Abstract: Color electrophotographic printers having latent image positions synchronized with start-of-scan signals. A laser source projects a laser beam onto a multifaceted rotating polygon that sweeps that beam in a scan line across a moving photoreceptor. A start-of-scan detector produces start-of-scan signals when the laser beam is in position to write a scan line. A belt sensor produces belt signals when indicia on the photoreceptor passes a reference position. A controller receives the belt signals and the start-of-scan and then adjusts the photoreceptors rotational velocity such that the belt signals are an integral multiple of the start-of-scan signals. To reduce the impact of drive roller eccentricities on belt signal to start-of-scan signal timing, the perimeters of photoreceptor roller elements are sub-multiples of the photoreceptor length.

Abstract: Systems and methods are provided that improve the registration between the color separation images. The systems and methods control the output of the image data for one or more of the color separation images and the velocity of an image-carrying member to remove or reduce registration offsets based on determined position and velocity of the image-carrying member. A position-determining sensor on an image-carrying member device module is used to determine the process-direction position of the image-carrying member to provide real time motion information. A position-determining controller determines the process-direction position of the image-carrying member by detecting a pattern of position-determining marks using the position-determining sensor and processing the detected data through averaging or correlation to eliminate detection errors.

Abstract: A method and apparatus for periodically upgrading the color calibration for an electrophotographic printer (or other digital document viewing device) using a color compensator is proposed. Initially, a fairly large number of colors are printed and measured. From this information a color correction is determined and stored in a high density compensator. A small number of color patch samples are printed and measured at regular intervals during the use of the printing machine. This low density information which is periodically updated compensates for slow drift in the high density compensator. Each time the small patch printing process is repeated a different set of colors is used to assure that all regions within the gamut of the machine are updated uniformly. A similar process can be used to maintain the gray scale fidelity in a black and white printer or digital document display device.

Abstract: An apparatus and method for registering and deskewing a sheet along a sheet path. A pair of drive spheres are located in the sheet path. When a sheet enters the nips formed by the spheres the sheet is driven until it is sensed by a sensor. The drive spheres are driven by a pair of wheels which allow the spheres to rotate about any axis through their center and parallel to the plane of the sheet. The spheres are driven such that the sheet is side registered and deskewed as it is moved along the sheet path. Constant feedback from the sensors to the drive controller allows the sheet to be registered in a very short distance and has the added benefit of self compensation for wear of the drive components. The wide registration and deskewing latitude of the device allows for the use of relatively inexpensive and low accuracy sheet drives preceding the device.

Abstract: There is provided a calibration system for a deskewing and registering device for an electrophotographic printing machine. The method includes a.) moving a sheet from a first position to a second position along a paper path; b.) sensing the position of the sheet at the first position and the second position; c.) choosing a correction value to cause the sheet to change a lateral position from the first position to the second position; d.) repeating the moving, sensing, and choosing steps until a predetermined adjustment is made when moving the sheet from the first position to the second position to determine a proper calibration value.

Abstract: An apparatus and method for registering and deskewing a sheet along a paper path. A pair of independently driven selectively actuable nips are used to drive a sheet transverse to a paper path direction until the edge of a sheet is registered laterally and in skew. The transverse nips are then deactivated and a drive nip moves the sheet in a process direction along the paper path. A first transport sensor senses the lead edge of a sheet, a second sensor is used to also detect the lead edge of a sheet within a certain distance from the detection by the first sensor. The transport drive nip can then be adjusted based on the transport time between the first transport sensor and the second transport sensor so that the sheet arrives at a registration sensor at the prescribed time. This apparatus and method allows the use of simple point type sensors as opposed to more complex and expensive sensor arrays.

Abstract: A deskewing and registering device for an electrophotographic printing machine. A single set of sensors determine the position and skew of a sheet in a paper path and generate signals indicative thereof. A pair of independently driven nips forward the sheet to a registration position in skew and at the proper time based on signals from a controller which interprets the position signals and generates the motor control signals. An additional set of sensors can be used at the registration position to provide feedback for updating the control signals as rolls wear or different substrates having different coefficients of friction are used.

Abstract: A piezoelectric bimorph scanner is disclosed which has a flexural beam attached to the free end of a cantilever mounted piezoelectric bimorph crystal. A mirror is bonded to the flexural beam a predetermined distance from the bimorph crystal. An AC voltage of predetermined frequency is applied to the bimorph crystal causing the flexural beam to oscillate with a node at the center of the mirror. The mirror rotates about the node rather than swinging in an arc, enabling the scanner to deflect a collimated light beam over a larger deflection angle than heretofore possible without additional light beam control apparatus. In an alternate embodiment, a laser diode may be mounted on the flexural beam instead of the mirror, further reducing costs and components.