Electricity: circuit makers and breakers – Multiple circuit control – Sequential operations
Reexamination Certificate
2001-02-06
2002-12-10
Luebke, Renee (Department: 2833)
Electricity: circuit makers and breakers
Multiple circuit control
Sequential operations
C200S406000
Reexamination Certificate
active
06492602
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a two-position pushbutton switch suitable for use in a digital camera.
2. Description of the Related Art
A conventional two-position pushbutton switch will be described below with reference to
FIGS. 32
to
35
. First, second, and third switch sections S
3
, S
4
, and S
5
are held in a casing
51
.
The first switch section S
3
is formed of a membrane switch in which an insulating sheet
54
with an opening is interposed in a folded sheet
53
having a fixed contact and a movable contact, as shown in FIG.
34
.
The second switch section S
4
is formed of a membrane switch in which a fixed contact formed on a sheet
52
and a movable contact formed on a sheet
53
are opposed to each other via the opening of the sheet
54
.
In the casing
51
, a platelike support member
55
is also placed, and an operating member
56
is mounted on the support member
55
.
The operating member
56
includes a mounting portion
56
a
mounted on the support member
55
, an elastic portion
56
b
connected to the mounting portion
56
a
, a projection
56
c
formed at one end of the elastic portion
56
b
, an operating portion
56
e
connected to the mounting portion
56
a
via hinge portions
56
d
, a projection
56
f
formed at the end of the operating portion
56
e
, and a projection
56
g
formed at the bottom center of the operating portion
56
e.
The sheet
53
is bent in the shape of the letter U, and the first switch section S
3
at the leading end thereof is placed on the upper surface of the operating portion
56
e
. A dome-shaped click spring
57
having a small working force and a small diameter is laid on the first switch section S
3
.
The second switch section S
4
, composed of three stacked sheets
52
,
53
, and
54
, is placed on the upper surface of the support member
55
, and a dome-shaped click spring.
58
having a great working force and a large diameter is laid on the second switch section S
4
and below the projection
56
g
. The third switch section S
5
is placed below the projection
56
f.
A key top
59
includes an operating portion
59
a
, two projections
59
b
and
59
c
formed on the lower side of the operating portion
59
a
, a support portion
59
d
formed at one end of the operating portion
59
a
, and a retaining portion
59
e
formed at the other end of the operating portion
59
a
. The key top
59
is supported in a cantilevered manner at the support portion
59
d.
When the key top
59
is mounted, the operating portion
59
a
is exposed from an opening portion
51
a
of the casing
51
, the projection
59
b
is in contact with the projection
56
c
of the operating member
56
, and the projection
59
c
is in contact with the click spring
57
. Furthermore, the retaining portion
59
e
is retained on the inner surface of the casing
51
by the resilient force of the elastic portion
56
b
of the operating member
56
.
The operation of the conventional two-position pushbutton switch will now be described. First, when the operating portion
59
a
of the key top
59
is pressed, the key top
59
tilts relative to the support portion
59
d
so as to simultaneously push the projection
56
c
and the click spring
57
.
Then, the click spring
57
with a small working force is first inverted and presses the sheet
53
(folded portion) so that the movable contact is put into contact with the fixed contact thereon, thereby turning on the first switch section S
3
.
In this case, the relationship between the stroke A and the working force B of the key top
59
is represented by a curve C
3
, and the stroke A
3
is short, as shown in FIG.
35
.
When the key top
59
is further pressed in this state, the operating portion
56
e of the operating member
56
is tilted via the hinge portions
56
d
, and therefore, the projection
56
g
of the operating portion
56
e presses the click spring
58
.
Subsequently, the click spring
58
with a large working force is inverted and presses the sheet
53
so that the movable contact is put into contact with the fixed contact of the sheet
52
, thereby turning on the second switch section S
4
.
In this case, the stroke A and the working force B of the key top
59
have a relationship represented by a curve C
4
, as shown in FIG.
35
.
In response to the tilting of the operating portion
56
e
, the projection
56
f
operates the third switch section S
5
so as to switch from the ON state to an OFF state.
When the key top
59
is then released from pressing, it is pushed back by the elastic portion
56
b
, and the operating portion
56
e
is returned to its initial state by-the hinge portions
56
d
. Furthermore, the click springs
57
and
58
are inverted into their initial states because of their own resilient forces. This turns off the first and second switch sections S
3
and S
4
, and returns the third switch section S
5
into an ON state.
In a case in which such a two-position pushbutton switch is adopted-in a digital camera, focusing is performed by operating the first switch section S
3
by a first press, and a shutter is released. by operating the second switch section S
4
by a second press.
In the conventional two-state pushbutton switch, however, since the click spring
57
is pressed and inverted immediately after the key top
59
abuts the click spring
57
, a stroke A
3
of the first press is short, as shown in FIG.
35
.
For this reason, when such a two-position pushbutton switch is adopted in a digital camera, the press stroke for focusing is short and the focusing operation is difficult. This decreases ease of use.
Furthermore, the operating member
56
includes the, mounting portion
56
a
and the operating portion
56
e
supported on the mounting portion
56
a
via the hinge portions
56
d
, and the operating
56
e
is able to move via the hinge portions
56
d
. This requires a large space in the lateral direction and increases the size of the switch.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a two-position pushbutton switch in which operability is improved by extending the stroke of a key top for switching between switch sections.
Another object of the present invention is to provide a compact two-position pushbutton switch which allows smooth operation.
In order to overcome the above problems, according to an aspect of the present invention, there is provided a two-position pushbutton switch including: a first click spring to be inverted by a first working force; a first switch section to be operated by the inversion of the first click spring; a driving member disposed opposed to the first click spring so as to press the first click spring; a second switch section laid on the driving member; a second click spring to be inverted by a second working force, different from the first working force, so as to operate the second switch section; and a key top for pressing the second click spring, wherein a cushioning member is placed on at least one of the first and second click springs and the click spring is pressed via the cushioning member.
This can make a first press stroke long. For this reason, in a case in which such a two-position pushbutton switch is adopted in a digital camera, a press stroke for focusing can be made long, and the focusing operation is easy. This improves ease of use of the pushbutton switch.
The cushioning member may be placed on the second click spring.
This can make the first press stroke long. Moreover, since the key top and the second click spring are not in direct contact with each other, even when the key top rattles, no sound is produced by the contact therebetween.
The cushioning member may be placed on the first click spring.
This can make the first press stroke long. The first press stroke can be further extended by using the cushioning member in combination with a cushioning member placed on the second click spring.
Preferably, the two-position pushbutton switch further includes a casing for holding the key top, an operating portion of the key top
Asai Akira
Homma Sachiko
Oba Katsuichi
Sato Shigenori
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Luebke Renee
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