Proceedings of the Multi-Disciplinary Senior Design Conference Page 9

Multi-Disciplinary Senior Design Conference Kate Gleason College of Engineering Rochester Institute of Technology Rochester, New York 14623

Project Number: P09503

ELECTROPHOTOGRAPHIC DEVELOPMENT AND TONING STATION

David Schwartz / Project Manager Daniel Summers / Mechanical Engineer Andrew Kearns / Electrical Engineer Ruth Gay / Mechanical Engineer Rachel Chrash / Electrical Engineer Phillip Lopez / Mechanical Engineer Min Shi Hsiao / Electrical Engineer Sasha Oliver / Computer Engineer

ABSTRACT photoreceptor that mirrors the information to be transferred to the real image. [1] The purpose of project P09503 is to take an inoperable Develop – Electrostatically charged and pigmented Electrophotographic Development and Transfer polymer particles called toner, ~10 um in diameter, are Station (EDTS), donated from Kodak to RIT and make brought into the vicinity of the latent image. By virtue it functional, improve the usability, sensing and safety. of the electric field created by the charges on the The EDTS is a test stand that replicates the Charging, photoreceptor, the toner adheres to the latent image, Exposure, Development and Transfer portions of the transforming it into a latent image. [1] Electrophotographic (EP) Process. Once operational the EDTS has three major purposes. First to increase the understanding of the EP process by manipulating the input parameters and monitoring the process in real time. Second, to perform experiments with various fusing methods, as the EDTS contains all the subsystems of a typical EP machine, with the exception of the fusing subsystem. The third, and final, purpose of the EDTS is to perform research with layered manufacturing. This paper will aim to describe Fig. 1 – Image of the EDTS the EP process as it relates to the EDTS and the improvements made to the system. Transfer – The developed toner on the photoreceptor is transferred to paper by charging the back of the NOMENCLATURE paper with a charge opposite to that of the toner particles. In the case of the EDTS the developed toner Charge – A corona discharge caused by air breakdown is transferred to an intermediary transfer drum before uniformly charges the surface of the photoreceptor, being transferred onto paper. [1] which, in the absence of light, is an insulator.[1] Fuse – The image is permanently fixed to the paper by Corona - In a general sense, the visible flow produced melting the toner into the paper surface. [1] by ionized air in the path of a high voltage electrical Clean – The photoreceptor is discharged and cleaned discharge. [1] of any excess toner using coronas, lamps, brushes Expose – Light, reflected from the image or produced and/or scraper blades. [1] by a laser, or in the case of this EDTS and LED array, Photoconductor (Photoreceptor) - A material which discharges the normally insulating photoreceptor exhibits increased electrical conductivity when producing a latent image – a charge pattern on the exposed to light. [1]

roller lift. The system is limited by the 1.5 Cv value BACKGROUND (flow coefficient) of the MAC 45 series valves.

The EDTS takes the form of a linear setup, PROCESS where a drive screw translates a flat plate photoconductor to interact with a charging, exposure, The customer stressed thirty one explicit development and transfer system. Modern day needs for the EDTS ranging from broad system level electrophotographic systems, such as printers and needs to detailed ones for each subsystem. However photocopiers utilize photoreceptors that are shaped in after a review of the needs six specific needs were a cylindrical form and rotate as opposed to translate, utilized as the key to driving the improvements of the greatly reducing the travel time and process time of EDTS. The selected six were as follows: 1. Is the light sensitive photoconductive material from feet Operational 2. Is Safe 3. Minimize user Intervention 4. to inches and minutes to seconds. This rotation process Can Monitor Key Process Parameters 5. Can operate is more efficient for a commercial setting to produce a and monitor machine from one interface and 6. Easy higher yield however for studying the EP process, to learn to use. translation systems are of more use for research and Five of the six critical customers needs lead experimentation. As an example the average distance the team to develop the specification of an automatic between systems in a typical commercial printer is one and manual control interface of the to two inches where on the EDTS the development Electrophotographic Process. Since the purpose of this and transfer systems are separated by about two feet. machine is for research in Electrophotography an automated user interface that allowed for the manipulation and monitoring of all EP process parameters was planned for implementation. Since this project consisted of improvements to the current system, each team member was assigned a concept that was chosen based upon selection from Pugh’s Matrix, including automation and safety. The following concepts were selected to be designed implemented by the team: 1. ISO Safety Warning Signs 2. Ozone Fan\Filter Assembly Analysis 3. Fig. 2 – EDTS Architecture Electrostatic Voltage Measurements 4. LED Exposure Timing is critical to the EP process due to the System 5. Paper Delivery System 6. Photoconductor dark decay properties of the photoconductive material Imaging System Mount 7. Electrophotographic used. Photoreceptors with a longer dark decay time, Process Control and Automation such as Estar, are more useful for the EDTS since the A user manual was also written for each long potential fall off time is suited to the longer system present on the machine along with each process times of the EDTS. This results in increased concept designed by the team. The user manual image quality. The total process time for the EDTS to includes information on how to operate, troubleshoot produce one image can take up to two minutes where and maintain the machine. in a commercial printer it can take only seconds. The current EDTS system donated by Kodak, ELECTROPHOTOGRAPHIC PROCESS utilizes pneumatics for the exposure and transfer CONTROL AND AUTOMATION system to directly interact with the photoconductor. Due to the nature of the charging and development The most critical parameter of the control stations, only translation at distances <2mm is system for the EDTS was timing. In order to complete required. The exposure station is pneumatically lifted the electrophotographic process, each device on the to touch the photoconductor so that the latent image machine had to be triggered at the appropriate time. produced on the photoconductor is in focus. The The controller was a digital LABVIEW data transfer station also utilizes pneumatics since the acquisition (DAQ) device that had a current limit of transfer step requires direct contact in order to transfer 125 mA and a voltage limit of 30 V. The devices that the toner from the photoconductor, to the transfer drive each station on the machine are drum, and then finally to a substrate. electromechanical and can draw up to 3 A. Since the The pneumatics were a previously installed DAQ couldn’t handle the loads it needed to drive, a system. It consists of four parts within the system and relay was placed in series with each device in order to an input pump outside of the system. The stations are protect the DAQ from power surges. The DAQ divided up between the exposure lift, the intermediate enabled voltage signals on each device using a 24 roller lift, the intermediate roller lock and the backup VDC supply. The power supply was also vulnerable to

Project P09503 Proceedings of the Multi-Disciplinary Senior Design Conference Page 3 high current levels, so a 2 A circuit breaker was could provide enough current when the pulse train was connected in series with the power supply and all the fed to the motor such that the motor would not become components it was driving. stalled when the PC reached the end of the machine The actual hardware that was connected to where the lead screw became jammed. A similar the DAQ included four DC motors, two optical process was performed to control the DC motors that encoders, four magnetic sensors, two LED arrays, four moved the drum, paper feed, and toning rollers. pneumatic valves, and one rotary solenoid. The The PC needed to return to a home position sensors and encoders were connected directly to the after the process was complete. This required that the counter card of the DAQ since their power levels PC motor be able to rotate in two directions. A double couldn’t damage the DAQ. Each sensor is normally pole Double Throw (DPDT) relay was connected to active high. When a sensor is tripped by placing a the motor to facilitate motion in opposite directions. magnet in front of it, the voltage level is low. Since the The DPDT relay had a switch that was between two sensors were receiving the logic high from the DAQ as sets of inputs. When the relay was off, two inputs were well as being grounded with the DAQ, a 1 kΩ pull up connected to the switch. When the relay was on, two resistor was connected in parallel with the positive different inputs were connected to the switch. One side terminal of each sensor and the logic level from the of the motor was connected to an input that was DAQ to ensure that the logic level would only change normally closed and to an input that was normally on one sensor when it was tripped. Each encoder open. The other side of the motor was connected to the produces six pulse outputs. Only three were needed to opposite sides of the DPDT relay that were normally monitor the speed of a motor. Each encoder had a closed and normally open. By feeding the pulse to drive shaft that was connected to the load on the both of the switching inputs of the relay and providing motor. When the load completed one rotation the an enable that turned the relay on when reverse motion encoder would produce 100 pulses. A simple was required, the motor could be controlled properly. conversion of units was calculated to derive speed of Since the DPDT relay couldn’t amplify the pulse from the load from the frequency of the pulse signal from the DAQ to 15V, a solid state relay fed the DPDT the encoder. Since the counter card could interpret relay the 15V pulse train. pulse trains, it was logical that the encoders be connected to it. A Pulse Width Modulation (PWM) signal was used to control the velocity of each DC motor. A motor takes a certain amount of time to respond to a voltage. If a particular voltage level is applied the motor cannot reach the maximum velocity determined by that voltage instantaneously. A pulse train can be used to vary the speed on the motor. When the pulse is high, the motor is on. When the pulse is low the motor is off. Taking into account the motor response time Fig. 3 – DPDT Schematic and the reaction of the motor to the pulse train a solution is apparent. The duty cycle of a pulse is the The pneumatic valves, rotary solenoid, percentage of time that the pulse is high over the exposure LED array, and toner removal LED bar were period of the pulse. By changing the duty cycle, the all binary outputs from the DAQ. 24VDC was routed time that the motor is on versus the time that it is off to the DAQ which could then manipulate the logic can be varied. Thus the speed that the motor reaches level on whatever load was supposed to be triggered. can be varied by changing the amount of time it is Once again, a solid state relay was connected between turned on for, by the pulse. Changing or modulating the DAQ and the load to protect the DAQ from high the width or duty cycle of the pulse train changes what current levels. It was observed that multiple power speed the motor was allowed to reach. This machine supplies were necessary to drive the number of used a 15 VDC supply that was connected to the devices on the machine. When the DAQ tried to drive output side of a solid state relay for each motor. The multiple outputs simultaneously, the power supply control side of the relay was fed a pulse train from the failed due to the fact that too much current was being DAQ resulting in an output pulse train with amplitude drawn from it. Two supplies were necessary to drive of 15 VDC. The top speed of the motor if fed 15V the set of binary control devices. The pneumatic continuously was 1700 rpm. This speed was much system was used to lift the exposure box, drum, and greater than the speed necessary for the process. A bottom transfer roller. The system had to be 15V supply was necessary due to deterioration of the pressurized to 15 psi in order to lift the drum. Once the mechanical connection between the main drive screw system was completely functional a schematic was and the photoconductor (PC) mount. The 15V supply created separately from the schematic for the power

Copyright © 2008 Rochester Institute of Technology Proceedings of the Multi-Disciplinary Senior Design Conference Page 4 distribution system and exposure LED array. The reaches the transfer drum/bottom roller, both the control schematic referenced the other systems and transfer drum and bottle roller begin to rotate and reflects the wiring of the hardware on the machine. transfer the developed image from the transfer LabView is used to control the device instead of the roller to the paper. PLC. LabView was chosen because of the native 7. Finally the paper passes through the rollers compatibility of the NI-DAQ and encoders. The EDTS and is deposited on the paper delivery system can be operated by running the primary state machine with toner attached. The drum, bottom roller and VI or tested by using the manual test panel VI. Both paper feed all stop motion. The PC then goes in test panels were designed for simplicity to use by reverse a little bit past the first sensor so it can anyone. begin the state machine once more. At this point The linearity of the EP process lends itself very toner has now been transferred to paper. well to a state machine design. Four position sensors serve as pivotal points in the state machine design. This automation process is accomplished with 11 The photoconductor moves along the EDTS until it states in a Labview state machine. All components, reaches the end interacting with the four subsystems with the exception of the motors are connected to the and stopping at pivotal points to accomplish all parts NI-DAQ, PCI-6515. The motors are connected to PCI- of the EP process. Here is the breakdown of the 6600 which allows for a Pulse Width Modulation automation process implemented into the State (PWM) to controls the motors. The devices are then Machine VI: processed by a DAQ assistants within the state machine program. Global channels are set up to 1. Starting from the edge of the EDTS the generate a PWM pulse to rotate any of the motors. A photoconductor (PC) moves to Sensor 1, frequency channel is set up to gather the frequency translating over the charging system. The information from the transfer drum and the PC. photoconductor is charged after this step. 2. At sensor 1 the PC stops directly above the The states are enumerated as follows: exposure system. The pneumatically controlled exposure lift moves upward to touch the PC. 1. Initialize – moves to sensor 1 While the lift is still touching the PC the LEDs 2. GT_sensor1 – raises the exposure are briefly activated thereby exposing the PC to lift and illuminates the LEDs light. The LEDs are then turned off and the lift 3. GT_sensor2 – moves from exposure returns to its original resting state. After this step lift to sensor2 and lowers the exposure lift and a latent image has been formed on the PC. turns off the LEDs 3. The PC the continues downward on the 4. GT_sensor3 – actuates the solenoid EDTS and when it reaches sensor 2 it does not turns on the LED bar and rotates the toning pause, but keeps moving forward. However station motor, while moving the PC when the EDTS passes by the second sensor the 5. Sensor3_actions – Stops everything toning station motor is engaged, the LED bar except for the PC, raises and begins rotating turns on and the solenoid actuates. Following drum and PC simultaneously. this step toner has been applied to the PC and the 6. Sensor4_actions – Stops the PC and LED bar has decreased the charge. raises the bottom roller. 4. When the PC reaches sensor 3, the previous 7. Transfer – Paper feed and drum three items turn off. The transfer drum is raised begin rotating for 134 pulses (10s) first, and while the PC is still in motion the PC 8. Turn off – All moving components and drum come in contact with each other and turn off and the bottom roller is lowered. start moving/rotating at the same speed thereby 9. Reverse – Reverses the PC to sensor transferring the image from the PC to the transfer 1 drum. Following this step the developed image is 10. Reverse2 – Reverses past sensor 1 transferred to the transfer drum. 11. Stop – Infinitely loops until user 5. The PC reaches sensor 4, at which point, the presses Start on the VI front panel. drum and PC both cease motion, rotational and translation, respectively. The transfer drum comes down and the paper feed turns on thereby feeding paper towards the transfer drum. 6. The bottom roller is then raised to create pressure between the bottom roller and the transfer drum. The paper that is being fed through the paper roller is timed so that once it

Project P09503 Proceedings of the Multi-Disciplinary Senior Design Conference Page 5

Fig. 4 – Automatic and Manual Control Interface

LED EXPOSURE SYSTEM

At the image plane, light passes through a mask that creates light and dark areas on the film. Originally, the exposure station utilized a projector system to expose photoconductive material. The Fig. 5 – Testing of Light Sources - In this figure the intensity and uniformity at the image plane was tested uniformity and intensity of each light source was to analyze how effective the system is. The system analyzed. The absolute illuminance was plotted proved to be sufficient in intensity, but was not against the area of the image plane. The projector uniform. The uniformity of light is important in the system had sufficient intensity, but is not considered exposure process so that the film is discharged uniform. The 3x4 array produced a smoother, uniformly. If the film is not discharged uniformly, the Gaussian distribution of light. Without the collimating resulting image will be too dark or too light in certain lenses, the 3x4 array becomes perfectly uniform but areas. The projector system also consumed a large area intensity is sacrificed. The LUX meter used in the on EDTS, required a large amount of power to experiment is one fifth less sensitive to blue light than operate, and needed to be turned on prior to the it is to white light. If the intensity of blue light was to operation of the system so that the bulb had sufficient be accounted for, results of the array could be time to warm up. The system was relatively low multiplied by five. maintenance but replacement bulbs or parts are The LEDs have a turn on time of 100ns. The expensive and time consuming. For these reasons it turn on time is short enough that the LEDs do not need was decided that the projector system could be to warm up and can be turned on at the time of replaced with one that is more efficient. exposure. This allows for less overall power Luxeon Star high powered LEDs were chosen consumption for a system that does not consume much to replace the projector exposure system. To achieve power to begin with. The system runs on 24 VDC, the most effective exposure, blue LEDs were used which is much less than the 120 VAC that the since photoconductive material is most sensitive to the projector system ran used. The LED configuration also short wavelength of blue light. The number of LEDs consumes much less space than the projector system. used in the system and their configuration was tested The LED array is small enough that it can be mounted by analyzing their intensity and uniformity. The tests within the exposure box and can be seen in Figure 6. proved that a 3x4 array of LEDs produced the best Velcro, on the underside of the array, was used to results. The LEDs were configured to make the array mount and secure the system. By using Velcro, it the same size as the image plane. By making the array allows for simple movement of the system and easy the same size as the image plane, it allows less of a access for maintenance. Maintenance to the system is chance for light intensity to decrease at the edges of low. Dust cannot collect on the LEDs and solder the image plane. Each LED has a collimating lens that connections are to be checked every six months. is used to direct light into a beam and increase its LEDs have a much longer lifetime than a traditional intensity. Light slightly drops off on the edges of the incandescent bulb but if one is to burn out, it is image plane but is still intense enough not to cause a inexpensive and simple to replace. discrepancy in the image. Compared to the projector system, the LED system is more uniform and provides sufficient intensity for exposure as seen in Figure 5 below. The collimating lenses of the LEDs can be removed to provide a completely uniform light source. This sacrifices intensity but since the photoconductive material is so sensitive to blue light, it still proves to be better than the projector bulb. The LUX meter used in the experiment is one fifth less sensitive to the blue Fig. 6 – The LED system is mounted inside the light than it is to white light. When the intensity and exposure box and is secured by Velcro. uniformity of the light sources are compared to each other, the blue LEDs are shown to be less intense than Overall the LED system is smaller, less the projector bulb due to the nature of the LUX meter expensive, consumes less power, and is easier to used. maintain than the projector bulb system. Through testing, it was proved that the LED system is a more uniform source of light that can provide sufficient

Copyright © 2008 Rochester Institute of Technology Proceedings of the Multi-Disciplinary Senior Design Conference Page 6 light for exposure. The LED system is a versatile to be mounted in the hole beneath, in order to take source of light that allows the user to have options pictures of the developed photoconductor before while producing the best possible exposure of the Transfer. Two Polycarbonate trays were constructed: photoconductive material. one to be installed, and one as a replacement if needed. The frame has parallel side bars for the tray to rest on, PAPER DELIVERY SYSTEM made from 6061 Aluminum. All parts were assembled and installed on the The initial evaluation of the status of each test bench. As designed, the paper delivery system is subsystem revealed several possible safety hazards in adjustable; the tray can be removed or can slide closer the Transfer station. The hazards to a human user to or farther from the transfer station. Although the include moving parts, possible shocks or shorts from included tray sufficiently accomplishes the intended the high voltage charge on the roller, as well as pinch objective, the only suggested improvement would be points between the Photoconductor and the roller and to use a scratch-resistant polycarbonate for the tray for between the primary and secondary rollers. However, an even clearer window to take pictures through. Most the existing system neglected to provide a way to of all, the tray successfully removes the need for collect paper as it is expelled from between the rollers. human intervention in this step of the This compelled the operator to manually grasp the electrophotographic process. paper as it was presented to keep it from falling while the EDTS was still in operation, exposing the operator PHOTOCONDUCTOR IMAGING SYSTEM to the above hazards as well as introducing the MOUNT possibility of marring the image and interfering with test results. The photoconductor imaging system mount To correct this oversight, the concept of a was the result of a need to image the photosensitive paper delivery system was developed: a tray to receive material after it had been developed. The major the paper after Transfer occurs. The solution needed to design requirement was that the mount not be hold 4.25” x 5.5” paper samples. It needed to fit in the permanently attached to the stand. The initial design available space adjacent to the transfer roller without involved using an existing mount to hold the camera in interfering with other components. The existing test place. The design proved inadequate for the needs, as bench base has two parallel 3/8” slots with the centers the weight of the camera stripped the mounting screws of the slots 8” apart, that are used to secure the and the space required by the setup would be systems in place. Just before the Transfer station, there unavailable in the final project. A hanging design was is a 5½“ square hole in the bench with ¾” radius eventually decided upon, wherein the camera would corners centered between the slots. The pneumatic lift point straight up through the paper tray, which would for the lower roller is 4¼” above the test bench base double as a protective aspect. The mount consisted of and the bottom of the bar is 1¼” above and connected two parts, a brace on top to stay on the stand and a to the lift. The protruding edge of the tray would have hanging part to which the camera was mounted. To to be at this level between the lift and the bar in order enable the use of a 1/4 inch screw for mounting the to receive the paper. Additional design constraints camera, a countersink was put in the hanging section. included manufacturability using appropriate inexpensive, easily obtainable materials, as well as ease of installation, adjustment, and removal.

Fig. 8 – CAD Drawing of the Camera Mount

ELECTROSTATIC VOLTAGE Fig. 7 – Implemented Paper Delivery System over MEASUREMENTS (ESVM) Camera The output quality of the xerographic image The camera needed to be mounted within the is determined by the functionality of each subsystem. same space as the paper delivery system. To allow Monitoring the voltage on the photoconductor right this, a tray was designed from clear Polycarbonate after the charging station will help to characterize the plastic. The clear tray rests on the frame directly above photoconductor’s dark decay property as well as the square hole in the test bench, allowing the camera

Project P09503 Proceedings of the Multi-Disciplinary Senior Design Conference Page 7 charge uniformity as the exposure input noise source. source for a period t=1.1 RtCt. During this period, the It can also be helpful in terms of creating a voltage vs. current i will flow out of the switched current source exposure level plot when the measurement is taken and provide a fixed amount of charge, Q = i x t, into after exposure. the capacitor, CL. This will normally charge Vx up to a A Trek 344 Electro-Static Voltage Meter is higher level than V1. At the end of the timing period, the measuring device. Its probe works like a capacitor the current i will turn OFF, and the timer will reset that charges itself up to the same level as the object itself. Now there is no current flowing from pin 1, and being measured. Therefore it allows potential on the the capacitor CL will be gradually discharged by RL photoconductor plate to be determined without until Vx falls to the level of V1. Then the comparator physical contact. will trigger the timer and start another cycle. The The probe has to be placed 2mm from the current flowing into CL is exactly IAVE = i x (1.1xRtCt) x surface of the photoconductor. It cannot be held by f, and the current flowing out of CL is exactly Vx/RL . hand since it will charge itself up with respect to the VIN/RL. If VIN is doubled, the frequency will double to object being measured; therefore, the probe needs to maintain this balance. Even a simple V-to-F converter be positioned by a fixture. The solution is to use the can provide a frequency precisely proportional to its old camera holder along with a probe mount as the input voltage over a wide range of frequencies. fixture since it can be easily adjusted and repositioned while staying at the same distance from the photoconductor. Based on the size of the ESVM, it was essential that mount footprint remain small. Clearance at the mounting point had to be minimal to ensure accurate measurement, requiring countersinking for the bolts. Readings of the charge will be taken immediately after charging and exposure station by two separate ESVMs. Fig. 10 – LM331 basic operation cycle ESVM ADC The simple stand-alone V-to-F converter The ESVM has a DC output that is 1/100 of shown in Figure 10 includes all the basic circuitry of what it is reading from the probe. This signal cannot Figure 9 plus a few components for improved be read directly by the DAQ since it only recognizes performance. A resistor, RIN=100 kΩ±10%, has been digital inputs. Therefore, an analog to digital converter added in the path to pin 7, so that the bias current at (ADC) has to be designed in order for the DAQ to pin 7 ( 80 nA typical) will cancel the effect of the bias read the output of the ESVM. The simplest solution − current at pin 6 and help provide minimum frequency found was to use a voltage to frequency converting offset. The resistance RS at pin 2 is made up of a 12 chip (LM331) as shown in Figure 9. Preliminary tests have been conducted and output frequency does kΩfixed resistor plus a 5 kΩ(cermet, preferably) gain increase linearly with the input voltage. adjust rheostat. The function of this adjustment is to trim out the gain tolerance of the LM331, and the tolerance of Rt, RL and Ct. For best results, all the components should be stable low temperature- coefficient components, such as metal-film resistors. The capacitor should have low dielectric absorption; depending on the temperature characteristics desired, NPO ceramic, polystyrene, Teflon or polypropylene are best suited. A capacitor CIN is added from pin 7 to Fig. 9 – LM331 chip ground to act as a filter for VIN. A value of 0.01 μ F to 0.1 F will be adequate in most cases; however, in The operation of the LM331 chips is best μ cases where better filtering is required, a 1 μ F understood by going through the operating cycle of the capacitor can be used. When the RC time constants are basic V-to-F converter, Figure 10, which consists of matched at pin 6 and pin 7, a voltage step at VIN will the simplified block diagram of the LM331 and the cause a step change in fOUT. If CIN is much less than CL, various resistors and capacitors connected to it. The a step at VIN may cause fOUT to stop momentarily. A voltage comparator compares a positive input voltage, 50Ωresistor, in series with the 1 μ F CL, provides V1, at pin 7 to the voltage, Vx, at pin 6. If V1 is hysteresis, which helps the input comparator provide greater, the comparator will trigger the 1-shot timer. the excellent linearity. The output of the timer will turn ON both the The output frequency followed this formula: frequency output transistor and the switched current

available to us at the time. After consulting with PRISM we concluded that the current ozone system would be sufficient enough for the station. The only

U1 R5 action taken was replacing two brackets used to Rin 7 3 IN FRQOUT 100k support the fan and filter, thus making the assembly 5 1 Vin 2 R/C IOUT 10k 3V REF Cin 6 more maintenance friendly. THRS 0.1u 8 Vlogic VS 5V RL Rt C2 100k LM331 1u Vs 15V Rs 5.6k 12k R4 50 Ct .01u

Fig. 11 – Voltage to Frequency Converter Schematic Charging Station using LM331 = Test Location (Grid and Corona) OZONE FAN\FILTER ASSEMBLY ANALYSIS Fig. 12 – Circles Indicate Ozone Testing Locations

The objective of this analysis is to verify that RESULTS AND CONCLUSION the charging area of the EDTS where ozone is produced, the charging station, is safe for the operators After implementation of all improvements the of the machine. Due to the high voltages being utilized critical system test that ultimately defined success or in the charging station at the Corona and the Grid, an failure of this project was the Standard EP Process unknown amount of ozone is produced. Ozone in itself Test, which was performed successfully. This two part can be hazardous to humans if exposed to large test would determine if: 1. During automated amount. Law states that the maximum allowable operation, the EDTS would carry out the EP process amount of ozone in an air conditioned space is as described in the seven state machine breakdown 0.050ppm. Studies also show that at 0.200ppm and mentioned above and 2. Toner successfully transferred higher there is a possibility of decrease lung function, from the development system, onto the nasal irritation, induced asthma, coughing, chest pains, photoconductor, onto the transfer drum and then and inflammation of lung tissue. Since the only finally to a substrate. The total design called for 46 moderating device of ozone on the EDTS is the specifications, to which 40 were within, four were not fan/filter assembly, determining the amount of ozone within and two received special circumstances. The that is produced if the assembly isn’t functioning six design specifications that were not met are not properly has to be addressed. The procedure followed critical to EDTS operation. was to verify if the current sub-system is safe enough, The EDTS can now be successfully operated or to proceed with implementation of further by anyone with knowledge of Electrophotography. improvements to bring the ozone level within EPA regulations if the charging system producing an unsafe REFERENCES amount of ozone. The testing device utilized was an ozone [1] Schein, Lawrence B. Electrophotography and detector, borrowed from Environmental Energy Development Physics. New York: Laplacian P, 1996. Technologies, which can accurately read ozone levels at amounts of 0.5ppm or greater. If the detector at any ACKNOWLEDGMENTS point were to have indicated the presence of ozone the ozone fan and mount on the fan filter assembly would This project would not be accomplished if not for be upgraded immediately. This improved mount the following dedicated individuals. Their help with would help increase the suction force of the fan the understanding of Electrophotography, Printing and relative to the area where the ozone was being created. Data Acquisition proved to be essential to the Furthermore the tests that were run originally had completion of the EDTS. Bill Nowak – Xerox, Greg several areas in which the detector would be placed. Miller – Kodak, John Wellin – Mechanical After testing it was observed there were no detectable Engineering, Dr. Jon Arney – Center for Imaging amounts of ozone amounts for all situations. It is noted Science, Dr. Susan Farnand – Center for Imaging that around 0.2ppm is when throat and nasal irritation Science, John Bonzo – Brinkman Laboratory and may occur. This was not experienced by any of the finally Dr. Marcos Esterman – Industrial and Systems testers in the surrounding area. This is the only relative Engineering. conclusion we can make with the limited equipment

Project P09503