GB728977A - Differential indicator device for measuring instruments - Google Patents

Abstract

728,977. Cathode-ray oscilloscopes. ARMSTRONG WHITWORTH AIRCRAFT, Ltd., Sir W. G. Aug. 6, 1953 [Nov. 28, 1952], No. 30169/52. Class 37. [Also in Group XIX] A device for indicating the difference between two readings of a measuring instrument comprises a main control knob coupled to a spindle of the instrument and provided with a hairline cursor which coacts with graduations on a zero-setting dial arranged concentrically with the spindle and frictionally held against a fixed part but capable of adjustment, both hair-line and zero-setting dial coacting with a stationary marker, the hair-line being positioned on the control knob so that when aligned with the stationary marker the knob is angularly movable in opposite directions to equal extents, the movements of the knob and zero-setting dial being at all times mechanically independent. As shown, Fig. 2, a control knob 12 carries a transparent cursor 17 with hair line 18 and is secured to a potentiometer spindle 13 extending through a boss 22 with radial flange 22a axially locating a graduated zero-setting dial 23 journalled on the boss against a friction ring 24 fixed to a panel 20 which supports a stationary marker 27 with hair-line. The device may be used for measuring the amplitude and the low and high values of a wave form on the screen of a cathode ray oscillograph by a succession of manipulations and readings, obviating calculation by the observer.