The present invention provides systems and methods which can be employed to locate or detect presence of various materials, including nonferrous metals. In the lens barrel, barrier blades openably covers an image-taking by changing over its position between an image-taking position and a standby position. A three-phase inverter circuit 52 having a substantially constant operation period is employed. The second housing portion includes a surface visible to the customer and an image display system in the surface. The busy signal releases the busy state after completion of all initialization operations for the plurality of memory chips.