Photo interrupter with dual-direction detection ability

Details Photo interrupter with dual-direction detection ability Photo interrupter with dual-direction detection ability

2002-01-23

2003-10-28

Fulton, Christopher W. (Department: 2859)

Radiant energy

Photocells; circuits and apparatus

Signal isolator

C250S239000

Reexamination Certificate

active

06639238

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a photo interrupter with dual-direction detection ability, especially to a photo interrupter with dual-direction detection ability to sense the paper fed in different directions.
BACKGROUND OF THE INVENTION
The paper detector used in conventional printer generally comprises a photo interrupter with paper detection function. As shown in
FIGS. 1 and 2
, a prior art photo interrupter with single-direction detection function comprises a main body
1
a
, a pointer
2
a
and a spring
3
a
. The main body
1
a
comprises a recess
13
a
between a light emitter
11
a
and a light receiver
12
a
, and retainers
14
a
and
15
a
on both sides of the recess
13
a
. The pointer
2
a
has two rotational pivots
21
a
and
22
a
on both sides thereof and the rotational pivots
21
a
and
22
a
are pivotally arranged on the retainers
14
a
and
15
a
. The pointer
2
a
has a baffle
23
a
at front side thereof and located in the recess
13
a
to block light from the light emitter
11
a
. Moreover, the baffle
23
a
is abutted to the main body la such that the pointer
2
a
has counterclockwise rotation only. The pointer
2
a
further has a pendulum end
24
a
on bottom thereof to detection the presence of paper. The spring
3
a
is looped on the rotational pivot
22
a
on one side of the pointer
2
a
to provide a reverse torque to the pointer
2
a
. The spring
3
a
has one side fixed to a slit
25
a
of the pointer
2
a
and another side lay on the main body la. When the pendulum end
24
a
of the pointer
2
a
is driven to move in counterclockwise direction, the spring
3
a
is distorted to produce a reverse torque. When the force exerted on the pendulum end
24
a
of the pointer
2
a
is not present, the pointer
2
a
is returned to original position due to the reverse torque of the spring
3
a
. However, the pointer
2
a
has only rotation in counterclockwise direction and cannot provide dual-direction detection function. Therefore, the photo interrupter is not-feasible for double-side printing application.
FIGS. 3 and 4
show another prior art photo interrupter with double-direction detection function, wherein the baffle
23
a
of the pointer
2
a
is not lay on the main body
1
a
. The spring
3
a
has two ends fixed to a hook
16
a
on the main body
1
a
and fixed to the slit
25
a
of the pointer
2
a
such that the pointer
2
a
can rotate in both clockwise and counterclockwise directions. However, this imposed restrict demand on design of the spring
3
a
. Once the torque requirement of the pointer
2
a
is changed, the design of the spring
3
a
should be renewed. Moreover, the single spring
3
a
can provide single-valued torque, which is not suitable for pointer
2
a
requiring different torques along different rotation directions.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a photo interrupter with dual-direction detection ability, wherein the spring has simple design with consideration of rotation direction only.
It is another object of the present invention to provide a photo interrupter with dual-direction detection ability, wherein the restoring torque for respective direction can be easily changed.
It is still another object of the present invention to provide a photo interrupter with dual-direction detection ability, wherein photo interrupter has more than one springs to provides corresponding torque for respective direction.
To achieve above object, the present invention provides a photo interrupter with dual-direction detection ability, which comprises a main body, a pointer, a first spring and a second spring. The main body has retainers for pivotally clamping the pointer such that the pointer can rotate both in counterclockwise and clockwise directions. The pointer has a baffle in the recess to block a light from a light emitter to a light receiver and a pendulum end to sense the presence of paper. The first spring provides a counterclockwise restoring force for the pointer and the second spring provide a clockwise restoring force for the pointer such that the photo interrupter can sense paper fed in both directions.


REFERENCES:
patent: 5156464 (1992-10-01), Sakai
patent: 5200608 (1993-04-01), Kitajima
patent: 5672884 (1997-09-01), Muhleck et al.
patent: 5700003 (1997-12-01), Sung
patent: 6050471 (2000-04-01), Yagi
patent: 6102389 (2000-08-01), Sakurai et al.
patent: 6140635 (2000-10-01), Kazumi et al.
patent: 6179498 (2001-01-01), Tsukada
patent: 6409043 (2002-06-01), Fujita et al.
patent: 11180589 (1999-07-01), None
patent: 200211809 (2000-08-01), None

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