The influence of toner and carrier particle size on toner tribocharge has been studied by the measurement of dependence of toner q/m on toner concentration. The q/m of ferrite carrier (100 μm) and P1 toner (8.1 μm) developer is decreased with increasing toner concentration (Type II). However, the q/m of ferrite carrier (65 μm) and P1 toner (8.1 μm) developer is without dependence on toner concentration (Type I). The q/m of P2 toner (10.5 μm) and P3 toner (12.3 μm) for ferrite carrier (65 μm, 100 μm) shows always no dependence on toner concentration and constant value (Type I). In the case of iron carrier (100 μm), the q/m of P1, P2 and P3 toner are always decreased with increasing toner concentration (Type II). It was shown that a reason to change from Type II to Type I (from 100 μm carrier —P1 toner pair to 65 μm carrier— P1 toner pair) could be explained in some of number of toner particles that it sticks to one carrier particle. In other words, because there are many attached toner particles on 100 μm carrier, it becomes Nc < Nt, and because there are a little attached toner particles on 65 μm carrier, it becomes Nc > Nt, and toner concentration dependence of q/m is different each other. The dependence of triboelectric charging characteristics on toner concentration is governed by the relative difference of number of charging sites between toners and carriers. The relative difference of toner and carrier effective charging sites is very useful concept for the analysis of microscopic behaviour of two component systems.
In the color laser printer with an intermediate transfer medium, four color toner images on an OPC are transferred successively to overlap one another on the intermediate transfer medium. And a complete color image which was formed by four toner images on the intermediate transfer medium is transferred to a sheet of paper at one time. Using two transfer processes, it is important that each transfer process should be highly efficient. Then, 1 st and 2 nd transfer processes on the intermediate transfer system have been investigated. Potential distribution in the transfer region changes on the time period of the transfer process, because the intermediate transfer medium has electric semi-conductive resistance. A simulation model and a method for calculating the time variation of potential distribution are proposed. Transfer efficiencies which were estimated by this proposed model were in conformity with the experimental results. The simulation results show that the time constants of the intermediate transfer medium layer and the paper layer are important parameter on the transfer processes. In addition, it has been clarified that the transferable maximum toner mass is affected by the multiple value of toner charge and toner mass.
We have investigated layered photoreceptors consisting of fluorenone bisazo pigment (Azo-FO) and poly (methylphenyl silane) (PMPS) to enhance the photosensitivity and photoresponse. Although it is known that layered photoreceptors consisting of an azo pigment carrier generation layer (CGL) and PMPS carrier transport layer (CTL) do not exhibit high photosensitivity compared with layered photoreceptors with a molecularly-doped-polymer (MDP)-based CTL, we examined layered photoreceptors with regard to the number of photocarrier generation sites. From the results of analyses using TEM micrograph and photoluminescence quenching, the number of photocarrier generation sites was proved to be insufficient for high photosensitivity. Based on these results photoreceptors consisting of PMPS doped Azo-FO CGL and PMPS CTL were prepared for increasing the amount of contact between the carrier generation material and the carrier transport material (CTM). As a result, the photosensitivity of the layered photoreceptor was observed to be as high as that with a low-molecular-weight CTM doped Azo-FO CGL or PMPS CTL, or that with a MDP-based CTL. The photoresponse was compared by the xerographic discharge technique in combination with xenon microsecond exposure. PMPS photoreceptor with PMPS doped CGL showed faster photoresponse than MDP-based photoreceptor, even exceeding those PMPS photoreceptors containing low-molecular-weight CTM doped CGL or CTL.
The setting position of equivalent air layers inevitably caused by air existing in fusing region and having remarkable thermal resistance are studied for precise estimation of temperature field. Five layer setting models for numerical estimation are proposed and the estimated toner surface temperature is compared with the evaluations from the measured one at the nip outlet based on the similarity law of temperature field. It is clarified that the estimated temperature shows a good agreement with measured ones with the following models: 1) The air layer based on paper surface roughness is positioned between toner-roller interface and that based on the voids between toner particles is in the midst of toner layer. 2) The air layer based on paper surface roughness is the same position with model 1) and the toner is treated as a porous layer including air. The other calculation is applied to two kinds of paper with different surface roughness and also offers good estimation. The results confirm the usefulness of the models for numerical estimation.