chapter  31
Magnetic Displacement Sensors
Pages 14

Several types of linear and angular displacement measuring devices rely on electromagnetic Ÿelds, and the magnetic properties of materials, in the operation of their basic sensing elements. Some may not commonly be referred to as magnetic sensors but are instead named according to their speciŸc sensing technique. œe magnetic sensors presented here use either a permanent magnet, an AC-or DC-powered electromagnet, or a coiled conductor. Together with various components and materials used to sense the magnetic Ÿeld, the combination is arranged to obtain a response indicating angular or linear displacement or position.Either the sensor is caused to operate by a magnetic Ÿeld or the properties of the sensor are derived from the use of a magnetic Ÿeld.Types of magnetic sensors presented in this section include magnetostrictive, distributed impedance, magnetoresistive, Hall e¥ect, and magnetic encoders. Some versions of synchro/resolvers and related sensors loosely meet the characteristics listed earlier but are included in another section of this handbook and thus will not be included in this section. Linear variable di¥erential transformers (LVDTs) and inductive proximity sensors are types of magnetic displacement sensors, but measure displacement over a limited range, and are also covered in another section of this handbook.