Equivalent circuits and efficacy of single-layer ACPEL devices

Abstract

A series resistance - capacitance equivalent circuit has been used to describe a single layer AC Powder Electroluminescence (ACPEL) lamp in operation. The two crucial components of this practical equivalent circuit are frequency and voltage dependent and have been independently determined for a single layer ACPEL device over a range of 50-800 Hz and 10-150V. The organic binder containing a ferroelectric component is mainly responsible for determining the capacitive element since it acts in series with a larger capacitative contribution mainly from the phosphor. The series resistive element will be determined by mainly the phosphor particles, and the remarkable changes in the effective series resistance and capacitance of the lamp structure are shown to be brought about by the activation of the ZnS phosphor. The effective resistance is consistent with a model where conductivity is governed by the average charge recombination time under given internal field and frequency conditions. Using the effective resistance and capacitance values of our equivalent circuit, the average rate of energy dissipation can be easily calculated as a function of applied voltage and frequency. For sinusoidal waveforms, first indications are that efficacy will be optimized at low voltages, but only weakly dependent on frequency. © The Author(s) 2014.