JP2001094905A - Multi-projection display apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-projection display apparatus that has a configuration capable of front projection and rear projection at the same time, a simple structure, and can adjust tilting on an image by the front projection without affecting the image of the rear projection and focus the projected image on an external screen and a rear screen at the same time. SOLUTION: This multi-projection display apparatus has an optical engine 4 that forms an image light in response to image information, a projection lens 5 that magnifies its image light to project it as a projection light, and a half mirror 3 that divides the projected light through transmission and reflection, leads the transmitted projected light to a rear face 2b of a rear screen 2 and the reflected projected light to a front face 9a of an external screen 9. The multi-projection display device has a configuration for adjusting a projected position of the reflected projection light onto the outer screen 9, by using a jig 8 to make the half mirror 3 turnable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-projection display device capable of simultaneously performing so-called front projection and rear projection.

[0002]

2. Description of the Related Art A multi-projection display device capable of simultaneously performing such front projection and rear projection has been proposed. This is described, for example, in Japanese Patent Laid-Open No. 6-18155.
As described in Japanese Patent Application Publication No. 8 (1996) -1994, as a multi-screen projection monitor, image light emitted from a projection lens is split by an optical splitting unit, and these split image lights are respectively placed on the back surfaces of a plurality of rear screens. There is a configuration that leads. Thus, even if there is one projection optical system from the light source to the projection lens, the image light can be enlarged and projected on two or more rear screens. In addition, by retracting the total reflection mirror constituting the optical splitting unit from the optical path, it is possible to enlarge and project from the window of the case to the external screen.

Here, a basic configuration of a conventional multi-projection display device capable of simultaneously performing such front projection and rear projection will be described below. FIG. 3 is a plan vertical sectional view showing a schematic configuration of a conventional multi-projection display device. In the figure, first, reference numeral 31 denotes a cabinet which forms an outer box of the apparatus, and 32 is disposed at a left portion inside the cabinet 31.
Denotes an optical engine, and 33 adjacent thereto is a projection lens. The optical engine 32 has a function of forming image light according to image information.

[0004] Further, a diagonally disposed 34 in front of the projection lens 33 (to the right in the figure) with respect to the optical path is provided on the front of the cabinet 31 on the side of the half mirror 34 (below the figure). Numeral 35 is a flat, transmissive rear screen, and 36 provided on the right side of the cabinet 31 to the right of the half mirror 34 is a cabinet opening.
In addition, 37 arranged on the right outside of the cabinet 31 is a flat external screen. Now, when the image light from the optical engine 32 is projected as projection light L by the projection lens 33, a part thereof is reflected by the half mirror 34,
The projection light L1 is projected on the rear surface 35b of the rear screen 35 (rear projection). At this time, the rear screen 35
An image is projected on the front surface 35a side of.

On the other hand, the remainder of the projection light L is transmitted through the half mirror 34 except for the attenuation, passes through the cabinet opening 36 as the projection light L 2,
7a (front projection). At this time, the front 3
An image is displayed on 7a. In this way, front projection and rear projection can be performed simultaneously, and images can be simultaneously observed on the rear screen and the external screen.

[0006]

However, in the configuration described in the above-mentioned Japanese Patent Application Laid-Open No. 6-181558 or the basic configuration of the conventional multi-projection display device described above, an external screen and a rear display are not provided. It is difficult to simultaneously focus the projected images on the screen.
Further, it is not possible to adjust the position of an image projected front on the external screen, that is, adjust the tilt.

In order to be able to adjust the tilt, for example, it is necessary to change the position of the projection lens and, if necessary, the position of the optical engine. Furthermore, even if the position of the projection lens and the optical engine is changed and the tilt is adjusted, the position of the image projected on the rear screen on the rear screen will be shifted as it is, so, for example, a half mirror is also linked to prevent it It is necessary to move the device, and the configuration of the device becomes large.

The present invention has been made in view of the above problems, and has a simple structure in which a front projection image and a rear projection image can be simultaneously formed without affecting the rear projection image. It is an object of the present invention to provide a multi-projection display device capable of adjusting the tilt and simultaneously adjusting the focus of projected images on an external screen and a rear screen.

[0009]

According to the present invention, there is provided an optical engine for forming image light according to image information, and an enlarged projection optical system for enlarging the image light and projecting it as projection light. Optical splitting means for splitting the projection light by transmission and reflection, guiding the transmitted projection light to the rear surface of the rear screen, and guiding the reflected projection light to the front surface of the external screen. The configuration according to claim 1, wherein a projection position of the reflected projection light on the external screen can be adjusted by making the optical splitting unit rotatable.

The optical splitting means is a half mirror, and the optical splitting means has a configuration according to a second aspect of the present invention.

Further, the enlarged projection optical system has a predetermined projection distance and an F-number having a depth of field including a projection distance range from the rear screen to the external screen. The structure of claim 3 described in the above.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front vertical sectional view schematically showing the configuration of an embodiment of the multi-projection display device of the present invention. Referring to FIG. 1, reference numeral 1 denotes a thin rectangular parallelepiped cabinet forming an outer box of the apparatus. Reference numeral 4 disposed in the lower portion of the cabinet 1 denotes an optical engine and reference numeral 5 denotes a projection lens. The optical engine 4
It has a function of forming image light corresponding to image information. The detailed configuration thereof will be described later.

Further, 6 disposed at the lower part on the right side of the cabinet 1 in front of the projection lens 5 (obliquely above and right in the figure) is a flat reflection mirror, and is disposed obliquely above and to the left as viewed from the total reflection mirror 6. The reference numeral 3 denotes a flat half mirror, the half mirror 3 is provided on the left side surface of the cabinet 1 adjacent to the left side, and the reference numeral 2 denotes a flat rear transmission screen, and the half mirror 3 is provided on the right upper half of the cabinet 1 right side. The provided 7 is a cabinet opening. Reference numeral 9 disposed obliquely to the upper right of the outside when viewed from the cabinet 1 is a flat external screen.

At the upper end of the half mirror 3, a jig 8 for rotating the half mirror 3 about one axis is provided. By rotating the half mirror 3, it is fixed. The so-called tilt adjustment described below can be performed. Now, when the image light from the optical engine 4 is projected by the projection lens 5 as projection light L shown by a solid line, it is first totally reflected by a total reflection mirror 6 as shown by a broken line. Further, a part thereof is reflected by the half mirror 3, passes through the cabinet opening 7 as the projection light L1, and is projected on the front surface 9a of the external screen 9 (front projection).
At this time, an image is displayed on the front surface 9a.

In this case, the half mirror 3 is rotated by the jig 8 from the state shown by the solid line to the state shown by the dotted line as shown by the arrow A, and is fixed at a desired position, so that the projection light L1 is obtained. From L1a represented by a dotted line to L1b represented by a dashed line,
In this example, the vertical adjustment can be performed in the vertical direction.
The configuration in which the half mirror 3 is rotated about one axis is not limited. For example, if the half mirror 3 can be rotated in multiple axes, the projection position on the external screen 9 can be changed. The tilt can be adjusted not only vertically but also horizontally and diagonally.

On the other hand, the rest of the projection light L passes through the half mirror 3 except for the attenuation, and
(Rear projection). At this time, an image is projected on the front surface 2a side of the rear screen 2. In this way, front projection and rear projection can be performed simultaneously,
In each of the rear screen and external screen,
Images can be observed simultaneously. Further, even if the tilting is adjusted by rotating the half mirror 3 as described above, the light transmitted through the half mirror 3 is not affected.
Adjustment of the projection position on the rear screen 2 is unnecessary.

As described above, the image projected on the front screen on the external screen is based on the projection light reflected by the half mirror, and the image projected on the rear screen on the rear screen is based on the projection light transmitted through the half mirror. Therefore, the images viewed from the front are not reversed left and right. Further, the total reflection mirror 6 is not always required. This total reflection mirror 6 is a means for compactly organizing the configuration of the optical system in the cabinet 1. If there is enough space, it is removed and the projection light L is directly projected on the half mirror 3. Is also good. However, since the image is inverted left and right as it is, a means for correcting this is separately required.

FIG. 2 is a view schematically showing a schematic configuration of the optical engine 4. In the figure, 21 is a lamp as a light source, and 22 is a reflector arranged so as to surround the lamp 21. Reference numeral 27 denotes a UV cut filter that is disposed so as to cover the light emission port 22a of the reflector 22, and that cuts ultraviolet light included in light from the light source. An integrator 28 is arranged behind the UV cut filter 27 (to the right in the figure).
This is to optically optimize the light from the light source using a lens array or the like so that the light from the light source becomes as nearly uniform as possible. Note that a rod prism or the like may be used instead of the integrator.

Reference numerals 23a and 23b disposed behind the integrator denote flat dichroic mirrors for separating the light from the light source, respectively, and 24a, 24b and 24.
c is a flat total reflection mirror for guiding the color-separated light to a display panel described later, 25a, 25b, and 25c are display panels that modulate the color-separated light to form image light, and 26 indicates each image light. This is a dichroic prism that synthesizes colors.
Each of the display panels is disposed so as to face three predetermined surfaces of, for example, a cubic dichroic prism 26.

In the above configuration, the white light from the lamp 21 passes through the UV cut filter 27 directly or after being reflected by the reflector 22, and further becomes almost uniform substantially parallel light by the integrator 28. The light enters the dichroic mirror 23a at approximately 45 degrees. Here, of the white light, red light R indicated by a solid arrow is selectively reflected, and green light G indicated by a broken arrow and blue light B indicated by a dotted arrow are transmitted. The red light R color-separated by the dichroic mirror 23a is reflected by a total reflection mirror 24a, and then irradiates a display panel 25a displaying a red image. After being optically modulated according to the image information by the display panel 25a, the light is transmitted therethrough and enters the dichroic prism 26.

On the other hand, the green light G and the blue light B transmitted through the dichroic mirror 23a are
3b is incident at approximately 45 degrees. Here, green light G is selectively reflected, and blue light B is transmitted. The green light G color-separated by the dichroic mirror 23b irradiates a display panel 25b that displays a green image. And
After being optically modulated in accordance with the image information by the display panel 25b, the light is transmitted therethrough and enters the dichroic prism 26.

Further, the blue light B transmitted through the dichroic mirror 23b is sequentially reflected by total reflection mirrors 24b and 24c, and thereafter, a display panel 25c for displaying a blue image.
Is irradiated. After being optically modulated in accordance with the image information by the display panel 25c, the light is transmitted therethrough and enters the dichroic prism 26. In this manner, the image lights of the respective colors incident on the dichroic prism 26 from the three directions are finally synthesized here, and are respectively given as predetermined color image light to the rear screen 2 and the external screen 9 by the projection lens 5 of FIG. Enlarged projection at magnification.

As described above, the configuration of the optical engine according to the present embodiment is such that three display panels are respectively RGB.
It is a so-called three-plate type that modulates each color. Further, a transmissive liquid crystal display element is used as a display panel. However, the present invention is not limited to such a configuration, and may be a so-called single-panel type, or the display panel may be configured as another optical system using a reflective liquid crystal display element or a display element other than liquid crystal. Is also good.

In the projection system of the conventional multi-projection display device as described above, even if it is attempted to simultaneously focus the front projection image and the rear projection image on the external screen and the rear screen, respectively, the respective projection distances may be reduced. If different, it was difficult. Therefore, it is difficult to simultaneously use the projected images on each screen,
The benefits of multi-projection have not been fully exploited. Therefore, in the present embodiment, by increasing the F number in the projection lens, the depth of focus and the depth of field are increased, so that focusing is not required within a certain projection distance. The principle and specific examples will be described below.

In general, a lens focuses an image of a subject on the optical axis on an image plane, but it also appears that a certain area before and after a point at which the object is focused is in focus. This is because if the blur of the image is smaller than a certain amount, it looks as if the subject is in focus. The magnitude of this blur amount is called an allowable circle of confusion. The range before and after the image plane side where the blur is smaller than the permissible circle of confusion is called the depth of focus. Further, a range on the subject side for forming an image within the depth of focus is called a depth of field. All the objects within this depth appear as if they were in focus.

In this embodiment, the screen is on the object side, and the display panel is on the image plane side. The depth of field at this time is obtained by the following equation. Lr = δ · FNO · L ² / (f ² −δ · FNO · L) Lf = δ · FNO · L ² / (f ² + δ · FNO · L) d = 2δ · FNO

Here, Lr: rear depth of field Lf: front depth of field f: focal length of the projection lens FNO: F number δ: allowable confusion circle L: projection distance d: depth of focus Lr + Lf is the depth of field.

Here, the permissible circle of confusion is considered to be twice the pixel pitch at which the display panel can resolve black and white. For example, 1.
Since the pixel pitch of the 3-inch panel is 0.026 mm,
Let the allowable circle of confusion be δ = 0.052 mm. At this time, in a projection lens having a focal length f = 20 mm and a projection distance L = 800 mm, considering three types of F-numbers F = 2, 4, and 8, the rear depth of field Lr and the front depth of field are obtained from the above equations. Lf is as follows.

[F-number] [Back Depth of Field Lr] [Front Depth of Field Lf] 2 210 mm 137 mm 4 570 mm 235 mm 8 3962 mm 363 mm

Thus, when the F-number reaches 8,
It can be seen that a considerable depth, particularly a rear depth of field, can be obtained. With such a configuration, in the present embodiment, it is possible to adopt a configuration having a depth of field that includes the projection distance range from the rear screen to the external screen, and focus within a certain projection distance. It is possible to obtain the same effect as adjusting the focus of the projected images on the external screen and the rear screen at the same time without performing the alignment.

In the present embodiment, the magnifying projection optical system is constituted by using the projection lens 5, but the magnifying projection optical system may be constituted by combining a plurality of aspherical mirrors. An enlarged projection optical system may be configured by combining with a spherical mirror.

[0032]

As described above, according to the present invention,
In a configuration where front projection and rear projection can be performed simultaneously, with a simple structure, it is possible to adjust the tilt of the front projection image without affecting the rear projection image, and within a certain projection distance If so, it is possible to provide a multi-projection display device that can achieve the same effect as focusing the projected images on the external screen and the rear screen at the same time without focusing.

[Brief description of the drawings]

FIG. 1 is a front vertical sectional view schematically showing a configuration of an embodiment of a multi-projection display device of the present invention.

FIG. 2 is a diagram schematically showing a schematic configuration of an optical engine.

FIG. 3 is a plan vertical sectional view showing a schematic configuration of a conventional multi-projection display device.

[Explanation of symbols]

 Reference Signs List 1 cabinet 2 rear screen 3 half mirror 4 optical engine 5 projection lens 6 total reflection mirror 7 cabinet opening 8 jig 9 external screen 21 lamp 22 reflector 23a, 23b dichroic mirror 24a, 24b, 24c total reflection mirror 25a, 25b, 25c Display panel 26 Dichroic prism 27 UV cut filter 28 Integrator

Claims (3)

[Claims] 1. An optical engine for forming image light according to image information, and an expansion projection optical system for expanding the image light and projecting it as projection light, wherein the projection light is divided by transmission and reflection. Optical splitting means for guiding the transmitted projection light to the rear surface of the rear screen, and guiding the reflected projection light to the front surface of the external screen. A projection position of said projected light on said external screen is adjustable. 2. The multi-projection display device according to claim 1, wherein said optical splitting means is a half mirror. 3. The enlarged projection optical system has a predetermined projection distance and an F-number having a depth of field including a projection distance range from the rear screen to the external screen. The multi-projection display device according to claim 1 or 2.