Claims
- 1. A test pattern for determining optimum printing-medium advance in an incremental printer that uses an image-marking device which prints in a particular colorant; said pattern comprising:a printing medium; and marked on the printing medium, plural representative image patches for the particular colorant; each of the representative image patches comprising plural overlapping swaths of the colorant, corresponding features of said overlapping swaths being spaced by a certain distance selected for each of said patches respectively; said certain distances being different for the plural patches, respectively.
- 2. The test pattern of claim 1, for determining optimum advance in said printer wherein the image-marking device comprises plural marking units, marking in plural different particular colorants respectively; and wherein:said patches comprise for each certain distance a set of plural patches; each set comprising at least one patch for each of said plural colorants.
- 3. The test pattern of claim 2, wherein:in each set, all the patches are adjacent to one another along a scanning direction.
- 4. The test pattern of claim 3, further comprising:plural alignment reference lines printed in association with each set.
- 5. The test pattern of claim 4, wherein:the alignment reference lines are above each set.
- 6. The test pattern of claim 5, wherein:the alignment lines extend across substantially the entire pattern.
- 7. The test pattern of claim 4, further comprising:at least one nozzle-conditioning patch associated with each of the representative image patches.
- 8. The test pattern of claim 3, further comprising:at least one nozzle-conditioning patch associated with each of the representative image patches.
- 9. The test pattern of claim 8, wherein:the nozzle-conditioning patches are adjacent to their associated representative image patches, along the scanning direction.
- 10. The test pattern of claim 1, further comprising:at least one nozzle-conditioning patch associated with each of the representative image patches.
- 11. The test pattern of claim 1, wherein:the representative image patches comprise area fills.
- 12. The test pattern of claim 11, wherein:the area fills are at different tonal levels for at least some of the different colorants, respectively.
- 13. The test pattern of claim 12, wherein:the tonal levels are between twenty-five and fifty-five percent for yellow colorant, and between forty-five and seventy-five percent for at least one other substantially undiluted colorant.
- 14. The test pattern of claim 13, wherein:the tonal levels are at roughly forty percent for yellow colorant, and roughly sixty percent for the at least one other substantially undiluted colorant.
- 15. The test pattern of claim 13, wherein:the tonal levels are between seventy-five and one hundred percent for at least some dilute colorants.
- 16. The test pattern of claim 13, wherein:the tonal levels are at roughly ninety percent for at least some dilute colorants.
- 17. The test pattern of claim 1, wherein:said certain distances are distributed about a nominal value for the advance distance.
- 18. A method of determining optimum printing-medium advance in an incremental printer that uses image-marking devices which print in respective different colors or color dilutions; said method comprising the steps of:printing a test pattern that includes a set of representative image patches at each of plural printing-medium advance settings in turn; each set comprising at least one representative image patch for each of the different colors or color dilutions; and performing optical measurements of the test pattern to ascertain a relationship between said printing-medium advance settings and resulting image quality of said patches.
- 19. The method of claim 18, further comprising the step of, in association with each representative image patch or set, printing at least one feature selected from the group consisting of:a nozzle-conditioning patch; an alignment reference line.
- 20. An incremental printer for using image-marking devices to form images on a printing medium; said printer comprising:a support for such printing medium; a carriage for holding such marking devices and scanning such marking devices relative to such medium, to form such images on such medium; a printing-medium advance mechanism for progressively moving such medium relative to the carriage at right angles to the scanning; a sensor for measuring test-pattern image quality; and programmed processor means for: controlling the carriage, the advance mechanism, and such marking devices to print a test pattern comprising a set of representative image patches at each of plural printing-medium advance settings in turn, each set comprising at least one representative image patch for each of plural different colors, and operating the sensor and interpreting resulting signals from the sensor to determine optimum printing-medium advance.
- 21. The incremental printer of claim 20, in further combination with:said image-marking devices.
- 22. The combination of incremental printer of claim 21, wherein:the image-marking devices comprise inkjet pens.
- 23. The incremental printer of claim 20, wherein the programmed processor means further comprise means for:determining which particular marking device is most active in a particular swath of a desired image; determining an optimum medium advance for at least said particular marking device; and employing said optimum advance for said particular device in printing said particular swath.
- 24. The incremental printer of claim 20, wherein the programmed processor means further comprise means for:determining the relative degree of activity of each marking device, respectively, in a particular swath of a desired image; taking said relative degrees of activity into account in determining an optimum medium advance for all the marking devices considered in the aggregate, at said particular swath; and employing said optimum advance in printing said particular swath.
- 25. An incremental printer for using image-marking devices to form an image on a printing medium; said printer comprising:a support for such printing medium; a carriage for holding such marking devices and scanning such marking devices relative to such medium, to form such image on such medium; a printing-medium advance mechanism for progressively moving such medium relative to the carriage at right angles to the scanning; a sensor for measuring test-pattern image quality; and programmed processor means for: operating the sensor and interpreting resulting signals from the sensor to determine optimum printing-medium advance; thereafter controlling the carriage, the advance mechanism, and such marking devices to employ particular printing-medium advance values while printing such image; and selecting the particular advance values to provide a sequence of values that varies about the determined optimum advance.
- 26. The printer of claim 25, wherein:the sequence of values is a pseudorandom sequence perturbed to preferentially include values relatively nearer to the determined optimum advance.
- 27. The printer of claim 26, wherein:the sequence of values is obtained by a combination of a normal distribution with a pseudorandom number generator, substantially according to the function AP exhibited below, AP being printing-medium advance and AP being a nominal value of printing-medium advance, AP(fi|all i)≡AO·NORMAL[fM(rand), σf]with the distribution truncated to the lower and upper PBF values, where NORMAL≡μ+σ2-σ2·ln[rand(1)]·cos[2π rand(1)]σ≡σf, standard deviation of all fi μ≡fM≡∑i=1NfiN,N≡number of pens, maximum value of i rand (x)≡a function that generates uniformly distributed random numbers from 0 through x NORMAL≡fM+σf2-σf2·ln[rand(1)]·cos[2π rand(1)]so AP≡AO(fM+σf2-σf2·ln[rand(1)]·cos[2π rand(1)])(truncated as mentioned above).
- 28. An incremental printer for using image-marking devices to form an image on a printing medium; said printer comprising:a support for such printing medium; a carriage for holding such marking devices and scanning such marking devices relative to such medium, to form such image on such medium; a printing-medium advance mechanism for progressively moving such medium relative to the carriage at right angles to the scanning; a sensor for measuring test-pattern image quality; and programmed processor means for: operating the sensor and interpreting resulting signals from the sensor to determine an optimum printing-medium advance for each marking device respectively; and thereafter controlling the carriage, the advance mechanism, and such marking devices to employ a particular printing-medium advance value that is substantially the median of the optimum advances for the image-marking devices respectively.
- 29. An incremental printer for using image-marking devices to form an image on a printing medium; said printer comprising:a support for such printing medium; a carriage for holding such marking devices and scanning such marking devices relative to such medium, to form such image on such medium; a printing-medium advance mechanism for progressively moving such medium relative to the carriage at right angles to the scanning; a sensor for measuring test-pattern image quality; and programmed processor means for: operating the sensor and interpreting resulting signals from the sensor to determine an optimum printing-medium advance for each marking device respectively; thereafter determining, for a specific image swath, the image density contributed by each marking device respectively; and thereafter controlling the carriage, the advance mechanism, and such marking devices to employ a particular printing-medium advance value that is substantially a sensitivity-weighted mean of the optimum advances for the image-marking devices respectively; wherein the sensitivity-weighted mean is calculated substantially by weighting an optimum advance value for each marking device by the sensitivity of banding to printing density for a color in that image-marking device respectively.
- 30. The printer of claim 29, wherein:the specific image swath is a swath that is prospectively to be printed; and the particular printing-medium advance value is employed for said specific image swath prospectively to be printed.
- 31. The printer of claim 29, wherein:the sensitivity-weighted mean is found substantially according to the expression exhibited below. AP(fi|all i)≡AO fMWS where fM W S≡∑Si(ρi)Wifi∑Si(ρi)Wiρ1≡density to print by pen i, based on current—pass usage S1(ρi)≡empirical sensitivity of banding to printing density, for color in pen i so AP≡AO∑SiWifi∑SiWi.
- 32. An incremental printer for using image-marking devices to form an image on a printing medium; said printer comprising:a support for such printing medium; a carriage for holding such marking devices and scanning such marking devices relative to such medium, to form such image on such medium; a printing-medium advance mechanism for progressively moving such medium relative to the carriage at right angles to the scanning; a sensor for measuring test-pattern image quality; and programmed processor means for: operating the sensor and interpreting resulting signals from the sensor to determine an optimum printing-medium advance for each marking device respectively; thereafter determining, for a specific image swath that is prospectively to be printed, a characteristic of the image components to be contributed by each marking device respectively; and thereafter, for said specific image swath that is prospectively to be printed, controlling the carriage, the advance mechanism, and such marking devices to employ a particular printing-medium advance value that is a function of the said determined characteristic of image components to be contributed by each marking device respectively.
- 33. The printer of claim 32, wherein:the specific image swath is to be printed substantially immediately.
RELATED PATENT DOCUMENTS
Related documents are other, coowned U.S. utility-patent documents hereby incorporated by reference in their entirety into this document. One is in the names of David Donovan and Miquel Boleda, entitled “APPARATUS AND METHOD FOR MITIGATING COLORANT-DEPOSITION ERRORS IN INCREMENTAL PRINTING”, patent application Ser. No. 09/688,610; another of Cluet et al., “PRINTING AND MEASURING DIRECTLY DISPLAYED IMAGE QUALITY, WITH AUTOMATIC COMPENSATION, IN INCREMENTAL PRINTING” —Ser. No. 09/642,418; another of Zapata et al., entitled “BANDING REDUCTION IN INCREMENTAL PRINTING, BY SPACING-APART OF SWATH EDGES AND RANDOMLY SELECTED PRINT-MEDIUM ADVANCE” —Ser. No. 09/516,816, issued as U.S. Pat. No. 6,336,702; another of Askeland, and entitled “BANDING REDUCTION IN INCREMENTAL PRINTING, THROUGH VARIATION OF NOZZLE COMBINATIONS AND PRINTING-MEDIUM ADVANCE” —Ser. No. 09/516,815; another of Thomas H. Baker et al., Ser. No. 09/183,819 entitled “COLOR-CALIBRATION SENSOR SYSTEM FOR INCREMENTAL PRINTING”; a further one of Chris T. Armijo et al., 08/811,412, “DETECTION OF NON-FIRING PRINTHEAD NOZZLES BY OPTICAL SCANNING OF A TEST PATTEPN”, and now issued as U.S. Pat. No. 6,352,331; still another in the names of Francis Bockman et al., Ser. No. 08/960,766, “CONSTRUCTING DEVICE-STATE TABLES FOR INKJET PRINTING”, and issued as U.S. Pat. No. 6,178,008; and yet another in the name of Ramon Borrell, Ser. No. 09/146,858, “ENVIRONMENTAL AND OPERATIONAL COLOR CALIBRATION, WITH INTEGRATED INK LIMITING, IN INCREMENTAL PRINTING”; a further one in the name of Antonio Murcia et al., Ser. No. 09/211,713, “METHOD AND APPARATUS FOR HIDING ERRORS IN SINGLE-PASS INCREMENTAL PRINTING”, issued as U.S. Pat. No. 6,270,187,; another of Francesc Subirada et al., Ser. No. 09/034,722, “SCANNING AN INKJET TEST PATTERN FOR DIFFERENT CALIBRATION ADJUSTMENTS”, issued as U.S. Pat. No. 6,196,652; another in the names of Joan Manel Garcia-Reyero et al., Ser. No. 09/516,007, later converted to provisional No. 60/219,315, and nonprovisional application Ser. No. 09/632,197 based thereon, “IMPROVEMENTS IN AUTOMATED AND SEMIAUTOMATED PRINTMASK GENERATION FOR INCREMENTAL PRINTING” —and several earlier documents cited therein; another in the name of Jose-Julio Doval, provisional No. 60/179,383 and later nonprovisional application Ser. No. 09/693,524 based thereon, “COMPENSATION FOR MARKING-POSITION ERRORS ALONG THE PEN-LENGTH DIRECTION, IN INKJET PRINTING”. Others are issued U.S. Pat. Nos. 6,062,137 of Shilin Guo et al., “APPLICATION OF SPECTRAL MODELING THEORY IN DEVICE-INDEPENDENT COLOR SPACE HALFTONING”; U.S. Pat. No. 5,980,016 of Gregory D. Nelson et al., “SYSTEMS AND METHOD FOR DETERMINING PRESENCE OF INKS THAT ARE INVISIBLE TO SENSING DEVICES”; U.S. Pat. No. 5,796,414 of Otto Sievert et al., “SYSTEMS AND METHOD FOR ESTABLISHING POSITIONAL ACCURACY IN TWO DIMENSIONS BASED ON A SENSOR SCAN IN ONE DIMENSION”; U.S. Pat. No. 5,644,343 of Ross Allen, “METHOD AND APPARATUS FOR MEASURING THE TEMPERATURE OF DROPS EJECTED BY AN INK JET PRINTHEAD”; and U.S. Pat. No. 5,430,306 of Hanno Ix, Ph. D., “OPTOELECTRONIC DETECTOR WITH HIGH, UNIFORM SENSITIVITY AND LARGE FIELD OF VIEW, FOR THERMAL-INKJET INKDROPS”.
Also of interest in regard to malfunctioning-nozzle identification and compensation is U.S. Pat. No. 6,010,205 of Donald Billet, with Raster Graphics. That patent, however, is not incorporated by reference.
This invention relates to routine automatic calibration and recalibration of finished incremental-printer products, in the facilities of end-users. Such operation is to be distinguished from tests and measurements made in the course of research on or development of such printer products.
With this in mind, the invention relates generally to machines and procedures for incremental printing of text or graphics on printing media; and more particularly to a scanning machine and method that construct text or images from individual spots created on a printing medium, in a two-dimensional pixel array. Aspects of the invention include a test pattern, and methods and apparatus for printing, using, and analyzing a test pattern, to establish an optimum value for printing-medium advance between scans of the machine—or a series of print-medium advance values related to such an optimum value.
From the results the invention is able in some cases to optimize the image quality directly. In other cases the invention instead uses the results to identify weak or misdirected printing elements, and can exploit multipass printmode techniques to divert operation from those elements to others.
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