JPH09146063A - Liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projector having an illumination optical system which is hardly deteriorated by the heat of a light source by arranging a polarization conversion optical system on the liquid crystal panel side of an optical integrator and keeping it at a distance from the light source. SOLUTION: The polarization conversion optical system is arranged on the liquid crystal panel side of the optical integrator so as to be kept at a distance from the light source 1. By such constitution, white random polarized luminous flux emitted from the light source 1 is reflected by a reflector 2 and the unnecessary wavelength band thereof is cut by an IR-UV cut filter 3. Thereafter, it is made incident on a first lens array 4. Then, the luminous flux from the light source 1 is split into the plural luminous fluxes, made incident on a polarizing beam splitter 5 and split into the luminous flux of two mutually orthogonally crossing linearly polarized components. Out of them, the luminous flux of the polarized component required for illuminating the liquid crystal panel is guided to a second lens array 7 constituting the optical integrator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector having a polarization conversion optical system and an illumination optical system including an optical integrator for obtaining a bright and uniform projected image.

[0002]

2. Description of the Related Art In the field of conventional liquid crystal projectors,
For example, as disclosed in JP-A-6-265887 or JP-A-7-120753, an illumination optical system including a polarization conversion optical system and an optical integrator for obtaining a projected image with a bright and uniform illuminance distribution is provided. Liquid crystal projectors that have are known.

[0003]

However, in the liquid crystal projector having the above-mentioned polarization conversion optical system and the illumination optical system including the optical integrator, the polarization conversion optical system is in the vicinity of the light source, so that it is easily deteriorated by heat. was there. It is an object of the present invention to provide a liquid crystal projector having an illumination optical system that is less deteriorated by heat of a light source even if a polarization conversion optical system and an optical integrator are used.

[0004]

In order to achieve the above object, the present invention provides a liquid crystal projector including a light source, an illumination optical system including a first lens array and a second lens array in order from the light source, and a liquid crystal panel. In the above, the polarization conversion optical system is arranged closer to the liquid crystal panel than the first lens array. According to the configuration of the present invention, by disposing the polarization conversion optical system on the liquid crystal panel side of the optical integrator and keeping it away from the light source, it is possible to reduce deterioration of the polarization conversion optical system due to heat of the light source.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. 1 is a configuration diagram of a first embodiment of the present invention, and FIGS. 2 to 5 are second to fifth embodiments of the present invention.
It is a main part block diagram of the illumination optical system of embodiment. In FIG. 1, a white randomly polarized light beam emitted from a light source 1 is reflected by a reflector 2 and an unnecessary wavelength region is cut by an IR-UV cut filter 3, and then a first lens array that constitutes an optical integrator. It is incident on 4. The light flux from the light source is split into a plurality of light fluxes by the first lens array 4 and is incident on the polarization beam splitter 5, and is split into two light fluxes of two linearly polarized light components orthogonal to each other. Among these, the liquid crystal panels 6a, 6
The light fluxes of the polarization components necessary for the illumination of b and 6c are guided to the second lens array 7 which constitutes the optical integrator.

In the case of the present embodiment, the light beam reflected by the polarization splitting surface of the polarization beam splitter 5 is the liquid crystal panel 6a,
If a light flux of a polarization component necessary for illumination of 6b and 6c and a polarization component that passes through the polarization beam splitter is required for illumination of the liquid crystal panel, that light flux may be used. As described above, since the light fluxes that reach the liquid crystal panels 6a, 6b, and 6c do not have the light flux of the unnecessary polarization component, it is possible to prevent unnecessary heat generation due to the unnecessary polarization component in the liquid crystal panel and prevent the deterioration of the liquid crystal panel. be able to. Therefore, it becomes possible to illuminate the liquid crystal panel with the light flux of the polarization component necessary for a larger amount of illumination than when the light flux of the unnecessary polarization component reaches the liquid crystal panel, and a brighter projected image can be obtained.

The light source 1 and the individual lenses on the second lens array 7 are in an optically conjugate relationship, and the image of the light source 1 is the second
An image is formed on each lens on the lens array 7 of, and each serves as a secondary light source. The light flux guided to the second lens array 7 is passed through the dichroic mirrors 8a and 8b.
It is separated into three wavelength bands of R, G and B. The light flux in the R wavelength band that has passed through the dichroic mirror 8a is reflected by the total reflection mirror 9a, and after passing through the field lens 10a,
The light flux of the G wavelength band reflected by the dichroic mirror 8b that illuminates the liquid crystal panel 6a is generated by the field lens 1
After passing 0b, the liquid crystal panel 6b is illuminated, and the light flux in the wavelength band of B that has passed through the dichroic mirror 8b passes through the total reflection mirrors 9b and 9c, the relay optical systems 11a and 11b, and the field lens 10c, and then the liquid crystal panel 6c. Illuminate.

Since the distance between the liquid crystal panel 6c and the second lens array 7 is different from the distance between the liquid crystal panels 6a and 6b and the second lens array 7, the relay optical system 11 is used.
The illumination state of the liquid crystal panel 6c is the same as that of the liquid crystal panels 6a and 6b by using a and 11b. The liquid crystal panel 6a by the field lenses 10a, 10b, 10c,
6b and 6c are telecentric illuminated.

Here, the individual lenses on the first lens array 4 and the liquid crystal panels 6a, 6b, 6c are in an optically conjugate relationship, and each light beam divided by the first lens array 4 is a liquid crystal. Since the panels 6a, 6b, 6c are superposed on each other, the liquid crystal panels 6a, 6b, 6c are illuminated with a uniform light amount distribution. Therefore, the liquid crystal panels 6a, 6
The R, G, and B images displayed on b and 6c are combined by the dichroic prism 12 and projected as a color image on the screen (not shown) by the projection lens 13 with a uniform illuminance distribution.

As described above, in the present embodiment, the polarization beam splitter and the optical integrator are used in the illumination optical system in order to obtain a projected image with a bright and uniform illuminance distribution. However, the polarization beam splitter constitutes the optical integrator. By arranging it between the first and second lens arrays and sharing the space occupied by the polarization beam splitter and the optical integrator, a space-saving illumination optical system is realized, and a very compact liquid crystal projector is realized.

In the present embodiment, the metal halide lamp is used as the light source 1, but it goes without saying that a xenon lamp or a halogen lamp may be used. Further, as shown in FIG. 2, a polarizing beam splitter 15 in which a prism side through which a light flux of a polarization component necessary for illumination of a liquid crystal panel does not pass is used, or a polarization plate formed of a flat plate as shown in FIG. If the beam splitter 25 is used, the weight of the polarization conversion optical system can be reduced. Further, as shown in FIG. 4, a polarizing plate 3 is used instead of the polarization beam splitter in the polarization conversion optical system.
5 and the total reflection mirror 39, or the configuration using only the polarizing plate 45 as shown in FIG. 5, the same effect can be obtained.

6 to 10 show the sixth to tenth aspects of the present invention.
It is a main part block diagram of the illumination optical system of embodiment. In FIG. 6, the randomly polarized light flux emitted from the light source 51 is
After being reflected by the reflector 52 and having an unnecessary wavelength band cut by the IR-UV cut filter 53, the light enters the first lens array 54 that constitutes an optical integrator. The light flux from the light source is split into a plurality of light fluxes by the first lens array 54, enters the polarization beam splitter 55, and is split into two light fluxes of two linearly polarized light components orthogonal to each other. Of these, the light flux of the polarization component necessary for illumination of the liquid crystal panel is reflected by the polarization splitting surface of the polarization beam splitter 55 in the present embodiment, and is guided to the second lens array 57 that constitutes the optical integrator. Illuminate. The light flux of the polarization component unnecessary for illumination of the liquid crystal panel that has passed through the polarization splitting surface of the polarization beam splitter 55 is reflected by the total reflection mirror 59, returned to the light source 51 section, and again reflected by the reflector 52, and then the polarization beam splitter 55. Be led to.

Here, a quarter wavelength plate 56 is provided between the reflector 52 and the polarization beam splitter 55,
The light flux of the polarization component unnecessary for the illumination of the liquid crystal panel is converted into the light flux of the polarization component required for the illumination of the liquid crystal panel. Therefore, the light beam guided to the polarization beam splitter 55 again is reflected by the polarization splitting surface this time, and the second lens array 5
7 is to guide the liquid crystal panel, and the light source 51
Energy can be effectively used, and a brighter projected image can be obtained.

Further, since the light flux of the polarization component unnecessary for illumination of the liquid crystal panel is returned to the light source 51 again, it is prevented from becoming stray light in the liquid crystal projector and causing ghost and flare. Further, as shown in FIG. 7, a total reflection concave mirror 69 is provided in place of the total reflection mirror 59 in the embodiment of FIG. 6, and a total reflection concave mirror 69 is condensed near the light source to generate a light flux of a polarization component unnecessary for illumination of the liquid crystal panel. When it is returned, it returns to the polarization beam splitter again in the same optical path as that of the original light source light, so that the utilization light rate of the light source light further increases.

As shown in FIG. 8, instead of the total reflection concave mirror 69, a combination of a convex lens 78 and a total reflection mirror 79 is used, or as shown in FIG. 9, a convex lens and a reflection surface 85a are integrally formed. Beam splitter 85
The same effect can be obtained by using. When the polarization beam splitter 85 is used, the number of parts can be reduced. Further, as shown in FIG. 10, the light flux returned by the reflecting concave mirror 69 may be returned to the polarization beam splitter not at the reflector 52 but at the reflecting surface 98a of the reflecting member 98. Further, due to the reflecting surface 98b of the reflecting member 98,
By returning to the reflector 52 the wasted light flux that does not directly reach the reflector 52 due to the light flux from the light source, the light source light can be used more effectively.

FIG. 11 is a schematic view of the essential parts of an illumination optical system according to the eleventh embodiment of the present invention. In FIG. 11, the light source 1
The white randomly polarized light beam emitted from 01 is reflected by the reflector 102, and the IR-UV cut filter 1
After the unnecessary wavelength range is cut by 03, the first lens array 10 forming the optical integrator is formed.
4 is incident. The light flux from the light source is divided into a plurality of light fluxes by the individual lenses of the first lens array 104,
It is incident on the corresponding individual lens of the second lens array 107. The light flux that has entered the second lens array 107 passes through the polarizing plate 105 that is a polarization conversion optical system and then illuminates the liquid crystal panel. Only the light flux of the polarization component necessary for illuminating the liquid crystal panel is transmitted through the polarizing plate 105.

Therefore, it is possible to prevent unnecessary heat generation by the light flux of the unnecessary polarization component in the liquid crystal panel, and prevent deterioration of the liquid crystal panel and the like. Therefore, it becomes possible to illuminate the liquid crystal panel with the light flux of the polarization component necessary for a larger amount of illumination than when the light flux of the unnecessary polarization component reaches the liquid crystal panel, and a brighter projected image can be obtained. Further, since the polarizing plate 105 is arranged on the liquid crystal panel side of the optical integrator, the polarizing plate can be spaced from the light source, and the influence of heat of the light source on the polarizing plate 105 can be reduced. Here, a polarizing beam splitter may be used instead of the polarizing plate.

[0018]

As described above, the present invention reduces the deterioration of the polarization conversion optical system due to the heat of the light source by disposing the polarization conversion optical system on the liquid crystal panel side of the optical integrator and keeping it away from the light source. Therefore, a liquid crystal projector with stable quality can be obtained. In addition, a compact liquid crystal projector can always be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of main parts of an illumination optical system according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a main part of an illumination optical system according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a main part of an illumination optical system according to a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of a main part of an illumination optical system according to a fifth embodiment of the present invention.

FIG. 6 is a configuration diagram of main parts of an illumination optical system according to a sixth embodiment of the present invention.

FIG. 7 is a configuration diagram of a main part of an illumination optical system according to a seventh embodiment of the present invention.

FIG. 8 is a configuration diagram of a main part of an illumination optical system according to an eighth embodiment of the present invention.

FIG. 9 is a configuration diagram of main parts of an illumination optical system according to a ninth embodiment of the present invention.

FIG. 10 is a configuration diagram of main parts of an illumination optical system according to a tenth embodiment of the present invention.

FIG. 11 is a configuration diagram of main parts of an illumination optical system according to an eleventh embodiment of the present invention.

[Explanation of symbols]

 1 Light Source 2 Reflector 3 IR-UV Cut Filter 4 First Lens Array 5 Polarizing Beam Splitter 6a Liquid Crystal Panel 6b Liquid Crystal Panel 6c Liquid Crystal Panel 7 Second Lens Array 8a Dichroic Mirror 8b Dichroic Mirror 9a Total Reflection Mirror 9b Total Reflection Mirror 9c Total reflection mirror 10a Field lens 10b Field lens 10c Field lens 11a Relay optical system 11b Relay optical system 12 Dichroic prism 13 Projection lens 15 Polarization beam splitter 25 Polarization beam splitter 35 Polarizing plate 39 Total reflection mirror 45 Polarizing plate 51 Light source 52 Reflector 53 IR -UV cut filter 54 First lens array 55 Polarizing beam splitter 56 Quarter wave plate 57 Second lens array 59 Total reflection mirror 9 total reflection concave mirror 78 lens 79 the total reflection mirror 85 a polarizing beam splitter 85a reflecting surface 98a reflecting face 98b reflecting surface 101 the light source 102 a reflector 103 IR-UV cut filter 104 first lens array 105 polarizing plate 107 second lens array

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hideki Nagata 2-3-13 Azuchi-cho, Chuo-ku, Osaka Osaka International Building Minolta Co., Ltd.

Claims (1)

[Claims] 1. A light source, an illumination optical system including a first lens array and a second lens array in this order from the light source, and a liquid crystal panel, and a polarization conversion optical system closer to the liquid crystal panel than the first lens array. A liquid crystal projector characterized by being arranged.