JP2001146004A - Printing method of ink-jet printing head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a printing quality deterioration because of broken dots in a banding method of an ink-jet printing head of a double shift type. SOLUTION: According to the printing method, a driving frequency of an adjacent nozzle to a failing nozzle is increased to print dots which are to be printed by the failing nozzle. The printing is thus complemented not to generate broken dots.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of printing on a recording medium of an ink jet head which ejects ink droplets by some energy means, and more particularly to a complementary printing method when a print nozzle failure occurs in a banding printing method. It is.

[0002]

2. Description of the Related Art FIG. 1 shows an ink jet head (hereinafter referred to as a jet pack) composed of 32 nozzles in one row.
Shown is a printhead mounted in two rows and having a total of 384 nozzles.

[0003] The 32 nozzles (nozzles arranged vertically in the figure) on one jet pack are odd nozzles (1, 1).
, 31) and even nozzles (2, 4,
... 32) are shifted in the main scanning direction (left and right directions in the figure) by １ ／ dot. Therefore, after the ink ejection from the odd nozzles, 1
Since the even nozzles are ejected after the print head moves in the main scanning direction for / 2 dots, the number of simultaneous ejections is reduced to を to improve the crosstalk characteristics.

On the other hand, in a large-sized ink jet type print head having 300 or more nozzles, defective nozzles that cannot eject ink due to clogging of ink or defective characteristics of a piezoelectric element for driving nozzles are present. The probability of occurrence is greater. In the case of a large-sized ink jet print head, when one ejection defective nozzle is generated due to clogging of ink or defective characteristics of the nozzle driving piezoelectric element, a white streak appears on a horizontal line as shown in FIG. It becomes noticeable because it becomes.

Therefore, in the related art, by performing the above-described scan banding processing, white spots in the print result due to the occurrence of defective ejection nozzles are made inconspicuous.

Here, the scan banding process described above will be described in more detail with reference to FIG.

FIG. 2 shows an actual print image by a 2-scan banding printing method which is a method of improving print quality.
This shows printing for the first scan and printing for the second scan.

Actually, it is possible to print 384 dots in one scan using the ink jet head of FIG. 1, but in the banding printing method, as shown in FIG. A checkerboard pattern is printed in each scan in the main scanning direction, and the sub-scanning direction between the first and second scans (vertical direction in FIG. 1)
Is carried out at 192 dots, which is 1/2 of 384 dots, and printing is performed in the first scan and the second scan so as to complement the vacant portions.

Specifically, when observing the two-scan banding printing method shown in FIG. 2, the first-scan printing is performed in the sub-scanning direction in a total of 19 dots from 193 dots to 384 dots.
Two dots are printed, and similarly, the second scan is printed in the sub-scanning direction in a total of 192 dots from the first dot to the 192th dot.
Dots are printed, and a total of 384 dots are printed.

[0010] Looking at the actual first line printed by the banding method, the first scan is next to the 17th nozzle (r1-17) in the first row of the jet pack, and the second scan is the jet pack. Printing is performed by the first nozzle (r1-1) in the first row. That is, the odd nozzles of the first scan (the 17th nozzle)
Next to the odd nozzle of the second scan (first nozzle)
This results in printing.

The print result of the 13th line is next to the print of the 18th nozzle (r1-18) in the first row of the jet pack in the first scan, and the second print in the first row of the jet pack in the second scan. No. (r1-2). This results in printing the even nozzles next to the even nozzles.

Therefore, if the two-scan banding process shown in FIG. 4 is used, even if one defective nozzle is generated, the printing rate of the defective nozzle in the main scanning direction of the print head is reduced to half. However, as shown in FIG. 5, white spots in the print result can be made inconspicuous.

[0013]

As described above, in the related art, by performing the scan banding process, white spots in the print result due to the occurrence of defective nozzles are made inconspicuous. However, the printing method using scan banding merely makes the missing dots inconspicuous, and there is a problem in that print data is lost due to missing dots.

That is, as shown in FIG. 5, although white spots in the print result become inconspicuous, dot spots (every other in FIG. 5) occur, and the fundamental problem has not been solved. It is.

[0015]

According to the printing method of the present invention, a dot to be printed by a defective nozzle is printed by another nozzle. By performing printing instead, printing without missing dots can be performed, and a decrease in print quality can be prevented.

That is, in order to solve the above problems, in the present invention, dots printed by the second scan of the ink jet print head are interposed between dots printed by the first scan of the ink jet print head. In the printing method of an ink jet print head which performs complementary printing so as to fill in, when a jet defective nozzle is generated in the ink jet print head, the driving frequency of the nozzle for printing a dot adjacent to the dot to be printed by the defective jet nozzle is set to 2 In this case, the printing was performed so as to prevent the occurrence of white spots due to the ejection failure nozzle.

The defective ejection nozzle is visually identified as a defective ejection nozzle which cannot eject ink by printing an arbitrary test pattern, and is detected by setting and inputting the defective ejection nozzle to a control device in advance. ,
An arbitrary test pattern may be printed and scanned, and the ejection failure nozzle that cannot eject the ink may be detected in advance by automatically identifying it.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

The structure of the print head is the same as that of the prior art, and 12 rows of ink jet heads (hereinafter, referred to as jet packs) each having 32 nozzles in one row are mounted.
It has 84 nozzles.

In the 32 nozzles on one jet pack, the odd-numbered nozzles (1, 3, 5,... 31) are equal to the even-numbered nozzles (2, 4, 6,... A two-shift nozzle array that is shifted by two dots in the main scanning direction (the horizontal direction in the drawing) is employed.

As described in the prior art, a checkerboard pattern is printed in each scan in the main scanning direction of the ink jet head, and the sub-scanning direction between the first scan and the second scan (the vertical direction in FIG. 1). 3) paper transport amount
192 dots, which is 1/2 of 84 dots, are printed, and printing is performed in the first scan and the second scan so as to complement the vacant portions.

In the printing method according to the present invention, as shown in FIG. 5, defective ejection nozzles which cannot eject ink due to clogging of the nozzles of the print head or defective characteristics of the nozzle driving piezoelectric element. Occurs,
As shown in FIG. 6, when printing is performed while moving the print head in the main scanning direction, the driving frequency of the nozzle that prints the dot adjacent to the dot where the defective dot is to be printed is doubled, and the white spot due to the defective nozzle is removed. Perform complementary printing so that it does not occur.

For example, when the nozzle (r6-17) in the first scan is an ejection failure nozzle in the two-scan banding printing method, the nozzle (r6-1) is driven in the second scan. Double the frequency. As a result, it is possible to prevent a decrease in print quality due to missing dots.

In the present invention, since the driving frequency is doubled only for the nozzles that print the dots adjacent to the dots to be printed by the defective ejection nozzle, the time required for the entire printing is longer than the printing time when all the nozzles are normal. It will not be long.

Next, a method of detecting an ejection failure nozzle will be described.

As a first method, there is a method in which a nozzle that cannot eject ink is visually identified from the result of the test pattern printing, and the nozzle number is set and input to the printer. The ink jet printer according to the present invention performs printing so that the misfiring nozzles set and input are complemented by other nozzles.

As another method of the second method of detecting a defective nozzle, there is a method of scanning a test pattern printing result and automatically identifying a nozzle that cannot discharge ink.

[0028]

As described above, according to the present invention,
In the case of an ink jet printer, when a nozzle that cannot eject ink occurs due to clogging of the nozzle of the print head or defective characteristics of the piezoelectric element for driving the nozzle, only the drive frequency of the specific normal nozzle is increased by n times. By performing complementary printing of defective nozzles, printing without missing dots becomes possible. Further, since only the drive frequency of the specific nozzle is changed, there is an advantage that the time required for printing does not need to be the same as when all the nozzles are normal.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a nozzle arrangement of a print head.

FIG. 2 is an explanatory diagram showing a two-scan banding printing method.

FIG. 3 is an explanatory diagram showing a printing result in a case where a missing dot occurs due to an ejection failure nozzle.

FIG. 4 is an explanatory diagram showing a print pattern according to a two-scan banding printing method.

FIG. 5 is an explanatory diagram showing a print pattern obtained by a conventional dot missing countermeasure method.

FIG. 6 is an explanatory diagram showing a printing pattern according to the printing method of the present invention.

[Explanation of symbols]

 1 is a printing dot, 2 is a jet pack.

Claims (3)

[Claims] An ink jet print head which performs complementary printing by filling dots printed by a second scan of the ink jet print head between dots printed by a first scan of the ink jet print head. In the printing method, when an ejection failure nozzle occurs in the inkjet print head, the drive frequency of the nozzle that prints a dot adjacent to the dot to be printed by the ejection failure nozzle is doubled to cause the ejection failure nozzle. A printing method for an ink jet print head, wherein printing is performed so that white spots are not generated. 2. A method for printing an ink jet print head according to claim 1, wherein said defective ejection nozzle visually identifies a defective ejection nozzle which cannot eject ink by printing an arbitrary test pattern, and preliminarily determines a defective ejection nozzle. A printing method for an inkjet print head, wherein the detection is performed by setting and inputting a nozzle to a control device. 3. The method for printing an ink jet print head according to claim 1, wherein said defective jet nozzle prints and scans an arbitrary test pattern and automatically identifies in advance a defective jet nozzle which cannot discharge ink. A method for printing an ink jet print head.