| 摘要 |
<p>1,081,782. Burglar alarms. GENERAL ALARM CORPORATION. March 9, 1966 [Oct. 4, 1965], No. 10255/66. Heading G4N. A door 10 is secured against more than a predetermined amount of movement relative to a jamb 11 by a chain 13 one end of which is detachably mounted in a slotted plate 12 on the door whilst its other end is fixed to a bolt 36 which projects from a switch operating lever (28), Fig. 3A (not shown), contained in a housing 16. If the chain is tensioned it causes lever (28) to actuate the operating handle (26) of an alarm switch (25), Fig. 2 (not shown), thus placing alarm (21) in circuit with a battery (22). The alarm may be a bell or buzzer in housing 16 or it may be a remote alarm, e.g. a flashing light. The alarm may also be sounded by a push-button 37. In a modification, Fig. 7, the chain is secured at one end to a strike plate 61 of a lock and at its other end to an anchor 91 which is slidable in a slot in a housing 60 secured to the door. Unlocking of the door from the outside by turning a key in lock cylinder 72 is prevented by a thumb-turn 71 which is slotted at 92 to receive a projection on chain anchor 91. If the door is forced the chain will cause housing 60 to tilt about a fulcrum 75. This causes a slot 81 in housing 60 to engage a switch handle 77 of alarm switch 79, thus placing alarm 80 in circuit with a battery 78. A lamp (86), Fig. 9 (not shown), lights up to indicate when bolt (67) is retracted.</p> |
