JP2011112669A - Reflection screen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflection screen for projection enabling bright and high-contrast display in a wide range even when an image is projected at a close range by a projector from the upper part of the screen under bright room environment where ceiling light is turned on. <P>SOLUTION: The reflection screen includes: a first optical element having a first surface that refracts incident light, a second surface that totally reflects or transmits the light refracted by the first surface, and a third surface that absorbs or transmits the light totally reflected by the second surface; and a second optical element having a fourth surface on which the light transmitted through the second surface is made incident, a fifth surface that reflects the light transmitted through the fourth surface, and a sixth surface that projects the light reflected by the fifth surface to the front of the screen. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a screen that displays an image by reflecting image light projected from an image display device such as a projector.

When an image projected from a projector is projected in a bright room environment, there is a problem that external light scattered on the screen surface is reflected to the viewer side and becomes a reflected image with low contrast, resulting in poor visibility.
Various methods have been proposed for obtaining high contrast in such a bright room environment.

For example, as in Patent Document 1, a method for obtaining contrast by providing sawtooth-shaped irregularities on the screen surface, having a light absorbing surface and a light reflecting surface, and absorbing external light coming from above the screen on the light absorbing surface and so on.
Further, as disclosed in Patent Document 2, there is a method in which a layer that reflects light and a unit prism shape that absorbs light are alternately arranged, and external light coming from above the screen is absorbed to obtain contrast.

Japanese Patent Laid-Open No. 2006-23693 JP 2008-39862 A

Usually, as a form of projecting from the projector, there is a method of projecting from the lower side of the screen by placing the projector main body on the floor or desk, and a method of projecting from the upper side of the screen by installing the projector main body on the ceiling or the like. Assuming a general bright room environment, ceiling lighting is the light that has the strongest influence on the outside light that causes the contrast to decrease.
The methods of Patent Document 1 and Patent Document 2 are proposed as the former form, and a video with high contrast cannot be obtained in the latter form. This is because both the projector projection light and the ceiling illumination light enter the screen from the upper side of the screen, so that the projector projection light is absorbed together with the ceiling illumination light.
In order to obtain a high-contrast image in the latter form, it is necessary to have a structure in which only the projector projection light is reflected to the observer, and the ceiling illumination light and external light coming from other directions are absorbed and not reflected to the observer.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

Application Example 1 A reflective screen according to this application example includes a first surface that refracts incident light;
A first optical element comprising: a second surface that totally reflects or transmits light refracted by the first surface; and a third surface that absorbs or transmits light totally reflected by the second surface. When,
A fourth surface on which light transmitted through the second surface is incident; a fifth surface that reflects light transmitted through the fourth surface; and light reflected by the fifth surface is emitted forward of the screen. And a second optical element having a sixth surface.

  According to this application example, the light incident on the screen is transmitted or totally reflected by the second surface depending on the angle difference between the incident angles of the light incident on the first surface, and the light incident on the first surface is selected. It becomes possible. That is, the projector projection light passes through the second surface, enters the second optical element from the fourth surface, is reflected by the fifth surface, and exits from the sixth surface. On the other hand, external light is totally reflected by the second surface and absorbed or transmitted by the third surface. In this way, it is possible to provide a reflection screen that reflects projector projection light, efficiently absorbs external light, and can display a high-contrast image.

  Application Example 2 In the reflection screen according to the application example described above, a transparent medium having a refractive index smaller than that of the first optical element is provided between the second surface and the fourth surface. It is characterized by.

  According to this application example, since the refractive index of the transparent medium is smaller than that of the first optical element, the light is totally reflected or transmitted depending on the angle of light incident on the second surface. It can be transmitted and emitted to the observer.

  Application Example 3 In the reflective screen according to the application example described above, the area of the first surface is larger than the area of the sixth surface.

  According to this application example, the projector projection light is incident on the first surface of the first optical element and is emitted from the sixth surface of the second optical element, and the area of the first surface Is formed larger than the area of the sixth surface, the area of light incident on the sixth surface is reduced, and this makes it possible to suppress a decrease in the brightness of the projector projection light emitted from the screen. Become.

  Application Example 4 In the reflective screen according to the application example described above, the third surface has a black light absorbing material.

  According to this application example, since the black light absorbing material on the third surface has high light absorption characteristics, it absorbs external light efficiently. The emitted external light can be reduced.

  Application Example 5 In the reflective screen according to the application example described above, a seventh surface that reflects a part of the light reflected by the fifth surface that does not reach the sixth surface toward the sixth surface. Is provided at a position facing the fourth surface.

  According to this application example, since the light reflected by the fifth surface can be reflected by the seventh surface so as to be incident on the sixth surface, the light that does not directly enter the sixth surface can be reflected. Thus, the light reflected by the surface 5 is emitted from the sixth surface without waste, so that the projector projection light can be emitted to the observation side without waste.

  Application Example 6 In the reflective screen described in the above application example, the sixth surface has a fine uneven shape on the surface.

  According to this application example, since the fine uneven shape is formed on the surface of the sixth surface from which light is emitted, the emitted light is emitted while diffusing due to the difference in the refraction angle due to the fine unevenness. Thus, an image can be provided over a wide range to the observer.

  Application Example 7 In the reflection screen according to the application example described above, a metal reflective material having high reflectance characteristics is provided on the surface of the fifth surface.

  According to this application example, the surface of the fifth surface is provided with the metal reflector having high reflectance characteristics, and thus the light from the fourth surface is reflected toward the sixth surface without being attenuated. As a result, it is possible to suppress a decrease in luminance of light emitted from the projector.

  Application Example 8 In the reflection screen according to the application example described above, the fifth surface has a plurality of surfaces or curved surfaces, and reflects light incident on the plurality of surfaces or curved surfaces in different directions. And

  According to this application example, the fifth surface has a polyhedral shape in order to reflect the light from the fourth surface toward the sixth surface, and all the light from the fourth surface is the sixth surface. The light can be reflected toward the surface, so that the projector projection light can be emitted to the observation side without waste.

It is a figure which shows the positional relationship of the reflective screen which concerns on 1st Embodiment of this invention, a projector, and ceiling illumination light. It is a fragmentary sectional view which shows the structure of the reflective screen which concerns on 1st Embodiment of this invention. It is a figure which shows the mode of the reflection of the light ray inside the structure of the reflective screen which concerns on 1st Embodiment of this invention. It is a figure which shows the manufacturing method of the 1st optical element of the reflective screen which concerns on 1st Embodiment of this invention. It is a figure which shows the manufacturing method of the 2nd optical element of the reflective screen which concerns on 1st Embodiment of this invention. It is a figure which shows a mode that the 1st optical element and 2nd optical element of the reflective screen which concern on the 1st Embodiment of this invention were bonded together.

(First embodiment)
FIG. 1 is a diagram showing an arrangement relationship between a projector main body and ceiling lighting with respect to a screen. The upper end 4 of the screen 1 is the ceiling side with respect to the observer, and the side facing the ceiling is the lower end 5 of the screen 1. The projector 2 is installed at a distance L1 from the screen 1 to the viewer side with respect to the screen 1 in the ceiling direction. The ceiling illumination 3 is installed at a distance L2 from the screen 1 toward the observer side with respect to the screen 1. The distance from the screen to the viewer side of the projector 2 and the ceiling illumination 3 is L1 <L2. In this arrangement state, the incident angle θP1 of the projection light P1 incident on the upper end 4 and the incident angle θG1 of the illumination light G1 of the ceiling illumination 3 have a relationship of θP1> θG1. The incident angle θP2 of the projection light P2 incident on the lower end 5 and the incident angle θG2 of the illumination light G2 of the ceiling illumination 3 have a relationship of θP2> θG2.

FIG. 2 is a partial cross-sectional view showing the structure of the screen 1.
The optical element 6 (first optical element) has a triangular shape made of a transparent resin or the like, and has a transparent surface 8 (first surface) on the viewer side and a slope 9 (on the opposite side of the viewer). The third surface) and the slope 10 (second surface). The surface of the slope 9 is painted black to absorb light. The inclined surface 10 is inclined so as to totally reflect light incident at a predetermined angle or less and transmit light having an angle larger than that. The specified angle is an angle at which projector projection light (incident angle θ1) is transmitted and ceiling illumination light (incident angle θ2) is totally reflected.

  The optical element 7 (second optical element) has a pentagonal shape made of a transparent resin or the like, and has a surface 11 (sixth surface) that diffuses and transmits light on the viewer side, and an opposite side of the viewer. Further, it is composed of an inclined surface 12 (fourth surface), an inclined surface 14 (seventh surface), and a surface 13 (fifth surface) composed of surfaces having different angles. The inclined surface 12 has the same inclination angle as the inclined surface 10. The surface 13 is coated with a reflective material having a high reflectance characteristic such as aluminum vapor deposition, and has two surfaces with different angles so as to efficiently reflect the light coming from the inclined surface 12 to the surface 11. In order to prevent the light reflected by the surface 13 from becoming stray light in the optical element 7 by using two surfaces, this embodiment uses two surfaces 13, but the surface can be formed. It may be further diversified or curved in the range. The inclined surface 14 gives an inclination angle so that the light reflected by the surface 13 does not reach the surface 11 directly but is reflected to the inclined surface 14 side so as to reach the surface 11. Fine irregularities are provided on the surface 11, and the irregularities allow light to be emitted while diffusing to the viewer side.

  The optical element 6 and the optical element 7 are arranged with a medium 15 made of a transparent material having a refractive index characteristic smaller than the refractive index of each optical element. In the present embodiment, this medium is air having a refractive index of 1.0, but a transparent material smaller than the refractive index of the optical elements 6 and 7 by 0.25 or more is preferable. For example, the optical element 6 and the optical element 7 are preferably made of vinylidene chloride resin having a refractive index of 1.6, and the medium 15 is preferably made of fluororesin (PTFE) having a refractive index of 1.35.

  A state of light rays in the optical element when projector projection light and ceiling illumination light are incident on the optical element will be described. The projector projection light 17 is reflected by the surface 13 through the surface 8, the inclined surface 10, and the inclined surface 12 of the optical element 6, and diffused and emitted from the surface 11 to the observer. On the other hand, in the ceiling illumination light 18, the light that enters from the surface 8 is totally reflected by the slope 10 and absorbed by the slope 9. When the projector projection light 17 is incident not on the surface 8 but on the surface 11, it becomes stray light in the optical element 7 and is not emitted to the observer side, causing a reduction in reflection luminance. Therefore, the area of the surface 8 of the optical element 6 is as much as possible. Is made larger than the area of the surface 11 of the optical element 7. Further, the element size (see FIG. 2) is set to be equal to or smaller than the projection pixel pitch in order to prevent the deterioration of the projection image quality.

  FIG. 3 is a diagram showing a ray trajectory by simulation in the present embodiment. FIG. 3A shows a case where projector projection light incident on the upper end of the screen is assumed, and it can be seen that light incident at an angle of 50 degrees is diffused and emitted toward the viewer. FIG. 3B shows a case where projector projection light incident on the lower end of the screen is assumed, and it can be seen that light incident at an angle of 70 degrees is diffused and emitted toward the viewer. FIG. 3C shows a case where ceiling illumination light incident on the lower end of the screen is assumed, and it can be seen that light incident at an angle of 40 degrees is absorbed without being emitted to the viewer side. Absorbing incident light at 40 degrees or less, for example, can absorb light from a room window at the same height as the screen without reflecting it to the observer side. Therefore, it is possible to provide a reflective screen having a high contrast that is not easily affected by outside light even in a bright room environment.

  4, 5, and 6 are diagrams for explaining a manufacturing method of the reflective screen according to the present embodiment. FIG. 4 is a schematic diagram of a method for manufacturing the first optical element. The shape of the upper mold 19 is transferred to the transparent resin 20 by heat and pressure onto the transparent resin 20 such as vinylidene chloride resin or polystyrene, and the transparent resin shape is obtained. 21 is molded. In order to apply the black paint that absorbs light only to the light absorption surface, the black paint is applied by the spray 22 in a state where the surfaces other than the light absorption surface are protected by the mask 23 to form the light absorption surface 24. An adhesive is applied to the plane 26 at the apex of the triangle with a roller 25 or the like.

  FIG. 5 schematically shows a method for manufacturing the second optical element. The upper mold 28 is formed by heat and pressure on a thin sheet in which a metal film 30 such as aluminum is bonded to a transparent resin 29 such as vinylidene chloride resin or polystyrene. The shape of the lower mold 31 is transferred to the transparent resin, and the transparent resin shape 32 is molded. Further, a surface having fine irregularities formed on the surface 27 of the upper mold 28 by blasting or the like is transferred to the transparent resin 29 to form a light diffusing and emitting structure having fine irregularities on the surface 33. .

  Then, as shown in FIG. 6, two transparent resin sheets are bonded together so that the concave and convex surfaces of the first optical element 34 and the second optical element 35 are alternately overlapped, and a reflective screen is completed.

  The present invention is not limited to the above-described embodiment, and various changes can be made. For example, in the above-described embodiment, the inclined surface 12 has the same inclination angle as the inclined surface 10, but the inclination angle may be different.

  DESCRIPTION OF SYMBOLS 1 ... Reflective screen 2 ... Projector 3 ... Ceiling illumination 4 ... Screen upper end part 5 ... Screen lower end part 6 ... 1st optical element 7 ... 2nd optical element 8, 9, 10 ... Surface of 1st optical element 11, 12, 13, 14 ... second optical element surface 15 ... medium 17 ... projector projection light 18 ... external light 19 ... first optical element upper mold 20 ... transparent resin 21 ... molded resin 22 ... spray 23 DESCRIPTION OF SYMBOLS ... Mask 24 ... Light-absorbing material 25 ... Roller 26 ... Adhesive 28 ... Upper mold for second optical element 29 ... Transparent resin 30 ... Metal film 31 ... Lower mold for second optical element 32 ... Resin after molding 33 ... Uneven surface.

Claims (8)

A first surface that refracts incident light; a second surface that totally reflects or transmits light refracted by the first surface; and a second surface that absorbs or transmits light totally reflected by the second surface. A first optical element comprising three surfaces;
A fourth surface on which light transmitted through the second surface is incident; a fifth surface that reflects light transmitted through the fourth surface; and light reflected by the fifth surface is emitted forward of the screen. And a second optical element having a sixth surface.   The reflective screen according to claim 1, further comprising a transparent medium having a refractive index smaller than that of the first optical element between the second surface and the fourth surface.   The reflective screen according to claim 1, wherein an area of the first surface is larger than an area of the sixth surface.   The reflective screen according to claim 1, wherein the third surface includes a black light absorbing material.   A seventh surface that reflects a part of the light reflected by the fifth surface and does not reach the sixth surface toward the sixth surface is provided at a position facing the fourth surface. The reflective screen according to claim 1, wherein the reflective screen is provided.   The reflective screen according to claim 1, wherein the sixth surface has a fine uneven shape on the surface.   The reflective screen according to any one of claims 1 to 6, wherein a metal reflective material having a high reflectance characteristic is provided on a surface of the fifth surface.   8. The fifth surface according to claim 1, wherein the fifth surface has a plurality of surfaces or curved surfaces, and reflects light incident on the plurality of surfaces or curved surfaces in different directions. Reflective screen.

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