초록 ▼

A method and apparatus for characterizing a central circular aperture of a workpiece, for example a flexible information storage disk. The apparatus utilizes a noncontact sensor system having a rotary stage upon which the workpiece is placed. A reference edge extending approximately to the axis of r

A method and apparatus for characterizing a central circular aperture of a workpiece, for example a flexible information storage disk. The apparatus utilizes a noncontact sensor system having a rotary stage upon which the workpiece is placed. A reference edge extending approximately to the axis of rotation of the stage serves as a reference point from which a laser beam measures a plurality of radial distances extending from the reference edge to a plurality of points about the disk\s central aperture. A computer utilizes these distances along with a known deviation of the reference edge from the center of rotation of the stage to construct a shape comprising a plurality of inscribed triangles. The center of the shape is found by mathematically determining its center of gravity. The center of gravity is then used to locate a reference coordinate system and precise reference circles are drawn around the center of gravity. The size and shape of the disk central aperture is then plotted based on the deviation of the aforementioned shape from the reference circles.

대표청구항 ▼

Apparatus for characterizing the roundness of a workpiece aperture, said apparatus comprising: (a) a rotary stage adapted to receive a workpiece having an aperture to be characterized, said rotary stage including a central aperture surrounding the workpiece aperture; (b) a reference surface mounted

Apparatus for characterizing the roundness of a workpiece aperture, said apparatus comprising: (a) a rotary stage adapted to receive a workpiece having an aperture to be characterized, said rotary stage including a central aperture surrounding the workpiece aperture; (b) a reference surface mounted to provide a fixed radial reference point approximately at the axis of rotation of said rotary stage; (c) movement means for incrementally rotating said rotary stage, to rotate the workpiece in a stepwise manner around the fixed radial reference point; (d) a non-contact detection means for measuring a radial distance associated with each angular position of the workpiece, each radial distance extending along a predetermined radial path between the fixed radial reference point and the corresponding periphery of the workpiece aperture; and (e) programmable computer means, in communication with said movement means and having an input for receiving a signal from said detection means corresponding to each radial distance that is measured, said computer means being adapted to coordinate each radial distance with the corresponding angular position of the workpiece, to characterize the size and the shape of the workpiece aperture.