Electricity: circuit makers and breakers – Solid contact – Membrane type
Reexamination Certificate
2003-06-27
2004-06-01
Friedhofer, Michael A. (Department: 2832)
Electricity: circuit makers and breakers
Solid contact
Membrane type
C200S0050EA, C200S517000
Reexamination Certificate
active
06743994
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a slim switch which is employed in operation areas of various apparatuses such as electrical appliances.
A membrane switch, for example, is known as the slim switch. This membrane switch is employed in operation areas of various apparatuses such as electric appliances, because it is highly reliable and contributes to realization of space saving.
In
FIG. 3
, a membrane switch
51
comprises an exterior sheet
52
, a spacer sheet
53
and a circuitry
54
, which are laminated on a base plate
55
. The respective members are bonded with each other with adhesive layers
56
.
A movable contact
57
is provided on a predetermined position of a back face of the exterior sheet
52
. A through hole
58
is formed in the spacer sheet
53
in alignment with the position of the movable contact
57
. The circuitry
54
is provided with a switch circuit having an appropriate pattern, which is not shown. Fixed contacts
59
are provided on the switch circuit at positions opposed to the movable contact
57
.
In the membrane switch
51
having the above described structure, when a front face of the exterior sheet
52
is pressed downward with switch operation of a finger
60
of an operator, as shown by an arrow mark, the movable contact
57
and the fixed contacts
59
are brought into electrical contact with each other in association with flexure of the exterior sheet
52
. In this manner, the conductive condition of the non-shown switch circuit is established. On the other hand, when the finger
60
of the operator is detached from the membrane switch
51
, the exterior sheet
52
which is flexed until then will be recovered to the original state, and the conductive condition of the switch circuit will be released.
Besides the above described membrane switch
51
, a dome switch having the following structure is commonly used as the slim switch.
In
FIGS. 4 and 5
, a dome switch
61
comprises an exterior sheet
62
, a spacer sheet
63
and a circuitry
64
which are laminated on a base plate
65
. The respective members are bonded to each other with adhesive layers
66
. Moreover, the dome switch
61
is designed in such a manner that more improved feeling of click as compared with the above described membrane switch
51
(see
FIG. 3
) can be obtained.
The exterior sheet
62
is formed with a dome part
67
which is projected in a dome shape. A movable contact
68
is provided at the top of a back face of the dome part
67
. A through hole
69
is formed in the spacer sheet
63
at a position corresponding to the dome part
67
. Into this through hole
69
, the dome part
67
which is projected downward is adapted to be inserted. The circuitry
64
is provided with a not-shown switch circuit with an appropriate pattern. Fixed contacts
70
are provided on the switch circuit at positions opposed to the movable contact
68
.
In the dome switch
61
having the above described structure, when the dome part
67
is pressed downward with switch operation of a finger
71
of an operator as shown by an arrow mark, and the movable contact
68
of the dome part
67
which is projected downward comes into electrical contact with the fixed contacts
70
of the circuitry
64
, the conductive condition of the non-shown switch circuit can be obtained. When the dome part
67
is projected downward, the feeling of click can be obtained. On the other hand, when the finger
71
of the operator is detached from the dome part
67
, the dome part
67
which is projected downward until then will be recovered to the original state, and the conductive condition of the non-shown switch circuit will be released.
The above described membrane switch
51
and the dome switch
61
have had several problems as follows.
First, there is a problem that it is difficult to secure a sufficient stroke length when the switch is operated. There is such an anxiety that a person who operates the switch is unable to reliably recognize ON-OFF of the switch.
Second, there is a problem that operation load of the switch operation is determined to some extent, depending on a shape of the part to be pressed, and it is actually difficult to change feeling of the switch operation even if so desired. Third, there is another problem that freeness of design is limited due to the shape of the part to be pressed.
Lastly, in the dome switch
61
, when the dome part
67
which is projected downward is recovered to the original state, speed of the recovery may be faster than speed of the finger
71
to be detached. Therefore, there is a problem that some of the operators may feel uncomfortable when they receive a repulsive force of the dome part
67
.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a slim switch in which a sufficient stroke length at the switch operation can be secured, and improved feeling of the switch operation can be obtained. It is also an object of the invention to provide a slim switch in which freeness of design can be enhanced.
In order to achieve the above object, according to the invention, there is provided a switch, comprising:
a circuitry, provided with a first switching contact;
a first spacer, laminated on the circuitry so as to provide a first space above the first switching contact;
a first, elastic sheet member, laminated on the first spacer and provided with a second switching contact opposing to the first switching contact in the first space, the first sheet member being operable to deform while using the first space to bring the second switching contact into an electrical contact with the first switching contact;
a second spacer, laminated on the first sheet member so as to provide a second space above a first part of the first sheet member;
a second sheet member, laminated on the second spacer, the second sheet member being operable to deform while using the second space to thereby deform the first part of the first sheet member; and
an elastic member, interposed between the first sheet member and the second sheet member at the second space, the elastic member having an elastic deformability which is higher than an elastic deformability of the first sheet member.
In such a configuration, when the switch is operated, the second sheet member is first subjected to a pressure load and deformed, and at the same time, the elastic member is elastically deformed. Then, the first part of the first sheet member is deformed downward, so that the second switching contact is brought into contact with the first switching contact. With this action, the switch is turned on. On the other hand, when the pressure load is released, the first part of the first sheet member deformed downward, the elastic member elastically deformed, and the second sheet member deformed downward are recovered to their original state, and the conductive condition of the switch is released. On this occasion, a repulsive force of the first part of the first sheet member is absorbed by the elastic member.
Accordingly, not only a sufficient stroke length can be secured, but also the freeness of design of the second sheet member serving as an exterior appearance member can be enhanced. Further, the feeling at the switch operation can be improved.
Preferably, the static member is fixed to at least one of faces of the first sheet member and the second sheet member which are opposed to each other through the second space.
In such a configuration, since distance between the first sheet member and the second sheet member is kept constant, the stroke length can be always secured in a stabilized state. Moreover, the feeling at the switch operation can be maintained in a favorable condition.
Preferably, the first part of the first sheet member is projected toward the second sheet member in a condition where no load is applied thereto.
REFERENCES:
patent: 4417294 (1983-11-01), Herron, Jr.
patent: 4598181 (1986-07-01), Selby
patent: 5306886 (1994-04-01), Yamada
patent: 5697493 (1997-12-01), Sach et al.
patent: 5950808 (1999-09-01), Tanabe et al.
patent: 9-293430 (1997-1
Friedhofer Michael A.
Yazaki -Corporation
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