Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-03-08
2002-09-03
Nguyen, Lamson D. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S043000
Reexamination Certificate
active
06443554
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a technique that prints an image with a head assembly that is obtained by combining a plurality of nozzle units, from which ink droplets are ejected.
BACKGROUND ART
The printing apparatus that has a plurality of nozzles formed in a print head and causes ink droplets to be ejected from the respective nozzles so as to create ink dots on a printing medium and thereby complete a printed image has widely been used as an output device of various image-related equipment. The printing apparatus prints the image while repeatedly carrying out main scan and sub-scan of the print head as discussed below. This prior art technique carries out one pass of the main scan of the print head in a direction crossing an extending direction of a nozzle array to form plural arrays of ink dots (hereinafter referred to as raster lines). After a pass of the sub-scan in a direction crossing an extending direction of the raster lines, the technique carries out another pass of the main scan to form another plural raster lines at different positions. The repeated cycles of the main scan and the sub-scan of the print head form raster lines at all the possible positions on the printing medium, thereby completing a desired image on the printing medium.
In this printing apparatus, the greater number of nozzles formed in the print head effectively increases the number of raster lines formed by each pass of the main scan and thereby enhances the printing speed. The effect of the large-sized print head with the greater number of nozzles is especially significant in the case of printing on large sheets of paper like the A3 and A0 sizes, since a large number of raster lines should be formed in such large sheets of paper.
It is thought convenient to construct a head assembly by combining a plurality of nozzle units of conventionally used print heads, instead of newly manufacturing a large-sized integral print head. This method enables a head assembly of a desired size to be constructed by combining an appropriate number of nozzle units. Application of the manufacturing technique of the conventional print heads facilitates the manufacture of the head assembly, compared with the manufacture of the large-sized integral print head.
The respective nozzle units combined to construct the large-sized head assembly generally have a slight difference in ink ejection characteristics. Such variation may deteriorate the printing quality in the case of printing an image with the head assembly. Even a small error in assembling position of each nozzle unit causes the positions of all the dots created by the nozzle unit to be deviated uniformly by a fixed amount. The difference in error of the assembling position among the respective nozzle units may accordingly deteriorate the printing quality at positions corresponding to joints of adjoining nozzle units.
The object of the present invention is thus to provide a technique that prevents the printing quality from deteriorating at positions corresponding to joints of adjoining nozzle units in the case of printing an image with a large-sized print head obtained by combining a plurality of nozzle units.
DISCLOSURE OF THE INVENTION
At least part of the above and the other related objects is attained by a printing apparatus that causes ink droplets to be ejected from a nozzle array, which is formed by arranging a plurality of nozzles, so as to create ink dots on a printing medium and thereby print an image. The printing apparatus includes: a head assembly obtained by combining a plurality of nozzle units arranged in an extending direction of the nozzle array, that is, in a sub-scanning direction, where each nozzle unit has the plurality of nozzles; a raster formation unit that creates the ink dots while moving the head assembly in a main scanning direction, which crosses the sub-scanning direction, so as to form raster lines on the printing medium at intervals of a k raster lines space, where each raster line represents an array of dots; and a sub-scan unit that moves the head assembly in the sub-scanning direction, which crosses the main scanning direction, by a predetermined amount. The sub-scan unit carries out respective passes of sub-scan of the head assembly, in order to record all raster lines included in an effective area on the printing medium, each pass of the sub-scan causing a rear most nozzle included in each nozzle unit to be located at a specific position that is apart by at least k raster lines from a certain position where a rear most nozzle included in another nozzle unit is located prior to the pass of the sub-scan.
There is also a method corresponding to the printing apparatus of the above arrangement. The present invention is accordingly directed to a method of printing an image by causing ink droplets to be ejected from a nozzle array, which is formed by arranging a plurality of nozzles, to create ink dots on a printing medium while changing a relative position of the nozzle array to the printing medium. The method includes the steps of: creating ink dots while successively moving a head assembly in a direction that crosses an extending direction of the nozzle array, so as to form raster lines on the printing medium at intervals of a k raster lines space, where each raster line represents an array of dots and the head assembly is obtained by combining a plurality of nozzle units arranged in the extending direction of the nozzle array, each nozzle unit having the plurality of nozzles; and successively moving the head assembly in the extending direction of the nozzle array by a predetermined amount, so as to record all raster lines included in an effective area on the printing medium, each movement of the head assembly causing a rear most nozzle included in each nozzle unit to be located at a specific position that is apart by at least k raster lines from a certain position where a rear most nozzle included in another nozzle unit is located prior to the movement of the head assembly.
In the printing apparatus and the corresponding method of the present invention, the head assembly is subjected to each pass of the main scan that causes ink droplets to be ejected from the nozzle array, which is an alignment of the plurality of nozzle units, and thereby creates ink dots on the printing medium. This forms a plurality of raster lines at equal intervals of a k raster lines space on the printing medium. A next pass of the main scan is carried out after one pass of the sub-scan of the head assembly. The technique successively carries out the main scan and the sub-scan of the head assembly and completes a printed image on the printing medium. Here k is a natural number of not less than 1. Each pass of the sub-scan of the head assembly is carried out to cause a rear most nozzle included in each nozzle unit of the head assembly, that is, a nozzle at the opposite end in the sub-scanning direction, to be located at a specific position that is apart by at least k raster lines from a certain position where a rear most nozzle included in another nozzle unit is located prior to the pass of the sub-scan.
This arrangement causes any position printed by the joint of nozzle units in each pass of the main scan to be printed by a part of the nozzle unit other than the joint in another pass of the main scan. This effectively prevents any overlap of the printing positions corresponding to the joints of the nozzle units. Even if some difference in printing-related characteristic between the nozzle units slightly worsens the picture quality at the joint of the nozzle units, this arrangement effectively prevents the picture quality-deteriorating factors from being collectively accumulated in any specific part on a resulting printed image and thereby makes the deteriorating picture quality sufficiently inconspicuous. This arrangement further relieves the deteriorating picture quality at the joint in the course of printing and eventually ensures the good picture quality.
In order to clearly show the effects of the present invention, the following des
Nguyen Lamson D.
Seiko Epson Corporation
LandOfFree
Printing device, printing method, and recording medium does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Printing device, printing method, and recording medium, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Printing device, printing method, and recording medium will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2890808