Patent GB-1334778-A (GB)
Title: Apparatus for operating a controlled device
IPC: G07C9/00
Filed: 1971-05-31
Abstract: 1334778 Locks R B PHINIZY 13 May 1971 [25 May 1970] 14830/71 Heading E2A A security system comprises a set of pushbuttons 10 and a key-receptacle 10K by means of which a sequential or instantaneous pattern of impulses may be fed to a detector circuit which operates a control 12 on receipt of a correct sequence but operates an alarm 20 if a wrong sequence is given. An anti-bandit circuit is provided which allows an operator to open the system under compulsion by using part of the correct button sequence together with a preselected false button which also gives a secret alarm. In addition a time delay 21 ensures that the signals must all appear within a set time to be effective. A mode selector 13 has a lever by means of which the operator may select to operate on push-buttons, or a key, or both. The buttons are connected through a patch panel of which the top part is reserved for the correct sequence sockets and the lower part for the rest. If wrong buttons are pushed or a wrong key used, a signal passes to a wrong signal detector 19, and if the correct push-button signals appear in the wrong order, a detector 16 detects it. In either case, a signal is sent to detector 18 to energise the alarm. Moreover, additional signals after the correct sequence, act to block operation of the control 12, by means of an anti-manipulation hold 17. In order to achieve all this, the buttons are connected to bistable elements 45-48, the first one, 45, being connected to the first button through terminals E, F, of the mode selector 13. The lower part of the board is connected to OR gate 19 which detects incorrect buttons. The sequential order of operation of the elements 45-48 is detected by a series of AND gates 50, 51, 52 whose outputs are connected in parallel with the output of OR gate 19 and also to a bistable element 18 feeding an OR gate 55 feeding the alarm in the event of an incorrect signal or sequence. The outputs of the bistable elements 45-48 feed an AND gate 53 controlling the control unit 12, a time delay 63 giving an antimanipulation feature. Timing of the sequence is achieved by a timer 58 feeding the Reset terminals of bistable elements 18 and 48. The 'ambush' button which operates the control 12 and also an alarm is connected to terminal A5. This is connected to set the bistable element 48 through diode 62, as required, but it also sends a grounding impulse to inverter 61, which feeds the OR gate 55 to operate the alarm 20. A capacitor 54 provides a time delay factor which gives the alarm on simultaneous operation of the buttons. For operation by key 70 which makes selective contacts 76, 77, 78, the selector 13 is switched to connect the key recognition circuit 80 to the AND gate 62. Suitable delay circuits 58 and 63 are described (Figs. 3, and 4, not shown). In the modified arrangement shown in Fig. 5, the push-button 12' are connected to active memory elements 150 comprising silicon controlled rectifiers, and feeding an AND gate 151 for the correct sequence, to operate a door latch driver 153, and feeding an OR gate 154 for an erroneous sequence to inhibit this driver and give the alarm at 157.