A series of arylamine derivatives consisting of only N-phenyl units, which can be taken as a structural minimum unit for hole carrier, was synthesized and their hole drift mobilities in the polymer dispersions were inter related with their chemical structures. As a result, the validity of the previously proposed guiding concept for developing better charge transporting organic materials [Electrophotography, 25, 16(1985)] was demonstrated and furthermore the dependence of the mobility on the chemical structure was newly found relating to the substitution site of N-phenyl group on benzene ring. The dependence was interpreted by the more concrete concept of poly-functionality and intramolecular-mobility based on the molecular orbital calculations. Among the compounds investigated a new arylamine derivative, N, N, N', N'-tetrakis (3-methylphenyl)-m-phenylenediamine (m-PDA), was nominated for high hole mobility compounds.

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Polymorphism on oxotitanium phthalocyanines (TiOPcs) and their xerographic application as charge generation materials for multi-layered photoreceptors has been investigated. It was found that TiOPc has five typical polymorphs, i.e., amorphous, α, β, γ, and m-forms. Their differences can be seen evidently in X-ray powder diffraction patterns, infrared and optical absorption spectra and electron spin resonance ones. Crystals of copper phthalocyanine (CuPc) and TiOPc grown from solvents in solvent were observed with a scanning electron microscope, and their crystals were found to be hexagonal and pyramida1, respectively.
The photoreceptors using these TiOPc as charge generation materials showed high electrophotographic properties at near-infrared region. The order of photosensitivity was γ ≥ amorphous > m > α > β. Especially, a photoreceptor of γ-TiOPc/butadiene derivative exhibited excellent performance; the dark decay = 54 V/sec, E_1/2 = 1.8 erg/cm², a surface voltage with irradiations of 5 erg/cm² = -35 V, 10 erg/cm²= - 30 V and 30 erg/cm² = - 25 V at 790 nm.

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The dye transfer ink sheets have been made of one of cyan dyes with the low melting point and poly(vinyl alcohol) (PVA) binder, and confirmed to be used for G2 facsimile machines. Although authors tested the ink sheets of both magenta and yellow dyes possessing as same melting points as cyan respectively, these sheets showed the very low dynamic sensitivities. We investigated the causes of their low sensitivities. We investigated the causes of their low sensitivities, and make it clear that they are due to the interaction between dye molecules and PVA binder. When poly(vinyl pirrolidon) (PVP), which does not interact with these dyes, was used as their binder and glycerin as its plasticizer, we can obtain the dye transfer sheet which can be used for G2 facsimile from the view of sensitivity.

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As one of the mechanical properties of magnetic brush, we measured distribution of pressure perpendicular to drum surface in the developing area.
In case of ferrite developer, this force which magnetic brush presses drum surface is maximum about 3 - 10 gf/cm² in the developing area.
This force depends not only on the characteristics of the carriers but also on the developer density, which can change depending on the feeding rate of the developer into the developing area and also on the change of drum developing roller distance in the different position of the developing area.

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Brushing force of magnetic brush which works tangential to drum surface has been measured.
In case of ferrite developer, this force of magnetic brush, which rubs photoconductor surface is about 20 - 30 gf per total development area of the magnetic brush.
This force depends on the density of developer and the dynamic magnetic property of the carrier.
Evaluation of this brushing force provides very useful information for the improvement of copy quality.

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Japan Hardcopy '90 has been held at Nohkyo Hall in Tokyo on June 20-22,1990 by the Society of Electrophotograply of Japan. There were 700 participant and 68 popers (including 6 ouerneas papers) were presented.
Up-te-date non-impaot priting technologies on elcctrophotograply, thermal, inkjet, image processing and so on have been eagerly discussed.

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