Patent GB-544411-A (GB)
Title: Improvements in or relating to keyboard controlled photographic recorder
IPC: B41B19/01
Filed: 1940-08-27
Abstract: 544,411. Indicating apparatus. INTERNATIONAL BUSINESS MACHINES OORPORATION. Aug. 27, 1940, No. 13532. Convention date, Nov. 1, 1939. [Class 40 (i)] [Also in Groups XX and XL] A recording apparatus comprises means for generating electrical components representative of the outlines of a set of characters, an electronic character-displaying device adapted to display the character or characters represented by the generated electrical components, means for photographing the displayed character, and a keyboard for selecting the character to be displayed. As described, the apparatus forms a typewriter substitute, the operation of the keys of a normal keyboard causing the corresponding character to be momentarily formed in succession on the screen of a cathode-ray tube and to be photographed to produce a film record. The apparatus comprises three main units, an emitter unit comprising a separate emitter for each character which when connected to the deflecting plates of the cathode ray tube applies varying voltages which cause the cathode ray beam to trace out. the corresponding character on the screen, a keyboard unit the keys of which connect the corresponding emitter to the cathode-ray tube, and a recording unit comprising the tube and camera. The units may be separated and accurately controlled by means of connecting. cables. One keyboard may control a number of recording units for making duplicate records concurrently, and one emitter unit may be common to a number of keyboards and recording units. The emitter unit, Figs. 12, 14, comprises shafts 212 driven by a motor 211 and carrying opaque discs 213, one for each character, eachprovided with two variable-width tracks 213X, 213Y which as the disc revolves vary the light passing from lamps 215 to two photo-electric cells 218X, 218Y. A separate valve amplifier. circuit for each photo-electric cell produces corresponding potential variations in the deflecting plates of the cathode-ray tube when connections, are made by the corresponding key of the keyboard unit, the tracks 213X, 213Y controlling, respectively the horizontal and vertical movements of the beam which together cause it to trace the desired character on the screen. In order that the tracing beam may be suppressed during parts of the rotation of the pattern disc when the beam is not moving, or is "jumping" between two points of the image, a commutator (not shown) rotating with each disc completes at such times a circuit which increases the negative bias on the intensity control grid of the tube. The recording unit, Figs. 1, 3, 5, shown as mounted at the back of the keyboard unit although it may be remote from it and connected by wires, comprises a cathode-ray tube 40 and a camera 41 focused on the screen 100 of the tube. The perforated film passes from a supply spool 24, under a sprocket 57, through a gate 58 with a sprocket 71, and over a sprocket 60 to a take-up spool 61. After a line has been recorded, the film is fed for recording of the succeeding line by energization of a magnet which causes a pawl (not shown) to advance a ratchet wheel which through gears drives the sprockets 57, 71, 60 the take-up spool being belt-driven. A knob 92, Fig..l, carrying a pointer co-operating with an adjustable index plate 93 is driven through gears from the spindle to indicate the number of lines recorded. The knob serves also for feeding the film manually when loading the camera. The character on the.screen 100 is projected through a slot 102 in the gate 58, Fig. 6, and the characters are spaced by horizontal movements of the gate, which is slidably mounted on rods 103, the sprocket 71 being also slidable with it on a squared driving shaft. These movements are produced by a forked arm. 106 on a shaft 107, which engages a pin on a rod 104 secured to the gate. The shaft 107 is swung by. a telescopic arm 111, 111a, Fig. 1, pivoted to a rack 116 which, at each operation of a character key or the spacing key, is allowed to move one tooth to the right as seen in Fig. 1 by means of an electromagnetically operated double-pawl escapement 42, the rack movement being produced by a spring-tensioned tape 124. The return of the rack at the'end of each line is effected by a tape 123 which is wound on a drum 144 when the latter is clutched to the shaft of a motor 122 by a clutch operated by a. lever 150, which is rocked through a toggle linkage operated by a solenoid 162. At the end of the return movement a lug 127 on the rack opens switch contacts 128 to deenergize the magnet so that the drum 144 is de-clutched. The lens shutter is operated to expose each character by a solenoid (not shown). A switch is opened by an arm 350 bearing on the film on the supply spool when the film is exhausted, de-energizing the apparatus and extinguishing a signal lamp 256. Fig. 10 shows a section of the keyboard unit. On depression of a character key 24b a bell-crank 15 operated from the key lever 13 closes contacts 17, 18, 19, the first and last of which connect the two amplifiers of the corresponding emitter to the :deflecting plates of the tube 40, whilst the .switch .18 connects the corresponding commutator to the intensity control grid for suppressing, the beam at the requisite times. Immediately after operating these switches, the key lever depresses hinged bail 33 common to all the levers the movement of this bail opening a contact 36c and closing a contact 36b. The contact 36c opens a circuit normally supplying a high negative bias to the intensity, control grid, and contact 36b closes a. circuit which energizes the shutter-operating magnet of the camera, and the. magnet operating the escapement 42. The character image formed on, the screen is thus photographed, and when the key is released, the de-energization of the escapement magnet allows the rack to move one position to the right, so traversing, the film horizontally to receive the.next character.. The key is retained depressed.for a.complete cycle of operations by a hinged locking bar 26 which engages a hook 25 extending from the key lever. The bar is rocked to release the key by a magnet 31 energized by a rotary, contact member 163, Fig. 3, which is clutched to the shaft of the motor 122 when a magnet 173 is energized, by closure of the contacts 36b and makes nearly a complete rotation before energizing the magnet 31. The spacing key and line spacing keys close contacts energizing the magnet of the escapement 42 and film-feeding magnet respectively. The capital key 20CA when depressed closes the circuit of a relay to operate contacts which change over the connections from the switches 17, 19, to the amplifiers of emitters generating capital letters. Alternatively, the small characters may be enlarged to serve as capitals, the same emitters being employed, but the potentials of the deflecting plates of the cathode ray tube being increased when the capital key is depressed to increase the size of the image.