Statics of Pin Electrode in Pin-to-Plate Discharge System.

Abstract

The electrostatic force acting on a pin electrode in a pin-to-plate corona discharge system was measured and numerically calculated by a static unipolar model. The model neglects the effects of diffusion and convection of charged particles. It is assumed that generation of ions takes place on a tip of the pin electrode and that surface electric field is less than the onset field of corona discharge. Numerical calculation, s were conducted using an iterative finite element method. Calculated voltage-current characteristics of the positive corona qualitatively agreed with the measured result that the corona discharge took place over a threshold voltage and the current was in the order of several ten microamperes. Trichel pulse was observed in case of negative corona and the negative corona current was large compared to the positive corona. Vertical electrostatic force was also measured and calculated. Although extremely small electrostatic pull force was induced if discharge did not take place, the force became repulsive and relatively large when the corona discharge took place. Force in negative corona was almost same with that in positive corona. Calculated force without discharge agreed with the measured but the calculation did not simulate repulsive characteristics at corona discharging. Convection of air must be included in the model. Effect of lean of the pin electrode has been also investigated. The present investigation is expected not only to realize a new ozone-free charger but also to clarify quantitative mechanisms of the bead carry-out in the magnetic brush development subsystem of electrophotography.