Patent GB-809007-A (GB)
Title: Improvements in or relating to protective apparatus for electro-sensitive paper recorders
Inventor: FERGUSON ROBERT SCOTT
IPC: H04N1/00
Filed: 1956-02-20
Abstract: 809,007. Copying-telegraph receivers. MUIRHEAD & CO. Ltd. Feb. 8, 1957 [Feb. 20, 1956], No. 5194/56. Addition to 736,428. Class 40 (3). The protective arrangement for the facsimile recorder claimed in the parent Specification in which a pad or button on a contact spring moves into a cavity on a support member when the recording paper is broken or the supply fails and closes a fixed contact to operate an alarm, is modified by the provision of a contact spring with a pad in engagement with the paper on the fixed support member and carrying the fixed contact of the alarm circuit and a further or third spring member spaced from the spring member carrying the fixed contact and carrying a contact normally engaged by a contact on the spring member having the pad located opposite the cavity in the support member. As shown in Fig. 1, the recording paper 20 is fed from a roll 21 over a support member 23 between a bar electrode 27 and the helical electrode 26 of a drum 25 and over a support 24. Contact spring 29 carries a pad or button 33 located opposite the cavity 34 and spring 28 carries a pad 32 engaging the paper 20 on the support member 23. A third spring 30 spaced from spring 28 by a distance piece 30a carries a contact in engagement with a contact on the spring 29 when its button 33 engages recording paper passing over the cavity 34. If the paper breaks or its supply fails, the button 33 passes into the cavity 34, closing contacts on the springs 28, 29 to actuate an alarm and opening the contacts on springs 29, 30 to perform a function, such as the disconnection of the drive to the drum 25. The relative positions of the contacts 28, 29, 30 shown in Fig. 1 for the operative condition of the recorder with its door closed are as for the inoperative state with the door open. In a modification, Figs. 2 and 5, the distance piece 30a is omitted, and the spring 30 is provided with a stiffing strip 67. The contact assembly is mounted on the cover of the casing of the recorder and is adjusted so that all the contacts are open as indicated by Fig. 4 (not shown), when the cover is raised. With normal paper feed as in Fig. 5, the closure of the switch 40 manually or automatically in response to a signal from the transmitter, completes the circuit of an electromagnetic clutch 37 from springs 29, 30 to brushes 35, 39, rings 36,38 and battery 41. Armature 42 is attracted against the action of spring 46 to engage its slot 44 with the pin 45 on shaft 43 to connect the drum 25 to the shaft 48. Contact members 50, 51 are separated and members 50, 52 closed to transfer the output of signal receiver 55 from the load resistor 57 to the printing bar 27. If the paper supply fails, the pad 33 moves into the cavity 34, the contacts carried by the springs 29, 30 are opened, the clutch 37 is deenergized and the contacts of members 50, 51 close so that the output of 55 is applied to the load resistor 57. Also, the closure of contacts carried by the springs 28, 29 connects the secondary winding of transformer 58 via capacitor 63 and resistor 64 to the cathode circuit of the valve V1 so that the coupled valve pair VI, V2 is set into oscillation to produce an alarm signal from the loud-speaker 66. When the casing of the recorder is opened the contacts carried by the springs 28, 29, 30 are all opened so that the clutch and alarm circuits are rendered inoperative.