This paper describes a macroscopic analysis of forces acting on carrier iron powder in the adhesive process of the electrophotographic development by magnetic brush method. Applying the carrier iron powder model for magnetic brush development presented by R.M. Schaffert et al, on a macroscopic scale, the magnitude of forces acting on a carrier iron powder were computed from the physical circumstance produce by the developing magnet and the electrophotographic layer. Carrier iron powders adhering to image area were suggested to deposit on toners by the coulomb attractive force due to the electrostatic latent image.
Field problems on the magnet roll were generally solved and the results were applied to a cylindrical sleeve rotating around a magnet rod and conveying a magnetic carrier layer thereon. The magnetic pressure acting upon the magnetic carrier layer, the capacity of carrier conveyance on the sleeve and influences thereupon due to the friction of the sleeve surface were calculated. Further magnetic pressure acting upon toner particles between magnetic carrier particles is microscopically estimated. It is concluded that the magnetic pressure may sometimes be sufficient to crush toner particles between carrier particles, when the magnetic field is high. Roughening of the sleeve surface results in a weaker magnetic field than is usually used, in a remarkable improvement not only in the carrier conveyance capacity but also in prevention of the sleeve surface exposure which is caused near the magnetic poles by doctor scraping. Besides, by use of an apparatus freshly designed in order to measure the doctor blade resistance, conspicuos minima and maxima were found to occur a little in advance of the magnetic poles, say “P”, and of the middle points between adjacent magnetic poles, say “R”, respectively. These extremum values increase approximately in proportion to the 2nd power of the field intensity. Their distances from “P” and “R”, respectively, are approximately proportional to the doctor scrape depth, therefore the extremum points coincide with “P” and “R”, respectively, when the doctor scrape depthbecomes nil.
An empirical equation for the light decay curves of zinc-oxide electrophotographic (ZnO) layers is suggested. In the relatively wide range from the initial value to a value about one third of the initial value, the surface potential of the ZnO-resin layers seems to conform to the equation V = Vi exp(-α t2) where Vi: initial value of the surface potential, α positive constant. The authors use this equation to quantitatively determine the degree of reciprocity law failure and to determine an intrinsic value for the photosensitivity of ZnO-resin layers.
Measurements of the small signal impedance of photoconductive layers have been made both in the light and in the dark over the frequency rang 0.001 Hz to 10 kHz. The impedance in the rang 0.1 Hz to 10 kHz was measured with a a.c. bridge and for the frequencies lower than 0.1 Hz the measurements were achieved with the aid of Rissajious' figure method given by A.J. Baker and A.R.Piercy. The results were obtained as an equivalent parallel resistance Rp and a capacitance Cp of the photoconductive layer. Impedance loci were plotted using equivalent series resistance Rsand reactance Xs converted from above parallel components. The theory resulted in an equivalent circuit for a photoconductive layer and then each value of curcuit elements was determined empirically utilizing the parallel components or impedance loci descrived above. Theoretical considerations were given on the basis of the equivalent circuits for the internal states of photoconductive films.