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Agenda. Introduction 12:00 Ozone Fan/Filter Assembly 12:15 Monitoring Charge on Photoconductor 12:30 LED Exposure System 12:45 Paper Delivery System 1:00 High Visibility Warning Signs 1:15 Camera System 1:30 Transfer Roller Speed Measurement 1:45 Labview Control Interface 2:00

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Presentation Transcript
  • Introduction 12:00
  • Ozone Fan/Filter Assembly 12:15
  • Monitoring Charge on Photoconductor 12:30
  • LED Exposure System 12:45
  • Paper Delivery System 1:00
  • High Visibility Warning Signs 1:15
  • Camera System 1:30
  • Transfer Roller Speed Measurement 1:45
  • Labview Control Interface 2:00
  • Additional Issues 2:15
detailed design review p09503 electrophotographic development and transfer station

Detailed Design ReviewP09503 – Electrophotographic Development and Transfer Station

Friday, October 31, 2008



introduction to electrophotography
Introduction to Electrophotography
  • Electrophotography is base technology used in modern day copy printers
  • Six Step Process
    • Charging
    • Exposure
    • Development
    • Transfer
    • Fusing
    • Cleaning
  • EDTS only includes first four
project introduction
Project Introduction
  • EDTS will contribute to understanding of current EP technology
    • Manipulation of input parameters
  • Objective is to take existing EDTS and
    • Make it functional
    • Improve Usability
    • Automate Control of Machine
    • Additional Performance Improvements
project deliverables
Project Deliverables
  • 1 – An inventory and status of current sub-systems, including needed support systems.
  • 2 – A working EDTS.
  • 3 – Demonstrably improved device safety.
  • 4 – An improved user interface (includes control and display functions)
  • 5 – Device documented for use, maintenance and upgrade of the device (User & Lab Technician Manual)
  • 6 – Demonstrably Improved Sensing and Control Subsystem
system level overview
System Level Overview
  • Photoconductor
    • Hold Photosensitive Material
    • Photosensitive Material
      • Increased conductivity during exposure to light
    • Traverse EDTS
    • Interact Photosensitive Material with
      • Charge
      • Discharge
      • Development
      • Transfer
system level overview1
System Level Overview
  • Charging
    • Establish an electrical field within the area of the Photoconductor
    • Photoconductor passes at very small distance
    • Corona
      • Wires subjected to up to 10,000 Volts
    • Grid
      • Distribute charge of corona
system level overview2
System Level Overview
  • Exposure
    • Expose Photosensitive material to light
    • Reduce charge on exposed areas
    • Electrostatic latent image remains
system level overview3
System Level Overview
  • Development
    • Deposit charged toner particles onto charged areas of photosensitive material
    • Magnetic Developer creates a “wall” of toner and developer
system level overview4
System Level Overview
  • Transfer
    • Transfer toner from photosensitive material to paper
    • Transfer Drum is Charged
    • Two Steps
      • Toner to Transfer Drum
      • Transfer Drum to Paper
system level functional diagram
System Level Functional Diagram
  • Functional Diagram shows areas for improvement
customer needs
Customer Needs
  • 1. Is Operational
  • 2. Is Safe
  • 3. Minimizes user intervention during Charging
  • 4. Minimizes user intervention during Discharge
  • 5. Minimizes user intervention during Development
  • 6. Minimizes user intervention during Transfer
  • 7. Minimizes user intervention during maintenance
  • 8. Can monitor key process parameters
  • 9. Automation of Parameter Settings
  • 10. Can operate and monitor machine from one interface
  • 11. Easy to learn to use
  • 12. Areas for system upgrades are identified and documentation for upgrade procedures available where applicable
  • 13. Maintenance of system is documented
  • 14. Both drawings and Bills of Materials document device
  • 15. Operation of Device Is Documented
  • 16. Toner clean up
  • 17. Inventory and Status Report of current systems
  • 18. Vary charging voltage
  • 19. Vary charging current
  • 20. Vary exposure
  • 21. Can accommodate different toner materials
  • 22. Vary development voltage
  • 23. Vary development current
  • 24. Can use multiple toner stations
  • 25. Vary transfer voltage
  • 26. Vary transfer current
  • 27. Improve exposure subsystem
  • 28. Monitor charge of the Photoconductor
  • 29. Incorporate other manufacturers development systems
  • 30. Paper delivery system Ability to accommodate different types of media
engineering specifications
Engineering Specifications
  • Please see documentation
  • Reduce and Secure Ozone Test Stand
    • Ozone hazardous to humans if exposed to enough
    • Law states maximum ozone in A/C Space is 0.05 ppm [1]
    • >0.200 ppm increases risk of health issues [1]
  • Two Options
    • Verify current system or
    • Implementation of further improvement to control Ozone Levels


proof of concept
Proof of Concept
  • Measure ozone at various locations to determine if measurements are within limits
  • Test/Experimental – TBD due to insufficient equipment

= Test Areas

proof of concept2
Proof of Concept
  • Set values
    • 0-1.0 kV at increments of 0.1 kV for Grid and Corona
    • 1-10kV at increments of 0.5 kV for Grid and Corona
  • Will Measure
    • Ozone Produced without Fan
    • Ozone Produced with Fan
  • At original height and two inches higher
proof of concept3
Proof of Concept
  • Material Selected Al 2024
  • Stress found to be ~520 psi
  • Less than Yield Stress of 45ksi
  • Less than Ultimate Stress of 65ksi
  • Output quality determined by functionality of each subsystem
  • Monitoring charge of photosensitive material will help characterize exposure input noise source
  • Can also help create charge v. exposure plot after measurement
  • Measuring device is Trek 344 Electrostatic Volt Meter (ESVM)
  • Probe functions like capacitor that charges up to same level as object being measured
drawings schematics
  • Probe must be placed 2mm from PC surface
  • Cannot be held by hand
    • Could result in short or shock
  • Position should be fixed during measurement
  • Existing Camera Mounts used
    • Allows for easy adjustment
    • Intermediate probe mount needed to attach probe to camera mount
proof of concept4
Proof of Concept
  • Mylar used for testing instead of PC Material
    • Mylar not sensitive to light, no exposure necessary
  • Mylar glued to PC plate and driven down EDTS
  • Begin with 500 Volts at charging
  • Measurements taken after charging and exposure
led exposure system

LED Exposure System

Rachel Chrash

  • LED Print Heads used in copiers and printers to expose Photosensitive Material are commonly used
  • LED Exposure system to replace current incandescent system
  • Advantages
    • More versatile and reliable light source
    • Low Power Consumption
    • Longer Bulb Life
    • No potential for overheat
    • Inexpensive to replace
current system vs led system
Current System vs. LED System
  • Current System
    • Incandescent light uses collimating lens to collect light and direct toward image plane
  • LED System
    • Provide more direct source of light to image plane
relative intensity vs wavelength
Relative Intensity vs. Wavelength
  • Plot shows intensity, or relative spectral power distribution w.r.t. wavelenth
  • PC Material most sensitive to blue light which has shortest wavelength
  • Explains why system can be successfully operated in yellow light without large impact on PC exposure
proof of concept5
Proof of Concept
  • Most successful exposure results in even light distribution across entire image plane
  • Three light sources tested using Gossen PanLUX Analog Lux Meter
  • LUX = intensity (lumen/m2)
  • Grid constructed over image plane at level where exposure takes place
  • Light intensity and uniformity measured every 1x1 inch
  • Pinpoint measurements were then taken of the current system
    • 2x2 LED Array
    • 2x3 LED Array
mounting system
Mounting System
  • Array can be contained inside projector casing
    • Located at bottom or
    • Located on Small Shelf at height TBD by testing
  • Larger than 3x3 array could pose issue due to size
    • Modify Projector Case
  • Existing roller system requires manually catching paper after application of toner from roller
  • Possible risks of manual handling
    • Shock Short from High Voltage Roller
    • Pinch Point of Rollers and Pneumatics
    • Marred Image Quality
  • Paper Delivery System Solution
    • Hold 4.25” x 5.5” paper samples
    • Fit in available space
  • Purpose of warning signs
    • Alert user to specific hazard
    • Identify how hazard can be avoided
  • Remove current warning signs
  • Replace with ISO designed signs
  • Add new ISO signs where needed
new high voltage sign
New High Voltage Sign

Old High Voltage Sign

New High Voltage Sign

Actual Height of Sign = 1.5”

pinch point sign
Pinch Point Sign

Actual Height of Sign = 1.5”

system warning signs
System Warning Signs

Actual Height of Sign = 1.25’

before and after
Before and After



proof of concept9
Proof of Concept
  • Signs Designed under guidance of ISO-3864
    • Establishes the safety identification colors and design principles for safety signs to be used in workplaces and in public areas
  • Danger - signal word used to indicate an imminently hazardous situation that, if not avoided, will result in death or serious injury
    • Chosen for High Voltage and Pinch Point
  • Caution - signal word used to indicate a potentially hazardous situation which, if not avoided could result in minor or moderate injury
    • Chosen for overall system warning
size of signs
Size of Signs
  • ISO Equation: H = D/40
    • H = Height of Sign (mm)
    • D = safe viewing distance (mm)
  • Pinch Point / Electrical Hazard
    • Safe Viewing Distance is 5 feet
    • Results in sign height of 1.5 inches
  • Avoid Injury
    • Safe Viewing Distance of 50 feet
    • Results in sign height of 1.25 feet
other sign details
Other Sign Details
  • Signs will be placed on both sides of identified hazard areas
  • Hazard Areas identified during Failure Modes Effect Analysis (FMEA)
  • Signs will be placed as not to disturb operation and maintenance of machine
  • Signs made from laminated paper
  • Signs attached using double sided tape
camera system

Camera System

Andrew Kearns

  • Purpose is to gain understanding of how image is developed onto photoreceptive material
  • Photoconductor system stopped
  • Photoreceptive material imaged after development and before transfer
  • Nikon D50 Camera used to Study Process as it occurs
  • Mirror will reflect image of photoconductor to camera lens
proof of concept10
Proof of Concept
  • Utilize one of three existing mounts
  • Third Magnetic Sensor will tell Labview when to stop Photoconductor for image capture
  • Camera will interface with computer via USB
  • Labview will call command to Nikon Software to capture image
  • LED Bar may be removed if paper delivery system occupies too much space
  • Speed of transfer roller critical to timing control and image quality
  • Need to assure that transfer drum rotates at the same speed as the moving photoconductor as to not elongate/condense the image
  • Need to assure that the transfer roller will be in the proper position for transfer to paper
  • Encoder provides feedback as to current speed of drum
proof of concept11
Proof of Concept
  • Optical Encoder sends 1024 pulses / rev
proof of concept12
Proof of Concept

A & B Outputs of Drum Encoder at 1.74kHz

Measurements Taken for Encoder B Output Signal

  • Current control system is done via KV300 PLC
  • Better solution needed to replace current system with a new user friendly interface
  • Labview uses dataflow programming to define inputs/outputs and execution sequence of the virtual instrument
  • Connect devices directly to DAQ to allow for more robust control
further issues
Further Issues
  • Tilting or Machining the Development System
  • Development System Toner Uniformity
  • Documentation of a user manual
  • Identification of a DAQ for purchase
  • Toner Bias
  • Test Plan with Critical Parameters Table
  • Transfer Roller Height Restriction
  • Air Filtration System