ESD WARNING: NORMAL HANDLING PRECAUTIONS SHOULD BE TAKEN TO AVOID STATIC DISCHARGE.
Agilent HEDS-9730, HEDS-9731
Small Optical Encoder Modules
480lpi Digital Output
Data Sheet
Description
The HEDS- 973X is a high
performance incremental
encoder module. When operated
in conjunction with either a
codewheel or codestrip, this
module detects rotary or linear
position. The encoder consists
of a lensed LED source and a
detector IC enclosed in a small
C- shaped plastic package. Due
to a highly collimated light
source and a unique
photodetector array, the module
is extremely tolerant to
mounting misalignment.
The two channel digital outputs
and 3.3V supply input are
accessed through four solder
plated leads located on 2.54mm
(0.1inch) centers.
The standard HEDS- 973X is
designed for use with an
appropriate optical radius
codewheel or linear codestrip.
Other options are available.
Please contact the factory for
more information.
Block Diagram
Figure 1
RESISTOR
LENS
LED
COMPARATORS
PHOTO-
DIODES
SIGNAL
PROCESSING
CIRCUITRY
+
Ð
A
2
A
EMITTER SECTION
CODE
WHEEL
DETECTOR SECTION
+
Ð
B
4
GND
1
VCC
3
B
CHANNEL A
CHANNEL B
Features
· Small Size
· High Resolution
· Two Channel Quadrature Output
· Linear and Rotary Applications
· No Signal Adjustment required
· TTL or 3.3V/5V CMOS Compatible
· Wave Solderable
· Lead-free Package
· -40
o
C to 85
o
C Operating
Temperature
· Single 3.3V Supply
Applications
The HEDS- 973X provides
sophisticated motion detection,
making closed loop control very
cost competitive. Typical
applications include printers,
plotters, copiers and office
automation equipment.
Note:
Agilent Technologies' encoders are not
recommended for use in safety critical
applications, e.g., ABS braking systems and
critical-care medical equipment. Please contact a
sales representative if more clarification is
needed.
2
Theory of Operation
A 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
digital outputs.
As seen in 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 is
the integrated detector circuit.
This IC consists 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
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
photodiodes 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 signal 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 2
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 degrees that an output
is high during one cycle,
nominally 180
°
e or 1/2 a 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
electrical degrees between the
center of the high state on
channel A and the center of the
high state on channel B. This
value is nominally 90
°
e for
quadrature output.
Phase Error (
): The deviation
in electrical degrees of the
phase from its 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 (R
op
): The
distance from the codewheel's
center of rotation to the optical
center (O
.
C) of the encoder
module.
Angular Misalignment Error
(E
A
): Angular misalignment of
the sensor in relation to then
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.
Output Waveforms
Figure 2.
3
Absolute Maximum Ratings
Recommended Operating Conditions
Electrical Characteristics
Encoding Characteristics
Parameter
Symbol
Min.
Max.
Units
Notes
Storage Temperature
T
S
-40
85
°
C
Operating Temperature
T
A
-40
85
°
C
Supply Voltage
V
CC
-0.5
7
Volts
Output Voltage
V
O
-0.5
V
CC
Volts
Output Current per Channel
I
OUT
-1.5
19
mA
Soldering Temperature
T
SOL
20
260
°
C
t
5 sec
Parameter
Symbol
Min.
Typ.
Max.
Units
Notes
Temperature
T
A
-40
85
°
C
Supply Voltage
V
CC
2.8
3.3 or 5
5.2
Volts
Ripple < 100mVp-p
Load Capacitance
C
L
100
pF
Pull-up Resistor
R
L
none
Recommend no pullup. Device
has integrated 2.5 k
on outputs
Frequency
f
40
kHz
Velocity (rpm) x N/60
Angular Misalignment
E
A
-2.0
0.0
+2.0
Deg.
Refer to Mounting Consideration
Mounting Position
R
M
R
OP
-0.14
(R
OP
-0.006)
mm
(inch)
Refer to Mounting Consideration
Electrical Characteristics Over the Recommended Operating Conditions. Typical Values at 25
°
C.
Parameter
Symbol
Min.
Typ.
Max.
Units
Notes
Supply Current
I
CC
12
25
40
mA
Typ. 3.3V
55
85
Typ. 5V
High Level Output Voltage
V
OH
2.4
Volts
When V
OH
= 2.4V (Min)Typ.
I
OH
= -0.4 mA @ 3.3VTyp.
I
OH
= -1.0 mA @ 5V
Low Level Output Voltage
V
OL
0.4
Volts
When V
OL
= 0.4V (Max)Typ.
I
OL
= 12 mA @ 3.3VTyp.
I
OL
= 14 mA @ 5V
Rise Time
t
r
200
ns
C
L
=25 pF
Fall Time
t
f
50
ns
Encoding Characteristics Over the Recommended Operating Conditions and Mounting Conditions These characteristics do
not include codewheel/codestrip contribution. The typical values are average over the full rotation of the codewheel
Parameter
Symbol
Typical
Maximum Units
Notes
Pulse Width Error
P
5
50
°
e
State Width Error
S
3
50
°
e
Phase Error
2
15
°
e
4
Mounting Considerations
Note: These dimensions include shaft end play and codewheel warp.
For both rotary and linear motion, angular misalignment, E
A
must be
±
1 degrees to achieve Encoding Characteristics.
All dimension for mounting the module and codewheel/codestrip should be measured with respect to two mounting posts, as shown above
Recommended Codewheel and Codestrip Characteristics
Parameter
Symbol
Min.
Max.
Unit
Notes
Window/bar Ratio
Ww/Wb
0.9
1.1
Window Length (Rotary)
L
W
1.80
(0.071)
2.31
(0.091)
mm
(inch)
Absolute Maximum Codewheel Radius
(Rotary)
R
c
Rop + 3.40
(Rop + 0.134)
mm
(inch)
Includes eccentricity errors
Center of Post to Inside Edge of Window
W1
1.04
(0.041)
mm
(inch)
Center of Post to Outside Edge of Window
W2
0.76
(0.036)
mm
(inch)
Center of Post to Inside Edge of Codestrip
L
3.60
(0.142)
mm
(inch)
E A
ALIGNMENT TAB RECEIVING HOLE
IMAGE SIDE OF
CODEWHEEL/CODESTRIP
A 0.13 mm (0.005")
CENTER OF ROTATION
MOTOR SHAFT CENTER
- A -
Rm
MAX.
Rop
Rm = Rop - 0.14 (0.006)
DIMENSIONS IN MILLIMETERS (INCHES).
L
C OF ALIGNMENT TAB
5.32
(0.209)
SEE NOTE 1
MAX.
6.30
(0.248)
MIN.
6.50
(0.256)
2X R
HOLE MIN.
2.03
(0.080)
DEEP MIN.
1.0
(0.039)
MIN.
2.03
(0.080)
DEEP MIN.
1.0
(0.039)
4.40 ± 0.13
0.17 ± 0.005
Lw
Wb
Wb
Rop
W1
W2
Rc
Ww
Ww
MAX 3.4 (0.134)
L
5
Ordering Information
Package Dimension
HEDS - 973
Lead Configurations
0 - Straight leads
1 - Bent leads
Bracket Option
50
Resolution
3 - 480 LPI
Option
Option 50
XXXXX
YYWW
C X
50
AGILENT
8.7
6.4
0.14
(OPTICAL CENTER)
2x
2.00 ± 0.02
1.4
5.0
3.9
R 1.4
10.1
7.5
4.2
3.90 ± 0.10
0.8
1.70 ± 0.15
4.2
3.0
9.8
1.8
3.8
0.5
20.2 ± 0.5
15.0
8.4
PART #
(REFER -05)
C = COUNTRY
OF ORIGIN
MARKING
(REFER -05
FOR DETAILS)
DATE CODE
12.6 ± 0.5
7.0
OPTION CODE
PIN 1 ID
CH B
V
CC
CH A
GND
LEAD THICKNESS = 0.25 mm
LEAD PITCH = 2.54 mm
10.8 ± 0.5
5.5 ± 0.3
R 2.6
Bent Version - Option 50
XXXXX
YYWW
C X
50
AGILENT
8.7
6.4
0.14
(OPTICAL CENTER)
2x
2.00 ± 0.02
R 2.6
1.4
5.0
3.9
R 1.4
10.1
7.5
4.2
3.90 ± 0.10
0.8
1.70 ± 0.15
9.2 ± 0.3
5° TYP.
4.2
3.0 ± 0.3
6.0
9.8
1.8
10.8 ± 0.5
3.8
0.5
20.2 ± 0.5
15.0
8.4
PART #
(REFER -05)
DATE CODE
12.6 ± 0.5
7.0
OPTION CODE
PIN 1 ID
CH B
V
CC
CH A
GND
LEAD THICKNESS = 0.25 mm
LEAD PITCH = 2.54 mm
C = COUNTRY
OF ORIGIN
MARKING
(REFER -05
FOR DETAILS)
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