Spindle Know-How

Encoders

Encoders for signal forma­tion from move­ments work opti­cally, magne­ti­cally or mecha­ni­cally with conta­cts. Trans­du­cers or input devices detect the current posi­tion of a shaft or drive unit and output it as an electri­cal signal. There are two types of encoders: rotary and linear encoders. Rotary encoders are moun­ted on rota­ting compon­ents, for example on a motor shaft. Linear encoders are typi­cally moun­ted on compon­ents with strai­ght move­ments.

Encoders have incre­men­tal, coun­ta­ble or even abso­lute mate­rial measu­res as line patterns (light barrier), magne­tiz­a­tion or conta­cts. In the case of perma­nent magne­tiz­a­tion, the magne­tic field modu­la­tion can be control­led by means of AMR, GMR, hall sensors or induc­tive sensors can be evalua­ted. For incre­men­tal induc­tive sensors, non-magne­tic toot­hing is often suffi­ci­ent.

Abso­lute encoders operate on the basis of mate­rial measu­res which assign a unique signal pattern to each posi­tion (see abso­lute encoders).

Non-abso­lute measu­ring encoders are called incre­men­tal encoders. They are used on motor shafts but also as input devices for digi­tally opera­ting devices, to set para­me­ters (e.g. volume) or to control motor move­ments manu­ally (e.g. at CNC control systems).

With the help of the output signal of an encoder, a suita­bly equip­ped drive unit can carry out repro­du­ci­ble move­ments and – in the case of an abso­lute encoder – move back exactly to the star­ting posi­tion (refe­rence posi­tion) even after the machine has been swit­ched off. Incre­men­tal encoders require an addi­tio­nal encoder to find the refe­rence posi­tion, for example a limit switch. An example of a linear incre­men­tal encoder is the opti­cal scan­ning of a line pattern applied to a strip in a prin­ter which allows the print carriage to perform a defi­ned move­ment along the line.

Source: German Wiki­pe­dia

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