Linear Encoder LIA - NUMERIK JENA

Catalogue Linear Encoder LIA

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Offset and Amplitude Control, Set up LED

Dynamic Offset and Amplitude Control

Contamination and mounting errors lead to interferences in the optical scanning of the scale by the scanning head, and so to periodic deformations of the sinusoidal counting track signals.

These deformations manifest themselves as

■ offset deviations and

■ amplitude deviations, as well as

■ amplitude differences between the sine and cosine channel

and lead to interpolation errors.

The signals generated by the measuring module are automatically corrected within the sensor without following error over the entire velocity range.

This measure not only increases the accuracy, but also the reliability of the encoder.


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Scanning signal of contaminated scale before offset and amplitude correction


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Set up LED

The mechanical alignment of the scale and scanning head to each other can be checked with the set up LED.

The signal for triggering the LED is gained from the coarse sensor signals before the offset and amplitude control.

Signaling of mounting errors

■ The LED is dark when the encoder is optimally mounted according to the prescribed tolerances.

■ The LED begins to shine when deviations from the optimal mounting state occur. The larger the deviations, the brighter the LED shines.

Signaling of scale tape contaminations

■ The LED industrial lights up briefly when contaminated positions of the scale are traversed.

Scanning signal at incorrect mounting conditions before offset and amplitude correction

Scanning signal of contaminated scale and/or incorrect mounting conditions after offset and amplitude correction

Switch sensors

The opto-electronic switch sensors additionally integrated in the scanning head can be used

■ to detect limit positions with left/right recognition or

■ to indicate the scanning head position within the measuring range or

■ to enable a reference mark

(selection of one reference mark from n marks). A combination of these variants is also possible.

By using these switch sensors, you save the cost and cabling for additional sensors.

The scanning head of the LIA 21 is equipped with one switch sensor, and the scanning head of the LIA 22 with two switch sensors.

The switch sensors of the LIA 22 can be differently aligned as viewed from the measuring direction (see page 7):

S1 + S2 alignment behind each other in one track or S1 + S3 alignment next to each other in two parallel tracks

The switch sensors can be used universally via the various output circuits (ordering options):

■ TTL low activ or TTL high activ

■ open collector low activ or open collector high activ

■ MOS relays opening or

closing up to a 300 V switching voltage

When using MOS relays and two switch sensors (LIA 22), the two switching outputs have a common switching contact, which can be connected to either 0 V or to the switching voltage.