Two or more imagers having associated frame rates are each configured with a global shutter having an exposure interval less than a frame interval. The method includes visually indicating that a recovery operation has started, periodically determining the remaining recovery time based on the remaining tape spool, and displaying the determined remaining recovery time to show progress status of the operation. In a partial annular region of a lower end surface 10a1 of a disk part 10a making up the holding member 10, a region where a plurality of dynamic pressure grooves 10a2 and a plurality of sectioning parts 10a3 formed between the plurality of dynamic pressure grooves 10a2 to section the respective dynamic pressure grooves 10a2 are arrayed spirally is formed. The groove 22 reaches the substrate. As a result, a high-integrated high-speed electronic circuit, which is excellent in uniformity and reproducibility, can be easily embodied. The engaging piece is adjacent to the delivery assembly and includes a shaft, the shaft inserts through the slantwise slot to couple the engaging piece to the mounting piece.