Electronic caliper for internal or external diameters - measures and processes chord length and chord height of circular section

摘要

The method is for measuring the diameter of cylindrical or spherical objects or bores, and is suitable for use by untrained staff. A pair of feelers are used, separated by a distance smaller than the diameter so that they contact the circular section at the ends (1, 2) of a chord (S). The perpendicular distance of the chord from the circumference is used as a measure of the diameter, after the conversion to an analogue voltage, being derived as a simple difference measurement using the distance of the two feelers from a fixed reference plane or point. To cover different ranges, the feeler spacing may be made variable and its value converted into an analogue voltage for computation automatically.