Patent ID: 7827002
Filing Date: 2010-11-02
Classification: G01B,G01D

Abstract:
1. A contact displacement meter that has a housing and a contact attached to the housing to be movable in one direction, and measures a displacement of the contact, the contact displacement meter comprising: a light emitting element; a line sensor with light receiving elements for receiving light emitted from the light emitting element are arrayed at a first array pitch; a movement scale which is arranged on an optical path from the light emitting element to the line sensor, has reference light passing regions arrayed in a line in the one direction, a light shielding portion adjacent to the reference light passing regions, and a lattice region in which light passing regions and light shielding regions at substantially equal intervals are alternately arrayed at a second array pitch different from the first array pitch in the one direction between the reference light passing regions, and moves in the one direction together with the contact, the reference light passing regions being away from each other by a distance of a unique value in the movement scale; and a control circuit comprising: a detector for detecting a peak position of the reference light passing region at which a received light signal of light passed through the reference light passing region takes a local maxim; a first specifier for specifying an absolute position of the reference light passing region based on a distance between the adjacent peak positions detected by the detector; a second specifier for specifying a relative position of the reference light passing region with respect to the line sensor based on a received light signal of light passed through the lattice region; and a displacement calculator for calculating the displacement of the contact based on the absolute position specified by the first specifier and the relative position specified by the second specifier.