2
Theory of Operation
The AEDB-9140 are emitter/detector
modules. Coupled with a codewheel,
these modules translate the rotary
motion of a shaft into a three-chan-
nel digital output.
As seen in Figure 1, the modules
contain a single Light Emitting Diode
(LED) as its light source. The light is
collimated into a parallel beam by
means of a single polycarbonate lens
located directly over the LED. Op-
posite 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 rotates between the
emitter and detector, causing the
light beam to be interrupted by the
pattern of spaces and bars on the
codewheel.
The photodiodes which detect these
interruptions are arranged in a pat-
tern that corresponds to the radius
and design of the code-wheel. 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 then
fed through the signal processing
circuitry resulting in A, Abar, B, Bbar,
I and Ibar. Comparators receive these
signals and produce the fi nal outputs
for channels A and B. Due to this inte-
grated phasing technique, the digital
output of channel A is in quadrature
with that of channel B (90 degrees
out of phase).
Resolutions
(Cycle/Rev)
Shaft Diameter*
02 - 3mm
04 - 5/32 in
05 - 3/16 in
06 - 1/4 in
11 - 4mm
12 - 6mm
13 - 8mm
14 - 5mm
C - 100 CPR
E - 200 CPR
F - 256 CPR
G - 360 CPR
H - 400 CPR
A - 500 CPR
AEDB-9140 Option
Ordering Information
Three Channel Encoder Modules with Codewheel, 11 mm Optical Radius
* Please contact factory for other shaft diameters
Available Options
Part No CPR
Shaft Diameter Options
02 04 05 06 11 12 13 14
AEDB-9140 C
••••
E
••• •
F
•••
G
•••
H
••
A
••••••••
