GB785450A - Improvements in or relating to facsimile telegraph scanning mechanism - Google Patents

Abstract

785,450. Copying-telegraphy. MUIRHEAD & CO., Ltd. June 3, 1955 [June 29, 1954], No. 19056/54. Class 40 (3). In a facsimile scanning mechanism comprising a drum and automatic stopping mechanism, a manuallyoperated member initiates the operation of means by which the speed of the drum is automatically reduced below a predetermined level before the automatic stopping mechanism is engaged to stop the drum in a desired position for unloading and loading the sheets employed by a transmitter or by a receiver. As shown in Fig. 1, the drum 1 is rotated by a gear 3 meshing with a gear 4 driven from the motor 5 and which rotates a toothed wheel 24. The drum is traversed by a half-nut 6 which is mounted on a shaft 6a and engages a threaded shaft 2. For the scanning operation the lever 20 is moved to the right so that the rod 23 operates a switch 23<SP>1</SP> to its upper position in which the motor drives the drum 1 and wheel 24 in the direction of the arrows A, B. During scanning a pawl 25 connected by a spring 26 to a pin on the wheel 24 rocks and passes a latch 27 biased by a spring 29. When scanning ceases the nut 6 engages a non-threaded part of the shaft 2 and the transverse of the drum is discontinued. The member 20 is moved to the left to operate the switch 23<SP>1</SP> to reverse the motor so that the drum is firstly brought to rest before commencing its reverse movement during which the pawl 25 is engaged by the latch 27 so that the wheel 24 under the action of spring 26 is brought to a stop and returns to the position with the pin 25a in engagement with the pawl 25. The lever 20 may be actuated by a projection on the lid of the machine so that the motor is operated in the forward direction when the lid is closed, and the switch is operated for the reverse movement when the lid is raised. In the alternative arrangement, Fig. 2, the drum 35 is mounted on a hollow shaft 36 which is driven from a motor 47 and which through gears 58, 59, 60, 61 drives, at a speed different from that of the drum, a threaded shaft 34 engaged by a half nut 37 projecting through a longitudinal slot 38 to effect connection of the drum to the hollow shaft which carries a gear wheel 39 engaging a gear 40 on a shaft 42. In the operative position of the lever 51, a spring 50 operates on clutch plates 41, 41a directly, and through a pin 42a and collar 42b connects gear wheel 40 to a sleeve extension 43a of gear wheel 43 driven from the motor 47 at the synchronous speed and driving a gear wheel 46 freely rotatable on the shaft 36. Gear 39 is driven at a slightly faster rate than gear 46 and carries a lug 48 operating in conjunction with a permissive latch 49 on the wheel 46 so that the latch can pass the lug 48 when the wheel 39 is stationary, but the lug 48 cannot pass the latch 49 when the wheel 39 tends to overtake the wheel 46. When scanning is complete, the movement of the lever 51 to the left opens the clutch plates 41, 41a so that the drive is disconnected from the wheel 39 which is braked by a projection 62 carried by a stop arm 52. When the speed of the wheel 39 has been considerably reduced the projection 62 is able to enter an aperture 53 so that the drum 35 is arrested in a predetermined position. After the drum 35 has been moved to the left and loaded the movement of the lever 51 to the right allows gear 39 to be driven from gears 40, 43, 44 and brought up to synchronous speed at which it is held by the engagement of the lug 48 with the latch 49 on the wheel 46 driven directly by the synchronous motor 47.