Electricity: circuit makers and breakers – Solid contact – Push button operated
Reexamination Certificate
2000-07-25
2001-08-14
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Solid contact
Push button operated
C200S406000, C200S279000
Reexamination Certificate
active
06274834
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a structure of a push-button switch for use in electronic devices such as home electric appliances, business machines, and communication devices. Particularly, the invention is concerned with a structure of a push-button switch which is required to have a dust resistance.
2. Description of the Prior Art
A conventional structure of a push-button switch is shown in
FIGS. 6
to
8
, of which
FIG. 6
is a sectional view of the push-button switch,
FIG. 7
is a sectional view of the push-button switch as seen in a direction different from
FIG. 6
, and
FIG. 8
is a perspective view of a fixed contact formed by a wire rod.
In these figures, the push-button switch is made up of a generally cylindrical, bottomed housing
11
formed by molding a synthetic resin, a pair of fixed contacts
12
exposed to an inside bottom of the housing
11
, a fixed terminal
13
integral with the fixed contacts
12
and projecting to the exterior of the housing
11
, a movable contact
14
formed by a dome-like inversion spring incorporated within the housing
11
and capable of moving into contact with and away from the fixed contacts
12
, a stem
15
formed of a synthetic resin, the stem
15
being mounted on the movable contact
14
and capable of moving into the housing
11
, and a cover formed by a metallic plate and fixed to an upper surface of the housing
11
.
The fixed contact
12
and the fixed terminal
13
are integrally formed using the same wire rod. The wire rod is a single round wire rod having been subjected to a thickness deviation working. A total of two such round wire rods are used in a partially embedded state in the housing
11
.
The two round wire rods, which extend in parallel with each other, are formed with two raised portions
12
a
, respectively, which are raised upward by a thickness deviation working. By inserting these round wire rods into a cavity of a mold and molding the housing
11
, the raised portions
12
exposed to the inside bottom of the housing are used as the fixed contacts
12
and the round wire rods are used as the fixed terminals.
By this insert molding, the bottoms of the raised portions
12
a
are embedded in the housing
11
, so that the round wire rods are difficult to turn with respect to the housing
11
and difficult to be disengaged from the housing.
In the push-button switch described above, when an operator depresses the stem
15
, the movable contact
14
, which is opposed to the inside bottom of the housing
11
, undergoes a depressing force and is inverted into contact with both fixed contacts
12
(raised portions
12
a
), so that the fixed contacts
12
are rendered conductive with each other through the movable contact
14
, thus causing the switch to turn ON.
With the switch ON, if the depressing force for the stem
15
is released, the movable contact
14
which has been inverted reverts to the original dome shape by virtue of its own elasticity. Consequently, both fixed contacts
12
cease to conduct and the switch turns OFF. At this time, the stem
15
undergoes a biasing force of the movable contact
14
and is pushed up to its initial position.
In the above conventional push-button switch structure, however, since the raised portion
12
a
of each round wire rod is constituted as the fixed contact
12
, dust which has entered the switch may adhere to the fixed contact
12
(raised portion
12
a
) and cause a poor conduction, thus giving rise to a problem in point of contact reliability.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to solve the above-mentioned problems and provide a structure of a push-button switch capable of preventing the occurrence of a poor conduction caused by the influence of dust or the like which has entered the switch and ensuring a stable contact reliability despite of adopting a contact structure which uses round wire rods.
For solving the above-mentioned problems, in the first aspect of the present invention there is provided a push-button switch comprising a housing having a receptacle portion, a fixed terminal formed by a wire rod, embedded in the housing, and partially projecting to the exterior of the housing, a fixed contact integral with the fixed terminal and using as a contact portion a partially exposed, raised portion of the wire rod exposed to an inside bottom of the receptacle portion, and a dome-like movable contact accommodated in the receptacle portion and capable of moving into contact with and away from the fixed contact, wherein a groove is formed in an upper surface of the raised portion of the fixed contact so as to cross the raised portion transversely and/or longitudinally, and the thus-grooved upper surface of the raised portion comes into contact with the movable contact.
In the second aspect of the present invention, the groove is formed in V shape.
In the third aspect of the present invention, the groove is formed in a plural number.
In the fourth aspect of the present invention, the fixed contact is formed in pairs opposed to each other in the inside bottom of the receptacle portion.
REFERENCES:
patent: 3959611 (1976-05-01), Green et al.
patent: 3973091 (1976-08-01), Kaminski
patent: 4056700 (1977-11-01), Stannek
patent: 4375017 (1983-02-01), Smith
patent: 4931605 (1990-06-01), Zoller
patent: 6049047 (2000-04-01), Miyashima et al.
patent: 06028947 A (1994-04-01), None
Okada Mitsuhiro
Sato Hidetaka
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Friedhofer Michael
LandOfFree
Push-button switch with part to a wire rod exposed to an... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Push-button switch with part to a wire rod exposed to an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Push-button switch with part to a wire rod exposed to an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2454461