JP2012226103A - Reflection screen and image display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection screen capable of displaying a bright and fine image with high contrast even under a bright room environment, and an image display system equipped with the reflection screen of such a high quality.SOLUTION: A reflection screen 10 includes a lens layer 11; a reflection layer 12 formed on lens surfaces 111a of unit lenses 111; and an optical control layer 14 disposed between an image source and the lens layer 11, and in which the magnitude of a diffusion action to light made incident at an incident angle within a specified angle range including a direction orthogonal to a screen surface of the reflection screen is larger than a diffusion action to light made incident from other angles, in a direction parallel with an arranging direction of the unit lenses 111. In the optical control layer 14, projecting portions 141 and recessed portions 142 having substantially rectangular cross sections are alternately arranged in the direction parallel with the arranging direction of the unit lenses 111, and minute recessed and projecting shapes for diffusing light are formed on top surfaces 141a of the projecting portions 141 and surfaces 142a of the recessed portions 142.

Description

  The present invention relates to a reflection screen and a video display system including the reflection screen.

In recent years, as a video source for projecting an image on a reflective screen, a short focus type image projection device (projector) that realizes a large screen display by projection from a close range has been widely used. Such a short focal point type image projection apparatus can project on the reflection screen from above or below at a larger incident angle than a conventional image source, and saves space in an image display system using the reflection screen. Etc.
In order to satisfactorily display the image light projected by such a short focus type image projection device, a lens layer having a linear Fresnel lens shape or a circular Fresnel lens shape formed by arranging a plurality of unit lenses. Various reflective screens having a reflective layer formed on the surface have been developed (for example, Patent Documents 1 and 2).
Further, as a video display system using a reflective screen, there is an increasing demand for a video display system capable of displaying a video with good contrast and the like even in a bright room environment.

JP-A-8-29875 JP 2008-76522 A

Some reflective screens using the lens layer as described above include a light diffusion layer that diffuses light closer to the image source than the lens layer for the purpose of obtaining a suitable viewing angle.
However, part of the image light incident on the reflection screen is diffused by the light diffusion layer and cannot reach the reflection layer at an appropriate angle. As a result, the amount of image light reaching the observer side, which is substantially in the front direction of the reflective screen, is reduced, the use efficiency of the image light is greatly reduced, and there is a problem that the brightness of the image is lowered or blurred. is there.
In addition, unnecessary external light such as illumination light incident on the reflection screen is also diffused by the light diffusion layer, so that it reaches the observer and causes a reduction in the contrast of the image.
The above-mentioned Patent Documents 1 and 2 do not disclose any measures for preventing such a decrease in the use efficiency of image light.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a reflective screen capable of displaying a bright and high-contrast good image even in a bright room environment, such a high-quality reflective screen, and an image display system including the reflective 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 reflection screen that reflects image light projected from an image source and displays the image light so as to be observable, and a unit lens (111) having a lens surface (111a) and a non-lens surface (111b). A lens layer (11) having a Fresnel lens shape arranged on the back side along the screen surface of the reflection screen, and a reflection layer (12, 12) formed on at least the lens surface of the unit lens and reflecting light. 32), and is incident on an image source side with respect to the lens layer and is incident at an incident angle in a specific angle range including a direction perpendicular to the screen surface of the reflecting screen in a direction parallel to the arrangement direction of the unit lenses. A light control layer (14) having a large diffusion effect on light compared to the diffusion effect on light incident from other angles, the light control layer comprising: On the image source side, a convex portion (141) convex toward the image source side and a concave portion (142) located closer to the lens layer than the convex portion are parallel to the arrangement direction of the unit lenses along the screen surface. The projections are arranged alternately in the direction, and the projections have a substantially quadrangular cross-section in a cross section that is parallel to the arrangement direction and orthogonal to the screen surface, and the top surface (141a on the image source side of the projections). ) And the surface of the concave portion (142a) is formed with a fine uneven shape for diffusing light, which is a reflective screen (10, 20, 30).
According to a second aspect of the present invention, in the reflective screen according to the first aspect, the arrangement pitch of the convex portions (141) is P, and from the surface (142a) of the concave portion (142) to the top surface (141a) of the convex portion. The reflective screen (10, 20, 30) is characterized by satisfying a relationship of 0.12 ≦ H / P ≦ 0.2, where H is the dimension of.
According to a third aspect of the present invention, there is provided the reflective screen according to the first or second aspect, wherein the top surface (141a) of the convex portion (141) and the surface of the concave portion (142) have a fine concavo-convex shape. Reflective screen (10, 20, 30) characterized in that arithmetic average roughness Ra (JIS B0601-2001) as roughness is preferably 0.3 μm or more, and more preferably 0.5 μm or more. It is.
According to a fourth aspect of the present invention, in the reflective screen according to any one of the first to third aspects, the convex portions (141) are in a cross section that is parallel to the arrangement direction and orthogonal to the screen surface. The reflecting screen (10, 20, 30) is characterized in that the cross-sectional shape is a substantially rectangular shape.

According to a fifth aspect of the present invention, in the reflective screen according to any one of the first to fourth aspects, the unit is disposed on the image source (LS) side of the lens layer (11) and within the screen surface. Reflection characterized by comprising an anisotropic light diffusion layer (25) that has a larger diffusion effect in a direction perpendicular to the arrangement direction of the unit lenses than a diffusion action in a direction parallel to the arrangement direction of the lenses (111). Screen (20).
A sixth aspect of the present invention is the reflective screen according to any one of the first to fifth aspects, wherein the arrangement direction of the unit lenses (111) and the convex portions (141) is the screen of the reflective screen. It is a reflective screen (10, 20, 30) characterized by being in the vertical direction.
The invention according to claim 7 is the reflection screen according to any one of claims 1 to 6, wherein the unit lens (111) absorbs light on the non-lens surface (111b). A reflective screen (30) characterized in that a layer (36) is formed.

The invention of claim 8 is the reflection screen (10, 20, 30) according to any one of claims 1 to 7, and an image source (LS) for projecting image light to the reflection screen. And a video display system (1).
The invention of claim 9 is the video display system according to claim 8, wherein the video source (LS) is a short focus projector.

According to the present invention, the following effects can be obtained.
(1) The reflection screen according to the present invention has a large diffusion effect on light incident at an incident angle in a specific angle range including a direction orthogonal to the screen surface of the reflection screen in a direction parallel to the arrangement direction of the unit lenses. The light control layer includes a light control layer that is larger than the diffusion action for light incident from other angles, and the light control layer includes a convex portion that is convex on the image source side and a lens layer that is more convex than the convex portion. The concave portions located on the side are alternately arranged in a direction parallel to the arrangement direction of the unit lenses along the screen surface, and the convex portions are cross-sectional shapes in a cross section that is parallel to the arrangement direction and orthogonal to the screen surface. Is a substantially quadrangular shape, and a fine concavo-convex shape for diffusing light is formed on the top surface of the convex portion on the image source side and the surface of the concave portion.
Therefore, image light projected obliquely from below or the like to the reflection screen can reach the reflection layer without being diffused and be reflected, and can be reliably diffused when emitted from the light control layer in a substantially front direction. it can. Therefore, the image light can be reflected efficiently, and a bright and clear image with a wide viewing angle can be displayed.
In addition, external light incident on the reflection screen obliquely from above reaches the reflection layer without being diffused and is reflected and hardly diffuses when it is emitted from the light control layer to the lower side of the reflection screen. I do not receive it. Therefore, the external light reaching the front direction of the reflection screen on the viewer side can be greatly reduced, the reduction of contrast due to the external light can be improved, and an image with high contrast can be displayed.
Such an effect is particularly high when using a short-focus image source that projects image light from the lower side or the upper side in the vertical direction of the screen at a larger incident angle than a general projection system. .

(2) When the arrangement pitch of the convex portions is P and the dimension from the surface of the concave portion to the top surface of the convex portion is H, the relationship 0.12 ≦ H / P ≦ 0.2 is satisfied, so that bright and uneven brightness is obtained. It is possible to display a clear and high contrast image.

(3) The arithmetic average roughness Ra (JIS B0601-2001), which is the surface roughness of the fine irregularities on the top surface of the convex part and the surface of the concave part, is preferably 0.3 μm or more, more preferably 0.5 μm. As described above, video light can be diffused and widened, and a good viewing angle can be obtained.

(4) Since the convex portion has a substantially rectangular cross section in a cross section that is parallel to the arrangement direction and orthogonal to the screen surface, the sheet surface (when viewed as the entire light control layer) with respect to the light control layer It is possible to reliably diffuse 100% of light incident from the normal direction with respect to the plane direction of the reflection screen and a plane parallel to the screen surface of the reflection screen. In addition, since the cross-sectional shape of the convex portion is a substantially rectangular shape, the light control layer (convex portion) can be easily released from the mold during molding, and manufacturing can be performed easily.

(5) The reflecting screen has a diffusing action in a direction perpendicular to the arrangement direction of the unit lenses, compared to a diffusing action in the direction parallel to the arrangement direction of the unit lenses in the screen surface on the image source side from the lens layer. Has a large anisotropic light diffusion layer. Therefore, it is possible to give the image light a diffusing action in a direction orthogonal to the arrangement direction of the unit lenses, and a good viewing angle can be obtained.

(6) Since the arrangement direction of the unit lenses and the convex portions is the screen vertical direction of the reflection screen, the image light is projected from the lower side or the upper side of the reflection screen in the vertical direction of the screen and reflected substantially in the front direction. it can. In addition, it is possible to efficiently reflect outside light that is mainly incident from above the reflection screen to the lower side.

(7) Since the light absorption layer which absorbs light is formed on the non-lens surface, the unit lens can absorb external light and improve the contrast.

(8) Since the video display system includes the reflective screen according to the present invention and the video source that projects video light onto the reflective screen, a bright, clear and high-contrast video can be displayed.

(9) Since the video source is a short focus projector, the space of the video display system can be saved. Further, a large screen display can be realized with a short projection distance.

It is a figure which shows the video display system 1 using the reflective screen 10 of 1st Embodiment. It is a figure which shows the layer structure of the reflective screen 10 of 1st Embodiment. FIG. 4 is a diagram illustrating the shape of a light control layer 14. It is a figure which shows the mode of the angle range of the spreading | diffusion and transmission in the screen up-down direction of the light which injects into the reflective screen. 6 is a graph showing a relationship between an incident angle for each ratio H / P and a ratio of light (non-diffused transmitted light) that is transmitted without being diffused in a certain light beam incident on the light control layer 14. It is a figure explaining the reflective screens 20 and 30 of 2nd and 3rd embodiment.

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. Therefore, the incident angle of each light beam may differ from the actual angle.
In addition, the terms “plate”, “sheet”, “film” and the like are used, but these are generally used in the order of thickness, “plate”, “sheet”, “film”. I am using it. However, there is no technical meaning for such proper use, so the terms of sheets, plates, and films can be replaced as appropriate. For example, the optical sheet may be an optical film or an optical plate.
Furthermore, numerical values such as dimensions and material names of each member 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.

(First embodiment)
FIG. 1 is a diagram illustrating an image display system 1 using a reflective screen 10 according to the first embodiment.
The video display system 1 includes a reflective screen 10, a video source LS, and the like. In the present embodiment, a general video display system in which the reflective screen 10 reflects video light projected from the video source LS and displays the video on the screen will be described. 1 may be, for example, a front projection television system that projects image light from the image source LS, a position detection unit that detects the positions of the reflection screen 10, the image source LS, and the reflection screen on the observation screen, a personal computer, and the like. It is good also as an interactive board system provided with.
The video source LS is a video projection device that projects the video light L onto a reflective screen, and a general-purpose projector or the like can be used. As shown in FIG. 1B, the video source LS is a short focus general-purpose projector that projects the video light L from the lower side of the screen center of the screen when the reflective screen 10 is used.

The reflection screen 10 reflects the image light L projected by the image source LS toward the observer O and displays an image. In the state of use, the observation screen of the reflection screen 10 has a flat shape, and when viewed from the observer O side, the observation screen has a substantially rectangular shape with the long side direction being the horizontal direction of the screen. In the following description, the screen up and down direction and the screen left and right direction are the screen up and down direction (vertical direction) and the screen left and right direction (horizontal direction) when the reflective screen 10 is used, unless otherwise specified. To do.
The reflective screen 10 is provided with a flat support plate 50 on the back side of the reflective layer 12 via a bonding layer (not shown) made of an adhesive material or the like. Is maintained. The support plate 50 of this embodiment does not have light transmittance.

FIG. 2 is a diagram illustrating a layer configuration of the reflective screen 10 according to the first embodiment.
In FIG. 2A, a part of a cross section in a cross section orthogonal to the screen surface of the reflective screen 10 and parallel to the vertical direction of the screen in the use state is shown enlarged. 2 (b) and 2 (c), the unit lens 121 of the cross section in FIG. 2 (a) is further enlarged, but in FIG. 2, the support plate 50 and the like are shown for ease of understanding. Are omitted as appropriate.
The reflective screen 10 includes a light control layer 14, a base material layer 13, a lens layer 11, a reflective layer 12, and the like in order from the image source LS side (observation surface side). Here, the screen surface indicates a surface in the reflective screen 10 which is a planar direction of the reflective screen 10 when viewed as the whole screen, and also in the present specification and claims. They are used as the same definition. The screen surface of the reflection screen 10 is parallel to the observation screen of the reflection screen 10.
For example, the reflective screen 10 of the present embodiment can have a diagonal screen size of 80 inches (1220 × 1620 mm).

The base material layer 13 is a transparent or translucent sheet-like member that becomes the base material of the reflective screen 10. The light control layer 14 is integrally formed on the image source side (observation surface side) of the base material layer 13, and the lens layer 11 is integrally formed on the back surface side (back surface side).
Examples of the base material layer 13 include PET (polyethylene terephthalate) resin having a thickness of 100 to 200 μm, PC (polycarbonate) resin, MS (methyl methacrylate / styrene) resin, MBS (methyl methacrylate / butadiene / styrene). A resin-made sheet-like member such as a resin, an acrylic resin, or a TAC (triacetyl cellulose) resin can be used. The base material layer 13 of the present embodiment uses a sheet-like member made of PET resin having a thickness of 100 μm.
The base material layer 13 may be colored with a dye or pigment such as gray for obtaining a predetermined transmittance.

The lens layer 11 is a light-transmitting layer provided on the back side of the base material layer 13, and a Fresnel lens shape is formed on the back side (the side opposite to the base material layer 13).
The Fresnel lens shape formed on the lens layer 11 may be a linear Fresnel lens shape in which unit lenses are arranged in one direction, or a circular Fresnel lens shape in which unit lenses are arranged concentrically. The optimum one can be selected and used as appropriate in accordance with the use environment, the optical characteristics of the image source LS, and the like.
In the present embodiment, the lens layer 11 will be described with an example in which a linear Fresnel lens shape is formed. The linear Fresnel lens shape of the lens layer 11 of this embodiment is formed by arranging a plurality of unit lenses 111 in the vertical direction of the screen along the screen surface.

The lens layer 11 is made of an ultraviolet curable resin. The lens layer 11 may be formed of another ionizing radiation curable resin such as an electron beam curable resin.
The lens layer 11 can be produced, for example, by forming the lens layer 11 on the other surface of the base material layer 13 having the light control layer 14 formed on one surface by an ultraviolet molding method or the like. The method for forming the lens layer 11 may be freely selected as appropriate, and is not limited to this.
By forming the lens layer 11 (unit lens 111) by an ultraviolet molding method, it is possible to form the unit lens 111 with finer pitch and higher shape accuracy.

The unit lens 111 has a substantially triangular cross-sectional shape in a cross section parallel to the direction orthogonal to the screen surface (thickness direction of the reflection screen 10) and parallel to the arrangement direction of the unit lenses 111 (the screen vertical direction of the reflection screen 10). It has a shape, and has a vertex t, a lens surface 111a that is a Fresnel lens-shaped lens surface, and a non-lens surface 111b that faces the lens surface 111a across the vertex t. The unit lens 111 of the present embodiment has a substantially triangular prism shape that is convex on the back side, and its longitudinal direction is parallel to the horizontal direction of the screen and is arranged in the vertical direction of the screen.
In the usage state of the reflection screen 10, the unit lens 111 has the lens surface 111a positioned on the upper side in the vertical direction with respect to the non-lens surface 111b with the apex t interposed therebetween. That is, in the vertical direction, the non-lens surface 111b is located on the image source LS side with respect to the vertex t, and the lens surface 111a is located on the opposite side to the image source LS.

In the unit lens 111, as shown in FIG. 2B, the angle formed by the lens surface 111a and the surface parallel to the screen surface is α, and the angle formed by the non-lens surface 111b and the surface parallel to the screen surface is β ( β> α). Further, the arrangement pitch of the unit lenses 111 is P1.
The arrangement pitch P1, the angle α, and the angle β of the unit lenses 111 are the size of the pixel of the video source LS (projector) that projects the video light, and the projection angle of the video light of the video source LS (video light with respect to the screen surface). The incident angle can be appropriately changed.
FIG. 2 shows an example in which the arrangement pitch P1, the angle α, and the angle β of the unit lenses 111 are constant for easy understanding, but in reality, the angle α is an arrangement of the unit lenses 111. It changes within a predetermined angular range along the direction.
As an example, the unit lens 111 of the present embodiment has an arrangement pitch P1 of 100 μm, an angle α that is variable in the range of 6 to 20 ° along the arrangement direction, and an angle β of 90 °. Further, the refractive index of the unit lens 111 (lens layer 11) of the present embodiment is 1.55.

  Note that the angles α and β and the arrangement pitch P1 are, for example, such that the arrangement pitch P1 of the unit lenses 111 is substantially constant, and the angle α decreases as it becomes lower in the vertical direction of the screen (the arrangement direction of the unit lenses 121). It is good also as a form. For example, the arrangement pitch P1 may gradually change along the arrangement direction of the unit lenses 111. The shape of the unit lens 111 may be appropriately selected according to the use environment, desired optical performance, and the like.

The reflective layer 12 has a function of reflecting light, and is a layer formed on at least the lens surface 111a.
The reflective layer 12 is formed of a silver-based paint, an ultraviolet curable resin containing a silver-based pigment or beads, a metal vapor-deposited film such as silver or aluminum, a metal foil, or the like. The reflective layer 12 has a reflectance of preferably 40% or more, and more preferably 70% or more, in order to display a bright image.
The reflective layer 12 of the present embodiment fills the valleys between the unit lenses 111 and covers the lens surface 111a and the non-lens surface 111b, and is formed of an ultraviolet curable resin containing a silver pigment. ing. However, the present invention is not limited to this, and it may be formed with a predetermined thickness along an uneven shape composed of the lens surface 111a and the non-lens surface 111b.
As described above, since the lens surface 111a and the non-lens surface 111b of the unit lens 111 are covered with the reflection layer 12, light incident on the lens surface 111a and the non-lens surface 111b is reflected by the reflection layer 12.

Since the lens layer 11 has the Fresnel lens shape as described above, as shown in FIG. 2C, the image light is projected from the image source LS and incident from below the reflection screen 10 in the vertical direction of the screen. L1 passes through the light control layer 14 and the base material layer 13, enters the unit lens 111 of the lens layer 11, enters the lens surface 111a, is reflected by the reflecting layer 12, and is reflected on the reflecting screen 10 as an observable light beam. Heading in the normal direction (substantially front direction) of the observation screen.
The external light G1 is incident mainly from above the reflection screen 10 in the vertical direction of the screen, is incident on the lens surface 111a of the unit lens 111, is reflected by the reflection layer 12, and travels below the reflection screen 10. It hardly reaches the observer O in the substantially normal direction (substantially front direction) of the observation screen of the screen 10.
Therefore, according to the reflective screen 10, the image light can be efficiently reflected toward the observer O, and the external light can be directed in a direction in which the observer O does not visually recognize the image.

The light control layer 14 is disposed on the image source LS side with respect to the lens layer 11, and is a direction orthogonal to the screen surface of the reflection screen 10 in a direction parallel to the arrangement direction of the unit lenses 111 (the screen vertical direction of the reflection screen 10). This is a layer having a function that the magnitude of the diffusing action for light incident at an incident angle in a specific angle range including is larger than the diffusing action for light incident from other angles.
FIG. 3 is a diagram illustrating the light control layer 14. 3A to 3C show a part of the image source side surface of the light control layer 14 in a cross section orthogonal to the screen surface of the reflection screen 10 and parallel to the vertical direction of the screen. FIG. 3D schematically shows an incident angle range and an output angle range in which the magnitude of the diffusion action of the light control layer 14 is different.
As shown in FIG. 3A, the light control layer 14 is alternately arranged in the direction parallel to the arrangement direction of the unit lenses 111 (the vertical direction of the reflection screen 10) along the screen surface on the image source LS side. It has a concavo-convex shape in which convex portions 141 and concave portions 142 are arranged.
The light control layer 14 is formed of an ultraviolet curable resin, but is not limited thereto, and may be formed of another ionizing radiation curable resin such as an electron beam curable resin.

The convex portion 141 has a shape that protrudes toward the video source LS, and has a substantially rectangular cross-sectional shape in a cross section that is parallel to the arrangement direction (the vertical direction of the screen) and orthogonal to the screen surface. The convex portions 141 have a substantially rectangular column shape, and the longitudinal direction thereof is the left-right direction of the screen, and a plurality of the convex portions 141 are arranged at predetermined intervals in the vertical direction of the screen.
The convex portion 141 includes a top surface 141a that is a surface on the image source LS side, and side surfaces 141b and 141c that face each other with the top surface 141a interposed therebetween. In the present embodiment, the top surface 141a is substantially parallel to the screen surface, and the side surfaces 141b and 141c are orthogonal to the screen surface.
The concave portions 142 are provided alternately with the convex portions 141 in the vertical direction of the screen along the screen surface, and the surface 142 a is a portion that is closer to the lens layer 11 (back side) than the convex portions 141. In this embodiment, the surface 142a of the recess 142 is substantially parallel to the screen surface.

The top surface 141a of the convex portion 141 and the surface 142a of the concave portion 142 have fine irregularities formed on the surfaces thereof, and have light diffusibility to diffuse light. From the viewpoint of exhibiting light diffusibility, the fine uneven shape preferably has an arithmetic average roughness Ra (JIS B0601-2001) of 0.3 μm or more, 0.5 μm or more. More preferably.
The fine concavo-convex shape forms a fine concavo-convex shape in a portion corresponding to the top surface 141a and the surface 142a of the mold for shaping the shape of the convex portion 141 and the concave portion 142, and the shape of the convex portion 141 and the concave portion 142 is formed. It may be formed by transferring at the time of molding, or after forming the shape of the planar convex portion 141 and the concave portion 142, a binder containing a diffusing agent is coated on the top surface 141a of the convex portion 141 or the surface 142a of the concave portion 142. The surface 142a of the concave portion 142 may be formed with a fine concavo-convex shape by transfer as described above, and the top surface 141a of the convex portion 141 may be formed with a fine concavo-convex shape by coating or the like as described above. May be. The top surface 141a of the convex portion 141 and the surface 142a of the concave portion 142 may have different surface roughness, and the formation method may be different.

  In the present embodiment, the top surface 141a of the convex portion 141 and the surface 142a of the concave portion 142 have substantially the same arithmetic average roughness Ra, and Ra = 0.8 μm. In addition, the fine uneven shape of the top surface 141a of the convex portion 141 and the surface 142a of the concave portion 142 of the present embodiment is a portion corresponding to the top surface 141a and the surface 142a of the mold for shaping the convex portion 141 and the concave portion 142. The fine concavo-convex shape for shaping the fine concavo-convex shape is formed, and the fine concavo-convex shape is transferred when the convex portions 141 and the concave portions 142 are formed.

The arrangement pitch of the convex portions 141 of the light control layer 14 in the vertical direction of the screen is P, and the surface of the concave portion 142 from the top surface 141a of the convex portion 141 in the thickness direction of the reflective screen 10 (the direction perpendicular to the screen surface). The dimension up to 142a (the height of the convex portion 141) is H, the width of the convex portion 141 in the vertical direction of the screen is W1, and the width of the concave portion 142 is W2 (P = W1 + W2).
In the present embodiment, the arrangement pitch P of the convex portions 141 is 100 μm, the height H of the convex portions 141 is 20 μm, the width W1 of the convex portions 141 and the width W2 of the concave portions 142 are equal, and W1 = W2 = 50 μm.
In this embodiment, the ratio of the arrangement pitch P to the height H is H / P = 0.2. The ratio H / P is preferably 0.12 ≦ H / P ≦ 0.2 from the viewpoint of displaying a bright and clear image with high contrast.

Since the light control layer 14 has such convex portions 141 and concave portions 142, the light control layer 14 has a large diffusion effect on light incident at an incident angle in a specific angle range including a direction orthogonal to the screen surface of the reflective screen 10. It has a function of being larger than the diffusing action for light incident from other angles.
As shown in FIG. 3D, in the vertical direction of the screen (the arrangement direction of the convex portions 141 and the concave portions 142), the light enters the light control layer 14 at an incident angle within an angular range R2, R4 including the normal direction of the screen surface. It exerts a diffusing action on the light that it does. However, light incident at an incident angle within the angular ranges R1, R3, R5, and R6 other than the above-described angular ranges is allowed to pass straight without exhibiting a diffusing action, or to diffuse even if diffused. The size is small. Note that a straight line S shown in FIG. 3D is a straight line orthogonal to the screen surface.

For this reason, light incident at an incident angle within the angle range R1, R3, R5, R6 in the vertical direction of the screen (arrangement direction of the convex portion 141) is partly from the top surface 141a of the convex portion 141 or the surface 142a of the concave portion 142. Although incident and diffused, a part of the other light enters or exits from the side surfaces 141b and 141c with respect to the convex portion 141, as indicated by light A1 to A3 in FIG. Since the side surfaces 141b and 141c are planes that do not have a fine uneven shape or the like, the light A1, A2, and A3 pass through the light control layer 14 without being diffused and travel to the base material layer 13. The light is emitted from the reflection screen 10.
On the other hand, as shown in FIG. 3C, the light beams A4 and A5 incident at an incident angle within the angle ranges R2 and R4 are the top surface 141a of the convex portion 141 in the vertical direction of the screen (the arrangement direction of the convex portions 141). Alternatively, since the light passes through the surface 142a of the recess 142, it is diffused.
The angle ranges R1 to R6 are determined by the ratio H / P between the arrangement pitch P of the convex portions 141 and the height H. The angle range R1 is equal to the angle range R6, the angle range R2 is equal to the angle range R4, and the angle range R3 is equal to the angle range R5.

FIG. 4 is a diagram illustrating a state of an angle range of diffusion and transmission of light incident on the reflection screen 10 in the vertical direction of the screen.
As described above, the reflective screen 10 of this embodiment includes the light control layer 14. Video light L2 projected from below the reflective screen 10 by the video source LS is incident on the reflective screen 10 at an incident angle within the range of the angular range R3, reflected by the reflective layer 12, and in an angular range R2 that is substantially in the front direction. It emits within the range. At this time, the image light L <b> 2 does not receive the diffusion action of the light control layer 14 or is received only slightly when entering the reflection screen 10. However, at the time of emission, the image light L2 is subjected to the diffusion action of the light control layer 14, and most of it is diffused.
Therefore, since the image light reaches the reflection layer 12 (lens surface 111a) with almost no diffusion, the image light is efficiently reflected toward the observer O, and a bright and clear image can be displayed. Further, since the image light is diffused after being reflected by the reflection layer 12, the viewing angle can be widened and the surface uniformity of brightness can be improved.

On the other hand, unnecessary external light G2 such as illumination light is incident on the reflection screen 10 mainly from above the reflection screen 10 at an incident angle within the range of the angle range R1, reflected by the reflection layer 12 on the lens surface 111a, and reflected. The light is emitted within a range of an angle range R3 on the lower side of the screen 10. At this time, the external light G <b> 2 does not receive the diffusion action of the light control layer 14 or is received only slightly when entering the reflection screen 10. Further, even when the light is emitted, the external light G2 is not affected by the diffusion action of the light control layer 14 or little.
Accordingly, the external light is reflected by the reflection layer 12 (lens surface 111a) with almost no diffusion and is emitted to the lower side of the reflection screen 10 with almost no diffusion, so that it does not reach the observer O side. Alternatively, external light reaching the observer O side can be reduced as much as possible. Accordingly, it is possible to more effectively prevent contrast reduction due to external light.

Here, the reason why 0.12 ≦ H / P ≦ 0.2 is preferable regarding the relationship between the arrangement pitch P and the height H of the convex portions 141 will be described.
FIG. 5 is a graph showing the relationship between the incident angle for each ratio H / P and the ratio of light (non-diffused transmitted light) that is transmitted without being diffused in a certain light flux incident on the light control layer 14.
The vertical axis shown in FIG. 5 is the ratio of light that is transmitted without being diffused (non-diffused transmitted light) out of the light flux incident on the light control layer 14, and the horizontal axis is the incident angle (incident angle with respect to the screen surface). It is.
The ratio of non-diffuse transmitted light is light that is not subjected to the diffusing action by the top surface 141a of the convex portion 141 or the surface 142a of the concave portion 142 in a light beam incident on the light control layer 14 at a certain incident angle (incident angle with respect to the screen surface). Means the percentage of When the image source LS projects an image from below the reflection screen 10 as in the present embodiment, the ratio of non-diffuse transmitted light is, for example, incident from the side surface 141b of the convex portion 141 and the light control layer 14 is This is the ratio of light that is transmitted and incident on the base material layer 13 without being incident on the top surface 141a of the convex portion 141 or the surface 142a of the concave portion 142.
A graph showing the relationship between this ratio H / P and the ratio of non-diffuse transmitted light is calculated. In FIG. 5, for the ratio H / P = 0.1, the ratio H / P = 0.15, and the ratio H / P = 0.2, the non-diffuse transmitted light every 2 ° within the range of the incident angle of 30-80 °. The percentage of was calculated. At this time, the calculation is performed assuming that the width W1 = W2 and W1 = W2 = P / 2.

As shown in FIG. 5, while the incident angle is small, the ratio of non-diffuse transmitted light is larger when the ratio H / P is larger. The ratio of the non-diffuse transmitted light increases as the incident angle with respect to the screen surface increases regardless of the ratio H / P, and peaks at a predetermined incident angle for each ratio H / P, and decreases beyond that. is doing. The incident angle at which the ratio of the non-diffuse transmitted light reaches a peak tends to decrease as the ratio H / P increases.
Here, at the ratio H / P = 0.2, the ratio of the non-diffuse transmitted light starts to decrease with an incident angle of about 68 ° as a peak, and then starts increasing again at an incident angle of 78 °. In the case of having such an inflection point that starts to increase again, a variation in luminance occurs on the screen screen, which is observed as luminance unevenness, and the surface uniformity of brightness decreases.
Therefore, the ratio H / P is preferably H / P ≦ 0.2 from the viewpoint of reducing luminance unevenness. Note that, at the ratio H / P = 0.2, the inflection point is present as described above. However, the reflection screen corresponding to the commonly used short focus type image source has the maximum incident angle. Even if it has an inflection point in the vicinity of 78 °, the influence on luminance unevenness is small and it can be used satisfactorily.

Table 1 shows the ratio H / P according to the ratio H / P when the light quantity of non-diffuse transmitted light in the whole light incident at an incident angle of 30 to 80 ° is set as a reference (100%) when the ratio H / P = 0.2. It is a table | surface which shows the ratio of the light quantity of non-diffusive transmitted light.
That is, the non-diffused transmission light curve for each H / P when the ratio curve of non-diffused transmitted light at the ratio H / P = 2.0 shown in FIG. 5 is integrated and the integrated value is used as a reference (100%). This corresponds to the ratio of the integral value of the light ratio curve.
As shown in Table 1, as the ratio H / P increases, the amount of non-diffused light in the entire light incident at an incident angle of 30 to 80 ° increases.
The ratio H / P = 0.11 is 77%, but the ratio H / P = 0.12 is 82%. It is clear that the ratio of the amount of non-diffuse transmitted light in the entire light incident at an incident angle of 30 to 80 ° is 80% or more when the ratio H / P = 0.2 is set as a reference (100%). This is preferable from the viewpoint of displaying an image and preventing contrast reduction due to external light. Therefore, the ratio H / P is preferably H / P ≧ 0.12.
From the above results, the ratio H / P preferably satisfies 0.12 ≦ H / P ≦ 0.2.
The reflective screen 10 of the present embodiment has this ratio H / P = 0.2, which satisfies the preferred range.

(Second and third embodiments)
FIG. 6 is a diagram illustrating the reflection screens 20 and 30 according to the second and third embodiments.
FIG. 6A is a diagram showing a layer configuration of the reflective screen 20 of the second embodiment, and schematically shows a cross section in a direction parallel to the screen vertical direction of the reflective screen 20 and perpendicular to the screen surface. ing.
The reflective screen 20 of the second embodiment is substantially the same as the reflective screen 10 of the first embodiment described above, except that the light diffusing layer 25 is different from the reflective screen 10 of the first embodiment. It is. 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, and redundant description is omitted.
The reflective screen 20 of the second embodiment includes a light diffusing layer 25 between the base material layer 13 and the light control layer 14, and is similar to the reflective screen 10 of the first embodiment described above in the video display system 1. Can be used. The light diffusion layer 25 may be disposed closer to the video source LS than the light control layer 14.

  The light diffusion layer 25 is an anisotropic diffusion layer that has a larger diffusion characteristic in the horizontal direction of the screen than in the vertical direction of the screen. The light diffusion layer 25 is formed by adding a needle-like diffusing agent in a resin such as PET, and the orientation direction of the diffusing agent is the vertical direction of the screen. In addition, even if it is a thing of a form other than this, if it has a desired optical characteristic, you may use it suitably.

  According to this embodiment, since the light diffusion layer 25 is provided, light can be diffused mainly in the horizontal direction, the viewing angle in the horizontal direction can be widened, and the viewing angle can be improved. Further, since the action of diffusing light is small in the vertical direction, the front luminance can be improved as compared with a diffusion layer having an isotropic diffusion action. Therefore, according to the present embodiment, it is possible to widen the viewing angle in the horizontal direction while maintaining high front luminance.

FIG. 6B illustrates the lens layer 11, the reflective layer 32, and the light absorption layer 36 of the reflective screen 30 according to the third embodiment. In FIG. 6B, only the lens layer 11, the reflection layer 32, and the light absorption layer 36 are shown for easy understanding.
The reflective screen 30 of the third embodiment differs from the reflective screen 10 of the first embodiment except that the reflective screen 30 includes a reflective layer 32 and a light absorbing layer 36. It is substantially the same form. 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, and redundant description is omitted.
The reflective screen 30 includes a light control layer 14, a base material layer 13, and a lens layer 11, and further includes a reflective layer 32 and a light absorption layer 36 on the back side of the lens layer 11, and the first embodiment described above. Similar to the reflective screen 10, the image display system 1 can be used.

The reflective layer 32 is formed with a predetermined thickness on the lens surface 111a of the lens layer 11, and is not formed on the non-lens surface 111b.
The light absorption layer 36 has a function of absorbing light, and is formed so as to cover the non-lens surface 111 b of the lens layer 11. The light absorption layer 36 is formed of a dark paint such as black, or a resin containing a dark pigment or dye.
As shown in FIG. 6B, the light absorption layer 36 may be formed so as to fill the valleys between the unit lenses 111 on the back side of the lens layer 11 on which the reflection layer 32 is formed. Further, it may be formed in a predetermined thickness only on the non-lens surface 111b, and can be selected as appropriate according to the manufacturing method, material, and the like.

  According to this embodiment, since the light absorption layer 36 is provided, when a part of external light (external light G3) incident from above the reflection screen 30 enters the non-lens surface 111b, the light absorption layer 36 Absorbed. As a result, a decrease in contrast due to external light can be further suppressed, and the contrast can be improved.

(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, an example in which a linear Fresnel lens shape is formed on the back side of the lens layer 11 of the reflection screens 10, 20, and 30 is shown. However, the present invention is not limited to this. It is good also as a lens layer in which the circular Fresnel lens shape arranged in the shape was formed.

(2) In each embodiment, although the reflective screens 10, 20, and 30 are bonded to the support plate 50 provided on the back side thereof via an adhesive layer or the like, an example of a substantially flat plate shape is shown. For example, it is good also as a form joined to a wall surface via an adhesive material layer etc.
Moreover, in each embodiment, although the reflective screens 10, 20, and 30 showed the example which is substantially flat form in a use condition and a non-use state, it is not restricted to this, The rewinding which can be wound up and stored when not in use is possible. It is good also as a various form. In the case of such a form, the support plate 50 or the like is not provided, and the back side of the reflective screens 10, 20, and 30 is made of a cloth or resin shading curtain that hardly transmits light or a protective layer that improves scratch resistance. It is good also as a form to coat | cover.

(3) In each embodiment, the reflective screens 10, 20, and 30 are, for example, a glass or resin substrate layer for increasing the rigidity of the reflective screen and maintaining flatness, a colored layer for improving contrast, It is good also as a form further equipped with the ultraviolet-ray absorption layer which has an ultraviolet-ray absorption effect | action, a touchscreen layer, etc. You may set suitably about the position which provides these layers.

(4) In each embodiment, the example in which the light control layer 14 is provided on the most image source LS side (observation surface side) of the reflection screens 10, 20, and 30 has been described. A surface functional layer having a hard coat function, an ultraviolet absorption function, an antiglare function, an antistatic function, an antifouling function, or the like may be provided on the image source LS side of the layer 14. At this time, when the concavo-convex shape including the convex portion 141 and the concave portion 142 of the light control layer 14 is filled with an adhesive material or the like, it is preferable that there is a refractive index difference between the light control layer 14 and the bonding layer or the like. .

(5) In each embodiment, the convex part 141 showed the example whose cross-sectional shape is a substantially rectangular shape, but it is not restricted to this, For example, the width | variety of the top surface by the side of the image source LS is the reflection layer side. A substantially trapezoidal shape narrower than the width may be used, or a part of the shape may be a curved surface. Furthermore, the cross-sectional shape of the convex portion 141 may be a polygonal shape such as a substantially pentagonal shape or a substantially hexagonal shape.
In each embodiment, the example in which the arrangement pitch and the height H of the convex portions 141 are constant has been shown. The shape of the screens 10, 20, and 30 may be changed as appropriate according to the position on the screen.
Furthermore, the width W1 of the top surface 141a of the convex portion 141 and the width W2 of the surface 142a of the concave portion 142 may both change along the arrangement direction, or may have different values.

(6) In each embodiment, the example in which the main incident direction of the image light is from the lower side of the reflection screen 10 in the usage state of the reflection screens 10, 20, and 30 has been shown. When the main incident direction of light is the upper part of the screen, the reflecting screens 10, 20, and 30 of the embodiment may be turned upside down accordingly.

(7) In each embodiment, the example in which the lens layer 11 is integrally formed on one surface of the base material layer 13 by ultraviolet molding has been described. However, the present invention is not limited to this. For example, the lens layer may be formed by extrusion molding. Good. At this time, if the lens layer 11 has a sufficient thickness, the base material layer 13 may not be provided, or the lens layer 11 and the base material layer 13 may be extruded and molded together. By adopting such a form, mass production is further facilitated and can be provided at low cost.

(8) In each embodiment, although the light control layer 14 demonstrated the example by which the convex part 141 and the recessed part 142 were alternately arranged by the image source LS side, it is not restricted to this, As the light control layer 14 Also, “Lumisty” (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., which is an optical film having a visibility control action, may be used. Since the optical film having the visibility control action does not have a concavo-convex shape such as a convex portion or a concave portion on its surface, a layer having another function can be easily laminated on this layer.

(9) In each embodiment, the video display system 1 including the reflection screens 10, 20, and 30 and the video source LS is shown. However, the present invention is not limited to this. For example, a control unit such as a personal computer or a user It is also possible to provide an interactive board system that includes a position detection device that detects the position of the reflective screen 10 touched on the screen and that can communicate with the control unit such as a personal computer. In such a form, for example, information such as characters and figures drawn by the user on the observation screens of the reflection screens 10, 20, and 30 with a touch pen, fingers, etc. is combined with the projected image, and the figures and characters are displayed. It is possible to display the image as drawn on the projection image, or to convert and store the projection image including the information.
Moreover, the reflective screen 10 draws information, such as a character and a figure, by handwriting on the surface (observation screen) using a predetermined writing instrument such as a marker, such as a general white board, or the like. Or can be deleted. In the case of such a form, providing a layer having a hard coat function, writing property, etc. closer to the image source side than the light control layer 14 prevents damage to the convex portion 141 or the like. This is preferable from the viewpoint of improving the quality of the board system.

  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 to the embodiment described above.

DESCRIPTION OF SYMBOLS 1 Video display system 10,20,30 Reflective screen 11 Lens layer 111 Unit lens 111a Lens surface 111b Non-lens surface 12,32 Reflective layer 13 Base material layer 14 Light control layer 141 Convex part 141a Top surface 142 Concave part 142a Concave surface 25 Light diffusion layer 36 Light absorption layer

Claims (9)

A reflection screen that reflects image light projected from an image source and displays the image light so as to be observable;
A lens layer having a Fresnel lens shape on the back side in which a plurality of unit lenses having a lens surface and a non-lens surface are arranged along the screen surface of the reflective screen;
A reflection layer that is formed on at least the lens surface of the unit lens and reflects light;
A diffusing action for light incident at an incident angle in a specific angle range including a direction orthogonal to the screen surface of the reflective screen in a direction parallel to the arrangement direction of the unit lenses and arranged in the image source side of the lens layer A light control layer whose size is greater than the diffusion effect on light incident from other angles,
With
In the light control layer, a convex portion that is convex toward the image source side and a concave portion that is positioned closer to the lens layer than the convex portion are parallel to the arrangement direction of the unit lenses along the screen surface. Are arranged alternately in different directions,
The convex portion has a substantially quadrangular cross section in a cross section that is parallel to the arrangement direction and orthogonal to the screen surface,
The top surface on the image source side of the convex part and the surface of the concave part are formed with fine concave and convex shapes that diffuse light,
Reflective screen featuring. The reflective screen according to claim 1.
When the arrangement pitch of the protrusions is P, and the dimension from the surface of the recesses to the top surface of the protrusions is H,
0.12 ≦ H / P ≦ 0.2
Satisfying the relationship
Reflective screen featuring. The reflective screen according to claim 1 or 2,
The arithmetic average roughness Ra (JIS B0601-2001), which is the surface roughness of the fine irregularities on the top surface of the convex part and the surface of the concave part, is preferably 0.3 μm or more, more preferably 0.5 μm or more. Being
Reflective screen featuring. The reflective screen according to any one of claims 1 to 3,
The convex portion has a substantially rectangular shape in cross section in a cross section that is parallel to the arrangement direction and orthogonal to the screen surface,
Reflective screen featuring. The reflective screen according to any one of claims 1 to 4, wherein:
Anisotropic light having a larger diffusing action in the direction perpendicular to the arrangement direction of the unit lenses than the diffusing action in the direction parallel to the arrangement direction of the unit lenses in the screen surface on the image source side than the lens layer Providing a diffusion layer;
Reflective screen featuring. The reflection screen according to any one of claims 1 to 5,
The arrangement direction of the unit lenses and the convex portions is the screen vertical direction of the reflective screen,
Reflective screen featuring. The reflective screen according to any one of claims 1 to 6,
The unit lens has a light absorption layer that absorbs light on the non-lens surface,
Reflective screen featuring. A reflective screen according to any one of claims 1 to 7,
An image source for projecting image light to the reflective screen;
A video display system comprising: The video display system according to claim 8, wherein
The video source is a short focus projector;
A video display system characterized by

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