The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 05, 1997
Filed:
Dec. 23, 1994
Takashi Suzuki, Aichi-ken, JP;
UHT Corporation, Aichi-ken, JP;
Abstract
A method for accurately determining a center of target marks provided on a workpiece. The method involves imaging, at an imaging station, a circular target mark associated with the workpiece. A signal produced by the imaging operation is binary-encoding, in an image processor, and displayed on a monitor screen connected to said image processor. Starting points X1 and X2 of a different level of intensity are detected by scanning in one of either an X-axis direction or a Y-axis direction on a center of a cursor (shown on the monitor screen) when the center of the cursor is within the target mark. Other starting points Y1 and Y2 of a different level of intensity are detected by scanning in another of the X-axis direction or the Y-axis direction on a mid-point of coordinates of the starting points X1 and X2. Still other starting points X1' and X2' of a different level of intensity are detected by scanning, in parallel to the direction of the starting points X1 and X2, on a mid-point of coordinates of the starting points Y1 and Y2. A reference value of a diameter in the X-axis direction and the Y-axis direction of the target mark stored in a memory (ROM) is compared with a distance between Y1 and Y2 and a distance between X1' and X2', in order to determine an intersection point 0 of segments between points Y1 and Y2 and X1' and X2' as the center of the target mark when the comparison matches.