| 摘要 |
PURPOSE:To accomplish corrections responding to contact positions for high- accuracy measurement of a shape, by detecting the contact positions effected on a probe-head basing upon resistance values of the contact points of a probe and of an electrode. CONSTITUTION:Over the surface of a seramic sphere 22 representing an insulator of a probe 20, a resistance coating is spread in a thin and uniform layer up to a position slightly above the half-sphere to an electric resisting layer 26 and at the top-most position, electrodes 28a-28d are installed with equal distances. Further, a specimen 30 represents a dielectric substance and an electric current of approximately 1mA, is admitted through a constant current circuit 22 to the electrodes 28a-28d. This current is admitted to flow in reversed proportion to the resistance values found between contact points and electrodes 28a-28d and individual currents 1a-1d flowed to each electrode is transformed into voltages Va-Vd and introduced into a computer 38 through an A/D convertor 36. The computer 38 processes four input data and determines positions of contact points of top of the probe-head. Thus, by making corrections in response to the contact positions, high-accuracy measurement of shape becomes available.
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