Optical: systems and elements – Mirror – With support
Reexamination Certificate
2000-12-11
2002-03-26
Shafer, Ricky D. (Department: 2872)
Optical: systems and elements
Mirror
With support
C359S848000, C248S468000, C248S475100
Reexamination Certificate
active
06361177
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical device fixing device, and particularly to a prism mounting device for an optical device using light beam which passes through a prism or lens, a lens fixing device for aligning and fixing the center of a lens with a prescribed optical axis, and a reflecting mirror fixing device for fixing a reflecting mirror of an optical device.
2. Description of the Related Art
To open a locked door or to allow only registered persons to access to valuable data, a judging device according to fingerprint checking has been developed.
A conventionally known developed individual fingerprint checking device comprises a prism, a lens, and an image processing circuit.
FIG. 12
shows such a device as a schematic vertical sectional view.
The device shown in
FIG. 12
has a fingerprint checking device housed into a case
1
and a top lid
2
mounted at the top. Within the case
1
, a prism
4
and a lens
5
are disposed substantially in a horizontal direction, and an emission unit
3
is positioned below the prism
4
. The upper part of the prism
4
is in contact with the top lid
2
. The prism
4
is positioned with its center axis aligned with the optical axis of the lens
5
. A mirror
7
is positioned to reflect the light coming out of the lens
5
, and the light reflected on the mirror
7
enters an image pickup device
8
. The prism
4
is fully covered with a light impermeable material excluding a surface opposed to the emission unit
3
, a surface on which a finger
9
is positioned, and a surface from which light is entered into the lens
5
.
In the device shown in
FIG. 12
, when light is emitted from the emission unit
3
to the prism
4
, the emitted light passes through the prism
4
and also the top lid
2
. When the finger
9
is positioned on a lighted area to check a fingerprint, the light from below is substantially absorbed at valley portions of the fingerprint, and the light is mostly reflected on ridge portions of the fingerprint to enter the prism
4
.
As indicated by the arrows, the light goes downward within the prism
4
, and reflects again on the prismss surface opposed to the emission unit
3
(a bottom face
4
a
of the prism
4
). In view of the shape of the prism
4
, the surface of the prism
4
opposite from the lens
5
forms a reflection surface
10
for the light, so that the light reflected on the bottom face
4
a
of the prism
4
is reflected on the reflection surface
10
, and goes straight through the prism
4
to the lens
5
.
The lens
5
is covered by a lens holder
6
and held within the case
1
. Accordingly, the position of the lens
5
can be adjusted to focus the light, which has advanced through the prism
4
toward the lens
5
, beyond the lens
5
by the lens
5
. By adjusting to focus on the mirror
7
, the fingerprint image is enlarged by the lens
5
, and the light reflected on the mirror
7
reaches the image pickup device
8
to process the fingerprint as a digital image, for example.
To process a small line pattern like a fingerprint as a digital image, the dimensions of the prism
4
and the lens
5
are prescribed, and the dimension of the case
1
for accommodating them is roughly determined accordingly. But, as to the Light beam for fingerprint checking, in order to accurately form a fingerprint image on the image pickup device, it is necessary to accurately set the positions of the prism
4
and the lens
5
within the case
1
.
Therefore, a position adjusting means has been used as shown as schematic views in FIG.
13
and FIG.
14
.
FIG. 13
is a diagrammatic sectional view showing a position adjusting means. In
FIG. 13
, the prism
4
is in contact with the case
1
by being pushed slightly by springs
11
,
12
from two sides toward the end on the lens side in the case
1
. Strength and direction of the springs
11
,
12
are adjusted so that the optical axis of the prism
4
agrees with the optical axis of the lens
5
at the position where the prism
4
is pushed within the case
1
by the springs
11
,
12
.
FIG. 14
is similar to
FIG. 13
except that screws
13
,
14
are used instead of the springs
11
,
12
used in FIG.
13
. The screws
13
,
14
are used in the same way as the springs.
In the prior arts shown in FIG.
13
and
FIG. 14
, the direction and strength to push the prism
4
in the case
1
toward the lens are adjusted by the springs
11
,
12
or the screws
13
,
14
, so that prescribed alignment of the optical axes of the lens
5
and the prism
4
is easily made.
But, when an external impact is applied to the case
1
after making the adjustment, and even if it is a small impact, the pressure and the position to apply the pressure to the prism
4
by the springs
11
,
12
are changed, and the optical axis of the prism
4
is deviated from the optical axis of the lens
5
and when the screws
13
,
14
are used, the optical axes are deviated when the screws are loosened.
Meanwhile, various devices have been proposed to fix the lens
5
.
FIG. 15
is a diagram for showing a first prior art.
A cylindrical lens guide
15
is integral with the case
1
and provided in a vertical position with respect to the surface of the prism
4
. A screw hole
16
is formed on the side face of the lens guide
15
, and a fixing screw
17
is driven into the screw hole
16
.
In the fixing device configured as described above, the prism
4
is mounted, the lens
5
is inserted into the lens guide
15
, and the bottom of the lens
5
is contacted to one surface of the prism
4
. In this state, the fixing screw
17
is tightened to fix the lens
5
.
FIG. 16
shows a second prior art.
A cylindrical lens guide
18
is integral with the case
1
and provided in a vertical position with respect to the surface of the prism
4
. An annular guide claw
19
is formed at the leading end of the lens guide
18
. And, a lens holder
20
is provided to cover the side face and bottom of the lens
5
.
In the fixing device as described above, the lens
5
is inserted into the lens guide
18
prior to mounting the prism
4
. When the prism
4
is mounted in this state, the bottom of the lens
5
is pressed against the surface of the prism
4
. By such a pressure, the curved part of the lens
5
is caught and fixed by the guide claw
19
. And, the bottom and side face of the lens
5
are fixed in close contact with the lens guide
18
and the prism
4
through the lens holder
20
.
FIG. 17
is a diagram showing a third prior art.
A cylindrical lens guide
21
is integral with the case
1
and provided in a vertical position with respect to the surface of the prism
4
. The leading end of the lens guide
21
has a conical surface within it and a conical claw
22
which has its center open. And, a lens holder
20
is provided to cover the side face and bottom of the lens
5
.
In the fixing device configured as described above, the lens
5
is inserted into the lens guide
21
prior to mounting the prism
4
. When the prism
4
is mounted in this state, the bottom of the lens
5
is pressed against the surface of the prism
4
. By such a pressure, the curved part of the lens
5
is advanced in sliding contact with the surface of the conical claw
22
, and the central axis of the lens
5
is aligned with the central axis of the conical claw
22
. And, the bottom and side face of the lens
5
are fixed in close contact with the lens guide
21
and the prism
4
through the lens holder
20
.
But, the first and second prior arts have to form the lens guides
15
,
18
having accurate dimensions to align the center axis of the lens with the optical axis of the prism
4
. Particularly, the dimensions are varied in a lens polishing process or other processes. It is very hard to form the lens guides
15
,
18
having the dimensions conforming with such variations.
And, in the first prior art when the fixing screw
17
was being tightened, the lens
5
was often inclined or displaced and fixed as shown in FIG.
18
.
On the other hand, in the second prior art, a pla
Blackwell Sanders Peper Martin LLP
Fujitsu Denso Ltd.
Shafer Ricky D.
LandOfFree
Optical device fixing device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optical device fixing device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical device fixing device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2862612