Image Number 5 for United States Patent #4647184.
An automated process and apparatus is provided for establishing the basic xerographic operating parameters for an electrophotographic printing machine. The document scanning means is used in a setup mode to generate test patches of varying density on the machine photoreceptor. The levels are measured and compared to present values stored in a digital controller memory until convergence is obtained along three separate points on the PIDC curve. The controller adjusts the system parameters of charge circuit, developer bias and system exposure in an iterative process and corresponding to the photo-induced discharge curve for the particular machine.