JP2022109279A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection screen that is highly transparent and can display excellent images, and to provide a display device having the same.

SOLUTION: A screen 10 has a semi-transmissive reflective layer 13 for reflecting one portion of incident light and for transmitting the others. When the total Sp of light entering from an image source side at an incidence angle of 0° is taken as 100%, the sum of transmittance Tp(%), and a reflection factor Rp(%) is equal to or less than 90%, absorptance Ap(%) is equal to or more than 10%, the transmittance Tp ranges from 10 to 85%, and the absorptance Ap(%) ranges from 10 to 30%, and then absorptance of light in a rear side region Sb relative to light entering a screen surface of the screen 10 from a rear side at the incidence angle of 0° is larger than absorptance of light in an image source side region Sa relative to light entering the screen surface of the screen 10 from the image source side at the incidence angle of 0°.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a reflective screen that reflects and displays projected image light, and an image display device having the same.

2. Description of the Related Art Conventionally, various kinds of reflective screens have been developed for reflecting and displaying image light projected from an image source (see, for example, Patent Document 1). Above all, it can be used as a reflective screen that reflects the projected image light so that the image can be viewed well by attaching it to a highly translucent member such as a window glass, and it does not project the image light. Demand for semi-transmissive reflective screens through which the scenery on the other side of the screen can be seen through when in use is increasing due to their high designability and the like.

JP-A-9-114003

However, if such a semi-transmissive reflective screen is provided with a diffusion layer containing diffusion particles or the like, the scenery on the other side of the screen will appear whitish and blurry, resulting in a deterioration in design. improvement was an issue. In addition, various screens are always required to be thin and to display good images with high contrast.
The above-mentioned Patent Document 1 proposes a screen that can be used for both transmission type and reflection type, and is capable of transmitting light from the rear side. However, this Patent Document 1 does not disclose any countermeasures for improving transparency.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reflective screen that is highly transparent and capable of displaying a good image, and an image display device that includes the same.

The present invention solves the above problems by means of the following solutions. In order to facilitate understanding, reference numerals corresponding to the embodiments of the present invention are used for description, but the present invention is not limited to these.
A first invention is a semi-transmissive reflective screen for displaying an image by reflecting image light (L) projected from an image source, wherein a part of the incident light is reflected and the rest is transmitted. A transmissive reflective layer (13), at least one image source side layer (11, 12) having optical transparency provided on the image source side of the reflective layer, and at least one layer on the back side of the reflective layer. and a rear side layer (14, 15, 25, 26) having light transmittance is provided, and the total amount Sp of light incident on the screen surface of the reflective screen from the image source side at an incident angle of 0° is calculated. When 100%, the sum of the transmittance Tp (%) transmitted to the back side and the reflectance Rp (%) reflected by the reflective layer and emitted to the image source side is 90% or less. The light absorptance Ap (%) in the reflective screen is 10% or more. When the image source side area (Sa) and the area from the image source side surface (13a) to the back side surface (10b) of the reflective layer is the back side area (Sb), the screen surface of the reflective screen has a The light absorptance of the back side region with respect to the light incident at an incident angle of 0° is the light absorptance of 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°. A reflective screen (10, 20) characterized in that it is larger than
A second invention is the reflective screen according to the first invention, wherein 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 a reflective screen (10, 20) characterized in that the absorptivity of light incident at an incident angle of 0° is 10-30%.
A third invention is the reflective screen according to the first invention or the second invention, wherein the light incident on the screen surface of the reflective screen from the rear side at an incident angle of 0° is reflected by the reflective layer (13). the reflectance emitted from the back side of the reflective screen is smaller than the reflectance of the light incident on the screen surface of the reflective screen from the image source side at an incident angle of 0° and reflected by the reflective layer and emitted from the image source side; A reflective screen (10, 20) characterized by

A fourth invention is the reflective screen according to any one of the first invention to the third invention, wherein the image source side layer has optical transparency, and a unit optical shape (121) is formed on the rear side surface. ) are arranged in a plurality, and the unit optical shape has a first surface (121a) on which image light is incident and a second surface (121b) opposite to the first surface (121a). and the reflecting layer (13) is formed on at least a part of the first surface of the unit optical shape (10, 20).
A fifth aspect of the present invention is the reflective screen according to any one of the first to fourth aspects, wherein the reflective layer (13) has fine and irregular irregularities formed on its surface. A reflective screen (10, 20) characterized by:
In a sixth invention, in the reflective screen according to any one of the first to fifth inventions, in the thickness direction of the reflective screen, from the back side surface (10b) to the image source side surface of the reflective layer characterized in that at least one light absorption layer (15, 26) is provided in the back side region (Sb) up to (13a) to absorb light and set the light transmittance of the reflective screen to a predetermined value. a reflective screen (10, 20).
A seventh invention is the reflective screen according to any one of the first invention to the sixth invention, wherein from the emission angle at which the reflected light of the reflection screen has the peak luminance to the emission angle at which the luminance is 1/2 are +α1 and −α2, and α is the average value of the absolute values, 5°≦α≦45°.
In an eighth invention, in the reflective screen according to any one of the first invention to the seventh invention, the image source side layer has optical transparency, and a unit optical shape (121) is formed on the rear surface side. ) are arranged in a plurality, and the unit optical shape has a first surface (121a) on which image light is incident and a second surface (121b) opposite to the first surface (121a). Then, in the arrangement direction of the unit optical shapes, the angle change amounts from the emission angle at which the reflected light of the reflecting screen has the peak luminance to the emission angle at which the luminance is 1/2 are defined as +α1 and -α2, and the absolute values thereof Let α be the average value, and let θ1 be the angle formed by the first surface with a plane parallel to the screen surface. ))).
In a ninth invention, the reflective screen according to any one of the first invention to the eighth invention, and the image source side layer has light transmissivity, and image light is incident on the back side surface. An optical shape layer (12) in which a circular Fresnel lens shape is formed by arranging a plurality of unit optical shapes (121) having a first surface (121a) and a second surface (121b) facing the first surface (121a) and the optical center (C) of the circular Fresnel lens shape is outside the display area of the reflective screen, and the reflective layer (13) is formed on at least part of the first surface of the unit optical shape. A reflective screen (10, 20) characterized in that

A tenth aspect of the invention provides an image comprising: the 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. A display device (1).
In an eleventh aspect based on the image display device according to the tenth aspect, the incident angle of the image light (L) projected by the image source (LS) onto the screen surface of the reflection screen (10, 20) is An image display device (1) characterized by being larger than 0°.

Advantageous Effects of Invention According to the present invention, it is possible to provide a reflective screen that is highly transparent and capable of displaying good images, and an image display device that includes the same.

It is a figure which shows the video display apparatus 1 of 1st Embodiment. It is a figure explaining layer constitution of screen 10 of a 1st embodiment. 2 is a view of the first optically shaped layer 12 of the first embodiment viewed from the rear side (−Z side). FIG. It is a figure explaining the relationship between 1/2 angle (alpha), incident angle (phi) of image light, and angle (theta)1 of the 1st slope 121a. It is a figure explaining the transmittance|permeability of the light of the screen 10 of 1st Embodiment, and absorptivity. 4A and 4B are diagrams showing states of image light and external light on the screen 10 of the first embodiment; FIG. It is a figure explaining the layer structure of the screen 20 of 2nd Embodiment. It is a figure explaining the layer structure of the screen 30 of a deformation|transformation. It is a figure which shows 1 A of video display apparatuses of a deformation|transformation.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, each figure shown below including FIG. 1 is a schematic diagram, and the size and shape of each part are appropriately exaggerated for easy understanding.
In this specification, terms that specify shapes and geometric conditions, for example, terms such as parallel and orthogonal, have the same optical function and can be regarded as parallel or orthogonal in addition to the strict meaning. It shall include the state with an error of

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

(First embodiment)
FIG. 1 is a diagram showing an image display device 1 according to 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. FIG.
The video display device 1 has a screen 10, a video source LS, and the like. The screen 10 of this embodiment is a reflective screen that reflects the image light L projected from the image source LS to display an image on the screen. The details of this screen 10 will be described later.
In this embodiment, as an example, the image display device 1 is applied to a shop window, and the screen 10 is fixed to the glass of the shop window.

Here, in order to facilitate understanding, an XYZ orthogonal coordinate system is appropriately provided and shown in each figure shown below including FIG. In this coordinate system, the horizontal direction (horizontal direction) 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 .
In addition, the +X direction is the direction toward the right side in the horizontal direction as viewed from the observer O1 positioned in the front direction of the image source side of the screen 10, the +Y direction is the direction toward the upper side in the vertical direction, and the back side (back side) in the thickness direction. ) toward the image source side (observer side) is the +Z direction.
Furthermore, in the following description, unless otherwise specified, the up-down direction of the screen, the left-right direction of the screen, and the thickness direction refer to the up-down direction of the screen (vertical direction), the left-right direction of the screen (horizontal direction), It is the thickness direction (depth direction) and is parallel to the Y direction, X direction, and 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 projector.
This image source LS is located at the center of the screen 10 in the horizontal direction when the screen (display area) of the screen 10 is viewed from the front (the direction normal to the screen surface) when the image display device 1 is in use. , and positioned below the screen of the screen 10 in the vertical direction.
The image source LS can obliquely project the image light L from a position that is significantly closer to the surface of the screen 10 in the depth direction (Z direction) than a conventional general-purpose projector positioned in the front direction of the screen. . Therefore, compared to conventional general-purpose projectors, the image source LS has a short projection distance to the screen 10 and a large incident angle at which the projected image light enters the screen 10 .

The screen 10 can reflect the image light L projected by the image source LS toward the observer O1 positioned in the front direction of the image source side, and can display the image, and the image can be displayed on the other side of the screen 10 (back side, - Z side) is a transflective screen that allows observation of the landscape.
The screen (display area) of the screen 10 has a substantially rectangular shape when viewed from the observer O1 side, and the long side direction is the horizontal direction of the screen when in use.
The screen 10 has a large screen size of about 80 to 100 inches diagonally, and the aspect ratio of the screen is 16:9. However, the size is not limited to this, and the size 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.

Generally, the screen 10 is a laminate of thin resin layers or the like, and in many cases, it alone does not have sufficient rigidity to maintain flatness. Therefore, as shown in FIG. 1B, etc., the screen 10 of the present embodiment is bonded (or partially fixed) to the support plate 50 via a bonding layer 51 having light transmittance on the back side thereof, and the screen is maintains the flatness of
The support plate 50 is a plate-shaped member having light transmission properties and high rigidity, and a plate-shaped member made of resin such as acrylic resin or PC resin, glass, or the like can be used.
In this embodiment, the support plate 50 is a window glass of a show window of a store or the like. The screen 10 is not limited to this, and the screen 10 may be configured such that its four sides and the like are supported by frame members and the like (not shown) to maintain its flatness.

FIG. 2 is a diagram for explaining the layer structure of the screen 10 of the first embodiment. In FIG. 2, the point A (see FIGS. 1A and 1B), which is the center of the screen (the geometric center of the screen) of the screen 10, is parallel to the screen up-down direction (Y direction). A part of the cross section orthogonal to the plane (parallel to the Z direction) is shown enlarged. 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 optically shaped layer 12 of the first embodiment viewed from the back side (−Z side). For easy understanding, the reflective layer 13, the second optical shape layer 14, the protective layer 15, etc. are omitted.
As shown in FIG. 2, the screen 10 includes a substrate layer 11, a first optically shaped layer 12, a reflective layer 13, and a second optically shaped layer 11 in order from the image source side (+Z side) in the thickness direction (Z direction). A layer 14, a protective layer 15 and the like are provided.

The base material layer 11 is a sheet-like member having optical transparency, and the first optically shaped layer 12 is integrally formed on the back side (−Z side) thereof. This substrate layer 11 is a layer that serves as a substrate (base) for forming the first optical shape layer 12 .
The base material layer 11 is formed of, for example, polyester resin such as PET (polyethylene terephthalate), acrylic resin, styrene resin, acrylic styrene resin, PC (polycarbonate) resin, alicyclic polyolefin resin, TAC (triacetylcellulose) resin, or the like. 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 layer having optical transparency formed on the back side (−Z side) of the base layer 11 . A plurality of unit optical shapes (unit lenses) 121 are arranged and provided on the back side (−Z side) surface of the first optical shape layer 12 . As shown in FIG. 3, the unit optical shapes 121 are arranged concentrically with a point C located outside the screen (display area) of the screen 10 as the center. That is, the first optical shape layer 12 has a circular Fresnel lens shape on the back 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 with the point C as the center (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, a unit optical shape (unit lens) 121 having a partial shape (arcuate shape) of a perfect circle is formed. It is observed that multiple arrays are arranged. As shown in FIG. 3, this point C is located at the center of the screen in the horizontal direction and below the screen. Therefore, when the screen 10 is viewed from the front direction, the points C and A are located on the same straight line.

In the present embodiment, an example in which a circular Fresnel lens shape is formed on the back side surface of the first optically shaped layer 12 is shown, but not limited to this, the back side of the first optically shaped layer 12 On the surface, a linear Fresnel lens shape may be formed in which the unit optical shapes 121 are arranged in the horizontal direction (X direction) of the screen and arranged in the vertical direction (Y direction) of the screen.

As shown in FIG. 2, the unit optical shape 121 is parallel to the direction perpendicular to the screen surface (the Z direction) and has a substantially triangular cross-sectional shape in a cross section parallel to the arrangement direction of the unit optical shape 121. .
The unit optical shape 121 is convex on the back side, and has a first slope (lens surface) 121a on which image light is incident and a second slope (non-lens surface) 121b facing thereto. In one unit optical shape 121, the first slope 121a is positioned above (+Y side) the second slope 121b across the vertex t.
The angle between the first slope 121a and the plane parallel to the screen surface is θ1. The angle between the second slope 121b and the plane parallel to the screen surface 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 fine and irregular uneven shapes. The fine concave-convex shape is formed by irregularly arranging convex shapes and concave shapes in two-dimensional directions, and the convex shapes and concave shapes are irregular in size, shape, height, and the like.

The arrangement pitch of the unit optical shapes 121 is P, and the height of the unit optical shapes 121 (the dimension from the vertex t to the valley bottom point v between the unit optical shapes 121 in the thickness direction) is h.
In order to facilitate understanding, FIG. 2 shows an example in which the arrangement pitch P and the angles θ1 and θ2 of the unit optical shapes 121 are constant in the arrangement direction of the unit optical shapes 121 . However, in the unit optical shapes 121 of this embodiment, although the arrangement pitch P is actually constant, the angle θ1 gradually increases with increasing distance from the point C, which is the Fresnel center, in the arrangement direction of the unit optical shapes 121. .
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 incident angle of the image light to the screen 10), the size of the pixels of the image source LS, and the screen 10. may be appropriately set according to the screen size of the screen, the refractive index of each layer, and the like. For example, along the direction in which the unit optical shapes 121 are arranged, the arrangement pitch P may change, and the angles θ1 and θ2 may change.

The first optically shaped layer 12 is made of UV curable resin such as urethane acrylate, polyester acrylate, epoxy acrylate, polyether acrylate, polythiol, butadiene acrylate, etc., having high light transmittance.
In the present embodiment, an ultraviolet curable resin will be described as an example of the resin forming the first optically shaped layer 12. However, the resin is not limited to this, and other ionizing radiation such as an electron beam curable resin It may be formed from 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). The reflective layer 13 is a semi-transmissive reflective layer that reflects part of the incident light and transmits the rest, that is, a so-called half mirror.
As described above, the first slope 121a and the second slope 121b are formed with fine unevenness, and the reflective layer 13 is formed so as to follow this fine unevenness. Also, the thickness of the reflective layer 13 is sufficiently thinner than the unevenness of the fine unevenness. Therefore, the surface of the reflective layer 13 on the image source side (the surface on the side of the first optically shaped layer 12) and the surface on the back side (the surface on the side of the second optically shaped layer 14) have fine and irregular uneven shapes. It has a matte surface.
The reflective layer 13 has a function of diffusing and reflecting a portion of the incident light by means of fine irregularities and transmitting the other light that is not reflected without diffusing.

The surface roughness of the image source side surface of the reflective layer 13 (that is, the surface roughness of the first slope 121a) has an arithmetic mean roughness Ra (JIS B0601-2001) of about 0.10 to 0.50 μm. This is preferable from the viewpoint of good image display by reflected light. The arithmetic average roughness Ra, which is the surface roughness of the image source side surface of the reflective layer 13 (that is, the surface roughness of the first slope 121a), may be appropriately selected according to 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.

In addition, the reflective layer 13 has a non-rough surface region, that is, it does not have a fine uneven shape, and the surface on the image source side (the surface on the first optical shape layer 12 side) is mirror-finished. In order to sufficiently diffuse the image light and obtain a good viewing angle, the specular area where the projected image light is mirror-reflected is 5% or less per unit area of the reflective layer 13 formed on the first slope 121a. and ideally 0%.
If the non-roughened specular area exceeds 5% per unit area of the reflective layer 13 formed on the first slope 121a, the components of the image light that are reflected without being diffused may cause bright lines or decrease the viewing angle. It is not preferable because

Such a reflective layer 13 is made of a highly light-reflective metal such as aluminum, silver, or nickel, and has a thickness of several tens of angstroms. The reflective layer 13 of this embodiment is formed by vapor-depositing aluminum.
Note that the reflective layer 13 is not limited to this, and may be formed by, for example, sputtering a metal with high light reflectivity, transferring a metal foil, or applying a paint containing a thin metal film. . Alternatively, the reflective layer 13 may be formed by depositing a dielectric multilayer film.

The second optically shaped layer 14 is a layer having optical transparency provided on the back side (−Z side) of the first optically shaped layer 12 . The second optical shape layer 14 is provided to flatten the back side (−Z side) surface of the first optical shape layer 12, and is formed so as to fill the valleys between the unit optical shapes 121. there is Therefore, the image source side (+Z side) surface of the second optical shaped layer 14 is formed by arranging a plurality of substantially reversed shapes of the unit optical shapes 121 of the first optical shaped 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 side surface of the screen 10, and the support plate 50 and the like can be easily laminated. Joining is also facilitated.
The refractive index of the second optically shaped layer 14 is preferably the same as that of the first optically shaped layer 22, and the second optically shaped layer 14 is made of the same UV curable resin as the first optically shaped layer 12 described above. preferably formed. In this embodiment, the second optically shaped layer 14 is made of the same resin as the first optically shaped layer 12 .

The protective layer 15 is a layer formed on the back side (−Z side) of the second optical shape layer 14 and is a sheet-like member having a function of protecting the back side of the screen 10 . The protective layer 15 is a light absorption layer that is colored with a coloring material such as gray or black dyes or pigments and has light absorption properties. In addition, the protective layer 15 has its coloring density and layer thickness set so that the light transmittance of the screen 10 has 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 (methacrylstyrene) resin, and MBS (methacrylbutadiene styrene). A resin or the like is suitable. Also, the base material of the protective layer 15 may be the same material as the base material layer 11 described above.
Colorants contained in the protective layer 15 include dark dyes and pigments such as gray and black, and metal salts such as carbon black, graphite, and black iron oxide.
The thickness, light transmittance, absorptivity, etc. of the protective layer 15 may be appropriately adjusted according to the screen size of the screen 10 and desired optical performance.
As described above, the screen 10 of the present embodiment does not include a light diffusion layer containing a diffusing material such as particles having a diffusing action. Only shape.

The screen 10 is formed, for example, by the following manufacturing method.
A base material layer 11 is prepared, laminated on one surface thereof in a state in which a molding die for shaping the unit optical shape 121 is filled with an ultraviolet curable resin, and irradiated with ultraviolet rays to cure the resin by a UV molding method. A first optical shape layer 12 is formed. At this time, fine irregularities are formed on the surfaces of the mold for shaping the unit optical shape 121 on which the first slope 121a and the second slope 121b are formed. This fine uneven shape can be formed by repeating plating two or more times under different conditions or by performing an etching process on the surface of the mold for forming the first slope 121a and the second slope 121b.
After the first optically shaped layer 12 is formed on one surface of the substrate 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, from above the reflective layer 13, an ultraviolet curable resin is applied so as to fill the valleys between the unit optical shapes 121 and form a flat surface, the protective layer 15 is laminated, and the ultraviolet curable resin is cured. , the second optical shape layer 14 and the protective layer 15 are integrally formed. After that, the screen 10 is completed by cutting to a predetermined size.
The base material layer 11 and the protective layer 15 may be in the shape of a sheet or in the shape of a web. For example, when the substrate layer 11 and the protective layer 15 are web-shaped, and the first optically shaped layer 12 has a linear Fresnel lens shape, the screen 10 before cutting can be continuously manufactured. Therefore, the production efficiency of the screen 10 can be improved and the production cost can be reduced.

Further, for example, as a method of forming rough surfaces on the first slope 121a and the second slope 121b, diffusion particles or the like are applied onto the first slope 121a and the second slope 121b, and the reflective layer 13 is formed thereon. , a method of performing blasting on the first slope 121a and the second slope 121b after forming the first optically shaped layer 12, and the like are known. However, when the reflective surface of the reflective layer 13 is roughened by such a manufacturing method, the dispersion characteristics, quality, etc., of the individual screens 10 vary greatly, and stable manufacturing 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 slopes 121a and second slopes 121b of the unit optical shape 121 with a molding die. Also in the case of manufacturing, there is an advantage that there is little variation in quality and it can be manufactured stably.

Here, the arrangement direction of the unit optical shapes 121 (this embodiment Let K1 and K2 be the angles at which the brightness is halved in the vertical direction of the screen), and the angle change amount from the angle K of the peak brightness to the angles K1 and K2 at which the brightness is halved is +α1 (however, K+α1 =K1), -α2 (K-α2=K2), the average value of the absolute values of the angle change amount from the peak brightness to the brightness being 1/2 is α (hereinafter referred to as 1/2 angle α ), the half angle α preferably satisfies 5°≦α≦45°.

If α<5°, the viewing angle becomes too narrow and the image becomes difficult to see, 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 decreases, the image blur increases, and the contrast of the image decreases due to the reflection of external light on the screen 10, which is preferable. do not have. Therefore, the 1/2 angle α is preferably within the above range.
In addition, 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 horizontal direction of the screen is equal or substantially equal to the 1/2 angle α in the vertical direction of the screen. .

FIG. 4 is a diagram for explaining the relationship between the ½ angle α, the incident angle φ of image light, and the angle θ1 of the first slope 121a. In FIG. 4, in order to facilitate understanding, the configuration inside the screen 10 is simplified, and the base layer 11 and the protective layer 15 are omitted. In FIG. 4, regarding the angles α and φ, the upper side of the screen is indicated by + and the lower side of the screen is indicated by -.
The angle θ1 of the first slope 121a is set so that the image light is most efficiently reflected to the viewer positioned in front of the screen 10, that is, the angle K at which the reflected light peaks in brightness is 0°. In addition, it is designed based on the refractive index of each layer. Also, the range from -α to +α is a range where it is assumed that an observer positioned in front of the screen can observe the image satisfactorily.
Here, at a certain point in the vertical direction of the screen (the direction parallel to the arrangement direction of the unit optical shapes 121 passing through the point A), the image light L is incident on the screen 10 from below at an incident angle of -φ, and 1. The light travels through the optical shape layer 12, is incident on the first slope 121a forming an angle .theta.1 with respect to the screen surface, is reflected by the reflective layer 13, and is emitted from the screen 10 in a direction orthogonal to the screen surface (emission angle 0.degree.). Then, the angle θ1 is represented by the following (Equation 1).
θ1=1/2×arcsin((sinφ)/n) (Formula 1)

When the image light is projected from the image source LS and reflected by the screen 10 to display the image as in the present embodiment, the light source of the image source LS that projects the image light is reflected and the contrast of the image is lowered. A problem may arise. The main cause of this reflection of the 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 should be positioned outside the angle range (-α to +α) where the observer can mainly observe the image satisfactorily on the surface of the screen 10. It is preferable that the image light reflected by . When a portion Lr of the image light L incident at the incident angle -φ is reflected by 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 (the arrangement direction of the unit optical shapes 121), the 1/2 angle α and the angle θ1 of the first slope 121a are , at least in a partial area of the screen 10 (for example, the center of the screen), the following (formula 2) is preferably satisfied.
α<arcsin(n×sin(2×(θ1))) (Formula 2)
Further, in order to prevent the reflection of the image source, it is more preferable that the ½ angle α and the angle θ1 of the first slope 121a satisfy the above (Equation 2) over the entire area of the screen 10 .
By setting the angle θ1 and the 1/2 angle α to satisfy the above (Equation 2), the direction in which the light reflected on the surface of the screen 10 when incident on the screen 10 (+φ direction) is mainly directed is It is outside the range (-α to +α) in which the image light reflected by the reflective layer 13 travels after being emitted from the screen 10 . As a result, it is possible to reduce the reflection of the image source LS in the range from -α to +α and display a good image with high contrast.

FIG. 5 is a diagram for explaining the light transmittance and absorbance of the screen 10 of the first embodiment. In FIG. 5, in order to facilitate understanding, the unit optical shapes 121 of the first optical shape layer 12 are omitted, and the reflective layer 13 is described as planar.
Regarding the light incident on the screen surface of the screen 10 of this embodiment from the image source side (+Z side) at an incident angle of 0°, when the total amount Sp is 100%, the transmittance transmitted to the back side (total light transmittance ) is Tp (%), the reflectance reflected by the reflective layer 13 and emitted to the image source side is Rp (%), and the absorptance absorbed in the screen 10 (from the total amount Sp, the transmittance Tp and the reflectance Rp) is Ap (%), the sum of the transmittance Tp and the reflectance Rp is 90% or less, and the absorptance Ap is 10% or more. That is, they satisfy the following expressions.
Tp+Rp≦90 (Formula 3)
Ap=Sp-(Tp+Rp)≧10 (Formula 4)

In addition, in the screen 10 of the present embodiment, the transmittance of the light La incident on the screen surface at an incident angle of 0° (corresponding to Tp described above) 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. Moreover, if the transmittance is higher than 85%, the brightness of the reflected image is lowered, which is not preferable. Therefore, the transmittance Tp preferably satisfies the above range.

In the screen 10 of the present embodiment, the absorptivity of light incident on the screen surface at an incident angle of 0° (corresponding to Ap described above) is 10° regardless of whether the light is incident from the image source side or from the back side. ~30%, more preferably 10-20%. That is, the absorption rate Ap preferably satisfies 10≦Ap≦30, and more preferably satisfies 10≦Ap≦20.
If this absorptivity is less than 10%, the contrast of the image is lowered, which is not preferable. On the other hand, if the absorptivity is higher than 30%, the brightness of the image displayed by reflection is lowered, and the transparency of the screen is lowered, which is not preferable. Therefore, the absorbance preferably satisfies the above range.

In the thickness direction of the screen 10, the area from the image source side surface 10a of the screen 10 to the back side (−Z side) surface 13b of the reflective layer 13 is defined as an image source side area Sa, and the back side surface 10b of the screen 10 is defined as an image source side area Sa. to the image source side (+Z side) surface 13a of the reflective layer 13 is defined as the back side region Sb, the absorption rate of light that is incident on the screen surface at an incident angle of 0° and is transmitted through the back side region Sb (hereinafter referred to as the light absorptivity of the back side area Sb) is the absorptance of light that enters the screen surface at an incident angle of 0° and is transmitted through the image source side area Sa (hereinafter referred to as the light absorptance of the image source side area Sa). absorption rate).

Here, the light absorptivity of the image source side area Sa and the light absorptivity of the back side area Sb are defined as 0 incident angle to the screen surface from the image source side (+Z side) and the back side (−Z side). , is reflected by the reflective layer 13 and emitted to the image source side and the rear side. The reflection layer 13 itself has the same reflectance for light incident from the image source side and light incident from the rear side.
The reflectance of the light Lc incident on the back side surface of the screen 10 of the present embodiment at an incident angle of 0° (hereinafter referred to as the reflectance of the light in the back side region Sb) is the incident angle It is smaller than the reflectance of the light Lb incident at 0° (hereinafter referred to as the reflectance of the image source side area Sa). That is, the amount of light incident on the back side surface 10b of the screen 10 at an incident angle of 0°, reflected by the reflective layer 13 and emitted to the back side of the screen 10 enters the image source side surface 10a of the screen 10 at an incident angle of 0°. It is smaller than the amount of light that is incident, reflected by the reflective layer 13, and emitted from the screen 10 toward the image source.

In this embodiment, the light reflectance of the image source side area Sa is about 40%, the light reflectance of the back side area Sb is about 30%, and the light transmittance Tp of the screen 10 as a whole is is the same 40% for both incident light from the rear side and incident light from the image source side. Therefore, the screen 10 has a higher reflectance in the image source side area Sa and a higher light absorption rate in the rear side area Sb.
By adopting such a form, when the other side of the screen 10 (image source side) is seen from the back side, or when the other side of the screen 10 (back side) is seen from the image source side, the screen 10 While maintaining high transparency, it is possible to absorb unnecessary illumination light and external light such as sunlight entering from the back side, and improve the contrast of the image. Moreover, since the protective layer 15 does not absorb the image light for displaying the image to the observer O1, the efficiency of using the image light necessary for displaying the image is maintained high, and a bright and clear image can be displayed.

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

Of the image light incident on the first slope 121a, the other image light L3 that is not reflected passes through the reflection layer 13 and exits from the back side (-Z side) of the screen 10. FIG. At this time, the image light L3 is emitted upward from the screen 10 and does not reach the observer O2 who is positioned in the front direction on the back side of the screen 10 .
Further, part of the image light L4 of the image light L1 projected from the image source LS is reflected by the surface of the screen 10 and travels upward on the screen 10 . At this time, since the angle of reflection of the image light L4 is larger than the 1/2 angle α or more as described above, it does not hinder the viewing of the image by the observer O1.
In this 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 on the screen 10 in the vertical direction. Light does not directly enter the second slope 121b, and the second slope 121b hardly affects the reflection of the image light.

Next, external light (hereinafter referred to as external light) such as sunlight other than image light incident on the screen 10 from the rear side (−Z side) or the image source side (+Z side) will be described.
As shown in FIG. 4, part of the external light G2 and G6 out of the external light G1 and G5 incident on the screen 10 is reflected by the surface of the screen 10 and travels toward the lower side of the screen. Part of the external light G3 of the external light G1 is reflected by the reflective layer 13, and part of it is emitted to the lower side of the screen 10. The light is totally reflected downward into the screen 10 and attenuated. Part of the external light G7 of the external light G5 is partially absorbed by the protective layer 15, reflected by the reflective layer 13, and emitted to the outside and upper side of the screen on the back side (−Z side). . Other external lights G4 and G8 that have not been reflected by the reflective layer 13 are transmitted through the reflective layer 13 and emitted toward the rear side and the image source side, respectively. At this time, external light G2, G3, and G8 emitted to the image source side does not reach the observer O1, so that a decrease in image contrast can be suppressed.

In addition, although not shown, part of the external light incident on the screen 10 from the image source side and the back side is totally reflected by the surface of the screen 10 on the back side and the image source side, travels downward inside the screen, and is attenuated. do.
Other external lights G9 and G10 are transmitted through the reflective layer 13, part of the light is absorbed by the light-absorbing protective layer 15, and the other light is emitted to the rear 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 lights G9 and G10 that pass 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 whitening.

In conventional transflective reflective screens with a diffusing layer containing diffusing particles, the image light is diffused twice before and after being reflected by the reflective layer. is a problem. In addition, the diffuser particles also diffuse the outside light, so the scenery on the other side of the screen is observed as blurry or white.

However, in the screen 10 of the present embodiment, the surface of the reflective layer 13 has no diffusing action except that the surface is rough with fine and irregular irregularities, so the image light is diffused only when it is reflected. . Moreover, in the screen 10 of this 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 with a good viewing angle and resolution, and the scenery on the other side of the screen 10 is not blurred or blurred, and the observer O1 can see it well. and high transparency can be achieved.
Further, in the screen 10 of the present embodiment, even when the image light is projected onto the screen 10, the observer O1 can partially see the scenery on the other side (back side) of the screen 10. Further, the observer O2 positioned on the back side of the screen 10 can visually recognize the scene on the image source side (+Z side) through the screen 10 with high transparency regardless of whether or not the image light is projected. can do.

Further, in the screen of the present embodiment, the reflectance of the back side area Sb is smaller than that of the image source side area Sa. That is, the light absorptance of the back side area Sb is higher than the light absorptance of the image source side area Sa.
Therefore, it is possible to absorb external light that enters from the back side (-Z side) and escapes to the image source side (+Z side), which adversely affects the visual recognition of the image of the observer O1, while having high transparency as a screen. It can display images with high contrast. Moreover, since the protective layer 15 does not absorb the image light that enters from the image source side and is reflected by the reflective layer 13 to display the image, the image light can be used with high efficiency 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 obtained by the above-mentioned (Equation 2) with respect to the ½ angle α of the image light (reflected light) diffusely reflected by the reflective layer 13. Therefore, the image light reflected on the surface of the screen 10 on the image source side is directed outward from the 1/2 angle α, so that the image source LS is not reflected and a good image can be displayed.

(Second embodiment)
FIG. 7 is a diagram for explaining the layer structure of the screen 20 of the second embodiment. FIG. 7 shows an enlarged part of the cross section of the screen 20 of the second embodiment. 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 includes a substrate layer 11, a first optically shaped layer 12, a reflective layer 13, and a second optically shaped layer in order from the image source side (+Z side) along the thickness direction (Z direction). 14 , a light absorbing layer 26 and a protective layer 25 . The screen 20 of the second embodiment can be used in the image display device 1 instead of the screen 10 of the first embodiment.
The screen 20 of the second embodiment has the same form as the screen 10 of the first embodiment described above, except that the protective layer 25 does not contain a coloring material and the light absorbing layer 26 is provided. Therefore, portions that perform the same functions as those of the first embodiment described above are denoted by the same reference numerals or the same reference numerals at the end thereof, and overlapping descriptions are 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 coloring material such as a dye or pigment such as gray or black. is a layer having The thickness and density of the light absorption layer 26 are set so that the transmittance of the screen 10 has a predetermined value.
This 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 that serves 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. Colorants for the light absorption layer 26 include dark dyes and pigments such as gray and black, and metal salts such as carbon black, graphite, and black iron oxide.
The light absorbing layer 26 of the present embodiment can be integrally laminated by, for example, co-extrusion molding with the protective layer 25 described later.
Note that the light absorption layer 26 is not limited to the above example, and may be formed by vapor-depositing a material having a light absorption effect on one side of the protective layer 25, or may be formed by coating. good.

The thickness of the light absorption layer 26 and the light transmittance and light absorption may be set according to the screen size of the screen 10 and desired optical performance.
In addition, in the present embodiment, an 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. side).

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

Also in the present embodiment, when the total amount Sp of 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 (% ), the reflectance Rp (%) reflected by the reflective layer 13 and emitted to the image source side, and the absorptivity Ap (%) absorbed in the screen 10 are expressed by the above-mentioned (Equation 3) and (Equation 4) meet.
Further, the screen 20 has a transmittance (corresponding to Tp described above) of light incident on the screen surface at an incident angle of 0°, which is 10 to 85% regardless of whether the light is incident from the image source side or from the rear side. be.
In addition, the absorptance of the light incident on the screen surface at an incident angle of 0° (corresponding to the aforementioned Ap) of the screen 20 is 10 to 30% regardless of whether the light is incident from the image source side or from the rear side. More preferably 10 to 20%.
Furthermore, the light transmittance and absorptance of the base material layer 11 and the first optically shaped layer 12 of the present embodiment are equal to the light transmittance and absorptance of the protective layer 25 and the second optically shaped layer 14 . Since the screen 20 of this 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 image source side region Sa, as in the first embodiment. greater than the absorption rate of light.
According to the present embodiment, as in the first embodiment described above, it is possible to realize the screen 20 and the image display device 1 capable of displaying high-contrast, bright and favorable images while maintaining high transparency.

(deformed form)
Various modifications and changes are possible without being limited to the embodiments described above, and they are also within the scope of the present invention.
(1) In the first embodiment, the example in which the protective layer 15 contains a coloring material and serves as a light absorbing layer having a light absorbing action is shown, but this is not restrictive. The shaped layer 14 may contain a coloring material or the like and have a light absorbing effect, or the protective layer 15 and the second optical shaped layer 14 may contain a coloring material and have a light absorbing effect.
Further, in the second embodiment, at least one of the protective layer 25 and the second optical shape layer 14 may be colored with a coloring material in addition to the light absorption layer 26 to have a light absorption effect.
Further, in the second embodiment, in addition to the light absorption layer 26, the screen 20 is positioned closer to the image source (+Z side) than the reflection layer 13, and has a higher light transmittance (lower absorption rate) than the light absorption layer 26. ) A configuration having a second light absorption layer may be employed. The same applies to the first embodiment, and a configuration in which a layer corresponding to the second light absorption layer is provided further on the image source side than the reflection layer 13 may be employed.

Further, in the second embodiment, a light absorption layer may be provided between the reflective layer 13 and the second optically shaped layer 14 . In this case, a second optical shape layer 14 in which a plurality of second unit optical shapes that are the inverse of the unit optical shapes 121 are arranged is formed on the surface on the image source side from an ultraviolet curable resin or the like. It can be formed by, for example, vapor-depositing a material having a light-absorbing effect on the second unit optical shape.
Further, in each embodiment, the layer having a light absorbing function may be a non-colored, transparent layer having a light absorbing function.
Further, in the first and second embodiments, the protective layer 15 and the light absorption layer 26 may have a configuration in which the absorption rate of light is increased and most of the external light from the rear side is blocked.

(2) In each embodiment, the reflective layers 13 and 33 are formed on the unit optical shape 121, but the present invention is not limited to this. , and may have a form in which fine and irregular uneven shapes are formed on the image source side surface and the back side surface.

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

Since the reflective layer 33 as described above is provided, the modified screen 30 has a higher light absorptance in the back side area Sb than in the image source side area 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 configuration, the layers on the image source side and the back side of the reflective layer 33 are transparent and have the same transmittance. High transparency can be achieved even when viewed from above.

(4) In each embodiment, a hard coat layer may be provided on the surface of the screens 10 and 20 on the image source side (+Z side) for the purpose of preventing scratches. The hard coat layer is formed, for example, by coating an ultraviolet curable resin (for example, urethane acrylate, etc.) having a hard coat function on the image source side surface of the screens 10 and 20 (the image source side surface of the base layer 11). It is formed by, for example, forming by
In addition, not only the hard coat layer, but also a layer having appropriate necessary functions such as antireflection function, ultraviolet absorption function, antifouling function, 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 of Furthermore, 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, emitted from the back side, and displayed as if the image leaked to the back side. can be prevented.
A layer having a hard coating function, an antireflection function, or the like may be provided not only on the image source side (+Z side) side of the screens 10 and 20 but also on the back side surface.

(5) In each embodiment, the image source LS is located at the center of the screens 10 and 20 in the left-right direction and on the bottom side in the vertical direction. , 20, and the image light may be projected onto the screens 10, 20 in the horizontal direction of the screen from oblique direction light.
FIG. 9 is a diagram showing a modified image display device 1A.
FIG. 9 shows an example in which the first optical shape layer of the screen 10A has a linear Fresnel lens shape in which columnar unit optical shapes 221A are arranged on the back side for easy understanding, but the present invention is not limited to this. Instead, it may have a circular Fresnel lens shape as in each of the above-described embodiments, or may have a form in which a plurality of columnar unit prisms are provided.
As shown in FIG. 9, for example, when the image source LS is arranged below the left side of the screen 10A in the left-right direction (-X side), the unit optical shape 121 is arranged such that the arrangement direction and the longitudinal direction of the image source LS are In accordance with the position, they are inclined with respect to the screen vertical direction (Y direction) and the screen horizontal direction (X direction). By adopting 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 like the screens 10 and 20 shown in the above embodiments, the arrangement direction of the unit optical shapes 121 is tilted according to the position of the image source LS. Such a modified form is applicable by adopting a modified form.

(6) In each embodiment, the unit optical shape 121 has shown an example in which the first slope 121a and the second slope 121b are formed by flat surfaces, but is not limited to this. For example, a curved surface and a flat surface are combined. It may be in the form of a folded surface.
Also, in each embodiment, the unit optical shape 121 may be a polygonal shape formed by three or more surfaces.
In each embodiment, the reflective layer 13 is formed on the first slope 121a and the second slope 121b, but the reflective layer 13 is not limited to this. It may be in the form
Further, in each embodiment, the first slope 121a and the second slope 121b are rough surfaces having fine irregularities, 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 includes the substrate layer 11 and the protective layer 25 when the first optically shaped layer 12 and the second optically shaped layer 14 have sufficient thickness and rigidity. It is good also as a form which does not have either, and it is good also as a form which does not have either.
Further, in the first embodiment, the screen 10 does not include the substrate layer 11 when the first optically shaped layer 12 and the second optically shaped layer 14 have sufficient thickness, rigidity, etc. good too.
In each of the embodiments, the screens 10 and 20 may have at least one of the substrate layer 11 and the protective layer 25 as a plate-like member having optical transparency such as a glass plate. At this time, the first optical shape layer 12 and the like may be joined to a glass plate or the like via an adhesive layer or the like.

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

(9) In each embodiment, the image display device 1 is arranged in a show window of a store, etc., but is not limited to this. can also be applied. Further, the screens 10 and 20 may be attached to the windshield, and the image display device 1 may be applied to a head-up display (HUD: HEAD-Up Display) of an automobile, or may be applied to a vehicle other than an automobile. good.

Although the present embodiment and modifications can be used in combination as appropriate, detailed description thereof will be omitted. Moreover, the present invention is not limited to each embodiment described above.

REFERENCE SIGNS LIST 1 image display device 10, 20 screen 11 substrate layer 12 first optically shaped layer 13 reflective layer 14 second optically shaped layer 15, 25 protective layer 26 light absorption layer LS image source

Claims (11)

an image source for projecting image light;
a transflective reflective screen that displays an image by reflecting image light projected from an image source;
A video display device comprising
The image source is positioned outside the screen of the reflective screen when the screen of the reflective screen is viewed from the front,
The reflective screen is
a semi-transmissive reflective layer that reflects part of the incident light and transmits the rest;
at least one light-transmissive image source-side layer provided on the image source side of the reflective layer;
a back side layer having at least one light transmissive layer provided on the back side of the reflective layer;
with
When the area from the image source side surface to the back side surface of the reflective layer in the thickness direction of the reflective screen is defined as the image source side area, and the area from the image source side surface to the back side surface of the reflective layer is defined as the back side area. , the absorptance of the light in the back side region with respect to the light incident on the screen surface of the reflective screen from the back side at an incident angle of 0° is the light incident on the screen surface of the reflective screen from the image source side at an incident angle of 0° greater than the light absorptance of the image source side region for
The image source side layer has optical transparency, and has an optical shape layer in which a plurality of unit optical shapes are arranged at a constant arrangement pitch on the back side surface,
The unit optical shape includes a first surface inclined with respect to the screen surface of the reflective screen, and a second surface connecting the first surface and provided facing the first surface. have
the first surface is inclined in a direction of reflecting image light projected from the image source toward the image source;
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 in a direction orthogonal to the screen surface of the reflective screen and along the arrangement direction of the unit optical shapes,
Let θ1 be an angle formed by a line segment connecting a position of the first surface closest to the image source and a position of the first surface closest to the back side and a plane parallel to the screen surface,
Let θ2 be the angle formed by the line segment connecting the position of the second surface closest to the image source and the position of the second surface closest to the back surface and the plane parallel to the screen surface, then the relationship θ2>θ1 is established. fulfilling,
An image display device characterized by: The image display device according to claim 1,
the angle θ2 is greater than the incident angle of the image light on the reflective screen 10;
An image display device characterized by: In the image display device according to claim 1 or claim 2,
The transmittance of light incident on the screen surface of the reflective screen at an incident angle of 0° is 10 to 85%;
An image display device characterized by: In the image display device according to any one of claims 1 to 3,
absorptivity of light incident on the screen surface of the reflective screen at an incident angle of 0° is 10 to 30%;
An image display device characterized by: In the image display device according to any one of claims 1 to 4,
The reflectance of 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 is 0° incident angle from the image source side on the screen surface of the reflective screen. The reflectance of the light incident on the reflective layer is smaller than the reflectance emitted from the image source side after being reflected by the reflective layer;
An image display device characterized by: In the image display device according to any one of claims 1 to 5,
A light absorption layer that absorbs light and sets the light transmittance of the reflection screen to a predetermined value in the back side region from the back side surface to the image source side surface of the reflection layer in the thickness direction of the reflection screen. comprising at least one
An image display device characterized by: In the video display device according to any one of claims 1 to 6,
5° ≤ α ≤ 45°;
An image display device characterized by: In the image display device according to any one of claims 1 to 7,
The image source side layer has optical transparency, and has an optical shape layer in which a plurality of the unit optical shapes are arranged to form a circular Fresnel lens shape on the back side surface,
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 part of the first surface of the unit optical shape;
An image display device characterized by: In the image display device according to any one of claims 1 to 8,
The image source side layer has a first optical shape layer having optical transparency and having a plurality of unit optical shapes arranged on the back side surface;
an image source side surface layer provided on the image source side of the first optical shape layer in any one of a plate shape, a sheet shape, and a film shape;
has
a second optical shape layer, wherein the back side layer has optical transparency and is provided on the back side of the first optical shape layer;
a back side surface layer provided on the back side of the second optical shape layer in any one of a plate-like, sheet-like, and film-like form;
has
wherein the reflective layer is sandwiched between the image source side surface layer and the back side surface layer;
An image display device characterized by: In the video display device according to claim 9,
The back side surface layer has light absorption,
An image display device characterized by: In the image display device according to any one of claims 1 to 10,
the image source projects P-wave image light at an incident angle φ onto the screen surface of the reflection screen;
When the incident angle at which the reflectance of the P-wave image light projected onto the reflective screen is zero is θb (°),
(θb-10)°≤φ≤85°
satisfying the relationship of
An image display device characterized by:

Images