Rotary Encoders

The mode of operation of optoelectronic incremental encoders can be traced back to the principle of the light barrier. A disc made of metal, glass or special plastic with a grating forms the diaphragm, which is rotatably mounted in the beam path of a light source (LED). An optical system receives the light pulses generated by the rotation of the disc and converts them into electrical signals. In order to determine the direction of the rotation, the scanning is always carried out by means of two photodetectors offset by 90°. Two quasi-sinusoidal signals with a phase shift of p/2 are applied to their output. These signals can be evaluated directly with some types. With the majority of encoders, however, there is still an internal pulse shaping into square-wave signals. By means of simple logical operations, it is possible to obtain the information about the direction of rotation contained in this so-called quadrature signal (90° phase shift). By evaluating the signal edges of both channels, it is also possible to double or quadruple the number of pulses without loss of information.

Rotary encoders are used for manual setpoint setting and serve as a human-machine interface. The setpoint value is specified by selecting the angle of rotation. Rotary encoders are available with or without pushbutton and with or without detent. They optionally have a button for acknowledging the setpoint value and a detent as haptic and audible (click) feedback. The intensity of the detent torque can also be selected. In addition, the push-buttons differ in their characteristics with regard to the duty cycle for keystroke travel and keying torque. In principle, it is possible to adapt the aforementioned properties to the respective customer requirements. Numerous electrical connection options round off the portfolio of our rotary encoders.