Patent GB-665889-A (GB)
Title: Improvements in or relating to apparatus for reproducing letters by photographic methods
Inventor: CHEETHAM CLIFFORD
IPC: B41B17/10
Filed: 1948-07-28
Abstract: 665,889. Photographic type composing machines. MINISTER OF SUPPLY. Aug. 17, 1949 [July 28, 1948], No. 20112/48. Class 98 (i). Apparatus for producing a photographic copy of letters spaced in a line of text comprises several letter heads each consisting of a first portion bearing a letter and a second portion bearing an initial mark, a centre mark and at least one final mark, the distance between the initial and centre marks being a first fixed distance for each particular letter, each final mark being associated with a particular letter or letters and the distance between the centre and final marks being a particular second fixed distance determined by the letter or letters associated with the final mark, means for repeatedly positioning selected letter heads in an operating position, means for illuminating the letter head in the operating position, a light sensitive surface and associated photographic shutter, a sighting screen, optical means for projecting an image of the first portion of the operative letter head on to said surface where the shutter is open and for projecting an image of the second portion on to the sighting screen, means for operating the shutter to expose said surface, means for advancing said surface in two stages between the instants of photographing the letters on successive letter heads, at least one cursor cooperating with the sighting screen and movable into co-incidence with any of the index mark images appearing thereon, the cursor or cursors controlling the means for advancing the lightsensitive surface so that the distance by which said surface is advanced during each stage is determined by the position of the cursor or one of the cursors, the arrangement being such that if the light-sensitive surface is advanced between the instant of photographing a given letter and the instant of photographing the following letter by a displacement proportional to the particular second fixed distance of the given letter which is associated with the following letter and thus advanced by a displacement proportional. to the first fixed dis- 'tance of the following letter, a photographic copy is obtained on the light-sensitive surface of the two letters spaced with respect to each other. As shown in Fig. 1, the letter heads are in the form of rectangular negatives and are mounted on a rotatable transparent disc 21 so that the negatives bearing different letters in the same style are bounded by ,the same concentric circles whereas the negatives bearing the same letter in different styles extend radially from the axis 22 of the disc. The axis 22 is movable parallel to itself so that a letter in the desired style can be positioned in the light path from a source 29; by rotating disc 21, the required letter heads can be selected. Each letter head consists of a letter and several index marks 33-37. In the path of light from said marks a reflector 26 is placed so that an image of the index marks is formed on a sighting screen 31 by a lens 27; an image of the selected letter is formed by a lens 28 on a film 38 when a shutter (not shown) is opened. Movable across the screen 31 so that it may be positioned in register with any one of the index mark images 33-37 is a cursor 40 to which is secured an arm 49, pivoted at a variable distance from one end thereof at 46 and carrying at 47 a pair of pads, which lie one on each side of the. film and are spring urged together to grip the film 38. The pull of the springs is overcome so that the film is not gripped when solenoids which attract armatures fitted to the pads are energized. For this purpose, a contact is provided on cursor 40 and a second contact is provided on a mounting (not shown) which is moved by the cursor in such a way that during movement of the cursor in a forward direction across screen 31 there is a. slight gap between the contacts whereas the contacts touch and the solenoids are energized as soon as the cursor is allowed to return. In use, the disc 21 is rotated and/or axis 22 is moved so that the screen image of the index mark 33 on the letter head bearing the required letter registers with cursor 40, cursor 40 is moved so as to register with the screen image of mark 34 and thereby moves film 38 through the required distance, the film is exposed and, if the letter V which has been selected, is not to be followed by the letters A, I or W, the film is advanced further by moving the cursor into register with the screen image of mark 35. The cursor 40 then returns to its initial position, the film remaining stationary since the solenoids are energized during such movement. Thereafter, the next letter to be photographed is selected and the procedure repeated. When the letter following V is A or I, the cursor 40, after exposure of film 38, is only moved into register with the image of mark 37 whereas if the succeeding letter is W, the cursor is moved into co-incidence with the image of mark 36. When these operations have been completed, the film 38 is processed and dried and then placed with its exposed surface uppermost on a convex support and sprayed with a gum known under the Registered Trade Mark " Emultex ". The film is then left at normal room temperature for 12-16 hours before a prepared paper backing is applied to the gum, the adherence of this paper to the gum being less than that of the gum to the emulsion. The film is then turned over and the base thereof removed. After this operation, the film is cut around the various letters, the cut-out portions are peeled off the paper backing and then stuck on a sheet in the required positions. In a modification, two cursors are provided and the pull of the springs of pads 47 is overcome when current passes through a solenoid 66, Fig. 3. In this form there is provided a slidable mounting 53 having contacts 54, 55 and 56 for engagement with parallel conducting strips 50, 51 and 52 respectively fixed to movable bases 64, 65. Fixed to base 65 and set on the screen image of mark 34 of the selected letter head is a cursor 58 and a second cursor 59 is fixed to base 64 and set on the screen. image of the appropriate mark 35, 36 or 37. The position of the screen image of mark 33 is set on the mechanical zero position 57 of the mounting 53. The mounting 53 performs two journeys from position 57 to a position 60 during the presentation of each letter. This mounting and the strips 50-52 are connected in circuit with the solenoid 66 through switches 62 and 63 which rotate in synchronism so that the circuit is completed via lead 67 during all return journeys of mounting 53 and so that contact 56 and strip 52 are in circuit during the first forward trip and contacts 54 and 55 and strips 50, 51 are in circuit during the second forward trip of the mounting.