Abstract: Using a document scanner or other image input device of an image or document processing system to periodically scan or image printed test images from a plurality of marking engines replaces internal sensors as a feedback means in image quality control. For example, image lightness (L*) is controlled by periodically printing mid-tone test patches, scanning the printed test patches with a main job document scanner and analyzing the scanned image to determine updated marking engine actuator set points. For instance, ROS exposure and/or scorotron grid voltages are adjusted to maintain image lightness consistency between marking engines.

Abstract: A toner container cartridge and refilling apparatus is provided for including (a) a wall defining a toner containing chamber for containing refill toner, a first end and second end; (b) a movable sealing disc closing the first end of the chamber; (c) a thin rupturable membrane sealing the second end of the chamber; (d) means for coupling the second end to a toner cartridge to be refilled with toner; and (e) a piston device for contacting and moving the sealing disk from the first end towards the second end of the chamber, thereby dispensing the refill toner from the storage chamber into the toner cartridge.

Abstract: A printing apparatus includes a guide member for directing sheets toward a transfer zone. The guide member defines a set of ribs which hold the sheets above the main surface of the guide member. Thus, any stray marking material which lands on the guide member is relatively unlikely to contact a sheet moving over the guide member.

Abstract: A printing apparatus includes a guide member for directing sheets toward a transfer zone. The guide member defines a set of ribs which hold the sheets above the main surface of the guide member. Thus, any stray marking material which lands on the guide member is relatively unlikely to contact a sheet moving over the guide member.

Abstract: In a xerographic printing apparatus, during the transfer step wherein marking material is electrostatically transferred from the photoreceptor to the print sheet by a transfer corotron and the sheet is then detached from the photoreceptor by a detack corotron, the bias associated with the transfer corotron is maintained at a constant value while the bias associated with the detack corotron is progressively decreased to approximately zero as the print sheet moves through the transfer zone.

Abstract: An apparatus and method are described for extending the life of a photoreceptor in xerographic printing. At a predetermined point in the life span of a photoreceptor, a correction circuit is interposed between the power supply and the charging device of the printer. Correction circuits of different designs can be selected to compensate for the photoreceptor properties at different stages of its useful life. The different correction circuits can be automatically activated over time, or can be retrofitted into a replaceable module when the replaceable module is remanufactured.

Abstract: In a xerographic printing apparatus, during the transfer step wherein marking material is electrostatically transferred from the photoreceptor to the print sheet by a transfer corotron and the sheet is then detached from the photoreceptor by a detack corotron, the bias associated with the transfer corotron is maintained at a constant value while the bias associated with the detack corotron is progressively decreased to approximately zero as the print sheet moves through the transfer zone.

Abstract: A xerographic printer includes a rotatable photoreceptor which is exposed, with each cycle, by a regular exposure device to create an image desired to be printed. Elsewhere along the photoreceptor is disposed a supplemental discharge device which discharges only those small areas on the photoreceptor which were not discharged by the regular exposure device within the cycle. In this way, every small area of the photoreceptor is evenly discharged within each cycle, and thus every small area of the photoreceptor experiences the same amount of aging. The system is particularly useful for full-color xerographic printers, in which the photoreceptor is repeatedly discharged by different exposure devices within each cycle.

Abstract: A solenoid-controlled sheet registration mechanism for a copier/printer includes registration fingers for registering the lead edge of a sheet before it is fed to the transfer station of the copier/printer, to receive a developed image from the photoreceptor. The mechanism also includes a pair of nip rolls for forwarding the sheet to the transfer station, after registration. Energization of the solenoid moves the registration fingers into the registration position and disengages the nip rolls. Conversely, release of the solenoid allows the registration fingers to return to a non-registration position and the nip rolls to return to paper-feeding engagement, both of those return movements taking place under a resilient bias. To soften the impact between the nip rolls as they re-engage, and so reduce any resulting noise, the release of the solenoid is controlled by applying a pulsed drive signal to the solenoid during the release period after the energizing signal has ceased.

Abstract: A printing machine, having operating parameters associated therewith, for producing prints is provided. The printing machine includes a controller for controlling the operating parameters and an operator replaceable sub-assembly adapted to serve as a processing station in the printing machine. The operator replaceable sub-assembly includes a memory device, communicating with the controller when the replaceable sub-assembly is coupled with the printing machine, for storing a value which varies as a function of the usage of the replaceable sub-assembly, the controller adjusting a selected one of the operating parameters in accordance with the stored value for maintaining printing quality of the printing machine.

Abstract: In a laser printer, in which a latent image is generated on a circulating imaging member in accordance with digital image signals and subsequently developed with toner, the number of pixels to be toned is used as an indication of the rate at which toner is being depleted from the developer mixture. The device for dispensing fresh toner to the developer mixture is operated in dependence on the number of pixels to be toned so that there is a pre-established relationship between the pixel count and the length of time for which the dispensing device is in operation. If the efficiency of the dispensing device falls, the pre-established relationship is adjusted so that the toner density in the developed images remains constant. If a predetermined level of adjustment is reached, it is taken as an indication that the supply of toner in the printer is low, and should be replenished.