Patent ID: 6434851
Filing Date: 2002-08-20
Classification: F02K,F16M,G01B

Abstract:
A constant pressure mechanism of a probe for unidirectionally urging the probe in a predetermined direction by virtue of elastic force of a spring, comprising:a first pulley rotatably supported around a central axis by an instrument stationary portion; a rotation force urging mechanism for urging the first pulley in a predetermined rotation direction; and a first wire having a first end fixed to the first pulley and a second end joined to the probe, wherein the rotation force urging mechanism includes: a second pulley coaxial with the first pulley and capable of combined rotation therewith; and a second wire having an end fixed to the second pulley, and the spring having one end fixed to the instrument stationary portion with a free end joined to the other end of the second wire; wherein the first pulley and the second pulley are respectively either a circular pulley or a spiral pulley; and wherein a radius â€œrâ€  and an angle â€œ&phgr;â€  of polar coordinates of a spiral drawn by the contact point between the spiral pulley and the first or the second wire are represented by the following equations: r=f&af;(Ï†)=K&CenterDot;R2Fm&it;1+Î¸2â€ƒwhere â€œf(&phgr;)â€  represents an function of the rotation angle â€œ&phgr;â€ ; â€œKâ€  represents spring constant of the spring; â€œRâ€  represents a radius of the circular pulley; â€œFmâ€  represents measurement force of the probe; and â€œ&thgr;â€  represents a rotation angle of the circular pulley and the spiral pulley.