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A mathematical model of the electrophotographic printing process has been developed. This model can be used for analysis. From this a print simulation process has been developed to simulate the effects of the model components on toner particle placement. A wide variety of simulated prints are produced from the model's three main inputs, laser spread, charge to toner proportionality factor and toner particle size. While the exact placement of toner particles is a random process, the total effect is not. The effect of each model parameter on the ISO 13660 print quality attributes line width, fill, raggedness and blurriness is described.

We present an analysis and model for evaluation of color shifts in halftone printing caused by inter-separation misregistration for periodic clustered dot halftones. Using a lattice framework, we present intuitive analysis that demonstrates conditions under which the average color is asymptotically invariant under inter-separation misregistration. Combining the framework with an analytic representation for the halftone dots, we develop a hybrid analytical-numerical model for quantitatively estimating color shifts as a function of inter-separation misregistration. The model is compared against experimental data for a xerographic printer.

Charge transport phenomena in semiconducting doped polymers is very important due to their spread use in xerography, electroluminescent devices (OLED's), photovoltaic cells and photorefractive systems. The carrier mobilities were determined by time-of-flight (TOF) measurements on indium-tin oxide/polymer composites/indium-tin oxide samples. Data are collected as a function of different external applied fields at various temperatures and are analyzed according to the disorder formalism.

We aim to fabricate microstructure and microdevices by integrating and arranging powder particles, i.e., the particle assemblage. We have developed three assembling techniques of the particles. The details of the assembling techniques and samples of the assembled microstructures are introduced. A manipulator is developed to manipulate and to weld metal particles by using a tungsten probe. Nickel alloy particles of 50 micrometers were piled on a gold substrate by the manipulator, and a leaning tower of the particles is fabricated. The array of the leaning tower is considered to act as an actuator. For the integration of a great number of particles, we developed another method based on the principle with the xerography. An electron beam or an ion beam is irradiated on an insulating substrate. An electrified pattern is formed on the substrate by the doped electron or doped ion. Fine particles are attracted to the pattern by the electrostatic force. Thus, we can arrange particles by immersing the substrate in the suspension of particles. The third is a productive method of ordered mixture by the electrostatic force. A self- thermostatic heater is made from the composite particles of BaTiO3 and In produced by the method.

Some kinds of bisazo pigments and single-crystal hydrazone derivatives have been synthesized and three types of experimental organic photoconductors for advanced electrophotography were prepared and tested. The result shows that under visible light the photoconductor of ortho- chloride bisazo pigment is far more sensitive than p- chloride and non-chloride bisazo pigments. Its sensitivity reaches 0.71 Lx.s and is appropriate for advanced xerography.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In Tri-level xerography, the control of the modulated levels creates a new set of problems, which did not plague the usual binary levels in normal xerography. One of the many concerns is controlling overshoot of the mid-level exposure so that the signal does not invade into the high-level exposure. Another concern is to maintain adequate signal width, which correlates well with the desired output pattern.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

TiO-phthalocyanine and H 2 -phthalocyanine dispersions with polymeric binders are presently used as charge generation layers in xerography. The question arises whether an admixture of the electron acceptor C 60 to the dispersion is able to inhibit the recombination of excited states and therefore enhance the charge-generation efficiency. We study the effect of an admixture of 5 percent C 60 on the unoccupied density of states by x-ray absorption near edge spectroscopy using tuneable light from the Berlin electron storage ring for synchrotron radiation. Information on the occupied states is obtained by photoelectron spectroscopy with UV-radiation. The spectral features are identified by comparison with spectra from the single components and discussed. The influence of structural differences of H 2 -Pc on the optical properties is considered using optical transmission data.

The expression 'Plain' paper was coined in the early days of electrophotography to distinguish the capabilities of the new dry toner based photocopying process which did not require a sensitized or special coated paper to produce an image. Currently 'Plain' paper is considered in the electronic printing industry, to be any uncoated paper, usually of the type used in office photocopying applications. It is assumed that all 'Plain' papers are identical or at least equivalent in their properties such that all papers will give equivalent print quality performance. Due to the wide availability and low price of 'Plain' papers, it is also considered desirable by vendors of electronic marking processes, that their technology be capable of producing good image quality on 'Plain' paper. The chemical and physical differences which can occur among 'Plain' papers are discussed with respect to the specific image quality and engine reliability requirements of the major nonimpact electronic marking technologies, including electrophotography and laser printing, electrographic and ionographic processes, thermal transfer and ink jet. Paper properties of interest include, smoothness, surface energy, electrical resistivity, porosity and aqueous and nonaqueous liquid adsorption. Color printing has added additional requirements to paper quality, if good image quality is to be achieved and maintained. Given the apparently conflicting requirements for some of the electronic marking technologies, it will be a challenge to define a single grade of paper which will produce optimum print quality for all electronic printing processes.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The xerographic laser printing system is reviewed and the role that materials play in the seven xerographic subsystems is described. The functional performance of four major materials systems, photoreceptors, developers, fuser roll materials and paper, is defined and related to their respective composition and component properties. It is shown that the performance of the printing system and the quality of the output documents are almost exclusively dependent on the quality and reliability of these exceptional materials systems.

An overview is given of permanent changes in the refractive index and optical transmission which occur in some rare earthdoped inorganic glasses and optical fibers when resonantly excited into specific 4f and 5d manifolds. These phenomena arebelieved to be electronic in nature involving color centers. They are important for both refractive index grating devices as wellas for the optical reliability ofEr3—doped optical fiber amplifiers. 1. REFRACTWE iNDEX CHANGES1.1. Bulk glassPhotosensitivity in disordered solids has been known for many decades and it is technologically very important: for instance, it provides the enabling technology for xerography. Traditionally most of the materials involved are semiconductinginorganic glasses. Much less well understood is similar behavior in insulating glasses, such as in germanosilicate opticalfibers. In the laffer family of glasses UV4nduced refractive index changes and multiphoton induced second harmonic frequency generation (SHG) has been StUdied intensively in the last ten ears1'2 These effects are currently believed to be theresult of a specific charge redisthbution mechanism following the optical excitation of an oxygen-deficient Ge-related defect,yielding a permanent change in the refractive index or in the microscopic symmetzy in the case of SHG.

Image noise, tone reproduction, color reproduction, fine line reproduction and OHPperformance are the most important characteristics for a high quality color copier.Technologies enabling such quality are use of fine toner, halftone algorithm to ensuregood highlight reproduction, soft roll fuser with good release performance, smoothsurface and high thermal conductivity, white and smooth paper, and selection of a coating material for the surface layer of the OHP sheets. These technologies are integrated in the Fuji Xerox "A-Color" product. Utilizing7im color toner, "A-Color" can make very high quality color copies. I . IntroductionSince the first color copier product was introduced in late 60's, the products have not been so successful in the market. There are several reasons why, however the biggest one is apparently the level ofcopy quality.The customer wants to reproduce the same level of quality as the original. But it isalmost impossible by the conventional analog (light-lens) technologies.Xerox 6500, Canon NP-T, Ricoh 5000, Fuji Xerox 6800, Kodak Color Edge are allanalog type copiers.

Single pass highlight color printing with tn-level xerography has some unique capabilities, but also has some inherent difficulties which needed to be overcome before launching the new Xerox 4850 Highlight Color Laser Printing System. These capabilities and potential pitfalls are discussed below, with the aid of a computer model of tn-level xerography. 1. INTRODUCTIONThere are many xerographic methods of obtaining black plus one color on a page, including tandem printengines or a single engine with twin charge-expose-develop stations. Xerox Corporation recently launchedthe Xerox 4850 Highlight Color Laser Printing System which utilizes another method, namely tn-level xerography1 . Tn-level xerography derives its name from the number of levels the laser raster output scanner (ROS) must address. In "traditional" xerography, at each pixel location the laser is either on to fully discharge the photoreceptor or off, leaving the photoreceptor highly charged. The development housing is

Recent needs of higher copy quality with dry xerography led to aggressive pursuit of smaller particle size toners also in the toner technology areas. This is based on a belief that copy quality will be improved as the toner particle size is reduced. On the other hand, the toner size reduction has been known to cause difficulties in the xerographic process, such as poor transfer properties, for example. The development and transfer steps in the xerographic system depend on detachment of charged toner particles by the electric field which has to overcome the adhesion force to carrier beads and the photoreceptor. In order to find small toner particles matching the xerographic process, understanding of adhesion forces of charged toner particles is necessary. We have evaluated the detachment field of charged toner particles varying the size, composition materials, and surface structure. The results showed that the detachment field was dominated by the electrostatic force which in turn depended on the toner surface roughness. This roughness can be related to the actual contact area with the substrate surface. Seven micrometers toners designed according to the above findings gave good transfer properties.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

One exposure, trilevel xerography provides a novel means to produce, single pass, highlight color prints. In this scheme, a ROS creates an imagewise three level, unipolar latent image in which the color information is encoded in the discharge level. The highest charge regions represent one color, and the lowest charge regions a second color. An intermediate charge level, approximately midway between the high and low charge, serves as the background reference and is not printed. The components of the composite two color latent image are developed sequentially using charged area and discharged area development and bipolar developers. Electrostatic transfer is enabled by converting the developed bipolar image to a unipolar image using a pretransfer charging step. Because of the nature of the latent image, a trilevel development system must satisfy demands substantially beyond those required in conventional xerography. This paper will discuss these requirements.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

When Chester Carison invented xerography, he employed sulfur and anthracene as photoconductors. Although the initial commercialization of his idea relied on inorganic photoconductors, the current trend is towards use of organic photoconductors because of their material variety, economy and flexibility. High speed copying and printing machines use belts coated with organic photoreceptors, while personal copiers and printers use aluminum drums dip-coated with organic photoreceptors. Multilayered, organic photoreceptors are now routinely mass produced by the millions with both visible sensitivity for copiers and infrared sensitivity for printers. This paper presents a brief overview of key photoreceptor properties and follow with a survey of electronic organic materials of current interest. The photodischarge characteristic is determined mainly by three factors: the photogeneration, the injection, and the transport of charge carriers. These functions can be accomplished by separate electronic material layers; photogeneration by organic pigments and charge transport by aromatic-amine electron-donor molecules. The photogeneration layers are usually fabricated by solvent coating a dispersion of a pigment in a polymeric binder while the charge transport layers are solvent coated to form a solid solution of the aromatic amine in a polymeric binder. Examples and characteristics of organic pigments and charge transport molecules of current interest are discussed.

Printing at the rate of 75 pages per minute has been demonstrated with a modified Corjet ionographic head mounted on a modified Delphax 2460 printer engine, using grey scale fonts and encapsulated toner. Image quality approaching that of laser xerography was obtained. Very good reliability is predicted for the printer components.

In contrast to other segments of the computer and peripheral equipment field in the last decade, the line printer has seen little real evolution. However, the recent introduction of high speed non-impact laser printers by IBM, Xerox and Siemens represents the beginning of a transformation in printer technology. These units use "laser xerography" to produce clearer output at rates an order of magnitude faster than conventional impact-type printers. Moreover, the technology is applicable over a wide range of speeds and resolution levels, creating some very exciting possibilities in the office of the future. Because of its freedom from fixed type, the laser printer will allow the extension of the word processing function into more general areas of information handling and office printing. In this paper we intend to aid in the development of systems for this application by explaining the components of the laser subsystem and the interrelationships among its various performance parameters.

In xerography, a corona charged photoconductor film transforms an optical image into an electrostatic image that is subsequently developed. A variety of photoconductor materials has been employed in commercial reproduction machines. These include alloys of amorphous selenium with arsenic and tellurium, zinc oxide, and cadmium sulfide particles in organic binders; one and two layer organic systems; and, most recently, hydrogenated amorphous silicon. The physics of the charge photogeneration and transport processes are examined and illustrated with the above materials. These processes are shown to determine the reproduction characteristics of the xerographic system.