Portable electronic precise slide caliper

摘要

The calliper consists of a slider (1) which may be moved along a fixed rod (2) so as to measure an object between jaws (10,20). The fixed rod (2) has a ruler (21) attached to it which is magnetised periodically along its length at a period of approximately 1 mm. The slider (1) has a sensor (112) consisting of a network of magnetoresistive electrodes arranged in sets of at least eight in order to reduce current consumption and enable a battery (110) and electronic circuit (11) to measure resistances using bridge methods. The resistance measurements are used to determine the distance between the jaws of the calliper which is shown on a liquid crystal display (12).