JP2000075407A - Light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the light condensing loss in an incident section and to make the luminance of a light source device higher by providing the light source device with the incident surfaces of a rod integrator at the same number as the number of light sources and adopting the shape that the incident light from the respective incident surfaces is totally reflected at another incident surfaces. SOLUTION: This light source device has the two light sources 1a, 1b and the rod integrator 3. The radiation light from the two light sources 1a, 1b is made incident respectively on the incident surfaces 4b, 4a of the rod 3 by a reflector. The respective rays are thereafter totally reflected by another incident surfaces 4b, 4a and are introduced toward the exit surface 6. At this time, the greater part of the rays repeat the total reflection on the flank 5 of the rod 3 and thereafter arrive at the exit surface 6. The illumination unevenness existing at the time of incident is eliminated on the exit surface 6 and the uniform illumination light of the high luminance having brightness for two pieces of lamps is obtd. The focal position of the luminous flux by the reflector is set near the center of the surfaces at which the rays are totally reflected after the incidence on the rod 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a light source device used for an illumination optical system such as a liquid crystal projector.

[0002]

2. Description of the Related Art In a display device such as a liquid crystal projector, a clear light image is generally projected to every corner of a display screen, and therefore, a light source device with very little illumination unevenness is required. As one of the techniques for realizing such a light source device, a light source device using a rod integrator as shown in FIG. 5 has been conventionally known.

The light source device shown in FIG. 5 is composed of a lamp 10 as a light source, an elliptical reflector 20, and a rod integrator 30 made of a columnar glass material. Rod 3
0 incidence surface 40 is arranged. Then, based on the principle described below, uniform illumination light can be obtained.

[0004] Light rays emitted by the lamp 10 are collected by a reflector 20 on an incident surface 40 of a rod integrator 30. At the entrance surface 40, an image of the lamp 10 is formed, at which point the illuminance distribution is non-uniform. However, the luminous flux incident on the rod 30 repeats total reflection on the rod side surface 50, and the illuminance distribution and the angular intensity distribution are superimposed according to the number of times, and reaches the emission surface 60. For this reason, the light source image existing on the incident surface 40 disappears before reaching the emission surface 60, and uniform illumination light can be obtained.

In general, in a light source device, one of the important issues is to increase the luminance of the light output in addition to reducing the illumination unevenness. The simplest way to solve this is to increase the lamp wattage while using the same optical system as in FIG. However, this type of method is likely to shorten the life of the lamp. For this reason, as a method of using two lamps without changing the wattage of the lamp, a rod integrator provided with a partial introduction portion as shown in FIG. 6 is disclosed in JP-A-5-72628. .

The optical system shown in FIG. 6 is composed of two lamps 11a and 11b, reflectors 21a and 21b, a rod integrator 31, and a partial introduction part 42. The partial introduction part 42 is half the incidence surface 41 of the rod 31. Is covered with a partial introduction portion 42 made of a prism or a mirror.

According to such a configuration, light from one reflector 21a is directly condensed on the incident surface 41 as usual, and light from the other reflector 21b is incident on the incident surface 41 through the partial introduction portion 42. It is led to 41. Therefore, the luminous flux of two lamps enters the rod integrator 31,
The light output at the emission surface 61 can be doubled.

[0008]

However, in the rod integrator corresponding to the two lamps described above, the provision of the partial introduction portion at the rod incident portion causes the following adverse effects.

For example, when the partial introduction part is a glass prism having a vertex angle of 45 degrees, in the case of ordinary glass, when the incident angle of the light beam on the partial introduction part exceeds about 6 degrees, the total reflection on the prism inclined surface is reduced. Will not happen.

In general, in the case of an elliptical reflector, the angle of incidence of a light beam on the partial introduction portion is often in the range of ± 20 to ± 30 degrees. Therefore, in most applications, a part of the light beam is totally reflected by the prism slope. Loss of light quantity occurs.

In order to avoid this, a mirror or the like on which aluminum deposition is applied may be provided in the partial introduction part. However, since the entire energy of the lamp is collected in the vicinity of the partial introduction part, the vapor deposition film is self-absorbed. It becomes extremely hot. For this reason, the deposited film may be peeled off or the prism may be cracked, and there is a problem in reliability.

Further, if the partial introduction portion is formed integrally with the rod body from the protruding shape, it is difficult to polish the surface. After the two components are individually polished, they must be bonded. At this time, as with the case of the aluminum deposition, there is a problem in the heat resistance of the ordinary adhesive, and it is difficult to ensure the reliability.

In view of the above problems, the present invention provides a rod integrator having excellent workability and reliability which can be applied when a plurality of lamps are used. Is realized.

[0014]

According to the first aspect of the present invention, a plurality of light sources, a light condensing means for condensing light emitted from the light sources, and a light condensed by the light condensing means are provided. A light source device having rod integrators for emitting uniform light from an output surface, the same number of input surfaces of the rod integrator as the number of the light sources, and light incident from each of the incident surfaces is used as another input device. The above-mentioned problem is solved by forming a shape that is totally reflected on the surface.

According to a second aspect of the present invention, the above object is achieved by forming one incident surface of the rod integrator and another incident surface at a 60-degree angle to each other.

According to a third aspect of the present invention, the rod integrator has two incident surfaces, and the dividing direction of the incident surfaces is set to be a longitudinal direction of a cross-sectional shape of the rod integrator, thereby achieving the above object. Solve.

According to a fourth aspect of the present invention, the above-mentioned object is attained by arranging the focal position of the light beam by the light condensing means so as to be near the center of the surface which is totally reflected after entering the rod integrator.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 shows an embodiment of the light source device according to the present invention. As shown in FIG.
It comprises a pair of light sources 1a, 1b, reflectors 2a, 2b, and a rod integrator 3.

As the light sources 1a and 1b, for example, a discharge lamp such as a metal halide lamp, a xenon lamp, and a mercury lamp can be used.

However, the light source is not limited to these, and a fluorescent lamp, a halogen lamp, a light emitting diode or the like may be used.

Each of the reflectors 2a and 2b has an elliptical reflecting surface, and focuses the light emitted from the lamp placed at the first focal point at the second focal point. As such a light collecting means, for example, a combination of a parabolic mirror and a lens may be used other than the elliptical reflector.

The light emitted from the two light sources 1a, 1b is transmitted by the reflectors 2a, 2b to the incident surfaces 4a, 4b of the rod 3.
4b. Thereafter, each light beam is totally reflected by the other incident surfaces 4b and 4a, and is guided to the exit surface 6.
At this time, most of the light rays reach the emission surface 6 after repeating total reflection on the side surface 5 of the rod. For this reason. Exit surface 6
Thus, uneven illumination existing at the time of incidence is eliminated, and high-luminance and uniform illumination light having the brightness of two lamps can be obtained.

In this embodiment, the focal position of the lamp beam by the reflector is not set at the incident surface of the rod as in the prior art, but as shown in FIG. It is set near the center. This is not to simply increase the amount of light incident on the rod, but to maximize the amount of light effectively guided to the rod exit surface by total reflection.

FIG. 2 is a perspective view showing the shape of the rod integrator, which is the point of the present invention. The cross-sectional shape of the rod is a rectangle having a horizontal dimension H and a vertical dimension V. In the present embodiment, the aspect ratio is set to 16: 9 to correspond to a so-called wide screen display.

The rod incident portion is provided with two incident surfaces 4a and 4b forming an angle of 60 degrees with each other. These incident surfaces 4a and 4b divide the rod cross-sectional shape in the horizontal direction which is the longitudinal direction. As a result, the apparent aspect ratio when one incident surface (the side acting as the total reflection surface) is viewed from the other incident surface (the side acting as the incident surface) is close to a square of 8: 9, and is collected by the reflector. The emitted light is efficiently guided into the rod.

FIG. 3 shows a design example of the rod incident portion.
FIG. 4 shows the relationship between various shapes of an incident portion and angles at which a light beam enters a rod. In FIG. 3, the apex angle α of the rod incident portion is classified into three (A) to (C) based on 60 degrees.

FIG. 3A shows a case where the apex angle α is 60 degrees, which corresponds to the rod integrator shown in FIGS. In this case, the incident direction of the light beam may be perpendicular to the incident surface regardless of the refractive index of the rod material, and the opening angle β of the two reflectors is 120 degrees.

FIG. 3B shows a case where the apex angle α is larger than 60 degrees, and FIG. 3C shows a case where the apex angle α is smaller than 60 degrees. In these cases, the ray does not pass perpendicularly through the plane of incidence, and is refracted at the interface according to Snell's law. Therefore, if the apex angle and the refractive index of the rod are appropriately selected, the opening angle β of the reflector can be set to an arbitrary angle other than 120 degrees.

Although FIG. 3 shows the rod integrators all having an axially symmetrical shape, if the rod incident portion is made asymmetrical, the arrangement of the reflectors can be made asymmetrical, and the layout of the optical system can be made. Can be made more flexible.

In the above description, two light sources have been described. However, according to a configuration in which the same number of incident surfaces as the number of light sources are provided in the incident portion of the rod integrator, and the incident light beam is totally reflected on another incident surface, the number of lamps can be set to an arbitrary number.

For example, when using four light sources, a light beam emitted from the light sources may be incident from four directions using a rod integrator as shown in FIG. Also in this case, similarly to the above example, each light beam incident on the rod is totally reflected by another incident surface and guided to the rod exit surface. And light source 4
A light source with higher luminance can be realized by the light flux for each light.

As the shape of the rod integrator, a polygonal shape such as a hexagon, a circular shape, an elliptical shape, or the like may be used in addition to the rectangular shape as described above. Further, the cross-sectional shape may be different between the incident portion and the output portion, and the rod slope may be inclined. Further, the material of the rod is not limited to glass but may be a plastic material as long as the material has no problem in permeability and heat resistance.

[0033]

According to the first aspect of the present invention, in a light source device comprising a plurality of light sources and a rod integrator,
Since the rod can be formed only by polishing a single glass material, a rod integrator excellent in workability and heat resistance can be formed, and a highly reliable and high-luminance light source device can be realized.

According to the second aspect of the present invention, in a light source device including a plurality of light sources and a rod integrator, the layout of the optical system does not depend on the refractive index of the material of the rod. Becomes possible.

According to the third and fourth aspects of the present invention, in a light source device comprising a plurality of light sources and a rod integrator, the light-collecting loss at the incident portion is minimized, and the light source device has higher brightness. can do.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a light source device according to the present invention.

FIG. 2 is a perspective view of a rod integrator used in the light source device according to the present invention.

FIG. 3 is a diagram showing a cross-sectional shape of a rod integrator according to the present invention.

FIG. 4 is a perspective view of a rod integrator according to the present invention.

FIG. 5 is a diagram showing an example of a light source device using a rod integrator according to the related art.

FIG. 6 is a diagram illustrating an example of a light source device corresponding to two light sources using a partial introduction unit in the related art.

[Explanation of symbols]

 1a, 1b Lamp 2a, 2b Reflector 3 Rod integrator 4a, 4b Rod entrance surface 5 Rod side surface 6 Rod exit surface 10, 11a, 11b Lamp 20, 21a, 21b Reflecting mirror 30, 31 Rod integrator 40, 41 Rod entrance surface 42 part Introduction part 50 Rod side surface 60, 61 Rod exit surface

Claims (4)

[Claims] A plurality of light sources; a light condensing means for condensing light emitted from the light sources; and a light condensed by the light condensing means incident on an incident surface;
A light source device including a rod integrator that emits uniform light from an output surface, wherein the rod integrator has the same number of incident surfaces as the light sources, and has a shape in which light incident from each incident surface is totally reflected on another incident surface. A light source device, comprising: 2. The light source device according to claim 1, wherein one incident surface of the rod integrator and another incident surface are shaped so as to have an angle of 60 degrees with each other. 3. The rod integrator according to claim 1, wherein the rod integrator has two incident surfaces, and a dividing direction of the incident surfaces is a longitudinal direction of a cross-sectional shape of the rod integrator. Light source device. 4. The light source according to claim 1, wherein a focal position of the light beam by the light condensing means is arranged near a center of a surface which is totally reflected after being incident on the rod integrator. apparatus.