초록 ▼

An alarm system monitors a region, and includes a transducer supported to aim toward a boundary of the region. The transducer transmits sonic waves and receives echoes. The system generates an initial value corresponding to the distance between the transducer and a boundary of the region at one time

An alarm system monitors a region, and includes a transducer supported to aim toward a boundary of the region. The transducer transmits sonic waves and receives echoes. The system generates an initial value corresponding to the distance between the transducer and a boundary of the region at one time, and activates the transducer at a later time to generate a current value corresponding to the distance between the transducer and a location from which the echoes originate. A control compares the current value to the initial value and activates an alarm when the current value differs significantly from the initial value. In one embodiment of the invention, the transducer aims toward a window of a vehicle and thereby detects either opening of the window or an associated door, breakage of the window, or intrusion into the vehicle between the transducer and the window. Transducers mounted on the underside of a trunk lid and a hood detect lifting the trunk lid or hood, respectively. The hood transducer also detects elevation of the vehicle.

대표청구항 ▼

An alarm system for detecting movement of a vehicle upwardly from a surface supporting said vehicle, said alarm system comprising: transducer means, facing downwardly toward said surface, for transmitting a sonic wave toward and receiving an echo from said surface; an alarm; electronic means for act

An alarm system for detecting movement of a vehicle upwardly from a surface supporting said vehicle, said alarm system comprising: transducer means, facing downwardly toward said surface, for transmitting a sonic wave toward and receiving an echo from said surface; an alarm; electronic means for activating said transducer means to transmit a sonic wave and receive an echo and thereby determine a parameter indicative of a reference distance from said transducer means to said support surface; and means for periodically activating said transducer means and comparing current data corresponding to the distance from said transducer means to said support surface to said reference distance, and activating said alarm if said current data indicates a current distance that is significantly greater than said reference distance.