Claims
- 1. A modular apparatus for monitoring the presence of a person within a predefined space on a bed, said bed having a mattress, said apparatus comprising:a mattress cover, generally constructed of fabric material, said mattress cover having at least one flexible capacitance sensor, said at least one flexible capacitance sensor comprising a plurality of coplanar conductive elements positioned in spaced relation to one another, said mattress cover being adapted for over fitting the mattress such that a person may overlie said plurality of coplanar conductive elements when resting on the bed, said plurality of co-planar conductive elements comprising: first and second parallel, coplanar layers of conductive ink, deposited in bands across an underside surface of said mattress covert; and first and second parallel, coplanar layers of flexible, resilient conductive material, deposited in bands substantially over said layers of conductive ink, said layers of flexible, resilient conductive material leaving a limited portion of said layers of conductive ink exposed for electrical connection thereto; a driver/sensor circuit electrically connected to said flexible capacitance sensor for supplying a voltage between said plurality of conductive elements, detecting a change in capacitance associated with said flexible capacitance sensor in response to a change in position of a person with respect to said flexible capacitance sensor, and generating an output signal having frequency variations representative of said change in capacitance, said driver/sensor circuit being positioned adjacent said plurality of conductive elements to minimize interference from external electromagnetic fields; and a control/monitor module electrically connected to said driver/sensor circuit for receiving said output signal from said driver/sensor circuit, analyzing said output signal to make a determination of whether said output signal is representative of a change in presence of a person within a predefined space, and generating an alarm signal if said determination is affirmative.
- 2. The apparatus of claim 1 wherein said coplanar layers of conductive ink comprise bands of silver oxide conductive ink deposited on said mattress cover.
- 3. The apparatus of claim 1 wherein said coplanar layers of flexible, resilient, conductive material comprise bands of carbon graphite impregnated rubber material deposited over said layers of conductive ink.
- 4. The apparatus of claim 3 wherein said carbon graphite impregnated material is air permeable and water impermeable.
- 5. The apparatus of claim 3 herein said fabric material of said mattress cover is air permeable and water impermeable.
- 6. The apparatus of claim 1 wherein said coplanar layers of conductive ink comprise a pair of bands spanning the width of said mattress cover.
- 7. The apparatus of claim 1 wherein said coplanar layers of conductive ink are deposited across said underside surface of said mattress cover by weaving thread impregnated with said conductive ink into said fabric material of said mattress cover.
RELATED APPLICATIONS
The present application is a continuation-in-part of U.S. patent application Ser. No. 09/401,482, filed Sep. 22, 1999, now U.S. Pat. No. 6,297,738 issued Oct. 2, 2001, which is a continuation-in-part of U.S. patent application Ser. No. 08/871,363, filed Jun. 9, 1997, now U.S. Pat. No. 6,025,782, which is a continuation-in-part of U.S. patent application Ser. No. 08/708,397, filed Sep. 4, 1996, now abandoned, disclosures of which are incorporated herein by reference.
US Referenced Citations (43)
Continuation in Parts (3)
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Number |
Date |
Country |
Parent |
09/401482 |
Sep 1999 |
US |
Child |
09/969497 |
|
US |
Parent |
08/871363 |
Jun 1997 |
US |
Child |
09/401482 |
|
US |
Parent |
08/708397 |
Sep 1996 |
US |
Child |
08/871363 |
|
US |