Optical Rotary Encoders

Encoders are sensors that generate digital signals in response to movement. Encoders come with two outlines: rotary and linear. Both types sense mechanical motion and translate the information (velocity, position, acceleration) into useful data. 

A contactless technology 

To address demands for longer service life and with its strong track record in contact technology position sensors (potentiometers), Electromechanical Solutions SBU has been developing own-brand contactless sensors for nearly 10 years. These sensors are absolute and incremental optical encoders, magnetic technology and inductive sensors. 

Absolute optical or magnetic encoders: absolute optical encoders are position sensors that use optical signals to identify an absolute angular position. The Exxelia encoders offer very high performance levels for a very small footprint: 

• high precision (<30 arcsec), 
• high resolution (up to 21 bits), 
• highly thin (10mm), 
• EMI EMC compatibility 

Incremental optical or magnetic encoders: absolute optical encoders are position sensors that use optical signals to identify an absolute angular position. Incremental encoders have to be initialized by a first turn to produce an absolute position. 

Applications: Aeronautics, Defense, Railway, Medical, Oil exploration, Telecommunications 

Exxelia encoders can also be easily combined with other functions like Slip rings or rotary joints (FORJ, HF...) in complete proprietary systems.

A well-known image is that the difference between incremental and absolute encoders is similar to the difference between a stop watch and a clock. A stop watch measures the incremental time that elapses between its start and stop, just like an incremental encoder will provide a known number of pulses relative to a movement. If you knew the actual time when you started the watch, you can tell what time it is later by adding the elapsed time value from the stop watch. For position control, adding incremental pulses to a known starting position will measure the current position. When an absolute encoder is used, the actual position will constantly be transmitted, just as a clock will tell you the current time.