Systems and methods for multi-user detection are provided. The controller controls a conveying gap between a sheet and a succeeding sheet on the second conveying path regardless of the length of the sheets in the conveying direction. From the scanned information or manual selection, a selection of value-added services is made and the closed system metering device performs accounting related to the selected value-added services. The tool can be made from plastic, wood, metal, or any other suitable material. Thus each region of the lens or shield has no difference in temperature without regulating power supplied to the transparent conductive film, thereby eliminating wasted power consumption and allowing even a structure using a battery as the power supply to have much longer available time.