HEDS-9780#G50 Avago Technologies US Inc., HEDS-9780#G50 Datasheet - Page 2

• Manufacturer Part Number: HEDS-9780#G50
• Description: Encoders 2 Channel 360CPR
• Manufacturer: Avago Technologies US Inc.

Specifications of HEDS-9780#G50

• Number Of Channels: 2
• Mounting Style: PCB
• Supply Voltage: 5 V
• Product: Optical
• Technology: Rotary
• Pulses Per Revolution: 360 CPR
• Termination Style: Solder Pin
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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.
The standard HEDS-978x is
designed for use with an 11 mm
optical radius codewheel, or
linear codestrip. Other options
are available. Please contact
factory for more information.
Applications
The HEDS-978x provides
sophisticated motion detection at
a low cost, making closed-loop
control very cost-competitive!
Typical applications include
printers, plotters, copiers, and
office automation equipment.
Note: Avago 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.
2
Theory of Operation
The HEDS-978x 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 a digital output.
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.
Block Diagram
The codewheel/codestrip moves
between the emitter and detector,
causing the light beam to be inter-
rupted by the pattern of spaces
and bars on the codewheel/code-
strip. The photodiodes which
detect these interruptions are
arranged in a pattern that corre-
sponds to the radius and count
density of the codewheel/code-
strip. 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 com-
parators 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).