Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
2001-10-24
2003-06-24
Allen, Stephone B. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C250S216000, C356S003130, C396S114000, C359S819000
Reexamination Certificate
active
06583433
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a range finder mounted on an automatic focusing camera. Specifically, the present invention relates to a module structure of the range finder.
2. Description of Related Art
First, a conventional range finder based on the principle of triangulation using the external light mounted on an auto-focusing camera is explained.
FIG. 5
is a block diagram of a conventional range finder based on the principle of triangulation using the external light. Referring now to
FIG. 5
, the conventional range finder includes an image forming optical system including a pair of range finding lenses
1
L,
1
R and a semiconductor optical sensor chip
5
including photo-sensor arrays
5
L,
5
R, quantizer circuits
51
L,
51
R and a logic circuit
52
integrated into the semiconductor optical sensor chip
5
. The photo-sensor arrays
5
L and
5
R convert the images of an object (hereinafter referred to as the “object images”) to electrical signals. The quantizer circuits
51
L and
51
R convert the electrical signals outputted from the photo-sensor arrays
5
L and
5
R to digital signals, The logic circuit
52
calculates a range signal (or a distance signal) based on the digital signals outputted from the photo-sensor arrays
5
L and
5
R. The images of an object T (hereinafter referred to as the “object images”) are formed on the photo-sensor arrays
5
L and
5
R through the range finding lenses
1
L and
1
R arranged side by side such that the centers of the range finding lenses
1
L and
1
R are spaced apart for a base line length B.
The distance d from the range finding lenses
1
L,
1
R to the object T (hereinafter referred to as the “object distance”) is calculated by the following formula (1) based on the principle of triangulation.
d=B×fe
/(
X
1
+
X
2
)
=B×fe/X
(1)
Here, fe is the distance from the range finding lenses
1
L and
1
R to the sensor arrays
5
L and
5
R, that is equal to the focal length of the range finding lenses
1
L and
1
R. The X
1
and X
2
are the differences between the positions of the object images on the photo-sensor arrays
5
L and
5
R when the object T is at a finite distance and the positions of the object images on the photo-sensor arrays
5
L and
5
R when the object T is at the point of infinity distance. The length X (=X
1
+X
2
) is the relative shift length of the object images on the photo-sensor arrays
5
L and
5
R.
The structure of the conventional range finder integrated into a module mounted on a camera is shown in FIGS.
6
(
a
) through
8
. FIG.
6
(
a
) is a top plan view of a conventional range finder module. FIG.
6
(
b
) is a side plan view of the conventional range finder module. FIG.
6
(
c
) is another side plan view of the conventional range finder module.
FIG. 7
is an exploded perspective view of the conventional range finder module including the optical lens mount, the aperture mount and the sensor stage shown in FIGS.
6
(
b
) and FIG.
6
(
c
).
FIG. 8
is a cross sectional view of the range finder module shown in FIGS.
6
(
a
) through
6
(
c
). Referring now to these figures, the range finder module includes an optical lens mount
1
including the pair of the range finding lenses
1
L and
1
R arranged side by side, an aperture mount
2
for guiding the rays impinging onto the range finding lenses
1
L and
1
R to the photo-sensor arrays
5
L and
5
R on the semiconductor sensor chip
5
, and a sensor stage
3
including the semiconductor sensor chip
5
mounted thereon. The optical lens mount
1
, the aperture mount
2
and the sensor stage
3
are made of plastic. These constituents are piled up and bonded at the bonding planes thereof such that they are combined into a unit.
The range finding lenses
1
L and
1
R are integrated into the optical lens mount
1
such that the range finding lenses
1
L and
1
R are positioned side by side. A pair of light guide spaces
2
a
are formed in the aperture mount
2
corresponding to the respective range finding lenses
1
L and
1
R. Aperture holes
2
L and
2
R, that determine the amount of the light impinging onto the semiconductor optical sensor chip
5
, are formed in the respective light guide spaces
2
a
. The sensor stage
3
includes a lead frame
4
formed by insertion molding into the sensor stage
3
. Bonding wires connect the lead frame
4
and the semiconductor optical sensor chip
5
mounted at a predetermined position on the sensor stage
3
.
The space inside the range finder module is filled with a transparent filler
6
such as a transparent silicone gel, that seals the semiconductor optical sensor chip
5
and the vicinity thereof to prevent the pad of the sensor chip
5
and the bonding wires from being deteriorated by temperature change, moisture, thermal stress, foreign substances and such causes.
FIG. 9
is a cross sectional view for explaining the method of injecting a transparent filler into the range finder module of FIG.
8
. Referring now to
FIG. 9
, the back surface of the sensor stage
3
is open to provide an injection port for injecting the transparent filler and for absorbing thermal expansion and thermal contraction of the transparent filler. First, the range finder module of
FIG. 8
is set upside down. A syringe containing a fluid transparent filler is set at the injection port in the open back surface of the sensor stage
3
. The transparent filler
6
is injected into the range finder module through the gap between semiconductor optical sensor chip
5
and the sensor stage
3
. The transparent filler
6
, that has flowed into the inside space surrounded by the optical lens mount
1
, the aperture mount
2
and the sensor stage
3
, fills the inside space. Further, the transparent filler
6
covers the semiconductor optical sensor chip
5
. Then, a heat treatment is conducted to cure the transparent filler
6
. The amount of the transparent filler
6
is controlled such that the transparent filler
6
is injected up to the level of the open back surface of the sensor stage
3
at the end of the transparent filler injection.
The transparent filler injection into the conventional range finder module as described above causes the following problems. When injection speed variation and injection amount variation are caused during injecting the transparent filler
6
, the light guide spaces
2
a
in the aperture mount
2
are not completely filled with the transparent filler
6
sometimes. When the light guide spaces
2
a
are not filled with the transparent filler
6
completely, voids are caused by heat treatment in the field of view between lenses
1
L,
1
R and the optical sensor arrays
5
L,
5
R. As a result, the object images are not formed correctly on the photo-sensor arrays
5
L and
5
R.
The present inventors have found the causes for the voids in the transparent filler. As shown in
FIG. 9
, the transparent filler
6
is injected from one injection port. However, the inside space of the range finder module to be filled with the transparent filler
6
forks to the right light guide space and the left light guide space in the aperture mount
2
. Since the front end of the aperture mount
2
is in contact with the optical lens mount
1
and since the light guide spaces
2
a
are separated from each other by a partition wall
2
b
as shown in
FIG. 8
, the light guide spaces
2
a
are shaped with respective pockets and the middle portions of the pocket-shaped light guide spaces
2
a
are narrowed by the aperture holes
2
L and
2
R.
During the transparent filler injection described in
FIG. 9
, the air in the spaces replaced by the transparent filler
6
may escape upward through the aperture holes as far as the transparent filler flows little by little into the space between the optical lens mount
1
and the aperture mount
2
through the aperture holes
2
L and
2
R. However, when the transparent filler flowing onto the aperture holes
2
L and
2
R closes the narrow aperture holes
2
L and
2
R while unfil
Izumi Akio
Sugiyama Osamu
Yamamoto Toshio
Allen Stephone B.
Fuji Electric & Co., Ltd.
Rossi & Associates
Spears Eric J
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