Patent GB-733790-A (GB)
Title: Improvements relating to photographic type-composition
IPC: B41B21/26
Filed: 1952-06-09
Abstract: 733,790. Photographic type - composing. HIGONNET, R. A. E., and MOYROUD, L. M. June 9, 1953 [June 9, 1952], No. 14520/52. Class 98 (1). A matrix member for a photographic typecomposing machine carries a font of characters circularly disposed about an axis, a lens having its optical axis inclined to this axis and positioned to form an image of a selected character in the font upon the axis and in a plane perpendicular thereto for photographic reproduction upon a light-sensitive surface, and means for selecting characters of the font for formation of images thereof. The characters may be disposed either on a conical or a cylindrical surface, the planes of a selected character and its image intersecting in the principal plane of the lens. Preferably the characters are selectively illuminated, and a number of lenses are used to form images of illuminated characters. As shown, Fig. 4, a drum 6 carries seven fonts of characters 10-16. The drum is carried by a disc 32 with a boss 33 slidable along a shaft 36 to bring the required font into projection position. The shaft 36 carries a lens holder 20 with a number of evenly-spaced lenses 7. The optical axis NOP of a lens 7 intersects the drum 6 at N and the axis of shaft 36 at P, so that an image of a character at N may be formed at P. The light-sensitive surface 8 may receive the image at P, or the image may be projected on the surface by further optical means. The drum 6 is surrounded by an annular lamp 80, and the characters are selectively illuminated by cylindrical shutter elements such as 24. Each element has two sets of apertures, the apertures in one set corresponding to unapertured portions of the other set, and is movable axially between two positions in which one set of apertures or the other corresponds with the point N. The members are operated according to a code, so that for a particular character the members allow light from lamp 80 to illuminate the selected character only. In this respect, the shutter members operate in a manner similar to the shutter members described in Specification 733,789. If there is one lens 7 to each character, the aperture of the lense is restricted, and it is therefore preferred that the number of lenses is a submultiple of the number of characters, the lens holder 20 and the shaft 36 being rotatable. For example, there may be half as many lenses 7 as there are characters, and the shaft 36 may be movable between two positions, defined by stops 21, 22 and a cross-pin, by means of a rotary solenoid 23. The upper and lower case characters may be arranged alternately on the drum, so that the lenses correspond with upper case characters in one position and with lower case characters in the other position. Furthermore, the lens holder 20 may be arranged to move with one of the shutter members. The annular lamp 80 may be replaced by a number of lamps, and each such lamp may have a shutter so as to illuminate a single character. Since distortion occurs due to the inclination of the object and image planes to the optical axis, the characters must be given a corresponding distortion. The character drum is therefore produced as illustrated in Fig. 5. The drum 6 is mounted on a hollow shaft 6<SP>1</SP>. A master character is drawn on a large scale on a card 40 supported on a jig and illuminated by lamps 43. An image of the character is formed on a screen 44 by a lens 46 mounted in shaft 6. The shaft supports lenses 45 in the same way as the lenses 7; preferably the same lenses are used both for making the drum and for use in the machine. A shutter drum 47 has an aperture 50 which allows only one lens 45 to form an image on a light-sensitive surface on the inside of drum 6. The drum 47 is rotated step-by-step as by a ratchet mechanism to form images of successive characters. Image distortion caused by imperfect lenses can be eliminated as described in Specification 733,788. Specifications 685,310, 691,761, 691,762, 691,763 and 691,910 also are referred to.