INSPECTING METHOD FOR DEFECT OF PERIODIC PATTERN

摘要

PURPOSE:To execute high-speed inspection by a line sensor camera of high resolution without using a large-capacity memory, by recognizing the opposite ends of connecting components of binary signals as being outside a region having a periodic pattern and by removing signals outside the region. CONSTITUTION:A shadow mask 2 conveyed at a prescribed speed by a conveyor device 3 is illuminated 4 and the image of a transmitted light therethrough is picked up by a line sensor camera I. Signals of this image are smoothed by a signal processing device 6 and sliced by a prescribed level and thereby binary signals are obtained. These signals are subjected to an expansion processing so as to recognize the outer periphery of a periodic pattern. Next, the signals are subjected to a degeneration processing so as to remove signals generated outside a periodic pattern part. Since the signals are made narrower in width than the actual periodic pattern by the degeneration processing, they are expanded further by a prescribed number of pixels and the opposite ends of the signals are recognized as addresses of the outer periphery of the periodic pattern part. These are subjected to secondary differentiation so as to remove signals outside a region and then subjected to a slicing processing and thereby a defect is extracted. According to this constitution, detection of the defect in each scan of the camera is enabled and a large-capacity memory is dispensed with.