Electricity: circuit makers and breakers – Liquid contact – Contact dips into the conductive liquid
Reexamination Certificate
2002-08-19
2004-06-22
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Liquid contact
Contact dips into the conductive liquid
C200S559000
Reexamination Certificate
active
06753489
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a switch for use in, for example, a door switch in a refrigerator, and in particular, to a switch such as a push-button switch and a rotary-lever switch which can reduce the number of parts and also achieve stable contact performances.
BACKGROUND OF THE INVENTION
In general, a switch used for a domestic electric appliance, for example, a door switch installed in a domestic refrigerator, has switching functions which turns on and off a lamp in the refrigerator, and also turns on and off a cooling motor, when the door of the refrigerator is opened and closed.
The amount of protrusion of an operation unit (actuator) for the switch to be press-down operated tends to vary due to a dimensional error between the external shape of the door switch and the shape of a recessed portion of the attaching position in the refrigerator. This results in the operation unit tending to have an excessive or insufficient operation in its stroke, making it difficult to maintain switching functions of the door switch.
In order to obtain stable on-off operations without having adverse effects caused by deviations in attaching precision in the door switch, a longer operation stroke is required in the operation direction. However, at present, the application of a longer operation stroke makes the switch itself become bulky, and might cause damages to switching parts due to an over-stroke.
Depending on differences in the open-close system of the door, such as a one-side opening system and a two-side opening system, there are two types of door switches in the operation direction of the door switch. Specifically, there is a push-button type in which the switching operation is carried out by advancing or retreating in the straight line direction, and a rotary-lever type in which the switching operation is carried out while rotating. Different contact structures need to be prepared depending on the respective types.
When, upon a switching operation, the contact switching between contacts is slow, an arc tends to be caused, resulting in a defective contact. In order to prevent this defective contact, a snap action opening and closing mechanism, which quickly carries out switching between contacts, or an opening and closing mechanism having the same function, needs to be prepared.
In order to solve such a problem, a switch has been proposed in which, in cooperation with a depressing operation of a push button, a movable contact which moves in a tilted manner between a tilt position having a tilt angle of approximately 45° with one end supported by a coil spring and a vertical position so as to switch contacts (for example, see Japanese Laid-Open Patent Application No. 11-111105).
However, such a switch needs a fixed contact and a movable contact inside thereof and an exclusively-used coil spring that allows the movable contact to return to its original position. This results in a complicated contact structure, and upon assembling the switch, handling and assembling of the coil spring having an elastic force are difficult. A number of parts and manufacturing processes are also required, resulting in a limitation to cost reduction.
Although, upon switching contacts, this structure has a sliding contact function which switches contacts with the contact portion of the movable contact sliding on the contact portion of the fixed contact while removing an oxide film, it is susceptible to great abrasion and the resulting in short service life.
In addition to these problems, when one door switch is used for turning on-off the lamp illuminating the inside of a refrigerator as well as for turning on-off the cooling motor, a single-pole double-throw switch, which has a normally-closed and normally-open contact construction that turns the switch on and off in response to opening and closing of the door, is required. However, in the case of a door switch which only turns on-off the lamp or only turns on-off the cooling motor, it is easily manufactured by using only the single-pole single-throw switch that has a normally-closed or normally-open contact construction.
However, in the case of this single-pole single-throw switch, since the switch structure is different depending on the normally-closed and normally-open contact constructions, the same housing is not used commonly, and housings corresponding to different contact structures of two types need to be prepared. For this reason, at present, a single-pole single-throw door switch, which can be switched between the normally-closed state and normally-open state by using a single-switch construction, is used as a single-pole single-throw door switch, and either of the contact constructions is selectively used depending on the use.
However, when only one of the normally-closed and normally open contact constructions is selectively used, the other contact construction on the unused side is never used, making the door switch uneconomical with the unused contact parts still assembled therein, as well as causing high costs.
For this reason, it has been proposed that the contact parts on the unused side have been preliminarily omitted. However, in this case, a space is formed in the housing after the contact parts on the unused side have been removed, with the result that the movable contact member facing the space becomes difficult to take a normal amount of shift due to an excessive tilt, etc. Consequently, the movable contact member has a positional deviation or the like, making the contact structure unbalanced, thereby resulting in susceptibility to failure and degradation in the contact performance. Therefore, this case needs the addition of a revising member such as a dummy contact to prevent the movable contact member from having the excessive tilt, and since the addition of one part causes a great increase in the manufacturing costs in mass-produced switches, there has been a strong demand for the development of switches from which the dummy contact has been eliminated.
SUMMARY OF THE INVENTION
In one embodiment of the invention, the movable contact member has two functions, including a spring function configured to elastically shift in addition to a contact function, which is provided as a single commonly-used part. The invention provides a switch having high reliability, such as a push-button switch and a rotary-lever switch, which can cut costs by reducing the number of parts, achieve a small-size device and a high assembling property, and ensure a superior contacting property by using a snap action to provide a longer service life.
In another embodiment of the present invention, a switch, which has a concave-shaped housing with one side being opened, a cover for sealing the opened face and a fixed conductive contact member and a movable contact member that are placed face to face with each other in the housing such that an operative force of operation members that are held in the housing and operated is transmitted to the movable contact member so that the movable contact member is moved and shifted to connect and separate the contacts so as to carry out a switching operation, is provided with a common fixed contact member and a fixed contact member that is different from the common fixed contact member that are placed in parallel with each other in the housing. The movable contact member, which has a tilt-movement fulcrum portion that is placed orthogonal to the parallel arranging direction of the respective fixed contact members, in a manner so as to freely tilt in the orthogonal direction, while being pressed toward the common fixed contact member side, at an intermediate position on one side member of a conductive plate spring member that is bent into a U shape, and a contact portion formed at one end of the one side member in the length direction with the tilt-movement fulcrum portion in the movable shifting direction of this one side member serving as a base point, is placed. In the arrangement a contact switching mechanism is installed which carries out a switching operation by reversing the mov
Kiyono Yasuhiro
Naruo Toshihiro
Friedhofer Michael
Klaus Lisa
Morrison & Foerster / LLP
Omron Corporation
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