JP2012042518A - Reflection type front screen and stereoscopic display system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of a reflection type front screen capable of displaying images of high contrast even in a bright room illumination environment, to suppress external light from the vicinity of a projector, and to enable an angular field of view to be wide.SOLUTION: As to the first problem, a reflection type front screen includes: a total reflection prism sheet 22 in which a plurality of prism elements 24, each of which consists of an incident face t and a total reflection face u and has an apex angle θ, are vertically arranged on the incident side, and an emission surface of which consists of a transparent material 21a without surface shape of a refraction factor of n, and the apex angle θ of the element 24 is equal to or more than sin-1(1/n); a black mask 28 arranged on the emission surface of the sheet 22; and scatter reflection means 32 arranged on the emission surface of the sheet 22. As to the next problem, this is solved by means which actuates the external light suppression function of a lenticular lens with a BM in a transparent angle domain of a diffusion film having the transparent angle domain and a diffusion angle domain.

Description

  The present invention relates to a reflective front screen used for a front projection type display device and a stereoscopic display system using the same.

There are two types of projection-type display devices: rear-projection type and front-projection type. The rear-projection type requires a projector to be placed on the rear side of the screen. In other words, the limited space such as a conference room cannot be used effectively.
On the other hand, front projection type display devices can display images by placing a screen near a wall or window, and can effectively use a limited space such as a conference room. It is increasing.

  The front projection type projection display device has a configuration in which a screen, that is, a reflection type front screen is arranged substantially vertically, and a front projector that projects image light is arranged on the surface side thereof. There is a type that radiates image light to the reflective front screen from a position relatively close to the front of the reflective front screen, but it is placed diagonally forward and downward from the front and reflects diagonally upward from there. Increasing numbers of mold front screens are irradiated with image light.

  Projectors are placed diagonally forward and downward from the front, and image light is projected obliquely upward from there on the reflective front screen. Increasingly, external light is mostly reflected by illuminating lights. In many cases, the light is incident obliquely downward from above on the front screen. By setting the image light direction from the projector to the reflective front screen obliquely upward, the reflective front screen transmits external light and reflects the image light. This is because it is easy to do so, and even if the indoor lighting is bright, it is easy to make the image displayed with good contrast. And that is becoming increasingly important.

This is because when watching movies and movies using a projection display device, you may turn off the lights and darken the room, but refer to the materials prepared at hand while viewing the image on the screen. In addition, when taking a meeting by taking notes or having a discussion while looking at each other's faces among people gathered, or at a school (elementary school, junior high school, high school, university, various schools), various training When used for education at various seminars, etc., students must be able to view and read materials, textbooks and other texts, prints, etc., and take notes and notes.
To do this, the room lighting must be turned on and the room must be bright enough. Even if the room is brightened, the image displayed on the screen must have a sufficient contrast with the outside light due to the brightness of the room.

And the technique which responds to the request was developed, and the result was disclosed by Unexamined-Japanese-Patent No. 2009-271263 (: patent document 1) etc. FIGS. 25A to 25C are vertical sectional views showing different examples of the reflection type front screen introduced by Japanese Patent Application Laid-Open No. 2009-271263 (Patent Document 1).
The thing 2a shown in FIG. 25 (A) has a diffuser plate 4 that has the property of diffusing and transmitting only light incident from a specific angle region and straightly transmitting light incident from other angle regions. On the back side of the diffusion plate 4, a light transmission layer 6 having a surface whose back surface is bent in a sawtooth shape is disposed.

Specifically, the surface bent in a sawtooth shape on the back surface of the light transmission layer 6 is formed along a vertical direction between a mirror forming area 8 having a certain inclination and a non-mirror forming area 10 having a different inclination. The mirror-forming areas 8, 8,... Are formed with mirror-reflecting films 14, 14,.
The diffusing plate 4 is made of, for example, a diffusing sheet, and has a property of diffusing and transmitting incident light in an incident angle range of image light from a front projector, and transmitting incident light from outside the angular range in a straight line.

The light transmission layer 6 is made of, for example, resin, and the surfaces of the non-mirror-formed regions 10, 10,... Are made light diffusive by a roughening process.
The specular reflection film is formed by using, for example, anisotropic sputtering using a metal such as aluminum Al or silver Ag.

The reflective front screen 2b shown in FIG. 25B is common to the reflective front screen 2a, but differs only in two points. The first difference is that the mirror non-forming areas 10, 10,... Are not roughened, and the second difference is the same as the light transmission layer 6 on the back surface of the light transmission layer 6. The refractive index adjusting film 16 which is a transparent resin layer having the above refractive index is provided, and the light absorbing film 18 is further provided on the back surface of the refractive index adjusting film 16. The light that has entered the mirror non-formation areas 10, 10,... Enters the refractive index adjustment film 16 without being reflected there, and is absorbed by the light absorption film 18, so that it is not reflected.
The mirror non-formation areas 10, 10,... Are not particularly problematic even if they are roughened for some reason even if they are not roughened.

The reflective front screen 2c shown in FIG. 25C is different from the reflective front screen 2a in that the non-mirror forming areas 10, 10,. -Although it is different by the point which provided the light absorption films 20, 20, ... on the top, it is common in other points.
According to the reflection type front screens 2 (2a to 2c) shown in FIGS. 25A to 25C, the image light projected from the projector disposed obliquely below the mirror forming areas 8, 8, Are reflected on the front side by the specular reflection films 14, 14,... Formed thereon, and are viewed by people viewing the reflective front screen 2 on the front side.

Moreover, since external light, such as room illumination light or sunlight, is incident obliquely downward with respect to the reflective front screen 2, it is mainly incident on each non-mirror-forming area 10, 10,. The incident light is diffused there, or enters the refractive index adjusting film 16 from the areas 10, 10,... And is absorbed by the light absorption film 18, or is positioned on the areas 10, 10,. It is absorbed by the light absorbing film 20 and is not diffused or reflected on the front side of the reflective front screen 2.
Accordingly, the image light is effectively reflected on the front surface of the reflective front screen 2, and the external light is absorbed by the reflective front screen 2.

JP 2009-271263 A

  However, there were problems with this reflective screen. The film that plays an important role in this reflective screen is a diffuser plate 4 that has the property of diffusing and transmitting only light incident from a specific angle region and transmitting light incident from other angle regions. . The angle range for diffusing the light on the diffusion plate 4 is referred to as a diffusion angle region, and the angle region for allowing light to travel straight through is referred to as a transparent angle region. The basic principle of this reflective front screen is that projector light is projected from below, which is the transparent angle region, and the reflection direction is shifted from the regular reflection direction by the sawtooth reflector, and diffused toward the screen normal direction. By entering the diffusion angle region of the plate 4, the image is diffused and displayed.

  Therefore, the suppression function does not work at all with respect to the external light entering from the transparent angle region that is the incident angle region. This transparent angle area picks up the outside light that diffuses from a large floor area, so in the case of a bright floor, if there is illumination light on the ceiling, sunlight entering from the window, especially the western sun, There is a problem that the contrast is remarkably lowered. This problem is shown in FIG. It can be seen that external light from a considerably large area of the floor diffuses into the observation angle region and causes deterioration in contrast. In FIG. 26, 140 is a projector, and 142, 142,... Are lights arranged on the ceiling.

Further, when the projector is used as a ceiling-mounted projector, since the projectors that are widely used have ceiling lights 142, 142,... Between the screen and the ceiling-mounted projector, this light is contrasted. Will be greatly deteriorated.
In particular, when the screen is a large screen, the screen is installed on the upper side from a position higher than the desk, so the upper end of the screen is near the ceiling.

Therefore, at the upper end of the screen, the light beam from the ceiling-mounted projector is in the vicinity of low-angle vertical incidence, and therefore the ceiling-mounted projector must be separated from the screen by the projection distance. Therefore, in the case of a large screen, there will be a significant number of ceiling lights between the ceiling installed projector and the screen. This state is as shown in FIG. When the ceiling-mounted projector is installed in the back of the room, all the ceiling lights in the room cause a decrease in contrast.
This reflective front screen has further disadvantages. As a basic principle, since the transparent angle region and the diffusion angle region are folded back by a sawtooth mirror, the size of each angle region cannot be controlled independently.

Therefore, when the viewing angle in the vertical direction of the screen is increased, the transparent angle region that is the incident angle region and the diffusion angle region that is the observation angle region overlap. In this state, the external light entering from the diffusion angle region, which is the observation angle region, returns to the observation angle region again due to the overlap, and thus the contrast is remarkably reduced.
Therefore, as a basic design principle of the reflection type screen, the overlap between the transparent angle region and the diffusion angle region is not allowed.

Therefore, only a screen with a narrow vertical viewing angle can be realized. This is a big problem for the front screen. This is because a range where the entire screen can be seen is not obtained in the vicinity of the screen, and particularly in the case of a large screen, it must be far away from the screen.
Therefore, in a general meeting room, a seminar room, and a classroom, a wide space at the front of the room becomes unusable. As shown in FIG. 26, it can be seen that the observer cannot sit in front of the room. In contrast to the rear projection, the front projection should have an advantage that does not take up much space, but with this reflective screen, this advantage is halved.

The above problems are summarized as follows.
(1) There is no external light suppression function for external light entering from the transparent angle region, which is the incident angle region. Therefore, the contrast is remarkably deteriorated by the external light from the vicinity of the projector.
(2) Since the overlap between the transparent angle region and the diffusion angle region is not permitted as a basic principle, the vertical viewing angle cannot be increased and the entire screen cannot be viewed from a position close to the screen. Therefore, there is a problem that the room space cannot be used effectively.

In addition, the conventional reflective front screens 2a to 2c as shown in FIG. 25 have the above-described problems and the problem that the price is increased.
For example, when the reflective front screen 2a shown in FIG. 25A is taken as an example, the structure is, for example, a diffusion layer 4 made of a diffusion sheet and a transparent resin formed on the back surface thereof, and the back surface is sawtooth-shaped. A light transmission layer 6 formed and a mirror reflection film 14 made of, for example, metal (aluminum Al or silver Ag, etc.) formed only in each of the mirror formation areas 8, 8,. The number is complicated. In particular, the diffusion layer 4 cannot be realized by a single DLC film, and at least one diffusion layer 4 is required for vertical diffusion and at least three diffusion layers for horizontal diffusion. This is because there is a limit to the width of the diffusion angle region of a single DLC film, and it is necessary to laminate DLC films having a plurality of different diffusion angle regions in order to obtain a necessary diffusion angle. At present, at least four DLC films must be laminated, and the diffusion layer 4 is considerably expensive.

In addition, the non-mirror-formed areas 10, 10,... On the serrated back surface of the light transmission layer 6 need to be roughened, and only on the mirror-formed areas 8, 8,. In order to form the specular reflection film 14 on the surface, it is necessary to perform a high-priced process such as anisotropic sputtering of metal.
In the reflective front screens 2b and 2c shown in FIGS. 25B and 25C, it is not necessary to roughen the mirror non-forming areas 10, 10,... It is necessary to form the absorption film 18, or the troublesome and costly operation of forming the specular reflection film 14 only on each non-mirror formation area 10, 10.

In short, according to the conventional technology, despite the above-mentioned drawbacks (1) and (2), there is a problem that the price is high. Specifically, the reflective front screen is expensive, such as 10,000 yen per inch. Therefore, for example, in the case of 40 inches, the actual situation is about 400,000 yen and in the case of 100 inches, it is about 1 million yen.
On the other hand, a flat-screen television receiver, such as a liquid crystal television, can be purchased for 40,000 yen and can be purchased for 100,000 yen. The price of not only the screen but also the image receiving circuit is so low, whereas the projector has the disadvantages (1) and (2) as described above, but the screen alone is 1 per inch. It will be 10,000 yen.
This has been a factor that hinders the spread of projection display devices.

  In the present invention, first, the problem of the above two points (1) and (2), that is, (1) an external light suppression function for external light entering from a transparent angle region which is an incident angle region. Therefore, there is a problem that the contrast is remarkably deteriorated by external light from the vicinity of the projector, and (2) the overlap between the transparent angle region and the diffusion angle region is not allowed as a basic principle, so the vertical viewing angle is increased. In order to fundamentally solve the problem that the entire screen cannot be viewed from a position close to the screen and therefore the space of the room cannot be used effectively, the external light suppression principle of the conventional DLC front screen is fundamentally solved. However, on the front screen, the angle projection is converted to position information and the rear projection that suppresses external light is performed on the front screen. , It was conceived in response to devise a new concept is introduced to the transparent angular region.

  That is, the present invention has been made to solve such a problem, and effectively diffuses and reflects image light from the front projector to the front side, and external light such as indoor illumination light and outdoor sunlight. It is possible to provide a reflection-type front screen that can absorb a large amount of light and display a sufficiently high-contrast image even if the room lighting is sufficiently bright, and thereby promote the spread of front-projection display devices. Furthermore, it is also an object to provide a high-quality reflective front screen that enables observation from the vicinity of the screen by suppressing external light from the vicinity of the projector and expanding the vertical viewing angle, which are problems with the conventional front screen. .

  In the reflection type front screen according to claim 1, a plurality of prism elements having an incident angle and a total reflection surface on the incident side and having an apex angle θ are arranged along the vertical direction, and the emission side has an emission surface having no surface shape. A total reflection prism sheet made of a transparent material having a refractive index n, and the apex angle θ of each prism element set to a total reflection critical angle θc [= sin−1 (1 / n)] or more, and the total reflection prism sheet A black mask arranged on the exit surface except for a position where it does not block light incident on the entrance surface of each prism element and totally reflected by the total reflection surface, and disposed on the exit surface of the total reflection prism sheet It is characterized by having scattered scattering reflection means.

Incidentally, as a transparent material, those that are relatively excellent in processability and inexpensive are transparent synthetic resins, for example, acrylic resins, which have a refractive index n of about 1.5 and a refractive index of air of 1, in that case. The apex angle θ of each prism element is the total reflection critical angle θc [= sin−1 (1 / n)] = 41.8 ° or more. If the refractive index n of the transparent material is different, the optimum value of the apex angle θ is naturally different.
The scattering reflection means is preferably paper, particularly white paper. This is because it has almost ideal scattering reflection characteristics while being extremely inexpensive. A white paint may be used. This is because it is extremely inexpensive but has almost ideal scattering reflection characteristics and can be formed simply by coating.
In the specification and claims of the present application, the black mask includes, for example, a black stripe type extending in the horizontal direction, and a non-mask portion arranged vertically and horizontally in a pinhole shape and a portion other than the non-mask portion. A pinhole type that becomes a black light absorbing portion may be included.

According to a second aspect of the present invention, there is provided a reflective front screen according to the first aspect, wherein the apex angle of the prism element is substantially equal so that incident light is substantially perpendicular to the incident surface of the prism element in accordance with a change in incident angle of incident light. The prism element incident angle and the total reflection surface are rotated while being kept constant.
A reflection type front screen according to a third aspect is characterized in that, in the reflection type front screen according to the first or second aspect, a linear hot spot / hot line prevention light absorbing film is attached to each prism element apex portion. .

A reflection type front screen according to a fourth aspect is characterized in that, in the reflection type front screen according to the first, second, or third aspect, irregularities are formed on an incident surface of each prism element apex angle portion.
The reflection type front screen according to claim 5 is the reflection type front screen according to claim 1, 2, 3 or 4, wherein one or both of the incident surface and total reflection surface of each prism element are one-dimensionally condensed. It has a function.
Note that providing a one-dimensional condensing function on the incident surface can be realized by making the incident surface a cylindrical refractive lens. Also, providing the total reflection surface with a one-dimensional light collecting function can be realized by making the total reflection surface into a total reflection cylindrical concave mirror.

  A reflective front screen according to a sixth aspect is the reflective front screen according to the first, second, third, or fourth aspect, wherein the incident surface of each prism element is a cylindrical refractive lens having a one-dimensional condensing function. The total reflection surface of the element is a total reflection type cylindrical concave mirror having a one-dimensional condensing function, and the collection direction of the one-dimensional condensing function of the incident surface and the collection of the one-dimensional condensing function of the total reflection surface. Pinhole type black where the light condensing position is a pinhole when the black mask provided on the exit surface with no surface shape is reflected by the total reflection surface of each prism element. It is a mask.

A reflection type front screen according to a seventh aspect is the reflection type front screen according to the first, second, third or fourth aspect, wherein either one or both of the incident surface and the total reflection surface of each prism element are two-dimensionally condensed. The black mask provided on the exit surface that has a function and has no surface shape is a pinhole type black mask in which the condensing position of the light reflected by the total reflection surface of each prism element is a pinhole. And
The reflective front screen according to claim 8 is a mirror assembly having a plurality of mirror surfaces of a concave mirror having a metal reflection or total reflection tilt having a one-dimensional light collecting function or a two-dimensional light collecting function; The inclined surface which is substantially in the normal direction of the reflective screen has scattering reflection means having a diffusion function at each focal position, and a black mask having a light absorption function is provided at portions other than the focal position. Features.

  The reflective front screen according to claim 9 has a scattering reflection function at a substantially condensing position of large-angle incident light of a lenticular lens sheet having a one-dimensional condensing function or a fly-eye lens having a two-dimensional condensing function. It has a scattering reflection means, and a black mask having a light absorption function is provided in a portion other than the focal position on the emission side of the scattering reflection means.

The reflection type front screen according to claim 10 is the reflection type front screen according to claim 8 or claim 9, wherein the reflection type surface is subjected to surface-shaped metal reflection on the reflecting surface as scattering reflection means. It is characterized by using what was made to do.
The reflection type front screen according to claim 11 scatters from a low-angle incident to a substantially condensed position of large-angle incident light of a lenticular lens sheet having a one-dimensional condensing function or a fly-eye lens having a two-dimensional condensing function. It has a scattering reflection means having a reflection function, or further has a scattering reflection means to which a sawtooth reflecting surface structure for directing the diffusion principal ray direction to the screen normal direction is added in addition to this diffusion means, and this scattering reflection means A black mask having a light absorption function is provided at a portion other than the focal position on the exit side of the light source, and the transparent angle region and the diffusion are diffused on the surface or just inside the main plane of the lenticular lens or fly-eye lens. It has the diffusion film which has an angle area | region, It is characterized by the above-mentioned. As the diffusion film having the transparent angle region and the diffusion angle region, a DLC film is specifically used. However, since only one longitudinal diffusion is required, it is much cheaper than the conventional screen shown in FIG.

The reflective screen according to claim 12 is the reflective screen according to claim 11, wherein the scattering reflection means at the focal position has anisotropic scattering reflection characteristics in almost one direction, and a lenticular lens, or The diffusion characteristic of the diffusion film having the transparent angle region and the diffusion angle region on the surface or just inside the fly-eye lens is characterized by being substantially unidirectional anisotropic diffusion property.
The stereoscopic display system according to claim 13 uses the reflective front screen according to claim 9, claim 11, or claim 12, and maintains a polarization maintaining property and a reflecting surface of a diffusion film having a transparent angle region and a diffusion angle region. Realizes polarization maintaining and diffusing function by combining surface-shaped metal reflection with polarization maintaining diffusion, and assigning two linearly polarized light orthogonal to right eye image and left eye image, or assigning right circular polarization and left circular polarization , (Circle) 3D display is performed by using polarized glasses.

  A stereoscopic display system according to claim 14 is a shutter glasses that uses the reflective front screen according to any one of claims 1 to 12 to display a right-eye image and a left-eye image in a time-division manner at high speed and to synchronize with this. Is used to perform high-contrast stereoscopic display even in a bright place.

According to the reflection type front screen of the first aspect, if the image light from the projector is incident on the incident surface of each prism element in the substantially normal direction of the incident surface, the incident surface of each prism element. Nearly all of the incident light passes through the incident surface and can be reflected to the exit side by the total reflection surface.
This is because the vertex angle θ of each prism element is not less than 41.8 ° when the total reflection critical angle θc [= sin−1 (1 / n) and the refractive index n of the prism sheet material is 1.5]. This is because the incident angle of the image light incident on the total reflection surface (the angle of the incident light with respect to the normal direction) is equal to or greater than the total reflection critical angle and is totally reflected to the emission side.

On the exit side, there is a scattering reflection means at a position where the image light reflected by the total reflection surface of each prism element reaches, and the other positions are a black mask (a black stripe is an example of a black mask). Therefore, the image light can be diffused and reflected effectively to the front side of the reflective front screen, and the external light can be effectively absorbed by the black mask.
Therefore, it effectively scatters and reflects the image light from the front projector to the front side, effectively absorbs outside light such as indoor illumination light, outdoor sunlight, etc. It is possible to provide a reflective front screen that can display a sufficiently high-contrast image even if the brightness is sufficient for taking notes.

In the reflection type front screen according to the first aspect of the present invention, the only requirement for the material of the total reflection prism sheet is basically a transparent material having a refractive index appropriately larger than 1, and the condition is a normal transparent resin. Is very inexpensive. Prism element formation can also be performed at low cost by molding.
By the way, acrylic and other synthetic resins and glasses have a refractive index of about 1.5.
The black mask can be formed by applying a light-shielding material (black one) to the exit surface of the total reflection prism sheet and patterning it. Specifically, for example, a liquid mask film in which a photosensitive material for UV light (ultraviolet light) is added to a black material having light shielding properties is coated on the back surface of the total reflection prism sheet, and UV light (ultraviolet light) is applied to the liquid mask film. ) Is selectively irradiated (exposure) and developed, and can be easily formed at a low cost by the established photolithography technique, and the cost required for the formation can be extremely low.

Further, the scattering reflection means can be formed of paper, in particular, white paper or white paint, and these are also extremely low in material cost, and the cost required for formation can be extremely low.
That is, white paper or white paint as the scattering reflection means has extremely excellent scattering reflection characteristics. This is because white paper and white paint look white even when viewed from any direction, that is, whether the viewing angle relative to the normal is small or large, and the reflection angle range is extremely wide. This is the best characteristic for a reflective front screen that requires a wide angle range in which an image can be viewed well with respect to the screen, and white paper and white paint are very prestigious with respect to the characteristic.

That is, the reflective front screen of claim 1 has excellent scattering reflection characteristics such as white paper and white paint, and images can be visually recognized from a wide angle range. However, basically, an inexpensive material is effectively utilized. Is. In addition, these materials are not merely inexpensive, and no special technique is required for formation and assembly, and the formation cost can be extremely reduced.
The reflective front screen according to claim 1 is based on a total reflection prism sheet having a low material cost and a forming cost, a black mask having a low material cost and a forming cost, and a material cost and a forming method, at least on the basic principle. The conventional reflective type front shown in FIG. 25 can be constructed with scattering and reflecting means made of low-cost white paper or white paint, and the number of layers to be formed is small and the cost for forming each layer is low. A reflective front screen can be provided at a very low cost compared to a screen.

However, in principle, a reflective front screen can be constructed with a total reflection prism sheet, a black mask, and scattering reflection means, but in practice a reinforcing effect to maintain mechanical strength. It can be said that it is necessary to form a base on the back surface of the scattering reflection means [for example, means for reflecting image light passing through (transparent) white paper to the front side and contributing to image display].
However, since the base only needs to play a reinforcing role and a light reflecting role, it can be formed of a thin metal plate such as aluminum. Aluminum and the like are extremely inexpensive materials.
Therefore, in practice, a reflective front screen can be provided at a very low cost as compared with that shown in FIG.

  Specifically, it has been confirmed that a reflective front screen can be provided at a price of 1000 yen or less per inch of screen at the prototype stage. Therefore, the price of the reflective front screen can be reduced to 100,000 yen or less even with a large screen of 100 inches. However, if it goes into mass production system, it is possible to make it less than 500 yen per inch. Therefore, the price of a 100-inch reflective front screen can be reduced to 50,000 yen or less.

  According to the reflection type front screen of the second aspect, the prism element incident angle is maintained while keeping the apex angle of the prism element substantially constant so that the incident light beam is substantially perpendicular to the prism element incident surface according to the change in the incident angle of the incident light. Since the total reflection surface is made different depending on the prism element position, even if the projector is placed obliquely upward at a position very close to the reflection type front screen, image light is transmitted from the upper end to the lower end of the reflection type front screen. It is possible to obtain a characteristic that can be reflected effectively and reliably on the front side, and to obtain a uniform contrast from the upper end to the lower end of the reflective front screen.

According to the reflection type front screen of the third aspect, since the linear hot spot / hot line preventing light absorption film is formed at the apex corner of each prism element, there is no possibility of reflection on the top surface of each prism element. .
This point will be described in detail as follows.
In the reflection type front screen according to claims 1 and 2, if the angle θ between the incident surface of each prism element and the total reflection surface is not a predetermined angle, for example, 41.8 ° or more, and a relatively steep angle, the image from the projector The light cannot effectively be totally reflected to the scattering reflection means side by the total reflection surface, a part of the light is reflected to the front side, and a dot-like hot spot of relatively strong light or relatively strong light is vertically directed. An extended hot line is created. This significantly reduces the image quality.

  However, the top of each prism element tends to be rounded due to the limitations of the molding technology. And when the top has a rounded shape, when light enters the rounded top, the image light incident on the incident surface of each prism element is transmitted there and totally reflected by the total reflection surface. The expected phenomenon does not occur, and at least a part of the image light incident on the top of the image is reflected to the front side, thereby disturbing the image. As a result, the hot spots and hot lines described above are generated.

Therefore, in the reflection type front screen of claim 3, a light absorption film for preventing hot spots / hot lines (black, for example, similar to a black mask) is formed on the top of each prism element. By doing so, the image light incident in the vicinity of the top can be absorbed by the light absorption film for preventing hot spots / hot lines, and the generation of hot spots and hot lines can be prevented.
By the way, forming a light absorbing film for preventing hot spots / hot lines on the top of each prism element is possible, for example, with the prism sheet side of the prism sheet facing downward and the liquid surface of black ink stored in a black container. This can be done easily by a simple method such as immersing the top of each prism element.

  According to the reflection type front screen of the fourth aspect, since the irregularities are formed (roughened) at the apex corners of the prism elements, the image light incident on the apexes of the prism elements is scattered and reflected by the irregularities. Therefore, even if the top of the prism element is rounded, the image light that enters the top of the prism is scattered and reflected by the uneven surface, the light components that cause hot spots and hot lines are attenuated, and hot spots and hot lines are generated. Can be suppressed.

  According to the reflection type front screen of the fifth aspect, in the reflection type front screen of the first, second, third or fourth aspect, one or both of the incident surface and the total reflection surface of each prism element are one-dimensional. Since it has a condensing function, the ratio of the width (or area ratio) of the mask part of the black mask to the non-mask part (slit part) in the condensing direction is increased, thereby increasing the external light suppression ratio. As a result, the contrast ratio of the image with respect to external light can be increased.

  According to the reflection type front screen of the sixth aspect, in the reflection type front screen of the first, second, third or fourth aspect, the incident surface of each prism element is constituted by a cylindrical refractive lens having a one-dimensional condensing function. The total reflection surface of each prism element is constituted by a total reflection type cylindrical concave mirror having a one-dimensional condensing function, and the condensing direction of the one-dimensional condensing function of the incident surface and the one-dimensional collection of the total reflection surface. The light collection direction of the light function reflected by the total reflection surface of each prism element is made by making the light collection direction of the optical function substantially orthogonal to each other and the pinhole (non-mask portion) of each prism element of the black mask provided on the exit surface. Since it is positioned at the light position, the ratio of the width or area of the mask part of the black mask to the non-mask part (slit part) in the directions orthogonal to each other (for example, both in the vertical direction and the horizontal direction) Kikushi, increased dimensional synergistically external light suppression ratio, by extension, it is possible to increase the contrast ratio of an image for the external light two-dimensionally synergistically.

  According to the reflection type front screen of claim 7, in the reflection type front screen of claim 1, 2, 3 or 4, two or more dimensions are provided on one or both of the incident surface and the total reflection surface of each prism element. Condensing the light reflected by the total reflection surface of each prism element through the pinhole (non-mask part) of each prism element of the black mask prism element provided on the exit surface. Since it is located at the position, the ratio of the length (or width) of the mask part of the black mask to the non-mask part (slit part) can be increased two-dimensionally, and the external light suppression ratio can be increased two-dimensionally. As a result, the contrast ratio of the image to the external light can be increased two-dimensionally.

According to the reflection type front screen of claim 8, a mirror sheet comprising a plurality of mirror elements of a concave mirror having a one-dimensional condensing function or a two-dimensional condensing function and inclined by metal reflection or total reflection, and this focal position A scattering mask is provided at each focal position on the inclined surface where the diffuse principal ray direction is substantially the normal direction of the reflective screen, and a black mask having a light absorption function is provided at portions other than the focal position. Therefore, the plurality of mirror elements can condense one-dimensionally or two-dimensionally and reflect the diffused reflection at the focal position.
Accordingly, the ratio of the length (or width) of the mask portion of the black mask to the non-mask portion (slit portion) can be increased one-dimensionally or two-dimensionally, and then one-dimensionally or two-dimensionally. The external light suppression ratio can be increased, and thus the contrast ratio of the image to the external light can be increased one-dimensionally or two-dimensionally.

  According to the reflection type front screen of claim 9, a diffusion function is provided at a substantially condensing position of large-angle incident light of a lenticular lens sheet having a one-dimensional condensing function or a fly-eye lens having a two-dimensional condensing function. Since the black mask having the light reflecting function is provided on the exit side in the portion other than the focal position having the scattering reflection means, the image light is two-dimensionally or lentically by the lenticular lens sheet or by the fly-eye lens. The light can be condensed on the scattering reflection means located in the light condensing position. Accordingly, the ratio of the width or area of the mask portion of the black mask to the non-mask portion (slit portion) can be increased one-dimensionally or two-dimensionally, and the external light can be suppressed one-dimensionally or two-dimensionally. By increasing the ratio, the contrast ratio of the image with respect to outside light can be increased one-dimensionally or two-dimensionally.

According to the reflection type front screen of claim 10, in the reflection type front screen according to claim 8 or claim 9, as the scattering reflection means, the surface to be reflected is reflected by surface-shaped metal reflection. Since what is held and diffused is used, polarized light can be held even when reflected.
Therefore, three-dimensional display is performed by assigning two linearly polarized light orthogonal to the right-eye image and left-eye image, or assigning right-circular polarized light and left-circular polarized light, and using (circle) polarized glasses. It can be used as a screen that constitutes it in the system.

  According to the reflective front screen of claim 11, the substantially condensing position of the incident light from the low angle incidence to the large angle incidence light of the lenticular lens sheet having a one-dimensional condensing function or the fly-eye lens having a two-dimensional condensing function. A scattering reflection means having a scattering reflection function, or in addition to the diffusion means, a scattering reflection means having a sawtooth reflection surface structure in which the principal ray direction of diffusion is directed to the normal direction of the screen. A portion of the reflecting means other than the focal position on the exit side is provided with a black mask having a light absorption function, and a transparent angle region on the surface or immediately inside the main plane of the lenticular lens or fly-eye lens. And a diffusion film having a diffusion angle region, the image projection light from the projector first has a diffusion film having this transparent angle region. A transparent angle region of the beam, lenticular lens without diffusion or enters the fly-eye lens, the condensing function of the lens, is focused on the focal point of the lens. Since there is no black mask at this focal position and there is a scattering reflection means, the image light is diffusely reflected. When the scattering reflection surface is inclined and the surface has a rough serrated shape so that the diffuse reflection principal ray direction is the screen normal direction, the screen normal direction is diffused so as to be the diffusion principal ray.

In this case, since the diffusing position is the focal position of the lenticular lens or fly-eye lens, when passing through the lenticular lens or fly-eye lens again, the change in focal length due to the influence of spherical aberration will be Since there is almost no light, it should be almost parallel and not diffuse.
However, the reflective screen according to claim 11 has a diffusion film having a transparent angle region and a diffusion angle region in the vicinity of the main plane of the lenticular lens or fly-eye lens. The incident light is reflected, and the angle is changed by the reflecting surface and diffused. And when it comes out, it will inject into the diffusion angle area | region of a diffusion film. Accordingly, the image light is diffused here, and a function as a screen is realized.

On the other hand, since external light is incident from a direction other than the projector light, it is absorbed by the black mask regardless of whether it is incident from the transparent angle region or the diffuse angle region. Such a problem does not occur, and a very high contrast can be realized.
As the diffusion film having the transparent angle region and the diffusion angle region, a DLC film is specifically used. However, since only one longitudinal diffusion is required, it is much cheaper than the conventional screen shown in FIG.

According to the reflection type screen of claim 12, the scattering reflection means at the focal position of the reflection type screen according to claim 11 has an anisotropic scattering reflection characteristic in substantially one direction, and a lenticular lens, Alternatively, since the diffusion characteristic of the diffusion film having the transparent angle region and the diffusion angle region on the surface or in the immediate vicinity of the main plane of the fly-eye lens is an anisotropic diffusion property in almost one direction, Diffusion characteristics are controlled only in the lateral direction by the scattering reflection means, and the diffusion film having a transparent angle region and a diffusion angle region on the surface or just inside the main plane of the lenticular lens or fly-eye lens. The diffusion characteristic in the vertical direction can be controlled by the diffusion characteristic.
Therefore, it is possible to realize the control of the diffusion characteristics independently in the horizontal direction and the vertical direction.

  In addition, even if the transparent angle region and the diffusion angle region in the reflection type front screen of claim 11 and claim 12 are designed to overlap each other, a conventional diffusion film having a transparent angle region and a diffusion angle region was used. Since there is no problem of reduced contrast due to the reflection type front screen, the vertical viewing angle can be increased, and even on a large screen, the entire screen image can be viewed from the vicinity of the screen. It can be used effectively.

  According to the three-dimensional display system according to claim 13, using the reflective front screen according to claim 9, 11 or 12, the polarization maintaining characteristics of the diffusion film having a transparent angle region and a diffusion angle region Since the polarization maintaining diffusion function is realized by combining the polarization shape with surface shape metal reflection on the reflection surface, either two linearly polarized light orthogonal to the right eye image and the left eye image are assigned, or the right circular polarization and the left circular By assigning polarized light and using (circle) polarized glasses, stereoscopic display is possible.

  According to the three-dimensional display system of claim 14, the shutter glasses for displaying the right-eye image and the left-eye image in a time-sharing manner at high speed using the screen according to any one of claims 1 to 12, and synchronizing with the shutter glasses. Since it is used, a high-contrast stereoscopic display can be performed even in a bright place.

It is sectional drawing which shows the 1st Example (: Example 1) of this invention. (A)-(C) are sectional drawings which show each another modification which changed a part of the Example, respectively. (A), (B) shows the 2nd Example (: Example 2) of this invention, (A) is the perspective view which cut | disconnected a part, (B) is a front view. It is the perspective view which cut | disconnected a part of 3rd Example (: Example 3) of this invention. (A), (B) shows the 4th example (: Example 4) of the present invention, (A) is a sectional view and (B) is a perspective view showing an important section. It is the perspective view which cut | disconnected a part which shows the 5th Example (: Example 5) of this invention. (A)-(C) is an action explanatory view showing an outline of an action with respect to image light or external light from a projector by the reflective front screen of the fifth embodiment. (D), (E) is an effect explanatory view showing the outline of the effect on the external light by the reflective front screen of the fifth embodiment. It is the perspective view which cut | disconnected a part which shows the 6th Example (: Example 6) of this invention. It is the perspective view which cut | disconnected a part which shows the 7th Example (: Example 7) of this invention. It is sectional drawing for demonstrating the problem at the time of using a general lenticular lens (or fly eye lens) as a front screen. It is sectional drawing for demonstrating the principle of the said 7th Example paying attention to one convex curved surface (or convex spherical surface). It is sectional drawing for demonstrating the principle of the said 7th Example paying attention to several convex curved surface (or convex spherical surface). It is sectional drawing for demonstrating the principle of the said 7th Example also illustrating a black mask and a scattering-diffusion means. It is the perspective view which cut | disconnected a part which shows the 8th Example (: Example 8) of this invention. In order to explain the principle of a BM-equipped wrench / DLC front screen according to the ninth embodiment of the present invention, also illustrating a diffusion film having a transparent angle region and a diffusion angle region, a lenticular lens, a black mask, and a scattering diffusion means FIG. The BM wrench / DLC front screen modified type principle of the ninth embodiment of the present invention is illustrated with a diffusion film having a transparent angle region and a diffusion angle region, a lenticular lens, a black mask and a scattering diffusion means. It is sectional drawing for demonstrating. It is a figure explaining the suppression function with respect to the external light which approachs from the downward direction rather than a projector light among the external light suppression functions of the wrench with BM and the DLC front screen which are the 9th Example of this invention. FIG. 26 is a diagram illustrating that in the conventional reflective front screen shown in FIG. 25, it is impossible to suppress external light entering from below the projector light. It is drawing explaining the suppression mechanism of the external light which enters from the diffusion angle area | region in the wrench with BM and DLC front screen which is the 9th Example of this invention, and the principle which can expand a vertical viewing angle. It is drawing explaining the example of a ceiling installation type projector use environment. The principle of the tenth embodiment of the present invention when a BM-equipped wrench / DLC front screen is used for a ceiling-mounted projector is a diffusion film having a transparent angle region and a diffusion angle region, a lenticular lens, a black mask, and scattering diffusion. FIG. 5 is a cross-sectional view for illustrating and explaining the means, and in addition, is a diagram for explaining a mechanism for suppressing external light from the ceiling illumination between the ceiling-mounted projector and the screen. FIG. 26 is a diagram illustrating that external light from ceiling illumination between the ceiling-mounted projector and the screen cannot be suppressed when the conventional reflective front screen shown in FIG. 25 is used in a ceiling-mounted projector. It is sectional drawing which shows the wrench with BM and DLC front screen which are the 11th Example of this invention, and the principle at the time of using it with respect to a ceiling installation type projector is a diffusion film and lenty which have a transparent angle area | region and a diffusion angle area | region A cylindrical lens, a black mask, and scattering / diffusing means are also illustrated and described. (A)-(C) are sectional drawings which show another prior art example, respectively. It is a figure which shows the problem of the reflection type front screen of the prior art example shown in FIG.

In the present invention, the total reflection prism sheet, mirror element, lenticular lens sheet, fly-eye lens or the like is very preferably formed of a transparent synthetic resin. This is because the synthetic resin has a low material cost, can be processed by an inexpensive and sophisticated processing technique such as a molding technique, and the processing cost can be extremely low.
The scattering reflection means in the present invention is optimally paper, particularly white paper. This is because the surface of paper, especially white paper, is bright evenly when viewed from any angle, and white on white paper. This has a scattering reflection characteristic that is almost ideal in a reflective front screen that requires a wide viewing angle. Nevertheless, paper and white paper are very inexpensive members. Therefore, it is an ideal material as a scattering reflection means for diffusely reflecting the image light of the reflective front screen to the front side.
However, a white coating film may be used as the scattering reflection means. This is because it has excellent scattering and reflection characteristics like paper.

Furthermore, in the present invention, a black mask (in the application documents of this application such as this specification, the black mask includes a black stripe which is a stripe-shaped mask) on the exit side of a member such as a total reflection prism sheet. Although it is necessary to form it, it can be said that any material having a light absorption property may be used.
Specifically, a liquid film in which a black dye, a pigment or the like is contained in a UV photosensitive material is applied to the exit side of a member such as a total reflection prism sheet, and the film is selectively irradiated with UV light ( For example, the film can be easily formed by performing an exposure process by irradiating through a mask having a predetermined pattern) and then performing a development process.

Incidentally, the reflection type front screen of the present invention can be constituted only by providing the scattering reflection means such as paper on the emission side on which the black mask such as the total reflection prism sheet is formed, but in practice, the back side of the scattering reflection means. It can be said that it is preferable to provide a base. The reason is that the intensity of the reflection type front screen can be increased to a necessary level, and the image light that has passed through the scattering reflection means, for example, paper, can be reflected to the front side to make the image light stronger. .
As the base, a metal plate, for example, a thin plate made of aluminum Al is suitable. This is because it has reflectivity, can obtain the required mechanical strength even if it is thin, is ready for processing and has a very low material cost.

The reflective front screen of the present invention can be used in a stereoscopic display system. If the reflective front screen retains polarization characteristics, the right-eye image and left-eye image may be assigned to vertical linearly polarized light, horizontal linearly polarized light, right circularly polarized light, or left circularly polarized light and viewed with polarized glasses. .
In the case of total reflection, white paint, and diffusion on paper, polarization cannot be maintained. However, specular scattering by metal has a characteristic of maintaining the polarization of light. Therefore, when it is designed only by metal reflection, stereoscopic display using polarized light is possible.

Hereinafter, the details of the present invention will be described based on illustrated embodiments.
FIG. 1 is a cross-sectional view showing a first embodiment (Example 1) of a reflective front screen of the present invention, and FIGS. 2A to 2C are respectively different views in which a part of the embodiment is modified. It is sectional drawing which shows a modification.
First, a first embodiment will be described with reference to FIG.
21a is a reflection type front screen of the first embodiment, 22 is a total reflection prism sheet, and a large number of prism elements 24, 24,... Extending in the horizontal direction (horizontal direction) are arranged in the vertical direction (vertical direction). Many are arranged along. The total reflection prism sheet 22 is made of, for example, an acrylic transparent resin, and is formed by molding.

  .. Are light absorbing films for preventing hot spots and hot lines applied to the tops of the prism elements 24, 24,... By absorbing the image light incident on the tops. It serves to prevent the light incident on the front side from being reflected to the front side and generating hot spots and hot lines (lines extending in the vertical direction). The hot spot / hot line preventing light absorbing films 26, 26,... Are made of black ink or other paint liquid placed in a container or the like with the total reflection prism sheet 22 facing the prism element forming surface downward. It can be formed by immersing each prism element 24, 24,...

28, 28,... Are striped black masks extending in the horizontal direction, and are made of, for example, a black resin having photosensitivity to UV light. , 30,... Are gap portions (non-mask portions) between adjacent stripe-shaped masks 28, 28, 28, 28,..., And the total reflection surfaces of the prism elements 24, 24,. The position is set so as to be positioned where the image light reflected by the light reaches.
32 is a white paper which is a scattering reflection means laminated on the exit surface including the black masks 28, 28,... Of the total reflection prism sheet 22. The blank paper 32 has a characteristic that the surface uniformly and effectively scatters (diffuses) and reflects the incident light over a wide angle range, and is exposed to the non-mask portions 30, 30,.

Reference numeral 36 denotes a base layered on the back side of the blank paper 32, which secures the mechanical strength of the reflective front screen 2a and is partially incident on the surface of the blank paper 32 but transmitted through the blank paper 32 without being diffusely reflected. It plays a role of reducing the attenuation of image light by reflecting light.
The base 36 may be formed of a thin metal foil, such as an aluminum foil.

Since the total reflection prism sheet 22 is made of, for example, an acrylic transparent resin, the refractive index n is about 1.5. Each of the prism elements 24, 24,... Constituting the total reflection prism sheet 22 includes an obliquely downward incident surface t and a total reflection surface u having an apex angle θ with respect to the incident surface t. Is set to be perpendicular to the image light R from a projector (not shown).
The apex angle θ is set to a total reflection critical angle θc = sin−1 (1 / n) or more with respect to the air (refractive index is 1.00) of the total reflection prism sheet 22. In this case, since the refractive index of acrylic resin or the like is 1.5, the total reflection critical angle θc is 41.8 °, and the apex angle θ is θc or larger. In this embodiment, the apex angle θ is set to θc = 41.8 °.

Therefore, the total reflection surface u totally reflects the image light R from the projector incident in the normal direction with respect to the incident surface t on the inner surface toward the exit surface side of the total reflection prism sheet 22. Then, the positions where the image light R is totally reflected and incident are non-mask portions 30, 30,..., And the other portions are striped black masks 28, 28,. Yes.
Here, paying attention to the image light R incident on the incident surface t of one prism element 24a in FIG. 1, the ratio of the width between the non-mask portion 30 and the black mask 28 is considered as follows.

First, the distance between the tip of the incident surface t, that is, the apex of the prism element 24a, and the point where the light beam crossing the apex of the prism 24b below is incident is b, and the light beam crossing the apex of the prism element 24b is incident. And a is the distance between the bottom surface of the incident surface t and a.
The distance between the vertex of the normal that crosses the vertex of the prism 24b and the point where the normal reaches the incident surface t is L.

Then, the width ratio a: b between the non-mask portion 30 and the black mask 28 is expressed by the following equation.
a: b = Ltan 48.2 °: Ltan 20.9 °
= 1.1184: 0.3818
= 2.9281: 1
From the above, it can be said that a: b is approximately 3: 1, which is a sufficient value as the external light suppression ratio, and the contrast ratio of the image to the external light can be sufficiently increased.

Next, each modified example in which a part of the embodiment shown in FIG. 1 is modified will be described with reference to FIG.
In this modification, as shown in FIGS. 2A and 2B, the vicinity of the top of the incident surface t of each prism element 24, 24... Is roughened, or as shown in FIG. Furthermore, the moth-eye structure is formed [the portion v in FIG. 2C corresponds to that]. Roughening or moth-eye structuring to scatter image light that is incident on the vicinity of the top of the prism elements 24, 24,... And is not reflected at all, thus reducing hot lines and hot spots, It is not generated at all. v is the roughened or moth-eye structured part.

FIGS. 3A and 3B show a second embodiment (Example 2) of the reflective front screen of the present invention. FIG. 3A is a perspective view with a part cut away, and FIG. FIG.
21b is a reflection type front screen of the present embodiment. The embodiment (Example 1) 21a shown in FIG. 1 is different from the embodiment 21a in that the tops of the prism elements 24, 24,. The horizontal reflection elements 40, 40,... Are different in shape, but are common in other points. Since common points have already been described, description thereof will be omitted.

The hot-line preventing lateral reflection elements 40, 40,... Formed on the tops (tips) of the prism elements 24, 24,. Since light is diffusely reflected in the horizontal direction, the light component that is reflected in the vertical direction and forms a hot line is significantly attenuated, thereby preventing the hot line.
It should be noted that the arrangement pitch of the lateral reflection elements 40, 40,. This is because if the arrangement pitch is constant, interference occurs and interference fringes may occur in the image. The surface of the lateral reflection elements 40, 40,... Is a transparent medium surface such as an acrylic surface.

FIG. 4 is a perspective view of a third embodiment (Example 3) of the reflective front screen according to the present invention, partly cut away.
21c is a reflection type front screen of the present embodiment, and this reflection type front screen 21c is different from the second embodiment 21b in that at least image light is incident on the total reflection surface u of each prism element 24, 24,. The areas to be made are cylindrical concave curved surfaces 42, 42,..., And are different in that the incident image light is focused one-dimensionally. However, there are no other differences.

The embodiment 21c will be described in detail with reference to FIG. 4. One point on the extension line of the concave curved surface is set as o, the distance between the focal point of the concave curved surface and the point o is set as f, and the point o is the starting point. And a cylindrical concave curved surface 42 in which the following equation is established when the direction of the focal point is the y-coordinate and the point o is the starting point and the direction perpendicular to the y-coordinate is the x-coordinate.
y = x2 / 4f
Are formed in stripes so that only the condensing positions of the image light incident on the concave curved surfaces 42, 42,... Of the prism elements 24, 24,. Black masks 28, 28,... Are formed.

According to such a reflective front screen 21c, the condensing function by the concave curved surfaces 42, 42,... Can increase the ratio of the width of the mask portion to the non-mask portion, and the contrast with the background of the image. Can be made stronger.
In addition, the hot line prevention effect by the horizontal direction reflection elements 40, 40, ... is acquired similarly to 2nd Example (: Example 2) 21b.

FIGS. 5A and 5B show a fourth embodiment (Example 4) 21d of the reflection type front screen of the present invention. FIG. 5A is a sectional view, and FIG. 5B is a perspective view showing the main part. FIG.
This example 21d is basically different from the third example 21c in that each reflecting surface not only has a one-dimensional (vertical direction: longitudinal) condensing function, but is perpendicular to the condensing direction. It is different in that it has a shape having a light collecting function in a direction (horizontal direction: lateral direction).
That is, in the third embodiment 21c, the concave curved surface portion 42 of the total reflection surface of each prism element extending in the horizontal direction is cylindrical so as to collect light in the vertical direction with the center extending in the horizontal direction as the center of rotation. there were.

However, as shown in FIG. 5B, the fourth embodiment 21d also has a cylindrical shape that condenses in the lateral direction with the center extending in the vertical direction as the center of rotation, and is orthogonal to each other. It concentrates in two directions.
Therefore, unlike the first to third embodiments, the black mask 44 is not a stripe type but a pinhole type in which pinholes 46, 46,... is there.

According to the fourth embodiment 21d, the total reflection light on each total reflection surface 42, 42,... Is two-dimensionally collected, so that the area of the mask portion of the black mask 44 relative to the non-mask portion is increased. The ratio can be made larger.
Therefore, the contrast with respect to the background of the image can be made stronger than in the case of the third embodiment 21c.
In addition, since the part shown with the code | symbol 48, 48, ... of FIG. 5 carries out a diffuse diffuse reflection in a horizontal direction, a hot line can also be prevented.

FIG. 6 is a cross-sectional view showing a fifth embodiment (Example 5) of the reflective front screen according to the present invention, and FIGS. 7A to 7C and FIGS. 8E and 8F are reflective types. It is an effect explanatory view showing an outline of an effect on image light and external light from a projector by a front screen.
Reference numeral 21e denotes a reflective front screen of the present embodiment. The reflective front screen 21e receives image light from a projector disposed obliquely below the front surface on a substrate 62 made of metal (for example, aluminum) or a resin film. The condensing mirror surface 64 that receives and collects and reflects the light in a one-dimensional manner and the diffuse reflection surface 66 that receives light from the condensing mirror surface 64 are alternately arranged along the vertical direction. It differs from the first to fourth embodiments 21a to 21d in that the total reflection prism sheet 22 is not used.

The substrate 62 has a flat back side, and a condensing mirror surface 64 extending in the horizontal direction (horizontal direction) on the front side and a diffuse reflection surface 66 extending in the horizontal direction (horizontal direction) alternately along the vertical direction (vertical direction). It has an arranged shape.
Each condensing mirror surface 64, 64... Has a concave curved surface shape and has a one-dimensional condensing function. Each of the diffuse reflection surfaces 66, 66,... Is a surface that receives the light reflected by each of the condensing mirror surfaces 64, 64 ..., and a scattering reflection film 68 made of a white paint is formed on the surface. ing. Each diffuse reflection surface 66 may be a surface shape diffuse reflection surface that reflects and diffuses light according to the surface shape. In this case, the scattering reflection film 68 is unnecessary. Specular shape scattering by metal has the property of maintaining the polarization of light, and assigns stereoscopic display to vertical and horizontal linear polarizations, right circular polarization, right circular polarization, and left circular polarization for right-eye and left-eye images, This is an effective means when using polarized glasses.

70, 70,... Are striped black masks, 72, 72,... Are non-mask portions and are reflected by the respective collecting mirror surfaces 64, 64. It is positioned in the part where the light is collected. Then, the surface of the scattering reflection film 68 made of a white paint is exposed at the non-mask portions 72, 72,.
Therefore, the image light R from the projector is incident on each of the condensing mirror surfaces 64, 64,..., Is condensed and reflected one-dimensionally, and is reflected by the non-mask portions 72, 72,. It is diffusely reflected toward the front side of the mold front screen 21e and contributes to the display of images.

Next, the action of the reflective front screen 21e on light will be described with reference to FIGS. 7 (A) to (C) and FIGS. 8 (D) and 8 (E). In FIGS. 7 and 8, the scattering reflection film 68 made of white paint is omitted.
FIG. 7A shows image light (projector light) from a projector (not shown) disposed obliquely below the front surface of the reflective front screen 21e.
The image light is incident obliquely upward on each of the collecting mirror surfaces 64, 64,..., Where it is collected and reflected, incident on the focal point (the non-mask portion 66 located above), and exposed to the surface. Scattering reflection film [In FIG. 7, this scattering reflection film 68 is omitted. It is scattered and reflected from the surface to the front side in a fairly wide angle range. Therefore, an image can be visually recognized in a wide angle range on the front side of the screen 21e.

FIG. 7B shows external light from above. The striped black masks 70, 70,... Formed on each scattering reflection film exhibit a louver function with respect to external light from above, and suppress external light by angle separation.
FIG. 7C shows external light from the front direction. The light in the front direction passing through A, A,... In the figure is the light incident on the collector mirror surface 64, and this light is reflected by the collector mirror surface 64, and the angle information is converted into position information. Absorbed by the black mask 70.

Light in the front direction passing through B, B,... In the figure is incident on the scattering mirror surface 64 on the condensing mirror surface 64, but for the light, a striped black mask 70, 70,.・ Suppresses by exhibiting a louver function and absorbing external light.
FIG. 8D shows external light from the bottom but above the image light (projector light), and FIG. 8E shows light from below the image light.
8D and 8E, the light from below passing through A, A,... In the figure is reflected by the condensing mirror surface 64, and the angle information is converted into position information. Is absorbed by.

In addition, the light from below passing through B, B,... In the figure is incident on the scattering reflection surface 66. For the light, the striped black masks 70, 70,. It functions by suppressing it by absorbing external light.
As shown in FIGS. 7A to 7C and FIGS. 8D and 8E, image light can be effectively scattered and reflected in the front direction, and external light in any direction can be obtained. It can be effectively absorbed by the black mask 70, and as a result, the contrast with the background of the image can be improved.

According to such a reflection type front screen 21e, the diffuse reflection film 68 is formed by applying a white paint to each diffusion reflection surface 66 of the substrate (metal foil) 62 made of aluminum or the like and molded into a predetermined shape. By selectively forming the striped black mask 70 on the diffuse reflection film 68, it is possible to form the mask with a cheap material at a very low cost.
And according to the present Example 21e, by the one-dimensional condensing function of each condensing mirror surface 64, 64, ..., striped black mask 70 rather than Example 21a, 21b shown in FIG. 1, FIG. The ratio of the width of the non-mask portion 72 to the width of the non-mask portion can be reduced, the width of the non-mask portion can be reduced, and the contrast with respect to the background of the image can be further increased.

Each of the diffuse reflection surfaces 66, 66,... Of the substrate (metal foil) 62 made of aluminum has scattering reflectivity when appropriately roughened. Therefore, the diffuse reflection surfaces 66, 66,... Are directly exposed to the non-mask portions 72, 72,... Without forming the diffuse reflection films 68, 68,. The image light condensed at 64, 64,... May be directly scattered and reflected on each of the diffuse reflection surfaces 66, 66,.
However, the scattered and reflected light has a metallic luster and may deteriorate the quality of the image, and the image quality may be slightly inferior to the case of Example 21e shown in FIG.

FIG. 9 is a perspective view showing a sixth embodiment (Example 6) of the reflective front screen according to the present invention, with a part cut away.
21f is a reflection type front screen of the present embodiment, and this embodiment 21f is different from the reflection type front screen 21e shown in FIG. 6 in that the collecting mirror surfaces 64, 64,. ) Not only has a one-dimensional condensing function, but also has a condensing function in the horizontal direction (horizontal direction) perpendicular to that direction, and as a result, the black mask has a pinhole shape instead of a stripe shape It differs only in that it forms 74, and is otherwise the same. Reference numeral 76 denotes a pinhole-shaped non-mask portion.

  According to the present Example 21f, it can be manufactured at a low price similar to that of the Example 21e, and the two-dimensional collection is performed by the condensing mirror surface 64 having a two-dimensional condensing function in a direction perpendicular to each other. Since the light is reflected, the area ratio between the black mask 74 and the non-mask portions 72, 72,... Can be made larger than that in Example 21e, and therefore the contrast with the background of the image is stronger than that in Example 21e. it can.

FIG. 10 is a perspective view showing a seventh embodiment (Example 7) of the reflective front screen according to the present invention, with a part cut away.
21g shows a present Example and this Example 21g is completely different from the first to sixth Examples 21a to 21f in that the lenticular lens sheet 102 is used as a main member.

The lenticular lens 102 is made of a transparent resin, for example, acrylic resin, and has a plurality of cylindrical surface lens elements 104 extending in the horizontal direction (horizontal direction) with a radius r and arranged in the vertical direction (vertical direction). The thickness T is expressed by the following equation.
T≈r + f (θ1) cos θ1
Note that θ1 is the angle of image light from the projector located obliquely below the normal line extending horizontally in front of the screen.
And the thickness T is smaller than 3r.
That is, T≈r + f (θ1) cos θ1 <3r.

106, 106,... Are stripe-shaped black masks formed on the bottom surface of the lenticular lens 102, and 108, 108,... Exist between 106, 106, 106, 106,. This is a non-masked striped portion that is positioned where image light (angle θ1) from the projector is condensed by each lens element 104.
110 is a white paper which is a scattering reflection means for scattering and reflecting light, and is formed on the bottom surface of the lenticular lens 102 having the black masks 106, 106,. Has been. The surface of the blank paper 110 is exposed to the non-mask portions 108, 108,.

Reference numeral 112 denotes a base made of, for example, aluminum, which is fixed to the bottom surface of the blank paper 110, and serves to secure the strength of the reflective front screen 21g and to reflect image light that attempts to pass through the blank paper 110 to increase the use efficiency of the image light. Fulfill.
In the following, the process of obtaining the idea of creating a reflective front screen mainly using a lenticular lens (or fly-eye lens) will be described, and the principle of this embodiment will be described.
FIG. 11 shows a case where a general lenticular lens (or a fly-eye lens may be used. However, it is not repeated hereinafter that a fly-eye lens may be used) 101 is used as a front screen. The thickness of the general lenticular lens 101 is set to the focal length f of the lens elements 103, 103,.

When such a lenticular lens 101 is used, image light from the projector 120 is reflected even if it enters the lens elements 103, 103,... And is condensed on the non-mask portions 108, 108,. Since the light passes through the lens elements 103, 103,... Again, it becomes parallel light and returns to the projector 120 side. That is, it does not diffuse. Light entering the adjacent lens element 103 also becomes parallel light and does not diffuse.
Therefore, the diffusion angle does not widen and does not function as a screen.
Therefore, it has been considered that the lenticular lens 101 cannot be used for a reflective front screen.

  However, if the thickness of the lens is significantly shorter than the spherical lens focal length 3r, the inventor of the present application generates strong spherical aberration for large-angle incident light (incident light having a large angle with respect to the ray) and is scattered and reflected. This example was devised with the idea that it could not be parallel light, diffused, and could function as a reflective front screen because it would not pass through the lens element that passed through and another lens element. did.

FIG. 12 is a diagram for explaining the principle of this embodiment 21g.
Reference numeral 122 denotes a lens element having a convex curved surface (convex spherical surface in the case of a fly-eye lens) having a radius r, which is made of, for example, an acrylic resin and has a refractive index nr of 1.5. Incidentally, the refractive index na of air is 1.0.
f is a focal length of each lens element 122 having a convex curved surface, and attention is paid to a light ray R incident on a certain point p on the surface of the lens element 122 in parallel with the optical axis.

If the angle of the incident light ray R with respect to the normal of the line perpendicular to the tangent to the point p is θ1, the following equation 1 is established.
nasin θ1 = nrsin θ2 Equation 1
Θ2 is an angle of a portion of the light ray R passing through the lens element 122 with respect to a line connecting the point p and the center o of the lens element 122.
When 1.0 is substituted for the refractive index na of air in the above formula and 1.5 is substituted for the refractive index nr of the acrylic resin, the following formula 2 is established.
1.0 sin θ1 = 1.5 sin θ2 Equation 2

Next, when the angle of the light ray R with respect to the optical axis of the lens element 122 is θ3, the following Expression 3 is established.
r / sin θ3 = f / sin θ2 Equation 3
It should be noted that a triangular shape connecting the center o of the sphere, the point p, and a point q (a point away from the center o by a focal length f: focal point) q where the light ray R incident on the lens element 122 parallel to the optical axis crosses the optical axis. As is apparent from the figure, θ1 = θ2 + θ3 holds.

From the above equation 2, sin θ2 = 1.0 sin θ1 / 1.5 is established.
Further, the following expression 4 is established from the above expression 3 and θ1 = θ2 + θ3.
f (θ1) = sin θ2 · r / sin θ3 = 1.0 · sin θ1 · r / 1.5 · sin θ3
= R · sin θ1 / 1.5 · sin (θ1-θ2) Equation 4
From the above equation, θ2, 1 / sin (θ1−θ2), and focal length f (θ1) when θ1 is changed every 10 ° from 10 ° to 90 ° (including the case where θ1 = 45 °) are obtained. Shown in Table 1 below.

As is apparent from Table 1 above, the focal length f (θ1) is 1.9799r and about 2r when θ1 is 10 °, and 1.044r and about 1r when 80 °.
That is, the focal length f (θ1) changes in the range of 1r to 2r due to spherical aberration.
Accordingly, when θ1 is a large angle such as 80 °, for example, a light beam that has passed through a certain lens element 122a is incident on a focal position and is scattered and reflected there as shown in FIG. It passes through the element 122c and does not become parallel light but diffuses within an angle of ± θ5.

Therefore, as shown in FIG. 14, when the thickness T of the lenticular lens is significantly smaller than r + f (θ1) cos θ1 and 3r, the light incident at a large angle and scattered and reflected at the focal position becomes parallel light in the front direction. Since it does not scatter, it can function as a front screen.
Furthermore, light incident at a large angle is not completely collected at a single focal position due to spherical aberration, and the condensing position is widened and has a size, so that angular diffusion between the lens elements 104 and 104 occurs.
Therefore, the problem that light incident on the lens is condensed through the incident lens element 103 and becomes parallel light even when the light incident on the lens is scattered and reflected as in the case of using a lenticular lens as shown in FIG. 11 is avoided. It can be used sufficiently as a reflection type front screen, and this is the embodiment 21g shown in FIG.

FIG. 15 is a perspective view of a reflective front screen according to the eighth embodiment (Embodiment 8) 21h of the present invention, with a part cut away.
This Example (Example 8) 21h differs from the Example 21g shown in FIG. 10 in that the fly-eye lens 103 is basically used in place of the lenticular lens (102), so that the vertical direction (vertical direction) is obtained. The point of difference is that not only the condensing of light but also the light condensing in the horizontal direction (horizontal direction) is performed.
Reference numerals 105, 105,... Denote fly eye lens elements constituting the fly eye lens 103.

The reason why the fly-eye lens 103 is used in this way is to make the area ratio of the black mask and the non-mask portion larger than that of the embodiment 21g and to increase the contrast with the background of the image. Of course, there is a difference that the black mask is not a stripe type but a pinhole type. However, there is no difference in other points.
107 is a black mask, 109, 109,... Is a pinhole type non-mask part, and the surface of the white paper 110 that is a scattering reflection means, for example, is exposed to the non-mask part 109, 109,. The light incident on is scattered and reflected. Reference numeral 112 denotes a base made of, for example, aluminum.

FIG. 16 is a sectional view showing a ninth embodiment (Example 9) 21i of the reflective front screen of the present invention.
First, the significance of this example (Example 9) will be described. The above embodiments 7 and 8 can function effectively in the case of large angle incidence, but in the case of a projector having a projection angle in the range from low angle incidence to large angle incidence, diffusion is performed on the low angle side. There is no danger that the light will be close to parallel light and the viewing angle will be very narrow on the low angle side.

This is because even in the case of a wide-angle short-focus projector that has been developed in recent years, the projection angle is about 20 ° to 60 °, and projectors that use only large-angle incidence are limited. For this reason, in order to cope with projectors that are already in widespread use, a front screen that can take measures against external light is desirable even for projections from low angles to large angles.
Therefore, the ninth embodiment 21i is a form obtained by further evolving the seventh and eighth embodiments 21g and 21h. In addition, a tenth embodiment 21j and an eleventh embodiment 21k, which will be described later, are forms in which the seventh and eighth embodiments 21g and 21h are further evolved like the ninth embodiment 21i.

This Example 21i is the same as Example 7.8 in that it has the idea of converting angle information into position information by using a lenticular lens or a fly-eye lens, and taking measures against external light. It is fundamentally different that a diffusing film of a transparent angle region and a diffusing angle region is installed in the vicinity of the lens principal plane of a lenticular lens or fly-eye lens so that it can be used in a reflective front screen.
The configuration of the present Example 21i will be described with reference to FIG. In the figure, reference numeral 130 denotes a base made of, for example, aluminum, and 132 denotes a surface of the base 130, which has a sawtooth reflector shape, a reflective Fresnel lens shape, or a reflective cylindrical Fresnel lens shape.

134, 134,... Are stripe-type black masks that are formed so as to mask except for a portion corresponding to the focal point of each lens element of a lenticular lens sheet (136) described below. That is, the surface 132 of the base 130 is exposed at a portion corresponding to the focal point of each lens element.
Reference numeral 136 denotes a lenticular lens sheet whose back surface is bonded to the surface of the base 130 (including the portion where the black masks 134, 134,... Are formed), and the focal length thereof is f. The lens element forming surface is the surface, and the light incident on each lens element in parallel with the optical axis is condensed on the exposed surface 132 of the base 130.

138 is a transparent optical adhesive (refractive index is 1.4), and a diffusion (DLC) film 140 is adhered to the lens element forming surface of the lenticular lens sheet 136 via the adhesive 138. The focal length f of the lenticular lens sheet 136 is a focal length determined by two refractive index differences between a 136 refractive index acrylic and a transparent optical adhesive having a refractive index of 1.4 and a lens shape. The diffusion film 140 has a transparent angle region and a diffusion angle region. As a specific example, it has a diffusion characteristic independent of the incident angle with respect to the incident light in the range of the incident angle + 15 ° to −15 °, and is transparent with respect to the incident light outside the range.
Next, the principle of Example 21i will be described. Projector light R from a floor-mounted or desk-mounted projector (not shown) enters the screen 21i from an obliquely lower front side. The incident angle of this projector light is in the transparent angle region of the diffusion film 140 installed in the vicinity of the lens main plane, and the projector light R does not diffuse at all in the diffusion film 140 and goes straight in the same way as it passes through the glass plate. .

In this state, the projector light R that has reached the surface of the lenticular lens 136 (a fly-eye lens may be used. Hereinafter, this will not be repeatedly described) is focused on each lens element of the lenticular lens 136. Focused on the position. Since there is no black mask at each focal position, the direction is changed and the light is scattered and reflected by the reflecting surfaces 132, 132,... At the focal position.
As described above, the reflecting surfaces 132, 132,... Are a sawtooth reflector having scattering reflectivity, a reflective Fresnel lens having scattering reflectivity, or a reflective silndral Fresnel having scattering reflectivity. The lens shape. Therefore, the diffusion principal ray direction is directed to the screen normal direction.

When the light diffused by the reflecting surfaces 132, 132,... At the respective focal positions is incident on the lenticular lens 136 (or fly-eye lens) again, the reflection direction changes so much in the case of low angle incidence. Because it is not, it should return to almost parallel light.
However, in the case of the ninth embodiment 21i (the same applies to the case of the tenth embodiment 21j and the eleventh embodiment 21k described later), as shown in FIG. Since it passes through the diffusion angle region of the diffusion film 140 installed in the vicinity of the lens main plane of the fly eye lens (or fly-eye lens), it is diffused firmly and image display can be performed without problems.

In this embodiment (i.e., ninth embodiment) 21i shown in FIG. 16, a diffused light control film (DLC-film) (Japanese Patent Laid-Open No. 2006-84563 or KG170001) is used as the diffusion film 140 having the transparent region and the diffusion angle region. -The film described in US is used. A film with similar characteristics is Sumitomo Chemical's “Lumisty”.
Typical examples of the diffusion angle range of the diffusion film described above are those of ± 15 ° up and down and ± 25 °. Except this diffusion angle, it becomes transparent like glass. As a modified version of this film, there is a film that has a diffusion angle region in the range of + 5 ° to −45 °. By laminating, a diffusion angle region of ± 45 ° can be realized. Also, other variations can be used. Now, although it is external light, the black mask is firmly installed on the reflective surface, so the black mask absorbs both external light entering from the transparent angle region and external light entering from the diffusion angle. So you can achieve very good contrast in the light.
As the diffusion film having the transparent angle region and the diffusion angle region, a DLC film is specifically used. However, since only one longitudinal diffusion is required, it is much cheaper than the conventional screen shown in FIG.

According to the configuration of the ninth example 21i shown in FIG. 16, it can be seen that all the functions of the rear projection TV known as the configuration of Fresnel lens + lenticular lens + black mask + diffusion film can be realized.
There is no other example of a reflective front screen that can realize all the functions of the rear projection system, and very excellent characteristics can be expected.

FIG. 17 is a sectional view showing a tenth embodiment (Example 10) 21j of the reflective front screen of the present invention.
In Example 21j, a diffusion film 140 having a transparent region and a diffusion angle region is installed in the vicinity of the main plane (lens element forming surface) inside the lenticular lens sheet 136 (or fly-eye lens). In addition, it is good to name this screen as a wrench with BM and a DLC front screen. Incidentally, BM indicates a black mask.

Here, the external light suppression function of the ninth (and tenth) embodiment 21i (21j) will be described.
FIG. 18 is a cross-sectional view showing an example of the external light suppression function of the screen (9th embodiment) 21i shown in FIG. This outside light suppressing function exhibits a suppressing function against outside light from below the projector light, which is impossible to suppress outside light on the conventional reflective front screen shown in FIG.

This outside light is generated as diffused light from the floor in the vicinity of the projector. For example, diffused light from ceiling illumination light, sunlight from a window (western sun), etc. is reflected by the floor and is incident on the screen. Intrusions from the transparent angle region.
As shown in FIG. 18, it can be seen that the black masks 134, 134,.
FIG. 19 shows the external light suppression function in the case of the conventional type shown in FIG. 25, and is for comparison with the external light suppression function of Example 21i shown in FIG.

In the external light suppression function shown in FIG. 19, since the external light entering from the transparent angle region, which is the incident angle region, has no suppression function at all, the direction is changed by the sawtooth reflecting surface. It can be seen that external light penetrates into the diffusion angle region and diffuses into the observation angle region, so that the contrast is significantly reduced.
On the other hand, the BM-equipped wrench / DLC front screen 21i (21j) of the ninth and tenth embodiments of the present invention not only functions to suppress external light from the transparent angle region but also to external light from the diffusion angle region. On the other hand, since the black mask on the reflecting surface absorbs external light, the external light can be suppressed without any problem no matter how wide the diffusion angle region is.

FIG. 20 is a diagram showing that a function of suppressing external light from the diffusion angle region is also provided. That is, as shown in FIG. 20, the outside light from the diffusion angle region can be absorbed by the black masks 134, 134,... Having a large occupied area ratio with respect to the screen, and the outside light can be effectively suppressed. . Therefore, the diffusion angle region and the transparent angle region may overlap, and therefore the vertical viewing angle can be widened.
This extraneous light suppression characteristic is that the area of the diffusion angle determines the width of the viewing angle, so that an area where the entire screen can be seen from the vicinity of the screen can be realized, so a conference room, seminar room, classroom, etc. This is an important characteristic for effective use of space.
On the other hand, in the conventional reflection type front screen, since the transparent angle region and the diffusion angle region are merely folded back by the sawtooth reflector, if the diffusion angle region is increased, an overlap always occurs due to mirror symmetry. Since a part of the external light from the diffusion angle region enters the diffusion angle region again, in principle, a wide vertical viewing angle cannot be taken. Therefore, it is impossible to realize the screen characteristics of the ninth and tenth embodiments 21i and 21j of the present invention. From this, it can be seen that the characteristics of the ninth example 21i and the tenth example 21j shown in FIGS. 16 and 17 are superior.

FIG. 21 shows an example of the usage environment of a ceiling-mounted projector to which the BM-equipped wrench / DLC front screen of the ninth embodiment 21i and the tenth embodiment 21j is applied.
When a ceiling-mounted projector is used as the projector 150, since the ceiling illuminations 152, 152,... Exist between the screen and the ceiling-mounted projector in the projector that is generally spread, this light is Contrast is greatly deteriorated. It is indispensable to suppress external light from above the ceiling-mounted projector light (corresponding to external light from below the projector light in the case of a floor-mounted projector). In particular, when the screen is a large screen, the screen is installed on the upper side from a position higher than the desk, so the upper end of the screen is near the ceiling.

  Therefore, at the upper end of the screen 21i, the light beam from the ceiling-mounted projector is in the vicinity of the low angle vertical incidence, and therefore the ceiling-mounted projector must be separated from the screen by the projection distance. Therefore, in the case of a large screen, a considerable number of ceiling lights 152, 152,... Exist between the ceiling installed projector 150 and the screen 21i (or 21j). When the ceiling-mounted projector 150 is installed in the back of the room, all of the ceiling lights 152, 152,... In the room cause a decrease in contrast.

Furthermore, since the light from the ceiling-mounted projector enters from the vicinity of the screen normal direction at the upper end portion of the screen, it is indispensable that the function of suppressing external light can be exhibited even at a low angle. This is possible only with the wrench and DLC front screen 21i, 21j with BM of the present invention.
FIG. 22 is a cross-sectional view showing an example of suppressing external light from above the projector light in the ninth example 21i. As is clear from this figure, since the external light from above the projector light is absorbed by the black masks 134, 134,... Of the reflecting surface 132, no matter how wide the diffusion angle region is, there is no problem. External light can be suppressed.

  FIG. 23 shows an example in which it is impossible to suppress external light from above the projector light when the conventional reflective front screen is used in an environment where a ceiling-mounted projector is used. In this case, as is apparent from FIG. 23, external light from above the projector light is reflected on the surface side in each mirror forming region and viewed by the viewer. Compared with the case of the external light suppression example of the ninth embodiment 21i (and the tenth embodiment 21j) of the present invention shown in FIG. 22, it is clear that the external light suppression effect is significantly inferior in the case of the conventional type. It is.

FIG. 24 is a sectional view showing an eleventh embodiment (embodiment 11) 21k of the reflective front screen of the present invention.
The present Example 21k makes the surface of the base 130 a flat surface 132p, that is, eliminates the need for a saw-tooth shape of a reflector, thereby facilitating the manufacture of the base 130.
This embodiment 21k is different from the ninth embodiment 21i shown in FIG. 16 in that, first, as the base 130, the surface 132p has a surface shape for lateral diffusion, and a sawtooth surface shape in the vertical direction. It is different in that it does not have. Therefore, the base 130 is easier to manufacture than the ninth embodiment 21i.

Secondly, the present Example 21k is different from the ninth Example 21i shown in FIG. 16 in that the diffusion angle area is shifted downward from the screen normal direction as the diffusion film 140a. Yes. Specifically, for example, a material having diffusion characteristics that do not depend on the incident angle in the range of + 5 ° to −45 ° is used. Of course, it has the characteristic of being transparent to light other than that angle.
The significance of existence of the eleventh embodiment 21k is described as follows.
FIG. 21 shows the usage environment of the BM-equipped wrench and DLC front screen for ceiling-mounted projectors. Under such an environment, no one can observe from a position higher than the screen.
Therefore, it is useless to diffuse upward on the screen. Therefore, by setting the diffusion principal ray direction slightly below the screen normal direction, the screen configuration is obtained by removing the sawtooth shape from the shape of the reflecting surface 132p.

That is, since the ceiling-mounted projector 150 projects projector light (image light) from the ceiling, image light enters from above the screen 21j. Therefore, since there is an observer below the screen in the regular reflection direction, there is no need to change the reflection direction, and the diffusion angle region of the diffusion film having the transparent angle region and the diffusion angle region is shifted downward from the normal direction of the screen. The image is displayed to the viewer using the diffusion film 140a.
The film to be used is a film having a diffusion angle region of + 5 ° to −45 °. Except this angle, it is transparent like glass. The projector light can be incident from a low angle incident just 5 ° above the normal direction of the screen, and the position of the upper end of the screen can be set up to the vicinity of the ceiling. Therefore, it is possible to view a large screen display with high contrast even in a lighted state. In addition, since the vertical viewing angle is 50 °, the entire screen can be seen from the front of the room, and the room space can be used effectively.

  The unidirectionality of the diffusion characteristics in the diffusion films 140 and 140a and the reflecting surface 132 of the ninth example 21i, the tenth example 21j, and the eleventh example 21k is an anisotropic one. The diffusion direction of the diffusion film having the transparent angle region and the diffusion angle region realizes diffusion only in the vertical direction, and diffusion on the reflecting surface realizes diffusion only in the horizontal direction. This is also the embodiment described in claim 11.

Although not shown, the reflective front screen of the present invention can also be used for stereoscopic display. One embodiment used for stereoscopic display as such is the twelfth embodiment (Example 12) of the present invention, and the embodiment will be described below.
When the reflective front screen retains polarization characteristics, the right-eye image and the left-eye image are assigned to vertical linearly polarized light, horizontal linearly polarized light, right circularly polarized light, and left circularly polarized light, and are visually recognized using polarized glasses.

Specular shape scattering by metal has the property of maintaining the polarization of light, and polarization cannot be maintained in the case of total reflection, diffusion in white paint, and paper. Therefore, when it is designed only by metal reflection, stereoscopic display using polarized light is possible. When surface-shaped metal reflection is used for the reflecting surface of the screen according to claims 8 and 9, polarization can be maintained.
In addition, the diffusion films 140 and 140a having the transparent angle region and the diffusion angle region used in the ninth to eleventh examples 21i, 21j, and 21k retain the polarized light even though they are transmissive diffusion films. The wrench / DLC front screen with BM of the present invention according to claims 10 and 11 is a polarization-maintaining reflective front screen, so that stereoscopic display using polarized light is possible. .

  It is to be noted that the right-eye image and the left-eye image are displayed in a time-sharing manner at high speed using the screen according to claims 1 to 11, and a high-contrast three-dimensional display is performed even in a bright place by using shutter glasses synchronized therewith. Is possible.

  INDUSTRIAL APPLICABILITY The present invention has wide industrial applicability to a reflective front screen used in a front projection type display device, and further uses a reflective front screen to display a stereoscopic display image (third order) in a high contrast image display in a bright place. A stereoscopic display system that can visually recognize an original image has industrial applicability.

21a to 21k ... reflective type front screen of each embodiment,
22 ... Total reflection prism sheet,
24 ... Prism element of total reflection prism sheet, t ... Incident surface u ... Total reflection surface, v ... Roughened portion of total reflection surface,
26. Light absorbing film for preventing hot spots and hot lines,
28 ... Black mask (black stripe type),
30 ... non-mask part,
32 ... scattering reflection means (white paper or white paint, etc.),
34 ... surface of the scattering reflection means (scattering reflection surface),
40: Transverse reflection element for hot line prevention,
42 ... concave surface reflecting image light,
44 ... Black mask (pinhole type), 46 ... Non-mask part,
62 ... Substrate (metal such as aluminum or resin film)
66... Scattering reflection surface of substrate,
68: Scattering diffuse reflection means (for example, white paint),
70 ... Black mask (stripe type), 72 ... Non-mask part,
74 ... Black mask (pinhole type),
102 ... Lenticular lens, 103 ... Fly eye lens,
104 ... Lenticular lens element, 105 ... Fly eye lens element,
106 ... Black mask (stripe type),
107 ... Black mask (pinhole type),
108, 109 ... non-mask part,
110 ... scattering reflection means (for example, white paper),
120 ... projector 122 ... spherical (cylindrical) lens elements 122a, 122c ... lenticular lens element 130 ... base (for example, made of aluminum),
132, 132p ... Surface of base (reflection surface)
134 ... Black stripe or pinhole type black mask 136 ... Lenticular lens sheet,
138 ... Transparent optical adhesive 140, 140a with a refractive index of 1.4, ... Diffusion film having a transparent angle region and a diffusion angle region,
150... Projector, 152.

Claims (14)

Each prism element is made of a transparent material having a refractive index n, in which a plurality of prism elements each having an incident surface and a total reflection surface on the incident side and having an apex angle θ are arranged in the vertical direction, and the exit side is an exit surface having no surface shape. A total reflection prism sheet whose apex angle θ is set to sin-1 (1 / n) or more;
A black mask disposed on the exit surface of the total reflection prism sheet except for a position where the light incident on the incident surface of each prism element and totally reflected by the total reflection surface is not blocked;
The scattering reflection means disposed on the exit surface of the total reflection prism sheet,
A reflective front screen characterized by comprising: The reflective front screen of claim 1,
The prism element incident angle and total reflection surface are rotated while keeping the apex angle of the prism element substantially constant so that the incident light beam is substantially perpendicular to the incident surface of the prism element according to the change in the incident angle of the incident light. Reflective front screen. The reflective front screen according to claim 1 or 2,
A reflection type front screen characterized in that a linear hot spot / hot line preventing light absorbing film is formed at the apex corner of each prism element. The reflective front screen according to claim 1 or 2,
A reflection-type front screen, wherein an uneven surface or a moth-eye structure is formed on the incident surface of each prism element apex portion. The reflective front screen according to claim 1, 2, 3, or 4,
One of the incident surface and total reflection surface of each prism element, or both surfaces have a one-dimensional condensing function. The reflection type front screen characterized by the above-mentioned. The reflective front screen according to claim 1, 2, 3, or 4,
A cylindrical refractive lens in which the incident surface of each prism element has a one-dimensional condensing function,
The total reflection surface of each prism element is a total reflection type cylindrical concave mirror having a one-dimensional condensing function,
The condensing direction of the one-dimensional condensing function of the incident surface and the condensing direction of the one-dimensional condensing function of the total reflection surface are substantially orthogonal to each other,
Reflection characterized in that it is a pinhole type black mask in which the light condensing position of the black mask provided on the exit surface having no surface shape reflected by the total reflection surface of each prism element becomes a pinhole Type front screen. The reflective front screen according to claim 1, 2, 3, or 4,
Either one or both of the incident surface and the total reflection surface of each prism element have a two-dimensional condensing function,
Reflective front characterized in that the black mask provided on the exit surface with no surface shape is a pinhole type black mask where the condensing position of the light reflected by the total reflection surface of each prism element becomes a pinhole screen. A mirror assembly having a plurality of mirror surfaces of a concave mirror with a metal reflection or total reflection tilt having a one-dimensional light collecting function or a two-dimensional light collecting function;
On the inclined surface where the diffuse principal ray direction is substantially the normal direction of the reflective screen, it has scattering reflection means having a diffusion function at each focal position,
A reflective front screen characterized in that a black mask having a light absorption function is provided in a portion other than the focal position. It has a scattering reflection means having a scattering reflection function at a substantially condensing position of large-angle incident light of a lenticular lens sheet having a one-dimensional condensing function or a fly-eye lens having a two-dimensional condensing function,
A reflection type front screen, wherein a black mask having a light absorption function is provided in a portion other than the focal position on the emission side of the scattering reflection means. The reflective front screen according to claim 8 or 9,
A reflection-type front screen characterized in that as a scattering reflection means, a surface to be reflected is subjected to surface-shaped metal reflection so as to be polarized and diffused. Whether a lenticular lens sheet having a one-dimensional condensing function or a fly-eye lens having a two-dimensional condensing function has a scattering / reflecting means having a scattering / reflecting function at a substantially condensing position of low-angle incident light to large-angle incident light. Alternatively, in addition to this diffusing means, it has a scattering reflecting means to which a sawtooth reflecting surface structure for directing the diffusion principal ray direction to the screen normal direction is added,
A portion other than the focal position on the exit side of the scattering reflection means is provided with a black mask having a light absorption function, and in the vicinity of the main plane of the lenticular lens or fly-eye lens, on the screen surface, just inside, A reflection type front screen comprising a diffusion film having a transparent angle region and a diffusion angle region. The reflective front screen according to claim 11,
The scattering reflection means at the focal position has an anisotropic scattering reflection characteristic in almost one direction and diffuses with a transparent angle region on the surface or just inside the main plane of the lenticular lens or fly-eye lens. A reflection type front screen characterized in that the diffusion characteristic of a diffusion film having an angular region is an anisotropic diffusion characteristic in almost one direction. Using the reflective front screen according to claim 9, claim 11 or claim 12,
A polarization maintaining diffusion function is realized by combining polarization maintaining characteristics of a diffusion film having a transparent angle region and a diffusion angle region and polarization maintaining diffusion by surface shape metal reflection on the reflecting surface, and the right eye image and the left eye image are orthogonal to each other. A three-dimensional display system characterized by assigning two linearly polarized lights, or assigning right circularly polarized light and left circularly polarized light, and using (circle) polarized glasses. Using the reflective front screen according to any one of claims 1 to 12,
A three-dimensional display system characterized in that a right-eye image and a left-eye image are displayed in a time-sharing manner at high speed, and high-contrast stereoscopic display is performed even in a bright place by using shutter glasses that synchronize with this.

Images