Detection means for multiple capacitive sensing devices
First Claim
1. 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.
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Accused Products
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.
212 Citations
13 Claims
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1. A circuit for measuring the response of a capacitance responsive sensing element, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A circuit for measuring the response of a capacitance responsive sensing element, comprising:
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an electrical source means for providing a pulse signal to said capacitance responsive sensing element; 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 an operational amplifier having a diode feedback path connected to a common input with said capacitance responsive element.
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8. A circuit for measuring the response of a capacitance responsive sensing element, comprising:
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an electrical source means for providing a pulse signal to said capacitance responsive sensing element; 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 an operational amplifier, a diode connected between said capacitance responsive sensing element and one input of said operational amplifier, and a parallel resistance-capacitance feedback path connected to said one input of said operational amplifier.
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9. A method for measuring the response of a capacitance responsive sensing element comprising the steps of:
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providing a pulse signal to said capacitance responsive sensing element; and 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 measuring including applying said pulse signal as received from said capacitance responsive sensing element across the capacitor of a capacitor-resistor time constant circuit and measuring the recovery time of the voltage across said capacitor. - View Dependent Claims (10, 11)
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12. A method for measuring the response of a capacitance responsive sensing element comprising the steps of:
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providing a pulse signal to said capacitance responsive sensing element; and 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 measuring including coupling said pulse signal as transmitted by said capacitance responsive sensing element to one input of an operational amplifier having a diode feedback path connected to said one input.
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13. A method for measuring the response of a capacitance responsive sensing element comprising the steps of:
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providing a pulse signal to said capacitance responsive sensing element; and 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 measuring including coupling said pulse signal as transmitted by said capacitance responsive sensing element through a diode to one input of a second operational amplifier, said second operational amplifier having a second feedback path connected to said one input thereof, said second feedback path including a parallel resistance-capacitance combination.
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Specification