Control system with capacitive detector
First Claim
1. A capacitive sensor system for controlling operation of a device, the system comprising:
- sense electrodes for enabling establishment of an electric field for intercepting motion of a proximate object; and
an electronic circuit for providing a control output signal in response to a rate of change in capacitance of the sense electrodes due to motion of the proximate object within the field without intermediate electronic differentiation of signals related to a change in capacitance.
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Accused Products
Abstract
A capacitive sensor system for controlling operation of a device in response to a rate of change in capacitance due to motion of a proximate object includes at least two sense electrodes disposed on a surface and a phase locked loop, including a voltage controlled oscillator and a phase/frequency comparator, connected between the sense electrodes and an RC network for providing an operating frequency to the sense electrodes. A circuit loop, including a reference oscillator, provides a fixed frequency reference for the phase locked loop to follow and a phase delay circuit connected between said phase/frequency comparator and said voltage controlled oscillator causes the voltage controlled oscillation to run ahead of the reference oscillator. A trigger circuit provides a control output in response to a change in phase shift between said fixed frequency and said operating frequency.
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Citations
24 Claims
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1. A capacitive sensor system for controlling operation of a device, the system comprising:
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sense electrodes for enabling establishment of an electric field for intercepting motion of a proximate object; and
an electronic circuit for providing a control output signal in response to a rate of change in capacitance of the sense electrodes due to motion of the proximate object within the field without intermediate electronic differentiation of signals related to a change in capacitance. - View Dependent Claims (2, 3, 4)
a phase locked loop, including a voltage controlled oscillator (VCO), connected to the sense electrodes, for providing an operating frequency to the sense electrodes;
a fixed frequency reference oscillator for providing a fixed frequency reference;
a phase/frequency comparator for comparing a VCO frequency with the fixed reference frequency;
a phase delay circuit for changing a phase difference between the VCO frequency and the fixed reference oscillator frequency when the loop is phase locked;
a loop filter for integrating a phase error signal from the phase/frequency comparator in order to define a dynamic response of the loop; and
a phase sensitive trigger circuit for providing a control output signal in response to change in a phase difference between the fixed reference frequency and the operating frequency.
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3. The system according to claim 2 wherein the phase delay circuit is operative for causing the VCO frequency to run ahead of the fixed reference frequency in order that a positive rate of change in capacitance controls operation of the device.
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4. The system according to claim 2 wherein the phase delay circuit is operative for causing the VCO frequency to lag behind the fixed reference frequency in order that a negative rate of change in capacitance controls operation of the device.
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5. A capacitive sensor system for controlling operation of a device in response to a rate of change in capacitance due to motion of a proximate object, the system comprising:
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at least two sense electrodes disposed in a spaced apart relationship for enabling establishment of an electric field between the sense electrodes, said electric field extending outwardly and between the sense electrodes;
a phase locked loop, including a voltage controlled oscillator (VCO), connected to the sense electrodes, for providing an operating frequency to the sense electrodes;
a fixed frequency reference oscillator for providing a fixed frequency reference;
a phase/frequency comparator for comparing a VCO frequency with the fixed reference frequency;
a phase delay circuit for causing a phase difference between the VCO frequency and the fixed reference oscillator frequency when the loop is phase locked;
a loop filter for integrating a phase error signal from the phase/frequency comparator in order to define a dynamic response of the loop; and
a phase sensitive trigger circuit for providing a control output signal in response to change in a phase difference between the fixed reference frequency and the operating frequency. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A capacitive sensor system for controlling operation of a device in response to a rate of change in capacitance due to motion of a proximate object, the system comprising:
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at least two sense electrodes disposed in a spaced apart relationship for enabling establishment of an electric field between the sense electrodes, said electric field extending outwardly and between the sense electrodes;
a phase locked loop, including a voltage controlled oscillator (VCO), connected to the sense electrodes, for providing an operating frequency to the sense electrodes;
a fixed frequency reference oscillator for providing a fixed frequency reference;
a loop filter for integrating a phase error signal from the phase/frequency comparator in order to define a dynamic response of the loop; and
a phase sensitive trigger circuit for providing a control output signal in response to a change in a phase difference between the fixed reference frequency and the operation frequency, the trigger circuit including a voltage comparator, having one side connected to the VCO, and a long time constant loop filter connected between the phase/frequency comparator and the voltage comparator. - View Dependent Claims (22, 23, 24)
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16. A capacitive sensor system for controlling operation of a device in response to a rate of change in capacitance due to motion of a proximate object, the system comprising:
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at least two sense electrodes disposed in a spaced apart relationship for enabling the establishment of an electric field between the sense electrodes;
a phase locked loop, including a voltage controlled oscillator (VCO), connected to the sense electrodes, for providing an operating frequency to the sense electrodes;
a fixed frequency reference oscillator for providing a fixed frequency reference;
a phase frequency comparator for comparing a VCO frequency with the fixed reference frequency;
phase delay circuit connected between said phase/frequency comparator and said voltage controlled oscillator for causing said voltage controlled oscillator to run ahead of the reference oscillator; and
a trigger circuit for providing a control output in response to a change in phase shift between said fixed frequency and said operating frequency. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification