Optics: image projectors – Temperature control – Blower
Reexamination Certificate
2003-02-24
2004-11-09
Mahoney, Christopher E (Department: 2851)
Optics: image projectors
Temperature control
Blower
C353S061000, C353S119000, C348S748000
Reexamination Certificate
active
06814446
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rear projector including an image generator that has an optical device for modulating a light beam irradiated by a light source in accordance with image information to form an optical image and a projection optical system for enlarging and projecting the optical image, a box-shaped casing for accommodating the image generator, and a screen exposed on one of the sides of the box-shaped casing onto which the optical image generated by the image generator is projected.
2. Description of Related Art
Recently, a rear projector has come to be used in the field of home theater etc. Such rear projector has an image generator for generating a projection image, a box-shaped casing accommodating the image generator and a reflection mirror for reflecting the projected image and a transmissive screen exposed to a side of the box-shaped casing.
The image generator has a light source lamp, an optical device such as a liquid crystal panel for modulating a light beam irradiated by the light source lamp in accordance with image information, and a projection optical system such as a projection lens for enlarging and projecting the generated optical image.
The optical image generated by the image generator is reflected on a mirror etc. to be projected on the transmissive screen, which transmits through the screen to be viewed as an image.
Such rear projector also accommodates acoustic device such as a speaker inside the casing thereof, so that the large-screen image has much presence with the use of the acoustic device.
Incidentally, the image generator of such rear projector has the light source lamp, a light source driving block for driving the light source lamp, and a power source block for supplying electric power to the board for controlling the drive of the optical device, all of which are heat source. On the other hand, some of the components of the optical device etc. are weak against heat. Accordingly, it is important to cool the interior of the projector efficiently.
Conventionally, the interior of the projector is conducted according to the following arrangements.
In an arrangement shown in Japanese Patent Laid-Open Publication No. 2001-343708, an intake opening and an exhaust opening are provided on a front side, i.e. on a side provided with a screen, of the casing of a rear projector, through which the cooling air is introduced to the interior of the projector and is exhausted therefrom (see
FIG. 6
thereof).
In another arrangement shown in Japanese Patent Laid-Open Publication No. Hie 9-98360, an intake opening is provided on a front side of the casing of a rear projector and an exhaust opening is provided on a rear side of the casing of the rear projector, where the interior of the projector is cooled by a cooling channel from the front side to the rear side of the rear projector (see FIG.
9
).
However, according to the cooling method shown in Japanese Patent Laid-Open Publication No. 2001-343708, since both of the intake opening and the exhaust opening are provided on the front side of the casing, a part of the air having cooled the interior of the projector and exhausted from the exhaust opening is taken in by the intake opening, thus raising the temperature of the cooling air introduced from the intake opening and the interior of the projector cannot be efficiently cooled.
Further, since the heated air having cooled the interior of the projector is exhausted from the front side of the casing, the spectator may feel unpleasantness according to the amount of the discharged air.
Since the exhaust opening is provided on the rear side of the casing in the cooling method shown in Japanese Patent Laid-Open Publication No. Hie 9-98360, when the rear projector is installed, for example, with the rear side thereof being opposed to a room wall, the flow of the cooling air is blocked by the wall, so that the heat may remain interior the projector and the interior of the projector cannot be efficiently cooled.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a rear projector capable of efficiently cooling the interior of the projector and giving no unpleasant feeling to the spectators.
A rear projector according to an aspect of the present invention comprises: an image generator having an optical device that modulates a light beam irradiated by a light source in accordance with image information to form an optical image and a projection optical system that enlarges and projects the optical image; a box-shaped casing that accommodates the image generator; and a screen exposed on any one of lateral sides of the box-shaped casing that on which the optical image formed by the image generator is projected, in which an intake opening that introduces a cooling air to the image generator is formed on a first lateral side of the casing adjacent to a first edge of the screen other than the lateral side provided with the screen and an exhaust opening that discharges the air after cooling the image generator is formed on a second lateral side of the casing adjacent to a second edge of the screen opposite to the first edge of the screen, and in which a cooling channel for the cooling air to be flowed is formed inside the casing along the surface of the screen.
The optical device as a component of the image generator includes various optical modulators capable of optically modulating the light beam irradiated by the light source in accordance with image information, which may modulate the color image with a single plate or, alternatively, may combine a plurality of color lights of R, G and B by a color combining optical device such as a prism to form a color image after modulating the color lights with a plurality of optical modulators. The optical modulator includes a micro-mirror as well as transmissive liquid crystal panel and reflective liquid crystal panel.
The shape of the screen is not restricted, but may be designed in any manner such as rectangle and trapezoid.
According to the above arrangement, since the intake opening and exhaust opening are separately formed on the lateral sides other than the side provided with the screen adjacently to the opposing edges of the screen, the air having cooled the interior of the projector discharged from the exhaust opening can be securely prevented from entering into the intake opening. Accordingly, the temperature of the air introduced from the intake opening is always approximately the same as room temperature, thereby efficiently cooling the interior of the casing.
Further, when the rear projector is installed with backside thereof facing, for instance, a wall of a room, the flow of the cooling air is not hindered by the wall, thereby efficiently cooling the interior of the projector.
Since the air having cooled the interior of the projector is discharged from the lateral side of the casing provided with no screen, the air having cooled the interior of the projector is not discharged from the front side of the casing, thus causing no unpleasant feeling on spectators. Further, blur of image on the screen caused when the temperature of the discharged air is high can be prevented.
In the above rear projector, a first duct that guides at least a part of the cooling air in normal line direction of the surface of the screen may preferably be provided in the cooling channel.
The first duct may preferably have a tube-shaped body having an introduction hole that introduces at least a part of the cooling air at a side adjacent to a first end thereof and a discharge hole for discharging the introduced cooling air at a side adjacent to a second end opposite to the first end. Incidentally, the cross section of the first duct may be designed in any manner such as cylindrical shape and square pillar in accordance with layout of the interior of the projector and the component to be cooled as long as the cooling air can be efficiently flowed.
According to the above arrangement, when it is preferable to form a cooling channel in a normal line direction of the
Arai Jun
Yamada Haruyoshi
Mahoney Christopher E
Oliff & Berridg,e PLC
Seiko Epson Corporation
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