Abstract: Apparatus and techniques are disclosed for aligning the operation of the ink jet printhead cartridges of a multiple printhead ink jet swath printer that includes a print carriage that is movable along a horizontal carriage scan axis, (b) first and second ink jet printhead cartridges supported by the movable carriage for printing onto a print media that is selectively movable along a vertical media scan axis, and (c) an optical sensor supported by the movable carriage.

Abstract: Apparatus and techniques are disclosed for aligning the operation of the ink jet printhead cartridges of a multiple printhead ink jet swath printer that includes a print carriage that is movable along a horizontal carriage scan axis, (b) first and second ink jet printhead cartridges supported by the movable carriage for printing onto a print media that is selectively movable along a vertical media scan axis, and (c) an optical sensor supported by the movable carriage. The optical sensor includes a quad photodiode detector whose outputs are indicative of the horizontal positions of vertical test lines imaged on the detector in conjunction with horizontal alignment correction, as well as the vertical positions of horizontal test lines imaged on the detector in conjunction with vertical alignment correction.

Abstract: Apparatus and techniques are disclosed for aligning the operation of the ink jet printhead cartridges of a multiple printhead ink jet swath printer that includes a print carriage that is movable along a horizontal carriage scan axis, (b) first and second ink jet printhead cartridges supported by the movable carriage for printing onto a print media that is selectively movable along a vertical media scan axis, and (c) an optical sensor supported by the movable carriage. The optical sensor includes a quad photodiode detector whose outputs are indicative of the horizontal positions of vertical test lines imaged on the detector in conjunction with horizontal alignment correction, as well as the vertical positions of horizontal test lines imaged on the detector in conjunction with vertical alignment correction.

Abstract: Scan exposure in a row or swath scanner is controlled by pulsing light sources with pulses that are separated by dark intervals from each other--and from the detector readout periods. Detector sequencing is thereby made independent of the velocity of the pixel-line advance mechanism. Different pulse widths for different colors provide color correction without calculation, or regularize color-space conversion calculations where needed. In a swath scanner, known technology of printing modes is imported into the scanning context. Order of pixel columns within each swath is reversed for printing--permitting use of novel configurations such as a dual-parallel-flatbed copier in which a single common scan-and-advance mechanism simultaneously transports the scan sensor and printheads. To produce mirror images, this configuration is also used without column reversal. In addition to red, green and blue light sources, an infrared source is used for reading invisible indicia that identify forms or media types.

Abstract: Greater throughput is possible by using wider print swaths in each traverse across printing media. Multiple print cartridges are mounted to be offset from each other in the media scan direction (X-axis). The amount of offset is adjustably varied by selective on/off control of individual printing elements as well as by relative mechanical movement of the print cartridges.

Abstract: Apparatus and techniques are disclosed for aligning the operation of the ink jet printhead cartridges of a multiple printhead ink jet swath printer that includes a print carriage that is movable along a horizontal carriage scan axis, (b) first and second ink jet printhead cartridges supported by the movable carriage for printing onto a print media that is selectively movable along a vertical media scan axis, and (c) an optical sensor supported by the movable carriage.

Abstract: Signals indicating ink-discharge presence control priming and preferably halt document creation pending ink resupply--or pending an operator command to go on without resupply. A detector senses ink discharge; circuits including a programmed microprocessor apply the detector signal to control, most typically, pen priming or repriming--and preferably related functions including suspension of printer operation. The detector preferably includes an optical source and detector along an optical path that intersects an ink-discharge path. With a pen that has multiple ink-discharge nozzles, preferably the apparatus distinguishes between ink discharge from the different nozzles (by correlation with nozzle-actuating pulses), and accordingly controls priming of each nozzle independently. Preferably this system is operated before starting to print a new sheet and upon newly installing a pen.

Abstract: Greater throughput is possible by using wider print swaths in each traverse across printing media. Multiple print cartridges are mounted to be offset from each other in the media scan direction (X-axis). The amount of offset is adjustably varied by selective on/off control of individual printing elements as well as by relative mechanical movement of the print cartridges.

Abstract: Apparatus and techniques are disclosed for aligning the operation of the ink jet printhead cartridges of a multiple printhead ink jet swath printer that includes a print carriage that is movable along a horizontal carriage scan axis, (b) first and second ink jet printhead cartridges supported by the movable carriage for printing onto a print media that is selectively movable along a vertical media scan axis, and (c) an optical sensor supported by the movable carriage. Alignment of the operation of the printheads along the media scan axis is performed by determining with the optical sensor the relative positions of horizontal test line segments printed by selected nozzles of the printhead cartridges.

Abstract: Apparatus and techniques are disclosed for aligning the operation of the ink jet printhead cartridges of a multiple printhead ink jet swath printer that includes a print carriage that is movable along a horizontal carriage scan axis, (b) first and second ink jet printhead cartridges supported by the movable carriage for printing onto a print media that is selectively movable along a vertical media scan axis, and (c) an optical sensor supported by the movable carriage. The optical sensor includes a quad photodiode detector whose outputs are indicative of the horizontal positions of vertical test lines imaged on the detector in conjunction with horizontal alignment correction, as well as the vertical positions of horizontal test lines imaged on the detector in conjunction with vertical alignment correction.

Abstract: Apparatus and techniques are disclosed for aligning the operation of the ink jet printheads of a multiple printhead ink jet swath printer, and particularly for aligning the operation of the printheads along the carriage scan axis. The relative positions of vertical test line segments printed by the cartridges at a fixed swath position are determined with an optical sensor. The relative position information is utilized to calculate horizontal alignment corrections for the printhead cartridges which are utilized to adjust the horizontal offset shifts provided for the swath data and to adjust the timing of the firing of the ink jet nozzles of the printhead cartridges.

Abstract: Apparatus for determining inter-pen offsets in a multiple pen ink jet printer including a drop detector for measuring flight time of ink drops, an aperture plate disposed in the print media plane, and a carriage position sensor for determining carriage position when ink drop flight time exceeds a predetermined value, which indicates that an ink jet is at the edge of the aperture plate. The sensed carriage positions for the respective pens provides information indicative of inter-pen offset in the scan axis direction. In a further embodiment of the invention, the aperture plate can have a stair-shaped boundary to facilitate the calibration of a plurality of nozzles in one scan. For determination of inter-pen offset in the media scan direction, the aperture includes a comb-like boundary that is utilized to produce detect/no detect pattern for a nozzle array in each of the pens, whereby the pattern for each of the pens provides information indicative of the offset between pens.

Abstract: Apparatus for determining inter-pen offsets in a multiple pen ink jet printer including a drop detector for measuring flight time of ink drops, an aperture plate disposed in the print media plane, and a carriage position sensor for determining carriage position when ink drop flight time exceeds a predetermined value, which indicates that an ink jet is at the edge of the aperture plate. The sensed carriage positions for the respective pens provides information indicative of inter-pen offset in the scan axis direction. In a further embodiment of the invention, the aperture plate can have a stair-shaped boundary to facilitate the calibration of a plurality of nozzles in one scan. For determination of inter-pen offset in the media scan direction, the aperture includes a comb-like boundary that is utilized to produce the detect/no detect pattern for a nozzle array in each of the pens, whereby the pattern for each of the pens provides information indicative of the offset between pens.

Abstract: A media advance system for swath-type printers for precisely positioning the media for successive swath printing. A dual photodiode line sensor is mounted on the print head. The diode active areas are separated by less than the line widths of lines printed in the media margin. Circuitry is provided to provide a signal indicative of the difference between the photocurrents produced by each photodiode. For the first swath of the page or plot, marginal lines are drawn by the first and Nth print device of the print head. Without moving the media, the line sensor is positioned over the marginal line printed by the first device, and the resulting difference signal is saved as a reference value. The media is then advanced until the same value of the difference signal is obtained from the line image of the marginal line drawn by the Nth print device. The media is then advanced a predetermined amount to precisely position the media for the next successive swath to be printed.

Abstract: A rigid link is provided between a plot medium (14) and a position transducer (50) so that accurate plot medium advance measurement can be attained. The device (30) comprises a movable carriage (42) and an arm-like extension (38) that juts out from the carriage to the plot medium. A friction hold is made between the extension arm and the plot medium by applying a force to the extension arm normal to the plot medium by means of an electromagnet (33) which includes a coil (34), the extension arm serving as the armature. The electromagnet is located beneath the platen (12) which supports the medium on a base (32) which also supports the carriage.With the electromagnet activated, the extension arm is held against the plot medium. As the plot medium is advanced by a plot medium drive system (20), the extension arm and carriage are pulled along. Plot medium advance is stopped when the proper advance distance has been sensed by the position transducer.

Abstract: A pen-lift system is provided which can achieve high speed plotting while maintaining line definition of drafting quality. The system includes a pen-lift mechanism for raising and lowering the pen, a pressure control system in order to provide a constant pen force for different kinds of pens, a velocity controller for varying the vertical velocity of the pen in response to changes in platen height and relative lateral pen position, and a position controller for sensing the present pen height relative to the platen and for actuating the pen-lift mechanism to achieve the desired pen-lift heights for different plotting situations.

Abstract: A controller minimizes periodic torque or force perturbations in an inductor-type synchronous motor drive by supplying current waveforms to each motor phase that contain a fundamental frequency component and selected harmonic components. The harmonic components in the phase currents heterodyne with the periodic permanent magnet flux fundamental frequency to create periodic torques or forces which subtract from the unwanted torques or forces perturbing the moving portion of the motor. The controller, which includes an interpolator, a memory, and a converter, provides for smooth incremental movement of a member such as a plot head, at substantially constant velocity, by applying selected continuous periodic waveform signals as phase currents to the windings of inductor-type synchronous motors.