Touch-sensitive potentiometer for operator control panel
First Claim
1. Apparatus for providing a control voltage corresponding to a point along a linear strip touched by an operator, comprising:
- a longitudinally extending polymeric resistor strip formed on a substrate and exposed for touching by the operator; and
touch responsive means connected to said resistor responsive to the operator'"'"'s touch for providing a touch position signal voltage corresponding to the point on the resistor touched by the operator, said touch responsive means comprising an AC-excited bridge circuit for providing a touch received signal when said resistor is touched and a synchronous demodulator responsive to said bridge becoming unbalanced for removing AC components from said touch received signal to provide said touch position signal.
4 Assignments
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Accused Products
Abstract
A touch-sensitive potentiometer for an operator control panel. A linear strip having a polymeric resistor film is provided as an operator actuatable control. The stray capacitance of an operator'"'"'s body, when the operator touches the strip along its length, unbalances a transformer bridge and provides a voltage proportional to the position of the operator'"'"'s finger along the length of the polymeric resistor. The potentiometer is suitable for use in any operator control environment where it is desired to (1) rapidly and quickly approach a control range without multiple turns required by optical position encoder-type control devices, or (2) rapidly and quickly be reset to a null or zero state upon the completion of a control in preparation for a subsequent control.
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Citations
8 Claims
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1. Apparatus for providing a control voltage corresponding to a point along a linear strip touched by an operator, comprising:
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a longitudinally extending polymeric resistor strip formed on a substrate and exposed for touching by the operator; and touch responsive means connected to said resistor responsive to the operator'"'"'s touch for providing a touch position signal voltage corresponding to the point on the resistor touched by the operator, said touch responsive means comprising an AC-excited bridge circuit for providing a touch received signal when said resistor is touched and a synchronous demodulator responsive to said bridge becoming unbalanced for removing AC components from said touch received signal to provide said touch position signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A control potentiometer for an operator control panel, comprising:
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an oscillator; a balanced transformer bridge comprising a primary winding excited by said oscillator and a center tapped secondary winding for providing a touch received signal; a longitudinally extending resistor strip connected between the terminals of said secondary winding, said resistor strip being exposed for touching by an operator; a synchronous demodulator connected to the center tap of said transformer secondary; and means for amplifying signals provided by said synchronous demodulator, whereby when the resistor strip is touched, the bridge is unbalanced and said amplifier provides a voltage corresponding to the point on the resistor strip touched by the operator. - View Dependent Claims (8)
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Specification