Project

Overview

      Developing a laser fuser test bed that has continusous variation ability, necessary for testing the reaction of toner under different scenarios. Toner distribution and image quality are still very variable attributes when it comes to laser printing. This test bed will help in experimenting and understanding the effects that speed, pressure and temperature have on image quality. The customers for this project are Dr. Marcos Esterman, RIT and HP, all of whom are ultimately interested in improved image quality of laser printers. The test bed will have the ability to vary pressure, temperature, and speed associated with a toner populated media. The pressure, temperature, and speed settings will be adjusted and recorded by a computer , with an easily understandable graphic user interface. These criteria will met by the conclusion of the 22 week project. The team must provide complete documentation of the analysis, design, manufacturing, fabrication, test, and evaluation of this system to a level of detail that a subsequent team can build upon their work with no more than one week of background research.

Design Team

  • Industrial and Systems Engineers
    1. Justin McMillan
      Christopher Fink

  • Mechanical Engineers
    1. Damon Peters
      Robert Northrup

  • Electrical Engineers
    1. Kevin Duffus
      Joseph McGrath
      Ruben Caballero

CUSTOMER NEEDS & ENGINEERING SPECS

      The customer was interviewed upon the outset of the project and the overreaching results of the interview confirmed the goals of the project. The ability to independently and accurately control pressure, temperature, and dwell time were the most important deliverables set forth by the customer. The sampled parametric values must be passed to a computer in a closed loop data acquisition and control system. Sample size requirements, of 2cm x 2cm, as well as heating and change over time were also defined as critical customer needs. All determined customer needs were then given a ranking to help quantify their relative importance to the customer. A ranking system of 1-10 was employed, 1 being not very important and 10 being critical. From these customer needs, engineering specifications were derived. It was determined necessary for the unit to run on a 110V outlet; accurate within 3% of measured temperature, 5% of measured pressure, and 6% of determined dwell time; have a change overtime of less then 3 hours; it must be able to accommodate a minimum 2cm x 2cm paper sample. The test bed was also required to be able to test a range of temperatures from room temperature up to 400 degrees Fahrenheit, a range of pressures from 0 to 3 atmospheres, and to test these parameters over a time of 10 milliseconds. These were the corner stone engineering specifications used as design drivers upon the outset of the project.

Structural Drawings

9

Electronic Schematics

3

Make it safe

9

Durability

3

Cost Effective

1

Adaptability (pressure profile variation, media type)

3

Plug into standard wall outlet

9

Good functional user interface

9

Real-time data acquisition

3

Accuracy of temperature, pressure, and dwell time data acquisition

9

Accurate controlling mechanisms (temp, press, dwell time)

9

Kill switch

1

Documentation (operators manual)

9

Monitor Energy Consumption

3

Minimum sample size must be 2cm x 2cm

9

TABLE 1: Ranking metric


Sub-System Development

      Being able to independently vary temperature, pressure, and dwell time on un-fused toner became the focus of the team as the project moved forward into initial sub-system brainstorming. A brainstorming session was then performed by the team in an effort to determine what sub-systems would be necessary to satisfy the customer needs. The session determined the primary sub-systems to be the heating system, the control system, the sensing system, and the pressure application system. Once critical subsystems were agreed upon, investigation of the best means of accomplishing the goal of each sub-system ensued. The needs of the heating system to instantaneously raise the temperature of the toner during pressure application, were addressed with suggestions of radiation coupling or conduction from media or structure. Conduction quickly became the decided upon choice due to the fact that it is more accurate to the actual method by which toner in a printer is fused to paper. The pressure application system was a bit more complicated of a decision. There was no clear way to be able to apply pressure to the toner evenly. The nearly instantaneous nature of the pressure application system, much less then a second, made for some interesting suggestions. One team member suggested that a cannon be used as a possible means of applying pressure over the short period of time. Motors on a rail system and servo motors also came up during discussion as possible solutions. Ultimately a combination of motors would be the determined best solution. The sensing and controlling aspects of the system presented their own set of problems. With such a short period of time to work with, what kind of DAQ (Data acquisition) system would possess the ability to sample at an extremely high rate. The software that was determined as the optimum for our application was LabView. Due to its versatility and availability, LabView was really the only software given serious consideration. The DAQ board was researched and the National Interments cDAQ-9172 8-slot USB 2.0 Chassis, US(120 VAC) chassis with analog and digital cartridges was determined to provide the functionality and expandability required for the future of the test bed. Thermal couple wire is the most versatile and accurate temperature sensor found by the LFTB team. It is able to be placed and record temperatures any where the wire can be fastened. The Pressure could be measured accurately through the use of a piezoelectric load cell. The load cell would sense an applied force and transmit that force to the DAQ system at a conversion of 5mV/lb.

Concept Development

      With best sub-system decisions made the team proceeded to the concept development stage. During concept development the best sub-system solutions were combined together in differing configurations in an effort to come up with the best over all system as outlined by our customer needs. The results of the brain storming sessions are shown below. Pugh’s matrix was used to select the best concept. A vote was then taken to determine the best concept. Sketches of the concept were then done and the system was outline prior to moving forward to the parts order and fabrication stages.

System need addressed

Sub-System Solution

Convert electrical to thermal energy

Ohmic

Transfer thermal energy to toner

Conduction from media / structure

Control temperature signal

electrical relays

Apply and release pressure

pneumatic

Control pressure signal

DAQ board

Sense temperature in toner

Laser temperature gun (IR)

Sense pressure

Digital pressure gauges

Energy Transfer

modeling

Transfer thermal energy to media

Conduction from media / structure

Sense media temperature

Laser temperature gun (IR)

Sense input energy

Monitor power input

Sense how much energy gets to toner

Modeling

Sense dwell time

A function of the pressure sensor

Control dwell time

pneumatic

TABLE 2: Selected concept


Final Concept

      Just prior to moving forward with the selected best concept, it was put through extreme scrutiny by the team to make sure it was going to fill all the customer needs prior to moving forward. Unfortunately, the chosen concept had some major short coming when the 'reality check' customer needs were looked at closely. Sensing the temperature at the toner was still not determined to be possible; determining the pressure profile (curve) on the toner was still up in the air as far as accuracy of measurement; and determining nip width was deemed to be a nearly impossible task. This step back allowed for a new direction to be revealed. A cam can have a curve directly related to its shape through cam design, and the magnitude can be adjusted through linear position change of the cam itself. This was a better solution to the pressure application system needs. Then the idea of the equilibrium temperature was presented to the group by customer and team member Dr. J. Arney. This seemed to be the ice breaker that the team needed, and when HP bought into this idea of bringing the toner to equilibrium temperature prior to applying pressure, the path to success was illuminated. The temperature in the toner could accurately be determined due to the fact that the entire space would be at an equilibrium temperature, thus the toner would also be at that measured temperature. The force on the toner could be sensed by a load cell located directly below the toner itself and rigidly connected the impact area. This force could then be translated to pressure through the use of the formula p=f/a, knowing the area of the impact surface. Finally the concept that would satisfy all the customer needs was determined, and the process could move to the research and production stage.

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Rochester Institute of Tech.
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©2007 Kevin O. Duffus