JP2001109068A - Light source device for projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of color uniformity such as the coexistence of a red component and an orange component in the same image plane, caused by the effect that the reflection wavelength characteristics of a dichroic coat applied on a reflection type color wheel are different according to the incident angle of light. SOLUTION: A spherical reflector 3 with the light emitting part of a lamp positioned at the center is arranged so as to eliminate the large component of the incident angle of a luminous flux made incident on the reflection type color wheel, and then, all the luminous flux projecting downwards are returned to the light source part and outputted toward an elliptic reflector 2 on the opposite side, then, the incident angle of the luminous flux made incident on the reflection type color wheel 6 is narrowed, then, color unevenness is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source for a projection type device for projecting an image or a video, and more particularly to a micro projector or a dichroic mirror having a color wheel and projecting a color image by a color time division method. The present invention relates to a light source of a projector device having the same.

[0002]

2. Description of the Related Art In a projection type device, for example, a liquid crystal display panel is used as a transmission type light valve, and a digital micromirror (DMD) is used as a reflection type light valve. Alternatively, it is an apparatus for displaying an image by reflecting the light and spatially modulating the light by the light valve and projecting it on a screen by a projection lens system.

[0003] In particular, a projection device using a DMD is small in size, has high brightness, and has a fast moving image, compared to a projection device using a liquid crystal panel as a light valve, because it uses a high light efficiency without using polarization. Suitable for display. Single plate DMD
In a device for projecting a color image by using a light valve as a light valve, a method of irradiating light to the light valve in a time-division manner using a color wheel in a time-division manner is employed. This color wheel is classified into a transmission type and a reflection type. The reflection type color wheel has a feature that an effective area can be obtained without being affected by the outer shape of the motor, unlike the transmission type.

FIG. 2 shows a configuration of a conventional projection device optical system using a DMD as a light valve and a reflection type as a color wheel. The light emitted to the DMD 33 is collected on the reflection type color wheel 26 by the reflector 22 having an axisymmetric elliptical shape in which the light emitted from the lamp 21 is emitted. The motor unit 27 that rotates the wheel rotates and scans mirrors having different reflection wavelength characteristics of the three colors RGB arranged on the circumference on the reflection type color wheel 26, and performs color time division irradiation of light to the DMD 33. . The irradiation light reflected by the color wheel 26 is transmitted through the rod lens 28 so that the intensity in the cross section of the light beam is made uniform, and further, the area of the light beam is enlarged by the relay lenses 29 and 30 constituting the telescope. The DMD 33 is irradiated. The light spatially modulated by the DMD 33 is enlarged and projected by the projection lens 35.

[0005]

The mirrors of the color wheel having different reflection wavelength characteristics utilize the reflection spectral characteristics of the dielectric multilayer film. This dichroic coat has different wavelength characteristics to be reflected depending on the incident angle of light, and the incident angle dependent characteristic is particularly remarkable for the red component on the long wavelength side. When the incident angle becomes shallower, the peak of the reflection spectral characteristic shifts to the shorter wavelength side. Therefore, when light is incident at a large angle on the mirror that originally wants to reflect only red (the angle with respect to the normal to the reflecting surface is defined as the incident angle) ), The component in the wavelength range from vermilion to orange is reflected, and the red component and the orange component are mixed in the same screen, which causes deterioration of the color uniformity. In order to solve this problem, it is necessary to narrow the incident angle of the irradiation light to the color wheel and to enhance the vividness of the reflected light color and the uniformity of the color in the screen.

[0006]

According to a first aspect of the present invention, there is provided a light source device for a projector, comprising: a light source; and a first focus of a spheroid having a light emitting portion of the light source as a first focus. And a first reflector having a shape cut in half along an axis connecting the second focal point of the spheroid and a second reflector having a concave spherical shape obtained by cutting a sphere in half, It is characterized in that the first reflector and the second reflector are configured so that the light source is wrapped therein and their concave surfaces face each other. A projector light source device according to a second aspect of the present invention is characterized in that a center of a spherical surface of the second reflector is made to coincide with a center of a light emitting portion of the light source. Claim 3 of the present invention
The light source device for a projector according to the invention according to the above aspect, further includes a reflection surface of a reflection type color wheel near the second focal position of the first reflector. A projector light source device according to a fourth aspect of the present invention is characterized in that the projector has a reflecting surface of a dichroic mirror near the second focal position of the first reflector. The projector light source device according to claim 5 of the present invention is characterized in that the rotation paraboloid having the light source and the light emitting portion of the light source as the focal point is halved along an axis connecting the focal point and the origin of the paraboloid. A first reflector having a cut shape, and a second reflector having a concave spherical shape obtained by cutting a sphere in half, wrapping the light source with the first reflector and the second reflector, It is characterized in that each concave surface is configured to face each other. A projector light source device according to a sixth aspect of the present invention is the projector light source device according to the fifth aspect, wherein the center of the spherical surface of the second reflector coincides with the center of the light emitting portion of the light source. It is characterized by having. A projector light source device according to a seventh aspect of the present invention, in the projector light source device according to the fifth aspect, enlarges or reduces a parallel light beam emitted from the projector light source device or the emitted parallel light beam. A transmission type light valve is provided in the parallel light beam through the means.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a configuration of an optical system of a projection device according to an embodiment of the present invention. The lamp 1, the elliptical reflector 2, the spherical reflector 3, and the cover glass 4 constitute a light source unit. On the optical axis, a reflection type color wheel 6, a rod lens 8, a relay lens 9 and a relay lens 10, a spherical mirror 11 and a spherical mirror 12 are arranged, and a DMD 13 and a projection lens 15 are arranged ahead of them. ing. The reflection type color wheel 6 has an integral structure with the motor unit 7, and is constituted by a dichroic mirror that spectrally reflects red, green, and blue light on the color wheel.
It is a known fact that a total reflection mirror and the like are also configured. On the back side of the DMD 13, a heat sink 14 for cooling is provided.

A feature of the present invention is that a reflection type color wheel 6 is provided.
In order to condense the luminous flux emitted from the lamp unit on the reflecting surface of the lamp and to eliminate a component having a large incident angle of the luminous flux incident on the reflection type color wheel, the spherical reflector 3 centered on the light emitting portion of the lamp is moved downward. 1 is returned to the light source section, and is output to the elliptical reflector 2 on the opposite side.
The elliptical reflector 2 is a half of a spheroid formed by cutting one of two focal points on a light emitting portion of a lamp and the other on a reflecting surface of a reflective color wheel 6 on an axis connecting the two focal points. Part of the shape.

As described above, a part of a half shape obtained by cutting the spheroid on the axis connecting the two focal points is used as a main reflector, and the other half cut and separated is used as a hemispherical auxiliary reflector. As can be seen from the ray trajectory radiated by the lamp 1 shown in FIG. 1, the angle of the light beam incident on the reflection type color wheel becomes narrower, and the conventional axially symmetric elliptical reflector 22 is provided. Is half of the case of using. This makes it possible to reduce the incident angle dependence of the reflection spectral characteristic, which is a characteristic of the dichroic mirror. For this reason, for example, there is an effect that color unevenness in the red spectral region, which is remarkably dependent on the incident angle of the reflection spectrum, is reduced.

In the conventional configuration of a spheroidal reflector that is axially symmetric with respect to the optical axis 5 as shown in FIG. 2, if the axial direction of the electrode of the lamp 1 and the optical axis are matched,
In the center of the light beam, a portion of low illuminance due to the shadow of the non-light emitting portion of the lamp 1 is generated, and means for uniformizing the illuminance distribution of the illuminating light beam to the DMD 13, which is a light valve, is complicated and expensive. According to the above configuration, since the shadow of the electrode of the lamp is located at the periphery of the light beam reflected by the elliptical reflector 2, a light beam having a uniform illuminance distribution can be easily obtained. Also, depending on the directional characteristics of the light emission of the lamp,
The direction of the electrode axis and the direction of the optical axis can be arbitrarily set.

Therefore, for example, in an optical system of a projection apparatus using a liquid crystal panel as a light valve, since a light beam incident on the liquid crystal panel needs parallel light, a reflector for reflecting lamp light has a light source focused on a light source section. Although an object surface is used, by changing the reflector 2 of this embodiment from an elliptical surface to a paraboloid, a parallel luminous flux having a uniform illuminance distribution can be obtained as compared with a case where a conventional axisymmetric parabolic reflector is used. As a result, it is possible to realize a bright light source device for a liquid crystal projection type projector having a high utilization rate of projection light.

In the embodiment shown in FIG. 1, the uniformity of the illuminance of the screen is improved by providing a rod-shaped lens and mixing light. However, small condenser lenses are integrated and arranged in a matrix on the same plane. The same effect can be obtained by providing two integrator lenses.

[0013]

As described above, in the light source device for a projector according to the present invention, the angle of the light beam incident on the reflection type color wheel is narrowed by the above structure, and the reflection by the incident angle, which is a feature of the dichroic mirror, is achieved. It is possible to reduce the dependence of the spectral characteristics. As a result, for example, there is an effect that color unevenness in a red spectral region, which is remarkably angle-dependent, is reduced.

Further, since the shadow of the electrode of the lamp is located at the periphery of the light beam reflected by the elliptical main reflector, a light beam having a uniform illuminance distribution for light valve illumination can be obtained.

By changing the main reflector from an elliptical surface to a parabolic surface, a parallel luminous flux having a uniform illuminance distribution can be obtained as compared with the case where a conventional axisymmetric parabolic reflector is used. A highly efficient light source device for a liquid crystal projection type projector can be realized.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram showing a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 lamp 2 elliptical reflector 3 spherical reflector 4 cover glass 5 optical axis 6 reflective color wheel 7 motor unit 8 rod lens 9 relay lens 10 relay lens 11 spherical mirror 12 spherical mirror 13 DMD 14 heat sink 15 projection lens 21 lamp 22 Axisymmetric elliptical reflector 26 Reflective color wheel 27 Motor unit 28 Rod lens 29 Relay lens 30 Relay lens 33 DMD 35 Projection lens

Claims (7)

[Claims] 1. A half cut along a light source and an axis connecting a first focal point and a second focal point of the spheroid of a spheroid having a light emitting portion of the light source as a first focal point. A first reflector having a shape having a shape, and a second reflector having a shape of a concave sphere obtained by cutting a sphere in half, wrapping the first reflector and the second reflector around the light source, respectively A light source device for a projector, wherein the concave surfaces of the light sources face each other. 2. The light source device for a projector according to claim 1, wherein a center of a spherical surface of said second reflector is made to coincide with a center of a light emitting portion of said light source. 3. The light source device for a projector according to claim 1, further comprising a reflection surface of a reflection type color wheel near the second focal position of the first reflector. 4. The light source device for a projector according to claim 1, further comprising a reflection surface of a dichroic mirror near the second focal position of the first reflector. 5. A light source, and a first reflector having a shape in which a paraboloid of revolution having a light-emitting portion of the light source as a focal point is cut in half along an axis connecting the focal point and the origin of the paraboloid. A second reflector having a shape of a concave spherical surface obtained by cutting a sphere in half, the first reflector and the second reflector are wrapped around the light source, and the respective concave surfaces face each other. A light source device for a projector, comprising: 6. The light source device for a projector according to claim 5, wherein a center of a spherical surface of the second reflector is made to coincide with a center of a light emitting portion of the light source. 7. A transmission type light valve in a parallel light beam emitted from the light source device for a projector or in a parallel light beam through means for expanding or reducing the emitted parallel light beam. 7. The light source device for a projector according to 5 or 6.