JP2004501007A - Anti-defect resistance of inkjet using huge ink droplets - Google Patents

Abstract

An inkjet device.
Kind Code: A1 An image portion that is not printed correctly due to a partial or total failure of the device is identified and, if possible, adjacent to reduce the visual effect of the failure to print in place. A printing method that adjusts the size of the ink dots in a column or row.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to digital printing, and more particularly, to printing using a device that ejects ink onto a non-printed material 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.
[0002]
[Prior art]
In an ink ejection device, a printhead has an array of nozzles that selectively ejects ink onto a non-printing material that moves relative to the printhead. The printhead can be printed by scanning across the non-printed material and printing the horizontal width, or can pass along the length of the page if the printhead is a full page width printhead It is. In the case of a scanning printhead, when a nozzle is blocked, a plurality of horizontal blank lines are generated, and in the case of a page width printhead, one vertical blank line is generated.
[0003]
[Problems to be solved by the invention]
The present invention is a method of improving a print in an image to reduce or effectively eliminate the visual effects caused by one or more such blocked nozzles that are visible to a viewer in normal use. I will provide a. However, the invention is applicable to other forms of printing in which the elements (passive or active) are used repeatedly to produce dots of ink or the like on non-prints. INDUSTRIAL APPLICABILITY The present invention is applicable to laser printers, LED printers, and copiers in which a defect in an image drum or a light source may repeatedly cause a defect in a created image. The term "image" used above and in the detailed description and claims of the invention is to be interpreted broadly and includes any printed matter, such as text, diagrams, and the like.
[0004]
[Means for Solving the Problems]
In one broad form, the present invention provides a method of partially modifying an image that is digitally printed by a printing device to compensate for defects that do not print ink dots exactly at specific locations. The method includes:
(1) identifying the particular one or more locations; (2) adjusting the dot size of at least one dot adjacent or adjacent to each particular location required by the image data. In a broad form, the present invention provides a method for controlling a row of activatable elements, which upon activation activates a row of dots on a non-printed material, in a direction substantially perpendicular to the row of dots and relative to the row of elements. Means for moving a printed material. The printer includes:
1) means for determining whether one or more of the above elements does not operate correctly; 2) analyzing the image or image data and identifying the dots of ink to be printed by activation of the incorrectly operating elements. Control means for identifying one or more locations and adjusting the size of the dots created by one or both of the elements on either side of the failed element.
[0005]
Incorrectly operating elements result in one or more defective lines in the printed image. Incorrectly operated elements typically do not produce ink or a sufficient amount of ink, creating blanks and blurred lines. To compensate for this, adjacent ink dots are larger than the dots required by the raw image data. Conversely, if the incorrectly operating element created a huge ink dot, the dot size of adjacent dots would be small.
[0006]
If a portion of the image requires an incorrectly operating element to place a continuous or substantially continuous row of dots, it is preferred that the size of all adjacent rows of dots be adjusted. If there are few locations on the row of elements that operate incorrectly that require ink, the size of the dots in adjacent rows may or may not be adjusted.
[0007]
The size of the dots in three or more adjacent rows may be adjusted. The size of dots in adjacent rows may only be adjusted if they are within a predetermined vertical or horizontal distance, or within one or more specific locations. For example, not only the size of the dots in the columns on both sides of the defective row may be adjusted, but also the size of the dots in the 2-3 columns above and / or below each location.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be more fully understood from the following description of non-limiting preferred embodiments and figures.
[0009]
Referring to FIG. 1, a printhead 10 has an array of inkjet nozzles 12 arranged in a single line. For illustrative purposes, only 14 nozzles are shown, but in practice there may be tens to thousands of nozzles in a single line. The paper passes under the printhead in a direction substantially perpendicular to the line of inkjet nozzles, as indicated by arrow 14. The printhead may be a fixed head or a moving head. As the paper passes beneath the printhead, the inkjet nozzles AN 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 be the same, but they need not necessarily be realized because the factors of the respective intervals are different. The printhead may be a hedge-width printhead or a smaller printhead that scans across the page to position the head across the width of a series of prints. .
[0010]
For purposes of illustration, it is assumed that inkjets ag and in operate correctly, but for some reason inkjet h does not operate correctly or does not operate at all. It is also assumed that the printer diagnostic system, as will be understood by those skilled in the art, has also detected that nozzle h is not functioning correctly. In most cases, a malfunctioning element will partially or totally occlude, resulting in improper or no ink placement on the paper.
[0011]
Referring to FIG. 2, a print portion made with the printhead 10 without correcting for defects is schematically illustrated. Here, a blank line described by “h” corresponding to the inkjet h is shown. On the other hand, rows ag and in are correctly and selectively printed. This causes one or more blank lines to appear in the print, depending on whether the printhead 10 is a full page width printhead or a scanning printhead. The unshaded circles with the numbers 16, 18, 20, 22 correspond to ink drops that should be printed in row h but are not printed. FIG. 3 shows the same image printed by the printhead 10 with defect correction, according to an operational embodiment of the present invention.
[0012]
Referring to FIG. 3, the ink drops in rows g and i are larger than normal ink drops, as described below. This reduces the amount of white space between dots and between rows g and i. This has the effect of making it difficult for the user to visually recognize the unprinted line h. When printing on A4 or letter size paper which is usually read at a distance of 20 cm to 30 cm or the like, the effect is exhibited at about 1600 dpi or more.
[0013]
In the print of FIG. 3, only the size of the dot intended to be printed on rows g and i has been increased, but the image on both sides of the defective row, regardless of the normal or adjusted size, It is within the scope of the present invention to be able to print excess ink dots where the data does not require dots. As can be seen from FIG. 3, the dots exist only in about 50% of the positions where the dots can be arranged in the image, and even if an oversized dot is used, a white space still stands out. This white space can be reduced by printing the dots in blank areas, reducing and / or eliminating the visual effect of unprinted rows.
[0014]
Preferably, the area of each adjusted size dot is about 50% larger, but this can be varied as needed. Two rows of giant dots may be slightly infested on the same row. However, the size of the dots may be reduced so that the two rows of dots do not touch each other, or may be increased such that adjacent dots overlap.
[0015]
If ink dots are needed frequently in row h, the giant ink drops are placed continuously at nozzles g and i. It is understood that if the ink dots are placed less frequently, the drop size of the ink in rows g and i will be larger only in the area adjacent to or close to the area of the ink drop to be placed in row h. Like. These giant drops of ink may reach columns in row h where ink placement is not intended. If ink placement is not intended over long distances in row h, then no giant drops are preferably created in rows g and i.
[0016]
With reference to FIGS. 4 and 5, there are shown second schematic print diagrams with and without defect correction, respectively. As can be seen in FIG. 4, in columns 1, 2, 3, 5, 7 of row h, indicated by unshaded circles 30, 32, 34, 36, 38, dots of ink are required but not printed . In FIG. 5, the dots on rows g and i on the columns above and below the non-printed dots 30, 32, 34, 36, 38 are enlarged. Because there are more dots in these rows as compared to the prints of FIGS. 2 and 3, the enlarged dots overlap more closely, reducing a significant proportion of the white space. Again, if desired, normal or giant sized dots can be printed in blank locations such as columns 1, 5 of row g and columns 2, 3, 7, etc. of row i.
[0017]
In the case of an ink ejection type printer, enlargement of the dot size is achieved by increasing the amount of ejected ink. In the case of a thermal ink ejection device, this can be achieved by increasing the heating current pulse width. In the case of a piezoelectric ink ejection device, this can be achieved by increasing the drive voltage, increasing the current, and causing greater distortion, or increasing the pulse width. Similarly, in the case of the mechanism type ink ejection element, it can be achieved by increasing the pulse width and / or increasing the driving voltage or increasing the current. The present invention can also be applied to situations where individual elements produce large amounts of ink and can be adjusted to reduce the dot size of ink dots created by adjacent elements.
[0018]
It will also be appreciated that the technology can be used with laser printers, LED printers, copiers, and other types of digital printers, where the placement of the ink dots is dependent on the individual activation of elements or components. For example, an LED in an LED printer may fail or a defect may occur in the photoconductive imaging drum of a laser printer. In both cases, the size of adjacent dots can be adjusted to hide or reduce the visual effect of defects in elements or components.
[0019]
In the case of laser or LED printers, the dot size can be changed by changing the intensity and / or the total amount of light applied to the corresponding portion of the optoelectronic image drum.
[Brief description of the drawings]
FIG.
FIG. 2 is a schematic view of a set of nozzles of an inkjet print head.
FIG. 2
FIG. 2 is a schematic diagram of an array of ink dots formed by the print head of FIG. 1 when no defect correction operation is used.
FIG. 3
FIG. 3 is a schematic diagram of the same array of ink dots as FIG. 2 formed by the print head of FIG. 1 when using a defect correction operation.
FIG. 4
FIG. 2 is a second schematic diagram of an array of ink dots formed by the printhead of FIG. 1 without a defect correction operation.
FIG. 5
FIG. 5 is a schematic diagram of the same array of ink dots as FIG. 4 formed by the print head of FIG. 1 when using a defect correction operation.
[Explanation of symbols]
10 print head, 12 ink jet nozzle, 14 paper passage direction, 16, 18, 20, 22 ink dots that are not printed, 30, 32, 34, 36, 38 ink dots that require printing but are not printed.

Claims (15)

A method of partially modifying an image that is digitally printed by a printing device to compensate for defects that do not print ink dots accurately at a particular location, the method comprising: (1) providing the one or more locations. Identifying
(2) adjusting the dot size of at least one dot adjacent to or adjacent to each of the specific positions required by image data;
A method that includes The method of claim 1, wherein the adjusted one or more dots increase in dot size if no dots or microdots are printed at each of the specific locations. The method of claim 1, wherein a dot size of the adjusted dot is reduced when a huge ink drop is printed at each of the specific locations. The method of claim 1, wherein the size of the dots located horizontally and vertically away from the respective positions is adjusted. The method of claim 1, wherein the selected adjusted giant dot contacts or overlaps an adjacent dot. The method of claim 1, wherein the selected adjusted size dots do not touch or overlap adjacent dots. A row of activatable elements for arranging rows of dots on the non-print when activated, and means for moving the non-print relative to the rows of elements in a direction substantially perpendicular to the rows of dots. Means for determining whether one or more of said elements are not operating correctly, and analyzing the image or image data to determine the dots of ink to be printed by activation of the incorrectly operating elements. Control means for identifying a particular location or locations and adjusting the size of the dots created by one or both sides of the failed element. The printer according to claim 7, wherein the control unit adjusts the size of the dots arranged on the same row as the specific position by using one or both elements on both sides of the failed element. The control means adjusts the size of the dots placed by one or both elements on either side of the failed element in at least one row adjacent or adjacent to each particular location row. The printer according to claim 7. If the activation of the incorrectly operating element does not create a dot or creates a small dot, the activation of one or both elements adjacent to the incorrectly operating element The printer according to claim 7, wherein the size of the dot created by the method is increased. The printer of claim 7, wherein the element is a thermomechanical ink ejection element and the control system activates the ejection element for a long time, provides a large drive signal, or both. The printer according to claim 7, wherein the element is a light emitting element, and a total light emission amount of the light emitting element is adjusted. The printer of claim 7, wherein the elements are part of a photoconductive imaging drum, and wherein the adjusted dot size is adjusted by changing the amount of light to which each of the elements is exposed. The printer of claim 7, wherein at least some adjusted giant dots contact or overlap adjacent dots. 8. The printer of claim 7, wherein the adjusted size dots do not touch or overlap adjacent dots.