Image Number 2 for United States Patent #5523742.
A motion detection device for use as a monitor for patient movement, inclng a sensor for generating motion signals, an integrator for integrating the motion signals over a period of time, and a threshold level of signals generating an alarm signal upon exceeding a predetermined minimum value of the motion signals to activate an alarm. The sensor includes an edge detector for providing a motion sensed outpost of a series of sharp voltage rises and falls to generate a sequence of voltage pulses of predetermined magnitude and time duration which generate an alarm signal if the pulses are generated faster than a preset rate of voltage decay based upon a preselected minimum movement to be sensed. The preferred intermittent switch comprises a conductive rolling sphere in a cylindrical chamber having a conductive wall with one electrical pole and end plates electrically insulated from the conductive wall and having the other electrical pole such that movement of the element caused by movement of the cylinder will generate intermittent electrical contact between one end plate and the cylinder wall. The device preferably further includes a transmitter producing a transmitted radio signal upon receipt of the alarm signal, the radio signal being receivable by a conventional radio.