JP2021099514A - Reflection screen and video display device - Google Patents

Abstract

To provide a reflection screen that has high transparency and can display a satisfactory video, and a video display device including the same.SOLUTION: A screen 10 is a reflection screen that reflects part of video light projected from a video source LS for displaying a video and transmits part of the video light, and comprises a plurality of reflection layers 13 that are located inside the screen 10 and arranged along a screen surface and have a function to diffuse and reflect part of incident light and transmits at least part of another incident light. The reflection layer 13 has a rough surface having an irregular rugged shape on both sides. In a thickness direction of the screen 10, the diffuse reflectance in reflected light that is light incident from the back side, reflected on the reflection layer 13, and emitted to the back side is larger than the diffuse reflectance in reflected light that is light incident from the video source side, reflected on the reflection layer 13, and emitted to the video source side.SELECTED DRAWING: Figure 2

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). Among them, the translucent reflective screen, which has transparency, allows the scenery on the other side of the screen to be seen, and the demand for it 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 light diffusing layer containing diffusing particles or the like having a function of diffusing light, the scenery on the other side of the screen is observed whitish and blurred, and has a design property. Therefore, improvement of transparency has been 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, 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 including the reflective screen.

The present invention solves the above problems by the following solutions. 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 reflective screen that reflects a part of the image light projected from the image source (LS) to display an image and transmits a part of the image light, and is located in the reflection screen and incident. A reflection layer (13) having a function of diffusing and reflecting a part of light and transmitting at least a part of other incident light is provided, and the reflection layer is a rough surface having an irregular uneven shape on both sides thereof. In the thickness direction of the reflective screen, the diffuse reflectance of the reflected light that is reflected by the reflective layer and emitted from the back surface is such that the light incident from the image source side is reflected by the reflective layer. The reflective screen (10) is characterized in that it is larger than the diffuse reflectance of the reflected light emitted to the image source side.
The second invention is the reflective screen (10) of the first invention, wherein the reflective layer (13) is formed of a metal thin film.
A third aspect of the present invention is the reflective screen of the first invention or the second invention, which has light transmittance and has a first surface (121a) on which image light is incident and a second surface (121b) facing the first surface (121a). The first unit optical shape (121) having () is light-transmitting with the first optical shape layer (12) arranged on the back surface side, and is on the back side of the first optical shape layer. The reflection layer is provided with a second optical shape layer (14) in which a plurality of second unit optical shapes (141), which are the inverse of the first unit optical shape, are arranged on a surface on the image source side. (13) is a reflection between the first optical shape layer and the second optical shape layer, which is located at least on a part of the first surface of the first unit optical shape. The screen (10).
The fourth invention is characterized in that, in any of the reflective screens from the first invention to the third invention, the reflection screen does not include a light diffusion layer containing diffuse particles having an action of diffusing light. The screen (10).
A fifth invention is an image display device (1) including any one of the reflective screens (10) from the first invention to the fourth invention, and an image source (LS) for projecting image light onto the reflective screen. ).

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 embodiment. It is a figure explaining the layer structure of the screen 10 of an embodiment. It is a figure which looked at the 1st optical shape layer 12 of embodiment from the back side (−Z side). It is a figure which shows the state of the image light and the outside light on the screen 10 of an embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. It should be noted that each of the figures 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 plates, sheets, and films 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 the entire screen, and is assumed to be parallel to the screen (display surface) of the screen.

(Embodiment)
FIG. 1 is a diagram showing a video display device 1 of the present embodiment. FIG. 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 can reflect the image light L projected from the image source LS and display the image on the screen (display surface) on the image source side. Details of the screen 10 will be described later.

Here, in order to facilitate understanding, in each of the following figures 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, when viewed from the observer O1 located in the front direction of the image source side of the screen 10, the direction toward the right side of the screen left-right direction (horizontal direction) is + X direction, and the direction toward the upper side of the screen vertical direction (vertical direction) is + Y. In the direction and thickness direction, the direction from the back surface side (back surface side) to the image source side is defined as 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 (vertical direction) in the usage state of the screen 10, unless otherwise specified. It is assumed that the thickness direction (depth direction) is parallel to the Y direction, the X direction, and the Z direction, respectively.

The image source LS is an image projection device (projector) that projects the image light L onto the screen 10. The image source LS of this embodiment is a short focus type projector.
This image source LS is a screen 10 when the screen (display area) of the screen 10 is viewed from the front direction (normal direction of the screen surface) of the image source side (+ Z side) in the state of use of the image display device 1. It is located at the center of the screen in the left-right direction of the screen 10 on the lower side (−Y side) in the vertical direction with respect to the screen of the screen 10.
The image source LS can project the image light L diagonally from a position in the depth direction (Z direction) from a position where the distance from the surface of the image source side (+ Z side) of the screen 10 is significantly closer than that of the conventional general-purpose projector. .. Therefore, compared to the conventional general-purpose projector, the image source LS has a shorter projection distance to the screen 10, a large incident angle at which the projected image light is incident on the screen 10, and a change in the incident angle (from the minimum value to the maximum value). The amount of change up to the value) is also large.

The screen 10 is a reflective screen that displays a part of the image light L projected by the image source LS toward the observer O1 side located on the image source side (+ Z side) and displays the image light. This is a translucent reflective screen having transparency that allows the scenery on the other side of the screen 10 to be observed when the screen is not used.
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 on the image source side (+ Z side) in the used state.
The screen size of the screen 10 is about 40 to 100 inches diagonally, and the aspect ratio of the screen is 16: 9. Not limited to this, the screen size of the screen 10 may be, for example, 40 inches or less, and the size and shape of the screen 10 can be appropriately selected according to the purpose of use, the environment of use, and the like.

In general, the screen 10 is a laminated body of thin layers made of resin or the like, and in many cases, the screen 10 alone does not have sufficient rigidity to maintain flatness. Therefore, the screen 10 of the present embodiment is integrally joined (or partially fixed) to a support plate (not shown) via a joint layer (not shown) having light transmission on the back side thereof, and the flatness of the screen is maintained. You may.
Such a support plate is a flat plate-shaped member having light transmittance and high rigidity, and a plate-shaped member made of a resin such as an acrylic resin or a PC resin or made of glass can be used. Further, the screen 10 is not limited to this, and the screen 10 may be in a form in which its four sides and the like are supported by a frame member or the like (not shown) to maintain its flatness.
The video display device 1 of the present embodiment is applied to, for example, a show window of a store or the like. At this time, it is preferable that the screen 10 has a form in which the glass of the show window is fixed as the support plate.

FIG. 2 is a diagram illustrating a layer structure of the screen 10 of the present embodiment. In FIG. 2, the screen 10 passes through a point A (see FIG. 1), which is the center of the screen (geometric center of the screen) on the image source side (+ Z side) of the screen 10, and is parallel to the vertical direction (Y direction) of the screen. A part of the cross section perpendicular to the screen surface (parallel to the Z direction, which is the thickness direction) is shown in an enlarged manner.
FIG. 3 is a view of the first optical shape layer 12 of the present 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 11, and the like of the screen 10 are omitted.
As shown in FIG. 2, the screen 10 includes a protective layer 11, a first optical shape layer 12, a reflection layer 13, a second optical shape layer 14, and a base material layer 15 in the order of the image source side (+ Z side). There is.

The protective layer 11 is a light-transmitting layer formed on the image source side (+ Z side) of the first optical shape layer 12, and has a function of protecting the image source side of the screen 10.
As the protective layer 11, a resin sheet-like member having high light transparency is used. The protective layer 11 is, for example, a polyester resin such as PET (polyethylene terephthalate) having high light transmittance, an acrylic resin, a styrene resin, an acrylic styrene resin, a PC (polycarbonate) resin, an alicyclic polyolefin resin, and a TAC (triacetyl cellulose). ) A sheet-like member formed of resin or the like is suitable.
The protective layer 11 may have, for example, a hard coat function, an antistatic function, an antifouling function, and the like. Further, the protective layer 11 may not be provided as long as the first optical shape layer 12 and the like have sufficient thickness and scratch resistance.

The first optical shape layer 12 is a light-transmitting layer provided on the back surface side of the protective layer 11 (the image source side of the reflective layer 13).
On the back surface of the first optical shape layer 12, a plurality of first unit optical shapes (unit lenses) 121 having a partial circular shape (arc shape) are arranged concentrically around the point C. A circular Fresnel lens shape is formed. As shown in FIG. 3, the point C is located outside the screen (display area) of the screen 10, and the first optical shape layer 12 has a so-called offset structure centered on the point C (Fresnel center). It has a circular Fresnel lens shape.
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 A are located on the same straight line parallel to the vertical direction (Y direction) of the screen.

As shown in FIG. 2, the first unit optical shape 121 has a cross-sectional shape parallel to the direction orthogonal to the screen surface (Z direction) and substantially parallel to the arrangement direction of the first unit optical shape 121. It has a triangular shape.
Further, the first unit optical shape 121 is convex toward the back surface side (−Z 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. And have. In the cross section shown in FIG. 2, in one first unit optical shape 121, the second slope 121b is located on the lower side (−Y side) of the first slope 121a 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 of θ2> θ1.
Further, the first slope 121a and the second slope 121b of the first unit optical shape 121 are formed with fine and irregular uneven shapes. The concave-convex 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 first unit optical shape 121 is P, and the height of the first 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 first 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 first unit optical shape 121 are constant in the arrangement direction of the first unit optical shape 121. However, in the first unit optical shape 121 of the present embodiment, the arrangement pitch P is actually constant, but gradually as the angle θ1 moves away from the point C which becomes the Fresnel center in the arrangement direction of the first unit optical shape 121. It's getting bigger.
The angles θ1, θ2, the arrangement pitch P, etc. are the projection angle of the image light from the image source LS (angle of the image light incident on the screen 10), the size of the pixels of the image source LS, and the screen of the screen 10. It may be appropriately set according to the size, the refractive index of each layer, and the like. For example, the arrangement pitch P may change along the arrangement direction of the first unit optical shape 121, and the angles θ1 and θ2 may change.

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 first 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.

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, which have high light transmittance.
In the present embodiment, as the resin constituting the first optical shape layer 12, an ultraviolet curable resin will be described as an example, 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.
It is desirable that the refractive index of the first optical shape layer 12 is equal to or substantially equal to the refractive index of the second optical shape layer 14, which will be described later (the difference in refractive index is small enough to be regarded as equal). Further, the first optical shape layer 12 and the second optical shape layer 14 are preferably formed by using the same ultraviolet curable resin, but may be formed by different materials.
In the present embodiment, the first optical shape layer 12 and the second optical shape layer 14 are formed of the same material and have the same refractive index.

The reflective layer 13 is a layer having a function of reflecting light, and is a layer provided between the first optical shape layer 12 and the second optical shape layer 14 in the screen 10. 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 at least a part of the other incident light.
The surface of the reflective layer 13 on the image source side and the surface on the back surface side are rough surfaces having a fine and irregular uneven shape. The concave-convex 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 reflective layer 13 has a function of diffusing and reflecting a part of the incident light due to a fine and irregular uneven shape, and transmitting at least a part of other non-reflected light without diffusing it.

The reflectance and transmittance of the reflective layer 13 can be appropriately set according to the desired optical performance, but the image light is reflected well and light other than the image light (for example, light from the outside such as sunlight). It is desirable that the transmittance is in the range of about 30 to 80% and the reflectance is in the range of about 5 to 60% from the viewpoint of satisfactorily transmitting the light.

The reflective layer 13 is a thin film formed of a metal having high light reflectivity, for example, aluminum, silver, nickel, or the like. 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. Further, the reflective layer 13 may be formed by depositing a dielectric multilayer film or the like.

The second optical shape layer 14 is a light-transmitting layer formed on the image source side (the back side of the first optical shape layer 12 and the reflection layer 13) of the base material layer 15.
The image source side (+ Z side) surface of the second optical shape layer 14 has a shape that is the reverse of the circular Fresnel lens shape provided on the back surface side (−Z side) surface of the first optical shape layer 12. Is formed. That is, on the surface of the second optical shape layer 14 on the image source side, a plurality of second unit optical shapes 141, which are the inverse of the first unit optical shape 121, are arranged concentrically.
As shown in FIG. 2, the second unit optical shape 141 has a cross-sectional shape parallel to the direction orthogonal to the screen surface (Z direction) and substantially parallel to the arrangement direction of the second unit optical shape 141. It has a triangular shape. The second unit optical shape 141 is convex toward the image source side (+ Z side) and has a first slope 141a and a second slope 141b. In the cross section shown in FIG. 2, in one second unit optical shape 141, the second slope 141b is located on the upper side (+ Y side) of the first slope 141a with the apex t2 in between.

The first slope 141a and the second slope 141b of the second unit optical shape 141 have fine and irregular uneven shapes on their surfaces. The concave-convex 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 angle formed by the first slope 141a of the second unit optical shape 141 with the surface parallel to the screen surface is θ1. The angle formed by the second slope 141b with the plane parallel to the screen plane is θ2. The angles θ1 and θ2 satisfy the relationship of θ2> θ1.

The second optical shape layer 14 is formed of an ultraviolet curable resin such as a urethane acrylate-based, polyester acrylate-based, epoxy acrylate-based, polyether acrylate-based, polythiol-based, or butadiene acrylate-based resin having high light transmittance.
In the present embodiment, as the resin constituting the second optical shape layer 14, an ultraviolet curable resin will be described as an example, 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.
Further, the second optical shape layer 14 of the present embodiment is formed of a resin having a glass transition temperature Tg of 50 to 100 ° C. from the viewpoint of enhancing the adhesion between the second optical shape layer 14 and the reflection layer 13. preferable. Further, by setting the glass transition temperature Tg of the resin forming the second optical shape layer 14 within the above range, the second unit optical shape 141 is formed when the reflective layer 13 is formed on the second unit optical shape 141. The surface of the reflective layer 13 is roughened, and a haze difference between the surface of the reflective layer 13 on the side of the first optical shape layer 12 and the surface of the reflective layer 13 on the side of the second optical shape layer 14 can be easily imparted. The light diffusing action of the region from 13 to the surface on the back surface side can be made larger than the light diffusing action of the region from the reflection layer 13 to the surface on the image source side.

The base material layer 15 is a sheet-like member having light transmission. The base material layer 15 is located on the back surface side of the screen 10, and the second optical shape layer 14 is integrally formed on the image source side (+ Z side) thereof. The base material layer 15 is a layer serving as a base material (base) for forming the second optical shape layer 14.
The base material layer 15 is, for example, a polyester resin such as PET (polycarbonate terephthalate) having high light transmittance, an acrylic resin, a styrene resin, an acrylic styrene resin, a PC (polycarbonate) resin, and a fat, similarly to the protective layer 11 described above. A sheet-shaped member formed of a ring-type polyolefin resin, a TAC (triacetyl cellulose) resin, or the like is suitable.

As described above, the screen 10 of the present embodiment does not include a light diffusing layer containing a diffusing material such as particles having a diffusing action of diffusing light, and image light or the like is reflected by the reflecting layer 13 when reflected. , Diffused by the fine and irregular uneven shape of its surface.

The screen 10 of the present embodiment is manufactured by, for example, the following manufacturing method.
A base material layer 15 is prepared, and one surface thereof is laminated with an ultraviolet curable resin filled in a molding mold forming the second unit optical shape 141, and the ultraviolet curable resin is cured by irradiating with ultraviolet rays. The second optical shape layer 14 is formed by the UV forming method. At this time, fine and irregular uneven shapes are formed on the surfaces forming the first slope 141a and the second slope 141b of the molding die that shape the second unit optical shape 141. This fine and irregular uneven shape can be formed by performing surface processing a plurality of times on the surfaces forming the first slope 141a and the second slope 141b of the molding die. This surface processing includes, for example, plating processing, etching processing, blasting processing, and the like. Further, the surface processing may be performed a plurality of times by changing various conditions and the like.

After forming the second optical shape layer 14 on one surface of the base material layer 15, the reflective layer 13 is formed by depositing aluminum on the first slope 141a and the second slope 141b of the second unit optical shape 141. To do.
As described above, the first slope 141a and the second slope 141b of the second unit optical shape 141 of the second optical shape layer 14 are formed with fine and irregular uneven shapes, and the reflective layer 13 is formed by this. It is formed following the uneven shape, and is formed while maintaining the uneven shape of the first slope 141a and the second slope 141b. Therefore, the reflective layer 13 has a surface on the second optical shape layer 14 side (back side in the used state) and a surface on the side on which the first optical shape layer 12 is formed (image source side in the used state). It has a fine and irregular uneven shape.

After that, an ultraviolet curable resin is applied from above the reflective layer 13 so as to fill the valley between the second unit optical shapes 141 so as to be flat, and the protective layer 11 is laminated and irradiated with ultraviolet rays to obtain ultraviolet rays. The curable resin is cured to integrally form the first optical shape layer 12 and the protective layer 11. At this time, since a fine and irregular uneven shape is formed on the surface of the reflective layer 13, the first slope 121a and the second slope 121b of the first unit optical shape 121 of the first optical shape layer 12 may be formed. A fine and irregular uneven shape that follows this uneven shape is formed.
After that, the screen 10 is completed by cutting it to a predetermined size or the like.
The base material layer 15 and the protective layer 11 may have a single-wafer shape or a web-like shape.

As a method of forming a fine and irregular uneven shape on the surface of the reflective layer 13, for example, diffusion particles or the like are applied on the first slope 141a and the second slope 141b to form the reflective layer 13 from above. Conventionally known methods include forming a reflection layer 13 after blasting the first slope 141a and the second slope 141b after forming the second optical shape layer 14. However, with such a manufacturing method, stable manufacturing cannot be performed due to large variations in diffusion characteristics, quality, and the like on the individual screens 10.
On the other hand, as described above, the reflective layer 13 is formed after forming fine and irregular uneven shapes on the first slope 141a and the second slope 141b of the second unit optical shape 141 by a molding die. Therefore, even when a large number of screens 10 are manufactured, there is little variation in quality and stable production can be performed.

Further, as described above, the first optical shape layer 12 is provided to flatten the surface of the second optical shape layer 14 on which the reflection layer 13 is formed on the image source side, and has a second unit optical shape. It is formed to fill the valley between 141.
By providing such a first optical shape layer 12, there is an advantage that the reflective layer 13 can be protected and handling becomes easy, and that the protective layer 11 and the like can be easily laminated.

FIG. 4 is a diagram showing the state of image light and external light on the screen 10 of the present embodiment. FIG. 4 shows an enlarged part of a cross section of the first 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. 4, in order to facilitate understanding, it is shown that there is no difference in 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 first unit optical shape 121 and is reflected. It is diffusely reflected by the layer 13 and emitted to the observer O1 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 image light L1 projected from the image source LS, a part of the image light L4 is reflected on the surface of the screen 10 and heads upward to the screen 10, so that it does not reach the observer O1 and hinders the visual recognition of the image. It does not become.
In the present embodiment, the image source LS is located below the screen 10, the image light L1 is projected from below the screen 10, and the angle θ2 (see FIG. 2) of the second slope 121b is the screen 10. Since it is larger than the incident angle of the image light at each point in the vertical direction of the screen, the image 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 such as sunlight (hereinafter referred to as external light) 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, of the external light G1 and G5 incident on the screen 10 from above, some of the external light G2 and G6 are reflected by the surface of the screen 10 and head toward the lower side of the screen. Further, some of the external light G3 and G7 are reflected by the reflection layer 13. Then, for example, a part of the external light G3 is totally reflected on the surface of the screen 10 on the image source side (+ Z side) and heads downward inside the screen 10, and the other part of the external light G3 (not shown) is. It emits light toward the lower side of the screen 10. Further, the external light G7 is 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 reflection layer 13 pass through the reflection layer 13 and are emitted to the back surface side and the image source side, respectively. At this time, since the external lights 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.

Further, a part of the external light incident on the screen 10 is totally reflected on the surface of the screen 10 on the image source side and the back surface side, and is attenuated toward the lower side inside the screen.
Further, the external lights G9 and G10 incident on the screen 10 at a small incident angle pass through the reflection layer 13 and are emitted to the back side and the image source side, respectively. Since the screen 10 does not have a light diffusion layer containing diffuse particles that diffuse light, the external light G9 and G10 transmitted through the screen 10 are not diffused. Therefore, when observing the scenery on the other side of the screen 10 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 the conventional semi-transmissive reflective screen provided with a light diffusing layer containing diffused particles and the like, the image light is diffused twice before and after the reflection by the reflective layer, so that a good viewing angle can be obtained while the image is obtained. There is a problem that the resolution of the light is reduced. Further, in such a conventional semi-transmissive reflective screen, since external light is also diffused by the diffused particles, the scenery on the other side of the screen is observed as blurred or white bleeding, and the transparency is lowered.

However, the screen 10 of the present embodiment does not have a light diffusion layer containing diffuse particles and the like, and the image light is diffused only at the time of reflection due to the fine and irregular uneven shape of the surface of the reflection layer 13. .. Further, in the screen 10 of the present embodiment, only the light reflected by the reflective layer 13 is diffused, and the light transmitted through the reflective layer 13 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, in the screen 10 of the present embodiment, the observer O2 located on the back side has high transparency in the scenery on the image source side (+ Z side) through the screen 10 regardless of the presence or absence of projection of image light. Can be visually recognized well.

Here, the optical characteristics of the screen 10 of the present embodiment will be further described.
In the screen 10 of the present embodiment, in the thickness direction, the light diffusing action of the region from the reflective layer 13 to the surface on the back surface side is based on the light diffusing action of the region from the reflective layer 13 to the surface on the image source side. Is also big. That is, in the screen 10, when the light incident from the back surface side (−Z side) is reflected by the reflection layer 13 and emitted to the back surface side, the diffusing action received is that the light incident from the image source side (+ Z side) is reflected. This is larger than the diffusion action that is received when the light is reflected by the layer 13 and emitted to the image source side.
Therefore, the diffuse reflectance (diffuse reflectance on the back side) of the reflected light incident from the back side (−Z side) of the screen 10 and reflected by the reflection layer 13 and emitted to the back side is the image source of the screen 10. It is larger than the diffuse reflectance (diffuse reflectance on the image source side) of the reflected light incident from the side (+ Z side), reflected by the reflection layer 13, and emitted to the image source side.

With such a form, a part of the external light incident on the screen 10 from the upper side of the back side is diffusely reflected by the reflection layer 13 and emitted to the upper side of the screen 10, so that the observer on the back side can see the light. It does not reach O2, and uneven brightness due to reflection of external light when observed from the back side can be suppressed.
Further, since the image light is sufficiently diffusely reflected by the reflection layer 13, an image having good brightness can be displayed for the observer O1 located on the image source side. Further, regarding the external light from the upper side of the image source side, even if it is diffusely reflected by the reflective layer 13, it goes to the lower side of the screen 10 and does not reach the observer O1, so that the decrease in the contrast of the image can be suppressed.

Screens corresponding to the examples and comparative examples of the screen 10 of the present embodiment were prepared, and the appearance and transparency of the image were evaluated.
In the screen 10 of the embodiment, the haze on the back side is larger than the haze on the image source side. That is, in the screen of the embodiment, the diffuse reflectance of the reflected light when incident from the image source side is about 5.8%, and the diffuse reflectance of the reflected light when incident from the back surface side is about 9.2%. Therefore, the diffuse reflectance on the back side is larger than the diffuse reflectance on the image source side.
Further, the screen of the comparative example has the same form as the screen of the embodiment, but differs from the screen of the embodiment in that the haze on the image source side and the haze on the back side are substantially equal to each other. That is, in the screen of the comparative example, the diffuse reflectance of the reflected light when incident from the image source side is about 5.2%, and the diffuse reflectance of the reflected light when incident from the back surface side is about 5.5%. Therefore, the difference between the diffuse reflectance on the back surface side and the diffuse reflectance on the image source side is small.

The diffuse reflectance is the ratio of diffuse reflected light in the reflected light when light is incident on the point A at the center of the screen of the screens of Comparative Examples and Examples from the lower side in the vertical direction of the screen at an incident angle of 8 °. Was measured with a haze meter (HR-100 manufactured by Murakami Color Co., Ltd.).
Regarding the appearance of the image and the transparency of the screen, the screen of the example is arranged in a bright room environment (lighting is about 600 lux in the center of the screen), the image light is projected from the image source LS, and the front direction of the screen. The appearance of the image and the transparency of the screen were visually observed and evaluated from a position of 3 m.

On the screen of the example, a bright and good image was observed, and the viewing angle was sufficient. In addition, the transparency of the screen when observing the screen from the image source side and the back side was high, and the scenery on the other side of the screen did not become cloudy. Further, when the screen of the example was observed from the back side, unevenness of brightness due to external light was not observed.
On the other hand, on the screen of the comparative example, a bright and good image was observed, but it was not preferable because uneven brightness was observed when viewed from the back side due to external light incident from the back side.

From the above, in the screen 10 of the present embodiment, the light diffusing action of the region from the reflective layer 13 to the surface on the back surface side is the light diffusing action of the region from the reflective layer 13 to the surface on the image source side. Because it is very large, it is possible to display a good image that is bright and has high contrast while maintaining transparency, and it is possible to reduce uneven brightness on the back side due to external light.
Further, according to the present embodiment, in the first optical shape layer 12, the point C serving as the Fresnel center is located outside the display area and on the image source LS side, and has a so-called offset structure circular Fresnel lens shape. Therefore, even if the image light L has a large incident angle projected from the image source LS, which is a short-focus type projector, the image in the left-right direction of the screen does not become dark and the surface uniformity of brightness does not occur. It is possible to display a high quality image.

(Transformed form)
Not limited to the embodiments described above, various modifications and changes are possible, and these are also within the scope of the present invention.
(1) In the embodiment, a hard coat layer for the purpose of preventing scratches may be provided on the image source side (+ Z side) and the back surface side (−Z side) of the screen 10. The hard coat layer is formed by applying, for example, an ultraviolet curable resin having a hard coat function (for example, urethane acrylate or the like) on the image source side surface of the screen 10 (the image source side surface of the protective layer 11). And so on.
Further, not limited to the hard coat layer, one layer having appropriately 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 screen 10. One or more may be selected and provided. Further, a touch panel layer or the like may be provided on the image source side (+ Z side) of the protective layer 11.
For example, when an antireflection layer is provided on the surface of the screen 10 on the image source side, the effect of reducing reflection on the surface of the screen 10 to increase the amount of incident light on the screen 10 and improving the brightness of the image is achieved. In addition, a part of the light reflected by the reflection layer 13 is reflected on the surface on the image source side and emitted from the back side, so that it is possible to prevent the observer O2 on the back side from seeing a part of the image.

(2) In the embodiment, a light absorption layer that transmits light to the image source side (+ Z side) of the reflection layer 13 but is colored with a dark color material such as black or gray and has light absorption. The black brightness of the image may be reduced and external light may be absorbed from the image source side to improve the contrast of the image.
Further, in the embodiment, the light absorption layer as described above may be provided on the back side of the reflection layer 13 to absorb the external light incident from the back side to improve the contrast of the image.
The above-mentioned light absorbing layer may be a transparent layer that does not contain a coloring material and has a light absorbing action.

(3) In the embodiment, the first slope 121a and the second slope 121b of the first unit optical shape 121 of the first optical shape layer 12, the first slope 141a and the first slope 141a of the second unit optical shape 141 of the second optical shape layer 14. The second slope 141b has shown an example of being formed by a flat surface, but the present invention is not limited to this, and for example, a curved surface and a flat surface may be combined or a folded surface shape may be used.
Further, the first unit optical shape 121 and the second unit optical shape 141 may be polygonal shapes formed by a plurality of three or more surfaces.
Further, the reflective layer 13 has shown an example in which the first slope 141a and the second slope 141b (first slope 121a and second slope 121b) are formed, but the present invention is not limited to this, and for example, the first slope 141a (first slope 141a) is shown. It may be a form formed on at least a part of one slope 121a).
Further, although the first slope 121a and the second slope 121b, the first slope 141a and the second slope 141b have shown an example having a fine and irregular uneven shape, the first slope 121a and 141a are not limited to this. It may be a form having a fine and irregular uneven shape.

(4) In the 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 screen 10 in the left-right direction of the screen and below the outside of the screen. It may be arranged on the side or the like, and the image light may be projected from the oblique light in the left-right direction of the screen with respect to the screen 10.
In this case, the point C, which is the Fresnel center of the circular Fresnel lens shape of the first optical shape layer 12, is arranged so as to be offset according to the position of the image source LS. With such a form, the position of the image source LS and the like can be freely set.

(5) In the embodiment, the screen 10 includes a base material layer 15 and a protective layer 11 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 that does not have one, or a form that does not have either one.
Further, in the screen 10, at least one of the base material layer 15 and the protective layer 11 may be 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.

(6) In the 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 screen 10 at an incident angle φ. This incident angle φ is (φb-10) ° or more and 85 ° when the incident angle (Brewster angle) at which the reflectance of the image light (P wave) projected on the screen 10 is zero is φb (°). It is set in the following range. For example, when the incident angle φb at which the reflectance of the video light projected on the screen 10 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, it is possible to suppress the specular reflection on the surface of the screen 10 even when the angle of incidence φ on the screen 10 is large. , The degree of freedom in designing the projection system, such as the installation position of the image source LS, can be increased. Further, by using such an image source LS, it is possible to reduce the reflection of the image light on the screen surface when it is incident on the screen 10, and it is possible to improve the brightness and sharpness of the image.
The angle φb (Brewster's angle) differs depending on the material of the surface of the screen 10 on which the image light is projected.
Further, in such a form, a TAC sheet-like member is suitable as the base material layer 15 and the protective layer 11.

(7) In the embodiment, the image display device 1 is applied to 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. Applicable. Further, the image display device 1 may be applied to a head-up display (HUD: HEAD-Up Display) of an automobile by attaching the screen 10 to the windshield, or may be applied to a vehicle other than the automobile.

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 the embodiments described above.

1 Image display device 10 Screen 11 Base material layer 12 1st optical shape layer 121 Unit optical shape 121a 1st slope 121b 2nd slope 13 Reflective layer 14 2nd optical shape layer 141 Unit optical shape 141a 1st slope 141b 2nd slope 15 Protective layer

Claims (5)

A reflective screen that reflects a part of the image light projected from the image source to display the image and transmits a part of it.
A reflective layer located within the reflective screen and having the function of diffuse-reflecting a part of the incident light and transmitting at least a part of the other incident light is provided.
The reflective layer is a rough surface having an irregular uneven shape on both sides thereof.
In the thickness direction of the reflection screen, the diffuse reflectance of the reflected light that is reflected by the reflection layer and emitted to the back side is that the light that is incident from the image source side is reflected by the reflection layer. It is larger than the diffuse reflectance of the reflected light emitted to the image source side.
A reflective screen featuring. In the reflective screen according to claim 1,
The reflective layer is made of a metal thin film.
A reflective screen featuring. In the reflective screen according to any one of claims 1 and 2.
A first optical shape layer having a plurality of light-transmitting first unit optical shapes having a first surface on which image light is incident and a second surface facing the first surface and a second surface facing the first surface are arranged on the back surface side. ,
A second unit having light transmission, provided on the back side of the first optical shape layer, and having a plurality of second unit optical shapes arranged on the surface on the image source side, which is the reverse of the first unit optical shape. Optical shape layer and
With
The reflective layer is located between the first optical shape layer and the second optical shape layer, and is located at least on a part of the first surface of the first unit optical shape.
A reflective screen featuring. In the reflective screen according to any one of claims 1 to 3.
Not having a light diffusing layer containing diffusing particles that have the effect of diffusing light,
A reflective screen featuring. The reflective screen according to any one of claims 1 to 4,
An image source that projects image light onto the reflective screen,
A video display device comprising.

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