HEDS-974X Datasheet, PDF (1/6 Pages) Agilent(Hewlett-Packard) – 180, 300, 360 LPI Small Optical Encoder Modules

Agilent HEDS-974x Series
for 180, 300, 360 LPI Small Optical
Encoder Modules
Data Sheet
Description
The HEDS-974x series is a high
performance, low cost, optical
incremental encoder module. When
operated in conjunction with code-
strip, this module detects linear
position. The module consists of a
lensed LED source and a detector
IC enclosed in a small C-shaped
plastic package. Due to a highly
collimated light source and a
unique photodetector array, the
module is extremely tolerant to
mounting misalignment.
The two-channel digital outputs and 5
V supply input are accessed through
four solder-plated leads located on
2.54 mm (0.1 inch) centers.
Applications
The HEDS-974x provides sophisti-
cated motion detection at a low
cost, making close-loop control
very cost-competitive! Typical
applications include printers,
plotters, copiers, and office
automation equipment.
Note: Agilent Technologies
encoders are not recommended for
use in safety critical applications.
Eg. ABS braking systems, power
steering, life support systems and
critical care medical equipment.
Please contact sales
representative if more
clarification is needed.
Theory of Operation
The HEDS-974x is a C-shaped
emitter/detector module. Coupled
with a codewheel, it translates
rotary motion into a two-channel
digital output. Coupled with a
codestrip, it translates linear
motion into digital outputs.
As seen in the block diagram, the
module contains a single Light
Emitting Diode (LED) as its light
source. The light is collimated
into a parallel beam by means of
a single lens located directly over
the LED. Opposite the emitter is
the integrated detector circuit.
This IC consists of multiple sets
of photodetectors and the signal
processing circuitry necessary to
produce the digital waveforms.
The codestrip moves between the
emitter and detector, causing the
light beam to be interrupted by the
pattern of spaces and bars on the
codestrip. The photodiodes which
detect these interruptions are
arranged in a pattern that corre-
sponds to the count density of the
Features
• Small size
• Multiple mounting options
• Wide resolution range
• Linear options available
• No signal adjustment required
• Insensitive to radial and axial play
• –40°C to +85°C operating
temperature
• High resolution version of the
HEDS-970x
• Two-channel quadrature output
• TTL or 5.0 V CMOS compatible
• Single 5 V supply
• Wave solderable
• Integrated 2.5 KΩ pullup on outputs
codestrip. These detectors are also
spaced such that a light period on
one pair of detectors corresponds
to a dark period on the adjacent
pair of detectors. The photodiode
outputs are fed through the signal
processing circuitry. Two compara-
tors receive these signals and
produce the final outputs for
channels A and B. Due to this
integrated phasing technique, the
digital output of channel A is in
quadrature with channel B (90
degrees out of phase).
ESD WARNING: NORMAL PRECAUTIONS SHOULD BE TAKEN TO AVOID STATIC DISCHARGE.