Electrical resistors – Resistance value responsive to a condition – Current and/or voltage
Reexamination Certificate
2003-03-10
2003-12-09
Easthom, Karl D. (Department: 2832)
Electrical resistors
Resistance value responsive to a condition
Current and/or voltage
C338S047000, C338S092000, C338S096000, C338S099000
Reexamination Certificate
active
06661332
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to switches, and particularly to a press-type varistor switch with adjustable impedance so that the switch can be operated in various operation modes.
BACKGROUND OF THE INVENTION
Conventionally, a switch is operated at two status, one being fully turning-on and the other being full turn-off. Referring to
FIGS. 8
to
10
, the cross section views of some prior art switches are presented. These prior art switches are operated at two states, i.e., fully open and fully close.
FIG. 9 and 10
shows the operation of one prior art switch. It is illustrated these kinds of switches are operated only at two modes. However recently, the electronic products are made more and more complex, and thus they need some operation modes other than full turning-on or turning off. That is, a switching state between full turning-on and turning-off is necessary, for example to press a switch continuously or to press a switch twice, or to press a switch for a predetermined time period so as to execute a desired operation, etc. However many prior art designs have complex structures and thus the costs are high.
Thereby, there is an eager demand for a novel switch which can improve above flaws in the prior art.
SUMMARY OF THE INVENTION
Accordingly, the primary object of the present invention is to provide a press-type varistor switch. A center of a upper cover is formed with a round hole. A head of a silicide cap is embedded into the round hole. Opposite sides of the seat are formed with a metal guide pin. The head of the silicide cap protrudes from a round hole of the upper cover so that the silicide cap is enclosed between the upper cover and the seat. Each to the adjacent sides of the metal guide pins is extended with a carbon-film resistor; the two carbon-film resistors are not in contact to one another. An interior of the head is installed with a conductive rubber. The conductive rubber is above the two carbon-film resistor. When a force is applied to the silicide cap, the two carbon-film resistors are in contact with the two metal guide pins partially or fully so that the impedance is adjustable.
REFERENCES:
patent: 4847586 (1989-07-01), Tanaga et al.
patent: 5231386 (1993-07-01), Brandenburg et al.
patent: 6275138 (2001-08-01), Maeda
patent: 6344791 (2002-02-01), Armstrong
patent: 6437682 (2002-08-01), Vance
patent: 6531951 (2003-03-01), Serban et al.
patent: 6563415 (2003-05-01), Armstrong
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