| 摘要 |
<p>Provided is a device for detecting a state-change of a wire rod, which detects either the total length of a wire rod (10) buried in a base metal (3) or the extension change between two arbitrary points so that the information on the magnitude of the extension may be outputted at an original position. In the longitudinal direction of the wire rod, there is disposed a casing member, in which a first rigid cable (21) and an elastic member (41) are connected in series between fixing members disposed at the two ends of the wire rod. A switch unit (16) is fixed on a fixing member connected to the elastic member, and detects a relative displacement from a contact point on the first rigid cable (21). An information output circuit (13) outputs information in accordance with that displacement. When the wire rod (10) causes the extension change in the longitudinal direction, the elastic member (41) extends and changes the state, and the contact point displaces relative to the switch unit (16), so that the information is outputted from the information output circuit (13).</p> |
