We tried to clarify the mechanism of hopping charge transport in molecularly doped polymers (MDP's) by means of time-of-fight photoconductivity measurements and molecular orbital calculations. It was found that the magnitude of the hole drift mobility in binary solid solution MDP's is closely related to electronic properties of dopant molecules. Diagonal and off-diagonal disorders dominating the general feature of charge transport are mainly caused by the spatially in homogeneous distribution of charge on dopant molecules. With an increase in the drift mobility, the structural change between neutral and cation forms of a doped molecule, the polaron effect, as well as diorder control the hopping rate. The delocalization of charge in both neutral and cation forms determines the degree of disorder and is important for designing molecules having high mobility. Microscopic considerations based on molecular orbital calculations are growing need for the understanding of charge transport in MDP's.

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Development mechanisms have been examined for minute pattern of latent image potential distribution formed by intensity modulated laser scanning exposure. In DC bias development, highlight region of exposure is developed with more toner than calculation for the effective developing potential. A model based on the charge transport equilibrium mechanism for the electric field between a positive region of image potential on photoconductor to adjacent region of negaive image potential is proposed to explain that phenomena.
Development mechanisms in the condition of AC bias superimposition is also discussed to obtain linear development characteristics to the developing bias potential.

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For electro-photographic processing, scorotoron charger is frequently used, simply because uniform and stable electoric potentials of photoconductors can easily be obtained. This is due to the fact that grid wires can control photoconductor current. However, in this instance, electricity generated by corona current is mostly consumed by grid wires. In this system corona current must be increased and, as a result, a large amount of ozone is created with increased power consumption. Therefore, to use scorotoron charger, it is important that grid current be minimized without reducing the control effect of surface potentials. To this end, an attempt was made to analyze the effect of grid wire structures on charge characteristics of scorotoron charger, Shield- grid-, and photoconductor-currents were measured by varying grid pitches and gaps between the grid and the photoconductor. In addition, numerical calculations of electric fields were performed. Through these analyses, the effects of grid pitches and grid gaps on charge characteristics of scorotoron charger have been clarified.

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Utilizing our previously reported themo-chemical decomposition of titanylphthalocyanine (TiOPc) in TiOPc/organopolysilane layered films, we have succeeded in developing a novel direct laser writing-in xeroprinting master for dry multi-duplication system. Themo-chemical reaction of TiOPc with organopolysilane photoinduced as a result of photon-thermal energy conversion in TiOPc pigment converts semiconducting TiOPc layer to an insulating layer, which impedes charge injection from a metal substrate to an organopolysilane hole transport layer during corona charging and discriminates from the laser unirradiated portion in charge acceptance on the receptor to provide electrostatic latent image. Very fine line-patterns with 20 μm separation, drawn by a diode laser irradiation (830 nm, -1 μm in dia.), were successfully reproduced by development with small toner of 7 mu;m.

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It is shown that optimum combinations of JPEG compression ratio and pixel resolution exist that yield peak image quality. Five test images, identical in content but different in pixel resolution, are evaluated by subjective opinion tests. For a compressed file size of320kBytes,the optimum image quality (MOS > 4) is achieved when the pixel resolution is 1024 × 1280and the compression ratio is 1/16. For 80 kByte files, peak quality (MOS < 2) is achieved at 512 × 640 pixels and a 1/16 compression ratio. This effect is thought to be due to the combination of two factors: the nonlinearity of the JPEG coding scheme and the perception of image quality as a nonlinear function of pixel resolution.

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The purpose of this paper is to analyze re-transfer phenomenon of corona separation. We have tried to clarify some characteristics of this phenomenon in terms of energy-analysis, which was applied to the analysis on the mechanism of corona separation by the authors. Consequently we have found that the range of discharger conditions, on which corona separation is possible, could be divided into the maximum 3 regions on re-transfer phenomenon.
   1) The first is re-transfer region, on which this phenomenon is always generated to all image density.
   2) The second is neutral region, on which this phenomena is or not generated by image density.
   3) The third is non re-transfer region, on which this phenomenon is not generated to all image density.
As separation efficiency grows bigger, neutral region, re-transfer region and non re-transfer region appear in that order.
In order to verify these facts, we had an experiment with the laser printer and we could get good results which agree with the theoretical analysis roughly.

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A new melt-type thermal transfer printing system which uses focused laser beam instead of a thermal head is investigated. More particularly, using a high-power single-mode laser diode as the light source, a small and simple printing system can be developed. Owing to the high converging property of the laser beam, this system is able to print the high definition images.
This paper reports the analysis of the laser thermal-transfer printing process using the thermal transfer equation of thin film, and evaluation of printing density, energy, experimentally. As a result, we have confirmed that a minimum transfer line width 7.5 μm that corresponds with the resolution of 3,333 dpi,and printing energy about 1.27 J/cm². Favorable results were obtained by printing a standard l mm² sample character.

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We have investigated the melt-type laser induced thermal transfer printihg using high-power laser diode. We have previously reported some high-definition printing characteristics of this method.
In this paper, the analyses of the thermal response and printing dots using laser heat-mode processes are described. To analyze the thermal response in the laser thermal transfer processes, we have simulated the thermal properties in ink and base layer by 3-dimensional thermal analysis. For evaluation of dot-printing process, single laser pulse printing method is used.
As a result, we have confirmed that the thermal response in the region induced laser power can be shown with the anti-constant heat transfer function, and there is the reciprocity law failure in the laser heat-mode printing processes. On this printing, system, there has been found many important problems of the control of heat generation and transfer in ink sheet.

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This paper describes some technologies of thermal dye sublimation transfer to realize high quality printer, Trueprint2200.
(1) Mechanical technology realizing the feeding and position controling of ink films and receivers with the ease and the smallest floor area,
(2) Signal process of controling optimal heat energy of heating elements of thermal head and of having several correcting functions, and
(3) Color reproduced technology that emulates colors of the process print and monitor, which let you get the colors you want easily.

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