Patent GB-484308-A (GB)
Title: Improvements in automatic burglar and fire alarms
IPC: H04M11/04
Filed: 1936-11-04
Abstract: 484,308. Fire &c. alarm systems ; gramophones. MOUNTSTEPHEN, E. R., WOOD, W. J., and SPENCE, A. G. Nov. 4, 1936, Nos. 30014/36 and 22707/37. [Classes 40 (i) and 40 (ii)] [Also in Group XXXIX] In automatic sub-station equipment which, in the event of burglary or fire, causes a connection to a police or other station to be set up and a message transmitted thereto from a gramophone, the means for effecting the necessary sequence of events are operated by a self-contained driving unit comprising a shaft geared to the gramophone motor and operating further shafts which effect the dialling operation and operate lowering, lifting and restoring mechanism for the tone arm of the gramophone. Specification 442,565 is referred to. Driving unit. A vertical shaft 8, Fig. 1, geared at 14, 15 to the spindle of the gramophone turntable drives a dial-operating shaft 10 through bevel gearing 16, 17 and a tonearm operating shaft 11 through a worm and worm-wheel 19, 20. The shaft 11 also carries a cam 21 controlling the position of the dial and the mechanism so far described is all carried by a bracket 12 secured to base-plate 13. According to the first Provisional Specification the dial and tone-arm control mechanism is driven by a common shaft geared to shaft 8. Dialling mechanism. A standard dial 26 with a pin 29 inserted in the " O '' or other hole is carried by a pivoted arm 27 so that it may be moved substantially vertically to bring pin 29 into the path of an arm 25 on a crown wheel 22 driven by pinion 18 on a shaft 10. The dial is raised by lever 33 engaging beneath a pivoted finger 35 on the dial body and operated by lever 31 and cam 21 which is shaped so as to raise and lower the dial a number of times corresponding to the number of digits and maintain it raised for periods corresponding to the value of the digits. It is arranged that on the last digit the dial is rotated (clockwise) sufficiently for pin 29 to push finger 35 out of engagement with lever 33 so that cam 21 subsequently does not raise and lower the dial. This may obviously be done if only the last digit is 0 but if the number 999 is required advantage is taken of the operating margins of dial to rotate it a little further for the last 9 than for the others. Alternatively, the finger 35 may be moved to an ineffective position by mechanism controlled directly by cam 21. Tone-arm controlling mechanism. The tonearm 39 and casing 40 containing the transmitting microphone constructed as described in Specification 484,307 is carried by a spindle 41 to permit rotation of the arm over the record, the spindle being mounted in a member 42 horizontally pivoted and carrying an arm 50 by which the tone-arm is lowered and raised. The arm 50 is held in the raised position of the tone-arm by a catch 47 engaging a roller on arm 50 and when shaft 11 is rotated a cam thereon pushes catch 47 clear, takes over its function temporarily and then gradually lowers the tone-arm. After one revolution of shaft 11, the cam raises the tone-arm again and a plate 45 on tone-arm spindle 41 comes against stop 46 but owing to the rotation of the tone-arm across the record, plate 45 meets stop 46 at an angle so that the tone-arm is urged back to its original position. The tone-arm is again lowered and the record repeated several times until the motor runs down. Connecting the apparatus to line, starting and disconnecting. Operation of alarm magnet 57 and armature 55 releases a weighted arm 58 which (1) disengages a counterweighted catch 60 from a stop 61 on the. turntable and (2) depresses a lever 64, operating a multicontact switch 54 to connect the apparatus to line. Lever 64 is held down by the armature 68 of release magnet 69. When the governor of the gramophone speeds up, disc 77 thereon moves a contact lever 74, Fig. 1, into the broken line position and after the digits have been dialled, the movement of pivoted finger 35 as previously described is accompanied by movement of link 79 which swings a contact lever 75 into the path of contact lever 74. When the gramophone motor runs down, lever 74 returns to its normal position and makes contact with 75 to operate the release magnet 69 whereupon lever 64 is released and switch 54 disconnects the apparatus. Parts of the mechanism such as lever 58 and finger 35 are restored manually.