We have newly developed the electrostatic latent image measuring system equipped with the laser scanning optical unit. One of the features of this method is that the laser scanning optical unit is arranged outside the vacuum chamber. The vibration and the electromagnetic field interference of a polygon motor do not affect the orbit of the electron beam because the polygon motor is kept away from the electron optics system. A pair of laser diodes (LDs) is used as the light source of the laser scanning unit, enabling it to scan a maximum of two lines in the sub-scanning direction. Arbitrary latent image patterns can easily be formed by using the laser scanning unit. The laser scanning unit also includes a shutter, which shields against offset emission by the bias current of the LD. Measurement results were obtained as a new knowledge in relation to latent image characteristics for exposure conditions.
Among the bumping technology of LSI packaging, the technology using solder ball has excellent characteristics in electrical continuity between LSI and circuit board. It is necessary to array solder balls on the needed position of circuit board. In the previous technology of solder ball, patterned mask is needed and in order to manufacture the mask, cost and time is needed. New technology without mask is proposed on the base of electrophotography. The mounting process is as follows : desired light pattern is irradiated on photoreceptor drum and solder balls are attached to electrostatic latent image generated by the light irradiation and the balls are transferred to circuit board. The electrostatic image is generated in every solder ball pattern forming process, so without mask process becomes possible. In this paper, comparison of mounting technologies, proposal of new technology on the base of electrophotography, 60-100 μm diameter solder ball jumping condition, capturing the ball by latent image, and the applicability of above conditions to LSI bonding system are described.
An identification card (ID card) is one of the most important devices for physical security systems. Recently, spread of color printers and scanners has increased the risk of abusing ID card copies. Therefore, we have introduced an information embedding method on digital watermark using color difference for printing images. When the printing resolution is larger than 300 (dpi), it is hard to sense the color difference of two adjacent pixels for human eyesight. Using this characteristic, digital watermark can be embedded in the printing image as invisible fine color difference modulation. Additionally, we have developed a technique to apply this digital watermark to thermal transfer printing. Evaluations of invisibility and restoring show the good results. Further simulation experiment indicates that constructing sub image information by machine readable code is promising.
The improvement of image quality was formerly placed as one of the most important subject for study as well as raising photosensitivity in the development of silver halide photographic technology. Tone reproduction, granularity, sharpness, and color reproduction were studied notably among a great variety of factors affecting image quality at that time. The results obtained there can also be applied to today's digital imaging systems, where the details of the technology have been changed from the silver halide photography. The image quality will be kept to be an important subject for study from now on. A goal and a target of the study should be made clear, or the study will fall into an endless cycle. While evaluation of image quality is often carried out objectively on the basis of the data through some precision instruments, subjective evaluation by the impressions made through our eyes is needed in the final analysis. It is very important to take this matter into consideration when performing R & D.
The electrophotographic technology got over the conversion period such as digitization, colorization and high definition, by technical evolution aimed for the stabilization of the process as well as the innovation of the toner and the photoconductor, and it developed as the mainstream of the record technology in the office duties. Today the various print systems which made use of a strength of the electrophotographic technology are offered to the digital print market. However, the image quality of the electrophotography does not reach the image quality of the offset printing. By this report, about the high-resolution action in dry process two-component developing method I consider the action until the present and the directionality of future measures.
For better image quality of electrophotography, technologies which faithfully transfer toner images on an OPC or on an intermediate transfer member to transfer media, such as intermediate transfer members and papers, are demanded in the transfer process. Understanding the physics in the process, including various image degradation phenomena, is necessary for ensuring the fidelity, and therefore, fundamental technologies like visualization, measurement, and simulation play an important role in design and development for better image quality. For example, toner scatterings and non-uniformity of the image density, which are typical image degradation phenomena in the transfer process, have been investigated in detail by such fundamental technologies, and in recent printers, they are suppressed by design and development depending on the physics. In this article, some transfer technologies to suppress image degradations in practical use are reviewed, with studies on the image degradations by using fundamental technologies. And as a topic, Ricoh AC Transfer Technology, which realizes uniform images even on heavily textured papers, is introduced, and technology trends in the field of transfer process are discussed.
Fusing is the final process of xerography process and the image quality is determined by fusing finally. Fusing process has developed from mono fusing to color fusing. And the functions of fusing process has changed not only fixing on paper but also to get the aiming toner image structure. To get high image quality, the most important point is to control the toner rheology in fusing process. Many competitors have developed their original fusing concept and introduced into their production printers. The aims of their fusing concept are to get uniform and stable image gloss, high productivity, media free and high reliability. Technical innovation of fusing will be born with the xerography process revolution. Technology of solidification in fusing nip is one of the promising technology in future.
Technology of electrophotography has been developed with the aim of high quality-image in its history. The improvement of this technology has been remarkable during the past 75 years since its principal was invented. On the other hand, there are a lot of requests to toner because it is related closely with many process in electrophotography such as development, transfer, fixing, cleaning, etc., Here, we look back on how we have worked to enhance image quality from the perspective of toner transition. Further, in considering the high quality-image, in addition to the “improvement of the resolution” and “suppression of noise” as a basic performance, I want to spread perspective on added value of “expansion of the color gamut” and “control of texture”.
We have been developing various types of electrophotographic papers in order to respond to a wide range of necessities of the digital printer user. For example, we can propose “Mitsubishi EP-L Series” approved by HP Indigo, which are suitable for wet toner without requiring primer treatment before printing. The primer treatment is performed to stabilize the print quality by coating specific chemicals composed of highly reactive polymer on the surface of paper. However, the primer treatment is not effective because of cost increase and aged deterioration of paper quality, etc. As for “Mitsubishi EP-L Series”, we have improved the interaction between wet toner and paper not by using chemicals similar to the primer treatment but by controlling surface quality of paper. We report a summary of the development trends of electrophotographic papers suitable for wet toner or dry toner. Moreover, we introduce properties to affect the print quality.