Transcript Slide 1

Linear encoder
A linear encoder is a sensor, transducer or readhead paired with a scale that
encodes position. The sensor reads the scale in order to convert the encoded
position into an analog or digital signal, which can then be decoded into position
by a digital readout (DRO) or motion controller. The encoder can be either
incremental or absolute. Motion can be determined by change in position over
time. Linear encoder technologies include optical, magnetic, inductive,
capacitive and eddy current. Optical technologies include shadow, self imaging
and interferometric. Linear encoders are used in metrology instruments and high
precision machining tools ranging from digital calipers to coordinate measuring
machines
Rotary encoder
A rotary encoder, also called a shaft
encoder, is an electro-mechanical device
that converts the angular position of a shaft
or axle to an analog or digital code, making it
an angle transducer. Rotary encoders are
used in many applications that require
precise shaft unlimited rotation—including
industrial controls, robotics, special purpose
photographic lenses[1], computer input
devices (such as optomechanical mice and
trackballs), and rotating radar platforms.
There are two main types: absolute and
incremental (relative).
Mechanical
absolute
encodersAbsolute rotary
encoder ROD 425
Optical absolute encoders
Standard binary encoding
Rotary encoder for angle-measuring devices marked
in 3-bit binary. The inner ring corresponds to Contact
1 in the table. Black sectors are "on". Zero degrees is
on the right-hand side, with angle increasing
counterclockwise.
An example of a binary code, in an extremely
simplified encoder with only three contacts, is shown
below.
In general, where there are n
contacts, the number of distinct
positions of the shaft is 2n. In this
example, n is 3, so there are 2³ or 8
positions.
Gray code
The reflected binary code, also known as Gray code after Frank Gray, is a
binary numeral system where two successive values differ in only one bit.
The reflected binary code was originally designed to prevent spurious output from
electromechanical switches. Today, Gray codes are widely used to facilitate error
correction in digital communications such as digital terrestrial television and some
cable TV systems.
Milestone: Inductive Micro Encoder
LM10 linear magnetic encoder
system
• The LM10 features a compact sealed readhead that rides at up to
1.5 mm from the self-adhesive magnetic strip scale, which brings
100 m travel.
• Simple to install, the LM10 features an integral set-up LED on the
readhead, wide installation tolerances and an applicator tool for the
adhesive-backed magnetic scale. A bidirectional reference is
provided that can be either actuated by a preset mark integrated
within the scale or by adding a reference sticker on top of the scale
with the help of a self aligning installation tool.
• The encoders come in digital or analogue output variants and offer a
range of customer selectable resolutions 1 µm, 2 µm, 5 µm, 10 µm,
20 µm and 50 µm. The LM10 is capable of velocities up to 25 m/s;
even at 1 µm resolution it is capable of 4 m/s.
iC-LSB
8-Channel Active Photosensor Array
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