US 4,845,682 A · Interference avoidance device for use in a sensor system

Abstract

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.

Claims28

Dependent claims

An interference avoidance device for use in a sensor system comprising:

generator means to selectively generate a predetermined pattern of signals;
first control means for producing first control signals coupled to said generator means to produce one of said predetermined patterns of signals for each first control signal;
timing means for producing timing signals coupled to said control means to cause said control means to produce a first control signal for each timing signal received;
said timing means producing said timing signals at irregular intervals to cause said predetermined pattern of signals to occur at irregular intervals;
transmitter means coupled to said generator means for transmitting said predetermined pattern of signals toward a remote point;
receiver means to receive any reflected signals which result from the contact of said transmitted signals with a remote object;
at least two storage means, a first storage means coupled to said receiver means to store a first reflected signal pattern;
second storage means coupled to said receiver means to store the next sequential reflected signal pattern;
and
comparison means coupled to said first and said second storage means to produce a first output signal if the contents of said first and said second storage means are the same and a second output signal if the contents of said first and said second storage means are different.

7 more elements

Dependencies are inferred from the claim text.

Interference avoidance device for use in a sensor system

Life of this patent

Interference avoidance device for use in a sensor system

Life of this patent

Abstract

Claims28