Apparatus for mutual information transmission in a lock and key system

Claim 1

An electronic lock control device for use in lock-key system having a lock and a key for inductive coupling with said lock and thereby generating an encoded signal of damped and undamped signals, comprising: means in said lock for generating a periodic signal; coil means in said lock for transmitting said periodic signal; said coil means being selectively energetically coupled to said key to alternately damp and undamp said periodic signal means in said lock for comparing the amplitudes of said damped and undamped periodic signal comprising: a first comparator means; means for supplying one side of said comparator means with a first signal having an amplitude between the amplitude of said damped periodic signal and the amplitude of said undamped periodic signal; means for supplying a second side of said comparator means with said damped and undamped periodic signal; said comparator producing a periodic comparator signal during said undamped periodic signal and producing a continuous signal during said damped periodic signal; and means for removing said periodic comparator signal and retaining said continuous signal; whereby a signal is produced only during said damped periodic signal.

Claim 5

A device for detecting an encoded signal in an electronic lock, the encoded signal being generated by an electronic key inductively coupled to said electronic lock and being characterized by alternately damped and undamped periodic signals, comprising: first and second branches, a first comparator having a non-inverting input and an inverting input connected to respective ones of said first and second branches, a rectifier connected in said first branchtto supply a selectively definable d.c. voltage thereto, a voltage divider in said second branch, a second comparator having inverting and non-inverting inputs, said non-inverting input of said second comparator being connected to said voltage divider, said inverting input of said second comparator being connected to a circuit ground, a first flip-flop having a clock input connected to an output of said second comparator and a clear input connected to an output of said first comparator, an inverter connected to an output of said second comparator, a second flip-flop having a clock input connected to said inverter and a data input connected to an output of said first flip-flop, whereby an output signal from said second flip-flop corresponds exactly to said encoded signal.

Claim 6

A device for detecting an encoded signal in an electronic lock, the encoded signal being generated by an electronic key inductively coupled to said electronic lock and being characterized by alternately damped and undamped periodic signals, comprising: first and second branches, a first comparator having a non-inverting input and an inverting input connected to respective ones of said first and second branches, a rectifier connected in said first branchtto supply a selectively definable d.c. voltage thereto, a voltage divider in said second branch, a second comparator having inverting and non-inverting inputs, said non-inverting input of said second comparator being connected to said voltage divider, said inverting input of said second comparator being connected to a circuit ground, a first flip-flop having a clock input connected to an output of said second comparator and a clear input connected to an output of said first comparator, an inverter connected to an output of said second comparator, a second flip-flop having a clock input connected to said inverter and a data input connected to an output of said first flip-flop, whereby an output signal from said second flip-flop corresponds exactly to said encoded signal.