Abstract: Techniques for calibrating a scanner mounted on a scanning carriage of an image forming device. The scanner array can also be used for print media border location.

Abstract: A sensor system for detecting skew in print media along the feed path of a hardcopy device is disclosed. In one embodiment of the invention the system is arranged to generate a first image of a portion of print media at a first position along the feed path and to generate a second image of the portion of print media at a second position along the feed path, the system is arranged to compare the first and second images and thereby detect a change in the angle of skew of the media between the first and second positions.

Abstract: A method of an embodiment of the invention is disclosed in which a linear imaging array captures a first one pixel-wide image of media, and the media is effectively advanced relative to the linear imaging array. The linear imaging array captures a second one pixel-wide image of the media, and the first and the second one pixel-wide images are compared to determine relative advancement of the media.

Abstract: A method of an embodiment of the invention is disclosed in which a linear imaging array captures a first one pixel-wide image of media, and the media is effectively advanced relative to the linear imaging array. The linear imaging array captures a second one pixel-wide image of the media, and the first and the second one pixel-wide images are compared to determine relative advancement of the media.

Abstract: A method for image recognition. In the method, a section of an element is imaged while the element is at a first speed to obtain a first image pattern. The section of the element is also imaged while the element is at a second speed to obtain a second image pattern. The first speed differs from the second speed. In addition, the apparent speeds of the element in the first image pattern and the second image pattern are made to appear approximately the same.

Abstract: By implementation of an optical scanner, the calibration of printheads of a printing mechanism may be performed in a relatively short period of time as compared to known techniques. In one respect, the time required to perform the calibration may be substantially reduced by virtue of the relatively wide field of view of the optical scanner. The relatively wide field of view generally enables for the scanning of test patterns to be performed with a relatively fewer number of scanning passes, thus reducing the time required to perform the scanning operations as well as the calibration operations. In addition, the scanning operations may yield relatively more accurate results as compared to known scanning operations. In one respect, optical scanners are capable of detecting smaller drops of ink on print media by virtue of their higher resolution capabilities.

Abstract: By implementation of an optical scanner, the calibration of printheads of a printing mechanism may be performed in a relatively short period of time as compared to known techniques. In one respect, the time required to perform the calibration may be substantially reduced by virtue of the relatively wide field of view of the optical scanner. The relatively wide field of view generally enables for the scanning of test patterns to be performed with a relatively fewer number of scanning passes, thus reducing the time required to perform the scanning operations as well as the calibration operations. In addition, the scanning operations may yield relatively more accurate results as compared to known scanning operations. In one respect, optical scanners are capable of detecting smaller drops of ink on print media by virtue of their higher resolution capabilities.

Abstract: A scan axis assembly for a printer comprises first and second tracks, the tracks being rigidly located relative to one another by one or more track support members, and each track being arranged to support a print carriage such that the print carriage may move along the track to traverse a print zone.

Abstract: The present invention is directed to a method and apparatus for testing the operational status of printhead nozzles. High throughput drop detection devices are used to detected ink drops that are fired from the printhead nozzles, and the operational status is determined from the ink drop characteristics. The ink drop characteristics may include the presence or absence of an ink drop. Ink drop characteristics may also include the size and the location of an ink drop. The drop detection devices are capable of detecting a plurality of ink drops that are ejected substantially simultaneously.

Abstract: An optical sensor for detecting the position of marks on a medium, wherein relative motion is provided between the optical sensor and the medium during an optical sensing operation. The optical sensor produces an electrical sensor signal, and has a field of view at the media in a direction of the relative movement. The marks have a nominal dimension in the direction of the relative movement, and the field of view is larger than the nominal dimension. This produces a sensor signal with a clear and relatively sharp peak in response to scanning the media mark.

Abstract: The present invention is directed to a method and apparatus for testing the operational status of printhead nozzles. High throughput drop detection devices are used to detected ink drops that are fired from the printhead nozzles, and the operational status is determined from the ink drop characteristics. The ink drop characteristics may include the presence or absence of an ink drop. Ink drop characteristics may also include the size and the location of an ink drop. The drop detection devices are capable of detecting a plurality of ink drops that are ejected substantially simultaneously.

Abstract: By implementation of an optical scanner, the calibration of printheads of a printing mechanism may be performed in a relatively short period of time as compared to known techniques. In one respect, the time required to perform the calibration may be substantially reduced by virtue of the relatively wide field of view of the optical scanner. The relatively wide field of view generally enables for the scanning of test patterns to be performed with a relatively fewer number of scanning passes, thus reducing the time required to perform the scanning operations as well as the calibration operations. In addition, the scanning operations may yield relatively more accurate results as compared to known scanning operations. In one respect, optical scanners are capable of detecting smaller drops of ink on print media by virtue of their higher resolution capabilities.

Abstract: A test pattern is scanned to find ideal print-medium advance for a pen (or other marking device). The pattern has a medium; and, marked on it, image patches each with overlapped swaths stepped by different distances. At best there are different-color pens; and for each distance a set of patches, each with a patch for each color (preferably area fills at sensitive tones by color). All patches in a set are best adjacent along a scan direction, with alignment lines above each set across the whole pattern, and a nozzle-conditioning patch at each image patch. A processor prints the pattern, operates a sensor and uses its signals to find optimum advance. The system finds and prints with ideal advance for a most-active pen; or weighs pen activity to find an optimum for all pens based on certain statistical and/or prospective choices.

Abstract: A diagnostic technique allows an easy visual detection of poor media advance calibration. The diagnostic technique employs a print mode that prints different areas of the plot at different passes with a controlled amount of advances between them. The dot positioning error in the different areas has a non-systematic nozzle contribution, that tends to cancel out, and a systematic contribution due to the accumulative media advance error. Different patterns can be used to make the dot positioning error due to the accumulative media advance error show up. By increasing the number of media advances between the printing of sets of pixels, e.g. pixels in a horizontal line, the effect of accumulated errors and the apparent visual effect is increased.

Abstract: To compensate for color-calibration sensor drift, a measurement of bare-print-medium tonal value is taken in immediate time juxtaposition to each color test pattern; measured bare-medium tone is then used to correct color-patch readings. A line sensor or the like, on the scanning printhead carriage, is used for the reading. Preferably two such readings are taken, one at each end of each test pattern; ideally separate scans of the bare medium are taken without any test-pattern patch to develop longterm and short-term drift profiles, for refining the corrections. To compensate for calibration error due to runout in the carriage track—particularly for wide-bed printers—sensor response to bare medium is used to represent variations in carriage-to-medium spacing along the track; these variations are corrected in later sensor use.

Abstract: A calibration technique, for a printer having a plurality of different color ink printheads, which includes printing and scanning a test pattern. The test pattern is printed by each printhead printing a plurality of swaths having a length and distanced apart from each other. An optical sensor is used to scan the printed test pattern. Calibration is performed for each head by reading the swath length and the relative spacing of the swath and comparing the length to the spacing. This comparison is used to find the directional error for each head.

Abstract: A test pattern is scanned to find ideal print-medium advance for a pen (or other marking device). The pattern has a medium; and, marked on it, image patches each with overlapped swaths stepped by different distances. At best there are different-color pens; and for each distance a set of patches, each with a patch for each color (preferably area fills at sensitive tones by color). All patches in a set are best adjacent along a scan direction, with alignment lines above each set across the whole pattern, and a nozzle-conditioning patch at each image patch. A processor prints the pattern, operates a sensor and uses its signals to find optimum advance. The system finds and prints with ideal advance for a most-active pen; or weighs pen activity to find an optimum for all pens based on certain statistical and/or prospective choices.

Abstract: A test pattern is printed and thereafter scanned with a carriage-mounted optical sensor in order to automatically calibrate relative location and alignment between the separate printheads such as CYMK printheads in both the X-axis (media advance) and the Y-axis (carriage scan). To improve the precision of the calibration, the system and method employ small subset groupings of multiple test pattern samples with common reference markings. Each different test pattern is formed by multiple pairs of spaced-apart bars printed by each printhead in a subset associated with a common reference mark such as a magenta reference bar, and the resulting optically sensed measurements may then be averaged over the entire pattern.

Abstract: A nozzle detection test pattern has been developed which can be sensed by an optical sensor located on an inkjet printer carriage. By having the same nozzle print ink drops on multiple pixels to form a single thickened test line during multiple passes of the printhead, it is possible to thereafter scan across such test line and automatically determine by the light contrast ratios which nozzles are not firing properly. A green light LED is used to illuminate the magenta, cyan and black test patterns as they are being sensed, and a blue light LED is used to illuminate the yellow test pattern as it is being sensed. A separate test pattern is used for each printhead ink color. The test pattern constitutes six rows with forty test lines on each row for a printhead having 240 active nozzles.

Abstract: A calibration technique for a plurality of different color ink printheads which includes printing and scanning a test pattern which incorporates two different calibration adjustments from the same test pattern, with one calibration adjustment at right angles to the scan axis. Further calibration precision is provided by incorporating a controlled color background for the test pattern that minimizes light reflection, as well as basing printhead alignment on the overall swath height of the printheads rather than the centers of the printheads.