Abstract: The present invention relates to a system and a method for detecting and monitoring the distance between a patient and a reference point on an inflatable air mattress and for controlling the air supply to that mattress in relation to such distance. The patient distance sensing system includes a rigid support frame such as a bed frame, an inflatable air mattress positioned atop the bed frame with the upper surface of the inflatable air mattress forming a patient support surface, an air supply operable to provide controlled variations in air supply, and a series of patient distance sensing devices. Such devices including a heterodyning proximation detector, a force responsive distance sensing device, and a light responsive sensing device. Each device is operable to act separately or cooperatively in maintaining a therapeutically beneficial patient support surface through variable control of the delivery of inflation pressure to the air mattress.

Abstract: The present invention relates to a system and a method for detecting and monitoring the distance between a patient and a reference point on an inflatable air mattress and for controlling the air supply to that mattress in relation to such distance. The patient distance sensing system includes a rigid support frame such as a bed frame, an inflatable air mattress positioned atop the bed frame with the upper surface of the inflatable air mattress forming a patient support surface, an air supply operable to provide controlled variations in air supply, and a series of patient distance sensing devices. Such devices including a heterodyning proximation detector, a force responsive distance sensing device, and a light responsive sensing device. Each device is operable to act separately or cooperatively in maintaining a therapeutically beneficial patient support surface through variable control of the delivery of inflation pressure to the air mattress.