A numerical method to analyze the potential distribution involved in the transport of charge due to the rotation of a resistive roller in the electrophotographic process is proposed. This method is based on the smoothed particle hydrodynamics (SPH) method, which is a particle method using a smoothing function often used in fluid analysis. The potential equation and the continuity equation are discretized with calculation-points instead of particles as in SPH. The validity of the method in the electrostatic and conductive analysis is confirmed using the model, strict solution of which is known. The transport of charge due to the rotation of a roller is performed by the movement of the calculation-points according to the rotation of a roller. Using the proposed method, the potential distribution on the surface of the rotating roller with a bias voltage is calculated for various peripheral velocities and resistivities, and the dependences of the potential distribution on the velocity and resistivity are obtained.

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Gamut Mapping Algorithm (GMA) is a key technology to meet the demand for a high-quality color reproduction across different media. So far a most typical application of GMA addressed to map a wide-gamut display image onto a narrow-gamut print image. We reported a narrow to wide “expansion” GMA is useful for an image taken under bad illumination or faded pictures. This paper proposes a versatile GMA with bi-directional function of “compression” or “expansion”. A proposed GMA uses a simple GBD (Gamut Boundary Descriptor) called r-image, a set of maximum radial vectors represented by a 2D gray scale image. The paper examines how to decide which should be applied, compression or expansion in reference to the each r-image of image and device and introduces gamut expansion results applied to the different devices.

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Multi-beam scanning is effective for high-speed and high-resolution optical scanning equipments in laser printers. A five-channel array laser diode with a wavelength of 635nm is developed.
In laser diodes with a wavelength of 635nm, the droop ratio tends to be large and the image uniformity to be degraded. To solve these problems, authors tried to optimize the threshold current and facet reflectance of laser array diode, and besides, improved the drive circuit, in which each laser diode is driven with a constant voltage part of a zener-diode.

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Gloss values of various electrophotographic prints and papers are obtained by employing Ray-tracing method based on measured three-dimensional shape. Cook-Torrance reflection model is used for the calculation of micro-reflection light. The comparison results between calculated gloss values and measured values are studied. In addition to the calculation of gloss values, “print” images which contain both gloss reflection and diffusion color are created by composing gloss images and scanned color images. The rendered “print” images show how those look like from arbitrary view points. And, the prototype of interactive “HANDHELD PRINT” display system is developed. The system can be used as a substitution of “electrophotographic prints with handheld”. By using the system, electrophotographic prints can be examined in various conditions, and compared with other print materials and other many display devices.

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Magnetic force acting on the toner from the magnetic latent image in the black image area and white image area in the magnetic printer was analyzed. Electromagnetic field simulator by finite element method and proximate equations were used for simulative calculation. Distance of 1/2 dot between the adjoining transition regions in the recording medium was allocated to form one dot black image and the distance of 3/2dots between the adjoining transition regions was allocated to form one dot white image. The following results were found. Toner is attracted strongly to the recording medium at the transition regions. Toner is attracted to the next toners each other at the intermediate region between the adjoining transition regions in the black image area. Toner bridge is formed at the black image area. On the contrary toners in the white image area get very weak attractive force and toner bridge is not formed. As a result it is considered that black image of 1dot and white image of 1dot are formed.

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In order to study the tribocharging mechanism of electrophotographic toner, particles of trianilinotriphenylmethane (TATPM) (positive type Charge Control Agent, CCA) were externally added at the interface between CCA-free model toner and carrier, and toner charge generated by agitation was investigated. The amount of generated positive charge q/m on the CCA-free model toner was larger than that on conventional pulverized toner in which almost all TATPM particles exist in the toner inner part. It was confirmed that the charging mechanism of the CCA-free model toner by the TATPM particles externally added at the interface between toner and carrier is as follows: a)during the toner-carrier mixing process, small size TATPM particles are produced and adhere onto the carrier particle surface, b) a charge exchange between the adhered TATPM particles and carrier particle surfaces occurs, and TATPM particles acquire positive charge, c)positively charged TATPM particles are transferred from the carrier particle surface to the toner particle surface,and finally the CCA-free model toner acquires positive charge. The amount of TATPM deposited on the carrier surface was determined by the absorption at 602nm with the TATPM/ethanol solution extracted from a carrier/ethanol dispersion. The relationship between the amount of TATPM on the carrier surface and the amount of positive charge on the toner is also discussed.

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The multi-alignment technique using an azimuthal anchoring control has been applied to form the polarized latent image in liquid crystal (LC) cells. The relationship between the twist angle and the anchoring energy is theoretically clarified using the torque balance equation in a twisted nematic (TN)LC cell. Experimentally, the azimuthal anchoring strength of the rubbed photo-crosslinkable polymer is increased by exposing the unpolarized UV light and the twist angle is changed from 0 to 90 degree by changing the UV exposure time in the TN LC cell. Moreover, when the LC cell is exposed with the UV light through a mask (a negative photo film), and is thermally developed, as well as the black and white photo-printing process, the twist angle continuously changes and the positive image appears in the LC cell between parallel polarizers. This multi-alignment technique makes it possible to form the latent image with a continuous grey levels and a high resolution more than 3000dpi.

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The imagio Neo C600series is a digital color, copier-based MFP while at the same time realizing superior image quality, productivity and product reliability in accordance with the performance level demanded by today's office environments.
The major features of this product include:
1. A 4-drum tandem engine and high-speed controller work in conjunction to provide high productivity.
2. A new type of fine-particle developer, new oil-less pulverized F/C toner and high-precision toner positioning system provide high image quality.
3. A newly developed non-contact hard roller drum-charging system, high-durability developer and OPC, and a process control system that uses an ID sensor located on the intermediate transfer belt provide more stable image quality and overall product performance.
4. A soft toner cartridge, which gradually deflates as toner is used for easy disposal, and paper trays capable of automatic size detection further improve product usability.
5. No materials prohibited by the RoHS Hazardous Substance Directive are used on this product, making it the first Ricoh product to do so.

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ApeosPort C 6550is the color MF machine that achieves compact size, high image quality and 50-ppm color productivity. The main technologies for high image quality are the VCSEL-ROS, the high-resolution digital screen, and the high-resolution digital pixel control. VCSEL-ROS realized 2400dpi exposure. Then, the main technologies for the high-productivity are the VCSEL-ROS, the new chemical process toner and the free belt nip fuser. This paper describes the technologies for high-image quality and the technologies for high-productivity.

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We developed the highest A4 full color printer in the world, and succeeded in the market access in 2004. This machine has many No.1 functions and qualities in the world and is placed as the flagship of Konicaminolta printers. We took the most advanced technologies in Konica Minolta including developing, transfer, fusing, optics, imaging and driving technologies. Our mission is to provide them for our users timely. We attained it in the magicolor 5400 series

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The electrophotographic full color Multi-Function Printer imageRUNNER C 6800,introduced into market by Canon in 2004,is equipped with an A-Si (Amorphous Silicon)drum. The concept of the MFP is “A color MFP to replace B/W MFPs in the office.”
To realize the concept, we selected an A-Si drum, which has many merits: high surface hardness, linear E-V characteristics, little degradation by charging or light exposure, and high permittivity. And as a developing system suitable for the A-Si drum, we, for the first time at Canon, combined magnetic monocomponent jumping development for black, with two-component development for Y, M and C (“Hybrid engine”). More specifically, the color development system features high resistive and low magnetized carrier particle and low compression to developing agent.

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Our company achieved high quality and a living long life by the tandem engine color printer which used a-Si photoconductor and LED head. Also, it confirmed relation between the layer composition and the latent image forming of the a-Si photoconductor from the both sides of the simulation and the experiment and it clarified relation between the depth of wear and the latent image forming of the a-SiC : H layer which is the most surface layer of the photoconductor.

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RISO has produced two-colour stencil duplicator RISOGRAPH MZ 770, which enables to print A3 paper at 150 pages per minute. This paper introduces its function balancing instant and easy-to-use features with high throughput, and describes the key technologies adopted in it.

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Océ Direct Imaging technology is a unique digital print process with 7colour dry toner. It is named after its way of image generation-directly generating image on imaging medium without generating latent image. Its most distinctive feature is colour consistency. Other two unique technologies, Océ Mono Component Toner Technology and Océ Colour Copy Press Technology, are indispensable to Océ Direct Imaging technology. I would like to shortly explain about them, too.

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