Electrophotographic processes using a dielectric layer bonded to a photoconductive layer as in the Katsuragawa process

With a photosensitive plate having a dielectric overcoating, an electrophotographic process available for repeated operation is developed. This process consists of three steps, utilizing the effect of photopolarization. An important feature is to allow the employment of higher photoconductive layers. As a result, high photosensitivity and high electrostatic contrast in electrophotography are achieved with this process. Factors determining the sensitivity are the rate of dark depolarization and light polarization and, in addition, the corona charging rate. This process may make possible applications in fields where only a slight exposure is allowed. What occurs in each step of this process is investigated analytically and experimentally.