Proximity sensing circuit
First Claim
1. The combination comprising:
- a first terminal for the application thereto of sampling signals;
first and second circuits, each circuit having an input connected to said first terminal and an output;
a sensor responsive to external stimuli connected to said first circuit for varying the response of the first circuit to said sampling signals; and
comparator means connected to the outputs of said first and second circuits for comparing the output signals produced at the outputs of said first and second circuits;
said comparator means including a regenerative circuit having at least two input terminals, an output terminal, and two power terminals for the application therebetween of an operating potential;
one of said two input terminals being connected to the output of said first circuit and the other one of said two input terminals being connected to the output of said second circuit; and
means for applying an operating potential to said power terminals of said regenerative circuit at a rate corresponding to that of said sampling signals for sensing the signals present at the outputs of said first and second circuits during a sampling signal and for producing at the comparator output terminal a signal indicative of which of the two signals has the greater magnitude.
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Accused Products
Abstract
A proximity sensor system includes first and second circuits connected at their inputs to a source of sampling pulses and at their outputs to a difference circuit. A proximity sensor is connected to the first circuit for modifying the amplitude of the signals produced at its output in response to the presence of an object in proximity to the sensor. The signals produced at the output of the second circuit are substantially independent of the presence of an object. The difference circuit produces an output signal indicative of which one of the first and second circuits produces the largest amplitude signal and is indicative of the presence or absence of an object. The proximity sensor may be comprised of a sheet or conductive material with a first wire connected between the sheet and the first circuit and a second wire isolated from the sheet but extending along the first wire and being connected to the second circuit.
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Citations
14 Claims
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1. The combination comprising:
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a first terminal for the application thereto of sampling signals; first and second circuits, each circuit having an input connected to said first terminal and an output; a sensor responsive to external stimuli connected to said first circuit for varying the response of the first circuit to said sampling signals; and comparator means connected to the outputs of said first and second circuits for comparing the output signals produced at the outputs of said first and second circuits; said comparator means including a regenerative circuit having at least two input terminals, an output terminal, and two power terminals for the application therebetween of an operating potential;
one of said two input terminals being connected to the output of said first circuit and the other one of said two input terminals being connected to the output of said second circuit; andmeans for applying an operating potential to said power terminals of said regenerative circuit at a rate corresponding to that of said sampling signals for sensing the signals present at the outputs of said first and second circuits during a sampling signal and for producing at the comparator output terminal a signal indicative of which of the two signals has the greater magnitude. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. The combination comprising:
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a first terminal for the application thereto of sampling signals; first and second circuits, each circuit having an input connected to said first terminal and an output; a proximity sensor whose electrical capacitance changes in response to the proximity of an object, said proximity sensor including;
a) an antenna comprising a sheet of conductive material;
b) a first conductor connected at one end to said sheet and at its other end to said first circuit for varying the response of the first circuit to said sampling signals in response to the proximity of an object; and
c) a second conductor electrically isolated from said sheet and extending between said sensor and said second circuit for approximately the full length of said first conductor, said second conductor being connected at one end to said second circuit; andmeans connected to the outputs of said first and second circuits including a comparator having first and second inputs and an output, said first and second inputs of said comparator being coupled to the first and second outputs, respectively, of said first and second circuits, and said comparator producing at its output a signal indicative of which of the two signals applied to its inputs has the greater magnitude. - View Dependent Claims (11)
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12. A proximity sensor comprising:
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a sheet of conductive material functioning as a sensing antenna for sensing the presence of an object; a first wire for coupling said sheet to a circuit, said first wire being connected at one end to said sheet and means for connecting the other end of said wire to an input point of said circuit; and a second wire for sensing the approximately same ambient noise sensed by said first wire;
said second wire being terminated at one end adjacent to said sheet but being electrically isolated from said sheet, said second wire extending alongside said first wire for approximately the full length of said first wire, and means for connecting the other end of said second wire to a second point of said circuit, said second wire for applying to said second point the same ambient noise signals picked up by said first wire. - View Dependent Claims (13, 14)
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Specification