The charging characteristics of photoconductors that were electrostatically fatigued(repeated charge and photodischarge)and subjected to surface abrasion(cleaning blade wear)have been characterized by an electrophotographic incremental charging technique. This technique revealed differences in the photoconductor charging profile as the surface is incrementally charged up to its final surface potential. Samples that were charged and photodischarged but not subject to surface abrasion during extended printing showed hole injection from the surface and a reduced image density in half-tone images. The abrasive removal of damaged Charge Transport Layer surface layers restored the quality of the half-tone images. The half-tone image quality was not as severely reduced for the charge only sample(ionized gas charges but no accumulation of sub-surface trapped charges). The characteristic of these three sample regions changed with the extent of OPC fatigue. This methodology provides a means of characterizing and understanding the behavior of fatigued photoconductors.
Organic photoreceptors (OPC) are organic-chemical-based photoelectric transducers. For optimum performance in an electrophotographic (EP) process, the OPC dark and photoelectrical characteristics must be stable. Exposure of the device to ultraviolet light (UV) may cause undesirable performance changes (fatigue) as a function of EP cycling. We have previously shown that for OPCs formulated with triarylamine-based charge transport materials (CTM), the CTMs undergo photochemical reactions that cause the observed UV fatigue. The addition of specific electron-deficient acceptors to the charge transport layer (CTL) formulation can substantially reduce or eliminate UV fatigue. Based on analysis of the photophysics of acceptor-doped CTL systems, we propose a mechanism for UV fatigue reduction that invokes energy transfer from the excited singlet state of the CTM to donor-acceptor charge-transfer sites in the CTM-polymer binder coating. Using the photophysics as a guide, several classes of chemicals, both monomeric and polymeric, have been identified and shown to be effective in reducing UV photofatigue in OPCs.
In this research, we proposed new evaluation method for display color reproduction ability. It considers the numbers of distinguishable colors based on luminance and chromatic Just Noticeable Difference(JND). When unit cell for distinguishable colors was defined, we verified luminance and chromaticity JND using the latest TV sets. Then we clarified that the numbers of distinguishable colors was influenced by contrast ratio, maximum luminance and color gamut. The number of distinguishable colors of the display designed contrast ratio 3000 : 1, maximum luminance 450cd/m2, BT. 709 color gamut were 65000 colors at 40cd/m2 and 32.71 million colors in total. And it was possible to evaluate display color reproduction ability our proposal method using distinguishable colors. Finally, we evaluated the influence of gamma and bit depth using our proposal method. Then we clarified that the display which designed gamma 2.2, 3000 : 1, 450cd/m2, BT. 709 color gamut were needed 12bit for color reproduction in visually high density.
There are several synthetic methods to produce functional polymer particles which can have diversified functionalities by controlling size diameter and distribution range, figure, and surface condition. The particles has played an active part in application to light-diffuser plate and sheet for LCD, and to external additive for toner. Recently, a new synthetic method is developed using Micro-Channel that enables to produce bichromal mono-dispersed micro particles. The bichromal particles are used in PLD(paper like display)with rotating ball system that has been expected as an emerging application area.
The external additive is one of the key materials to design the toner formulation. An inorganic fine particle is generally used as an external additive. Production process, character of inorganic fine particle and technical trend are described in this article.
In recent years, with the spread of color toner, titanium dioxide surface-treated with organic compounds is being used for a toner additive as well as silica. The titanium dioxide shows several effects such as tribo-electric charge control, improvement of environmental stability and flowability of the toner. In this study, physical properties of titanium dioxide are shown related to surface-treating materials and particle diameters.
In recent years, highly concentrated inks of gold and silver nanoparticles have been successfully produced by using a special type of protective polymer and a mild reductant. Metal nanoparticles posses unique properties that they do not exhibit in their bulk states. One of properties of metal nanoparticles is a lowering of melting point. Metal nanoparticles are useful as conductive materials with heat treatment at low temperature. Ag and Pd nanoparticles are useful as catalyst of electoless plating. In this article, preperation of Metal nanoparticles and thei application to conductive circuit pattern formation with ink jet printing and/or electoroless plating are described.