Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-11-05
2002-01-08
Nguyen, Judy (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06336698
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet printer having an exchangable printing head.
2. Description of Related Art
A known ink jet printer includes a carriage, which can reciprocate horizontally along a printing medium. A head holder is mounted removably on the carriage, and supports print heads on it. The heads can eject ink onto the medium. The printer also includes a capping device, which includes protective caps for covering the ejection faces of the heads to prevent the ink on and in the heads from drying. There may be cases where the heads need to be replaced because of their lives, trouble, etc.
FIGS. 20
,
21
A,
21
B,
21
C,
22
A and
22
B of the accompanying drawings show a known ink jet printer of the foregoing type. As shown in
FIG. 20
, the printer includes a carriage
103
, a head holder
102
mounted removably on the carriage
103
, and print heads
101
(only one shown) supported on the holder
102
. Each head
101
has an ejection face
101
a
(
FIGS. 22A and 22B
) and an array of nozzles (not shown) formed in it. The front ends of the nozzles are open in the ejection face
101
a
. The holder
102
includes a pair of side walls
107
. The carriage
103
includes a pair of side walls
106
. The printer also includes protective caps
105
each for covering one of the ejection faces
101
a
. The caps
105
are positioned outside one edge of the path along which a printing medium moves. The caps
105
are supported at a fixed position, but with such slight play that they can incline forward and backward for close contact with the ejection faces
101
a.
The printer includes mounting mechanism
104
provided between the head holder
102
and the carriage
103
to mount the holder on the carriage. The mounting mechanism
104
include a pair of grooves
106
a
each formed on the inner side of one of the carriage walls
106
. The front end of each groove
106
a
is closed, and the rear end is open and wider than the front end. The mounting mechanism
104
also include a pair of horizontal pins
107
a
each formed on one of the holder walls
107
to engage slidably with the adjacent groove
106
a.
It is possible to mount the head holder
102
on the carriage
103
by:
moving the holder
102
toward the protective caps
105
, as shown in
FIGS. 21A and 21B
, with the holder pins
107
a
engaged with the carriage grooves
106
a
; and
then turning the holder
102
around its pins
107
a
clockwise in
FIGS. 21A and 21B
to bring the print heads
101
to the normal position shown in
FIG. 21C
, where the heads correctly face the printing position on the printing medium.
One might consider replacing the print heads
101
after moving the carriage
103
to a position where it faces the printing medium path. In such a case, it would be necessary to put the head holder
102
on the carriage
103
in a direction inclined with respect to the medium path, in such a manner that the upper edges of the heads
101
might move toward the medium path beyond the normal position of the heads
101
. It would then be necessary to turn the inclined holder
102
to its normal position. When the upper edges of the heads
101
move toward the medium path, however, they would impinge on the printing medium, because the ejection faces
101
a
are normally spaced only about 2 mm from the path. It would consequently be impossible to replace the heads
101
when the carriage
103
faces the medium path.
Therefore, the print heads
101
can be replaced at their position where their ejection faces
101
a
are covered with the protective caps
105
. The head replacement involves:
removing the head holder
102
from the carriage
103
;
providing a new head holder
102
supporting new print heads
101
;
engaging the horizontal pins
107
a
of the new holder
102
with the carriage grooves
106
a
, as shown in
FIG. 22A
, with the heads
101
inclined with respect to their normal position;
then moving the holder
102
until a portion over the ejection face
101
a
of each head
101
comes into contact with the upper edge of the associated protective cap
105
;
further moving the holder
102
, as shown in
FIG. 22B
, so that each cap
105
inclines around its upper edge and parallels the associated ejection face
101
a
; and
then turning the holder
102
around the pins
107
a
clockwise in
FIGS. 22A and 22B
to bring the heads
101
into the normal position, moving the ejection faces
101
a
upward.
When the ejection faces
101
a
move up, the caps
105
, which are supported at their fixed position, rub on the faces. This may force dust etc. on the caps
105
and the ejection faces
101
a
into the head nozzles. Therefore, there is need for strong purging every time the heads
101
have been replaced. There may be cases where such purging is not sufficient to remove dust etc.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an ink jet printer of which the print head can be replaced without the protective cap rubbing on the ejection face of the head.
In accordance with a first aspect of the invention, a printer is provided, which includes a carriage movable in opposite reciprocating directions. The carriage has a turning axis extending in the reciprocating directions. A head holder can be mounted on the carriage, and holds a print head. The head has an ejection face and a nozzle for ejecting ink onto a printing medium. The nozzle is open in the ejection face. The printer also includes a capping mechanism, which includes a protective cap for covering the ejection face. The head holder can be mounted on the carriage with a mounting mechanism by a process including the steps of:
moving the holder toward the turning axis until part of the holder arrives at the axis and until the ejection face comes into contact with the protective cap; and
thereafter turning the head holder around the axis.
The protective cap is supported in such a manner:
that, while out of contact with the ejection face, the cap is oriented opposite the direction in which the head holder can be moved toward the turning axis; and
that, while the holder is turned, the cap can turn in the turning directions in which the holder turns.
As stated above, the protective cap of this printer is supported in such a manner that, while it is out of contact with the ejection face, that is to say, while the head holder is not mounted on the carriage, the cap is oriented opposite the direction in which the head holder can be moved toward the turning axis. For replacement of the print head, a new head holder holding a new print head is first moved to the turning axis until part of the holder engages with the carriage. When the holder part engages with the carriage, the ejection face of this head faces and comes into close contact with the cap, as shown in
FIG. 9B
of the accompanying drawings. Subsequently, while the head holder is turned around the axis, the protective cap is turned, kept in contact with the ejection face. Therefore, while the head holder is turned, the protective cap does not slide on the ejection face. This prevents the nozzle from clogging due to the cap slide or slip.
In particular, the capping mechanism of this printer may be so designed that, when the print head is replaced, the front edge of the protective cap can follow the locus of the ejection face moving while the head holder is turning around the turning axis.
The capping mechanism may also include a casing. A cap holder for holding the protective cap may be supported by the casing movably in the turning directions. An urging member may be interposed between the casing and the cap holder. The member urges the protective cap to either a first position where the cap is oriented opposite the direction in which the head holder can be moved toward the turning axis or a second position where the cap faces the ejection face of the print head when the head holder has been mounted on the carriage.
The urging member can alternatively orient the protective cap. Specifically, the cap is oriented to the firs
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