User guide

3
1.0 Introduction
As the market becomes increasingly driven by consumer
demands, businesses are forced into an intensied eort of
meeting those demands to ensure their survival. It is a free-
for-all in a business landscape that is lled with unpredictable
sentiment and unforgiving circumstances. From suppliers to
manufacturers, distributors to sales channels, all mechanisms
involved in supporting the end products are faced with the
seemingly unreasonable task of delivering products that are
record-breaking miniature sizes; complete with extended
capacities, high quality, while continuously maintaining a
cost-down price structure.
Avago Technologies, a leading supplier of motion control
products, for industrial and oce automation and consumer
applications, understands these needs. With a presence that
began over 40 years ago from its Agilent/Hewlett-Packard
roots, coupled with the technical competency and innovation
excellence, Avago continues to oer products that have
assisted thousands of automation-enablers throughout
the world, in achieving the highest level of eciency in
their equipment.
With a focus towards improving the capabilities of electrical
motor systems that will ultimately drive the automation
landscape, Avago oers the most comprehensive line of
motion control encoders to meet the needs of its customers.
Avago’s motion control encoders come with a variety of
options and characteristics that include, high operating
temperature, a wide range of resolutions, multiple channels,
various output options, and more.
2.0 What are motion control encoders?
Motion control encoders are electro-mechanical devices
that are designed to translate mechanical motion such as
position change and direction, into electrical signals.
2.1 Type of encoders available at Avago Technologies
Avago Technologies oer several types of motion control
encoder solutions to meet the needs of dierent electrical
motor systems. These encoders are divided into two
categories: Incremental and Absolute.
At the core of the encoder design is the use of proprietary
optical or magnetic-based technology for sensing
purposes. The optical technology is further expanded
by providing two dierent position sensing approaches:
transmissive or reective sensing technology.
2.1.1 Incremental and Absolute Encoders
Incremental encoders provide relative position, where the
feedback signal is always referenced to a start or home
position. On an incremental encoder, each mechanical
position is uniquely dened. The current position sensed is
only incremental from the last position sensed.
Absolute encoders generate a unique code for each
position. It has the distinctive feature of being able to
provide positional information instantly upon power-up.
2.1.2 Transmissive, Reective and Magnetic
Sensing Technology
Optical-based encoders use light to sense speed, angle
and direction of a rotary shaft. These encoders are further
separated by dierences in their sensing technology.
In transmissive optical encoders, light from a light source
penetrates a moving codewheel and is sensed by the
photo-detector on the opposite side of the codewheel.
In a reective encoder, light from a light source bounces
back from a moving codewheel and is sensed by the
photo-detector, which is located on the same side of the
codewheel as the emitter.
Magnetic-based encoders typically utilize the Hall eect
or magneto-resistive (MR) eect to sense the positional
information. Avago’s magnetic encoder with an integrated
Hall sensor requires a permanent magnet that is rigidly
mounted on the rotating shaft of a motor.
Another component of a magnetic encoder is the
magnetic sensor and associated signal conditioning
electronics. The encoder module is typically mounted
directly on the end bell of a motor. It operates on a non-
contact basis; without the need for moving parts such as
seals and bearings. Because of this, mechanical wear is not
a consideration.
Motion Control Encoders in Electrical Motor Systems
Design Guide