JPH0553199A - Light guiding device - Google Patents

Abstract

PURPOSE:To improve uneven luminance of mainly a peripheral part of an image of a liquid crystal projector device. CONSTITUTION:Light from the center part of a light source 1 passes through a roughly cylindrical light guiding part 5 and the center part of an annular light guiding lens 11 and goes straight on in the direction of an optical axis 4. Also, light from a peripheral part of the light source opposed to the light guiding part is made incident on an incident surface part 6 consisting of a transparent acryl resin, etc., and part of the light incident at an angle being less than a total reflection angle is refracted in the direction of an emitting surface part 7 by an interface. These light beams are made incident on a hollow part 10 consisting of water, etc., whose refractivity is higher than that of the acryl resin, etc., which comes into contact with the incident surface part, and further refracted in the direction of the emitting surface part by an interface to water. Also, the light refracted in the direction of a cylindrical inside surface part 8 or a cylindrical outside surface part 9 is reflected thereby, and the greater part thereof is emitted from the emitting surface part consisting of glass, etc., whose refractive index is similar to water together with the light which reaches directly. The light from the emitting surface part is made incident on the light guiding lens, guided to a range of an angle set by the light guiding lens, and irradiates uniformly a liquid crystal panel, etc., together with the light which passes through the center part.

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 device, and more particularly to a light guide arranged in front of a light source for improving brightness of an image projected on a screen and reducing unevenness in brightness of the image.

[0002]

2. Description of the Related Art In a liquid crystal projector device, a metal halide lamp or the like is used as a light source for illuminating a liquid crystal panel, and this lamp is placed in the vicinity of the focal point of a reflecting mirror having a parabolic reflecting surface so that the amount of light emitted from the lamp is large. The part outputs to the front and enters the liquid crystal panel. However, when the center of the light emission of the lamp is placed near the focal point of the reflecting mirror, some of the light from the peripheral portion of the lamp is diffused and does not enter the liquid crystal panel. Only about 2 can be used. Therefore, when the optical axis of the light is set to be in the center of the liquid crystal panel, the liquid crystal panel 52 is arranged from the light source 51 as shown in the conceptual diagram of the brightness distribution of the image shown in FIG.
The brightness distribution of the image 53 that is generated by being incident on is such that the central part is bright and the peripheral part is gradually darkened as shown by the curve 54.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and collects light that is diffused in the periphery and does not enter the liquid crystal panel, thereby increasing the brightness of the peripheral portion of the image and The present invention provides a light guide for installation in front of a light source that improves the brightness of the entire image.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is a liquid crystal projector device in which light from a light source is incident on a liquid crystal panel driven by a video signal, converted into image light and projected on a screen. In, the light is incident on the peripheral portion of the optical path from the light source portion, which is substantially cylindrical and hollow, and has an incident surface facing the light source portion and an inner diameter substantially the same as the incident surface and an outer diameter smaller than the outer diameter of the incident surface. A light emitting surface for emitting light from a surface in the optical path direction, the cylindrical portion excluding the light emitting surface is formed of a substantially transparent first light guide body having a first refractive index,
The exit surface is formed of a second transparent material having a second refractive index larger than the first refractive index and is substantially transparent, and the hollow portion has a third light guiding body having a refractive index similar to that of the second light guiding body. The present invention provides a light guide configured by a light guide portion formed by filling with a light guide lens, and a light guide lens facing the light exit surface and having an annular shape substantially the same in inner diameter as the light exit surface.

[0005]

With the above construction, in the light guide according to the present invention, the light emitted from the light source and diffused to the peripheral portion is guided in the optical axis direction and is made incident on the liquid crystal panel. It increases the total amount of light incident on the panel and reduces the unevenness of the distribution of the incident light amount.

[0006]

Embodiments of the light guide according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a main part of an embodiment of a light guide according to the present invention. In the figure, reference numeral 1 denotes a light source, which reflects white light emitted from the metal halide lamp 2 or the like on a parabolic reflecting surface of the reflecting mirror 3 and outputs it in the direction of the optical axis 4. Reference numeral 5 denotes a light guide portion, which has an incident surface portion 6 facing the light source 1 for allowing the light from the light source 1 to enter, and an emitting surface portion 7 for emitting the light from the incident surface portion 6 in the direction of the optical axis 4. A cylindrical outer side portion 9 having a cylindrical shape and having an inner diameter of a cylindrical inner side portion 8 between the entrance surface portion 6 and the exit surface portion 7 is a uniform diameter, and the exit surface portion 7 side is gradually smaller in diameter than the outer diameter on the entrance surface portion 6 side,
The incident surface portion 6, the inner cylindrical portion 8 and the outer cylindrical portion 9 are formed of a transparent material having a required refractive index, for example, acrylic resin, and the outgoing surface portion 7 has a higher refractive index than the incident surface portion 6 and the like. It is made of a transparent material such as glass. The hollow portion 10 surrounded by the incident surface portion 6, the inner cylindrical portion 8, the outer cylindrical portion 9 and the outgoing surface portion 7 has a refractive index substantially similar to that of the glass used for the incident surface portion 7.
For example, water (pure water) is filled. It should be noted that the outer surface of the cylindrical outer portion 9 is covered with a highly-reflecting film such as an aluminum vapor-deposited film to reflect the light penetrating the cylindrical outer portion 9 to reflect the hollow portion 10.
To return to. Reference numeral 11 denotes a light guiding lens, which is formed by removing the central portion of the convex lens so as to have an inner diameter substantially the same as that of the cylindrical inner portion 8 and forming an annular shape, or the central portion has a uniform thickness,
The light is prevented from refracting in this portion, and the light from the light emitting surface 7 is guided in the direction of the optical axis 4, and the light source 1 passing through the inner side of the cylindrical inner side 8 at the center of the ring is used. Through the light.

Next, the operation of the light guide according to the present invention will be described with reference to FIG. The figure is a diagram for explaining the optical path and the brightness distribution of the image when the light guide according to the present invention is arranged in the front part of the light source 1. Light from the peripheral part of the light source 1 facing the incident surface part 6 is guided. It is incident on the incident surface portion 6 of the portion 5. Since the incident surface portion 6 is formed of a transparent acrylic resin or the like having a refractive index higher than that of air, light incident at an angle larger than the total reflection angle of the acrylic resin is directed toward the emission surface portion 7 at the interface between the air and the acrylic resin. Refract. Then, the light passing through the acrylic resin and incident on the hollow portion 10 filled with water or the like having a higher refractive index than the acrylic resin is further refracted at the interface between the acrylic resin and water in the direction of the emission surface portion 7, The light exits in the direction of the optical path through almost all of the exit surface 7 made of transparent glass or the like having a refractive index close to that of the above. Further, the light reflected on the acrylic resin surface is reflected again on the opposite acrylic resin surface, and these are appropriately repeated and emitted from the emission surface portion 7. The light that has passed through the outer cylindrical portion 9 is reflected by the surface of the outer cylindrical portion 9 that is provided, for example, a vapor-deposited film of aluminum, and is reflected in the direction of the emission surface 7. Is emitted from the emission surface 7 together with other light.

The light from the emission surface portion 7 is incident on the light guide lens 11 which is formed in an annular shape and is opposed to the light guide lens 11. Light guide lens
The focal length of 11 is appropriately set so that most of the light from the emission surface portion 7 is incident on the range 21 centered on the peripheral portion of the liquid crystal panel 22. Further, the light passing through the light guide portion 5 and the central portion 25 of the light guide lens 11 directly illuminates the liquid crystal panel 22. As a result, in the luminance distribution of the image 23 by the liquid crystal panel 22, as shown by the curve 24, the brightness particularly in the peripheral portion is increased and the unevenness of the luminance is reduced.

FIG. 3 is a cross-sectional view of an essential part of an example in which the light guide according to the present invention is mounted on a liquid crystal projector device. That is, the white light from the light source 1 is installed in the front of the light guide.
The light is guided through 31 (constituted by the light guide section 5 and the light guide lens 11), reflected by a cold mirror 32 for removing heat rays, further removed by a cold filter 33, and then incident on a dichroic mirror 34. Only the blue light B is reflected upward. The blue light B is reflected to the right by the mirror 35 and is a condenser lens.
Liquid crystal panel 37 driven by the video signal of the primary blue color via 36
Incident on. On the other hand, the green light G of the light that has passed through the dichroic mirror 34 is reflected upward by the dichroic mirror 38 and enters the liquid crystal panel 40 driven by the video signal of the green primary color via the condenser lens 39. Further, the red light R that has passed through the dichroic mirror 38 enters the liquid crystal panel 42 driven by the video signal of the red primary color through the condenser lens 41. The blue image light generated by the liquid crystal panel 37 is combined with the green image light by the liquid crystal panel 40 by the dichroic mirror 43, and then reflected by the mirror 44 in the upward direction.
The red image from 42 is combined via the dichroic mirror 45 and projected on the screen by the projection lens 46.

[0010]

As described above, according to the light guide according to the present invention, among the light emitted from the light source, the light which does not enter the liquid crystal panel and diffuses to the periphery is mainly focused on the peripheral portion of the liquid crystal panel. Since the light is guided so as to be incident on the range of light, the light is condensed so that the absolute amount of the light incident on the liquid crystal panel surface increases and the distribution of the incident light becomes uniform. In the liquid crystal projector device using, the brightness of the image projected on the screen is improved, and particularly, the brightness of the peripheral portion, which is conventionally darker than the central portion, is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an embodiment of a light guide according to the present invention.

FIG. 2 is a diagram for explaining a luminance distribution of an image using the light guide according to the present invention.

FIG. 3 is a conceptual diagram of a main part for explaining a configuration of a liquid crystal projector device.

FIG. 4 is an example of a luminance distribution of a conventional image.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 5 Light guide section 6 Incident surface section 7 Outgoing surface section 8 Inner cylinder section 9 Outer cylinder section 10 Light guide filling section 11 Light guide lens

Claims (1)

[Claims] 1. In a liquid crystal projector device, in which light from a light source unit is incident on a liquid crystal panel driven by a video signal, converted into image light and projected on a screen, the liquid crystal projector device is disposed in a peripheral portion of an optical path from the light source unit. A cylindrical and hollow entrance surface that faces the light source and an exit surface that has an inner diameter that is substantially the same as the entrance surface and has an outer diameter that is smaller than the outer diameter of the entrance surface for exiting light from the entrance surface in the optical path direction. And a cylindrical portion excluding the emission surface is formed of a first transparent material having a first refractive index and is substantially transparent, and the emission surface is substantially transparent having a second refractive index larger than the first refractive index. A light guide portion formed of a second light guide body, the hollow portion being filled with a third light guide body having a refractive index similar to that of the second light guide body; A light guide comprising a light guide lens having the same inner diameter and an annular shape.