A design method of transfer condition for electrophotographic printing on a booklet has been developed. There are three main problems in developing a printing system for a electrophotographic booklet printer; the design of the transfer potential for printing, consideration of effect of transfer pressure and dirtiness of pages. Whereas the conventional method can calculate the electric charge for printing on single paper, our new method was found experimentally to be able to calculate a necessary and sufficient voltage for electrophotographic printing on a booklet. And transfer pressure was found to be related to transfer potential. Since the main material that disturbs electrophotographic printing was found to be oleic acid, a cleaning roller made of butadiene rubber with oil-absorbing resin was developed.

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In order to evaluate the possibilities for realizing a new printing system, in this study, we have proposed a new numerical analysis method that forms a relationship between an electric field and a flow field that includes a free surface. This analysis method is applied to the flow field of a water-based ink layer that has a free surface, which is greatly deformed by the actions of electrostatic force. Fundamental experiment was also conducted to judge the validity of the numerical analysis method. The following conclusions can be drawn from the results of this study. (1) Ink was deformed and transported to the paper by electrostatic force both in the numerical analysis and the experiment. (2) The effects of the initial shape of the free surface on the characteristic of ink transportation can be predicted only by the numerical analysis. (2) The effects of viscosity and surface tension of ink on the characteristic of ink transportation can be predicted. (4) These experiments indicated no clear effects of applied voltage on the ink transport time, but the numerical analysis indicated an effect that was considered pertinent. (5) It was clarified that it was possible to control ink transport time by adjusting ink viscosity, ink surface tension, externally applied voltage and the shape of the initial ink surface.

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The movement of conductive toner in a rewritable reflection-type display cell, in which conductive toners and white particles are enclosed, was investigated. The conductive toners in the display cell moved at low threshold voltage in the absence of white particles, and the reflection density reached saturation at 200V. The coverage of the conductive toners on the electrode surface, covering power, was ca. 50% above the saturation. On the other hand, the reflection density showed saturation, ca. 26%, at the voltage of 300V or above in the presence of the white particles. These results indicates an increase in the threshold voltage for the toner movement by the addition of the white particles. Further investigations in this study revealed that a particle-free space of ca. 50% is required for the movement of the conductive toner particles in the display cell.

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The response time of a toner display with charged conductive toners has been investigated. The display consists of the conductive toners and white particles which are inserted between two substrate electrodes. Its indication of images are based on absorption and scattering of ambient light at the image and the non-image area, respectively. The response time of the display to applied voltages was measured using a photon counting method. The response time for switching from black to white display was 1.1 ms at an applied voltage of 500V, and the reverse process took 1.0ms. The response time depended on the amount of the particles enclosed in the display cell. From the observation of particle distribution in the toner display cell, it has been confirmed that the positively charged black toners and negatively charged white particles adhered to the separate electrode surfaces and air gap was formed between the two electrodes. These results agreed with the concept that the cell displays black when the negatively charged white particles are replaced by the positively charged black toners under an application of negative bias voltages or vice versa.

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