Electronic sensing and control circuit
First Claim
1. An electronic circuit for sensing the distance to an object, comprising:
- a single sensing plate spaced from said object;
means for charging said sensing plate to a value dependent upon a capacitance existing between said sensing plate and said object, said capacitance varying with the position of said object relative to said sensing plate;
means for sampling the charging current of said sensing plate;
means for outputting said sampled current, said output current being proportional to said capacitance and varying with the distance between said sensing plate and said object; and
means for providing an opposing current flow equal to any current flow attributable to any residual capacitance of the electronic circuit so that it is only necessary to detect the change of capacitance involved in distance measuring.
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Accused Products
Abstract
An electronic sensing and control circuit is provided which includes a sensing plate and means for charging the sensing plate to a value dependent upon the capacitance existing between the sensing plate and a remote object. The capacitance between the sensing plate and the object varies with the distance of the object relative to the sensing plate. The sensing plate is periodically discharged and charged producing a useful current proportional to the capacitance and varying with the distance between the sensing plate and the object. Two sensing plates are used to provide first and second signals. The first and second signals are subtracted to derive a lateral displacement signal and added to derive a distance signal. The lateral displacement signal and the distance signal can be used to control the forward, reverse and turning motion of a motorized wheelchair.
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Citations
41 Claims
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1. An electronic circuit for sensing the distance to an object, comprising:
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a single sensing plate spaced from said object; means for charging said sensing plate to a value dependent upon a capacitance existing between said sensing plate and said object, said capacitance varying with the position of said object relative to said sensing plate; means for sampling the charging current of said sensing plate; means for outputting said sampled current, said output current being proportional to said capacitance and varying with the distance between said sensing plate and said object; and means for providing an opposing current flow equal to any current flow attributable to any residual capacitance of the electronic circuit so that it is only necessary to detect the change of capacitance involved in distance measuring. - View Dependent Claims (2, 6, 7)
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3. An electronic circuit for sensing the distance to an object comprising:
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a sensing plate; a first switch operable to effect discharge of said sensing plate; a second switch operable to effect a path for outputting sampled charging of said sensing plate, said output current being proportional to a capacitance existing between said sensing plate and said object and varying with the distance between said sensing plate and said object; a third switch operable to control charging of sais sensing plate through a current sampling means and provide a path for outputting the sampled current; and a fourth switch operable to effect an opposing current flow equal to a current flow generated by a residual capacitance of said circuit, so that only the change of capacitance involved in distance measuring is detected, and the opposing current flow is opposite to that current flow which came during the switch on time effectively neutralizing said residual current. - View Dependent Claims (4, 5)
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8. An electronic circuit for sensing the distance to a dielectric or electrically conducting object, comprising:
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a sensing plate; a first switch operable to effect discharge of said sensing plate and produce a current sample; a second switch operable to effect a path for outputting said sampled current; a third switch operable to control charging of said sensing plate and provide a path for outputting the sampled current; a fourth switch operable to effect an opposing current flow equal to a current flow generated by a residual capacitance of said circuit, so that only the change of capacitance involved in distance sensing is detected, said opposing current flow being opposite to current flowing during the switch-on time, effectively neutralizing said residual current; and a square wave oscillator simultaneously driving said switches thereby controllably charging said sensing plate in proportion to the capacitance existing between said sensing plate and said object and sampling said sensing plate charging current to produce a sampled output current directly proportional to said capacitance and varying with the distance between said sensing plate and said object. - View Dependent Claims (9, 10, 11)
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12. An electronic circuit for sensing the distance to a dielectric or electrically conducting object, said electronic circuit having a residual capacitance, comprising:
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a sensing plate forming a capacitor with said object, the capacitance existing between said sensing plate and said object varying with the position of said object relative to said sensing plate; a first resistor having a first end connected to said sensing plate; a second resistor having a first end connected to said sensing plate; a third resistor having a first end connected to a second end of said second resistor; a fourth resistor having a first end connected to a voltage source and a second end coupled to said first end of said third resistor and to said second end of said second resistor; a fifth resistor having a first end coupled to said voltage source; a capacitor having a first end connected to said second end of said fourth resistor and having a second end connected to said first end of said third resistor and said second end of said second resistor; a first switch connected to a second end of said first resistor and operable to effect discharge of said sensing plate through said first resistor; a second switch connected to a second end of said third resistor and operable to effect a path for outputing said sampled current through said capacitor and third resistor; a third switch connected to a second end of said fourth resistor and said first end of said capacitor and operable to control charging of said sensing plate from said voltage source through said second and fourth resistors and said capacitor, said capacitor acquiring a sample of charging current, said third switch providing a path for outputting said sampled current; and a fourth switch connected to a second end of said fifth resistor and operable to effect an opposing current flow through said fifth resistor equal to a current flow generated by said residual capacitance of said circuit, so that only the change of capacitance involved in distance sensing is detected, said opposing current flow being opposite to the current flow which came during the switch on time effectively neutralizing said residual current. - View Dependent Claims (13, 14, 15)
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16. An electronic circuit for sensing the position of a dielectric or electrically conducting object, comprising:
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a first sensing plate forming a capacitor with said object, the capacitance existing between said first sensing plate and said object varying with the position of said object relative to said first sensing plate; a second sensing plate forming a capacitor with said object, the capacitance existing between said second sensing plate and said object varying with the position of said object relative to said second sensing plate; means for charging each of said first and second sensing plates in proportion to the capacitance existing between each of said sensing plates and said object; means for sampling the charging current of said first and second sensing plates producing first and second signals proportional to said capacitance between each of said first and second sensing plates and said object, said capacitance varying with the position of said object relative to said sensing plates; means for subtracting said first and second signals and deriving a lateral displacement signal; and means for summing said first and second signals and deriving a distance signal therefrom. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. An electronic circuit for sensing the distance to an object, comprising:
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a first sensing plate; means for charging said first sensing plate to a value dependent upon a capacitance existing between said first sensing plate and said object, said capacitance varying with the position of said object relative to said first sensing plate; means for sampling the charging current of said sensing plate; means for outputting said sampled current, said output current being proportional to said capacitance and varying with the distance between said first sensing plate and said object; means for converting said first sampled output current to a first voltage signal varying with the distance between said first sensing plate and said object; a second sensing plate; means for charging said second sensing plate to a value dependent upon a capacitance existing between said second sensing plate and said object, said capacitance varying with the position of said object relative to said second sensing plate; means for sampling the charging current of said sensing plate; means for outputting said sampled current, said output current being proportional to said capacitance and varying with the distance between said second sensing plate and said object; means for converting said second sampled output current to a second voltage signal varying with the distance between said second sensing plate and said object; and means for receiving said first and second voltage signals and producing an output signal having a component representative of the distance of said object from said plates collectively and a component proportional to the lateral displacement of said object between said plates.
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29. An electronic circuit for sensing the position of a user'"'"'s head for controlling operation of a motorized wheel chair, comprising:
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a first sensing plate forming a capacitor with the head, the capacitance existing between said first sensing plate and the head varying with the position of the head relative to said first sensing plate; a second sensing plate forming a capacitor with the head, the capacitance existing between said second sensing plate and the head varying with the position of the head relative to said second sensing plate; means for charging each of said first and second sensing plates in proportion to the capacitance existing between each of said sensing plates and the head; means for sampling the charging current of said first and second sensing plates producing first and second signals proportional to said capacitance between each of said first and second sensing plates and the head, said capacitance varying with the position of the head relative to said sensing plates; means for subtracting said first and second signals and deriving a lateral displacement signal for controlling turning motion of said wheel chair; and means for summing said first and second signals and deriving a distance signal therefrom for controlling forward and reverse motion of said wheel chair. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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Specification