Compensation for a switching regulator is attained by developing a compensation signal for a switching regulator that is independent of changes in the switching frequency. The overhanging part is formed on an edge portion thereof with a surface that slants downward from a top surface of the outside rail. The switching signal held by the output interface circuit is a digital representation of a detection coil position parallel to an external magnetic field. The mattress optionally might have one or more folding sections to convert the bed into more like a chair or reclining chair. The authentication server 600 performs an authentication processing of the authentication ticket, and the authentication result is notified. Also, in a preferred embodiment, the images are encrypted to prevent tampering by the user or a third party, and thereby preserve the integrity of the receipt image.