US Digital

HEDS Transmissive Optical Encoder Module

Overview

  • Two channel quadrature output with optional index pulse
  • TTL Compatible
  • Single +5V supply
  • Resolutions up to 2048 CPR (8192 PPR)
  • -40C to 100C operating temperature

HEDS is a transmissive optical encoder module. This module is designed to detect the rotary or linear position when used together with a codewheel or linear strip. The HEDS module consists of a lensed LED source and a monolithic detector IC enclosed in a small polymer package. The HEDS module uses phased...

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Product Specifications

CPI-
CPR		1" Disk
Non-index		1" Disk
With Index		2" Disk
Non-index		2" Disk
With Index		Linear Strip
Non-index
50 HEDS-9100-S00 HEDS-9140-S00  -  -  -
96 HEDS-9100-C00* HEDS-9140-C00*  -  -  -
100 HEDS-9100-C00 HEDS-9140-C00 HEDS-9100-S00* HEDS-9140-S00*  -
110 HEDS-9100-C00*  -  -  -  -
120 HEDS-9100-C00*  -  -  -  -
180  -  -  -  - HEDS-9200-Q00
192 HEDS-9100-E00* HEDS-9140-E00*  -  -  -
200 HEDS-9100-E00 HEDS-9140-E00 HEDS-9100-C00* HEDS-9140-C00*  -
250 HEDS-9100-F00* HEDS-9140-F00*  -  -  -
256 HEDS-9100-F00* HEDS-9140-F00  -  -  -
300  -  -  -  - HEDS-9200-300
360 HEDS-9100-G00 HEDS-9140-G00  -  - HEDS-9200-360
400 HEDS-9100-H00 HEDS-9140-H00 HEDS-9100-E00* HEDS-9140-E00*  -
500 HEDS-9100-A00 HEDS-9140-A00 HEDS-9000-A00 HEDS-9140-F00*  -
512 HEDS-9100-I00 HEDS-9140-I00 HEDS-9000-A00*  -  -
540 HEDS-9100-I00*  -  -  -  -
1000 HEDS-9100-B00  - HEDS-9000-B00 HEDS-9040-B00  -
1016 HEDS-9100-J00*  -  -  -  -
1024 HEDS-9100-J00  - HEDS-9000-J00 HEDS-9040-J00  -
2000  -  - HEDS-9000-T00 HEDS-9040-T00  -
2048  -  - HEDS-9000-U00 HEDS-9040-T00  -

*Some modules can be used with other-than-native OD and/or CPI/CPR while maintaining specified tolerances.

ParameterMin.Max.UnitsNotes
Temperature -40 100 C
Supply Voltage 4.5 5.5 Volts Ripple (<100mV P-P)
Load Capacitance - 100 pF
Count Frequency - 100 kHz rpm/60 x cycles/rev.
  • Specifications apply over entire operating temperature range.
  • Typical values are specified at Vcc = 5.0Vdc and 25°C.
ParameterMin.Typ.Max.UnitsNotes
Output Voltage -0.5 - Vcc Vdc
Supply Current
(Index or 1" >=1000 CPR or 2" >=2000 CPR only)		 30 57 85 mA
Supply Current
(All Other Resolutions)		 - 17 40 mA

Low-level Output
(Index or 1" >=1000 CPR or 2" >=2000 CPR only)

 - - 0.5 Vdc IOL = 8.0mA max.
Low-level Output
(All Other Resolutions)		 - - 0.4 Vdc IOL = 3.2mA max.
High-level Output
(Index or 1" >=1000 CPR or 2" >=2000 CPR only)		 2.4 - - Vdc IOH = -200uA max.
High-level Output
(All Other Resolutions)		 2.4 - - Vdc IOH = -40 uA max.
Output Current Per Channel -1.0 - 5.0 mA

Encoding Characteristics:

  • Specifications apply over entire operating temperature range.
  • Values are for the worst error over full rotation.
  • Refer to Timing Diagram below.
ParameterSymbolMin.Typ.Max.Units
Cycle Error
(2000 or 2048 CPR only)
- 3.0 7.5 °e
Cycle Error
(All Other Resolutions)
- 3.0 5.5 °e
Symmetry
(2000 or 2048 CPR only)
130 180 230 °e
Symmetry
(All Other Resolutions)
150 180 210 °e
Quadrature
(2000 or 2048 CPR only)
40 90 140 °e
Quadrature
(All Other Resolutions)
60 90 120 °e
Index Pulse Width
(2000 or 2048 CPR only)		 Po 40 90 140 °e
Index Pulse Width
(All Other Resolutions)		 Po 60 90 120 °e
Ch. I Rise After Ch. B or Ch. A Fall
(2000 & 2048 CPR only)		 t1 10 450 1500 ns
Ch. I Rise After Ch. B or Ch. A Fall
(All Other Resolutions)		 t1 -300 100 250 ns
Ch. I Fall After Ch. B or Ch. A Rise
(2000 & 2048 CPR only)		 t2 10 250 1500 ns
Ch. I Fall After Ch. B or Ch. A Rise
(All Other Resolutions)		 t2 70 150 1000 ns

Timing Diagram:

timing_diagram_1.gif

CPR (N): The number of Cycles Per Revolution.

One Shaft Rotation: 360 mechanical degrees, N cycles.

One Electrical Degree (°e): 1/360th of one cycle.

One Cycle (C): 360 electrical degrees (°e). Each cycle can be decoded into 1 or 4 codes, referred to as X1 or X4 resolution multiplication.

Symmetry: A measure of the relationship between (X) and (Y) in electrical degrees, nominally 180°e.

Quadrature (Z): The phase lag or lead between channels A and B in electrical degrees, nominally 90°e.

Index (CH I.): The index output goes high once per revolution, coincident with the low states of channels A and B, nominally 1/4 of one cycle (90°e).

Position Error: The difference between the actual shaft position and the position indicated by the encoder cycle count.

Cycle Error: An indication of cycle uniformity. The difference between an observed shaft angle which gives rise to one electrical cycle, and the nominal angular increment of 1/N of a revolution.

ParameterTorque
Mounting Screws 3.5 in.-lbs

US Digital is the designer and manufacturer of the EM1 transmissive optical encoder module. The design of the EM1 provides electrical and mechanical compatibility with the Agilent HEDS-9000, HEDS-9100, HEDS-9200, HEDS-9040, and HEDS-9140 series modules.

The process of switching from the HEDS to the EM1 module should not require any mechanical or electrical changes. Simply use the EM1 and matching codewheel in place of the HEDS module and codewheel. The EM1 has a built-in index channel available on all resolutions, for both rotary disks and linear strips. The EM1 uses a US Digital designed codewheel with 2 tracks rather than 3 tracks for index versions. Non-index codewheels are interchangable between the EM1 and HEDS modules. The EM1 offers improved output drive capability and will source and sink 8mA at TTL levels. 

Physically, the EM1 has no external wire loops which can interfere when mounting. The connector pins are 0.051" shorter than HEDS modules, while still providing .30" insertion depth. US Digital's EM1 offers custom and special resolutions.

Product Description

Restriction of Hazardous Substances

HEDS is a transmissive optical encoder module. This module is designed to detect the rotary or linear position when used together with a codewheel or linear strip. The HEDS module consists of a lensed LED source and a monolithic detector IC enclosed in a small polymer package. The HEDS module uses phased array detector technology to provide superior performance and greater tolerances over traditional aperture mask type encoders.

The HEDS module provides digital quadrature outputs. It is available with a third index channel output on some resolutions. Power is supplied from a single +5Vdc source.

The resolution of the modules and encoder disks or linear strips must match. Two mounting holes are provided to accept 4-40 machine screws.

For open collector and higher voltage applications, add the PC3 cable driver, or for differential cable driver outputs, add the PC4 cable driver. Encoder disks, linear strips, quadrature decoder chips, counter chips, computer interface boards, mating connectors and cables are also available.

Product Notes
  • US Digital warrants its products against defects in materials and workmanship for two years. See complete warranty for details.
  • Please note that optical encoder rotary disks, linear strips and modules are sold separately.
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Product Part Number
Quantity Price
1 $26.25
10 $23.35
50 $19.92
100 $17.65
Over 100 Call for quote
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For your convenience, use the above part number to order via phone 800.736.0194

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