Photogeneration efficiencies have been measured in dual-layer aggregate photoreceptors over a wide range of fields and wavelengths.The efficiencies are strongly dependent on the field and donor concentration of the transport layer and are independent of wavelength. The interpretation of the experimental results leads to the conclusion that hole photogeneration occurs in the following manner: (1) photon absorption and the creation of a mobile exciton in the dye-aggregate phase, (2) diffusion of the exciton to the interface between the dye-aggregate phase and the transport layer, and (3) dissociation of the exciton into a free electron and a free hole. The results are described by a model based on a theory of geminate recombination, originally due to Onsager. The key parameters of the model are the quantum yield of exciton formation and the exciton electron–hole separation distance. For aggregate photoreceptors, the exciton yield is 0.60. The separation distances are between 20 and 60 Å, and increasing with increasing concentration of the donor component of the transportlayer.

Chatter vibration of a cleaner blade charged by a contact charger roller was mathematically investigated. From the results of the investigation, the following points were deduced: (1) The chatter vibration is basically induced by nonlinear negative damping due to negative speed dependence of the friction coefficient between the cleaner blade and a photoreceptor drum. Parametric excitation and forced vibration are also generated by the photoreceptor vibration induced by the alternating electrostatic force of the charger roller. (2) Calculated results based on the present model qualitatively agreed with experimental observations, and several methods to suppress the chatter vibration were proposed.

A new printing process called ELPHI (ELectroPHoretic Imaging) is presented. An electronic print plate with an electrode for each pixel of the final image generates an electric field. Charged dye particles of a liquid toner suspension migrate under the influence of the electric field and deposit on the pixel electrodes. The gray scale of each pixel is controlled by the applied voltage and by the time during which the voltage is applied. After development the toner image is transferred to paper. A comparison of the ELPHI process with common imaging technologies shows the advantages of the new approach. An experimental printing setup that is described is used for measuring the process characteristics. The electronic control of the process allows for correction of the nonlinear characteristics. Printing samples of two different electrode test structures are presented to demonstrate the potential of the ELPHI process for the printing of high-quality gray-scale images.

Resolution and tone reproduction characteristics of all hardcopy images on paper are significantly influenced by the way light scatters in the paper. However, little has been published on experimental techniques for measuring light scattering and resolution characteristics of paper. Three experimental techniques are discussed in the current work. The first is a direct measure of paper MTF by microdensitometric scans of illuminated edges projected onto the paper. This technique is tedious and of intrinsically low precision. The second technique is based on Kubelka-Munk theory and derives MTF behavior from the Kubelka-Munk equations and experimental measurements of paper reflectance. This technique has the advantage of relating paper MTF to the fundamental metrics of light scattering and light absorption.However, the accuracy of the technique is questionable due to the assumptions intrinsic to Kubelka-Munk theory. The third technique involves modeling the Yule-Nielsen effect of optical dot gain and fitting the model to experimental data. The data are generated by image analysis of idealized halftone patterns formed by placing high-resolution halftone line screens in close mechanical contact with the paper under analysis. This technique is shown to provide estimates of paper MTF with significantly higher precision than traditional microdensitometry scans of illuminated edges. Experimental data are collected for a wide variety of hardcopy substrates, and the results are used to examine some of the assumptions inherent in applying Kubelka-Munk theory to papers.

A new method for high speed drying of wet ink on media, essential for the operation of a high-speed full-color ink-jet printer, is proposed and studied experimentally. Immediately prior to jetting of ink drops, a medium is heated to a very dry condition by bringing it into contact with a moving-belt-type preheater. Experimental results show a clear print quality with low feathering, for such paper as plain paper for laser printers and recycled paper. Also, features such as high-speed drying, short warmup times, low power consumption, compactness, and safety, all inherent in the proposed drying method, are confirmed.

A novel system has been developed to improve the quality of video printing. The fully automatic improvement is based on a model of image degradation in the video coding and recording process. The scheme consists of six methods: temporal filtering of subcarrier residuals, smoothing of horizontal color noise, reducing vertical incorrect colorings, sharpening color transitions along horizontal lines, increasing color saturation, and compensating the gamma correction in the camera. The printed results show significant improvements in the image quality. The quality achieved is sufficient to enable video printing of cost-critical low-end products. The system is in use in a Finnish repro and printing house. Although the methods were developed for S-video, they can be modified to work with normal composite video.

3-D color stereophotolithography is based on the classic laser stereophoto-lithography technique, but it needs several reactors containing colored resins instead of just one containing a commercial resin. By moving the incident laser beam in each reactor for each color, one can create color parts of very fine quality. This could be applied to the manufacture of 3-D color objects conceived in the computer-aided design process. This new technique should be very attractive in fine arts, architecture, etc.

Six bisazidovinyl compounds (AVs) were synthesized for application to photosensitive materials. AVs easily yielded bifunctional 2H-azirine (AZ) in a thin polymer film of poly(1,2-butadiene (PB) or poly(4-hydroxystyrene) (POHSt) by heat treatment. By photoirradiation of those films, AZ yielded nitrile ylide (NY). The crosslinking reaction of the polymers proceeded through a 1,3-dipolar addition of NY with vinyl group (PB) and an addition with alcohol (POHSt). These reactions were confirmed by absorption and infrared spectra. The irradiated polymer films were insoluble in chloroform. The most sensitive AV compound is 2,7-bis(1-azidoethenyl)-dibenzothiophene, which can reproduce line-and-space patterns at 1.2 mJ cm⁻² (PB thin film with 254 nm photoirradiation).