Patient signalling system
First Claim
1. A patient signalling system comprising:
- (a) a touch sensitive capacitive transducer comprising an exposed conductive plate carried by a body of dielectric material, said transducer adapted to be conveniently and comfortably placed with a patient afflicted with an illness or paralysis rendering him incapable of providing any significant manual force or dexterity;
(b) a flexible electrical cable of significant length connected at one end to said plate; and
(c) a circuit having an input and an output and located physically remote from the patient, said circuit input connected to the other end of said cable, said circuit converting a change in capacitance of said transducer when touched by the patient into an electrical signal for causing operation of an appliance connected to said circuit output, said circuit comprising a source of supply voltage, a high gain amplification stage operatively connected to said supply and having an input connected to said transducer for converting a minute signal produced by said transducer when touched by said patient into an output signal which switches at the voltage level of said supply, a wave shaping stage having an input connected to the output of said high gain amplification stage for converting impulse signals into square wave output signals, and a d.c. switch connected in controlled relation to the output of said wave shaping stage for causing completion of an electrical power circuit for the appliance.
1 Assignment
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Accused Products
Abstract
A patient signalling system comprising a touch sensitive capacitive transducer adapted to be conveniently and comfortably placed with a patient afflicted with an illness or paralysis rendering him incapable of producing any significant manual force or dexterity, a flexible electrical cable of appreciable length connected at one end to the transducer, and a circuit located remote from the patient and connected to the other end of the cable for converting a change in capacitance of the transducer when touched by the patient into an electrical signal for causing operation of an appliance such as a signalling or communication device connected to the circuit. The circuit includes an input stage in the form of a high input impedance semiconductor device, a direct coupled a.c. amplifier, a resistive coupled a.c. amplifier, and a d.c. semiconductor switch. The system can include provision for patient electrical isolation and low battery voltage indication.
20 Citations
17 Claims
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1. A patient signalling system comprising:
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(a) a touch sensitive capacitive transducer comprising an exposed conductive plate carried by a body of dielectric material, said transducer adapted to be conveniently and comfortably placed with a patient afflicted with an illness or paralysis rendering him incapable of providing any significant manual force or dexterity; (b) a flexible electrical cable of significant length connected at one end to said plate; and (c) a circuit having an input and an output and located physically remote from the patient, said circuit input connected to the other end of said cable, said circuit converting a change in capacitance of said transducer when touched by the patient into an electrical signal for causing operation of an appliance connected to said circuit output, said circuit comprising a source of supply voltage, a high gain amplification stage operatively connected to said supply and having an input connected to said transducer for converting a minute signal produced by said transducer when touched by said patient into an output signal which switches at the voltage level of said supply, a wave shaping stage having an input connected to the output of said high gain amplification stage for converting impulse signals into square wave output signals, and a d.c. switch connected in controlled relation to the output of said wave shaping stage for causing completion of an electrical power circuit for the appliance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17)
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12. A patient signalling system comprising:
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(a) a touch sensitive capacitive transducer comprising an exposed conductive plate carried by a body of dielectric material, said transducer adapted to be conveniently and comfortably placed with a patient afflicted with an illness or paralysis rendering him incapable of providing any significant manual force or dexterity; (b) a flexible electrical cable of significant length connected at one end to said plate; (c) a circuit having an input and an output and located physically remote from the patient, said circuit input connected to the other end of said cable, said circuit converting a change in capacitance of said transducer when touched by the patient into an electrical signal for causing operation of an appliance connected to said circuit output, said circuit having an electrical ground in floating relation to earth ground; and (d) means for isolating said transducer means electrically from said floating ground, said isolating means comprising modulator circuit means operatively connected to said circuit means and isolation transformer means operatively connected to said modulator circuit means and to said circuit electrical ground and to earth ground.
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Specification