Apparatus for controlling the inflation pressure of a mattress in response to deformation of the mattress using impedance measurement

摘要

A method and apparatus for supporting a patient on a mattress. The apparatus includes a mattress which has at least one controlled release chamber with a top face and a bottom face. A flexible film of a thin metal foil is linked to the top face, while at least one impedance varying device is linked to the bottom face of the chamber. The impedance varying device is an integral part of a measuring electronic bridge. Changes in the impedance as a result of movement of the top face with respect to the bottom face activates a servo control which increases or decreases the inflation pressure within the chamber to make certain that the distance between the top face and the bottom face of the chamber is maintained at a predetermined distance. The method of this invention includes the steps of providing a mattress having at least one closed or controlled release chamber having a top face and a bottom face, providing a measurement device which includes a flexible film of a thin metal foil linked to the top face of the chamber and cooperating with at least one impedance varying element linked to the bottom face of the chamber, the impedance varying element being integral with a measuring electronic bridge, and measuring spacing between the top face and the bottom face to provide control of the supporting action of the mattress as a function of the patient's morphology and position on the mattress.