| 摘要 |
PURPOSE:To detect the defects near contours with good accuracy in appearance inspection by image pickup signal processing by counting change points respectively at two large and small levels only when the regions contg. the contours of an object are scanned. CONSTITUTION:The optical image of an inspecting object 50 illuminated by an illuminating device 51 is photoelectrically converted by a photoelectric converting device, and is inputted via an amplifier 53 to change point detecting parts 54, 55. Said parts 54, 55 binary encodes these with the threshold level lower than the contour level and the intermediate level of the contour level and the defect level and input one pulse for each of respective change points to gates 57, 58. A region assigning part 56 opens the gates 57, 58 only when the current scanning point is the part contg. the contours of the inspecting object. A comparing decision part 61 compares the value subtracting the number of the change points of normal cases from the count value of a change point number counter 59 and the count value of a change point number counter 60 per se as a defect quantity in the regions A with the respective set values of a permissible defect value setting part 62, thereby deciding whether the inspecting object is defective or non-defective. |
