US 4,266,144 A · Detection means for multiple capacitive sensing devices

Abstract

A detection circuit for detecting discrete states of multiple capacitive sensing devices in a continuum provides an output which is linearly variable with respect to changes in the states of the sensing devices. The circuit uses either a time interval measurement or voltage measurement which has a magnitude which linearly corresponds to changes in the states of the sensing devices. By continuously monitoring these outputs, a continuous indication of discrete changes in the states of the sensing devices is detectable. In accordance with the present invention, a single drive electrode and a single sense electrode in combination with a plurality of sensing devices capacitively transmit electrical pulses in accordance with the various states of the sensing devices whereby the detection circuit detects discrete changes in a state of the sensing devices in a continuum.

Claims13

Dependent claims

A circuit for measuring the response of a capacitance responsive sensing element, comprising:

an electrical source means for providing a pulse signal to said capacitance responsive sensing element, said electrical source means including means for generating a square wave pulse signal;
and
circuit means for measuring the amount of said pulse signal transmitted through said capacitance responsive sensing element to provide an indication of the amount of capacitance to which said element is responding, said circuit means for measuring including a time constant circuit and means for measuring the recovery time of said time constant circuit in response to said square wave signal as an indication of the amount of said pulse signal transmitted through said capacitance responsive sensing element.

Dependencies are inferred from the claim text.

Detection means for multiple capacitive sensing devices

Life of this patent

Detection means for multiple capacitive sensing devices

Life of this patent

Abstract

Claims13