Displacement sensing system

Abstract

A displacement sensing system including an oscillator circuit having a characteristic frequency which varies as a function of a magnetic field in the vicinity thereof, an element whose position relative to the oscillator circuit is varied by a displacement, the element being operative to vary the magnetic field in the vicinity of the oscillator circuit as a function of the displacement and circuitry for sensing a change of frequency of the oscillator circuit over time (delta f/delta t) and for providing an output indication when the change in frequency of the oscillator circuit over time exceeds a threshold.

1 - 146 . (canceled)  
   
   
       147 . Security apparatus comprising: 
 at least one displacement sensor associated with an object, said at least one displacement sensor sensing a distance of displacement;    at least one time duration sensor for sensing a duration of time said distance of displacement exceeds at least a first predetermined distance, indicative of a possible security violation; and    at least one alarm actuator operative to provide a security violation alarm in response to said duration of time exceeding at least a first predetermined duration.    
   
   
       148 . Security apparatus according to  claim 147  and wherein at least one of said first predetermined distance and said first predetermined duration is variable.  
   
   
       149 . Security apparatus according to  claim 147  and wherein said at least one alarm actuator is operative to provide at least said first and a second security violation alarm when said distance of displacement exceeds said first predetermined distance and a second predetermined distance for at least said first predetermined duration, said second predetermined distance being different from said first predetermined distance.  
   
   
       150 . Security apparatus according to  claim 147  and wherein: 
 said at least one alarm actuator is also operative to provide at least an additional security violation alarm when said duration of time exceeds a second predetermined duration, said second predetermined duration being different from said first predetermined duration.    
   
   
       151 . Security apparatus according to  claim 147  and wherein: 
 said at least one time duration sensor is also operative to sense an additional duration of time said distance of displacement exceeds a second predetermined distance, said second predetermined distance being different from said first predetermined distance; and    said at least one alarm actuator is also operative to provide at least an additional security violation alarm when said additional duration of time exceeds a second predetermined duration, said second predetermined duration being different from said first predetermined duration.    
   
   
       152 . Security apparatus according to  claim 149  and wherein at least one of said first and second predetermined distances and said predetermined duration is variable.  
   
   
       153 . Security apparatus according to  claim 148  and wherein said first predetermined distance varies as a function of a currently perceived security violation threat.  
   
   
       154 . Security apparatus according to  claim 153  and wherein said currently perceived security violation threat is determined by a pattern of past distances of displacement sensed by said at least one displacement sensor.  
   
   
       155 . Security apparatus according to  claim 147  and wherein at least one of said at least one displacement sensor and said at least one duration sensor are operated in accordance with a duty cycle.  
   
   
       156 . Security apparatus according to  claim 155  and wherein said duty cycle is variable.  
   
   
       157 . Security apparatus according to  claim 156  and wherein said duty cycle is adaptive.  
   
   
       158 . Security apparatus according to  claim 156  and wherein said duty cycle varies as a function of a currently perceived security violation threat.  
   
   
       159 . Security apparatus according to  claim 158  and wherein said currently perceived security violation threat is determined by a pattern of past outputs of said at least one displacement sensor sensing said distance of displacement.  
   
   
       160 . Security apparatus according to  claim 147  and wherein said first predetermined distance varies in accordance with long time scale changes in said distance of displacement.  
   
   
       161 . Security apparatus according to  claim 147  and also comprising wireless communication circuitry operative to transmit said security violation alarm to a remote receiving location.  
   
   
       162 . Security apparatus according to  claim 147  and also comprising a locator operative for sensing the location of at least one of said displacement sensor, said time duration sensor and said alarm actuator.  
   
   
       163 . Security apparatus according to  claim 147  and wherein at least one of said displacement sensor, said time duration sensor and said alarm actuator are attached to said object.  
   
   
       164 . Security apparatus according to  claim 147  and wherein said at least one displacement sensor is operative for sensing said distance of displacement by sensing changes in a magnetic field in the vicinity of said displacement sensor.  
   
   
       165 . Security apparatus according to  claim 164  and wherein said magnetic field is generated by a magnet, which is associated with said displacement sensor.  
   
   
       166 . Security apparatus according to  claim 165  and wherein said magnet is mounted onto said displacement sensor.  
   
   
       167 . Security apparatus according to  claim 165  and wherein said magnet is physically separated from said displacement sensor.  
   
   
       168 . Security apparatus according to  claim 165  and wherein said magnet is mounted onto said object.  
   
   
       169 . Security apparatus according to  claim 165  and wherein at least one of said displacement sensor, said magnet, said time duration sensor and said alarm actuator is attached to said object.  
   
   
       170 . Security apparatus according to  claim 164  and wherein said at least one displacement sensor is operative to sense changes in said magnetic field by sensing changes in the frequency of an oscillator for which the oscillating frequency changes in accordance with changes in said magnetic field.  
   
   
       171 . Security apparatus comprising: 
 at least one displacement sensor associated with an object, said at least one displacement sensor sensing a distance of displacement;    at least one time duration sensor for sensing a duration of time said distance of displacement exceeds at least a first predetermined distance, indicative of a possible security violation; and    at least one alarm actuator operative to provide a security violation alarm when said distance of displacement exceeds said first predetermined distance for at least a first predetermined duration and is followed, within a predetermined time window, by another distance of displacement which exceeds at least a second predetermined distance for at least a second predetermined duration.    
   
   
       172 . Security apparatus according to  claim 171  and wherein said first predetermined distance and said second predetermined distance are equal.  
   
   
       173 . Security apparatus according to  claim 171  and wherein said first predetermined distance and said second predetermined distance are not equal.  
   
   
       174 . Security apparatus according to  claim 171  and wherein said first predetermined duration and said second predetermined duration are equal.  
   
   
       175 . Security apparatus according to  claim 171  and wherein said first predetermined duration and said second predetermined duration are not equal.  
   
   
       176 . Security apparatus comprising: 
 at least one displacement sensor associated with an object, said at least one displacement sensor sensing a distance of displacement; and    at least one time duration sensor for sensing a duration of time said distance of displacement exceeds at least a predetermined distance, indicative of a possible security violation, and wherein said sensor provides an output indication.    
   
   
       177 . Security apparatus according to  claim 176  and wherein said predetermined distance is variable.  
   
   
       178 . Security apparatus according to  claim 177  and wherein said predetermined distance varies as a function of a currently perceived security violation threat.  
   
   
       179 . Security apparatus according to  claim 178  and wherein said currently perceived security violation threat is determined by a pattern of past distances of displacement sensed by said at least one displacement sensor.  
   
   
       180 . Security apparatus according to  claim 176  and wherein at least one of said at least one displacement sensor and said at least one time duration sensor are operated in accordance with a duty cycle.  
   
   
       181 . Security apparatus according to  claim 180  and wherein said duty cycle is variable.  
   
   
       182 . Security apparatus according to  claim 181  and wherein said duty cycle is adaptive.  
   
   
       183 . Security apparatus according to  claim 181  and wherein said duty cycle varies as a function of a currently perceived security violation threat.  
   
   
       184 . Security apparatus according to  claim 183  and wherein said currently perceived security violation threat is determined by a pattern of past outputs of said at least one displacement sensor sensing said distance of displacement.  
   
   
       185 . Security apparatus according to  claim 176  and wherein said predetermined distance varies in accordance with long time scale changes in said distance of displacement.  
   
   
       186 . Security apparatus according to  claim 176  and also comprising a locator operative for sensing the location of at least one of said displacement sensor and said time duration sensor.  
   
   
       187 . Security apparatus according to  claim 176  and wherein at least one of said displacement sensor and said time duration sensor is attached to said object.  
   
   
       188 . Security apparatus according to  claim 176  and wherein said at least one displacement sensor is operative for sensing said distance of displacement by sensing changes in a magnetic field in the vicinity of said displacement sensor.  
   
   
       189 . Security apparatus according to  claim 188  and wherein said magnetic field is generated by a magnet, which is associated with said displacement sensor.  
   
   
       190 . Security apparatus according to  claim 189  and wherein said magnet is mounted onto said displacement sensor.  
   
   
       191 . Security apparatus according to  claim 189  and wherein said magnet is physically separated from said displacement sensor.  
   
   
       192 . Security apparatus according to  claim 189  and wherein said magnet is mounted onto said object.  
   
   
       193 . Security apparatus according to  claim 189  and wherein at least one of said displacement sensor, said magnet, and said time duration sensor is attached to said object.  
   
   
       194 . Security apparatus according to  claim 188  and wherein said at least one displacement sensor is operative to sense changes in said magnetic field by sensing changes in the frequency of an oscillator for which the oscillating frequency changes in accordance with changes in said magnetic field.  
   
   
       195 . Security apparatus comprising: 
 at least one displacement sensor associated with an object, said at least one displacement sensor sensing a distance of displacement;    at least one time duration sensor for sensing a plurality of time durations during which said distance of displacement exceeds a corresponding plurality of predetermined distances, each of said plurality of predetermined distances being associated with a respective one of a plurality of predetermined durations, indicative of a possible security violation; and    at least one alarm actuator operative to provide a security violation alarm when at least one of said plurality of time durations exceeds a corresponding one of said plurality of predetermined durations.    
   
   
       196 . Security apparatus according to  claim 195  and wherein said plurality of predetermined durations are determined as inverse functions to corresponding ones of said plurality of predetermined distances.  
   
   
       197 . Security apparatus according to  claim 195  and wherein said at least one alarm actuator provides at least said first and a second security violation alarm when said distance of displacement exceeds a first and a second of said plurality of predetermined distances for a first and a second of said respective predetermined duration.