Two Channel High Resolution
Optical Incremental Encoder
Modules
Technical Data
Features
· High Resolution: Up to 2048
Cycles per Revolution
· Up to 8192 Counts per
Revolution with 4X Decoding
· Two Channel Quadrature
Output
· Low Cost
· Easy to Mount
· No Signal Adjustment
Required
· Small Size
· -40
°
C to 100
°
C Operating
Temperature
· TTL Compatible
· Single 5 V Supply
Description
The HEDS-9000 Options T and U
and the HEDS-9100 Options B
and J are high resolution two
channel rotary incremental
encoder modules. These options
are an extension of our popular
HEDS-9000 and HEDS-9100
series. When used with a code-
wheel, these modules detect
relative rotary position. The
HEDS-9200 Option 300 and 360
are high resolution linear encoder
modules. When used with a
HEDS-9000/9100/9200
Extended Resolution
Series
codestrip, these modules detect
relative linear position.
These modules consist of a lensed
Light Emitting Diode (LED)
source and detector IC enclosed
in a small C shaped plastic
package. Due to a highly
collimated light source and
unique photodetector array, these
modules provide a highly reliable
quadrature output.
The HEDS-9000 and HEDS-9100
are designed for use with
codewheels which have an optical
radius of 23.36 mm and 11 mm
respectively. The HEDS-9200 is
designed for use with a linear
codestrip.
These components produce a two
channel quadrature output which
can be accessed through five
0.025 inch square pins located on
0.1 inch centers.
The resolution of the HEDS-9000
Options T and U are 2000 and
2048 counts per revolution
respectively. The HEDS-9100
Options B and J are 1000 and
1024 counts per revolution
respectively. The HEDS-9200
Option 300 and 360 linear
encoder modules have resolutions
of 300 and 360 lines per inch.
Consult local Agilent sales
representatives for other
resolutions.
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.
ESD WARNING: NORMAL HANDLING PRECAUTIONS SHOULD BE TAKEN TO AVOID STATIC
DISCHARGE.
2
Block Diagram
Theory of Operation
The diagram shown on the fol-
lowing page is a block diagram of
the encoder module. As seen in
this block diagram, the module
contains a single 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. 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 passes
between the emitter and detector,
causing the light beam to be
interrupted by the pattern of
spaces and bars on the code-
wheel. The photodiodes which
detect these interruptions are
arranged in a pattern that
corresponds to 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 then fed
through the signal processing
circuitry resulting in A, A, B, and
B. 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
that of channel B (90 degrees out
of phase).
Definitions
Count (N):
The number of bar
and window pairs or counts per
revolution (CPR) of the
codewheel.
1 cycle (C):
360 electrical degrees
(
°
e), 1 bar and window pair.
1 Shaft Rotation:
360 mechanical
degrees, N cycles.
Pulse Width (P):
The number of
electrical degrees that an output
is high during 1 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
°
e.
Phase (
):
The number of elec-
trical degrees between the center
of the high state of channel A and
the center of the high state of
channel B. This value is nominally
90
°
e for quadrature output.
Phase Error (
):
The deviation
of the phase from its ideal value
of 90
°
e.
Direction of Rotation:
When the
codewheel rotates in the direction
of the arrow on top of the
module, channel A will lead
channel B. If the codewheel
rotates in the opposite direction,
channel B will lead channel A.
Optical Radius (R
op
):
The dis-
tance from the codewheel's center
of rotation to the optical center
(O.C.) of the encoder module.
Output Waveforms
3
Recommended Operating Conditions
Parameter
Symbol
Min.
Typ.
Max.
Units
Notes
Temperature
T
A
-40
100
°
C
Supply Voltage
V
CC
4.5
5.0
5.5
Volts
Ripple < 100 mV
p-p
Load Capacitance
C
L
100
pF
3.3 k
pull-up resistor
Count Frequency
f
100
kHz
Velocity (rpm) x N/60
Shaft Axial Play
±
0.125
mm
±
0.005
in.
Note: The module performance is guaranteed to 100 kHz but can operate at higher frequencies. For frequencies above 100 kHz it is
recommended that the load capacitance not exceed 25 pF and the pull up resistance not exceed 3.3 k
. For typical module performance
above 100 kHz please see derating curves.
Package Dimensions
Absolute Maximum Ratings
Storage Temperature, T
S .....................................................................
-40
°
C to 100
°
C
Operating Temperature, T
A ................................................................
-40
°
C to 100
°
C
Supply Voltage, V
CC ......................................................................................
-0.5 V to 7 V
Output Voltage, V
O ........................................................................................
-0.5 V to V
CC
Output Current per Channel, I
out .................................................
-1.0 mA to 5 mA
26.67 (1.05)
HEDS-9X00
15.2
(0.60)
CL
17.27
(0.680)
20.96
(0.825)
1.85 (0.073)
8.64 (0.340)
REF.
ALIGNING RECESS
2.44/2.41 DIA.
(0.096/0.095)
2.16 (0.085)
DEEP
1.02 ± 0.10
(0.040 ± 0.004)
5.1 (0.20)
X00
YYXX
OPTION CODE
0.63 (0.025)
SQR. TYP.
2.54 (0.100) TYP.
DATE CODE
1.0 (0.04)
3.73 ± 0.05
(0.147 ± 0.002)
2.67 (0.105) DIA.
MOUNTING THRU
HOLE 2 PLACES
2.44/2.41 X 2.79
(0.096/0.095 X 0.110)
2.16 (0.085) DEEP
OPTICAL CENTER
1.52 (0.060)
20.8
(0.82)
11.7
(0.46)
8.6 (0.34)
1.78 ± 0.10
(0.070 ± 0.004)
2.92 ± 0.10
(0.115 ± 0.004)
10.16
(0.400)
5.46 ± 0.10
(0.215 ± 0.004)
OPTICAL
CENTER LINE
2.54
(0.100)
2.21
(0.087)
5.8
(0.23)
6.35 (0.250) REF.
ALIGNING RECESS
2.44/2.41 X 2.79
(0.096/0.095 X 0.110)
2.16 (0.085) DEEP
4.11 (0.162)
ALIGNING RECESS
2.44/2.41 DIA.
(0.096/0.095)
2.16 (0.085) DEEP
OPTICAL
CENTER
45°
8.81
(0.347)
11.9
(0.47)
4.75 ± 0.10
(0.187 ± 0.004)
2.9
(0.11)
1.8
(0.07)
6.9 (0.27)
V
CC
GND
5 CH. B
4 V
CC
3 CH. A
2 N.C.
1 GND
SIDE A
SIDE B
TYPICAL DIMENSIONS IN
MILLIMETERS AND (INCHES)
4
Electrical Characteristics
Electrical Characteristics over Recommended Operating Range, typical at 25
°
C.
Parameter
Symbol
Min.
Typical
Max.
Units
Notes
Supply Current
I
CC
30
57
85
mA
High Level Output Voltage
V
OH
2.4
Volts
I
OH
= -200
µ
A max.
Low Level Output Voltage
V
OL
0.4
Volts
I
OL
= 3.86 mA
Rise Time
t
r
180
ns
C
L
= 25 pF
Fall Time
t
f
40
ns
Encoding Characteristics
Encoding Characteristics over Recommended Operating Range and Recommended Mounting Tolerances.
These Characteristics do not include codewheel/codestrip contribution. The Typical Values are averages over
the full rotation of the codewheel. For operation above 100 kHz, see frequency derating curves.
Description
Symbol
Typical
Maximum
Units
Pulse Width Error
P
5
45
°
e
Logic State Width Error
S
3
45
°
e
Phase Error
2
15
°
e
Note: Module mounted on tolerance circle of
±
0.13 mm (
±
0.005 in.) radius referenced from module Side A aligning recess centers.
3.3 k
pull-up resistors used on all encoder module outputs.
R
L
= 3.3 k
pull-up
5
Derating Curves over Extended Operating Frequencies (HEDS-9000/9100/9200
Extended Series)
Below are the derating curves for state, duty, phase and V
OH
over extended operating frequencies of up to
240 kHz (recommended maximum frequency is 100 kHz). The curves were derived using standard TTL load.
40
°
C operation is not feasible above 160 kHz because V
OH
will drop below 2.4 V (the minmum TTL for logic
state high) beyond that frequency.
120
220
FREQUENCY (kHz)
-40
0
CHANGE IN PULSE WIDTH ERROR
(ELECTRICAL DEGREE)
240
-30
-20
160
-10
140
200
180
100°C
25°C
-40°C
-50
120
220
FREQUENCY (kHz)
10
50
CHANGE IN STATE WIDTH ERROR
(ELECTRICAL DEGREE)
240
20
30
160
40
140
200
180
100°C
25°C
-40°C
0
120
220
FREQUENCY (kHz)
-10
0
CHANGE IN PHASE ERROR
(ELECTRICAL DEGREE)
240
-5
160
140
200
180
100°C
25°C
-40°C
120
220
FREQUENCY (kHz)
3
5
CHANGE IN V
OH
(VOLTS)
240
4
160
140
200
180
100°C
25°C
-40°C
2
1
0
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