Reflective Optical Surface
Mount Encoders
Technical Data
Features
• Reflective Technology
• Surface Mount SO-8 Package
• Two Channel Quadrature
Outputs for Direction
Sensing
• Two Encoding Resolution
Options:
– 2.76 – 2.95 Lines/mm
(70 – 75 Lines/inch)
– 5.91 Lines/mm
(150 Lines/inch)
HEDR-8000 Series
HEDR-8100 Series
HEDR-8010 Series
Description
The HEDR-8000/8100 Series
encoders use reflective technol-
ogy to sense rotary or linear
position. This sensor consists of
an LED light source and a
photodetector IC in a single SO-8
surface mount package. When
used with a reflective codewheel
or codestrip, this device can sense
rotary or linear position.
NOTE: HEDR-8000 series
products are classified as MSL
Level 3.
Outline Drawing
8
7
6
5
6.2 ± 0.20
(0.244 ± 0.008)
1.97 REF.
(0.078)
REF.
PIN ONE
INDICATOR
LOCATION
0.38 ± 0.08
(0.016 ± 0.003)
5.08 ± 0.13 *
(0.200 ± 0.005)
1.84 REF.
(0.072)
1.40 ± 0.02
(0.055 ± 0.001)
1
2
3
4
1 NC
2 GND
3 A
4 V
CC
V
LED
NC
B
GND
8
7
6
5
3.94 ± 0.13 *
(0.155 ± 0.005)
1.270 TYP.
(0.050)
NOTES:
*FLASH MAY ADD 0.38 (0.015) MAX.
AT PARTING LINE.
DIMENSIONS IN MILLIMETERS (INCHES).
FOR THE 1CHANNEL HEDR-8010, PIN 6
IS CONSIDERED NC.
3.18 ± 0.13
(0.125 ± 0.005)
0.025 MIN.
(0.001)
1.52 REF.
(0.06)
0.23 ± 0.03
(0.009 ± 0.001)
0.700 R REF.
(0.0276)
LEAD COPLANARITY ± 0.051
(0.002)
0.18 ± 0.08
(0.007 ± 0.003)
0.59 MIN.
(0.023)
ESD WARNING: NORMAL HANDLING PRECAUTIONS SHOULD BE TAKEN TO AVOID STATIC
DISCHARGE.
2
The reflective surface mount
optical encoders provide two
square wave outputs in quadra-
ture for count and direction
information. These TTL
compatible outputs correspond to
the alternating reflective/non-
reflective pattern of the
codewheel or codestrip.
The HEDR-8000/8100 series
encoders can be used over a
range of codewheel and codestrip
resolutions. The HEDR-8000/
8100 reflective encoder can
operate from 2.76 to 2.95 lines
per mm (70 to 75 lines per inch).
The HEDR-8100 can be used with
a codewheel or codestrip with
150 lines per inch (5.91 lines
per mm).
it ideal for high volume
applications. Its small size and
surface mount capability make it
ideal for printers, copiers, card
readers, and consumer product
applications.
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.
As seen in the block diagram, the
HEDR-8000/8100 series has three
key parts: a single light emitting
diode (LED) light source, a
photodetector IC with a set of
uniquely configured photodiodes,
and a pair of lenses molded into
the package. The lens over the
LED focuses light onto the
codewheel or codestrip. Light is
either reflected or not reflected
back to the lens over the
photodetector IC.
As the codewheel rotates or
codestrip passes by, an alternat-
ing pattern of light and dark
corresponding to the pattern of
the codewheel falls upon the
photodiodes. This light is used to
produce internal signals A and
A,
and B and
B.
As part of this
“push-pull” detector system, these
signals are fed through compara-
tors to produce the final outputs
for channels A and B.
Theory of Operation
The HEDR-8000/8100 series
combines an emitter and a
detector in a single surface mount
SO-8 package. When used with a
codewheel or codestrip, the
reflective sensors translates
rotary or linear motion into a two
channel digital output.
Applications
The HEDR-8000/8100 series
provides two channel motion
sensing at a very low cost, making
Block Diagram
V
LED
GND
V
CC
CH A
CH B
SIGNAL
PROCESSING
CIRCUITRY
R
CODEWHEEL
OR
CODESTRIP
GND
3
Definitions
Count (N):
For rotary motion,
the number of bar and window
pairs or counts per revolution
(CPR) of the codewheel. For
linear motion, the number of bar
and window pairs per unit length
(lines per inch [LPI] or lines per
mm [LPmm]).
One Cycle (C):
360 electrical
degrees (°e), 1 bar and window
pair.
One Shaft Rotation:
360
mechanical degrees, N cycles
(rotary motion only).
Line Density:
The number of
reflective and non-reflective pairs
per unit length, expressed as
either lines per inch (LPI) or lines
per mm (LPmm).
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 (φ):
The number of
φ
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.
Phase Error (
∆
φ
):
The deviation
in electrical degrees of the phase
from its ideal value of 90°e.
Direction of Rotation:
When the
codewheel or codestrip moves in
the direction from pin 1 to pin 4,
as viewed when looking down on
the lenses, channel B will lead
channel A. If the codewheel or
codestrip moves in the opposite
direction, channel A will lead
channel B.
Optical Radius (Rop):
For rotary
motion, the distance from the
codewheel’s center of rotation to
the center line connecting the two
lenses of the encoder.
Gap (G):
The distance from the
top of the package to the surface of
the reflective codewheel or
codestrip.
Specular Reflectance (R
f
):
a
measure of a surface’s reflective
finish. This is quantified by the
amount of light reflected when hit
with an incident beam. A device
called a scatterometer is used to
quantify specular reflectance on a
percent scale. (Contact factory for
more information.)
Radial and Tangential
Misalignment Error (E
R
, E
T
):
For rotary motion, mechanical
misalignment in the radial and
tangential directions relative to the
codewheel.
Angular Misalignment Error
(E
A
):
angular misalignment of the
sensor in relation to the tangential
direction. This applies for both
rotary and linear motion.
RADIAL
TANGENTIAL
E
A
HEDR-8000
HEDR-8000
SHAFT
SHAFT
CODEWHEEL
CODEWHEEL
Output Waveforms
C
P
ALL FOUR STATES (S1 TO S4)
ARE MAINTAINED.
CH. A
AMPLITUDE
S1
S2
S3
S4
φ
CH. B
CODEWHEEL ROTATION OR LINEAR MOVEMENT
4
Absolute Maximum Ratings
Storage Temperature, T
S
Operating Temperature, T
A
Supply Voltage, V
CC
Output Voltage, V
O
Output Current per Channel, I
OUT
-40°C to 85°C
-10°C to 85°C
-0.5 V to 7 V
-0.5 V to V
CC
-1.0 mA to 5 mA
Note:
Exposure to extreme light intensity (such as from flashbulbs or spotlights) can
cause permanent damage to device.
Recommended Operating Conditions
Parameter
Temperature
Supply Voltage
LED Current
Load Capacitance
Count Frequency
Radial Misalignment
Tangential Misalignment
Angular Misalignment
Codewheel or Codestrip
Gap
Symbol
T
A
V
CC
I
LED
C
L
f
E
R
E
T
E
A
G
G
Codewheel or Codestrip
Specular Reflectance
Codewheel/Codestrip Tilt
Codewheel/Codestrip
Resolution
R
f
C
T
LPmm
(LPI)
LPmm
(LPI)
Min.
-10
4.5
13
Typ.
5.0
15
Max.
85
5.5
18
Units
°C
Volts
mA
pF
kHz
mm
(in.)
mm
(in.)
deg.
mm
(in.)
mm
(in.)
Notes
Ripple < 100 mVp-p
See “Current Limiting
Resistor for LED”
2.7 KΩ Pull-Up
Velocity (rpm) x N/60
100
15
±
0.38
(± 0.015)
±
0.38
(± 0.015)
0
±
1.5
1.52
2.03
2.54
(0.060) (0.080) (0.100)
1.02
1.52
2.03
(0.040) (0.060) (0.080)
60%
0
2.76
(70)
5.91
150
1
2.95
(75)
HEDR-8000
HEDR-8010
HEDR-8100
As Measured on TMA
µscan
Scope (see Note 1)
deg.
lines/mm
(lines/in.)
lines/mm
(lines/in.)
HEDR-8000
HEDR-8010
HEDR-8100
Notes:
1. Contact factory for more information regarding measurement of specular reflectance.
Encoding Characteristics
Encoding Characteristics Over the Recommended Operating Conditions and Mounting Conditions.
Parameter
Pulse Width Error
Pulse Width Error (Ch.A,Ch.B)
Phase Error
Pulse Width Error (Ch.A,Ch.B)
Phase Error
Symbol
∆P
∆P
∆φ
∆P
∆φ
Typical
15
16
10
15,25
12
Maximum
55
75
60
55,75
60
Units
°e
°e
°e
°e
°e
Notes
HEDR-8010
HEDR-8100
HEDR-8100
HEDR-8000
HEDR-8000
Note:
Typical Value was obtained at typical condition. Maximums were obtained over all range of recommended operating condition and
mounting condition.
5
Electrical Characteristics
Electrical Characteristics Over Recommended Operating Conditions. Typical Values at 25°C.
Parameter
Supply Current
High Level Output Voltage
Low Level Output Voltage
Rise Time
Fall Time
Symbol
I
CC
V
OH
V
OL
t
r
t
f
2.4
150
50
0.4
200
60
Min.
Typ.
2.2
Max.
5.0
Units
mA
V
V
ns
ns
I
OH
= -40
µA
min.
I
OL
= 3.86 mA
C
L
= 25 pF
R
L
= 2.7 KΩ
Notes
Current Limiting Resistor
for LED
A resistor to limit current to the
LED is required. The recom-
mended value is 220
Ω
(±10%)
and should be placed in series
between the 5 V supply and pin 8
of the device (V
LED
). This will
result in an LED current of
approximately 15 mA.
Recommended Codewheel and Codestrip Characteristics
W
b
L
w
W
w
R
OP
L
w
W
w
W
b
Parameter
Window/Bar Ratio
Specular Reflectance
Line Density
Symbol
Ww/Wb
R
f
LPmm
(LPI)
LPmm
(LPI)
Lw
Window Length
Min.
0.9
60
–
2.76
(70)
5.91
(150)
1.80
(0.071)
Max.
1.1
85
10
2.95
(75)
7.09
(180)
2.31
(0.091)
Units
Notes
Reflective Bars
Non-reflective Bars
HEDR-8000
HEDR-8010
HEDR-8100
mm
(inches)
lines/mm
(lines/inch)
lines/mm
(lines/inch)
mm (inches)
Contact factory for further information on compatible codewheel and codestrips.
