Solid rod dust-proof structure for projecting apparatuses

Details Solid rod dust-proof structure for projecting apparatuses Solid rod dust-proof structure for projecting apparatuses

2000-08-08

2002-05-28

Dowling, William (Department: 2851)

Optics: image projectors

Housing

C353S099000, C353S122000, C385S133000, C385S146000, C385S147000

Reexamination Certificate

active

06394611

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a projecting apparatus and, in particular, to a solid rod dust-proof structure for projecting apparatuses.
2. Related Art
Shown in
FIG. 1
is a schematic view of an optical system of a projecting apparatus. The apparatus includes a reflection mirror
10
, a light source
11
, a first lens set
12
, a solid rod
13
, a second lens set
14
, a projecting display apparatus
15
, an image formation device
16
and a display screen
17
. The first lens set
12
consists of at least a lens. The solid rod
13
being an optical device that can homogenize the light passing through includes an incident-beam surface
131
and an outgoing-beam surface
132
. The second lens set
14
consists of at least one lens or optical device. The projecting display apparatus
15
can be a transmissive LCD, a reflective LCD, a digital micro device (hereinafter as DMD) or other display devices.
The projecting display apparatus
15
in
FIG. 1
is a transmissive LCD and the image formation device
16
is a projecting device. Through the solid rod
13
, light can be converged onto the incident-beam surface
131
of the solid rod
13
by directly transmitting from the light source
11
or by reflecting from the reflection mirror
10
and through the first lens set
12
. The light that is homogenized after passing through the solid rod
13
reaches the projecting display apparatus
15
through the second lens set
14
. Therefore, the image on the projecting display apparatus is projected onto the display screen
17
by the image formation device
16
.
The projecting display apparatus
15
in
FIG. 2
is a DMD. The light, transmitting to the DMD
15
and being reflected from the DMD
15
to the image formation device
16
, projects the image formed on the DMD
15
toward the display screen
17
. image formed on the DMD
15
toward the display screen
17
.
The projecting display apparatus
15
in
FIG. 3
is a reflective LCD. When light enters the second lens set
14
, it first transmits to the projecting display device
15
, reflects back on the second lens set
14
. Afterward, the light, turning a 90-degree angle and transmitting to the image formation device
16
projects the image formed on the reflective LCD
15
toward the display screen
17
.
The main function of the solid rod
13
is to homogenize the light passing through so as to achieve the effect of making the projected image uniform. However, one problem is that: when there is dust on the outgoing-beam surface
132
of the solid rod, the dust will also be projected onto the display screen
17
and to blur the image.
Currently, only the dust on the outgoing-beam surface
132
of the solid rod
13
will be projected onto the display screen
17
while the dust on the other portion will not. Thus, this problem can be solved once a dust-proof structure is provided for the outgoing-beam surface
13
.
SUMMARY OF THE INVENTION
It is one of the object of the invention to provide a solid rod dust-proof structure for projecting apparatuses that can prevent the outgoing-beam surface of the solid rod from dust accumulation so that the transmitting light through the outgoing plane will not be blocked. This structure can thus avoid the influence of the dust on the projected image.
To achieve the above object, the solid rod in the structure has an incident-beam surface and an outgoing-beam surface. The dust-proof structure includes a housing having a first chamber and a second chamber wherein the cross section of the second chamber is greater than that of the first chamber. The first chamber contains the solid rod, and the opposite end of the second chamber includes a stopping portion for stopping the solid rod. Also, a dust proof plate which is a transparent plate is contained in the second chamber of the housing for completely covering the outgoing-beam surface of the solid rod.
Using the above structure, the outgoing-beam surface of the solid rod can be completely covered by the transparent dust-proof plate so that the structure is free from dust and the light transmitting through the outgoing-beam surface will not be blocked.


REFERENCES:
patent: 4456329 (1984-06-01), Henderson, et al.
patent: 5530940 (1996-06-01), Ludwig, Jr. et al.
patent: 5625738 (1997-04-01), Magarill

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