Prepared by: Sheldon Munns Utah State University E: samunns@ccu; T: ( 435)792-4031;

1. ECE5320 MechatronicsAssignment#01: Literature Survey on Sensors and Actuators Topic: Photoelectric sensors Prepared by: Sheldon Munns Utah State University E: samunns@cc.usu.edu; T: (435)792-4031; 3/11/2005

2. Outline • Reference list • To probe further • Major Applications • Basic working principle • Sample configuration in application • Major specifications • Limitations • Relevant issues in applications (how to choose, cost information, where to buy etc.)

3. Reference list • http://www.eatonelectrical.com • http://www.bannerengineering.com/training/subtopic.php?topicID=P1_02 • http://www.eatonelectrical.com/NASApp/cs/ContentServer?pagename=C-H/Common/AssetTemplateLink&c=Apubarticles&cid=986913539643&Sec=products • http://web6.automationdirect.com/adc/Overview/Catalog/Sensors_-z-_Encoders/ Photoelectric_Sensors • http://www.ab.com/sensors/products/photoelectric_sensors/index.html • http://www.globetron.com/aboutphoto.html • http://proximity-sensors.globalspec.com/LearnMore/Sensors_Transducers_Detectors/ Proximity_Presence_Sensing/Photoelectric_Sensors • http://www.engineeringtalk.com/guides/photoelectric-sensors.html

4. To explore further • www.eatonelectrical.com/unsecure/cms1/PG0507TE.PDF • www.bannerengineering.com • http://www.knowledge.omron.com/

5. Major Applications • Material Handling • Ensure items move along a conveyor belt in an orderly fashion • Packaging • Verify containers are filled properly, labeled properly, and have correct seals • Machine Operation • Verify that a machine is operating properly, materials are present and tooling is not broken • Paper Industry • Detect web flaws, web splice, clear web and paper presence, while maintaining high speeds

6. Major Applications • Fill-Level Detection • Box Counting • Log Diverter • Cookie Motion Detection • Lid Detection • Tamper-Evident Seal Detection • Tollbooth Control • Garage Door Control • Cut-Off Saw Control www.eatonelectrical.com

7. Major Applications • Broken Tool Detection • Broken Bit Detection • Machine Process • Tool position • Bottle Filing Detection • Process Control • Jam Detection • Conveyor System Control • Stack height Control Tool position www.eatonelectrical.com

8. Major Applications • Liquid Level Detection • Bulk Material Detection • Hopper Fill Level Control • Web Loop Control • Parts Presence/Detection • Small Parts Detection • Filter Paper Length Control • Broken Thread Detection • Hypodermic Needle Quality Control www.eatonelectrical.com

9. Basic working principle • A photoelectric sensor has two main components: an emitter and a receiver. • Emitter • The emitter contains a light source of either an LED or laser • The emitters light source is pulse modulated by an oscillator • Receiver • The receiver contains the photoelectric device such as a photodiode or phototransistor • The receiver is tuned to the frequency of the emitter, and ignores other ambient light • The receiver produces an output which occurs above or below a specified intensity www.bannerengineering.com/training

10. Basic working principle www.eatonelectrical.com/unsecure/cms1/PG0507TE.PDF

11. Basic working principle Mode of Operation www.eatonelectrical.com/unsecure/cms1/PG0507TE.PDF

12. A typical sample configuration in application • Thru-Beam • Separate light source and detector units face one another across an area. The column of light traveling in a straight line between the two lenses is the effective sensing beam. An object crosses the path has to completely block the beam to be detected www.eatonelectrical.com/unsecure/cms1/PG0507TE.PDF

13. A typical sample configuration in application • Reflex (Retro-Reflective) • The source and detector are positioned parallel to each other on the same side of the object to be detected. Another element (retro reflector) is placed across from the source and detector. When a target object passes between the source/detector unit and the retro reflector, the beam is no longer reflected and the target is sensed www.eatonelectrical.com/unsecure/cms1/PG0507TE.PDF

14. A typical sample configuration in application • Diffuse Reflective • The source and the detector are positioned on the same side of the target. The two components are aligned so that their fields of view cross. When the target moves into the area, light from the source is reflected off the target surface back to the detector www.eatonelectrical.com/unsecure/cms1/PG0507TE.PDF

15. A typical sample configuration in application • Background rejection (Perfect Prox or Fixed-Field/Adjustable Field) • This type of detection is a special type of diffuse reflective sensing. It combines high sensing power with a sharp optical cut-off. This allows the sensor to reliably detect targets regardless of color, reflectance, contrast, or surface shape, while ignoring objects just outside of the target range. This method uses two different photo-detectors. If the near signal is stronger than the far signal, the sensor output is ON. If the far signal is stronger or equal to the near sensor, the output is OFF www.eatonelectrical.com/unsecure/cms1/PG0507TE.PDF

16. Major specifications • Operating Voltage • 10 - 30 VDC • 20 - 264 VAC • Sensing Range • 250 meters (800 feet) • Optimum Range – 0.03 to 90 meters (0.1 to 300 feet) • Field of View • 0.25 inch diameter at 2 inch up to 33 inch diameter at 25 feet • Response Time • 1 to 35 ms (depending on manufacturer and application type)

17. Major specifications • Output Type (“Dark-On” or “Light-On”) • VMOS (bidirectional) • NPN (sink) • NPN and PNP (dual outputs) • DMOS • SPDT, SPST • Power dissipation • 1 to 3 Watts • Sensing Beam • Infrared • Visible Red

18. Limitations • Thru-Beam Sensors • Must purchase and mount separate emitter and receiver • Installation difficulties • Alignment can be difficult with larger distance detection zone • Retro-Reflective Sensors • Reflector must be mounted • Shiny, highly reflective, or clear objects may trick sensor • Not suitable for detecting small objects • Diffuse Sensors • Non-reflective object may decrease sensing range • Sensing distance depends on targets size, surface and shape • Background Rejection Sensors • High gloss object may produce various results

19. Relevant issues in applications • How to Choose • Application (selected few for demonstration; see Major Applications slide) • Detect color • Discriminate Surface differences • Cost (see next slide) • Where to buy (see next slide) • Detect small objects • Detect registration marks

20. Relevant issues in applications • Cost Information • Application, operating mode, and sensor type dependant • Tens to hundreds of dollars • Where to buy (just a selected few websites) • www.emxinc.com • www.SenSource.biz • www.AutomationDirect.com

21. Summary • Reference list • To probe further • Major Applications • Basic working principle • Sample configuration in application • Major specifications • Limitations • Relevant issues in applications (how to choose, cost information, where to buy etc.)