Patent ID: 7148432

Claim:
A weight sensor characterized by comprising: a first rotating shaft vertically and rotatably supported on a stage; a second rotating shaft axially and coaxially connected to the first rotating shaft with a magnetostrictive member interposed therebetween for rotatably supporting an object to be measured; detecting means for detecting changes in magnetic permeability or remnant magnetization of the magnetostrictive member, wherein load or pressure of the object is detected as changes in magnetic permeability or remnant magnetization, which are caused by extension and contraction of the magnetostrictive member, wherein the detecting means includes a pickup coil disposed to surround the magnetostrictive member without contacting the first and second rotating shafts, the changes in magnetic permeability or remnant magnetization are detected as changes in inductance of the pickup coil, and the first rotating shaft is rotatably supported by a pair of radial magnets disposed between the first rotating shaft and the stage such that their magnetic poles are opposite each other.