Lexmark Rotary Shaft Encoder Team members: Scott Blakely Jeff Clover Luke Spicer Kurt Thomas Dustin Webb

 Review project objectives and system requirements  Background and derived requirements  Static test results  Conclusions drawn  Dynamic test results  Conclusions and part recommendations  Summary Overview

 Characterize the reflective approach with multiple devices and a variety of films and substrate materials on the encoding disk  Carefully control the emitter/detector array to encoding disk spacing during testing  Optimize the reflective design to achieve the best performance at the lowest cost possible Project Objectives

Previous Transmissive Approach

 Converts shaft angular position to an analog electrical output  Output is used to determine shaft angular position, RPM, etc.  Opto-Reflective array is used to produce the analog electrical output Reflective Operational Concept Diagram courtesy of previous UofL CAPSTONE Group IR LED Photo Transistor Encoding Disk

 Input  24 VDC motor power, 5 or 3.3 VDC, and Ground  Output  High ≥ 2.2 VDC; Low ≤ 0.6 VDC  Pulse width ≥ 17 μsec  Motor Speed  Max ≈ /- 150 RPM; Min ≈ 200 RPM  Size of PCB  Length = 37.0 mm, Width = 30.5mm, Height = 14.0mm  All materials must adhere to UL Material Flame Class 94V0 System Requirements

 Data sheets show for sensor to be most effective:  Industry Standard = 1mm from encoding disk  Optimal range = 0.6 ≤ x ≤ 0.8 mm  Similar graph for Fairchild and Sharp Derived Requirement Figure from OSRAM SFH 9201 data sheet.

Test Fixture

 Designed based around moving the sensor instead of the disk  Calipers chosen based on level of accuracy and price  Modeled in SolidWorks  Screwing components used to move the calipers in small increments

Test Fixture  Can measure +/-.02mm  Vertically adjustable  Fixture was rapid prototyped  Rubber band acts as a retracting mechanism  Allows for the disk to be stationary by moving the sensor to and from the disk while motor is running.  Secured so the sensor is parallel to disk.

 We tested multiple sensors from each company (Sharp, ORSRAM, & Fairchild)  Incremented the spacing between opto-reflective array and encoding disk to find optimum range  Noted reproducibility characteristics for each sensor and compared normalized data Static Testing

Fairchild Static Test Results

Normalized Fairchild Data

 Verified I c /I max vs. Distance curves from datasheets  Fairchild is the overall favorite  Performance  Reproducibility  Cost Reduction  Front runners for encoding disk design  8-window PCB with copper  8-window photo paper  On to dynamic testing!!!! What we know now

Dynamic Testing

 8-window versions  PCB with copper plating  White paper  48-window versions  PCB with copper plating  White paper Test Combinations  64-window versions  PCB with copper plating  Stamped Aluminum  Sputtered Gold  Black Nylon  White Painted

Fairchild QRE-1113 #18 Window Disk PCB SubstrateBare Copper Surface Speed = 6,000 RPM 2.2 Volts 0.6 Volts 540 μs High Time Pulse Width 570 μs Low Time Pulse Width *5 VDC Applied

Fairchild QRE-1113 #18 Window Disk PCB SubstrateBare Copper Surface Speed = 200 RPM 2.2 Volts 0.6 Volts 25 ms High Time Pulse Width 20.4 ms Low Time Pulse Width

Fairchild QRE-1113 #348 Window Disk PCB SubstrateBare Copper Surface Speed = 200 RPM 2.2 Volts 0.6 Volts 1.36 ms High Time Pulse Width 1.48 ms Low Time Pulse Width *5 VDC Applied

Fairchild QRE-1113 #348 Window Disk PCB SubstrateBare Copper Surface Speed = 6,000 RPM 2.2 Volts 0.6 Volts *Signal did not meet requirements *5 VDC Applied

Fairchild QRE-1113 #3 8 Window DiskWhite Paper Speed = 6,000 RPM 2.2 Volts 0.6 Volts 560 μs High Time Pulse Width 470 μs Low Time Pulse Width *3.3 Volts Applied

FairchildOSRAMSharp 64 PCB w/ CuX* Sputtered AuX* White PaintedXXX Stamped AlX* White PaperXXX 48 PCB w/ CuX*XX White PaperX* 16 PCB w/ Cu√√√ 8 PCB w/ Cu√√√ White Paper√√√ Summary of Dynamic Results * Indicates signal did not meet max RPM requirements

 Opto-reflective array to encoding disk spacing  From static tests, ideal spacing ≈ 0.7 +/- 0.1 mm  Can still see clear useable signal out to 1.2 mm  Best sensor  Fairchild outperformed Sharp and OSRAM during dynamic testing  Best encoding disk  8 & 16 window Copper PCB Conclusions

 Power Supply  We were able to meet requirements at 5 VDC and 3.3 VDC using best combination of sensor/disk  64 window designs did not meet all requirements  Suggestion for further study:  Study the effects of window width in higher window designs  Study the effects of life testing and aging of opto- reflective array Conclusions (cont’d)

 Reviewed project objectives  Reviewed system requirements and primary derived requirement  Improved Test Fixture  Static testing showed us optimal spacing  Dynamic testing showed us best combination of sensor array and encoding disk Summary

Prototype

Questions?

OSRAM Static Test Results

Normalized OSRAM Data

Sharp Static Test Results

Normalized Sharp Data

Fairchild QRE-1113 #3 8 Window DiskWhite Paper Speed = 6,000 RPM 2.2 Volts 0.6 Volts 460 μs High Time Pulse Width 510 μs Low Time Pulse Width *5 VDC Applied