JP2018013634A - Transmission type screen, and rear surface projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission type screen that is high in transparency, and can display excellent pictures, and to provide a rear surface projection type display device that includes the transmission type screen.SOLUTION: A screen 10, which serves as a transmission type screen, comprises: a light incidence surface 10a upon which picture light is incident; a light emerging surface 10b which opposes the light incidence surface, and from which the picture light emerges; and an interface K that is provided between the light incidence surface 10a and the light emerging surface 10b in a thickness direction of the interface, is plurally arrayed along a prescribed direction, and serves as a total reflection surface making at least a part of the picture light incident from the light incidence surface 10a totally reflect, and making the totally reflected picture light head for the light emerging surface 10b. An angle θ3 formed by a light emerging end part of the interface K serving as the total reflection surface and a light incident side end part of the interface K serving as the total reflection surface adjacent to the light emerging end part is an acute angle.SELECTED DRAWING: Figure 2

Description

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

  2. Description of the Related Art Conventionally, as one of video display devices, a transmissive screen that displays video by transmitting video light projected from a video source and a rear projection display device including the same 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 (for example, see Patent Documents 1 and 2).

JP 2008-033097 A JP 2008-032997 A

The conventional transmissive screen is very low in transparency to prevent the image source located behind (see-through phenomenon) from being seen through and to improve the contrast of the image. It is common to have no view of the scenery.
In recent years, however, it has been installed in store show windows, etc. to display images and when image light is not projected, etc., to a highly transparent screen where the scenery on the other side of the screen can be seen well The demand is growing.

However, the screens of Patent Documents 1 and 2 described above do not take measures to improve the transparency of such a transmissive screen.
In addition, a hologram screen or the like has been developed as a highly transparent screen, but it is not widely used because it is difficult to manufacture or expensive.
Furthermore, displaying a good image with high contrast is always required for display devices.

  An object of the present invention is to provide a transmissive screen that is highly transparent 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. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.
The invention of claim 1 is a transmissive screen that transmits image light and displays the light incident surface (10a, 20a) on which the image light is incident and the light incident surface to emit the image light. In the thickness direction of the light exit surface (10b, 20b) and the transmission screen, the light exit surface is located between the light entrance surface and the light exit surface, a plurality of light sources are arranged along a predetermined direction, and are incident from the light entrance surface. A total reflection surface (K) that totally reflects at least a part of the image light and directs it toward the light exit surface, and a light output side end of the total reflection surface and a light incident side end of the total reflection surface adjacent thereto The transmission screen (10, 20) is characterized in that an angle (θ3) formed between the connection surface formed by the portion and the total reflection surface is an acute angle.
According to a second aspect of the present invention, in the transmissive screen according to the first aspect, when the angle formed by the connecting surface and the normal direction of the screen surface is φ1, φ1> 1/2 × arcsin (1/2) It is the transmission type screen (10, 20) characterized by satisfying.
According to a third aspect of the present invention, in the transmissive screen according to the first or second aspect, when the angle formed by the connecting surface and the normal direction of the screen surface is φ1, φ1 ≧ arcsin (1/2) It is the transmission type screen (10, 20) characterized by satisfying.
According to a fourth aspect of the present invention, in the transmissive screen according to any one of the first to third aspects, the total reflection surface (K) has a fine irregular irregular shape. The transmissive screen (10, 20).
According to a fifth aspect of the present invention, in the transmissive screen according to any one of the first to fourth aspects, an angle (θ2) between the total reflection surface (K) and a surface parallel to the screen surface is: It is a transmission type screen (10, 20) characterized by becoming gradually smaller from one side to the other along the arrangement direction of the total reflection surface.
A sixth aspect of the present invention is the transmissive screen according to any one of the first to fifth aspects, wherein the total reflection surface (K) is a low refractive index layer having a lower refractive index than an adjacent layer. The transmission screen (10, 20) is characterized in that it is formed at the interface between (13) and a layer (14) adjacent thereto.
The transmissive screen according to claim 7 is the transmissive screen according to claim 6, wherein the low refractive index layer (13) is also formed on the connection surface. It is.
The invention according to claim 8 is the transmissive screen according to any one of claims 1 to 7, wherein the first surface (121a) and the second surface facing the first surface (121a) are convex on the light output side. Unit optical shape (121) having (121b) has an optical shape layer (12) having a circular Fresnel lens shape arranged concentrically around one point (C) on the light-emitting side surface, A low refractive index layer (13) having a refractive index lower than that of the adjacent layer is formed on a part of the second surface, and an interface between the low refractive index layer and the adjacent layer (14) is the total reflection. An angle (θ2) between the total reflection surface and the plane parallel to the screen surface gradually decreases with increasing distance from the one point along the arrangement direction of the total reflection surface. A mold screen (10).
The invention of claim 9 is the transmission screen according to claim 8, wherein the one point (C) is located outside the display area of the transmission screen. .
According to a tenth aspect of the present invention, in the transmissive screen according to any one of the eighth or ninth aspects, the low refractive index layer (13) is the first surface corresponding to the connection surface ( 121a) is a transmissive screen (10) characterized in that it is also formed.
The invention of claim 11 is the transmissive screen according to any one of claims 6 to 10, 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) characterized.
A twelfth aspect of the present invention is the transmission screen according to any one of the first to eleventh aspects, wherein a light diffusing layer containing a diffusing material that diffuses light is not provided. It is a transmissive screen (10, 20).
The invention according to claim 13 is the transmission type screen according to any one of claims 1 to 12, further comprising a light absorption layer that absorbs part of incident light. Screen (10, 20).
The invention of claim 14 is the transmission screen (10, 20) according to any one of claims 1 to 13, a video source (LS) for projecting video light on the transmission screen, Is a rear projection display device (1).
According to a fifteenth aspect of the present invention, in the rear projection display device according to the fourteenth aspect, in the arrangement direction of the total reflection surfaces (K) of the transmission screens (10, 20), the total reflection surface is a screen surface. The rear projection display device (1) includes an angle (θ2) formed with a parallel plane that decreases with distance from the video source (LS).

  According to the present invention, it is possible to provide a transmissive screen that can display a good image with high transparency 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 apex angle theta 3 of unit optical shape 121. FIG. It is a figure explaining angle (phi) 1 of the unit optical shape 121. FIG. It is a figure explaining angle (phi) 1 of the unit optical shape 121. FIG. 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 deformation | transformation form. It is a figure which shows the unit optical shape 421 of the screen 40 of a deformation | transformation form.

Embodiments of the present invention will be described below with reference to the drawings. In addition, each figure shown below including FIG. 1 is the figure shown typically, and the magnitude | size and shape of each part are exaggerated suitably for easy understanding.
In this specification, terms that specify shape and geometric conditions, for example, terms such as parallel and orthogonal, are strictly meanings, have similar optical functions, and can be regarded as parallel and orthogonal It also includes a state having an error (substantially equal state).

In the present specification, numerical values such as dimensions and material names of each member to be described are examples of the embodiment, and are not limited thereto, and may be appropriately selected and used.
In this specification, words such as a plate and a sheet are used. In general, the plates are used in the order of thickness, in the order of plate, sheet, and film, and are used in this specification as well. However, there is no technical meaning in such proper use, so these terms 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.

(First embodiment)
FIG. 1 is a diagram illustrating a rear projection display device 1 according to the first embodiment. FIG. 1 shows the rear projection display device 1 as viewed from the side.
The rear projection display device 1 includes a screen 10, a video source LS, and the like, and is a display device that displays video by projecting and transmitting video light from the video source LS to the screen 10.
In the present embodiment, as an example, the rear projection display device 1 will be described with reference to an example in which the rear projection display device 1 is applied to a shop show window 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 a resin, etc., and the screen 10 alone often does not have sufficient rigidity to maintain flatness. Therefore, as shown in FIG. 1, the screen 10 of the present embodiment is integrally joined (or partially fixed) to the support plate 50 via a light-transmitting joining layer 51 on the light output side, so that the flatness of the screen is obtained. Is maintained.
The support plate 50 is a flat plate member having light transmittance and high rigidity, and a plate 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 such as a store. However, the present invention is not limited to this, and the screen 10 may be configured such that its four sides are supported by a frame member (not shown) and the like so as to maintain its flatness.

Here, for easy understanding, an XYZ orthogonal coordinate system is provided as appropriate in each of the following drawings including FIG. 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 10.
In addition, the direction toward the right side of the screen in the left-right direction as viewed from the observer O1 positioned in the front direction on the light output side (observer side) of the screen 10 is the + X direction, the direction toward the upper side in the screen vertical direction is the + Y direction, and the thickness direction. The direction from the light incident side (image source side) to the light outgoing side (observer side) is defined as + 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) in the usage state of the screen 10 unless otherwise specified, The thickness direction (depth direction) is parallel to the Y direction, the X direction, and the Z direction, respectively.

The video source LS is a video projection device that projects the video light L onto the screen 10, and is, for example, a short focus projector.
This video source LS is obtained when the screen (display area) of the screen 10 is viewed from the front direction (normal direction of the screen surface) on the video source side (−Z side) in the usage state of the rear projection display device 1. The center of the screen 10 in the horizontal direction of the screen 10 is located on the lower side (−Y side) in the vertical direction than the screen of the screen 10.
The image source LS can project the image light L obliquely in a depth direction (Z direction) from a position where the distance from the surface of the screen 10 is significantly closer than that of a conventional general-purpose projector. Therefore, compared with a conventional general-purpose projector, the video source LS has a shorter projection distance of the video light L to the screen 10, a larger incident angle θa at which the projected video light L is incident on the screen 10, 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, for example, when the image light is not projected, the scenery beyond the screen 10 is transmitted through the screen 10 on the light output side (+ Z side). And a transmission type screen that can be observed from the light incident side (−Z side).
The screen 10 has a light incident surface 10a on which the image light L is incident and a light exit surface 10b opposite to the light incident surface 10b from which the image light L is emitted. The light incident surface 10a and the light emitting surface 10b are parallel or substantially parallel to each other and parallel to the screen surface (XY surface).
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 light emitting side (+ Z side) observer O1 side.
The screen 10 has a screen size of about 40 to 100 inches diagonal and a screen aspect ratio of 16: 9. However, the present invention is not limited to this, and the screen size of the screen 10 may be, for example, 40 inches or less, and the size and shape can be appropriately selected according to the purpose of use, the use environment, and the like.

In the present embodiment, the incident angle θa of the image light L with respect to the area corresponding to the screen of the light incident surface 10a of the screen 10 is about 18 to 78 °. The minimum value of the incident angle θa is a value at the center in the left-right direction at the lower end of the area corresponding to the screen of the light incident surface 10 a of the screen 10. The maximum value of the incident angle θa is a value at both ends in the left-right direction of the upper end of the area corresponding to the screen of the light incident surface 10 a of the screen 10.
Regarding the incident angle θa of the image light L, the above range is an example and can be appropriately changed according to the screen size of the screen 10, the image source LS, and the like, and 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 illustrating a layer configuration of the screen 10 according to the first embodiment. In FIG. 2, it passes through a point A (see FIG. 1) which is the screen center (the geometric center of the screen) on the light output side (observer side, −Z side) of the screen 10 and is parallel to the screen vertical direction (Y direction). However, a part of a cross section perpendicular to the screen surface (parallel to the Z direction which is the thickness direction) is shown in an enlarged manner. 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). In order to facilitate 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 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 order from the light incident side (−Z side). 15 is provided.

The base material layer 11 is a sheet-like member having optical transparency. The base material layer 11 is integrally formed with the first optical shape layer 12 on the light output side (observer side, + Z side). The base material layer 11 is a layer that becomes a base material (base) for forming the first optical shape layer 12.
The base material layer 11 is made of, for example, polyester resin such as PET (polyethylene terephthalate) having high light transmittance, acrylic resin, styrene resin, acrylic styrene resin, PC (polycarbonate) resin, alicyclic polyolefin resin, 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 serving as 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 on the light output side surface of the first optical shape layer 12.
As shown in FIG. 3, the unit optical shape 121 is a partial shape (arc shape) of a perfect circle, 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. This circular Fresnel lens shape is a circular Fresnel lens shape having a so-called offset structure centered on the point C (Fresnel center).
In the present embodiment, as shown in FIG. 3, the point C is located at the center in the horizontal direction of the screen and below the screen. Further, when the screen 10 is viewed from the front direction, the point C and the point 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 base layer 11 and the protective layer 15 are omitted in order to further expand FIG. 2 described above and facilitate understanding.
As shown in FIGS. 2 and 4, the unit optical shape 121 is parallel to the direction orthogonal to the screen surface (Z direction), and the cross-sectional shape in the cross section parallel to the arrangement direction of the unit optical shapes 121 is substantially triangular. Shape.
The unit optical shape 121 is convex on the light output side (+ Z side), and has a first inclined surface (lens surface) 121a on which image light is incident and a second inclined surface (non-lens surface) 121b opposite to the first inclined surface (lens surface) 121b. Yes.
In one unit optical shape 121, the second inclined surface 121b is positioned below the first inclined surface 121a with the apex t interposed therebetween.
The first inclined surface 121a and the second inclined surface 121b of the unit optical shape 121 have fine and irregular uneven shapes.

The angle formed by the first slope 121a and a plane parallel to the screen surface is θ1. The angle formed by the second inclined surface 121b and a plane parallel to the screen surface is θ2. The angles θ1 and θ2 satisfy the relationship 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 direction of the screen surface is φ1, and the angle formed by the second inclined surface 121b with the normal direction of the screen surface is φ2. The sum of the angles φ1 and φ2 is an angle θ3.
The angle φ1 preferably satisfies φ1> 1/2 × arcsin (1 / n), and more preferably satisfies φ1 ≧ arcsin (1 / n). 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 becomes the valley bottom between the unit optical shapes 121) is h.

For easy understanding, FIGS. 2 and 4 show examples in which the arrangement pitch P, the angles θ 1, θ 2, etc. of the unit optical shapes 121 are constant in the arrangement direction of the unit optical shapes 121. However, in the unit optical shape 121 of the present embodiment, the arrangement pitch P is actually constant, but as the distance from the point C that becomes the Fresnel center in the arrangement direction of the unit optical shapes 221, the angle θ1 gradually increases. The angle θ2 is gradually reduced.
Similarly, FIGS. 2 and 4 show examples in which the angles φ1, φ2 and the angle θ3 are constant in the arrangement direction of the unit optical shapes 121, but the unit optical shape 121 of the present embodiment is a unit. As the distance from the point C that becomes the Fresnel center in the arrangement direction of the optical shape 221 increases, the angle φ2 gradually increases, the angle φ1 gradually decreases, and the angle θ3 is constant. The angle θ3 may change along the arrangement direction of the unit optical shapes 121.

  The angles θ1, 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 to the screen 10), the size of the pixels (pixels) of the image source LS, the screen 10 You may set suitably according to the screen size, the refractive index of each layer, etc. For example, the arrangement pitch P may be changed along the arrangement direction of the unit optical shapes 121.

The first optical shape layer 12 is made of an ultraviolet curable resin having a high light transmittance and a refractive index higher than that of a general ultraviolet curable resin. For example, the first optical shape layer 12 is formed of an ultraviolet curable resin such as an epoxy acrylate-based ultraviolet curable resin or a urethane-based resin having a high refractive index added with a metal oxide. Further, the first optical shape layer 12 may be made of an ultraviolet curable resin to which titanium oxide (TiO ₂ ) is added to increase the refractive index.
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, for example, other ionizing radiation curable resin such as an electron beam curable resin.

The low-refractive index layer 13 is a layer that has optical transparency and 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 respect to the screen surface. The first slope 121a described above corresponds to a connection surface that connects the total reflection surfaces (interfaces K), and the first slope 121a and the first low refractive index portion 131 are angled with respect to the normal direction of the screen surface. Make φ1.

The low refractive index layer 13 is formed following the fine and irregular concavo-convex shape formed on the first inclined surface 121a and the second inclined surface 121b of the unit optical shape 121, and is opposite to the unit optical shape 121 side. Also on this surface, the film is formed in a state in which this fine and irregular uneven shape is maintained. Therefore, the low refractive index layer 13 has fine and irregular uneven shapes on both sides thereof.
Light incident on the low refractive index layer 13 at an incident angle greater than the critical angle is diffused when totally reflected by this fine and irregular concavo-convex 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 concavo-convex shape of the low refractive index layer 13 may be appropriately selected according to the desired optical performance or the like.

The low refractive index layer 13 is formed of a material having a high light transmittance and a lower refractive index than 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 silicon resin.
The low refractive index layer 13 is formed by evaporating or sputtering the above-described material.
The low refractive index layer 13 preferably has a refractive index of about 1.35 to 1.45 from the viewpoint of efficiently and totally reflecting the image light at the interface K with the second optical shape layer 14.

The thickness of the low refractive index layer 13 is preferably 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 becomes insufficient, or the image deteriorates due to interference when the image light is totally reflected. It is not preferable. Further, 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 like, or the surface of the unit optical shape 121 is filled with fine and irregular uneven shapes. Since the surface is flattened and the surface opposite to the unit optical shape 121 side becomes flat, it is not preferable.

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 refractive index higher than that of 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 part of the incident image light and directs it toward the observer O1 side on the light output 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 makes the light output side (observer side) surface of the first optical shape layer 12 flat. ing. Therefore, the light incident side (−Z side) surface 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. Thus, an image can be displayed to the observer on the light emission side.
Further, by flattening the light output side surface by the second optical shape layer 14, the protective layer 15 and the like can be easily laminated on the back side surface of the first optical shape layer 12 of the screen 10, and the support plate 50. It becomes easy to join them.

The second optical shape layer 14 is an ultraviolet curable resin having a high light transmittance and a refractive index higher than that of a general ultraviolet curable resin, for example, an epoxy which is the same material as the first optical shape layer 12 described above. Acrylate UV curable resin, UV curable resin such as urethane with high refractive index added with metal oxide, UV curable resin with high refractive index added with titanium oxide (TiO ₂ ) Etc. are used.
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. 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 formed 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.
In the present embodiment, the second optical shape layer 14 is described by taking an example in which the second optical shape layer 14 is formed of an ultraviolet curable resin. However, the present invention is not limited to this. For example, other ionizing radiation curing such as an electron beam curable resin is used. You may form by mold resin.

Returning to FIG. 2, the protective layer 15 is a light-transmitting layer formed on the light output side (+ Z side) of the second optical shape layer 14, and has a function of protecting the light output side of the screen 10. Yes.
The protective layer 15 is made of a resinous sheet-like member having high light transmittance. For example, the protective layer 15 may be a sheet-like member formed using the same material as the base material layer 11 described above.
Further, when the light exit surface 10 b of the screen 10 is joined to the support plate 50, the screen 10 may be configured not to include the protective layer 15.
Further, when the screen 10 is not bonded to the support plate 50 or the like and the protective layer 15 is 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 function. It may have a function or the like.

As described above, the screen 10 of this embodiment does not include a light diffusion layer containing a diffusing material such as particles having a diffusing action, and the surface 10 of the low refractive index layer 13 has a diffusing action. And it is only irregular uneven | corrugated shape.
The screen 10 has a total light transmittance of 30% or more for incident light from a direction orthogonal to the screen surface (incident angle to the screen surface of 0 °), which is favorable while realizing transparency of the screen 10. From the viewpoint of displaying a simple image. The total light transmittance is the ratio of the total transmitted light to the light incident on the screen 10 at an incident angle of 0 °, and can be obtained by measurement using 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.
The total light transmittance is preferably as high as possible. For example, the screen 10 is provided with a light-absorbing layer so as to absorb unnecessary external light such as sunlight and illumination light. In order to improve the contrast, the total light transmittance is preferably 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 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 the diffuse transmittance in the total light transmittance, and can be obtained by measurement with a haze meter or the like. If this haze value is larger than 30%, the transparency of the screen 10 is lowered, and the scenery on the other side of the screen is observed whitish, which is not preferable.

FIG. 5 is a diagram illustrating the angle θ3 of the unit optical shape 121. FIG. FIG. 5A shows a case where the angle θ3 is an acute angle (0 ° <θ3 <90 °), and FIG. 5B shows a case where the angle θ3 is 90 ° or more.
6 and 7 are diagrams illustrating the angle φ1 of the unit optical shape 121. FIG. 6A shows a case where φ1 <1/2 × arcsin (1 / n), and FIG. 6B shows a case where φ1 = 1/2 × arcsin (1 / n). Yes. 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 a case where φ1> arcsin (1 / n).
5, 6, and 7, an enlarged part of the cross section of the screen 10 corresponding to FIG. 2 described above is shown, and the low refractive index layer 13 is simplified for easy understanding. The material layer 11 and the protective layer 15 are omitted.
Here, with reference to FIGS. 4 to 7, the angle θ3, the angles φ1 and φ2 will be described with reference to 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) enters 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. Among the image light La, a part of the image light is reflected by the interface (the first inclined surface 121a) between the first low refractive index portion 131 and the first optical shape layer 12, but the light amount is small and is incident on the light incident side. The observer who is positioned does not visually recognize 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 inclined surface 121a is 0 ° or in the vicinity of 0 °, the incident light enters the interface (first inclined surface 121a) between the first low refractive index portion 131 and the first optical shape layer 12. The reflected image light has a reflection angle of 0 ° or near 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, etc., and the incident angle θa of the image light so that the incident angle of the image light La is 0 ° or near 0 °.

  At least a part of the image light La incident on the region B near the point v serving as the valley bottom of the first slope 121a, transmitted through the first low refractive index portion 131 and incident on the second optical shape layer 14 is an adjacent unit. The incident light enters the interface K (total reflection surface) between the second low refractive index portion 132 and the second optical shape layer 14 formed on the second inclined surface 121b of the optical shape 121 at an incident angle greater than the critical angle and is totally reflected. The observer O1 positioned in the front direction on the light exit 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 by the fine and irregular concavo-convex shape on the surface of the low refractive index layer 13 (see video light Lb in FIG. 4).

The image light La incident on 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 ( In order to emit light to the observer O1 side located in the front direction on the + Z side), 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 normal to the screen surface. 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 having an error that can be regarded as equal), and φ2 is set to θ1. More preferably, they are equal.
When the angle φ2 is 0 °, the image light incident on the interface K between the second low refractive index portion 132 and the second optical shape layer 14 has an incident angle less than the critical angle and is not totally reflected at the interface K. Therefore, the image light cannot be directed to the light emission 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 upward on the light exit side of the screen 10 and the front side 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 positioned on the light output side of the screen 10, as described above, the angle θ3 that is the apex angle of the unit optical shape 121 is an acute angle (0 ° <θ3 <90 °). It is preferable that
As shown in FIGS. 5A and 5B, by making the angle θ3 an acute angle, the area of the second inclined surface 121b (that is, total reflection) is larger than when the angle θ3 is 90 ° or more. This is because the area of the interface K, which is a surface, can be increased. Thereby, it is possible to increase the amount of the image light L that is totally reflected at the interface K, which is a total reflection surface, and travels toward the observer O1 side that is located on the light output side (+ Z side). The brightness and clarity of the image can be improved.

Next, external light such as sunlight and illumination light that has entered 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 is a critical angle with respect to the interface between the second optical shape layer 14 and the first low refractive index portion 131. The light enters the first low refractive index portion 131 without being totally reflected, and travels downward on 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 reflected light has a small amount of light and travels upward on the light exit side of the screen 10, it does not reach the observer O1 positioned in the front direction on the light exit side, and suppresses a decrease in image contrast due to external light Ga. it can.

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 the interface between the second low refractive index portion 132 and the first optical shape layer 12 (second inclined surface). 121b) is incident at an incident angle less than the critical angle, passes through the second low-refractive-index portion 132, and enters the screen without entering the interface between the second optical shape layer 14 and the first low-refractive-index portion 131. Head down 10
Further, in the present embodiment, a part of the external light Gc out of the external light incident on the screen 10 from above the light incident side is the interface between the first low refractive index portion 131 and the first optical shape layer 12 (the first optical shape layer 12). After entering the inclined surface 121a and reflecting (including total reflection), the light passes through the second low refractive index portion 132 and travels downward on the light output side of the screen 10.
A part of the external light Gb and Gc is incident on the interface (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 most of them are incident. The light 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), after the external light Gb incident on the screen 10 from above the light incident side passes through the second low refractive index portion 132, the second In some cases, the light is 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 exit side. When such outside light reaches the observer O1 side, the contrast of the image is lowered, which is not preferable.
Therefore, as described above, the angle φ1 formed by the first low refractive index portion 131 (first slope 121a) and the normal direction of the screen surface preferably 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 is transmitted 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 the front side of the light output side (+ Z side) of the screen 10 or a small angle with respect to the front direction Therefore, it reaches the observer O1 (see FIG. 1) located on the light output side. 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 output side is large.
As shown in FIG. 6B, when the angle φ1 = ½ × arcsin (1 / n), the angle φ1 is obtained when the external light G incident on the screen 10 from the light incident side is the second optical shape. The boundary value is reflected at the interface between the layer 14 and the first low refractive index portion 131 and reaches the observer O1 positioned in the front direction on the light output side.
Therefore, the angle φ1 is preferably φ1> 1/2 × arcsin (1 / n) from the viewpoint of suppressing a decrease in 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), it is large from above the light incident side (−Z side). A part of the external light G incident on the screen 10 at the incident angle is transmitted through the second low refractive index portion 132 and 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 exit side (+ Z side) of the screen 10.
As shown in FIG. 7B, when the angle φ1 = arcsin (1 / n), this angle φ1 is obtained when the external light G incident on the screen 10 at a large incident angle from above the light incident side is the second low level. This is a boundary value that passes through the refractive index portion 132 and enters 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 that the external light transmitted through the second low refractive index portion 132 makes 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), the external light that is incident at a large incident angle from above the light incident side and is transmitted through the second low refractive index portion 132. G passes through the second low-refractive index part 132 and then does not enter the interface between the first low-refractive index part 131 and the second optical shape layer 14 and travels downward on the light output side of the screen 10. At this time, a part of the external light G is reflected at the interface between the first optical shape layer 12 and the first low refractive index portion 131 and transmitted through the second low refractive index portion 132 to be emitted from the screen 10. Head side down.
Therefore, the angle φ1 is more preferably φ1 ≧ arcsin (1 / n) from the viewpoint of reducing the contrast reduction of the image due to external light.

  In the screen 10 of the present embodiment, the angle φ1 satisfies φ1 ≧ arcsin (1 / n). Therefore, the external light Gb and Gc incident on the screen 10 from above the incident light side does not reach the observer O1 positioned in the front direction on the light exit side, and the contrast reduction of the image due to the external light can be suppressed.

The screen 10 of this embodiment is formed by the following manufacturing methods, for example.
A base material layer 11 is prepared, and on one surface thereof, a molding die for shaping the unit optical shape 121 is laminated in a state filled with an ultraviolet curable resin, and the resin is cured by irradiating ultraviolet rays. The first optical shape layer 12 is formed. At this time, fine and irregular concavo-convex shapes are formed on the surfaces on which the first inclined surface 121a and the second inclined surface 121b of the mold for forming the unit optical shape 121 are formed. This fine and irregular concavo-convex shape is formed by repeating plating of different conditions twice or more on the surface forming the first inclined surface 121a and the second inclined surface 121b of the mold or performing an etching process. 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 inclined surface 121a and the second inclined surface 121b by vapor deposition or the like.

Thereafter, 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 and form a flat surface, and the protective layer 15 is laminated to form an ultraviolet curable resin. The second optical shape layer 14 and the protective layer 15 are integrally formed by curing. Thereafter, the screen 10 is completed by cutting into a predetermined size.
The base material layer 11 and the protective layer 15 may be a single wafer shape or a web shape.

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

FIG. 8 is a diagram illustrating a state of image light and external light on the screen 10 according to the first embodiment. FIG. 8 shows a cross section corresponding to the cross section shown in FIG. In FIG. 8, for easy understanding, there is no difference in refractive index between the interface between the base material layer 11 and the first optical shape layer 12 in the screen 10 and the interface between the second optical shape layer 14 and the protective layer 15. Although there is no refractive index difference, 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 are shown.
Of the image light L1 projected from the image source LS positioned 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 up. The image light L2 does not reach the observer O2 positioned in the front direction on the light incident side (image source side) of the screen 10.

In addition, a part of the image light L3 out of the image light L1 enters 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 (first low refractive index portion 131). ) And is incident on the interface K between the second low-refractive-index part 132 and the second optical shape layer 14 at an angle greater than the critical angle, and is totally reflected at the interface K and is emitted from the screen 10 on the light output side (+ Z side). Are emitted toward the observer O1 side located in the front direction. The image light L3 is diffused by a fine and irregular concavo-convex shape of the interface K (the surface of the low refractive index layer 13), and provides a good field of view to an observer O1 positioned in the front direction on the light output side of the screen 10. An image having a corner can be displayed.
A part of the image light is reflected when the image light L3 is incident on the first low refractive index portion 131, but the amount of light is small, so that the observer O2 located on the incident light side visually recognizes the image. There is nothing. When the image light L3 is incident on the first low refractive index portion 131 (first inclined surface 121a) at an incident angle of 0 ° or near 0 °, the reflected light also has a reflection angle of 0 ° or 0 °. Since it is close to 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.

Of the image light incident on the screen 10, a part of the image light L 4 is incident on the first inclined surface 121 a at a angle less than the critical angle, passes through the first low refractive index portion 131, and is above the screen 10 from the light exit side. To exit. This image light L4 does not reach the observer O1 located in the front direction of the screen 10 on the light output side.
In the present embodiment, the angle θ3 is an acute angle, and as described above, the interface is compared with the case where the low refractive index layer is formed on the unit lens having the circular Fresnel lens shape when the apex angle of the unit lens is 90 °. The area of K (second inclined surface 121b) can be increased, such image light L4 can be reduced, the image light L3 reaching the observer O1 can be increased, and 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 FIGS. 2 and 4, etc.) of the second inclined surface 121 b is the image light at each point in the screen vertical direction of the screen 10. Since it 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, light from the outside such as sunlight and illumination light other than image light incident on the screen 10 from above the light incident side (−Z side) or the light outgoing side (+ Z side) (hereinafter referred to as external light) will be described. To do.
As shown in FIG. 8, out of the external light G1 incident on the screen 10 from the light incident side, a part of the external light G2 is reflected by the light incident surface 10a of the screen 10 and travels downward from the screen 10 so that the observer It does not reach O2.
In addition, a part of the external light G1 that is incident on the screen 10 is incident on the second inclined surface 121b at a small incident angle that is equal to or greater 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 downward on the light exit side of the screen 10 without being incident on the interface with the screen 14, and part of the light exits from the light exit surface 10b downward on the light exit side, or part of the light is reflected by the light exit surface 10b and proceeds downward in the screen 10. It gradually attenuates.

Further, a part of the external light G4 incident on 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 in the same manner as the external light G2 described above. Head side down. Further, a part of the external light G4 is incident on the interface (first inclined surface 121a) between the first low refractive index portion 131 and the first optical shape layer 12 to be reflected or the like (including total reflection). Head downward on the light emission side.
And most of the external light G4 is totally reflected by the light exit surface 10b, proceeds downward in the screen 10 and gradually attenuates, and part of the light is emitted downward from the light exit surface 10b.

Further, of the external light G5 incident on the screen 10 from the light output side, a part of the external light G6 is reflected by the light output surface 10b of the screen 10 and travels downward from the screen 10 and does not reach the observer O1.
Of the external light G5, external light G7 incident on 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 less than the critical angle, and the first low refractive index. The light passes through the portion 131 and travels downward on the light incident side of the screen 10. The external light G7 is emitted downward on the light incident side of the screen 10, or totally reflected by the light incident surface 10a of the screen 10 and proceeds downward inside the screen 10, and gradually attenuates.
Accordingly, since any external light that enters the screen 10 from above the light incident side and light output side does not reach the observers O1 and O2, it is possible to suppress a decrease in the contrast of the image due to the external light.

  Further, since the screen 10 does not include a light diffusion layer containing diffusing particles or the like that diffuse light, the external lights G8 and G9 that enter the screen surface at a small incident angle and pass through the screen 10 are 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 incident side (−Z side) and the outgoing side (+ Z side), the scenery on the other side of the screen 10 is obtained. It can be observed with high transparency without blurring or white blurring.

  Here, the conventional transmissive screen is designed so that the transparency of the screen is very low so that the image source side cannot be seen through, and the scenery beyond the screen cannot be seen. In addition, in order to provide an image having a sufficient viewing angle, the conventional transmissive screen is often provided with a light diffusing layer containing diffusing particles that diffuse light, and the transparency of other layers is increased. Even if it is improved, outside light is also diffused by the diffusing particles of the light diffusion layer, so that there is a problem that the scenery on the other side of the screen is observed blurred or whitened.

However, the screen 10 of this embodiment has no diffusing action except that the surface of the low-refractive index layer 13 has a fine and irregular concavo-convex shape. And diffused only when totally reflected at the interface K between the second optical shape layer 14 and the second optical shape layer 14. Further, the transmitted light is not diffused on the screen 10 of the present embodiment.
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 emission side (+ Z side) and in a state where no image light is projected. The scenery on the other side (-Z side) of the screen 10 is not visually blurred or blurred, and can be seen well by the observer O1, and high transparency can be realized.
Moreover, according to the present embodiment, since the angle θ3 is an acute angle, the screen 10 can increase the area of the interface K that is the total reflection surface, can increase the amount of light toward the observer O1 side on the light output side, and is bright and good. Can be displayed. In addition, according to the present embodiment, since the angle φ1 satisfies φ1 ≧ arcsin (1 / n), the screen 10 can effectively suppress a decrease in the contrast of an image due to external light.

In addition, according to the present embodiment, the screen 10 does not diffuse transmitted light and has high transparency. Therefore, in a state where no image light is projected, the light incident side (−Z side) of the screen 10. The scenery on the other side (+ Z side) of the screen 10 is also visually recognized by the observer O2 who is in the room.
In addition, according to the present embodiment, the screen 10 does not diffuse transmitted light and has high transparency. Therefore, even when image light is projected on the screen 10, the observers O1 and O2 A part of the scenery on the other side (light incident side, light outgoing side) of the screen 10 can be visually recognized through the screen 10.

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

(Second Embodiment)
FIG. 9 is a diagram illustrating the layer configuration of the screen 20 according to the second embodiment. 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 viewed 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, parts having the same functions as those of the first embodiment described above are denoted by the same reference numerals or the same reference numerals at the end thereof, and repeated descriptions are appropriately omitted.
The screen 20 of the second embodiment includes a base material layer 11, a first optical shape layer 22, a low refractive index layer 13, a second optical shape layer 14, and a protective layer 15 from the light incident side, and a light incident surface 20a and a light exit surface. It has a surface 20b. This screen 20 is applicable 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 light output side surface. The unit optical shapes 221 are columnar, and a plurality of units are arranged in the vertical direction of the screen (Y direction) with the horizontal direction of the screen (X direction) as the longitudinal direction.
The unit optical shape 221 has a triangular shape in which the cross-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 includes an angle θ1 formed by the first inclined surface 121a being parallel to the screen surface, an angle θ2 formed by the second inclined surface 121b being parallel to the screen surface, and the first inclined surface 121a and the second inclined surface 121b. The angle θ3 formed, the angle φ1 formed by the first inclined surface 121a with the normal direction of the screen surface, the angle φ2 formed by the second inclined surface 121b with the normal direction of the screen surface, the arrangement pitch P, the lens height h, etc. This is the same as the unit optical shape 121 shown in the embodiment.

According to the present embodiment, as in the first embodiment described above, a good video can be displayed, and the screen 20 and the rear projection display device 1 having transparency can be obtained.
Moreover, 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 enlarge the screen 20 and Even when the screen is enlarged, the manufacturing cost of the screen 20 can be suppressed.

(Deformation)
Without being 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 each embodiment, a hard coat layer may be provided on the light incident side (−Z side) of the screens 10 and 20 for the purpose of preventing scratches. 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 (surfaces on the light incident side of the base material layer 11). And so on.
Further, not only the hard coat layer but also a layer having necessary functions as appropriate, such as an antireflection function, an ultraviolet absorption 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. Moreover, the base material layer 11 may have these functions.

In each embodiment, the support plate 50 may be disposed on the light incident side (−Z side) of the base material layer 11 via the bonding layer 51. One or a plurality of layers having necessary functions such as a hard coat function, an antireflection function, an ultraviolet absorption function, an antifouling function, an antistatic function and the like may be selected and provided, and the protective layer 15 provides these functions. You may have. Further, a touch panel layer or the like may be provided on the light output side of the protective layer 15 or the like.
When the support plate 50 is disposed 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. Thus, the amount of light incident on the screen may be improved.

(2) In each embodiment, the low refractive index layer 13 is only required to be formed on at least a part of the second inclined surfaces 121b and 221b, and the screen 10 is not formed on the first inclined surfaces 121a and 221a. The transparency of 20 may be improved.
In each embodiment, the low refractive index layer 13 may be formed by coating the first slopes 121a and 221a and the second slopes 121b and 221b with a highly transparent fluorine-based coating agent.
In each embodiment, a layer having an anchor function or the like is provided on at least one of the surface on the first optical shape layer 12, 22 side and the surface on the second optical shape layer 14 side of the low refractive index layer 13. May be.

(3) In each embodiment, the video source LS has a longer projection distance of video light than the one shown in each embodiment and there is no incident angle θa of the video light on the screen unless there is a problem such as a space to arrange. You may use a thing with a small variation | change_quantity.
FIG. 11 is a diagram showing a modified rear projection display device 3. FIG. 11 shows the rear projection display device 3 as viewed from the side. The rear projection display device 3 in a modified form includes an image source LS3 and a screen 30 and is bonded to a support plate 50 located on the light output side (+ Z side) of the screen 30 via a bonding 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 first embodiment described above, and the incident angle of the image light L incident on the screen 30. The change amount of 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 are in accordance with 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 range of the incident angle θa of the image light in an area corresponding to the screen of the light incident surface 30a of the screen 30 is about 35 to 65 ° as an example. 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.

In the case of such a configuration, the space as the rear projection display device 3 is increased. However, as in the above-described embodiment, the transmissive screen 30 and the rear projection type have high transparency and can display a good image. The display device 3 can be obtained.
Further, by adopting such a form, the amount of change in the incident angle θa of the image light L to the screen 30 becomes small, so the first optical shape layer 12, the second optical shape layer 14, the low refractive index layer 13, etc. It is easy to select the optimal refractive index.
Further, by adopting such a form, the image light L is 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, thereby obtaining an effect of improving the contrast of an image.

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

(5) In each embodiment, the unit optical shapes 121 and 221 may be, for example, a combination of a curved surface and a flat surface, or may be a folded surface.
In each embodiment, unit optical shape 121, 221 is good also as a polygonal column shape formed by a plurality of three or more surfaces.

(6) In each embodiment, the unit optical shapes 121 and 221 positioned at the upper part of the screens 10 and 20 have curved shapes such that the second inclined surfaces 121b and 221b are convex with respect to the upper side in the vertical direction of the screen. You may do it.
FIG. 12 is a diagram showing a unit optical shape 421 of the screen 40 according to a modified embodiment. FIG. 12 shows a cross section corresponding 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 inclined surface 421a and a second inclined surface 421b, and the second inclined surface 421b is convex with respect to the upper side in the vertical direction of the screen. It has a curved shape. A low refractive index layer 43 (a first low refractive index portion 431 and a 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 can be efficiently reflected on the light output side of the screen 40. It can be directed to the observer O1 located in the (+ Z side) front direction.
Further, even when the refractive index difference between the low refractive index layer 43 and the second optical shape layer 14 is smaller than that in the first embodiment, the second low refractive index portion 432 and the second optical refractive index portion 432 and the second optical refractive index portion 432 are similar to the image light Le. Two total reflections can be made twice or more at the interface K with the optical shape layer 14 and directed to the observer O1 on the light output side.
Accordingly, by having such a curved shape, even if the interface K between the second low-refractive index portion 432 and the second optical shape layer 14 at the top of the screen is difficult for the image light to be directed toward the observer O1 side on the light output side, The image light can be efficiently directed to the observer O1 side, and the reduction in the brightness of the image at the top of the screen 40 can be improved.

(7) In each embodiment, the screens 10 and 20 are colored with a dark coloring material such as black or gray, have a light absorption property, and have a light absorption layer that absorbs a part of incident light. You may have. This light absorption layer may be located on the light exit side (+ Z side) with respect to the low refractive index layer 13, or may be located on the light incident side (−Z side).
By providing the light absorbing layer on the screens 10 and 20, the stray light that travels through the screens 10 and 20 while being totally reflected at the interface between the screens 10 and 20 and air, which is caused by external light incident on the screens 10 and 20, is absorbed It is possible to suppress a decrease in the contrast of the image due to stray light.

When the light absorption layer is located on the light output side with respect to the low refractive index layer 13, it is possible to reduce the black luminance of the image and to absorb 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 with respect to the low refractive index layer 13, external light incident from the light incident side can be absorbed and the contrast of the image can be improved.
Further, the low refractive index layer 13 may have a light absorption function, or a light absorption layer may be formed on the light incident side or the light output side of the low refractive index layer 13.
In addition, the above-mentioned light absorption layer is good also as a layer which does not contain a coloring material but is a transparent layer, and has a light absorption effect | action.

(8) In each embodiment, the video source LS has been described with an example in which the video source LS is located at the center of the screens 10 and 20 in the horizontal direction of the screen and below 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 obliquely below the screens 10 and 20 and project the image light from the oblique direction in the left-right direction of the screen with respect to the screens 10 and 20.
In this case, the arrangement direction of the unit optical shapes 121 and 221 is inclined according to the position of the video source LS. By adopting such a form, the position of the video source LS and the like 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 video source LS is viewed from the normal direction of the screen surface when the screens 10 and 20 are in the horizontal direction of the screen. It is good also as a form which is located in the center of the screen and above the screen.

(9) In each embodiment, when the first optical shape layers 12 and 22 and the second optical shape layer 14 have sufficient thickness, rigidity, etc., the screens 10 and 20 It is good also as a form which is not provided with the protective layer 15, and is good also as a form which is not provided with either one.
Moreover, in each embodiment, the screens 10 and 20 are good also considering the at least one of the base material layer 11 and the protective layer 15 as a plate-shaped member which has light transmittances, such as a glass plate. At this time, the first optical shape layer 12 or the like may be bonded to a glass plate or the like via a bonding layer (not shown) formed of an adhesive, an adhesive, or the like.

(10) In each embodiment, the video source LS may be, for example, a video source that projects video 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, when the incident angle (Brewster angle) at which the reflectance of the image light (P wave) projected onto the screens 10 and 20 is zero is θb (°), the incident angle θa is (θb-10). It is set in the range of not less than 85 ° and not more than 85 °. For example, when the incident angle θb at which the reflectance of the image light projected onto 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 °.

Thus, by using the image source LS that projects image light having a P-wave polarization component, even when the incident angle θa to the screens 10 and 20 is large, specular reflection on the surfaces of the screens 10 and 20 is suppressed. 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, the reflection of the image light on the screen surface when entering the screens 10 and 20 can be reduced, and the brightness and clearness of the image can be improved.
The angle θb (Brewster angle) varies depending on the material of the surfaces of the screens 10 and 20 onto which the image light is projected.
Moreover, in the case of such a form, as the base material layer 11 and the protective layer 15, the TAC sheet-like member is suitable.

(11) In each embodiment, the rear projection display device 1 has been described as being disposed in a show window of a store or the like. However, the present invention is not limited to this, and for example, video display in an indoor partition, an exhibition, or the like The present invention can also be applied to devices, display panels for advertising, etc. that are placed indoors.

  In addition, although this embodiment and modification can also be used in combination as appropriate, detailed description is abbreviate | omitted. Further, the present invention is not limited by the embodiments described above.

DESCRIPTION OF SYMBOLS 1 Image display apparatus 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)

The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected and demonstrated, it is not limited to this.
The invention of claim 1 is a transmissive screen that transmits image light and displays the light incident surface (10a, 20a) on which the image light is incident and the light incident surface to emit the image light. In the thickness direction of the light exit surface (10b, 20b) and the transmission screen, the light exit surface is located between the light entrance surface and the light exit surface, a plurality of light sources are arranged along a predetermined direction, and are incident from the light entrance surface. A total reflection surface (K) that totally reflects at least a part of the image light and directs it toward the light exit surface, and a light output side end of the total reflection surface and a light incident side end of the total reflection surface adjacent thereto The transmission screen (10, 20) is characterized in that an angle (θ3) formed between the connection surface formed by the portion and the total reflection surface is an acute angle.
According to a second aspect of the present invention, in the transmission screen according to the first aspect, an angle formed by the connection surface and a normal direction of the screen surface is φ1, and a refractive index of a region adjacent to the connection surface is n. The transmission screen (10, 20) is characterized by satisfying φ1> 1/2 × arcsin (1 / n) .
According to a third aspect of the present invention, in the transmissive screen according to the first or second aspect, an angle formed by the connection surface and a normal direction of the screen surface is φ1, and refraction of a region adjacent to the connection surface is made. The transmission screen (10, 20) is characterized by satisfying φ1 ≧ arcsin (1 / n) when the rate is n .
According to a fourth aspect of the present invention, in the transmissive screen according to any one of the first to third aspects, the total reflection surface (K) has a fine irregular irregular shape. The transmissive screen (10, 20).
According to a fifth aspect of the present invention, in the transmissive screen according to any one of the first to fourth aspects, an angle (θ2) between the total reflection surface (K) and a surface parallel to the screen surface is: It is a transmission type screen (10, 20) characterized by becoming gradually smaller from one side to the other along the arrangement direction of the total reflection surface.
A sixth aspect of the present invention is the transmissive screen according to any one of the first to fifth aspects, wherein the total reflection surface (K) is a low refractive index layer having a lower refractive index than an adjacent layer. The transmission screen (10, 20) is characterized in that it is formed at the interface between (13) and a layer (14) adjacent thereto.
The transmissive screen according to claim 7 is the transmissive screen according to claim 6, wherein the low refractive index layer (13) is also formed on the connection surface. It is.
The invention according to claim 8 is the transmissive screen according to any one of claims 1 to 7, wherein the first surface (121a) and the second surface facing the first surface (121a) are convex on the light output side. Unit optical shape (121) having (121b) has an optical shape layer (12) having a circular Fresnel lens shape arranged concentrically around one point (C) on the light-emitting side surface, A low refractive index layer (13) having a refractive index lower than that of the adjacent layer is formed on a part of the second surface, and an interface between the low refractive index layer and the adjacent layer (14) is the total reflection. An angle (θ2) between the total reflection surface and the plane parallel to the screen surface gradually decreases with increasing distance from the one point along the arrangement direction of the total reflection surface. A mold screen (10).
The invention of claim 9 is the transmission screen according to claim 8, wherein the one point (C) is located outside the display area of the transmission screen. .
According to a tenth aspect of the present invention, in the transmissive screen according to any one of the eighth or ninth aspects, the low refractive index layer (13) is the first surface corresponding to the connection surface ( 121a) is a transmissive screen (10) characterized in that it is also formed.
The invention of claim 11 is the transmissive screen according to any one of claims 6 to 10, 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) characterized.
A twelfth aspect of the present invention is the transmission screen according to any one of the first to eleventh aspects, wherein a light diffusing layer containing a diffusing material that diffuses light is not provided. It is a transmissive screen (10, 20).
The invention according to claim 13 is the transmission type screen according to any one of claims 1 to 12, further comprising a light absorption layer that absorbs part of incident light. Screen (10, 20).
The invention of claim 14 is the transmission screen (10, 20) according to any one of claims 1 to 13, a video source (LS) for projecting video light on the transmission screen, Is a rear projection display device (1).
According to a fifteenth aspect of the present invention, in the rear projection display device according to the fourteenth aspect, in the arrangement direction of the total reflection surfaces (K) of the transmission screens (10, 20), the total reflection surface is a screen surface. The rear projection display device (1) includes an angle (θ2) formed with a parallel plane that decreases with distance from the video source (LS).

The angle formed by the first slope 121a and a plane parallel to the screen surface is θ1. The angle formed by the second inclined surface 121b and a plane parallel to the screen surface is θ2. The angles θ1 and θ2 satisfy the relationship 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 direction of the screen surface is φ1, and the angle formed by the second inclined surface 121b with the normal direction of the screen surface is φ2. The sum of the angles φ1 and φ2 is an 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 preferable. 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 becomes the valley bottom between the unit optical shapes 121) is h.

Claims (15)

A transmissive screen that transmits image light and displays the image light,
A light incident surface on which image light is incident;
A light exit surface facing the light entrance surface and emitting image light;
In the thickness direction of the transmissive screen, a plurality of light beams are arranged between the light incident surface and the light exit surface and arranged in a predetermined direction, and at least part of the image light incident from the light incident surface is totally reflected. A total reflection surface directed toward the light exit surface;
With
The angle formed between the total reflection surface and the connection surface formed by the light emission side end of the total reflection surface and the light incident side end of the total reflection surface adjacent thereto is an acute angle,
A transmissive screen characterized by The transmissive screen according to claim 1,
When the angle formed by the connecting surface and the normal method of the screen surface is φ1,
φ1> 1/2 × arcsin (1/2)
Meeting,
A transmissive screen characterized by The transmissive screen according to claim 1 or 2,
When the angle formed by the connecting surface and the normal method of the screen surface is φ1,
φ1 ≧ arcsin (1/2)
Meeting,
A transmissive screen characterized by The transmissive screen according to any one of claims 1 to 3, wherein
The total reflection surface has a fine and irregular concavo-convex shape;
A transmissive screen characterized by The transmissive screen according to any one of claims 1 to 4, wherein
The angle formed by the total reflection surface and a surface parallel to the screen surface is gradually reduced from one to the other along the arrangement direction of the total reflection surface,
A transmissive screen characterized by The transmission screen according to any one of claims 1 to 5,
The total reflection surface is formed at an interface between a low refractive index layer having a refractive index lower than that of an adjacent layer and an adjacent layer;
A transmissive screen characterized by The transmissive screen according to claim 6,
The low refractive index layer is also formed on the connection surface;
A transmissive screen characterized by The transmissive screen according to any one of claims 1 to 7,
Optical shape having a circular Fresnel lens shape on the light-emitting side surface, which is convex on the light-emitting side and has a unit optical shape having a first surface and a second surface facing the first surface, concentrically arranged around one point Has a layer,
A low refractive index layer having a refractive index lower than that of an adjacent layer is formed on at least a part of the second surface, and an interface between the low refractive index layer and a layer adjacent thereto is the total reflection surface,
An angle formed by the total reflection surface and a plane parallel to the screen surface is gradually reduced as the distance from the one point is increased along the arrangement direction of the total reflection surface.
A transmissive screen characterized by The transmission screen according to claim 8, wherein
The one point is located outside the display area of the transmissive screen;
A transmissive screen characterized by The transmission type screen according to any one of claims 8 and 9,
The low refractive index layer is also formed on the first surface corresponding to the connection surface;
A transmissive screen characterized by The transmission screen according to any one of claims 6 to 10, wherein
The low refractive index layer has a thickness of 1 μm or more and 10 μm or less,
A transmissive screen characterized by 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;
A transmissive screen characterized by The transmission screen according to any one of claims 1 to 12,
A light absorption layer that absorbs part of the incident light;
A transmissive screen characterized by The transmissive screen according to any one of claims 1 to 13,
An image source for projecting image light onto the transmissive screen;
A rear projection display device comprising: The rear projection display device according to claim 14,
In the arrangement direction of the total reflection surfaces of the transmissive screen, an angle formed by the total reflection surface and a surface parallel to the screen surface decreases as the distance from the image source increases.
A rear projection display device comprising:

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