GB475865A - Improvements relating to warning systems for dwelling houses, hotels, and similar establishments - Google Patents

Abstract

475,865. Mercury switches. CIANCHI, A. March 23, 1936, No. 8686. [Class 38 (v)] [Also in Groups XXXIX and XXXVIII] For giving telephone calls, the bell-hammer or other part which is vibrated when a subscriber is called carries a mercury switch which is adapted to operate an electric lighting system, e.g. the ordinary lighting system at the subscriber's premises. As shown in Fig. 2, the ringing mechanism 12 operates a mercury switch mounted on a lever 9 and connected in a circuit 7 which is adapted to operate a warning system of the type described in Specification 436,216, [Group XXXVIII], wherein the ordinary lighting system 2 of a house or other establishment is used to give a warning when a door push button 16 is operated. Operation of the ringing mechanism 12 operates a mercury switch 18 to switch on the lights 3 during the day and vary the illumination by the inclusion of a resistance 4 during the night. The mercury switch 18 comprises a hollow armature 19 which when attracted by the solenoid 6a displaces mercury and establishes electrical contact between the electrodes 26, 27. The armature incorporates a valve 21 and byepass 28<1> which allows mercury to flow back into the armature and break the circuit after a time period in the event of continuous energization of the solenoid. Instead of the mercury switch, an electromagnetically operated two-way switch used in conjunction with a time delay thermostatic switch may be used. The mercury switch associated with the ringing mechanism may be mounted on a pivoted lever provided with a forked end which embraces the bell-hammer. One form of switch is shown in Fig. 5 and comprises a closed vessel 36 containing two pools of mercury 37, 38 which establish con. tinuous electrical contact between the electrodes 371, 38<1> when the switch is vibrated bodily. In a modification one pool may be arranged within the other. The Provisional Specification states that sound-emitting apparatus other than a telephone bell may be employed for operating the system.