TbCo longitudinal recording films for thermomagnetic printing were deposited by RF sputtering.
The multilayered TbCo films deposited in the magnetic field showed longitudinal anisotropy with the coercive force of 43kA/m and the saturation magnetization of 0.25 T. The absorption of sufficient volume of the magnetic toners onto the recorded latent image was confirmed.
Using the underlayer of the multilayered TbCo film which have an uniaxial anisotropy orthogonal to that of the recording layer of the multilayered TbCo film, the size of zigzag wall formed at the transition region became small and high recording density such as 600DPI was obtained.

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We studied dot formation process of water based ink on inkjet paper. Experimental investigation shows that an ink droplet spreads on paper in several microseconds and penetrates into paper in several miliseconds.
We propose penetration model including void fraction of coated layer, ink fill up ability, ink spreading on paper surface by wetting, and ink penetration velocity. On the basis of the model, computer simulation program has been developed. The simulator can predict dot diameter on coated paper in 10 % error range.

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The xerographic toner transfer efficiency using a corona charger decreases in value under high humidity environments,and toner image quality deteriorates. However, a highly-stable color laser printer has been developed by using a new toner transfer roller, which is made of elastic sponge rubber sheathed by a resistive/conductive double-layer resin sheet. The new roller with a 4.2×10⁹ ∼ 8.5×10¹⁰ Ω·cm resistive layer of 120 μm thickness makes it possible to obtain high efficiency (more than 85%) and good toner image quality even in high humidity conditions (85% RH).
This developed color printer attains the following features under broader operating conditions: First,the toner transfer efficiency is attained above 85%. Second, printed image color differences are within 2.0 from 20°C, 60%RH to 35°C, 85%RH. Third, high-quality full color images can be printed in these conditions.

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The dependence of triboelectric charging characteristics of two-component developers on toner concentration is well known by our proposed new mode. We verify the proposed model of earlier works by using the several toner and carrier. The influence of charging site number on carrier surface by coating materials to toner charge is experimentally investigated. We examine the dependence of triboelectric charging characteristics of two-component developers on toner concentration by carrier surface's modification and get the results to fit the proposed model of toner triboelectric charging. The influence of coating materials on carrier surface to toner charge has been studied by the measurement of dependence of toner q/m on toner concentration.
The results of uncoated ferrite carrier are described as Type I characteristics (constant tribo-charge with toner concentration) and uncoated iron carrier are Type II characteristics (decreasing tribocharge with toner concentration). In the case of silicone coated carrier, according to the silicone materials, the triboelectric charging characteristics changed from Type I characteristics to Type II characteristics and still remained Type I characteristics. In the case of fluorine coated carrier, the triboelectric charging characteristics changed from Type I characteristics to Type III characteristics. In the cases of coated carriers, they exhibited all Types (Type I, Type II and Type III characteristics).

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The influence of external additives materials to charging site number on toner surface has been experimentally investigated. The variation of external additives materials on toner surface and toner concentration have been examined by blow-off method. There is a strong correlation of the toner triboelectric charge and its toner concentration dependence with the silica content on the toner surface. It means that the silica charging site is contributed to toner triboelectric charging characteristics. It is found that a independent relationship between the triboelectric charging characteristics of toner and silica is indicated.

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In this journal (Vol. 36(4), 260 (1997)), we proposed a tribocharging model that the charging process was an equilibrium of transfer of charge between the toner and the carrier, where the opposite result to Takahashi et al. was obtained. To our result, Takahashi et al. reported the contradiction that our solving-process of the equation was full of mistakes in this louma1 (Vol. 37(1), 74. We, therefore, show our model and equation correct in further discussion and correction of the model. Concurrently, we point out some problems in their model and equation.

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