Download Technical Paper Revision 5 - Edge

Multi-Disciplinary Senior Design Conference
Kate Gleason College of Engineering
Rochester Institute of Technology
Rochester, New York 14623
Project Number: P10503
FLAT PLATE XEROGRAPHIC TEST FIXTURE
Adam Regula - ME
Dan Prosser – ME
Steve Snyder - ME
Guide: William Nowak
Amar Mohamed - EE
Lam Nyguen, Jr. - IE
Guide: Michael Zona
Copyright © 2008 Rochester Institute of Technology
MC – Motion Controller: A digital device that
controls the photoreceptor carriage.
ABSTRACT
The objective of this project was to make an existing
xerographic fixture operational and usable in a
classroom setting as well as research and development.
In order to achieve these goals, the project group
concentrated on determining nominal operational and
safety values for various controls concerning velocities
and voltages/currents as well as creating a LabView
interface that is both easy to use and functional. A
summary of the results of the project will go here
when we get there.
NOMENCLATURE
ESVM – Electrostatic Volt Meter: These devices are
used to measure the voltage across a certain element.
Unlike regular voltmeters used in everyday practice,
electrostatic voltmeters do not require the use of an
actual physical connect: instead of leads, probes are
placed in the vicinity of the component being
measured in order to obtain a more accurate reading.
Four of these are used in order to monitor the voltage
drop at crucial points during experimentation.
PC – Photoreceptor Carriage: This is the device which
the photoreceptor is attached to. It moves down the
line along each of the substations while the
photoreceptor is being manipulated by the substations.
PR – Photoreceptor: A device that becomes an
insulator in the dark and a conductor when exposed to
light. The photoreceptor is the main component of
this experiment since it will hold a latent image and
maintain toner on its surface.
DAQ – Data Acquisition: The device that obtains
analog data from a system and transfers it into digital
signals that can be stored and manipulated by the
LabVIEW software.
HSVP – High Voltage Power Supply: These power
supplies generate a large amount of power to the
devices of the Xerographic Plate Fixture. A total of
four are used in this system.
EM – Electromagnetic Field
LabVIEW – Laboratory Virtual Instrumentation
Engineering Workbench: The software that enables
the storage and manipulation of data into a user
friendly form. This software also controls every
device in the Xerographic Fixture through the user
interface.
NI – National Instruments:
manufactured LabVIEW.
The company that
LED – Light Emitting Diode: An electrical circuit
device that emits light when a positive voltage forward
biases the device and a current passes through it.
UI – User Interface: The style and display of a
program in which someone who is controlling the
computer must use.
INTRODUCTION
Prior to P10503, the xerographic test fixture was
worked on but not to completion and not to full
operational capacity. The objective of this project was
to achieve operational capacity for the fixture as well
as create an interface through which professors and
students as well as people involved in R&D to
manipulate the fixture. Another overarching objective
was to determine nominal settings for various controls
as well as safety limits to ensure fixture integrity as
well as operator well being. The customer of this
project was Professor Marcos Estermann of the RIT
ISE department and was guided by Xerox adjuncts
William Nowak and Michael Zona.
Theory:
- Fixture described series of inputs that become
outputs for next station, using this structure
we know which controls/inputs influence
which outputs for testing purposes (here
describe all inputs and outputs)
Project Planning:
- Show top customer needsshow CAD
drawings, interface screenshots, concept
creening results, link each back to customer
needs
Assumptions:
- Foam core will be able to block out all
relevant light sources
- Encoder has good enough resolution for data
acquisition and carriage control purposes
- Debugger interface has enough functionality
for testing purposes
Methods:
- Various test plans for each station to ensure
operational capacity and determine nominal
values
- Test plans to determine effectiveness of dark
enclosure
Experiments:
-
Describe each test, each setting in the
debugger interface for each test (here link
back to specs)
ASSEMBLY OF XEROGRAPHIC FIXTURE
In order to successfully enable the fixture to work, the
main project was divided into five subsequent stations,
each of which contributes heavily towards the end
result. The five substations in order are as follows:
Charging, Exposure, Development, Pre-Transfer, and
Transfer. Even though the functionality of the next
station depends on the state of the prior station, each
station was worked on individually and then a series of
tests were used in order to link their individual process
together.
Even though each individual station was responsible
for different tasks regarding the entire project, the
equipment and assembly of the fixture had to be taken
care of individually. Four high voltage power supplies
(HVPS) from the company TREK were required in
order to provide the proper voltages and current to the
fixture. Two HVPS were dedicated solely to the
charging station. One of them, designated to be the
Corona, had to supply a current of around 1800 µA in
order to induce a strong electromagnetic (EM) for the
charge to situate itself on the photoreceptor material.
This HVPS supplied a total of -650 V to the
The third HVPS, which was used for the Toner Bias,
was situated at the Development station in order to
attract the toner particles onto the photoreceptor. This
power supply also applied a high voltage to the toner
on the order of
-525 V. The last HVPS, which is
situated in the Transfer station, is the simply denoted
as the Transfer bias. These four HVPS evoked the
majority of the safety concerns for this project.
There were two main challenges to this project: to be
able to successfully run and control the xerographic
fixture and to be able to obtain the data and convert it
into a readable form that can easily be analyzed. The
first one involved extensive research of how to charge
the photoreceptor and charger the toner particles and
then attract it on paper, but the latter involved using
LabVIEW, which enabled both the automation of
different aspects of the xerographic fixture and the
acquisition of the output analog data produced from
the xerographic fixture, convert it into digital data, and
then send and store it into the computer to be
analyzed.
In order to obtain data and operate the xerographic
fixture from the computer for convenience, the
software of LabVIEW had to work with a total of three
DAQs (data acquisition) components. To account for
all of the automation and data acquisition involved
with this fixture, a total of three DAQs were used in
order to accomplish this. The three DAQs used were
the NI PCI 7330 MC (sole purpose was to control the
movement of the photoreceptor carriage), the NI PCI
6515 (sole purpose was to control the
electromechanical automations from pneumatics to
turning on the Exposure and Pre-Transfer LEDs), and
the NI PCI 6229 (sole purpose was to obtain and
monitor the analog inputs of the voltages and currents
of each station and to provide a low voltage to be
supplied and amplified by the HVPS.
Figure 2: EDTS System Controls State
Diagram for the LABView Interface
Figure 1: Basic Wiring Diagram for the four
High Voltage Power Supplies
In order to test the functionality of each station, four
TREK model 344 ESVMS are utilized. These
devices, unlike regular voltmeters, are independent of
the source of measurement by the use of probes, thus
enabling a more accurate measurement. Three of the
five stations, Charge, Exposure, and Pre-Transfer,
each have voltage outputs that need to be monitored
extensively. The ESVM probes are placed before and
after these stations and the voltage values are then sent
back to the computer through the 6229 DAQ. These
values are then displayed in the form of a graph on the
monitor by the LabVIEW UI, specifically voltage
versus time graphs to show and monitor the changes in
voltage.
Figure 4: Dark Enclosure covering the
Xerographic Fixture
Figure 3: Screenshot of LabVIEW User
Interface
DARK ENCLOSURE ENDEAVOR AND DARK
DECAY
In order to limit the dark decay due to the sensitivity
of the photoreceptor to light, a dark enclosure was
designed. The dark enclosure was built over the
charging, exposure, and development stations since at
these three stations the charge on the photoreceptor
was at its peak sensitivity due to the abrupt changes in
voltage at such abrupt times. After the PC exits the
photoreceptor, the presence of light is negligible since
the photoreceptor does not need such a high amount of
voltage across the last two stations. Since the main
objective of the dark enclosure was to shield the
operating fixture from light, the material chosen had to
be opaque and the dimensions had to be large enough
to encase the entire fixture, but not inhibit any of the
actions that occur during operation time.
The material chosen for the dark enclosure was foam
core, a thick, three-layered polystyrene material that
satisfied all of the needs for the dark enclosure. The
foam core used was black and completely opaque, two
characteristics which made it the optimal dark decay
inhibitor, easy to cut, which made it easy to assemble
the photoreceptor, and extremely lightweight, which
made it easy to do all of the applicable dark decay
testing necessary.
Once completed, the dark
enclosure, whose shape was rectangular, covered the
stations of the fixture like a box on all sides, but had a
reversible hinged door at the end of the development
station side so that the PC attached with the
photoreceptor can move back and forth through the
dark enclosure with ease.
In addition to the reversible hinged door, the dark
enclosure was assembled with a door at its side so that
the first three stations can be seen for the purposes of
troubleshooting and being able to demonstrate the
process of Xerography to observers. The quality of
the lightweight foam core made the dark enclosure
even more efficient since it can be taken off easily
from the fixture. The bottom of the enclosure attaches
the bottom of the fixture table by Velcro and can be
taken off easily so that a series of tests can be run in
order to measure the dark decay rate of the individual
photoreceptors due to the access to the back of the
fixture can be accessed easily for troubleshooting.
Figure 5: Measurement of Dark Decay with
and without the Dark Enclosure
PHOTORECEPTOR
There were two types of photoreceptors used during
this project: Xerox photoreceptor and Kodak
photoreceptor; however, mylar, a polyester made from
polyethylene terephthalate known for its strong
electrical insulation, often used in the applications of
helium balloons, was also used for experimental
purposes. The main concept of a photoreceptor that
proves its utmost importance in this experiment is its
ability to act as an insulator in the absence of light and
then emulate the characteristics of a conductor in the
light. A multitude of tests were used on each of the
photoreceptors, such as varying the charging voltage,
exposure station duration, to changing the overall
speed of the PC.
CHARGING STATION
The charging station is responsible for applying a large
voltage to the photoreceptor, typically in the range of
-600 to -700V. This voltage is applied through the
HVPS designated as the Grid Voltage. Accompanied
by the Grid Voltage in this station was the Coronode
Current, which was necessary in establishing the
electromagnetic field needed to ionize the air particles
so that charge can be delivered to the photoreceptor.
The corona HVPS typically supplied 1.8 mA to the
charging station.
The exposure station is responsible for illuminating
the photoreceptor as the PC crosses over the exposure
mount. When the charged photoreceptor is centralized
over the exposure mount, the PC stops and beneath the
mount, twelve light emitting diodes turn on,
illuminating the photoreceptor. This illumination from
the LEDs serves two main purposes. The first one is
to embed the image onto the photoreceptor. From the
properties explained earlier about the photoreceptor,
the uniformly charged photoreceptor is exposed to
both the lights and the image. The image that is on the
exposure mount blocks the light from reaching the
parts of the photoreceptor that will continue to hold
charge and which in turn, will develop the image,
while the unshielded regions of the photoreceptor will
discharge once light reaches it. The light that shines
on the photoreceptor also discharges it.
The main problem within the exposure station is the
inadequate knowledge of the properties of the
photoreceptors used. Because of this, it was difficult
to see what color of LED to shine on the
photoreceptor. The initial LEDs used in the exposure
station were twelve blue batwing Luxeon LEDs. This
choice, however, seems incompatible with the Kodak
photoreceptors since they are both of a blue color.
Because of this implication, the blue LEDs were
replaced with white batwing Luxeon LEDs.
DEVELOPMENT STATION
Figure 6: Graph of Charging Station
Potential and Photoreceptor Carriage
Velocity
The main problem that inhibited progress from the
charging station was the orientation of the
photoreceptor when it was to be connected to the PC.
A ramification of this obstacle was the difficulty with
the polarity of the photoreceptor and the voltage
supplied from the Grid Voltage. Initially, this problem
inhibited the progress of the xerographic process since
it was believed that the photoreceptor had to be
opposite polarities; however, this was not the case.
The polarities of both the photoreceptor and the Grid
Voltage had to be the same. Another concern that had
to be taken into account was the actual polarity of the
toner particles used. Also, the polarity of the of the
coronode current and the grid voltage must be the
same, but opposite of the photoreceptor. INSERT
EXPOSURE STATION
The third process of the xerographic process is known
as the development stage. In this stage, the toner
particles that will be transferred onto the paper are
finally introduced. Toner particles are infinitesimally
small polymer particles that have a unique
pigmentation and are polarized. The polarization
characterization of the toner particles plays a vital role
in the xerographic process. This is due to the fact that
the chosen toner particle’s polarity has a lot of
ramifications on how the other components of the
xerographic fixture functions with regards to charging
the devices to a positive or negative bias. These toner
particles are stored within a container and then
transferred onto the charged areas of the photoreceptor
remaining from the exposure station by the means of
roller.
The roller located within this station is known as the
development roller and its purpose is to transfer the
toner particles within the development station
container onto the photoreceptor by the use of a
skiving blade. Before this is done, however, the
development roller is charged to -525 V in order to
charge the toner. When this is all set, the skiving
blade, saturated with toner particle, spreads across the
photoreceptor and the toner particles are attracted to
the charged areas of the photoreceptor left by the
latent image due to the exposure station. Due to the
high potentials involving both the charged
photoreceptor and toner particles, a strong electric
field between the two enables a clear path for the toner
particles to travel onto the photoreceptor.
PRE-TRANSFER STATION
After the photoreceptor carriage leaves the
development station with the toner particles charged
onto the photoreceptor, it enters the pre-transfer
station. Most xerographic fixtures classify this station
to be an adjunct to either the development station or
the actual transfer station, but within this fixture, the
pre-transfer light emitting diodes are considered
independent of either of these stations. The pretransfer light emitting diodes within this xerographic
fixture consists of an array bar that emits red light.
This erases the charge to a mere -50 V in order to
make the transition of the toner particles from the
photoreceptor to the transfer roller drums much more
smooth.
RESULTS AND DISCUSSION
Evaluation of success:

effectiveness
of
dark
enclosure,
effectiveness of user interface

enforcement of safety limits both through
interface and on hardware

operational capacity of each subsystem,
nominal values of settings determined through testing
CONCLUSIONS AND RECOMMENDATIONS
This section should include a critical evaluation of
project successes and failures, and what you would do
differently if you could repeat the project. It’s also
important to provide recommendations for future
work.
REFERENCES
[1] Schein, Lawrence B. Electrophotography and
Development Physics. New York: Laplacian P, 1996.
[2] The Story of Xerography 1999.
TRANSFER STATION
The final process of the xerographic process, the
transfer station is where the allocation of toner
particles from the photoreceptor to the transfer drums
and then finally to the paper. Within the transfer
station are two roller drums which attract the charge
from the photoreceptor. The first drum is charged to a
bias of 2000 V in order to attract the -50 V charged
toner particles to the drum. Once the toner comes off
the photoreceptor and onto the initial spinning drum.
The second drum is applied with a bias of equal
magnitude and opposite polarity, giving it a -2000 V
bias. Once the second drum has been given the
required voltage and starts rotating, the toner on the
initially charged drum will move to the second latter
of the two roller drums. The paper is then pushed in
between the two rollers and the toner is transferred
onto the paper.
[3] Ientilucci, Emmett Fundamentals of Xerography
1994
ACKNOWLEDGMENTS
Thanks to the help and guidance of faculty guides
Michael Zona, William Nowak, and Marcos Esterman,
the endeavor of making the Xerographic Flat Plate
Fixture was a success. In addition to these people,
special thanks goes out to the attendees of the Detailed
Design Review, which included but not limited to
John Arney, Dale Mashtare. But most importantly, the
project would not have been completed in time
without the help of the LabVIEW Specialist Jeffrey
Robble, the teaching assistant assigned to P10503.