Electricity: circuit makers and breakers – Multiple circuit control – Pivoted contact
Reexamination Certificate
2001-05-25
2002-02-19
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Multiple circuit control
Pivoted contact
Reexamination Certificate
active
06348664
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multidirectional switch which outputs a switching signal in accordance with the tilting direction of a stem, and, more particularly, to a multidirectional switch which outputs a switching signal even when a stem is pushed.
2. Description of the Related Art
A description of a conventional multidirectional switch will be given with reference to the relevant drawings.
FIG. 8
is a sectional view of a conventional multidirectional switch.
FIG. 9
is a plan view of a housing of the conventional multidirectional switch.
FIG. 10
is an exploded perspective view of movable contact springs and the housing of the conventional multidirectional switch.
FIG. 11
illustrates the operation of the conventional multidirectional switch.
As shown in
FIGS. 8
to
10
, a housing
20
is molded out of a synthetic resin material, and comprises side walls
20
a
that surrounds four sides, an inside bottom portion
20
b
surrounded by the side walls
20
a
, four bosses
20
c
provided in a standing manner so as to extend outward from the four corners of the open end of the side walls
20
a
, four positioning portions
20
d
provided near the bosses
20
c
, and four inner protrusions
20
e
protruding from the inside bottom portion
20
b.
At the inside bottom portion
20
b
of the housing
20
are exposed a circular central fixed contact
2
, a common contact
3
which surrounds the periphery of the central fixed contact
2
, and peripheral fixed contacts
4
disposed at four locations, at the front, back, left and right sides along the periphery of the common contact
3
. The central fixed contact
2
, the common contact
3
, and the peripheral fixed contacts
4
protrude outwardly as terminals
5
from opposing side walls
20
a
of the housing
20
. Here, the four protrusions
20
e
at the inside bottom portion
20
b
are provided in a standing manner so as to surround the circular central fixed contact
2
.
A central tactile spring
60
serving as a central movable contact spring is formed by using a highly resilient base material, such as phosphor bronze or SUS, and subjecting the base material to surface treatment using silver (Ag). The central tactile spring
60
is dome shaped and is placed on the common contact
3
such that it is surrounded by the protrusions
20
e.
Peripheral tactile springs
70
serving as peripheral movable contact springs are formed by using highly resilient base materials, such as phosphor bronze or SUS, and subjecting the base materials to surface treatment using silver (Ag). The peripheral tactile springs
70
are formed into rectangular shapes. A bulging portion
70
a
which is fixed on both sides is integrally formed at the center of its corresponding peripheral tactile spring
70
. The peripheral tactile springs
70
are placed on the common contact
3
, inwardly of each of the peripheral fixed contacts
4
, and are positioned by the corresponding protrusions
20
e
and the inside walls of the housing
20
.
In other words, the central tactile Spring
60
, serving as a central movable contact spring, and each of the peripheral tactile springs
70
, serving as a peripheral movable contact spring, are formed with different shapes, and are separately disposed inside the housing
20
.
A first stem
8
is molded out of a synthetic resin material, and comprises a cylindrical portion
8
a
, a skirt
8
b
, and four semicircular protrusions
8
c
, which are integrally formed. The skirt
8
b
spreads obliquely downward from one end portion of the cylindrical portion
8
a
. Each semicircular protrusion
8
c
is formed at the bottom surface of the skirt
8
b
so as to be maintained at equal angular distances of approximately 90 degrees from each other. The protrusions
8
c
oppose the bulging portions
70
a
of their corresponding peripheral tactile springs
70
.
A guide hole
9
is formed in the center portion of the cylindrical portion
8
a
so as to pass vertically therethrough.
Four protrusions
8
d
are integrally formed at the peripheral edge of the lower portion of the skirt
8
b
. These protrusions
8
d
extend outwardly from portions midway between corresponding two adjacent protrusions
20
e
, and engage the corresponding positioning portions
20
d
of the housing
20
.
The first stem
8
is rockably supported with respect to the housing
20
by the peripheral tactile springs
70
, which are placed on the inside bottom portion
20
b
of housing
20
. The housing protrusions
20
e
have slots in a lower portion thereof (as best seen in
FIG. 9
) which hold the peripheral tactile springs
70
in place.
A second stem
10
is molded out of a synthetic resin material. A flange
10
a
is integrally formed at the bottom end of the second stem
10
. The bottom surface of the flange
10
a
opposes the top surface of each of the protrusions
20
e
of the housing
20
so as to be maintained at a predetermined distance therefrom. The second stem
10
protrudes upward from the first stem
8
as a result of being inserted into the guide hole
9
from therebelow, and is stopped by the flange
10
a
so as not be dislodged from the first stem
8
. A presser protrusion
10
b
is integrally formed at the center of the lower surface of the second stem
10
. The bottom end of the presser protrusion
10
b
is in contact with the central tactile spring
60
.
A cover
11
is formed of a metal plate by a pressing operation. A circular central hole
11
a
is formed in the center of the cover member
11
, and mounting holes (not shown) are formed in the four corners thereof. A portion which widens in the downward direction is formed at the peripheral edge of the central hole
11
a
. With the skirt
8
b
of the first stem
8
being passed through the center hole
11
a
, the cover member
11
covers the open end of the top portion of the housing
20
by caulking the bosses
20
c
passed through their corresponding mounting holes (not shown).
In the multidirectional switch having the abovedescribed structure, the central tactile spring
60
and each of the peripheral tactile springs
70
are separately disposed inside the housing
20
. The peripheral tactile springs
70
and the corresponding protrusions
8
c
are made to oppose each other with predetermined separations therebetween in order to provide a play therebetween. Therefore, in certain states of use of the switch, when, as shown in
FIG. 11
, the second stem
10
and the first stem
8
are rocked with respect to the housing
20
so that the entire multidirectional switch is tilted while in a switched state. In this configuration, one of the peripheral tactile springs
70
b
is compressed, while, the distance between the peripheral tactile spring
70
c
disposed opposite to the direction of operation of the first stem
8
and the corresponding protrusion
8
c
increases. Therefore, the peripheral tactile spring
70
may lift from the inside bottom portion
20
b
of the housing
20
, causing the outside end of the peripheral tactile spring
70
to move upward along the corresponding side wall
20
a
of the housing
20
. If the peripheral tactile spring
70
stays on the side wall
20
a
when the multidirectional switch is tilted back to its original position (as will sometimes occur), the switching of the peripheral tactile spring
70
may be hindered.
In the above-described multidirectional switch, in order to always cause each of the peripheral tactile springs and the central tactile spring to be in electrical conduction with the common contact, it is necessary to wire the common contact so as to surround the central tactile spring. This has prevented size reduction of the multidirectional switch in the widthwise direction.
In addition, a large number of tactile springs are used, and the assembly operations are troublesome to carry out, so that the multidirectional switches cannot be provided at low costs.
SUMMARY OF THE INVENTION
To achieve the foregoing and other objects of the invention a multidirectional switch is provided that includes a hou
Alps Electric Co. ,Ltd.
Beyer Weaver & Thomas LLP
Friedhofer Michael
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