JP2002341452A - Image projecting device, multiple image projecting device and screen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image projecting device thin-shaped in a depth direction without deteriorating the image quality. SOLUTION: As for the image projecting device wherein an image displayed by display elements is enlarged and projected on a screen 1 by a projection optical system, a 4th mirror 4, a 3rd mirror 5, a 2nd mirror 6 and a 1st mirror 7 are arranged in luminous flux passing order on an optical path between the projection optical system and the screen 1 so as to bend the optical path, then, the volume of a space where the luminous flux passes is made smaller as a whole, besides, as for the mirror 5 among several mirrors, the mirror 5 provided with the furthest end edge separated furthest away from the screen 1 in a Z-axis direction is formed as a concave mirror, then, a distance DO from the screen 1 to the furthest end edge is made shorter than that in the case the mirror 5 is formed as a plane mirror, then, the thin-shaped image projecting device is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image projection apparatus and a multi-image projection apparatus for projecting a light flux relating to an image displayed by a display element on a screen by diffracting a plurality of light beams, and
A screen on which the image is projected.

[0002]

2. Description of the Related Art There have been proposed various image projection apparatuses for projecting an image displayed by a display element on a screen and displaying the image so that the image can be observed.

[0003] Such an image projection apparatus enlarges and projects an image on a display element using a projection optical system. At this time, when the projection is performed so that the light flux is rapidly expanded, the image is projected on the periphery of the image. The projected light rays are incident at a considerably oblique angle, so that the peripheral light quantity is insufficient and the quality of the image is degraded.

Therefore, when the image quality is emphasized, the light beam is projected so as to spread gently. However, at this time, since the optical path length becomes long, the size of the image projection apparatus in the depth direction becomes large as it is. Would.

Therefore, there has been proposed an image projection apparatus in which the optical path is bent using a mirror to reduce the thickness in the depth direction.

As an example of such a technique, Japanese Patent Laid-Open No.
Japanese Patent No. 84313 discloses an image display device for displaying an image, a projection lens for enlarging and projecting an image projected on the image display device, a reflection mirror for reflecting the enlarged and projected image, and a reflection mirror for the image display device. And a screen for forming an image reflected by the rear projector, a plurality of the reflection mirrors provided, a final reflection mirror for finally forming an image on the screen, the image display device, and the projection lens A rear projector arranged at substantially the same height as the arrangement height of the screen is described.

The optical system in the rear projector described in this publication specifically has three images on an optical path for projecting an image displayed on an image display device comprising a cathode ray tube onto a screen using a projection lens. By arranging mirrors and bending the optical path, the overall size of the apparatus is reduced.

Further, a technique has been proposed in which a light path is bent using a mirror and an image is projected at a launch angle at which a chief ray incident on a screen is inclined, thereby reducing the thickness of the image projection apparatus. For example, JP-A-59
No. 15925.

Japanese Patent Application Laid-Open No. 59-15925 discloses that
As a screen that favorably displays an image projected with such a launch angle, a rear projection screen configured such that a linear Fresnel lens surface is positioned on the projection side of a screen body having a circular Fresnel lens surface is described. .

On the other hand, instead of the above-described concentric circular Fresnel lens surface, a technique using a combination of a vertical stripe horizontal convergent Fresnel surface and a horizontal stripe vertical convergent Fresnel surface is disclosed in, for example, Japanese Patent Application Laid-Open No. 58-93044. No., published in Japanese Unexamined Patent Publication No. More specifically, according to the publication, the screen is composed of two or more transparent plastic layers, and a vertical black striped surface is formed on the first surface, and the horizontal black stripe is formed on the second surface. A lenticular surface is formed, a horizontal converging vertical stripe Fresnel surface is formed on the third surface, and a fourth surface is formed on the fourth surface.
There is described an image projection apparatus provided with a screen having a vertically converging horizontal stripe-shaped Fresnel / lenticular surface formed after the surface.

Further, the publication also describes a technique for reducing moire interference caused by interference between a scanning line and a Fresnel lens while improving productivity.

[0012]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 7-843.
With reference to FIGS. 10 to 12, an example of a configuration described in Japanese Patent Application Laid-Open No. 13-132, which aims to reduce the size of an image projection apparatus by bending an optical path by using a plurality of mirrors will be described.

FIG. 10 is a plan view showing an example of the configuration of an image projection apparatus having room for further reduction in thickness, FIG. 11 is a side view showing the configuration of the image projection apparatus of FIG.
FIG. 11 is a diagram showing a configuration of a display element and a projection optical system in the image projection device of FIG. 10 from above.

In FIGS. 10 to 12, when viewed from the observer who observes the image displayed on the screen 91, the upward direction is the positive direction of the Y-axis, the left direction is the positive direction of the X-axis, Is defined as the positive direction of the Z axis.

As shown in FIGS. 10 and 11, the image projecting apparatus includes a display element 92 for displaying an image, and a screen 91 for displaying an image displayed by the display element 92, which will be described later.
Optical system 93 for projecting light toward
A fourth mirror 94 for reflecting the light beam projected in the negative direction of the approximate X axis by the third mirror 94 and bending the light beam in the positive direction of the approximate Y axis;
A third mirror 95 that reflects the light beam from the mirror 94 and bends it in the substantially negative direction of the Z axis, and a second mirror that reflects the light beam from the third mirror 95 and bends it in the substantially positive direction of the Y axis. 9
6, a first mirror 97 that reflects the light beam from the second mirror 96 and bends it in the substantially negative direction of the Z-axis, and receives and diffuses the light beam from the first mirror 97 to observe an image. And a screen 91 to be displayed on the screen.

Further, the projection optical system 93 is configured as, for example, a telecentric optical system, and as shown in FIG. 12, a convex lens 93a, a concave lens 93b bonded to the convex lens 93a, and a stop 93c.
, A concave lens 93d, and a convex lens 93e.

The convex lens 93a and the concave lens 93b are
It is formed of mutually different glass materials and is for correcting chromatic aberration and the like.

The concave lens 93d and the convex lens 93
Is responsible for most of the power for enlarging and projecting the image displayed on the display element 92.

In such a configuration, the depth size of the image projection device is determined by the length from the screen 91 to the farthest edge of the third mirror 95 in the Z-axis direction.
D1 shown in FIG.

Since it is desired that such an image projection device has a large screen and a small depth size, a technique for further shortening D1 and making it thinner is required.

Further, in the apparatus disclosed in JP-A-59-15925, a circular Fresnel screen is employed only from the viewpoint of projecting an image from a single image projection unit. Even if it is applied to a multi-image projector that projects a partial image from the image projection unit as it is, the following problem occurs.

That is, in the multi-image projection apparatus, in order to smoothly connect a plurality of partial images projected from a plurality of image projection units on a screen, the edges of the partial images are overlapped with each other. Perform projection. In such a superimposed region of partial images, since light from different image projection units enters at different incident angles, when light is diffused by a circular Fresnel screen, light from one image projection unit is Even if the light is diffused correctly, the light from the other image projection unit will not be diffused correctly. When such diffusion is performed, the seam between the partial images is clearly recognized, and the image quality is greatly impaired.

Also, the technique described in Japanese Patent Application Laid-Open No. 58-93044 does not consider a multi-image projection apparatus, and displays a single image by projecting partial images from a plurality of image projection units. It is not a suitable configuration.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an image projection apparatus which is reduced in the depth direction without deteriorating the image quality.

Another object of the present invention is to provide a multi-image projection apparatus which is thin in the depth direction without deteriorating the image quality even when partial images are projected from a plurality of image projection units.

Still another object of the present invention is to provide a screen which can be applied to a multi-image projection apparatus and which can easily display an image projected at a predetermined launch angle.

[0027]

In order to achieve the above object, an image projection apparatus according to a first aspect of the present invention provides a display element for displaying an image, and an image projected by the display element in an enlarged manner. A projection optical system, a screen for displaying the image observable by diffusing a light beam relating to the image projected by the projection optical system, and a screen arranged in order on the optical path between the projection optical system and the screen. A plurality of mirrors, each of which bends the optical path to perform a plurality of bendings so as to reduce the volume of the space through which the light flux passes as a whole, wherein The mirror provided with the farthest edge farthest from the screen in the direction of the normal set on the main surface of the screen has the farthest edge of the normal more than when formed as a plane. Screw in the direction And it is formed as a curved surface, as close to the down.

An image projection apparatus according to a second aspect of the present invention
In the image projection device according to the first aspect, the curved surface having the farthest edge approaching the screen in the direction of the normal is a concave surface having a positive power.

Further, in the image projection apparatus according to the third invention, in the image projection apparatus according to the second invention, the mirror provided with the farthest edge is arranged from the screen side of the plurality of mirrors. This is the third mirror counted.

An image projection apparatus according to a fourth aspect of the present invention is the image projection apparatus according to the second aspect, further comprising an eccentricity correcting optical element for correcting the eccentricity of the mirror having a concave surface having a farthest edge. It is a thing.

An image projection apparatus according to a fifth aspect of the present invention is the image projection apparatus according to the fourth aspect, wherein the projection optical system includes a stop, and the eccentricity correction optical element is optically separated from the stop. Is located in the position.

According to a sixth aspect of the present invention, in the image projection device according to the fifth aspect, the eccentricity correcting optical element is an eccentricity correcting lens included in the projection optical system.

An image projection apparatus according to a seventh aspect of the present invention is the image projection apparatus according to the fifth aspect, wherein the eccentricity correcting optical element is a mirror provided with the farthest edge of the plurality of mirrors. An adjacent mirror, wherein the adjacent mirror is formed as a convex mirror having negative power.

An image projection apparatus according to an eighth aspect of the present invention provides a display element for displaying an image, a projection optical system for enlarging and projecting an image displayed by the display element, and a projection optical system for projecting the image projected by the projection optical system. A screen for displaying the image observable by diffusing the light beam, and sequentially arranged on an optical path between the projection optical system and the screen, each of which bends the optical path to form the light beam as a whole. A plurality of mirrors that bend a plurality of times so as to reduce the volume of the space through which the light passes, and a mirror in a direction normal to the main surface of the screen among the plurality of mirrors. The first with the furthest edge furthest from the screen
The mirror has a smaller reflective surface area so that the farthest edge is closer to the screen in the direction of the normal than the case where the mirror is formed as a flat surface, and despite the reflective surface area being reduced. It is formed as a convex mirror having negative power so as to obtain a necessary spread of a light beam without lengthening the optical path, and is provided on the optical path of the first mirror among the plurality of mirrors. Second adjacent to
Is formed as a concave mirror having a positive power so as to correct the eccentricity of the first mirror and to spread the light beam by the first mirror appropriately.

An image projection apparatus according to a ninth aspect is the image projection apparatus according to the eighth aspect, wherein the first mirror is a third mirror of the plurality of mirrors counted from the screen side. is there.

A multi-image projection apparatus according to a tenth aspect of the present invention provides a screen, a display element for displaying an image, a projection optical system for enlarging and projecting a partial image displayed by the display element, the projection optical system, and the screen. And a first mirror surface arranged to project the partial image toward the screen on an optical path between the first mirror surface and the first mirror surface arranged to project the partial image toward the first mirror surface on the optical path. And a plurality of image projection units each having a second mirror surface, wherein on the screen, adjacent partial images have a superimposed region on the periphery thereof.
A multi-image projection apparatus that projects a partial image by each of the plurality of image projection units to display a seamless image on the screen so as to be observable, wherein the plurality of image projection units are adjacent to each other. In the image projection unit, the first mirror surface on one side and the second mirror surface on the other side are mirror surfaces provided on the main surfaces of the same flat plate member.

A screen according to an eleventh aspect of the present invention is a multi-image projection apparatus for projecting a partial image while enlarging each of the partial images by a plurality of image projection units, wherein a principal ray of each partial image is inclined with respect to a normal set on the screen. A screen applicable to a multi-image projector configured to be incident at a predetermined launch angle that is an angle,
A method in which a Fresnel-shaped portion formed of a ridge in one direction is arranged at a predetermined pitch along another direction perpendicular to the one direction, and the Fresnel-shaped portion stands a main ray incident at the launch angle on the screen. A one-dimensional Fresnel screen which is shaped so as to be converted into a ray in the direction of a line and emits the light, and obliquely incident rays that can be included in a light beam passing through the one-dimensional Fresnel screen are perpendicular to the main surface. A double-sided lenticular screen in which lenticular-shaped portions are arranged at a predetermined pitch on both the front and back main surfaces so as to convert the light into light that is diffused about the direction.

According to a twelfth aspect of the present invention, in the screen according to the eleventh aspect, the multi-image projecting device corresponds to the plurality of partial images with display elements each having a plurality of display pixels arranged two-dimensionally. The one-dimensional Fresnel screen of the one-dimensional Fresnel screen and the lenticular shape of the double-sided lenticular screen have a pitch of the display pixel projected on the screen in the other direction as PG, When the pitch of the double-sided lenticular screen is PL and the pitch of the one-dimensional Fresnel screen is PF, it is formed so as to satisfy the relationship of PG ≧ 2PL ≧ 4PF.

[0039]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 9 show an embodiment of the present invention. FIG. 1 is a plan view showing a configuration of an image projection device, FIG. 2 is a side view showing a configuration of the image projection device, and FIG. FIG. 4 is a side view showing a second configuration example of the image projection device, FIG. 5 is a side view showing a third configuration example of the image projection device, and FIG. 6 is a side view showing a configuration example of the multi-image projection device, FIG. 7 is a side view showing another configuration example of the multi-image projection device, and FIG. 8 is a diagram showing a configuration of a screen in the image projection device extended in the optical axis direction. FIG. 9 is an exploded perspective view, and FIG. 9 is a view showing how light rays are bent by a one-dimensional Fresnel screen and a horizontal lenticular screen.

First, in the drawings of the present embodiment, when viewed from an observer observing an image displayed on the screen 1, the upward direction is the positive direction of the Y axis, the left direction is the positive direction of the X axis, and the back of the screen 1. The side direction is defined as the positive direction of the Z axis.

Accordingly, the display surface of the screen 1 is a surface in which the Z-axis coordinate is a constant, that is, a surface parallel to the XY plane. The element 2 and the projection optical system 3 are provided.

This image projection apparatus, as shown in FIGS. 1 and 2, displays an image and comprises a plurality of display pixels.
A display element 2 arranged in a two-dimensional manner; a projection optical system 3 for projecting an image displayed by the display element 2 onto a screen 1 described later; A fourth mirror 4 that reflects the projected light beam and bends it in the substantially positive Y-axis direction; and a third mirror 5 that reflects the light beam from this fourth mirror 4 and bends it in the substantially negative Z-axis direction.
A second mirror 6 that reflects the light beam from the third mirror 5 and folds it in the substantially positive direction of the Y axis; and reflects a light beam from the second mirror 6 and folds it in the negative direction of the substantially Z axis. A first mirror 7 to be bent, and a screen 1 for displaying an image observable by receiving and diffusing a light beam from the first mirror 7
, And is configured.

The display element 2 is composed of, for example, a transmissive LCD which displays an image upon receiving an image signal. The display element 2 emits a luminous flux relating to the displayed image by being irradiated with illumination light from the back side. It has become. This display element 2
Are arranged in such a direction that the normal line on the display surface is substantially in the negative direction of the X-axis, but more specifically, they are arranged slightly inclined as described later.

Since the projection optical system 3 enlarges and projects the image displayed on the display element 2, the projected light beam gradually spreads toward the screen 1. Accordingly, the fourth mirror 4 and the third mirror 4 are sequentially arranged on the optical path between the projection optical system 3 and the screen 1.
The mirror 5, the second mirror 6, and the first mirror 7 are also configured so that the area of the reflection surface increases in this order so as to be necessary and sufficient to reflect the light beam.

Further, a third one of the fourth mirror 4 to the first mirror 7 which is the third from the screen 1 side is counted.
The mirror 5 is disposed on the most rear side (the positive side of the Z axis) of the image projection apparatus, and is arranged at the farthest position from the screen 1 in the direction of a normal line on the main surface of the screen 1. It is a mirror with a far edge.

The third mirror 5 has an aspherical surface or a free surface so that the amount of projection in the positive direction of the Z axis is small, that is, the farthest edge is close to the screen 1 along the Z axis direction. It is formed as a concave mirror having a curved surface and a positive power. More specifically, the concave shape of the third mirror 5 is formed so that, for example, the power in the vertical direction (substantially Y-axis direction) and the power in the horizontal direction (substantially X-axis direction) are the same. A part of the power for projecting the image of the element 2 on the screen 1 is shared by the projection optical system 3.

Thus, the distance D0 in the positive direction of the Z axis from the display surface of the screen 1 to the farthest edge of the third mirror 5
Is configured to be smaller than the distance D1 in the configuration as shown in FIG.

The reflection direction of the light beam by each of the mirrors is described in more detail as follows.

The fourth mirror 4 reflects the light beam substantially in the positive direction of the Y axis and slightly inclines in the positive direction of the Z axis. The third mirror 5 reflects the light beam in the substantially negative direction of the Z axis. The second mirror 6 reflects the light beam so as to be slightly inclined in the positive direction of the Y-axis, and the second mirror 6 reflects the light beam so as to be slightly inclined in the positive direction of the Y-axis and slightly in the positive direction of the Z-axis. The light beam is arranged to be reflected so as to be inclined substantially in the negative direction of the Z axis and slightly in the positive direction of the Y axis. With such a configuration, the optical path is bent,
As a whole, the volume of the space through which the light flux relating to the image passes can be reduced.

The light beam reflected by the first mirror 7 and incident on the screen 1 is projected so as to be slightly upward (positive direction of the Y axis) as seen from the observer as described above. Become. The launch angle θ at this time, that is, the inclination angle with respect to the normal to the screen 1 when the chief ray is incident is set to be a predetermined angle, and specifically, 20 ° is an example. No.

By projecting the image onto the screen 1 at a predetermined launch angle θ in this manner, the thickness of the image projection apparatus is reduced. However, the mirror having the farthest edge as described above is formed into a curved surface. The technique for reducing the thickness of the image projection apparatus by forming the projection angle θ can also be applied to the case where the launch angle θ is 0 °.

On the other hand, the projection optical system 3 is configured as shown in FIG.

First, the display element 2 for displaying an image is disposed so that the normal line on the display surface thereof is directed substantially in the negative direction of the X axis. It is arranged to incline. The display element 2 is arranged to be inclined in order to improve the display quality of an image projected at a launch angle.

The projection optical system 3 for projecting a light beam emitted in a slightly oblique direction from the display element 2 includes an eccentricity correcting lens 3a as an eccentricity correcting optical element for correcting eccentricity by the third mirror 5, and It has a convex lens 3b, a concave lens 3c bonded to the convex lens 3b, a convex lens 3d, a stop 3e, and a concave lens 3f.

The eccentricity correcting lens 3a is arranged at a position optically separated from the stop 3e as much as possible, that is, at a position closest to the display element 2 in the projection optical system 3. Because the light emitted from each of the display pixels is focused, the stop 3e
The position where each ray is separated as far as possible from
This is because the ability to correct eccentricity increases.

Further, in the projection optical system 3, the convex lens 3d and the concave lens 3f bear most of the power for projecting the image displayed on the display element 2, as described above. The third mirror 5 also bears part of the power.

The concave lens 3c and the convex lens 3b are formed of mutually different glass materials, and are for correcting chromatic aberration and the like.

Thus, by making the third mirror 5 a concave mirror, it is possible to reduce the thickness of the image projection device in the direction perpendicular to the screen 1.

Next, another configuration example of the image projection apparatus will be described with reference to FIG.

In the configuration shown in FIGS. 1 and 2, only the third mirror 5 counted from the screen 1 side is a curved reflecting surface. However, the configuration example shown in FIG. The second second mirror 6A counted from 1 is also a curved reflecting surface.

That is, the second mirror 6A is configured as a convex mirror having a negative power, which is an aspherical surface or a free-form surface. For example, the vertical power and the horizontal power are the same. ing. Further, the second mirror 6A is an eccentricity correcting optical element for correcting eccentricity caused by the third mirror 5.

The eccentricity correcting optical element for correcting the eccentricity by the third mirror 5 is desirably arranged at a position separated from the stop of the projection optical system as described above. The eccentricity is corrected by using a second mirror 6A closer to the screen 1 than the mirror 5. Although the first mirror 7 is located at a position further optically separated from the stop than the second mirror 6A, the first mirror 7 that finally projects onto the screen 1 is used.
Since it is desirable that the second mirror 6A is a convex mirror, the best configuration is that the second mirror 6A is a convex mirror.

Since the correction is performed by the second mirror 6A, the projection optical system as shown in FIG. 12 can be used almost as it is as the projection optical system.

As described above, by combining the concave mirror and the convex mirror, the aberration can be corrected so that the Petzval sum becomes zero.

With such a configuration, the screen 1
It is possible to reduce the thickness of the image projection device in the direction perpendicular to the direction.

Next, another example of the configuration of the image projection apparatus will be described with reference to FIG.

In the configuration shown in FIG. 5, the relationship between the concave mirror and the convex mirror in the second mirror 6A and the third mirror 5 shown in FIG. 4 is reversed.

That is, the second mirror 6B, which is an eccentricity correcting optical element, is configured as a concave mirror having a positive power, and the third mirror 5B is configured as a convex mirror having a negative power.

Here, the reason why the second mirror 6B is a concave mirror is to restrict the light beam at the third mirror 5B, whereby the third mirror 5B has a reflecting surface sufficient to reflect the narrowed light beam. The third mirror 5B can be reduced in size as long as it has an area.

In other words, the third mirror 5B having the farthest edge farthest from the screen 1 in the direction of the Z axis (see FIG. 2 and the like) has a small reflecting surface area and a small size. It is configured such that the farthest edge is closer to the screen 1 in the Z-axis direction than when formed as a plane.

Further, the third mirror 5B is a convex mirror having a negative power so that a necessary light beam can be spread without elongating the optical path despite the reduction in the area of the reflecting surface. Is formed.

On the other hand, it is necessary to make sure that the light flux projected on the screen 1 in an enlarged manner, especially in the vicinity of the edge, does not have a large inclination. This is because if the inclination is large, there is a possibility that the image quality may be degraded such as a shortage of light amount near the periphery of the image.

For this purpose, the second mirror 6B adjacent to the third mirror 5 on the optical path rearward is formed as a concave mirror having a positive power so that the spread of the light beam by the third mirror 5B becomes appropriate. Have been. The second mirror 6 further has a function of correcting eccentricity caused by the third mirror 5, and serves as an eccentricity correcting optical element.

Further, the second mirror 6B and the third mirror 5B
Is a combination of a concave mirror and a convex mirror, so that aberration can be satisfactorily corrected, and the projection optical system shown in FIG. What can be performed is the same as the configuration example shown in FIG.

With the configuration shown in FIG. 5,
The image projection device in the direction perpendicular to the screen 1 can be made thinner.

Next, with reference to FIG. 6, a description will be given of a multi-image projection apparatus which performs a multi-image display by combining a plurality of the configurations shown in FIGS.

By using the configuration shown in FIGS. 1 and 2 as one image projection unit, a plurality of the image projection units are combined, and a partial image is projected from each image projection unit. It is possible to generate a single image.

More specifically, in this multi-image projection apparatus, a plurality of image projection units project partial images on the screen 1 so that adjacent partial images have a superimposed region OWR1 on the periphery thereof. By doing so, a seamlessly integrated image as a whole is displayed on the screen 1 so as to be observable.

In order to provide such a superimposition region OWR1, it is necessary to arrange the image projection units as close as possible to each other, and as shown in the drawing, the second mirror of the image projection unit arranged on the upper side 6 and the first mirror 7 of the image projection unit arranged on the lower side are arranged so that they are almost back to back and adjacent to each other.

Although FIG. 6 shows a state in which the image projection units are arranged vertically, it is needless to say that since the image projection units are similarly arranged in the horizontal direction,
A plurality of image projection units can be arranged two-dimensionally.

According to such a configuration, it is possible to reduce the thickness in the direction perpendicular to the screen 1 even in the multi-image projector.

FIG. 7 is a slightly improved version of the configuration shown in FIG.

In the above description, the first mirror 7 and the second mirror 6 of the image projection units vertically adjacent to each other are arranged back to back, but in the example shown in FIG. 7, they are shared by one member. It was made.

That is, the first and second common mirror 8 has a mirror surface 8b having the same function as the first mirror 7 on one side of the flat plate member, and has the same function as the second mirror 6 on the other side. This is a double-sided mirror on which a mirror surface 8a is formed.

In the configuration shown in FIG. 7, the first and second common mirrors 8 need to be used for the mirror sandwiched between the upper image projection unit and the lower image projection unit. The mirror only needs to have the mirror surface 8b, and the lower mirror only needs to have the mirror surface 8a. Therefore, the mirror can be configured as a mirror having only one mirror surface. Alternatively, the first and second mirrors are also used for the upper mirror and the lower mirror.
The common mirror 8 may be used as it is to reduce costs by sharing parts.

According to such a configuration, since only one flat plate member is required to form the mirror surface, it is possible to reduce the weight and to manufacture the mirror at low cost. Further, the two flat plates shown in FIG. The thickness of the member can be reduced to approximately half or less as compared with the configuration using a mirror.

Further, since the mirror frame member for holding the first and second common mirrors only needs to be configured to hold one mirror, the space occupied by the mirror frame member can be reduced.

Thus, the overlapping area OWR2 in the configuration shown in FIG. 7 is replaced with the overlapping area OWR shown in FIG.
Since it can be larger than 1, partial images can be connected more smoothly.

Thus, it is possible to reduce the thickness of the multi-image projector in the direction perpendicular to the screen 1 while improving the display quality of the image.

Here, the configuration of the screen 1 applicable to the above-described image projection device and multi-image projection device will be described with reference to FIGS.

The screen 1 has a one-dimensional Fresnel screen 11, a horizontal lenticular screen 12, a vertical lenticular screen 13, and a diffusing plate 14 superimposed in the traveling direction of the light beam. Although it is shown in an exploded manner in the optical axis direction, it is actually integrated in a state of being in close contact.

The one-dimensional Fresnel screen 11 is provided with a Fresnel-shaped portion 11a, which is formed of a strip that is elongated in the horizontal direction (X-axis direction), on the main surface opposite to the horizontal lenticular screen 12, in the vertical direction (Y-axis direction). 9) are arranged at a predetermined pitch, and light rays incident at a launch angle as shown by a solid line in FIG. 9 are incident from a substantially vertical direction as shown by a two-dot line in FIG. It converts it into a ray equivalent to the incoming ray. In order to perform such a change in the direction of the light beam, the Fresnel-shaped portion 11 a
It is formed in a triangular wave shape such that a slope portion is mainly observed when viewed from the axial direction.

The horizontal lenticular screen 12
The vertical direction (Y) of the two main surfaces on which the lenticular-shaped portions 12a in the horizontal direction (X-axis direction) having a substantially cylindrical shape form the front and back sides.
(Axial direction) at a predetermined pitch, and formed as a double-sided lenticular screen. The horizontal lenticular screen 12 is for correcting a horizontal viewing angle.

The vertical lenticular screen 13 has a plurality of lenticular shaped portions 13a in a vertical direction (Y-axis direction), each having a substantially cylindrical shape, at a predetermined pitch in the horizontal direction (X-axis direction) on both main surfaces forming the front and back surfaces. They are arranged and formed as a double-sided lenticular screen. The vertical lenticular screen 13 is for correcting a vertical viewing angle.

Thus, for example, the light obliquely incident on the edge of the screen or the like is also reflected on the horizontal lenticular screen 1.
After passing through the vertical lenticular screen 2 and the vertical lenticular screen 13, the light is converted into light that diffuses around the vertical direction.

Further, the diffusion plate 14 has, for example, a main surface on the side facing the vertical lenticular screen 13 formed as a diffusion surface 14 a, and the light diffused by the two lenticular screens 12, 13. Is further diffused to obtain a wider viewing angle.

In this way, even in the superimposition region, since all the light rays incident from the adjacent projection units are diffused about the vertical direction, a seamless image can be displayed regardless of the observation direction. Thus, the configuration is suitable not only for use in a normal image projection apparatus, but also for use in a multi-image projection apparatus.

In such a configuration, assuming that the pitch of the one-dimensional Fresnel screen 11 is PF, the pitch of the horizontal lenticular screen 12 is PH, and the pitch of the vertical lenticular screen 13 is PV, these satisfy the following relationship. It is configured. PH> 2PF or PF> 2PH

Further, each of the above pitches is PH は 3.5 PF or PH> 4.5 PF or PF ≒ 3.5 PH or PF> 4.5 P
It is more desirable to satisfy the relationship of H.

Actually, it is difficult to reduce the pitch of the lenticular screen from the viewpoint of manufacturing technology, and it is easier to reduce the pitch of the one-dimensional Fresnel screen. Therefore, PF is set smaller than PH. , PH ≒
It is considered that 3.5 PF or PH> 4.5 PF contributes to reducing the manufacturing cost.

Further, assuming that the pitch of the display pixels projected on the screen 1 is PG, and that the pitch PH of the horizontal lenticular screen 12 or the pitch PV of the vertical lenticular screen 13 is PL,
These satisfy the following relations. PG ≧ 2PL ≧ 4PF

By forming the Fresnel-shaped portion 11a and the lenticular-shaped portions 12a and 13a so as to satisfy this relational expression, the occurrence of moire can be suppressed and the quality of the displayed image can be further improved.

Note that this relational expression is also applied to the case where the lenticular screen is arranged in an oblique direction rotated around the optical axis.

The pitch PG is more desirably 3.5 times the pitch PH and 3.5 times the pitch PV.

In general, it is desirable that the pitch ratio be a half-integer such as 2.5 or 3.5. In particular, by increasing the ratio up to about 3.5, the moire caused by harmonics can also reduce the amplitude. It becomes possible to make it smaller and less noticeable.

According to the image projection device of such an embodiment, it is possible to reduce the thickness in the depth direction without deteriorating the image quality.

Further, according to the multi-image projection apparatus of such an embodiment, even if partial images are projected from a plurality of image projection units, the thickness can be reduced in the depth direction without deteriorating the image quality.

Further, according to the screen of such an embodiment, the present invention can be applied to a multi-image projector,
An image projected at a predetermined launch angle can be displayed in an easily viewable manner.

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.

[0110]

As described above, according to the image projection apparatus of the present invention, it is possible to reduce the thickness in the depth direction without deteriorating the image quality.

Further, according to the multi-image projection apparatus of the present invention, even if partial images are projected from a plurality of image projection units, the thickness can be reduced in the depth direction without deteriorating the image quality.

Further, according to the screen of the present invention, the screen can be applied to a multi-image projection apparatus, and an image projected at a predetermined launch angle can be easily displayed.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of an image projection device according to an embodiment of the present invention.

FIG. 2 is a side view showing the configuration of the image projection device according to the embodiment.

FIG. 3 is a diagram showing a configuration of a display element and a projection optical system in the image projection apparatus of the embodiment from above.

FIG. 4 is a side view showing a second configuration example of the image projection device in the embodiment.

FIG. 5 is a side view showing a third configuration example of the image projection device in the embodiment.

FIG. 6 is a side view showing a configuration example of the multi-image projection device in the embodiment.

FIG. 7 is a side view showing another example of the configuration of the multi-image projector in the embodiment.

FIG. 8 is an exploded perspective view showing a configuration of a screen in the image projection device of the embodiment, which is extended in an optical axis direction.

FIG. 9 is a diagram showing how light rays are bent by a one-dimensional Fresnel screen and a horizontal lenticular screen in the embodiment.

FIG. 10 is a plan view showing a configuration example of an image projection device that has room for further reduction in thickness.

FIG. 11 is a side view showing the configuration of the image projection device of FIG. 10;

FIG. 12 is a diagram showing a configuration of a display element and a projection optical system in the image projection apparatus of FIG. 10 from above.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Screen 2 ... Display element 3 ... Projection optical system 3a ... Eccentricity correction lens (eccentricity correction optical element) 3e ... Aperture 4 ... 4th mirror 5 ... 3rd mirror (mirror provided with the farthest edge) 5B ... 3rd Mirror (mirror with farthest edge, first mirror) 6 ... second mirror 6A ... second mirror (eccentricity correcting optical element) 6B ... second mirror (eccentricity correcting optical element, second mirror) 7 ... 1st mirror 8 ... 1st and 2nd common mirror (flat member) 11 ... 1-dimensional Fresnel screen 11a ... Fresnel shape part 12 ... Horizontal lenticular screen (double-sided lenticular screen) 12a ... Lenticular shape part 13 ... Vertical lenticular screen (double-sided lenticular screen) Screen) 13a: Lenticular shape part 14: Diffusion plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H021 BA25 5C058 AB06 BA23 BA35 EA02 EA03 EA12 EA36

Claims (12)

[Claims] A display element for displaying an image; a projection optical system for enlarging and projecting the image displayed by the display element; and a light beam relating to the image projected by the projection optical system being diffused. A screen for displaying the image so as to be observable, and sequentially arranged on an optical path between the projection optical system and the screen, each of which bends the optical path to collectively define a space through which the light flux passes. A plurality of mirrors that bend a plurality of times so as to reduce the volume, comprising: a mirror that, from among the plurality of mirrors, extends in a direction of a normal to the main surface of the screen. The mirror having the furthest edge that is farthest away is characterized in that the farthest edge is formed as a curved surface that is closer to the screen in the direction of the normal line than when it is formed as a flat surface. Toss Image projection apparatus. 2. The image projection apparatus according to claim 1, wherein the curved surface whose farthest edge is close to the screen in the direction of the normal is a concave surface having a positive power. 3. The image projection according to claim 2, wherein the mirror provided with the farthest edge is a third mirror counted from the screen side among the plurality of mirrors. apparatus. 4. The image projection apparatus according to claim 2, further comprising an eccentricity correcting optical element for correcting eccentricity of the mirror having a concave surface having a farthest edge. 5. The image according to claim 4, wherein the projection optical system includes a stop, and the eccentricity correction optical element is disposed at a position optically separated from the stop. Projection device. 6. The image projection apparatus according to claim 5, wherein the eccentricity correction optical element is an eccentricity correction lens included in the projection optical system. 7. The eccentricity correcting optical element is a mirror adjacent to the mirror having the farthest edge of the plurality of mirrors, wherein the adjacent mirror has a convex surface having negative power. The image projection device according to claim 5, wherein the image projection device is formed as a mirror. 8. A display element for displaying an image, a projection optical system for enlarging and projecting the image displayed by the display element, and a light flux relating to the image projected by the projection optical system is diffused. A screen for displaying the image so as to be observable, and sequentially arranged on an optical path between the projection optical system and the screen, each of which bends the optical path to collectively define a space through which the light flux passes. A plurality of mirrors that bend a plurality of times so as to reduce the volume, comprising: a mirror that, from among the plurality of mirrors, extends in a direction of a normal to the main surface of the screen. The first mirror with the furthest edge that is furthest away reduces the area of the reflective surface so that the farthest edge is closer to the screen in the direction of the normal than when formed as a plane. Along with The plurality of mirrors are formed as negative-power convex mirrors so that a required light beam spread can be obtained without elongating the optical path despite the reduced area of the projecting surface. Among them, the second mirror adjacent to the rear of the first mirror on the optical path corrects the eccentricity of the first mirror and spreads the light beam by the first mirror appropriately. An image projection device formed as a concave mirror having a positive power. 9. The image projection device according to claim 8, wherein the first mirror is a third mirror of the plurality of mirrors counted from the screen side. 10. A screen, a display element for displaying an image, a projection optical system for enlarging and projecting a partial image displayed by the display element, and a projection optical system on an optical path between the projection optical system and the screen. A first mirror surface arranged to project the partial image toward the screen, and a second mirror surface arranged to project the partial image onto the optical path toward the first mirror surface And a plurality of image projection units each comprising: and, on the screen, the plurality of image projection units convert the partial images so that adjacent partial images have a superimposed region on an edge thereof. By projecting each,
A multi-image projection device that displays a seamless image on the screen so as to be observable, among the plurality of image projection units, one of the image projection units adjacent to each other, the first mirror surface on one of the plurality of image projection units, The multi-image projector according to claim 1, wherein the second mirror surface is a mirror surface provided on each of the front and back main surfaces of the same flat plate member. 11. A multi-image projection apparatus for projecting a partial image while enlarging each of the partial images by a plurality of image projection units, wherein a chief ray of each partial image is a predetermined angle which is an inclination angle with respect to a normal set on a screen. A screen applicable to a multi-image projector configured to be incident at a launch angle, wherein a Fresnel-shaped portion made of a ridge in one direction is formed at a predetermined pitch along another direction perpendicular to the one direction. The one-dimensional Fresnel is formed such that the Fresnel-shaped portion is formed such that a principal ray incident at the launch angle is converted into a ray in a direction of a normal line set on the screen and emitted. Screen and a light beam obliquely incident on the light beam that has passed through the one-dimensional Fresnel screen is converted into a light beam that is diffused about a direction perpendicular to the main surface. In order to conversion, a screen, characterized by comprising a double-sided lenticular screen formed by arranging a lenticular shape portion at a predetermined pitch in both the main plane of the front and back. 12. The one-dimensional Fresnel projection device according to claim 1, wherein the multi-image projection device includes a plurality of display elements each having a plurality of display pixels arranged two-dimensionally in correspondence with the plurality of partial images. The Fresnel-shaped portion of the screen and the lenticular-shaped portion of the double-sided lenticular screen are defined as follows: the pitch of the display pixel projected on the screen in the other direction is P G, the pitch of the double-sided lenticular screen is P L, and the one-dimensional Fresnel The screen according to claim 11, wherein the screen is formed so as to satisfy a relationship of PG≥2PL≥4PF, where PF is a pitch of the screen.