Patent GB-519395-A (GB)
Title: Photoelectric telegraph transmitter
IPC: H04L17/14
Filed: 1938-10-21
Abstract: 519,395. Photo-electric telegraph transmitters ; feeding sheets. CREED & CO., Ltd. Oct. 21, 1938, No. 30527. Convention date, Dec. 20, 1937. [Class 40 (iii)] [Also in Group XVI] A photo-electric telegraph transmitter for transmitting signals from sheets having multiple code marks arranged in successive lines is arranged to scan a line of code marks while the sheet is at rest by means of a stationary lamp and a stationary photo-electric device in conjunction with a movable scanning device which is the sole means of determining the sequence of scanning. Belts 49, Fig. 1, co-operate with the edges of the sheet 53 for feeding the sheet the space of one line at a time between a fixed lamp 116, Fig. 5, and a photo-cell 122. In the interval, while the sheet is at rest, a pair of perforated tapes 76, 87, Figs. 1 and 14, move in the direction of the line for scanning all the code marks of the line in succession. In the apparatus shown, each code mark has a possible maximum number of six transparent or opaque spots transverse to the line, the tape 76 has transverse slots 78 extending over the whole range of the six spots of the code, and the tape 87 has sets of six longitudinal slots 89 stepped to come in operation successively. While the sheet is at rest and the tape 76 also at rest with one slot 78 over a code mark, the tape 87 moves to cause each slot 89 in turn to come in register with the slot 78 and one of the spots of the code, thereby causing impulses to be transmitted corresponding to the code mark. When one code mark has been scanned, the tape 76 is moved a step to shift the slot 78 to the next code mark in the line ; and the tape 87 again moves and scans the code mark by a second set of slots 89. This operation is repeated until the whole line is scanned, then the tapes are stopped while the sheet is moved one step to bring the next line in position for scanning, after which the tapes are set in operation again, the next slot 78 of the tape 76 then coming into operation. When the complete sheet has been scanned, it is ejected and a fresh sheet is supplied from a magazine and scanned in its turn. In addition to the impulses produced by the photo-electric scanning of the sheet, additional impulses are produced, at the completion of the scanning of each code mark, by an additional photo-electric cell 124, Fig. 3, when an aperture 127 in a disc 126 comes between the cell and a lamp 123, the disc 126 being driven by the mechanism which drives the tapes. Scanning-tapes mechanism.-The tapes 76, 87 are in the form of endless belts. The tape 76, Figs. 1 and 2, extends between an idler sprocket wheel 73 on the left to a driving sprocket wheel 67 on the right. The tape 87 rides over the tape 76 and extends between idler sprocket wheel 84 and driving sprocket wheel 81. The spindles of the idler sprocket wheels 73, 84 are mounted in brackets 71, 70 which are adjustably fastened to the bed of the apparatus. The driving sprocket wheels 67, 81, Figs. land 3, are rotatably mounted on a sleeve 63 loose on a shaft 31 driven by gearing 29, 28 from a shaft 24 itself driven by gearing 27, 23 from shaft 22 of electric motor 21. A gear wheel 56 fast with shaft 31 is in mesh with a gear wheel 91 loose on a shaft 92 below the shaft 31 ; a gear wheel 101 fast on shaft 92 is in mesh with a gear wheel 102 loose on sleeve 63 and carrying a pawl co-operating with a ratchet 83 fast with the sprocket wheel 81 ; and a cam 105 on shaft 92 fits in a slot in a lever 107 pivoted on shaft 31 and carrying a pawl co-operating with a ratchet 69 fast with sprocket wheel 67. When clutch elements 94, 93 are coupled together, rotation is transmitted to shaft 92, sprocket wheel 81 of tape 87 is driven continuously by gearing 101, 102, and sprocket wheel 67 of tape 76 is driven intermittently by cam 105. One revolution of shaft 92 causes tape 87 to scan one code mark, tape 76 is then moved one step by cam 105 to bring slot 78 on next code mark, and next revolution of shaft 92 scans next code mark, and so on until the whole line is scanned. At the end of the line, a signal causes a clutch member 58 on sleeve 63 to engage clutch member 57 on shaft 31, whereby sleeve 63 is rotated one revolution. Arms 181, 182 on the sleeve between the sprocket wheels 67, 81 then engage lugs on these sprocket wheels to drive the tapes to the starting position for the next line. This corresponds to " carriage return " operation in a printer. Over travel of the sprockets 67, 81 is prevented by lugs 193, Fig. 4, thereon coming against shoulders 197 on levers 194, which are connected by a link 199 to the throw-out lever 97 whereby the shoulders 197 are placed in the path of the lugs 193 when the clutch 93, 94 is disengaged. At this stage, the sheet is also moved the space of one line in readiness for the scanning of the next line. Line-feed mechanism.-The edges of the sheet 53, Fig. 1, are engaged by pins on belts 49 extending between idler sprockets 47, Fig. 5, and driving sprockets 44, which are fast on shaft 42 coupled by gearing 41, 39 and a spring loaded friction clutch to a shaft 37, Fig. 3, coupled by gearing 36, 34 to the shaft 31, which as described above is driven by the motor 21. A ratchet 218 on shaft 42 is normally engaged by a pawl 217 preventing rotation of shaft 42. When the scanning of a line is completed, pawl 217 is withdrawn from ratchet, and pawl 216 on same pivot 219 is brought against the ratchet, this allows partial rotation of shaft 42 until pawl 216 stops ratchet. Immediately after this, the pawls are rocked back, allowing the ratchet to complete one step, when it is again stopped by the pawl 217 engaging the next tooth of the ratchet. This step rotation of the shaft 42 moves the sheet 53 forward the space of one line. Sheet storage and delivery mechanism.-A number of sheets 53 are piled one above the other in stepped formation in an inclined magazine 261, Fig. 8 and 9. The sheets are held up between rollers 292 and sprocket wheels 273 fast with a ratchet 276 locked by a pawl 279 on an arm 278 rockably mounted on the shaft 272 of the sprocket wheels. The arm 278 is connected by a link 282 to a lever 283 pivoted at 284 and having its free end in the path of a pin 289 on a sprocket 47. At each revolution of this sprocket, the pin 289 rocks the lever 283, causing the ratchet 276 to rotate one step whereby the bottom edge of the bottom sheet in the magazine comes under a bail 264 pivoted at 263 and integral with an arm 266 bearing on a cam 267 on the shaft 48 of the sprocket 47. The notch of the cam 267 then allows the bail 264 to deflect the bottom end of the sheet into the path of a claw 269 on the belt 49, and the sheet is extracted by this claw from the magazine and carried on by the belt. A grooved roller 294 on the same spindle as one of the rollers 292 allows a roller 296 to move up when the magazine is empty of sheets, whereupon a lever 297 carrying the roller 296 allows contacts 301. to open to cause the operation of the transmitter to stop if and when no sheet is on the belts 49 as explained below. Similarly a roller 306 moves up into a grooved roller 302 when no sheet is on the belt 49, whereupon lever 307 carrying roller 306 allows contacts 311 to open. This movement of the lever 307 can only take place in one position of the shaft 48 when a single depression in a cam 313 on this shaft comes below a pin 312 on the lever 307. The opening of contacts 311 causes the cessation of the scanning operation as explained below. The feed pawl 279 may be put out of action by a cam 366, Fig. 13, provided with a handle 368 and formed with two notches for engagement by a catch 369 on the feed pawl 279 to retain the device in either operative or inoperative position. This disabling of the feed pawl suspends the feed of the sheets stacked in the magazine and permits a special sheet to be inserted by hand over the rollers 292 and under the shaft 263 to be taken up by the belts 49. A knob 371 is provided on the end of the shaft 272 for manual operation backward or forward when the feed pawl is inoperative. Selector mechanism.-A selector mechanism, Fig. 7, responsive to the signals and serving to control the transmitter is associated with the shaft 92 and comprises a cam assembly 139 on shaft 92, a selector magnet 131, with an armature lever 133, a selector lever 134, sword levers 137, T-levers 138, intermediate levers 141, and slidable notched code bars 142 co-operating with function bars 144, 201, 206, 234 and 236. The function bars 144, 201 control the "carriagefeed" function ; the function bars 206, 234 control the "line-feed" function ; and the function bar 236 controls the delivery of the message page. The function bar 144 is mounted by a slot on a pin 146, Fig. 5, and is urged upwards and forwards by a spring 148. When the slots in the code bars 142 allow the function bar 144 to rise within reach of a bail 151, this bail engages a notch 161 in the function bar 1 and, at the end of one revolution of shaft 92, the bail is rocked counter-clockwise (looking at Fig. 5) by linkwork operated by a cam 156 on shaft 92. This drives the function-bar to the left, and a shoulder 171 thereon bearing on the arm 167 of a bell crank lever 166 rocks that lever clockwise. This causes a throw-out lever connected to a link 172 to allow clutch 57, 58, Fig. 3, to engage to cause sleeve 63 to be rotated to perform the function equivalent to "carriage feed " as aforesaid. At the same time, a bail 164 is rocked clockwise by the bell crank lever and operates a throw-out lever causing clutch 93, 94 to disengage when shaft 92 reaches its rest position with aperture 127 of disc 126 in line with lamp 123 and photo-cell 124. At the end of the revolution of sleeve 63, a cam 186, Fig. 4, thereon rocks a lever 187 connected to a link 191 ; and a projection 192, Fig. 15, on this link depresses function bar 144 away from bail 151. whereupon the function bar moves forward again in re