Linear magnetic encoder technology

A differential magnetoresistive sensor detects the magnetic signature of the magnetised scale. The sensor produces a sine and cosine signal as the sensor moves along the scale. These analogue signals can then be interpolated internally to produce a range of resolutions to 1 µm.

Accurate and reliable reading is obtained by saturating the sensors with flux from the magnetic scale. To achieve this condition the distance between the sensor and the magnetic scale must not exceed 3/4 of the pole pitch. Within this rideheight tolerance the Sine/Cosine signals are stable to 10 % signal amplitude.

The sensor detects the magnetic field gradient and is therefore almost insensitive to homogenous stray fields.

The same principle can also be used for rotative measurements, be it full revolution or partial arc. For measurements requiring a full revolution special magnetic rings are used. For partial arc measurements with a diameter of more than 60 mm the same magnetic scale as for linear measurements can be used.

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