In 1842 Ronalds called down lightning from the sky to generate the world's first ion print. His "Recorder of Atmospheric Electrical Events" employed a wire, supported from an elevated anchor paint, as a atmospheric charge collector. The wire was connected to a stylus which radially traversed a rotating insulating disk to form a spiral track on the surface of the disk. When the potential across the recording gap at the tip of the stylus exceeded the breakdown strength of air, a discharge occurred which formed an electrostatic latent image on the surface of the insulating disk.
The Corjet1 is an air-assisted ionographic printing device that offers advantages in the design of xerographic printers over the conventional laser scanned systems. The practical implementation of this technology required the solution of certain unique problems during its evolutionalry development.
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.
High resolution gray scale ionographic printing requires the ability to deposit different amounts of charge on specific but very small areas of an image receiving dielectric. The dynamic process of the dielectric surface charging has been studied. It is being shown that with increase of the deposited charge the trajectories of charged particles are more increasingly affected by the blooming effect.This effect becomes the major limiting factor in attainment of high resolution printing which at the moment for Delphax printers using monocomponent inductive toner is about 18 lines/mm.
Print quality deterioration can also be caused by the latent image fringing electrostatic field. In some cases, particularly if dark and very light areas are to be printed side by side, the fringing field influence can result in the pattern shape or printed gray level degradation. Possible compensation for it by using multiple dielectric layer as the image receptor is discussed.
Stable charge emission from ionographic printheads is a crucial for high quality printing. Differences in gray scale and dot size will occur with varying amounts of emitted charge. Charge output analysis on Delphax printheads, using RF-bursts for charge generation have been conducted. Significant variations between negative and positive charge output has been recorded. It has been shown that these variations can be evoked by differences of dielectric surface charging rates during oppositely charged particles emission. High instability in negative charge output, particularly at the beginning of RF burst has been observed. Charge output stability has been significantly improved by enlarging of ratio between speed of RF-voltage increase and rate of dielectric surface charging, along with increasing the number of ionization sites. Improvements of two orders have been experimentally confirmed.
A novel ionographic imaging device, the Corjet, is described. The physical principles of the device are discussed, and a number of the factors that determine the imaging capability of the device are considered.
This paper provides an up-to-date status of the continuing effort at Bull to further improve the speed and productivity of magnetographic printing and explore new potential applications. Besides puting into perspective the whole research and development program in Very High Speed Magnetographics (VHSM), the paper deals more specifically with the design, construction and testing of full size, full function, prototypes of a Press Integrable Magnetographic (PIM) module. Major guidelines for the project have been: (1) consistent print quality at variable speed over a full range of speeds, (2) accomodation of high web tensions as may be required by a press, (3) printing process totally slaved to the paper web motion as imposed by press environment, (4) extended range of printing media. Development steps, technical approaches chosen and measured performances are discussed.
Computer-intensive image processing for film recording can be significantly reduced by using the flexibility of a digitally controlled electron beam recorder (EBR) to accomplish radiometric and spatial changes during exposure.
While recording, on a pixel-by-pixel basis, radiometric changes can be introduced with a digital gamma exposure control for sensor radiance uniformity corrections, image enhancement techniques which meet the processing application, the exposure media used and final display requirements.
All spatial changes can also be accomplished during recording for time displacement errors of the sensor, Dlatform movement and final image display by digital geometric correction control commands.
For wide field of view images (20,000 pixels x 20,000 lines) an EBR can eliminate extensive radiometric computer preprocessing for recording hard copy.
The image exposure, determined by the processing work station algorithms selected by the operator using the small field of view, workstation softcopy display may be used to digitally control the EBR exposure for recording the very wide field of view.
Digital control enables full use of the inherent flexibility of an EBR to record multiple types of sensors thereby maximizing the enhancement needed for the individual sensors.
The analysis of the physical condition of the developer in the copier during the copying process requires a lot of time and much technical expenditure and sometimes also a limited modification of the equipment. The knowledge of changes in time and place in the condition of the developer in the development zone is, however, essential for understanding the proceedings while electrostatic picture reproductions.
With the popularization of various types of plastic cards with embossed pattern, such as credit cards and ID cards, there has been the need for hardcopy of embossed pattern to identify the user. At present, embossed pattern is copied with an inprinter using carbon paper. We have developed a method of making hardcopy of embossed pattern, based on a new concept. In this method, embossed pattern is read optically by a contact-type image sensor, and converted into electrical signals. The hardcopy of embossed pattern is obtained with an image printer. Using this method, not only embossed pattern but also image pattern can be processed and stored as electrical signals.
In order to obtain satisfactory smoothness and sharpness in images as regards the sublimation-type thermal dye transfer printer, the following problems are discussed to be compensated.
(1) Unevenness of optical density in main scanning direction
(2) Drop of voltage depending on the number of driven heating elements
(3) Thermal effect due to adjacent heating elements or preceding lines
(4) Time lag at heating-on and off
We estimated the thermal influence of the above problems by numerical computations. As for the experiments, we compensated the energy applied to the heating elements. As a result, we have obtained good smoothness and sharpness in images.
A key element to printing high resolution grey level images using resistive ribbon thermal printing technology, is the ability to fabricate a high density electrode print head. To print at 40 dots/mm resolution, the print head electrodes have to be on 25 im centers. Each electrode having a width of 15 to 17 /im. Wet etching techniques can not etch such structures in 25 thick tungsten. A reactive ion etching process suitable for manufacturing high resolution print heads from a tungsten sheet has been developed. Various system parameters were studied, such as gas mixtures, system vacuum pressure and applied RF power, with the goal of achieving an optimum etching process. The results identified SF6 based gas mixtures as the most suitable candidate for high volume removal of tungsten with an acceptable etch rate and edge profile. To study the print quality at 40 pel/mm, other parameters such as ink ribbon and paper surface finish were also investigated. An ink layer thickness and a paper were selected to match the quality of the high resolution print head. The electric power requirements to print single pel features repeatedly was studied.
By flowing the electric current to heat elements of thermal head, the sublimation dye ink is heated, and the ink is transferd to receptacle paper. In this case, by diffrence of shape and pitch of heat elements, the quantity of ink transfer is varied, and so the optical density on the receptacle paper surface is varied.
When the shape and pitch of heat elements are large, the optical density characteristic become none-linear, and so the maximum optical density cannot be high. On the other, when the shape and pitch of heat elements are small, the characteristic of optical density is good, and the maximum optical density obtain high. But the shape of heat elements cannot be too small, and when the pitch of heat elements is small, the printing data are increased, and so the printing speed become slow. We analized these influences in sublimation dye thermal transfer, and selected the condition of high optical density so that high resolusion can be realized.
The IRIS 3024 and 3047 ink jet printers are capable of placing from 0 to 31 18 µm diameter drops of each color ink in each pixel. A graph showing the number of drops per pixel of a specific color ink versus the optical density of the printed area is not linear. We attempt to explain the shape of this tone reproduction curve (TRC) and linearize it by approximation. The linear TRC helps reduce false contours and facilitates adjustment of image contrast and average density.
Ink jet printing demands that excess water on the surface of the printed substrate be removed within a set time. In addition, other requirements should be met: acceptable print quality, low sheet deformation, minimal strike-tnrough, minimal feathering. The set time is ictated by substrate path and substrate process speed. Mechanisms to remove the water from the surface are referred to as dryers. A slow drying rate can result in image offset or smear, excessive image spreading or penetration which will result in deformation due to stress relaxation. Typical drying mechanisms are: surface evaporation, diffusion of ink into the substrate or surface blotting .
In the present study, various experimental methods and techniques for efficiently drying inkjet images printed with aqueous ink formulations on plain paper have been developed ana where applicable, numerical analysis have been correlated with experimental data.The drying methods which have been explored should be able to satisfy drying requirements of Ink Jet printers and copiers with a wide range of substrate throughput.
Highlights of conductive, convective and infrared drying and combinations thereof are presented. The metrics for defining acceptable drying in terms of moisture content of paper and image offset density are discussed. Criteria for choosing the optimum dryer so as to optimize trade offs between power consumption, cost, size, architecture and efficiency are also discussed.
Du Pont has developed new silver electrostatic master technology suitable for making multiple copies of high quality prints. A digital laser image is captured by a multilayered silver halide film and diffusion transfer chemistry is used to form a unique conducting silver image in a polymeric insulating layer. For prints the silver master is corona charged; where there is a silver image, charge is bled off to an underlying ground plane and where there is no silver, charge is retained by the insulator. The charged master is then developed with high resolution liquid toners and the toner image transferred to paper. The charging, toning, and transfer steps are repeated for multiple copies. Quality is maintained at printing rates exceeding 8 inches per second. The silver master looks like a normal photographic film and is processed like one but has dual functionality; it can be used as an electrostatic printing master and as a normal photographic film, i.e., as a graphic arts intermediate. The master will be described in more detail and examples shown.
This paper will review the needs of prepress proofing, then, point out some limitations of current proofing methods. After this, DuPont's new technology aimed at providing a modular "ink-on-paper" proofing system, will be described first, the concept, then the overall process and components of this system. And finally, the capabilities of this technology will be summarized
Great interests have been focused to the computer-to-plate system for more than decade years, since the system would be instrumental to the future development of graphic arts industry. Very few models have been commercialized, though many attempts have been expedited. In 1983, we released an OPC metal plate for the use of laser direct prepress system of the Wall Street Journal via satellite data transmission. We have believed there is still a spacious market niche, if we can develop an adequate direct prepress system by utilizing of the currently available computer technologies and material science.
An electrostatic imaging system using permanently imaged photopolymers as printing masters is being developed for producing multiple copies of four color proofs with high productivity and consistency. The imaging element - the master film, is based on electrical conductivity change induced by photopolymerization. After corona charging, the electrostatic latent images are developed by liquid toners and the toner images transferred to a receptor in sequence to yield a color proof. The original photopolymer images may be re-used to produce multiple copies by repeating the charging, toning and transfer steps.
This paper describes the Coulter Systems Corporation Laser Color Recorder, which records three color - Red, Green, Blue (RGB) - continuous tone images of up to 8196 by 10240 pels, up to 12 bits deep per color, on most color films and papers. This recorder produces images in formats from 35 millimeter half-frame to 12 by 18-inch. Half resolution, up to 4096 by 5120 pels is also available. All image formats have the same available resolutions except for differences due to aspect ratio. The basic writing engine will produce an image in less than five minutes, in any format and resolution. Additional digital processing modules will be available to provide a wide variety of interfaces, real time scaling for resolution adjustment, color coordinate conversion (e. g. CMYK to RGB), and "printing type" halftone screening.
We started delivering our 1440 Platesetter, a computer-to-infrared laser plate system, a year ago. I plan to discuss how this product will benefit users in the prepress and press industry, and how this technology combines five steps into one computer-to-plate process. The five steps are typesetting, keylining, camera, stripping and platemaking. The reduction of these steps increases productivity and decreases operational costs.
The AC discharge method of ionographic printing developed at Dennison during the late seventies employs a large array of individual printing sites. Obtaining uniformity among these sites has long been recognized as a requirement for high quality printing. Recently, attention has been directed toward improving the uniformity of the output from any one site.
This paper describes an experiment to measure the charge produced by an individual ion generation site. The apparatus constructed directly records the charge produced by 4096 consecutive AC burst firings of one site at a rate of 12 KHz. This is comparable to printing one page at 300 dpi. and 200 feet per minute. These measurements are analyzed to show the average charge output, and the distribution of the charge amplitude. Results are presented which show the effects of variations in the applied voltages around the normal printing conditions. Additional experiments give insight into the processes involved in printing from an AC discharge. The use of nitrogen as a working atmosphere for a print cartridge is explored.
Ink Jet is the only printing technology which is available in economically viable alternatives over the entire range of normal printing speeds. Each ink jet alternative has technical problems, most of which are common to the entire range of technical options. In this paper» an attempt is made to briefly describe the problems, the approaches which have been taken to solve them, and the disciplines required for the solution. It will be shown that the disciplines involved are very diverse indeed.
In thermal dye diffusion printing the head drive method influences the quality of the prints produced. Eastman Kodak Company's pulse count modulation head drive method better controls the heater temperature on the thermal heads, resulting in improved printing quality. In thermal printing, pulse count modulation produces continuous tone color images with good tone scale and high densities. The pulse count modulation head drive method was developed to reduce printing artifacts and produce the widest range of density, without distorting the plastic receiving layer, or producing printing group artifacts. Excellent continuous tone color prints of near photographic quality can be achieved with thermal dye diffusion printing.
Delphax type ionographic heads are one of the image writing bar devices used in nonimpact printers. One design issue is that an error of screen electrode alignment on ion generator may cause a significant variation of output current. In this study the relationship between alignment error and the output current is identified from the results of a multiple regression analysis on experimental data. In conclusion the magnitude of the effect of an alignment error on the output current is —1.1% per micrometer. Based on this value, a dimensional tolerance can be derived for the design and assembly of head parts according to required uniformity of output current. The secondary factor of output current variation is the difference between drive electrodes, which can be corrected by input voltage. The magnitude of the effect of screen aperture diameter variation is 0.32 % per micrometer, which is small enough to be negligible.
The pictures taken by the conventional Hi-Band SV camera, FUJIX ES-30 TW, and by the digital SV camera which stores pictures digitally in a solid-state memory card, FUJIX DS-X, both introduced into the market in December, 1989 in Japan, will be shown on the TV display and video prints. The quality of both seems to be good for close-up shots but not so good for distant shots.
Then, rather than looking at the video color prints, the near term challenge is to integrate electronic image with Audio Visual systems. We can enjoy our photos on a TV screen with Audio, and select audio sources based on CD from classic, easy listening, etc. Audio helps to visualize just one photo with various emotional responses by changing audio sources. Audio Visualized Entertainment of Electronic Photography is more than just a change in our still-photographic experience (demonstration).
Moreover, we can understand our electronic still-photographs in knowledge-base by looking at their explanation on a display monitor in PC-based multimedia presentation.
Magnetography emerged in the late 1980s as one of the most reliable, high-speed non-impact printing technologies available. It was developed by Bull after a ten- year research and development effort. This presentation describes its development path, from its magneto-electric roots in the mid-1800s to present-day machines that are capable of printing well over one hundred pages per minute.
The major topics covered will be: the anatomy of a high-speed magnetographic printer, with reference to the mechanics of the printing process; applications and the market potential for the technology; and market trends for the 1990s.