APPARATUS FOR MUTUAL INFORMATION TRANSMISSION IN A LOCK AND KEY SYSTEM

摘要

An apparatus for mutual information transmission between an electronic lock and a key uses antenna coils at both the key and lock. A periodic signal is emitted from the lock and is received by the key upon activation of a key electronics and emission of a coded information signal. This returned signal received from the lock coil is briefly short-circuited or damped at the key side in order to produce a synchronization switch synchronizing the points in time of the signal appearance. Electronic converters are provided which, given the pre-condition that the short-circuit signal extends over a plurality of signal pulses, generate a digital signal corresponding to the shortcircuit times.