JP2011140230A - Method for correcting image to be printed - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct an image to be printed by a printer. <P>SOLUTION: The printer has a fixed print head, and inkjet nozzles are arranged in a single line which intersects perpendicularly to the direction, wherein a print medium is moved through the fixed print head. The print head prints the image in a plurality of print lines on the print medium when the print medium passes along the print head. The method concerned includes a step for compensating the failure of the nozzle so as to correctly print an ink dot at a specific position of the print medium and recognizing the specific position on which the first nozzle fails to print the ink dot correctly according to the image, and a step for printing the ink dot at the position adjoining the recognized specific position and correcting the image even when the second nozzle adjoining the first nozzle is not required to print the ink dot according to the image. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to digital printing, and more particularly to printing using an apparatus that ejects ink onto a substrate to be printed. However, the present invention is not limited to the ink ejection device, but can be applied to a laser printer, an LED printer, and a digital copier.

  In an ink ejection device, a print head has an array of nozzles that selectively eject ink onto a substrate that moves relative to the print head. The printhead can be printed by scanning across the substrate and printing the horizontal width or, if the printhead is a full page width printhead, can pass along the length of the page It is. In the case of a scanning print head, when the nozzle is blocked, a plurality of horizontal blank lines are generated, and in the case of a page width print head, a single vertical blank line is generated. Such blank lines are undesirable because they degrade the print quality.

[Problems to be solved by the invention]
The present invention provides a method for improving the printing in an image so as to reduce or effectively eliminate the visual effects caused by one or more such occluded nozzles visible to an observer in normal use. To do. However, the present invention is applicable to other forms of printing where the element (whether passive or active) is used repeatedly to produce ink dots or the like on the substrate. The present invention can be applied to a laser type printer, an LED type printer, and a copier in which a defect is caused in a created image due to a defect in an image drum or a light source. The term “image” as used above and throughout the detailed description of the invention and the claims is to be interpreted in a broad sense and encompass any printed matter such as text, diagrams, and the like.

[Means for solving problems]
In one broad form, the present invention provides a method for modifying a digitally printed image by a printing device that compensates for the failure to accurately print ink at one or more specific locations. The method includes the step of identifying the one or more specific positions, and for at least one specific position, the print position of a dot intended for a specific position in the image with another image dot. Shifting to an unused shift position.

In another broad form, the present invention provides an array of elements that arranges a row of dots on a substrate, and moves the substrate relative to the array of elements in a direction substantially perpendicular to the array of dots. And a printer. The printer includes:
(1) Means for determining whether one or more of the elements do not operate correctly (2) Analyzing the printed image and activating the failed elements to determine when ink dots should be printed Control means to shift the dot position in the printed image so that the dot is printed by activation of one of the elements on both sides of the failed element and the printing is originally intended by the defective element The printed ink dots can be shifted to the horizontal side, the vertical side, or both. The ink is preferably shifted to a position immediately adjacent to the original position.

  The defective element preferably produces one or more defective lines in the printed image, and the ink is preferably shifted so that it is staggered relative to the sides of the one or more lines. It is preferred that the ink be shifted to the side only relative to the line, but if there are no positions available on the same row, then the vertical and horizontal sides and the vertical side along the line. It is possible to shift. The ink can be shifted to the front or back row relative to the original row position.

It is the schematic of the set of the nozzle of an inkjet print head. FIG. 2 is a schematic diagram of an array of ink dots formed by the print head of FIG. 1 when a defect correction operation is not used. FIG. 3 is a schematic diagram of the same array of ink dots as in FIG. 2 formed by the print head in FIG. 1 when using a defect correction operation. FIG. 6 is a second schematic diagram of an array of ink dots formed by the print head of FIG. 1 when no defect correction operation is used. FIG. 5 is a schematic view of the same array of ink dots as in FIG. 4 formed by the print head of FIG. 1 when using a defect correction operation.

BEST MODE FOR CARRYING OUT THE INVENTION

  The present invention will be more fully understood from the following non-limiting preferred embodiments and the description of the drawings.

  Referring to FIG. 1, the print head 10 has an array of inkjet nozzles 12 arranged in a row. For illustration purposes, only 14 nozzles are shown, but in practice there may be tens to thousands of nozzles in a row. The paper passes under the print head in a direction substantially perpendicular to the inkjet nozzle line, as indicated by arrow 14. The print head may be a fixed head or a moving head. As the paper passes under the print head, inkjet nozzles A-N selectively operate to place an array of ink dots on the paper. The array is a series of rows and columns, the spacing of which depends on the spacing of the inkjet nozzles and the minimum feed step, respectively. It is preferable that the horizontal and vertical intervals of the dots are the same, but it is not always necessary to realize them because the factors of the intervals are different. The printhead can be a hage-width printhead, or a smaller printhead that scans across the page and prints horizontally in order to place the head across the width of a series of prints. May be used.

For purposes of illustration, it is assumed that inkjet nozzles A - G and I - N operate correctly, but for some reason, inkjet nozzle H does not operate correctly or at all. Also assume that the printer diagnostic system, which would be well understood by those skilled in the art, has detected that the nozzles H do not function correctly. In most cases, the malfunctioning element will be partially or totally occluded, resulting in improper, i.e. no ink placed on the paper.

Referring to FIG. 2, a print portion made with the print head 10 without correcting the defects is schematically shown. Here, a blank line described with “ H ” corresponding to the inkjet nozzle H is shown. On the other hand, rows A to G and I to N are correctly and selectively printed. This causes one or more blank lines to appear in the print, depending on whether the print head 10 is a full page width print head or a scanning print head. White circles with numbers 16, 18, 20, and 22 correspond to ink droplets that should be printed in row H but not printed. In FIG. 3, the same image printed by the print head 10 with defect correction according to an operational embodiment of the present invention is shown.

As described above, the paper is fed through the print head in the direction of arrow 14 so that row 1 is printed first. On line H of the column 1, it should dots 16 are printed. Since nozzle H does not function, the control system determines whether adjacent nozzles G and I require ink dots. Because it does not require both ink dots, the control system selects the Dochi et al one of the rows G and I in a substantially random, place the dot in the appropriate line instead of the line H.

  Typically, the control system prints excess ink drops on alternate sides for defective nozzles. Thus, the first selected side is the reverse direction of the last printed side. It may be obvious that there is no previous data, such as immediately after a nozzle defect is detected or when the printer is re-initialized. In such a case, either the left or right row is selected at random.

Since rows G and I are “empty”, the system places a single dot at position G based on the above criteria.

In column 2, since there are no dots in row H , no extra dots are created.

In column 3, dot 18 is required in row H and rows G and I are again empty. Since the last printed surplus dot exists on row G (column 1), the surplus dot is printed on row I.

In the column 4 as well, the arrangement of the dots 20 in the row H is intended, but in this case, the dots need to be in both the rows G and I. Therefore, excess dots are not printed on row 4. However, in column 5, no dot is needed on row H , and rows G and I are empty. Since the last printed surplus dot exists on row I , column 5 of row G is selected, and the originally intended dot is printed on column 4 of row H.

Also in column 6, dot 22 is required in row H. In this case as well, rows G and I have already been used, and the surplus dots are carried over to column 7, which is the next column. Dot is not required in row H or G column 7, but is required by the line I. Recall that the dots 20 are arranged on the row G. According to the first criterion, dots 22 are arranged on row I. However, since this location is already required, thereby occurs surplus dots continuously on line G is, but the system is to place the dots on the line G.

5 and 6, are approximately Figure 2 and 3 two sets of prints requested number of dots than are shown. Similarly in this case, the nozzle H does not operate correctly. Also, column 1 is printed first, and dot 30 is requested on row H. Since only the row G is empty, the dots 30 are arranged on the row G. Even in columns 2 and 3, dots are required on row H , but row G cannot be used, so both dots 32 and 34 have a "need" to stagger the print side. , Arranged on row I.

Dots are not required on columns 4 or 6, but are required on columns 5 and 7. Similarly in this case, since only one column can be used, the dots 36a and 38 are arranged in the columns G and I , respectively.

  It will be appreciated that this technique can also be used in laser printers, LED printers, copiers and other types of digital printers where the placement of ink dots depends on the individual activation of the element or component. . For example, LEDs in LED printers can fail and defects can occur in the photoconductive drum of a laser printer. In both cases, shifting the dots can hide or reduce visual effects due to defects in the element or component.

DESCRIPTION OF SYMBOLS 10 ... Print head, 12 ... Inkjet nozzle, 14 ... Paper passing direction, 16, 18, 20, 22 ... Unprinted ink dot, 16, 18, 20, 22 ... Excess dot, 30, 32, 34, 36, 38 ... ink dots that are not printed, 30, 32, 34, 36, 38 ... surplus dots.

Claims (3)

In a method of modifying an image printed by a printing device having a fixed printhead, the printhead includes inkjet nozzles in a single line orthogonal to the direction in which the print medium is moved through the fixed printhead. Is disposed and compensates for the failure of one or more nozzles to accurately print ink dots at one or more specific locations on the print medium, the print head passing the print medium through the print head The method of printing the image on a plurality of print lines on the print medium when:
Recognizing a specific position where the first nozzle fails to accurately print ink dots according to the image;
Even when the second nozzle adjacent to the first nozzle does not need to print ink dots according to the image, the ink dot is printed at a position adjacent to the recognized specific position and the image is corrected. A step to do;
Said method.   The method of claim 1, wherein the adjacent location is on the same print line as the specific location.   The method according to claim 1, wherein the adjacent position is on a print line different from the specific position.

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