Projection device and cover for projection device

Abstract

To provide a projection device capable of suppressing luminance unevenness of a display image and generation of double images even for incident light having a wide distribution of incident angles.SOLUTION: A housing-shaped projection device 100 according to the present invention includes at least a light source 2, a display element 3, a mirror 4, and a cover 1 for a projection device. The cover 1 for the projection device is provided at an opening from which projection light TL is emitted from the projection device 100, and is characterized such that a luminous reflectance for light incident at an incident angle of 30-55° on at least one surface thereof is 6% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a projection device and a cover for the projection device that can suppress uneven brightness of a displayed image and the occurrence of double images. [Background technology]

[0002] In recent years, many head-up display devices for vehicles have been developed that display images on semi-transparent plates such as the windshield or combiner of a vehicle (hereinafter collectively referred to as "display surface"). A head-up display device for vehicles is an image display device that is disposed, for example, on the dashboard of a vehicle and projects image light onto the windshield to display driving information as a virtual image. Because the driver can simultaneously view the virtual image and the scenery through the windshield, this has the advantage of requiring less eye movement compared to conventional display devices such as liquid crystal displays that are installed outside the range of the windshield.

[0003] Another type of projection device that is different from the head-up display device is a projector, which is a device that can magnify and display light from a display element through an optical system such as a lens. In such a projection device, components such as a light source, a display element, a mirror, and a lens are generally housed in a single housing.

[0004] In the case of the projection device described above, a transparent cover member (hereinafter referred to as a "projection device cover") is generally provided at the opening through which the projection light is emitted from the housing in order to prevent impurities from entering the housing and to protect the components inside the housing. However, this projection device cover has the problem that light is reflected from its surface, and this reflected light may enter the driver's eyes or reduce the visibility of the displayed image.

[0005] One technique for solving these problems is to bend the projection device cover at a predetermined curvature. For example, Patent Document 1 discloses a virtual image display device that uses reflection of display light at a projection unit to display a visible virtual image, and discloses a technology that suppresses diffusion of reflected light and improves visibility by curving the opening cover along a parabola so that it is recessed toward the incident side of the display light on both sides separated by the opening. Furthermore, Patent Document 2 discloses a projector that includes a projection unit that projects projection light toward an illuminated surface, a housing that houses the projection unit and has an opening formed therein for emitting the projection light to the outside, and a cover unit that is provided in the opening and allows the projection light to pass through, and that includes a technology for bending the peripheral portion of the cover unit toward the incident side of the projection light in order to reduce the reflectance of the projection light at the incident surface of the cover unit.

[0006] However, the above-mentioned projection device cover has problems such as uneven brightness of the displayed image due to the fact that the light is more likely to be reflected on the surface when the incident angle of light is large, and double images are likely to occur due to the double reflection on the front and back surfaces of the cover. These problems become more pronounced when the projection device cover is bent, and therefore improvements to these problems have been desired.

[0007] Therefore, in order to suppress the occurrence of the above-mentioned uneven brightness of the displayed image and double images, a technique has been developed in which a specific anti-reflection layer is provided on the cover for the projection device. For example, Patent Document 3 discloses a technology for suppressing double images caused by reflections on the front and back surfaces of a cover for a projection device by forming a reflective film having a multilayer film or a moth-eye structure on the cover. Furthermore, Patent Document 4 discloses a technology for suppressing double images caused by reflections on the front and back surfaces of a cover for a projection device by forming a reflective film with a moth-eye structure on the inside of the cover.

[0008] Furthermore, another technique for solving the above problem is to adjust the rolling direction of the resin material that constitutes the projection apparatus cover. For example, Patent Document 5 discloses a cover for a head-up display that is formed to have an approximately wedge-shaped cross section in which the optical path that transmits and emits object point light from an arbitrary object point in the display source, among the display light, coincides with the reflection-side optical path that transmits and emits reflected object point light that is incident from the object point and internally reflected. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2019-98923 [Patent Document 2] Patent No. 5544711 [Patent Document 3] U.S. Patent No. 10,302,937 [Patent Document 4] Patent No. 5080763 [Patent Document 5] Patent No. 6665943 Summary of the Invention [Problem to be solved by the invention]

[0010] The technologies of Patent Documents 3 to 5 can all suppress uneven brightness and double images in the displayed image to some extent. However, in recent years, with the demand for smaller devices and larger display areas, the distribution of the angle of incidence of light incident on the projection device cover has widened, which is thought to make the above-mentioned uneven brightness and double images in the displayed image more likely to occur, and there has been a demand for the development of a technology that can more reliably suppress these occurrences.

[0011] The present invention has been made in consideration of the above circumstances, and aims to provide a projection device and a cover for a projection device that can suppress uneven brightness in the displayed image and the occurrence of double images, even for incident light with a wide distribution of incident angles.

[0012] The present inventors have conducted extensive research to solve the above-mentioned problems regarding a housing-shaped projection device that includes at least a light source, a display element, a mirror, and a projection device cover, and as a result, have noticed that the above-mentioned brightness unevenness and double images in the displayed image are more likely to occur when the angle of incidence of light incident from the light source is large. After further extensive research, they have found that by providing a projection device cover at an opening through which projection light is emitted from the projection device and suppressing the reflectance of light incident at a large angle of incidence (30 to 55°) on at least one surface of the cover to 6% or less, it is possible to more reliably suppress the brightness unevenness and double images in the displayed image than with conventional techniques, even when the distribution of incident angles is wide.

[0013] The present invention has been made based on the above findings, and the gist of the present invention is as follows. (1) A housing-shaped projection device including at least a light source, a display element, a mirror, and a projection device cover, The cover for the projection device is provided at an opening through which projection light is emitted from the projection device, and the luminous reflectance of at least one surface of the cover for the projection device for light incident at an incident angle of 30 to 55° is 6% or less. (2) The projection device according to (1) above, characterized in that the luminous reflectance of at least one surface of the projection device cover for light incident at an incident angle of 5° is 3% or less. (3) The projection device according to (1) or (2) above, characterized in that the luminous reflectance of at least one surface of the projection device cover for S-polarized light incident at an incident angle of 30 to 55° is 10% or less. (4) The projection device according to any one of (1) to (3) above, wherein the thickness of the projection device cover is 0.1 mm or more. (5) The projection device according to any one of (1) to (4) above, wherein the projection device cover has a curved surface with a radius of curvature of 500 mm or less. (6) The projection device according to any one of (1) to (5) above, wherein the projection device cover contains a polycarbonate resin, an acrylic resin, or an acetyl cellulose resin. (7) The projection device cover has a projection device cover body and an anti-reflection layer formed on the projection device cover body, The projection device described in any one of (1) to (6) above, characterized in that the anti-reflection layer is formed on the projection device cover body via an adhesive layer, or the anti-reflection layer is formed directly on the projection device cover body. (8) The projection device according to any one of (1) to (7) above, characterized in that the projection device is a head-up display or a projector. (9) A cover for a projection device provided at an opening through which projection light is emitted in a housing-shaped projection device, The cover for a projection device is characterized in that the luminous reflectance of at least one surface of the cover for a projection device for light incident at an incident angle of 30 to 55° is 6% or less. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a projection device and a cover for the projection device that can suppress uneven brightness of a displayed image and the occurrence of double images even for incident light with a wide distribution of incident angles. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view schematically illustrating an embodiment of a projection device of the present invention. [Figure 2] 1 is an enlarged cross-sectional view schematically illustrating a portion of an embodiment of a projection device of the present invention. [Figure 3] 1 is a cross-sectional view schematically showing a fine uneven structure formed on a cover for a projection apparatus according to the present invention. [Figure 4] FIG. 10 is an enlarged cross-sectional view schematically illustrating a part of the cover for the projection device for explaining a double image. [Figure 5] (a) is a graph showing the relationship between the incident angle of light (unpolarized) and luminous reflectance for each model of projection device cover in the examples, and (b) is a graph showing the relationship between the incident angle of light (S-polarized) and luminous reflectance for each model of projection device cover in the examples. [Figure 6] (a) is a graph showing the relationship between the angle of incidence of light (unpolarized) for each model of projection device cover and 5° and 55° in the examples, and (b) is a graph showing the relationship between the angle of incidence of light (S-polarized) for each model of projection device cover and double image intensity in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the projection device and projection device cover of the present invention will be specifically described with reference to the drawings as necessary. Note that for the sake of convenience of explanation, some of the components disclosed in Figures 1 to 4 are shown schematically at a scale and in a shape different from the actual ones.

[0017] <Projection device> First, an embodiment of the projection device of the present invention will be described. As shown in FIG. 1, the projection device of the present invention is a housing-like projection device 100 that includes at least a light source 2, a display element 3, a mirror 4, and a projection device cover 1. The projection device 100 being casing-shaped means that each component is installed inside a predetermined housing 11. The shape of the housing 11 is not particularly limited, and can be selected appropriately depending on the type of projection device 100 and the required performance.

[0018] Here, the projection device is a device that displays an image (display image DI in FIG. 1) such as a still image or a moving image by projecting a virtual image or a real image onto a projection plate (display surface 5 in FIG. 1). The type of the projection device is not particularly limited, and examples thereof include a head-up display or a projector (not shown) as shown in Fig. 1. The configuration of the projection device 100 will be described below with reference to drawings (Figs. 1 and 2) showing a head-up display, which is one embodiment of the projection device 100 of the present invention.

[0019] As shown in FIG. 1, the projection device 100 of the present invention is characterized in that the cover 1 for the projection device is provided at an opening through which the projection light TL is emitted from the projection device 100, and that the luminous reflectance of at least one surface thereof for light incident at an incident angle of 30 to 55° is 6% or less. Brightness unevenness and double images in a display image caused by light entering the projection device cover 1 tend to occur more easily when the angle of incidence θ of light incident from the light source 2 is large. Therefore, in the present invention, by keeping the reflectance of light incident at a high angle of incidence (30 to 55°), which causes brightness unevenness and double images in a display image DI, low (to 6% or less) on at least one surface (1B and 1A in FIG. 1) of the projection device cover 1, it is possible to effectively suppress brightness unevenness and double images in a display image DI even when the distribution of the angle of incidence of incident light is wide.

[0020] On the other hand, projection devices using conventional projection device covers are not controlled to reduce the reflectance for incident light at high angles of incidence, and are therefore considered to be less effective at suppressing uneven brightness in the displayed image and the occurrence of double images than the projection device 100 of the present invention. FIG. 4 is a schematic diagram illustrating the process by which a double image is generated due to reflected light when light (incident light IL) is incident on the projection device cover 1. When the incident light IL enters the projection device cover 1, most of the light is transmitted through the projection device cover 1, but is reflected by the projection device cover 1's incident surface 1A (generating reflected light RL0). Most of the light that passes through the projection device cover 1's incident surface 1A passes through the projection device cover 1's exit surface 1B and is emitted as output light OL (projected light). However, a portion of the light is reflected by the projection device cover 1's exit surface 1B, generating internally reflected light RL1. This internally reflected light RL1 is then further reflected by the projection device cover 1's incident surface 1A, generating internally reflected light RL2. This internally reflected light RL2 passes through the projection device cover 1's exit surface 1B, generating output light (output light GL) separate from the output light OL. This output light GL forms a secondary image, resulting in a double image.

[0021] The components of one embodiment of the projection device 100 of the present invention will be described below. (Projector cover) As shown in FIG. 1, the projection device 100 of the present invention includes a projection device cover 1 provided at an opening of the housing of the projection device 100. As shown in FIG. The projection device cover 1 may be disposed at an opening of the housing of the projection device 100, and a coating such as a protective film may be applied to the projection device cover 1. However, from the viewpoint of more reliably suppressing uneven brightness of the displayed image and the occurrence of double images, it is preferable that the projection device cover 1 be disposed on the outermost side of the housing of the projection device 100 (in the direction in which the emitted light is emitted from the housing).

[0022] As described above, by setting the luminous reflectance of at least one surface of the projection device cover 1 to 6% or less for light incident at an incident angle of 30 to 55°, it is possible to prevent uneven brightness of the displayed image and the occurrence of double images even when the distribution of the incident angle θ of the light incident from the light source 2 is wide and the incident angle θ is large (such that the maximum incident angle θ is approximately 55°). From the same viewpoint, the luminous reflectance of the light incident at an incident angle of 30 to 55° (θ: 30 to 55°) is preferably 3% or less, and more preferably 2% or less. The projection device cover 1 has a "luminous reflectance of 6% or less for light incident at an incident angle of 30 to 55°" meaning that the luminous reflectance is 6% or less for all incident light in the range of incident angles θ of 30 to 55°. Here, the luminous reflectance of the cover 1 for the projection device can be obtained from the tristimulus value Y calculated in accordance with JIS Z 8722:2009 from the reflectance spectrum measured using a commercially available spectrophotometer (for example, V-650 manufactured by JASCO Corporation).

[0023] The luminous reflectance of the projection device cover 1 described above for light with an incident angle of 30 to 55° needs to be 6% or less on at least one side of the projection device cover 1, and may be on either side of the projection device cover 1. However, from the viewpoint of more effectively suppressing uneven brightness of the displayed image and the occurrence of double images, it is preferable that the side of the projection device cover 1 whose luminous reflectance is controlled to 6% or less be the incident side of the light from the light source 2. From the same viewpoint, it is more preferable that the luminous reflectance on both sides of the cover 1 for a projection apparatus is 6% or less.

[0024] As described above, the luminous reflectance of the projection device cover 1 must be 6% or less for light with an incident angle of 30 to 55°, but it is preferable that the luminous reflectance of the projection device cover 1 be 3% or less for light incident at an incident angle of 5°. Even when the incident angle θ is small, better anti-reflection performance can be obtained, so that uneven brightness of the displayed image and the occurrence of double images can be suppressed even for light with a wider range of incident angles. From the same viewpoint, the luminous reflectance of the projection apparatus cover 1 on both surfaces for light incident at an angle of incidence of 5° is more preferably 2% or less, and even more preferably 1% or less.

[0025] Furthermore, it is preferable that the cover 1 for the projection device has excellent transmissive anti-reflection performance even when the incident light is polarized. Specifically, the luminous reflectance of at least one surface of the cover 1 for the projection device for S-polarized light incident at an incident angle of 30 to 55° is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less. Note that the projection device cover 1's "luminous reflectance of 6% or less for S-polarized light incident at an incident angle of 30 to 55°" means that the luminous reflectance of the projection device cover 1 is 6% or less for all S-polarized incident light with an incident angle θ in the range of 30 to 55°. Here, the luminous reflectance of the cover 1 for the projection device can be obtained from the tristimulus value Y calculated in accordance with JIS Z 8722:2009 from the reflectance spectrum measured using a commercially available spectrophotometer (for example, V-650 manufactured by JASCO Corporation), just like with unpolarized incident light.

[0026] The cover 1 for the projection device is not particularly limited as long as it is transparent and at least one side has the above-mentioned visual reflectance (visual reflectance of 6% or less for light with an incident angle of 30 to 55°), and other configurations can be selected appropriately depending on the required performance.

[0027] Examples of materials for the projection apparatus cover 1 include thermoplastic resins such as polycarbonate (PC), acrylic resin (PMMA), acetyl cellulose (TAC), polyester (PEs), polyphenylene sulfide (PPS), polypropylene (PP), and polyvinyl chloride (PVC), as well as glass, etc. Among these, it is preferable to use polycarbonate, acrylic resin, or acetyl cellulose resin, as these have excellent transparency while ensuring the strength required for the cover member.

[0028] Furthermore, there is no particular limitation on the thickness of the projection device cover 1, and it can be appropriately selected depending on the required performance. For example, from the viewpoint of ensuring the strength of the cover while significantly exhibiting the effect of suppressing uneven brightness of the displayed image and the occurrence of double images according to the present invention, the thickness of the projection device cover 1 is preferably 0.1 mm or more, more preferably 0.3 mm or more, and even more preferably 0.5 mm or more. The thickness of the projection device cover 1 must be 0.1 mm or more at all points, and if the thickness of the projection device cover 1 varies in parts, the thickness of the thinnest part of the projection device cover 1 must be 0.1 mm or more.

[0029] Furthermore, the shape of the projection device cover 1 is not particularly limited and can be determined appropriately depending on the required dimensions and performance. For example, as shown in Fig. 1, the projection device cover 1 can be flat, or as shown in Fig. 2, the projection device cover 1 can be a plate-like shape having a curved surface. When the projection device cover 1 has a curved surface, the shape of the curved surface is not particularly limited, and examples thereof include a spherical surface, an ellipsoidal surface, a two-leaf hyperboloid, an elliptical paraboloid, and a randomly curved surface, and the number of curved surfaces is also not limited. Among these, from the viewpoint of being able to significantly exert the effect of suppressing uneven brightness and double images in the display image according to the present invention, it is preferable that the projection device cover 1 has a curved surface, and more preferably a curved surface with a curvature radius of 500 mm or less. The occurrence of uneven brightness and double images in the display image tends to increase when the projection device cover 1 has a curved surface, and the suppression effect according to the present invention can be more significantly confirmed.

[0030] Here, the method for realizing the above-mentioned luminous reflectance in the projection apparatus cover 1 is not particularly limited, and it can be appropriately set within a desired range by controlling the manufacturing conditions using a known method. For example, an antireflection structure such as a dielectric film, a multilayer antireflection film (multilayer AR), a fine uneven structure (moth-eye structure), etc. can be formed on the projection apparatus cover 1. Among these antireflection structures, it is preferable to form a fine uneven structure from the viewpoints of high antireflection performance and ease of control of the luminous reflectance described above.

[0031] For example, when a dielectric film is used as the antireflection structure, the luminous reflectance can be adjusted by adjusting the film composition and film thickness of the dielectric. Furthermore, when a multilayer antireflection film is used as the antireflection structure, the luminous reflectance can be adjusted by adjusting the film composition and film thickness of each layer constituting the multilayer film. Furthermore, when a fine concavo-convex structure is used as the antireflection structure, the luminous reflectance can be adjusted by controlling the height of the concaves and convexes of the fine concavo-convex structure and the spacing between the concaves and convexes.

[0032] When the dielectric film or the multilayer antireflection film is used as the antireflection structure, the dielectric material constituting the film or multilayer antireflection film may be, for example, TiO2, Ta2O5, Al2O3, SiO2, or MgF2. The thickness of the dielectric film and the thickness of the films constituting the multilayer antireflection film are not particularly limited, and can be set appropriately depending on the above-mentioned luminous reflectance and required performance.

[0033] Furthermore, when forming the dielectric film or multilayer anti-reflection film on the projection device cover 1, it is also possible to form an adhesive layer between the projection device cover body and the dielectric film or multilayer anti-reflection film in order to improve adhesion. In addition, when the antireflection layer has adhesive properties, the dielectric film or the multilayer antireflection film can be provided directly on the projection apparatus cover body without providing the adhesive layer.

[0034] When a fine uneven structure is used as the anti-reflection structure, examples include a structure in which a fine uneven layer 20 having a fine uneven structure (so-called moth-eye structure) on the surface is formed on at least one side of the projection device cover body 10, as shown in Figure 3, and a structure in which a fine uneven structure is formed directly on the surface of the projection device cover body 10 by sputtering or etching, although not shown.

[0035] The arrangement of the projections and recesses in the fine projection and recess structure is not particularly limited. For example, the projections and recesses can be arranged in a hexagonal lattice pattern or a square lattice pattern, or they can be arranged randomly. The shape of the projections 21 in the fine projection and recess structure is also not particularly limited as long as the desired optical properties can be obtained, and may be bullet-shaped, cone-shaped, columnar, needle-shaped, or the like. The shape of the recesses refers to the shape formed by the inner walls of the projections 21.

[0036] The average height H of the fine unevenness (depth of the recesses) is an important condition for obtaining excellent anti-reflection performance. Specifically, the average height H of the fine unevenness is 150 It is preferable that the average height H of the fine irregularities is 190 to 300 nm, and more preferably 190 to 230 nm. This is because the distribution of the incident angle θ of the light incident from the light source 2 is wide, and even when the incident angle θ is large (up to about 55°), it is possible to suppress uneven brightness of the displayed image and the occurrence of double images. From the same viewpoint, the average irregularity height H of the fine irregularities is more preferably 190 to 300 nm, and further preferably 190 to 230 nm. Furthermore, the average height H of the fine uneven structure is preferably 300 nm or less from the viewpoint of releasability from the mold.

[0037] The unevenness height H of the fine uneven structure is the distance from the bottom of the recess to the apex of the protrusion 21, as shown in Figure 3, and the average unevenness height can be obtained by measuring the unevenness height H at several locations (for example, five locations) and calculating the average. Furthermore, the conditions of the support portion 22 where the fine uneven structure of the fine uneven layer 20 is not formed are not particularly limited, but considering that when the linear expansion coefficients of the resin and the substrate are different, there is a concern that problems may occur in adhesion and the like if the thickness is too thick in terms of long-term reliability, etc., it is preferable that the thickness be approximately 10 to 9000 nm.

[0038] Furthermore, it is preferable that the fine uneven structure has an uneven period (uneven pitch) P that is equal to or less than the wavelength of visible light (for example, 830 nm or less). It is preferably 400 nm or less, and more preferably 250 nm or less. When the fine structure is aligned, if the uneven pitch is large, there is a concern that reflected and diffracted light due to the structure arrangement may occur depending on the angle of incident light, affecting imaging quality. The concave-convex period P of the fine concave-convex structure is the arithmetic mean value of the distances between adjacent convex portions and between adjacent concave portions. The concave-convex period P of the fine concave-convex structure can be obtained by cross-sectional observation using, for example, a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Furthermore, a method for deriving the arithmetic mean value of the distance between adjacent convex portions and concave portions includes, for example, picking out multiple combinations of adjacent convex portions and / or multiple combinations of adjacent concave portions, measuring the distance between the convex portions and the distance between the concave portions that make up each combination, and averaging the measured values. The concave-convex period P of the fine concave-convex structure may be the same or different, as shown in Fig. 3. However, even if the concave-convex period P of the fine concave-convex structure is different on each surface, it is preferable that the concave-convex period is equal to or less than the wavelength of visible light.

[0039] When the fine unevenness layer 20 is formed on the projection device cover 1, there are no particular limitations on the material that constitutes the fine unevenness layer 20. For example, from the viewpoint of formability of the fine unevenness layer 20, it is possible to use a resin composition that hardens by a curing reaction, such as an active energy ray-curable resin composition (a photocurable resin composition, an electron beam-curable resin composition) or a thermosetting resin composition, which contains, for example, a polymerizable compound and a polymerization initiator.

[0040] Examples of polymerizable compounds that can be used include (i) esters obtained by reacting 1 mole of polyhydric alcohol with 2 moles or more of (meth)acrylic acid or a derivative thereof, and (ii) esters obtained from a polyhydric alcohol, a polycarboxylic acid or anhydride thereof, and (meth)acrylic acid or a derivative thereof. Examples of (i) include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, tetrahydrofurfuryl acrylate, glycerin tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, acryloyl monophorin, and urethane acrylate. Examples of the above (ii) include esters obtained by reacting a polyhydric alcohol such as trimethylolethane, trimethylolpropane, glycerin, or pentaerythritol with a polycarboxylic acid or anhydride thereof selected from malonic acid, succinic acid, adipic acid, glutaric acid, sebacic acid, fumaric acid, itaconic acid, or maleic anhydride, and (meth)acrylic acid or a derivative thereof. These polymerizable compounds may be used alone or in combination of two or more.

[0041] Furthermore, when the resin composition is photocurable, examples of the photopolymerization initiator include carbonyl compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzil, benzophenone, p-methoxybenzophenone, 2,2-diethoxyacetophenone, α,α-dimethoxy-α-phenylacetophenone, methylphenyl glyoxylate, ethylphenyl glyoxylate, 4,4'-bis(dimethylamino)benzophenone, 1-hydroxycyclohexylphenyl ketone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and benzoyldiethoxyphosphine oxide; and the like, and one or more of these can be used.

[0042] In the case of electron beam curing, examples of the electron beam polymerization initiator include thioxanthones such as benzophenone, 4,4-bis(diethylamino)benzophenone, 2,4,6-trimethylbenzophenone, methyl orthobenzoylbenzoate, 4-phenylbenzophenone, t-butylanthraquinone, 2-ethylanthraquinone, 2,4-diethylthioxanthone, isopropylthioxanthone, and 2,4-dichlorothioxanthone; diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyl dimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one, and the like. acetophenones such as 1-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone; benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; methylbenzoyl formate, 1,7-bisacridinylheptane, and 9-phenylacridine, and one or more of these can be used.

[0043] In the case of thermosetting resins, examples of the thermal polymerization initiator include organic peroxides such as methyl ethyl ketone peroxide, benzoyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyoctoate, t-butyl peroxybenzoate, and lauroyl peroxide; azo compounds such as azobisisobutyronitrile; and redox polymerization initiators obtained by combining the organic peroxides with amines such as N,N-dimethylaniline and N,N-dimethyl-p-toluidine.

[0044] These photopolymerization initiators, electron beam polymerization initiators and thermal polymerization initiators may be used alone or in any desired combination. The amount of polymerization initiator is preferably 0.01 to 10 parts by mass per 100 parts by mass of the polymerizable compound, because within this range, curing proceeds sufficiently, the molecular weight of the cured product becomes appropriate, sufficient strength is obtained, and problems such as discoloration of the cured product due to polymerization initiator residues, etc., do not occur. Furthermore, the resin composition may contain, as necessary, a non-reactive polymer or an active energy ray sol-gel reactive component, and may also contain various additives such as a thickener, a leveling agent, an ultraviolet absorber, a light stabilizer, a heat stabilizer, a solvent, and an inorganic filler.

[0045] The material constituting the projection apparatus cover main body 10 is the same as the material constituting the projection apparatus cover 1 described above.

[0046] In addition, when forming the fine uneven layer 20 on the projection device cover 1, it is also possible to form an adhesive layer (not shown) between the projection device cover main body 10 and the fine uneven layer 20 in order to improve adhesion. The material for the adhesive layer is not particularly limited, and an optimum material can be selected depending on the combination of resins used for the projection apparatus cover body 10 and the fine uneven layer 20. For example, a coating agent containing a general silane coupling agent, an ultraviolet curable resin, a thermosetting resin, a solvent, etc. can be used. In addition, when the fine concave-convex layer 20 has adhesive properties, the fine concave-convex layer 20 can be provided directly on the projection apparatus cover body 10 without providing the adhesive layer.

[0047] (light source) Furthermore, the projection device 100 of the present invention includes a light source 2 inside the housing of the projection device 100, as shown in FIG. There are no particular limitations on the light source 2, and it is sufficient to appropriately select a light source that is normally used in a projection device, such as a laser light source, an LED light source, or a mercury lamp.

[0048] (display element) Furthermore, the projection device 100 of the present invention includes a display element 3 inside the housing of the projection device 100, as shown in FIG. The display element 3 is an element for displaying a projection image, and can be appropriately selected depending on the type and required performance of the projection device 100. For example, various liquid crystal display elements, digital mirror devices, etc. can be used.

[0049] (mirror) Furthermore, the projection device 100 of the present invention includes a mirror 4 inside the housing of the projection device 100, as shown in FIG. The mirror 4 is a member for magnifying and reflecting the light from the light source. The type and number of mirrors are not particularly limited, and it may be composed of one mirror 4 as shown in Figure 1, or two mirrors 4', 4'' as shown in Figure 2, or more mirrors may be provided as needed.

[0050] (Other materials) Furthermore, the projection device 100 of the present invention can further include members (other members) other than the projection device cover 1, light source 2, and mirror 4 described above, depending on the type of product and the required performance. 1, a polarizing element 6 may be further provided in the housing of the projection device 100. In addition to the polarizing element 6, other components may be incorporated into the projection device 100 as needed.

[0051] <Projection device cover> Next, an embodiment of the projection apparatus cover of the present invention will be described. As shown in FIG. 1, the projection device cover 1 of the present invention is a projection device cover 1 provided at an opening through which projection light TL is emitted in a housing-shaped projection device 100, The cover 1 for a projection apparatus is characterized in that at least one surface thereof has a luminous reflectance of 6% or less for light with a wavelength of 550 nm incident at an incident angle of 30 to 55° (θ: 30 to 55°). By keeping the reflectance of light incident at a large angle of incidence (30 to 55°) low (to 6% or less), uneven brightness in the displayed image and the occurrence of double images can be effectively suppressed, even when the distribution of incident angles is wide and light is incident at a high angle of incidence.

[0052] The configuration of the projection apparatus cover of the present invention is the same as that of the projection apparatus cover 1 described in the projection apparatus 100 of the present invention. [Example]

[0053] The present invention will be specifically described based on examples, but the present invention is not limited to the following examples.

[0054] <Projector cover model> Models of projection device covers according to the present invention and comparative examples were produced as follows.

[0055] (Example 1 of the present invention) As shown in FIG. 3, a projection device cover according to Example 1 of the present invention was prepared by forming a projection device cover body 10 made of a 0.4 mm thick flat polycarbonate resin on a 5 μm thick UV-curable acrylic resin, and forming a fine uneven surface layer 20 (the unevenness height H of the fine uneven surface was 250 nm, the unevenness formation pitch P was 200 to 230 nm, and the uneven surface was arranged in a hexagonal lattice pattern) on the surface of the projection device cover body 10. The UV-curable acrylic resin is a resin composition containing 45% by mass of a monomer ("Aronix (registered trademark) M305" manufactured by Toagosei Co., Ltd.), 20% by mass of an oligomer ("UV-1700" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 5% by mass of a reactive diluent ("DMAA (registered trademark)" manufactured by KJ Chemicals Corporation) and a photopolymerization initiator ("Irgacure 184" manufactured by IGM Resins BV), which is cured by ultraviolet irradiation.

[0056] (Comparative Example 1) As a cover for a projection device in Comparative Example 1, a flat glass plate ("S9112" slide glass, manufactured by Matsunami Glass Industry Co., Ltd.) having a thickness of 1.3 mm was prepared.

[0057] (Example 2 of the present invention) As a projection apparatus cover of Example 2 of the present invention, a projection apparatus cover body made of a 0.4 mm thick flat PET resin plate was prepared by wet coating.

[0058] (Example 3 of the present invention) As a projection device cover for Example 3 of the present invention, an anti-reflection film was prepared by laminating, in this order, a TAC film, a 150 nm thick zirconia nanoparticle layer formed on the TAC film, and a 100 nm thick silica nanoparticle layer formed on the zirconia nanoparticle layer, on a projection device cover body made of a 0.3 mm thick flat polycarbonate resin, and bonding this to the cover body with a 25 μm thick optical adhesive.

[0059] <Evaluation> The following evaluations (1) to (3) were carried out on each of the produced projection device covers of the invention example and comparative example.

[0060] (1) Relationship between the thickness of the projector cover and the occurrence of double images The projection device cover of Comparative Example 1 was placed at the exit of a projector (Casio Computer Co., Ltd. XJ-V110W projector), and a screen was placed 2 m away. A grid-like image was displayed, and when the display light was incident, the occurrence of double images was observed and evaluated according to the following criteria. 〇:Not noticeable △: A faint double image is observed ×: Double images are noticeable The occurrence of double images was observed when the thickness of the projection device cover of Comparative Example 1 was changed to 0.1 mm, 0.3 mm, 0.5 mm, and 1 mm, and when the curvature of the projection device cover of Comparative Example 1 was changed to 50 mm, 100 mm, 500 mm, and ∞ (flat), and an evaluation was performed for each case. The evaluation results are shown in Table 1.

[0061] [Table 1]

[0062] The results in Table 1 show that the occurrence of double images becomes more pronounced when the projection device cover is thick or when the radius of curvature is small.

[0063] (2) Relationship between the luminous reflectance of the cover for the projection device and the angle of incidence of light For each model of the projection device cover produced in the examples of the present invention and the comparative examples, the luminous reflectance (%) was calculated relative to the incident angle (°) of incident light with a black PET film attached to the back surface. The luminous reflectance was determined by measuring the reflectance spectrum using a spectrophotometer (JASCO V-650) and calculating the tristimulus value Y in accordance with JIS Z 8722:2009. The luminous reflectance (%) as a function of the angle of incidence (°) of the incident light was calculated for both unpolarized and S-polarized incident light. The results are shown in Figure 5. Furthermore, the luminous reflectance (%) when the incident angle (°) of the incident light is 5° and 55° is as follows: This is also shown in Table 2.

[0064] (3) Calculation of double image intensity Regarding the models of projection device covers manufactured in the examples of the present invention and the comparative examples, The light was incident under the conditions above, and the double image intensity (%) relative to the incident angle (°) of the incident light was calculated according to the following formula: Double image strength (%)=(1-r1)(1-r2)r1r2×100% r1: reflectance at the incident surface of the projection device cover, r2: reflectance at the exit surface of the projection device cover The double image intensity is an index used to determine the extent to which double images occur, with larger values indicating more noticeable double images. Additionally, the double image intensity (%) as a function of the angle of incidence (°) of the incident light was calculated for both unpolarized and S-polarized incident light. The results are shown in Figure 6. Furthermore, Table 2 also shows the double image intensity (%) when the incident angle (°) of the incident light is 5° and 55°.

[0065] [Table 2]

[0066] 5 and Table 2, it can be seen that for all projection device covers, the luminous reflectance increases as the incident angle of incident light increases. Furthermore, when the projection device covers of the present invention were used, it was found that the luminous reflectance for light incident at an incident angle of 30 to 55° was 6% or less.

[0067] 6 and Table 2, it can be seen that for all projection device covers, the greater the incident angle of the incident light, the greater the double image intensity. Furthermore, it can be seen that when the projection device cover of Example 1 of the present invention was used, the double image intensity was particularly kept low. [Industrial Applicability]

[0068] According to the present invention, it is possible to provide a projection device and a cover for the projection device that can suppress uneven brightness of a displayed image and the occurrence of double images even for incident light with a wide distribution of incident angles. [Explanation of symbols]

[0069] 1 Projector cover 2 light source 3 Display element 4, 4', 4'' mirror 5 Display surface 6 Polarizing element 10 Main Unit 20 Fine unevenness layer 21 Convex part 22 Support part 23 Grid structure materials 100 Projection device TL projection light DI display image IL incident light OL, GL output light RL0 reflected light RL1, RL2 internally reflected light H Height of the convex part P Concave and convex cycle

Claims

1. A housing-shaped projection device including at least a light source, a display element, a mirror, and a projection device cover, The projection device cover is provided at an opening through which projection light is emitted from the projection device, and at least one surface of the cover has a luminous reflectance of 6% or less for light incident at an incident angle of 30 to 55 degrees.

2. 2. The projection device according to claim 1, wherein the luminous reflectance of at least one surface of the projection device cover for light incident at an incident angle of 5° is 3% or less.

3. 3. The projection device according to claim 1, wherein the luminous reflectance of at least one surface of the projection device cover for S-polarized light incident at an incident angle of 30 to 55° is 10% or less.

4. 3. The projection device according to claim 1, wherein the projection device cover has a thickness of 0.1 mm or more.

5. 3. The projection device according to claim 1, wherein the projection device cover has a curved surface with a radius of curvature of 500 mm or less.

6. 3. The projection apparatus according to claim 1, wherein the projection apparatus cover contains a polycarbonate resin, an acrylic resin, or an acetyl cellulose resin.

7. the projection apparatus cover includes a projection apparatus cover body and an anti-reflection layer formed on the projection apparatus cover body; 3. The projection device according to claim 1, wherein the anti-reflection layer is formed on the projection device cover body via an adhesive layer, or the anti-reflection layer is formed directly on the projection device cover body.

8. 3. The projection device according to claim 1, wherein the projection device is a head-up display or a projector.

9. A projection device cover provided at an opening through which projection light is emitted in a housing-shaped projection device, The cover for a projection device is characterized in that the luminous reflectance of at least one surface of the cover for a projection device for light of a wavelength of 550 nm incident at an incident angle of 30 to 55° is 6% or less.

Images