FAULHABER encoders: Optical encoders

Optical encoders are characterised by a very high position and repeat accuracy as well as a very high signal quality due to the precise measuring element. Furthermore, they are insensitive to magnetic interference.

In optical encoders, a code disc with a measuring element is used that is attached to the shaft of the motor. A distinction is made here between reflective and transmissive optical encoders.

Reflective encoders

With reflective encoders, the light from an LED is reflected by the reflective surface of the code disc and collected by photodetectors. Reflective optical encoders are especially compact since the LED, the photodetectors and the electronics can be mounted on the same circuit board or even on the same chip. For these reasons, FAULHABER primarily uses reflective optical encoders.

Transmissive encoders

Transmissive encoders make use of the transmitted light process. Here, the light from the LED passes through slits in the code disc and is collected by photodetectors on the other side of the code disc.

FAULHABER encoders: Magnetic encoders

Magnetic encoders are especially insensitive to dust, humidity and thermal or mechanical shock. In magnetic encoders from FAULHABER, sensors are used that determine the changes of the magnetic field. The magnetic field is changed by the movement of a magnetic object. This can be the magnet of the motor or an additional sensor magnet with a defined measuring element that is attached to the shaft of the motor.

Using magnetic encoders, an additional sensor magnet is usually necessary. In case of integrated digital or analogue Hall sensors, however, the movement of the rotor magnet in the motor can be measured directly. With integrated Hall sensors, such as nearly all FAULHABER Brushless DC-motors have, there is generally no additional sensor magnet is necessary.

Digital Hall sensors for magnetic encoders

The term sensor refers to digital or analogue Hall sensors which, in case of the FAULHABER Brushless DC-Motors, are usually mounted directly on the motor circuit board. Digital Hall sensors are used primarily for the commutation of the Brushless DC-Motors and for simple speed control. Nearly all FAULHABER brushless DC-Motors are equipped by default with three integrated digital Hall sensors and are thus ideally suited for use in combination with incremental encoders from FAULHABER.

A comparison of analogue Hall sensors and encoders

Analogue Hall sensors are an economical, simple and compact alternative to encoders. Due to the higher resolution, these can also be used for exact rotational speed or position control. For the analogue Hall sensors option from FAULHABER please refer to “Controller combinations” directly in the motors’ data sheets under this selection, no encoder is necessary. If you opt for an analogue Hall sensor, it is recommended that the sensor will be operated with FAULHABER Controllers, which are perfectly laid out for the analogue Hall signals.