Image pickup apparatus for a printed wiring board

摘要

Disclosed herein is an image pickup apparatus for a printed wiring board comprising a solid state image sensor whose light receiving surface is set to be opposed to the surface of the printed wiring board, a main illumination source arranged to satisfy the law of regular reflection on the surface of the printed wiring board with respect to the light receiving surface of the solid state image sensor and a subsidiary illumination source arranged not to satisfy the law of regular reflection with respect to the light receiving surface of the solid state image sensor thereby to supply the light receiving surface with scattering light by strias formed on copper patterns. The amount of regularly reflected light, which is changed depending on the strias formed on the copper patterns, is substantially compensated by the scattering light, so that the amounts of light received by the solid state image sensor relating to the copper patterns are made substantially constant regardless of the radiation pattern of the strias. In addition, the main and subsidiary illumination sources are formed by light emitting diodes thereby to attain technical and economical advantages.