The present invention is directed to obtaining an image having predetermined brightness, while making the degradation of the image as little as possible. In this vibration plate unit, a plate member made from metal is fitted in the interior of the resonance conduit via a support member made from rubber, and thereby it is arranged, while blocking mutual flow of air between the banks, also to obtain the beneficial effects of resonant supercharging by enabling the mutual transmission of pressure between surge tanks. The browser automatically displays each page of the content at specific intervals according to the instruction, and a user confirms the displayed information. Stacks input to the machine may include mixtures of various types of sheets.