Patent ID: 7814779

Claim:
A surface texture measuring instrument, comprising: a measuring portion including a stylus having a contact portion that contacts a surface of a workpiece and a measuring force detecting unit that detects a detection measuring force when the contact portion contacts the surface of the workpiece; a relative movement unit that relatively moves the measuring portion and the workpiece; a position detecting unit that outputs as measuring point information a measuring point on which the workpiece is measured by the measuring portion; a force control loop that collects the detection measuring force detected by the measuring portion and drives the relative movement unit such that the detection measuring force substantially coincides with a target measuring force; a touch signal generating unit that collects the detection measuring force detected by the measuring portion and generates a touch signal when the detection measuring force coincides with a contact measuring force; and a measurement value collecting unit that collects the measuring point information from the position detecting unit each time the touch signal is generated from the touch signal generating unit, wherein the force control loop is adjustable such that the detection measuring force detected by the measuring portion oscillates, the force control loop includes a processing unit that computes a deviation between the detection measuring force detected by the measuring portion and the target measuring force and outputs the deviation, and a gain adjusting unit that amplifies an output from the processing unit by a setting gain and gives the output to the relative movement unit, and the setting gain of the gain adjusting unit of the force control loop is adjustable such that the detection measuring force detected by the measuring portion oscillates.