Amerace Corporation

Electro Corporation

James M Boozer

Robert W Mayer

Paul F Lindlau

Alan J Kumasaka

Paul R Strelecki

The invention provides an apparatus and method to confirm or deny the presence of an object within the scan area of an ultrasonic sensing system by requiring that any object be identified on at least two consecutive scans of the sensing system and using scan energy patterns which occur at irregular repetition times to selectively reject spurious direct or reflected signals present in the area. A generator of predetermined pattern burst of ultrasonic energy is arranged to produce one such burst of ultrasonic energy and a timing signal is coupled thereto so as to apply timing signals to cause production of the bursts. The timing signal source produces timing signals only according to a varying pattern whereby separation between adjacent signals meet certain present parameters. The energy patterns are applied to a transmitter which applies them to a scan area whereby the echo or returned energy from an object in the scan area is received and stored. The return from the next sequential burst is also stored and compared to the first. If the two agree the presence of the object is confirmed. If the two do not agree, then the contents of storage one is destroyed and the storage used to store the next sequential burst is compared. Failure to confirm means that an object was not present or that the object moved out of the scan area before its presence could be confirmed or a false signal was present, or one of a number of reasons, but no object is present.

Interference avoidance device for use in a sensor system

A fail-safe sensor system to provide a positive indication of the proper operation of a sensor system by accounting for the return signals from an active zone and a monitor zone beyond. Search signals, provided by a transducer operating in the transmit mode, are transmitted within an active zone within which objects to be detected are expected to be located. Unreturned search signals are permitted to travel beyond the active zone into a monitor zone beyond and objects in such monitor zone cause return signals which are also employed. A counter feed from a free running clock source is permitted to run up a count whose predetermined limit represents the estimated maximum time period during which a sensor system should operate without contacting an object. Return signals, whether from objects in the active zone or the monitor zone, reset the counter back to zero. The absence of a return signal permits the counter to exceed its predetermined limit and produce an output signal which can be directed to control circuitry, an alarm or logic circuitry to determine if the system is operative.

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Hampton, NJ, United States of America

James M Boozer