To provide an inexpensive linear switch having a simple structure, and at the same time to provide a sensor sheet for bed by which whether a bed user is lying in bed or getting up, and in addition, at least the offsetting at a position on the bed can be detected.

This hydraulic linear switch 18 is constituted of a flexible tube 19 which can be elastically collapse-deformed at least in the radial direction, a liquid which is enclosed in the flexible tube 19, and a pressure switch 20 which outputs a signal to the outside when the liquid pressure is at a set value or higher. This bed sensor sheet 10 has a structure wherein the hydraulic linear switch 18 is respectively arranged on both sides of a bed, and at the same time, at an approximately intermediate part of the bed, a strip switch 17 having an electric contact point in the longitudinal direction is arranged.

COPYRIGHT: (C)2004,JPO