GB1344544A - Calculating device - Google Patents

Abstract

1344544 Calculating device C SIANTONAS 28 Jan 1971 3356/71 Heading G4B In a calculating device of the type including two scale-bearing tapes, disposed side-by-side and wound on two respective pairs of reels, and a drive mechanism for selectively moving either tape back and forth between its carrier reels or for moving both tapes simultaneously and at the same speed past a fixed datum line, a movable pointer is provided for use in conjunction with equally-spaced marks provided along the length of each tape for checking that no relative longitudinal movement between the tapes has occurred during simultaneous movement thereof and for enabling a correction to be applied if any such relative movement is discovered. As shown, each tape TP1 or TP2 passes between a corrugated-rubber-surfaced roller R1 or R2 and a transparent sheet 10 or 10A, spring- urged towards its respective roller. Either roller may be rotated to move its associated tape by means of a corresponding knob Kn 1 or Kn 2 . Alternatively, a nut Nt may be tightened to draw high coefficient of friction surfaces Ds together for simultaneous driving of the tapes. Rotation of the rollers R 1 , R 2 is transmitted via pulleys Pw and belts B to the respective pair of reels 1 and 2, 1a and 2a, the arrangement being such that the belts will slip on the pulleys if the speed at which the tapes are driven does not correspond to the required winding speed at the reels. The equally-spaced marks are shown along the outer edges of the tapes in Fig. 4. The adjacent inner edges bear logarithmic scales. The datum line Lu Fig. 1 (not shown), is marked on the transparent sheets 10, 10A. The pointer Pt is slidable along an edge of the upper half of the device casing, Fig. 2. Before simultaneous movement of the tapes, a mark on one of the tapes is aligned with the datum line and the pointer Pt is aligned with an adjacent mark on the other tape. After a simultaneous movement, a similar relationship should exist with an adjacent pair of marks on the part of the tapes now located beneath the datum line. If this relationship is not found, nut Nt is loosened and a correction applied. A frame 15 may be releasably secured to the device at Px, Gx and may contain either a roll of paper, withdrawable through slot Sl for making written calculations, or batteries for powering either an electric motor drivingly connected to the rollers R 1 , R 2 or a light located within the device.