Abstract: A corona discharge device including a throw-away subassembly which is inexpensive and can therefore be discarded when it becomes ineffective for its intended purpose. The subassembly can be readily installed into the printing machine in which it is used. It comprises a generally rectangular-shaped insulative frame and a tungsten wire. When the subassembly is inserted into the machine, it cooperates with a generally U-shaped, conductive shield which is an integral part of the machine to form the corona discharge device.

Abstract: A page printer for selectively printing on a paper, including means for selectively charging the paper by applying radiant energy to selected portions to cause electrons to be removed from the normal bond, applying a high voltage field to prevent the removed electrons from returning to the paper, thereby charging the paper, applying and then fixing the toner to obtain the desired printout. The means for selectively applying radiant energy can be a field of light emitting diodes or scanning circuit means for selecting the LEDs of the field to be energized. The means for selectively supplying radiant energy can operate responsive to input information from a computer, memory means, or responsive to keyboard input information.