GB1453298A - Electronic locking system - Google Patents

Abstract

1453298 Locking devices INTERTECH INC 22 Nov 1973 54224/73 Heading E2A An opto-electronic locking system for a closure member D having a locking bolt 40, comprises an optically encoded key 10, an identically optically encoded element 18 in the closure member and hidden from view, light sources 14, 16 for irradiating the key and the element whereby a matrix code 12 is formed having pre-determined light levels, separate light sensor 22, 28 for the key and the element whereby the light levels obtained therefrom are converted into electrical signals and a linearly movable separator 20 positioned between the key and the element whereby when the key is inserted in the closure member and moved past one light sensor 26 the separator is engaged and moved which in turn moves the element in a linear direction past the light sensor 28. There is also a comparator device 25 for comparing the output of the electrical signals from the key with the signals from the element, a solenoid for actuating the bolt 40 and an electronic circuit connecting the comparator device with the solenoid including an AND gate whereby when the electric signals derived from the key and the element at the AND are identical the solenoid is activated to unlock the locking bolt. As shown, the key 10 has a pre-arranged matrix code 12 having an optical filter coating thereon to prevent direct readout and copying of the code and the sensors 26, 28 are provided with opto-electronic light detectors 22, 24 such as photo-transistors, photo-Voltaic cells or photo-resistors; the plate 18 is spring-biassed back to the normal forward position thereof. When the key 10 and plate 18 are moved across the detectors 22, 24 the outputs of the latter are fed to the comparator 25 which compares each corresponding bit of the output of the detectors from the key and plate, the output of the comparator being logically true when the inputs from the key and plate have identical logical values. The output of the comparator is fed to the AND gate 30 having auxiliary inputs a, b, c, d, which clear the flip flop 31 under certain conditions the first of which conditions is the input into the d input and the gate and from the light source 16 through detector 17 and amplifier 19 whereby false comparison due to light source failure is prevented and the second of which conditions is the input from the antenna 37 and inverter amplifier 35 into the input c of the gate to prevent false true setting of the flip flop due to electrical noise; inputs a and e are used to reset the flip-flop after the lock has operated. A micro-switch 32 operated by the plate 18 initially sets the flip flop at the beginning of insertion of the key. The output of the flip flop is fed to AND circuit 34 having a second input from the switch 33 which is operated by plate 18 following full insertion of the key, the two inputs being logical true only when the key 10 and plate 18 have the same pattern; the output of the AND circuit 34 is fed to a driver circuit 36 which in turn actuates the solenoid 38 to withdraw the lock bolt 40.