Wachendorff Encoder Combines Magnetic and Optical Sensing

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Drawing on its expertise from 10 years in magnetic sensing and 20 years in optical sensing, Wachendorff Automation has developed a family of redundant incremental encoders that incorporate both types of sensing in a single encoder. 

Fail-safeness is increased by using different measuring principles and as few identical components as possible. The redundant standard encoders provide diverse signals that are generated completely independently but can still be correlated. Even the power supplies are available separately for each sensor unit. The basic idea behind this, explains the company, is that the different sensor platforms also react with different sensitivities or insensitivities to disturbances of any kind and therefore do not fail simultaneously, so that the associated electronics can reliably detect a possible failure. 

Magnetic resolution is rated at up to 1,024 ppr, with optical resolution up to 5,000 ppr. There are two versions, both in a 58 mm housing. The WDGR 58B model is incremental magnetic and incremental optical, the WDGE 58B is absolute magnetic and incremental optical. 

The company’s magnetic encoders work on a non-contact magnetic scanning principle. A diametral magnetized magnet is mounted in the stainless-steel shaft with its backlash-free bearings. If the shaft is rotated, the magnet and the magnetic field rotate with it. This change in the magnetic field is detected and processed by a sensor chip on the printed circuit board opposite. The evaluation enables signals to be generated that are 90° phase-shifted as well as a zero pulse. The downstream electronics conditions these into high-precision signals and amplifies them into industrially usable square-wave pulses in HTL and TTL plus their inverted signals. 

Based in Geisenheim, Germany near Wiesbaden, Wachendorff develops and manufactures rotary encoders, engine feedback devices and complete measuring systems for use in a wide range of serial production applications for mechanical and plant engineering. For more info, see www.wachendorff.de.