JP6272013B2 - Reflective screen, video display system - Google Patents

Description

  The present invention relates to a reflective screen that reflects projected image light and displays an image, and an image display system including the same.

In recent years, as a video source for projecting an image on a reflective screen, a short focus type image projection device (projector) that projects a video light at a relatively large projection angle from a short distance to realize a large screen display has been widely used. ing. The short focus type image projection apparatus can project image light with respect to the reflection type screen from above or below at a larger incident angle than that of the conventional image source, and the image display system using the reflection type screen can be saved. Contributes to space.
In order to satisfactorily display the image light projected by such a short focus type image projection device, the surface of the lens layer having a linear Fresnel lens shape or a circular Fresnel lens shape formed by arranging a plurality of unit lenses is used. Various reflective screens and the like on which a reflective layer is formed have been developed (for example, Patent Documents 1 and 2).

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

In an image display system that uses an image source that projects image light at a large angle from a close distance to the reflective screen as described above, a portion of the image light is reflected on the reflective screen. May be reflected on the image source side surface and reach the ceiling or the like, and the image may be reflected on the ceiling. Such a reflection of the image on the ceiling has a problem that it hinders comfortable visual recognition of the image.
The above-mentioned Patent Documents 1 and 2 do not take measures for improving the reflection of the image on the ceiling.

  In order to improve the reflection of the image on the ceiling, a reflective screen having a mat shape or a prism shape on the surface on the image source side has been developed. However, such a reflective screen has a problem in that the contrast of the image is reduced, image blurring, bright lines, etc. are generated and the quality of the image is deteriorated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a reflective screen capable of reducing image reflection on the ceiling and display defects such as bright lines and displaying a bright and good image, and an image display system including the same. .

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 according to claim 1 is a reflective screen that reflects the image light projected from the image source and displays the image light so as to be observable, the reflective layer reflecting the image light, and the thickness direction of the reflective screen. A surface optical layer (15), which is positioned on the image source side of the reflective layer and a plurality of unit prisms (151) each having a substantially polygonal prism shape projecting toward the image source side on the surface of the image source side. The height (h2) of the unit prism varies regularly or irregularly in the longitudinal direction of the unit prism, and the unit prism in the longitudinal direction of the unit prism (151) The height (h2) of the unit prism periodically changes in the longitudinal direction. When the period is P, and the difference d between the highest point and the lowest point of the unit prism, the ratio P / d satisfies 14 ≦ P / d ≦ 84 Succoth a reflective screen according to claim (10).
The invention according to claim 2 is a reflective screen that reflects the image light projected from the image source and displays the image light so as to be observable, and a reflective layer (12) that reflects the image light, and a thickness direction of the reflective screen A surface optical layer (15), which is positioned on the image source side of the reflective layer and a plurality of unit prisms (151) each having a substantially polygonal prism shape projecting toward the image source side on the surface of the image source side. The height (h2) of the unit prism varies regularly or irregularly in the longitudinal direction of the unit prism, and the unit prism in the longitudinal direction of the unit prism (151) height (h2) is periodically varied in the longitudinal direction, the period P is 100 [mu] m or more, is 600μm or less, a reflective screen according to claim (10).
According to a third aspect of the present invention, in the reflective screen according to the first or second aspect, the height (h2) of the unit prism (151) is adjacent to the unit on a straight line parallel to the arrangement direction. A reflective screen (10) characterized by being different from the height of a prism.
According to a fourth aspect of the present invention, there is provided a reflective screen according to any one of the first to third aspects, wherein a lens is disposed on the back side of the surface optical layer (15) in the thickness direction of the reflective screen. A lens layer (13) having a Fresnel lens shape on the back side in which a plurality of unit lenses (131) having a surface (132) and a non-lens surface (133) and convex on the back side are arranged; (12) is a reflective screen (10) characterized in that it is formed on at least the lens surface of the unit lens.
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).

  Advantageous Effects of Invention According to the present invention, it is possible to provide a reflective screen capable of reducing image reflection on the ceiling and display defects such as bright lines and displaying a bright and good image, and an image display system including the same. Can play.

It is a figure explaining the video display system 1 of 1st Embodiment. It is a figure explaining the layer structure of the reflection type screen 10 of 1st Embodiment. It is a figure explaining the lens layer 13 of 1st Embodiment. It is a figure explaining the surface optical layer 15 of 1st Embodiment. It is a figure explaining the function of the surface optical layer 15 of the reflection type screen 10 of 1st Embodiment. It is a figure which shows the mode of the light in the image source side surface in the reflection type screens 10B-10D of a comparative example. It is a figure explaining the evaluation method which evaluates the reflection of the image | video on a ceiling. It is a figure explaining the reflection type screen 20 of 2nd 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.
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.

(First embodiment)
FIG. 1 is a diagram illustrating a video display system 1 according to the first 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. This video display system 1 is a general video display system in which video light L projected from a video source LS is reflected by a reflective screen 10 and video is displayed on the screen (display area). The video display system 1 can also be used as a front projection television system or the like.

  The video source LS is a device that projects the video light L onto the reflective screen 10, and a general-purpose short focus projector or the like can be used. The image source LS is the center in the horizontal direction of the screen of the reflective screen 10 when the screen of the reflective screen 10 is viewed from the normal direction (normal direction of the screen surface) in the use state. It is arranged at a position below the 10 screens (display area). The screen surface refers to a surface in the planar direction of the reflective screen when viewed as the entire reflective screen.

  The image source LS receives the image light L from a position where the distance from the reflective screen 10 in a direction orthogonal to the screen of the reflective screen 10 (thickness direction of the reflective screen 10) is much closer than that of a conventional general-purpose projector. Can project. Therefore, the video source LS has a shorter projection distance to the reflective screen 10 and a larger incident angle of the video light L with respect to the reflective screen 10 than a conventional general-purpose projector.

The reflective screen 10 is a screen that displays the image by reflecting the image light L projected by the image source LS toward the viewer O side. In the state of use, the screen (display area) of the reflective screen 10 is assumed to be substantially rectangular with the long side direction being the left-right direction of the screen when viewed from the observer O side.
In the following description, unless otherwise specified, the screen vertical direction, screen horizontal direction, and thickness direction are the screen vertical direction (vertical direction) and screen horizontal direction (horizontal direction) when the reflective screen 10 is used. ) And the thickness direction (depth direction).

The reflective screen 10 is provided with a flat support plate 50 on the back side thereof via a bonding layer (not shown) made of an adhesive material or the like. The support plate 50 maintains its flatness. Yes. However, 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 or the like (not shown) and the flatness thereof is maintained.
The reflective screen 10 has a large screen (display area) such as a diagonal of 80 inches or 100 inches.

FIG. 2 is a diagram illustrating the layer configuration of the reflective screen 10 according to the first embodiment.
In FIG. 2, it passes through the point A (see FIGS. 1A and 1B) which is the geometric center of the screen (display area) of the reflective screen 10, and is parallel to the vertical direction of the screen and is on the screen surface. A part of a cross section orthogonal (parallel to the thickness direction) is shown enlarged.
The reflective screen 10 includes a surface optical layer 15, a base material layer 14, a lens layer 13, a reflective layer 12, a protective layer 11 and the like in order from the image source side (observer side). Hereinafter, each layer will be described.

The base material layer 14 is a sheet-like member serving as a base material for forming the lens layer 13. A surface optical layer 15 is integrally formed on the image source side (observer side) of the base material layer 14, and a lens layer 13 is integrally formed on the back side (back side).
The base material layer 14 includes a light diffusion layer 141 and a colored layer 142. The light diffusion layer 141 and the colored layer 142 are laminated together. In the present embodiment, as illustrated in FIG. 2, an example in which the light diffusion layer 141 is on the back side and the coloring layer 142 is positioned on the image source side is shown, but the present invention is not limited thereto, and the light diffusion layer 141 is the image source. It is good also as a form which is located in the side and the colored layer 142 is located in the back side.

The light diffusion layer 141 is a layer that contains a light transmissive resin as a base material and contains a light diffusing material. This light diffusion layer 141 has an action of diffusing light, and has a function of widening the viewing angle and improving the in-plane uniformity of brightness.
Examples of the resin used as the base material of the light diffusion layer 141 include PET (polyethylene terephthalate) resin, PC (polycarbonate) resin, MS (methyl methacrylate / styrene) resin, MBS (methyl methacrylate / butadiene / styrene) resin, acrylic resin, and the like. Resin, TAC (triacetyl cellulose) resin, PEN (polyethylene naphthalate) resin and the like.
Examples of the diffusing material include an average particle diameter of about 1 to 50 μm, and resin particles such as acrylic resin, epoxy resin, and silicone, and inorganic particles.
Although the thickness of the light diffusing layer 141 depends on the screen size of the reflective screen 10 or the like, the thickness of the light diffusing layer 141 is set to about 100 to 3000 μm. From the viewpoint of obtaining.

The colored layer 142 is a layer colored with a dark-colored coloring material in order to obtain a predetermined transmittance. In the present embodiment, the colored layer 142 is located on the image source side (observer side) of the light diffusion layer 141.
The colored layer 142 has a function of absorbing light, absorbs unnecessary external light such as illumination light incident on the reflective screen 10, and reduces the black luminance of the displayed image. Has the function of improving the contrast.
The base material of the colored layer 142 is formed of PET resin, PC resin, MS resin, MBS resin, acrylic resin, TAC resin, PEN resin, or the like. Examples of the colorant include dark dyes and pigments such as gray and black.
Although the coloring layer 142 depends on the screen size of the reflective screen 10 or the like, the thickness is set to about 30 to 3000 μm and the transmittance is set to about 30 to 80% to obtain sufficient external light absorption. From the viewpoint of the above.
The base material layer 14 of the present embodiment is formed by integrally laminating the light diffusion layer 141 and the colored layer 142 by coextrusion molding.

FIG. 3 is a diagram illustrating the lens layer 13 according to the first embodiment. FIG. 3A shows a state in which the lens layer 13 is observed from the front side on the back side, and the reflection layer 12 and the protective layer 11 are omitted for easy understanding. FIG. 3B shows an enlarged part of the cross section shown in FIG.
The lens layer 13 is a light-transmitting layer provided on the back side of the base material layer 14, and a plurality of unit lenses 131 are arranged concentrically around the point C as shown in FIG. It has a circular Fresnel lens shape on its back side. In the circular Fresnel lens formed by arranging the unit lenses 131, the point C which is the Fresnel center which is the optical center thereof is outside the area of the screen (display area) of the reflective screen 10, and the reflective screen. 10 is located below.

2 and 3B, the unit lens 131 is parallel to the direction orthogonal to the screen surface (thickness direction of the reflective screen 10) and in a cross section parallel to the arrangement direction of the unit lenses 131. The cross-sectional shape is a substantially triangular shape.
The unit lens 131 is convex on the back side, and includes a lens surface 132 and a non-lens surface 133 that faces the lens surface 132.
When the reflective screen 10 is in use, the unit lens 131 has the lens surface 132 positioned above the non-lens surface 133 with respect to the vertex t1 in the vertical direction.

In the unit lens 131, as shown in FIG. 3B, the angle formed between the lens surface 132 and the surface parallel to the screen surface is α, and the angle formed between the non-lens surface 133 and the surface parallel to the screen surface is β (β> α).
The arrangement pitch of the unit lenses 131 is P1, and the lens height of the unit lenses 131 (the dimension from the vertex t1 in the thickness direction of the screen to the point v1 that becomes the valley bottom between the unit lenses 131) is h1.
In order to facilitate understanding, in FIG. 2 and the like, the arrangement pitch P1 and the angles α and β of the unit lenses 131 are shown to be constant in the arrangement direction of the unit lenses 131. However, the unit lenses 131 of the present embodiment actually have a constant arrangement pitch P1, but gradually increase as the angle α increases away from the point C that becomes the Fresnel center in the arrangement direction of the unit lenses 131.

However, the present invention is not limited thereto, and the angle α or the like may be constant, or the arrangement pitch P1 may gradually change along the arrangement direction of the unit lenses 131, and the pixel of the video source LS that projects the video light. It can be appropriately changed according to the size of (pixel), the projection angle of the image source LS (the incident angle of image light on the screen surface of the reflective screen 10), the screen size of the reflective screen 10, the refractive index of each layer, etc. It is.
In this embodiment, the lens layer 13 is described as an example having a circular Fresnel lens shape. However, the unit lens 131 has a triangular prism shape, and a linear shape arranged in the vertical direction of the screen with the screen horizontal direction as the longitudinal direction. It is good also as a form which has a Fresnel lens shape.

The lens layer 13 is formed of an ultraviolet curable resin such as urethane acrylate or epoxy acrylate. The lens layer 13 may be formed of another ionizing radiation curable resin such as an electron beam curable resin.
The lens layer 13 is, for example, a molding die for shaping one surface of the base material layer 14 (in this embodiment, the surface on the light diffusion layer 141 side) into a circular Fresnel lens shape filled with an ultraviolet curable resin. It can be formed by an ultraviolet molding method or the like in which the mold is released from the mold after being pressed and cured by irradiation with ultraviolet rays. The method for forming the lens layer 13 may be selected as appropriate, and is not limited to this.

The reflection layer 12 is a layer having an action of reflecting light. The reflective layer 12 is formed on at least the lens surface 132.
The reflection layer 12 is formed on the lens surface 132 as shown in FIGS. 2 and 3B, but is not formed on the non-lens surface 133.
The reflective layer 12 is formed by evaporating aluminum on the lens surface 132. The reflective layer 12 is not limited to the above, and can be formed on the lens surface 132 by evaporating a metal such as aluminum, silver, or nickel, sputtering, or transferring a metal foil.

The protective layer 11 is a layer provided on the back side of the lens layer 13 and the reflective layer 12. The protective layer 11 has a function of protecting the reflective layer 12 and the lens layer 13 by suppressing deterioration and peeling of the reflective layer 12, damage of the reflective layer 12 and the lens layer 13, and the like. The protective layer 11 has a function of absorbing light.
As shown in FIGS. 2 and 3B, the protective layer 11 covers the reflective layer 12 and the non-lens surface 133 from the back side. Accordingly, the protective layer 11 is formed on the non-lens surface 133. Further, the protective layer 11 sufficiently fills the irregularities of the unit lens 131 of the lens layer 13, and the surface on the back side thereof is substantially flat parallel to the screen surface.
In the thickness direction of the reflective screen 10, the protective layer 11 has a sufficient protective function and a light absorption property when the dimension from the vertex t 1 of the unit lens 131 to the back surface thereof is about 5 to 100 μm. From the viewpoint of sufficiently exhibiting the above.
If the protective layer 11 has a sufficient protection function and light absorption function, the back side surface thereof has an uneven shape, such as being formed with substantially the same thickness along the uneven shape of the unit lens 131. You may do it.

  The protective layer 11 is made of a resin such as urethane resin, epoxy resin or acrylic resin, which is a mixture of these materials, and a dark color paint such as black or a dark color dye such as black as a light absorbing material. A lens having a reflective layer 12 formed of a material to which various additives having functions such as protection of the reflective layer 12 from deterioration such as oxidation are added. It is formed by applying and curing on the back side of the layer 13. The protective layer 11 may be formed using a thermosetting resin or ultraviolet curable resin containing a light absorbing material and various additives, or may be formed of a black paint or the like.

FIG. 4 is a diagram illustrating the surface optical layer 15 of the first embodiment.
4A is a view of the surface optical layer 15 as viewed from the front side of the observer side (image source side), and FIG. 4B is a cross section parallel to the horizontal direction of the screen and the direction orthogonal to the screen surface. It is the figure which expanded the cross section of the surface optical layer 15 in. FIG. 4C is an enlarged view of a cross section of the surface optical layer 15 passing through the vertex t2 of the unit prism 151 and parallel to the longitudinal direction.
The surface optical layer 15 is a layer that is disposed closest to the viewer side in the thickness direction of the reflective screen 10. A plurality of unit prisms 151 are arranged on the surface of the surface optical layer 15 on the image source side.

The unit prisms 151 have a substantially triangular prism shape that protrudes toward the image source side, and are arranged in the vertical direction of the screen with the longitudinal direction being the horizontal direction of the screen, as shown in FIG.
As shown in FIG. 4B, the unit prism 151 includes a first surface 152 that is an upper surface and a second surface that is a lower surface in the vertical direction of the screen when the reflective screen 10 is used. 153. The apex angle of the unit prism 151 is θ1, the angle formed by the first surface 152 and the surface parallel to the screen surface is θ2, and the angle formed by the second surface 153 and the surface parallel to the screen surface is θ3. The arrangement pitch of the unit prisms 151 is P2.
In this embodiment, θ2 = θ3, and the arrangement pitch P2 is equal to the width of the unit prisms 151 in the arrangement direction.
By providing such a unit prism 151, the surface optical layer 15 allows the image light L projected from the image source LS located below to efficiently enter the reflective screen 10 from the second surface 153, Light reflected on the ceiling side can be reduced, and the reflection of images on the ceiling can be suppressed.

Here, when the apex angle θ1 is θ1 = 90 °, the light reflected by the reflective layer 12 and directed toward the front observer in the horizontal direction of the screen is totally reflected by the inclined surfaces 152 and 153 of the unit prism 151. As a result, the phenomenon of moving toward the back side again occurs, so that the image may become dark. Accordingly, the apex angle θ1 is preferably set to an angle other than 90 °.
Further, for example, when the apex angle θ1 is an acute angle (0 ° <θ1 <90 °), reflection of the image light to the ceiling side can be further suppressed, but the front luminance of the image tends to be slightly reduced.
Therefore, in this embodiment, the apex angle θ1 is an obtuse angle (θ1> 90 °). When the apex angle θ1 is an obtuse angle (θ1> 90 °), the front luminance of the image is improved and the reflection of the image light to the ceiling side can be sufficiently suppressed as compared with the case where the apex angle is an acute angle.
The apex angle θ1 may be appropriately selected and designed according to the use environment of the reflective screen 10, the size of the screen, the desired optical performance, and the like.
Further, the arrangement pitch P2 of the unit prisms 151 is preferably smaller than the arrangement pitch P1 of the unit lenses 131 from the viewpoint of reducing moire.

Generally, the surface optical layer having such a unit prism is formed by filling a molding die for shaping the unit prism with a resin and curing the resin. When manufacturing a molding die for shaping the unit prism, there are cases where a chamfered corner of the cutting tool is used because of chipping countermeasures on the cutting tool or problems in manufacturing accuracy of the cutting tool. For this reason, the apex angle of the unit prism formed by the mold made of such a cutting tool is not a perfect sharp corner but a flat or rounded apex. There is a problem that the image light is reflected and diffused at such a top portion and is observed as a bright line (hot line) running in the longitudinal direction of the unit prism, and the quality of the image is deteriorated.
Therefore, the surface optical layer 15 changes the height in the longitudinal direction of the unit prism 151, so that even if the top of the unit prism 151 is flat or rounded, It has the effect of diffusing the factor light and greatly reducing the emission lines.

As shown in FIG. 4C, the height h2 of the unit prism 151 is not constant but regularly changes in the longitudinal direction. The period of change of the height h2 of the unit prism 151 is P, and the difference between the height of the highest point and the height of the lowest point is d.
In the longitudinal direction of the unit prism 151, the period P of the change in the height h2 of the unit prism 151 and the difference d between the height of the highest point and the height of the lowest point of the height h2 are from the viewpoint of preventing bright lines. The ratio P / d preferably satisfies 14 ≦ P / d ≦ 84.
If P / d <14, the diffusing action becomes too strong and the light causing the bright line is diffused and the bright line is reduced, but the external light is also diffused, the contrast is lowered, and the image is blurred. There is a problem.
On the other hand, when P / d> 84, there is a problem that the diffusion effect becomes too weak and bright lines are generated.

  Further, the period P of the change in the height h2 of the unit prism 151 is preferably 100 μm or more and 600 μm or less. This is because when the period P is less than 100 μm, the difference d that satisfies the above-mentioned preferable range of the ratio P / d becomes a fine value, and it is difficult to finely process the mold for forming such a unit prism 151. And the period P is larger than 600 μm, the value of the difference d that satisfies the above-described preferable range of the ratio P / d becomes too large, and it is difficult to perform deep cutting or the like in the mold for forming such unit prism 151. This is based on the fact that the unit prism 151 has a disadvantageous shape.

Here, it is preferable that the unit prism 151 has a height h2 different from that of the adjacent unit prism 151 on a straight line parallel to the arrangement direction from the viewpoint of effectively suppressing the bright line. That is, as shown in FIG. 4B, in the cross section parallel to the arrangement direction of the unit prisms 151 and the thickness direction of the reflective screen, the height h21 of the unit prisms 151-1 is equal to the adjacent unit prisms 151-2. It is preferable to be different from the heights h22 and h23 of 151-3.
Further, the difference d between the height of the highest point h2 and the height of the lowest point of the unit prism 151 may be different for each unit prism 151 as long as it is within the above range. It may be different in the longitudinal direction.
Furthermore, in the present embodiment, the unit prism 151 has an example in which the height is regularly different in the longitudinal direction, but the present invention is not limited to this, and the unit prism 151 may be changed irregularly.

The surface optical layer 15 is integrally formed on the surface of the base material layer 14 with an ionizing radiation curable resin such as an ultraviolet curable resin having a hard coat function. The surface optical layer 15 may be formed of a thermoplastic resin or the like. The surface optical layer 15 may have a laminated structure having a prism layer in which unit prisms 151 are formed of one side of a thermoplastic resin base material with an ultraviolet curable resin or the like.
For example, the surface optical layer 15 is filled with an ultraviolet curable resin in a molding die (not shown) in which a concave shape for shaping the unit prism 151 is formed, and one surface of the base material layer 14 (in this embodiment, colored) The layer 142 side surface) is pressed against the mold and cured by irradiating with ultraviolet rays and then released from the mold.
The method for forming the surface optical layer 15 may be selected as appropriate, and is not limited to this.

The state of the image light L1 and the external lights G1 and G2 incident on the reflective screen 10 of the present embodiment will be described with reference to FIG. For easy understanding, for the image light L1 and the external lights G1 and G2 shown in FIG. 2, the refractive indexes of the surface optical layer 15, the base material layer 14, and the lens layer 13 are equal, and the light diffusion layer 141 and the like are diffused. The operation and the like are omitted.
As shown in FIG. 2, most of the image light L1 projected from the image source LS is incident from below the reflective screen 10, passes through the surface optical layer 15 and the base material layer 14, and is a unit of the lens layer 13. The light enters the lens 131.
Then, the image light L1 enters the lens surface 132, is reflected by the reflective layer 12, and exits from the reflective screen 10 toward the viewer O side. Note that the image light L1 is projected from below the reflective screen 10, and the angle β is larger than the incident angle of the image light L1 at each point in the vertical direction of the screen of the reflective screen 10, so the image light L1 is the non-lens surface 133. The non-lens surface 133 does not affect the reflection of the image light L1.

On the other hand, unnecessary external lights G1 and G2 such as illumination light are mainly incident from above the reflection type screen 10 and transmitted through the surface optical layer 15 and the base material layer 14 as shown in FIG. The light enters the unit lens 131.
A part of the external light G1 enters the non-lens surface 133 and is absorbed by the protective layer 11. Further, a part of the external light G2 is reflected by the lens surface 132 and is mainly directed to the lower side of the reflective screen 10, so that it does not reach the observer O side directly. , Significantly less than the image light L. Therefore, the reflective screen 10 can suppress a decrease in the contrast of the image due to the external lights G1 and G2.

Depending on the shape and the like of the outermost surface (most observer side surface) of the reflective screen 10, some of the image light projected on the reflective screen may be reflected by the surface of the reflective screen. .
FIG. 5 is a diagram illustrating the function of the surface optical layer 15 of the reflective screen 10 according to the first embodiment. FIG. 5A shows a state in which the reflective screen 10 of the present embodiment is viewed from the side surface, and FIG. 5B shows a state in which the reflective screen 10 of the present embodiment is viewed from the upper surface side. .
FIG. 6 is a diagram illustrating a state of light on the image source side surface of the reflective screens 10B to 10D of the comparative example. FIG. 6A shows a state in which the reflective screen 10B of the comparative example is viewed from the side, and FIG. 6B shows a state in which the reflective screen 10C of the comparative example is viewed from the side. FIG. 6C shows a state in which the reflective screen 10D of the comparative example is viewed from the side. In order to facilitate understanding, in FIGS. 5 and 6, the reflective screens 10, 10B, 10C, and 10D are shown in a simplified manner.

The reflective screen 10B of the comparative example is the same as the reflective screen 10 of the present embodiment except that the surface optical layer 15B is not the surface optical layer 15 but the surface on the image source side is a smooth surface. It is a form.
The reflective screen 10C of the comparative example has the same configuration as that of the reflective screen 10 of the present embodiment except that the reflective optical screen 10C includes not the surface optical layer 15 but the surface optical layer 15C having a matte surface on the image source side. It is. The surface optical layer 15 </ b> C is a layer having a fine concavo-convex shape formed on the surface thereof and having an action of diffusing light isotropically.
The reflective screen 10D of the comparative example includes a surface optical layer 15D in which a plurality of unit prisms 151D are arranged. However, the height of the unit prism 151D is constant in the longitudinal direction of the present embodiment. This is the same form as the reflective screen 10.

  In the reflective screen 10B of the comparative example, since the image source side surface is a smooth surface or the like, a part of the image light L31 incident on the upper side of the screen is substantially regular reflected above the reflective screen 10B like the light L32. And reach the ceiling. Such light L32 causes the image to be reflected on the ceiling, and hinders comfortable visual recognition of the image. In particular, when the reflective screen 10B is placed in a dark room environment, when the projected image is a moving image, or when the reflective screen 10B is a large screen, the portion of the image reflected on the ceiling Since the brightness is conspicuous or a blurred moving image is visually recognized on the ceiling, comfortable viewing is greatly hindered when the observer O visually recognizes an image displayed on the reflective screen 10B.

In the reflective screen 10C of the comparative example, a part of the image light L41 incident on the upper side of the screen is diffusely reflected on the surface of the surface optical layer 15C like the light L42. Therefore, in the reflective screen 10C of the comparative example, the amount of reflected light reaching the ceiling is reduced, and the reflection of an image on the ceiling is slightly reduced compared to the reflective screen 10B.
However, in addition to the problem that the transfer of the image to the ceiling is insufficient, depending on the intensity of the mat (diffusion action) on the surface of the surface optical layer 15C, the light L42 diffusely reflected on the surface causes the upper part of the screen, etc. However, there is a problem that the contrast of the image is deteriorated and the image is easily blurred.

In the reflective screen 10D of the comparative example, most of the video light L51 incident on the upper side of the screen is incident on the flat reflective screen that does not have the unit prism 151D with respect to the second surface 153 of the unit prism 151D. It is possible to enter at an incident angle smaller than that in the case. Therefore, most of the image light L51 can be efficiently incident on the reflective screen 10D like the light L52, and the reflection of the image on the ceiling by the reflected light on the ceiling side is similar to that of other comparative examples. This is a significant improvement over the reflective screens 10B and 10C.
However, a part of the light L53 is reflected and diffused at the top of the unit prism 151D having the flat part and the roundness as described above, and becomes a bright line (hot line) extending in the horizontal direction of the screen and the like to the observer O. Observed, resulting in degradation of image quality.

On the other hand, according to the reflective screen 10 of the present embodiment, as shown in FIG. 5A, the image light L21 incident on the upper side of the screen is directed to the second surface 153 of the unit prism 151. The incident light can be incident at a smaller incident angle than that incident on a flat reflective screen that does not have the unit prism 151, and can be efficiently incident on the reflective screen 10 (see light L22). Accordingly, the amount of reflected light on the ceiling side is greatly reduced, and the reflection of the image on the ceiling is improved.
Further, according to the reflection type screen 10 of the present embodiment, as described above, the height h2 of the unit prism 151 changes along the longitudinal direction. Therefore, as shown in FIG. The reflected light is mainly diffused in the horizontal direction of the screen, and the generation of bright lines can be effectively reduced.
Therefore, according to the present embodiment, the image light reflected on the surface of the reflective screen and directed toward the ceiling side can be greatly reduced, the reflection of the image on the ceiling can be improved, and bright lines (hot lines) and the like can be improved. Occurrence can be greatly improved.
Further, according to the present embodiment, it is possible to greatly reduce the blurring of the video and the decrease in contrast, and it is possible to display a good video.

Here, surface optical layers for multiple measurement examples with different surface shapes on the image source side, etc. are prepared, and the reflection of the image on the ceiling, the front luminance, and the presence of bright lines (hot lines) on a reflective screen equipped with this. Etc. were evaluated.
The surface optical layer of Measurement Example 1 has a mat shape having an isotropic diffusion action on the surface on the image source side. That is, the surface optical layer of Measurement Example 1 corresponds to the surface optical layer 15C of the comparative example described above.
The surface optical layers of Measurement Examples 2 to 6 are formed by arranging a plurality of unit prisms on the image source side surface, and the apex angles θ1 = 155 ° and θ2 = θ3 = 12.5 °. The surface optical layers of the measurement examples 2 to 6 are different in the presence or absence of the height change of the ridgeline of the unit prism 151, the change period, and the like.
The surface optical layer of Measurement Example 2 is formed by arranging a plurality of unit prisms on the surface on the image source side, and the height h2 is constant in the longitudinal direction of the unit prisms. That is, the surface optical layer of Measurement Example 2 corresponds to the surface optical layer 15D of the comparative example described above.

In the surface optical layer of Measurement Example 3, the height h2 of the unit prism 151 changes with a period P = 250 μm and a height difference d = 3 μm. Further, P / d = 83.3.
In the surface optical layer of Measurement Example 4, the height h2 of the unit prism 151 changes with a period P = 250 μm and a height difference d = 17 μm. Further, P / d = 14.7.
In the surface optical layer of Measurement Example 5, the height h2 of the unit prism 151 changes with a period P = 250 μm and a height difference d = 2 μm. Further, P / d = 125.
In the surface optical layer of Measurement Example 6, the height h2 of the unit prism 151 changes with a period P = 250 μm and a height difference d = 20 μm. Further, P / d = 12.5.

The reflection of the image on the ceiling was evaluated by the ceiling illuminance.
FIG. 7 is a diagram for explaining an evaluation method for evaluating the reflection of an image on the ceiling.
As shown in FIG. 7, the reflective screen 10A provided with the protective layer 11 to the base material layer 14 was arrange | positioned on the wall surface. The reflective screen 10A has a size of 100 inches (2233 mm × 1260 mm). The dimension D1 from the ceiling to the reflective screen is 400 mm.
The surface optical layer of each measurement example (300 mm × 300 mm, made of PET resin having a thickness of 100 μm) is located at a position 1100 mm from the bottom of the screen in the horizontal direction on the image source side surface of the reflective screen 10A. And a white prism from the image source LS (short focus projector: PDG-DWL2500J manufactured by Sanyo Electric Co., Ltd.). Irradiate. At this time, the projection port of the image light from the image source LS is a distance D3 = 140 mm in the vertical direction from the lower end of the reflective screen 10A, and a distance D4 = 450 mm in the direction perpendicular to the sheet surface (screen surface) of the reflective screen 10A. It is. The incident angle of the image light to the geometric center A2 of the reflective screen 10A is 52 °.

The measured ceiling illuminance is the illuminance of reflected light to the ceiling in the surface optical layer of each measurement example. This ceiling illuminance is on the ceiling surface, in the center in the left-right direction of the reflective screen 10A, and at a distance D2 = 180 mm from the surface of the reflective screen 10A, an illuminometer (digital luminometer T-1 manufactured by Minolta) Was measured by projecting white light from the image source LS in a dark room environment. An illuminance of 95 lx or less was judged as good (◯), and an illuminance greater than 95 lx was judged as impossible (x).
In addition, although the reflected light from the area where the surface optical layer of each measurement example is not arranged reaches the ceiling, most of them reach other areas instead of the place where the illuminometer is arranged, and the illuminometer is arranged. Since the amount of light reaching the position is very small, the influence on the measurement is not problematic.

  Further, the contrast is measured in a bright room environment (100 lx at the point A which is the center of the screen), and the surface layer of each measurement example is the point A2 where the center is the screen center of the reflective screen 10A when viewed from the front. Are arranged so as to coincide with each other, and image light is projected from the image source LS, D8 = 3 m from the surface of the surface layer of each measurement example to the image source side at the center in the horizontal direction of the screen of the reflective screen 10A, from the floor At the position of D7 = 1.04 m, the measurer M visually observes the point A2 which is the center of the reflective screen 10A, and the image with a low contrast and the image looks whitish is disabled (x), and a good image with a high contrast is obtained. What can be visually recognized was judged as good (◯).

  Further, regarding the bright line (hot line), in the dark room environment, the surface optical layer of each measurement is arranged at the same position as the above-described contrast measurement, white light is projected from the image source LS, and the reflective screen 10A At the center of the screen in the left-right direction and at a position of D8 = 3 m from the surface of the surface optical layer of each measurement example to the image source side and D7 = 1.04 m from the floor, the measurer M visually observes each surface optical layer and Evaluation was made by regarding the case where no is observed (×) and the case where no bright line was observed as being good (◯).

As shown in Table 1, the reflection of the image light on the ceiling is sufficiently reduced with respect to the reflective screen including the surface optical layers of Measurement Examples 3 and 4 corresponding to the examples of the present embodiment, and Sufficient contrast and bright line (hot line) improvement effects were obtained.
However, for the reflective screens provided with the surface optical layers of measurement examples 1, 2, 5, and 6 corresponding to the comparative example, the reflection of the image light on the ceiling is remarkable, the contrast is lowered, etc. It was not preferable because it hindered the viewing of good images.
From the above, according to the present embodiment, it is possible to sufficiently improve the reflection of image light on the ceiling, suppress bright lines, and display a bright and good image.

(Second Embodiment)
FIG. 8 is a diagram illustrating the reflective screen 20 according to the second embodiment.
FIG. 8A shows an enlarged part of the same cross section of the reflective screen 20 as in FIG. 2, and FIG. 8B shows the surface optical layer 25 of the reflective screen 20 in FIG. A part of it is shown enlarged.
The reflective screen 20 of the second embodiment is different from the reflective screen 10 of the first embodiment in that the cross-sectional shape of the unit prism 251 of the surface optical layer 25 is an unequal triangular shape and θ3 <θ2. These are the forms similar to the reflective screen 10 of 1st Embodiment. Therefore, parts having the same functions as those of the first embodiment are denoted by the same reference numerals or the same reference numerals at the end thereof, and repeated description is appropriately omitted.

The reflective screen 20 of the second embodiment includes a surface optical layer 25, a base material layer 14, a lens layer 13, a reflective layer 12, and a protective layer 11.
The reflective screen 20 of the second embodiment can be used for the video display system 1 shown in the first embodiment.

The surface optical layer 25 includes a plurality of unit prisms 251 each having a substantially triangular prism shape whose longitudinal direction is the horizontal direction of the screen.
The unit prism 251 of the surface optical layer 25 has an unequal triangular shape in cross section parallel to the vertical direction of the screen and parallel to the thickness direction, and with respect to the apex t3 when the reflective screen 20 is used. The screen 253 is located on the lower side in the vertical direction of the screen, and the surface 252 is located on the upper side.
In this unit prism 251, θ1> 90 ° and θ2> θ3.

As shown in FIG. 8B, above the screen of the reflective screen 20, the image light L <b> 6 is a flat reflective screen that does not have the unit prism 151 with respect to the lower surface 253 of the unit prism 251. The incident angle can be smaller than the incident angle. Therefore, the image light L5 can be efficiently incident into the reflective screen 120 from the surface 253, and the light reflected by the surface of the reflective screen 20 and reflected toward the ceiling can be greatly suppressed.
In addition, external light G3 such as illumination light enters the upper surface 252 of the unit prism 251 and is absorbed by the colored layer 142 or the non-lens surface of the unit lens 131 as in the above-described external light G1 and G2. The light is absorbed by the protective layer 11 formed on the surface 133 or reflected downward by the reflective layer 12. Therefore, the external light reaching the observer O side can be greatly suppressed, and the reduction in contrast due to the external light can be suppressed.

Therefore, also in the present embodiment, it is possible to greatly suppress the reflection of the image on the ceiling, suppress the bright line, and display a bright and good image.
Moreover, in this embodiment, since external light can be efficiently incident on the reflective screen 20 and absorbed by the colored layer or the protective layer 11 having internal light absorption, the contrast can be further improved. .
The unit prisms 251 may be configured such that their shapes (arrangement pitch P1, angles θ1, θ2, θ3, etc.) change along the arrangement direction.

(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) The layers positioned between the surface optical layers 15 and 25 and the reflective layer 12 in the thickness direction of the reflective screens 10 and 20 are appropriately selected according to the desired optical characteristics and the environment in which they are used. Can be provided.
For example, the reflective screens 10 and 20 may be provided with a light transmissive glass substrate, a resin plate, or the like in order to maintain flatness as the reflective screen.
In addition, for example, the reflection type screens 10 and 20 may include an anisotropic diffusion layer or the like in which the diffusion action in the horizontal direction of the screen is larger than the diffusion action in the vertical direction of the screen.

(2) The unit prism is not limited to a substantially triangular prism shape, and may be another polygonal prism shape such as a substantially pentagonal prism shape.

(3) The surface optical layers 15 and 25 may be appropriately provided with an antireflection function, an antiglare function, an ultraviolet absorption function, an antifouling function, an antistatic function, and the like. In this case, for example, the surface optical layers 15 and 25 may have these functions, or a layer having these functions may be provided as a separate layer between the surface optical layers 15 and 25 and the base material layer 14. Alternatively, the resin for forming the surface optical layers 15 and 25 may be formed by selecting one having the above function.

(4) The reflective layer 12 is composed of a white or silver paint, an ultraviolet curable resin or a thermosetting resin containing a white or silver pigment or beads, a metal vapor deposition film such as silver or aluminum, a metal foil, or the like. A coating material containing pulverized particles and fine flakes may be applied and cured by various coating methods such as spray coating, die coating, screen printing, and groove filling by wiping.
Further, the reflective layer 12 may be formed on the non-lens surface 133. In this case, the reflective layer 12 may have a form in which the valleys between the unit lenses 131 are filled and the back side surface thereof is substantially planar, or is formed with a predetermined thickness along the uneven shape of the unit lenses 131. The thickness may not be uniform as long as it has sufficient reflection characteristics.

(5) The unit lens 131 may have, for example, a substantially trapezoidal cross-sectional shape, and the lens surface 132 and the non-lens surface 133 face each other across a top surface (not shown) parallel to the screen surface. Good. At this time, the top surface is preferably formed in a region that does not contribute to the reflection of the image light. A protective layer 11 may be formed on the top surface, or a reflective layer 12 may be formed.
In the cross section shown in FIG. 2 and the like, the unit lens 131 may have a part of the lens surface 132 and the non-lens surface 133 curved, or at least one of the lens surface 132 and the non-lens surface 133. However, it is good also as a form comprised from a some surface.

(6) The colored layer 142 may contain a diffusing material. Alternatively, the base material layer 14 may be a single layer and may contain both a diffusing material and a colorant such as a pigment or a dye.
In addition, the light diffusion layer 141 and the colored layer 142 may be formed as separate bodies, and may be integrally joined with an adhesive (not shown) or the like.

(7) The reflective screens 10 and 20 may not be provided with the support plate 50, for example, and may be joined to a wall surface or the like via an adhesive layer or the like, or the wall surface in a state where the support plate 50 is joined to the back surface. It is good also as a form etc. which are fixed to a wall, or are hung on a wall surface by support members, such as a hook.
Moreover, the reflective screens 10 and 20 are good also as a rollable form which can be wound up and stored when not in use. 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 and 20 is covered with a cloth or resin light-shielding curtain that hardly transmits light, a layer that improves scratch resistance, or the like. It is good also as a form to do.

(8) Although the surface optical layers 15 and 25 and the lens layer 13 are made of an ultraviolet curable resin and are integrally formed on each surface of the base material layer 14 by an ultraviolet molding method, the present invention is not limited thereto. For example, it is made of a thermoplastic resin or the like, and the surface optical layers 15 and 25 and the lens layer 13 may be formed by an extrusion molding method or another manufacturing method.

(9) The video source LS may be positioned above the reflective screens 10 and 20 in the vertical direction, and the video light L may be projected obliquely from above the reflective screen 10. At this time, the reflective screen 10 may have a form in which the vertical direction of the surface optical layers 15 and 25 and the lens layer 13 shown in FIG. 2, FIG. 3, FIG.

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

DESCRIPTION OF SYMBOLS 1 Image display system 10,20 Reflective screen 11 Protective layer 12 Reflective layer 13 Lens layer 14 Base material layer 15,25 Surface optical layer 151,251 Unit prism LS Image source

Claims (5)

A reflective screen that reflects image light projected from an image source and displays it in an observable manner,
A reflective layer that reflects image light;
A surface optical layer in which a plurality of substantially prismatic unit prisms are arranged on the image source side surface of the reflective screen in the thickness direction of the reflection type screen and are convex on the image source side. When,
With
In the longitudinal direction of the unit prism, the height of the unit prism changes regularly or irregularly,
The height of the unit prism in the longitudinal direction of the unit prism changes periodically in the longitudinal direction, the period is P, and the difference d between the highest point and the lowest point of the unit prism is When the ratio P / d is
14 ≦ P / d ≦ 84
Meeting,
Reflective type screen. A reflective screen that reflects image light projected from an image source and displays it in an observable manner,
A reflective layer that reflects image light;
A surface optical layer in which a plurality of substantially prismatic unit prisms are arranged on the image source side surface of the reflective screen in the thickness direction of the reflection type screen and are convex on the image source side. When,
With
In the longitudinal direction of the unit prism, the height of the unit prism changes regularly or irregularly,
The height of the unit prism in the longitudinal direction of the unit prism periodically changes in the longitudinal direction, and the period P is 100 μm or more and 600 μm or less,
Reflective type screen. The reflective screen according to claim 1 or 2 ,
The height of the unit prisms is different from the height of the adjacent unit prisms on a straight line parallel to the arrangement direction;
Reflective type screen. The reflective screen according to any one of claims 1 to 3 , wherein
A lens 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 and convex on the back side are arranged on the back side of the surface optical layer in the thickness direction of the reflective screen With layers,
The reflective layer is formed on at least the lens surface of the unit lens;
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