figure 4 It is a cross-sectional view schematically showing the light diffusion control parts of Example 1, Comparative Example 1, and Comparative Example 2.

[0032] Figure 5 A diagram for explaining the incident ranges of the light that forms the aerial image and the light that forms the double image determined in Experimental Example 1.

[0033] Figure 6 This is a graph showing the results of measuring the optical characteristics of the light diffusion control portion in Test Example 1.

[0034] Figure 7 The following are images showing an aerial image and a double image captured in Experimental Example 2. DETAILED DESCRIPTION

[0035] Hereinafter, embodiments of the present invention will be described.

[0036] Figure 1 FIG. 1 is a cross-sectional view schematically showing an example of an aerial imaging device according to the present embodiment. Figure 1 As shown, the aerial imaging device 10 of the present embodiment comprises: a display unit 1, which has a display surface and emits light from the display surface; a light diffusion control unit 2, which is arranged on the above-mentioned display surface side of the display unit 1, and causes the light to be diffused or transmitted according to its incident angle; and a translucent imaging unit 3, which is stacked on the surface side of the light diffusion control unit 2 opposite to the display unit 1, and causes the light that penetrates the light diffusion control unit 2 to be transmitted and imaged at a position on the surface side opposite to the light diffusion control unit 2.

[0037] further, Figure 2 FIG. 2 is a perspective view schematically showing the internal structure of the light diffusion control unit. Figure 2As shown, the light diffusion control portion 2 has a regular internal structure in the shape of a venetian blind, and the regular internal structure in the shape of a venetian blind has a plurality of plate-like regions 201 with a relatively high refractive index in a region 202 with a relatively low refractive index. By having this regular internal structure, the light diffusion control portion 2 can make the incident light incident on the surface of the light diffusion control portion 2 within a specified incident angle range be strongly diffused and emitted at a specified aperture angle. On the other hand, in the case of incident light outside the above-mentioned incident angle range, it can be transmitted without diffusion, or can be emitted with a diffusion weaker than that of the incident light within the incident angle range. In addition, the direction of the surface ( Figure 2 The direction represented by “D1” in FIG. 1 is set as the “first direction”.

[0038] When the aerial imaging device 10 of this embodiment displays a desired image (real image) on the display surface of the display unit 1, when observing from a predetermined observation point 5, it is possible to Figure 1 The image (aerial image) formed by the above-mentioned real image imaging in the air is observed at the position represented by the symbol "4". In addition, in this specification, the surface at the position represented by the symbol "4" is set as the "aerial image observation surface".

[0039] In conventional aerial imaging devices, an image called a ghost image is sometimes displayed while displaying an aerial image. A ghost image is an image that reflects a real image and is displayed around the aerial image on the aerial image observation surface 4, although it is not displayed on the display surface of the display unit 1. In order to suppress the occurrence of such a ghost image, an optical element that only shields light that contributes to the formation of the ghost image is sometimes used. However, since the optical element shields part of the light emitted by the display unit 1, the brightness of the aerial image is reduced, and there is a problem that it is difficult for the observer to observe the aerial image.

[0040] In this regard, the aerial imaging device 10 of this embodiment can effectively suppress the generation of ghosting while maintaining sufficient brightness of the aerial image by having the light diffusion control unit 2. It is speculated that this effect is caused by the role played by the light diffusion control unit 2 as described below. However, it is not limited to this role, and the possibility of other roles is not denied.

[0041] Figure 3 This is a diagram for explaining the role played by the optical diffusion control section 2, and in particular, a diagram for explaining the relationship between the optical characteristics of the optical diffusion control section 2 and the light forming the aerial image and the light forming the double image.

[0042] As described above, the light diffusion control unit 2 diffusely transmits light incident within a predetermined incident angle range, and transmits light incident outside the incident angle range without substantially diffusing it. Figure 3 The graph shows the relationship between the incident angle of light incident on the light diffusion control unit 2 and the haze value. Specifically, for light incident from an incident angle range of about -10° to about 10°, a haze value of more than 80% is shown (that is, the light is diffusely transmitted). On the other hand, for light incident from an incident angle range of about -70° to about -20°, a haze value of about 15% is shown (that is, the light is basically not diffused but transmitted). In addition, sometimes the incident angle at which the haze value changes greatly (in Figure 3 The value of -15° in the figure is called the "threshold".

[0043] Here, the above-mentioned "haze value" is different from the usual "haze" and refers to a measured value obtained by taking a predetermined distance between the opening of the integrating sphere and the sample and changing the incident angle to the sample. In the measurement of this specification, the predetermined distance is set to 20 mm, but as long as it is a value that can confirm the direct transmission / diffuse transmission of the incident light, the value is not particularly limited.

[0044] The aerial imaging device 10 of this embodiment has a light diffusion control unit 2 that exhibits the above-mentioned optical characteristics between the display unit 1 and the light-transmitting imaging unit 3. The light diffusion control unit 2 allows the light used to form the aerial image to reach the light-transmitting imaging unit 3 well, and on the other hand, allows the light used to form the ghost image to reach the light-transmitting imaging unit 3 in a diffused state. As a result, the observer can clearly observe the aerial image and it is not easy to observe the ghost image. Moreover, since the light diffusion control unit 2 does not shield the light but controls the diffusion of the light, it is possible to display the aerial image with sufficient brightness while suppressing the generation of the ghost image.

[0045] In addition, by appropriately adjusting the type of the light diffusion control unit 2 or the stacking state of the light diffusion control unit 2 and the light transmission imaging unit 3, the light diffusion control unit 2 can be formed. Figure 3 By adjusting the threshold value in a manner such that it is located between the incident angle range of light used to form an aerial image and the incident angle range of light used to form a double image, a better effect can be achieved.

[0046] 1. Display

[0047] The display unit 1 constituting the aerial imaging device 10 of the present embodiment is not particularly limited as long as it has a display surface, can display an image on the display surface, and emits light to the light diffusion control unit 2 and the light-transmitting imaging unit 3. For example, as the display unit 1, a liquid crystal (LCD) display, a light-emitting diode (LED) display, an organic electroluminescent (organic EL) display, etc. can be used.

[0048] In addition, the positional relationship between the display unit 1, the light diffusion control unit 2, and the light-transmitting imaging unit 3 is not particularly limited. Figure 1 As shown, the display unit 1 and the light diffusion control unit 2 are sufficiently separated, and there is a space between them. In addition, it is also preferred that the display unit 1 is arranged with respect to the light diffusion control unit 2 and the light transmission imaging unit 3 in such a manner that the display surface of the display unit 1 is not parallel to the surface of the light diffusion control unit 2 on the opposite side to the light transmission imaging unit 3. With this positional relationship, the aerial image can be better displayed.

[0049] 2. Light diffusion control unit

[0050] The light diffusion control unit 2 constituting the aerial imaging device 10 of the present embodiment is not particularly limited as long as it has the above-mentioned louver-like regular internal structure.

[0051] From the perspective of easily forming the above-mentioned regular internal structure, the light diffusion control unit 2 is preferably a material formed by curing a light diffusion control unit composition, wherein the light diffusion control unit composition contains a high refractive index component and a low refractive index component having a refractive index lower than that of the high refractive index component. In particular, the high refractive index component and the low refractive index component preferably each have 1 or 2 polymerizable functional groups.

[0052] (1) High refractive index component

[0053] As a preferred example of high refractive index, (meth)acrylate containing aromatic rings can be listed, and (meth)acrylate containing multiple aromatic rings can be particularly preferably listed. As examples of (meth)acrylate containing multiple aromatic rings, biphenyl (meth)acrylate, naphthyl (meth)acrylate, anthracene (meth)acrylate, benzylphenyl (meth)acrylate, biphenyloxyalkyl (meth)acrylate, naphthyloxyalkyl (meth)acrylate, anthraceneoxyalkyl (meth)acrylate, benzylphenoxyalkyl (meth)acrylate, etc., and compounds in which a part of these compounds is substituted by halogen, alkyl, alkoxy, haloalkyl, etc. can be listed. Among them, from the perspective of easily forming a good regular internal structure, biphenyl (meth)acrylate is preferred, and specifically, o-phenylphenoxyethyl acrylate, o-phenylphenoxyethoxyethyl acrylate, etc. are preferred. In addition, in this specification, (meth)acrylic acid refers to both acrylic acid and methacrylic acid. The same is true for other similar terms.

[0054] The molecular weight of the high refractive index component is preferably 150 to 2500, particularly preferably 200 to 1500, and further preferably 250 to 1000. By making the molecular weight within the above range, it is easy to form a light diffusion control unit 2 with a desired regular internal structure. In addition, in the case where the theoretical molecular weight of the high refractive index component can be determined according to the molecular structure, the molecular weight of the high refractive index component refers to the theoretical molecular weight. However, in the case where the theoretical molecular weight is difficult to determine because the high refractive index component is, for example, a polymer component, the molecular weight of the high refractive index component refers to the weight average molecular weight obtained as a value converted by standard polystyrene determined by gel permeation chromatography (GPC). In addition, the method for determining the weight average molecular weight in this specification refers to a value converted by standard polystyrene determined by the GPC method.

[0055] The refractive index of the high refractive index component is preferably 1.45 to 1.70, more preferably 1.50 to 1.65, particularly preferably 1.54 to 1.62, and further preferably 1.56 to 1.59. By making the refractive index within the above range, it is easy to form a light diffusion control unit 2 having a desired regular internal structure. In addition, the refractive index in this specification refers to the refractive index of a specified component before curing the composition for the light diffusion control unit, and the refractive index is a value measured based on JIS K0062:1992.

[0056] The content of the high refractive index component in the light diffusion control layer composition is preferably 25 to 400 parts by mass, more preferably 50 to 350 parts by mass, particularly preferably 75 to 300 parts by mass, and further preferably 100 to 200 parts by mass relative to 100 parts by mass of the low refractive index component. By making the content within the above range, in the regular internal structure of the formed light diffusion control layer 11, the region from the high refractive index component and the region from the low refractive index component exist in a desired ratio, and the desired regular internal structure is easily formed.

[0057] (2) Low refractive index component

[0058] Preferred examples of low refractive index components include urethane (meth) acrylate, (meth) acrylic polymers having (meth) acryloyl groups in side chains, silicone resins containing (meth) acryloyl groups, unsaturated polyester resins, etc. Among them, urethane (meth) acrylate is particularly preferred from the perspective of easily forming a good regular internal structure. More specifically, urethane (meth) acrylate formed from (a) a compound containing at least two isocyanate groups, (b) a polyalkylene glycol, and (c) a hydroxyalkyl (meth) acrylate is preferably used.

[0059] Preferred examples of the compound (a) containing at least two isocyanate groups include aromatic polyisocyanates such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylylene diisocyanate, and 1,4-xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and biuret forms and isocyanurate forms of these compounds, and adducts thereof as reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil, etc. Among them, alicyclic polyisocyanates are preferred, and alicyclic diisocyanates are particularly preferred.

[0060] Preferred examples of the polyalkylene glycol (b) include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyethylene glycol, etc. Among them, polypropylene glycol is preferred. In addition, the weight average molecular weight of the polyalkylene glycol (b) is preferably 2300 to 19500, particularly preferably 3000 to 14300, and further preferably 4000 to 12300.

[0061] Preferred examples of the (c) hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. Among them, 2-hydroxyethyl (meth)acrylate is preferred.

[0062] The synthesis of urethane (meth) acrylate using the above components (a) to (c) as materials can be carried out according to conventional methods. In this case, from the perspective of efficient synthesis of urethane (meth) acrylate, the blending ratio of components (a) to (c) is preferably (a) component: (b) component: (c) component = 1-5:1:1-5, and particularly preferably 1-3:1:1-3 in terms of molar ratio.

[0063] The weight average molecular weight of the low refractive index component is preferably 3000 to 20000, particularly preferably 5000 to 15000, and further preferably 7000 to 13000. When the weight average molecular weight is within the above range, the light diffusion control unit 2 having a desired regular internal structure can be easily formed.

[0064] The refractive index of the low refractive index component is preferably 1.30 to 1.59, more preferably 1.38 to 1.50, particularly preferably 1.42 to 1.49, and further preferably 1.46 to 1.48 or less. By setting the refractive index within the above range, it is easy to form the light diffusion control unit 2 having a desired regular internal structure.

[0065] (3) Other additives

[0066] In addition to the high refractive index component and the low refractive index component, the light diffusion control unit composition may also contain other additives. Other additives include, for example, multifunctional monomers, photopolymerization initiators, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, polymerization accelerators, polymerization inhibitors, infrared absorbers, plasticizers, diluents, and leveling agents.

[0067] Among them, the light diffusion controlling layer composition preferably contains a photopolymerization initiator. This makes it easy to efficiently form the light diffusion controlling part 2 having a desired regular internal structure.

[0068] Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propane-1-one, 4-(2-hydroxyethoxy)phenyl-2-(

[0043] In some embodiments, the photopolymerization initiator may be benzophenone, benzophenone, p-phenylbenzophenone, 4,4-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo[2-hydroxy-2-methyl]-1-[4-(1-methylvinyl)phenyl]propane], etc. These photopolymerization initiators may be used alone or in combination of two or more.

[0069] When a photopolymerization initiator is used, the content of the photopolymerization initiator in the light diffusion control unit composition is preferably 0.2 to 20 parts by weight, more preferably 0.5 to 16 parts by weight, particularly preferably 1 to 13 parts by weight, and further preferably 1 to 10 parts by weight, relative to 100 parts by weight of the total amount of the high refractive index component and the low refractive index component. By setting the content within the above range, it is easy to effectively form the light diffusion control unit 2 having a desired regular internal structure.

[0070] (4) Preparation of Composition for Light Diffusion Control Unit

[0071] The light diffusion control unit composition can be prepared by uniformly mixing the high refractive index component and the low refractive index component described above, and other additives such as a photopolymerization initiator and an ultraviolet absorber as required.

[0072] During the mixing, the mixture may be stirred while being heated to 40° C. to 80° C. to obtain a uniform light diffusion control member composition. A diluting solvent may be added and mixed so that the obtained light diffusion control member composition has a desired viscosity.

[0073] (5) Internal structure of rules

[0074] As described above, the light diffusion control unit 2 preferably has a louver-like regular internal structure including a plurality of plate-like regions 201 having a relatively high refractive index in a region 202 having a relatively low refractive index.

[0075] In the light diffusion control unit 2, as Figure 2 As shown, it is preferred that each of the plate-shaped regions 201 is inclined in the first direction D1 in the light diffusion control unit 2. Thus, the aerial imaging device 10 of the present embodiment can easily display an aerial image more brightly while suppressing the occurrence of ghost images.

[0076] When the plate-like region 201 is tilted as described above, the tilt angle is preferably 0° or more, more preferably 1° or more, particularly preferably 2° or more, and further preferably 3° or more relative to the thickness direction of the light diffusion control unit 2. In addition, the above angle is preferably 30° or less, more preferably 28° or less, particularly preferably 25° or less, further preferably 20° or less, and particularly preferably 10° or less. By tilting the plate-like region 201 at the above angle, the aerial imaging device 10 of this embodiment can easily suppress the generation of ghosting and display the aerial image more brightly.

[0077] The light diffusion control unit 2 may also have Figure 2 For example, the plate-shaped region 201 may be bent in the middle of the thickness direction of the light diffusion control unit 2. In addition, the light diffusion control layer 10 may be a layer having a regular internal structure in which two or more plate-shaped regions 201 are arranged.

[0078] (6) Thickness of the light diffusion control portion

[0079] The thickness of the light diffusion control unit 2 is preferably 1 to 500 μm, more preferably 10 to 300 μm, particularly preferably 50 to 250 μm, further preferably 80 to 200 μm, and particularly preferably 100 to 160 μm. By making the thickness within the above range, the aerial imaging device 10 of this embodiment can easily suppress the generation of ghosting and display the aerial image more brightly.

[0080] (7) Method for forming light diffusion control portion

[0081] The method for forming the light diffusion control section 2 is not particularly limited, and the light diffusion control section 2 may be formed by a conventionally known method.

[0082] For example, after the aforementioned light diffusion control layer composition is applied to one surface of the process sheet to form a coating film, one surface (particularly the peeling surface) of the release sheet is attached to the surface of the coating film opposite to the process sheet. Then, the coating film is irradiated with active energy rays through the process sheet or the release sheet to be cured, thereby forming the light diffusion control part 2. Thus, by laminating the release sheet on the coating film, the gap between the release sheet and the process sheet is maintained, the coating film is prevented from being crushed, and the light diffusion control part 2 with uniform thickness and a desired regular internal structure is easily formed.

[0083] As the stripping film, for example, resin films such as polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene-(methyl) acrylic acid copolymer film, ethylene-(methyl) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, and fluororesin can be used. In addition, crosslinked films of these films can also be used. Further, laminated films of these films can also be used.

[0084] The release surface of the release sheet is preferably subjected to a release treatment. As the release agent used for the release treatment, preferably, for example, alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, paraffin-based, etc. release agents are mentioned.

[0085] The thickness of the release sheet is not particularly limited, but is preferably 20 to 200 μm, more preferably 30 to 100 μm, from the viewpoint of excellent handleability and good protection until the light diffusion controlling portion is used.

[0086] As the process sheet, the resin film, crosslinked film, or laminated film thereof used as the release sheet can be used. In addition, the release sheet can also be used as the process sheet.

[0087] The thickness of the process sheet is preferably 20 to 250 μm, more preferably 30 to 200 μm, from the viewpoint of facilitating the formation of a desired light diffusion controlling portion and enabling good protection until the light diffusion controlling portion is used.

[0088] Examples of the coating method include knife coating, roll coating, bar coating, blade coating, die coating, and gravure coating. The light diffusion control unit composition may be diluted with a solvent as necessary.

[0089] The coating film may be irradiated with active energy rays by a conventionally known method. For example, a linear light source is used as the light source of the active energy rays, and the surface of the irradiated object is irradiated with band-shaped (roughly linear) light that is random in the width direction (TD direction) and slightly parallel in the conveying direction (MD direction). In addition, by adjusting the irradiation angle of the above light, the inclination angle of the plate-shaped region 201 can also be adjusted.

[0090] The active energy rays are active energy rays having energy quanta among electromagnetic waves or charged particle beams, and specific examples thereof include ultraviolet rays, electron beams, etc. Among active energy rays, ultraviolet rays are particularly preferred because they are easy to handle and can easily form a desired regular internal structure.

[0091] When ultraviolet rays are used as active energy rays, the irradiation conditions are preferably such that the peak illuminance on the coating surface is 0.1 to 200 mW / cm 2 Furthermore, it is preferred that the accumulated light intensity on the coating surface be set to 5 to 300 mJ / cm 2 In addition, the relative moving speed of the active energy ray light source with respect to the irradiation target is preferably 0.1 to 10 m / min.

[0092] In order to achieve more reliable curing, it is preferred to irradiate with normal active energy rays (active energy rays or scattered light that have not been converted into parallel light, strip light, etc.) after curing using the aforementioned strip light.

[0093] 3. Transparent imaging unit

[0094] The light-transmitting imaging unit 3 constituting the aerial imaging device 10 of the present embodiment is not particularly limited as long as it can transmit light from the display unit 1 and form an aerial image on a predetermined aerial image observation surface. Examples of such a light-transmitting imaging unit 3 include a reverse transmission optical element that reversely transmits incident light.

[0095] As the above-mentioned reverse transmission optical element, although the reverse transmission optical element known in the past can be used, from the perspective of making it easy to form an aerial image well, it is preferred to use a reverse transmission optical element having a dihedral corner reflector array structure, a reverse transmission optical element formed by stacking two layers with multiple reflection surfaces, etc., and it is more preferred to use a reverse transmission optical element formed by stacking two layers with multiple reflection surfaces. In particular, in the reverse transmission optical element, it is preferred that: in each of the above-mentioned two layers, the multiple reflection surfaces are perpendicular to one surface of the reverse transmission optical element and are arranged at a predetermined interval from each other, and the above-mentioned two layers are stacked in a manner that the above-mentioned reflection surface of one of the above-mentioned two layers is orthogonal to the above-mentioned reflection surface of the other layer.

[0096] The thickness of the light-transmitting imaging portion 3 is preferably 0.1 to 20 mm, more preferably 0.5 to 15 mm, particularly preferably 1 to 12 mm, further preferably 2 to 10 mm, and particularly preferably 4 to 8 mm. By making the thickness of the light-transmitting imaging portion 3 within the above range, the aerial imaging device 10 of this embodiment can easily suppress the generation of ghosting and display the aerial image more brightly.

[0097] 4. Other components

[0098] The aerial imaging device 10 of this embodiment may also include components other than the above-mentioned display unit 1, light diffusion control unit 2, and light-transmitting imaging unit 3. In particular, the aerial imaging device 10 of this embodiment preferably includes a frame for fixing and storing the display unit 1, light diffusion control unit 2, and light-transmitting imaging unit 3 at a predetermined position.

[0099] The material, shape, size, etc. of the frame can be appropriately selected according to the application, purpose, etc. In particular, the frame is preferably formed of a light-shielding material, which can prevent the light from the display unit 1 from accidentally leaking to the outside, and at the same time prevent the external light from accidentally intruding the light path from the display unit 1 to the light diffusion control unit 2.

[0100] 5. Positional relationship of each element

[0101] In the aerial imaging device 10 of the present embodiment, it is assumed that Figure 1 In the case where the first direction is indicated by "D1" in the figure, and the direction parallel to the plane perpendicular to the display surface of the display unit 1 and one surface of the light diffusion control unit 2 and existing in the surface of the light diffusion control unit 2 on the opposite side of the light-transmitting imaging unit 3 is assumed to be the second direction, the acute angle formed by the first direction and the second direction is preferably greater than 0° and less than 90°. Regardless of the angle of the above-mentioned acute angle, by considering the incident angle to the light diffusion control unit 2 in the plane including D1 and perpendicular to the light diffusion control unit 2, the aerial imaging device 10 of this embodiment can easily suppress the generation of ghosting while displaying the aerial image more brightly.

[0102] In addition, the aerial imaging device 10 of this embodiment, when having the above-mentioned reverse transmission optical element with a dihedral corner reflector array structure as a translucent imaging unit 3, or having a reverse transmission optical element formed by stacking two layers with multiple reflection surfaces, preferably satisfies the following conditions.

[0103] First, as a premise, a plane F is assumed which is perpendicular to the surface of the light-transmitting imaging section 3 on the opposite side to the light diffusion control section 2 and the display surface of the display section 1 and passes through the center point of the light-transmitting imaging section 3. And, the width of the light-transmitting imaging section 3 in the cross section formed by cutting the light-transmitting imaging section 3 with the plane F is set to width W.

[0104] Furthermore, an observation point that exists within the plane F and satisfies the following two conditions, Condition A and Condition B, is assumed.

[0105] (Condition A)

[0106] When the angle formed by the line segment connecting the above-mentioned observation point and the above-mentioned center point and the surface of the translucent imaging part 3 on the opposite side to the light diffusion control part 2 is set to angle α, and the angle formed by the plane including the display surface of the display part 1 and the plane including the surface of the translucent imaging part 3 on the opposite side to the light diffusion control part 2 is set to angle β, the total of angle α and angle β is 90°.

[0107] (Condition B)

[0108] The distance between the observation point and the center point is 1 to 10 times the width W.

[0109] In addition, as a supplement, the above condition A means that the position of the observation point is determined according to the positional relationship between the display unit 2 and the light-transmitting imaging unit 3 in the aerial imaging device 10. For example, for the aerial imaging device 10 in which the display unit 2 and the light-transmitting imaging unit 3 are set at an angle β of 45°, it means that the angle α of the observation point is 45°, and for the aerial imaging device 10 in which the angle β is 60°, the angle α of the observation point is 30°.

[0110] In addition, regarding the above condition B, the expression "1 to 10 times the length of the width W" means that the above observation point only needs to satisfy the condition of any point in the range. In particular, the condition B is preferably "the distance between the above observation point and the above center point is 3.5 times the length of the width W".

[0111] Then, when the aerial imaging device 10 is viewed from this observation point, it is preferable that each element of the aerial imaging device 10 is configured so that the light diffusion control unit 2 satisfies the following two conditions simultaneously.

[0112] (Condition 1)

[0113] Of the light irradiated from any point of the display unit 1 and reaching the observation point, the haze value of the light reflected by the two layers constituting the reverse transmission optical element is 60% or less.

[0114] (Condition 2)

[0115] Of the light irradiated from any point of the display unit 1 and reaching the observation point, the light reflected in only one of the two layers constituting the retro-transmissive optical element has a haze value of 60% or more.

[0116] By making the aerial imaging device 10 of the present embodiment satisfy the above-mentioned conditions, it is easy to display the aerial image more brightly while suppressing the occurrence of ghosting.

[0117] Here, "reflection occurs in both layers of the two layers" or "reflection occurs in only one of the two layers" means reflection in the sense of change in the traveling direction, not physical reflection. Since parallel mirror surfaces are arranged in each layer of the reverse transmission optical element formed by stacking two layers with multiple reflection surfaces, the traveling direction changes at odd-numbered reflections, and does not change at even-numbered reflections. The "reflection occurs" in the above sentence can be replaced by "an odd-numbered reflection occurs, and the traveling direction changes".

[0118] 6. Physical properties of aerial imaging devices

[0119] In the aerial imaging device 10 of the present embodiment, the luminance measured when the entire surface of the display unit 1 is displayed in white is preferably 1 to 1000 cd / m 2 , more preferably 3~500cd / m 2 , particularly preferably 5 to 100 cd / m 2 , more preferably 7~50cd / m 2 , especially preferably 9~30cd / m 2 , the most preferred is 10~15cd / m 2 By setting the brightness when displaying in white to be within the above range, the aerial image can be observed more clearly.

[0120] In addition, for the aerial imaging device 10 of this embodiment, the brightness measured when the entire surface of the display unit 1 is displayed in black is preferably 0.01 to 10 cd / m 2 , more preferably 0.05~5cd / m 2 , particularly preferably 0.10~1cd / m 2 , more preferably 0.15~0.50cd / m 2 , especially preferably 0.20~0.30cd / m 2 By setting the brightness when displaying in black to be within the above range, it is easy to improve the contrast and observe the aerial image more well.

[0121] The details of the method for measuring the brightness in the above-mentioned white display and black display are shown in the test examples described later.

[0122] Furthermore, for the aerial imaging device 10 of the present embodiment, the contrast ratio calculated based on the brightness when displayed in white and the brightness when displayed in black is preferably 1 to 10,000, more preferably 10 to 5,000, particularly preferably 20 to 1,000, further preferably 30 to 500, and particularly preferably 40 to 100. By making the contrast ratio within the above range, the aerial image can be recognized more well.

[0123] 7. Method for manufacturing aerial imaging device

[0124] The manufacturing method of the aerial imaging device 10 of the present embodiment is not particularly limited. For example, after the display unit 1, the light diffusion control unit 2, and the light-transmitting imaging unit 3 are prepared separately, the aerial imaging device 10 can be obtained by setting the display unit 1 at a predetermined position of the frame and setting a laminate of the light diffusion control unit 2 and the light-transmitting imaging unit 3.

[0125] 8. How to use the aerial imaging device

[0126] The aerial imaging device 10 of this embodiment can be used as a display device for displaying arbitrary images, videos, etc. in the air. The specific method of use is not limited, and it can be used in the same manner as a conventionally known display device.

[0127] In addition, in this specification, when it is recorded as "X to Y" (X, Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", and also includes the meaning of "preferably greater than X" or "preferably less than Y". In addition, when it is recorded as "X or more" (X is an arbitrary number), unless otherwise specified, it includes the meaning of "preferably greater than X", and when it is recorded as "Y or less" (Y is an arbitrary number), unless otherwise specified, it also includes the meaning of "preferably less than Y".

[0128] The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, the elements disclosed in the above embodiments are intended to include all design changes, equivalents, etc. that fall within the technical scope of the present invention.

[0129] Example

[0130] Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[0131] [Example 1]

[0132] 1. Preparation of the composition for the light diffusion control unit

[0133] To 40 parts by mass (solid content conversion value; the same below) of polyether urethane methacrylate having a weight average molecular weight of 9,900 as a low refractive index component, 60 parts by mass of o-phenylphenoxyethoxyethyl acrylate having a molecular weight of 268 as a high refractive index component and 8 parts by mass of 2-hydroxy-2-methyl-1-phenylpropane-1-one as a photopolymerization initiator were added, and the mixture was heated and mixed under the condition of 80° C. to obtain a composition for a light diffusion control unit, wherein the polyether urethane methacrylate was obtained by reacting polypropylene glycol, isophorone diisocyanate and 2-hydroxyethyl methacrylate.

[0134] Here, the weight average molecular weight (Mw) is a weight average molecular weight in terms of standard polystyrene measured under the following conditions using gel permeation chromatography (GPC) (GPC measurement).

[0135] <Measurement Conditions>

[0136] ·Measurement device: HLC-8320 manufactured by TOSOH CORPORATION

[0137] ·GPC columns (passed in the following order): manufactured by TOSOH CORPORATION

[0138] TSK gel superH-H

[0139] TSK gel superHM-H

[0140] TSK gel superH2000

[0141] · Determination solvent: tetrahydrofuran

[0142] ·Measurement temperature: 40℃

[0143] 2. Formation of the light diffusion control unit

[0144] The obtained composition for light diffusion control part was applied on the release surface of a release sheet (manufactured by LINTEC Corporation, product name "SP-PET381130", thickness: 38 μm) as a process sheet, in which one surface of a polyethylene terephthalate film was subjected to release treatment with a silicone release agent, to form a coating film. Thus, a laminate consisting of the coating film and the process sheet was obtained. Then, the release surface of a release sheet (manufactured by LINTEC Corporation, product name "SP-PET381130", thickness: 38 μm) in which one surface of a polyethylene terephthalate film was subjected to release treatment with a silicone release agent was laminated on the coating film side of the laminate, to obtain a laminate formed by laminating the process sheet, the coating film and the release sheet in this order.

[0145] Next, the obtained laminate is placed on a conveyor belt. At this time, the surface of the release sheet of the laminate is placed on the upper side, and the long side direction of the process sheet and the release sheet is parallel to the conveying direction of the conveyor belt. Next, an ultraviolet irradiation device (manufactured by EYE GRAPHICS COMPANY, product name "ECS-4011GX") is set on the conveyor belt on which the laminate is placed, and the ultraviolet irradiation device is provided with a linear high-pressure mercury lamp and a focusing cold light mirror. This device can irradiate the object with ultraviolet rays that are focused into a band shape (roughly linear). In addition, when the above-mentioned device is set, the above-mentioned ultraviolet irradiation device is set in a manner that the long side direction of the above-mentioned high-pressure mercury lamp is orthogonal to the conveying direction of the conveyor belt.

[0146] Furthermore, when observing from the long side direction of the high-pressure mercury lamp, the irradiation angle of ultraviolet rays irradiated to the laminate by the high-pressure mercury lamp was set to 5° when the normal line relative to the laminate surface was used as a reference. In addition, the irradiation angle here means that when the ultraviolet rays are irradiated to the downstream side of the conveyor belt, the acute angle formed by the normal line relative to the laminate surface and the ultraviolet rays is recorded with a positive sign, and when the ultraviolet rays are irradiated to the upstream side of the conveyor belt, the acute angle formed by the normal line relative to the laminate surface and the ultraviolet rays is recorded with a negative sign.

[0147] Thereafter, the conveyor belt was started to move the laminate at a speed of 1.0 m / min while the peak illuminance on the coating surface was 2.5 mW / cm 2 , the accumulated light intensity is 40.0mJ / cm 2 The coating film in the laminate is cured by irradiating ultraviolet rays through the release sheet under the conditions of (for convenience, this curing is sometimes referred to as "primary curing").

[0148] Next, the luminaire was moved at a speed of 1.0 m / min with a peak illuminance of 190 mW / cm 2 , the accumulated light intensity is 180mJ / cm 2 Under the conditions of , the coating film is irradiated with ultraviolet light (scattered light) through the release sheet, thereby curing the coating film in the laminate (for convenience, this curing is sometimes referred to as "secondary curing"). In addition, the above-mentioned peak illuminance and cumulative light amount are values ​​obtained by setting a UV illuminance meter (manufactured by EYE GRAPHICS COMPANY, product name "EYE Ultraviolet Integrated Illuminance Meter UVPF-A1") equipped with a light receiver at the position of the above-mentioned coating film and measuring.

[0149] The coating film was sufficiently cured by the primary curing and the secondary curing to form a light diffusion control layer. Thus, a laminated body was obtained in which the process sheet, the light diffusion control part having a thickness of 140 μm, and the release sheet were laminated in this order.

[0150] In addition, when a cross section of the formed light diffusion control portion was observed under a microscope, it was confirmed that Figure 2 As shown, a louver structure is formed in which a plurality of plate-like regions 201 are arranged in parallel at predetermined intervals inside the light diffusion control unit. The acute angle formed by the main surface of the louver structure and the normal line of the light diffusion control unit is 3.3°.

[0151] 3. Formation of aerial imaging device

[0152] The peeling sheet is peeled off from the laminated body obtained in the above manner, and the exposed surface of the light diffusion control part exposed thereby is stacked on one surface of a reverse transmission optical element (manufactured by Asukanet Co., Ltd., product name "ASKA3D-200NT", length 200mm×width 200mm×thickness 6.3mm) which is formed by stacking two layers with multiple reflective surfaces as a translucent imaging part.

[0153] Next, the obtained laminate of the light diffusion control part and the light-transmitting imaging part is placed on a predetermined frame in such a manner that the main surface of the laminate is horizontal and the surface of the light diffusion control part side faces downward. Furthermore, as a display part, a screen of a notebook computer is placed in the frame in such a manner that it faces the laminate of the light diffusion control part and the light-transmitting imaging part.

[0154] When the above display unit is set, Figure 4 As shown in (a) in FIG. 1 , the angle formed by the display surface of the display unit 1 and the main surface of the light diffusion control unit 2 is 45°. In addition, in the first direction (a direction perpendicular to the long side direction of the plate-shaped region and existing in the surface of the light diffusion control unit on the opposite side to the light-transmitting imaging unit), Figure 2 The display unit is set in such a way that the angle formed by the first direction (D1) and the second direction (a direction parallel to a plane perpendicular to the display surface and one surface of the light diffusion control unit, and existing in a surface of the light diffusion control unit on the opposite side of the transparent imaging unit) is 0°.

[0155] Furthermore, the frame shields the light emitted from the display unit so that the light does not escape to the outside from a portion other than the light diffusion control unit and the light-transmitting image forming unit.

[0156] Therefore, if Figure 4 As shown in (a) in FIG. 1 , an aerial imaging device 10 is obtained in which the light-transmitting imaging unit 3 , the light diffusion control unit 2 , and the display unit 1 are arranged in a frame.

[0157] [Example 2]

[0158] An aerial imaging device was obtained in the same manner as in Example 1 except that a commercially available light diffusion control film (manufactured by LINTEC Corporation, product name "WINCOS Z-2555") was used as the light diffusion control unit 2 and the angle formed by the first direction and the second direction was set to 90°. Figure 4 As shown in (a) in FIG. 1 , an aerial imaging device 10 is obtained in which the light-transmitting imaging unit 3 , the light diffusion control unit 2 , and the display unit 1 are arranged in a frame.

[0159] In addition, the above commercially available light diffusion control film is a laminate of two layers. Figure 2 The film is obtained by forming a layer of a louver structure with a plurality of plate-like regions 201 arranged in parallel at a predetermined interval. The two layers are stacked in such a way that the inclination directions of the louver structures are opposite. In addition, the angle of the acute angle formed by the main surface of the louver structure and the normal line of the light diffusion control part is -27° for one layer and +27° for the other layer.

[0160] [Example 3]

[0161] An aerial imaging device was obtained in the same manner as in Example 1, except that a reverse transmission optical element (manufactured by Parity Innovations Co. Ltd., product name "Parity Mirror", 300 mm in length × 300 mm in width × 2 mm in thickness) having a dihedral corner reflector array structure on a resin plate was used as the light-transmitting imaging portion, and a light diffusion control portion was stacked on the resin plate surface of the reverse transmission optical element that was not provided with a dihedral corner reflector array structure. Figure 4 As shown in (a) in FIG. 1 , an aerial imaging device 10 is obtained in which the light-transmitting imaging unit 3 , the light diffusion control unit 2 , and the display unit 1 are arranged in a frame.

[0162] [Comparative Example 1]

[0163] The aerial imaging device was obtained in the same manner as in Example 1 except that the light diffusion control unit was not used. Figure 4 As shown in (b) in the figure, an aerial imaging device is obtained in which the light-transmitting imaging unit 3 and the display unit 1 are arranged in a frame.

[0164] [Comparative Example 2]

[0165] The aerial imaging device was obtained in the same manner as in Example 1, except that the light diffusion control unit was not used and a display unit with a privacy film (manufactured by 3M, product name "PF12.1WH2") attached to the screen of a laptop computer was used. The privacy film shields specific light so that the effective viewing angle in the left and right directions is reduced to within 48°, and the privacy film controls the viewing angle in a direction orthogonal to the second direction (becomes Figure 4 The display unit is attached to the display unit in a manner perpendicular to the inner direction of the paper surface in (c). Figure 4 As shown in (c) in the figure, an aerial imaging device is obtained in which the light-transmitting imaging unit 3, the privacy film 6 and the display unit 1 are arranged in a frame.

[0166] [Comparative Example 3]

[0167] The aerial imaging device was obtained in the same manner as in Example 3 except that the light diffusion control unit was not used. Figure 4 As shown in (b) in the figure, an aerial imaging device is obtained in which the light-transmitting imaging unit 3 and the display unit 1 are arranged in a frame.

[0168] [Comparative Example 4]

[0169] An aerial imaging device was obtained in the same manner as in Example 3, except that the light diffusion control unit was not used and a display unit with a privacy film (manufactured by 3M, product name "PF12.1WH2") attached to the screen of a laptop computer was used. In addition, the privacy film was attached to the display unit in such a manner that the viewing angle control direction of the privacy film was orthogonal to the second direction. Figure 4 As shown in (c) in the figure, an aerial imaging device is obtained in which the light-transmitting imaging unit 3, the privacy film 6 and the display unit 1 are arranged in a frame.

[0170] [Test Example 1] (Confirmation of the Relationship of the Specified Angles of the Aerial Imaging Device)

[0171] (1) Determination of the incident angle range of light that forms an aerial image and light that forms a double image

[0172] In the same manner as in Comparative Example 1, an aerial imaging device was manufactured in which a light-transmitting imaging unit and a display unit were arranged in a frame (without a light diffusion control unit and a privacy film). For this aerial imaging device, an image of 70 mm in length and 100 mm in width was displayed on the display surface of the display unit. Thus, the generation of aerial images and double images was confirmed by naked eyes.

[0173] Here, the position (observation point) of the observer when confirming the above-mentioned aerial image is set as follows. First, assume a plane F that is perpendicular to the surface on the display side of the translucent imaging part and the display surface of the display part and passes through the center point of the translucent imaging part. Further, the width of the translucent imaging part in the cross section formed by cutting the translucent imaging part with the plane F is set to width W (specifically, 200 mm). In addition, a point that exists in plane F and satisfies the above-mentioned conditions A and B is used as the observation point. Among them, with respect to condition A, since the angle β of the manufactured aerial imaging device is 45°, the angle α is 45°. In addition, with respect to the magnification of condition B, 3.5 times is selected (that is, the distance between the observation point and the above-mentioned center point is set to a length 3.5 times the width W).

[0174] Next, based on the aerial images and double images confirmed by the naked eye, the area in the light-transmitting imaging unit through which the light forming these images among the light emitted by the display unit passes is determined. Figure 5 (a) shows a cross-sectional view of the light-transmitting imaging unit 3 and the display unit 1 viewed from the side (a cross-sectional view formed by cutting along the above-mentioned plane F). Figure 5 (b) shows that the light-transmitting imaging unit 3 and the display unit 1 are connected to Figure 5 The cross-sectional view is formed by cutting the plane represented by the symbol F' in (c). In addition, the plane represented by the symbol F' is a plane perpendicular to the above-mentioned plane F and one surface of the light-transmitting imaging part 3. Figure 5 The image shown in (a) in the figure is sometimes expressed as an image in the "front-back direction". Figure 5 In the case of the image shown in (b) in the figure, it is sometimes indicated as an image in the “left-right direction”.

[0175] In the above Figure 5 (a) and Figure 5 In (b) of FIG. 1 , the area indicated by "R" is the area where the real image is displayed in the display unit 1. In addition, the area indicated by "A" is the area through which the light forming the aerial image passes. In addition, the area indicated by "G" is the area through which the light forming the ghost image passes. In addition, when observing the cross section based on plane F', the ghost image would originally be symmetrically generated on the left and right sides of the aerial image, but since it is sufficient to discuss only one side, in Figure 5 In (b), only one side is displayed (only the ghost image on the right side is displayed).

[0176] Determine the light path of the light that forms the aerial image, which is irradiated from the end of region R and reaches the end of region A (at Figure 5 (a) and Figure 5Similarly, determine the optical path of the light that is illuminated by the end of region R and reaches the end of region G in the light that forms the ghost (in (b)). Figure 5 (a) and Figure 5 (a line segment connecting the ends of region R and region G in (b)).

[0177] Next, the acute angles formed by these line segments and the normal line of one surface of the light-transmitting imaging unit 3 are measured ( Figure 5 (a) and Figure 5 The results are shown in Table 1. In addition, the angles in Table 1 are Figure 5 (a) and Figure 5 In (b), based on the normal line, a minus sign is used to indicate an acute angle on the left side of the paper, and a plus sign is used to indicate an acute angle on the right side of the paper.

[0178] [Table 1]

[0179]

[0180] It can be seen from this that the light irradiated from any point on the display surface for forming an aerial image reaches the light-transmitting imaging section with an incident range of θau~θad in the front-back direction, and reaches the light-transmitting imaging section with an incident range of θar~θal in the left-right direction. In addition, the light irradiated from any point on the display surface for forming a double image reaches the light-transmitting imaging section with an incident range of θgu~θgd in the front-back direction, and reaches the light-transmitting imaging section with an incident range of θgr~θgl in the left-right direction.

[0181] (2) Determination of variable angle haze

[0182] The light diffusion control part used in Examples 1 and 2 was measured for haze value (%) using a variable angle haze meter (manufactured by Toyo Seiki Seisaku-sho, Ltd., product name: “Hydrometer Plate”).

[0183] Specifically, regarding Example 1, light was irradiated onto one surface of the light diffusion control portion while changing the incident angle relative to its normal line in the range of -90° to 0° along the front-back direction determined in the above step (1), and the haze value (%) was measured sequentially. The results are shown in Figure 6 (a) in .

[0184] In addition, regarding Example 2, light was irradiated onto one surface of the light diffusion control portion while changing the incident angle relative to its normal line in the range of -90° to 90° along the left-right direction determined in the above step (1), and the haze value (%) was measured sequentially. The results are shown in Figure 6 (b) in .

[0185] In addition, Figure 6 (a) and Figure 6 In (b) of FIG. 1 , the graph represented by a curve shows the change in haze value as the incident angle changes.

[0186] (3) Confirmation of the relationship between incident range and variable angle haze

[0187] The measurement results of the above step (2) are overlapped with the incident ranges of the light of the aerial image and the light of the double image determined in the above step (1). Figure 6 In (a), for the aerial imaging device of Example 1, the following are respectively indicated by the areas with diagonal lines: in the front and rear directions, the incident range θau~θad of the light forming the aerial image when it is incident on the light-transmitting imaging unit (and the light diffusion control unit), and the incident range θgu~θgd of the light forming the double image when it is incident on the light-transmitting imaging unit (and the light diffusion control unit). Figure 6 In (b), for the aerial imaging device of Example 2, the areas with slashes are respectively shown: in the left and right directions, the incident range θar~θal when the light forming the aerial image is incident on the light-transmitting imaging part (and the light diffusion control part), and the incident range θgr~θgl when the light forming the double image is incident on the light-transmitting imaging part (and the light diffusion control part).

[0188] For the aerial imaging device of Example 1, Figure 6 As shown in (a) in the figure, it can be seen that in the front-to-back direction, the light diffusion control unit has a sharp change in haze value with an incident angle of approximately -20° as a threshold. Moreover, the light diffusion control unit shows a low haze value (about 5%) in the incident range θau~θad of the aerial image, and a high haze value (about 80%) in the incident range θgu~θgd of the ghost image. That is, it can be seen that the light diffusion control unit of Example 1 can transmit the light forming the aerial image well in the front-to-back direction, and diffuse the light forming the ghost image.

[0189] For the aerial imaging device of Example 2, Figure 6As shown in (b) in the figure, it can be seen that in the left and right directions, the light diffusion control unit has a sharp change in haze value with the incident angle near -30° and 30° as the threshold. Moreover, the light diffusion control unit shows a low haze value (about 5%) in the incident range θar~θal of the aerial image, and a high haze value (about 80%) in the incident range θgr~θgl of the ghost. That is, it can be seen that the light diffusion control unit of Example 2 can well transmit the light forming the aerial image in the left and right directions, and diffuse the light forming the ghost.

[0190] [Test Example 2] (Reduction of ghosting and evaluation of brightness)

[0191] For the aerial imaging devices manufactured in Examples 1 and 3 and Comparative Examples 1 to 4, an aerial image was generated by displaying an image on a display unit, and observed with the naked eye while capturing a static image. The observation conditions were the same as those described in step (1) of Test Example 1.

[0192] The captured image is shown in Figure 7 . Figure 7 (a) is an image of Example 1, Figure 7 (b) is the image of Comparative Example 1. Figure 7 (c) is the image of Comparative Example 2. Figure 7 (d) is an image of Example 3. Figure 7 (e) is an image of Comparative Example 3. Figure 7 (f) in the figure is an image of Comparative Example 4. As can be seen from these images, for the aerial imaging devices of Comparative Examples 1 and 3, ghost images are obviously generated on the left and right sides of the aerial image, while for the aerial imaging devices of Examples 1 and 3 and Comparative Examples 2 and 4, the generation of ghost images is reduced to a level that is almost unobservable to the naked eye. In addition, the aerial imaging device manufactured in Example 2 was also observed with the naked eye under the same conditions, and it was confirmed that the generation of ghost images was reduced to a level that is almost unobservable to the naked eye.

[0193] Furthermore, for the purpose of confirming the brightness of the aerial image, the brightness (cd / m 2), and the contrast is calculated based on these values. Luminance meter LS-110 manufactured by KONICA MINOLTA was used for brightness measurement. In addition, for Examples 1 and 2 and Comparative Examples 1 and 2, the ambient illuminance was set to about 100 lx and the measurements were performed. On the other hand, for Example 3 and Comparative Examples 3 and 4, when the ambient illuminance was set to about 100 lx, periodic light and dark caused by surface reflection were easily generated, and accurate measurements could not be performed. Therefore, the ambient illuminance was set to about 20 lx and the measurements were performed (these ambient illuminances were measured by HIOKI LUX HiTESTER3423). The measurement results are shown in Table 2.

[0194] [Table 2]

[0195]

[0196] According to Table 2, the aerial imaging device of Comparative Example 1 has the highest brightness and the highest contrast in both cases of displaying in white and displaying in black. This is believed to be because the aerial imaging device does not have a light diffusion control unit or a privacy film. In addition, the aerial imaging device of Comparative Example 1 has obvious ghosting as described above.

[0197] On the other hand, when comparing the aerial imaging device of Example 1 having a light diffusion control unit with the aerial imaging device of Comparative Example 2 having a privacy film, it can be seen that the aerial imaging device of Example 1 has higher brightness and higher contrast in both cases of displaying in white and displaying in black. The same conclusion can be drawn when comparing the aerial imaging device of Example 3 having a light diffusion control unit with the aerial imaging device of Comparative Example 4 having a privacy film.

[0198] As can be seen from the above, the aerial imaging device of Example 1 can effectively reduce the occurrence of ghosting while fully maintaining the brightness of the display.

[0199] Industrial Applicability

[0200] The aerial imaging device of the present invention can be suitably used as a display for displaying aerial images, etc.

[0201] Description of Reference Numerals

[0202] 10: aerial imaging device; 1: display unit; 2: light diffusion control unit; 201: plate-shaped area; 202: area with relatively low refractive index; 3: light-transmitting imaging unit; 4: aerial image observation surface; 5: observation point; 6: privacy film.

Claims

1. An aerial imaging device, characterized in that: have: A display unit having a display surface and emitting light from the display surface; a light diffusion control unit disposed on the display surface side of the display unit and causing the light to diffuse or transmit according to its incident angle; and a light-transmitting imaging portion which is stacked on the surface side of the light diffusion control portion opposite to the display portion and transmits the light passing through the light diffusion control portion to form an image at a position on the surface side opposite to the light diffusion control portion, The light diffusion control portion has a louver-like regular internal structure including a plurality of plate-like regions with a relatively high refractive index in a region with a relatively low refractive index.

2. The aerial imaging device according to claim 1, characterized in that: The display section is arranged with respect to the light diffusion control section and the light-transmitting imaging section so that the display surface is not parallel to a surface of the light diffusion control section that is opposite to the light-transmitting imaging section.

3. The aerial imaging device according to claim 2, characterized in that: In the case where a direction perpendicular to the long side direction of the plate-shaped region and existing in a plane of the light diffusion control unit on the opposite side to the light-transmitting imaging unit is set as a first direction, and a direction parallel to a plane perpendicular to both the display surface and one surface of the light diffusion control unit and existing in a plane of the light diffusion control unit on the opposite side to the light-transmitting imaging unit is set as a second direction, The acute angle formed by the first direction and the second direction is greater than or equal to 0° and less than or equal to 90°.

4. The aerial imaging device according to claim 1, characterized in that: When a direction perpendicular to the long side direction of the plate-shaped region and existing in a plane of the light diffusion control portion on the opposite side to the light-transmitting imaging portion is defined as a first direction, Each of the plate-shaped regions is inclined toward the first direction in the light diffusion control portion.

5. The aerial imaging device according to claim 4, characterized in that: The angle of inclination of the plate-shaped region is not less than 0° and not more than 30° with respect to the thickness direction of the light diffusion control portion.

6. The aerial imaging device according to claim 1, characterized in that: The light-transmitting imaging unit includes a reverse-transmission optical element for reversely transmitting incident light.

7. The aerial imaging device according to claim 6, characterized in that: The reverse transmission optical element is an element formed by laminating two layers having a plurality of reflection surfaces. In each of the two layers, the plurality of reflection surfaces are arranged perpendicular to one surface of the reverse transmission optical element and spaced apart from each other by a predetermined interval. The two layers are stacked such that the reflection surface of one of the two layers is orthogonal to the reflection surface of the other layer.

8. The aerial imaging device according to claim 7, characterized in that: Assuming that a plane F is perpendicular to the surface of the light-transmitting imaging portion opposite to the light diffusion control portion and the display surface and passes through the center point of the light-transmitting imaging portion, and the width of the light-transmitting imaging portion in a cross section formed by cutting the light-transmitting imaging portion with the plane F is set to width W, When the aerial imaging device is observed from an observation point existing in the plane F and satisfying the following two conditions, condition A and condition B, The light diffusion control unit has a haze value of 60% or less for light reflected in the two layers constituting the reverse transmission optical element among the light irradiated from any point of the display unit and reaching the observation point, The light diffusion control unit has a haze value of 60% or more for light reflected only in one of the two layers constituting the reverse transmission optical element, among the light irradiated from any point of the display unit and reaching the observation point. Condition A: When the angle formed by the line segment connecting the observation point and the center point and the surface of the light-transmitting imaging portion on the opposite side to the light diffusion control portion is set as angle α, and the angle formed by the plane including the display surface of the display portion and the plane including the surface of the light-transmitting imaging portion on the opposite side to the light diffusion control portion is set as angle β, the total of the angle α and the angle β is 90°, Condition B: The distance between the observation point and the center point is 3.5 times the width W.

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