Patent GB-715480-A (GB)
Title: Record carrier for the recording of electronic images, and method of and apparatus for producing the same
IPC: G03B17/50
Filed: 1951-07-31
Abstract: 715,480. Electron beam apparatus. INGLESBY, J. C. VREDENBURG-, and FRIES, G. July 31, 1951 [Oct. 6, 1950], No. 18117/51. Class 39(1) [Also in Groups XXXVIII and XL(b)] An electron sensitive record carrier for use in the atmosphere comprises a transparent or translucent plate an ionic crystal layer applied to one surface of the plate and a transparent or translucent protective layer covering the ionic crystal layer in an air tight manner, at least one of the outer layers being pervious to cathode rays and the ionic crystal and protective layers being applied in vacuum, preferably by evaporation. In manufacture the carrier film is unwound from spool 67 by starting motor 6 which energizes toothed drum 18 through the couplings shown. The film passes first over guide roller 42 and through passage 43 into the pre-vacuum chamber 45 which is evacuated by motor driven vacuum pump 47 to 10<SP>-3</SP>mm. Here it is subjected to a glow discharge between electrode 49 and insulated high voltage roller 48 so as to remove traces of gas and impurities therefrom. It then passes over roller 50 and through passage 51 into high vacuum chamber 52 at 10<SP>-6</SP> mm.. roller 50 being earthed to casing 53 so as to remove residual charge from the film. The image layer is deposited by evaporation from tantalum or molybdenum vessel 55, the powdered material being fed to the vessel by dredging and conveying mechanism from a storage reservoir, Fig. 3 (not shown). Mechanism controlled by a hand wheel, screw spindle and nut and including a friction wheel displaceable on a friction disc regulates the rate of feeding of the material to the vessel 55. The adjustments maybe automatic. Vessel 55 is heated by eddy currents produced by winding 61 which is mounted on a holder 62 movable up and down by hand wheel 63 and screw spindle 64, to control the temperature and rate of evaporation. A second evaporation vessel 100 holds the protective layer material the supply of which is regulated in a similar manner. Alternatively the protective layer such as a cellulose varnish is supplied from reservoir 70. The varnish runs on to a layer of water passing along channel 68. The flow of water in a closed circuit 73 is maintained by gear pump 13. A screwed spindle 76 and rotatable mounting 75 allows for variation of the inclination of channel 68 and hence of the rate of flow of the water. While in channel 68, the varnish spreads and partly dries but is prevented from sticking to the sides by energizing a small supersonic generator (not shown). The partly dried varnish film is picked up by drum 39 and passed as a self-supporting strip over roller 25 then via passage 77 to prevacuum chamber 78 and through passage 79 to roller 14 beneath which it is placed on top of the image layer. The record carrier then passes over rollers 81, 82, 83 and the edges of the varnish layer are sealed to the film 1 by an electrically heated roller 88, or by high frequency heating. It then passes through a passage 84, pre-vacuum chamber 45 and passage 87. Spring biased roller 82 keeps the carrier taut over curved track 85 which may be replaced by a roller with a flywheel. The edges of the varnish layer are painted with acetone supplied from reservoir 89 through two wicks 90 to ensure the air tightness of the seal. After passing through further rollers the completed carrier film is wound on spool 10; constant speed drum 93 has therein a photocell 94 illuminated by light source 95. The quality of the process may be tested and/or controlled by recording a sound or tone on the film by means of cathode ray tube 96 the intensity modulated beam of which passes out through Lenard window 98. The record is then reproduced by means of photocell 94 the output of which is fed to an amplifier and loudspeaker. The reproduced signal may be used for automatically controlling the stages of the manufacturing process, e.g. the layer uniformity and rate of evaporation and cessation of the signal can be used for automatically stopping the apparatus. The driving mechanism for the rollers and conveyor mechanism is described in detail, mainly with reference to Fig. 3 (not shown). To make short lengths of carrier film, e.g. of single picture size. the protective film may be formed in narrow transverse bands across the film, sealed thereto and the film severed to remove the unprotected film parts. The sealing is effected by heating ribs of a roller or by using the ribs as high frequency electrodes. The carrier film may cooperate with a glass film sensitive to irradiation by ultra violet light and X-rays; the glass film which may be coated on one or both surfaces with cellulose acetate to render it less liable to break may or may not form the protective layer. In the former case a negative image is recorded on the active layer, the glass layer is illuminated with ultra violet light for a long period so as to record a positive image thereon, and on heating the positive image is developed while the negative image is removed. The glass layer may be formed by evaporation on a carrier whether or not it serves as the protective layer. The film may be used for (a) sound recording, (b) picture recording, (c) reproduction printing especially for producing printing plates for multi-colour printing. This is effected by projecting the colour picture through colour filters on to the photo cathode of an image converter, the electron images being recorded on the film, (d) the electronic recording of electrically controlled matrix images in phototype setting machines, (e) electromagnetic and electrostatically focused electron microscopes, (f) image converters for infra-red and X-rays, (g) as an intermediate member for large screen television projection. The film is scanned with a modulated electron beam and a light beam projects the image on to a large viewing screen. For colour or stereoscopic pictures the picture components are recorded successively on different areas of the film and projected simultaneously through coloured or polarizing filters. The film may move in a closed path, the picture being erased by heat or by an electrostatic field and the film being fed back for recording of another picture. The active layer of the film is an alkali or alkaline earth halide. e.g. of Na, K, Li, Ca or Sr of a thickness of 10-<SP>2</SP>-10-<SP>4</SP> mm. or less and the film is arranged outside a cathode ray tube. The protective layer may be of cellulose, e.g. a cellulose varnish, quartz, aluminium oxide or copper, and the carrier may or may not be of the same material. Either the carrier or the protective layer may be electron pervious.