JP2002277965A - Optical screen unit and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device, etc., wherein stripes caused by joint lines are prevented from being observed to the utmost in an image projected on an optical sheet with the joint lines. SOLUTION: As for the image forming device including the optical sheet 21 which is formed by mutually joining more than one sheet members 21b and 21c through the joint line 21a and an image projecting device 1 for forming an image and projecting the image toward the optical sheet 21 by a projecting optical system 20, the reflection of light and the diffusion of light at the joint line 21a are suppressed to a minimum by setting the relative positional relation between the image projecting device 1 and the optical sheet 21 so that the optical axis O of the projection optical system 20 for the image projecting device 1 vertically crosses the joint line 21a of the optical sheet 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical screen unit and an image forming apparatus, and more particularly, to an optical screen unit and an image forming apparatus configured to project an image on a main surface.

[0002]

2. Description of the Related Art Various types of optical screen units in which an image is projected from an image projection apparatus onto a main surface have been proposed.

As such an optical screen unit, for example, Japanese Patent Application Laid-Open No. 7-43835 discloses a transmission type projection screen in which a plurality of screen sheets are arranged in a plane direction of an image projection plane. By providing holding means for restricting the joint portion so as not to be movable in a direction substantially orthogonal to the joint portion and movably holding the joint portion in a direction substantially parallel to the joint portion,
There is described a transmission type projection screen in which the displacement of a joint portion is reduced.

The transmission type projection screen further includes a biasing means for biasing the screen sheet itself in a plane direction at an ineffective portion of the peripheral portion of the screen sheet where an image is not projected, so as to warp or bend. It has been devised to eliminate the problem.

In such an optical screen unit, in order to efficiently guide projected light to an observer, the surface shape of the screen is variously devised. For example, a screen in which a large number of beads are arranged in a plane is used. , A lens formed with a Fresnel lens, and a lens using a lenticular sheet. Further, in addition to any of these, it is common to arrange an optical member having a diffusion surface for widening the viewing angle.

By the way, in a multi-projector apparatus or the like that forms a single image on a screen by projecting a plurality of partial images from a plurality of arranged image projection apparatuses, the image is not observed when viewed from the front by an observer. The joint between the partial images may be observed when viewed from an oblique direction. However, the optical screen unit having the devised shape described above is also useful for alleviating this problem.

[0007]

However, in spite of this, an image projection apparatus arranged without any contrivance on an optical screen having a joint (joining line) as described in the above-mentioned Japanese Patent Application Laid-Open No. 7-43835. When an image is projected, the seam may be observed as a streak in the displayed image, which has been a cause of lowering the image quality.

Also, among the above-mentioned optical screen units, in the case of a lenticular sheet, for example, in order to obtain a two-dimensional effect, it is necessary to superimpose a two-way lenticular sheet. In order to sharply display an image formed on the lenticular sheet without blurring, the lenticular sheet needs to be in close contact with the above-described optical member having a diffusion surface.

Thus, there is a need for a technique for bringing an optical sheet such as a lenticular sheet into close contact with an optical member such as an optical plate having a diffusing surface without causing looseness or distortion.

The present invention has been made in view of the above circumstances, and is an optical screen unit capable of adhering an optical sheet to an optical plate so as not to impair the sharpness of an image formed on the optical sheet. It is intended to provide.

Another object of the present invention is to provide an image forming apparatus in which streaks caused by the joining line are not observed as much as possible on the image projected on the optical sheet having the joining line.

[0012]

In order to achieve the above-mentioned object, an image forming apparatus according to a first aspect of the present invention includes a plurality of sheet members joined to each other by using the edges of the sheet members as joining lines. An optical sheet configured with the above joining line, and an image or a part of an image are generated and projected onto the optical sheet by a projection optical system, and the joining lines are mutually formed on the optical sheet. When not intersecting, at least the number of the joining lines or more, when the joining lines intersect each other with nodes on the optical sheet, an image projection device provided with at least the number of nodes, In the first case where only one nodal point exists in the range of the optical sheet corresponding to the image or a part of the image projected by the image projecting apparatus, the image projecting apparatus has no nodal point and one In the second case only the joining line is present,
In the third case where there is no joining line, the optical axis of the projection optical system is disposed so as to match any one of the following two conditions. Intersect at the nodal point so as to coincide with the established normal,
In this case, the projection optical system is arranged so that the optical axis intersects with the joining line at an intersection and is in a plane including the normal and the joining line set on the main surface at the intersection. .

An image forming apparatus according to a second aspect of the present invention includes:
In the image forming apparatus according to the first aspect of the present invention, all of the nodes are four joining lines orthogonal to each other in a cross shape, or T
It is constituted by any one of three joining lines orthogonal to the shape of a letter.

Further, an image forming apparatus according to a third aspect of the present invention is the image forming apparatus according to the first aspect, wherein the joining lines are parallel to each other.

An image forming apparatus according to a fourth aspect of the present invention forms an approximately planar shape having one joining line by joining two sheet members to each other with an edge of the sheet member as a joining line. An optical sheet, comprising a plurality of image projection devices that generate a part of an image and project toward the optical sheet by a projection optical system, wherein the plurality of image projection devices are
The joining line and a normal line erected on the main surface of the optical sheet,
Are arranged in such a manner that the respective optical axes are located in a plane including.

An image forming apparatus according to a fifth aspect of the present invention has two or more joining lines parallel to each other by joining three or more sheet members to each other with the edges of the sheet members as joining lines. An optical sheet having a substantially planar shape and a part of an image generated and projected onto the optical sheet by a projection optical system. One or more of the two or more joint lines correspond to each of the two or more joint lines. And a plurality of image projection devices provided to perform the above, the image projection device, the corresponding bonding line, and a normal line on the main surface of the optical sheet,
Are disposed such that the optical axis is located in a plane including

According to a sixth aspect of the present invention, in the image forming apparatus, a plurality of sheet members are joined to each other with an edge of the sheet member as a joining line, thereby forming a plurality of joining lines and one or more nodes where the joining lines intersect each other. An optical sheet having a substantially planar shape configured to have a part of an image and projected onto the optical sheet by a projection optical system, and for each of the one or more nodes, And at least one image projection device provided so as to correspond to one of the optical sheets, wherein the image projection device corresponding to the nodal point has an optical axis of the projection optical system at the nodal point of the optical sheet. It is arranged so that it intersects with the normal line on the main surface.

An image forming apparatus according to a seventh aspect of the present invention is the image forming apparatus according to the sixth aspect, wherein one or more image projecting apparatuses provided so as to correspond to the joining lines at portions other than the nodes. The image projection apparatus further includes a joint line corresponding to a portion other than the node, wherein the optical axis of the projection optical system is a normal set on the main surface of the optical sheet at the joint line, and the joint line And are disposed in a plane including

An image forming apparatus according to an eighth aspect of the present invention includes an optical sheet including a unique portion having specific optical characteristics, and an image projecting device for projecting an image toward the optical sheet by a projection optical system. , The image projection device, under a constraint condition relating to a predetermined positional relationship to the optical sheet,
It is arranged at a position where the solid angle when viewing the unique portion from the projection optical system is minimized.

An optical screen unit according to a ninth aspect of the present invention is an optical screen unit configured to project an image on a main surface, comprising: a rigid optical plate; It comprises one or more flexible optical sheets arranged, and close contact means for bringing the main surface of the optical plate and the main surface of the optical sheet into close contact with each other.

An optical screen unit according to a tenth aspect of the present invention is the optical screen unit according to the ninth aspect, wherein the optical plate is formed so as to be curved such that a main surface facing the optical sheet has a convex surface. It is a thing.

An optical screen unit according to an eleventh aspect is the optical screen unit according to the tenth aspect, wherein the convex surface is a cylindrical surface.

An optical screen unit according to a twelfth aspect is the optical screen unit according to the tenth aspect, wherein the maximum amount of protrusion of the convex surface when no stress is applied to the optical plate is 2 mm or more and 100 mm or less.

An optical screen unit according to a thirteenth aspect of the present invention is the optical screen unit according to the ninth aspect, further comprising a pulling means for applying a pulling force to the optical sheet at least in a main surface direction.

An optical screen unit according to a fourteenth aspect of the present invention is the optical screen unit according to the tenth aspect, wherein the close contact means applies a tensile force to the optical sheet in a main surface direction and the optical sheet to the optical plate. The optical sheet has tension means for applying a pressing force to the convex surface, and the optical sheet to which the tensile force is applied is brought into close contact with the convex surface of the optical plate by pressing.

An optical screen unit according to a fifteenth aspect of the present invention is the optical screen unit according to the fourteenth aspect, further comprising a frame member for supporting the optical plate, and one end of the pulling means is supported by the frame member. And an elastic member having the other end coupled to the optical sheet to generate a tensile force.

An optical screen unit according to a sixteenth aspect is the optical screen unit according to the fifteenth aspect, wherein a plurality of the optical sheets are provided.
Each of the optical sheets is pulled independently by a plurality of elastic members, and is pulled so that the pulling force applied to each optical sheet is in the same direction.

An optical screen unit according to a seventeenth aspect is the optical screen unit according to the fifteenth aspect, wherein a plurality of the optical sheets are provided.
Each of the plurality of elastic members is independently pulled by a plurality of elastic members, and a tensile force applied to a farthest optical sheet located farthest from the optical plate among the plurality of optical sheets is close to the optical plate. Having a component in a direction in which the tensile force applied to at least one of the plurality of optical sheets except for the farthest optical sheet is a component in a direction away from the optical plate. The resultant force of the tensile forces applied to the plurality of optical sheets has a component in a direction approaching the optical plate.

An optical screen unit according to an eighteenth aspect is the optical screen unit according to the fifteenth aspect, wherein the convex surface of the optical plate is a cylindrical surface,
The elastic member pulls the optical sheet in a circumferential direction of a cylindrical surface of the optical plate.

An optical screen unit according to a nineteenth aspect is the optical screen unit according to the fifteenth aspect, wherein the elastic member pulls the optical sheet in a radial direction from the center of the main surface of the optical sheet. is there.

An optical screen unit according to a twentieth aspect of the present invention is the optical screen unit according to the fifteenth aspect, wherein the tension means further includes a tension adjustment means for adjusting a tension by the elastic member.

An optical screen unit according to a twenty-first aspect is the optical screen unit according to the ninth aspect, wherein the optical sheet is formed by joining a plurality of sheet members together at edges. At least one of one or more joining lines formed by joining a plurality of sheet members intersects with the optical axis of a projection optical system of an image projection device that projects onto the optical screen unit. It is configured to be a position.

An optical screen unit according to a twenty-second aspect is the optical screen unit according to the ninth aspect, wherein the optical plate is a diffusion plate, and the optical sheet is provided in plural, and at least two lenticular sheets are provided. Is included.

An optical screen unit according to a twenty-third aspect of the present invention is the optical screen unit according to the twenty-second aspect, wherein the surface of the diffusion plate on the side in contact with the lenticular sheet is formed as a diffusion surface; The anti-glare treatment is applied to the surface on the opposite side.

An optical screen unit according to a twenty-fourth aspect of the present invention is the optical screen unit according to the twenty-second aspect, wherein the surface of the diffusion plate on the side in contact with the lenticular sheet is formed as a diffusion surface; The anti-reflection treatment has been applied to the surface on the opposite side.

[0036]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 24 show an embodiment of the present invention. FIG. 1 is a side view showing a configuration of an optical screen unit on which an image is projected from an image projection device. FIG. FIG. 3 is a perspective view illustrating a configuration of an optical sheet and an optical plate in an optical screen unit on which an image is projected. FIG. 3 is a plan view and a front view illustrating a relationship between a joining line in the optical screen unit and an optical axis of the image projection apparatus. FIG. 4 is an enlarged view showing the configuration of the optical sheet and the optical plate in the stacking direction, FIG. 5 is a front view and a side view showing a first example of a configuration in which the optical sheet is elastically supported on a frame member, and FIG. Is a front view and a side view showing a second example of a configuration in which the optical sheet is elastically supported by the frame member, and FIG. 7 is a third example of a configuration in which the optical sheet is elastically supported by the frame member. FIG. 8 is a front view and a side view showing a modification of the third example shown in FIG. 7, and FIG. 9 is a fourth view showing a configuration in which the optical sheet is elastically supported by a frame member. FIG. 10 is a front view and a side view showing an example, FIG. 10 is an enlarged view from the front side showing a state in which a tension variable mechanism is added to a structure for supporting an optical sheet with elasticity to a frame member, and FIG. FIG. 12 is a cross-sectional view illustrating an internal configuration, FIG. 12 is a perspective view illustrating an image forming apparatus that projects an image from one image projection device onto an optical sheet having one joining line, and FIG. FIG. 14 is a plan view illustrating an image forming apparatus that projects an image from one image projecting apparatus, FIG. 14 is a side view illustrating an image forming apparatus that projects an image from one image projecting apparatus onto an optical sheet having one joining line, and FIG. Joint line and image projection FIG. 16 is an enlarged plan view showing a desirable positional relationship between light rays projected from the apparatus, FIG. 16 is an enlarged plan view showing an undesired positional relationship between a joining line and light rays projected from the image projection apparatus, and FIG. Optical sheet with one joint line 3
FIG. 18 is a perspective view showing an image forming apparatus that projects an image from one image projecting apparatus. FIG.
FIG. 19 is a plan view showing an image forming apparatus that projects an image from one image projecting apparatus. FIG.
FIG. 20 is a side view illustrating an image forming apparatus that projects an image from one image projecting apparatus. FIG. 20 illustrates an image forming apparatus that projects images from nine image projecting apparatuses arranged in a grid on an optical sheet having three parallel joining lines. FIG. 21 is a plan view showing an image forming apparatus that projects images from nine image projectors arranged in a lattice on an optical sheet having three parallel joining lines, and FIG. 22 is a vertical joining line. FIG. 23 is a perspective view showing an image forming apparatus for projecting images from nine image projectors arranged in a grid on an optical sheet 27 having six and four joining lines in the left-right direction. FIG. 24 is a side view showing an image forming apparatus for projecting images from nine image projecting apparatuses arranged in a grid on the optical sheet 27 having six and four joining lines in the left-right direction. 6
Optical sheet 27 with four joint lines in the left-right direction
FIG. 7 is a front view showing an arrangement of partial images projected from nine image projectors arranged in a grid.

As shown in FIGS. 1 and 2, the optical screen unit 3 projects an image from the image projection device 1 onto the main surface, and has a rigidity provided on the observer side. Optical plate 7 having the optical plate 7
And two flexible optical sheets 5 and 6 arranged so as to be in close contact with each other along the main surface of the frame member 4.
It is configured to be supported by.

The optical plate 7 is formed of an acrylic plate or the like having a predetermined thickness, and substantially maintains its curved surface even when the optical sheets 5 and 6 are brought into close contact with tension as described later. It has such rigidity that it can be used.

The optical sheets 5 and 6 are, for example, lenticular sheets, and the direction of the lenticular formed on the optical sheet 5 and the direction of the lenticular formed on the optical sheet 6 are orthogonal to each other. Are arranged as follows.

In order to construct the large-screen optical screen unit 3, a large-area lenticular sheet is required. The lenticular sheet is made of a transparent resin material heated and softened, and a lenticular sheet on the peripheral surface. In many cases, a female mold is formed by pressing with a roll-shaped member engraved, and considerable pressure must be applied to form a thin lenticular sheet. Therefore, if an attempt is made to increase the width while maintaining the thinness, the required pressure becomes too large, and the rigidity of the manufacturing apparatus must be extremely increased, which increases the manufacturing cost. Therefore, a technique has been developed in which lenticular sheets having a predetermined width are joined to form a lenticular sheet having a larger area.

For example, the joining line 3a in the optical screen unit 3 shown in FIGS. 3A and 3B is a joining line caused by such a seam of the lenticular sheet, and as shown in FIG. Is the image projection device 1
Are positioned on the optical axis O of the projection optical system.

With this configuration, the joining line 3
Since the light from the image projection apparatus 1 is incident on the light emitting device 1 at a substantially right angle, the joining line 3a can be made less noticeable than when the light is incident obliquely. ing.

In the case of an optical screen formed by joining three or more optical screens, it is desirable that at least one joining line is located on the optical axis O of the projection optical system of the image projection apparatus 1. .

In the case of a multi-projector device that projects a partial image from a plurality of image projection devices, it is sufficient that the joining line is located on the optical axis of the projection optical system of any of the image projection devices. .

The optical plate 7 is configured to be brought into close contact by pressing the optical screens 5 and 6 to which a tensile force has been applied.
It is formed so as to be convex toward 6.

At this time, it is desirable that the convex surface is a curved surface equivalent to a flat two-dimensional space. That is, in the case of a cylindrical surface, for example, which is a curved surface equivalent to a flat two-dimensional space, it is possible to make it coincide with a plane when expanded, but for example, a spherical surface which is equivalent to a curved two-dimensional space. In such a case, even if it is unfolded, it cannot be matched with the plane. For this reason, if a spherical surface or the like is used as the convex surface, bending, distortion, or the like will occur somewhere on the optical screens 5, 6.

Thus, as shown in FIG. 2 and the like, the main surface of the optical plate 7 is formed, for example, as (a part of) a cylindrical surface.

More specifically, when no stress is applied to the optical plate 7, the maximum protrusion H of the main surface which is a convex surface is configured to be 2 mm or more and 100 mm or less. The optimum value is selected according to the screen size and the material of the optical sheet.

The reason for providing the above-mentioned restriction is that if the amount of protrusion is too small, a large tensile force must be applied to bring the optical screens 5 and 6 into close contact, and the frame has sufficient rigidity to support the tensile force. This is because the optical screen unit 3 must be provided on the member 4 and the weight of the optical screen unit 3 increases. On the other hand, if the projection amount is too large, the flatness of the optical screens 5 and 6 is lost.
This is because the screen is observed as a curved screen.

For example, as shown in FIG. 4, the surface of the optical plate 7 facing the optical sheets 5 and 6 of the two surfaces of a substrate 7a made of acrylic or the like is formed as a diffusion surface 7c. On the other side of the observer side,
The optical surface 7b on which anti-glare processing and anti-reflection processing have been performed is formed.

The reason why the optical plate 7 is configured as a diffusion plate in this way is to enable images formed on the optical sheets 5 and 6 to be observed at a wide viewing angle. If the distance between the optical plates 5 and 6 and the optical plate 7 is large, the images formed on the optical sheets 5 and 6 will be blurred.

Next, referring to FIG.
A first example of a configuration for applying a tensile force to the optical plate 7 to make it adhere to the optical plate 7 will be described.

First, the optical plate 7 is fixedly supported on the frame member 4 by an appropriate support structure.

Next, the optical sheets 5 and 6 have, for example, support pieces 11 attached to the four corners thereof.
One end of an elastic member 12 which is a close contact means made of, for example, a tension coil spring and also serves as a tension means is attached to each of the support pieces 11.

The other end of the elastic member 12 is fixed to the four inside corners of the frame member 4 as shown in FIG. 5A, and more specifically, as shown in FIG.
It is attached to the corner on the observer side so that the pressing force is directed to the optical plate 7.

As described above, in the first example, the two optical sheets 5 and 6 are independently pulled by the plurality of elastic members 12 and the tensile force applied to each of the optical sheets 5 and 6 is obtained. Are arranged in the same direction.

With such a configuration, the optical sheets 5, 6
This makes it possible to bring the optical plate 7 into close contact with the optical plate 7 without causing bending or bending.

Subsequently, referring to FIG.
A second example of a configuration for causing the optical plate 6 to adhere to the optical plate 7 by applying a tensile force will be described.

The optical plate 7 is fixedly supported on the frame member 4 by an appropriate support structure as described above.

As shown in FIG. 6A, support pieces 11 are attached to the four corners of the optical sheets 5 and 6, and each of the four support pieces 11 is made of, for example, a tension coil spring. Similarly, one end of the elastic member 12 is attached, and the other end of the elastic member 12 is fixed to four inner corners of the frame member 4.

However, as shown in FIG. 6B, the other end of the elastic member 12 attached to the optical sheet 5 has an angle on the observer side such that the pressing force is directed toward the optical plate 7. The other end of the elastic member 12 attached to the optical sheet 6 is attached to a corner on the image projection device 1 side so that the pressing force is directed to the optical sheet 5. .

Thus, the optical sheet 5 and the optical sheet 6
Although it is possible to further improve the adhesion between the two, the optical sheets 5 and 6 must be in close contact with the optical plate 7 as a result. The force is configured to be larger than the force of the elastic member 12 attached to the optical sheet 6.

Although the two optical sheets 5 and 6 are brought into close contact with the optical plate 7 in this case, more generally, a plurality of optical sheets are brought into close contact with each other. When the tensile force applied to at least one optical sheet except for the farthest optical sheet located farthest from the plate 7 has a component in a direction away from the optical plate 7, The tensile force applied to the distant optical sheet has a component in the direction approaching the optical plate 7, and the resultant force of the tensile forces applied to the plurality of optical sheets is close to the optical plate 7. It is necessary to have a directional component.

Further, referring to FIG.
A third example of a configuration for causing the optical plate 6 to be in close contact with the optical plate 7 by applying a tensile force will be described.

First, the optical plate 7 is fixedly supported on the frame member 4 by an appropriate support structure as described above.

Next, the optical sheets 5 and 6 have, for example, support pieces 11 attached to the center and the four corners of the long sides, and each of the six support pieces 11 is made of, for example, a tension coil spring. One end of the elastic member 12 is attached.

As shown in FIG. 7 (A), the other end of the elastic member 12 is fixed to the center of the long side inside the frame member 4 and to the left and right. It is designed to be applied vertically.

As for the laminating direction, FIG.
This is similar to the example shown in FIG. 7B, and as shown in FIG. 7B, the elastic member 12 is set so that the pressing force is directed to the optical plate 7 for each of the optical sheets 5 and 6. Is attached to a corner on the observer side.

As described above, when the optical plate 7 has a cylindrical shape that is straight in the left-right direction and curved in the up-down direction, as shown in FIG. The tension is applied in the circumferential direction of the cylindrical surface by the application, and the optical sheets 5, 6 can be efficiently used even with a relatively small force.
Can be brought into close contact with the optical plate 7.

In the examples shown in FIGS. 7A and 7B, the pulling force is basically applied in the vertical direction, but the pulling force may be supplementarily applied in the horizontal direction.

That is, as shown in the modified examples of FIGS. 8 (A) and 8 (B), the optical sheets 5 and 6 are provided with support pieces 11 at two positions on the left and right short sides, for example, at the center. , And one end of an elastic member 12a, such as a tension coil spring, which exerts an auxiliary tensile force, is attached to each of the four support pieces 11.

The other end of the elastic member 12 is fixed to two locations substantially at the center of the short side inside the frame member 4, and more specifically, a tensile force is applied in the left-right direction. .

With such a configuration, the optical sheets 5, 6
Can be further improved with respect to the optical plate 7.

Next, referring to FIG. 9, optical sheets 5 and 6 will be described.
A fourth example of a configuration for causing the optical plate 7 to adhere to the optical plate 7 by applying a tensile force to the optical plate 7 will be described.

First, the optical plate 7 is fixedly supported on the frame member 4 by an appropriate support structure as described above.

Next, the optical sheets 5 and 6 have support pieces 11 attached to, for example, the center and the four corners of the long side and the short side. Each of the eight support pieces 11 is provided with a tension coil spring, for example. One end of an elastic member 12 made of, for example, is attached.

As shown in FIG. 9A, the other end of the elastic member 12 is fixed to the center and four corners of the long side and the short side inside the frame member 4, respectively. The tensile force is applied radially from the center of the optical sheets 5 and 6.

As for the stacking direction, FIG.
9B, the other end of the elastic member 12 attached to the optical sheet 5 has a pressing force directed to the optical plate 7 as shown in FIG. 9B. The other end of the elastic member 12 attached to the observer side and the other end of the elastic member 12 attached to the optical sheet 6 is positioned at the corner on the image projection device 1 side so that the pressing force is directed to the optical sheet 5. Installed. Note that the relationship between the magnitudes of the urging forces of the elastic members 12 is the same as described above.

Next, FIGS. 10 and 11 show an example in which a tension varying mechanism for adjusting the tensile force by the elastic member 12 is provided. FIGS. 10 and 11 show examples of the configuration shown in FIGS. It can be applied to any of them.

The variable tension mechanism 15 serving as a tension adjusting means is provided, for example, between the elastic member 12 and the frame member 4. One end is fixed to the elastic member 12 and the other end is a link mechanism. It is attached to the frame member 4 so as to be movable by a connecting portion 14 such as.

More specifically, as shown in FIG. 11, the variable tension mechanism 15 includes a piston portion 15c having the elastic member 12 fixed at one end and a male screw 15d formed on a peripheral surface thereof, and a female screw 15b formed therein. The elastic member 12 is adapted to be screwed into the cylinder portion 15a formed on the inner peripheral surface, and the tensile force of the elastic member 12 is adjusted by the screwing depth.

On the other end side, a pin-like portion 15e provided with the connection portion 14 is attached to the cylinder portion 15a by a lid member 15f.

With such a configuration, the optical sheets 5, 6
It can be easily adjusted even if there is an individual difference in the size of the elastic sheet 12 and the mounting position of the elastic member 12 on the optical sheets 5 and 6.

The support pieces 11 attached to the optical sheets 5 and 6 are made of, for example, an acrylic plate. However, if the acrylic plate alone does not have sufficient durability against the tensile force of the elastic member 12, FIG. As shown in
A reinforcing piece 13 made of, for example, a metal plate or the like may be attached to a portion to which the elastic member 12 is attached.

Incidentally, FIG. 3A and FIG.
As described in (B), in order to prevent the joining line from being observed as a streak, it is necessary that the optical axis O of the projection optical system of the image projection apparatus 1 intersects the joining line almost perpendicularly. desirable.

The relationship between the bonding line of the optical sheet and the image projection device will be described with reference to FIGS.
This will be described in more detail.

First, FIG. 12 to FIG.
1 shows a case in which only one joining line 21a in the up-down direction exists and an image is projected onto the optical sheet 21 from a single image projection device 1.

That is, the optical sheet 21 is formed by joining two sheet members 21b and 21c to each other with their respective edges as joining lines 21a.

The image projection apparatus 1 generates an image and projects it on the optical sheet 21 by the projection optical system 20. The optical axis O of the projection optical system 20 is, for example, It intersects with the intersection 21g at the approximate center.

More specifically, the optical axis O is formed by a tangent vector (direction vector) at the intersection 21g of the joining line 21a and a normal vector set on the main surface of the optical sheet 21 at the intersection 21g. They are arranged so that they lie in a plane.

That is, as shown in FIG. 13, when the image forming apparatus including the optical sheet 21 and the image projecting apparatus 1 is viewed from above, the optical axis O of the projection optical system 20 is the main axis of the optical sheet 21. It intersects the joining line 21a so as to be perpendicular to the plane. On the other hand, when the image forming apparatus is viewed from the side, the joining line is set so that the optical axis O of the projection optical system 20 is perpendicular to the main surface of the optical sheet 21 as shown by a solid line in FIG. 21a, but is not limited to this.

For example, when an image is projected from the image projection device 1 onto the main surface of the optical sheet 21 such that the optical axis O is at an oblique angle as shown by the two-dot line in FIG. It is possible to make the "streaks" caused by 21a inconspicuous.

However, when an image is projected at a launch angle or a down angle, that is, when the projection light beam is deviated upward or downward as viewed from the optical axis O of the projection optical system 20, the optical axis O is set to the screen 21. In most cases, it is perpendicular to the main surface.

The reason why the optical axis O is perpendicular to the joining line 21a when viewed from above will be described with reference to FIGS.

When the joining line 21a is enlarged, as shown in FIG. 15 or FIG. 16, the joining surface 21d, which is an end surface substantially perpendicular to the main surface of the sheet member 21b, and the sheet member 2
The bonding surface 21e, which is an end surface substantially perpendicular to the main surface of 1c, is bonded to each other by using, for example, an adhesive 21f. The adhesive 21f is applied to the sheet member 21.
Although materials having the same refractive index as possible are used for the materials constituting b and 21c, in spite of that,
It is difficult to completely match the optical characteristics. Therefore, the optical characteristics are discontinuous at the joint surfaces 21d and 21e.

In such a configuration, when the optical axis O is within the plane defined by the tangent vector and the normal vector as described above, as shown in FIG. Is the above joining line 2 when viewed from above.
1a is almost perpendicularly incident. With this configuration, since the solid angles of the joining surfaces 21d and 21e when viewed from the projection optical system 20 are almost zero, the joining surfaces 21 having discontinuous optical characteristics.
d and 21e are hardly hit by light rays, and the joining surfaces 21d and 21e
At 21e, light reflection and scattering hardly occur.

On the other hand, when the optical axis O is not in the plane where the tangent vector and the normal vector extend, the light projected from the image projection apparatus 1 is viewed from above as shown in FIG. At this time, the light is obliquely incident on the joining line 21a with a solid angle ω as shown. At this time, since the solid angles of the joint surfaces 21d and 21e when viewed from the projection optical system 20 are larger than those shown in FIG. 15, the joint surfaces 21d and 21e are changed according to the solid angles.
d, 21e are irradiated with light rays, and the joining surfaces 21d, 21e
In this case, reflection and scattering occur depending on the amount of light.

Therefore, the joining line 21a is observed as a "streak". In particular, when the oblique direction is observed, the joining line 21a is observed as a "streak" having a certain width due to the thickness of the sheet members 21b and 21c. To make it more noticeable.

In this way, the optical axis O is located in the plane where the tangent vector and the normal vector extend as described above so that the "streak" is hardly observed.

More generally, when the optical sheet 21 has a peculiar part having a peculiar (for example, discontinuous) optical characteristic such as a joint surface, the optical sheet 21 is transmitted from the projection optical system 20 of the image projection apparatus 1. It is preferable to arrange the image projection device 1 such that the solid angle when viewing this unique portion is minimized. Of course, if the image projection device 1 is separated from the optical sheet 21 indefinitely, the solid angle gradually approaches 0. However, minimizing the solid angle described above does not mean that the solid angle is performed indefinitely.
This means that the image projection apparatus 1 is minimized under the constraint that the image projection apparatus 1 is in a predetermined positional relationship from the optical sheet 21. Here, the constraint condition is, for example, a condition that the image projecting apparatus 1 must be disposed at a predetermined distance from the main surface of the optical sheet 21 corresponding to the focal length of the projection optical system 20, or when performing offset projection. Examples of the conditions related to the offset range allowable in design are given as examples. Further, the unique portion is not limited to the bonding surface, and is a concept including a wide range of optical unique portions such as scratches that may exist on the optical sheet 21.

Next, referring to FIGS. 17 to 19, there is only one vertical joining line 23a on the optical sheet 23, and the image is projected onto the optical sheet 23 from the three image projectors 1A, 1B, 1C. An example of projecting will be described.

First, the optical sheet 23 is constituted by joining two vertically long sheet members 23b and 23c to each other with the long side edge as a joining line 23a.

The image projectors 1A, 1B and 1C are arranged at substantially equal intervals in the vertical direction, and have respective optical axes O.
A, OB, and OC are respectively connected to the joining line 23a.
They meet almost vertically at the intersection. More specifically,
As seen from above, they intersect almost vertically, as shown in FIG. 18, and when seen from the side, they intersect almost vertically, as shown in FIG.

However, the optical axes OA, OB, and OC are, as described above, the tangent vector (direction vector) at each intersection where these optical axes intersect with the joint line 23a, and the main axis of the optical sheet 21 at the intersection. Since it is only necessary to be within the plane where the normal vector set on the surface is stretched, it is not limited to being perpendicular when viewed from the side as shown in FIG.

A part of the image generated by each of the image projection devices 1A, 1B, 1C is projected on the optical sheet 23 such that the edges overlap each other. Typical images are smoothly connected to each other to form one seamless image as a whole.

Next, referring to FIGS. 20 and 21, there are three vertical joining lines on the optical sheet 25, and an image is projected onto the optical sheet 25 from nine image projectors arranged in a grid. An example will be described.

The optical sheet 25 has four sheet members 25.
d, 25e, 25f, and 25g are joined to each other by joining line 2
5a, 25b, and 25c are formed by joining each other.

The image projection devices 1D, 1E, 1F, 1
G, 1H, 1I, 1J, 1K, and 1L are arranged in a lattice so as to be 3 × 3.

More specifically, the image projection devices 1D, 1E,
1F, the respective optical axes OD, OE, OF intersect each other substantially perpendicularly to the joint line 25a at the respective intersections. Intersect each other approximately perpendicularly to the joint line 25b at the respective intersections.
J, 1K, and 1L are the optical axes OJ, OK, and OL, respectively.
Are arranged so as to intersect the joining line 25c substantially perpendicularly with the intersection.

At this time, as shown in FIG. 21, when viewed from above, each optical axis intersects substantially perpendicularly to each joint line, but when viewed from the side, it is not necessarily vertical. It is not limited to intersecting with.

Further, each of the image projection devices 1D, 1E, 1F,
Similar to the above, the partial images projected by 1G, 1H, 1I, 1J, 1K, and 1L are overlapped on the optical sheet 25 with their edges.

Next, referring to FIGS. 22 to 24, there are six vertical bonding lines and four horizontal bonding lines on the optical sheet 27, and nine image projection devices arranged in a grid pattern. An example in which an image is projected on the optical sheet 23 will be described.

The optical sheet 27 includes eight sheet members 27.
k, 27l, 27m, 27n, 27o, 27p, 27
q, 27r are formed by joining edges adjacent to each other.

More specifically, the sheet member 27k and the sheet member 27l are joined by the joining line 27a, and the sheet member 27l and the sheet member 27m are joined by the joining line 27b.
7m and the sheet member 27n are connected by a joining line 27c, and the sheet member 27k and the sheet member 27o are connected by a joining line 27d.
The sheet member 27l and the sheet member 27p are joined by the joining line 27e, and the sheet member 27m and the sheet member 27q are joined by the joining line 27e.
7f, the sheet member 27n and the sheet member 27r are connected by the joining line 27g.
p is joined by the joining line 27h, the sheet member 27p and the sheet member 27q are joined by the joining line 27i, and the sheet member 27q and the sheet member 27r are joined by the joining line 27j.

The image projection devices 1M, 1N, 1O, 1
P, 1Q, 1R, 1S, 1T, and 1U are arranged in a grid pattern so as to have a size of 3 × 3, as shown in FIGS.

That is, in the image projectors 1M and 1N, the respective optical axes OM and ON intersect each other substantially perpendicularly to the joining line 27a at the respective intersections. The axes OP and OQ intersect each other substantially perpendicularly to the joint line 27b at the intersections, and the image projection apparatuses 1S and 1T make the respective optical axes O
S and OT are arranged so as to intersect with the joining line 27c substantially perpendicularly at intersections.

The image projection device 10 has its optical axis OO
Intersects the node 27s of the joining lines 27a, 27d, 27e, and 27h almost perpendicularly with an intersection, and the image projection apparatus 1R has the optical axis OR of the joining lines 27b, 27e, and 2
The image projection device 1U is arranged so that the optical axis OU intersects the node 27u of the joint lines 27c, 27f, 27g, and 27j almost vertically with the intersection. Have been.

More specifically, the image projection devices 1M, 1N,
When viewed from above, 1P, 1Q, 1S, and 1T need only have their optical axes OM, ON, OP, OQ, OS, and OT intersect approximately perpendicularly with the corresponding joint lines. , 1R, and 1U need to have their optical axes OO, OR, and OU substantially perpendicular to the corresponding nodes 27s, 27t, and 27u both when viewed from above and from the side (see FIG. 23). .

In such an arrangement of the image projecting devices, as shown in FIG. 24, the partial images projected by each image projecting device not only have a superimposed region between the vertically adjacent partial images, but also In addition, there is a superimposed area also in the partial images adjacent to the left and right, and there is also an area in which the upper, lower, left and right partial images are superimposed four times.

Further, in the examples shown in FIGS. 22 to 24, the case where the joining lines intersect at right angles in a cross shape at the nodes is shown. However, the present invention is not limited to this. The above-described configuration is similarly applied to the case where the light beam intersects at right angles in a T-shape or the light beam crosses at three or more angles at an arbitrary angle. It is necessary for the point to be in the direction of the normal vector set on the main surface of the optical sheet.

The above-described configuration is similarly applied to a case where the optical sheet has a curved surface such as a cylindrical surface or a spherical surface. Further, specific examples of the optical sheet include an optical sheet in which a large number of beads are arranged in a plane, an optical sheet in which a Fresnel lens is formed, an optical sheet in which a lenticular lens is formed, and an optical sheet having a function of a diffusion sheet. And the like, and the above-described configuration can be applied to any of these.

Further, when an optical screen is formed by superposing a plurality of optical sheets, the joining lines of the respective optical sheets have the above-described relationship with respect to the optical axis of the image projection apparatus. I just want to.

The configuration described with reference to FIGS. 12 to 24 is not limited to the case where the optical sheet is closely contacted with the optical plate to form an optical screen. It is widely applied when an optical sheet having a joint line is generally used, such as when a screen is configured.

In addition, in an actual image forming apparatus,
In some cases, one or more mirrors or the like are arranged between the image projection device and the optical screen to bend the light beam projected from the image projection device. It is sufficient that the optical axis incident on the lens satisfies the above-described relationship.

According to this embodiment, when the optical sheets are bonded, they are arranged in such a way that the optical axis of the image projection device and the bonding line of the optical sheet intersect, and the intersection is In the configuration in which the optical axis is in the plane where the normal vector set on the main surface of the optical sheet and the tangent vector of the joining line at the intersection point, a large screen image forming apparatus in which the joining line is almost not observed. It can be realized.

Further, an optical member such as a diffusion plate is formed as an optical plate having a predetermined rigidity and is formed so as to have a predetermined curved surface shape, and a tensile force is applied to an optical sheet such as a lenticular sheet. Since the optical sheet is pressed against the optical plate so that the optical sheet and the optical plate are in close contact with each other, the image formed on the optical sheet is not blurred even if the field of view is widened by the diffusion surface of the optical plate.

By stretching the optical sheet using the elastic member, it becomes possible to flexibly cope with the expansion and contraction of the optical sheet due to a change in the temperature or humidity of the use environment.

Further, by applying an anti-glare process or an anti-reflection process to the surface of the optical plate on the observer side, the image can be more easily viewed.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications and applications can be made without departing from the gist of the invention.

[0130]

As described above, according to the optical screen unit of the present invention, since the optical sheet can be brought into close contact with the optical plate, the sharpness of the image formed on the optical sheet is not impaired. .

Further, according to the image forming apparatus of the present invention,
Streaks due to the bonding line are not observed as much as possible in the image projected on the optical sheet having the bonding line.

[Brief description of the drawings]

FIG. 1 is a side view showing a configuration of an optical screen unit on which an image is projected from an image projection apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of an optical sheet and an optical plate in an optical screen unit on which an image is projected from an image projection device in the embodiment.

FIGS. 3A and 3B are a plan view and a front view showing a relationship between a joining line in an optical screen unit and an optical axis of an image projection device in the embodiment.

FIG. 4 is an enlarged view showing a configuration of the optical sheet and the optical plate in the stacking direction in the embodiment.

FIG. 5 is a front view and a side view showing a first example of a configuration in which the optical sheet is elastically supported on a frame member in the embodiment.

FIG. 6 is a front view and a side view showing a second example of a configuration in which the optical sheet is elastically supported on the frame member in the embodiment.

FIG. 7 is a front view and a side view showing a third example of a configuration in which the optical sheet is elastically supported by the frame member in the embodiment.

FIG. 8 is a front view and a side view showing a modification of the third example shown in FIG. 7;

FIG. 9 is a front view and a side view showing a fourth example of a configuration in which the optical sheet is elastically supported by the frame member in the embodiment.

FIG. 10 is an enlarged front view of a configuration in which a variable tension mechanism is added to a configuration in which the optical sheet is elastically supported on a frame member in the embodiment.

FIG. 11 is a sectional view showing the internal configuration of the tension variable mechanism in the embodiment.

FIG. 12 is a perspective view showing an image forming apparatus that projects an image from one image projection device onto an optical sheet having one joining line in the embodiment.

FIG. 13 is a plan view showing an image forming apparatus that projects an image from one image projection device onto an optical sheet having one joining line in the embodiment.

FIG. 14 is a side view showing an image forming apparatus that projects an image from one image projection device onto an optical sheet having one joining line in the embodiment.

FIG. 15 is an enlarged plan view showing a desirable positional relationship between a joining line and a light beam projected from the image projection device in the embodiment.

FIG. 16 is an enlarged plan view showing an undesired positional relationship between a joining line and a light beam projected from the image projection device in the embodiment.

FIG. 17 is a perspective view illustrating an image forming apparatus that projects images from three image projection devices onto an optical sheet having one joining line in the embodiment.

FIG. 18 is a plan view showing an image forming apparatus that projects images from three image projectors onto an optical sheet having one joining line in the embodiment.

FIG. 19 is a side view showing an image forming apparatus that projects images from three image projection apparatuses onto an optical sheet having one joining line in the embodiment.

FIG. 20 is a perspective view showing an image forming apparatus that projects images from nine image projectors arranged in a grid on an optical sheet having three parallel joining lines in the embodiment.

FIG. 21 is a plan view showing an image forming apparatus for projecting images from nine image projecting apparatuses arranged in a lattice on an optical sheet having three parallel joining lines in the embodiment.

FIG. 22 is a cross-sectional view of an optical sheet according to the above embodiment, in which there are six vertical bonding lines and four horizontal bonding lines;
FIG. 2 is a perspective view showing an image forming apparatus that projects images from nine image projecting apparatuses arranged in a lattice.

FIG. 23 is a cross-sectional view of an optical sheet according to the above embodiment, in which there are six vertical bonding lines and four horizontal bonding lines;
FIG. 2 is a side view showing an image forming apparatus that projects images from nine image projecting apparatuses arranged in a lattice.

FIG. 24 shows an optical sheet according to the above embodiment, in which there are six vertical bonding lines and four horizontal bonding lines.
FIG. 4 is a front view showing the arrangement of partial images projected from nine image projection devices arranged in a lattice.

[Explanation of symbols]

1,1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1K, 1L, 1M, 1N, 1O, 1P,
1Q, 1R, 1S, 1T, 1U image projection device 3 optical screen unit 3a joining line 4 frame member 5, 6 optical sheet 7 optical plate 7a substrate 7b optical surface 7c diffusion surface 11 support Frames 12, 12a Elastic member (close contact means, tension means) 13 Reinforcement frame 15 ... Variable tension mechanism (tensile force adjusting means) 20 Projection optical system 21, 23, 25, 27 Optical sheets 21a, 23a, 25a, 25b, 25c, 27a, 27b, 27c, 27d, 27e, 27f, 27g, 27
h, 27i, 27j ... Junction lines 21b, 21c, 23b, 23c, 25d, 25e, 25f, 25g, 27k, 27l, 27m, 27n, 27
o, 27p, 27q, 27r ... Sheet member 21d, 21e ... Joining surface 21f ... Adhesive 21g ... Intersection 27s, 27t, 27u ... Node O, OA, OB, OC, OD, OE, OF, OG, OH, OI , OJ, OK, OL, OM, ON, OO, OP,
OQ, OR, OS, OT, OU… Optical axis

Continuing from the front page (72) Inventor Masakatsu Ouchi 4487-9 Kamimizo, Sagamihara-shi, Kanagawa Pref., Ltd. Seikogiken (72) Inventor Isao Toshida 4487-9, Kamimizo, Sagamihara-shi, Kanagawa F-term, Seikogiken (reference) 2H021 BA23 BA32 5C058 BA23 EA01 EA11 EA32

Claims (24)

[Claims] 1. An optical sheet having one or more joining lines by joining a plurality of sheet members to each other with an edge of the sheet members as joining lines, and an image or a part of an image. Is generated and projected onto the optical sheet by the projection optical system. When the bonding lines do not cross each other on the optical sheet, at least the number of the bonding lines or more, and the bonding When the lines cross each other with nodal points on the optical sheet, at least the number of the nodal points, an image projecting device provided, and In the first case where there is only one node in the range of the optical sheet corresponding to the above, the second case where there is no node and only one joining line exists, the third case where there is no joining line
In the first case, the optical axis of the projection optical system in the first case is coincident with the normal established on the main surface of the optical sheet at the node. As described above, in the second case, the optical axis of the projection optical system intersects the junction line at the intersection, and in the plane including the normal established on the main surface at the intersection and the junction line. An image forming apparatus provided as described in (1). 2. The method according to claim 1, wherein the connecting points are all four connecting lines orthogonal to each other in a cross shape, or three connecting lines orthogonal to each other in a T shape.
The image forming apparatus according to claim 1, wherein the image forming apparatus is configured by any one of the following. 3. The image forming apparatus according to claim 1, wherein the joining lines are configured to be parallel to each other. 4. An optical sheet having a substantially planar shape having one joint line by joining two sheet members to each other with an edge of the sheet member as a joint line; A plurality of image projection devices that generate a part and project toward the optical sheet by a projection optical system, wherein the plurality of image projection devices are connected to the bonding line and a main surface of the optical sheet. An image forming apparatus, wherein the optical axes are arranged such that respective optical axes are located in a plane including a vertical line. 5. By joining three or more sheet members to each other with the edge of the sheet member as a joining line, a substantially planar shape having two or more joining lines parallel to each other is formed. An optical sheet, a part of an image is generated, and projected onto the optical sheet by a projection optical system. One or more of the two or more joining lines are provided so as to correspond to each of the two or more joining lines. And a plurality of image projection devices provided, wherein the image projection device is configured such that the optical axis is located in a plane including a corresponding bonding line and a normal line erected on the main surface of the optical sheet. An image forming apparatus, comprising: an image forming apparatus; 6. A plurality of sheet members are joined to each other with an edge of the sheet member as a joining line, thereby having a plurality of joining lines and one or more nodes at which the joining lines intersect with each other. An optical sheet having a substantially planar shape, and a part of an image being generated and projected onto the optical sheet by a projection optical system. One provided so that one corresponds
And an image projection device corresponding to the nodal point, wherein the optical axis of the projection optical system coincides with a normal established on the main surface of the optical sheet at the nodal point. An image forming apparatus, which is arranged so as to intersect. 7. An image projection apparatus further comprising one or more image projection devices provided so as to correspond to the joining line at a portion other than the node, wherein the image projection device corresponds to the joining line at a portion other than the node. Is arranged such that the optical axis of the projection optical system is in a plane including a normal line established on the main surface of the optical sheet at the joining line and the joining line. The image forming apparatus according to claim 6, wherein: 8. An optical sheet including a unique portion having a specific optical characteristic, and an image projecting device for projecting an image toward the optical sheet by a projection optical system, wherein the image projecting device comprises: An image forming apparatus which is arranged at a position where a solid angle when viewing the singular part from the projection optical system is minimized under a constraint condition relating to a predetermined positional relationship with respect to an optical sheet. apparatus. 9. An optical screen unit configured to project an image on a main surface, comprising: a rigid optical plate; and a flexible member disposed along the main surface of the optical plate. An optical screen unit, comprising: at least one optical sheet; and a contact unit for bringing a main surface of the optical plate and a main surface of the optical sheet into close contact with each other. 10. The optical screen unit according to claim 9, wherein the optical plate is formed such that a main surface on a side facing the optical sheet is curved so as to be convex. 11. The optical screen unit according to claim 10, wherein the convex surface is a cylindrical surface. 12. The maximum protrusion amount of the convex surface when no stress is applied to the optical plate is 2 mm or more and 100 m or more.
The optical screen unit according to claim 10, wherein m is equal to or less than m. 13. The optical screen unit according to claim 9, further comprising a pulling unit for applying a pulling force at least in a main surface direction to the optical sheet. 14. The close-contact means, wherein:
The optical sheet has tensile means for applying a tensile force in a main surface direction and a pressing force for pressing the optical sheet against the convex surface of the optical plate, and the optical sheet to which the tensile force has been applied is applied to the optical plate. The optical screen unit according to claim 10, wherein the optical screen unit is brought into close contact by pressing against a convex surface. 15. A frame member for supporting the optical plate, wherein the tension means has one end supported by the frame member and the other end coupled to the optical sheet to generate a tensile force. The optical screen unit according to claim 14, comprising a member. 16. The optical sheet is provided in a plural number, is pulled independently by a plurality of elastic members, and is pulled so that a tensile force applied to each optical sheet is in the same direction. The optical screen unit according to claim 15, wherein: 17. The optical sheet, wherein a plurality of optical sheets are provided, each of which is independently tensioned by a plurality of elastic members, and is located at a position farthest from the optical plate among the plurality of optical sheets. The tensile force applied to the farthest optical sheet has a component in a direction approaching the optical plate, and at least one of the plurality of optical sheets excluding the farthest optical sheet. The tensile force applied to the sheet has a component in a direction away from the optical plate, and the resultant force of the tensile forces applied to the plurality of optical sheets has a component in a direction approaching the optical plate. The optical screen unit according to claim 15, comprising: 18. The optical plate according to claim 15, wherein the convex surface of the optical plate is a cylindrical surface, and the elastic member pulls the optical sheet in a circumferential direction of the cylindrical surface of the optical plate. An optical screen unit according to item 1. 19. The elastic member, wherein the optical sheet comprises:
16. The optical screen unit according to claim 15, wherein the optical screen unit is pulled in a radial direction from a center of the main surface of the optical sheet. 20. The optical screen unit according to claim 15, wherein said pulling means further includes a pulling force adjusting means for adjusting a pulling force of said elastic member. 21. The optical sheet is formed by joining a plurality of sheet members to each other at an edge, and is formed by joining a plurality of sheet members.
At least one of the joining lines is configured to be located at a position that intersects with the optical axis of the projection optical system of the image projection device that projects the optical screen unit. The optical screen unit according to claim 9. 22. The optical screen unit according to claim 9, wherein the optical plate is a diffusion plate, and the optical sheet is provided in a plural number and includes at least two lenticular sheets. 23. A surface of the diffusion plate, which is in contact with the lenticular sheet, is formed as a diffusion surface, and
23. The optical screen unit according to claim 22, wherein the surface opposite to the diffusion surface has been subjected to anti-glare treatment. 24. A surface of the diffusion plate, which is in contact with the lenticular sheet, is formed as a diffusion surface, and
23. The optical screen unit according to claim 22, wherein the surface opposite to the diffusion surface has been subjected to an anti-reflection treatment.