Measurement of Photoinduced Discharge Currents and Voltages

An apparatus has been developed for monitoring the instantaneous surface potential of photoconductive insulators during illumination. In addition, instrumentation methods have been evolved for measuring the effective photoinduced discharge current, transit time, and mobility of charge carriers in such materials. The device has proved useful and convenient for qualitative evaluation of the photoinduced discharge characteristics of electrophotographic paper and plate materials under dynamic conditions. It also provides means for precise quantitative measurement for theoretical study of the photoconductive properties of such media. Circuit analysis and theory of operation of the apparatus are described. Discussions are given on the accuracy and usefulness of the techniques presented for monitoring the effective photoinduced discharge current to yield insight into the electrical and optical properties of photoconductive insulators. Test data are shown and discussed.