Page 13 - Industrial Technology EXTRA 16th August 2021

segments, which create distinct light signals in demanding applications which could include the
received by optoelectronic sensors. This technology potential for impact or ingress. The MR2 magnetic
means that optical encoders are able to create encoder, for example, is insensitive to temperature
highly accurate, precise positioning. In addition to and has low sensitivity to unwanted external fields.
its high accuracy, the measurement of an optical
encoder, such as Portescap’s E9, is unaffected by How an encoder works
potential magnetic interference. As the encoder rotates, it generates two square
Meanwhile, a magnetic encoder comprises a wave outputs, A and B, which are normally 90
magnetised disc with a number of poles degrees out of phase with one another. By
surrounding the circumference. When the disc measuring the phase shift of the A and B outputs,
rotates, sensors detect the change in magnetic field, the encoder’s direction can be determined. To
such as those measured by Hall effect devices, measure its distance of travel or speed, the
which monitor the change in voltage. Magnetic encoder’s resolution must also be taken into
encoders, like the Portescap MR2, are ideal for use account. Resolution is the number of points of

August 2021 • INDUSTRIAL TECHNOLOGY EXTRA • p13