JPH02250080A - Light valve projector - Google Patents

Abstract

PURPOSE:To miniaturize a device and to improve 1st to third light efficiency of luminous flux by providing 1st - 3rd condensing optical systems guiding emitted light from a light source to corresponding light valves 1st to 3rd and color composing system composing the light from the light 1st - 3rd valves 1st to 3rd. CONSTITUTION:The green, blue and red light valves 9, 10 and 11 correspond to the 1st to 3rd light condensing optical systems 3, 4 and 5, respectively. The light emitted from the light source 1 is made incident on the plural light condensing optical systems 4 and 5 and irradiates the corresponding light valves 10 and 11. The light reflected by dichroic mirrors 6 and 7 placed behind the light condensing optical systems 4 and 5 returns to the position of the light source 1 and is made incident on the facing light condensing optical system 4 and 5 to increase light quantity. The light from the light valves 9 to 11 is composed at the color composing systems 12 and 13 and is enlarged by a projecting lens 14 and then forms a picture on a screen 15. Thereby, the device can be miniaturized and the efficiency in using the luminous flux can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a light valve projection device that can use a liquid crystal panel as a light valve.

As an example of a conventional technique, a projection device using a liquid crystal panel as a light valve will be described. As shown in FIG. 2, a conventional three-plate lens type liquid crystal color projection device includes a light source 1 and a reflecting mirror 2 for returning light emitted to the rear of the light source 1 to the light source 1.
, a condensing optical system 3 for guiding the light emitted from the light source 1 to a liquid crystal panel (described later), and a color separation system that combines a dichroic mirror that reflects red light and a dichroic ink mirror that reflects blue light. system 24, a green liquid crystal panel 25, a red liquid crystal panel 26, a blue liquid crystal panel 27, which are light valves, and the red and blue liquid crystal panel 26.
, the blue liquid crystal panel 27 has a structure in which a reflection mirror 8 guided from the color separation system 4, a dichroic ink mirror that reflects red light, and a dichroic mirror that reflects blue light are combined, and the liquid crystal panel 25, 26. It has a structure including a color synthesis system 29 for synthesizing light from 27, and a projection lens 10 for projecting images from liquid crystal panels 25, 26, and 27 onto a screen 31.

Problems to be Solved by the Invention One advantage of a liquid crystal projection device is that it can be made smaller than a projection device using a CRT.

The present invention realizes further miniaturization of the conventional three-plate lens type liquid crystal color projection device that has three light valves and one projection lens system, and increases the efficiency of using the luminous flux from the light source. The purpose is to

Means for Solving the Problems The light valve projection device of the present invention includes a first condensing optical system constituted by one or more spherical or aspheric lenses located on the axis connecting the light source and the projection lens; A second lens constituted by one or more spherical or aspheric lenses located on one or more axes intersecting the above-mentioned axis on the light source.
, a third condensing optical system, and two condensing optical systems arranged behind the second and third condensing optical systems that reflect the colors that the opposing condensing optical systems have but transmit other colors. It has a dichroic mirror.

One light valve corresponds to one condensing optical system, and light emitted from one light source enters the plurality of condensing optical systems and illuminates the corresponding light valve.

The light reflected by the dichroic mirror placed behind the condensing optical system returns to the light source position and enters the opposing condensing optical system from there to increase the amount of light. The light from the light valves is combined by a color synthesis system, magnified by a projection lens, and imaged onto a screen.

Effect: According to the light valve projection device of the present invention, the light emitted from the light source is incident on the first, second, and third condensing optical systems. Each focusing optical system converts diverging light from a light source into parallel light. The peripheral light path exits the first collection optic and illuminates the direct-line light valve. The red light path is such that the light directly enters the second condensing optical system, enters the third condensing optical system, is reflected by the red-reflecting dichroic mirror located behind the third condensing optical system, and is then reflected back to the third condensing optical system. There are two optical paths that enter the focusing optic from the rear, return to the position of the light source, and enter the second focusing optic. Of the light that exits the second condensing optical system, red light passes through a blue-reflecting dichroic mirror and illuminates a red light valve using two reflective mirrors.

The blue light path also illuminates the blue light valve in the same way as the red light path. The three light valves mentioned above are arranged in a U-shape, and the light from each light valve is combined by a color synthesis system composed of red-reflecting and blue-reflecting dichroic mirrors. The above-mentioned combined light enters the projection lens, and an enlarged image corresponding to the image on the light pulp is projected onto the screen.

Embodiment Hereinafter, a light valve projection device having a plurality of condensing optical systems according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a plan view of a light valve projection device according to an embodiment of the present invention.

In Figure 1, 1 is a light source, 2 is a reflecting mirror, 3 is a first focusing optical system composed of one or more spherical or aspherical lenses for the green optical path, and 4 is the first condensing optical system for the red optical path. A second condensing optical system composed of one or more spherical or aspherical lenses, and 5 a third condensing optical system composed of one or more spherical or aspherical lenses for the blue optical path. , 6 is a blue reflective dichroic mirror, 7 is a red reflective dichroic mirror, 8 is a reflective mirror, 9 is a peripheral light bulb,
10 is a light valve for blue, 11 is a light valve for red, 12 is a blue reflection dichroic mirror, 13 is a red reflection dichroic mirror, 14 is a projection lens system composed of a plurality of spherical or aspheric lenses, 15 is a screen.

To explain the green optical path, the light emitted from light source 1 is the first
Only the light corresponding to the image of the rim passes through the light valve 9, and only the light of the part corresponding to the image of the rim passes through the light bulb 9, which is collected by the condensing optical system 3 and becomes a parallel light flux to illuminate the rim light pulp 9. The zero-order red light passes through a color synthesis system consisting of a dichroic mirror 12 and a red reflective dichroic mirror 13, enters the projection lens 14, and projects a green image corresponding to the light valve 9 onto the screen 15. The optical path includes light that enters the second focusing optical system 4 from the light source 1 and light that enters the third focusing optical system 5 from the light source 1.

The parallel light exiting the third condensing optical system 5 enters a red reflective dichroic mirror 7. Red reflective dichroic mirror 7
The red light is reflected, but since it is incident as parallel light, the red light returns to the light source 1 along the path it has just taken and enters the second condensing optical system 4. The light flux exiting the second condensing optical system 4 passes through a blue reflection dichroic mirror 6, changes direction by 180 degrees by two reflection mirrors 8, and illuminates a red light valve 11, corresponding to a red image. Only the red light passes through the light valve 11 and is reflected by the red reflecting dichroic mirror 13, changed direction by 90 degrees, and enters the projection lens 14 to form an image corresponding to the light valve 11 on the screen 15. Project. The blue light path is transmitted and projected in the same way as the red light path.

According to the embodiment described above, the conventional color separation system is not required, the length in the depth direction can be shortened, and the disadvantage that the central part of the screen becomes dark due to the color separation system is eliminated. .

Effects of the Invention As described above, according to the light valve projection device of the present invention having a plurality of condensing optical systems, the color separation system can be omitted and it is very effective in downsizing and simplifying the light valve projection device. be. Conventionally, the color separation system used is composed of extremely thin gicchroic mirrors, so it is structurally weak, requires care even when assembled, and is expensive.

In addition, due to the structure of color separation systems, the central part becomes an ineffective part of the luminous flux, making the central part of the screen dark, and when it interferes with the ineffective part of the luminous flux at the center of the color synthesis system, a vertical bright line is generated at the center of the screen. . If this color separation system can be omitted,
Vertical bright lines no longer occur, and the phenomenon in which the central part of the screen becomes dark becomes only the ineffective part of the light flux of the color synthesis system, which is greatly reduced, and there is no need to minimize the ineffective part of the light flux at the center of the color synthesis system. The advantage of being able to omit the color separation system is not only for miniaturization, but also for simplifying the color composition system and improving the quality of images displayed on the screen.

[Brief explanation of drawings]

FIG. 1 is a plan view of a light valve projection device according to an embodiment of the present invention, and FIG. 2 is a plan view of a conventional technique. 1...Light source, 2...Reflector, 3...
...First condensing optical system, 4...Second condensing optical system, 5...Third condensing optical system, 6...
・Red reflective dichroic mirror 7... Blue reflective dichroic mirror, 8... Reflective mirror, 9I
25... Edge light bulb, 10.27...
... Blue light valve, 11.26 ... Red light valve, 12 ... Blue reflection dichroic mirror, 13 ... Red reflection dichroic mirror, 14.30. ...Projection lens system, 15.31.
...Screen, 24...Color separation system, 2
9...Color synthesis system. Name of agent: Patent attorney Shigetaka Awano (1 person) Figure 1

Claims (2)

[Claims] (1) A light source, first, second, and third light valves, a first condensing optical system for guiding the light emitted from the light source to the corresponding light valve, and a second condensing optical system. a color combining system that combines the lights from the first, second, and third light valves, and a projection lens that projects the combined light from the color combining system onto a screen. A light bulb projection device equipped with. (2) A first dichroic mirror and a reflecting mirror are installed behind the second condensing optical system to reflect the color required by the third light valve and transmit the color required by the second light valve. and a second dichroic mirror and a reflecting mirror that reflect the color required by the second light valve and transmit the color required by the third light valve are disposed behind the third condensing optical system. The light valve projection device according to claim (1).