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US 5,880,538 AGranted
Capacitive proximity switch circuit
Assigneei f m electronic GmbH
InventorJorg Schulz
Life of this patent
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Abstract
A capacitive proximity switch which may be used as an actuating device for a variety of control applications, such as windshield wipers and door locks. According to the invention, the actuating element a contact or proximity switch to be actuated in a nonmechanical manner, and a sensor provided on an object being made as part of a capacitive proximity switch, specifically as an operating electrode of the capacitive proximity switch.
Claims10
A capacitive proximity switch circuit, comprising:
- a reference electrode;
- an operating electrode;
- a changeover contact having an input electrically connected to said operating electrode, said changeover contact being controlled by a clock generator and having a first and second output, the second output of said changeover contact being connected to a frame potential;
- and
- a storage capacitance electrically connected via a charging resistor connected to a power supply voltage and via a discharging resistor to a first output of said changeover contact, said storage capacitance being further connected to said frame potential;
- wherein the circuit switches only when the capacitance between said operating electrode and said reference electrode changes at a rate which is greater than a stipulated lower boundary value.
3 more elements
Dependencies are inferred from the claim text.