GB612353A - Improvements in or relating to calculating devices - Google Patents

Abstract

612,353. Electric calculating machines. NATIONAL CASH REGISTER CO. May 20, 1946, No. 15180. Convention date, June 25, 1943. [Class 106 (i)] A calculating device includes a driven member adapted to be moved by a driving means through a plurality of selectable positions, and selectively operable electrical control means directly carried by the driven member to control the positioning and stopping of the driven member in any selected position. For each denomination, ten equally-spaced gas discharge tubes 51 are mounted on a plate 37 adapted to be rotated through a friction disc 35 by a reversible motor 34. The potential normally applied to the tubes is insufficient to initiate conduction although sufficient to maintain one tube conducting if it has already been started. Depression of a key 45, Fig. 1, closes corresponding contacts 108, 140-147, Fig. 4, to apply a temporary boost in potential to whichever tube is in contact with the corresponding firing contact " 1 "-" 9 " spaced round a fixed commutator, Figs. 2, 4, whereupon this tube fires while the potential applied to the tube at the registering position, which was previously conducting, is momentarily depressed through a series of condensers 62, so that the latter tube is extinguished. This drop in potential is conveyed by contacts 60, 72 to the grid of a vacuum tube 46 which also becomes non-conducting to de-energize a solenoid 43, whereupon a pawl 41 is retracted by a spring to allow the plate 37 to be rotated clockwise a number of steps corresponding to the key depressed, by the friction disc 35 and the motor 34. The rotation stops when the conducting tube 51 reaches registering position behind a window 44 and its contact 60 engages the contact 72 to raise the grid potential of the tube 46 to re-engage the pawl 41 with the plate 37. Tens transfer. As the disc 37 passes from 9 to 0, a contact 86 engages a fixed contact 87 to energize a solenoid 301 which applies a pulse to the firing contact " 1 " of the next higher denomination to add unity. Subtraction. Depression of a subtraction key S reverses the motor and shifts a set of contacts (Fig. 5, not shown) so as to apply potential to the firing contact corresponding to the tens complement of any key depressed. Transfer occurs as the " 0 " tube passes from registering position in a counterclockwise direction through the contacts 86, 87. Zeroizing. The register is cleared by depression of a key Z which applies potential through a ring 80 and a conductor 130 to the zero tubes 51 of all denominations so that these tubes fire and are stepped to registering position in the manner already described. Keys. To ensure only a momentary pulse being applied to the selected firing contact even if a key is held depressed, contacts 200, Fig. 6, are closed by a nose 204 on the key stem and open again when the key is fully depressed. Indicating. The tubes 51 are capped by transparent discs 53 bearing the appropriate numerals. Operation. A number is entered by depressing the appropriate keys one at a time.