JP6747132B2 - Transmissive screen, rear projection display - Google Patents

Description

The present invention relates to a transmissive screen and a rear projection display device including the transmissive screen.

BACKGROUND ART Conventionally, as one of image display devices, a transmissive screen that transmits an image light projected from an image source to display an image and a rear projection display device including the transmissive screen are known. The transmissive screen and the rear projection display device have been developed from various points such as improvement of the contrast of the image and improvement of the viewing angle (see, for example, Patent Documents 1 and 2).

JP, 2008-033097, A JP, 2008-032997, A

The conventional transmissive screen has very low transparency to prevent the image source behind it from seeing through (see-through phenomenon) and to improve the contrast of the image. It is common that you cannot see the scenery.
However, in recent years, when the image is displayed by being installed in a show window of a store or the like, and the image light is not projected, the screen on the other side of the screen can be visually recognized well and the screen has high transparency. The demand is increasing.

However, the screens of Patent Documents 1 and 2 described above do not take measures to improve the transparency of such a transmissive screen.
Although a hologram screen and the like have been developed as a highly transparent screen, they are not widely used because they are difficult to manufacture and expensive.
Further, displaying a good image with high contrast is always required for a display device.

An object of the present invention is to provide a transmissive screen having high transparency and capable of displaying a good image, and a rear projection display device including the transmissive screen.

The present invention solves the above problems by the following means. It should be noted that, for ease of understanding, reference numerals corresponding to the embodiments of the present invention will be given and described, but the present invention is not limited thereto.
A first invention is a transmissive screen for transmitting and displaying video light, the transmissive screen being parallel to a screen surface of the transmissive screen, the light incident surface (10a, 20a) on which the video light is incident, The light emitting surface (10b, 20b), which faces the light surface and is parallel to the screen surface of the transmissive screen and which emits image light , has optical transparency, and the light emitting surface in the thickness direction of the transmissive screen. On the side, a unit optical shape (121, 221) having a first surface (121a, 221a) and a second surface (121b, 221b) intersecting with the first surface is arranged in a direction parallel to the screen surface. An optical shaping layer (12, 22), a low refractive index layer (13) formed on at least the second surface, having a light transmittance, and having a lower refractive index than the first optical shaping layer; And a second optical shape layer (14) having a property of being formed on the light output surface side of the first optical shape layer and the low refractive index layer so as to fill a valley between the unit optical shapes. And the second optical shaping layer has the same refractive index as the first optical shaping layer, or has a small difference in refractive index so that it can be regarded as equal to the first optical shaping layer. ).
A second invention is the transmissive screen according to the first invention , wherein the surface of the first optical shape layer (12, 22) on the light incident surface side is a surface parallel to the screen surface. When the angle formed by the surfaces (121a, 221a) and the normal to the screen surface is φ1 and the refractive index of the first optical shape layer is n, φ1>1/2×arcsin(1/n) is satisfied. It is a transmissive screen (10, 20) characterized by that.
A third invention is the transmissive screen according to the first invention or the second invention , wherein the surface of the first optical shape layer (12, 22) on the light incident surface side is a surface parallel to the screen surface. When the angle formed by the first surface (121a, 221a) and the normal to the screen surface is φ1, and the refractive index of the first optical shape layer is n, φ1≧arcsin(1/n) It is a transmissive screen (10, 20) characterized by satisfying.
A fourth invention is the transmissive screen according to any one of the first invention to the third invention, wherein the low refractive index layer (132) formed on the second surface (121b, 221b) and the 2 The interface (K) with the optical shape layer (14) is a total reflection surface that totally reflects at least a part of the image light incident from the light incident surface (10a, 20a) and directs it toward the light emission surface side. , And a transmissive screen (10, 20).
A fifth invention is the transmission screen according to any one of the first invention to the fourth invention, wherein the first surface (121a, 221a) and the second surface are provided in the unit optical shape (121, 221). The angle (θ3) formed by (121b, 221b) is an acute angle in the transmissive screen (10, 20).
A sixth invention is the transmission screen according to any one of the first invention to the fifth invention , wherein the low refractive index layer (13) has fine and irregular uneven shapes on its surface. It is a characteristic transmissive screen (10, 20).
A seventh invention is the transmission screen according to any one of the first invention to the sixth invention , wherein an angle (θ2) formed by the second surface (121b, 221b) and a surface parallel to the screen surface is: A transmissive screen (10, 20) characterized by gradually becoming smaller from one side to the other side along the arrangement direction of the unit optical shapes (121, 221) .
An eighth invention is the transmission screen according to any one of the first invention to the seventh invention , wherein the low refractive index layer (13) is also formed on the first surface (121a, 221a). It is a transmissive screen (10, 20) characterized by that.
A ninth invention is the transmission screen according to any one of the first invention to the eighth invention , wherein the first optical shape layer (12) has one point (C) in the unit optical shape (121). The circular Fresnel lens shapes arranged concentrically as a center are formed on the surface on the light emitting surface side, and the angle (θ2) formed by the second surface (121b) and the surface parallel to the screen surface is the unit optical shape. The transmission screen (10) is characterized in that it becomes gradually smaller as it goes away from the one point along the arrangement direction of.
A tenth invention is the transmissive screen (10) according to the ninth invention , wherein the one point (C) is located outside the display area of the transmissive screen.
An eleventh invention is the transmission screen according to any one of the first invention to the tenth invention , wherein the low refractive index layer (13) has a thickness of 1 μm or more and 10 μm or less. It is a transmissive screen (10, 20).
A twelfth invention is the transmission screen according to any one of the first invention to the eleventh invention, which does not include a light diffusing layer containing a diffusing material for diffusing light. (10, 20).
A thirteenth invention is the transmission screen according to any one of the first invention to the twelfth invention, further comprising a light absorption layer for absorbing a part of incident light. , 20).
A fourteenth aspect of the invention is a rear surface including the transmissive screen (10, 20) according to any one of the first to thirteenth aspects of the invention and an image source (LS) for projecting image light onto the transmissive screen. It is a projection display device (1).
A fifteenth invention is the rear projection display device according to the fourteenth invention , wherein the second surface (121b) is a screen in the arrangement direction of the unit optical shapes (121) of the transmissive screen (10, 20). The rear projection display device (1) is provided with an angle (θ2) formed with a plane parallel to the plane, which becomes smaller with distance from the image source (LS).
A sixteenth invention is the rear projection display apparatus according to the fourteenth invention or the fifteenth invention, wherein the image source (LS) is outside the display area with respect to the display area of the transmissive screen (10, 20). The second surface (121b, 221b) of the transmissive screen is positioned downward in the vertical direction of the screen, and is curved so as to be convex toward the upper side of the screen in the vertical direction of the screen. It is a rear projection display device (1).

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

It is a figure which shows the rear projection type display apparatus 1 of 1st Embodiment. It is a figure which shows the layer structure of the screen 10 of 1st Embodiment. It is the figure which looked at the 1st optical shape layer 12 of 1st Embodiment from the light emission side (+Z side). It is a figure explaining the unit optical shape 121, the low refractive index layer 13, and the 2nd optical shape layer 14 of 1st Embodiment. It is a figure explaining the vertex angle (theta) 3 of the unit optical shape 121. It is a figure explaining the angle (phi)1 of the unit optical shape 121. It is a figure explaining the angle (phi)1 of the unit optical shape 121. It is a figure which shows the mode of the image light and external light on the screen 10 of 1st Embodiment. It is a figure explaining the layer structure of the screen 20 of 2nd Embodiment. It is the figure which looked at the 1st optical shape layer 22 of 2nd Embodiment from the light emission side (+Z side). It is a figure which shows the rear projection type display apparatus 3 of a modification. It is a figure which shows the unit optical shape 421 of the screen 40 of a modification.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. Each of the following drawings including FIG. 1 is a schematic view, and the size and shape of each portion 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, mean that in addition to strict meaning, they have the same optical function and can be regarded as parallel and orthogonal. A state having an error of (approximately equal state) is also included.

In the present specification, numerical values such as dimensions of respective members and material names described in the present specification are merely examples of the embodiment, and the present invention is not limited thereto and may be appropriately selected and used.
In the present specification, terms such as plate and sheet are used. Generally, a plate, a sheet, and a film are used in the order of increasing thickness, and they are also used in this specification in a similar manner. However, since there is no technical meaning in such proper use, these words can be appropriately replaced.
In the present specification, the screen surface refers to 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.

(First embodiment)
FIG. 1 is a diagram showing a rear projection display device 1 according to the first embodiment. In FIG. 1, the rear projection display device 1 is viewed from the side.
The rear-projection display device 1 is a display device that includes a screen 10, an image source LS, and the like, and projects image light from the image source LS onto the screen 10 to transmit the image light to display an image.
In this embodiment, as an example, the rear projection display apparatus 1 is applied to a show window of a store, and the screen 10 is fixed by being attached to the glass of the show window.

In general, the screen 10 is a laminated body of thin layers made of resin, etc., and in many cases, the screen 10 alone does not have sufficient rigidity to maintain flatness. Therefore, as shown in FIG. 1, the screen 10 of the present embodiment is integrally bonded (or partially fixed) to the support plate 50 through the light-transmissive bonding layer 51 on the light output side, and the screen flatness is improved. Is maintained.
The support plate 50 is a flat plate-shaped member that has optical transparency and high rigidity, and a plate-shaped member made of resin such as acrylic resin or PC resin or glass can be used.
The support plate 50 of this embodiment is a window glass of a show window of a store or the like. Note that the screen 10 is not limited to this, and may have a form in which the four sides thereof are supported by a frame member (not shown) or the like and the flatness thereof is maintained.

Here, in order to facilitate understanding, in each of the following drawings including FIG. 1, an XYZ orthogonal 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.
In addition, a direction toward the right side in the left-right direction of the screen viewed from the observer O1 located in the front direction on the light emission side (observer side) of the screen 10 is +X direction, a direction toward the upper side in the vertical direction of the screen is +Y direction, and a thickness direction. In the above, the direction from the light incident side (image source side) to the light emitting side (observer side) is defined as +Z direction.
Furthermore, in the following description, the screen up-down direction, the screen left-right direction, and the thickness direction, unless otherwise specified, are the screen up-down direction (vertical direction), the screen left-right direction (horizontal direction) in the usage state of the screen 10. It is a thickness direction (depth direction), and is parallel to the Y direction, the X direction, and the Z direction, respectively.

The image source LS is an image projection device that projects the image light L onto the screen 10, and is, for example, a short focus type projector.
The image source LS is used when the screen (display area) of the screen 10 is viewed from the front direction (the normal direction of the screen surface) on the image source side (−Z side) in the usage state of the rear projection display device 1. The center of the screen 10 in the left-right direction of the screen is located vertically below the screen of the screen 10 (−Y side).
The image source LS can obliquely project the image light L from a position where the distance from the surface of the screen 10 in the depth direction (Z direction) is significantly smaller than that of a conventional general-purpose projector. Therefore, as compared with the conventional general-purpose projector, the image source LS has a shorter projection distance of the image light L to the screen 10, the incident angle θa at which the projected image light L is incident on the screen 10 is large, and its change amount ( The amount of change from the minimum value to the maximum value) is also large.

The screen 10 can transmit and display the image light L projected by the image source LS, and when not in use, such as when the image light is not projected, the scenery on the other side of the screen 10 through the screen 10 is the light emitting side (+Z side). It is a transmissive screen that can be observed both from the light entrance side (-Z side).
The screen 10 has a light-entering surface 10a on which the image light L is incident, and a light-exiting surface 10b facing the light-incident surface 10a and emitting the image light L. The light entrance surface 10a and the light exit surface 10b are parallel or substantially parallel to each other and parallel to the screen surface (XY plane).
The screen (display area) of the screen 10 has a substantially rectangular shape in which the long side direction is the horizontal direction of the screen when viewed from the observer O1 side on the light output side (+Z side) in the use state.
The screen 10 has a screen size of about 40 to 100 inches diagonally and a screen aspect ratio of 16:9. Note that the screen size of the screen 10 is not limited to this, and may be 40 inches or less, for example, and the size and shape can be appropriately selected according to the purpose of use, environment of use, and the like.

In this embodiment, the incident angle θa of the image light L with respect to the area corresponding to the screen of the light entrance surface 10a of the screen 10 is about 18 to 78°. The minimum value of the incident angle θa is the value at the center in the left-right direction of the lower end of the area corresponding to the screen of the light entrance surface 10a of the screen 10. The maximum value of the incident angle θa is a value at the left and right ends of the upper end of the area corresponding to the screen of the light entrance surface 10a of the screen 10.
Regarding the incident angle θa of the image light L, the above range is an example, and it can be appropriately changed according to the screen size of the screen 10, the image source LS, and the like, and when the minimum value is smaller than the above angle range, , The case where the maximum value is large is also included.

FIG. 2 is a diagram showing a layer structure of the screen 10 of the first embodiment. In FIG. 2, a point A (see FIG. 1), which is the screen center (geometrical center of the screen) on the light output side (observer side, −Z side) of the screen 10, passes through and is parallel to the vertical direction (Y direction) of the screen. In addition, a part of a cross section perpendicular to the screen surface (parallel to the Z direction that is the thickness direction) is enlarged and shown. Note that, in FIG. 2, the support plate 50 and the like are omitted for easy understanding.
FIG. 3 is a view of the first optical shape layer 12 of the first embodiment viewed from the light output side (+Z side). For easy understanding, the low refractive index layer 13, the second optical shape layer 14, the protective layer 15 and the like are omitted.
As shown in FIG. 2, the screen 10 has a base material layer 11, a first optical shape layer 12, a low refractive index layer 13, a second optical shape layer 14, and a protective layer in this order from the light incident side (−Z side). It is equipped with 15.

The base material layer 11 is a light-transmissive sheet-shaped member. The first optical shape layer 12 is integrally formed on the light emitting side (observer side, +Z side) of the base material layer 11. The base material layer 11 is a base material (base) forming the first optical shape layer 12.
The base material 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, or a TAC (triacetyl). (Cellulose) resin or the like.
The thickness of the base material layer 11 can be appropriately selected according to the screen size and the like.
Further, in the present embodiment, an antireflection layer may be provided on the light incident side surface of the base material layer 11 which is the light incident surface 10a of the screen 10 to improve the amount of light incident on the screen 10.

The first optical shape layer 12 is a light-transmitting layer formed on the light output side (+Z side) of the base material layer 11. A plurality of unit optical shapes (unit lenses) 121 are arranged and provided on the light exit side surface of the first optical shape layer 12.
As shown in FIG. 3, the unit optical shape 121 is a part of a perfect circle (arcuate shape), and a plurality of unit optical shapes 121 are arranged concentrically around a point C located outside the screen (display area) of the screen 10. ing. That is, the first optical shape layer 12 has a circular Fresnel lens shape on the light output side surface. The circular Fresnel lens shape is a circular Fresnel lens shape having a so-called offset structure with the point C as the center (Fresnel center).
In the present embodiment, the point C is located at the center in the left-right direction of the screen and below the outside of the screen, as shown in FIG. Further, 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 Y direction, as shown in FIG.

FIG. 4 is a diagram illustrating the unit optical shape 121, the low refractive index layer 13, and the second optical shape layer 14 of the first embodiment. In FIG. 4, the above-described FIG. 2 is further enlarged, and the base material layer 11 and the protective layer 15 are omitted for easy understanding.
As shown in FIGS. 2 and 4, the unit optical shape 121 is parallel to the direction (Z direction) orthogonal to the screen surface, and the cross-sectional shape in the cross section parallel to the arrangement direction of the unit optical shapes 121 is substantially triangular. The shape.
The unit optical shape 121 is convex on the light output 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. There is.
In one unit optical shape 121, the second slope 121b is located below the first slope 121a with the vertex t interposed therebetween.
The first slanted surface 121a and the second slanted surface 121b of the unit optical shape 121 have fine and irregular uneven shapes.

The angle formed by the first inclined surface 121a and the surface parallel to the screen surface is θ1. The angle formed by the second inclined surface 121b and the surface parallel to the screen surface is θ2. The angles θ1 and θ2 satisfy the relationship of θ2>θ1.
The angle formed by the first slope 121a and the second slope 121b, that is, the apex angle of the unit optical shape 121 is θ3. The angle θ3 is an acute angle and 0°<θ3<90°.
The angle formed by the first inclined surface 121a with the normal line direction of the screen surface is φ1, and the angle formed by the second inclined surface 121b with the normal line direction of the screen surface is φ2. The sum of the angles φ1 and φ2 is the angle θ3.
This angle φ1 preferably satisfies φ1>1/2×arcsin(1/n), where n is the refractive index of the first optical shape layer 12 and the second optical shape layer 14 , and φ1≧arcsin(1 /N) is more preferably satisfied. In the present embodiment, the angle φ1 satisfies φ1≧arcsin(1/n).
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 in the thickness direction to the point v that is the valley bottom between the unit optical shapes 121) is h.

For easy understanding, FIGS. 2 and 4 show an example in which the arrangement pitch P of the unit optical shapes 121, the angles θ1, θ2, and the like are constant in the arrangement direction of the unit optical shapes 121. However, in the unit optical shape 121 of the present embodiment, the array pitch P is actually constant, but the angle θ1 gradually increases as the distance from the point C, which is the Fresnel center, in the array direction of the unit optical shapes 221 increases. The angle θ2 is gradually decreasing.
Similarly, although FIGS. 2 and 4 show an example in which the angles φ1, φ2, and the angle θ3 are constant in the arrangement direction of the unit optical shapes 121, the unit optical shapes 121 of the present embodiment are The angle φ2 gradually increases, the angle φ1 gradually decreases, and the angle θ3 becomes constant as the distance from the point C that becomes the Fresnel center in the arrangement direction of the optical shapes 221 increases. The angle θ3 may change along the arrangement direction of the unit optical shapes 121.

The angles θ1 and θ2, the array pitch P, and the like are the projection angle of the image light from the image source LS (the incident angle θa of the image light on the screen 10), the size of the pixels of the image source LS, the screen 10 It may be appropriately set depending on the screen size, the refractive index of each layer, and the like. For example, the arrangement pitch P may be changed along the arrangement direction of the unit optical shapes 121.

For the first optical shape layer 12, an ultraviolet curable resin having a high light transmittance and a refractive index higher than that of a general ultraviolet curable resin is used. For example, the first optical shape layer 12 is formed of an epoxy acrylate-based ultraviolet curable resin or a urethane-based ultraviolet curable resin having a high refractive index added with a metal oxide. Further, the first optical shape layer 12 may use an ultraviolet curable resin having a high refractive index added with titanium oxide (TiO ₂ ).
The refractive index of the first optical shape layer 12 is preferably about 1.56 to 1.7.
The first optical shape layer 12 is not limited to the ultraviolet curable resin and may be formed of other ionizing radiation curable resin such as electron beam curable resin.

The low-refractive index layer 13 is a layer that is light-transmissive and has a lower refractive index than the adjacent first optical shape layer 12 and second optical shape layer 14.
The low refractive index layer 13 of the present embodiment is formed on the unit optical shape 121 (on the first inclined surface 121a and the second inclined surface 121b), and the first low refractive index portion 131 formed on the first inclined surface 121a. And a second low refractive index portion 132 formed on the second slope 121b.
An interface K between the second low refractive index portion 132 formed on the second inclined surface 121b and the adjacent second optical shape layer 14 serves as a total reflection surface that totally reflects at least a part of the image light. The interface K, which is a total reflection surface, and the second low refractive index portion 132 form an angle θ2 with the screen surface. In addition, the above-described first slope 121a corresponds to a connection surface that connects the total reflection surfaces (interface K), and the first slope 121a and the first low refractive index portion 131 form an angle with respect to the normal direction of the screen surface. Make φ1.

The low refractive index layer 13 is formed so as to follow the fine and irregular concave-convex shapes formed on the first slope 121a and the second slope 121b of the unit optical shape 121, and on the side opposite to the unit optical shape 121 side. A film is also formed on the surface of (1) while maintaining the fine and irregular asperity shape. Therefore, the low-refractive-index layer 13 has fine irregular irregular shapes on both sides thereof.
Light incident on the low-refractive index layer 13 at an incident angle equal to or greater than the critical angle is diffused at the time of total reflection due to the fine and irregular uneven shape. Further, light incident on the low refractive index layer 13 at an incident angle less than the critical angle is transmitted without being diffused.
The fine and irregular irregular shape of the low refractive index layer 13 may be appropriately selected according to the desired optical performance and the like.

The low refractive index layer 13 is formed of a material having a high light transmittance and a refractive index lower than that of the adjacent first optical shape layer 12 and second optical shape layer 14. The low refractive index layer 13 is preferably made of, for example, a metal fluoride such as magnesium fluoride (MgF ₂ ) or aluminum fluoride (AlF ₃ ), silicon oxide (SiO ₂ ), or a silicon resin.
The low refractive index layer 13 is formed by depositing or sputtering the above-mentioned materials.
The refractive index of the low refractive index layer 13 is preferably about 1.35 to 1.45 from the viewpoint of efficiently totally reflecting the image light at the interface K with the second optical shape layer 14.

The low refractive index layer 13 preferably has a thickness of 1 μm or more and 10 μm or less.
If the thickness of the low refractive index layer 13 is less than 1 μm, the total reflection of the image light at the interface K will be insufficient, or interference will occur when the image light is totally reflected, and the image will be deteriorated. , Not preferable. When the thickness of the low-refractive index layer 13 is larger than 10 μm, it becomes difficult to form the low-refractive index layer 13 by vapor deposition or the fine optical irregularities on the surface of the unit optical shape 121 are filled. It is not preferable because the surface is flattened and the surface opposite to the unit optical shape 121 side becomes flat.

The second optical shape layer 14 is a light-transmitting layer provided on the light output side (+Z side) of the low refractive index layer 13. The second optical shape layer 14 has a higher refractive index than the low refractive index layer 13. The interface K between the second optical shape layer 14 and the second low refractive index portion 132 totally reflects at least a part of the incident image light and directs it toward the observer O1 side on the light emission side (+Z side).
The second optical shape layer 14 is formed so as to fill the valleys between the unit optical shapes 121 from above the low refractive index layer 13, and flattens the light exit side (observer side) surface of the first optical shape layer 12. ing. Therefore, the surface on the light incident side (−Z side) of the second optical shape layer 14 is formed by arranging a plurality of substantially reverse shapes of the unit optical shapes 121 of the first optical shape layer 12.

By providing such a second optical shape layer 14, the low refractive index layer 13 can be protected and the image light is totally reflected at the interface K between the low refractive index layer 13 and the second optical shape layer 14. Then, the image can be displayed to the observer on the light emitting side.
Further, by flattening the light output side surface by the second optical shape layer 14, it becomes easy to stack the protective layer 15 and the like on the back surface side of the first optical shape layer 12 of the screen 10, and the support plate 50 is provided. It is also easy to bond to etc.

The second optical shape layer 14 has a high light transmittance and an ultraviolet curable resin having a higher refractive index than a general ultraviolet curable resin, for example, the same material as the first optical shape layer 12 described above, epoxy. Acrylate-based UV-curable resin, urethane-based or other UV-curable resin with a high refractive index by adding a metal oxide, and UV-curable resin with a high refractive index by adding titanium oxide (TiO ₂ ). And the like.
The refractive index of the second optical shape layer 14 is preferably about 1.56 to 1.7 from the viewpoint of efficiently totally reflecting the image light at the interface K with the low refractive index layer 13. Further, the refractive index of the second optical shape layer 14 is preferably equal to or substantially equal to the refractive index of the first optical shape layer 22 (the difference in refractive index is small enough to be considered equal).

In the present embodiment, the second optical shape layer 14 and the first optical shape layer 12 are made of the same resin. The second optical shape layer 14 and the first optical shape layer 12 are not limited to this, and may be formed of different resins.
Further, in the present embodiment, the second optical shape layer 14 will be described by way of an example formed of an ultraviolet curable resin, but the present invention is not limited to this, and for example, another ionizing radiation curable such as an electron beam curable resin. It may be formed of a mold resin.

Returning to FIG. 2, the protective layer 15 is a light-transmissive layer formed on the light exit side (+Z side) of the second optical shape layer 14, and has a function of protecting the light exit side of the screen 10. There is.
As the protective layer 15, a sheet-shaped member made of resin having high light transmittance is used. As the protective layer 15, for example, a sheet-shaped member formed by using the same material as that of the base material layer 11 described above may be used.
Further, when the light emitting surface 10b of the screen 10 is joined to the support plate 50, the screen 10 may be configured without the protective layer 15.
Further, when the screen 10 is not joined to the support plate 50 or the like and the protective layer 15 is on the most light emitting side (observer side) in the screen 10, the protective layer 15 has a hard coat function, an antifouling function, and an antistatic property. It may have a function or the like.

As described above, the screen 10 of the present embodiment does not include the light diffusing layer containing the diffusing material such as particles having a diffusing action, and the diffusing action is due to the fineness of the surface of the low refractive index layer 13. And it is only irregular irregular shape.
In addition, it is preferable that the screen 10 has a total light transmittance of 30% or more with respect to incident light from a direction orthogonal to the screen surface (incidence angle to the screen surface is 0°) while realizing transparency of the screen 10. It is preferable from the viewpoint of displaying various images. The total light transmittance is a ratio of total transmitted light to light incident on the screen 10 at an incident angle of 0°, and is obtained by measurement with a haze meter (HM-150 manufactured by Murakami Color Research Laboratory Co., Ltd.). If the total light transmittance of the screen 10 is less than 30%, the transparency of the screen 10 decreases, which is not preferable.
It is preferable that the total light transmittance is as high as possible. For example, a layer having a light absorbing property is provided on the screen 10 to absorb unnecessary external light such as sunlight and illumination light, and In order to improve the contrast, it is preferable that the total light transmittance is 80% or less from the viewpoint of displaying a good image.

Further, the haze value of the screen 10 is preferably as small as possible, but it is preferably 30% or less from the viewpoint of displaying a good image while realizing the transparency of the screen 10. The haze value is the ratio of diffuse transmittance to the total light transmittance, and can be obtained by measurement with a haze meter or the like. When the haze value is larger than 30%, the transparency of the screen 10 is deteriorated and the view on the other side of the screen is observed as whitish, which is not preferable.

FIG. 5 is a diagram illustrating the angle θ3 of the unit optical shape 121. 5A shows the case where the angle θ3 is an acute angle (0°<θ3<90°), and FIG. 5B shows the case where the angle θ3 is 90° or more.
6 and 7 are diagrams for explaining the angle φ1 of the unit optical shape 121. FIG. 6A shows the case where φ1<1/2×arcsin(1/n), and FIG. 6B shows the case where φ1=1/2×arcsin(1/n). There is. FIG. 7A shows a case where 1/2×arcsin(1/n)<φ1<arcsin(1/n), and FIG. 7B shows a case where φ1=arcsin(1/n). FIG. 7C shows the case where φ1>arcsin(1/n).
5 and 6 and 7, a part of the cross section of the screen 10 corresponding to the above-described FIG. 2 is shown in an enlarged manner, and the low-refractive index layer 13 is simplified for easy understanding. The material layer 11 and the protective layer 15 are omitted.
Here, the angle θ3 and the angles φ1 and φ2 will be described with reference to FIGS. 4 to 7 and the states of the image light and the external light incident on the unit optical shape 121 of the present embodiment.

As shown in FIG. 4, the image light La projected from the image source LS and incident on the screen 10 from the light incident side (−Z side) is incident on the first inclined surface 121 a of the unit optical shape 121. At this time, since the incident angle of the image light La on the first slope 121a is less than the critical angle, a large amount of the image light La passes through the first low refractive index portion 131. A part of the image light La is reflected at the interface (the first inclined surface 121a) between the first low refractive index portion 131 and the first optical shape layer 12, but the amount of the light is small and the light enters the incident side. The observer located does not see the image.
The incident angle of the image light La on the first slope 121a is preferably 0° or near 0°. When the incident angle of the image light La on the first slope 121a is 0° or in the vicinity of 0°, the image light La is incident on the interface (the first slope 121a) between the first low refractive index portion 131 and the first optical shape layer 12. The reflected image light also has a reflection angle of 0° or in the vicinity of 0°, and travels toward the image source LS side below the light incident side (−Z side). Therefore, the image light does not reach the observer O1 (see FIG. 1) located on the light incident side and an unnecessary image is not displayed. Therefore, it is preferable to set the angle θ1, the refractive index of the first optical shape layer 12 and the like, and the incident angle θa of the image light La so that the incident angle of the image light La becomes 0° or in the vicinity of 0°.

At least a part of the image light La that is incident on the region B near the point v that is the valley bottom of the first slope 121a, is transmitted through the first low refractive index portion 131 and is incident on the second optical shape layer 14, is an adjacent unit. The light is incident on the interface K (total reflection surface) between the second low refractive index portion 132 formed on the second inclined surface 121b of the optical shape 121 and the second optical shape layer 14 at an incident angle equal to or greater than the critical angle, and totally reflected. , The observer O1 located in the front direction on the light output side (+Z side) of the screen 10 emits the image in a direction in which the image can be visually recognized. At this time, most of the totally reflected light is diffused due to the fine and irregular irregularities on the surface of the low refractive index layer 13 (see the image light Lb in FIG. 4).

The image light La that has entered the region B and transmitted through the first low refractive index portion 131 is totally reflected at the interface K between the second low refractive index portion 132 and the second optical shape layer 14, and the light output side of the screen 10 ( The interface K (that is, the second inclined surface 121b and the second low refractive index portion 132), which is a total reflection surface, is required to be emitted to the observer O1 side located in the front direction of the +Z side). The angle φ2 formed with respect to the direction is preferably 0<φ2<2×(θ1), more preferably φ2 is substantially equal to θ1 (a state in which there is an error that can be regarded as equal), and φ2 is equal to θ1. More preferably, they are equal.
When this angle φ2 is 0°, the incident angle of the image light incident on the interface K between the second low refractive index portion 132 and the second optical shape layer 14 is less than the critical angle, and the image light is not totally reflected at the interface K. Therefore, the image light cannot be directed to the light output side.
When the angle φ2 is 2×(θ1) or more, the image light totally reflected by the second low-refractive-index portion 132 is directed to the upper side of the light exit side of the screen 10 and the front surface of the light exit side (+Z side) of the screen 10. It does not reach the observer located in the direction. Therefore, the angle φ2 is preferably in the above range.

Further, from the viewpoint of displaying a bright image to the observer O1 located on the light exit side of the screen 10, the angle θ3 that is the apex angle of the unit optical shape 121 is an acute angle (0°<θ3<90°), as described above. Is preferred.
As shown in FIGS. 5A and 5B, this is because when the angle θ3 is set to an acute angle, the area of the second slope 121b (that is, the total reflection is smaller than that when the angle θ3 is 90° or more). This is because the area K of the interface K, which is a surface, can be increased. As a result, it is possible to increase the amount of the image light L that is totally reflected by the interface K that is the total reflection surface and travels toward the observer O1 located on the light emission side (+Z side), and to improve the light utilization efficiency. It is possible to improve the brightness and clarity of the image.

Next, external light such as sunlight or illumination light that enters the screen 10 from the light exit side (+Z side) or the light entrance side (−Z side) will be described.
Next, as shown in FIG. 4, most of the external light Ga incident on the screen 10 from above the light exit side has a critical angle with respect to the interface between the second optical shape layer 14 and the first low refractive index portion 131. The incident light is less than 100° C., is transmitted through the first low refractive index portion 131 without being totally reflected, and travels downward to the light incident side (−Z side) of the screen 10.
A part of the external light Ga is reflected at the interface between the second optical shape layer 14 and the first low refractive index portion 131 when entering the first low refractive index portion 131. However, since the amount of the reflected light is small and goes upward on the light exit side of the screen 10, the observer O1 located in the front direction on the light exit side does not reach the observer O1 and it is possible to suppress the contrast reduction of the image due to the external light Ga. it can.

Further, as shown in FIG. 4, in the present embodiment, the external light Gb incident on the screen 10 from above the light incident side is such that the interface (the second sloped surface) between the second low refractive index portion 132 and the first optical shape layer 12 is formed. 121b) is incident at an incident angle smaller than the critical angle, is transmitted through the second low refractive index portion 132, and is not incident on the interface between the second optical shape layer 14 and the first low refractive index portion 131. Heading down 10
Further, in the present embodiment, a part of the external light Gc of the external light incident on the screen 10 from above the light incident side is part of the external light Gc at the interface between the first low refractive index portion 131 and the first optical shape layer 12 (first After being incident on the inclined surface 121 a) and reflected (including total reflection), the light is transmitted through the second low refractive index portion 132 and goes downward on the light exit side of the screen 10.
It should be noted that a part of the external light Gb, Gc is incident on the interface (the second inclined surface 121b) between the second low refractive index portion 132 and the first optical shape layer 12 at a small incident angle, and therefore most of the external light Gb, Gc is mostly incident. It passes through the second low refractive index portion 132.

Here, depending on the angle of the first low-refractive index portion 131 (first inclined surface 121a), the external light Gb incident on the screen 10 from above the light incident side passes through the second low-refractive index portion 132 and then the second external light Gb. In some cases, the light beam may be incident on the interface between the optical shape layer 14 and the first low refractive index portion 131 at an angle equal to or greater than the critical angle, reflected, and emitted to the light output side. If such external light reaches the observer O1, the contrast of the image is deteriorated, which is not preferable.
Therefore, as described above, it is preferable that the angle φ1 formed by the first low refractive index portion 131 (first inclined surface 121a) and the normal line direction of the screen surface satisfies φ1>1/2×arcsin(1/n). , Φ1≧arcsin (1/n) is more preferably satisfied.

As shown in FIG. 6A, when the angle φ1<1/2×arcsin(1/n), the external light G incident on the screen 10 from the light incident side passes through the second low refractive index portion 132. After that, the light is reflected (including total reflection) at the interface between the second optical shape layer 14 and the first low refractive index portion 131, and a small angle with respect to the front direction of the light exit side (+Z side) of the screen 10 or the front direction. Therefore, the observer O1 (see FIG. 1) located on the light output side is reached. Moreover, when the angle φ1<1/2×arcsin (1/n), the amount of external light that enters the screen 10 from above the light incident side and reaches the observer O1 on the light emitting side is large.
As shown in FIG. 6B, when the angle φ1=1/2×arcsin(1/n), the angle φ1 is such that the external light G incident on the screen 10 from the light incident side has the second optical shape. It is a boundary value which is reflected at the interface between the layer 14 and the first low refractive index portion 131 and reaches the observer O1 located in the front direction on the light emitting side.
Therefore, it is preferable that the angle φ1 is φ1>1/2×arcsin(1/n) from the viewpoint of suppressing deterioration of the contrast of the image due to external light.

Further, as shown in FIG. 7A, when the angle φ1 is ½×arcsin(1/n)<φ1<arcsin(1/n), the angle from the light incident side (−Z side) is large. Part of the external light G that has entered the screen 10 at the incident angle passes through the second low refractive index portion 132 and is reflected at the interface between the first low refractive index portion 131 and the second optical shape layer 14, The light is emitted to the light output side (+Z side) of the screen 10.
As shown in FIG. 7B, when the angle φ1=arcsin(1/n), the angle φ1 is such that the external light G incident on the screen 10 at a large incident angle from the upper side of the light incident side is the second low. It is a boundary value that is transmitted through the refractive index portion 132 and is incident on the interface between the second optical shape layer 14 and the first low refractive index portion 131. At this time, the maximum value of the angle formed by the external light transmitted through the second low refractive index portion 132 with the normal direction of the screen surface in the cross section of the screen 10 shown in FIG. 7B is the angle φ1.

As shown in FIG. 7C, when the angle φ1 is φ1>arcsin(1/n), external light is incident from above the light incident side at a large incident angle and transmitted through the second low refractive index portion 132. After passing through the second low refractive index portion 132, G does not enter the interface between the first low refractive index portion 131 and the second optical shape layer 14 and goes downward on the light exit side of the screen 10. Further, at this time, a part of the external light G is reflected or the like at the interface between the first optical shape layer 12 and the first low refractive index portion 131, passes through the second low refractive index portion 132, and is emitted from the screen 10. Head downwards.
Therefore, the angle φ1 is more preferably φ1≧arcsin(1/n) from the viewpoint of reducing the deterioration of the contrast of the image due to the external light.

In the screen 10 of this embodiment, the angle φ1 satisfies φ1≧arcsin(1/n). Therefore, the external light Gb, Gc incident on the screen 10 from above the light incident side does not reach the observer O1 located in the front direction on the light emitting side, and it is possible to suppress the contrast reduction of the image due to the external light.

The screen 10 of this embodiment is formed by, for example, the following manufacturing method.
A base material layer 11 is prepared, and one side of the base material layer 11 is laminated in a state where a molding die for shaping the unit optical shape 121 is filled with an ultraviolet curable resin, and the resin is irradiated with ultraviolet rays to cure the resin. The first optical shape layer 12 is formed. At this time, fine and irregular concavo-convex shapes are formed on the surfaces that shape the first inclined surface 121a and the second inclined surface 121b of the molding die that shape the unit optical shape 121. This fine and irregular uneven shape is formed by repeating plating under different conditions two or more times or performing etching treatment on the surface of the molding die on which the first sloped surface 121a and the second sloped surface 121b are formed. it can.
After the first optical shape layer 12 is formed on one surface of the base material layer 11, the low refractive index layer 13 is formed on the first slope 121a and the second slope 121b by vapor deposition or the like.

After that, an ultraviolet curable resin is applied from above the low refractive index layer 13 so as to fill the valleys between the unit optical shapes 121 to form a flat surface, and a protective layer 15 is laminated to form the ultraviolet curable resin. After curing, the second optical shape layer 14 and the protective layer 15 are integrally formed. After that, the screen 10 is completed by cutting it into a predetermined size.
The base material layer 11 and the protective layer 15 may have a sheet-like shape or a web shape.

Conventionally, for example, as a method of forming fine and irregular uneven shapes on the first slope 121a and the second slope 121b, diffusion particles or the like are applied to the first slope 121a and the second slope 121b, and low refraction is applied from the top. A method of forming the refractive index layer 13 or blasting the first slope 121a and the second slope 121b after forming the first optical shape layer 12 is known.
However, when unevenness is formed on the first slope 121a and the second slope 121b by such a manufacturing method, the diffusion characteristics and quality of the individual screens 10 vary widely, and stable manufacturing cannot be performed.
On the other hand, in the present embodiment, a large number of the first optical shape layers 12 are formed by shaping the fine and irregular uneven shapes of the first slope 121a and the second slope 121b of the unit optical shape 121 with a molding die. Also, when the screen 10 is manufactured, there is an advantage that there is little variation in quality and the screen can be manufactured stably.

FIG. 8 is a diagram showing a state of image light and external light on the screen 10 of the first embodiment. FIG. 8 shows a section corresponding to the section shown in FIG. 2 of the screen 10. In FIG. 8, in order to facilitate understanding, there is no difference in refractive index at the interface between the base material layer 11 and the first optical shape layer 12 and the interface between the second optical shape layer 14 and the protective layer 15 in the screen 10. Although not shown, there is a difference in refractive index between the interface between the first optical shape layer 12 and the low refractive index layer 13 and the interface between the low refractive index layer 13 and the second optical shape layer 14.
Of the image light L1 projected from the image source LS located below the screen 10 and incident on the screen 10 from the light incident side (−Z side), a part of the image light L2 is incident on the light incident surface 10a of the screen 10. Reflect and head upward. The image light L2 does not reach the observer O2 located in the front direction on the light incident side (image source side) of the screen 10.

Further, a part of the image light L3 of the image light L1 is incident on the region B (see FIG. 4) of the first inclined surface 121a of the unit optical shape 121, and the low refractive index layer 13 (the first low refractive index portion 131). ), and enters the interface K between the second low refractive index portion 132 and the second optical shape layer 14 at an angle equal to or greater than the critical angle, and totally reflects at the interface K to the light exit side (+Z side) of the screen 10. The light is emitted toward the observer O1 located in the front direction. The image light L3 is diffused due to the fine and irregular asperity shape of the interface K (the surface of the low refractive index layer 13), and the observer O1 located in the front direction on the light exit side of the screen 10 has a good visual field. Images with corners can be displayed.
Although a part of the image light is reflected when the image light L3 enters the first low refractive index portion 131, the amount of the light is small, so that the observer O2 located on the light incident side views the image. There is no such thing. Further, when the image light L3 is incident on the first low refractive index portion 131 (first slope 121a) at an incident angle of 0° or in the vicinity of 0°, the reflected light also has a reflection angle of 0° or 0°. Since it is in the vicinity and goes toward the image source LS side below the light incident side, it does not reach the observer O2 and the observer O2 does not visually recognize the image.

In addition, a part of the image light L4 incident on the screen 10 is incident on the first inclined surface 121a at less than the critical angle, passes through the first low refractive index portion 131, and goes up the screen 10 from the light exit side. To go out. The image light L4 does not reach the observer O1 located in the front direction of the screen 10 on the light output side.
In this embodiment, as compared with the case where the low refractive index layer is formed in the circular Fresnel lens-shaped unit lens when the angle θ3 is an acute angle and the apex angle of the unit lens is 90° as described above, The area of K (the second slope 121b) can be widened, such image light L4 can be reduced, and the image light L3 reaching the observer O1 can be increased, so that a bright and clear image can be displayed to the observer O1. Can be displayed.
In the present embodiment, the image light is projected from below the screen 10, and the angle θ2 (see FIG. 2, FIG. 4, etc.) of the second inclined surface 121b is equal to that of the image light at each point in the screen vertical direction of the screen 10. Since the incident angle is larger than the incident angle, the image light does not directly enter the interface K without passing through the first low refractive index portion 131.

Next, a description will be given of light (hereinafter, referred to as “external light”) from the outside world, such as sunlight or illumination light, which is incident on the screen 10 from above the light incident side (−Z side) or the light outgoing side (+Z side). To do.
As shown in FIG. 8, a part of external light G2 of the external light G1 incident on the screen 10 from the light incident side is reflected by the light incident surface 10a of the screen 10 toward the lower side of the screen 10 to be observed by an observer. It doesn't reach O2.
In addition, a part of the external light G3 that is incident on the screen 10 of the external light G1 is incident on the second inclined surface 121b at an incident angle smaller than the critical angle and is transmitted through the second low refractive index portion 132. The screen 10 of the present embodiment satisfies the angle φ1≧arcsin(1/n), and the external light G3 transmitted through the second low refractive index portion 132 is the first low refractive index portion 131 and the second optical shape layer. 14 is directed to the lower side of the light exit side of the screen 10 without entering the interface with 14, and a part of the light exits from the light exit surface 10b to the lower part of the light exit side, or a part of the light is reflected by the light exit surface 10b to proceed downward inside the screen 10. , Gradually diminishes.

A part of the external light G4 entering the screen 10 from above the light incident side of the screen 10 is reflected by the light incident surface 10a and is incident on the screen 10 similarly to the external light G2 described above. Head downwards. Further, a part of the external light G4 is incident on the interface (the first inclined surface 121a) between the first low refractive index portion 131 and the first optical shape layer 12 and is reflected (including total reflection), so that the screen 10 is exposed. Heading downwards on the light output side.
Then, most of the outside light G4 is totally reflected by the light exit surface 10b, travels downward in the screen 10, and is gradually attenuated, and a part of the outside light G4 exits downward from the light exit surface 10b.

Further, a part of the external light G5 that enters the screen 10 from the light output side is reflected by the light output surface 10b of the screen 10 toward the lower side of the screen 10 and does not reach the observer O1.
Of the external light G5, the external light G7 that has entered the screen 10 enters the interface between the second optical shape layer 14 and the first low refractive index portion 131 at an incident angle that is less than the critical angle, and the first low refractive index. The light passes through the portion 131 and goes downward on the light incident side of the screen 10. The outside light G7 is emitted downward on the light incident side of the screen 10, or is totally reflected by the light incident surface 10a of the screen 10 to proceed downward inside the screen 10 and is gradually attenuated.
Therefore, since the external light that enters the screen 10 from above the light entering side and the light exiting side does not reach the viewers O1 and O2, it is possible to suppress the contrast reduction of the image due to the external light.

Further, since the screen 10 does not include a light diffusing layer containing diffusing particles or the like for diffusing light, external light G8, G9 that is incident on the screen surface at a small incident angle and is transmitted through the screen 10 is not diffused. .. Therefore, when the observers O2 and O1 observe the scenery on the other side of the screen 10 through the screen 10 from the light incident side (−Z side) and the light emitting side (+Z side), the scenery on the other side of the screen 10 is It can be observed with high transparency without blurring or bleeding white.

Here, in the conventional transmissive screen, the transparency of the screen is designed to be extremely low so that the image source side cannot be seen through, and the view on the other side of the screen cannot be seen. Further, in order to provide an image having a sufficient viewing angle, the conventional transmissive screen is often provided with a light diffusing layer or the like containing diffusing particles for diffusing light, so that the transparency of other layers can be improved. Even if it is improved, external light is diffused by the diffusing particles of the light diffusing layer, so that there is a problem that the scenery on the other side of the screen may be blurred or may be bleeding white and observed.

However, the screen 10 of the present embodiment has no diffusing action except that the surface of the low-refractive index layer 13 has fine and irregular irregularities, and the image light has a low refractive index layer 13. And is diffused only when totally reflected at the interface K between the second optical shape layer 14 and. Further, in the screen 10 of this embodiment, the transmitted light is not diffused.
Therefore, according to the present embodiment, the screen 10 can display an image having a good viewing angle, brightness, and resolution to the observer O1 on the light output side (+Z side), and in a state where no image light is projected, The view on the other side (−Z side) of the screen 10 is not visually blurred or blurred to the viewer O1 and is highly transparent.
Moreover, according to the present embodiment, since the angle θ3 of the screen 10 is an acute angle, the area of the interface K, which is a total reflection surface, can be increased, and the amount of light traveling to the observer O1 side on the light output side can be increased, which is bright and favorable. You can display various images. Further, according to the present embodiment, since the angle φ1 of the screen 10 satisfies φ1≧arcsin(1/n), it is possible to effectively suppress the contrast reduction of the image due to the external light.

In addition, according to the present embodiment, the screen 10 does not diffuse the transmitted light and has high transparency, so that in the state where the image light is not projected, the light entering side (−Z side) of the screen 10 is used. An observer O2 in the background can also visually recognize the scenery on the other side (+Z side) of the screen 10 in a good condition.
Further, according to the present embodiment, since the screen 10 does not diffuse the transmitted light and has high transparency, even when the image light is projected on the screen 10, the observers O1 and O2 are Through the screen 10, it is possible to partially view the scenery on the other side of the screen 10 (light incident side, light outgoing side).

Further, according to the present embodiment, the first optical shape layer 12 has the point C, which is the Fresnel center, located outside the display area of the screen 10 and below, and has a so-called offset structure Fresnel lens shape. There is. Therefore, even in the case of image light having a large incident angle θa projected from the short focus type image source LS located outside the display area of the screen 10 in the vertical direction of the screen, the image in the horizontal direction of the screen becomes dark. It is possible to display a good image with high brightness uniformity.
From the above, according to the present embodiment, the screen 10 has high transparency and can be used as the screen 10 and the rear projection display device 1 that can display a bright and good-contrast image.

(Second embodiment)
FIG. 9 is a diagram illustrating the layer structure of the screen 20 according to the second embodiment. FIG. 9 shows a cross section of the screen 20 corresponding to the cross section of the screen 10 shown in FIG.
FIG. 10 is a view of the first optical shape layer 22 of the second embodiment as seen from the light output side (+Z side).
The screen 20 of the second embodiment has the same form as the screen 10 of the first embodiment described above except that the first optical shape layer 22 has a linear Fresnel lens shape. Therefore, the portions having the same functions as those in the above-described first embodiment are designated by the same reference numerals or the same reference numerals at the end, and duplicate description will be appropriately omitted.
The screen 20 of the second embodiment includes a base material layer 11, a first optical shaped layer 22, a low refractive index layer 13, a second optical shaped layer 14, and a protective layer 15 from the light incident side, and a light incident surface 20a and a light outgoing surface. It has a surface 20b. This screen 20 can be applied to the rear projection display device 1 shown in the first embodiment.

The first optical shape layer 22 has a linear Fresnel lens shape in which unit optical shapes (unit lenses) 221 are arranged on the surface on the light output side. The unit optical shapes 221 are columnar, and a plurality of unit optical shapes 221 are arranged in the screen vertical direction (Y direction) with the screen horizontal direction (X direction) as the longitudinal direction.
The unit optical shape 221 has a triangular shape in which the sectional shape shown in FIG. 9 is convex toward the light output side, and has a first slope (lens surface) 221a and a second slope (non-lens surface) 221b.
The unit optical shape 221 has an angle θ1 formed by the first slope 121a and a plane parallel to the screen surface, an angle θ2 formed by the second slope 121b and a plane parallel to the screen surface, and a first slope 121a and a second slope 121b. The angle θ3 formed, the angle φ1 formed by the first inclined surface 121a and the normal line direction of the screen surface, the angle φ2 formed by the second inclined surface 121b and the normal line direction of the screen surface, the arrangement pitch P, the lens height h, etc. It is the same as the unit optical shape 121 shown in one embodiment.

According to the present embodiment, as in the case of the first embodiment described above, it is possible to provide the screen 20 and the rear projection display device 1 which can display a good image and have transparency.
Further, according to this embodiment, since the low refractive index layer 13 is formed in the unit optical shape 221 of the linear Fresnel lens shape of the first optical shape layer 22, it is easy to increase the screen size of the screen 20 and Even if the screen is enlarged, the manufacturing cost of the screen 20 can be suppressed.

(Variation)
The present invention is not limited to the embodiments described above, and various modifications and changes can be made, which are also within the scope of the present invention.
(1) In each embodiment, a hard coat layer for the purpose of preventing scratches may be provided on the light incident side (−Z side) of the screens 10 and 20. For the hard coat layer, for example, an ultraviolet curable resin (for example, urethane acrylate) having a hard coat function is applied to the light incident surfaces 10a and 20a of the screens 10 and 20 (the light incident side surface of the base material layer 11). And the like.
Further, the layer is not limited to the hard coat layer, and has a necessary function such as an antireflection function, an ultraviolet ray absorbing function, an antifouling function, an antistatic function, etc., depending on the use environment or purpose of use of the screens 10 and 20. One or more may be selected and provided. The base material layer 11 may have these functions.

Further, in each of the embodiments, the support plate 50 may be arranged on the light incident side (−Z side) of the base material layer 11 via the bonding layer 51. In this case, the support plate 50 may be disposed on the light emitting side of the protective layer 15. One or a plurality of layers having necessary functions such as a hard coat function, an antireflection function, an ultraviolet absorbing function, an antifouling function, an antistatic function, etc. may be selected and provided, and the protective layer 15 may provide these functions. You may have. Further, a touch panel layer or the like may be provided on the light emitting side or the like of the protective layer 15.
Further, when the support plate 50 is arranged on the light incident side (−Z side) of the base material layer 11 via the bonding layer 51, an antireflection layer or the like is provided on the light incident surface of the support plate 50. The amount of light incident on the screen may be improved.

(2) In each of the embodiments, the low-refractive index layer 13 may be formed on at least a part of the second slopes 121b and 221b, and is not formed on the first slopes 121a and 221a. The transparency of 20 may be improved.
Further, in each embodiment, the low refractive index layer 13 may be formed by coating the fluorine-containing coating agent having high transparency on the first slopes 121a and 221a and the second slopes 121b and 221b.
In each embodiment, a layer having an anchor function is provided on at least one of the surfaces of the low refractive index layer 13 on the first optical shape layers 12 and 22 side and the surface on the second optical shape layer 14 side. May be.

(3) In each of the embodiments, the image source LS has a longer projection distance of the image light than that shown in each of the embodiments and the incident angle θa of the image light with respect to the screen, if there is no problem such as a space for arrangement. You may use the thing with a small amount of change.
FIG. 11: is a figure which shows the rear projection type display apparatus 3 of a modification. In FIG. 11, the rear projection display device 3 is viewed from the side. The rear projection display device 3 of the modification has an image source LS3 and a screen 30, and is joined to a support plate 50 located on the light emission side (+Z side) of the screen 30 via a joining layer 51.

The image source LS3 used in the rear projection display device 3 has a longer projection distance of the image light L than the image source LS of the above-described first embodiment, and the incident angle of the image light L incident on the screen 30. The amount of change in θa is small.
The angle θ1 of the first inclined surface 121a and the angle θ2 of the second inclined surface 121b of the screen 30 correspond to the projection angle of the image light L of the image source LS3 (the incident angle θa of the image light on the screen 30). ..
When this image source LS3 is used, the incident angle θa of the image light in the area corresponding to the screen of the light entrance surface 30a of the screen 30 is, for example, about 35 to 65°. The incident angle θa is not limited to this range and can be appropriately set according to the refractive index of the base material layer 11 and the like.

With such a configuration, the space for the rear projection display device 3 becomes large, but like the above-described embodiment, the transmissive screen 30 and the rear projection type that have high transparency and can display a good image. It can be the display device 3.
Further, with such a configuration, the amount of change in the incident angle θa of the image light L on the screen 30 becomes small, so the first optical shape layer 12, the second optical shape layer 14, the low refractive index layer 13 and the like. It becomes easier to select the optimum refractive index of.
Further, with such a configuration, the image light L can be transmitted to the second low refractive index portion 132 and the second optical shape without increasing the refractive index difference between the low refractive index layer 13 and the second optical shape layer 14 or the like. Total reflection can be performed at the interface K with the layer 14, and thus, the effect of improving the contrast of an image can be obtained.

(4) In the first embodiment, the first optical shape layer 12 has a circular Fresnel lens shape of an offset structure in which the point C serving as the Fresnel center is located outside the screen of the screen 10 on the surface on the light output side (+Z side). Although the example is shown, the present invention is not limited to this, and the Fresnel center may be positioned within the screen of the screen 10 according to the projection angle of the image light of the image source LS to be used.

(5) In each of the embodiments, the unit optical shapes 121 and 221 may have a shape in which a curved surface and a flat surface are combined, or may have a bent surface shape.
Moreover, in each embodiment, the unit optical shapes 121 and 221 may be polygonal prism shapes formed by three or more surfaces.

(6) In each embodiment, the unit optical shapes 121 and 221 located above the screens of the screens 10 and 20 have a curved shape such that the second inclined surfaces 121b and 221b thereof are convex toward the upper side in the vertical direction of the screen. You may have.
FIG. 12 is a diagram showing a unit optical shape 421 of the modified screen 40. FIG. 12 shows a cross section that is the upper part of the screen 40 in the vertical direction of the screen and corresponds to the cross section of the screen 20 shown in FIG.
In the screen 40 of this modification, the unit optical shape 421 of the first optical shape layer 42 has a first slope 421a and a second slope 421b, and the second slope 421b is convex toward the upper side in the vertical direction of the screen. It has a curved shape. Further, the low refractive index layer 43 (first low refractive index portion 431, second low refractive index portion 432) is formed along the first slope 421a and the second slope 421b.

By having such a curved shape, the image light Ld totally reflected at the interface K between the second low-refractive index portion 432 of the low-refractive index layer 43 and the second optical shape layer 14 is efficiently emitted from the screen 40. It can be directed to the observer O1 located in the front direction (on the +Z side).
Even when the difference in the refractive index between the low refractive index layer 43 and the second optical shape layer 14 is smaller than that in the first embodiment described above, the second low refractive index portion 432 and the second low refractive index portion 432 are similar to the image light Le. It is also possible to perform total reflection twice or more at the interface K with the two-optical shape layer 14 and direct it to the observer O1 on the light output side.
Therefore, by having such a curved shape, even at the interface K between the second low refractive index portion 432 and the second optical shape layer 14 at the upper part of the screen where the image light is difficult to direct to the observer O1 side on the light output side, The image light can be efficiently directed to the observer O1 side, and the decrease in brightness of the image on the upper portion of the screen of the screen 40 can be improved.

(7) In each of the embodiments, a light absorbing layer that is colored with a dark colorant such as black or gray and has a light absorbing property and absorbs a part of incident light is provided in the screens 10 and 20. You may have it. The light absorption layer may be located on the light exit side (+Z side) or the light entrance side (−Z side) of the low refractive index layer 13.
By providing the light absorbing layer on the screens 10 and 20, the stray light that propagates through the screens 10 and 20 while being totally reflected at the interface between the screens 10 and 20 and the air, which is generated by external light incident on the screens 10 and 20, is absorbed. Therefore, it is possible to suppress a reduction in image contrast due to stray light.

When the light absorption layer is located closer to the light output side than the low refractive index layer 13, it is possible to reduce the black brightness of the image and absorb the external light incident from the light output side, thereby improving the contrast of the image. When the light absorption layer is located on the light incident side of the low refractive index layer 13, it is possible to absorb the external light incident from the light incident side and improve the image contrast.
Further, the low refractive index layer 13 may have a form having a light absorbing function, or the light absorbing layer may be formed on the light incident side or the light emitting side of the low refractive index layer 13.
The above-mentioned light absorbing layer may be a transparent layer which does not contain a coloring material and has a light absorbing function.

(8) In each embodiment, the image source LS is described as an example in which the image source LS is located at the center of the screens 10 and 20 in the left-right direction of the screen and below the outside of the screen when viewed from the normal direction of the screen surface. However, the present invention is not limited to this, and for example, it may be arranged on the diagonally lower side of the screens 10 and 20 and the like, and the image light may be projected onto the screens 10 and 20 from the diagonal direction in the horizontal direction of the screen.
In this case, the arrangement direction of the unit optical shapes 121 and 221 is tilted according to the position of the image source LS. With this configuration, the position of the image source LS can be freely set.
Further, in the environment where the rear projection display device 1 is used, when the external light from above does not pose a problem, the image source LS is arranged in the left and right directions of the screens 10 and 20 when viewed from the normal direction of the screen surface. It may be in the form of being located at the center of and above the outside of the screen.

(9) In each of the embodiments, the screens 10 and 20 have the base layer 11 and the base layer 11 when the first optical shape layers 12 and 22 and the second optical shape layer 14 have sufficient thickness and rigidity. The protective layer 15 may not be provided, or one of them may not be provided.
Further, in each of the embodiments, in the screens 10 and 20, at least one of the base material layer 11 and the protective layer 15 may be a light-transmissive plate-shaped member 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 a bonding layer (not shown) formed of a pressure-sensitive adhesive or an adhesive.

(10) In each embodiment, the image source LS may be, for example, an image source that projects image light having a P-wave polarization component.
The position and angle of the image source LS are set so that the image light is projected onto the screens 10 and 20 at the incident angle θa. At this time, the incident angle θa is (θb-10) when the incident angle (Brewster angle) at which the reflectance of the image light (P wave) projected on the screens 10 and 20 is zero is θb (°). It is set in the range of ° to 85°. For example, when the incident angle θb at which the reflectance of the image light projected on the screens 10 and 20 is zero is 60°, the incident angle θa of the image light is set in the range of 50 to 85°.

As described above, by using the image source LS that projects the image light having the polarization component of the P wave, even when the incident angle θa on the screens 10 and 20 is large, the specular reflection on the surfaces of the screens 10 and 20 is suppressed. Therefore, it is possible to increase the degree of freedom in designing the projection system such as the installation position of the image source LS. Further, by using such an image source LS, it is possible to reduce the reflection of the image light on the screen surface when entering the screens 10 and 20, and it is possible to improve the brightness and sharpness of the image.
The angle θb (Brewster angle) differs depending on the material of the surfaces of the screens 10 and 20 onto which the image light is projected.
Further, in the case of such a form, a sheet-shaped member made of TAC is suitable for the base material layer 11 and the protective layer 15.

(11) In each of the embodiments, the rear projection display device 1 is arranged in a show window of a store or the like, but the invention is not limited to this. For example, an indoor partition or an image display at an exhibition or the like. It can also be applied to a device, a display panel for advertisement placed in a room, and the like.

It should be noted that the present embodiment and the modified embodiments may be appropriately combined and used, but detailed description thereof will be omitted. Further, the present invention is not limited to the embodiments described above.

DESCRIPTION OF SYMBOLS 1 Image display device 10,20 Screen 11 Base material layer 12,22 1st optical shape layer 121,221 Unit optical shape 121a, 221a 1st slope 121b, 221b 2nd slope 13 Low refractive index layer 131 1st low refractive index part 132 Second low refractive index portion 14 Second optical shape layer 15 Protective layer LS Image source K Interface (total reflection surface)

Claims (16)

A transmissive screen that transmits and displays video light,
A light-entering surface which is parallel to the screen surface of the transmissive screen and on which image light is incident;
A light exit surface that faces the light entrance surface , is parallel to the screen surface of the transmissive screen, and emits image light;
A unit optical shape having a light transmitting property and having a first surface and a second surface intersecting with the light emitting surface side in the thickness direction of the transmissive screen is arranged in a direction parallel to the screen surface. A first optical shape layer,
A low-refractive index layer formed on at least the second surface, having a light-transmitting property, and having a lower refractive index than the first optical shape layer;
A second optical shape layer having a light-transmitting property, which is formed on the light output surface side of the first optical shape layer and the low refractive index layer so as to fill a valley between the unit optical shapes;
Equipped with
The second optical shape layer has the same refractive index as the first optical shape layer, or has a small difference in refractive index that can be regarded as equal.
Is a transmissive screen. The transmissive screen according to claim 1,
The light incident surface side surface of the first optical shape layer is a surface parallel to the screen surface,
When the angle formed by the normal line method of the first surface and the screen surface is φ1 and the refractive index of the first optical shape layer is n,
φ1>1/2×arcsin (1/n)
To meet,
Is a transmissive screen. The transmissive screen according to claim 1 or 2,
The light incident surface side surface of the first optical shape layer is a surface parallel to the screen surface,
When the angle formed by the normal line method of the first surface and the screen surface is φ1 and the refractive index of the first optical shape layer is n,
φ1≧arcsin(1/n)
To meet,
Is a transmissive screen. The transmissive screen according to any one of claims 1 to 3,
The interface between the low refractive index layer and the second optical shaping layer formed on the second surface totally reflects at least a part of the image light incident from the light entrance surface and directs the image light toward the light exit surface side. Be a total reflection surface,
Is a transmissive screen. The transmissive screen according to any one of claims 1 to 4,
The angle formed by the first surface and the second surface in the unit optical shape is an acute angle,
Is a transmissive screen. The transmissive screen according to any one of claims 1 to 5 ,
The low refractive index layer has a fine and irregular uneven shape on its surface ,
Is a transmissive screen. The transmissive screen according to any one of claims 1 to 6 ,
The angle formed by the second surface and the surface parallel to the screen surface is gradually reduced from one side to the other side along the arrangement direction of the unit optical shapes ,
Is a transmissive screen. The transmissive screen according to any one of claims 1 to 7 ,
The low refractive index layer is also formed on the first surface ,
Is a transmissive screen. The transmission screen according to any one of claims 1 to 8 ,
In the first optical shape layer, the unit optical shape has a circular Fresnel lens shape arranged concentrically around a single point on the surface on the light emitting surface side,
An angle formed by the second surface and a surface parallel to the screen surface is gradually reduced as the distance from the one point along the arrangement direction of the unit optical shapes is increased,
Is a transmissive screen. The transmissive screen according to claim 9 ,
The one point is located outside the display area of the transmissive screen,
Is a transmissive screen. The transmissive screen according to any one of claims 1 to 10,
The low refractive index layer has a thickness of 1 μm or more and 10 μm or less,
Is a transmissive screen. The transmissive screen according to any one of claims 1 to 11,
Not having a light diffusing layer containing a diffusing material that diffuses light,
Is a transmissive screen. The transmissive screen according to any one of claims 1 to 12,
Providing a light absorption layer that absorbs part of the incident light,
Is a transmissive screen. A transmissive screen according to any one of claims 1 to 13,
An image source for projecting image light on the transmissive screen,
Rear projection display device. The rear projection display device according to claim 14,
In the arrangement direction of the unit optical shapes of the transmissive screen, an angle formed by the second surface and a surface parallel to the screen surface becomes smaller as the distance from the image source increases.
Rear projection type display device characterized by . The rear projection display device according to claim 14 or 15,
The image source is located outside the display area and below the display area of the transmissive screen in the vertical direction of the screen.
The second surface of the transmissive screen is curved so as to be convex toward the upper side of the screen in the vertical direction of the screen.
Rear projection type display device characterized by.

Images