Abstract: The white vector—the voltage difference between white areas of a latent image on a photoconductive unit and a developer roller—may be independently adjusted at each photoconductive unit, allowing multiple image forming units to be driven from a shared power supply. The photoconductive unit is charged to a high voltage level relative to the developer roller, and selectively optically discharged to the desired white vector by a first laser source. The voltage of the discharged area may be measured, or may be calculated by increasing the developer roller voltage a predetermined amount, discharging the photoconductive unit until toner is sensed in white image areas, and then reducing the developer roller voltage. The white areas are discharged using a different light source, such as a laser, LED or electroluminescent source. A second laser may be of a different wavelength than a writing laser.

Abstract: An imaging apparatus includes a controller communicatively coupled to a first laser, a second laser, a scanning device and a light sensor. The controller is configured to perform actions including controlling the first laser, the second laser and the scanning device to simultaneously scan the first light beam and the second light beam across an image region of the photoconductive substrate over a plurality of scans to form a latent image on the photoconductive substrate; activating only the first laser outside the image region between first successive scans of the plurality of scans to sense with the light sensor the first light beam; and activating only the second laser outside the image region between second successive scans of the plurality of scans to sense with the light sensor the second light beam.

Abstract: A method for improving the operation of an electrophotographic printer. The method includes providing an electrophotographic printer containing a laser scanning unit. A torsion oscillator for the laser scanning unit is enclosed in closed compartment. The closed compartment includes side walls having first and second side wall edges, a bottom wall attached on the first side wall edges, and a cover attached adjacent to the second side wall edges. The closed compartment is sufficient to reduce stray air currents from adjacent the torsion oscillator thereby improving the operation of the electrophotographic printer.