Electricity: circuit makers and breakers – Solid contact – Reciprocating actuator
Reexamination Certificate
2000-02-09
2001-06-05
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Solid contact
Reciprocating actuator
C200S558000, C200S573000, C200S00600C, C200S0060BA
Reexamination Certificate
active
06242706
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention provides a microswitch which can be switched by loading a projection of a push lever projecting outside a case with external force or releasing the external force therefrom and which has general-purpose properties for an operation, a detection and so on of a wide variety of apparatuses.
2. Description of the Prior Art
A conventional microswitch which has been generally and widely used is constructed so that one end of a contact spring piece comprising a tension member and a compression member is fixed in a small box-shaped case (common terminal) and the other end is provided with a movable contact, said movable contact being provided opposite a fixed contact (terminal) (separately therefrom or coming into contact therewith), the above-described contact spring piece is pressed and inverted by pressing and descending an actuator, for example, a press button, the contact spring piece is reversed and inverted (snap action) at a given pressing point and contact of the movable contact with the fixed spring (ON) or separation of the movable contact from the fixed spring (OFF) is performed instantly. However, in case of the above-described conventional microswitch, not only has it been difficult to produce the contact spring piece comprising the tension member and the compression member precisely without scatter in each switch for manufacturing processing technique, material and so on with miniaturization of the switch, but also the precision in mounting technique for mounting the microswitch to a case has been at the end of its limitation and, particularly, it has not been possible to correspond to the recent super-miniaturization, for example, each dimension of longitude, side and height is proximately
10
mm, and there has been a problem that cost rises inevitably because of miniaturization and improvement in precision.
Furthermore, since the contact (ON) pressure of the movable contact with fixed contact which are important points for a switch operation is only spring pressure of a small contact spring piece, there occurs scatter in the contact pressure for every switch operation, thereby making the switch performance unstable. Also, there has been a problem that the switch performance deteriorates because of dirt on a contact part after long-term use, repeated use and so on.
SUMMARY OF THE INVENTION
This invention comprises as main members a push lever and a seesaw contact piece which can be easily miniaturized and sophisticated in high-precision and realizes miniaturization of a switch and cost reduction and, simultaneously, performs simply but precisely switch operation, that is to say, operations of a movable contact and a fixed contact by means of the seesaw contact piece which is coupled to the push lever like a seesaw and this invention performs the contact (ON) of both of the contacts by rocking of the push lever around a supporting shaft so that the bottom end of the push lever pushes immediately downward a right side piece of the seesaw contact piece to keep a state that the movable contact presses strongly and surely to the fixed contact, thereby dissolving occurrence of contact failure of the contacts and, simultaneously, producing a cleaning effect by friction of both of the contacts which come into contact with each other by flexure of the right side piece with pushing force to realize high-sophistication of switch and solve the aforementioned problems.
According to this invention, there is provided a microswitch comprising a push lever as an actuator, a seesaw contact piece to a right side piece of which a movable contact is attached, a fixed contact which switches ON or OFF by coming into contact with said movable contact or separating from said movable contact and a terminal, and a fixed contact piece supporting a corner part of the seesaw contact piece and a terminal and so on, outer peripheries thereof being enclosed with an insulating case, in which the above-described push lever is attached pivotally to the case by a supporting shaft, to a front end of which a projection is formed projecting outside the case by elastic force of a spring provided between its rear end and the case, and a lower end of which is equipped with a steel ball so as to freely roll, the seesaw contact piece comprises a left side piece and a right side piece which are formed substantially in the V-shape centered with respect to a corner part, the right side piece being provided with the movable contact, the corner part of said seesaw contact piece is supported to contact by support of an upper end of the fixed contact piece as a fulcrum so as to freely rock from right to left, and the seesaw contact piece and the fixed contact piece are made conductive and, simultaneously, the movable contact on the right side piece of the seesaw contact piece is provided opposite separately the fixed contact, and the steel ball of the above-described push lever is in contact with the left side piece of the seesaw contact piece, wherein at a free position where external force is not loaded to the projection of the push lever, the push lever rocks around the supporting shaft by the elastic force of the spring to project the projection outside the case and, simultaneously, the steel ball presses the left side piece of said seesaw contact piece to rock upward the right side piece of said seesaw contact piece with the corner part being as a fulcrum to locate the movable contact at a position separately from the fixed contact (switch OFF), said projection falls downward when the external force is loaded thereto, and the push lever rocks around the supporting shaft while compressing the spring, the steel ball rolls from the left side piece to the right side piece through the corner part while pressing the seesaw contact piece, thereby making the right side piece of the seesaw contact piece rock downward around the corner part to contact the movable contact with the fixed contact (switch ON), and when the external force is released from the projection the push lever rocks to be restored to the original state by the restoring elastic force of the spring and, simultaneously, the seesaw contact piece rocks to be restored to the original state by rolling to return the steel ball, thereby separating the movable contact from the fixed contact (switch OFF) to prepare for the original free position.
REFERENCES:
patent: 4408105 (1983-10-01), Tanaka
patent: 4654487 (1987-03-01), Sawada
patent: 4874911 (1989-10-01), Parrish
patent: 4978823 (1990-12-01), Sato et al.
patent: 5660270 (1997-08-01), Martin et al.
Friedhofer Michael
Mic Enterprise Co., Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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