Control system with capacitive detector

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:

• 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 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.

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:

• 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.

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:

• 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.