Electrophoretic particles were fabricated by modifying inorganic pigment surface with highly hydrophilic polymer shell. Firstly, silane coupling agents were used to modify inorganic pigment surface, and then monomers which have more than eight carbon atoms were used to form polymer coating shell on particles by radical graft polymerization. Silane coupling agent provides pigment with charge, and polymer shell prevents the pigment from flocculating in electrophoretic solvent by steric hindrance. Spatial distribution of electrophoretic TiO2 particles under the reciprocation motion between two electrodes was observed by using an optical microscope. The drift mobility and zeta potential of electrophoretic particles were calculated by the observation.
The sharpness of image is one of the important factors in image quality. In most imaging systems, the edge enhancement process is applied to improve the sharpness of the image. In this paper, the dependence of the optimum condition of edge enhancement is studied on the pixel size and the luminance distribution of image by subjective estimation. It is found that the optimum condition shifts to weak edge enhancement side according to the increase of pixel size and the reason of the shift is explained from human visual system, and it is also found that the optimum condition shows the same behavior as above according to the increase of luminance variance.
The trickle development method in two-component development system of electrophotography is described. This method was invented for reducing maintenance costs reduction. It has been applied to many electrophotographic commercial products of Fuji Xerox, starting by Color Laser Wind 3310. The reason why this method has been used widely in Fuji Xerox is considered that it provides great effects on the developer life with a simple configuration. In this method, steady charging level of developer is obtained by discharging of excess developer and at the same time an amount of carrier beads is provided in a “trickle” with dispensing toner. Mechanism of discharging excess developer has to be designed appropriately considering various restrictions required to make compact development unit. This report introduces typical discharging systems of excess developer, model of developer charging and concept of developer charge maintainability together with some examples.
In the Toner Projection Development(TPD), images are formed, in a non-contacting manner, by mono-component magnetic toner particles which are electrically charged and are transferred to latent images by the effect of alternating electric field. The TPD has been one of the key technologies in our black and white electrophotographic products, such as process cartridges, because of its simple configuration and its stability. Recently electrophotography has been required to be applicable to color and high speed POD products. In this paper, our recent activities on the improvement of the TPD will be explained, firstly from the viewpoint of both materials and hardware, with the results of visualization and simulation. Finally our recent activities on color and POD products will be explained. The TPD is expected to progress as our key technology because of its simple configuration.
This paper describes brief overview about two-component non-contact development method. In two-component non-contact development, AC voltage is superimposed on DC bias, so as to let only toner fly to photoconductor. Optimum design of developing condition is required for two-component non-contact development to prevent any defects such as background stain and carrier deposition. Another application of two-component non-contact development with a control electrode is introduced as one of solutions that achieves higher development efficiency by lower AC bias voltage applied. Further, two examples are introduced as the application of regulation method for thin layer formation which is essential technique of two-component non-contact development.
Touchdown developing is relatively an old developing system which originates from mono component developing technology. This system is also called a hybrid developing system because it adds carrier powder to charge toner particles as a dual component developing system. Recently, the touchdown developing system is getting popular for color printers, MFP and production printers because of its high image quality and long life performance. This paper describes historical background and commercialized technique of this developing system.
The liquid development technology has the potential ability to produce the images of offset printing quality in the electrophotographic technology, and this excellent potentiality is admitted widely. Moreover, some experimental models based on the liquid development method had been proposed and there have been considerable researches so far. However, there is only a limited product of liquid toner process in a commercial printing industry, despite the remarkable breakthrough of the dry toner electrophotographic system as the POD (Print On Demand) technology. In this thesis, look back on the transition of the liquid development technology and clarify the technical issue to be studied.
Super-high speed continuous feed B/W laser printers have been used for printing a large number of documents, accounts or statements in public offices. Generally, these jobs must be done in a limited time, then they are required for very high printing speed, durability and reliability. In addition to the performances described above, it is necessary to improve print qualities for monochrome printers in recent years. They have been adopted to direct mail and book markets, etc. The markets require halftone uniformity in photographs and line width stability1∼3). In this report, an overview of Developing system for Super-high speed continuous feed B/W laser printers is described. Especially performances of developing system with multi developing rollers, and developer mixing, toner feed and toner concentration sensing systems are described.
Toner development with conductive toner in electrophotography has been considered as an alternative to the most widely used dual-component toner development process. While in the latter case insulative toner particles are charged using tribo-electrification, this is not required for conductive toner where toner particles will be inductively charged when subjected to an image wise applied electrical field. Incorporating magnetic pigment in conductive toner particles allows for monocomponent development systems. This paper describes theory, key characteristics, advantages and challenges of conductive toner development with monocomponent magnetic toner. It will also describe the application in Océ printing systems.