Patent GB-739600-A (GB)
Title: High speed facsimile transmitter
IPC: H04N1/06
Filed: 1953-02-20
Abstract: 739,600. Copying-telegraph transmitters. CREED & CO., Ltd. Feb. 20, 1953 [Feb. 29, 1952], No. 4788/53. Class 40 (3). Facsimile transmitting apparatus comprises a cylinder having a transparent wall portion through which a rolled sheet may be optically scanned and an outer end through which the rolled sheet may be inserted so that the sheet extends longitudinally along the inside of the transparent wall portion of the cylinder, a bearing structure supporting the other end of the cylinder and including means for its rotation, a gate member mounted in a fixed support adjacent the outer end of the cylinder and incorporating a bearing structure forming, when the gate is closed, a rotatable bearing for the cylinder, the bearing structures providing an invariable axis of rotation for the cylinder. The scanning operation for transmission is effected by a mechanism traversed parallel to the axis of the rotating cylinder. As shown in Fig. 16, the glass drum 26 has a tightly fitting flange 28 having a hub 30 secured by screws 34 to the shaft 32 of the motor 24. An insulating plate 36 secured to supporting member 22 carries the stator section 38 of a tone generator and a spaced rotor 42 is provided with a cover 44 to eliminate or reduce the audible siren effect. The right-hand end of the cylinder has a flange 29 with a tapered portion 29a coacting with a bearing plate 62 attached by screws 60 to a bearing plate 58 mounted on a hollow shaft 56 rotatably mounted in ball bearings 54, 55 in a housing 52 carried by a gate member 50 rotatably supported by a hinge 47a on a support member 23 located near the end of the cylinder. A rubber-covered bumper 246 serves as a stop for the gate 50 in the open position. In the closed position of the gate 50 the housing 52 forms the bearing for the right-hand end of the drum, and a catch 66, 66a engages a detent member 68 to hold the gate closed. Switches 70, 72 are actuated by the closure of the gate and a magnet 74 is energized to raise a lock pin 78 below the thumb catch 66a. A hollow part 87 secured to an end cap 84 carries a housing 90 for a photo-cell 92 which is illuminated through a gap between the ends of the blank to produce phasing impulses at the beginning of a transmission, as described in Specification 739,594. The photo-cell 106 which receives the picturescanning light beam is mounted in a housing 102 provided with a projection tube 94 carrying a lens. The scanning carriage 122 is mounted on rails 110 and 112 and is advanced by a threaded half nut 134 engaging a lead screw 114, and normally held in engagement by a spring 142. The half nut 134 is disengaged from the shaft 114 by a bar 146 connected to a lever 150 actuated by an electromagnet 152, and the carriage is returned to its normal position by a band 166 associated with a governor-controlled spring drum 170. The start position of the scanning carriage is determined by an adjustable rod 182 carrying an elastic buffer 184 engaging a lever 194 on the underside of the carriage which operates a switch 198 to deenergize the magnet 152 to allow the half-nut to engage the lead screw. The end-of-message position is determined by an adjustable carriage 208 carrying a pointer 209 and mounted on parallel rails 210. A plate 212 mounted on a vertical plate 214 on the carriage 208 carries two cams 220 provided with oppositely directed extensions 223, 224 and located on opposite sides of a rod 226. The scanning carriage carries two pins 234, which in the predetermined end position engage the extensions 223, 224 to rock the cams clockwise to grip the rod 226 which is moved forward with the scanning carriage and operates a switch 228 which opens the circuit of the motor and energizes the solenoid 152 to allow the scanning carriage to return to its starting position. A reject push button 224, indicated in Fig. 18, enables transmission to be stopped at any position. Circuit arrangement. Switches 70, 72 occupy the positions corresponding to the gate 52 being open and are moved to the left when the gate is closed, the switch 70 being such that the transmitter is prevented from restarting until the gate has been swung open and reclosed, if the thumb latch on the gate should be released accidentally. In the normal condition with the gate open, relay 255 is operated and locked up. When the message is to be transmitted and the gate has been closed, relay 254 operates and locks up. Armature 2 connects a.c. the supply to the motor 24, and its contact 3 operates relay 252 after a time delay, e.g. of 2 seconds, during which the phasing signal is transmitted, and at its contact 2 the a.c. supply is connected to the line feed motor 118. Relay 252 also opens the circuit of relay 255 which releases and at contact 3 prepares a circuit for solenoid 152 which is not energized since the circuit is open at the actuated contact 3 of relay 254. Also, the armature 4 of relay 254 in its normal position causes a circuit 270 to transmit a stand-by signal and in the actuated portion to transmit the phasing signal. Relay 252 has a transfer armature 4 which on the operation of the relay after the 2-second interval switches the circuit 270 to the transmission of the message signals. At the end of the message the rod 226 opens contact 230 so that relay 254 releases and also releases relay 252. At contact 3 solenoid 152 is energized so that the scanning carriage is returned to its starting position. The transfer circuits at armatures 4 of relays 252, 254 are returned to normal and the release of relay 254 also de-energizes gate-locking solenoid 74. When the carriage reaches its start position the switch 198 is opened and solenoid 152 released so that the half-nut is returned to operative position. The operation of the reject push button 244 produces the same results as the actuation of the end-of-message switch 230. Specification 717,726, [Group XL (c)], also is referred to.