JP3211912B2 - Light source device for liquid crystal projector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device for a liquid crystal projector, and more particularly to a light source device for improving the use efficiency of light from a light source.

[0002]

2. Description of the Related Art In a light source of a liquid crystal projector, light from a light source is incident on a liquid crystal display panel with low loss. Is generated into a light beam distributed as described above, and this light is converted into linearly polarized light using a half-wave plate. The PBS and the half-wave plate are, for example,
As shown in the conceptual diagram of FIG.
Receives the light 22 from the light source, and splits the light 22 into transmitted light and reflected light by the PBS 23, and reflects the reflected light by the mirror 24, thereby emitting the light from the exit surface 25 having an aspect ratio of 3 to 4. This light is converted into linearly polarized light 27 by a half-wave plate 26 and is incident on the liquid crystal display panel.

[0003]

As described above, the PBS
When the light incident from the light source lamp is circular while the light incident surface of the light source is vertically long (aspect ratio is 3: 2), the light of the right and left portions of the light from the light source protrudes from the light incident surface of the PBS, and the light is used. The rate drops. In view of such a point, the present invention generates a circular light beam from the light source into a vertically long elliptical light beam corresponding to the shape of the incident surface of the PBS, and this light beam enters the PBS,
By generating a light flux having an aspect ratio of 3: 4 corresponding to the shape of the incident surface of the liquid crystal display panel, converting the light into linearly polarized light through a half-wavelength plate, and entering the liquid crystal display panel, a light source An object of the present invention is to provide a device that improves the light utilization rate.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is mounted on a base installed at an inclination angle of 34 degrees with respect to the optical axis of the light source light, and 135 degrees with respect to the optical axis. And a plurality of horizontally elongated strip-shaped cold mirrors having a tilt angle of about 3 and reflecting light generated by the plurality of cold mirrors into a vertically long elliptical shape having an aspect ratio of about 3: 2.
And a half-wave plate for converting light from the polarizing beam splitter into linearly-polarized light, and converting the light from the half-wave plate into an aspect ratio. An object of the present invention is to provide a light source device of a liquid crystal projector which is made to enter a three-to-four liquid crystal display panel.

[0005]

With the above construction, in the light source device of the liquid crystal projector according to the present invention, the circular luminous flux from the light source is set, for example, at a tilt angle of 34 degrees with respect to the optical axis of the light source light. The light is reflected by a plurality of strip-shaped cold mirrors mounted on a table and inclined at 135 degrees with respect to the optical axis to form a vertically long elliptical light beam having an aspect ratio of about 3 to 2, and a PB.
It is incident on S. This light beam is generated by the PBS into a horizontally long light beam having an aspect ratio of 3: 4, converted into linearly polarized light by a half-wave plate, and incident on a liquid crystal display panel having an aspect ratio of 3: 4. The light transmitted through the liquid crystal display panel is projected on a screen via a projection lens.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a light source device for a liquid crystal projector according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a conceptual diagram of a main part of an embodiment of a light source device of a liquid crystal projector according to the present invention. In the figure, reference numeral 1 denotes a light source lamp, for example, a white halogen lamp or the like is used. A reflecting mirror 2 has a substantially parabolic reflecting surface and condenses light from the light source lamp 1. Reference numeral 3 denotes a condenser lens that collects light from the light source lamp 1 and the reflecting mirror 2. Reference numeral 4 denotes a base, which is installed at an inclination angle of, for example, 34 degrees with respect to the optical axis of the light source light. Reference numeral 5 denotes a plurality of cold mirrors, each of which has a horizontally long rectangular shape, and is mounted on the base 4 so that the reflection surface is at 135 degrees with respect to the optical axis of the light from the light source. Reference numeral 6 denotes a PBS, which converts the vertically-elliptical light beam from the cold mirror 5 into a horizontally-elliptical light beam having an aspect ratio of 3: 4, converts the light beam into linearly polarized light by a half-wave plate, and enters the projector body 7. . The aspect ratio of the liquid crystal display panel incorporated in the projector main body 7 is 3 to 4, and is driven by a required video signal, and transmits or blocks linearly polarized light from the half-wave plate, and converts the light into a required image light. It is generated and projected on a screen via the projection lens 8.

Next, the operation of the light source device of the liquid crystal projector according to the present invention will be described. FIG. 2 is a conceptual diagram of a cold mirror portion. The light from the light source lamp 1 and the light reflected by the reflecting mirror 2 are condensed by a condensing lens 3 and are incident on a group of cold mirrors 5. The cold mirror 5 is a mirror that cuts ultraviolet rays and infrared rays and reflects only visible light, and is formed in a horizontally long strip shape. Place on. The light beam 11 from the light source is reflected by the group of cold mirrors 5 to form a light beam 12, which is incident on the PBS 6 via a not-shown ultraviolet / infrared cutoff filter or the like.

A base 4 on which the cold mirror group 5 is mounted.
By appropriately setting the inclination angle of, the shape of the light beam due to the reflection from the cold mirror 5 group can be made into a vertically long or horizontally long ellipse. That is, for example, when the light source is installed so as to have an angle of 34 degrees with respect to the optical axis from the light source (the angle θ with respect to the bottom surface is 90 degrees−34 degrees = 56 degrees), the circular light beam 11 from the light source becomes a cold mirror. Reflected by five groups, the shape of this light flux 12 is a frame 15 having an aspect ratio of 3 to 2 (shown by a thick line).
It becomes like a vertically long elliptical shape 14 corresponding to.

The shape of the frame 15 corresponds to the shape of the incident surface 21 of the PBS (aspect ratio 3 to 2) shown in FIG.
The incident light from the incident surface 21 is bisected by a PBS 23 that transmits 50% of the incident light and reflects 50% of the incident light, and is emitted from the emission surface 25 as light having an aspect ratio of 3: 4. The light is converted into linearly polarized light 27 by 26 and is incident on a liquid crystal display panel provided in the projector main body 7. This allows the light on both sides of the circular luminous flux from the light source to be incident on the incident surface of the PBS, so that most of the light from the light source can be used effectively and the utilization rate of the light from the light source is improved.

[0010]

As described above, according to the light source device of the liquid crystal projector according to the present invention, the circular luminous flux from the light source becomes a vertically long elliptical shape corresponding to the vertically long rectangle which is the shape of the entrance of the PBS. Since the light is generated as a light flux and is incident on the PBS, most of the light from the light source is incident on the PBS, the utilization efficiency of the light from the light source is improved, and the brightness of the image on the screen is improved.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of an embodiment of a light source device of a liquid crystal projector according to the present invention.

FIG. 2 is a conceptual diagram of a cold mirror portion used in a light source device of a liquid crystal projector according to the present invention.

FIG. 3 is a conceptual diagram of a polarizing beam splitter and a half-wave plate.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light source lamp 2 reflector 3 condensing lens 4 base 5 cold mirror (plural) 6 polarizing beam splitter and half-wave plate unit 7 projector body 8 projection lens

Claims (2)

(57) [Claims] An incident surface is mounted on a base having a required inclination angle with respect to an optical axis of light from a light source , and a reflecting surface is provided on the optical axis.
It has a tilt angle of 135 degrees for a plurality of the cold mirror horizontally strip for reflecting visible light, a polarization beam splitter for generating a light reflected by said plurality of cold mirror in the optical beam of the required aspect ratio A light source device for a liquid crystal projector in which light from a polarizing beam splitter is incident on a half-wave plate for converting light into linearly polarized light. Wherein the incident surface is mounted on a base installed at an inclination angle of 146 degrees to the optical axis of the source light, the reflecting surface is the
A plurality of horizontally long strip-shaped cold mirrors having an inclination angle of 135 degrees with respect to the optical axis and reflecting visible light, and a light beam generated by the plurality of cold mirrors into a vertically long elliptical shape having an aspect ratio of about 3: 2. And a half-wave plate for converting the light from the polarizing beam splitter into linearly polarized light, and a half-wave plate for converting the light from the polarizing beam splitter into linearly-polarized light. Light source device for a liquid crystal projector, wherein the light is incident on a liquid crystal display panel having an aspect ratio of 3: 4.