Patent GB-596401-A (GB)
Title: Improvements in or relating to combination locks
IPC: G07C9/00
Filed: 1945-05-28
Abstract: 596,401. Electrically-controlled fastenings. BIRD, L. R., BARLOW, F., STUTTARD, S. P. May 28, 1945, No. 7798. [Class 44] [Also in Groups XXXV and XXXVII] The latch or bolt of a lock is controlled by electromagnetic means in the circuit of which are a number of pairs of contacts which are closed successively by the operation of a selectively wired multi-way or multi-terminal switch mechanism when an appropriate sequence of current impulses is sent from an operating device, preferably a device for dial operation in a manner similar to those employed in automatic telephone systems. Fig. 6 shows the circuit arrangements as wired for a combination 2970. The arrangement of the sending device B is such that as soon as the dial is moved away from its stop position the contacts blare closed and remain closed until the dial has returned to the stop position after release. A circuit is thus closed through the connections CC, battery D, the field magnet winding M and armature m<1> of a motor and connections PP. The armature is thereupon rotated until arrested by a stop, whereby contacts n<1> normally open are closed after the first few degrees of rotation and contacts n normallv closed are opened during the last few degrees of rotation (the dotted lines between these parts indicate operative relation only). The rotation also serves by operation of a pawlcontrolled wiper arm to bridge the first member g<1> of a set of contacts H with the corresponding member of a set H<1>. During the operation of the dial the contacts b<2> will have been closed and opened as many times as the number dialled, i.e. two for the first operation, causing two current impulses to flow from battery D through the electromagnet N, connections I, contacts b<2>, contacts b<1>, and connections C, energization of the magnet operating a pawl. mechanism twice to bring a selector switch arm e to contact 2. On return of the dial to its initial position the contacts b<1> are broken causing de-energization of the motor, the armature m<1> of which thereupon returns to its initial position under the influence of a counterweight, the motion being caused to take a predetermined time, say 6 seconds, by connection to gearing to provide a load. In the return motion the contacts n are bridged and a circuit is thus completed between the battery D through switch-arm e and contacts 2, g' and the corresponding member of set H<1> and relay 1 which operates to bridge the pairs of contacts 1a, 1b and 1c, 1d. On the further return motion of the armature a pawl retaining the switch arm e is released causing the arm to return to its zero position under the action of a spring. Energization of the relay 1 is however now maintained through the contacts 1a, 1b so long as the contacts n<1> are closed. If the period of say 6 seconds necessary for complete return of the armature is allowed to elapse before dialling the next number the contacts n<1> will be opened and the relay de-energized ; also the pawl retaining the wiper arm bridging the contacts of the series H, H<1> will be released and the arm returned by a spring to its zero position, this action serving As a safeguard against tampering. If however the second number is dialled before this period has elapsed the previous sequence of events will be repeated, the wiper arm being moved on to bridge contact g<2> and its opposite number in the H<1> series the selector switch arm e moved to contact 9 and the relay 2 energized to. bridge the contacts 2a, 2b and 2c, 2d. When all the relays have been energized and the corresponding contacts closed a circuit will be completed through the battery D and contacts C, L to energize the electromagnet 17 whereby a catch is withdrawn from the bolt enabling it to be operated by hand. Resistances R<1>, R<2>, R<3>, R<4> are connected as shown to limit surges on breaking the circuits concerned. An indicating lamp may be connected through the terminals X. The selecting mechanism is mounted between vertical panels on a base A<1>, Figs. 3, 4, these figures being sections drawn to show respectively the operation of the switch arm e and the arrangements for bridging the sets of contacts H, H<1>. As shown in Fig. 4 the armature m<1> is carried by a shaft m mounted on the end panels, the field magnets m<2>, m<3> being carried by rods on the panel b. The armature is provided with a counterweight t for effecting return. movement, gearing, not shown, for retarding return being connected to the shaft m. The armature is provided with a pin m<4> engaging a stop s in its normal position and a stud s<1> whereby rotation is limited to about 90 degrees. The opening and closing of the contacts n, n<1> is effected by a pair of angularly displaced arms, now shown, on the shaft m. In the last few degrees of motion of the armature a pin 14a on an arm 14 carried by the shaft m engages a pair of arms 13 pivoted at 11 causing a pawl 12 to engage a plate h<2> mounted in a shaft f moving it against the action of spring c so that a pair of wiper arms h, h<1> thereon bridge the first pair of contacts of the series H, H<1>. A pawl 15 which has been moved into contact with the rack during the initial movement of the armature by means not shown retains the plate h<2> in this position until moved to bridge the next pair of contacts in a subsequent operation. The contacts H, H<1> and those of the switch arm e are mounted on an insulating panel d. The selector switch arm e, Fig. 3, is carried by a racked quadrant e<2> mounted on the shaft f and biassed by spring f<1>. On passage of a series of impulses through the electromagnet N the armature 9 is attracted and released a corresponding number of times causing a pawl 8 mounted thereon to move the rack a corresponding number of steps to bring the switch arm to the appropriate contact, the rack being held after each movement by a retaining pawl 10, brought into engagement with the rack by the armature shaft in the last few degrees of its motion. In the lock shown in Fig. 5, the electromagnet 17 is provided with a pivoted armature 20 carrying an arm 20a having a projection 20b adapted when the lock is fastened to engage in a notch 21 in a rotary member 22 operated by a knob to retract the latch 23. The impulse sending device B may be mounted on the outside of the door in proximity to the lock or may be located elsewhere for distant control. Instead of the arrangement of relays described the mechanism may incorporate a plurality of selector switches, one for each digit in the combination, the coil of each being connected to a terminal of a distributor switch, each selector switch having say ten terminals, and the distributor switch having one terminal for each number element of the combination, for example four, the distributor switch being adapted to connect a fresh selector switch into circuit for each number element, the several switches acting in succession to complete the circuit of the latch releasing electromagnet.