The factors which determine laser scanned resolution are reviewed and presented in concise form. Attention is devoted to the aperture shape factor and its numeric evaluation under a variety of shape, illumination and performance conditions. Practical derating factors are presented to account for aberrations. A Nomograph of the classic resolution equation is introduced to provide convenient access to key design parameters. Several examples of its application to typical scanner requirements are appended.

Multiple sensors provide reconnaissance coverage over a wide range of weather and lighting situations as well as over a range of platform operational scenarios. This paper addresses the requirement for an image recorder for reconnaissance ground stations in which image data from multiple sensors can be processed. Sensor types include electro-optical sensors using multi-element CCD detector arrays, infrared line scan sensors using arrays of detectors and Synthetic Aperture Radar (SAR) Side Looking Sensors (SAR/SLAB). Each of these sensors has particular scanning parameters and data rates. To be useful in a multisensor environment, an image recorder must be able to adapt its recording parameters and interface to accommodate the sensor requirements. The primary recording parameters that are effected by a requirement for multi-sensor capability are film velocity and thoughput, line rate, pixels per line, resolution and linearity. The range of performance required for each of these parameters and the techniques used to accommodate the range are presented. A versatile interface is another feature of an image recorder that facilitates use in a multi-sensor environment. Examples of specialized interfaces are given. The application of mature, proven technology to requirements for high resolution image recording systems is addressed and several examples are given. Features and capabilities are presented.

In 1984 Pixar's research and development group built and applied to the motion-picture arts at Lucasfilm's ILM facility a three color laser based film scanner/recorder system. The digital film printer is capable of reading and writing 35mm film formats on a variety of film stocks. The system has been used in award-winning special-effects work, and has been operated in a normal production environment since that time. The primary objective was to develop a full color high resolution system, free from scan artifacts, enabling traditionally photographed motion-picture film to be inter-cut with digital raster image photography. Its use is applied to the art of blue-screen traveling-matte cinematography for motion pic-ture special effects. The system was designed using the Pixar Image Computer and conventional gas laser technology as the illumination source. This paper will discuss recent experimental work in the application of GaAs microlaser technology to a digital film printing system of the future.

This paper describes a high resolution laser writer which has been designed and developed in the Hybrid Imaging Systems Division of the Photographic Research Laboratories of Eastman Kodak Company. It is a polygon based system printing 1800 dots per inch over a 13-inch-long scan line using a diode laser at 830 nm. The writer is compact, cost effective, and straightforward to align. The paper concentrates on the optical design aspects of the writer. The performance of the writer is discussed, as well as the limitation of the technology, and test prints are shown.

Ultre Corporation is the designer and manufacturer of a low cost, high resolution laser recorder, that we market only to OEM system integrators. The recorder makes unique use of the laser diode, the smallest light bulb available to imagesetter designers.

The optical design of a simple, compact, raster-scanning laser printer using three diode lasers and polygon deflection to produce continuous-tone color prints of high quality on photographic paper is described. Several important optical and calibration problems are discussed, and the results of image quality measurements are summarized.

A discussion of the various devices used to achieve grey scales, including an overview of current technology, and applications and projected trends. The various means of exposing media, the advantages and disadvantages of dry silver processing and continuing challenges in the industry are explored.

In general, Laser Beam Printer based on electrophotography is known as a high speed and a high quality output printer. We have developed a new Color Laser Printing System, which consists of 400dpi Color Scanner, Image Processing Unit, and a high quality 400dpi printer. Color Scanner scannes an original image and get 8- bits Red, Green and Blue color image data by CCD sensors. Image Processing Unit processes and converts the RGB data to YMC binary image data to output a laser electrophotographic image by the Printer . The new image processing technology reproduces high quality image output for several kinds of images such as text, halftone dot and photographic images. The algorithm of this image restoration forces edge enhancement only in the region of text and line - art, and forces low - pass filtering in halftone dot region in accordance with the information of image characteristics detecting both edge area and halftone area. We have obtained high quality binary color images by this system. Some print samples processed by the system are compared with those by conventional method.

A highly stable color laser printer has been experimentally developed, which uses a newly devised toner transfer roller, made of elastic sponge rubber sheathed with a plastic resistive layer. The developed color printer attains the following features: i. High quality full color images can be printed under broad operating conditions, e.g. from 20°C,40%RH to 30°C,85%RH. ii. Frequent color adjustment is not necessary because printed image color differences under different operating conditions are within 3. iii. The maintenance interval can be extended; the toner transfer efficiency from the photoconductor drum to the paper is above 85%. The amount of waste toner is reduced to about 1/3 of that for a conventional printer on an average.

We have developed a high-speed, high-precision raster-scan laser plotter for producing images on glass plates. This system is designed for producing precision photo masks used for various electronic devices such flat panel displays as liquid crystal, plasma, fluorescent tube, thermal printer heads, and IC lead frames. The multi-beam laser plotter splits an argon ion laser beam into 40 separate beams, each of which can be individually switched ON or OFF by two multi Acoustic Optical Modulators (AGMs). It works using the raster-scan method, moving the glass plate backward and forward to produce a photo mask. It takes approximately five hours to complete plotting on a photo mask of 500 x 600 mm with a laser spot diameter of 5μmø, a pixel pitch of 2.5μm, and a plotting accuracy of ±5/μm, producing precise and uniform image quality throughout the mask. Because the image is produced by raster-scanning, it is possible to plot a mask of a given size in a fixed time regardless of variations in image data volume. This plotter can therefore produce a standard photo mask in a fraction of the time needed by conventional vector-type photoplotters.

A laser color printer has been developed to depict continuous tone color images on a photographic color film or color paper with high resolution and fidelity. We have used three lasers, He-Cd (441.6 nm), Ar4⁺ (514.5 nm), and He-Ne (632.8 nm) for blue, green, and red exposures. We have employed a drum scanner for two dimensional scanning. The maximum resolution of our system is 40 c/mm (80 lines/mm) and the accuracy of density reproduction is within 1.0 when measured in color difference, where most observers can not distinguish the difference. The scanning artifacts and noise are diminished to a visually negligible level. The image quality of output images compares well to that of actual color photographs, and is suitable for photographic image simulations.

Thermal inkjet heaters were studied by infrared microradiometry using an apparatus similar to that reported in the literature. An InSb infrared sensor is mounted on a modified Leitz microscope equipped with a 36X reflecting objective. The system looks at a spot on the heater about 14 μm in diameter. The locally emitted infrared output is used as a qualitative measure of the local temperature. The temperature distribution on the heater surface is studied by constructing two-dimensional temperature contour maps. Current pulsing is carried out in air or in the presence of a high boiling point liquid. Other variables include pulse width, frequency, voltage, and heater geometry. Temperature profiles obtained in this way are in good agreement with those obtained from modeling calculations. Cycling has been carried out with several different passivation coatings with an emphasis on Ta passivation. Microradiometry of Ta-passivated heaters is complicated by the formation of Ta₂O₅ under most pulsing conditions and Ta₂O₅ has a much higher emissivity than tantalum. Burn-in curves (infrared output versus time) are used to monitor this oxidation process. Since the Ta₂O₅ thickness is not uniform over the heater surface, an accurate interpretation of the temperature contour maps of Ta-covered heaters is not easy. Microradiometry data of oxidized Ta heaters are supplemented with data obtained using optical microscopy, SEM, and profilometry. By overstressing heaters, hot spots were generated and studied using temperature contour maps. Subsequently, failed heaters were studied using SEM, and from these data failure mechanisms are postulated.

This paper discusses the damage to various passivation layers protecting Thermal Ink Jet heaters by the collapsing vapor bubble. The heater damage experiments were performed in either the printhead operational mode or or in an "open pool" configuration. The heaters described are located in a printhead channel and the passivation materials tested were Si0₂, Si₃N₄, TiW and Ta. Optical and SEM micrographs detailing the initial and later stages of cavitation damage have been taken and a comparison of heater damage/failure as a function of pulse number obtained. A discussion of the damage mechanism for the various passivation materials and the effects of bubble collapse and consequent cavitation will be presented.

A quiet revolution in the world of imaging has been underway for the past few years. The older technologies of dot matrix, daisy wheel, thermal paper and pen plotters have been increasingly displaced by laser, ink jet and thermal transfer. The net result of this revolution is improved technologies that afford superior imaging, quiet operation, plain paper usage, instant operation, and solid state components. Thermal transfer is one of the processes that incorporates these benefits. Among the imaging application for thermal transfer are: 1. Bar code labeling and scanning. 2. New systems for airline ticketing, boarding passes, reservations, etc. 3. Color computer graphics and imaging. 4. Copying machines that copy in color. 5. Fast growing communications media such as facsimile. 6. Low cost word processors and computer printers. 7. New devices that print pictures from video cameras or television sets. 8. Cameras utilizing computer chips in place of film.

Applications involving the electronic capture and/or the electronic generation of "photographic-like" images are becoming increasingly important. Such images can be generated from a variety of sources, including electronic still cameras, video camcorders, medical images, computer graphics, and scanned film. These electronic images can be conveniently processed and stored, but until now there has been no convenient way to convert these electronic images into true "photographic-quality" hard copy.

A brief introduction to continuous tone, dye sublimation transfer printing using a thermal head is given. Two problems that can arise in such a method of printing are discussed: density non-uniformities down the page due to the accumulation of heat in the thermal head, and density non-uniformities across the page due to variations in electrical, thermal or mechanical properties across the line of heating elements. Measurements and analyses of these effects are presented. Correction methods are proposed and implemented, and results are shown for each of these problems.

Advances in electron beam recording technology have made possible high quality hard copy output at throughput rates which are an order of magnitude or more faster than any other recording technique. The greater dynamic range and consistant excellent quality of the Electron Beam Recorder (EBR) output has provided very cost effective production of Aerial and Satellite Imagery, Geophysical Seismic Data, Graphic Arts Publishing, Cartographic products, Computer Output Micrographics, Movies, and Computer Assisted Retrieval Data Storage Output. The electron beam technology is described with the advantages provided for these various applications.

Processless Electron Recording Media are film-based recording materials that instantly produce an image when scanned by a beam of electrons in an electron beam recorder (EBR). No chemical or physical processing is required in order to develop or generate the image. PERM^tm is the GAF Chemicals Corporation trade name for this type of film.

A new photorecording device, the E-beam Sabrecon, for monochrome or color hard copy applications, has been developed. Based on the electron beam/phosphor/fiber optics principle, the new device is cylindrical in form. It incorporates a phosphor coated fiber optics strip mounted along most of its length, with an electron gun aiming an e-beam along the cylinder parallel to the phosphor surface. A series of electromagnets deflects the beam into the phosphor screen to produce a continuous single line scan, which, with video modulation, sequentially records an image on the photorecording medium passed across the external fiber optic, surface, The Sabrecon is much more compact than a conventional CRT and has a number of other advantages.

Mead Imaging's unique microencapsulated color imaging system (CYCOLOR) has many applications. Mead Imaging and Hughes have combined CYCOLOR and Fiber Optic Cathode Ray Tubes (FOCRT) to develop digital color printers.

In the discussion of color ink-jet technology that follows the areas that will be covered will be the principles of operation of Ink-jet technology and its performance vectors (where Hewlett Packard has been and where do we view ourselves going over the next few years). Image enhancement techniques that are being developed will be covered as will the associated image processing requirements that they will generate.

Mead Imaging is commercializing Cycolor^®, a revolutionary photoimaging system which will have broad applications in color copying and reproduction, referred to as cylithography. Cycolor possesses the following characteristics: • panchromatic sensitivity • dry processing • high resolution • continuous tone • high color quality • low cost. The Cycolor system is a result of work carried out at Mead Corporation over the past several years on the microencapsulated process.

As electronic imaging becomes a mature technology, the requirements of hard copy output systems become more demanding. Currently, color hard copy output is required with a 3- or 4-bit tone scale. However, many present and future applications will require a 6- to 9-bit tone scale. Current electronic imaging systems requiring this extended color tone scale include "high-end" computer graphics, remote sensing and medical imaging. Bimodal hardcopy output systems that use dithering to achieve a tone scale will not be able to meet the requirements of these new electronic imaging systems. In order to minimize the complexity and cost of a new hardcopy output system it is desirable to have an electronic interface rather than an optical interface (as in a photographic film recorder). Thermal dye transfer hard copy (TDT HC) meets the demanding requirements necessary for affordable, high quality "continuous tone" electronic imaging output.

An excellent image quality full color hardcopy system with easy maintainability has been developed. The system is characterized by a new type of color phtotothermographic material and also by light-emitting diodes (LED) as the light source for image exposure. The output images have good tonal and color renditions as well as an extreme low level of granularity, mainly owing to the photothermographic material • based on silver halide photo-sensor. As the chemistry and the hardware outline of the system have been reported elsewhere, the present paper will describe some features of its image exposure sub-system.

Significant technical progress has been made in Dry Silver Color technology in the past 12 months. Good color saturation can be obtained in as little as six seconds with several electronically addressable light sources. The quality of the color and the simplicity of the process is creating considerable interest for many industrial and scientific recording applications. This paper will describe how the process works and review recent technological accomplishments and future expectations.

This paper outlines the technical trend toward 2-color plain paper copiers (PPC) and new improvements in a double layer 2-color organic photoconductor (OPC) by Ricoh.

The use of a pin array to form electrostatic images has been successfully employed in printers and plotters over the past several decades. The economically successful extension of this technology into the area of high quality, high-speed "plain paper" imaging systems has, up to now, eluded the grasp of scientists and engineers.

The already low cost of the thin-film electroluminescent (TFEL) edge emitter imaging station will be further reduced by implementation of a multiplexed drive system. Therefore, the multiplexing modes for TFEL edge-emitting devices were examined. Several multiplexing modes were tested and 12.5% duty cycle was selected as having the potential to be the most economical. It was demonstrated that the output power required for printing can be maintained at this level of multiplexing.

We have proposed a new adaptive dot density LED printer with simple zoom optics using a high power GaAlAs LED array. A suitable dot density for any system is easily obtained by the printer.

New opportunities are emerging in the graphic-arts pre-press market stimulated by the need for digitally created images. To meet this need, we have designed a cost-effective three-color digital printer using PLZT light valves. Transparent lead lanthanum zirconate titanate (PLZT) ceramic crystals when used as a linear modulator offer a number of significant benefits. The primary advantage is that the light valve is an efficient modulator of incoherent light providing a broad spectral output ranging from 400nm to well into the infrared region. In addition, light valves offer the advantages of being small, low cost, have a wide dynamic range (>1000 to 1), and can be used with simple optical designs. The characteristics of the PLZT material plays an important role in the performance of the light valve. A number of variables such as ceramic composition, electrode spacing, and ceramic thickness can be altered to affect its quadratic electrooptic behavior. Additionally, the modulator design requires a closed-loop servo to eliminate the errors caused by the device's remanent polarization and nonlinear behavior.

The practical use of Hi-Vision (HDTV, High Definition Television), a new quality television system, is close at hand. It is advantageous to apply Hi-Vision technology not only for moving pictures but also for still pictures like hardcopies. As the input signal inproves in quality, hardcopy should also increase in quality. In order to reproduce beautiful pictures, the hardcopying system must have: 1) A recording method of direct density modulation to ensure good gradation and resolution. 2) A recording stylus and medium for the reproduction of the recording dots (pixels) with few reproduction errors and minimum resolution loss. 3) The ability of suitable signal processing to transform video signals to still pictures for printing and to match them with printer characters. A new system has been developed to fulfill the above requirements, having a signal processing circuit and a sublimation-dye type thermal transfer printer. After experimenting with the reproduction of pictures, we are now able to obtain hardcopies with quality close to conventional photographs.

A three-dimensional fluid mechanics analysis of a bubble growth and collapse has been carried out for some thermal ink jet printhead geometries. For that purpose, a computer code has been developed which can handle multi-valued free surfaces that arise in such geometries. This paper presents sample results which show how the bubble grows and collapses, and how it differs with geometrical changes.

Novel printing ink has been developed based on polymeric gel having the nature of gel to sol transition caused by application of electric voltage. The polymeric gel ink consisted of polyvinyl alcohol) (PVA) partially crosslinked with borax, carbon black as a pigment, and water. Printing facilities was also designed. Polymeric gel ink with electric conductivity 4.0 x 10^-3 Ω^-1cm^-1 was used. It could offer resolution of more than 200 dots per inch (dpi). Image density was fully controlled from 0.05 to 1.5 as optical density by application of electric voltage of 3 - 12 V. An advantage of this printing system was that polymeric gel ink not only acted as ink but also as the support.

The Direct Negative/Direct Plate (DNP) technology was developed for use with the IBM 4250 electro-erosion printer. This new printer supply allows either negatives or offset printing plates to be printed out directly from the IBM 4250 without any chemical processing. Since the introduction of the original DNP product , under the tradename electroNeg, we have continued to make major improvements in the functional characteristics of the material. These improvements encompass a) Improved optical quality, b) Reduced scratching, c) Increased press life and d) Far greater resistance to handling and environmental corrosion.

The Direct Negative/Direct Plate technology employs electro-erosion printing techniques to directly generate negatives and offset printing plates suitable for use in many printing and publishing applications. Recently we have been developing materials which yield functional characteristics which are considerably improved over the first product (IBM electroNeg) to use this process. The physical parameters that govern the suitability of materials for use in the demanding environment of both electro-erosion printing and offset printing is discussed and some results and techniques for measuring these parameters described.

In the first part of the paper the use of different paper qualities for different non-impact technologies is discussed.Special output technologies are explained and also the possibilities to use plain bookpaper is pointed out. The main technologies like electro-photography, electrography, ink-jet, magnetography and thermography are shortly explained and the state of the art of papermaking in connection with technology development of non-impact printers is listed. Also a short explanation is given about the 2 main directions of research 1. Developing paper for non-impact technologies 2. Developing non-impact technics for a special paper quality The quality parameters of the different technologies in respect to paper are mentioned and specifications are given for different paper qualities used for special non-impact procedures. At least the efforts of a modern paper mill producing new paper qualities and their testing programs for a constant quality of paper are shown. Also areport is given, how to get figures about the runability of paper and also which short testing procedures are useful for the enduser of hard-copy-paper. In the summary a table of special paper parameters for special printing technics is given.

In the fusing process in electrophotographic machines, the temperature field and melting in the toner during fusing are important factors. As a first step leading to quantitative analysis, methods to measure the following conditions are developed: heat flux and unsteady temperature change on the toner surface by flash fusing, thermophysical properties of the toner and the paper, and toner deposit thickness and coverage. The measurement results are applied to the boundary conditions and thermophysical properties in an analysis using the finite element method. A model configuration is constructed with a toner layer and a paper layer. In this way, a one-dimensional unsteady temperature distribution is analysed. As a result of the analysis, the following points are made. During the time when fixing is performed, the maximum difference between the temperature on the toner surface and on the toner-paper interface is more than 200°C, regardless of the kinds of toner; this is attributed to very low thermal properties of the toner powder. At the same magnitude of fixing strength, the toner surface temperature level varies about 100°C with the kinds of toner. However, the toner-paper interface temperature is roughly the same regardless of the kinds of toner. Therefore, the interface temperature level is considered to be the lowest limit for fixing. On the other hand, the melt viscosity superposed on the temperature field varies little with the kinds of toner on the mid-region in the toner layer. It is also considered to be a requirement for fixing.

This report describes R2T2, a dynamic thermal printing process. Print quality is dependent on many printing parameters interacting with each other during ink transfer. The entire transfer process can be divided into five stages: heat, melt, adhesion, separation, and solidification. The report deals with the ink and printing parameters most pertinent to print quality. The ink transfer temperature determines the printing power as well as the ribbon stability. The viscoelasticity and adhesive property of the ink-melt influences the actual print quality. Contact pressure, heat transfer, ink adhesion, and separation also play important roles. The effects of all these factors and the limitations of print speed arc discussed as well.

Graphic Arts imaging requires high contrast materials to generate halftone dots for controlled tonal reproduction in lithographic printing. Off-press color proofing systems must accurately reproduce the halftone patterns with very controlled maximum reflection density. Direct digital color proofing (DDCP) writing technologies are currently being developed to produce full color halftone proofs directly from digital data with electrophotographic processes having advantages in use of cost effective lasers and high spot addressability. Colored liquid toners are known to produce high resolution and contrast dependent on the electrophoretic mobility and conductivity of the toner dispersions. However, the interactions of the materials in the electrophotographic machine with a specific writing light source are critical to the precise reproduction of the full halftone dot range in the DDCP. The effects of colored liquid toner electrophoretic properties on the reproduction of halftone dots developed onto laser exposed photoreceptor are described in this paper. Several liquid toners with different particle mobility, conductivity, and charge per mass are used to relate process conditions such as deposition field and development time to optical density of the image and area coverage or halftone dot gain of the toner deposit. Microdensitometer traces and scanning electron micrographs of liquid toner developed laser scan lines are used to evaluate edge sharpness and density uniformity. The electrostatic field generated by the latent charge pattern in a uniform geometry is calculated and an electric field dependent deposition model is described to determine the size and optical density of the laser scan line for various liquid toner formulations. This model may be used to optimize the process conditions of a specific laser writer to obtain the required halftone reproduction for direct digital color proofing.

In designing ink jet printing devices, the greatest challenge is not in the design of the mechanism nor control aspects of the head. Surprising to many, it is the difficult task associated with the formulation of inks, toners and papers which will give you a suitable image. This image must possess good chromatic and archival characteristics. In the past, inks were the cause of much criticism associated with the bad reputation of ink jet printers; and rightly so. The inks used in ink jet printing were expected to perform many difficult tasks. They were subjected to evaporation and stability tests at high temperatures. They were expected to retain their physical parameters of viscosity, surface tension and pH for months in an oven at 40-60° C. Yet, when they were emitted onto a piece of paper at ambient conditions, they were expected to dry within 3 seconds. Chemists who were formulating inks based on criteria established by mechanical and electrical engineers were at a disadvantage. Inks were not considered a major component to other groups in the development program. Yet inherently, the ink was causing the majority of system failures due to head clogging, component breakdown, etc. The ink chemist was at a distinct disadvantage to begin with. A major cause for orifice clogging was the precipitation of salts out of the dye. Dyes may contain as much as 20 percent salt. A dye with less than 1 percent salt content was not available a few years ago. Today, however, dye manufacturers see the increase of requests for purer dyes and are making them available for a premium. There were not any specialty papers available for ink jet applications. Inks would either sit on the surface of the paper and not dry, or they would cause feathering or bleeding problems. Today there is a variety of papers available for ink jet systems.

In the recent years, thermal ink jet (bubble jet) has emerged to become a fast growing printing technology with market applications first aimed at the low end, high quality and color workstation printers. The break-through in this ink jet technology came in the areas of low cost/high volume manufacture using semiconductor thin-film processing, improved apparent reliability and the ability of high quality printing on wide range of office papers. Although the print head technology appears simple and compact, the underlining thin-film structures, micro fluid channels and drop generation process are by no mean straight-forward. In fact, the ink chemistry, the material integrity and the device physics are closely coupled to provide the proper functionality of the print engine. Hence optimization of the technology can only be achieved through complete device integration. In this paper, the basic implementations of the thermal ink jet technology is presented. The physics of bubble/drop formation process is described using results obtained from our experimental studies. Different failure modes of the electro-thermal drop generator (in particular, the thin-film resistive heater) are discussed. Results can be extrapolated to obtain a basic understanding in the requirements of the ink media and the material structure. Based on the current knowledge of this printing method, projections of the technology limitations in practical implementations can be made to support a view that thermal ink jet will become the dominant low end printing technology in the near future.

The stroke-width and halftone print fidelity from an electrophotographic (EP) printer is dependent on the size and shape of the discharge exposure spot. However, there are conflicting requirements on the spot size in that a large spot is needed to prevent scan lines in discharge areas, while a small spot is needed to print fine details. Others have proposed methods of optimizing the spot size. This paper presents the analysis and experimental verification of a data-dependent method of exposure control that allows the simultaneous satisfaction of both requirements. The result is better print fidelity over a broad range of applications from text to halftone images. This approach also leads to the more general result that, under certain conditions, the print fidelity from EP printers can be independently controlled, thereby allowing a greater latitude in the optimization of electrostatic set points, developer parameters, and optical spot size. This independence also allows relatively simple compensation for variations in other parameters that affect fidelity as well as adjustments based on user preference.

Ordered dither, the class of digital halftoning techniques which uses a periodic array of thresholds, is generalized for both rectangular and hexagonal grids, by means of the spatial method of recursive tessellation, a sub-tiling algorithm. The nature of the texture patterns so produced is illustrated and examined in the frequency domain, revealing several insights within and between the classes of rectangular and hexagonal grids. A simple explicit expression is derived which allows the use of the rectangular DFT to compute a hexagonal Fourier transform, maintaining continuous-space dimensions. Digitally produced examples are included.

High performance laser recorder systems require the use of many subsystems to perform auxiliary functions that preserve and enhance image quality. For example, image quality is preserved by subsystems that minimize pixel jitter and facet signature. Additionally, recorder operability and flexibility is greatly increased through the use of microprocessor controlled status and control buses. Microprocessor control architecture allows existing modes to be modified or new modes to be added to the recorder by altering the firmware. A menu driven control panel provides a user friendly interface by limiting the number of decisions required by the operator yet still provides control flexibility. Verification of performance or troubleshooting activity is aided by the versatility of microprocessor controlled test pattern generation. Annotation information generated by the recorder is recorded onto the film and provides valuable archival documentation. Where near real time imagery is required, a wet or dry in-line film processing subsystem, can be incorporated into the recorder design. Using these concepts a recorder system has been built that can record in excess of 10,000 pixels per line onto five inch wide film, at a line rate of 6000 lines per second. Another recorder system has 15 modes to support 4 different sensors and a film speed range of 40:1. Both recorders utilize in-line wet film processors that provide film ready for viewing in near real time. This paper will describe some of these auxiliary subsystems and show how these subsystems impact the overall performance and utility of a recorder.

We investigated water-based ink-jet inks which fix quickly on plain paper. Ink-jet inks have liquid components which evaporate slowly to prevent the print head nozzles from clogging. The fixing time of these inks is too long for printing on plain paper. Inks cannot penetrate paper which contains a sizing agent, which increases the paper's resistance to liquids. The most widely used sizing agent is rosin. We attempted to shorten fixing time by including in the ink, a component for dissolving rosin. The glycols used in the ink are useful because they evaporate slowly. We determined the relationship between the solubility of the ink for sizing agents, rosin, and the time needed for fixing and penetration. The higher the solubility of a glycol for rosin, the faster the penetration of the ink containing it. Hexylene glycol dissolves rosin over 70 wt%, and ink containing over 15 wt% hexylene glycol penetrated plain paper within 5 seconds.

The introduction of letter-quality, plain-paper, ink-jet printers such as Hewlett-Packard's DeskJet Printer portents a dramatic change in the 1990's office. The ability of ink-jet to offer low-cost, letter-quality print on plain paper positions this technology squarely along with others used for mainstream office printing. The ability of ink-jet to operate on "plain-papers", coupled with the rising use of paper in office printers, suggests that users will begin to demand office papers that are compatible with this technology. Hewlett-Packard is actively working to understand what customers need from office printers and how these needs impact office papers.

The DeskJet thermal inkjet printer was introduced in February 1988 and represents a landmark in printing technology. The DeskJet pen is the culmination of seven years of linked projects involving market research, product, process, ink, and assembly development. We have introduced three inkjet architectures since 1984 they are summarized in figure 1. Two contributions stand out for the DeskJet pen. First is unquestioned letter quality shown in figure 2c and second is its ability to print on plain paper. A brief look at the history of the DeskJet program will explain why we arrived at 300 DPI printing, however; by far the most critical and difficult issue for the DeskJet pen was the decision to print on plain paper. Following is a brief history of the DeskJet pen and a discussion of some of the critical issues in its development.

Typically, drop-on-demand ink jets have been operated so as to form a nearly spherical droplet in flight prior to impingement on the substrate being printed. Generally, this condition is obtained very near to the threshold at which droplets are just formed and the jetting velocities are of the order of 3 to 5 m/s. In the Dataproducts ink jet device, jetting velocities are of the order of 10 to 13 m/s. In this case, the element of ink that impinges on the substrate to form a dot is comprised of a leading, nearly spherical head followed by a relatively thin elongated tail (a "ligament") moving at a somewhat slower speed than the head. There are advantages to this high-velocity mode of operation including minimization of dot placement error, improved droplet aim, and reduced susceptibility to crosstalk effects on jet velocity. In this paper, discussions and strobe-illuminated photographs of the ligament formations and droplet shapes are presented. The potential consequences for jet performance and print quality with such droplet shapes are also discussed.

One of the challenges of 960 dot-per-inch resistive ribbon thermal transfer - R2T2 - printing is the control of energy delivered to the print head to assure very high fidelity printing. A method of manipulating image data to combat the undesired effects of thermal printing is presented. A brief review is given of some of the unique approaches required to construct a prototype of an inexpensive, near-typesetter-quality, desk-top machine, including techniques for fabricating a 960 dpi. R2T2 print head and a closed-loop paper incrementing technique. Print samples and examples of processed data for printing are presented.

A multiple-laser-diode printhead using a close-spaced array of single-mode optical fibers has been developed for large-format, high-resolution laser printing. This head avoids the output interaction problems of multiple-laser arrays on a single GaAs substrate, while providing small spots, close spacing, low noise, and a compact assembly. Each of the separately packaged laser diodes is controlled by current modulation, and its emission is coupled into the input end of a single-mode optical fiber. The array is made by mounting the fibers in a crystailographically etched set of parallel V-grooves in a silicon wafer. The fibers are specially prepared to allow close spacing. Single-mode fibers are desirable because their outputs can be imaged to give diffraction-limited spots. Close spacing of the multiple sources is desirable because the imaging lens utilizes a smaller field of view and requires less demagnification to give closely spaced scanlines. In order to further reduce the spot spacing to increase spot overlap, the writing head can be tilted with respect to the scanning direction, or the exposure tracks can be interleaved. Tilting requires appropriate pixel-data delays and tighter tolerances on the planarity of the array. A new and more convenient method of interleaving has been developed.

A novel laser beam deflector that utilizes rotating holographic gratings in a pyramidal geometry is described. Total rotational symmetry with regard to imaging properties is achieved with this deflector geometry, and therefore, it can be used for either flat-field or internal drum scanning applications. The scan beam from this deflector is bow free and totally uneffected by deflector wobble and centration errors.

The design and analysis of a novel motor and bearing assembly for a polygonal laser scanner are discussed. Static and dynamic characteristics of this assembly are investigated. A detailed analysis of bearing stiffness and load capacity at various rotational speeds is presented. The analysis also treats the dependence of magnitude and phase angle of the bearing reaction on the frequency of motion. The criterion for a relative transverse and angular oscillatory motion stability of the bearing surface is discussed. The analysis is compared with experimental results from a prototype.

The purpose of this paper is to investigate the interchange between gradient-index and homogenous optics for correction of laser scanning cross-scan error. The advantage of gradient-index (GRIN) optics being that a cylindrical corrector lens can be replaced by a piano parallel GRIN element and a toroidal corrector lens can be replaced with a weak cylindrical GRIN element.

It is well known that a monolithic arrayed laser diode is effective for a high-speed laser beam printer. In terms of the angular relation between the arrayed direction and the laser beam scanning line, two typical laser scanning optical systems using a monolithic arrayed laser diode are comparatively discussed in this paper. As for the first optical system, the arrayed direction is slightly tilted from the scanning line's direction. While this system has an advantage of easiness in the data processing technique in comparison with the other optical system, we have to pay attention in designing and manufacturing this optical system in terms of accuracy and complicateness. The second optical system forms a striking contrast to the first. The laser's arrayed direction of the second optical system is perpendicular to the laser beam scanning line. In this system, we need no such particular designing nor manufacturing as in the first one described above, but interlacing scanning method and the relevant data processing technique. Through comparing the above two systems, we are discussing optical issues. As the conclusion, we think, the second system of interlacing method would become popular in consideration of the future advances in data processing technique.

A high-quality, compact, low-priced, and completely plastic scanning lens system for laser beam printers (LBPs) is now being readied for mass production. The key to its development was the use of aspherical and anamorphic scanning lens surfaces, including a newly developed "modified cylindrical surface". These surfaces made wide field angle and temperature change compensation possible through the effective control of field curvature, fe linearity, mirror tilting, back focus length, focal point change, and scanning width change. This paper describes the function and development of the system.