Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-06-01
2003-12-16
Hsieh, Shih-Wen (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S035000
Reexamination Certificate
active
06663219
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inkjet recording apparatus for executing recording on a medium by ejecting ink droplets onto the medium and depositing the ink droplets thereon, and more particularly, to an inkjet recording apparatus for ejecting ink in a direction opposite to the direction of gravity.
2. Description of the Related Art
Recent developments in personal computers have caused remarkable technical innovations in recording technologies used in output apparatuses for personal computers. Among these recording technologies, inkjet recording is spotlighted as a technology used in an output apparatus for outputting not only characters but also images, and in particular, images such as photographs for which multigradation, multi-color, and high resolution are required.
Inkjet recording apparatuses print characters or create an image by outputting electric signals based on image information, ejecting a minute amount of ink droplets from nozzles, which are disposed in great numbers ordinarily, on demand through an electro-dynamic transducer, and depositing the ink droplets onto a medium such as a paper and the like.
Known well among these inkjet recording apparatuses is a recording apparatus which ejects ink in a direction along the gravity direction, that is in a downward direction and a recording apparatus which injects ink in a vertical direction normal to the gravity direction.
FIG. 1
is a sectional view showing a main portion of a conventional inkjet recording apparatus. In this recording apparatus, an inkjet recording head is arranged so as to eject ink in a direction along the gravity direction, that is, in a downward direction.
In the inkjet recording apparatus shown in
FIG. 1
, a recording head
101
and an ink tank
102
are mounted on a carriage
103
, wherein the recording head
101
ejects ink onto an upper surface of a medium M and forms an image thereon, and the ink tank
102
accommodates ink to be supplied to the recording head
101
. The carriage
103
is supported by two sliding shafts
105
a
and
105
b
and reciprocated by a carriage drive motor (not shown) through a timing belt (not shown) in a direction (vertical to the figure) which is normal to a direction in which the medium M is transported (right to left direction on the figure).
A head fixing cover
104
is mounted on the carriage
103
so that the recording head
101
can be fixed on the carriage
103
with a high degree of precision.
Note that these two sliding shafts
105
a
and
105
b
support the carriage
103
and determine a scanning direction thereof as well as regulate a distance between an ink ejecting port surface
101
a
of the recording head
101
and the medium M facing the ink ejecting port surface
101
a
to permit an image of high accuracy to be formed on the medium M.
As the carriage
103
moves, the inkjet recording apparatus creates an image for each one scan on the upper surface of the medium M by ejecting ink from the recording head
101
during reciprocating movement of the recording head
101
while alternately repeating the movement of the recording head
101
and transportation of the medium M at a each predetermined pitch.
A pair of sheet feed rollers
106
a
and
106
b,
which constitute a transportation unit for transporting the medium M, are disposed upstream of the carriage
103
with respect to a transporting direction of the medium M. The medium M is supplied between the sheet feed rollers
106
a
and
106
b
from an auto-sheet-feeder (not shown) or a cassette (not shown) mounted on the recording apparatus. Note that the sheet feed roller
106
b
is driven by a drive unit (not shown) through a drive gear
107
.
A guide member (not shown) is disposed downstream of the sheet feed rollers
106
a
and
106
b
with respect to the transporting direction of the medium M. The guide member prevents the ink ejecting port surface
101
a
from coming into contact with the medium M by preventing floating and twisting of the medium M at a position where it faces the ink ejecting port surface
101
a.
In addition to the above, the guide member keeps a distance between the ink ejecting port surface
101
a
and the upper surface of the medium M constant, thereby maintaining a position where ink reaches the medium M at a high degree of precision.
Further, a pair of sheet discharge rollers
108
a
and
108
b
are disposed downstream of the carriage
103
with respect to the transporting direction of the medium M. When the medium M arrives between the sheet discharge rollers
108
a
and
108
b,
it is further transported mainly by the sheet discharge rollers
108
a
and
108
b
thereafter, and the medium M, on which an image is created by the recording head
101
, is discharged to the outside of the recording apparatus.
It is known in recording by inkjet that execution of preliminary ejection is an effective means for achieving stable recording. A preliminary ejection receiver (which also is referred to as an ejection without ink receiver) has the function of receiving ink that is ejected from a recording head at a predetermined position outside the region where recording can be executed to a medium, prior to a recording operation and for supplying the thus received ink to a waste ink processing system.
While there are several reasons why this arrangement is necessary, one particular reason is to discharge ink which is condensed in nozzles when a recording apparatus is not used for a long period.
When a recording operation is resumed after the recording apparatus is brought to rest for a long time, ink condensed at positions near to ejecting ports of nozzles is ejected first, and then ink in the interiors of the nozzles and ink from an ink supply system located rearward of the nozzles are gradually ejected. An image recorded at that time is such that a beginning portion of the image has a deep tone, and an intrinsic tone of the ink is gradually reproduced toward a rear portion thereof, which results in an uneven tone. In particular, when uniform half-tones of 50%, 25% and the like which are adjacent each other are recorded on a white medium, a portion having a deep tone is formed first on the medium to be recorded and the tone becomes lighter toward a rear portion thereof, which makes irregularity of tone particularly conspicuous on the medium to be recorded.
To prevent occurrence of the above problem, an image is usually formed on a medium M after ink condensed in nozzles is discharged using a preliminary ejection receiver (ejection without ink receiver) as described above.
In
FIG. 1
, a preliminary ejection receiver
109
for receiving ink preliminarily ejected from the recording head
101
is disposed with its opening facing a direction opposite to the gravity direction, that is, in an upward direction. In the recording apparatus, the preliminary ejection receiver
109
is disposed outside a region, where recording can be executed by the recording head
101
to the medium M. More specifically, the preliminary ejection receiver
109
is disposed at a position in the vicinity of a terminal end in a moving region of the carriage
103
which moves along the sliding shafts
105
a
and
105
b.
As a result, when the carriage
103
moves to the terminal end, the ink ejecting port surface
101
a
of the recording head
101
mounted on the carriage
103
faces the opening of the preliminary ejection receiver
109
. Note that an absorption body
110
is disposed in the preliminary ejection receiver
109
to hold the preliminarily ejected ink.
A waste ink absorption body
111
and a waste ink holding member
112
are disposed in the inkjet recording apparatus below the above respective arrangements to cope with a case in which ink accidentally drops from the recording head
101
.
As described above, in a downward printing type recording apparatus, a preliminary ejection receiver is disposed below a recording head with its opening facing upward, and ink ejected into the preliminary ejection receiver drops downward due to gravity an
Kubota Hidemi
Tachihara Masayoshi
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