Electricity: circuit makers and breakers – Snap – Double snap
Reexamination Certificate
2002-01-11
2003-05-13
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Snap
Double snap
C200S516000
Reexamination Certificate
active
06563068
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a contact plate for use as a movable contact of a push-button switch, and more particularly to a disc contact plate press-formed into a dome shape, a sheet with the contact plate, and the structure of a switch device using the sheet.
2. Description of the Prior Art
Known structures of a contact plate for use as the movable contact of a push-button switch include the structures illustrated in FIG.
8
through FIG.
12
. FIG.
8
through
FIG. 10
are sectional views showing the relationship between a movable contact and a fixed contact, and
FIGS. 11 and 12
illustrate the relationship between the manipulative force on and the shifted quantity of the movable contact.
FIG. 8
shows a state in which a disc movable contact
51
formed by cupping a thin metallic sheet into a dome shape is mounted over a central fixed contact
53
and a peripheral fixed contact
54
, each similarly consisting of an electroconductive metallic sheet, arranged on the inner bottom face of a housing
52
consisting of synthetic resin or the like.
The movable contact
51
is formed of a skirt
51
a
rising from the outer circumference of a disc at a prescribed angle toward the center of the disc and a dome
51
b
, which is continuous from the skirt
51
a
and can be repetitively inverted. The skirt
51
a
and dome
51
b
are connected to each other by a smooth bend
51
c
. An outer peripheral end
51
d
of the skirt
51
a
is in contact with the peripheral fixed contact
54
at all times, and the inside of the top of the dome
51
b
constitutes a contact
51
e
, which comes into contact with the central fixed contact
53
when the dome
51
b
is repetitively inverted.
A gap is formed between the central fixed contact
53
and the peripheral fixed contact
54
, with the central fixed contact
53
being formed a step below the peripheral fixed contact
54
. As indicated by curve A in
FIG. 11
, when the dome
51
b
of the movable contact
51
is inverted the distance (shifted quantity) L
1
between the contact
51
e
and the central fixed contact
53
can be greater by the level difference of the step, thus the shifted quantity after the inversion of the movable contact
51
b
can be set greater than otherwise, resulting in a crispy feeling of click. In the diagram the vertical axis represents the manipulative force F, and the horizontal axis represents the shifted quantity L.
Incidentally, AO in the diagram denotes the tactile sensation (click feeling) curve of the movable contact
51
and LA denotes the point where the reaction force after the inversion of the movable contact
51
is at its minimum, i.e., the settable maximum of the shifted quantity.
FIG. 9
illustrates a state in which the movable contact
51
is mounted over a circuit board
55
on which a circuit pattern is formed of a copper foil or the like. In this case, since a central fixed contact
56
and a peripheral fixed contact
57
are formed of a copper foil or the like in a planar form over the circuit board
55
, the distance (the shifted quantity) L
2
between the contact
5
Se and the central fixed contact
56
is less than L
1
when the dome
51
b
of the movable contact
51
is inverted.
FIG. 10
shows a movable contact
58
formed in a state in which the rising angle &thgr;c of a skirt
58
a
is set more nearly upright than &thgr;b shown in
FIG. 9
(&thgr;b<&thgr;c) so that when the dome
58
b
of the movable contact
58
is inverted the distance (the shifted quantity) L
3
between a contact
58
e
and the central fixed contact
56
becomes equal to L
1
(L
3
=L
1
). As indicated by curve C in
FIG. 12
, when the dome
58
b
of the movable contact
58
is inverted, the distance (the shifted quantity) L
3
between the contact
58
e
and the central fixed contact
56
can be greater, the shifted quantity after the inversion of the movable contact
58
can be set greater than otherwise, resulting in a crispy feeling of click.
However, in the above-described structure of the movable contact
51
according to the prior art, when it is to be used in the planar circuit board
55
and when the dome
51
b
of the movable contact
51
is inverted, the distance (the shifted quantity) L
2
between the contact
51
e
and the central fixed contact
56
is less than L
1
. The shifted quantity thus becomes smaller after the inversion of the movable contact
51
as indicated by B in
FIG. 11
, resulting in a problem of a dull feeling of click.
Further, if the rising angle &thgr;c of the skirt
58
a
is increased, the reaction force of the tactile sensation curve CO of the movable contact
58
will take on a negative value at point LC as shown in
FIG. 12
, resulting in a problem that the movable contact
58
remains inverted instead of automatically returning to the original state.
SUMMARY OF THE INVENTION
An object of the present invention, therefore, is to solve the problems noted above and provide a movable contact structure which, even when used in a planar circuit board, can provide a crispy click feeling and will not fail to return to an original position after being inverted.
In order to solve the problems noted above, according to a first aspect of the invention, there is provided a contact plate consisting of a disc formed into a dome shape by cupping a center of a thin metallic sheet in one direction, provided with a skirt rising at a prescribed angle from an outer circumference of this disc toward a center of the disc, and a dome which is continuous from this skirt and can be repetitively inverted, the connecting part between the skirt and the dome being formed in multiple steps via a plurality of bent portions.
According to a second aspect of the invention, a projection in contact with a fixed contact is formed on an inner face of the dome.
According to a third aspect of the invention, an external face of the dome of the contact plate according to the first or second aspect of the invention is stuck to an adhesive back face layer of an insulating sheet, and the contact plate and an lower face of the insulating sheet are covered with a peelable protective sheet.
According to a fourth aspect of the invention, a spacer sheet having an accommodating hole for accommodating the contact plate is provided between the insulating sheet and the protective sheet.
According to a fifth aspect of the invention, the protective sheet of the sheet with the contact plate according to the third or fourth aspect of the invention is peeled, and the sheet with the contact plate after peeling is stuck to a circuit board, over which a plurality of fixed contacts are arranged, by the adhesive back face layer of the insulating sheet so that the contact plate is opposite the fixed contacts.
According to a sixth aspect of the invention, there is provided a switch device having the contact plate according to the first or second aspect of the invention and an accommodating section, whose inner bottom face is provided with a housing over which a fixed contact is arranged and a suppressing member liftably snapped into the accommodating section, wherein the contact plate is arranged opposite the fixed contact to be suppressible by the suppressing member.
REFERENCES:
patent: 4254309 (1981-03-01), Johnson
patent: 4343973 (1982-08-01), Main
patent: 4933522 (1990-06-01), Celander
patent: 5845766 (1998-12-01), Sako et al.
patent: 5924555 (1999-07-01), Sadamori et al.
patent: 5986228 (1999-11-01), Okamoto et al.
patent: 6259046 (2001-07-01), Iwama et al.
patent: 6271491 (2001-08-01), Ono et al.
Shimatani Katsuaki
Yamagata Takeo
Alps Electric Co. ,Ltd.
Beyer Weaver & Thomas
Friedhofer Michael
LandOfFree
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