GB595704A - An improved theft-alarm and protection device for shop or like windows - Google Patents

Abstract

595,704. Burglar and like alarms. MAY, H. A. June 1, 1945, No. 13751. [Class 118 (i)] In a shop-window or like theftalarm system, a lever normally rests against the inside of the glass but is arranged to bounce away when the window is struck, and thus close electric circuits to operate cameras and close the window space with shutters. A pivoted lever h is mounted by means of a suction pad b on the inside of the window a or frame and has a contact d near its upper end. Cooperating with this is a second contact mounted on an arm o pivoted on a fixed portion i and retained in a vertical position by a leaf spring e. A spring-loaded adjustable thumb-screw f serves to keep the lever h normally resting against the glass a and the contacts d are adjusted so as to be not quite touching. Any unusual shock to the window will cause the lever h to rebound and close the contacts d, thus energizing one or more solenoids to release two spring-urged shutters across the window space, and to operate a camera. The closing of the shutters completes a circuit for an audible alarm. The resilience of the spring e combined with the inertia of the lever h enables the contacts d to remain closed for a longer period than if the spring e were absent. The lever h is prevented from rebounding due to normal shocks, e.g. from traffic, by a weight nut j, which is vertically slidable.