Patent GB-733292-A (GB)
Title: Photoconductive facsimile transmitting apparatus
IPC: H04N1/29
Filed: 1953-10-09
Abstract: 733,292. Copying-telegraphy. CREED & CO., Ltd. Oct. 9, 1953 [Dec. 30, 1952], No. 27871/53. Class 40 (3). A facsimile transmitter comprises a photosensitive storage member which, after being uniformly charged to predetermined potential by exposure to a light image to produce a corresponding electrostatic charge image, is scanned by means including an electro-mechanical pick-up device to produce facsimile signals corresponding to the electrostatic charge on elemental areas of the storage member. A drum 11 having a conductive surface covered by photo-conductive material 12, such as anthracene, anthraquinone, or sulphur constitutes the storage member and is charged by rotation slowly relative to a set of prongs 17 on a member 16 fed with voltage from a suitable source. For the charging operation the drum is driven from a motor 42 by a worm and worm wheel 43, 38 and an electromagnetic clutch member 23 having a pin-and-slot connection with the shaft 13 of the drum. The motor and clutch are connected in parallel and in series with the contacts of a switch 37 which are normally open and shunted to start the motor, and when closed maintain the motor circuit until the switch is returned to normal by a cam 36 on the shaft 14 driven by the motor 42. For the exposing operation a circuit is completed for magnetic clutch 44 which through plate 48 connects a pulley 49 to the shaft 13 so that the motor rotates the drum for one revolution. Also the pulley 49 via belt 51 and pulleys 52, 53 rotates a shaft 54 carrying a mirror 61 which by means of a lens 64 having a shutter 66 operated by a solenoid 67 traverses an image of the matter to be transmitted over a slot 65 in a screen 68 located near the drum 11 so that a charge pattern of the matter 62 is formed on the drum. A high-speed motor 168 via helical gears 69 and intermediate gears 71 drives a gear 72 which through a one-way wedging-ball clutch 73, 74 rotates the drum, and through gear 76 drives a lead-screw 77 on which a half nut 78 is engaged by the energization of a magnet 83. The nut 78 is on a lever pivotally connected to a scanning carriage 79 sliding on rails 81 and provided with a stylus 84 mounted in a block 85 attached to the carriage. A cam 87 closes contacts 88 to transmit a phasing signal during each revolution of the drum 11 and a switch 89 operated by the end of the screw 77 at the conclusion of the travel of the carriage 79 opens the circuit of the magnet 83 so that the half nut is disengaged and the spring 91 returns the carriage to its initial position. Circuit arrangement, Fig. 2. With the switch 101 in the charge position, the actuation of key 102 operates relay 105 switching in the motor 42 and energizing the clutch 23 to rotate the drum 11 and the closure of contacts 37 by the cam 36 by-passes the key 102. Relay 103 operates and voltage is applied by transformer 104 to the member 16. When the switch 101 is moved to the " Expose " position and key 102 is closed, the motor is again operated and clutch 44 is energized to operate the pulley 49. The magnet 67 for the shutter 66 is also operated. When transmission is to take place the actuation of key 106 operates solenoid 83 and relay 107 which locks up over contact A and limit switch 89, and over contact C operates motor 168. Over contact B synchronizing pulses are applied from contact 88 to the centre of the output impedance 109 of the modulator 113. At the end of the travel of the carriage 79, contact 89 is opened and the circuits of motor 168 and relay 107 are broken. In a modification, Fig. 3 (not shown), the matter to be transmitted is supported on an endless loop driven by pulleys, the matter being retained by cleats and retaining clips. The movement of the loop traverses the image of the subject-matter-past an arrangement as shown in Fig. 1 and the cleats are utilized to open the circuit of the motor and simultaneously to apply a brake to arrest the feed of the sheet carrying the subject-matter to be transmitted.