Abstract: A non-impact printing apparatus and method for tri-level color xerographic recording. A binary printhead having M recording elements per inch is used to record each mainscan line (1/M lines per inch) of pixels using two sublines for recording each mainscan line. In a first embodiment, pixels to be developed in a first color are recorded during a first subline, and during a second subline of pixels to be developed in a second color are recorded using a different exposure duration from that used in recording the first subline of pixels. In a second embodiment, pixels of the first and second colors are recorded during a first subline and supplementary exposure is provided for completing the recording of pixels of the second color during a second subline of recording.

Abstract: In an electrophotographic printer first and second printheads are provided for recording, in accordance with electronic data the same image frame. To reduce the cost for mechanical supports needed to accurately register pixels recorded by the respective printheads, a test is run to determine the misregistration between the printheads and the data to be printed. In response to these tests, the timing and/or cross-track position of the printing of the pixels on the recording member is adjusted to register the pixels printed by one printhead with those printed by the other.

Abstract: A device for generating printed output has an array of point light sources focused onto a photosensitive surface. The array is spaced from the surface substantially at the position of best focus by generating a pattern of activated and unactivated light sources along the array such that a pair of light sources which lead to the creation of an image on the output are separated by a light source which does not lead to the creation of an image. Since the image size grows in width as the focus decreases, the width of the space between images can be used as a focusing gauge, and appropriate adjustments can be made to maximize the width of the space.

Abstract: An electronic flash unit has a safety circuit for removing stored electrical energy that is potentially hazardous to a flash unit user. A switch, responsive to opening of the flash unit housing, is closed to energize a quench circuit, which is parallel to a chargeable flash firing capacitor. The firing capacitor discharges through the quench circuit, thereby lowering the stored electrical energy to a level that is not hazardous to an operator.