Ignition lock for motor vehicles with electromagnetic locking

Claim 1

An ignition lock system for an automotive vehicle comprising, in combination: a lock cylinder for controlling the ignition of a vehicle and rotatable upon insertion of a key into said cylinder properly coordinated with said cylinder, said cylinder being provided along its periphery with a recess; an electromagnet juxtaposed with said cylinder and having a plunger adapted to engage in said recess in a position of said cylinder in which said recess is aligned with said plunger and in a deenergized condition of said electromagnet whereby said plunger can retain said cylinder against rotation even with a key coordinated to said cylinder inserted in said cylinder; a first circuit for receiving a coded signal representing authorized use of said vehicle; means for generating said coded signal whereby said coded signal is received by said first circuit, said first circuit being operable independently of insertion of said key in said cylinder; a second circuit responsive to insertion of said key in said cylinder for detecting the insertion of a key coordinated to said cylinder; and a control circuit receiving inputs from said first and second circuits for energizing said electromagnet to withdraw said plunger from said recess only upon receipt by said first circuit of a coded signal representing authorized use of the vehicle and independently therefrom a signal from said second circuit engaging the insertion of a key coordinated with said cylinder into said cylinder, said second circuit comprising a luminous diode disposed on one side of said cylinder and a phototransistor disposed on an opposite side of said cylinder, said cylinder having a notch in line with said photodiode and said phototransistor in a position of said cylinder in which said plunger is engageable with said recess and interruptable by the key.