GB534399A - Improvements in or relating to apparatus for plotting and reading graphs - Google Patents

Abstract

534,399. Plotting and reading graphs. MILLS, R. A. Dec. 7, 1939, No. 5448. [Class 106(i)] In apparatus for making and reading graphs of the Cartesian co-ordinate type, a pen or its equivalent is moved relatively to a record paper carrying table to produce or trace the graph, the ordinate and abscissa values or components of such movement being indicated upon separate or remote ordinate and abscissa value scale indicators actuated by said movement and characterized in that the movements of the pen or its equivalent and the table are linked together by a variable gear providing an infinite number of ratios between negative and positive maxima determined by the dimensions of the gear. A pen 1 is moved along a fixed bridge member 3 by a screw 6 operated by hand wheel 7 and writes on a paper carried by a board 5 moved at right angles to the travel of the pen by a screw 18 rotated through gears and shafts by hand wheel 26. The movements of the pen 1 and board 5 are transmitted to chart plates 14, 31 bearing scales 15, 32 read against pointers 16, 33. The two movements are linked together for producing straight line graphs by the following mechanism :-Hand wheel 38 rotates shafts 56 and 57 the latter driving telescopic shaft 62 which, when cam 65 operated by handle 68 lifts disc 66, drives screw 18 through gears 63, 24, 23, 21 to move board 5. Shaft 56 carries disc 35, supported on ball bearings 50, and frictionally rotating balls 40 in cage 39 to rotate roller 41 which drives screw 6 and hence pen 1 by spring tensioned chain gear. The cage 39 may be moved diametrically across disc 35 by hand wheel 47 and shaft 46 to vary the ratio of the movement of the pen to the movement of the board. The position of cage 39 is indicated upon either of scales 15 or 32 by indicators 69, 70 driven by worms on shafts 75, 76 which are geared to shaft 46 by slidably mounted changeover bevel gears 77,78. Hand setting by knobs 79, 80 is also provided. The machine may be entirely or in part electrically driven.