Patent GB-723127-A (GB)
Title: Improvements in or relating to type-composing apparatus
IPC: B41J19/64
Filed: 1953-01-12
Abstract: 723,127. Photographic type - composing. HIGONNET, R. A. E., and MOYROUD, L. M. Jan. 12, 1953 [Jan. 11, 1952], No. 918/52. Class 98 (1). [Also in Group XVI] A register for photographic type-composing apparatus comprises a rotatable drum having a surface capable of sustaining different magnetic states in discrete areas, recording means for pro - ducing a selected magnetic state in areas of the drum surface in accordance with a code representative of a character to be registered, and reading means for detecting magnetic state cf the areas. As shown, the keyboard K of a conventional typewriter is provided with permutation bars C controlling a set of seven contacts, a different combination of contacts being closed for each character. The closed contacts apply electric impulses to seven leads in two groups, a group A of four and a group B of three. The group A leads are connected to the contacts corresponding to the first four elements of a seven-element code, these elements being used to indicate the width of a character on the binary system. The contacts connected to the group B leads correspond to elements which differentiate between characters of equal width. The A leads are connected to a line length counter L which totals the widths of all the characters. The keyboard is also connected to a space counter S which counts the number of interword spaces in the line. Each of the seven leads is connected to a button 4 on a rotary switch 2, of which the arm 12 connects each button in turn to a conducting ring 20. The arm 12 is mounted on a shaft 8 driven by a motor 6 and also carrying a drum 10. A recording coil 30 is mounted on the typewriter platen 34 and is moved parallel and close to the drum 10. When a key is depressed, the closed contacts energize the coil through the rotary switch 2 and a writing amplifier W to magnetize the magnetic surface of the drum along a ring 32 in spots corresponding to the code combination of the selected character. When all the characters of a line have been registered, the line length counter L and the space counter S operate a justifier J which determines the spacing of the characters in the printed line. If a wrong character is recorded, the platen of the typewriter is brought back to the position of the faulty character. This brings coil 30 opposite the ring 32 where the corresponding code combination has been stored. A reading coil mounted with coil 30 is connected by lead 36 to a reading amplifier 38, from which pulses corresponding to the width indication are passed through a rotary switch 42 driven by shaft 8 to the line counter. The arrangement is such that the pulses are inverted and passed by leads 44 to the line length counter L, thus in effect subtracting the width of the erroneous character. An erasing circuit 48 is energized, and excites a coil mounted with coil 30 to erase the erroneous combination. The key for the correct character is then struck, registering the character in its proper place and its width in the line length counter. The completed line is read by a reading carriage 52 carrying a reading coil 54 and an erasing coil 56. Coil 54 starts opposite the first ring 32, and impulses corresponding - to the code of the first character in the line are generated therein and passed through a reading amplifier R to a rotary switch 64, which is similar to switch 2 but turned with respect thereto through an angle equal to the angular separation between coil 30 and coil 54, which are conveniently on diametrically opposite sides of drum 10. The impulses energize holding relays H which in turn operate a decoder D to effect, through a projection device P in a photographic type-composing machine, the projection of the character. A spacing mechanism is also operated which, together with the justifier J moves the film carriage F to space the characters to produce a justified line. The coil 56 is connected to an erasing circuit 70 so that as each character is read, the previous one is erased. The recording coil 30 may record a new line while a previously recorded line is being read. The coils need not move at the same speed provided coil 30 is prevented from catching up with coil 54. The rotary switches may be replaced by equivalent devices. For example, the drum may carry a ring of magnetized spots at one end generating impulses applied to an electronic gating circuit to connect the leads to the recording and reading coils as required.