Optics: image projectors – Reflector
Reexamination Certificate
2000-11-22
2002-07-02
Perkey, W. B. (Department: 2851)
Optics: image projectors
Reflector
C353S119000, C353S122000, C385S051000
Reexamination Certificate
active
06412954
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
The invention relates to a dust-proof device for a solid integration rod in projecting apparatuses, and particularly, to a dust-proof element being adhered to the solid integration rod in projecting apparatuses so that dust does not become attached to the solid integration rod. Furthermore, the solid integration rod can improve upon the problem of light energy loss due to flare portion of the adhesive.
B. Description of the Related Art
The conventional projecting display apparatus can be a transmissive LCD (liquid crystal display), a reflective LCD, a digital micro-mirror device (hereinafter referred as DMD), or any other type of display component. Referring to
FIG. 1
, a schematic system diagram for a conventional projecting apparatus uses a transmissive LCD projecting display apparatus. Such projecting apparatus consists of a reflection mirror
10
, a light source
11
, a first lens set
12
, a solid integration 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 consists of at least one lens. The solid integration rod
13
is an optical device that can homogenize the light passing through the device using an incident-beam surface
137
and an outgoing-beam surface
138
. The second lens set consists of at least one lens or optical element.
By means of the structure mentioned above, the light, either transmitted directly from the light source
11
or reflected from the reflection mirror
10
passes through the first lens set
12
and then converges on the incident-beam surface
137
of the solid integration rod
13
. The light is homogenized after passing through the solid integration rod
13
. Afterward, the light passes through the second lens set
14
and reaches the projecting display apparatus
15
so that the image of the projecting display apparatus
15
is projected on the display screen
17
through the image formation device
16
.
The conventional projecting display apparatus
15
shown in
FIG. 2
is a DMD. The light, once reaching the projecting display apparatus
15
, is refracted to the image formation device
16
so as to project the image of projecting display apparatus
15
on the display screen
17
.
The conventional projecting display apparatus
15
shown in
FIG. 3
is the reflective LCD. The light, after passing through the second lens set
14
and then reaching the projecting display apparatus
15
, is reflected back to the second lens set
14
again. Afterward, the light then turns 90 degree and reaches the image formation device
16
. Therefore the image of projecting display apparatus
15
is projected on the display screen
17
.
The main function of the above mentioned solid integration rod
13
is to homogenize the light passing through so as to achieve the effect of making the projected image uniform. At present, an integration rod is the component most frequently used to achieve uniform image projection. Usually an integration rod can be classified as a hollow integration rod or a solid integration rod wherein, the hollow integration rod is an optical rod forming a hollow column whose internal surface is coated with a layer of reflecting film which reflects the light beam multiple times inside the optical rod while passing through the optical rod, after which the light beam is emitted from the optical rod. The greater the number of times the light beam is reflected inside the optical rod, the more uniform the projected image emitted from the optical rod. However, the reflective index of the coated reflecting film itself has a limitation. When the length of the hollow integration rod is too long, the increase in the number of times the light beam reflects results in an increase in light energy loss and consequently, the illumination of the entire projection system is therefore reduced. Nevertheless, as long as the length of the hollow integration rod is adequate, producing a uniform projected image can be achieved without losing too much light energy. Thus, the hollow integration rod has an advantage of not requiring too much length. In contrast, the solid integration rod produces the light beam reflection completely inside the optical rod and then emits the light beam. Therefore, the energy of the light beam is not lost due to the influence of the length of the integration rod, which is the advantage of the solid integration rod. However, compared to the hollow integration rod, the incident angle of light beams entering the solid integration rod after refraction at the incident-beam surface is relatively smaller than the number of reflections of the light beams inside the optical rod. Thus, in order to achieve the same degree of uniformity in the projected image as that of the hollow integration rod, the length of the solid integration rod is necessary longer. It usually requires at least one and a half times the length as the hollow integration rod requires.
As mentioned above, the main function of the solid integration rod is to homogenize the light after it passes through in order to achieve a uniform projected image. Currently however, one problem that occurs during usage is that once dust attaches to the outgoing-beam surface
138
of the solid integration rod, an image of that dust will be projected on the display screen
17
rendering an unclear picture.
In recent tests, the dust on the outgoing-beam surface
138
of the solid integration rod
13
was projected on the display screen
17
while dust on the other area of the integration rod
13
was not projected on the display screen
17
. Therefore, this problem can be resolved when a dust-proof approach is implemented on the outgoing-beam surface
138
.
FIG. 4
refers to a conventional solid integration rod with a dust-proof structure wherein an integration rod
3
is provided with an incident-beam surface
31
and an outgoing-beam surface
32
. The dust-proof structure consists of a housing
2
, a dust-proof plate
4
, a buffering pad
5
and a fastening cover
6
.
Inside of housing
2
are a first chamber
21
and a second chamber
22
connected to each other wherein the cross section of the second chamber
22
is larger than, and is able to, thoroughly overlap that of the first chamber
21
. The first chamber
21
contains the solid integration rod
3
and the opposite end of the second chamber
22
has a stopping portion
23
to stop the edge of the incident-beam surface
31
of the solid integration rod
3
. The outgoing-beam surface
32
of the solid integration rod
3
is in the second chamber
22
.
The dust-proof plate
4
is a transparent plate, such as a plate of an acryl plate, positioned in the second chamber
22
of the housing
2
to press against and completely cover the outgoing-beam surface
32
of the solid integration rod
3
. The rubber buffering pad
5
has a window
51
in the central portion to cover the dust-proof plate
4
.
The central portion of the fastening cover
6
also has a window
61
. Two of its sidewalls are symmetrically provided with hooks
62
and
63
while the other two sidewalls are symmetrically provided with two stopping portions
64
. The front end of the hook
62
is provided with a slant-guiding surface
621
. The fastening cover
6
first covers the exterior of the buffering pad
5
and the dust-proof plate
4
. Then the hook
63
hooks onto the recess (not shown) on the back of the second chamber
22
of the housing
2
while the hook
62
hooks onto the back of the second chamber
22
using its guiding surface
621
. In this way, the dust-proof plate
4
and the buffering pad
5
are fixed to the second chamber
22
.
By means of the above mentioned structure, the outgoing-beam surface
32
of the solid integration rod
3
can be completely covered by the dust-proof plate
4
so that no dust is accumulated on the outgoing-beam surface
32
and consequently no image of dust is projected on the display screen
17
. Furthermore, the outgoing-beam surface
32
of the solid integration rod
3
pr
Coretronic Corporation
Hsu Winston
Perkey W. B.
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