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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