Patent GB-712626-A (GB)
Title: Improvements in or relating to picture telegraph receivers
IPC: H04N1/08
Filed: 1951-05-29
Abstract: 712,626. Copying-telegraph receivers. GENE RAL ELECTRIC CO., Ltd., and COLLINS, L. Aug. 29, 1952 [May 29, 1951], No. 12599/51. Class 40 (3) In a picture telegraph receiver comprising a rotatable drum on which photographic paper or film can be detachably secured and which is enclosed within a light-proof housing, means is associated with the drum to enable the paper or film to be secured to, or removed from, the drum without opening the housing to give access to the drum. The drum 1, which is driven through a ball clutch from a motor, is mounted in a housing comprising a front portion 16, which may have a suitable inspection window, hinged at 17 to a rear portion 15 carrying channel members 18, 19, for loading and discharging magazines 21, 22 respectively. The loading magazine 21, Figs. 9, 10, has a tapered end 71 closed by a hinged flap 72 and a detachable end 74 formed with spaced members 78, 79 between which are supported light springs 75, 76 which are compressed when the recording sheet is inserted and the end 74 closed. The discharge magazine 22, Figs. 12, 13, comprises a metal portion 83 s'idable between portions 84, 85 and carrying a member 87 engaging a member 96, Fig. 1, of the channel member when the magazine is inserted. Spring retaining members 88, 89 carry studs 94, 95 engaging arcuate grooves and are moved out of their latching positions to the positions 88<SP>1</SP>, 89<SP>1</SP>. The leading and trailing edges of the paper 99 are retained on the drum 1 by clips 26, 27, Fig. 4, comprising fingers mounted on rods 29, 30 terminating in levers 32, 33 pressed by springs 34, 35 to keep the clips 26, 27 normally in their closed position. The levers 32, 33 carry studs 36, 37 which are engaged by cams 41, 42, Fig. 5, mounted on a plate adjacent the end of the drums. The cam 41 has two surfaces 49, 50 and the stud 37 projects further axially than the stud 35 so that the surface 49 engages the stud 36 and the stud 37 is engaged by the surface 50. The cams are moved to their operative positions with respect to the studs by a lever 44, Fig. 5, which can be rotated to positions corresponding to " head," "take-up," "run" and "discharge," and operates through gear wheels 46, 47 to set the cams 41, 42 appropriately. The gear wheel 47 has a limited number of teeth so that the cam 42 is operated when the arm approaches the discharge position, but is otherwise held in a non-operative position by a spring 53. The drum is brought to predetermined seat positions by an arm 56 which in the phasing position 56' rocks a shaft 57 carrying a short arm 58 to the position 58' in which it engages a stop 55 on the drum. For the arrestment of the drum in the "load" position, the arm 56 is rocked to the slot 62 so that a cam 64 on the shaft 57 rocks a lever 65 to the position 65' in which it engages the stop 55 on the drum. With the drum in the loading position the magazine 21 is pushed in so that a roller 98, Fig. 1, opens the flap 72 and the paper 99 is urged by the springs into engagement with the clip 26 which has been opened by the surface 49 of the cam 41 engaging the stud 36 when the lever 44 is moved to the load position. The drum is set into rotation, and the lever 44 moved to "take-up," Fig. 15b, so that the engagement of the surface 50 of the cam 41 with the stud 37 opens the clip temporarily during each revolution to allow the sheet 99 to be wrapped around the drum. During the "takeup" period, rollers 101 bear on the sheet and are lifted by members 65, 106, 107 when the lever 44 is moved to the "run" position in which the clips 26, 27 are not operated. When the lever 44 is moved to the " discharge " position the stud 36 is engaged by the cam 42 and, as shown in Fig. 15d, opens the clip 26 near the bottom of its travel so that the leading edge of the sheet 99 moves into a channel formed by a guide 115 leading to the opening in the discharge magazine 22. The sheet is prevented from bowing out by pins 116 moved to the position 116' when the lever 44 is in the discharge position and the stiffness of the sheet disengages the trailing edge from the clip 27 so that the sheet is projected into the discharge magazine. The withdrawal of the magazine 22 allows the metal portion 83 to close automatically. The recorded sheet may pass directly into a processing tank, and in lieu of single record sheets, a roll of recording paper may be employed with appropriate severing mechanism. The optical head comprises a mirror galvanometer associated with a light source and a shaped aperture so that the amount of light passed by the aperture to the film on the drum 1 is dependent on the signal applied to the coil of the galvanometer.