Patent ID: 6778090
Filing Date: 2004-08-17
Classification: A61B

Abstract:
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.