Abstract: An image forming apparatus includes a plurality of photoconductive drums, each photoconductive drum transferring a portion of a toner image to an intermediate transfer member. The photoconductive drums are individually rotated to a printing speed such that a downstream photoconductive drum starts rotating prior to an adjacent upstream photoconductive drum starts image transfer. Similarly, an upstream photoconductive drum starts deceleration when its following downstream station has transferred image.

Abstract: An image forming apparatus includes a plurality of photoconductive drums, each photoconductive drum transferring a portion of a toner image to an intermediate transfer member. The photoconductive drums are individually rotated to a printing speed such that a downstream photoconductive drum starts rotating prior to an adjacent upstream photoconductive drum starts image transfer. Similarly, an upstream photoconductive drum starts deceleration when its following downstream station has transferred image.

Abstract: A print system comprises a printer including a printer controller. One or more optional support devices are associated with the printer, wherein each optional support device includes a device controller. The system further includes a bi-directional serial communications path, including one or more trunklines, which provides serial electrical interconnection between the printer controller and each device controller of each optional support device of the system. The printer controller automatically assigns a unique device address to each optional support device. Each optional support device further includes logic circuitry which, based upon a command of the printer controller, enables passage of information generated by the printer controller through a first optional support device to a next electrically serially connected optional support device following an assignment of a first device address to the first optional support device.

Abstract: A method of positioning an ink jet printhead in a printer includes dividing a bitmap into a plurality of rows of tiles. A subset of the rows of tiles to be printed in a next pass of the printhead is identified. Printable ones of the tiles in the subset of rows are identified. The printable tiles contain printable data. Within each printable tile, a top most location of the printable data and at least one of a left most location of the printable data and a right most location of the printable data are identified. A print medium is advanced in a feed direction until a portion of the print medium corresponding with the top most location of the printable data of at least one printable tile is substantially aligned with a top nozzle of the printhead.

Abstract: A method of positioning an ink jet printhead in a printer includes dividing a bitmap into a plurality of rows of tiles. A subset of the rows of tiles to be printed in a next pass of the printhead is identified. Printable ones of the tiles in the subset of rows are identified. The printable tiles contain printable data. Within each printable tile, a top most location of the printable data and at least one of a left most location of the printable data and a right most location of the printable data are identified. A print medium is advanced in a feed direction until a portion of the print medium corresponding with the top most location of the printable data of at least one printable tile is substantially aligned with a top nozzle of the printhead.

Abstract: An improved printer is provided which includes a print engine control program that minimizes the power consumption of the paper-handling devices to allow for a smaller DC power supply. Some of the paper-handling devices are input paper trays, output paper stackers, and a duplexer, which all preferably contain a microcontroller and an individual electric motor drive. The base printer also contains a microcontroller in the print engine that controls the printer's mechanisms and various subassemblies that are used in the laser electrophotographic printing process. To maintain control of the entire paper path, the print engine sends commands to the paper-handling devices, and these devices send responses to these commands. Most of the printer's paper-handling devices receive their electrical power entirely from the base printer, which is supplied as a DC voltage. The print engine avoids the concurrent running of subsystems in cases where the functionality of the printer is not compromised.

Abstract: A print system includes a printer having a printer controller. One or more optional support devices are associated with the printer, wherein each optional support device includes a device controller. The system further includes a bi-directional serial communications path, including one or more trunklines, which provides serial electrical interconnection between the printer controller and each device controller of each optional support device of the system. The printer controller automatically assigns a unique device address to each optional support device. Transmission error detection system and method are provided at the printer controller and/or each optional support device.

Abstract: A circuit for selecting a base memory to be accessed by a microcontroller in response to a command from the microcontroller. An input receives the command from the microcontroller. The command selectively instructs the circuit to reset the microcontroller and signal the microcontroller to access an internal memory as the base memory. Also, the command selectively instructs the circuit to reset the microcontroller and signal the microcontroller to access an external memory as the base memory. A reset output is used to send the reset signal to the microcontroller, and a memory select output is used to send a memory select signal to the microcontroller.

Abstract: A laser printer is provided having an automatic printhead identification system for use in a family of laser printers that are compatible with more than one model of printhead. For example, a single laser printer model can be made so that two different printheads can be successfully used, so long as the printer system knows which laser printhead has actually been installed. To detect which printhead has been installed, the printer operating system provides a reference clock signal having a pre-determined frequency, which dictates the rotational speed of the motor. Once the motor has achieved a "lock" operational speed, the printer measures the scan rate of the faceted mirror by detecting the time interval between pulses of the "HSYNC" signal. The HSYNC signal is sent to a "divide-by-n counter" circuit which divides the pulse frequency of the HSYNC signal, thereby increasing the time interval (by a factor of "n") that must be sensed by the system to determine which printhead is in fact installed.

Abstract: The invention is directed to a method of calibrating a laser in an electrophotographic image forming apparatus used for producing a print image on a print medium. A laser having a selectively energizable laser beam output is provided. A rotatable optical device and the laser combine to define a movable projection path of the laser beam output. Rotation of the optical device results in movement of the projection path across a scan line overlaying a photoconductive drum. The optical device has a rotational acceleration upon initial rotation thereof with a ramp-up period during which the rotational velocity increases. A safe area is established in a portion of the scan line which does not overlay an image area on the photoconductive drum. The laser is energized and calibrated when the projection path is positioned in the safe area. The calibration is carried out during the ramp-up period of the rotating optical device.

Abstract: A laser printer (3) can initiate a line of printing only when the sweep of the laser light reaches a point in its cycle. An inkjet printer (5) moves paper by stepper motor in increments. Switch (9) senses the paper (15) to determine the location of paper in path (6) with respect to nominal printing locations of the laser printer. The closest nominal position is selected for printing. The paper may lead or lag the selected position. Switch (11) senses the paper to determine the location of paper in the path with respect to nominal printing locations of the inkjet printer. Two leads are added to reach a net greater lead, a lag is subtracted from a lead, and two lags are added to reach a net greater lag. The closest nominal position is then selected. This assures that registration does not vary by more than one half of the spacing between nominal locations of the second printer.