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US 7,091,728 B2Granted
Voltage isolated detection apparatus and method
AssigneeGencsus
InventorsGuy Drouin, Martin Beaumont, René Goulet
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Abstract
A high-isolation call cord switch includes connectivity for a standard hospital-style push-button call cord while using low voltage alternating current to isolate detection circuitry from static electricity. An alternating current signal is used to permit transformer coupling, with its intrinsic isolation capability, between the call cord switch and the detection circuit.
Claims15
A detection circuit, comprising:
- a transformer primary circuit comprising:
- an alternating-current signal (AC) source;
- an impedance in series with said AC source;
- a transformer primary winding in series with said AC source and said impedance and establishing an electrical circuit by completing a signal path back to said AC source, wherein said transformer primary winding further comprises a primary winding on one of a ferrite core, an iron core, and a non-ferromagnetic core;
- and
- a detector positioned across one of said impedance and said primary winding;
- and
- a transformer secondary circuit comprising:
- a transformer secondary winding magnetically coupled to and electrically isolated from said transformer primary winding;
- a plurality of load devices switchably connected across said secondary winding
- a first load comprising a first load impedance and a call cord detection switch, wherein said first load impedance and said call cord detection switch are wired in series across said transformer secondary winding;
- and
- a second load comprising a call cord activations switch wired across said transformer secondary winding.
10 more elements
A method for monitoring a call cord, comprising the steps of:
- generating a generally sinusoidal signal across a series string comprising an impedance and a primary winding of a transformer;
- establishing capability for detecting a voltage across one of the impedance and the primary winding of the transformer wherein the primary winding comprises at least one selected from the group consisting of ferrite core, iron core and a non-ferromagnetic core;
- electrically isolating a magnetically coupled secondary winding of the transformer from the primary winding of the transformer;
- providing a first load comprising a first load impedance and a call cord detection switch, wherein said first load impedance and said call cord detection switch are wired in series across said transformer secondary winding;
- and
- providing a second load comprising a call cord activation switch wired across said transformer secondary winding.
3 more elements
Dependencies are inferred from the claim text.