Incremental printing of symbolic information – Ink jet – Medium and processing means
Reexamination Certificate
2003-03-20
2004-09-07
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Medium and processing means
C347S101000
Reexamination Certificate
active
06786589
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an ink jet printer, an ink jet head unit, and an image forming method which makes image formation on a recording medium by the jetting of ink drops on the recording medium.
In recent years, as an image forming method capable of forming an image simply at a low cost, an image forming method using an ink jet printer is used in a large number of cases. A serial type ink jet printer moves a recording medium, a paper sheet for example, intermittently in the sub-scanning direction, and while the recording medium is stopped, moves the head over the recording medium in the main scanning direction which is perpendicular to the sub-scanning direction. Further, during the moving of the head in the main scanning direction, the ink jet printer jets ink drops from the head to the recording medium by deforming a piezoelectric element forming an ink chamber, or by heating a heater in the case where a heater is provided in the ink chamber. In another case, an ink jet printer having a line-shaped head moves a recording medium, a paper sheet for example, in the sub-scanning direction, and jets ink drops from the line-shaped head provided lengthwise in the main scanning direction which is perpendicular to the sub-scanning direction to the recording medium. The methods of jetting ink drops in this case are same as those of serial type ink jet printer. By such operations of ink jet printers, an image is formed on a recording medium.
Incidentally, as regards an ink to be used in an ink jet printer, there is an active-ray-setting ink to be hardened by the irradiation of active rays such as ultraviolet rays or electronic rays. An active-ray-setting ink is composed of, for example, a color material, a polymerizable monomer or oligomer, and a polymerization initiator and a polymerization accelerator at need, and is hardened by a bridging reaction or a polymerization reaction induced by the irradiation of active rays. A printer practicing image formation with such an active-ray-setting ink has been being remarked in recent years from the viewpoint that it gives out comparatively lower smell compared to a printer practicing image formation with a solvent ink and is capable of recording on a recording medium having no ink absorbing ability.
Incidentally, as an ink jet printer making a print with a UV ink to be hardened by ultraviolet rays, such one as shown in
FIG. 9
is known.
FIG. 9
shows the top view of a state in which a recording medium
104
is being transported in the sub-scanning direction B as an outline view for the purpose of making it easy to understand the layout of the ink jet head. In the ink jet printer shown in
FIG. 9
, each of the heads
102
,
102
, - - - jets ink drops of a UV ink to the recording medium
104
; the heads
102
,
102
, - - - are provided on the carriage
101
which is movable back and forth in the main scanning direction A, and a light source
103
is provided at the downstream side of the carriage
101
in the sub-scanning direction B. That is, the light source
103
is provided at the downstream position in the transporting direction B′ of the recording medium
104
.
This ink jet printer jets ink drops during the moving of the carriage
101
in the main scanning direction A from the heads
102
,
102
, - - - towards the recording medium
104
, transports the recording medium
104
in the direction of the sub-scanning direction B, and makes the light source
103
emit ultraviolet rays. By this operation, ink drops landed on the recording medium
104
are hardened. However, in this ink jet printer, because it takes a considerable time to emit ultraviolet rays after the ink drops are landed on the recording medium
104
, the ink drops landed spread to an extent greater than necessary on the recording medium.
Especially, in the case of color printer, where plural heads jet respectively different color ink to form a color image, difference in the degree of color mixture occurs and may lead to a large image problem.
For the purpose of obtaining a high-quality image, it is desirable to irradiate the ink drops by ultraviolet rays to harden the ink drops as soon as possible after the UV ink drops are landed on the recording medium.
Therefore, the object of this invention is to make it possible to form a high-quality image on a recording medium. That is, the object is to accomplish an image formation of high image quality by the controlling of the spreading of ink drops landed on the recording medium as well as by the equalizing of the degree of their spreading.
The above-mentioned object is accomplished by any one of the structures described below.
(1) An ink jet printer for forming an image on a recording medium with an active-ray-setting ink, which is hardened by an irradiation of active rays, comprising: a plurality of heads, each of the plurality of heads having a plurality of jet openings for jetting the active-ray-setting ink as ink drops towards the recording medium; and a plurality of active ray sources to irradiate active rays for hardening the ink drops of the active-ray-setting ink landed on the recording medium, wherein each of the plurality of heads and each of the plurality of active ray sources are arranged alternately.
According to the structure (1), because each of the plural heads and each of the plural active ray sources are arranged alternately, the ink drops landed on a recording medium, from whichever heads they have been jetted, are immediately irradiated by the active rays emitted from the neighboring active ray source. Hence, any ink drop jetted from any one of the heads starts setting by the irradiation of the active rays within a specified range of time after landing on the recording medium; therefore, ink drops do not spread on the recording medium, and what is called a blur is prevented. Further, because the time interval from the landing of an ink drop to the irradiation by active rays does not vary from an ink drop from one head to that from another, the dispersion of the blur among the heads can be suppressed. Thus, a high-quality image can be obtained.
(2) An ink jet printer as set forth in the structure (1) further comprising a mobile body being movable in the main scanning direction relatively to a recording medium and having the aforesaid plural heads and the aforesaid plural active ray sources arranged alternately in said main scanning direction.
According to the structure (2), because the plural heads and the plural active ray sources are provided in the mobile body being movable in the main scanning direction relatively to a recording medium, this structure can be applied to an ink jet printer having a mechanism such that the printer jets ink drops to a recording medium while it moves the heads in the main scanning direction. This structure can provide a serial type ink jet printer.
(3) An ink jet printer as set forth in the structure (2), wherein the aforesaid plural jet openings are formed linearly along the sub-scanning direction which is substantially perpendicular to the aforesaid main scanning direction.
According to the structure (3), because the plural jet openings are formed linearly along the sub-scanning direction, compared to a conventional technology shown in
FIG. 9
, the time interval from the landing of an ink drop on a recording medium to the irradiation by active rays becomes shorter. Thus, the spreading of ink drops is reduced.
(4) The ink jet printer of the structure (2), wherein the intervals between each of the plurality of heads and each of the active ray sources neighboring to said each of the plurality of heads become equal to one another.
According to the structure (4), since the intervals between each of the plurality of heads and each of the active ray sources neighboring to said each of the plurality of heads become equal to one another, any one of ink drops jetted from any one of the heads has approximately a definite time interval from the landing on a recording medium to the irradiation by active rays. And all the ink drops have approximately a
Hirai Yoko
Suzuki Yoshiyuki
Frishauf Holtz Goodman & Chick P.C.
Konica Corporation
Meier Stephen D.
Shah Manish
LandOfFree
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