Technique for improving printing quality

Details Technique for improving printing quality Technique for improving printing quality

1998-12-21

2001-12-25

Barlow, John (Department: 2853)

Incremental printing of symbolic information

Ink jet

Controller

Reexamination Certificate

active

06332662

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a method for improving printing quality, more particularly, to a method for improving printing quality by printing through functioning nozzles, and reprinting over areas of non-functioning nozzles when non-functioning nozzles are present. The detection of nonfunctioning nozzles is accomplished by printing and scanning a piece of printed material.
DISCUSSION OF RELATED ART
Generally, an inkjet printer prints by jetting ink on paper through a number of nozzles by activating a number of electrical signals being applied to a jetting part of an ink head. However, alien substances may be inserted into any nozzle among nozzles jetting ink or a certain nozzle may not be continuously utilized. In those cases, any nozzle among the nozzles can be stopped or an electrical signal needed for jetting ink cannot be applied to a certain nozzle. As a result, malfunctioning nozzles, through which ink cannot be jetted in printing, may be formed. In earlier techniques, when an inkjet printer has malfunctioning nozzles, the ink head cannot jet ink through the malfunctioning nozzles. Accordingly, white lines formed on printing paper in a horizontal direction, and so the printing quality falls off.
SUMMARY OF THE INVENTION
Accordingly, in order to overcome such drawbacks in the earlier art, it is an object of the present invention to provide a method for improving printing quality by printing over these white lines using functioning nozzles. A scanner is used to detect the presence and location of any non-functioning nozzles so that the functioning nozzles can make-up for the non-functioning nozzles.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided a printing quality improving method comprising the steps of: inputting a printing order; detecting the presence and absence of malfunctioning nozzles among the nozzles of the jetting part in the inputting step and a position and number of malfunctioning nozzles in case malfunctioning nozzles are present; printing firstly as much as a width of a printing band having a reference line distance set by a line feed value in case of the absence of a malfunctioning nozzle in the detecting step; printing secondly a compensation letter line of one line for each of two lines by moving a normal nozzle to two malfunctioning nozzle positions of each two neighboring lines, after printing with a first printing band, which has a smaller first line distance than the reference line distance, in case of the presence of a single malfunctioning nozzle in the detecting step; and printing thirdly as much as a width of the printing band having the line distance by positioning a normal nozzle at a position of detected malfunctioning nozzles for every line having the reference line distance, printing as much as the width of the reference printing band having the reference line distance for every line in case of the presence of two or more malfunctioning nozzles in the detecting step.
Further, the detecting step comprises the steps of: printing a test printing pattern for detecting the presence or absence of malfunctioning nozzles; reading the printing pattern printed in the test printing step with a scanner; comparing the data read in the reading step with the printing data in the test printing step; and detecting the number and position of malfunctioning nozzles in the case malfunctioning nozzles are present, comparing whether the read data are accorded with the printed data in the comparing step.
Furthermore, the first printing band subtracts 2 from the number of nozzles.


REFERENCES:
patent: 6045210 (2000-04-01), Suzuki et al.
patent: 0783973 (1997-07-01), None
patent: 60104335 (1985-08-01), None

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