Patent ID: 8225519
Filing Date: 2012-07-24
Classification: G01B

Abstract:
1. A contact type measurement device which includes at least three linear motion axes and at least two rotating axes and in which a probe is attached to any one of the rotary axes with an arbitrary angle between the central axis of the probe and the direction of gravity, those at least three linear motion axes and at least two rotating axes are controlled according to a measurement program to move the relative position of the contact member attached to the probe with respect to the position on the surface of an object to be measured so that the central axis of the probe is kept perpendicular to the surface of the object to be measured, with the contact member in contact with the surface of the object to be measured, and measurement of the shape of the object to be measured is performed using displacement of the probe, said contact type measurement device comprising: a probe body supporting the probe with a fluid bearing; a fluid pressure controlling unit for controlling a fluid pressure inside the probe body to apply a pulling-in or pushing-out force to the probe; a distance adjusting unit having a movable part attached to the probe body; a permanent magnet attached to the movable part of the distance adjusting unit; a member attached to a second end of the probe for generating a repulsive or attractive force with respect to the permanent magnet on the movable part, the second end opposing the first end to which the contact member is attached; an angle calculating unit for determining an angle of the central axis of the probe with respect to the direction of gravity; a storage unit for storing previously-measured data on a relationship of the contact force of the probe to the object to be measured with an angle between the central axis of the probe and the direction of gravity, amount of displacement of the probe, and the fluid pressure; and a contact force controlling unit for obtaining the value of fluid pressure for canceling the variation in contact forces due to the own weight of the probe from an angle determined by the angle calculating unit on the basis of the data stored in the storage unit and controlling the fluid pressure controlling unit so that the obtained value of fluid pressure is achieved, or obtaining a displacement value of the probe for canceling the variation in contact forces due to the own weight of the probe when the fluid pressure is constant, from an angle determined by the angle calculating unit on the basis of the data stored in the storage unit and controlling the probe to move in the direction of the determined angle so that the obtained displacement value of the probe is achieved, wherein the variation in the effect of the gravitation force due to variation in the angle of the probe is cancelled out so that the contact force of the probe to the surface of the object to be measured is kept at a preset value.