Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-11-28
2004-04-13
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S015000
Reexamination Certificate
active
06719402
ABSTRACT:
This application is based on Patent Application No. 2000-366294 filed Nov. 30, 2000 in Japan, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet printing apparatus and an ink jet printing method which eject inks of different colors from at least two print heads for recording, and more particularly to a method of reducing degradation of image quality due to bleeding of ink.
2. Description of the Related Art
Printing apparatus used as printing means for printing images and others in printers, copying machines and facsimiles, and those used as print output devices for combination electronic equipment and workstations, including computers and word processors, are all designed to record images on a recording material (hereinafter referred to also as a print medium), such as paper and plastic thin plate, according to image information (all output information including character information).
Such printing apparatus may be classed into an ink jet system, a wire dot printing system, a thermal printing system and a laser beam printing system according to the printing method. Of these systems, the printing apparatus of the ink jet system (hereinafter referred to as an ink jet printing apparatus) ejects ink from a printing means including a print head onto a print medium to perform printing and has a variety of advantages, such as a capability to easily increase resolution, a high printing speed, a low noise and a low cost compared with printing apparatus of other systems.
In recent years as the importance of color outputs such as color images grows, a number of color ink jet printing apparatus with high quality matching that of a silver halide photography have been developed.
Such an ink jet printing apparatus improves the printing speed by using a print head which has a plurality of print elements integrally arrayed therein with high degree of accumulation and also a plurality of ink nozzles and liquid paths formed therein with high degree of accumulation in a one-to-one relationship with each print element. To print a color image, a plurality of such print heads are provided one for each color ink to be ejected.
FIG. 9
is a schematic diagram showing a nozzle array in an example of the print head.
In
FIG. 9
reference number
101
represents a black print head with an array of 320 nozzles at a degree of accumulation of 600 nozzles per inch (600 dpi) to eject a black ink.
102
,
103
and
104
represent cyan, magenta and yellow ink print heads, respectively, each with 128 nozzles with a degree of accumulation of 600 nozzles per inch (600 dpi). Y indicates a direction in which the print paper is fed (sub-scan direction).
The black print head
101
uses all 320 nozzles in a monochrome print mode for printing a monochromatic image such as sentences and, in a color mode, uses 128 nozzles from the top of the drawing to print a color image such as a photographic image. The color print heads
102
,
103
,
104
are used only in the color mode using all 128 nozzles. The color nozzles for the color mode are shifted 128 nozzles in the paper feed direction from the black nozzles.
Now, the color mode operation will be explained.
FIG. 10
shows the construction of main components of the printing apparatus that prints on paper by using the print heads described above. In the figure,
201
represents ink jet cartridges (printing means). These comprise four color ink tanks containing black, cyan, magenta and yellow inks and four print heads
202
corresponding to these ink tanks.
Designated
203
is a paper feed roller (sub-scanning means) which, together with an auxiliary roller
204
, holds the print paper P and rotates in the direction of arrow to intermittently feed the print paper P in the Y direction. Denoted
205
are a pair of paper supply rollers which, like the rollers
203
and
204
, hold the print paper P as they rotate. The rotating speed of the paper supply rollers
205
is set lower than that of the paper feed roller
203
, generating a tension in the paper so that it is fed without slack.
Reference number
206
represents a carriage (main scanning means) that supports the four ink jet cartridges
201
and reciprocally moves (or scans) in the main scan direction X perpendicular to the paper feed direction Y. When the print heads
202
are not performing the printing operation or are subjected to the ejection recovery operation, the carriage
206
stands by at its home position h indicated by a dashed line.
The carriage
206
situated at its home position h, upon receiving a print start command, prints on the paper over a width of {fraction (128/600)} inches (about 5.42 mm) by using 128 nozzles of the print head
202
as it scans in the X direction. When the printing is finished up to the side end of the paper, the carriage returns to the home position h and again performs the scan in the X direction. After the first printing operation is finished and before the second printing starts, the paper feed roller
203
rotates in the direction of arrow to feed the paper a distance equal to {fraction (128/600)} inches in the Y direction. In the second and subsequent printing operations, the color print heads are also used.
At each scan of the carriage
206
, the printing over a width of {fraction (128/600)} inches using the print heads
202
and the paper feeding are repeated until one whole page is printed. Such a print mode is referred to as a one-pass print mode.
The one-pass print mode is explained in detail by referring to the drawings.
FIG. 11
is a schematic diagram showing the printing method in the one-pass print mode.
In
FIG. 11
, reference number
301
and
302
represent a black print head and a color print head. The color print heads
302
for cyan, magenta and yellow are all arranged in line in the sub-scan direction, so the print time difference between the black print head
301
and any of the color print heads is almost equal. That is, the time difference between each of the color print heads and the black print head in the first and second scans is one scan period T for all color print heads. Hence, in
FIG. 11
the color print heads are shown as one print head for simplicity.
Here, a so-called one-way printing (hereinafter refereed to also as an 1-pass printing) is employed in which the printing is done only when the carriage moves forward. Thus, one scan period means the time it takes for the carriage to make a forward movement for printing and a backward movement for returning. In a so-called two-way printing (hereinafter refereed to also as a 2-pass printing) in which the printing is done in both the forward and backward scans of the carriage, the one scan period means the time taken by the carriage to make a forward and a backward movement for printing and return to its original position. A print area A represents an area that is printed by the 128 nozzles arrayed in the Y direction. That is, the print area A is 128 nozzles wide in the Y direction.
In the first scan, the black print head
301
completes printing all print data that is to be printed in the print area A. After this, the print paper is fed in the Y direction a distance equal to the length of 128 nozzles.
Next, in the second scan, the color print head
302
completes printing all color print data that is to be printed in the print area A. When the first and second scans are finished, the printing of black and color print data in the print area A is completed.
As described above, in the 1-pass print mode, when the black print area and the color print area adjoin each other, the color printing is performed with a time difference T after the black printing has been done. Thus, the color ink may be printed adjacent to the black ink before the black ink is fixed on the paper. In that case, the black and color inks may bleed to mix together, degrading the quality of printed image.
Another print mode used in the ink jet printing apparatus is a multi-pass print mode. In this multi-pass print mode, the print
Kanda Hidehiko
Moriyama Jiro
Nakagawa Yoshinori
Canon Kabushiki Kaisha
Do An H.
Fitzpatrick ,Cella, Harper & Scinto
Meier Stephen D.
LandOfFree
Ink jet printing apparatus and ink jet printing method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink jet printing apparatus and ink jet printing method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink jet printing apparatus and ink jet printing method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3252330