Proceedings - EDGE



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

The purpose of project P09503 is to take an inoperable Electrophotographic Development and Transfer Station (EDTS), donated from Kodak to RIT and make it functional, improve the usability, sensing and safety. The EDTS is a test stand that replicates the Charging, Exposure, Development and Transfer portions of the 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 the EP process as it relates to the EDTS and the improvements made to the system.

Nomenclature

Charge – A corona discharge caused by air breakdown uniformly charges the surface of the photoreceptor, which, in the absence of light, is an insulator.[1]

Corona - In a general sense, the visible flow produced by ionized air in the path of a high voltage electrical discharge. [1]

Expose – Light, reflected from the image or produced by a laser, or in the case of this EDTS and LED array, discharges the normally insulating photoreceptor producing a latent image – a charge pattern on the

photoreceptor that mirrors the information to be transferred to the real image. [1]

Develop – Electrostatically charged and pigmented polymer particles called toner, ~10 um in diameter, are brought into the vicinity of the latent image. By virtue of the electric field created by the charges on the photoreceptor, the toner adheres to the latent image, transforming it into a latent image. [1]

[pic]

Fig. 1 – Image of the EDTS

Transfer – The developed toner on the photoreceptor is transferred to paper by charging the back of the paper with a charge opposite to that of the toner particles. In the case of the EDTS the developed toner is transferred to an intermediary transfer drum before being transferred onto paper. [1]

Fuse – The image is permanently fixed to the paper by melting the toner into the paper surface. [1]

Clean – The photoreceptor is discharged and cleaned of any excess toner using coronas, lamps, brushes and/or scraper blades. [1]

Photoconductor (Photoreceptor) - A material which exhibits increased electrical conductivity when exposed to light. [1]

BACKGROUND

The EDTS takes the form of a linear setup, where a drive screw translates a flat plate photoconductor to interact with a charging, exposure, development and transfer system. Modern day electrophotographic systems, such as printers and photocopiers utilize photoreceptors that are shaped in a cylindrical form and rotate as opposed to translate, greatly reducing the travel time and process time of the light sensitive photoconductive material from feet to inches and minutes to seconds. This rotation process is more efficient for a commercial setting to produce a higher yield however for studying the EP process, translation systems are of more use for research and experimentation. As an example the average distance between systems in a typical commercial printer is one to two inches where on the EDTS the development and transfer systems are separated by about two feet.

[pic]

Fig. 2 – EDTS Architecture

Timing is critical to the EP process due to the dark decay properties of the photoconductive material used. Photoreceptors with a longer dark decay time, such as Estar, are more useful for the EDTS since the long potential fall off time is suited to the longer process times of the EDTS. This results in increased image quality. The total process time for the EDTS to produce one image can take up to two minutes where in a commercial printer it can take only seconds.

The current EDTS system donated by Kodak, utilizes pneumatics for the exposure and transfer system to directly interact with the photoconductor. Due to the nature of the charging and development stations, only translation at distances ................
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