Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-08-03
2003-04-08
Hsieh, Shih-Wen (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S029000
Reexamination Certificate
active
06543876
ABSTRACT:
This application is based on Patent Application No. 10-219449 (1998) filed Aug. 3, 1998 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 ejection recovery system and an ejection recovery method for a liquid ejection head, such as an ink-jet printing head or the like, to be mounted on an ink-jet printer, a plotter and so on, for performing printing by ejecting liquid, such as ink or the like, on a printing medium.
2. Description of the Related Art
Conventionally, as a printing system performing printing on a printing medium, such as paper, cloth, a plastic sheet, an OHP sheet or the like (hereinafter simply referred to as printing paper), there have been know various printing systems, such as a wire-dot system, a thermal printing system, a heat transfer system, an ink-jet system and so on. Among these systems, a printing apparatus employing the ink-jet system (hereinafter referred to an ink-jet printing apparatus) has been used and commercialized as output means of an information processing system, such as a printer as a copy terminal, or a handy type printer or a portable printer which can be connected to a personal computer, a host computer, a disk drive device, a video device or the like.
In the printing head to be employed in the above-mentioned ink-jet printing apparatus, energy generation elements for generating energy for ejecting ink from ejection openings are provided. As the energy generation element, there are one using an electromechanical transducer, such as a piezoelectric element, one generating heat by irradiating an electromagnetic wave, such as a laser for ejecting an ink droplet by action of the generated heat, one heating liquid by an electrothermal transducer having a heating resistor for ejecting the ink droplet, or so on.
On the other hand, for an ink-jet printing apparatus, outputting of a color image has been required for advancement of softwares and a computer in the recent year. Adapting to such situation, the ink-jet printing head is also adapted for color printing. Currently, a multi-color head has been typically realized by combining a plurality of single color heads. Also, through certain head manufacturing process, a multiple color head is present.
In addition to colorizing, higher printing density in outputting of an image has been demanded. By densification of printing density in the ink-jet system or using different ink densities, formation of higher density and higher quality of image is attempted to realize.
Then, in order to form a high density and high quality image, it has been attempted for further densification of arrangement pitch of ink ejection openings and for down-sizing of ink droplets to be ejected from the ink ejection openings by making an opening area of each ink ejection opening much smaller.
On the other hand, in the case where the multi-color head is formed by combining single color heads set out as one means for adaptation for colorizing, down-sizing of the single color head is inherent. As a result, an ink chamber formed within the head is inherently down-sized.
In the background set forth above, the entire head including the ink ejection openings and the ink chamber is inclined to be down-sized. A pre-shipment step after production of the head, an ink filling-up operation or recovery operation to the ink chamber and ink passages of the head to be mounted on an ink-jet printer or an ink-jet plotter has been performed by covering overall an ink ejection opening forming surface, with a cap formed of flexible material, and introducing vacuum within the cap for sucking the ink.
Here, a recovery cap and a recovery operation to be employed for the conventional ink-jet printing head will be explained.
FIGS. 9A and 9B
show recovery cap C to be used for recovery operation of the conventional ink-jet printing head, wherein
FIG. 9A
is a plan view of the recovery cap C and
FIG. 9B
is a section taken along line IXB—IXB of FIG.
9
A. The recovery cap C is generally constructed with an substantially plate-like cap guide
30
, rubber caps
31
a
and
31
b
respectively fitted in two recessed portions
30
a
and
30
b
of the cap guide
30
. The rubber caps
31
a
and
31
b
are respectively formed with suction holes
32
a
and
32
b
at substantially central portions. The suction holes
32
a
and
32
b
are generally formed with hole portions
30
c
and
30
d
respectively formed in the recessed portion
30
a
(not shown) of the cap guide
30
and in central bottom portion of the recessed portion
30
b
, and hole portions
31
c
and
31
d
communicated with the hole portions
30
c
and
30
d
and respectively formed in the central bottom portions of the rubber caps
31
a
and
31
b
. The rubber caps
31
a
and
31
b
are formed of a rubbery elastic material, such as a silicone rubber or a butyl rubber. Respective projection contours E of the rubber caps
31
a
and
31
b
are formed projecting from plain of the cap guide
30
. Therefore, as shown in
FIG. 10
, when the rubber caps
31
a
and
31
b
abut on the ink ejection opening forming surface, a space defined therebetween can be a sealed space by elastic deformation of the projection contours E. The sealed space is sucked by a suction pump (not shown) via a tube
40
connected to the suction holes
32
a
and
32
b
. Sucked ink is discharged to a waste ink holder (not shown).
A relationship between the conventional ink-jet printing head and the recovery cap is downwardly oriented the ink ejection opening forming surface, of the former, and upwardly oriented the recovery cap opposing to the ink ejection opening forming surface. This condition is illustrated in enlarged form in FIG.
11
A.
FIG. 11A
is an enlarged section showing an abutting condition of the ink cartridge and the recovery cap in FIG.
10
. The projecting contours E of the recovery caps abut onto the ink ejection opening forming surface, to define the inside of the projecting contours E as sealed space D for effectively transmitting a suction force F to ink passages
41
and an ink chamber
42
.
FIG. 11B
is an enlarged section showing a condition where recovery operation for filling-up ink into the ink chamber and the ink passages from the condition where the ink cartridge and the recovery cap abut. Here, for bubble J present in a condition where meniscus is formed within the ink passage
41
, bubble K present in a condition blocking the ink passage, and bubble M present in unspecified size within the ink chamber
42
, suction recovery operation is performed for removing these bubbles by the suction pressure F. Then, upon removal of bubbles, for the ink passages where bubble J and bubble K reside, suction has to be performed by shown acting pressures O
1
to O
4
in consideration of a damper effect and a meniscus force of bubbles. However, in the ink passages where no bubble is present, suction is effected even by acting pressure N much smaller than the acting pressures O
1
to O
4
. Accordingly, by the suction recovery operation, ink is directly sucked from the ink passages where no bubble is present. From the ink passages where a bubble is present, suction of the ink is difficult. Therefore, a large amount of ink should be sucked and drained in order to remove all of bubbles.
Problems in the conventional ejection recovery system is summarized as follows.
(1) In an ink-jet printing head, an ink droplet is formed by ejecting a necessary amount of ink filled in an ink passage with rupturing a meniscus formed in an ink ejection opening. Then, when filling-up of ink into ink passages and an ink chamber is to be performed by introducing a reduced pressure within a cap sealingly covering overall an ink ejection opening forming surface, a meniscus force generated in the ink ejection opening for small opening area of the ink ejection opening associating with demand for higher quality and higher definition of image required in the recent years, becomes large to require large suction pressure.
On the other hand, wh
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hsieh Shih-Wen
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