JP2000047325A - Reflection type image projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image projection device capable of translating a projection range to a screen without making a moving mechanism large-sized and lowering the luminance of an image which is projected even when a reflection type modulation element is used. SOLUTION: Illumination light emitted from a light source part 2 is made incident on a turning mirror 6 through a projection lens 5, reflected on the mirror 6 and made incident on a reflection type modulation element 3 through the lens 5. The reflected light modulated according to an image by the element 3 is transmitted through the lens 5 and passed through a side where the mirror 6 is not arranged to reach a screen 4. In order to shift the projection range, the element 3 is moved in parallel within a surface orthogonally crossed to an optical axis. By making it correspond to this movement, the turning action of the mirror 6 is adjusted so that the illumination light is efficiently made incident on the moved element 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image projection device such as a liquid crystal projector capable of shifting a projection image in a direction parallel to a screen, and more particularly to a reflection type image projection device using a reflection type image modulation device. About.

[0002]

2. Description of the Related Art Japanese Patent Laying-Open No. 5-27324 discloses a liquid crystal projector capable of shifting a projected image in a direction parallel to a screen. The liquid crystal projector disclosed herein makes a parallel light flux from a light source incident on a transmission type liquid crystal display panel, modulates the light, and projects the transmitted light on a screen via a condenser lens and a projection lens.

The condensing lens and the projection lens constitute a lens system that is telecentric with respect to the liquid crystal display panel as a single unit. The lens system is moved in parallel in a one-dimensional direction orthogonal to the optical axis to move the main body. Without moving
In addition, the projection range is shifted in a direction parallel to the screen without distorting the image.

[0004]

However, in the transmissive liquid crystal display panel used in the above-mentioned conventional liquid crystal projector, as the degree of integration increases, the area of a portion through which light is transmitted, such as a drive circuit and the like, is increased. Since the ratio of the area of the non-transmissive portion provided with the light-transmitting portion increases, there is a problem in that if the resolution is increased by using the same size modulation element, the light use efficiency is reduced.

In order to increase the resolution without lowering the light use efficiency, a large number of two-dimensionally arranged reflection type modulation elements, for example, a reflection type liquid crystal display panel and a small number of mirrors whose angles can be independently controlled. A digital micromirror device (DMD, a trademark of Texas Instruments Japan Limited) or the like may be used. This is because, in the reflection type modulation element, since the drive circuit and the like can be arranged on the back surface, the ratio of the reflection portion on the front surface can be kept high.

However, when a reflection type modulation element is used, it is necessary in principle that illumination light enters the modulation element from an oblique direction and light reflected in a direction different from that of the light source enters the projection lens. is there. For this reason, merely moving the projection lens by the mechanism disclosed in the above publication does not allow the reflected light to be efficiently captured by the projection lens, and the illuminance of the projected image is reduced, or a part of the image is A problem such as missing occurs. In order to shift the image without moving the projection lens, the modulation element may be shifted, but in this case, the illumination light must also be moved at the same time. However, when the light source is moved to move the illumination light, there is a problem that the moving mechanism becomes large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and is based on the premise that the projection range is shifted without distorting an image. It is another object of the present invention to provide a reflection-type image projection apparatus capable of moving a projection range in parallel with respect to a screen without increasing the size of a moving mechanism and without lowering the brightness of a projected image. I do.

[0008]

A reflection type image projection apparatus according to the present invention comprises a light source for emitting illumination light, a reflection type modulation element for modulating and reflecting illumination light from the light source in accordance with an image, and a reflection type projection device. A telecentric projection lens is arranged on the side of the reflection type modulation element that projects the light reflected by the modulation element onto the screen. A reflecting member for reflecting the illuminated light and entering the reflection type modulation element via a projection lens; first support means for movably supporting the reflection type modulation element in a direction perpendicular to the optical axis; Second support means for rotatably supporting the reflection member so that the light follows the movement of the reflection type modulation element.

According to the above arrangement, the projection range can be shifted by shifting the reflection type modulation element by the first support means, and the reflection member supported by the second support means can be shifted by the reflection type modulation element. , The illumination light can be efficiently incident by following the movement of the reflective modulation element.

The light source may be arranged on the same side of the projection lens as the reflection type modulation element or on the same side as the reflection member. In the former case, the illumination light passes through the projection lens, reaches the reflection member, is reflected by the reflection member, passes through the projection lens again, and enters the reflection type modulation element. In the latter case, the illumination light is incident on the reflecting member from a direction intersecting the optical axis without passing through the projection lens, passes through the projection lens, and is incident on the reflection type modulation element.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Two embodiments of a reflection type image projection apparatus according to the present invention will be described below. 1 and 2
1 shows a reflection-type image projection apparatus according to a first embodiment, FIG. 1 is a schematic diagram showing an overall configuration, and FIG. 2 is a lens diagram showing a specific configuration of a projection lens.

As shown in FIG. 1, an optical system of a reflection type image projection apparatus 1 according to a first embodiment includes a light source section 2 for emitting illumination light.
A reflection type modulation element 3 for modulating and reflecting illumination light from the light source unit 2 according to an image, and a projection lens 5 for projecting the light reflected by the reflection type modulation element 3 onto a screen 4
And a turning mirror 6 as a reflecting member that reflects illumination light and makes it incident on the reflection type modulation element 3 via the projection lens 5.

The projection lens 5 is a lens which is telecentric on the reflection type modulation element 3 side where the pupil on the reflection type modulation element 3 side is at infinity, and the turning mirror 6 is a stop position of the projection lens 5 on the screen 4 side. Thus, it is disposed on one side of the optical axis Ax of the projection lens, in this example, on the upper side in the figure.

The light source section 2 is arranged on the same side of the projection lens 5 as the reflection type modulation element 3, and includes a high-intensity lamp 2a such as a xenon lamp, a halogen lamp, a metal halide lamp, an ultra-high pressure mercury lamp, and a high-intensity lamp. A reflector 2b for directing the non-directional light from the lamp 2a as substantially parallel light to the reflection type modulation element 3 side, and a beam expander 2c for converting the beam diameter of the parallel light are provided.

The illumination light, which is parallel light emitted from the light source unit 2, is slightly inclined toward the projection lens 5 in a direction away from the optical axis Ax. This inclination causes the projection lens 5
Is converged on one side of the optical axis, in this example, the upper side in the figure, and enters the rotating mirror 6. The illumination light that has entered the rotating mirror 6 is reflected by the projection lens 5 side, passes through the projection lens 5 again, and enters the reflection type modulation element 3. At this time, the light that exits the projection lens 5 and travels to the reflective modulation element 3 is parallel light, and is parallel to the light traveling from the light source unit 2 to the projection lens 5.

The reflection type modulation element 3 is arranged perpendicular to the optical axis Ax, and the light reflected by this element is directed toward the projection lens 5 in the opposite direction to the incident light while maintaining a parallel state. The light enters the projection lens 5 at an inclination away from the optical axis.
At this time, the absolute value of the angle between the incident light and the optical axis Ax and the angle between the reflected light and the optical axis Ax are equal. Therefore, the reflected light from the reflection type modulation element 3 reaches the screen 4 through the side where the rotary mirror 6 is not provided, that is, the lower side in the figure at the stop position, with the optical axis Ax as a boundary, and forms an image. . At this stop position, the illumination light and the projection light are separated.

Since the reflection type modulation element 3 and the screen 4 are arranged perpendicular to the optical axis Ax of the projection lens 5, the reflection type modulation element 3 is polarized with respect to the optical axis Ax as shown in FIG. Even in the case of being arranged in the center, an image without distortion can be projected on the screen 4.

As the reflection type modulation element 3, a reflection type liquid crystal display panel or the above-mentioned digital micromirror device can be used. In this example, a reflection type liquid crystal panel is used. In a reflective liquid crystal display panel, it is sufficient to dispose the driving circuit and the like on the back surface, so that even if the degree of integration is high, it is not necessary to reduce the area ratio of the portion that reflects light. Compared with the case where the display panel is used, the light use efficiency can be increased if the size and the resolution are the same.

The device 1 of the first embodiment has a screen 4
In order to move the projection range parallel to the screen 4 in the vertical direction in the figure without distorting the image projected onto the screen 4, the reflection type modulation element 3 is shifted in the direction Y orthogonal to the optical axis of the projection lens 5. In order to change the direction of the reflected light in accordance with the shift of the reflection type modulation element 3, the rotation mirror 6 is supported so as to be rotatable around a rotation axis perpendicular to the plane of FIG. A second support mechanism 20 is provided.

To shift the projection range, the reflection type modulation element 3 may be translated in a plane perpendicular to the optical axis. However, if only the reflection type modulation element 3 is moved, the illumination light is reflected. The light cannot be effectively incident on the modulation element 3.
Although it is conceivable to widen the illumination range so as to cover the movement range of the reflection type modulation element 3, the light emitted from the light source cannot be used effectively, and the projected image becomes dark. Therefore, the turning mirror 6 is rotated and adjusted so that the illumination light is efficiently incident on the moved reflection type modulation element 3 in accordance with the shift of the reflection type modulation element 3.

As a result, the direction of the illumination light can be changed following the movement of the reflective modulation element 3, and the projection range is shifted without distorting the image while effectively using the light emitted from the light source. be able to. For example, when the reflection type modulation element 3 is arranged at a position indicated by a solid line in the figure, the rotating mirror 6 is set substantially perpendicular to the optical axis Ax. The projection light toward the screen 4 at this time is indicated by a solid line, and the projection range on the screen 4 is R1.

Here, for example, in order to shift the projection range to the lower side in the figure, the first support mechanism 10 is operated to shift the reflection type modulation element 3 to the position indicated by the broken line in the upper side in the figure. In response, the second support mechanism 20 is operated to rotate the rotating mirror 6 counterclockwise from the position shown by the solid line in the figure to the position shown by the broken line. As a result, the illumination light and the projection light reflected by the reflection type modulation element 4 pass through the path shown by the broken line in the figure, and the projection range on the screen becomes R2. Shift to the side.

Generally, in a projection device such as a liquid crystal projector, in order to prevent distortion of an image formed on a screen,
The screen and the modulator are set perpendicular to the optical axis of the projection lens. Then, when projecting an image from a position where the screen is looked up or looked down, the modulation element is disposed at a position decentered with respect to the optical axis. In such an eccentric arrangement, light only passes through approximately half the area of the projection lens, and the other areas are not used. First
In the optical system according to the embodiment, the area of the projection lens that has not been used in the optical system having such an eccentric arrangement can be effectively used to guide illumination light from the light source unit.

FIG. 2 is a lens diagram showing a specific configuration example of the projection lens 5 used in the first embodiment.
The projection lens 5 is configured by arranging a first group G1 having six lenses and a second group G2 having two lenses in order from the reflection type modulation element 3 side. The diaphragm is located between the first group G1 and the second group G2, and the rotating mirror 6 is arranged at this position.

Next, the configuration of a reflection type projection apparatus 1a according to a second embodiment will be described with reference to FIG. In the optical system according to the first embodiment described above, since the light source unit 2 and the reflective modulation element 3 are arranged on the same side with respect to the projection lens 5, interference with the light source unit 2 or illumination light In order to avoid interference with the optical path, the movement range of the reflective modulation element 3 is limited. Therefore, in the second embodiment, the light source unit 7 is rotated from the direction intersecting the optical axis without the rotation of the turning mirror 6 without the projection lens 5.
Is arranged at a position where illumination light is incident on the. Other configurations are the same as those of the first embodiment.

In the second embodiment, the light source unit 7 is composed of a high-intensity lamp 7a, a reflector 7b, and a condenser lens 7c, and is disposed on one side of the stop position of the projection lens 5 with the optical axis Ax as a boundary. Convergent light is made incident on the rotating mirror 6. The optical axis of the light source unit 7 is substantially perpendicular to the optical axis of the projection lens 5.

According to the arrangement shown in FIG. 3, the illumination light emitted from the light source unit 7 is incident so as to converge at the position of the rotating mirror 6, is reflected by this mirror, and is incident on the projection lens 5. The illumination light transmitted through the projection lens 5 is incident on the reflection type modulation element 3 as parallel light, is reflected there and is transmitted again through the projection lens 5, and a rotating mirror 6 is provided at the stop position with the optical axis Ax as a boundary. It reaches the screen 4 through the side that is not set, that is, the lower side in the figure, and forms an image. Here, for example, in order to shift the projection range to the lower side in the figure, similarly to the first embodiment, the first support mechanism 10 is operated to move the reflection type modulation element 3 to the upper broken line in the figure. And the second support mechanism 20 is operated accordingly to rotate the rotating mirror 6 counterclockwise from the position shown by the solid line in the figure to the position shown by the broken line. As a result, the illumination light and the projection light reflected by the reflection type modulation element 4 pass through the path shown by the broken line in the figure, and the projection range shifts downward from the state before the shift.

According to the second embodiment, it is not necessary to consider interference with the light source unit 7 and the illumination light when moving the reflection type modulation element 3, and it is possible to secure a wide moving range of the reflection type modulation element 3. Thus, the degree of freedom of the image forming position on the screen 4 can be increased.

[0029]

As described above, according to the structure of the first aspect, the projection range is shifted without distorting the image by shifting the reflection type modulation element perpendicularly to the optical axis. By making the illumination light incident on the reflection-type modulation element via the reflection member and the projection lens, the illumination light can be moved following the reflection-type modulation element only by rotating the reflection member, and the moving mechanism is enlarged. The luminance of the projected image can be kept high without causing the conversion.

According to the second aspect of the present invention, the illumination light is guided to the reflection member via the projection lens, so that it is not originally used in the optical system in which the modulation element is decentered with respect to the projection lens. The area of the projection lens can be effectively used for guiding the illumination light from the light source unit. Further, according to the third aspect of the present invention, the illumination light is made incident on the reflection member in a direction intersecting the optical axis, so that a wide moving range of the reflection type modulation element can be secured, and the image forming position on the screen can be freely set. The degree can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the entire configuration of a reflection type image projection apparatus according to a first embodiment.

FIG. 2 is a lens diagram showing a specific example of a projection lens of the apparatus of FIG.

FIG. 3 is a schematic diagram showing the entire configuration of a reflection type image projection apparatus according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reflection type image projection apparatus 2 Light source part 3 Reflection type modulation element 4 Screen 5 Projection lens 6 Rotating mirror 10 First support mechanism 20 Second support mechanism

Claims (3)

[Claims] 1. A light source that emits illumination light, a reflective modulation element that modulates and reflects illumination light from the light source according to an image, and projects the light reflected by the reflective modulation element onto a screen. A projection lens which is telecentric on the reflection type modulation element side, and which is arranged on one side of the projection lens at an aperture position with the optical axis of the projection lens as a boundary, and reflects the illumination light emitted from the light source to perform the projection. A reflecting member for entering the reflection type modulation element via a lens; first supporting means for movably supporting the reflection type modulation element in a direction perpendicular to an optical axis; and the reflection type modulation. And a second supporting means for rotatably supporting the reflecting member so as to follow the movement of the element. 2. The light source is disposed on the same side of the projection lens as the reflection type modulation element, and illumination light passes through the projection lens to reach the reflection member, and is reflected by the reflection member. 2. The reflection type image projection apparatus according to claim 1, wherein the light passes through the projection lens again and enters the reflection type modulation element. 3. The light source according to claim 1, wherein the light source is arranged at a position where illumination light is incident on the reflection member without passing through the projection lens from a direction intersecting the optical axis. Reflection type image projection device.