HEDS-9731#B50 Avago Technologies US Inc., HEDS-9731#B50 Datasheet - Page 2

• Manufacturer Part Number: HEDS-9731#B50
• Description: Encoders 2 Channel 1000CPR
• Manufacturer: Avago Technologies US Inc.
• Type: Optical Encoderr

Specifications of HEDS-9731#B50

• Number Of Channels: 2
• Mounting Style: PCB
• Supply Voltage: 5 V
• Product: Optical
• Technology: Rotary
• Pulses Per Revolution: 1000 CPR
• Termination Style: Solder Pin
• Detents: No
• Motion: Rotary
• Index Output: Not Indexed
• Encoder Signal: Digital
• Built In Switch: No
• Operating Supply Voltage (typ): 5VDC
• Operating Temperature Min Deg. C: -40C
• Operating Temperature Max Deg. C: 85C
• Terminal Type: PC Pins
• 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 .54
mm (0.1 inch) centers.
The standard HEDS-973x is designed for use with an 11
mm optical radius codewheel, or linear codestrip. Other
options are available. Please contact factory for more in-
formation.
Applications
The HEDS-973x provides sophisticated motion detection
at a low cost, mak­ing closed-loop control very cost-com-
petitive! 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.
Theory of Operation
The HEDS-973X 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.
The codewheel/codestrip moves between the emitter and
detector, causing the light beam to be interrupted by the
pattern of spaces and bars on the codewheel/codestrip.
The photodiodes which detect these interruptions are
arranged in a pattern that corresponds to the radius and
count density of the codewheel/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 comparators 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).
Block Diagram