GB740810A - Variable electrical resistances or potentiometers - Google Patents

Abstract

740,810. Variable resistors and potentiometers. NATIONAL RESEARCH DE - VELOPMENT CORPORATION. Oct. 15, 1953 [July 28, 1952], No. 18975/52. Class 37. [Also in Group XXXVIII] Relates to devices in which resistance variation is produced by change in position of tangential contact between a resistance element and a contact element. There may also be change in area of contact and at least one of the elements has a radius of curvature which is large compared with the length of the curve. The curve may be an arc having variations in curvature to suit the required output law. The position of the line of contact relative to either end of the resistance element is variable by a rolling motion of one member relative to the other which is substantially free from slip and is produced by a single displacement input at one part of one of the members. The invention is described with reference to transducers in which fluid pressure is the primary variable. In the potentiometer of Fig. 4 and 4a a frame 9 pivots about 19 at mid-point of fixed resistance element 3 so that end 2 of conducting bar 1 is displaced in a circular path and moves the tangent tap along 3 with contact pressure being maintained by tension-spring 22. Figs. 3 and 3a show a potentiometer in which a hairpin spring 16 maintains contact pressure between a curved resistance element 3 and a curved contact element 17 which is an extension of lever 12. The elements 3, 17 pivot respectively at 18, 13 and may have involute profiles or the profiles necessary for a particular output law. Specification 600,620 is referred to.