Abstract: Method and devices for reducing printing artifacts. In one embodiment, a method includes directing ink onto a medium, the medium having a trailing edge; tracking the position of the medium in relation to a nip roller; adjusting the direction of ink onto the medium a first time when the trailing edge of the medium is in close proximity to the nip roller; and adjusting the direction of ink onto the medium a second time.

Abstract: Printheads configured to operate in accordance with a plurality of print modes. For example, one of the plurality of print modes can be selected in accordance with a bit of address data received by the printhead. In an exemplary embodiment, the selection of print mode can be accomplished by switching one or more actuator (e.g., heater) circuit addresses on the printhead.

Abstract: Methods and systems for calibrating media indexing errors in a printing device are provided. In one embodiment, the method comprises feeding a calibration media through a printing device, sensing the position of the media as it moves through the printing device, sensing positions of a media indexing component as the media moves through the printing device, determining media indexing position errors based upon the sensed positions, and calculating a compensation factor to be applied based upon the errors. In some embodiments, parameters of a line and/or other function are determined from the error data and the parameters are utilized to calculate a compensation factor. Moreover, in some embodiments, it is determined what range the data fits within, and a predetermined compensation factor is determined based upon the range.

Abstract: A method of printing on a print medium includes using a first quantity of nozzles of a printhead to print a first set of scan lines of a plurality of scan lines at an edge of the print medium; using a second quantity of nozzles of the printhead to print a second set of scan lines of the plurality of scan lines in an interior region of the print medium; using a third quantity of nozzles to print a third set of scan lines of the plurality of scan lines to transition between the edge and the interior region, the third quantity of nozzles being greater in number than the first quantity of nozzles and less in number than the second quantity of nozzles; and printing each scan line of the plurality of scan lines forming the image with a same number of multiple passes of the printhead, regardless of the number of nozzles used for printing during a particular pass of the printhead.

Abstract: The invention provides an apparatus and method for printing an image using the printhead of an ink jet printer. The printhead ejects ink drops on a print medium in a series of scanning passes, and different addressing patterns are selected in each scanning pass to address ink drop locations for different portions of the raster lines addressed by each scanning pass. Addressing patterns having various interlacing percentages are selected in order to produce overlapping boundary regions between passes. The overlapping boundary regions minimize the banding effects that occur with inexact ink drop placement.

Abstract: A method of printing using an ink jet printer includes the steps of: defining at least one scan line with a plurality of pixel locations spaced apart at a predetermined print resolution; scanning a printhead across the scan line at a first velocity; printing on the scan line at selected pixel locations at the first scan velocity; scanning the printhead across the scan line at a second scan velocity which is different from the first scan velocity; and printing on the scan line at selected pixel locations at the second scan velocity.

Abstract: Methods and systems for calibrating media indexing errors in a printing device are provided. In one embodiment, the method comprises feeding a calibration media through a printing device, sensing the position of the media as it moves through the printing device, sensing positions of a media indexing component as the media moves through the printing device, determining media indexing position errors based upon the sensed positions, and calculating a compensation factor to be applied based upon the errors. In some embodiments, parameters of a line and/or other function are determined from the error data and the parameters are utilized to calculate a compensation factor. Moreover, in some embodiments, it is determined what range the data fits within, and a predetermined compensation factor is determined based upon the range.

Abstract: An ink-jet printer is provided with a printhead maintenance system which is capable of providing optimum maintenance for different types of color or monochrome printheads. Dummy heaters are provided in each printhead as a way of identifying the different types of printheads. A maintenance controller is provided in the printer for executing a maintenance program comprising first and second maintenance algorithms for controlling maintenance of monochrome and color type printheads. The controller includes an E.sup.2 PROM memory into which descriptor records are downloaded from a data processor to which the printer is connected. Each descriptor record contains a head detection pattern and various parameters specifying the number and time of wipes, the number of nozzle fires, etc. necessary to maintain a head of the type corresponding to the head detection pattern.

Abstract: A maintenance station for an ink jet printer comprises two modules supported from the printer middle frame by a tongue and groove arrangement and secured in place only by retaining elements integrally formed with the middle frame. The first module includes a wiper element and a cap to provide an air seal around the nozzles. The wiper and cap are mounted on a pivoted rocker element so that as the wiper is moved toward the printhead the cap is moved away therefrom and visa-versa. The second module carries a small DC motor, a nut with a pair of forked arms, and gearing for converting bidirectional rotation of the motor into linear reciprocal motion of the forked arms. The forked arms engage projections on the rocker element so that the wiper or cap is moved toward or away from the printhead depending on the direction of rotation of the motor. In a first position of the rocker element the wiper is positioned in the path of the printhead so as to wipe the nozzles as the printhead is moved back and forth.

Abstract: A system for automatically adjusting the print head gap of an impact printer, particularly for paper stocks of differing thicknesses and multi-layer forms, provides for measurement of an absolute distance between an undeflected platen position and a home position of the print head. Paper stock thickness is measured by measuring the distance to the home position from a position of the print head when a predetermined force is exerted by the print head against the platen. Since a similar measurement is made when paper stock is not present in the printer and using the same force against the platen, platen flexure is removed as a source of error and a standardized force is available for compression of the paper stock during measurement. Improved accuracy is achieved at high speed while avoiding the use of position encoder/decoder arrangements. A wider range of manufacturing variations in printer geometry and rigidity can be accommodated with uniformly improved print quality.

Abstract: A print quality enhancement arrangement for a dot matrix printer such as a thermal ink jet printer. The arrangement includes a buffer for receiving 300 dots per inch (dpi) resolution data in the horizontal (print head movement) direction and creates 600 dpi resolution data using image enhancement techniques. The arrangement further includes correction of the higher resolution data to remove pels which are unprintable due to the frequency response of the print elements in the print head. The correction is performed using knowledge of the history of printed pels and the original 300 dpi data. The creation of the higher resolution data and its correction occur "on-the-fly" as data is being fed to the print head, rather than through the creation of a 300 by 600 dpi bitmap.

Abstract: The printhead of an ink jet printer is mounted on a printhead carrier for reciprocal movement on a carrier guide rod above a record feed path. A bi-directional motor drives a drive belt attached to the carrier to thereby pull the printhead back and forth. The belt is attached to the carrier at two points which are spaced from the axis of the carrier guide rod, one point being above the axis and the other point being below the axis. The arrangement is such that any tilt of the printhead carrier in a vertical plane, resulting from a pulling force of the drive belt, is always in the same direction regardless of the direction in which the printhead carrier is pulled. This improves the accuracy of ink dot placement thereby giving better print quality. The drive belt is mounted on pulleys which are positioned such that there is an upward incline from each attachment point to a pulley. The carrier is provided with feet which ride in a groove in a carrier guide.

Abstract: In a printer having P+X printing elements for printing pixels with a vertical center-to-center spacing R.sub.1 during a plurality of line scans, and a stepper motor for moving a record medium in increments R.sub.2 where R.sub.2 is greater than R.sub.1, all points addressable printing is obtained by a combination of movement of the record medium orthogonal to the line scan direction and shifting address signals applied to the print elements. The stepper motor moves the record medium a distance k.sub.2 R.sub.2 between successive line scans and address signals are applied to (n+k.sub.1)th . . . (n+k.sub.1 +P-1)th print elements to cause a shift k.sub.1 R.sub.1 such that the sum of the distance the record medium is moved before a line scan and the shift caused by the address signals during a scan is equal to PR.sub.1 where P is the number of print elements active during the preceding line scan, or equal to any desired integral multiple of R.sub.1 in other print modes.

Abstract: A stepper motor damping control system. Damping is performed by switching the power supply connection(s) of energized motor phase windings alternatively ON and OFF at a predetermined relatively high fixed rate. Said switching is performed using a clock signal information for switching one way and an information denoting equality between a voltage substantially proportional to the current flowing through said motor phase windings with a predetermined sawtooth sloped reference signal synchronized with said clock signal for switching the other way.