Apparatus and methods usable in connection with dispensing flexible sheet material from a roll
First Claim
1. A proximity sensor circuit, comprising:
- an antenna having a baseline stray capacitance;
an oscillator circuit coupled to the antenna and generating an oscillation signal having a predetermined oscillation amplitude corresponding to the baseline stray capacitance of the antenna, the oscillation amplitude of the oscillation signal increasing in response to an increase in stray capacitance from the baseline stray capacitance of the antenna and decreasing in response to a decrease in stray capacitance from the baseline stray capacitance of the antenna; and
an automatic sensitivity control circuit coupled to the oscillator circuit and detecting a change in the oscillation amplitude of the oscillator signal, the automatic sensitivity control circuit controlling the amplitude of the oscillator signal to counteract a change in stray capacitance from the baseline stray capacitance of the antenna and maintaining the oscillation amplitude of the oscillator signal at the predetermined oscillation amplitude to provide a substantially constant sensitivity to changes in stray capacitance from the baseline stray capacitance of the antenna.
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Accused Products
Abstract
A proximity sensor circuit of a powered dispenser for dispensing individual sheet segments from a continuous roll of sheet material includes an antenna, an oscillator circuit and an automatic sensitivity control circuit. The antenna has a baseline stray capacitance. The oscillator circuit is coupled to the antenna and generates an oscillation signal having a predetermined oscillation amplitude corresponding to the baseline stray capacitance of the antenna. Preferably, the oscillator circuit has a Colpitts oscillator-type topography. The oscillation amplitude of the oscillation signal increases in response to an increase in stray capacitance from the baseline stray capacitance of the antenna and decreases in response to a decrease in stray capacitance from the baseline stray capacitance of the antenna. The automatic sensitivity control circuit is coupled to the oscillator circuit and detects a change in the oscillation amplitude of the oscillator signal.
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Citations
14 Claims
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1. A proximity sensor circuit, comprising:
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an antenna having a baseline stray capacitance;
an oscillator circuit coupled to the antenna and generating an oscillation signal having a predetermined oscillation amplitude corresponding to the baseline stray capacitance of the antenna, the oscillation amplitude of the oscillation signal increasing in response to an increase in stray capacitance from the baseline stray capacitance of the antenna and decreasing in response to a decrease in stray capacitance from the baseline stray capacitance of the antenna; and
an automatic sensitivity control circuit coupled to the oscillator circuit and detecting a change in the oscillation amplitude of the oscillator signal, the automatic sensitivity control circuit controlling the amplitude of the oscillator signal to counteract a change in stray capacitance from the baseline stray capacitance of the antenna and maintaining the oscillation amplitude of the oscillator signal at the predetermined oscillation amplitude to provide a substantially constant sensitivity to changes in stray capacitance from the baseline stray capacitance of the antenna. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for providing substantially constant sensitivity for sensing changes in a baseline stray capacitance to an antenna, the method comprising steps of:
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generating an oscillation signal coupled to the antenna and having a predetermined oscillation amplitude corresponding to the baseline stray capacitance of the antenna, the oscillation amplitude of the oscillation signal increasing in response to an increase in stray capacitance from the baseline stray capacitance of the antenna and decreasing in response to a decrease in stray capacitance from the baseline stray capacitance of the antenna;
detecting a change in the oscillation amplitude of the oscillator signal;
controlling the amplitude of the oscillator signal to counteract the detected change in stray capacitance from the baseline stray capacitance of the antenna; and
maintaining the oscillation amplitude of the oscillator signal at the predetermined oscillation amplitude to provide a substantially constant sensitivity to changes in stray capacitance from the baseline stray capacitance of the antenna. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification