JP2001296607A - Shading reflector and image projection device having shading reflector - Google Patents

Abstract

(57) [Problem] To prevent light leakage from a light source due to light emission of a light source, improve cooling efficiency of a light source unit, and reduce wind noise. SOLUTION: It comprises a reflector 10, a black infrared light transmitting paint 11, and a light source (arc tube) 12. The reflecting surface of the reflector is formed by a cold mirror. The light 1 emitted from the arc tube is divided into a light component 2 reflected on the reflection surface of the reflector and a light component 3 transmitted therethrough. Transmitted light component 3
Enters the black-infrared-light-transmissive paint layer 4 attached to the outside of the reflector. At this time, the visible light component 3a is absorbed by the infrared-light-transmissive paint layer, and only the infrared light component 3b is absorbed by the infrared light. It passes through the transparent paint layer 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection device such as a liquid crystal projector for enlarging and projecting an output signal from a personal computer or an image such as video onto a screen, and more particularly to preventing light leakage from a light source and improving cooling efficiency of a light source portion. And noise reduction by a cooling fan.

[0002]

2. Description of the Related Art Conventionally, there is an image projection apparatus which irradiates an optical image signal formed on a light valve represented by a liquid crystal display element by a projection unit and projects an optical image on a screen by the projection unit.

[0003] Such an image projection apparatus performs not only display of video such as video signals, but also display of image output of a personal computer, and its use for presentation is expanding.

[0004] Presentations using these image projection devices are performed with the image projection device placed in front of the viewer. Light leakage from a light source reduces the image quality (contrast) on the screen, or the light is directly viewed or viewed. Into the eyes of others, causing discomfort.

[0005] The heat generated by the light source not only affects the life of the light source but also adversely affects parts in the image projection apparatus.

The light source comprises a light emitting portion and a reflector for irradiating the light emitted from the light source to a target irradiation surface. Infrared light other than visible light, which is unnecessary light, is reflected by the reflector. In general, a cold-mirror-type reflector that transmits light without passing through the reflector is generally used.

However, in a cold-mirror type reflector, the luminous flux emitted from the arc tube is high, so that not only infrared light but also part of visible light is transmitted to the outside from the reflector.

Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 1-84290, a louver serving as a blind is integrally formed in a lamp house or a housing of a light source to shield light from light leakage and to cool from a gap therebetween. The wind was allowed to pass.

Since the output of the light source is large for cooling the light source unit, a cooling fan is configured in the vicinity of the light source. However, due to the light leakage, the cooling air path must be narrowed naturally. I can't get it.

[0010] For this reason, a vortex is generated in the louver portion by driving the cooling fan, which causes noise due to wind noise caused by the louver.

[0011]

On the other hand, in the presentation, the output of the light source tends to be increased so that the venue can be kept bright.

Therefore, not only the above-mentioned light leakage is affected, but also the overheating of the light source and the wind noise are problematic.

In the louver method disclosed in the prior art, light leakage and cooling efficiency are in an opposite relationship.

Although it is necessary to reduce the opening area of the louver in order to shield light leakage, the area through which the cooling air passes decreases, the cooling efficiency of the light source unit decreases, and the noise increases.

Therefore, there is a limit in a structure using a louver.

SUMMARY OF THE INVENTION In view of the above problems of the prior art, it is an object of the present invention to prevent light leakage from a light source due to light emission of the light source, improve cooling efficiency of a light source unit, and reduce wind noise.

[0017]

SUMMARY OF THE INVENTION The present invention provides a means for solving the above problems. In a reflector using a cold mirror on the inner surface, a light shielding means is provided on the outer surface of the reflector.

The light shielding means is obtained by applying a black infrared light transmitting paint.

According to the above configuration, the visible light component of the light from the light source accompanying the light emission of the light source is absorbed by the black infrared light transmitting paint on the outer surface of the reflector.

Since the infrared light which occupies most of the heat source passes through the reflector, it is possible to shield the light leaking outside the reflector without increasing the temperature of the reflector or the light source.

Further, the louvers of the lamp house can be eliminated.

Therefore, it is possible to prevent light leakage from the light source due to light emission of the light source, to improve the cooling efficiency of the light source unit, and to reduce wind noise caused by the louver.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a light shielding reflector according to the present invention will be described below with reference to FIG.

FIG. 1 shows an example of the configuration of a light source unit having a light-shielding reflector according to the present invention.
It is composed of a black infrared light transmitting paint 11 and a light source (arc tube) 12.

The reflecting surface of the reflector 10 is formed by a cold mirror.

The light 1 emitted from the arc tube is divided into a light component 2 reflected on the reflecting surface of the reflector and a light component 3 transmitted therethrough.

In a general cold mirror, since the luminous flux emitted from the arc tube is high, not only the infrared light but also a part of the visible light is transmitted to the outside from the reflector.

The transmitted light component 3 enters the black infrared light transmitting paint layer 4 attached to the outside of the reflector. At this time, the visible light component 3a is absorbed by the infrared light transmitting paint layer, and Only the light component 3b transmits through the infrared light transmitting paint layer 11.

At this time, the black infrared light transmitting coating layer 11 is coated with, for example, a black ceramic coating material CRC-1500 manufactured by Hisaka Laboratories Co., Ltd. in a thickness of 10 to 20 μm and then coated in a thickness of 120 to 120 μm.
It can be obtained by heating and curing at 300 ° C. for 10 to 40 minutes.

According to the above configuration, light can be shielded by the reflector itself, so that it is not necessary to provide a louver for shielding light in the lamp house.

Therefore, it is possible to prevent the cooling efficiency from being lowered by the louver portion, and to reduce the noise due to the wind noise because there is no louver which causes the vortex.

An image projection device having a light shielding reflector will be described below with reference to FIG. Light emitted from the light source 12 is reflected on the surface of the cold mirror 10. The visible light transmitted through the cold mirror 10 is shielded by the light shielding means 11, so that a light shielding louver provided in the opening 4 is usually unnecessary.

Therefore, the cooling efficiency of the set and the lamp due to the exhaust fan 5 can be prevented from lowering, and the voltage applied to the fan can be reduced. Therefore, the noise can be reduced because no wind noise is generated by the louver.

Next, other parts of FIG. 2 will be described below. The light reflected by the cold mirror 10 passes through the fly-eye lenses 7 and 8, the total reflection mirror 9, and the condenser lens 30, and then only the red component is transmitted by the dichroic mirror 31.

The transmitted red component is reflected by a total reflection mirror 32,
The light enters the red liquid crystal panel 14R having image information via the condenser lens 13R and is modulated. Thereafter, the light is reflected by the prism 20 and enters the projection lens 21.

On the other hand, the light component reflected by the dichroic mirror 31 is reflected only by the green component on the dichroic mirror 15. This green component is the condenser lens 13G
And is incident on a green liquid crystal panel 14G having image information and modulated. Thereafter, the light passes through the prism 20 and enters the projection lens 21.

The blue component transmitted through the dichroic mirror 15 is transmitted to a relay lens 16, a total reflection mirror 17,
The light enters the blue liquid crystal panel 14B via the relay lens 18, the total reflection mirror 19, and the condenser lens 13B.

The light modulated by the blue liquid crystal panel 14B is reflected by the prism lens 20 and enters the projection lens 21.

Light beams having image information of respective colors incident on the projection lens 21 are superimposed on each other to form a color image, which is projected on a screen.

[0040]

According to the present invention described above, the following effects can be obtained.

The visible light component of the light from the light source accompanying the light emission of the light source is absorbed by the black infrared light transmitting paint on the outer surface of the reflector.

Since infrared light, which occupies most of the heat source, passes through the reflector, light leaking outside the reflector can be blocked without raising the temperature of the reflector or the light source.

Further, the louvers of the lamp house can be eliminated.

Accordingly, it is possible to prevent light leakage from the light source due to light emission of the light source, to improve the cooling efficiency of the light source unit, and to reduce wind noise caused by the louver.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an embodiment of a light-shielding reflector according to the present invention.

FIG. 2 is a sectional view of an embodiment of an image projection device having a light-shielding reflector according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 light emitted from arc tube 2 light component reflected on reflector reflection surface 3 light component transmitted on reflector reflection surface 3a visible light component transmitted on reflector reflection surface 3b infrared light component transmitted on reflector reflection surface 10 reflects visible light Means 11 for transmitting a part of visible light and infrared light 12 light source

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Claims (3)

[Claims] 1. A light-shielding reflector using a cold mirror on the inner surface, wherein light-shielding means is provided on the outer surface of the reflector. 2. The light-shielding reflector according to claim 1, wherein said light-shielding means is a black infrared light transmitting paint. 3. An image projection device comprising the light-shielding reflector according to claim 1.