Patent GB-1151354-A (GB)
Title: Improvements relating to Photocomposing apparatus
Inventor: ASTLEY EDWARD THOMAS
IPC: B41B27/00
Filed: 1965-08-10
Abstract: 1,151,354. Photographic typecomposing apparatus. CROSFIELD ELECTRONICS Ltd. 1 Aug., 1966 [10 Aug., 1965], No. 34190/65. Heading B6W. In a photocomposing apparatus a set of matrix characters on a carrier pass through an exposure zone, a light deflector in the optical path between the exposure zone and a light sensitive surface moves continuously so that a light beam from a fixed point in the exposure zone would sweep along a line of the light sensitive surface, and timing means are provided responsive to the positions of the matrix carrier and the light deflector to illuminate a required matrix character by a light flash when the character is in a position within the exposure zone such that it will be exposed on to the required portion of the light sensitive surface, taking into account the position of the light deflector, the apparatus further including means for restricting the exposure flash to that portion of the matrix containing the required character. In a preferred embodiment the matrix carrying drum 17 rotates about cathode ray tube light source 18. Lens 19 controls character magnification and lens 20 supplies a parallel beam to mirror 21 which is mounted on continuously driven carriage 23 such that the area of film on to which a character can be exposed from drum 17 moves across a line of film. Character signals from tape reader 10 are processed by memory 11 which can store at least one line of text, arithmetic logic unit 9 which effects a line justifying computation, and width store 15 which stores the interword spaces calculated at 9. During an exposure cycle the next 6 characters are set up in identity information registers 12, the data stored representing the position of drum 17 to give the required character, and the required position of each of these characters in the line is supplied from unit 9 to line position registers 16. Carriage pick-up 30 supplies signals indicative of the actual carriage position to comparator 32 which compares these signals with those from the registers 16. Pick-up 40 indicates the actual drum position to comparator 42 which compares this information with that in the registers 12. A flash timing circuit 43 receives information from comparators 32 to 42 and generates a flash pulse when the drum and mirror are in a position to give a desired character at a desired position. If, when a required character is in the exposure zone, the mirror is not quite correctly placed compensation is effected by timing the flash to occur before or after the character crosses the optical axis of the system. For an exposure the circuit 43 generates a signal representing the position of the required character in the exposure zone and applies this signal to the X- shift conductor 45 to generate a light spot immediately behind the required character. As characters are exposed, new ones are immediately set up in the registers. Drive 24 may have a variable speed dependent upon the number of characters exposed in a previous drum revolution to obtain a maximum operating speed. A turret of lenses is provided for variable magnification.