Electricity: circuit makers and breakers – Snap – Double snap
Reexamination Certificate
1999-10-12
2001-09-11
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Snap
Double snap
C200S00100B, C200S01600R, C200S0510LM, C200S298000, C200S523000
Reexamination Certificate
active
06288352
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a push-button switch and more particularly, to a push-button switch which is shifted from an initial or first OFF state to an ON state and then, to a second OFF state as the amount of depression of the push-button increases.
2. Description of the Background Art
In cases where, for example, a manual operation is performed on a numerically controlled machine such as a robot, an operator often enters a dangerous area to carry out his job. In such cases, a pendant with a push-button, such as called an enable switch (or deadman switch), is used for preventing the occurrence of an accident during the work.
This pendant is a portable unit which is enabled by connection with an operation device to teach a program to the robot or operate the robot. As shown in
FIG. 80
, the pendant
500
includes an input keyboard
501
disposed on a main surface and a push-button switch (enable switch)
502
disposed on one side surface thereof. Incidentally, the push-button switch
502
may be sometimes disposed on the rear side of the pendant
500
. The pendant
500
further includes a signal cable
503
for connection with the operation device not shown.
As shown in
FIG. 77
, a conventional push-button switch
502
includes a push button
505
and a microswitch
506
disposed opposite to the push button. Disposed on a lower surface of the push button
505
is a leaf spring
507
extended downwardly therefrom. Disposed on a top surface of the microswitch
506
are a resilient push plate
508
and an actuator
509
. A bent portion
507
a
is formed at a tip of the leaf spring
507
.
When the push-button switch
502
is used, the pendant
500
incorporating the push-button switch
502
is first connected, via the signal cable
503
, to a control panel of a machine to be manually operated. If the push-button switch is in the OFF state at this time, manipulating the keyboard
501
of the pendant
500
does not effect the key entry.
Upon subsequent depression of the push button
505
, the bent portion
507
a
of the leaf spring
507
moving along with the push button
505
engages the push plate
508
of the microswitch
506
, and the push plate
508
is resiliently deformed downward to press down the actuator
509
, as shown in FIG.
78
. This causes the actuator
509
to lower for establishing contact between contacts within the microswitch
506
, thereby shifting the microswitch
506
to the ON state.
The operator keys in through the keyboard
501
of the pendant while keeping the push button
505
depressed for maintaining the microswitch in the ON state. If, at this time, the operator releases the push button
505
, sensing the danger of contacting some moving part of the machine manually operated, the push button
505
returns to the state shown in
FIG. 77
for turning OFF the microswitch
506
. Thus, the machine is stopped.
In a case where the operator, who has panicked sensing imminent danger, further presses down the push button
505
, the bent portion
507
a
of the leaf spring
507
slides on the push plate
508
to disengage therefrom, as shown in
FIG. 79
, so that the push plate
508
is returned to its original position by its restoring force. This shifts the microswitch
506
to the OFF state for stopping the machine.
Thus, the push-button switch
502
is adapted to enable the keyboard
501
of the pendant
500
or permits the key entry through the keyboard
502
for manual operation only when the microswitch
506
is in the ON state. Therefore, the operator's intent at the manual operation can be made distinct and hence, the operator's safety is ensured.
However, the known push-button switch is arranged such that the switch is maintained in the ON state by the engagement of the leaf spring and shifted to the OFF state by disengagement thereof which results from increased elastic deformation thereof. Accordingly, precisions of the leaf springs significantly affect a timing of shift between the ON and OFF states.
Therefore, the switch may sometimes be quick to be shifted from the ON state to the OFF state or slow to be shifted depending upon the variations of the leaf springs. Thus, the switch suffers from unstable operation and poor switching accuracy.
SUMMARY OF THE INVENTION
It is therefore, an object of the present invention to provide a push-button switch adapted for stable operation.
Another object of the invention is to provide a push-button switch capable of forcibly separating the contacts for shifting the switch to the OFF state, even if they are fused to each other, thereby providing even more stable operation of the switch.
It is still another object of the invention to provide a push-button switch which provides good operability and a positive shift to the OFF state in the event of an emergency when used as the enable switch of a teaching pendant for industrial manipulating robots.
REFERENCES:
patent: 4216358 (1980-08-01), Brozille
patent: 5115179 (1992-05-01), Fujii et al.
patent: 5665945 (1997-09-01), Oshima
patent: 6057521 (2000-05-01), Krebs et al.
patent: 735 643 (1943-05-01), None
patent: 0 702 384 (1996-03-01), None
patent: 59-138142 (1984-09-01), None
patent: 2-65834 (1990-05-01), None
patent: 7-262865 (1995-10-01), None
patent: 8-241649 (1996-03-01), None
Fujita Toshihiro
Fujitani Shigetoshi
Fukui Takao
Inoue Kenji
Kamino Yasushi
Friedhofer Michael
Griffin & Szipl, P.C.
Idec Izuni Corporation
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