JP2004198711A - Light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact light source device capable of emitting illuminating luminous flux having an appropriate NA (numerical aperture). <P>SOLUTION: The light source device is provided with a light valve 12, an elliptical reflection mirror 14 where the light valve 12 is arranged in the center of either ellipse of an elliptical rotating body and which is cut in almost the center between the centers of two ellipses, an aperture plane mirror 22 arranged at the aperture part of the reflection mirror 14, a filter reflector 24 arranged in a conical area linking the aperture part and the center of the other ellipse and inclined by 45° to an optical axis linking the centers C1 and C2 of the ellipses of a lens, and a light density uniformizing means where an incident surface 32 is arranged at a position conjugate to the center of the other ellipse on the reflection optical axis O2 of the reflector 24. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light source device used for an electronic device projector or the like, and more particularly, to a light source device that has a small loss of light amount and can withstand continuous use for a long time.
[0002]
[Prior art]
In a light source device of a current electronic device projector, a reflecting mirror such as a spherical surface, a parabolic surface, or an elliptical surface is used to reflect a light beam from a light valve in an arbitrary direction of an illumination system. However, at present, increasing the amount of light, high contrast, and miniaturization of the electronic device projector itself are very important design factors. In order to reduce the size in particular, light tunnels and glass rods are used in the integrator of the illumination system. Often. When a light tunnel or a glass rod is used, an elliptical mirror is the simplest structure for the light valve, and it is desirable.
[0003]
On the other hand, in order to further improve the efficiency of the illumination optical system when an elliptical mirror is used, it has been proposed to arrange an aperture plane reflecting mirror having an inner surface as a reflecting surface at the opening of the elliptical mirror ( For example, see Patent Document 1)
[0004]
[Patent Document 1]
JP-A-6-160613
[Problems to be solved by the invention]
What is important in reducing the size of the electronic device projector is that the light valve and the light tunnel or the glass rod are arranged in parallel so that the overall length of the illumination system itself is not long.
Furthermore, in order to obtain a large amount of illumination, it is necessary that the direct light beam from the light valve and the reflected light beam from the elliptical reflecting mirror enter the light tunnel at a high NA (aperture), for example, NA ≧ 0.3. .
[0006]
Further, when a high NA light beam is made incident on a visible reflection mirror at 45 ° incidence, there is a problem that high reflection efficiency cannot be obtained because the visible reflection mirror has a dielectric multilayer film (10 layers or more). .
In addition, when the display device is a liquid crystal device, since polarization becomes a problem, it is necessary to consider the limitation of the NA value in the polarization conversion system and the like in the illumination optical system of the electronic device projector main body.
Further, in the case where the display device is a DHD, if a configuration with a high NA by a reflecting mirror is employed, the inclination angle of the DHD is limited, and consequently, unnecessary stray light flux increases, which is not preferable in design.
[0007]
Therefore, high efficiency and high NA of the illumination optical system do not always coincide with each other, and this is a major problem particularly in an electronic device projector for a liquid crystal display device. For example, in order to achieve high contrast, it is necessary to improve the characteristics of the liquid crystal panel and the performance of the prism in the illumination system. In addition, enlargement of the electronic device projector is inevitable.
Under these circumstances, a desired amount of light can be obtained by irradiating a light beam with a high NA to the light tunnel or the glass rod. However, since the light tunnel has a high NA of, for example, 0.3 or more, the light tunnel or the glass rod is tapered. The only option was to add a corner or optimize the illumination system after that by using a plurality of lenses and reducing the NA to about 0.2.
However, in order to achieve high light utilization efficiency without the need for expensive tapered light tunnels or glass rods, for example, if one wants to optimize the NA before the light tunnels or glass rods, that is, to reduce the NA, the above-mentioned means is necessary. I can not use it.
[0008]
On the other hand, in a liquid crystal projector using a PBS, there is a limit to increasing the NA of a polarization conversion element or the like in order to increase the contrast. In such a projector, since the polarization conversion prism has an incident angle dependence, it is necessary to limit the NA value as much as possible before the illumination system. For that purpose, it is best to improve at the part of the reflecting mirror, but at present, it is difficult to reduce the size and the one that limits the NA has a complicated structure and has not been used. In addition, even if the NA was reduced, the light tunnel or the glass rods were arranged in parallel, so basically the overall length was not reduced, and only the effect of the NA was obtained. Met.
[0009]
Furthermore, at present, cold mirrors coated with a dielectric multilayer film are often used for the reflector itself to prevent the incidence of heat rays, but the number of vapor-deposited layers is large and the film formation time is long, requiring cost. Has been greatly improved. In addition, an IR / UV cut filter or the like is often installed immediately after the elliptical mirror in the projector illumination system in order to prevent unnecessary wavelengths other than the reflector from being incident. There was a disadvantage that the overall length was lengthened.
[0010]
[Object of the invention]
The present invention has been made in view of the above-described problems of a light source device such as a conventional electronic device projector, and has as its object to provide a light source device that is small and can emit an illumination light beam having an appropriate NA. And
[0011]
[Means to solve the problem]
According to the present invention, a light valve, the light valve is disposed at the center of one ellipse of the ellipsoidal rotator, the elliptical reflecting mirror cut at substantially the center between the two elliptical centers, and the light valve is disposed at the opening of the elliptical reflecting mirror. An aperture plane mirror, a filter reflector disposed in a conical region connecting the opening and the center of the other ellipse and inclined at 45 ° to an optical axis connecting the center of the lens ellipse, and a filter reflector of the other on the reflection optical axis of the filter reflector. A light source device comprising: a light-density equalizing member having an incident surface arranged at a position conjugate to an ellipse center.
[0012]
Embodiments of the present invention are as follows.
The filter reflection plate is made of a substrate having a UV absorption cut function. With this configuration, UV does not enter the electronic device that forms a video signal, and the durability of the electronic device can be increased.
Further, the filter reflection plate is made of a substrate having an IR absorption cut function. With this configuration, the heat ray does not reach the electronic device or the like, and the electronic device projector can be easily maintained at a certain temperature or lower.
[0013]
Further, the filter reflection plate is characterized in that a UV / IR absorption cut filter is sandwiched. With such a configuration, UV / IR absorption can be performed with almost no need for such a region, and an electronic device projector free from a problem of heat can be configured in a small size.
[0014]
Further, the filter reflection plate has a rear surface coated with a paint for increasing thermal conductivity. With such a configuration, heat generated by the light source device can be efficiently removed.
Further, the filter reflection plate has a configuration in which cooling air is applied to a back surface thereof. With such a configuration, heat generated by the light source device can be efficiently removed.
Further, the light density equalizing means is a light tunnel or a glass rod. With this configuration, it is possible to form a light source device that is small and easy to assemble.
[0015]
Embodiment
Hereinafter, a light source device for an electronic device projector according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the light source device 10 includes a light valve 12 and an elliptical reflecting mirror 14 surrounding the light valve 12. The elliptical reflecting mirror 14 is preferably a cold mirror, has an inner reflecting surface of an ellipsoidal rotator, and the light valve 12 is arranged at one of two elliptical centers. The elliptical reflecting mirror 14 has one form cut by a plane passing through a half of the ellipsoidal rotator, that is, a center line O1 connecting the centers of the ellipses C1 and C2 and orthogonal to the center line O1.
[0016]
As shown in FIGS. 2 and 3, an open disk mirror 22 having an opening 20 at the center is fixed to the opening of the elliptical reflecting mirror 14. It is preferable that the explosion-proof glass plate 23 be attached to the non-reflective side, that is, the outer surface of the apertured disk mirror 22 so as to cover the aperture 20 from the viewpoint of safety.
[0017]
In front of the opening 20, a filter reflector 24 made of a material is disposed at a central portion in a plane and inclined by 45 ° with respect to the center line O 1. The reflection surface of the filter reflection plate 24 may be provided with a general aluminum reflection coating, but it is particularly desirable to provide a dielectric multilayer coating in order to increase the reflection efficiency.
[0018]
As shown in FIG. 1, the substrate of the filter reflection plate 24 includes a front glass 24-1 having a UV absorption cutting function, such as 80152 of Corning T, and a rear glass 24-2 having an IR absorption cutting function, such as DMG. With HA-30. This arrangement of the front glass 24-1 and the rear glass 24-2 has a higher heat radiation efficiency than the reverse arrangement. The substrate of the filter reflection plate 24 may be one obtained by sandwiching a UV / IR absorption cut filter. The size of the filter reflector 24 is determined so as to cut the conical region 26 connecting the opening 20 and the elliptical center C2 of the elliptical reflector 14 and cover the cut surface.
[0019]
The entrance surface 32 of the light tunnel 30 is arranged on the reflection optical axis O2 of the filter reflection plate 24 and at a position conjugate with the ellipse center C2. The light tunnel 30 is for equalizing the light density of the illumination light beam, and may be a glass rod.
[0020]
It is desirable to apply black paint or a paint that increases thermal conductivity, such as steel or carbon graphite, on the back surface of the filter reflector 24. Further, it is desirable that an air blowing mechanism (not shown) is provided behind the filter reflection plate 24 and the cooling air 40 is applied to the back surface of the filter reflection plate 24 from an oblique direction of 45 °.
[0021]
Referring to FIG. 4, the NA of the illuminating light flux reflected by the filter reflector 24 of the light source device 10 having the above-described configuration and incident on the incident surface 32 of the light tunnel 30 is as follows. Let L be the distance along the optical axis O1 and n be the refractive index of the conical region 26.
NA = n · sin ⁻¹ [tan (D / 2) / L]
Required by
[0022]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the light source device of this invention, the light source device which can emit the illumination luminous flux of suitable NA with a small size can be comprised.
[Brief description of the drawings]
FIG. 1 is an optical side view of a light source device according to an embodiment of the present invention.
FIG. 2 is an optical side view of the aperture disk mirror of the light source device according to the embodiment of the present invention.
FIG. 3 is an optical plan view of an aperture disk mirror of the light source device according to the embodiment of the present invention.
FIG. 4 is an optical side view of the light source device according to the embodiment of the present invention.
[Explanation of symbols]
C1, C2 Elliptical center O1 Center line O2 Reflected optical axis 10 Light source device 12 Light valve 14 Elliptical reflecting mirror 20 Opening 22 Open disk mirror 23 Explosion-proof glass plate 24 Filter reflecting plate 24-1 Front glass 24-2 Back glass 26 Conical area 30 light tunnel 32 entrance surface 40 cooling air

Claims (7)

A light valve, the light valve is arranged at the center of one ellipse of the ellipsoidal rotator, an elliptical reflecting mirror cut at substantially the center between the two elliptical centers, and an opening plane mirror arranged at the opening of the elliptical reflecting mirror, A filter reflector disposed in a conical region connecting the opening and the center of the other ellipse and inclined at 45 ° to an optical axis connecting the center of the lens ellipse, and a conjugate with the center of the other ellipse on the reflection optical axis of the filter reflector; A light-density equalizing means in which an incident surface is arranged at an appropriate position. The light source device according to claim 1, wherein the filter reflection plate is formed of a substrate having a UV absorption cut function. The light source device according to claim 1, wherein the filter reflection plate is made of a substrate having an IR absorption cut function. 2. The light source device according to claim 1, wherein the filter reflector is a sandwich of a UV / IR absorption cut filter. The light source device according to claim 1, wherein the filter reflection plate has a rear surface coated with a paint that increases thermal conductivity. The light source device according to claim 1, wherein the filter reflector has a configuration in which cooling air is applied to a back surface thereof. The light source device according to claim 1, wherein the light density equalizing unit is a light tunnel or a glass rod.

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