| 摘要 |
A permanent magnet 3 is mounted on a piston 2 sliding in a non-magnetic cylinder 1. A magnetic detector 7 to respond to the magnetic field formed by the permanent magnet 3 and to generate detection signals is mounted on the cylinder 1. A magnetic induction piece 12 in thin (e.g. 20-100 mu ) sheet form is interposed between the cylinder 1 and the magnetic detector 7 and, as the magnet begins to approach the detector 7, as shown, it acts as a magnetic bypass to reduce the detected field. On closer approach of the magnet, sheet 12 saturates and the field at detector 7 rises relatively rapidly, whereby the signal therefrom is more accurately indicative of the position of the piston. Detector 7 may be a magnetoresistor, a Hall device or a reed switch. <IMAGE>
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