Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-06-08
2002-12-10
Nghiem, Michael (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S029000, C347S085000
Reexamination Certificate
active
06491365
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming method and an apparatus for forming an image on a printing medium by ejecting a liquid from a liquid ejecting head. More particularly, the invention is suitable for application to an ink-jet printer mounting a full-line type ink-jet head, in which a plurality of ejection openings for liquid are arranged over the entire width of an image forming region of the printing medium.
2. Description of the Related Art
An ink-jet printer for forming a desired image by ejecting an ink droplet onto a paper, a cloth, a resin, a metal and the like, features non-contact recording with respect to a printing medium and thus is superior in low noise, high printing speed, capability of high resolution printing, easiness of color printing, and capability of down-sizing of the overall apparatus.
As one of such ink-jet printers, there has been known a printer shown in
FIG. 10
, in which a plurality of elongated so-called full-line type ink-jet heads, each having a plurality of ejection openings arrayed over the entire width of an image forming region of a printing medium, are arranged in a feeding direction of the printing medium.
Namely, the printer includes four ink cartridges
33
Y,
33
M,
33
C, and
33
B respectively storing a yellow ink, a magenta ink, a cyan ink, and a black ink (hereinafter referred to as ink cartridge
33
) and four ink-jet heads
21
Y,
21
M,
21
C and
21
B (hereinafter referred to as ink-jet head
22
) connected to respective ink cartridges
33
via ink supply tubes
32
, respectively.
The ink-jet heads
21
, each of which is switched power supply between ON and OFF for respective ones of not shown electrothermal transducers by a head driver
61
connected to a control unit
60
, are arranged with a predetermined interval along a feeding direction of an endless feeding belt
62
so as to face a platen
63
via the feeding belt
62
. By head moving means
64
for recovery process, which is controlled by the control unit
60
, the ink-jet heads
21
are moved up and down with respect to the platen
63
. On the side portion of each ink-jet head
21
, capping members
22
, for performing recovery process of the ink-jet heads
21
by performing preliminary ejection of old inks within not shown ink passages provided within the ink-jet heads
21
from the ejection openings in advance of printing operation with respect to a printing paper
65
, are arranged in a condition shifted by one-half pitch with respect to an arrangement interval of the ink-jet heads
21
. By moving means
66
, which is controlled by the control unit
60
, the capping members
22
are moved to positions immediately below the ink-jet heads
21
at recovery process positions so as to receive waste inks ejected from the ejection openings.
The feeding belt
62
feeding the printing paper
65
is wound around a driving roller
68
connected to a belt driving motor
67
. The driving direction of the feeding belt
62
is switched by a motor driver
69
connected to the control unit
60
. On the upstream side of the feeding belt
62
, an electrostatic charger
70
is provided for electrostaticly charging the feeding belt
62
for adhering the printing paper
65
on the feeding belt
62
. The electrostatic charger
70
is switched ON and OFF by a driver
71
connected to the control unit
60
. To a pair of paper feeding rollers
72
for supplying the printing paper
65
on the feeding belt
62
, a paper feeding motor
73
, for rotatingly driving the pair of paper feeding rollers
72
, is connected. The operation of paper feeding motor
73
is switched by a motor driver
74
connected to the control unit
60
.
Accordingly, in advance of the printing operation for the printing paper
65
, the ink-jet heads
21
are elevated to the recovery process position away from the platen
63
. Then, the capping member
22
is moved immediately below the ink-jet heads
21
. Then, after the recovery operation for the ink-jet heads
21
, the capping member
22
is returned to an initial position. Also, the ink-jet heads
21
are moved toward the platen up to the image forming position. Then, the electrostatic charger
70
is actuated while the feeding belt
62
is driven. Also, the printing paper
65
is mounted on the feeding belt
62
by the paper feeding roller
72
, and a desired color image is formed on the printing paper
65
by the ink-jet heads
21
.
In the full-line type ink-jet printer shown in
FIG. 10
, the ink-jet heads
21
are located on the upper side of the ink cartridges
33
. A problem of causing leakage of the ink through the ejection openings of the ink-jet heads
21
due to a liquid pressure of the ink stored in the cartridges
33
can be successfully prevented.
Because of the constructions set forth above, when the ink-jet heads
21
are elevated from the image forming position to the recovery process position, as illustrated in a sectional structure of the lower end portion of the ink-jet heads
21
in
FIG. 11
, an ink surface (ink meniscus) M of the ejection openings
40
is located at a position shown by a two dotted line at the image forming position, namely at an ejection opening surface
44
where the ejection openings
40
are formed, and whereas, at the recovery process position above the image forming position, a waterhead difference between the ink surface M and the ink cartridge
33
becomes large to cause recession of the ink surface M into the ink passage
58
, as shown by the solid line.
As a result, foreign matter W, such as dust and the like deposited in the vicinity of the ejection openings
40
can be sucked into the ink passage
58
to be held within the ink passage
58
even if the recovery process is performed. In such case, ejection failure can result to prevent formation of a good quality image.
Such drawback may be caused not only in the ink but also in treatment liquid for adjusting printing ability of the ink on and/or in the printing medium.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an image forming method which can successfully prevent the drawback of sucking foreign matter, such as dust or the like from the ejection openings into ink passages even when a liquid ejection head ejecting a liquid is elevated from an image forming position to a recovery process position.
Another object of the present invention is to provide an image forming apparatus which can implement the image forming method set forth above.
The first aspect of the present invention is an image forming method forming an image on a printing medium in an image forming position utilizing a liquid ejection head for forming the image on the printing medium by ejecting liquid in the image forming position, comprising:
a step of performing a recovery process at a recovery process position set on an upper side of the image forming position for recovering ejecting condition of liquid from the liquid ejecting head; and
a step of closing a liquid supply passage for supplying liquid to the liquid ejection head during movement of the liquid ejection head from the image forming position to the recovery process position.
The second aspect of the present invention is an apparatus for forming an image on a printing medium utilizing a liquid ejection head provided with an ejection opening for ejecting liquid, comprising:
a liquid supply passage connected to the liquid ejection head;
recovery process means for recovering ejecting condition of liquid from the liquid ejection head;
head moving means for moving the liquid ejection head between the recovery process position for performing recovery process of the liquid ejection head by the recovery process means and an image forming position for forming an image on the printing medium by the liquid ejection head; and
closing means for closing the liquid supply passage during movement of the liquid ejection head at least to the recovery process position by the head moving means.
According to the present invention, when the image is formed on the print
Canon Aptex
Fitzpatrick ,Cella, Harper & Scinto
Hsieh Shih-wen
Nghiem Michael
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