Upload
cui-inc
View
615
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Explains how panel mount rotary encoders work and the differences between mechanical and optical encoder technologies. Also covers CUI's ACZ and C14 series encoders and typical applications for these. For more information on the ACZ series visit: http://www.cui.com/ACZ_Panel_Mount_Encoders For more information on the C14 series visit: http://www.cui.com/C14_Panel_Mount_Optical_Encoders
Citation preview
© 2012 CUI Inc
Panel Mount Encoders
© 2012 CUI Inc
IntroductionPurposeThe purpose of this training module is to familiarize you with the principles of panel mount rotary encoders and the key features of the ACZ and C14 series available through Digi-Key.
Objectives To explain how panel mount rotary encoders fundamentally work and provid
definitions to key specification and principles
Describe the difference between mechanical and optical encoder technology
Describe the key features of CUI’s ACZ and C14 series
Detail typical applications these encoder are used in
Content: 19 pages
Learning Time: 15 minutes
© 2012 CUI Inc
What Are Encoders?
Encoders are a type of sensor designed to provide rotation information
An encoder sends out a pulse each time it is moved a certain number of degrees
A microprocessor counts these pulses and calculates rotation
© 2012 CUI Inc
What are panel mount encoders?
Panel mount encoders are designed for use in human interface applications
They provide an accurate and inexpensive method for user manipulation of electronic products
© 2012 CUI Inc
Why an Encoder?
Encoders: Consistent Accurate Digital
Potentiometers: Inconsistent Accuracy is hardware dependent Analog
DIGITAL
vs
ANALOG
© 2012 CUI Inc
ApplicationsPanel mount encoders, like the ACZ and C14 series, are ideal for applications in many industries
Defense & Aerospace
Simulators, cockpit control Handheld, mobile, fixed radios Ground control, weapon control Marine applications
Rescue & Security
CCTV (closed circuit TV) Handheld, mobile, fixed radios Rescue tools and equipment
Infrastructure Control
Traffic control for car, railway Traffic information systems Power plant and energy distribution Communication network control
Light & Sound
Studio mixers and cutting PA and on-stage equipment On-site transmission equipment
© 2012 CUI Inc
Applications continued
Industrial Automation
Motor drives PLCs and control systems Remote control units Tooling machines
Building & Facilities
Heater and air conditioning Lock and access systems Remote control units Illumination control
Research & Science
Electronic lab and instrumentation Meteorology and geology measures Petro and pharmaceutical measures Other physical measures
Transportation Vehicle
Construction machinery cockpits Remote control for construction Rail car and ship cockpits Car side passenger information
Consumer
Audio equipment/home entertainment White goods (Washer/Dryer) Espresso machine Fitness and wellness equipment
Medical
Surgery tools Analysis devices X-ray, ultrasonic and MRI Life recovery and sustainment
© 2012 CUI Inc
Important Specifications
PPR(pulses per revolution)
The number of square wave pulses per revolution of the encoder shaft per channel, this measure is also known as “resolution”
CPR (counts per revolution)
The number of quadrature state changes per revolution, or PPR x 4
Detents
These prevent unwanted rotation and provide a “click” every time the shaft is rotated a certain number of degrees
Push Switch
The encoder shaft can be pressed down to actuate a simple SPST switch
© 2012 CUI Inc
Pulses
1 full cycle
Pulse = One full square wave cycle. A transition from low to high to low.
© 2012 CUI Inc
Output Square wave output over two channels
The signals are identical except they are slightly offset
By detecting which signal is leading, the direction of rotation can be monitored
Clockwise Rotation Counter-Clockwise Rotation
© 2012 CUI Inc
Output Continued
Microcontrollers use differentmethods for counting
Pulses on one channel 1 count per pulse
Pulses on two channels Using both channels doubles the
number of counts
Quadrature state changes 4 counts per cycle
Quadrature Truth Table
PositionState
A B
1 0 0
2 1 0
3 1 1
4 0 1
1 0 0
2 1 0
3 1 1
4 0 1
1 0 0
2 1 0
3 1 1
4 0 1
© 2012 CUI Inc
Sinking and Sourcing
Sinks provide paths to ground
Sources provide paths to a voltage
A sink needs a source to work and vice versa A faucet needs a sink, and a sink needs a faucet
CUI Inc panel mount encoders sink current, requiring a source to work properly
© 2012 CUI Inc
Mechanical vs. Optical Technology
Mechanical Inexpensive Rugged Variable source
voltage levels
Optical Cleaner Output Longer lasting Less external circuitry Higher resolution
© 2012 CUI Inc
How Optical Encoders Work
Attached to the shaft, inside the encoder body is a wheel a with slits cut in at regular intervals
A beam of light is aimed across the code wheel
A detector on the other side is used to tell if the beam is being transmitted through a slit or blocked by the material between slits
As the shaft is turned, the light beam is alternately blocked (state=0) or transmitted (state=1)
© 2012 CUI Inc
Features Compact – 15 mm width
Rugged – Metal body construction and optional IP65 rating
Quadrature output
Clean square wave output
Life – 1,000,000 cycles
C14 Optical Encoder Series
Available options 16 & 32 PPR (64 & 128 CPR)
Push switch or no switch
Detents or no detents
6 different termination types
3.175, 6, 6.35 mm shaft diameter
5 different mounting types
Optional IP65 rating
© 2012 CUI Inc
How Mechanical Encoders Work A code wheel with contacts turns inside the unit
as the encoder shaft is turned
When contact is made the voltage at the output is pulled up
When contact is broken the output is pulled low
Stationary contact
Moving contact
© 2012 CUI Inc
Switch Bounce and Debounce in Mechanical Encoders
An ideal switch will have two states, on and off, and it will instantlymove to one of these positions
In the real world a switch will hover, or bounce, between these states during switching operations
To compensate for this effect, switches need “debounce” circuitryand/or programming
Ideal Real world Bounce
© 2012 CUI Inc
ACZ Mechanical Encoder Series
Available options
12, 15, 20 ,30 PPR
Push switch or no switch
Detents or no detents
15, 20, 25 mm shaft length
Horizontal or vertical mounting
© 2012 CUI Inc
Summary CUI’s ACZ and C14 series encoders are designed to provide an accurate
and inexpensive method for user input across a wide range of applications
The ACZ series utilizes mechanical encoder technology, offering a rugged, low cost solution
The C14 series utilizes optical encoder technology, offering a clean signal and long cycle life for high precision applications
Learn More
View CUI’s panel mount encoders
View CUI’s full Encoder product portfolio