Page 21 - Keubler Motion Sensors
P. 21
Basics
Encoders Functional principle
Assembly and function Optical scanning (incremental)
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A disc fitted with a grating, having a code pattern
of slits and bars, is mounted so that it can rotate
between an LED and a receiver. Product overview
The light emitted by the LED is modulated by the Receiver
mask and grating and then strikes the receiver, which Mask Basics
produces a signal proportional to the luminosity. LED
When the disc rotates this signal has a shape that
approximates to a sine wave.
Optical scanning (absolut)
Grating
The light that is emitted by an LED is modulated by a
code pattern, which is applied to a rotating disc; this
is scanned by a special Kübler Opto ASIC. A unique
bit pattern is assigned to each position and this is
generally available as Gray Code.
The advantage, compared with incremental
encoders, lies in the fact that any movement of the
shaft whilst voltage is not applied is immediately
detected when power is re-applied, ensuring the
correct position is always available.
Magnetic scanning
The magnetic field created by a rotating permanent
magnet is scanned by a sensor ASIC. Each angular
position has underlying field vectors, which are
converted by the ASIC into incremental signals.
Magnet
Depending on the version, this signal will be emitted
as an incremental signal or in absolute form as a
SSI, 0 ... 10 V, 4 ... 20 mA signal or as a fieldbus signal. magn. Sensor ASIC
Limes rotary / Limes ring The Limes rotary magnetic measuring systems are
suitable for machines and plants where installation
space is tight.
The bearingless and non-contact measuring
principle allows error-free operation in
environmental conditions that require a high IP
protection level (up to IP69k) or high rotary speeds.
© Fritz Kübler GmbH, subject to errors and changes. 02/2015 www.kuebler.com 19
