Electricity: circuit makers and breakers – Solid contact – Membrane type
Reexamination Certificate
2001-02-23
2001-10-16
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Solid contact
Membrane type
C200S516000, C200S00100B
Reexamination Certificate
active
06303887
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a pushbutton switch element for a pushbutton switch structure used for electronic equipment, a portable terminal, an automobile component or the like, and more particularly to a pushbutton switch element for a pushbutton switch structure suitable for use for equipment such as a power window switch for an automobile or the like which is required to carry out an on-off operation of an electric circuit thereof in a multistage manner while generating a click in a multistage manner which is felt by a user.
A mechanical switch has been conventionally used as a switch which generates a click in a multistage way or manner which is felt by a user. Such a mechanical switch is constructed in such a manner as shown in
FIG. 7A
by way of example. There is also known another conventional mechanical switch which is constructed as shown in FIG.
8
.
The conventional mechanical switch shown in each of
FIGS. 7A and 8
is typically used for an electronic instrument such as an electronic piano, a power window switch for an automobile or the like so as to generate a click which is felt by a user or carry out electrical connection in a multistage manner.
The conventional mechanical switch generally designated by reference numeral
101
in
FIG. 7A
includes a housing
101
a
, a leaf spring
101
b,
a pressing force transmission member
101
c,
a spring
101
d,
a lead frame
101
e
and a base plate
101
f.
The leaf spring
101
b
is provided with a projection
101
b
1
and the pressing force transmission member
101
c
is provided with two recesses
101
c
1
and
101
c
2
. Locked fitting of the projection
101
b
1
of the leaf spring
101
b
in each of the recesses
101
c
1
and
101
c
2
of the pressing force transmission member
101
c
permits slide resistance or friction resistance between the leaf spring
101
b
and the pressing force transmission member
101
c
to be different from that therebetween obtained when the locked fitting is not carried out, so that the mechanical switch may generate a click which is felt by a user. The mechanical switch of
FIG. 7A
thus constructed exhibits a load curve shown in
FIG. 7B
, wherein a point F
1
indicates a click generated during first fitting of the recess
101
c
1
on the projection
101
b
1
and a point F
2
indicates a click generated during second fitting of the recess
101
c
2
on the projection
101
b
1
.
The conventional mechanical switch
102
generally designated by reference numeral
102
in
FIG. 8
includes a housing
102
a
, a frame
102
b
, a slide member
102
c
made of a plastic material, a spring
102
d
made of metal, plungers
102
e
, a cover member
102
f
made of an elastomer material, a key top
102
g
made of a resin material and a base plate
102
h
. Thus, the mechanical switch
102
is constituted by seven members made of plastic materials, the metal spring and the base plate to generate a click like that of the mechanical switch
101
described above. In the mechanical switch
102
, mechanical locking among the plastic members by fitting permits the mechanical switch
102
to generate a click which is felt by a user due to resistance to movement among the members. The mechanical switch
102
exhibits substantially the same load curve as that shown in FIG.
7
B.
In addition, there is used a press switch which is made of a silicone rubber material and constructed so as to generate a click in a multistage manner which is felt by a user. In general, a pushbutton switch made of a silicone rubber material attains a switching operation while being reduced in the number of parts, resulting in it being commonly used for a variety of pushbutton switch equipment such as an electronic calculator, a word processor, a remote controller and the like.
Now, a conventional pushbutton switch cover made of a silicone rubber material and adapted to be used for a word processor will be described with reference to
FIGS. 9A and 9B
.
A pushbutton switch cover
103
for a pushbutton switch structure is integrally formed so as to generate a click in a two-stage manner which is felt by a user and made of a rubber-like elastic material represented by silicone rubber. In
FIG. 9A
, only one pushbutton switch is illustrated. The pushbutton switch cover
103
includes a cylindrical rib
103
a
arranged so as to be positioned at a top of the pushbutton switch, a first dome-like section
103
b
for generating a first click at a point F
1
(FIG.
9
B), a second dome-like section
103
c
of a thin wall arranged at a central position of the pushbutton switch so as to generate a second click at a point F
2
, and a projection
103
b
2
formed so as to downwardly project from a ceiling of the second dome-like section
103
c
and provided on a lower surface thereof with a contact
103
b
1
. The rib
103
a
and thin-wall dome sections
103
b
and
103
c
are flexed in order by pressing a pushbutton, to thereby generate a click in a two-stage manner which is felt by a user. The pushbutton switch thus constructed is mainly used for a key board for a word processor intended to prevent thecitis.
In the past, a switch such as a power window switch for an automobile or the like which is demanded not only to exhibit two or more switching functions but to generate an enhanced click which is felt by a user (a click ratio being typically as high as 30% or more) generally is necessarily required to use a mechanical switch (tactile switch) mechanism which utilizes slide resistance due to a combination of functional parts. Also, the mechanical switch shown in
FIG. 8
is increased in the number of parts and complicated in structure, to thereby cause generation of rebound sound or contact sound during sliding of the parts and returning of the button, as well as resonance sound due to external vibration such as vibration of an engine of an automobile. Also, a so-called rubber switch such as the switch shown in
FIG. 9A
which exhibits two or more conductive functions fails to generate a click sufficient to permit a user or operator to recognize turning-on of the switch carried out twice by the feel.
This is due to the fact that the click is generated only by both deformation and restoration of the rib
103
a
and dome sections
103
b
and
103
c
which are made of a thin-wall rubber-like elastic material. In other words, this is due to the fact that the click is generated by impact resilience of the elastic material and restriction of a configuration of the dome sections determined depending on a material therefor.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing disadvantage of the prior art.
Accordingly, it is an object of the present invention to provide a pushbutton switch element for a pushbutton switch structure which is capable of generating a distinct click in a multistage manner which is felt by a user and reducing generation of sound during operation of a pushbutton as well as reducing generation of resonance sound.
In accordance with the present invention, a pushbutton switch element for a pushbutton switch structure is provided. The pushbutton switch element includes a movable thin wall section and a pushbutton section formed on an upper portion of a center of the movable thin wall section, and a first movable contact arranged so as to downwardly extend from a lower surface of the pushbutton section. The pushbutton switch element further includes a second movable contact having a substantially annular shape and arranged so as to downwardly extend from the lower surface of the pushbutton section and surround the first movable contact while being spaced from the first movable contact at a predetermined interval, and an inverted cup-like member adhesively attached to a distal end of the first movable contact and constructed so as to repeatedly carry out a flex operation between a flexed state and an original state restored from the flexed state while concurrently generating a click which is felt by a user.
In a preferred embodiment of the present invention, the second movable
Friedhofer Michael
Lerner David Littenberg Krumholz & Mentlik LLP
Shin-Etsu Polymer Co. Ltd.
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