Patent ID: 8723946

Claim:
A workpiece inspecting apparatus for rotating a workpiece having a shape portion containing a convex portion and a concave portion which are periodically and repetitively formed on the workpiece and picking up images of the shape portion of the workpiece to inspect the workpiece, comprising: a workpiece rotating mechanism that outputs reference pulses at a fixed interval while rotating the workpiece at a fixed rotational speed; an image pickup mechanism that picks up images of the shape portions of the workpiece every image pickup timing based on the reference pulses; an image pickup controller that synchronizes each of the shape portions of the workpiece with the image pickup timing based on the reference pulses; and an inspection processor that executes first image processing of taking a difference between a pickup k-th (k represents an integer) image and a pickup (k+1)-th image and first inspecting processing of detecting a defect on the basis of differential data representing the difference, wherein the image pickup mechanism comprises: a workpiece pulse output mechanism equipped with a rotator that is rotated integrally with the workpiece and has detection target portions arranged at the same angular interval as the shape portions of the workpiece with respect to a rotational center of the rotator, and a proximity sensor that outputs a workpiece pulse every time each of the detection target portions of the rotator is detected; and a pulse counter that counts an interval between the workpiece pulses on the basis of the reference pulses and achieves a pulse number corresponding to the interval, and the image pickup controller performs image pickup at the image pickup timing based on the reference pulses by using the workpiece pulse as a trigger, and performs image pickup at the image pickup timing based on the reference pulses every time the reference pulses whose number corresponds to the pulse number are output from the image pickup timing.