Electricity: circuit makers and breakers – Snap – Double snap
Reexamination Certificate
2002-03-28
2003-09-30
Donovan, Lincoln (Department: 2832)
Electricity: circuit makers and breakers
Snap
Double snap
C200S509000
Reexamination Certificate
active
06627830
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a push-button switch adapted to shift from a first OFF state to an ON state according to the increase of the amount of depression of a push button and then to shift to a second OFF state according to further depression of the push button, and also relates to a teaching pendant comprising the same.
BACKGROUND ART
In cases where, for example, a manual operation is performed on numerically controlled machines such as robots, an operator often enters a dangerous area to carry out his job. In such cases, a teaching pendant with a push-button switch, such as called an enable switch (or deadman switch), is used for preventing an accident due to contact with the machine during the work.
As shown in
FIG. 34
, a teaching pendant
600
is a portable unit which is used as connected with a control unit to teach a program to the robot or to operate the robot. The teaching pendant
600
includes an input keyboard
601
disposed on a main surface and a push-button switch (enable switch)
602
disposed on one side surface thereof. In some cases, the push-button switch
602
may be disposed on a rear surface of the teaching pendant
600
. The teaching pendant
600
further includes a signal cable
603
for connection with the control unit not shown.
Such a teaching pendant employs a push-button switch which is called a snap action type, as shown in
FIG. 35
for example.
As seen in
FIG. 35
, the push-button switch
602
includes a push button
605
and a microswitch
606
in opposing relation with the push button. The push button
605
is provided with a leaf spring
607
extended downwardly from a bottom surface thereof. Disposed on a top surface of the microswitch
606
are a resilient push plate
608
and an actuator
609
. A bent portion
607
a
is formed at a tip of the leaf spring
607
.
The push-button switch
602
is used as follows. First, the teaching pendant
600
incorporating the push-button switch
602
is connected, via the signal cable
603
, with a control panel of a machine to be manually operated. If the push-button switch
602
is in the OFF state at this time, manipulating the keyboard
601
of the teaching pendant
600
does not effect the key entry.
Next, depressing the push button
605
brings the bent portion
607
a
of the leaf spring
607
, moved in unison with the push button
605
, into engagement with the push plate
608
of the microswitch
606
. At the same time, the push plate
608
is resiliently deformed downward to press down the actuator
609
, as shown in FIG.
36
. This causes the actuator
609
to descend to bring a contact within the microswitch
606
into a contacted state, so that the microswitch
606
is shifted to the ON state.
The operator performs key entry via the keyboard
601
of the teaching pendant
600
while keeping the push button
605
depressed so as to maintain the microswitch in the ON state. If, during the operation, the operator releases the push button
605
sensing the danger of contacting some moving part of the machine manually operated, the push button
605
returns to the state shown in
FIG. 35
, thereby shifting the microswitch
606
to the first OFF state or the initial state. That is, the machine is brought into standstill.
In a case where the operator, who is in panic facing the imminent danger, further depresses the push button
605
, the bent portion
607
a
of the leaf spring
607
slides on the push plate
608
to disengage therefrom, as shown in
FIG. 37
, so that the push plate
608
is returned to its original position by its restoring force. This shifts the microswitch
606
to the second OFF state for deactivating the machine.
Thus, the push-button switch
602
is adapted to permit the key entry through the keyboard
601
of the teaching pendant
600
only when the microswitch
606
is in the ON state. Furthermore, the push-button switch
602
can be set to any of the three positions (the first OFF state, ON state and second OFF state) according to the amount of depression of the push button
605
. Therefore, the operator's intent during the manual operation of the machine can be distinctly implemented and hence, the operator's safety is ensured.
As the push-button switch having such three positions, there may be employed a push-button switch of a so-called slow action type, as shown in FIG.
38
.
As shown in
FIG. 38
, such a push-button switch
701
includes a switch case
702
, a push button
703
depressibly supported by the switch case
702
, a pair of stationary terminals
705
each attached to a leaf spring
704
disposed within the switch case
703
, a pair of movable terminals
707
attached to a bracket
706
and adapted to be brought into or out of contact with the stationary terminals
705
, and a switching mechanism
708
moving in response to the depression of the push button
703
for bringing the movable terminals
707
into contact with the stationary terminals
705
and designed to separate the movable terminals
707
from the stationary terminals
705
when the depression of the push button reaches a predetermined amount. In the push-button switch
701
, the movable terminal
707
and the stationary terminal
705
constitute a normally open contact.
The push button
703
is formed with an accommodating portion
709
defining a rectangular internal space in plan, the accommodating portion
709
formed with slopes
710
on opposite walls thereof.
The switching mechanism
708
includes an insertion member
712
disposed in the accommodating portion
709
of the push button
703
and formed with a pair of bores
711
, a pair of slide blocks
713
disposed in the respective bores
711
of the insertion member
712
as allowed to move horizontally (the transverse direction as seen in FIG.
38
), a helical spring
714
interconnecting the insertion member
712
and the bracket
706
and urging the movable terminals
707
downwardly, and a shaft member
715
projecting downward from the bracket
706
.
The slide blocks
713
are urged toward opposite ends of the push button
703
by helical springs
716
disposed in the respective bores
711
of the insertion member
712
. The slide blocks
713
are each formed with a slope
717
at one end thereof for engagement with each of the slopes
710
of the push button
703
.
The shaft member
715
has its lower portion inserted in a bore
718
formed at a bottom of the switch case
702
. Disposed in the bore
718
is a return spring
719
, an upper end of which is fixed to a lower end of the shaft member
715
. Thus, the shaft member
715
is normally urged upward by an urging force of the return spring
719
.
When the undepressed push button
703
in the first OFF state is depressed, the switching mechanism
708
is moved downward as interlocked with the push button
703
thereby pushing down the movable terminals
707
into contact with the stationary terminals
705
, as shown in FIG.
39
. Thus, the push-button switch
701
is shifted to the ON state. At this time, the slopes
710
of the push button
703
apply a pressure to the slopes
717
of the slide blocks
713
for moving the slide blocks
713
inwardly. However, the urging force of the helical spring
714
urging the slide blocks
713
upwardly is greater than this pressure, so that the slide blocks
713
stay at places to maintain the engagement with the push button
703
.
When the push button
703
in the ON state is further depressed, the urging force of the helical spring
714
surpasses the force for urging the slide blocks
713
outwardly, so that the slide blocks
713
are moved inwardly of the insertion member
712
as the slopes
717
of the slide blocks
713
slid on the slopes
710
of the push button
703
, as shown in FIG.
40
. This results in the disengagement of the slide blocks
713
from the push button
703
, while the switching mechanism
708
is moved upward by the return spring
719
, as shown in FIG.
41
. This movement involves an upward movement of the movable terminals
707
, which are separated from the stationary
Fukui Takao
Kamino Yasushi
Maeda Ken
Miyauchi Kenji
Okada Kazuya
Donovan Lincoln
Idec Izumi Corporation
Jordan and Hamburg LLP
Klaus Lisa
LandOfFree
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