AEDS-964X
Small Optical Encoder Modules 150, 300, and 360 LPI Digital Output
Data Sheet
Description
The AEDS-964X is a very small, low package height
and high performance incremental encoder module. It
can operate at supply voltage, Vcc, 3.3/5V and the
output voltage, Voh, will follow the Vcc voltage level.
When operated in conjunction with a codestrip, this
module detects linear position. The encoder consists
of lensed LED source and a detector IC enclosed in a
small C-shaped plastic package. Due to the brighter
LED, coupled with a photodetector array, which is less
sensitive to light, the encoder is highly tolerant to
aerosol environment. This module is extremely
receptive to mounting misalignment.
The two channel digital outputs and Vcc, supply
voltage input, are accessed through four solder plated
leads located on 2.00mm (0.1 inch) centers. The supply
input of LED, rated at 16mA is accessed through two
leads located at 2.54mm.
It is designed for use with a linear codestrip/codewheel.
Other options are available. Please contact the factory
for more information.
Features
•
Small Size
•
Built-in guide bumps for codewheel and codestrip
•
Low Package Height
•
Insensitive to Radial, Tangential and Axial Play
•
0°C to +70°C recommended operating temperature
•
Wide Resolution Range
•
Two Channel Quadrature Output
•
TTL 3.3V or 5.0V CMOS compatible
•
For Linear and Rotary Application
•
Wave solderable
•
RoHS Compliant
Applications
•
Printers
•
Copiers/Fax
•
Plotters
•
Office Automation Equipments
Theory of Operation
The AEDS-964X 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 two-channel
digital output.
As seen in the Figure 1, the module contains a single
Light Emitting Diode (LED) as its light source. The light
is collimated into parallel beam by means of a single
lens located directly over the LED. Opposite the emitter
are the integrated detector circuits.
This IC consists of multiple sets of photodetectors and
a 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 codehweel/
codestrip. The photodiodes that detect these
interruptions are arranged in a pattern that
corresponds to the radius and count density of the
codewheel/0codestrip.
These detectors are also spaced such that a light period
on one pair of detectors corresponds to a dark period
on the adjacent pairs 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 output of channel A
is in quadrature with Channel B (90 degrees out of
phase).
Definitions
Note: Refer to Figure 1 for the output waveform
Count (N):
The number of bar and window pairs or
counts per revolution (CPR) of the codewheel. Or the
number of lines per inch of the codestrip (LPI)
1 shaft Rotation = 360 degrees
= N cycles
1 cycle (c) = 360 electrical degree, equivalent to 1 bar
and window pair.
Pulse Width (P):
The number of electrical degree that
an output is high during one cycle. This value is
nominally 180° e or 1/2 cycle.
Pulse Width Error (∆P):
The deviation, in electrical
∆
degrees, of the pulse width from its ideal value of 180°
e.
State Width (S):
The number of electrical degrees
between a transition in the output of channel A and
the neighboring transition in the output of channel B.
There are 4 states per cycle, each nominally 90° e.
State Width Error (∆S):
The deviation, in electrical
∆
degrees of each state width from its ideal value of 90°
Phase (f): The number of electrical degrees between
the center of the high state of channel A and the center
of the high state of channel B.
Phase Error (∆φ
the deviation of the phase from its
∆φ):
∆φ
ideal value of 90°e.
Direction of Rotation: When the codewheel rotates in
the counter clockwise direction (as viewed from the
encoder end of the motor), channel A will lead channel
B. If the codewheel rotates in the clockwise direction,
channel B will lead channel A.
Optical Radius (Rop):
The distance from the
codewheel’s center of the rotation to the optical center
(O.C) of the encoder modules.
Angular Misalignment Error (E
A
):
Angular
misalignment of the sensor in relation to the tangential
direction. This applies for both rotary and linear motion.
Mounting Position (R
M
):
Distance from Motor Shaft
center of rotation to center of Alignment Tab receiving
hole.
2
Electrical Characteristics
Electrical Characteristics over Recommend Operating Range, typical at 25°C
Parameter
Supply Current (Detector)
High Level Output Voltage
Option P - 150 LPI
Option 1 & 2 - 300 & 360 LPI
Low Level Output Voltage
Option P - 150 LPI
Option 1 & 2 - 300 & 360 LPI
Rise Time
Fall Time
LED Forward Voltage
Symbol Min.
I
CC
V
OH
2.4
2.4
V
OL
1.5
Typ.@
3.3V
3.0
3.3
3.3
Max.
8
5.2
5.2
0.4
0.4
Units
mA
V
V
V
V
ns
ns
Notes
Typ. I
OH
= -0.7 mA @ 3.3 V
Typ. I
OH
= -0.4 mA @ 3.3 V
Typ. I
OH
= 8mA @ 3.3V
Typ. I
OH
= 13mA @ 3.3V
C
L
= 25 pF
R
L
= 11 kΩ
Typical I
F
= 16mA
t
r
tf
VF
200
50
1.3
1.6
(turn on)
1.8
V
Note: Refer to Figure 2 for output waveform on tr and tf
Encoding Characteristics
Encoding Characteristics over the Recommended
Operating Conditions and Mounting Conditions. These
characteristics do not include codewheel/codestrip
contribution.
1. The typical values are average over the full rotation
of the codewheel at Nominal Mouting Position and
Typical Operating Conditions.
2. For a codestrip, the Typical Values are obtained at
zero angular displacement and Typical Operating
Conditions.
3. Maximums are the worst case values predicted
over the full range of Recommended Mounting
Tolerances and Operating Conditions, with
consideration to population shift.
Parameter
Pulse Width Error
Logic State Width Error
Phase Error
Symbol Typ.
∆P
∆S
∆Φ
7
5
2
Max. Units
40
40
20
e
e
e
5
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