JP2016062031A - Reflective screen and image display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflective screen and image display device, capable of displaying good high-contrast images even in a bright room environment.SOLUTION: A reflective screen 10 includes; a prism layer 11 comprising a plurality of unit prisms 112, each having a convex surface on a rear side, arranged in a plane parallel to a screen surface; an air layer 12 provided on the rear side of the prism layer 11 in a thickness direction of the reflective screen 10 to abut at least portions of the rear-side surface of the unit optical pattern (of the prism layer), and having a refractive index lower than that of the unit prisms 112 and light transmissivity; a light absorption layer 14 provided on the rear side of the air layer 12 in the thickness direction of the reflective screen 10 to absorb light; and a light control layer 13 provided on an image source side of the prism layer 11 in the thickness direction of the reflective screen 10 and comprising light transmissive portions 132 that transmit light and light absorption portions 133 that absorb light alternately arranged along the screen surface in a direction parallel to a direction in which the unit prisms 112 are arranged.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a reflective screen and an image display system for displaying an image by reflecting projected image light.

Conventionally, reflective screens that reflect image light projected from a projector or the like and display the image so as to be observable are widely known (see, for example, Patent Documents 1 and 2).
Reflective screens are often used in home theaters, conferences, presentations, and the like, and there is a demand to use them in a bright room environment in addition to a dark room environment that is conventionally used.

JP 2002-31507 A JP 2010-262046 A

  However, in a bright room environment, since external light such as illumination light enters the reflective screen, there is a problem that the contrast of the image is lowered.

  An object of the present invention is to provide a reflective screen and an image display device capable of displaying a good image with high contrast even in a bright room environment.

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 reflective screen that reflects the image light projected from the image source and displays the image so that the image can be observed, and the unit optical shape (112) that is convex on the back side is parallel to the screen surface. A plurality of optically shaped layers (11) arranged along a plane, and provided on the back side of the optically shaped layer in the thickness direction of the reflective screen, and an interface with at least a part of the back side surface of the unit optical shape A low refractive index layer (12) having a refractive index lower than that of the unit optical shape and having light transmittance, and provided on the back side of the low refractive index layer in the thickness direction of the reflective screen. A light absorbing layer (14) that absorbs light, a light transmitting portion (132, 232, 332) that transmits light and is provided closer to the image source than the optical shape layer in the thickness direction of the reflective screen. Light absorption part (1 3, 333, 333), and light control layers (13, 23, 33) arranged alternately in a direction parallel to the arrangement direction of the unit optical shapes along the screen surface, A reflective screen (10).
According to a second aspect of the present invention, in the reflective screen according to the first aspect, the unit optical shape (112) has a substantially triangular prism shape, and the left-right direction of the screen in the usage state of the reflective screen is the longitudinal direction. A reflective screen (10) characterized by being arranged in the vertical direction.
According to a third aspect of the present invention, in the reflective screen according to the first or second aspect, the light absorbing portion (133, 233) is a cross section in a cross section parallel to the arrangement direction and the direction orthogonal to the screen surface. A reflective screen (10) characterized in that the shape is substantially wedge-shaped.
According to a fourth aspect of the present invention, in the reflective screen according to any one of the first to third aspects, the unit optical shape (112) is orthogonal to the screen surface and parallel to the arrangement direction. The reflective screen (10) is characterized in that the cross-sectional shape in a simple cross-section is a substantially triangular shape and the apex angle is 77 to 131 °.
The invention of claim 5 comprises the reflective screen (10) according to any one of claims 1 to 4, and an image source (LS) for projecting image light onto the reflective screen. A video display system (1).

  According to the present invention, there is an effect that it is possible to provide a reflective screen and an image display device capable of displaying a good image with high contrast even in a bright room environment.

It is a figure explaining video display system 1 of an embodiment. It is a figure which shows the layer structure of the reflection type screen 10 of embodiment. It is a figure explaining the light control layer 13 of embodiment. It is a figure explaining the prism layer 11 of embodiment. It is a figure explaining the mode of the image light L1 and external light G1, G2 which inject into the reflective screen 10 of embodiment. It is a figure explaining the other example of the light control layer 13 of embodiment. It is a figure explaining the reflective screen 50 of a deformation | transformation form. It is a figure which shows a mode that the surface layer 55 of the deformation | transformation form was seen from the image source side. It is a figure which shows the layer structure of the reflection type screen of a comparative example.

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, the terms “plate”, “sheet”, and the like are used, but these are generally used in the order of thickness, “plate”, “sheet”, “film”. Above all, it uses it. However, there is no technical meaning in such proper use, so these terms can be replaced as appropriate.
Numerical values such as dimensions and material names of the respective members described in the present specification are examples of the embodiment, and the present invention is not limited thereto, and may be appropriately selected and used.

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 of.
In this specification, the sheet surface indicates a surface in the planar direction of the sheet when viewed as the entire sheet. The same applies to the plate surface and the film surface.

(Embodiment)
FIG. 1 is a diagram illustrating a video display system 1 according to the present embodiment. FIG. 1A is a perspective view of the video display system 1, and FIG. 1B is a side view of the video display system 1.
The video display system 1 includes a reflective screen 10, a video source LS, and the like. In the video display system 1, the reflective screen 10 reflects the video light L projected from the video source LS and displays the video on the screen (display surface).
The video source LS is a video light projection device that projects the video light L onto the reflective screen 10. As the video source LS, a general-purpose projector or the like can be used.
As shown in FIG. 1, the image source LS passes through a point A that is the geometric center (the center of the screen) of the screen when the reflective screen 10 is used, and is on a straight line parallel to the normal direction of the screen surface. positioned. The image source LS is an image from the normal direction of the screen surface or a direction in which the angle formed with respect to the normal direction is 45 ° or less with respect to most of the screen (display surface) of the reflective screen 10. The light L can be projected.

The reflective screen 10 reflects the image light L projected by the image source LS toward the observer O and displays an image. Here, an example is given in which the screen (display surface) of the reflective screen 10 is a substantially rectangular shape with the long side direction being the left-right direction of the screen when viewed from the observer O side when the reflective screen 10 is in use. explain.
In the following description, the screen vertical direction and the screen horizontal direction are the screen vertical direction (vertical direction) and the screen horizontal direction (horizontal direction) when the reflective screen 10 is used unless otherwise specified. And

In addition, in each of the following drawings including FIG. 1, an XYZ coordinate axis in which the horizontal direction of the screen is the X direction, the vertical direction of the screen is the Y direction, and the direction orthogonal to the screen surface (thickness direction of the reflective screen 10) is the Z direction. Provided. When viewed from the observer O, the X1 side is the left side of the screen in the horizontal direction, the X2 side is the right side of the screen in the horizontal direction, the Y1 side is the lower side of the screen in the vertical direction, and the Y2 side is the upper side of the screen. The Z1 side is the back side (back side), and the Z2 side is the video source side (observer side).
Here, the screen surface indicates a surface in the planar direction of the reflection type screen 10 when viewed as the reflection type screen 10 as a whole, and is parallel to the screen (display surface) of the reflection type screen 10. . The normal direction of the screen surface (the direction perpendicular to the screen surface) is parallel to the thickness direction of the reflective screen 10.

In general, the reflective screen is a laminated body of thin layers made of a resin, etc., and the screen itself often does not have sufficient rigidity to maintain flatness. Therefore, the reflective screen 10 may be configured so as to maintain the flatness of the screen by being joined to the support plate (not shown) through a bonding layer (not shown) on the back side thereof. As the support plate, a flat plate member having high rigidity is preferable, and for example, a plate member such as a resin such as an acrylic resin or a PC resin, a metal such as aluminum, a wooden member, or the like can be used.
Further, the present invention is not limited to this, and the reflective 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.

FIG. 2 is a diagram showing a layer configuration of the reflective screen 10 of the present embodiment. In FIG. 2, a part of a cross section on the YZ plane (a plane orthogonal to the screen plane of the reflective screen 10 and parallel to the screen vertical direction) is shown in an enlarged manner.
The reflective screen 10 includes a surface layer 15, a light control layer 13, a bonding layer 16, a prism layer 11, an air layer 12, a light absorption layer 14, and the like in that order from the image source side (Z2 side).

The surface layer 15 is a layer provided on the most image source side (Z2 side) of the reflective screen 10. The surface layer 15 has a fine uneven shape (mat shape) on the surface of the image source side (Z2 side), and is formed of an ultraviolet curable resin (for example, urethane acrylate) having a hard coat function. Yes. Further, the surface layer 15 is formed integrally with a surface on the image source side (Z2 side) of the light control layer 13 described later (in this embodiment, a surface on the image source side of the light control base material portion 131). The thickness of the surface layer 15 is about 10 to 100 μm.
The surface layer 15 is not limited to this, and one or more necessary functions such as an antireflection function, an ultraviolet absorption function, an antifouling function, an antistatic function, and a touch panel function may be appropriately selected and provided. Further, as described above, the surface layer 15 may be formed directly by applying a resin having various functions to the image source side (Z2 side) surface of the light control layer 13 or not. It is good also as a form joined to the light control layer 13 with the adhesive material etc. of illustration.

Since the surface layer 15 of the present embodiment is formed by irregularly arranging fine irregularities on the surface, in addition to the above-described effects, for example, a function of preventing reflection of a light source image and external light, It also has a function to widen the viewing angle of images.
The thickness of the surface layer 15 can be appropriately set according to the desired function, the characteristics of the material used, and the like.
Further, the surface layer 15 is not limited to the above-described ultraviolet curable resin, and other ionizing radiation curable resins or the like may be used, or a material may be appropriately selected according to a desired function.

The light control layer 13 is a layer having a function of controlling the optical path of the image light and absorbing a part of unnecessary external light such as illumination light. The light control layer 13 is provided on the back side (Z1 side) of the surface layer 15.
The light control layer 13 includes a light control base part 131, a light transmission part 132, and a light absorption part 133.
The light control base material part 131 is a sheet-like member that has light permeability and serves as a base material (base) of the light control layer 13. The light control base material part 131 of the present embodiment has a surface layer 15 integrally formed on the image source side (Z2 side), and a plurality of light transmission parts 132 are arranged on the back side (Z1 side). Is formed.
The light control substrate 131 can be a sheet-like member made of a thermoplastic resin such as PET (polyethylene terephthalate) resin or PC (polycarbonate) resin.

FIG. 3 is a diagram illustrating the light control layer 13 of the present embodiment. 3, the light control layer 13 in the cross section shown in FIG. 2 is further enlarged.
The light transmission part 132 and the light absorption part 133 extend in parallel to the screen left-right direction (X direction), and extend in the screen vertical direction (surface on the back side of the light control layer 13) parallel to the screen surface (surface on the back side of the light control layer 13) (Along the Y direction).
The light transmitting portion 132 has a function of transmitting light, and the cross-sectional shape in the cross section shown in FIG. 3 is a substantially trapezoidal shape. In the light transmitting portion 132, the dimension W2 of the end on the back side (Z1 side) in the screen vertical direction (Y direction) is smaller than the dimension W1 of the end on the video source side (Z2 side).
The light transmission part 132 is formed on the back side (Z1 side) of the light control base material part 131 by an ionizing radiation curable resin such as an ultraviolet curable resin, a photocurable resin, or the like.

The light absorption part 133 has an action of absorbing light and is formed in a valley between the light transmission parts 132. The light absorbing portion 133 has an action of absorbing outside light, stray light, and the like.
The light absorbing portion 133 has a substantially wedge shape in cross section as shown in FIG. Here, the wedge shape means a shape that is wide at one end and gradually narrows toward the other end, and is a shape including a triangular shape or a trapezoidal shape.
3 has a substantially trapezoidal cross-sectional shape as shown in FIG. 3, and the dimension W3 of the image source side (Z2 side) end in the vertical direction of the screen is the end on the back side (Z1 side). The shape is smaller than the dimension W4. In addition, the light absorption part 133 is good also as a substantially triangular shape.

The light absorbing portion 133 is filled with an ionizing radiation curable resin such as an ultraviolet curable resin or a light curable resin containing light absorbing particles that absorb light by wiping (squeezing) between the light transmitting portions 132, It is formed by curing.
The light-absorbing particles used in the light-absorbing part 133 include light-absorbing colored particles such as organic fine particles colored with metal salts such as carbon black, graphite, black iron oxide, pigments, dyes, and colored glass beads. Is preferred. Moreover, it is good also as a colored particle which selectively absorbs a specific wavelength according to the characteristic of image light. The light absorbing particles preferably have an average particle size of 1 to 20 μm. When the average particle diameter of the light absorbing particles is smaller than this range, scraping by wiping becomes difficult, and the light absorbing particles are likely to remain on the light transmitting portion 132. Further, if the average particle diameter of the light absorbing particles is larger than this range, it becomes difficult to fill the gaps between the light transmitting portions 132. Therefore, the average particle diameter of the light absorbing particles is preferably in the above range.
The light absorbing unit 133 may have a form in which a black paint or the like is filled in the valleys between the light transmitting parts 132, or a black paint or the like may be applied to the slope portion of the light transmitting part 132.

The light transmission part 132 has an interface 134 (134a, 134b) with the light absorption part 133. It is assumed that the interface 134a of the light transmission part 132 is the upper side (Y2 side) in the screen vertical direction, and the interface 134b of the light transmission part 132 is the lower side (Y1 side) of the screen vertical direction. In the cross section shown in FIG. 3, the interfaces 134a and 134b form angles θ1 and θ2, respectively, with respect to the normal direction (Z direction) of the screen surface. In the present embodiment, θ1 = θ2.
The angles θ1 and θ2 are preferably set to 0 ° to 20 ° from the viewpoint of efficiently absorbing external light and efficiently transmitting video light.
The interface 134 may have a bent surface shape including a plurality of surfaces in the thickness direction, or may have a curved surface shape.

As shown in FIG. 3, the arrangement pitch of the light transmission parts 132 (the arrangement pitch of the light absorption parts 133) is P1 (P1 = W1 + W3 = W2 + W4). Further, the height (dimension in the Z direction) of the light absorbing portion 133 is H.
The ratio H / P1 between the arrangement pitch P1 and the height H preferably satisfies 0.3 ≦ H / P1 ≦ 0.8 from the viewpoint of displaying a bright and high-contrast image.
When H / P1 <0.3, the light absorption portion 133 provided in the light control layer 13 is sparse, the amount of external light absorbed by the light absorption portion 133 is reduced, and the contrast improvement effect cannot be obtained. . Further, when h / P> 0.8, the image light absorbed by the light absorption unit 133 is increased, which is not preferable because the image becomes dark. Therefore, the ratio H / P1 preferably satisfies 0.3 ≦ H / P1 ≦ 0.8.
The light transmission part 132 may be formed of a thermoplastic resin. At this time, if the light control layer 13 has sufficient rigidity as a layer, the light control base part 131 is not provided. Also good.

The bonding layer 16 is a layer formed of a light-transmitting pressure-sensitive adhesive or adhesive, and is a layer that integrally bonds the prism layer 11 and the light control layer 13 together.
For the bonding layer 16, an adhesive that exhibits adhesiveness due to irradiation of ultraviolet rays, pressure, or the like is preferably used.

FIG. 4 is a diagram illustrating the prism layer 11 of the present embodiment. 4, the prism layer 11, the air layer 12, and the light absorption layer 14 in the cross section shown in FIG. 2 are further enlarged.
The prism layer 11 is an optical shape layer including the prism base portion 111 and the unit prism 112. The prism layer 11 is provided on the back side (Z1 side) of the light control layer 13.
The prism base 111 is a layer that serves as a base (base) for the prism layer 11. The prism base 111 may be a sheet-like member made of a thermoplastic resin such as PC resin or PET resin.

The unit prism 112 has a substantially triangular prism shape that protrudes toward the back side (Z1 side). The horizontal direction (X direction) of the screen is the longitudinal direction (ridge line direction), and the vertical direction of the screen (Y direction) is along the screen surface. A plurality of unit optical shapes are arranged. The unit prism 112 is integrally formed on the rear surface of the prism base 111.
The unit prism 112 is formed of an ionizing radiation curable resin such as an ultraviolet curable resin or an electron beam curable resin. The unit prism 112 is not limited to this, and may be formed by an extrusion molding method, an injection molding method or the like integrally with the prism base portion 111 using a thermoplastic resin. At this time, the prism layer 11 is formed as a layer. In other words, the prism base 111 may be omitted. The method for forming the unit prism 112 and the prism base 111 may be freely selected as appropriate.

The unit prism 112 has a substantially triangular cross-section in the YZ plane (a direction orthogonal to the screen plane and a plane parallel to the arrangement direction of the unit prisms 112).
The unit prisms 112 have a triangular prism shape convex toward the back side, and are arranged in the screen vertical direction (Y direction) with the screen horizontal direction (X direction) as the longitudinal direction.
The unit prism 112 has two side surfaces 112a and 112b. Of these two side surfaces, the side surface 112a is the upper side (Y2 side) side of the screen in the vertical direction of the screen and the side surface 112b is the lower side (Y1 side), and each side is a plane parallel to the screen surface. Are an angle β and an angle γ, respectively. The apex angle of the unit prism 112 is an angle α. Further, the unit prism 112 has an arrangement pitch P2, the width of the unit prisms 112 in the arrangement direction (Y direction) is W5, and the arrangement pitch P2 is equal to the width W5 (P2 = W5).

The apex angle α of the unit prism 112 is preferably 77 to 131 °, and more preferably 90 °, from the viewpoint of efficiently reflecting video light toward the viewer. However, the apex angle α is appropriately changed according to the refractive index of the unit prism 112, the refractive index difference between the unit prism 112 and the air layer 12 which is a low refractive index layer described later, the position of the image source LS, and the like. Good.
The unit prism 112 of the present embodiment has an isosceles triangular cross section, α = 90 °, and β = γ = 45 °.

The arrangement pitch P2 of the unit prisms 112, the apex angle α, and the like are the size of the pixels of the image source LS (projector) that projects the image light, the projection angle of the image light of the image source LS (the image light on the screen surface). The angle can be appropriately changed according to the incident angle).
In the present embodiment, FIG. 2 and the like show an example in which the arrangement pitch P2 and the apex angle α of the unit prisms 112 are constant. However, the present invention is not limited to this, and the apex angle along the arrangement direction of the unit prisms 112 is shown. α, the arrangement pitch P2, the angle β, and the angle γ may be appropriately changed.
Moreover, although the cross-sectional shape of the unit prism 112 shows an example of an isosceles triangle shape, it is not limited to this, and may be an inequilateral triangle shape or the like, for example, in the arrangement direction (the screen vertical direction) Then, although it is an isosceles triangle shape, it is good also as a form which changes to an unequal triangle shape as it goes to the screen upper direction or the downward direction.
Further, the unit prisms 112 have a conical shape, a quadrangular pyramid shape, or the like, and may be arranged in the vertical direction of the screen and the horizontal direction of the screen.
Further, in the cross section shown in FIG. 4, the unit prism 112 may have a curved shape in which the top portion is convex, for example, on the back side, or the top portion may be planar. In the case of such a configuration, for example, there is an effect that the bonding with the light absorption layer 14 can be easily performed.

The air layer 12 is located on the back side (Z1 side) of the prism layer 11 and is alternately arranged with the unit prisms 112 in the arrangement direction (Y direction) of the unit prisms 112. That is, the side surfaces 112 a and 112 b of the unit prism 112 are in contact with the air layer 12 and serve as an interface with the air layer 12.
The air layer 12 is a low refractive index layer that is filled with air, has a refractive index lower than that of the unit prism 112, and has optical transparency.
In the present embodiment, the example in which the low refractive index layer is the air layer 12 formed by being filled with air has been described. However, the present invention is not limited to this. For example, the low refractive index layer may be formed of another gas such as nitrogen. Alternatively, it may be formed of a resin having a refractive index lower than that of the unit prism 112.

The light absorption layer 14 is a layer provided on the back side (Z1 side) of the air layer 12 and has a function of absorbing light.
The light absorption layer 14 of the present embodiment has a black sheet-like member as a base material, and has a black pressure-sensitive adhesive layer (not shown) on the surface that is the image source side (observation surface side) of the base material. ing. The light absorbing layer 14 is bonded to the apex t of the unit prism 112 by the pressure-sensitive adhesive layer, and is bonded to the prism layer 11 with the air layer 12 formed between the unit prisms 112. At this time, a part of the top part of the unit prism 112 including the vertex t of the unit prism 112 may enter the pressure-sensitive adhesive layer.

As the base material of the light absorption layer 14, a sheet-like member such as PET resin, PC resin, MS (methyl methacrylate / styrene / styrene) resin, MBS (methyl methacrylate / butadiene / styrene) resin, or acrylic resin may be used. it can. In this base material, when the pressure-sensitive adhesive layer is colored in a dark color such as black and has sufficient light absorption, a transparent or translucent member may be used, or a member such as white may be used. Also good. Moreover, as long as a base material is black etc. and it has sufficient light absorptivity, it is good also considering an adhesive layer as transparent or translucent.
The light absorption layer 14 may have a hard coat function, an ultraviolet absorption function, an antistatic function, an antifouling function and the like in addition to the function of absorbing light.

Here, video light and external light incident on the reflective screen 10 will be described.
FIG. 5 is a diagram illustrating the appearance of the image light L1 and the external lights G1 and G2 incident on the reflective screen 10 of the present embodiment. 5, a part of the cross section of the reflective screen 10 shown in FIG. 2 is further enlarged. 5A shows the state of the image light and the external light in the surface layer 15 and the light control layer 13, and in FIG. 5B, the image light and the external light in the prism layer 11, the air layer 12, and the light absorption layer 14 are shown. It shows the state of light. FIG.5 (c) is a figure which shows the c section detail of Fig.5 (a), and has shown the state of the external light G3 which injected into the light absorption part.
Further, in FIG. 5, for easy understanding, the refractive index of the surface layer 15, the light control base material part 131, the light transmission part 132, the prism base material part 111, and the unit prism 112 is assumed to be equal, and is indicated by an arrow. A diffusion action or the like due to the fine unevenness on the surface of the surface layer 15 with respect to the video light L1 and the external lights G1 and G2 is omitted.
As shown in FIG. 5, much of the image light projected from the image source LS has a small normal angle (45 ° or less) with the normal direction and the normal direction of the screen surface of the reflective screen 10 in the vertical direction of the screen. Incident from the direction (see video light L1). Then, the image light L1 passes through the surface layer 15, the light control layer 13, and the prism base portion 111 and enters the unit prism 112.

For example, the image light L1 is incident on one side surface 112a of the unit prism 112. At this time, the side surface 112a is in contact with the air layer 12 having a refractive index smaller than that of the unit prism 112, and the image light L1 is incident on the side surface 112a at an angle greater than or equal to the critical angle. Therefore, the image light L1 is totally reflected by the side surface 112a and is incident on the opposite side surface 112a.
Then, the image light L1 enters the side surface 112b at an angle greater than the critical angle, is totally reflected by the side surface 112b, travels toward the viewer, and exits in the front direction of the reflective screen 10 or in a direction having a small angle with the front direction. And reaches the observer O.

On the other hand, most of unnecessary external light such as illumination light is incident obliquely from above the reflective screen 10.
Out of such external light, external light G1 that is incident on the screen surface of the reflective screen 10 at a large incident angle enters the reflective screen 10 and is transmitted through the surface layer 15 and the light control substrate 131. Then, it enters the light transmission part 132. The external light G1 is incident on the interface 134b between the light transmission part 132 and the light absorption part 133 at an angle less than the critical angle and is absorbed by the light absorption part 133.

Further, the external light G2 having an incident angle with respect to the reflective screen 10 smaller than the external light G1 is incident on the reflective screen 10 and transmitted through the surface layer 15, the light control layer 13, and the prism base 111. The light enters the unit prism 112.
The external light G2 is incident on the reflective screen from the upper side of the screen in the vertical direction, and the incident angle with respect to the screen surface is larger than the image light L. Incident at an angle. Therefore, the external light G2 is refracted by the side surface 112b and enters the air layer 12, passes through the air layer 12, enters the light absorption layer 14, and is absorbed.

Here, when the refractive index of the light transmitting portion 132 is Np and the refractive index of the light absorbing portion 133 is Nb, the magnitude relationship between these refractive indexes can be appropriately set according to the desired optical performance.
For example, when Np> Nb, the image light that is incident on the interfaces 134a and 134b between the light transmitting portion 132 and the light absorbing portion 133 at an angle greater than the critical angle is totally reflected by the interfaces 134a and 134b. Can do. Therefore, when Np> Nb, the amount of image light absorbed by the light absorption unit 133 can be reduced, the luminance can be increased, and a bright image can be displayed.

Further, when Np ≦ Nb, the light incident on the interfaces 134a and 134b with the light absorbing unit 133 from the light transmitting unit 132 is not totally reflected, so that the light absorbing unit 133 is compared with the case where Np> Nb. Thus, external light and stray light can be absorbed more efficiently.
As described above, when Np> Nb, as shown in FIG. 5C, a part of the external light G3 is incident on the top of the light absorption unit 133 on the video source side, and the top light absorption. The light was transmitted through a region where no particles exist or between light-absorbing particles and the like, and was emitted to the light transmission unit 132 again as G3 ′. However, when Np <Nb, the external light G3 that is going to be emitted again to the light transmitting portion 132 can be totally reflected by the interface 134 and absorbed by the light absorbing particles of the light absorbing portion 133.
Therefore, when Np ≦ Nb (particularly Np <Nb), the contrast improvement effect can be further enhanced.

From the above, according to the present embodiment, the image light can be efficiently reflected to the observer O side, the outside light can be efficiently absorbed, and the outside light can reach the observer O side. Therefore, even in a bright room environment, a high-contrast, bright and good image can be displayed.
In addition, according to the present embodiment, it is not necessary to form a reflective layer of a metal vapor deposition film or a white or silver ink film as used conventionally, and the shape of the unit prism 112 of the prism layer 11 is also simple. Therefore, the reflective screen 10 can be easily manufactured, and the production cost can be suppressed. Therefore, it is possible to provide an inexpensive and favorable reflective screen 10 and video display system 1.

FIG. 9 is a diagram showing a layer structure of a reflective screen of a comparative example.
As shown in FIG. 9, the reflective screen of the comparative example is different from the reflective screen 10 of the present embodiment in that no light control layer is provided.
When external light is incident on the reflective screen of the comparative example, as shown in FIG. 9, a part of the external light G4 passes through the surface layer and the prism base material and enters the unit prism. When the light is refracted and emitted to the air layer side at the interface, is refracted and incident again on the unit prism side at the interface with the adjacent unit prism, and is totally reflected at the interface facing the interface and reaches the observer side There is.
Thus, if the light control layer is not provided on the reflective screen, the above-described external light (G4) may be observed on the viewer side.
On the other hand, the reflection type screen 10 of the present embodiment includes the light control layer 13 as described above, and absorbs the light absorption unit 133 even if the above-described external light G4 is emitted from the unit prism to the viewer side. And the occurrence of the above-mentioned problems can be suppressed.

The pitch P2 of the unit prisms 112 is preferably smaller than the pitch P1 of the light transmission parts 132. This is because if the pitch P2 of the unit prisms 112 is larger than the pitch P1 of the light transmitting parts 132, the light that is totally reflected at the interface of the unit prisms 112 and travels toward the observer side (Z2 side) It is because it can suppress entering into the (Z1 side) surface.
In addition, it is desirable that the pitch P1 of the light transmission parts 132 is not an integral multiple of the pitch P2 of the unit prisms 112 from the viewpoint of suppressing the occurrence of moire.

(Another example of the light control layer 13 of the embodiment)
FIG. 6 is a diagram illustrating another example of the light control layer 13 of the present embodiment. 6 shows a cross section of the light control layer corresponding to the cross section shown in FIG. 3. FIG. 6A shows a light control layer 23 as another example, and FIG. The light control layer 33 which is an example is shown.
Like the light control layer 23 shown in FIG. 6A, the light transmitting portion 232 may have a shape in which the size on the back side (Z1 side) in the arrangement direction is larger than the size on the video source side (Z2 side). At this time, the light absorption part 233 has a shape in which the dimension on the back side (Z1 side) in the arrangement direction is smaller than the dimension on the video source side (Z2 side). At this time, the light control base material portion 231 is positioned on the back side (Z1 side) with respect to the light transmission portion 232.
In the case of the reflection type screen including the light control layer 23 having such a form, in addition to the effect of displaying a good image with high contrast even in a bright room environment, the reflection type screen when not in use is further provided. The blackness of the screen is increased and the quality is improved.

Further, as in the light control layer 33 shown in FIG. 6B, the light transmitting portion 332 and the light absorbing portion 333 are rectangular in cross section in a cross section parallel to the arrangement direction and the direction orthogonal to the screen surface. It is possible to adopt a form (a form in which the dimensions on the back side (Z1 side) in the arrangement direction are equal to the dimensions on the video source side (Z2 side)). At this time, as shown in FIG. 6B, the light control layer 23 is configured such that the light control base material portion 331 is positioned on the image source side (Z2 side) of the light transmission portion 332, and the light transmission portion 332 and the light transmission portion 332. The absorbers 333 may be alternately arranged to form a surface on the back side (Z1 side) of the light control layer 33, or the light control base material portion 331 may be on the back side (Z1 side) of the light transmission portion 332. It is also possible to adopt a form in which the light transmitting part 332 and the light absorbing part 333 are alternately arranged to form the image source side (Z2 side) surface of the light control layer 33.
In the case of a reflective screen having such a light control layer 33, there is an effect that a good image can be displayed with high contrast even in a bright room environment.

In the light control layer 33, as shown in FIG. 6B, the angle between the interface 334 of the light transmitting portion 332 and the light absorbing portion 333 and the normal direction (Z direction) of the screen surface is 0 °. Although not shown, the shape may be a rectangular shape so that the back side (Z1 side) end of the light absorbing unit 333 is positioned above the video source side (Z2 side) end in the vertical direction of the screen. The light absorbing portion 333 may be inclined. In the case of such an inclination, the angle formed by the interface 334 between the light transmitting portion 332 and the light absorbing portion 333 and the normal direction of the screen surface is 0 ° or more and 10 ° or less, so that external light is efficiently absorbed. From the viewpoint of
In any of the light control layers 23 and 33, the difference in refractive index between the light transmitting portions 232 and 332 and the light absorbing portions 233 and 333 may be appropriately selected according to the desired optical performance or the like.

(Deformation)
The present invention is not limited to the above-described embodiments and the like, and various modifications and changes are possible, and these are also within the scope of the present invention.

(1) The surface layer 15 may have a form in which a plurality of unit lenses, unit prisms, and the like are arranged on the image source side (Z2 side) surface.
FIG. 7 is a diagram for explaining a modified reflective screen 50. In FIG. 7, the reflective screen 50 of a modified form passes through a point (corresponding to the point A in FIG. 1) at the center of the reflective screen 50, and in a cross section (YZ plane) perpendicular to the screen vertical direction and the screen surface. A part of the cross section is shown enlarged.
FIG. 8 is a diagram illustrating a state in which the modified surface layer 55 is viewed from the image source side (Z2 side).
The reflective screen 50 of the modified form has substantially the same form as the reflective screen 10 of the above-described embodiment except that the surface layer 55 is different. Accordingly, parts having the same functions are denoted by the same reference numerals or the same reference numerals at the end, and repeated description is appropriately omitted.
The reflective screen 50 in a modified form includes a surface layer 55, a light control layer 13, a bonding layer 16, a prism layer 11, an air layer 12, and a light absorption layer 14 in order from the image source side.
The surface layer 55 is integrally formed on the image source side surface of the light control layer 13 (light control substrate 131) with an ionizing radiation curable resin such as an ultraviolet curable resin, and on the image source side surface, A plurality of unit lenses 551 are formed.

The unit lens 551 has a substantially triangular shape in which a cross-sectional shape in a cross section parallel to the arrangement direction and the thickness direction (a cross section parallel to the arrangement direction and perpendicular to the sheet surface) is convex toward the image source side.
The unit lens 551 includes an incident surface 551a on which the projected image light is incident, and a total reflection surface 551b that totally reflects at least part of the light from the incident surface 551a.
Further, the unit lenses 551 are arranged concentrically around the point C as shown in FIG. This point C is outside the screen of the reflective screen 50 (outside the display area), and is located below the reflective screen 50 and at the center in the horizontal direction of the screen. That is, the surface layer 55 has a circular Fresnel lens shape formed of a so-called total reflection type unit lens on the surface on the image source side.
The surface layer 55 is not limited to this, and the surface layer 55 includes a substantially triangular prism-shaped unit lens 551 having an incident surface 551a and a total reflection surface 551b on the image source side surface. (A so-called total Fresnel lens shape composed of unit lenses 551) may be used.

The reflective screen 50 corresponds to a short-focus image source (projector) that has been widely used in recent years, and the incident angle of the image light L2 with respect to the reflective screen 50 is large as shown in FIG.
In the unit lens 551, the image light L2 projected from the image source is incident on the incident surface 551a and refracted toward the total reflection surface 551b and totally reflected by the total reflection surface 551b, as shown in FIG. It is deflected in a direction parallel to the normal direction of the screen surface or a small angle with the normal direction of the screen surface, and heads toward the back side (Z1 side). Then, the light is totally reflected by the side surfaces 112a and 112b of the unit prism 112, travels toward the image source side (Z2 side), and exits from the unit lens 551.

Further, as shown in FIG. 7, the external lights G3 and G4 such as illumination light enter the total reflection surface 551b from the upper side and are refracted, proceed to the back side, and are absorbed by the light absorption unit 133 and the light absorption layer 14. Is done.
Therefore, by providing such a surface layer 55, in addition to being able to display a good image with high contrast, it is possible to cope with a short-focus image source with a large projection angle of image light that has been widely spread in recent years, Space-saving in the depth direction of a video display system using a mold screen can be achieved.

The arrangement pitch of the unit lenses 551, the apex angle, the angle formed by the total reflection surface 551b and the incident surface 551a and the plane parallel to the screen surface, etc. may be constant in the arrangement direction of the unit lenses 551, respectively. May be appropriately changed.
The arrangement pitch of the unit lenses 551 depends on the size of the pixel of the video source LS that projects the video light, the projection angle of the video source (the incident angle of the video light on the screen surface of the reflective screen 50), and the reflection. It can be set as appropriate according to the screen size of the mold screen 50, the refractive index of each layer, and the like.

The unit lens 551 has an example in which the cross-sectional shape is a substantially triangular shape. However, the unit lens 551 has a function as an image light incident surface and a total reflection surface and a function as an image light exit surface. Is preferable, and may have a shape other than a triangular shape (for example, a substantially trapezoidal shape).
In addition, the surface layer 55 may be provided with a base material portion serving as a base for forming the unit lens 551, or may be integrally laminated with the light control layer 13 via a bonding layer or the like. Furthermore, the surface layer 55 may be formed of a thermoplastic resin.

(2) The prism base 111 may include a diffusing material that diffuses light. By using the prism base portion 111 as described above, it is possible to widen the viewing angle or improve the in-plane uniformity of brightness without increasing the layers constituting the reflective screen 10. In addition, the production cost can be reduced and the reflective screen 10 can be made thinner.
The light diffusing material is preferably a light-transmitting material, and examples thereof include acrylic-based, styrene-based, acrylic / styrene copolymers, silicone-based resin particles, and inorganic particles such as glass beads. The average particle diameter of these diffusing materials is preferably about 1 to 30 μm.
Further, the light control base material portion 131 may include a diffusing material as described above, or the light control base material portion 131 and the prism base material portion 111 may include a diffusing material. . Further, the bonding layer 16 may include a diffusing material.
Further, when it is not necessary to reduce the thickness, etc., it is not necessary to diffuse light between the prism layer 11 and the light control layer 13 or on the image source side (Z2 side) of the light control layer 13. The illustrated light diffusing layer may be further provided.

(3) The light transmission part 132 and the light absorption part 133 may have a cross-sectional shape in a cross section parallel to the arrangement direction and the thickness direction that is asymmetric in the arrangement direction. For example, the angles θ1 and θ2 formed by the interfaces 134a and 134b of the light transmitting portion with the light absorbing portion 133 and the normal direction of the screen surface may be different (θ1 ≠ θ2), or one of the interfaces may be bent. It is good also as a shape.
Further, the angles θ1 and θ2 formed by the interfaces 134a and 134b between the light transmitting portion 132 and the light absorbing portion 133 and the normal direction of the screen surface change gradually or stepwise along the arrangement direction (Y direction). It is good also as a form to do. The arrangement pitch P1 of the light transmission part 132 and the light absorption part 133 may be changed gradually or stepwise along the arrangement direction.

(4) The example in which the light control layer 13 is only one layer has been shown. However, the present invention is not limited to this. For example, the light transmission portion and the light absorption portion have the screen vertical direction (Y direction) as the longitudinal direction and the screen horizontal direction. A second light control layer (not shown) arranged in the (X direction) may be further laminated on the back side (Z1 side) of the light control layer 13 or the like.
The arrangement direction of the light transmission part and the light absorption part of the second light control layer is the arrangement of the light transmission part 132 and the light absorption part 133 of the light control layer 13 when viewed from the normal direction (Z direction) of the screen surface. It is orthogonal to the direction.
By setting it as such a form, the light ray control effect | action in a screen up-down direction (Y direction) and a screen left-right direction (X direction) can be exhibited, and effects, such as a reduction of stray light and a contrast improvement, can be show | played.

(5) The reflective screen 10 may include a coloring layer (not shown) that is adjusted by coloring to a predetermined transmittance on the image source side (Z2 side) from the unit prism 112. This colored layer is a layer containing a colorant such as black or gray-colored pigments or dyes, and can reduce the black luminance to improve the contrast or adjust the color tone.

(6) For example, the reflective screen 10 may not be provided with a support plate, and may be bonded to a wall surface or the like via an adhesive layer or the like, or may be fixed to the wall surface with the support plate bonded to the back surface. Further, it may be configured to be suspended from the wall surface by a support member such as a hook.
Further, the reflective screen 10 may be in a form that can be wound and stored when not in use. In the case of such a form, a support plate or the like is not provided, and the back side of the reflective screen 10 is covered with a cloth or resin light-shielding curtain that hardly transmits light, a layer that improves scratch resistance, or the like. Also good.

(7) In the above-described embodiment and other examples, the light transmitting portion 132 and the light absorbing portion 133 are examples in which the cross-sectional shape in a cross section parallel to the arrangement direction and the thickness direction is formed in a wedge shape or a rectangular shape. However, the present invention is not limited to this, and it may be formed in a parallelogram shape or a square shape.
In the above-described embodiment and other examples, the interface 134 between the light transmission part 132 and the light absorption part 133 is formed in a planar shape. However, the present invention is not limited to this example. You may make it form in a shape.

  In addition, although embodiment and a deformation | transformation form can also be used in combination as appropriate, detailed description is abbreviate | omitted. Further, the present invention is not limited by the above-described embodiments and the like.

DESCRIPTION OF SYMBOLS 1 Image display system 10 Reflective screen 11 Prism layer 111 Prism base material part 112 Unit prism 12 Air layer 13,23,33 Light control layer 131,231,331 Light control base material part 132,232,332 Light transmission part 133 233,333 Light absorption part 14 Light absorption layer 15 Surface layer LS Image source

Claims (5)

A reflective screen that reflects image light projected from an image source and displays the image in an observable manner;
An optical shape layer in which a plurality of unit optical shapes that are convex on the back side are arranged along a plane parallel to the screen surface;
Provided on the back side of the optical shape layer in the thickness direction of the reflective screen, forms an interface with at least a part of the back side surface of the unit optical shape, has a lower refractive index than the unit optical shape, and transmits light A low refractive index layer having
A light absorbing layer that is provided on the back side of the low refractive index layer in the thickness direction of the reflective screen and absorbs light;
An arrangement of the unit optical shapes arranged along the screen surface, wherein a light transmitting portion that transmits light and a light absorbing portion that absorbs light are provided on the image source side with respect to the optical shape layer in the thickness direction of the reflective screen. Light control layers arranged alternately in a direction parallel to the direction;
Providing
Reflective type screen. The reflective screen according to claim 1,
The unit optical shape is a substantially triangular prism shape, the horizontal direction of the screen in the usage state of the reflective screen is the longitudinal direction, and is arranged in the vertical direction of the screen,
Reflective type screen. The reflective screen according to claim 1 or 2,
The light absorbing portion has a substantially wedge-shaped cross section in a cross section parallel to the arrangement direction and the direction orthogonal to the screen surface;
Reflective type screen. The reflective screen according to any one of claims 1 to 3, wherein
The unit optical shape has a substantially triangular shape in a cross-section in a cross-section perpendicular to the screen surface and parallel to the arrangement direction, and the apex angle is 77 to 131 °.
Reflective type screen. The reflective screen according to any one of claims 1 to 4,
An image source for projecting image light onto the reflective screen;
A video display system comprising:

Images