Illumination – Light modifier – Reflector
Reexamination Certificate
1999-12-07
2001-05-08
Quach, Y. (Department: 2875)
Illumination
Light modifier
Reflector
C362S294000, C362S373000
Reexamination Certificate
active
06227686
ABSTRACT:
The present invention relates to a high-brightness light source apparatus incorporated in an image projection system such as a liquid crystal projector.
This type of a prior art light source apparatus is disclosed in, for example, Japanese Patent Kokai Publication No. 8-114857 published on May 7, 1996. The light source apparatus uses a high-pressure discharge lamp such as a small short-arc metal-halide lamp, which features large output, high light emission efficiency, long life, and superior color rendering, as the luminescent tube. When the luminescent tube is lit, the temperature of the luminescent tube increases as high as 400° C. to 700° C. This may cause some problems such as decreased transparency or devitrification, of the silica glass forming the luminescent tube, disconnection of the metal electrode of the luminescent tube because of oxidation, deformation or fracture of the silica glass, or cracks in the reflecting mirror. In order to prevent these problems from occurring, the prior art light source apparatus is provided with a ventilator for forcing out the air inside the reflecting mirror.
In the prior art light source apparatus, however, the luminescent tube frequently ruptures, which can result from insufficient or uneven cooling of the luminescent tube. This can cause the broken pieces of the glass forming the luminescent tube to scatter. Extreme care must be taken especially when replacing the luminescent tube.
If the luminescent tube is excessively cooled, sufficiently high level of brightness cannot be obtained, the emission color is degraded, and the sealed-in metal in the luminescent tube is spattered to cause blackening, reducing the transparency of the tube wall.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a light source apparatus that can reduce a risk of rupture of the luminescent tube and degradation of light emitting property and can be safely replaced even if the luminescent tube is ruptured.
According to the present invention, a light source apparatus comprises: a luminescent tube; a reflecting mirror including a large opening for light emission, a small opening used for holding the luminescent tube, and a light reflection surface disposed to encircle the luminescent tube; a holding member disposed to block a part of the small opening, the holding member holding the luminescent tube in the reflecting mirror; a light transmitting protection plate for blocking the large opening; a ventilator for sucking air inside the reflecting mirror through the small opening and sending out the air through an outlet; and a housing for combining the reflecting mirror and the ventilator so as to form a channel for directing the air sucked through the small opening toward the ventilator; the reflecting mirror including an air inlet disposed closer to the large opening than a center position of the luminescent tube.
REFERENCES:
patent: 4630182 (1986-12-01), Moroi et al.
patent: 4858089 (1989-08-01), Pietro
patent: 5207505 (1993-05-01), Naraki et al.
patent: 5622418 (1997-04-01), Daijogo et al.
patent: 8114857 (1996-05-01), None
patent: B2-2860989 (1998-12-01), None
Kawaguchi Mitsuhiro
Takahashi Motoo
Mitsubishi Denki & Kabushiki Kaisha
Quach Y.
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