JP2757890B

PURPOSE:To perform the comparison with a reference pattern in a prescribed time by comparing a light quantity signal obtained by image formation of a surface part of an article to be inspected, and a light quantity signal of the corresponding reference pattern and setting the illumination light quantity. CONSTITUTION:A rotation angle of an analyzer 32 of an illumination light quantity control means 22 is set to a standard value, an image pickup by a line sensor camera 12 is executed only for a prescribed time, the charge quantity accumulated in each photodetecting element of a line sensor 14 is fetched, and each picture element signal thereof is digitized by an A/D converter 50 and inputted to a CPU 52. Subsequently, each picture element of the part corresponding to a line sensor image projected to the surface of a lead frame material 2 is called, and it is compared with each picture element signal of a reference pattern stored in a memory 54. In the case it is decided that a result of comparison is outside of an allowable range, the analyzer 32 is rotated so that a prescribed transmittivity variation is obtained, and the light quantity from a light source 18 is adjusted. According to this constitution, even if a surface reflecting state is any article to be inspected, the comparison with the reference pattern can be executed correctly in a prescribed time.