JP7070613B2 - Video display device - Google Patents

Description

The present invention relates to a reflective screen that reflects and displays projected video light, and a video display device including the reflective screen.

Conventionally, various reflective screens have been developed that reflect and display the image light projected from the image source (see, for example, Patent Document 1). Above all, it can be used as a reflective screen that reflects the projected image light and allows the image to be seen well by attaching it to a member with high translucency such as window glass, and does not project the image light. Demand for semi-transmissive reflective screens, which allow the scenery on the other side of the screen to be seen through when in use, is increasing due to its high design.

Japanese Unexamined Patent Publication No. 9-114003

However, if such a transflective reflective screen is provided with a diffusing layer containing diffusing particles or the like, the scenery on the other side of the screen is observed to be whitish and blurred, resulting in deterioration of design, and thus transparency. Was an issue. In addition, it is always required to reduce the thickness of various screens and display good images with high contrast.
The above-mentioned Patent Document 1 proposes a screen that can be used for both a transmissive type and a reflective type, and can transmit light from the back surface side. However, this Patent Document 1 does not disclose any measures for improving transparency.

An object of the present invention is to provide a reflective screen having high transparency and capable of displaying a good image, and an image display device provided with the reflective screen.

The present invention solves the above-mentioned problems by the following solution means. In addition, in order to facilitate understanding, the description will be given with reference numerals corresponding to the embodiments of the present invention, but the present invention is not limited thereto.
The first invention is a semi-transmissive type reflection screen that reflects an image light (L) projected from an image source and displays an image, and is a semi-transmissive type that reflects a part of the incident light and transmits the other. A transmissive reflective layer (13), at least one image source side layer (11, 12) having light transmittance provided on the image source side of the reflective layer, and at least one layer on the back surface side of the reflective layer. The total amount Sp of the light incident on the screen surface of the reflection screen from the image source side at an incident angle of 0 ° is provided with the provided back surface side layer (14, 15, 25, 26) having light transmission. When it is set to 100%, the sum of the transmittance Tp (%) transmitted to the back surface side and the reflectance Rp (%) reflected by the reflective layer and emitted to the image source side is 90% or less. The light absorption rate Ap (%) in the reflective screen is 10% or more, and in the thickness direction of the reflective screen, from the image source side surface (10a) to the back surface side surface (13b) of the reflective layer. When the image source side region (Sa) is used and the area from the image source side surface (13a) to the back surface side (10b) of the reflection layer is the back side region (Sb), the screen surface of the reflection screen is covered from the back side. The absorption rate of the light in the back surface region with respect to the light incident at an incident angle of 0 ° is the absorption rate of the light in the image source side region with respect to the light incident on the screen surface of the reflection screen from the image source side at an incident angle of 0 °. It is a reflective screen (10, 20) characterized by being larger than.
According to the second invention, in the reflective screen according to the first invention, the transmittance of light incident on the screen surface of the reflective screen at an incident angle of 0 ° is 10 to 85%, and the screen surface of the reflective screen. The reflective screen (10, 20) is characterized in that the transmittance of light incident on the light at an incident angle of 0 ° is 10 to 30%.
According to the third invention, in the reflective screen according to the first invention or the second invention, light incident on the screen surface of the reflective screen from the back surface side at an incident angle of 0 ° is reflected by the reflective layer (13). The reflectance emitted from the back surface side is smaller than the reflectance emitted from the image source side by reflecting the light incident on the screen surface of the reflection screen from the image source side at an incident angle of 0 ° by the reflection layer. It is a reflective screen (10, 20) characterized by.

According to a fourth aspect of the present invention, in the reflective screen according to any one of the first to third inventions, the image source side layer has light transmission and has a unit optical shape (121) on the back surface side surface. ) Have an optical shape layer (12) in which a plurality of) are arranged, and the unit optical shape has a first surface (121a) on which image light is incident and a second surface (121b) facing the first surface (121a). However, the reflective layer (13) is a reflective screen (10, 20) characterized in that it is formed on at least a part of the first surface of the unit optical shape.
According to a fifth aspect of the present invention, in the reflective screen according to any one of the first to fourth inventions, the reflective layer (13) has a fine and irregular uneven shape formed on the surface thereof. , A reflective screen (10, 20).
The sixth invention is the surface of the reflective screen according to any one of the first to fifth inventions, from the back surface side surface (10b) to the image source side surface of the reflective layer in the thickness direction of the reflective screen. The back surface region (Sb) up to (13a) is provided with at least one light absorption layer (15, 26) that absorbs light and sets the light transmittance of the reflective screen to a predetermined value. Reflective screen (10, 20).
According to the seventh invention, in the reflection screen according to any one of the first to sixth inventions, from the emission angle which is the peak brightness of the reflected light of the reflection screen to the emission angle where the brightness is halved. The reflection screen (10, 20) is characterized in that 5 ° ≦ α ≦ 45 ° when the amount of change in the angle of is + α1 and −α2 and the average value of the absolute values is α.
According to the eighth aspect of the present invention, in the reflective screen according to any one of the first to seventh inventions, the image source side layer has light transmission and has a unit optical shape (121) on the back surface side surface. ) Have an optical shape layer (12) in which a plurality of) are arranged, and the unit optical shape has a first surface (121a) on which video light is incident and a second surface (121b) facing the first surface (121a). Then, in the arrangement direction of the unit optical shape, the amount of angle change from the emission angle which is the peak brightness of the reflected light of the reflection screen to the emission angle where the brightness is halved is set to + α1 and −α2, and the absolute value thereof is set. When the average value is α and the angle formed by the first surface with the surface parallel to the screen surface is θ1, α <arcsin (n × sin (2 × (θ11)) in at least a part of the reflective screen. ))) Is a reflective screen (10, 20) characterized by satisfying the relationship.
In the ninth invention, the reflective screen according to any one of the first to eighth inventions and the image source side layer have light transmission, and image light is incident on the back surface. There is an optical shape layer (12) in which a plurality of unit optical shapes (121) having a first surface (121a) and a second surface (121b) facing the first surface (121a) are arranged to form a circular Fresnel lens shape. The optical center (C) of the circular Fresnel lens shape is outside the display area of the reflection screen, and the reflection layer (13) is formed on at least a part of the first surface of the unit optical shape. It is a reflective screen (10, 20) characterized by being done.

A tenth aspect of the present invention comprises a reflective screen (10, 20) according to any one of the first to ninth inventions, and an image source (LS) for projecting image light onto the reflective screen. It is a display device (1).
According to the eleventh invention, in the image display device according to the tenth invention, the angle of incidence of the image light (L) projected by the image source (LS) on the screen surface of the reflection screen (10, 20) is determined. The image display device (1) is characterized in that it is larger than 0 °.

According to the present invention, it is possible to provide a reflective screen having high transparency and capable of displaying a good image, and an image display device including the reflective screen.

It is a figure which shows the image display device 1 of 1st Embodiment. It is a figure explaining the layer structure of the screen 10 of 1st Embodiment. It is a figure which looked at the 1st optical shape layer 12 of 1st Embodiment from the back surface side (−Z side). It is a figure explaining the relationship between the 1/2 angle α, the incident angle φ of the image light, and the angle θ1 of the first slope 121a. It is a figure explaining the light transmittance and the absorption rate of the screen 10 of 1st Embodiment. It is a figure which shows the state of the image light and the outside light on the screen 10 of 1st Embodiment. It is a figure explaining the layer structure of the screen 20 of the 2nd Embodiment. It is a figure explaining the layer structure of the screen 30 of a modified form. It is a figure which shows the image display device 1A of a modified form.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. In addition, each figure shown below including FIG. 1 is a diagram schematically shown, and the size and shape of each part are exaggerated as appropriate for easy understanding.
In the present specification, terms that specify a shape or a geometric condition, for example, terms such as parallel and orthogonal, have the same optical function in addition to their strict meanings, and can be regarded as parallel or orthogonal. It shall also include the state having the error of.

In the present specification, numerical values such as dimensions of each member and material names described are examples of embodiments, and the present invention is not limited to these, and may be appropriately selected and used.
In this specification, terms such as board and sheet are used. Generally, the plate, the sheet, and the film are used in the order of thickness, and are used in the same manner in the present specification. However, since there is no technical meaning in such proper use, these words can be replaced as appropriate.
In the present specification, the screen surface indicates a surface in the plane direction of the screen when viewed as a whole screen, and is assumed to be parallel to the screen (display surface) of the screen.

(First Embodiment)
FIG. 1 is a diagram showing a video display device 1 of the first embodiment. 1A is a perspective view of the image display device 1, and FIG. 1B is a side view of the image display device 1.
The image display device 1 has a screen 10, an image source LS, and the like. The screen 10 of the present embodiment is a reflective screen that reflects the image light L projected from the image source LS and displays the image on the screen. The details of the screen 10 will be described later.
In the present embodiment, as an example, the video display device 1 is applied to the show window of a store, and the screen 10 is fixed to the glass of the show window.

Here, in order to facilitate understanding, in each of the figures shown below including FIG. 1, an XYZ Cartesian coordinate system is appropriately provided and shown. In this coordinate system, the horizontal direction (horizontal direction) of the screen of the screen 10 is the X direction, the vertical direction (vertical direction) is the Y direction, and the thickness direction of the screen 10 is the Z direction. The screen of the screen 10 is parallel to the XY plane, and the thickness direction (Z direction) of the screen 10 is orthogonal to the screen of the screen 10.
Further, the direction toward the right side in the horizontal direction when viewed from the observer O1 located in the front direction on the image source side of the screen 10 is the + X direction, the direction toward the upper side in the vertical direction is the + Y direction, and the back side (back surface side) in the thickness direction. ) To the image source side (observer side) is the + Z direction.
Further, in the following description, the screen vertical direction, the screen horizontal direction, and the thickness direction are the screen vertical direction (vertical direction), the screen horizontal direction (horizontal direction), and the screen vertical direction in the usage state of the screen 10, unless otherwise specified. It is assumed that it is the thickness direction (depth direction) and is parallel to the Y direction, the X direction, and the Z direction, respectively.

The image source LS is an image projection device that projects the image light L onto the screen 10, and is, for example, a short focus type projector.
This image source LS is the center of the screen 10 in the left-right direction of the screen when the screen (display area) of the screen 10 is viewed from the front direction (normal direction of the screen surface) in the state of use of the image display device 1. It is located below the screen of the screen 10 in the vertical direction.
The image source LS can project the image light L diagonally in the depth direction (Z direction) from a position where the distance from the surface of the screen 10 is significantly closer than that of a general-purpose projector located in the front direction of the screen of the conventional screen. .. Therefore, as compared with the conventional general-purpose projector, the image source LS has a shorter projection distance to the screen 10 and a larger incident angle at which the projected image light is incident on the screen 10.

The screen 10 can display the image by reflecting the image light L projected by the image source LS toward the observer O1 side located in the front direction of the image source side, and can display the image on the other side (rear side,-) of the screen 10. It is a semi-transmissive reflective screen that can observe the scenery on the Z side).
The screen (display area) of the screen 10 has a substantially rectangular shape in which the long side direction is the left-right direction of the screen when viewed from the observer O1 side in the used state.
The screen 10 has a large screen having a screen size of about 80 to 100 inches diagonally, and the aspect ratio of the screen is 16: 9. The size and shape may be not limited to this, and may be, for example, about 40 inches or less, and the size and shape can be appropriately selected according to the purpose of use, the environment of use, and the like.

In general, the screen 10 is a laminate of thin layers made of resin or the like, and often does not have sufficient rigidity to maintain flatness by itself. Therefore, as shown in FIG. 1B and the like, the screen 10 of the present embodiment is integrally joined (or partially fixed) to the support plate 50 via a light-transmitting bonding layer 51 on the back surface side thereof, and the screen is displayed. Maintains the flatness of.
The support plate 50 is a flat plate-shaped member having light transmittance and high rigidity, and a plate-shaped member made of resin such as acrylic resin or PC resin or made of glass can be used.
In the present embodiment, the support plate 50 is a window glass of a show window of a store or the like. Not limited to this, the screen 10 may be in a form in which its four sides or the like are supported by a frame member or the like (not shown) to maintain its flatness.

FIG. 2 is a diagram illustrating a layer structure of the screen 10 of the first embodiment. In FIG. 2, the screen passes through a point A (see FIGS. 1 (a) and 1 (b)), which is the center of the screen (geometric center of the screen) of the screen 10, and is parallel to the vertical direction (Y direction) of the screen. A part of the cross section orthogonal to the plane (parallel to the Z direction) is shown enlarged. In FIG. 2, only the screen 10 is shown, and the support plate 50 and the like are omitted.
FIG. 3 is a view of the first optical shape layer 12 of the first embodiment as viewed from the back surface side (−Z side). For ease of understanding, the reflective layer 13, the second optical shape layer 14, the protective layer 15, and the like are omitted.
As shown in FIG. 2, the screen 10 has a base material layer 11, a first optical shape layer 12, a reflection layer 13, and a second optical shape in order from the image source side (+ Z side) in the thickness direction (Z direction). It includes a layer 14, a protective layer 15, and the like.

The base material layer 11 is a sheet-like member having light transmission, and the first optical shape layer 12 is integrally formed on the back surface side (−Z side) thereof. The base material layer 11 is a layer that serves as a base material (base) that forms the first optical shape layer 12.
The base material layer 11 is formed of, for example, a polyester resin such as PET (polyethylene terephthalate), an acrylic resin, a styrene resin, an acrylic styrene resin, a PC (polycarbonate) resin, an alicyclic polyolefin resin, a TAC (triacetyl cellulose) resin, or the like. Will be done.
The thickness of the base material layer 11 may be selected according to the screen size of the screen 10 and the like.

The first optical shape layer 12 is a light-transmitting layer formed on the back surface side (−Z side) of the base material layer 11. A plurality of unit optical shapes (unit lenses) 121 are arranged and provided on the back surface (−Z side) surface of the first optical shape layer 12. As shown in FIG. 3, a plurality of unit optical shapes 121 are arranged concentrically around a point C located outside the screen (display area) of the screen 10. That is, the first optical shape layer 12 has a circular Fresnel lens shape on the back surface side.
The circular Fresnel lens shape of the first optical shape layer 12 is a circular Fresnel lens shape having a so-called offset structure centered on the point C (Fresnel center). Therefore, as shown in FIG. 3, when the first optical shape layer 12 is viewed from the back side in the normal direction of the screen surface, the unit optical shape (unit lens) 121 which is a partial shape (arc shape) of a perfect circle is formed. Observed as if they were arranged in multiples. As shown in FIG. 3, this point C is located at the center in the left-right direction of the screen and at the lower side of the screen. Therefore, when the screen 10 is viewed from the front direction, the points C and the points A are located in the same linear shape.

In the present embodiment, an example in which a circular Fresnel lens shape is formed on the back surface of the first optical shape layer 12 is shown, but the present invention is not limited to this, and the back surface of the first optical shape layer 12 is not limited to this. On the surface, a linear Fresnel lens shape in which the unit optical shape 121 is arranged in the screen vertical direction (Y direction) with the screen left-right direction (X direction) as the longitudinal direction may be formed.

As shown in FIG. 2, the unit optical shape 121 is parallel to the direction orthogonal to the screen surface (Z direction), and the cross-sectional shape in the cross section parallel to the arrangement direction of the unit optical shape 121 is a substantially triangular shape. ..
The unit optical shape 121 is convex on the back surface side, and has a first slope (lens surface) 121a on which image light is incident and a second slope (non-lens surface) 121b facing the first slope (lens surface) 121a. In one unit optical shape 121, the first slope 121a is located on the upper side (+ Y side) of the second slope 121b with the apex t interposed therebetween.
The angle formed by the first slope 121a with the surface parallel to the screen surface is θ1. The angle formed by the second slope 121b with the plane parallel to the screen plane is θ2. The angles θ1 and θ2 satisfy the relationship θ2> θ1.
The first slope 121a and the second slope 121b of the unit optical shape 121 have a fine and irregular uneven shape. The fine uneven shape is formed by irregularly arranging the convex shape and the concave shape in the two-dimensional direction, and the convex shape and the concave shape have irregular sizes, shapes, heights, and the like.

The arrangement pitch of the unit optical shape 121 is P, and the height of the unit optical shape 121 (the dimension from the apex t in the thickness direction to the point v which is the valley bottom between the unit optical shapes 121) is h.
For ease of understanding, FIG. 2 shows an example in which the arrangement pitch P and the angles θ1 and θ2 of the unit optical shape 121 are constant in the arrangement direction of the unit optical shape 121. However, in the unit optical shape 121 of the present embodiment, the arrangement pitch P is actually constant, but the angle θ1 gradually increases as the angle θ1 moves away from the point C which becomes the Fresnel center in the arrangement direction of the unit optical shape 121. ..
Further, the angles θ1 and θ2, the arrangement pitch P, and the like are the projection angle of the image light from the image source LS (the angle of incidence of the image light on the screen 10), the size of the pixels of the image source LS, and the screen 10. It may be set as appropriate according to the screen size of the screen, the refractive index of each layer, and the like. For example, the arrangement pitch P may change along the arrangement direction of the unit optical shape 121, and the angles θ1 and θ2 may change.

The first optical shape layer 12 is formed of an ultraviolet curable resin such as urethane acrylate-based, polyester acrylate-based, epoxy acrylate-based, polyether acrylate-based, polythiol-based, and butadiene acrylate-based resin having high light transmittance.
In the present embodiment, the ultraviolet curable resin will be described as an example of the resin constituting the first optical shape layer 12, but the present invention is not limited to this, and for example, other ionizing radiation such as an electron beam curable resin is used. It may be formed of a curable resin.

The reflective layer 13 is formed on the unit optical shape 121 (on the first slope 121a and the second slope 121b). Further, the reflective layer 13 is a semi-transmissive reflective layer, a so-called half mirror, that reflects a part of the incident light and transmits the others.
As described above, the first slope 121a and the second slope 121b are formed with fine uneven shapes, and the reflective layer 13 is formed following the fine uneven shapes. Further, the thickness of the reflective layer 13 is sufficiently thinner than the unevenness of the fine uneven shape. Therefore, the surface of the reflective layer 13 on the image source side (the surface on the first optical shape layer 12 side) and the surface on the back surface side (the surface on the second optical shape layer 14 side) have fine and irregular irregular shapes. It has a matte surface.
The reflective layer 13 has a function of diffusing and reflecting a part of the incident light due to a fine uneven shape, and transmitting other non-reflecting light without diffusing.

The surface roughness of the surface of the reflective layer 13 on the image source side (that is, the surface roughness of the first slope 121a) is such that the arithmetic average roughness Ra (JIS B0601-2001) is about 0.10 to 0.50 μm. This is preferable from the viewpoint of displaying the image well by the reflected light. The arithmetic average roughness Ra, which is the surface roughness of the surface of the reflective layer 13 on the image source side (that is, the surface roughness of the first slope 121a), may be appropriately selected depending on the desired optical performance and the like.
The ratio of the reflectance and the transmittance of the reflective layer 13 can be appropriately set according to the desired optical performance.

Further, in the reflective layer 13, a region that is not a rough surface, that is, a surface on the image source side (a surface on the first optical shape layer 12 side) that does not have a fine uneven shape is a mirror surface and is incident. The mirror surface region where the image light is mirror-reflected is 5% or less per unit area of the reflection layer 13 formed on the first slope 121a in order to sufficiently diffuse the image light and obtain a good viewing angle. It is necessary for, and ideally it is 0%.
When the non-rough mirror surface region exceeds 5% per unit area of the reflection layer 13 formed on the first slope 121a, bright lines are generated or the viewing angle is lowered due to the components of the image light that is not diffused and reflected. It is not preferable because it may occur.

Such a reflective layer 13 is made of a metal having high light reflectivity, for example, aluminum, silver, nickel, or the like, and its thickness is about several tens of Å. The reflective layer 13 of the present embodiment is formed by depositing aluminum.
The reflective layer 13 is not limited to this, and may be formed by, for example, sputtering a metal having high light reflectivity, transferring a metal foil, applying a paint containing a metal thin film, or the like. .. Further, the reflective layer 13 may be formed by depositing a dielectric multilayer film.

The second optical shape layer 14 is a layer having light transmittance provided on the back surface side (−Z side) of the first optical shape layer 12. The second optical shape layer 14 is provided to flatten the back surface (−Z side) surface of the first optical shape layer 12, and is formed so as to fill the valley between the unit optical shapes 121. There is. Therefore, the surface of the second optical shape layer 14 on the image source side (+ Z side) is formed by arranging a plurality of substantially inverted shapes of the unit optical shape 121 of the first optical shape layer 12.
By providing such a second optical shape layer 14, the reflective layer 13 can be protected, the protective layer 15 and the like can be easily laminated on the back surface of the screen 10, and the support plate 50 and the like can be easily laminated. Joining is also easy.
It is desirable that the refractive index of the second optical shape layer 14 is the same as that of the first optical shape layer 22, and the second optical shape layer 14 uses the same ultraviolet curable resin as the first optical shape layer 12 described above. It is preferable to form it. In the present embodiment, the second optical shape layer 14 is formed of the same resin as the first optical shape layer 12.

The protective layer 15 is a layer formed on the back surface side (-Z side) of the second optical shape layer 14, and is a sheet-like member having a function of protecting the back surface side of the screen 10. Further, the protective layer 15 is a light absorbing layer that is colored with a dye such as gray or black or a coloring material such as a pigment and has light absorption. Further, the protective layer 15 is set in color density and layer thickness so that the light transmittance of the screen 10 becomes a predetermined value. The protective layer 15 has a function of absorbing unnecessary external light such as illumination light incident on the screen 10 and stray light to improve the contrast of the image.

The base material of the protective layer 15 includes polyester resin such as PET, acrylic resin, styrene resin, acrylic styrene resin, PC resin, alicyclic polyolefin resin, TAC resin, MS (methacrylic styrene) resin, and MBS (methacrylic butadiene styrene). Resin or the like is suitable. Further, the base material of the protective layer 15 may be the same material as the above-mentioned base material layer 11.
Examples of the coloring material contained in the protective layer 15 include dark-colored dyes and pigments such as gray and black, and metal salts such as carbon black, graphite and black iron oxide.
The thickness, light transmittance, absorption rate, etc. of the protective layer 15 may be appropriately adjusted according to the screen size of the screen 10 and the desired optical performance.
As described above, the screen 10 of the present embodiment does not have a light diffusing layer containing a diffusing material such as particles having a diffusing action, and it is the fine irregularities on the reflective surface of the reflective layer 13 that have a diffusing action. Only the shape.

The screen 10 is formed by, for example, the following manufacturing method.
By a UV molding method, a base material layer 11 is prepared, laminated on one surface of a molding mold having a unit optical shape 121 filled with an ultraviolet curable resin, and irradiated with ultraviolet rays to cure the resin. The first optical shape layer 12 is formed. At this time, fine uneven shapes are formed on the surfaces forming the first slope 121a and the second slope 121b of the molding die that shape the unit optical shape 121. This fine uneven shape can be formed by repeating plating under different conditions twice or more, or performing an etching process on the surfaces forming the first slope 121a and the second slope 121b of the molding die.
After the first optical shape layer 12 is formed on one surface of the base material layer 11, the reflective layer 13 is formed on the first slope 121a and the second slope 121b by vapor deposition or the like.

After that, the ultraviolet curable resin is applied from above the reflective layer 13 so as to fill the valley portion between the unit optical shapes 121 so as to be flat, and the protective layer 15 is laminated to cure the ultraviolet curable resin. , The second optical shape layer 14 and the protective layer 15 are integrally formed. After that, the screen 10 is completed by cutting it to a predetermined size or the like.
The base material layer 11 and the protective layer 15 may be in the form of a single leaf or in the form of a web. For example, when the base material layer 11 and the protective layer 15 have a web shape and the first optical shape layer 12 has a linear Fresnel lens shape, the screen 10 in the state before cutting can be continuously manufactured. It is possible to improve the production efficiency of the screen 10 and reduce the production cost.

Further, for example, as a method of forming a rough surface on the first slope 121a and the second slope 121b, diffusion particles or the like are applied on the first slope 121a and the second slope 121b to form the reflective layer 13 from above. , A method of blasting the first slope 121a and the second slope 121b after forming the first optical shape layer 12 is known. However, when the reflective surface of the reflective layer 13 is made a rough surface by such a manufacturing method, the diffusion characteristics and quality of each screen 10 vary widely, and stable production cannot be performed. On the other hand, as described above, a large number of first optical shape layers 12 and screens 10 are formed by shaping the fine uneven shapes of the first slope 121a and the second slope 121b of the unit optical shape 121 by a molding die. Even in the case of manufacturing, there is an advantage that there is little variation in quality and stable manufacturing is possible.

Here, the arrangement direction of the unit optical shape 121 (the present embodiment) with respect to the angle K of the peak brightness of the light (reflected light) incident on the reflection layer 13 from the first slope 121a and diffusely reflected and emitted from the screen 10. Then, in the vertical direction of the screen), the angle at which the brightness becomes 1/2 is K1 and K2, and the angle change amount from the peak brightness angle K to the angle K1 and K2 at which the brightness becomes 1/2 is + α1 (however, K + α1). When = K1) and -α2 (K-α2 = K2), the average value of the absolute value of the amount of change in angle from the peak brightness to the half of the brightness is α (hereinafter referred to as 1/2 angle α). It is preferable that this 1/2 angle α satisfies 5 ° ≦ α ≦ 45 °.

When α <5 °, the viewing angle becomes too narrow and it becomes difficult to see the image, which is not preferable. Further, when α <5 °, the specular reflection component increases in the reflected light, and the reflection of the light source occurs, which is not preferable.
When α> 45 °, the viewing angle is widened, but the brightness of the image is reduced, the image is blurred, and the contrast of the image is reduced due to the reflection of external light on the screen 10. not. Therefore, the above range is preferable for the 1/2 angle α.
In the screen 10 of the present embodiment, since the uneven shape of the reflective layer 13 is irregular, the 1/2 angle α in the left-right direction of the screen is equal to or substantially equal to the 1/2 angle α in the vertical direction of the screen. ..

FIG. 4 is a diagram illustrating the relationship between the 1/2 angle α, the incident angle φ of the image light, and the angle θ1 of the first slope 121a. In FIG. 4, for ease of understanding, the configuration inside the screen 10 is simplified, and the base material layer 11 and the protective layer 15 are omitted. Further, in FIG. 4, regarding the angles α and φ, the upper side of the screen is shown as + and the lower side of the screen is shown as − with respect to the normal of the screen surface.
The angle θ1 of the first slope 121a is such that the image light is most efficiently reflected by the observer located in the front direction of the screen 10, that is, the angle K at which the peak brightness of the reflected light is 0 °. In addition, it is designed based on the refractive index of each layer. Further, the range from −α to +α is a range assuming that the observer located in front of the screen can observe the image well.
Here, at a certain point in the vertical direction of the screen (the direction passing through the point A and parallel to the arrangement direction of the unit optical shape 121), the image light L is incident from below the screen 10 at an incident angle −φ, and has a refractive index n. 1 The optical shape layer 12 is advanced, is incident on the first slope 121a forming an angle θ1 with respect to the screen surface, is reflected by the reflection layer 13, and is emitted from the screen 10 in a direction orthogonal to the screen surface (emission angle 0 °). Then, the angle θ1 is expressed by the following (Equation 1).
θ1 = 1/2 × arcsin ((sinφ) / n) (Equation 1)

As in the present embodiment, when the image light is projected from the image source LS and reflected by the screen 10 and the image is displayed, the light source of the image source LS that projects the image light is reflected, and the contrast of the image is lowered. May occur. The main cause of the reflection of this image source is that the image light reflected on the surface of the screen reaches the observer.
In order to prevent such reflection of the image source, the surface of the screen is outside the angle range (−α to + α), which is the range on the surface of the screen 10 where the observer mainly observes the image well. It is preferable that the image light reflected by is advanced. When a part Lr of the image light L incident at the incident angle −φ is reflected on the screen surface, the reflection angle is + φ. Therefore, it is preferable that α <φ in order to prevent reflection of the image source.

Therefore, from the above-mentioned (Equation 1), in the vertical direction of the screen (arrangement direction of the unit optical shape 121), the angle θ1 between the 1/2 angle α and the first slope 121a is to prevent the reflection of the image source. , At least a part of the screen 10 (for example, the center of the screen) preferably satisfies the following (Equation 2).
α <arcsin (n × sin (2 × (θ1))) ・ ・ ・ (Equation 2)
Further, in order to prevent reflection of the image source, it is more preferable that the 1/2 angle α and the angle θ1 of the first slope 121a satisfy the above (Equation 2) in the entire area of the screen 10.
By making the angle θ1 and the 1/2 angle α satisfy the above (Equation 2), the direction (direction of + φ) in which the light reflected on the surface of the screen 10 mainly heads when incident on the screen 10 is set. The image light reflected by the reflective layer 13 is outside the range (−α to + α) emitted from the screen 10 and travels. As a result, in the range from −α to + α, the reflection of the image source LS can be reduced, and a good image with high contrast can be displayed.

FIG. 5 is a diagram illustrating the light transmittance and the absorption rate of the screen 10 of the first embodiment. In FIG. 5, for ease of understanding, the unit optical shape 121 of the first optical shape layer 12 is omitted, and the reflective layer 13 is described as a flat surface.
With respect to the light incident on the screen surface of the screen 10 of the present embodiment from the image source side (+ Z side) at an incident angle of 0 °, the transmittance (total light transmittance) transmitted to the back surface side when the total amount Sp is 100%. ) Is Tp (%), the reflectance reflected by the reflective layer 13 and emitted to the image source side is Rp (%), and the transmittance absorbed in the screen 10 (from the total amount Sp, the transmittance Tp and the transmittance). When Ap (%) is the value obtained by subtracting the sum with Rp, the sum of the transmittance Tp and the reflectance Rp is 90% or less, and the absorption rate Ap is 10% or more. That is, they satisfy the following equations.
Tp + Rp≤90 ... (Equation 3)
Ap = Sp- (Tp + Rp) ≧ 10 ... (Equation 4)

Further, in the screen 10 of the present embodiment, the transmittance of light La incident on the screen surface at an incident angle of 0 ° (corresponding to the above-mentioned Tp) may be incident from the image source side or the back surface side. It is 10 to 85%. That is, the transmittance Tp satisfies 10 ≦ Tp ≦ 85.
If the transmittance is less than 10%, the transparency of the screen 10 is lost, which is not preferable. Further, when the transmittance is larger than 85%, the brightness of the reflected and displayed image is lowered, which is not preferable. Therefore, the transmittance Tp preferably satisfies the above range.

Further, in the screen 10 of the present embodiment, the absorption rate of light incident on the screen surface at an incident angle of 0 ° (corresponding to the above-mentioned Ap) is 10 regardless of whether the light is incident from the image source side or the back surface side. It is ~ 30%, more preferably 10-20%. That is, the absorption rate Ap preferably satisfies 10 ≦ Ap ≦ 30, and more preferably 10 ≦ Ap ≦ 20.
If this absorption rate is less than 10%, the contrast of the image is lowered, which is not preferable. Further, when the absorption rate is larger than 30%, the brightness of the reflected and displayed image is lowered, and the transparency as a screen is lowered, which is not preferable. Therefore, the absorption rate preferably satisfies the above range.

Further, in the thickness direction of the screen 10, the region from the image source side surface 10a of the screen 10 to the surface 13b on the back surface side (−Z side) of the reflection layer 13 is defined as the image source side region Sa, and the back surface side surface 10b of the screen 10 is used. When the region from to the surface 13a on the image source side (+ Z side) of the reflective layer 13 is the back side region Sb, the absorption rate of light incident on the screen surface at an incident angle of 0 ° and transmitted through the back side region Sb. (Hereinafter referred to as the light absorption rate of the back surface region Sb) is the light absorption rate of light incident on the screen surface at an incident angle of 0 ° and transmitted through the image source side region Sa (hereinafter referred to as light of the image source side region Sa). It is larger than the absorption rate).

Here, the light absorption rate of the image source side region Sa and the light absorption rate of the back surface side region Sb are the incident angles 0 on the screen surface from the image source side (+ Z side) and the back surface side (−Z side), respectively. The light incident at ° can be compared by the reflectance when it is reflected by the reflection layer 13 and emitted to the image source side and the back surface side. The reflective layer 13 itself has the same reflectance of light incident from the image source side and the reflectance of light incident from the back surface side.
The reflectance of light Lc incident on the back surface of the screen 10 of the present embodiment at an incident angle of 0 ° (hereinafter referred to as the reflectance of light in the back region Sb) is an incident angle on the image source side surface 10a of the screen 10. It is smaller than the reflectance of the light Lb incident at 0 ° (hereinafter referred to as the reflectance of the image source side region Sa). That is, the amount of light incident on the back surface 10b of the screen 10 at an incident angle of 0 °, reflected by the reflective layer 13 and emitted to the back surface of the screen 10 is incident on the image source side surface 10a of the screen 10 at an incident angle of 0 °. It is smaller than the amount of light incident, reflected by the reflection layer 13, and emitted from the screen 10 to the image source side.

In the present embodiment, the light reflectance of the image source side region Sa is about 40%, the light reflectance of the back surface side region Sb is about 30%, and the light transmittance Tp of the entire screen 10 is Is the same 40% for both the incident light from the back surface side and the incident light from the image source side. Therefore, the screen 10 has a higher reflectance in the image source side region Sa and a higher light absorption rate in the back surface side region Sb.
With such a configuration, the screen 10 is viewed from the back side to the other side of the screen 10 (image source side), or from the image source side to the other side of the screen 10 (rear side). While maintaining high transparency, it is possible to absorb unnecessary illumination light incident from the back side and external light such as sunlight, and improve the contrast of the image. Further, since the protective layer 15 does not absorb the image light for displaying the image to the observer O1, the utilization efficiency of the image light required for displaying the image can be maintained high, and a bright and clear image can be displayed.

FIG. 6 is a diagram showing the state of video light and external light on the screen 10 of the first embodiment. FIG. 6 shows an enlarged part of a cross section of the unit optical shape 121 in a cross section parallel to the arrangement direction (Y direction) and the thickness direction (Z direction) of the screen. Further, in FIG. 6, in order to facilitate understanding, it is shown that there is no difference in the refractive index at the interface of each layer in the screen 10.
Of the image light L1 projected from the image source LS located below the screen 10 and incident on the screen 10, a part of the image light L2 is incident on the first slope 121a of the unit optical shape 121, and the reflection layer 13 It is diffusely reflected and emitted to the observer O side.

Of the video light incident on the first slope 121a, the other video light L3 that has not been reflected passes through the reflection layer 13 and is emitted from the back surface side (−Z side) of the screen 10. At this time, the image light L3 is emitted above the screen 10 and does not reach the observer O2 located in the front direction on the back side of the screen 10.
Further, of the video light L1 projected from the video source LS, a part of the video light L4 is reflected on the surface of the screen 10 and heads upward on the screen 10. At this time, since the reflection angle of the image light L4 is larger than the 1/2 angle α or more as described above, it does not interfere with the visual recognition of the image of the observer O1.
In the present embodiment, the image light L1 is projected from below the screen 10, and the angle θ2 (see FIG. 2) is larger than the incident angle of the image light at each point in the vertical direction of the screen of the screen 10. The light does not directly enter the second slope 121b, and the second slope 121b has almost no effect on the reflection of the image light.

Next, light from the outside world (hereinafter referred to as external light) such as sunlight other than the image light incident on the screen 10 from the back surface side (-Z side) or the image source side (+ Z side) will be described.
As shown in FIG. 4, among the external light G1 and G5 incident on the screen 10, some of the external light G2 and G6 are reflected on the surface of the screen 10 and head toward the lower side of the screen. Further, of the external light G1, a part of the external light G3 is reflected by the reflection layer 13, and a part of the external light G3 is emitted to the lower side of the screen 10, but a part of the external light G3 is on the surface of the screen 10 on the image source side (+ Z side). It is totally reflected and goes downward in the screen 10 and attenuates. Further, of the external light G5, a part of the external light G7 is absorbed by the protective layer 15 and then reflected by the reflective layer 13 and emitted to the upper side outside the screen on the back side (−Z side). .. Further, the other external light G4 and G8 that are not reflected by the reflective layer 13 pass through the reflective layer 13 and are emitted to the back surface side and the image source side, respectively. At this time, since the external light G2, G3, and G8 emitted to the image source side do not reach the observer O1, the decrease in contrast of the image can be suppressed.

Although not shown, a part of the external light incident on the screen 10 from the image source side and the back surface side is totally reflected by the surface on the back surface side and the image source side of the screen 10 and attenuated toward the lower side inside the screen. do.
Further, the other external light G9 and G10 pass through the reflective layer 13, a part of the light is absorbed by the protective layer 15 having light absorption property, and the other light is emitted to the back surface side and the image source side, respectively. do. Since the screen 10 does not contain a diffusing material or the like containing diffusing particles, the external light G9 and G10 transmitted through the screen 10 are not diffused. Therefore, when the scenery on the other side of the screen 10 is observed through the screen 10, the scenery on the other side of the screen 10 can be observed with high transparency without blurring or bleeding white.

In a semi-transmissive reflective screen having a diffusion layer containing conventional diffuse particles, the image light is diffused twice before and after reflection by the reflection layer, so that a good viewing angle can be obtained while the resolution of the image is obtained. There is a problem that In addition, since external light is also diffused by the diffused particles, the scenery on the other side of the screen is blurred or blurred into white.

However, the screen 10 of the present embodiment has no diffusing action except that the surface of the reflective layer 13 is a rough surface having a fine and irregular uneven shape, so that the image light is diffused only at the time of reflection. .. Further, in the screen 10 of the present embodiment, only the light reflected by the reflective layer 13 is diffused, and the transmitted light is not diffused. Therefore, the screen 10 of the present embodiment can display an image having a good viewing angle and resolution, and the scenery on the other side of the screen 10 is not blurred or blurred, and is well visible to the observer O1. And high transparency can be achieved.
Further, in the screen 10 of the present embodiment, the observer O1 can partially see the scenery on the other side (back side) of the screen 10 even when the image light is projected on the screen 10. Further, on the screen 10, the observer O2 located on the back side has high transparency and can see the scenery on the image source side (+ Z side) through the screen 10 well regardless of the presence or absence of projection of the image light. can do.

Further, in the screen of the present embodiment, the reflectance of the back surface side region Sb is smaller than that of the image source side region Sa. That is, the light absorption rate of the back surface side region Sb is larger than the light absorption rate of the image source side region Sa.
Therefore, it can be incident from the back side (-Z side) and escape to the image source side (+ Z side), and can absorb external light and the like that adversely affect the visual recognition of the image of the observer O1, while having high transparency as a screen. High-contrast images can be displayed. Moreover, since the protective layer 15 does not absorb the image light that is incident from the image source side and is reflected by the reflection layer 13 to display the image, the utilization efficiency of the image light is high and a bright and clear image can be displayed.

Further, in the screen 10 of the present embodiment, the angle θ1 of the first slope 121a is the above-mentioned (Equation 2) with respect to the 1/2 angle α of the image light (reflected light) diffusely reflected by the reflection layer 13. Therefore, the image light reflected on the surface of the screen 10 on the image source side is directed to the outside of the 1/2 angle α, and the image source LS is not reflected, so that a good image can be displayed.

(Second Embodiment)
FIG. 7 is a diagram illustrating a layer structure of the screen 20 of the second embodiment. In FIG. 7, a part of the cross section of the screen 20 of the second embodiment is enlarged and shown. The cross section of the screen 20 shown in FIG. 7 corresponds to the cross section of the screen 10 of the first embodiment shown in FIG.
The screen 20 of the second embodiment has a base material layer 11, a first optical shape layer 12, a reflection layer 13, and a second optical shape layer in order from the image source side (+ Z side) along the thickness direction (Z direction). It includes 14, a light absorbing layer 26, and a protective layer 25. The screen 20 of the second embodiment can be used for the image display device 1 in place of the screen 10 of the first embodiment described above.
The screen 20 of the second embodiment has the same embodiment as the screen 10 of the first embodiment described above, except that the protective layer 25 does not contain a coloring material and includes the light absorption layer 26. Therefore, the same reference numerals or the same reference numerals are given to the portions that perform the same functions as those of the first embodiment described above, and duplicate description will be omitted as appropriate.

The light absorption layer 26 is provided between the second optical shape layer 14 and the protective layer 15, and is a layer colored with a dye such as gray or black or a coloring material such as a pigment, and has light absorption property. It is a layer having. The thickness and density of the light absorption layer 26 are set so that the transmittance of the screen 10 becomes a predetermined value.
The light absorption layer 26 has a function of absorbing unnecessary external light such as illumination light incident on the screen 10 and stray light to improve the contrast of the image.

Examples of the resin serving as the base material of the light absorption layer 26 include PET resin, PC resin, MS resin, MBS resin, acrylic resin, TAC resin, PEN (polyethylene naphthalate) resin and the like. Examples of the coloring material of the light absorbing layer 26 include dark-colored dyes and pigments such as gray and black, and metal salts such as carbon black, graphite and black iron oxide.
The light absorption layer 26 of the present embodiment can be integrally laminated and formed, for example, by co-extrusion molding with the protective layer 25 described later.
Not limited to the above example, the light absorption layer 26 may be formed by depositing a material having a light absorption action on one side of the protective layer 25, or by coating the light absorption layer 26. good.

The thickness, light transmittance, and absorption rate of the light absorption layer 26 may be set according to the screen size of the screen 10 and the desired optical performance.
Further, in the present embodiment, the example in which the light absorption layer 26 is arranged on the image source side (+ Z side) of the protective layer 25 is shown, but the present invention is not limited to this, and for example, the back surface side (−Z) of the protective layer 25 is shown. It may be arranged on the side).

The protective layer 25 is a sheet-like member having light transmission. Unlike the protective layer 15 of the first embodiment described above, the protective layer 25 is a transparent layer that does not contain a coloring material and is not colored.
The protective layer 25 is formed of, for example, a polyester resin such as PET, an acrylic resin, a styrene resin, an acrylic styrene resin, a PC resin, an alicyclic polyolefin resin, a TAC resin, or the like.

Also in this embodiment, when the total amount Sp of the light incident on the screen surface of the screen 20 from the image source side (+ Z side) at an incident angle of 0 ° is 100%, the transmittance Tp (%) transmitted to the back surface side. ), The reflectance Rp (%) reflected by the reflective layer 13 and emitted to the image source side, and the absorption rate Ap (%) absorbed in the screen 10 are the above-mentioned (Equation 3) and (Equation 4). Meet.
Further, in the screen 20, the transmittance of light incident on the screen surface at an incident angle of 0 ° (corresponding to the above-mentioned Tp) is 10 to 85% regardless of whether the light is incident from the image source side or the back surface side. be.
Further, in the screen 20, the absorption rate of light incident on the screen surface at an incident angle of 0 ° (corresponding to the above-mentioned Ap) is 10 to 30% regardless of whether the light is incident from the image source side or the back surface side. More preferably, it is 10 to 20%.
Further, the light transmittance and the absorption rate of the base material layer 11 and the first optical shape layer 12 of the present embodiment are equal to the light transmittance and the absorption rate of the protective layer 25 and the second optical shape layer 14. Since the screen 20 of the present embodiment includes the light absorption layer 26 in the back side region Sb, the light absorption rate of the back side region Sb is the same as that of the first embodiment described above. It is larger than the light absorption rate.
According to the present embodiment, as in the first embodiment described above, it is possible to realize a screen 20 and an image display device 1 capable of displaying a bright and good image with high contrast while maintaining high transparency.

(Deformed form)
Not limited to each of the embodiments described above, various modifications and changes are possible, and these are also within the scope of the present invention.
(1) In the first embodiment, an example is shown in which the protective layer 15 contains a coloring material and becomes a light absorbing layer having a light absorbing action, but the present invention is not limited to this, and for example, the second optical is not the protective layer 15. The shape layer 14 may contain a coloring material or the like and have a light absorbing action, or the protective layer 15 and the second optical shape layer 14 may contain a coloring material and have a light absorbing action.
Further, in the second embodiment, in addition to the light absorbing layer 26, at least one of the protective layer 25 and the second optical shape layer 14 may be colored with a coloring material to have a light absorbing action.
Further, in the second embodiment, in addition to the light absorption layer 26, the screen 20 has a higher light transmittance (lower absorption rate) than the light absorption layer 26 on the image source side (+ Z side) of the reflection layer 13. ) It may be in the form of having a second light absorption layer. The same applies to the first embodiment, and a layer corresponding to the second light absorption layer may be further provided on the image source side of the reflection layer 13.

Further, in the second embodiment, a light absorption layer may be provided between the reflection layer 13 and the second optical shape layer 14. In this case, the second optical shape layer 14 in which a plurality of second unit optical shapes, which are the reverse of the unit optical shape 121, are arranged on the surface on the image source side is formed by an ultraviolet curable resin or the like, and the light absorption layer is formed. A material having a light absorbing action can be formed by depositing a material having a light absorbing action into a second unit optical shape or the like.
Further, in each embodiment, the layer having a light absorbing function may be an uncolored, transparent layer having a light absorbing function.
Further, in the first embodiment and the second embodiment, the protective layer 15 and the light absorption layer 26 may have a form in which the absorption rate of the light is increased and most of the external light from the back surface side is shielded.

(2) For each embodiment, the reflective layers 13 and 33 are shown as an example formed on the unit optical shape 121, but the present invention is not limited to this. For example, the reflective layers 13 and 33 are layers parallel to the screen surface. Therefore, a fine and irregular uneven shape may be formed on the surface on the image source side and the surface on the back surface side.

(3) In each embodiment, an example in which the protective layer 15 and the light absorbing layer 26 are colored and have light absorption is shown, but the present invention is not limited to this, and for example, as a form in which the reflective layer has a function of absorbing light. May be good.
FIG. 8 is a diagram illustrating a modified screen 30. The cross section of the screen 30 in the modified form shown in FIG. 8 corresponds to the cross section of the screen 10 shown in FIG. 2 of the first embodiment described above.
The protective layer 35 of the screen 30 in this modified form is a transparent layer that does not contain a coloring material or the like. The light transmittance and absorption rate of the protective layer 35 and the second optical shape layer 14 of the screen 30 are equal to the light transmittance and absorption rate of the base material layer 11 and the first optical shape layer 12.
In the modified form of the reflective layer 33, the absorption rate when the light incident from the back surface side (−Z side) is reflected is larger than the absorption rate when the light incident from the image source side (+ Z side) is reflected. Further, the reflective layer 33 has the same reflectance for light incident on the screen surface from the image source side at an incident angle of 0 ° and the reflectance for light incident on the screen surface from the back surface side at an incident angle of 0 °.
The reflective layer 33 is formed of, for example, a metal vapor deposition film such as aluminum or silver.

Since the reflection layer 33 as described above is provided, the screen 30 in the modified form has a light absorption rate of the back surface side region Sb higher than the light absorption rate of the image source side region Sa.
Even in such a form, it is possible to realize a screen and an image display device capable of displaying a high-contrast image while maintaining high transparency.
Further, in such a form, each layer on the image source side and the back surface side of the reflection layer 33 is transparent, and the transmittance and the like are the same. Therefore, either the image source side or the back surface side of the screen is used. High transparency can be achieved even when viewed from the perspective.

(4) In each embodiment, a hard coat layer for the purpose of preventing scratches may be provided on the surface of the screens 10 and 20 on the image source side (+ Z side). For the hard coat layer, for example, an ultraviolet curable resin having a hard coat function (for example, urethane acrylate or the like) is applied to the surface of the screens 10 and 20 on the image source side (the surface of the base material layer 11 on the image source side). It is formed by forming the film.
Further, not limited to the hard coat layer, a layer having appropriate necessary functions such as an antireflection function, an ultraviolet absorption function, an antifouling function, an antistatic function, etc., depending on the usage environment and purpose of use of the screens 10 and 20. May be provided by selecting one or more. Further, a touch panel layer or the like may be provided on the image source side (observer side) of the base material layer 11.
In particular, in the antireflection layer, for example, the image light reflected by the reflection layer 13 is reflected at the interface with the air on the image source side, is emitted from the back side, and is displayed as if the image leaked to the back side. Can be prevented.
The screens 10 and 20 may be provided with a layer having a hard coat function, an antireflection function, or the like on the surface on the back surface side, not limited to the surface on the image source side (+ Z side) of the screens 10 and 20.

(5) In each embodiment, the image source LS has been described with reference to an example in which the image source LS is located at the center of the screens 10 and 20 in the left-right direction in the vertical direction and below in the vertical direction. , 20 may be arranged diagonally below the screens 10 and 20, and the image light may be projected from the diagonal light in the left-right direction of the screen with respect to the screens 10 and 20.
FIG. 9 is a diagram showing a modified form of the video display device 1A.
In FIG. 9, for ease of understanding, the first optical shape layer of the screen 10A shows an example in which columnar unit optical shapes 221A are arranged on the back side and has a linear Fresnel lens shape, but the present invention is limited to this. Instead, it may have a circular Fresnel lens shape as in each of the above-described embodiments, or it may have a plurality of columnar unit prisms.
As shown in FIG. 9, for example, when the image source LS is arranged below the left side (-X side) of the screen 10A in the left-right direction of the screen, the unit optical shape 121 has an arrangement direction and a longitudinal direction of the image source LS. It is tilted with respect to the vertical direction (Y direction) and the horizontal direction (X direction) of the screen according to the position, respectively. With such a form, the position of the image source LS and the like can be freely set.
Even when the first optical shape layer has a circular Fresnel lens shape as in the screens 10 and 20 shown in the above-described embodiments, the arrangement direction of the unit optical shape 121 is tilted according to the position of the image source LS. Such a modified form can be applied.

(6) In each embodiment, the unit optical shape 121 shows an example in which the first slope 121a and the second slope 121b are formed by a flat surface, but the present invention is not limited to this, and for example, a curved surface and a flat surface are combined. It may be in the form or a folded surface.
Further, in each embodiment, the unit optical shape 121 may be a polygonal shape formed by a plurality of three or more surfaces.
Further, in each embodiment, the example in which the reflective layer 13 is formed on the first slope 121a and the second slope 121b is shown, but the present invention is not limited to this, and for example, the reflective layer 13 is formed on at least a part of the first slope 121a. It may be in the form.
Further, in each embodiment, the first slope 121a and the second slope 121b are rough surfaces in which fine uneven shapes are formed, but the present invention is not limited to this, and only the first slope 121a is a rough surface. It may be in the form.

(7) In the second embodiment, the screen 20 has a base material layer 11 and a protective layer 25 when the first optical shape layer 12 and the second optical shape layer 14 have sufficient thickness, rigidity, and the like. It may be a form not provided with, or a form not provided with either one.
Further, in the first embodiment, the screen 10 does not include the base material layer 11 when the first optical shape layer 12 and the second optical shape layer 14 have sufficient thickness, rigidity, and the like. It is also good.
Further, in each embodiment, the screens 10 and 20 may have at least one of the base material layer 11 and the protective layer 25 as a plate-shaped member having light transmittance such as a glass plate. At this time, the first optical shape layer 12 or the like may be bonded to the glass plate or the like via the pressure-sensitive adhesive layer or the like.

(8) In each embodiment, the image source LS may project, for example, image light having a polarization component of a P wave.
At this time, the position and angle of the image source LS are set so that the image light is projected onto the screens 10 and 20 at the incident angle φ. This incident angle φ is (θb-10) ° or more when the incident angle (Brewster angle) at which the reflectance of the image light (P wave) projected on the screens 10 and 20 becomes zero is θb (°). It is set in the range of 85 ° or less. For example, when the incident angle θb at which the reflectance of the video light projected on the screens 10 and 20 becomes zero is 60 °, the incident angle φ of the video light is set in the range of 50 to 85 °.
In this way, by using the image source LS that projects the image light having the polarization component of the P wave, the specular reflection on the surface of the screens 10 and 20 is suppressed even when the incident angle φ to the screens 10 and 20 is large. This makes it possible to increase the degree of freedom in designing the projection system, such as the installation position of the image source LS. Further, by using such an image source LS, it is possible to reduce the reflection of the image light on the screen surface when incident on the screens 10 and 20, and it is possible to improve the brightness and sharpness of the image.
The angle θb (Brewster's angle) differs depending on the surface material of the screens 10 and 20 on which the image light is projected.
Further, in such a form, a sheet-shaped member made of TAC is suitable as the base material layer 11 and the protective layers 15 and 25.

(9) In each embodiment, the image display device 1 has been shown as an example of being arranged in a show window of a store or the like, but the present invention is not limited to this, and is not limited to this, for example, for indoor partitions, image display at exhibitions, and the like. Can also be applied. Further, the image display device 1 may be applied to an automobile head-up display (HUD: HEAD-Up Display) by attaching screens 10 and 20 to the windshield, or may be applied to vehicles other than automobiles. good.

Although the present embodiment and the modified form can be used in combination as appropriate, detailed description thereof will be omitted. Further, the present invention is not limited to each of the embodiments described above.

1 Video display device 10, 20 Screen 11 Base material layer 12 First optical shape layer 13 Reflective layer 14 Second optical shape layer 15, 25 Protective layer 26 Light absorption layer LS Video source

Claims (10)

An image source that projects image light and
A semi-transmissive reflective screen that reflects the image light projected from the image source and displays the image ,
It is a video display device equipped with
The image source is located on the lower side in the vertical direction with respect to the screen of the reflective screen when the screen of the reflective screen is viewed from the front direction.
The reflective screen is
A semi-transmissive reflective layer that reflects part of the incident light and transmits the others,
At least one layer on the image source side of the reflection layer, which has light transmission property, and a layer on the image source side.
At least one light-transmitting back-side layer provided on the back-back side of the reflection layer,
Equipped with
When the area from the surface on the image source side to the surface on the back surface side of the reflection layer is the image source side region and the area from the surface on the image source side of the reflection layer to the surface on the back surface side is the back surface area in the thickness direction of the reflection screen. The absorption rate of the light in the back surface region with respect to the light incident on the screen surface of the reflection screen from the back surface side at an incident angle of 0 ° is the light incident on the screen surface of the reflection screen from the image source side at an incident angle of 0 °. Greater than the light absorption rate of the image source side region with respect to
The image source side layer has light transmission and has an optical shape layer in which a plurality of unit optical shapes are arranged at a constant arrangement pitch on the back surface side.
The unit optical shape includes a first surface inclined with respect to the screen surface of the reflective screen and a second surface connected to the first surface and provided so as to face the first surface. Have and
The first surface is inclined in a direction in which the image light projected from the image source is reflected toward the image source side.
The reflective layer is formed on the first surface and the second surface of the unit optical shape.
The reflective layer has a fine and irregular uneven shape formed on its surface.
In a cross section orthogonal to the screen surface of the reflective screen and in a direction along the arrangement direction of the unit optical shape.
Let θ1 be the angle at which the line segment connecting the position on the most image source side of the first surface and the position on the backmost side of the first surface is parallel to the screen surface.
Assuming that the angle formed by the line segment connecting the position on the most image source side of the second surface and the position on the backmost side of the second surface with the surface parallel to the screen surface is θ2, the relationship θ2> θ1 is established. Meet and
In the arrangement direction of the unit optical shape, the amount of angle change from the emission angle which is the peak brightness of the reflected light of the reflection screen to the emission angle where the brightness is halved is set to + α1 and −α2, and the average value of the absolute values thereof. When α is defined as α and the refractive index of the optical shape layer is n, the relationship of α <arcsin (n × sin (2 × (θ1))) is satisfied in at least a part of the reflective screen.
A video display device characterized by. In the video display device according to claim 1,
The transmittance of light incident on the screen surface of the reflective screen at an incident angle of 0 ° is 10 to 85%.
A video display device characterized by. In the video display device according to claim 1 or 2.
The absorption rate of light incident on the screen surface of the reflective screen at an incident angle of 0 ° is 10 to 30%.
A video display device characterized by. The video display device according to any one of claims 1 to 3.
The light incident on the screen surface of the reflective screen from the back side at an incident angle of 0 ° is reflected by the reflective layer and emitted from the back side, and the reflectance is the incident angle of 0 ° from the image source side on the screen surface of the reflective screen. The light incident in is smaller than the reflectance emitted from the image source side by being reflected by the reflection layer.
A video display device characterized by. The video display device according to any one of claims 1 to 4.
A light absorption layer that absorbs light in the back surface region from the back surface to the image source side of the reflection layer in the thickness direction of the reflection screen and sets the light transmittance of the reflection screen to a predetermined value. To have at least one,
A video display device characterized by. The video display device according to any one of claims 1 to 5.
5 ° ≤ α ≤ 45 °,
A video display device characterized by. The video display device according to any one of claims 1 to 6 .
The image source side layer has light transmission, and has an optical shape layer on the back surface side in which a plurality of the unit optical shapes are arranged to form a circular Fresnel lens shape.
The optical center of the circular Fresnel lens shape is outside the display area of the reflective screen.
The reflective layer is formed on at least a part of the first surface of the unit optical shape.
A video display device characterized by. The video display device according to any one of claims 1 to 7 .
The image source side layer has a light transmissive property, and is a first optical shape layer in which a plurality of unit optical shapes are arranged on the back surface side.
An image source-side surface layer provided on the image source side of the first optical shape layer in any of a plate-like, sheet-like, and film-like form.
Have,
The back surface side layer has a light transmissive property, and has a second optical shape layer provided on the back surface side of the first optical shape layer.
A back side surface layer provided on the back side of the second optical shape layer in the form of a plate, a sheet, or a film.
Have,
The reflective layer is arranged so as to be sandwiched between the image source side surface layer and the back surface side surface layer.
A video display device characterized by. In the video display device according to claim 8 ,
The back surface layer has light absorption.
A video display device characterized by. The video display device according to any one of claims 1 to 9 .
The image source projects the image light of the P wave as the angle of incidence φ on the screen surface of the reflection screen.
When the incident angle at which the reflectance of the image light of the P wave projected on the reflection screen becomes zero is θb (°),
(Θb-10) ° ≤ φ ≤ 85 °
Satisfying the relationship,
A video display device characterized by.

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