U.S. patent application number 12/814901 was filed with the patent office on 2011-02-03 for light irradiating apparatus, light irradiating process, and image recording process.
This patent application is currently assigned to SEIKO EPSON CORPORATION. Invention is credited to Keitero NAKANO, Takashi OYANAGI.
Application Number | 20110025795 12/814901 |
Document ID | / |
Family ID | 37797047 |
Filed Date | 2011-02-03 |
United States Patent
Application |
20110025795 |
Kind Code |
A1 |
OYANAGI; Takashi ; et
al. |
February 3, 2011 |
LIGHT IRRADIATING APPARATUS, LIGHT IRRADIATING PROCESS, AND IMAGE
RECORDING PROCESS
Abstract
The present invention provides a light irradiating apparatus
comprising a plurality of light emitting elements which emit light
of a specific wavelength region and form elliptical light images on
a surface to be irradiated, wherein the plurality of light emitting
elements are mutually arranged so that the light images are made
continuous along their major axis directions. Further, the
invention also discloses the above-mentioned light irradiating
process and an image recording process.
Inventors: |
OYANAGI; Takashi; (Nagano,
JP) ; NAKANO; Keitero; (Nagano, JP) |
Correspondence
Address: |
LADAS & PARRY LLP
26 WEST 61ST STREET
NEW YORK
NY
10023
US
|
Assignee: |
SEIKO EPSON CORPORATION
|
Family ID: |
37797047 |
Appl. No.: |
12/814901 |
Filed: |
June 14, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11483394 |
Jul 7, 2006 |
7850280 |
|
|
12814901 |
|
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Current U.S.
Class: |
347/102 ;
362/230 |
Current CPC
Class: |
B41J 11/002
20130101 |
Class at
Publication: |
347/102 ;
362/230 |
International
Class: |
B41J 2/01 20060101
B41J002/01; F21V 9/00 20060101 F21V009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 8, 2005 |
JP |
P.2005-200301 |
Mar 3, 2006 |
JP |
P.2006-058695 |
Claims
1. A light irradiating apparatus comprising a plurality of light
emitting elements which emit light of a specific wavelength region
and form elliptical light images on a surface to be irradiated,
wherein the plurality of light emitting elements are mutually
arranged so that the light images are made continuous along their
major axis directions.
2. The light irradiating apparatus according to claim 1, wherein
the plurality of light emitting elements are arranged in a line or
in a plurality of parallel lines.
3. The light irradiating apparatus according to claim 1 or 2,
wherein the plurality of light emitting elements comprise a single
species or a combination of plural species of light emitting
elements which emit an ultraviolet ray or visible light.
4. The light irradiating apparatus according to any one of claims 1
to 3, wherein an arrangement of the plurality of light emitting
elements is formed by arranging light emitting elements having the
same light emitting wavelength peak or light emitting elements
different in the light emitting wavelength peak, with spacing from
one another along major axis directions of the elliptical light
images.
5. The light irradiating apparatus according to any one of claims 1
to 4, wherein the aspect ratio of the light image is 2.0 or
more.
6. The light irradiating apparatus according to any one of claims 1
to 5, wherein the light emitting element is a semiconductor laser
element.
7. The light irradiating apparatus according to claim 6, wherein
the semiconductor laser element is one which emits an ultraviolet
ray having a wavelength of less than 400 nm.
8. The light irradiating apparatus according to claim 6, wherein
the semiconductor laser element is one which emits visible light
having a wavelength of 400 to 450 nm.
9. The light irradiating apparatus according to claim 6, wherein
the semiconductor laser element is a combination of one which emits
an ultraviolet ray having a wavelength of less than 400 nm and one
which emits visible light having a wavelength of 400 to 450 nm.
10. A light irradiating process comprising irradiating light by
using a plurality of light emitting elements which emit light of a
specific wavelength region and form elliptical light images on a
surface to be irradiated, wherein the light images are made
continuous along their major axis directions.
11. The light irradiating process according to claim 10, wherein
the light emitting element is allowed to achieve continuous light
emission.
12. The light irradiating process according to claim 10, wherein
the light emitting element is allowed to achieve pulse light
emission.
13. An image recording process comprising adhering a light curing
type ink composition onto a recording medium, and then, performing
light irradiation by the light irradiating apparatus according to
any one of claims 1 to 9.
14. An image recording process comprising adhering a light curing
type ink composition onto a recording medium, and then, performing
light irradiation by the light irradiating process according to any
one of claims 10 to 12.
15. The image recording process according to claim 13 or 14,
wherein the light curing type ink composition is one which contains
at least a polymerizable compound, a photopolymerization initiator
and a polymerization accelerator, and contains an N--vinyl compound
as the polymerizable compound, two or more selected from the group
consisting of a bisacylphosphine oxide, a monoacylphosphine oxide
and an .alpha.-aminoketone as the photopolymerization initiator,
and polymerizable functional group-containing fine particles as the
polymerization accelerator, respectively.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a light irradiating
apparatus for irradiating light having a specific wavelength region
on a surface to be irradiated, a light irradiating process and an
image recording process, and more particularly to a light
irradiating apparatus suitable for using when a light curing type
ink adhered onto a recording medium with an ink jet printer or the
like is cured by light irradiation, a light irradiating process and
an image recording process.
BACKGROUND OF THE INVENTION
[0002] In recent years, attention has been drawn to ultraviolet
curing type inks as inks used in ink jet printers and the like.
[0003] The point at which the ultraviolet curing type inks are
different from ordinary water-based and oil-based inks is that the
ultraviolet curing type inks are quickly cured when adhered onto
recording media (for example, print paper and the like), and then,
irradiated with a proper amount of a ultraviolet ray, thereby being
able to maintain stable printing quality, without depending on
physical properties of the recording media such as ink
permeability.
[0004] In the ink jet printer using such an ultraviolet curing type
ink, it is necessary to provide an ultraviolet irradiating
apparatus for irradiating an ultraviolet ray on an ink adhered onto
the recording medium, on the periphery of a recording head for
ejecting the ultraviolet curing type ink as fine-particle ink
droplets to adhere them onto the recording medium.
[0005] In the conventional ultraviolet irradiating apparatus, there
has been variously proposed one in which an ultraviolet lamp such
as a mercury lamp or a metal halide lamp is employed as a light
source for emitting an ultraviolet ray (for example, see Patent
Document 1).
[0006] However, light emitted from the ultraviolet lamp has a
continuous spectrum over a wide wavelength region and includes
visible light and infrared light in addition to a plurality of
ultraviolet lights having different wavelength regions, so that
there has been a problem that the infrared light in the continuous
spectrum gives a thermal damage to the recording medium.
[0007] When a band-pass filter is provided in order to remove the
hazardous infrared light, there has been a problem that the
structure of a device becomes complicated, resulting in an increase
in cost.
[0008] Further, the ultraviolet lamp has great power consumption,
so that there has been a problem that energy saving of the
ultraviolet irradiating apparatus is difficult.
[0009] In addition, the ultraviolet lamp itself is large, so that
there has also been a problem that miniaturization and weight
saving of the apparatus is difficult.
[0010] Consequently, associated with development of a solid laser
or a light emitting diode (LED) which includes no infrared light,
is capable of emitting only light of a specific wavelength region
and has relatively small power consumption, there has recently been
studied an ultraviolet irradiating apparatus in which these are
employed as a light source, thereby preventing a thermal damage
from being given to the recording medium caused by the infrared
light contained, while achieving energy saving, miniaturization and
weight saving (for example, see Patent Document 2).
[0011] Further, when printed images of the ultraviolet curing type
inks are irradiated with these light source, there has been used a
scanning system by a combination of a polygon mirror and an
f-.theta. lens or a galvano mirror (for example, see patent
document 3). However, these optical scanning systems have movable
parts. This makes it difficult to further miniaturize the
apparatus, and further, a decrease in reliability caused by
malfunction is unavoidable.
[0012] For this reason, a light irradiating apparatus which can be
further miniaturized, moreover, has no movable parts and can
perform high-reliability face irradiation. As the light irradiating
apparatus requiring no movable parts like this, there is
considered, for example, a structure in which small-sized light
sources are densely arranged.
[0013] [Patent Document 1] JP-A-2004-1326
[0014] [Patent Document 2] JP-A-2003-326691
[0015] [Patent Document 3] JP-A-2004-167793
[0016] However, there has been a problem that the structure of
densely arranging small-sized light sources increases the number of
light sources themselves, raises cost, and causes heat generated
from the light sources to be accumulated between the light sources,
also resulting in a decrease in life of the light sources due to
their thermal damage and necessity of a cooling operation and
means.
SUMMARY OF THE INVENTION
[0017] Accordingly, objects of the invention is to solve the
above-mentioned problems, and to provide a light irradiating
apparatus in which the number of light sources themselves is small,
and which does not deteriorate due to damage by heat generated
therefrom, a light irradiating process and an image recording
process.
[0018] The above-mentioned objects are achieved by the following
constitution:
[0019] (1) A light irradiating apparatus comprising a plurality of
light emitting elements which emit light of a specific wavelength
region and form elliptical light images on a surface to be
irradiated, wherein the above-mentioned plurality of light emitting
elements are mutually arranged so that the above-mentioned light
images are made continuous along their major axis directions;
[0020] (2) The light irradiating apparatus described in the above
(1), wherein the above-mentioned plurality of light emitting
elements are arranged in a line or in a plurality of parallel
lines;
[0021] (3) The light irradiating apparatus described in the above
(1) or (2), wherein the above-mentioned plurality of light emitting
elements comprise a single species or a combination of plural
species of light emitting elements which emit an ultraviolet ray or
visible light;
[0022] (4) The light irradiating apparatus described in any one of
the above (1) to (3), wherein an arrangement of the above-mentioned
plurality of light emitting elements is formed by arranging light
emitting elements having the same light emitting wavelength peak or
light emitting elements different in the light emitting wavelength
peak, with spacing from one another along major axis directions of
the elliptical light images;
[0023] (5) The light irradiating apparatus described in any one of
the above (1) to (4), wherein the aspect ratio of the
above-mentioned light image is 2.0 or more;
[0024] (6) The light irradiating apparatus described in any one of
the above (1) to (5), wherein the above-mentioned light emitting
element is a semiconductor laser element;
[0025] (7) The light irradiating apparatus described in the above
(6), wherein the above-mentioned semiconductor laser element is one
which emits an ultraviolet ray having a wavelength of less than 400
nm;
[0026] (8) The light irradiating apparatus described in the above
(6), wherein the above-mentioned semiconductor laser element is one
which emits visible light having a wavelength of 400 to 450 nm;
[0027] (9) The light irradiating apparatus described in the above
(6), wherein the above-mentioned semiconductor laser element is a
combination of one which emits an ultraviolet ray having a
wavelength of less than 400 nm and one which emits visible light
having a wavelength of 400 to 450 nm;
[0028] (10) A light irradiating process comprising irradiating
light by using a plurality of light emitting elements which emit
light of a specific wavelength region and form elliptical light
images on a surface to be irradiated, wherein the above-mentioned
light images are made continuous along their major axis
directions;
[0029] (11) The light irradiating process described in the above
(10), wherein the above-mentioned light emitting element is allowed
to achieve continuous light emission;
[0030] (12) The light irradiating process described in the above
(10), wherein the above-mentioned light emitting element is allowed
to achieve pulse light emission;
[0031] (13) An image recording process comprising adhering a light
curing type ink composition onto a recording medium, and then,
performing light irradiation by the light irradiating apparatus
described in any one of the above (1) to (9);
[0032] (14) An image recording process comprising adhering a light
curing type ink composition onto a recording medium, and then,
performing light irradiation by the light irradiating process
described in any one of the above (10) to (12); and
[0033] (15) The image recording process described in the above (13)
or (14), wherein the light curing type ink composition is one which
contains at least a polymerizable compound, a photopolymerization
initiator and a polymerization accelerator, and contains an N-vinyl
compound as the polymerizable compound, two or more selected from
the group consisting of a bisacylphosphine oxide, a
monoacylphosphine oxide and an .alpha.-aminoketone as the
photopolymerization initiator, and polymerizable functional
group-containing fine particles as the polymerization accelerator,
respectively.
[0034] In the light irradiating apparatus described in the above
(1), the light emitting elements are arranged with spacing from one
another in the major axis direction of the light images so that the
elliptical light images formed by the respective light emitting
elements are made continuous along the major axis direction of the
ellipsoids. Accordingly, the light irradiating process described in
the above (10) can be performed. Compared to the case of a light
irradiating apparatus in which the light emitting elements are
mutually arranged so that the elliptical light images are made
continuous along the minor axis direction of the ellipsoids, a
space between light emitting elements adjacent to one another can
be set large, and it becomes possible to irradiate light of a
specific wavelength region over the larger width by the smaller
number of light emitting elements used.
[0035] Accordingly, when light of a specific wavelength region is
irradiated over a predetermined width of a surface to be
irradiated, it becomes possible to reduce the number of light
emitting elements used as light sources to lower cost.
[0036] Further, the space distance between light emitting elements
as light sources can be set large, so that heat generated from the
respective light emitting elements becomes difficult to be
accumulated between the light emitting elements, which can prevent
the light emitting elements themselves from suffering from thermal
damage due to the accumulated heat, thereby being able to prevent a
decrease in life of the light sources due to their thermal
damage.
[0037] Furthermore, for example, when mounted on the periphery of a
print head of an ink jet printer to cure by light irradiation the
light curing type ink adhered onto the recording medium by means of
the print head of the printer, heat generation of the light
irradiating apparatus itself can be inhibited. Accordingly, it
becomes unnecessary to install a cooling operation and means such
as a cooling fun on the printer, which also largely contributes to
miniaturization of the ink jet printer and cost reduction.
[0038] In addition, the irradiating area of light according to the
arrangement of the light emitting elements as the light sources can
be set to an arbitrary size without being restricted by the major
axis size x and the minor axis size y of the elliptical light image
formed by the single light emitting element, by arranging the light
emitting elements in a line or in a plurality of parallel lines as
described in the above (2).
[0039] That is to say, the size of the irradiating area along the
width direction of the recording medium can be arbitrarily set by
appropriately setting the number of light emitting elements
arranged in s line along the width direction of the recording
medium, the size of the irradiating area along the transfer
direction of the recording medium can be arbitrarily set by
installing the element lines in the transfer direction of the
recording medium in multiple lines at predetermined intervals, and
the speeding up of processing can be achieved by increasing the
number of light emitting element lines to enlarge the irradiating
area of light in the transfer direction of the recording
medium.
[0040] Further, the light curing type ink can allow the curing
action to effectively proceed by the irradiation of an ultraviolet
ray having a specific wavelength. However, even when visible light
close to the ultraviolet ray is irradiated in place of the
ultraviolet ray, curing processing is possible although the
processing efficiency decreases, compared to the case of the
ultraviolet irradiation.
[0041] In general, a light emitting element which emits an
ultraviolet ray is more expensive than a light emitting element
which emits visible light.
[0042] Consequently, taking into account the difference in price
between the light emitting element for an ultraviolet ray and the
light emitting element for visible light, the processing speed
required and the like, the adoption of the light emitting element
for visible light which is low in price is also appropriately set,
as described in the above (2). This makes it possible to provide a
light irradiating apparatus well balanced in cost and
performance.
[0043] Further, in the light curing type ink, the difference occurs
in the wavelength region of light absorbed when irradiated,
depending on the difference in composition of a color material
component (pigment, dye or the like) and other components. This
causes the occurrence of the difference in curing time of the ink
in some cases.
[0044] Consequently, light irradiation in a wide wavelength region
having a plurality of light emitting peaks becomes possible by
using a construction in which light emitting elements different in
the light emitting wavelength peak are arranged, as the arrangement
of the plurality of light emitting elements, as described in the
above (4). Even when light of a part of the light emitting peaks is
absorbed, light of the other light emitting peaks effectively
contributes to curing of the ink to make it possible to stably
maintain the curing efficiency of the ink. Thus, it becomes
possible that irradiating light to be absorbed complies with
various kinds of light curing type inks different in the light
emitting wavelength peak. As a result, the ink species to be
complied with can be increased to improve the versatility as the
light emitting apparatus.
[0045] When the aspect ratio of the elliptical light images is set
to 2.0 or more as described in the above (5), the difference in an
arrangement space between the light emitting elements between the
case where the elliptical light images are arranged along the major
axis direction and the case where arranged along the minor axis
direction becomes extremely significant, compared to the case where
light emitting elements which form elliptical light images having
an aspect ratio of less than 2.0 are employed. A reduction in the
number of the light emitting elements used as the light sources and
enlargement of the space between the light emitting elements assist
diffusion of heat generated by the light emitting elements, and the
effect of preventing the light emitting elements from deteriorating
by thermal damage due to accumulated heat becomes clear.
[0046] Further, as described in the above (6), when the
semiconductor laser element is employed as the light emitting
element, outgoing light forms an elliptical light image for
structural reasons of the element itself such as a semiconductor
laser diode that is a semiconductor laser, and it becomes possible
to obtain the elliptical light image effective for enlargement of
the space between the light emitting elements without using a
special optical means.
[0047] Furthermore, in light emission by the semiconductor laser
element, outgoing light diffuses compared to light emission of a
solid laser, so that the wider area can be irradiated with a light
beam by one light emitting element. This is therefore suitable for
decreasing the light emitting elements used, and at the same time,
a combination with a scanning mechanism for enlarging the
irradiation area of a light beam becomes unnecessary. This makes it
possible to secure the wide irradiation area of the light beam at a
low price.
[0048] In addition, installation of the scanning mechanism becomes
unnecessary, so that such a construction that the light emitting
element is attached to a movable part for scanning becomes
unnecessary. Accordingly, it becomes possible to improve
operational reliability and durability as the light irradiating
apparatus by employing design excluding the movable part which
causes malfunction.
[0049] When the semiconductor laser element is employed as the
light emitting element, in order to obtain the light irradiating
apparatus described in the above (3), it is preferred that the
semiconductor laser element which emits visible light having a
wavelength of 400 to 450 nm and the semiconductor laser element
which emits visible light having a wavelength of 400 to 450 nm are
arranged alone or in an appropriately mixed state thereof, as
described in the above (7) to (9).
[0050] Further, for example, when the light emitting element is
used for applications in which the light curing type ink adhered
onto the recording medium by a print head in the ink jet printer is
cured by light irradiation, it is considered that the light
emitting element is allowed to achieve continuous light emission
toward a coated area of the light curing type ink during print
processing of the printer as described in (11). However, when the
light emitting element is allowed to achieve continuous light
emission, the amount of irradiated light possibly reaches the
amount equal to or more than the amount necessary for curing
processing of the light curing type ink. In such a case, the light
emitting element is allowed to intermittently achieve pulse light
emission as described in (12), thereby controlling the amount of
light irradiated to the light curing type ink to the necessary
amount to be able to achieve a reduction in power consumption in
the light irradiating apparatus, a reduction in heat generation of
the light emitting element, and prolongation of life by shortening
the actual working hours of the light emitting element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] FIG. 1 is a schematic perspective view showing a main
construction of one embodiment of an ink jet printer equipped with
a light irradiating apparatus according to the invention.
[0052] FIG. 2 is an enlarged perspective view of the light
irradiating apparatus shown in FIG. 1.
[0053] FIG. 3 is a block diagram showing an electric construction
in the ink jet printer shown in FIG. 1.
[0054] FIG. 4 is an illustrative view of an irradiation area at the
time when a plurality of light emitting elements which form
elliptical light images are mutually arranged so that the
elliptical light images given by the respective elements are made
continuous along the minor axis direction thereof.
[0055] FIG. 5 is a view showing another example of a continuous
state of the elliptical light images c.
[0056] The reference numerals used in the drawings denote the
followings, respectively.
[0057] 20: Ink Jet Printer, 30: Paper Feed Motor, 32: Rotary
Encoder, 34: Paper Feed Roller, 40: Platen, 50: Carriage, 52: Print
Head (Recording Head), 54: Black Cartridge, 56: Color Ink
Cartridge, 60: Carriage Motor, 62: Tow Belt, 64: Guide Rail, 70:
Linear Encoder, 72: Coding Plate, 74: Photo Sensor, 80: Capping
Device; 90: Light Irradiating Apparatus, 91: Element Support Means,
91a: Attachment Surface, 92: Bracket, 93: Bracket, 95: Light
Emitting Element, 102: Main Control Circuit, 104: CPU, 110: ROM,
112: RAM, 114: EEPROM, 120: Interface Circuit, 130: Paper Feed
Motor Driving Circuit, 140: Head Driving Circuit, 150: CR Motor
Driving Circuit, 160: Light Irradiating Apparatus Driving Circuit,
P: Print Paper (Recording Medium)
DETAILED DESCRIPTION OF THE INVENTION
[0058] A suitable embodiment of the light irradiating apparatus
according to the invention will be described below in detail with
reference to the drawings.
[0059] FIG. 1 is a schematic perspective view showing a main
construction of one embodiment of an ink jet printer 20 equipped
with a light irradiating apparatus according to the invention.
[0060] This printer 20 comprises a paper feed motor 30 for feeding
print paper P that is a recording medium, a platen 40, a print head
52 as a recording head for reducing a light curing type ink to fine
particle size and ejecting it to the print paper P, thereby
adhering it to the print paper P, a carriage 50 equipped with the
print head 52, a carriage motor 60 for moving the carriage 50 in a
main scanning direction, and a light irradiating apparatus 90 for
irradiating light of a specific wavelength region to an ink-adhered
surface of the print paper P to which the light curing type ink is
adhered by means of the print head 52.
[0061] The carriage 50 is towed by means of a tow belt 62 driven by
the carriage motor 60 and moves along a guide rail 64. The carriage
50 is equipped with a black cartridge 54 as a black ink container
accommodating a black ink supplied to the print head 52 and a color
ink cartridge 56 as a color ink container accommodating a color ink
supplied to the print head 52, as well as the print head 52.
[0062] A capping device 80 for sealing a nozzle surface of the
print head 52 at the time of stop is provided in a home position of
the carriage 50 (a position on a right side in FIG. 1). When a
printing job is ended and the carriage 50 reaches an upper part of
the capping device 80, the capping device 80 is automatically
lifted by means of a mechanism not shown to seal the nozzle surface
of the print head 52. By this capping, the ink in a nozzle can be
prevented from being dried. The positioning control of the carriage
50 is carried out, for example, in order to accurately place the
carriage 50 in the position of the capping device 80.
[0063] As shown in FIGS. 1 and 2, the light irradiating apparatus
90 comprises a plurality of light emitting elements 95 for emitting
light of a specific wavelength region, an element support means 91
for supporting these light emitting elements 95 in a line along the
width direction of the print paper P, brackets 92 and 93 for fixing
the element support means 91 to a housing of the printer 20, and a
light irradiating apparatus driving circuit 160 (see FIG. 3) for
controlling the light emission and light-out of the respective
light emitting elements 95.
[0064] The element support means 91 is a plate-shaped structural
member having a predetermined width W (see FIG. 2) along the
transfer direction of the print paper P in the printer 20 and a
predetermined length A (see FIG. 1) along the width direction of
the print paper P. The length A is set to be greater than the
maximum width of paper which can be handled in the printer 20.
[0065] The element support means 91 is disposed in parallel with a
surface of the print paper P which acts as a surface to be
irradiated with light, and fixed to the housing of the printer 20
by means of the brackets 92 and 93.
[0066] Then, a surface opposite to the surface of the print paper P
of the element support means 91 is an attachment surface 91a for
attaching the light emitting elements 95.
[0067] Further, a position in which the element support means 91 is
installed is a position apart from the print head 52 by a definite
distance downstream in the transfer direction of the print paper
P.
[0068] The brackets 92 and 93 fix ends of the element support means
91 to the housing of the printer 20 with a screw or through
concavo-convex fitting.
[0069] In the case of this embodiment, all of the light emitting
elements 95 emit light b in a specific wavelength region which is
effective for curing the light curing type ink ejected and applied
to the print paper P by the print head 52, and form elliptical
light images c on the surface of the print paper P, which is a
surface to be irradiated.
[0070] The elliptical light image c shows an irradiation area of
the light emitted from each light emitting element 95 on the print
paper P. Each light image c is in the same-sized form having a
major axis size of x and a minor axis size of y.
[0071] Further, in this specification, similarly to the slenderness
ratio of a rectangle, the ratio x/y of the major axis size x to the
minor axis size y of an ellipsoid is defined as the aspect ratio.
As each light emitting element 95, there is used one which gives an
elliptical light image c having an aspect ratio of 2.0 or more.
[0072] Further, on the attachment surface 91a of the element
support means 91, the light emitting elements 95 are arranged in a
line along the width direction of the print paper P, as shown in
FIG. 2.
[0073] The total number of the light emitting elements 95 installed
in a line on the attachment surface 91a is n. These n light
emitting elements 95 are mutually attached to the attachment
surface 91a at a predetermined arrangement space p so that the
light images c are made continuous along the major axis direction,
overlapping their end portions in the major axis direction one
another.
[0074] As a result, there is formed an approximately strip-shaped
irradiation area 98 in which the light images care alternately
arranged along the width direction of the print paper P.
[0075] This irradiation area 98 has a construction in which an
irradiation area 98a having a strong irradiation intensity formed
by overlapping the end portions of the light images c adjacent to
one another and an irradiation area 98b having a basic irradiation
density in the light images c are alternately arranged.
[0076] When the total number of the light emitting elements 95 used
is n, this irradiation area 98 is in an approximately strip-shaped
form having a size of L (L is nearly equal to np) in the width
direction of the print paper P and a size of y in the transfer
direction of the print paper P.
[0077] Further, in the case of this embodiment, semiconductor laser
elements are employed as the light emitting elements 95. In the
selection of the light emitting element, it is preferred to select
one in which the peak wavelength of light of a specific wavelength
region output from the semiconductor laser element is not
coincident with the absorption wavelength of the light absorbing
substance in the ultraviolet curing type ink.
[0078] For example, as a light emitting element which emits an
ultraviolet ray having a wavelength of 400 nm or less, there are
employable one having a model name of NDHU 110APAE2 (oscillation
wavelength: 370 to 380 nm) of a semiconductor laser diode series
manufactured by Nichia Corporation and the like, by way of
example.
[0079] On the other hand, as one which emits visible light having a
wavelength of 400 nm to 450 nm, there are employable ones having
model names of NDHV310APC and NDHV220APAE1 (oscillation wavelength:
400 to 415 nm) of a semiconductor laser diode series manufactured
by Nichia Corporation or one having a model name of NDHB20APAE1
(oscillation wavelength: 435 to 445 nm) an the like.
[0080] Then, the electric construction of the printer 20 will be
described with reference to FIG. 3. FIG. 3 is a block diagram
showing the electric construction of the printer 20. The printer 20
comprises a main control circuit 102, a CPU 104, and various
memories (an ROM 110, an RAM 112 and an EEPROM 114) connected to
the main control circuit 102 and the CPU 104 through buses.
[0081] To the main control circuit 102, there are connected an
interface circuit 120 for communicating a signal with an external
device such as a personal computer, a paper feed motor driving
circuit 130, a head driving circuit 140, a CR motor driving circuit
150, and a light irradiating apparatus driving circuit 160 for
controlling an operation of the light irradiating apparatus 90.
[0082] The paper feed motor 30 is driven by the paper feed motor
driving circuit 130 to rotate a paper feed roller 34, thereby
moving the print paper P in the transfer direction. The paper feed
motor 30 is provided with a rotary encoder 32, and a signal output
from the rotary encoder 32 is input to the main control circuit
102.
[0083] The print head 52 having a plurality of nozzles (not shown)
is provided on a bottom face of the carriage 50. Each nozzle is
driven by the head driving circuit 140 to eject droplets of the
ultraviolet curing type ink supplied from each cartridge 54 or 56
toward a recording medium such as paper, cloth or film.
[0084] The carriage motor 60 is driven by the CR motor driving
circuit 150. This printer 20 is provided with a linear encoder 70
for detecting the position and speed of the carriage 50 along the
main scanning direction. This linear encoder 70 is constituted by a
linear coding plate 72 provided in parallel with the main scanning
direction and a photo sensor 74 attached to the carriage 50. An
output signal from the linear encoder 70 is input to the main
control circuit 102.
[0085] The light irradiating apparatus driving circuit 160 controls
the light emission and light-out of the respective light emitting
elements 95, based on a control signal sent from the main control
circuit 102.
[0086] Specifically, when the print head 52 is driven to start
printing or when the printing operation is started and an adhered
surface of the ultraviolet curing type ink on the print paper P
reaches the irradiation area 98 of the light of a specific
wavelength region according to the light irradiating apparatus 90,
all of the light emitting elements 95 installed on the element
support member 91 are brought into a light emitting state, and the
light emitting state of the respective light emitting elements 95
is maintained until the adhered surface of the ultraviolet curing
type ink on the print paper P completely passes through the
irradiation area 98 of the light of a specific wavelength region
according to the light irradiating apparatus 90. That is to say,
the respective light emitting elements 95 are allowed to
continuously emit light until the adhered surface of the
ultraviolet curing type ink on the print paper P has passed through
the irradiation area 98 of the light of a specific wavelength
region according to the light irradiating apparatus 90.
[0087] The main control circuit 102 has the function of supplying a
control signal to the four driving circuits 130, 140, 150 and 160,
respectively, and also has the function of executing the decoding
of various print commands received by the interface circuit 120,
the control related to the regulation of print data, the monitoring
of various sensors, and the like. On the other hand, the CPU 104
has various functions for assisting the main control circuit 102,
and executes, for example, the control of various memories, and the
like.
[0088] In the light irradiating apparatus 90 described above, the
light emitting elements are arranged with spacing from one another
in the major axis direction of the light images c so that the
elliptical light images c formed by the respective light emitting
elements 95 are made continuous along the major axis direction of
the ellipsoids. Accordingly, there can be performed the light
irradiating process of forming the approximately strip-shaped
irradiation area 98 in which the light images c are continuously
arranged along the major axis direction, in the ink coating area on
the print paper P.
[0089] Then, compared to the case of the light irradiating
apparatus as shown in FIG. 4 in which the light emitting elements
are mutually arranged so that the elliptical light images c are
made continuous along the minor axis direction, the space p between
the light emitting elements adjacent to one another can be set
large. Further, as shown in FIG. 2 as the approximately
strip-shaped irradiation area 98, it becomes possible to irradiate
light of a specific wavelength region over the larger width L by
the smaller number of light emitting elements used.
[0090] Accordingly, when light of a specific wavelength region is
irradiated over a predetermined width of a surface to be
irradiated, it becomes possible to reduce the number of light
emitting elements used as light sources to lower cost.
[0091] The outgoing light from each light emitting element 95 is
turned to diffused light. Accordingly, when the attachment position
of the element support means 91 is adjusted to change the distance
between the light emitting element 95 and the surface to be
irradiated on the print paper P, the major axis size x and the
minor axis size y of the light image c change based on this.
[0092] When a semiconductor laser diode having a model name of NDHV
310APC (light diffusion in FWHM is (.theta..parallel.) 8.degree. in
the minor axis direction of the light image, and (.theta..perp.)
22.degree. in the major axis direction of the light image)
manufactured by Nichia Corporation was used and the distance
(irradiation distance) between the light emitting element 95 and
the surface to be irradiated on the print paper P was 30 mm in this
embodiment, the light image c had a major axis size x of 24.1 mm, a
minor axis size y of 9.95 mm and an aspect ratio of 2.20.
[0093] On the other hand, when the distance (irradiation distance)
between the same light emitting element and the surface to be
irradiated on the print paper P was 50 mm, the light image c had a
major axis size x of 39.1 mm, a minor axis size y of 15.5 mm and an
aspect ratio of 2.36.
[0094] Then, for the case of each irradiation distance, on the
assumption that the width of the print paper P is A4-size width,
and that the irradiation area 98 is formed fully in its paper
width, the number of light emitting elements needed was compared
between the case of the light emitting element arrangement shown in
FIG. 2 and the case of the element arrangement for comparison shown
in FIG. 4.
[0095] When the irradiation distance was 30 mm, the number of light
emitting elements needed was 9 for the element arrangement of the
embodiment shown in FIG. 2. In contrast, 22 light emitting elements
were needed for the element arrangement of the comparative example
shown in FIG. 4. It was confirmed that the number of elements could
be significantly decreased according to the above-mentioned
embodiment.
[0096] Further, when the irradiation distance was 50 mm, the number
of light emitting elements needed was 6 for the element arrangement
of the embodiment shown in FIG. 2. In contrast, 14 light emitting
elements were needed for the element arrangement of the comparative
example shown in FIG. 4. In this case, it was also confirmed that
the number of elements could be significantly decreased according
to the above-mentioned embodiment.
[0097] Furthermore, the space distance p between the light emitting
elements 95 as the light sources can be set large, so that heat
generated from the respective light emitting elements 95 becomes
difficult to be accumulated between the light emitting elements 95,
which can prevent the light emitting elements 95 themselves from
suffering from thermal damage due to the accumulated heat, thereby
being able to prevent a decrease in life of the light sources due
to their thermal damage.
[0098] Accordingly, when mounted on the periphery of the print head
52 of the ink jet printer 20 to cure by light irradiation the light
curing type ink adhered onto the print paper P as the recording
medium by means of the print head 52 of the printer 20, heat
generation of the light irradiating apparatus 90 itself can be
inhibited. It becomes therefore unnecessary to install a cooling
operation and means such as a cooling fun on the printer 20, which
also largely contributes to miniaturization of the ink jet printer
20 and cost reduction.
[0099] In addition, the light curing type ink can allow the curing
action to effectively proceed by the irradiation of an ultraviolet
ray having a specific wavelength. However, even when visible light
close to the ultraviolet ray is irradiated in place of the
ultraviolet ray, curing processing is possible although the
processing efficiency decreases, compared to the case of the
ultraviolet irradiation.
[0100] In general, a light emitting element which emits an
ultraviolet ray is more expensive than a light emitting element
which emits visible light.
[0101] Consequently, taking into account the difference in price
between the light emitting element for an ultraviolet ray and the
light emitting element for visible light, the processing speed
required and the like, the adoption of the light emitting element
for visible light which is low in price is also appropriately set.
This makes it possible to provide the light irradiating apparatus
90 well balanced in cost and performance.
[0102] Further, in the light curing type ink, the difference occurs
in the wavelength region of light absorbed when irradiated,
depending on the difference in composition of a color material
component (pigment, dye or the like) and other components. This
causes the occurrence of the difference in curing time of the ink
in some cases.
[0103] Consequently, light irradiation in a wide wavelength region
having a plurality of light emitting peaks becomes possible by
using light emitting elements different in the light emitting
wavelength peak in the arrangement of the plurality of light
emitting elements, like the above-mentioned embodiment. Even when
light of a part of the light emitting peaks is absorbed, light of
the other light emitting peaks effectively contributes to curing of
the ink to make it possible to stably maintain the curing
efficiency of the ink. Thus, it becomes possible that irradiating
light to be absorbed complies with various kinds of light curing
type inks different in the light emitting wavelength peak. As a
result, the ink species to be complied with can be increased to
improve the versatility as the light emitting apparatus 90.
[0104] When the aspect ratio of the elliptical light images c is
set to 2.0 or more like this embodiment, the difference in an
arrangement space between the light emitting elements between the
case where the elliptical light images c are arranged along the
major axis direction and the case where they are arranged along the
minor axis direction becomes extremely significant, compared to the
case where light emitting elements which form elliptical light
images c having an aspect ratio of less than 2.0 are employed. A
reduction in the number of the light emitting elements 95 used as
the light sources and broadening of the space between the light
emitting elements 95 assist diffusion of heat generated by the
light emitting elements 95, and the effect of preventing the light
emitting elements 95 from deteriorating by thermal damage due to
accumulated heat becomes clear.
[0105] Further, when the semiconductor laser element is employed as
the light emitting element 95 like this embodiment, outgoing light
forms an elliptical light image c for structural reasons of the
element itself such as a semiconductor laser diode that is a
semiconductor laser, and it becomes possible to obtain the
elliptical light image c effective for enlargement of the space
between the light emitting elements 95 without using a special
optical means.
[0106] Furthermore, in light emission by the semiconductor laser
element, outgoing light diffuses compared to light emission of a
solid laser, so that the wider area can be irradiated with a light
beam by one light emitting element 95. This is therefore suitable
for decreasing the light emitting elements used, and at the same
time, a combination with a scanning mechanism for enlarging the
irradiation area of a light beam becomes unnecessary. This makes it
possible to secure the wide irradiation area of the light beam at a
low price.
[0107] In addition, installation of the scanning mechanism becomes
unnecessary, so that such a construction that the light emitting
element 95 is attached to a movable part for scanning becomes
unnecessary. Accordingly, it becomes possible to improve
operational reliability and durability as the light irradiating
apparatus 90 by employing design excluding the movable part which
causes malfunction.
[0108] In the above-mentioned embodiment, the light emitting
elements 95 were arranged in a line. However, they may be arranged
in a plurality of lines parallel to each other. By arranging the
light emitting elements in a plurality of lines parallel to each
other, the whole irradiating area can be set to an arbitrary size
along the transfer direction of the print paper P without being
restricted by the major axis size x and the minor axis size y of
the elliptical light image formed by the single light emitting
element, and by increasing the number of light emitting element
lines to enlarge the irradiating area of light in the transfer
direction of the recording medium, the speeding up of processing
can be achieved.
[0109] Further, the continuous state of the elliptical light images
c along the width direction of the print paper P may be as shown in
FIG. 5.
[0110] Furthermore, it is desirable to select the light emitting
wavelength of the semiconductor laser element used as the light
emitting element in the invention according to characteristics of
the light curing type ink to be treated. Depending on
characteristics of the light curing type ink, it is possible to
select a suitably usable one, other than those having the light
emitting wavelengths shown in the above-mentioned embodiment.
[0111] In addition, the light emitting element which can be used in
the invention is not limited to the semiconductor laser element.
Any light emitting element other than the semiconductor laser
element can also be used, as long as it is an element in which a
light flux emitted from the element is turned to diffused light to
be able to form an elliptical light image.
[0112] Further, even when the light emitting element line is formed
by light emitting elements which emit light of an approximately
similar wavelength region, the light emitting element line can be
formed by only those having the same light emitting wavelength
peak, or by mixing those different in the light emitting wavelength
peak.
[0113] Furthermore, in the above-mentioned embodiment, the light
emitting element 95 in the light irradiating apparatus 90 is
allowed to achieve continuous light emission during print
processing. However, the light emitting element 95 may be allowed
to achieve pulse light emission by a predetermined time unit so as
to restrain the amount of light irradiated to the light curing type
ink to the bare minimum, based on the characteristics of the light
curing type ink used or the information of a print region (such as
the amount of the light curing type ink applied by ejection).
[0114] Thereby, the amount of light irradiated to the light curing
type ink is controlled to the bare minimum to be able to achieve a
reduction in power consumption in the light irradiating apparatus
90, a reduction in heat generation of the light emitting element
95, and prolongation of life by shortening the actual working hours
of the light emitting element 95.
[0115] An instrument to be equipped with the light irradiating
apparatus of the invention is not limited to the ink jet printer.
It can be installed on various instruments which perform adhesion
of the light curing type ink.
[0116] Further, as materials for the recording medium to which
light of a specific wavelength region is irradiated by the light
emitting apparatus of the invention, there are considered various
ones such as paper, film, fabric and thin metal plate.
[0117] The light curing type inks which are curable by the light
emitting apparatus of the invention are not particularly limited
to, but include well-known inks described, for example, in
JP-A-3-216379, JP-A-5-186725, JP-B-5-54667, JP-A-6-200204,
JP-A-7--224241, JP-A-8-48922, JP-A-8-218016, JP-A-10-7956,
JP-A-10-250052, JP-A-10-324836, JP-A-2000-44857, JP-A-2000-119574,
JPA-2000-158793, JP-A-2000-186242, JP-A-2000-186243,
JP-A-2000-336295, JP-T-2000-504778 (the term "JP-T" as used herein
means a published Japanese translation of a PCT patent
application), JP-T-2001-512777, JP-A-2001-220526, JP-A-2002-80767,
JP-A-2003-191593, JP-A-2003-191594, JPA-2003-313476,
JP-A-2004-27154 and U.S. Pat. No. 5,623,001.
[0118] Of these, particularly preferred is one which contains at
least a polymerizable compound, a photopolymerization initiator and
a polymerization accelerator, and contains an N-vinyl compound as
the polymerizable compound and two or more selected from the group
consisting of a bisacyiphosphine oxide, monoacylphosphine oxide and
an .alpha.-aminoketone as the photo-polymerization initiator.
[0119] All of the bisacylphosphine oxide, monoacylphosphine oxide
and .alpha.-amino ketone used in the above-mentioned ink
composition absorb light having a wavelength of 365 nm or more. In
particular, the bisacylphosphine oxide and monoacylphosphine oxide
have absorption in a longer wavelength range than the .alpha.-amino
ketone.
[0120] The bisacylphosphine oxides include, for example,
bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and the like,
which is available as the trade name of Irgacure 819 (manufactured
by Ciba Specialty Chemicals).
[0121] The monoacylphosphine oxides include, for example,
2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and the like, which
is available as the trade name of Darocur TPO (manufactured by Ciba
Specialty Chemicals).
[0122] The .alpha.-amino ketones include, for example,
2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 and the
like, which is available as the trade name of Irgacure 369
(manufactured by Ciba Specialty Chemicals).
[0123] In the above-mentioned light curing type ink, another
photopolymerization initiator may be used in combination, as long
as the ink composition contains at least two or more of the
above-mentioned compounds as the photopolymerization initiator.
[0124] Typical examples of the other photopolymerization initiators
which may be used in combination include benzoin methyl ether,
benzoin ethyl ether, isopropyl benzoin ether, isobutyl benzoin
ether, 1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime, benzil,
diethoxyacetophenone, benzophenone, chlorothioxanthone,
2-chlorothioxanthone, isopropylthioxanthone, diethylthioxanthone,
2-methylthioxanthone, polychlorinated polyphenyl, hexachlorobenzene
and the like. Preferred are isobutyl benzoin ether and
1-phenyl-1,2-propanedione-2-(o-ethoxycarbonyl)oxime.
[0125] Further, there can also be used photopolymerization
initiators available as trade names of Vicure 10 and 30
(manufactured by Stauffer Chemical), Irgacure 127, 184, 500, 651,
2959, 907, 379, 754, 1700, 1800 and 1850, OXE01, Darocure 1173 and
ITX (manufactured by Ciba Specialty Chemicals), Quantacure CTX and
ITX (manufactured by Aceto Chemical), Kayacure DETX-S (manufactured
by Nippon Kayaku Co., Ltd.), ESACURE KI150 (manufactured by
Lamberti), and Lucirin TPO (manufactured by BASF).
[0126] As the polymerizable compound contained in the light curing
type ink, what is necessary is just to contain at least an N-vinyl
compound.
[0127] The N-vinyl compounds include N-vinylformamide,
N-vinylcarbazol, N-vinylacetamide, N-vinylpyrrolidone,
N-vinylcaprolactam, derivatives thereof and the like.
[0128] Further, the light curing type ink may contain another
polymerizable compound other than the N-vinyl compound, as the
polymerizable compound.
[0129] The other polymerizable compound is not particularly
limited, as long as it is polymerized by radicals or ions formed
from the photopolymerization initiator. Such a polymerizable
compound means a molecule which can be a constitutional unit of a
basic structure of a polymer. Such a polymerizable compound is also
referred to as a photopolymerizable monomer, and includes a
monofunctional monomer, a bifunctional monomer, and a
polyfunctional monomer.
[0130] As typical examples of such polymerizable compounds, the
monofunctional monomers include
(2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate,
(2-methyl-2-isobutyl-1,3-dioxolan-4-yl)methyl acrylate,
phenoxyethyl acrylate, isobornyl acrylate, methoxydiethylene glycol
monoacrylate, acryloylmorpholine, lauryl methacrylate, allyl
glycol, 2-hydroxyethyl methacrylate, cyclohexyl methacrylate,
oxetane methacrylate and the like.
[0131] The bifunctional monomers include ethylene glycol
dimethacrylate, diethylene glycol diacrylate, diethylene glycol
dimethacrylate, tripropylene glycol diacrylate, 1,9-nonanediol
diacrylate, polyethylene glycol #400 di-acrylate, tetraethylene
glycol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol
dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol
dimethacrylate, 2-hydroxy-1,3-dimethacryloxypropane,
hydroxypioperinoic acid ester neopentyl glycol diacrylate and the
like.
[0132] The polyfunctional monomers include trimethylolpropane
triacrylate, trimethylolpropane trimethacrylate, trimethylolpropane
EO-adduct triacrylate, trimethylolpropane PO-adduct triacrylate,
glycerin EO-adduct triacrylate, glycerin EO-modified triacrylate,
glycerin PO-adduct triacrylate, pentaerythritol triacrylate,
dipentaerythritol hexaacrylate, (2,2,2-triacryloyloxymethyl)ethyl
hydrogen phthalate, dipentaerythritol polyacrylate and the
like.
[0133] Of the above-mentioned monofunctional monomers, bifunctional
monomers and polyfunctional monomers used in combination as
monomers other than the N-vinyl compound, preferred are
acryloylmorpholine (monofunctional monomer), phenoxyethyl acrylate
(monofunctional monomer), tripropylene glycol diacrylate
(bifunctional monomer), (2,2,2-triacryloyloxymethyl)ethyl hydrogen
phthalate (polyfunctional monomer) and glycerin EO-modified
triacrylate (polyfunctional monomer). However, the invention is not
limited to these combined uses.
[0134] As the polymerization accelerator contained in the light
curing type ink, what is necessary is just to contain fine
particles having at least a polymerizable functional group.
[0135] The polymerization acceleration mechanism of the fine
particles onto which polymerizable functional groups are introduced
is not clear but is presumed that radicals formed from the
photopolymerization initiator which has absorbed an ultraviolet ray
and has cleaved are trapped and stabilized on surfaces of the fine
particles and easily initiate the polymerization with the
polymerizable functional groups introduced onto the surfaces of the
fine particles and the polymerizable compound adsorbed on the
surfaces, thereby accelerating the polymerization reaction.
[0136] The polymerizable functional group-containing fine particles
are not particularly limited but are those generally referred to as
extenders. Inorganic compounds such as silica, alumina, titanic and
calcium oxide are exemplified. In particular, transparent ones such
as silica and alumina can be suitably used, and silica is
particularly preferred among others.
[0137] Further, the polymerizable functional group contained in the
fine particles is not particularly limited, and an acryloyl group,
a methacryloyl group or the like is exemplified. Furthermore, it is
also possible to use a polymerizable functional group having one or
more double bonds.
[0138] The size of the fine particles is not particularly limited,
but preferred are those having a particle size of 10 to 200 nm.
[0139] Although a method for preparing the polymerizable functional
group-containing fine particles is not particularly limited, there
is mentioned a method comprising preparing silica fine particles
having a large number of hydroxyl groups by a sol-gel reaction of a
silane compound such as tetraethoxysilane, and then, reacting them
with a compound capable of imparting polymerizable functional
groups to the hydroxyl groups (silane coupling agent).
[0140] The content of the polymerizable functional group-containing
fine particles in the light curable ink composition is not
particularly limited, and should be suitably selected depending on
the type of usage, the conditions, the relation between the
viscosity and polymerizability of the ink composition, and the
like. However, it is preferably 10% by weight or less based on the
whole amount of the ink composition.
[0141] Further, the light curing type ink may contain one other
than the polymerizable fine particles as a polymerization
accelerator.
[0142] Although the other polymerizable compound is not
particularly limited, an aminobenzoate derivative is particularly
preferred in view of an odor problem and more reliable curing of
the ink composition. This is because the aminobenzoate derivative
reduces polymerization inhibition induced by oxygen.
[0143] The aminobenzoate derivative does not have absorption in a
wavelength range of 350 nm or more. Examples of such aminobenzoate
derivatives are not particularly limited, but include ethyl
4-dimethylaminobenzoate and 2-ethylhexyl 4-dimethylaminobenzoate,
which are available as trade names of Darocur EDB and EHA
(manufactured by Ciba Specialty Chemicals).
[0144] The light curable ink composition contains a color
material.
[0145] The color material contained in the light curable ink
composition may be either a dye or a pigment. However, when
permeation of a coloring component in the ink composition is
restrained by the action of insolubilization or thickening of the
ink composition, the pigment dispersed in the ink is more
advantageous than the dye dissolved in the ink. Further, the
pigment is more advantageous in view of image durability of printed
matter.
[0146] As the dyes used in the light curable ink composition, there
can be used various dyes usually used in inkjet recording, such as
a direct dye, an acid dye, a food dye, a basic dye, a reactive dye,
a disperse dye, a vat dye, a soluble vat dye, and a reactive
disperse dye.
[0147] As the pigment used in the above-mentioned light curing type
ink, an inorganic pigment or an organic pigment can be used without
particular limitation.
[0148] As the inorganic pigment, there can be used carbon black
produced by known processes such as a contact process, a furnace
process and a thermal process, in addition to titanium oxide and
iron oxide. Further, as the organic pigment, there can be used an
azo pigment (including an azo lake, an insoluble azo pigment, a
condensed azo pigment, a chelate azo pigment and the like), a
polycyclic pigment (including a phthalocyanine pigment, a perylene
pigment, a perynone pigment, an anthraquinone pigment, a
quinacrydone pigment, a dioxazine pigment, a thioindigo pigment, an
isoindolinone pigment, a quinofuralone pigment and the like), a dye
chelate (including a basic dye type chelate, an acid dye type
chelate and the like), a nitro pigment, a nitroso pigment, aniline
black and the like.
[0149] As specific examples of the pigments, carbon blacks include
No. 2300, No. 900, MCF88, No. 33, No. 40, No. 45, No. 52, MA 7, MA
8, MA 100, No. 2200B and the like manufactured by Mitsubishi
Chemical Corp.; Raven 5750, 5250, 5000, 3500, 1255 and 700, and the
like manufactured by Columbia; Regal 400R, 330R and 660R, Mogul L
and 700, Monarch 800, 880, 900, 1000, 1100, 1300 and 1400, and the
like manufactured by Cabot; and Color Black FW1, FW2, FW2V, FW18
and FW200, Color Black S150, 5160, and 5170, Printex 35, U, V, and
1401Y, Special. Black 6, 5, 4A, and 4, and the like manufactured by
Degussa.
[0150] The pigments used in a yellow ink include C. I. Pigment
Yellow 1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98,
109, 110, 114, 128, 129, 138, 150, 151, 154, 155, 180, 185 and the
like.
[0151] Further, the pigments used in a magenta ink include C. I.
Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57:1, 112, 122,
123, 168, 184, 202 and 209, C. I. Pigment Violet 19 and the
like.
[0152] Furthermore, the pigments used in a cyan ink include C. I.
Pigment Blue 1, 2, 3, 15:3, 15:4, 60, 16, 22 and the like.
[0153] According to a preferred embodiment of the light curable
ink, the average particle size of the pigment is preferably in the
range of 10 to 200 nm, and more preferably about 50 to 150 nm.
[0154] The amount of the color material added in the ink
composition is preferably in the range of about 0.1 to 25% by
weight, and more preferably in the range of about 0.5 to 15% by
weight.
[0155] According to a preferred embodiment of the light curable
ink, the pigment is preferably added to the ink composition as a
pigment dispersion obtained by dispersing it in an aqueous medium
with a dispersant or a surfactant. As the preferred dispersant,
there can be used a dispersant conventionally used for preparing a
pigment dispersion, for example, a polymer dispersant. It will be
obvious for those skilled in the art that the dispersant and
surfactant contained in the pigment dispersion also functions as a
dispersant and surfactant for the ink composition.
[0156] Specific examples thereof include polymer dispersants such
as polyacrylic acid, a polyacrylic acid-styrene copolymer, a
polyester, a polyurethane, polyvinyl chloride, a polyvinyl
chloride-vinyl acetate copolymer, vinyl chloride-modified
polyacrylic acid, a polyoxyalkylene-added polyalkyleneamine and
polyvinyl butyral, silicone-based surfactants such as
polyester-modified polydimethylsiloxane and polyether-modified
polydimethylsiloxane, acetylene diol-based surfactants,
sorbitan-based surfactants and the like.
[0157] The light curable ink may contain an aqueous solvent.
Further, as optional components, there may be added a resin
emulsion, an inorganic oxide colloid, a wetting agent, a pH
regulator, a pesticide, a biocide and the like.
[0158] Further, it is preferred that the ink light curable ink
composition does not contain any organic solvent to be a
non-solvent type ink composition.
EXAMPLES
[0159] The present invention will be illustrated in greater detail
with reference to the following Examples, but the invention should
not be construed as being limited thereto.
[0160] 1. Preparation of Polymerizable Fine Particles 1A and
Dispersion Thereof
[0161] To a 200-mL Erlenmeyer flask was added 88.1 parts by weight
of a silica sol IPA-ST (an isopropyl alcohol (hereinafter
abbreviated as "IPA") dispersion having a silica concentration of
30% by weight, manufactured by Nissan Chemical Industries, Ltd.),
and then, 7.9 parts by weight of a silane coupling agent, Sila-Ace
S710 (3-methacryloxypropyltrimethoxysilane, manufactured by Chisso.
Corp.) was added thereto. While stirring with a magnetic stirrer, 4
parts by weight of hydrochloric acid having a concentration of 0.05
mol/L was added, and the reaction was carried out with stirring at
room temperature for 24 hours. As a result, IPA Dispersion A
containing methacryl group-containing polymerizable fine particles
1A (MPS) was obtained.
[0162] To a 300-mL round-bottom flask were added 70 parts by weight
of N-vinylformamide (hereinafter also referred to as "NVF", Beam
Set 770, manufactured by Arakawa Chemical Industries, Ltd.) and 100
parts by weight of the above-mentioned dispersion A, and then, IPA
was removed by evaporation using a rotary evaporator to obtain
dispersion B containing polymerizable fine particles 1A in an
amount of 30% by weight.
[0163] 2. Preparation of Pigment Dispersions
[0164] 2-1. (Yellow) Pigment Dispersion C
[0165] C. I. Pigment Yellow (P. Y.) 74 as a pigment that is a color
material, a polyurethane resin (average molecular weight; about
20,000) (herein after also referred to as "dispersant"), and NVF
were mixed at a ratio of pigment:dispersant:NVF=15:5:80 and
dispersed in a sand mill (manufactured by Yasukawa Seisakusho)
together with glass beads (diameter: 1.7 mm, 1.5 times the weight
of the mixture) for 2 hours. Thereafter, the glass beads were
separated to prepare pigment dispersion C (pigment concentration:
15% by weight).
[0166] 2-2. (Magenta) Pigment Dispersion D
[0167] Pigment dispersion D (pigment concentration: 15% by weight)
was prepared in the same manner as in the case of the
above-mentioned pigment dispersion C with the exception that the
pigment was changed to C. I. Pigment Red (P. R.) 122.
[0168] 2-3. (Cyan) Pigment Dispersion E
[0169] Pigment dispersion E (pigment concentration: 15% by weight)
was prepared in the same manner as in the case of the
above-mentioned pigment dispersion C with the exception that the
pigment was changed to C. I. Pigment Blue (P. B.) 15:3.
[0170] 2-4. (Black) Pigment Dispersion F
[0171] Pigment dispersion F (pigment concentration: 15% by weight)
was prepared in the same manner as in the case of the
above-mentioned pigment dispersion C with the exception that the
pigment was changed to C. I. Pigment Black (P. Bk.) 7.
[0172] 3. Preparation of Ink Compositions
[0173] 3-1. Yellow Pigment Ink Composition (Y)
[0174] To a vessel having light shielding properties were added 20
parts by weight of dispersion B and 10 parts by weight of pigment
dispersion C, and then, 29 parts by weight of NVF, 25 parts by
weight of tripropylene glycol diacrylate (hereinafter also referred
to as "TPGDA", Aronix M-220, manufactured by Toagosei Co., Ltd.),
10 parts by weight of glycerin EO-modified triacrylate (hereinafter
also referred to as "AGE3", HK Ester A-Gly-3E, manufactured by
Shin-Nakamura Chemical Corp.), 4.0 parts by weight of Irgacure 819
(bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, manufactured by
Ciba Specialty Chemicals), 1.0 part by weight of Irgacure 369
(2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,
manufactured by Ciba Specialty Chemicals) and 1 part by weight of
Darocur EHA (2-ethylhexyl-4-dimethoxyaminobenzoate, manufactured by
Ciba Specialty Chemicals) were added, followed by stirring and
mixing with a magnetic stirrer for 1 hour. Then, the mixture was
filtrated through a 5-.mu.m membrane filter under an environment
shielded from ultraviolet rays to prepare a yellow ink composition
having the following composition.
TABLE-US-00001 NVF 51 wt % TPGDA 25 wt % AGE3 10 wt % Dispersant
0.5 wt % Irgacure 819 4.0 wt % Irgacure 369 1.0 wt % Darocur EHA
1.0 wt % Polymerizable Fine Particles 1 6.0 wt % C.I. Pigment
Yellow 74 (color material) 1.5 wt %
[0175] 3-2. Magenta, Cyan, Black Pigment Ink Compositions
[0176] Similarly hereinafter, respective ink compositions having
the following composition were prepared using dispersion D, E and
F, respectively, instead of dispersion C.
TABLE-US-00002 Magenta Pigment Ink Composition (M) NVF 51 wt %
TPGDA 25 wt % AGE3 10 wt % Dispersant 0.5 wt % Irgacure 819 4.0 wt
% Irgacure 369 1.0 wt % Darocur EHA 1.0 wt % Polymerizable Fine
Particles 1 6.0 wt % C.I. Pigment Red 122 (color material) 1.5 wt
%
TABLE-US-00003 Cyan Pigment Ink Composition (C) NVF 51 wt % TPGDA
25 wt % AGE3 10 wt % Dispersant 0.5 wt % Irgacure 819 4.0 wt %
Irgacure 369 1.0 wt % Darocur EHA 1.0 wt % Polymerizable Fine
Particles 1 6.0 wt % C.I. Pigment Blue 15:3 (color material) 1.5 wt
%
TABLE-US-00004 Black Pigment Ink Composition (K) NVF 51 wt % TPGDA
25 wt % AGE3 10 wt % Dispersant 0.5 wt % Irgacure 819 4.0 wt %
Irgacure 369 1.0 wt % Darocur EHA 1.0 wt % Polymerizable Fine
Particles 1 6.0 wt % C.I. Pigment Black 7 (color material) 1.5 wt
%
[Curing Test]
[0177] Each of the above-mentioned ink compositions was dropped on
a glass substrate in an amount of about 0.05 mL, and a curing test
was carried out. The ultraviolet irradiation was performed by
combining the following two irradiating apparatuses. After curing
treatment was carried out under curing conditions of an irradiating
time of 15 seconds, curability was visually evaluated. As a result,
it was confirmed that all of the four color ink compositions were
well cured.
[0178] Irradiating Apparatus 1:
[0179] Light source: Ultraviolet LD NDHU110APAE2 (manufactured by
Nichia Corp.)
[0180] Peak Wavelength: 370 to 380 nm
[0181] Rated Output: 10 mW
[0182] Irradiating Apparatus 2:
[0183] Light source; LD NDHU110APAE2 (manufactured by Nichia
Corp.)
[0184] Peak Wavelength: 400 to 415 nm
[0185] Rated Output: 60 mW
[0186] While the present invention has been described in detail and
with reference to specific embodiments thereof, it will be apparent
to one skilled in the art that various changes and modifications
can be made therein without departing from the spirit and scope
thereof.
[0187] This application is based on Japanese Patent Application
Nos. 2005-200301 (tiled July 8, 2005) and 2006-058695 (filed Mar.
3, 2006), and the contents thereof are herein incorporated by
reference.
* * * * *