Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-03-27
2003-01-21
Barlow, John (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S029000
Reexamination Certificate
active
06508533
ABSTRACT:
This application is based on Patent application Ser. No. 2000-89654 filed Mar. 28, 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 a recovery processing method of an ejection port. More particularly, the invention relates to an ink-jet printing apparatus and a recovery processing method of an ejection port having a function for recovering or maintaining good ink ejection performance of a printing head.
2. Description of the Related Art
Associated with the proliferation of information processing equipment, printing apparatuses as peripheral equipment have also proliferated. Particularly, an ink-jet printing apparatus,which performs printing by ejecting ink droplets from a plurality of ejection openings provided in a printing head toward a printing medium, has rapidly proliferated because color printing can be performed easily. Furthermore, associated with a demand for down-sizing, there has been proposed a serial type ink-jet printing apparatus, which alternately repeats a printing operation of moving the printing head in a predetermined direction and ejecting ink droplets during movement of the printing head and a paper feeding operation for feeding the printing medium by a predetermined amount in a direction perpendicular to the motion direction of the printing head.
In such ink-jet printing apparatus, the printing head is frequently mounted on a carriage which can scan in a predetermined direction. In a case of full-color printing, each of the printing heads for respective colors of yellow, magenta, cyan and black is constructed by integrating an ejection opening array and an ink tank. Also, among the printing heads, there are some printing heads, in which only the ink tank is detachable.
On the other hand, as a color image can be easily processed by information processing equipment, there has been an increasing demand for an ink-jet printing apparatus that can readily print those images in full-color printing, with enhanced image quality. To meet the demand, there has been proposed an ink-jet printing apparatus in which high image quality is realized by printing multi-gradation levels of density using the following method.
For example, concerning magenta and cyan, two kinds of inks having mutually different densities, namely, high density ink and low density ink, are provided for dividing ink densities of image data into a greater number of gradation levels for performing printing with such high and low density inks. In the alternative, by switching the ink ejection amount to be ejected from the printing head using only one kind of ink for each color, depending upon the density of the image data, to perform printing with different sizes of dots on the printing medium can realize high gradation levels and high image quality.
Particularly, the method for increasing gradation levels by forming different sizes of dots on the printing medium by switching ink ejection amounts can restrict the number of ink tanks to be loaded. Therefore, such method is effective for down-sizing of ink tanks and down-sizing of the ink-jet printing apparatus.
The printing head switching the ink ejection amount has been disclosed in Japanese Patent Application Laid-open No. 9-254413(1997) and Japanese Patent Application Laid-Open No. 9-48125(1997). In the above-identified publications, it has been proposed to differentiate ejection amounts by arranging a plurality of rows of ejection openings on an ink ejection face and differentiating sizes of ejection openings per row of the ejection openings.
By performing a printing operation many times or by leaving the printing head inoperative for a long period, it is possible to cause variations in ejection amount and/or ejecting direction from the printing head nozzles due to deposition of dust and dirt around the ejection opening or plugging with ink of increased density. In the alternative, ink may be dried to make ejection unstable upon initiation of printing.
In order to prevent drying of ink or ejection failure, the ink-jet printing apparatus is provided with a cap for covering the ejection opening face while the printing head is not used, or is provided with means for performing preparatory ejection at a predetermined position out of the printing region. For example, in an ink-jet printing apparatus disclosed in Japanese Patent Application Laid-open No. 10-100451(1998), a cap covering a plurality of ejection openings is provided.
On the other hand, in the case of the printing head, in which only the ink tank is detachable, when the old ink tank is removed, air may penetrate into an ink passage connecting the ink tank and the ejection opening, or air may penetrate around the ejection opening. Therefore, when the ink tank is exchanged with new ink tank, re-filling of the ink becomes necessary up to around the ejection opening. Therefore, upon exchanging the ink tank, the ejection opening face is covered with the cap to perform suction of the ink by a suction means with driving a pump.
Such recovery operation by the preparatory ejection means, suction means and so on are performed during a printing operation or a non-printing operation, or upon exchanging of the ink tank or the like.
FIGS. 8A and 8B
are sections showing a printing head portion and recovery unit portion of the conventional ink-jet printing apparatus.
As shown in
FIG. 8A
, a printing head
83
is mounted on a head carriage frame
83
a
movably arranged on a pair of upper and lower guide members
82
. The printing head
83
is provided with two ejection opening portions
83
b
and
83
c
projecting downwardly from the lower surface of the head carriage frame
83
a, namely from a surface opposing the printing medium feeding passage, a black ink tank
83
d
and a color ink tank
83
e
arranged detachably on the head carriage frame
83
a.
The ejection opening portions
83
b
and
83
c
are formed with a plurality of ejection openings, respectively. The ejection opening portion
83
b
ejects black ink supplied from the black ink tank
83
d
and the ejection opening portion
83
c
ejects three kinds of inks of cyan, magenta and yellow supplied from the color ink tank
83
e.
It should be noted that the black ink ejection openings
83
f
, the yellow ink ejection openings
83
g
, the magenta ink ejection openings
83
h
and the cyan ink ejection openings
83
f
are provided in plural. However, for the purpose of illustration, only one ejection opening is illustrated.
The ink-jet printing apparatus feeds a printing medium by means of a not shown printing medium feeding member, reciprocally scans the printing head and ejects ink droplets from respective ejection openings to form a desired image on the printing medium.
As shown in
FIG. 8B
, a recovery unit
810
for providing recovery process for the printing head
83
is provided. To the recovery unit
810
, caps
89
b
and
89
c
for covering the ejection openings
83
b
and
83
c
are provided. The caps
89
b
and
89
c
are connected to not shown pumps. The recovery unit
810
moves up and down to cover the ejection openings
83
b
and
83
c
with the caps
89
b
and
89
c
and performs suction recovery by the pumps.
A plurality of ejection openings are arranged on the ejection opening face of the printing head. Among the various ink-jet printing apparatuses, some of the ink-jet printing apparatuses have ejection openings that are not uniform size and rather differentiate per row of ejection openings to permit printing of an image at higher resolution. When a plurality of kinds of ejection openings of different shapes are present, the conventional ink-jet printing apparatus is provided with the caps in a number corresponding to shapes and kinds of the ejection openings, which requires a large space and hinders down-sizing of the overall apparatus. On the other hand, when an attempt is made to perform suction recovery for all the ejection openings with one cap, fluctuations in suction may result d
Inamoto Tadayoshi
Kimura Isao
Kudo Kiyomitsu
Shimoda Junji
Suzuki Tooru
Barlow John
Hsieh Shih-Wen
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