Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-12-01
2002-12-10
Nguyen, Lamson (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S029000, C347S032000
Reexamination Certificate
active
06491370
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an ink jet recording apparatus for jetting ink drops from nozzle orifices, thereby recording images and characters on recording paper.
An ink jet recording apparatus using piezoelectric vibrators in a vertical vibration mode, which will be hereinafter referred to as recording head, generally comprises a channel unit
1
formed with a large number of nozzle orifices
8
and pressure chambers
7
and a head case
2
for housing piezoelectric vibrators
6
, to which the channel unit
1
is attached, as shown in
FIGS. 13 and 14
.
The channel unit
1
comprises a nozzle plate
3
formed with rows of the nozzle orifices
8
, a channel formation substrate
4
formed with rows of the pressure chambers
7
communicating with the nozzle orifices
8
, and a vibration plate
5
for blocking lower openings of the pressure chambers
7
, the nozzle plate
3
, the channel formation substrate
4
, and the vibration plate
5
being stacked on each other. The channel formation substrate
4
is formed with an ink reservoir
9
communicating with the pressure chambers
7
via an ink channel
10
for storing ink introduced into the pressure chambers
7
.
The head case
2
has a space
12
penetrated up and down for housing the piezoelectric vibrators
6
. Each piezoelectric vibrator
6
has a rear end side fixedly secured to a fix board
11
attached to the head case
2
and a tip face fixedly secured to an island part SA on the lower face of the vibration plate
5
. In
FIG. 13
, numeral
14
denotes a frame for protecting the nozzle plates
3
, etc.
In the recording head, a drive signal generated by a drive circuit is input to the piezoelectric vibrator
6
via a flexible circuit board
13
for expanding and contracting the piezoelectric vibrator
6
in the longitudinal direction thereof for changing pressure in the pressure chamber
7
, thereby jetting ink in the pressure chamber
7
as an ink drop through the nozzle orifice
8
.
In an ink jet recording apparatus using the recording head as described above, if print data runs out and the recording head itself is placed in a pause state, ink in the vicinity of the nozzle orifices
8
dries and the nozzle orifices are clogged. Thus, while the print operation is not performed, the recording head is sealed with a cap. However, if the recording head is left sealed with the cap for a long term, the solvent of ink in the proximity of the nozzle orifices
8
is volatilized little by little, the viscosity is increased, and trouble of making it impossible to print at once, degrading the print quality, etc., occurs easily. Further, new ink is supplied in sequence to the nozzle orifices
8
jetting ink drops consecutively by the print operation and the nozzle orifices
8
are hard to be clogged, but the nozzle orifices
8
positioned at the top end, the bottom end, etc., and having an extremely low opportunity of jetting ink drops are easily clogged because ink in the vicinity of the nozzle orifices
8
dries and the viscosity is increased during printing.
To deal with such a problem, as preliminary operation, etc., before print starts, when the recording apparatus is powered on or a print signal is first input, negative pressure is given to each nozzle orifice
8
by a suction pump, whereby ink is forcibly sucked from the nozzle orifices
8
, whereby clogging of the nozzle orifices
8
is resolved and the jetting capability of ink is recovered as “cleaning operation.”
To perform the cleaning operation, as shown in
FIG. 15A
, first the margin of a cap
15
shaped like a shallow box opened to the top is abutted against a nozzle face
40
on the lower side of the nozzle plate
3
for sealing. Next, a pump
16
connected to a suction pipe
17
is actuated with a valve
19
of a leak pipe
18
closed for sucking the inside of the cap
15
, whereby ink is forcibly sucked from the nozzle orifices
8
.
In the recording apparatus, after the ink suction terminates, sucking of the pump
16
is continued with the valve
19
of the leak pipe
18
opened for leaking the inside of the cap
15
and ink accumulating in the cap
15
is discharged. However, in the recording apparatus, when ink in the cap
15
is discharged, air enters the cap
15
from the leak pipe
18
and, bubbles
20
occur in a large amount in the cap
15
as shown in FIG.
15
B. The bubbles
20
are deposited on the nozzle face or a back-flow of ink is produced by the action of negative pressure occurring in the recording head or an ink cartridge and the bubbles
20
enter the nozzle orifices
8
and a print failure such that ink drops are not jetted or that the ink drop jetting direction becomes unstable may occur in later print.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide an ink jet recording apparatus for making it possible to preventing bubbles occurring in a cap after cleaning from adhering to a nozzle face, etc., and stabilize the printing operation.
In order to achieve the above object, according to the present invention, there is provided an ink jet recording apparatus comprising:
a recording head including a pressure chamber to which ink is supplied, a nozzle face provided with a nozzle orifice communicated with the pressure chamber, and an element for generating pressure in the pressure chamber to eject an ink drop from the nozzle orifice;
a cap member for sealing the nozzle face while defining an internal space therein;
a cover member provided in the internal space of the cap member;
a suction member for giving negative pressure to the internal space of the cap member; and
a protrusion formed on the cover member at a portion opposing to the nozzle orifice, so as to face the nozzle face while defining a narrow gap therebetween to cover the nozzle orifice when the cap member seals the nozzle face.
In this configuration, if bubbles occur in the internal space of the cap member at the time of nozzle maintenance such as a cleaning operation, the nozzle orifice is covered by the cover member with the narrow gap in between and thus entering bubbles in the nozzle orifice is almost eliminated. Since ink in the cap member is prevented from back flowing into the nozzle orifice, mixing of inks when a plurality of inks are used is prevented.
Furthermore, since ink is held by the surface tension of liquid sandwiched between the cover member and the nozzle face, so that deposition of bubbles occurring when ink is discharged onto the nozzle face can be effectively prevented without destroying meniscuses. In addition, a jet failure caused by drying the recording head is also decreased. Therefore, a print failure such that ink drops are not jetted or that the ink drop jetting direction becomes unstable is hard to occur in later print.
Preferably, a gap is defined between the cap member and the cover member. An opening is formed within the gap so as to communicate with the suction member.
In this configuration, since the ink is sucked from the opening in the gap while retaining the ink in the nozzle orifice by the cover member when the cleaning operation is performed, a jet failure during the cleaning operation can be avoided by the simple configuration.
Preferably, a top face of a peripheral margin portion of the cap member is higher than a top face of the protrusion.
Preferably, the cover member is provided with a first abutment protrusion which. is to be abutted against the nozzle face to define a gap between the cover member and the nozzle face. The first abutment protrusion is continuously formed so as to surround the protrusion.
The first abutment protrusion may be continuously formed so as to surround the cover member. Here, a second abutment protrusion is formed on a portion surrounded by the first abutment protrusion.
In the above configurations, the ink surface area exposed to the atmosphere is lessened with the cover member covering nozzle orifice with the narrow gap between and, for example, to cover the nozzle orifice with the cover member while the recording apparatus stops, volatilization of ink solvent f
Hsieh Shih Wen
Nguyen Lamson
Seiko Epson Corporation
Sughrue & Mion, PLLC
LandOfFree
Ink jet recording apparatus 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 recording apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink jet recording apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2990175