U.S. patent number RE41,985 [Application Number 12/314,441] was granted by the patent office on 2010-12-07 for gloss-imparting device and color image-forming apparatus.
This patent grant is currently assigned to Fuji Xerox Co., Ltd.. Invention is credited to Osamu Ide, Yu Tsuda.
United States Patent |
RE41,985 |
Ide , et al. |
December 7, 2010 |
Gloss-imparting device and color image-forming apparatus
Abstract
A gloss-imparting device for imparting a gloss on a color image,
the gloss-imparting device has a transparent toner image-carrying
body, a transparent toner image-forming unit, a
heating/pressurizing unit, and a cooling/releasing unit. The
transparent toner image-carrying body carries a transparent toner
image formed of a transparent toner thereon. The transparent toner
image-forming unit forms the transparent toner image on the
transparent toner image-carrying body. The heating/pressurizing
unit heats and pressurizes the transparent toner image and the base
material to bring them into contact. The cooling/releasing unit
cools the transparent toner image and releases the base material
from the transparent toner image-carrying body. The transparent
toner image is transferred and fixed onto the base material by the
heating/pressurizing unit.
Inventors: |
Ide; Osamu (Ashigarakami-gun,
JP), Tsuda; Yu (Ashigarakami-gun, JP) |
Assignee: |
Fuji Xerox Co., Ltd. (Tokyo,
JP)
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Family
ID: |
18988564 |
Appl.
No.: |
12/314,441 |
Filed: |
December 10, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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10141853 |
May 10, 2002 |
7180631 |
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Reissue of: |
11653265 |
Jan 16, 2007 |
07321449 |
Jan 22, 2008 |
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Foreign Application Priority Data
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May 11, 2001 [JP] |
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2001-142223 |
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Current U.S.
Class: |
358/1.9;
428/32.33; 358/2.1 |
Current CPC
Class: |
G03G
15/6585 (20130101); G03G 15/2064 (20130101); G03G
15/2025 (20130101); G03G 21/206 (20130101); G03G
2215/0174 (20130101); G03G 2215/00805 (20130101); G03G
2215/2016 (20130101); G03G 2215/2032 (20130101); G03G
15/2017 (20130101) |
Current International
Class: |
G06K
15/00 (20060101); B41M 5/40 (20060101) |
Field of
Search: |
;430/138,45 ;427/359
;428/195,32.23,195.1 ;399/39 ;358/1.9,2.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0349227 |
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Jan 1990 |
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EP |
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0349227 |
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Jan 1990 |
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EP |
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A 63-58374 |
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Mar 1988 |
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JP |
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A 63-259575 |
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Oct 1988 |
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JP |
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A 3-2765 |
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Jan 1991 |
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JP |
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A 03-267955 |
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Nov 1991 |
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JP |
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A 4-204670 |
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Jul 1992 |
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JP |
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A 4-278967 |
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Oct 1992 |
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JP |
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A 5-142963 |
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Jun 1993 |
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JP |
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A 5-158364 |
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Jun 1993 |
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JP |
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A 5-232840 |
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Sep 1993 |
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JP |
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A 7-72696 |
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Mar 1995 |
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JP |
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A 10-319755 |
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Dec 1998 |
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JP |
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09159020 |
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Jan 1999 |
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JP |
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A-09-159020 |
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Jan 1999 |
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JP |
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A 11-202583 |
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Jul 1999 |
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JP |
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A 2000-147863 |
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May 2000 |
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JP |
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Other References
US. Pat. No. 5,032,440 , withdrawn. cited by other .
U.S. Patent No. 5,009,945, withdrawn. cited by other.
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Primary Examiner: Grant, II; Jerome
Attorney, Agent or Firm: Oliff & Berridge, PLC
Parent Case Text
This is a Continuation of application Ser. No. 10/141,853 filed May
10, 2002 now U.S. Pat. No. 7,180,681. The disclosure of the prior
application is hereby incorporated by reference herein in its
entirety.
Claims
What is claimed is:
1. A color image forming apparatus for forming a color image with a
gloss, the color image forming apparatus comprising: a color toner
image forming unit that forms a color toner image on a base
material; a transparent toner image forming unit that forms a
transparent toner image on the color image on the base material; a
heating/pressurizing unit that heats and pressurizes the
transparent toner image, the color toner image and the base
material; and a cooling unit that cools at least the transparent
toner image heated and pressurized by the heating/pressurizing
material.
.Iadd.2. A color image forming apparatus comprising: a color toner
image forming device comprising a photoreceptor and a developing
unit that forms a color toner image on the photoreceptor, the color
toner image being placed on a recording medium; a transparent toner
image forming device comprising a photoreceptor and a developing
unit that forms a transparent toner image on the photoreceptor, the
transparent toner image being placed on the color toner image on
the recording medium; a fuser comprising a fixing rotatable body
and a pressure rotatable body, at least the fixing rotatable body
is provided with a heater; and a cooler located downstream of a nip
between the fixing rotatable body and the pressure rotatable body
of the fuser in a processing direction of the image formation, the
cooler cooling the transparent toner image, color toner image and
the recording medium that have been heated and pressurized by the
fuser..Iaddend.
.Iadd.3. A color image forming apparatus comprising: a color toner
image forming device comprising a photoreceptor and a developing
unit that forms a color toner image on the photoreceptor, the color
toner image being placed on a recording medium; a transparent toner
image forming device comprising a photoreceptor and a developing
unit that forms a transparent toner image on the photoreceptor, the
transparent toner image being placed on the color toner image on
the recording medium; a fuser comprising a fixing roller and a
pressure roller, at least the fixing roller is provided with a
heater; and a cooler located downstream of a nip between the fixing
roller and the pressure roller of the fuser in a processing
direction of the image formation, the cooler cooling the
transparent toner image, color toner image and the recording medium
that have been heated and pressurized by the fuser..Iaddend.
.Iadd.4. A color image forming apparatus comprising: a color toner
image forming device comprising a photoreceptor, a developing unit
and an intermediate transfer member, the developing unit forming a
color toner image on the photoreceptor, the color toner image being
transferred to the intermediate transfer member and further being
transferred onto a recording medium; a transparent toner image
forming device comprising a photoreceptor, a developing unit and an
intermediate transfer member, the developing unit forming a
transparent toner image on the photoreceptor, the transparent toner
image being transferred to the intermediate transfer member and
further being transferred onto the color toner image on the
recording medium; a fuser comprising a fixing rotatable body and a
pressure rotatable body, at least the fixing rotatable body is
provided with a heater; and a cooler located downstream of a nip
between the fixing rotatable body and the pressure rotatable body
of the fuser in a processing direction of the image formation, the
cooler cooling the transparent toner image, color toner image and
the recording medium that have been heated and pressurized by the
fuser..Iaddend.
.Iadd.5. A color image forming apparatus comprising: a color toner
image forming device comprising a photoreceptor, a developing unit
and an intermediate transfer member, the developing unit forming a
color toner image on the photoreceptor, the color toner image being
transferred to the intermediate transfer member and further being
transferred onto a recording medium; a transparent toner image
forming device comprising a photoreceptor, a developing unit and an
intermediate transfer member, the developing unit forming a
transparent toner image on the photoreceptor, the transparent toner
image being transferred to the intermediate transfer member and
further being transferred onto the color toner image on the
recording medium; a fuser comprising a fixing roller and a pressure
roller, at least the fixing roller is provided with a heater; and a
cooler located downstream of a nip between the fixing roller and
the pressure roller of the fuser in a processing direction of the
image formation, the cooler cooling the transparent toner image,
color toner image and the recording medium that have been heated
and pressurized by the fuser..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a color image-forming apparatus
for forming a color image by electrophotography, electrostatic
recording, or the like and, more particularly, a color
image-forming apparatus capable of forming color images with a high
gloss.
2. Description of the Related Art
In the related art, in the color image-forming apparatus of this
type for forming color images by electrophotography, electrostatic
recording, or the like, if the color image is formed on a base
material, for example, if the color copy is taken, the following
image forming steps are carried out. That is, light is irradiated
onto a color document, then the reflected-light image is read and
color-separated by a color scanner, then predetermined image
processing and color correction are applied by an image processing
device, then the semiconductor laser or the like is modulated based
on the resultant image signal of plural colors to emit a laser beam
from the semiconductor laser or the like modulated in response to
the image signal. A plurality of electrostatic latent images are
formed by irradiating the laser beam onto an inorganic
photoreceptor made of Se, amorphous silicon, or the like or an
organic photoreceptor, which employs phthalocyanine pigment,
bis-azo pigment, or the like as the charge generating layer, plural
times color by color. A plurality of electrostatic latent images
formed on the inorganic or organic photoreceptor are developed
sequentially by four-color toners consisting of yellow (Y), magenta
(M), cyan (C), and black (K), for example. Then, the formation of
the color image on the base material is carried out by transferring
the developed toner image from the inorganic or organic
photoreceptor to the base material such as paper and then
heating/fixing the image by a fixing device such as a
thermally-fixing roller, or the like.
The color toner employed in such color image-forming apparatus is
fabricated by adhering the fine grains, which have an average
diameter of about 5 to 100 nm, onto the particles, which have an
average particle diameter of 1 to 15 .mu.m. For example, such fine
grains are inorganic fine grains made of silicon oxide, titanium
oxide, aluminum oxide, etc. or finely divided resins made of PMMA,
PVDF, etc. For example, such particles are prepared by dispersing a
coloring agent into a binding resin that are formed of polyester
resin, styrene/acryl copolymer, styrene/butadiene copolymer, or the
like. Also, for example, the above coloring agents are benzidine
yellow, quinoline yellow, Hansa yellow, etc. for the yellow (Y)
toner, Rhodamine B, rose Bengal, pigment red, etc. for the magenta
(M) toner, phthalocyanine blue, aniline blue, pigment blue, etc.
for the cyans (C) toner, and carbon black, aniline black, blend of
color pigments for the black (K) toner.
The surface of the color image has a gloss to some extent since
such surface of the color image being formed of the above color
toner is smoothed in heating/fixing, while normally the surface of
the paper does not have a gloss. Thus, the color image has a
glossiness that is different from the surface of the paper. Also,
it is known that the viscosity of the toner is changed in
heating/fixing according to type of a binding resin used in the
color toner, the heating/fixing system, etc. and thus the
glossiness of the color image is changed.
Meanwhile, the taste in glossiness of the color image is different
according to the type of the image, the purpose in use, etc., and a
variety of tastes in glossiness are present. In the case of a
photographic print such as a portrait, a scenery, etc., normally
there is a tendency that an image with a high gloss is preferred
from the viewpoint of getting the vivid and crisp image.
Therefore, in the color image-forming apparatus, the technologies
disclosed in JP-A-Hei.5-142963, JP-A-Hei.3-2765,
JP-A-Sho.63-259575, etc., for example, have already been proposed
as the technology for preparing images with a high gloss. The
effect such that the image with a high gloss can be obtained by
employing a color copying machine and selecting the material of the
toner, the fixing conditions, etc. is set forth in these
Publications.
However, in the case of the technologies disclosed in these
Publications, the glossiness of the image portion made of the toner
can be enhanced. Nevertheless, these technologies have problems
that the glossiness of the non-image portion cannot be increased
higher and also that the glossiness on the base material cannot be
made uniform. Also, the unevenness of the color toner remains on
the surface of the image, and thus the color image does not become
smooth unlike silver halide photographic prints or printed matters.
Therefore, these technologies have the problem that a sufficiently
smooth appearance cannot be obtained.
Therefore, in order to deal with the above problems, in
JP-A-Sho.63-58374, JP-A-Hei.4-278967, JP-A-Hei.4-204670,
JP-A-Hei.5-232840, JP-A-Hei.7-72696, etc., for example, the device
for transferring/fixing transparent toner as well as color toners
onto the base material has been proposed.
However, in the case of the apparatus according to these proposals,
since the transparent toner image is formed on the based material,
a total amount of the transfer toner consisting of the color toner
and the transparent toner is increased and thus the good transfer
efficiency cannot be obtained. Therefore, not only the smooth image
cannot be obtained, but also the unevenness of the image remains
because the color toner is developed. As a result, these
technologies have the problem that the smooth image of high surface
uniformity cannot be obtained.
Also, as disclosed in JP-A-Hei.11-202583, in order to develop the
transparent toner between screen lines comprising color toners, a
technique has already been proposed that the image signals for
developing the transparent toner are set to be inserted into the
clearances between the pixels of the color toner.
However, actually it is difficult to develop the transparent toner
in the clearances between the pixels of the color toner due to
speed variation of a photoreceptor, speed variation, expansion, and
contraction/meandering of an intermediate transfer material and a
base material etc. Therefore, this technique has the problem that
the image surface structure is not smooth and that, due to poor
surface smoothness, images similar to silver halide photographic
and lithographic ones, which have a highly uniform appearance
cannot be obtained.
In addition, in JP-A-Hei.5-158364, the apparatus that can form the
image with high gloss, such as the silver photography by
heating/melting the base material, on which the color toner image
and the transparent toner image are formed, by the belt-type fixing
device and then cooling/releasing the base material is
disclosed.
However, in the case of this apparatus, there is the problem that
the height difference becomes prominent at the boundary between a
high density portion and a low density portion, and especially a
small low density spot in the high density portion becomes hollow
such that a pit is opened. This phenomenon becomes prominent when
speed of a base material passing through a fixing device is
enhanced. Thus, this apparatus has the problem that it is
impossible to achieve both of the high printing speed and the
highly glossy uniform image.
Therefore, the present invention has been made to overcome the
problems in the related art. It is an object of the present
invention to provide a gloss-imparting device capable of forming an
image, whose surface is smooth over an entire area of the image and
which has a high gloss independent of the image density, at a high
speed not to make height difference at a boundary between a high
density portion and a low density portion prominent, and a color
image-forming apparatus using the same.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, there is provided a
gloss-imparting device for imparting a gloss on a color image, the
gloss-imparting device having a transparent toner image-carrying
body, a transparent toner image-forming unit, a
heating/pressurizing unit, and a cooling/releasing unit. The
transparent toner image-carrying body carries a transparent toner
image formed of a transparent toner thereon. The transparent toner
image-forming unit forms a transparent toner image on the
transparent toner image-carrying body. The heating/pressurizing
unit heats and pressurizes the transparent toner image and the base
material to bring them into contact. The cooling/releasing unit
cools the transparent toner image and releases the base material
from the transparent toner image-carrying body. The transparent
toner image is transferred and fixed onto the base material by the
heating/pressurizing unit.
According to a second aspect of the invention, there is provided a
color image-forming apparatus for forming a color image with a
gloss, the color image-forming apparatus having a color
image-forming unit for forming a color image on a base material, a
transparent toner image-carrying body for carrying a transparent
toner image formed of a transparent toner thereon, a transparent
toner image-forming unit for forming the transparent toner image on
the transparent toner image-carrying body, a heating/pressurizing
unit for heating and pressurizing the transparent toner image,
which is formed on the transparent toner image-carrying body, and
the base material, on which the color image is formed by the color
image-forming unit, to bring the transparent toner image and the
base material into contact, and the cooling/releasing unit for
cooling the transparent toner image, which is heated/pressured by
the heating/pressurizing unit, and then releasing the base
material, on which the transparent toner image and the color image
are formed, from the transparent toner image-carrying body. The
transparent toner image formed on the transparent toner
image-carrying body is transferred and fixed onto the base material
by the heating/pressurizing unit.
According to a third aspect of the invention, there is provided a
color image-forming apparatus according to the second aspect, in
which the color image formed by the color image-forming unit is an
unfixed toner image, which is formed by color toners including at
least a thermoplastic resin.
According to a fourth aspect of the invention, there is provided a
color image-forming apparatus according to the second aspect in
which the color image-forming unit has a heating/fixing unit for
melting/fixing a toner image onto the base material and the color
image formed by the color image-forming unit is a toner image,
which is formed by color toners including at least a thermoplastic
resin, melted/fixed onto the base material by the heating/fixing
unit.
According to a fifth aspect of the invention, there is provided a
color image-forming apparatus according to the second aspect, in
which the transparent toner image-forming unit includes a
photoreceptor, a charging device for charging the photoreceptor,
facing the photoreceptor, an exposing device for exposing the
photoreceptor to form an electrostatic latent image on the
photoreceptor, a signal forming device for controlling an area in
which a transparent toner image is formed on the color image formed
by the color image-forming unit, a transparent toner
image-developing device for developing the electrostatic latent
image on the photoreceptor to form a transparent toner image on the
photoreceptor, the transparent toner image-developing device facing
the photoreceptor, and a transferring device for transferring the
transparent toner image formed on the photoreceptor onto the
transparent toner image-carrying body.
According to a sixth aspect of the invention, there is provided a
color image-forming apparatus according to the second aspect, in
which a surface of the transparent toner image-carrying body is
coated with a silicon rubber.
According to a seventh aspect of the invention, there is provided a
color image-forming apparatus according to the second aspect, in
which a surface of the transparent toner image-carrying body is
coated with a liquid fluoroelastomer.
According to an eighth aspect of the invention, there is provided a
color image-forming apparatus according to the second aspect, in
which the transparent toner includes at least a thermoplastic resin
having a weight-average molecular weight in a range of from 5,000
to 40,000 and a glass transition point of not lower than 55.degree.
C. and lower than 75.degree. C., and a wax whose melting point is
in the range of from 80.degree. C. to 110.degree. C. at a content
between 2 and 8 wt %.
According to a ninth aspect of the invention, there is provided a
color image-forming apparatus according to the fifth aspect, in
which when the toner developing device develops the electrostatic
latent image, a temperature of the transparent toner image-carrying
body is less than 60.degree. C. at a position thereon to which the
transparent toner developing device is opposed.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiments will be described with reference to the
drawings, in which like reference numerals represent like parts,
and wherein:
FIG. 1 is a cross-sectional view showing a color image-forming
apparatus to which a gloss-imparting device according to an
embodiment 1 of the present invention is applied;
FIG. 2 is a cross-sectional view showing the gloss-imparting device
according to the embodiment 1 of the present invention;
FIG. 3 is cross-sectional view schematically illustrating a color
image on which a transparent toner image is overlaid;
FIG. 4 is a cross-sectional view showing the gloss-imparting device
according to the embodiment 1 of the present invention;
FIG. 5 is a plane view of a color image in which the transparent
toner image is coated only at selected portions;
FIG. 6A shows a transparent toner image which is formed on the belt
and whose thickness is modulated by the amount of color toners, and
FIG. 6B shows the cross-sectional view of such transparent toner
image overlaid on a color toner image; and
FIG. 7 summarizes the evaluation results for the prints prepared by
the embodiments and comparative examples.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Embodiments of the present invention will be explained with
reference to the drawings hereinafter.
Embodiment 1
This color image-forming apparatus is constructed to form a color
image on a base material and form a glossy color image by
transferring/fixing a transparent toner image onto the base
material on which the color image is formed, and to have at least a
transparent toner image-carrying body for carrying a transparent
toner image thereon; a transparent toner image-forming unit for
forming the transparent toner image on the transparent toner
image-carrying body; a heating/pressurizing unit for heating and
pressurizing the transparent toner image, which is formed on the
transparent toner image-carrying body, and the base material on
which the color image is formed, to bring into contact; and a
cooling/releasing unit for cooling the transparent toner image,
that is transferred/fixed on to the base material, and then
releasing the base material, on which the transparent toner image
and the color image are formed, from the transparent toner
image-carrying body.
As a base material on which the color image is formed, the paper or
the plastic film onto which the color toner image is transferred,
paper on which an image is printed by the ink jet, the offset
printed matter such as a catalog, a handbill, etc. for example, may
be used. Any color image formed by any well-known image forming
apparatus may be employed, so long as the color image is formed on
a base material.
When a thermoplastic toner image is formed on a paper or a plastic
film, particularly preferable result can be obtained using the
color image-forming apparatus according to the invention. The toner
image may be an unfixed image or may be an image formed by
melting/fixing a toner by a heating/fixing device.
Also, a unit for forming the color toner image on the base material
may be a color image-forming apparatus based on well-known
electrophotographic processes or the like.
FIG. 1 is a cross-sectional view showing a color image-forming
apparatus to which a gloss-imparting device according to the
embodiment 1 of the present invention is applied.
Roughly classified, this color image-forming apparatus 1 has a
scanning device 2 for reading and digitalizing a color original, an
image outputting device 3 for outputting an image based on the
color image that is read by the scanning device 2 or image data
that is sent from a personal computer (not shown) or the like, and
a gloss-imparting device 4 for imparting a gloss on a base material
on which the color image output from the image outputting device 3
is formed or a base material on which the color image is formed by
other unit.
The scanning device 2 is constructed so as to illuminate the
original document located on a platen glass 5 with an illuminating
lamp 6 and then detect the reflected light from the document by a
color sensor 7 at a predetermined resolution (e.g., 16
pixels/mm).
The reflected light image of the document, which is read by the
scanning device 2, is supplied to an image processing device 8 as
three-color document reflectance data consisting of red (R), green
(G), and blue (B) (each 8 bit). In the image processing device 8,
predetermined image processing such as shading correction,
positional error correction, brightness/color space transformation,
gamma correction, frame erasure, color/move edition, etc. are
applied to the document reflectance data, and also resultant image
data are converted into four-color image data consisting of yellow
(Y), magenta (M), cyan (C), and black (K).
The image outputting device 3 capable of forming plural toner
images each having a different color is equipped in the color
image-forming apparatus 1. This image outputting device 3 has a ROS
(Raster Output Scanner) 9 as an image exposing unit, a
photosensitive drum 10 as an image carrying body on which an
electrostatic latent image is formed, and a rotary type developing
device 11 as a developing device capable of forming plural toner
images, each having a different color, by developing the
electrostatic latent image formed on the photosensitive drum
10.
The image data that are subjected to the predetermined image
processing at the image processing device 8 are sent to the ROS 9
as four-color image data consisting of yellow (Y), magenta (M),
cyan (C) and black (K) (each 8 bit).
As shown in FIG. 1, the ROS 9 modulates a laser diode 12 in
response to the image data. Then, a laser beam LB that is modulated
in response to the image data is emitted from this laser diode 12.
The laser beam LB emitted from this laser diode 12 is
deflected/scanned by a rotating polygonal mirror (not shown), and
then scanned/exposed onto the photosensitive drum 10 as the image
carrying body via an optical system having a f-.theta. lens, a
reflection mirror, etc.
The photosensitive drum 10 on which the laser beam LB is
scanned/exposed by the ROS 9 is rotated/driven by a driving unit
(not shown) at a predetermined speed along the arrow direction.
Electrostatic latent images are formed on the surface of the
photosensitive drum 10 by charging previously the surface thereof
up to a predetermined potential by a charger 13 for primary
charging to have a predetermined polarity (e.g., negative
polarity), and then scanning/exposing the surface thereof by the
laser beam LB, which correspond to the respective color of yellow
(Y), magenta (M), cyan (C) and black (K), sequentially in response
to the image data. The electrostatic latent images formed on the
photosensitive drum 10 are reversal-developed by toners, which are
charged to have, for example, negative polarity same as the charged
polarity of the photosensitive drum 10 by a rotary type developing
device 11 that has four-color developers 11Y, 11M, 11C, 11K of
yellow (Y), magenta (M), cyan (C) and black (K) to provide toner
images T of predetermined colors. In this case, the toner images T
formed on the photosensitive drum 10 are charged at a predetermined
polarity by a pre-transfer charger (not shown), as the case may be,
to adjust the amount of charge.
Each color toner used in the developing device 11 consists of
insulating particles containing at least a binding resin and a
coloring agent. A typical set of color toners are a cyan toner, a
magenta toner, a yellow toner and a black toner. The composition,
average grain size, etc. of each color toner may be selected
appropriately from a range that does not spoil the object of the
present invention.
As a binding resin, the binding resin in a transparent toner
described later as the example may be listed. Also, it is
preferable that the binding resin should be formed of polyester
whose weight-average molecular weight is in a range of 5000 to
12000. The coloring agents are not particularly limited so long as
coloring agents are employed normally in the toner. The coloring
agents may be selected from cyan pigments or dyes, magenta pigments
or dyes, yellow pigments or dyes, and black pigments or dyes, which
are well known. Preferably, in order to enhance the effect of
providing high gloss, it is important to suppress light scattering
at the boundaries between the pigment and the binder. A combination
using a coloring agent, in which the pigments having small grain
size and disclosed in JP-A-Hei.4-242752 are highly dispersed, is
effective.
Also, there is no necessity that the grain size of the color toner
should be particularly limited. However, if the necessity such that
the color toner should have a function of reproducing faithfully
the electrostatic latent image formed by the exposing device is
considered, a grain size between 4 .mu.m and 8 .mu.m is
preferable.
In the present invention, the color toner that is prepared
appropriately may be employed or products available in the market
may be employed.
The color toner is used after such color toner is combined with a
well-known carrier, which is selected appropriately, to constitute
the developer. Also, a mono component developer can be applied.
Respective color toner images being formed sequentially on the
photosensitive drum 10 are transferred to lay over one another onto
an intermediate transfer belt 14, which is arranged below the
photosensitive drum 10 as an intermediate transfer body, by a
primary transfer corotron 15 as a primary transfer unit. This
intermediate transfer belt 14 is tensioned by fixing end portions
thereof to roller members so that the intermediate transfer belt 14
can be rotated/driven at the same moving speed as the peripheral
speed of the photosensitive drum 10 along the arrow direction.
Sequential formation of four color images on the photoreceptor and
their sequential transfer in resister onto the intermediate
transfer belt 14 with use of the primary transfer corotron 15 are
carried out. Then, the toner images transferred onto the
intermediate transfer belt 14 are transferred onto a recording
paper 16 as the base material, which is driven to a secondary
transfer position at a predetermined timing, by the pressure and
electrostatic force of a back-up roller 17, which supports the
intermediate transfer belt 14, and a secondary transfer roller 18,
which constitute a part of a secondary transfer unit that is pushed
against the back-up roller 17. The recording paper 16 of a
predetermined size is fed from the paper-feed cassette (not shown)
that is arranged in the color image-forming apparatus 1. Then, as
described above, the toner images of predetermined colors are
transferred collectively from the intermediate transfer belt 14 to
the recording paper 16 by the back-up roller 17 and the secondary
transfer roller 18 as the secondary transfer unit.
Also, the recording paper 16 onto which the predetermined color
toner images are transferred from the intermediate transfer belt 14
is separated from the intermediate transfer belt 14, and then moved
to the gloss-imparting device 4 serving as the fixing device by a
carrying device 19.
As the carrying device 19 that carries the base material 16, on
which the color image is formed, to the gloss-imparting device 4
serving as the fixing device, any well-known carrying device can be
employed. Since it is preferable that the carrying device 19 has a
constant carrying speed, for example, either the device that drives
the base material while inserting the base material between a pair
of rubber rollers that are rotated at a constant rotational speed
or the device drives the base material at a constant speed while
inserting the base material on the belt that is formed of the
rubber, or the like and is stretched around a pair of rollers, one
of which is driven by a motor, etc. at a constant speed, may be
employed. If the unfixed toner image is formed on the base
material, the latter device is preferable from a viewpoint that the
toner image is not disturbed.
A gloss-imparting device acting also as a fixing device comprises a
transparent toner image-carrying body, a transparent toner
image-forming unit, and a heating/pressurizing unit, and a
cooling/releasing unit. In such a device, a transparent toner image
is formed on the image-carrying body with use of the transparent
toner image-forming unit, and then is brought into contact with
color toner images on the base material by the heating/pressurizing
unit whereby the transparent toner image and color toner images are
simultaneously fixed on the base material. Finally, in the
cooling/releasing unit the base material on which the transparent
and color toners are fixed is cooled and separated from the
transparent toner image-carrying body.
FIG. 2 shows the gloss-imparting device 4 that is used in
combination with the color image-forming apparatus 1.
The gloss-imparting device 4 is constructed to have a transparent
toner image-carrying body 20 such as an endless belt, a transparent
toner image-forming unit 21 for forming a desired transparent toner
image on the transparent toner image-carrying body 20, a
heating/pressurizing unit 22 for heating and pressurizing the
desired transparent toner image, which is formed on the transparent
toner image-carrying body 20, and the base material 16, on which
the color image is formed, to bring them into contact with each
other, and a cooling unit 23 for cooling the base material 16 on
which the color image is transferred/fixed in a situation that the
transparent toner image is coated on a surface of the color image
by the heating/pressurizing unit 22.
As the transparent toner image-carrying body 20, the fixing belt
that is formed of a polymer film such as polyimide, etc. such as an
endless belt is used. Also, in order to consistently form a
transparent toner image with a uniform thickness, the transparent
toner image-carrying body 20 whose electric resistivity is adjusted
to a desirable value by dispersing a conductive additive such as
conductive carbon particles, a conductive polymer, etc. is
preferable. Though such materials may be fabricated into sheets, it
is preferable to employ the transparent toner image-carrying body
20 formed in an endless belt. In addition, from a viewpoint of the
release property, it is preferable that the surface of the
transparent toner image-carrying body 20 formed into the endless
belt should be covered with a silicon resin and/or a fluororesin.
Furthermore, from a viewpoint of smoothness, it is preferable that
the transparent toner image-carrying body 20 has more than 60 of
surface glossiness as measured by a 75-degree gloss-meter.
In addition, the transparent toner image-forming unit 21 forms a
transparent toner image containing a thermoplastic resin on the
transparent toner image-carrying body 20. An image forming unit
having any well-known developing device may be used. As this
transparent toner image-forming unit, for example, there is used an
apparatus in which a mono component developing unit or a dual
component developing unit is disposed so as to face a counter
electrode member at a position where the counter electrode member
such as a roll, which is earthed or is applied a bias voltage, in
contact with the back of the transparent toner image-carrying body
and the mono component developing unit or the dual component
developing unit directly develops a transparent toner image on the
transparent toner image carrying body. It is preferable that when
the toner developing device develops an electrostatic latent image
(the transparent toner image), a temperature of the transparent
toner image-carrying body 20 is less than 60.degree. C. at a
position thereon where transparent toner development takes
place.
Further, as shown in FIG. 2, the transparent toner image-forming
unit 21 preferably has a photosensitive drum 24, a charging device
25 opposed to the photosensitive drum 24, an exposing device 26
made of a ROS, an LED array, or the like for exposing the
photosensitive drum 24, a signal forming device 27 for controlling
an area in which the transparent toner image is formed on the color
image, and the amount of the transparent toner image, a transparent
toner image-developing device 28 opposed to the photosensitive drum
24, and a transferring device 29 for transferring the transparent
toner image formed on the photosensitive drum 24 onto the
transparent toner image-carrying body 20.
Here, no particular limitation is imposed to the photosensitive
drum 24. The well-known drum may be employed, or the single-layer
structure may be employed, or the multi-layered structure having
separate functions may be employed. Also, as a material, inorganic
material such as selenium, amorphous silicon, etc. may be employed,
or organic material may be employed.
Also, as the charging device 25, for example, the well-known unit
such as a contact charger using a conductive or semi-conductive
roller, brush, film, rubber blade, etc., a corotron charger, a
scorotron charger, etc. using corona discharge, and others may be
employed.
In addition, as the exposing device 26, the well-known device such
as a laser ROS which consists of a semiconductor laser, a scanning
device and an optical system, an LED imager, a halogen lamp, etc.
may be employed. In order to develop the transparent toner only at
arbitrary areas within a color image, it is preferred to use a
laser ROS or an LED array.
As the signal forming device 27, any well-known unit may be
employed as far as the transparent toner image can be developed on
the base material at the desired position. In this case, as the
signal forming device 27, a device for forming the transparent
toner image signal based on an image data output from the image
processing device 8 may be employed.
In addition, as the transparent toner image-developing device 28,
the well-known developing device may be employed irrespective of
the mono component developer and the dual component developer as
far as such developing device can satisfy the purpose of forming
the uniform transparent toner image on the photosensitive drum 24.
In the transparent toner image-developing device 28, the
transparent toner is used, as described later.
Further, as the transferring device 29, the well-known unit may be
employed. For example, a unit for transferring charged particles of
the transparent toner by generating the electric field between the
photosensitive drum 24 and the transparent toner image-carrying
body 20 by using the conductive or semi-conductive roller, brush,
film, rubber blade, etc. to which the voltage is applied, a unit
for transferring the charged particles of the transparent toner by
corona-charging the back surface of the transparent toner
image-carrying body 20 by using a corotron charger, a scorotron
charger, etc. using a corona discharge, etc. may be employed.
As the heating/pressurizing device 22 serving as the
heating/pressurizing unit for heating and pressurizing the
transparent toner image-carrying body 20 on which the transparent
toner image is formed and the base material 16 on which the color
image is formed to bring them into contact with each other, the
well-known unit may be employed. As shown in FIG. 2, for example,
this heating/pressurizing unit 22 inserts the transparent toner
image-carrying body 20 on which the transparent toner image is
formed and the base material 16 on which the color image is formed
between a pair of rollers 30 and 31 which are driven at a constant
speed to carry them and then heat/pressurize them. Here, for
example, each surface of one or both of rollers 30, 31, is heated
up to temperature at which the transparent toner is melted by
providing heat sources 32, 33 at their centers. The two rollers 30,
31 are pushed against mutually. Preferably, a silicon rubber layer
or a fluorine rubber layer is provided to the surface of one or
both of rollers 30, 31. It is preferable that a length of a nip
area that is subjected to the heating/pressurizing is in a range of
from about 1 mm to about 8 mm.
The gloss-imparting device 4 will be further explained hereunder.
As shown in FIG. 2, the gloss-imparting device 4 has a heating
roller 30, the transparent toner image-carrying body 20 such as an
endless belt, that is supported rotatably by a plurality of rollers
30, 34, 35 containing the heating roller 30, and the pressurizing
roller 31 that is pushed against the heating roller 30 via the
transparent toner image-carrying body 20.
As shown in FIG. 2, for example, as the heating roller 30, the
roller in which an elastic layer made of the silicon rubber, or the
like is coated on a surface of a metallic core made of aluminum to
have a predetermined outer diameter may be employed. A halogen lamp
32 is provided within the inside of the heating roller 30 as the
heating source, and the heating roller 30 is heated from inside
such that the surface temperature of the heating roller 30 is
elevated up to a predetermined temperature.
Also, as shown in FIG. 2, for example, as the pressurizing roller
31, the roller in which the elastic layer made of a silicon rubber,
or the like is coated on the surface of the metallic core made of
aluminum, and then a mold-releasing layer made of a PFA tube, etc.
is coated on a surface of the elastic layer to have a predetermined
outer diameter may be employed. A halogen lamp 33 is provided to
the inside of the pressurizing roller 31 as the heating source, and
the pressurizing roller 31 is heated from inside such that the
surface temperature of the pressurizing roller 31 is elevated up to
a predetermined temperature.
Then, for example, the heating roller 30 and the pressurizing
roller 31 are pushed mutually by a pressurizing unit (not shown)
via the fixing belt 20 to have a width of the pushing portion (nip
portion) and a predetermined load.
In addition, the transparent toner image-carrying body 20 is
supported rotatably by a plurality of rollers consisting of the
heating roller 30, a releasing roller 34, and a driven roller 35,
and is rotated/driven by the heating roller 30, which is
rotated/driven by a driving source (not shown), at a predetermined
moving speed (e.g., 60 mm/sec). As the transparent toner
image-carrying body 20, for example, the member in which a silicon
rubber layer of 30 .mu.m thickness is coated on the endless film
made of the thermosetting polyimide having a thickness of 80 .mu.m
may be employed.
Also, a cooling/releasing heat sink 36 (or a heat pipe) as a
cooling/releasing device, which compulsorily cools the transparent
toner image-carrying body 20 to release the base material, is
provided between the heating roller 30 and the releasing roller 34
on the inner surface side of the transparent toner image-carrying
body 20. Thus, the toner and the base material 16 are cooled and
released by the cooling/releasing heat sink 36. Also, it is
preferable that a unit for inserting a releasing finger between the
transparent toner image-carrying body 20 and the base material 16
or a unit for releasing the base material 16 by providing a roller
34 having a small curvature at a releasing position, as shown in
FIG. 2, is provided.
Then, as shown in FIG. 2, in the gloss-imparting device 4, the base
material 16 onto the surface of which color toner images T are
transferred is introduced into a pushing portion (a nip portion)
between the heating roller 30 and the pressurizing roller 31, which
is pushed against the heating roller 30 via the transparent toner
image-carrying body 20, such that the color toner images T are
positioned on the heating roller 30 side. Then, as shown in FIG. 3,
while the base material 16 is being passed through the pushing
portion between the heating roller 30 and the pressurizing roller
31, the color toner images T are heated/melted on the base material
16 and simultaneously a transparent toner image 40 formed on the
transparent toner image-carrying body 20 is heated/melted on the
surface of the color toner images T and then fused thereon.
Then, for example, the color toner and the transparent toner are
heated and melted substantially at temperatures in a range of from
about 120.degree. C. to about 130.degree. C. in the pushing portion
between the heating roller 30 and the pressurizing roller 31. Then,
the base material 16 on which the transparent toner image 40 and
the color toner images T are fused is carried together with the
transparent toner image-carrying body 20 in a state that the
transparent toner image 40 on the surface of the base material 16
contacts tightly to the surface of the transparent toner
image-carrying body 20. The transparent toner image-carrying body
20 is cooled compulsorily by the cooling heat sink 36, and thus the
transparent toner image 40 and the color toner images T are cooled
and solidified and then are released by the releasing roller 34
because of the toughness (rigidity) of the base material.
In this case, after the releasing step is finished, the residual
toner, etc. are removed from the surface of the transparent toner
image-carrying body 20 by a cleaner (not shown), if necessary, to
prepare for the subsequent fixing step.
Meanwhile, the transparent toner used in this embodiment is
formulated so as to contain at least a thermoplastic binding
resin.
In the present invention, the "transparent toner" means toner
particles that do not contain coloring materials (pigment, dye,
carbon black, black magnetic powder, etc.) that aim at coloring by
using the absorption of light and the scattering of light. Normally
the transparent toner in the present invention is colorless and
transparent. However, sometimes the transparency thereof is
slightly low according to the type and the amount of the fluidizing
agent and the mold-releasing agent contained therein. The
transparent toner is substantially colorless and transparent.
Also, as the binding resin, any resin may be employed in response
to the purpose if such resin is substantially transparent. For
example, the well-known resin used in ordinary toners, e.g.,
polyester resin, polystyrene resin, polyacrylic resin, other vinyl
resin, polycarbonate resin, polyamide resin, polyimide resin, epoxy
resin, polyurea resin, or the like and copolymers thereof may be
mentioned. Since most of toner characteristics such as
low-temperature fixing property, fixing strength, storage
stability, etc. can be satisfied simultaneously, the polyester
resin is preferable among them. Also, it is preferable that such
binding resin has a weight-average molecular weight of not less
than 5000 and not more than 40000 and the glass transition point of
not less than 55.degree. C. and less than 75.degree. C. considering
the fixing speed and fixing temperature.
In this case, in the above transparent toner, in order to achieve a
high and uniform gloss, it is desired to control the fluidity and
the electrostatic property of the transparent toner. From the
viewpoint of controlling the fluidity and the electrostatic
property of the transparent toner, it is preferable that an
inorganic fine grain and/or an organic fine grain is externally
added to or adhered onto the surface of the transparent toner.
The above-cited inorganic fine grain is not particularly limited as
far as it does not spoil the advantages of the present invention.
Such inorganic fine grain can be selected appropriately from the
well-known fine grains used as the external additive in response to
the purpose. As the material, for example, silica, titanium
dioxide, tin oxide, molybdenum oxide, etc. may be used. Also, the
inorganic fine grains that are subjected to a hydrophobization
process, which is applied to these inorganic fine grains by using a
silane coupling agent, a titanium coupling agent, or the like, may
be employed with regard to the stabilities such as electrostatic
property.
Also, the above-cited organic fine grain is not particularly
limited as far as it does not spoil the advantages of the present
invention. Such organic fine grain can be selected appropriately
from the well-known fine grains used as the external additive in
response to the purpose. As the material, for example, polyester
resin, polystyrene resin, polyacrylic resin, vinyl resin,
polycarbonate resin, polyamide resin, polyimide resin, epoxy resin,
polyurea resin, fluororesin, or the like may be mentioned.
It is particularly preferable that the average grain size of the
inorganic fine grain or the organic fine grain is in the range of
from 0.005 .mu.m to 1 .mu.m. If this average grain size is blow
0.005 .mu.m, aggregation occurs when the inorganic fine grains
and/or the organic fine grains are adhered onto the surface of the
transparent toner, so that sometimes the desired advantage can not
be achieved. In contrast, if the average grain size exceeds 1
.mu.m, it is difficult to get the image with a higher gloss.
In addition, it is desired that the mold-releasing agent such as
the wax, or the like should be added to the transparent toner. The
composition of the wax is not particularly limited as far as such
composition does not damage the advantages of the present
invention. Such composition can be selected appropriately from the
well-known materials used as the wax in response to the purpose. As
the material, for example, polyethylene resin, carnauba natural
wax, or the like may be thought of. Here, it is preferable that the
wax whose melting point is not less than 80.degree. C. and not more
than 110.degree. C. is added to the transparent toner at a rate of
not less than 2 wt % and less than 8 wt %. The fluidity of the
toner become worse at an ordinary temperature if the melting point
of the wax is less than 80.degree. C. whereas melting at the low
temperature becomes difficult undesirably if the melting point of
the wax is higher than 110.degree. C. Also, the advantages of the
present invention are not sufficient if the content of the wax is
less than 2 wt %, while the characteristics of the toner such as
fluidity, electrostatic property, etc. become worse undesirably if
the content of the wax is not less than 8 wt %.
In addition, the grain size of the transparent toner is not
particularly limited. For example, the grain size of about 15 .mu.m
may be employed.
In this case, the transparent toner is used after such transparent
toner is combined with the well-known carrier, which is selected
appropriately, to constitute a developer. Also, as the mono
component developer, a unit for frictionally charging the toner by
a developing sleeve or a charging member to form a charged toner,
and then developing the image in response to the electrostatic
latent image may be applied.
According to the above configuration, in this embodiment, the
image, whose surface is smooth over the entire surface thereof and
which has a high gloss not to depend on the image density, can be
formed at the high speed not to make the height difference at the
boundary between a high density portion and a low density portion
prominent in the following manner.
In other words, in the color image-forming apparatus 1 to which the
gloss-imparting device 4 according to this embodiment is applied as
shown in FIG. 1, the unfixed color images T made of color toners of
yellow, magenta, cyan, and black colors are formed on the base
material 16 such as the recording paper, etc. by
electrophotography. Then, as shown in FIG. 4, the base material 16
on which the unfixed color images T made of the color toner are
formed is carried into the gloss-imparting device 4 by the carrying
device 19.
As shown in FIG. 2, the transparent toner image having a
predetermined pattern is formed on the transparent toner
image-carrying body 20 in the form of an endless belt. The surface
of the photosensitive drum 24 is charged uniformly by charging
device 25. Then, the area that corresponds to the transparent toner
image 40 is scanned/exposed by the exposing device 26. As shown in
FIG. 5, as the transparent toner image 40, the image that is in any
pattern such as a rectangle, a circle, etc., which corresponds to
the desired color images T, may be employed. Also, as the
transparent toner image 40, the image that covers uniformly the
entire surface of the base material 16 may be employed. However, as
shown in FIG. 6, if the thickness of the transparent toner image is
set thin in an area in which the thickness of the toner layer of
the color images T is thick and is set thick in an area in which
the thickness of the toner layer of the color images T is thin,
such thickness of the transparent toner image may be set such that
the surface of the transparent toner image becomes substantially
smooth consequently. In this case, the shape and the thickness of
the transparent toner image are decided based on the image data
that are processed by the image processing device.
The electrostatic latent image that corresponds to the transparent
toner image, which is formed on the photosensitive drum 24, is
developed by the transparent toner image-developing device 28 to
provide the transparent toner image 40. This transparent toner
image 40 formed on the photosensitive drum 24 is transferred onto
the transparent toner image-carrying body 20 by the transferring
device 29. The transparent toner image 40 formed on the transparent
toner image-carrying body 20 is formed at a predetermined timing in
synchronism with the base material 16 on which the color image is
formed, and then is moved to the heating and pressurizing
position.
As shown in FIG. 2, the transparent toner image 40 formed on the
transparent toner image-carrying body 20 is heated and pressurized
onto the surface of the base material 16 on which the color images
T are formed by the heat and the pressure of the heating roller 30
and the pressurizing roller 31. At that time, as shown in FIG. 3,
the color toner of the color images T, which are formed on the base
material 16 and consist of the color toner, is melted by the heat
and the pressure of the heating roller 30 and the pressurizing
roller 31. Then, the color images Tare melted/coated in a situation
that the transparent toner image 40 made of the transparent toner
is laminated on the surface of the color images having the color
toner. Then, the base material is cooled/released and thus the
color image can be obtained. In this manner, the image whose
surface is smooth over the entire surface of the image and which
has a high gloss independent of the image density can be formed at
a high speed not to make the height difference at the boundary
between the high density portion and the low density portion
prominent.
EXAMPLES
Examples of the present invention will be explained with reference
to the drawings hereunder. In this case, the present invention is
not limited to these examples.
Example 1
Color Toner Developer:
As the color toner developer used in the color image-forming
apparatus of the example 1, the cyan developer, the magenta
developer, the yellow developer, and the black developer for A
Color; manufactured by Fuji Xerox Co., Ltd. were used. The average
grain size of these color toners was 7 .mu.m.
Transparent Toner:
A linear polyester (mole ratio=5:4:1, Tg=62.degree. C., Mn=4500,
Mw=10000) obtained from terephthalic acid/bisphenol A ethyleneoxide
adduct/cyclohexanedimethanol was used as the binding resin. Then,
the transparent fine grains of d50=11 .mu.m was manufactured by
grinding such binding resin with a jet mill and then classifying
the ground resin by an air-type classifier. Two types of the
inorganic fine grains A and B to be described later were adhered to
the transparent fine grains of 100 wt % by the high-speed
mixer.
The inorganic fine grains A were SiO.sub.2 (the surface has been
subjected to a hydrophobization process with use of a silane
coupling agent, the average grain size 0.05 .mu.m, the addition
amount 1.0 wt %). The inorganic fine grains B were TiO.sub.2 (the
surface has been subjected to a hydrophobization process with use
of a silane coupling agent, the average grain size 0.02 .mu.m, the
refractive index 2.5, the addition amount 1.0 wt %).
The dual component developer was prepared by mixing the toner with
the same carrier as the black developer of the color toner.
Color Image-Forming Apparatus:
As the image forming apparatus, the color image-forming apparatus
shown in above FIG. 1 was used. The weight ratio of the toner and
the carrier, the photoreceptor charged potential, the exposure
amount, and the developing bias were adjusted such that the
developed amount of the color toner was 0.5 (mg/cm.sup.2) at a
solid area for every color.
Base Material:
As the base material used in the color image formation, OK special
art paper (manufactured by Oji Paper Co., Ltd.) was used.
Development of the Transparent Toner:
As the transparent toner developing device, the dual component
developing device was used. The weight ratio of the toner and the
carrier, the photoreceptor charged potential, the exposure amount,
and the developing bias were adjusted such that the developed
amount of the color toner of 1.0 (mg/cm.sup.2) can be obtained.
As the transparent toner image-carrying body, the member that is
obtained by coating the silicon rubber of 50 .mu.m thickness on the
polyimide film of 80 .mu.m thickness, into which the conductive
carbon is dispersed, was used.
Also, as the heating/pressurizing rollers, the roller in which a
silicon rubber layer of 2 mm thickness is provided onto the core
material made of aluminum was used, and a halogen lamp acting as
the heat source is arranged at the center of the roller. The
surface temperature of both rollers was adjusted to 155.degree.
C.
In this case, the fixing speed was set to 60 mm/s. Also, the
temperature of the base material at the releasing position was set
to 70.degree. C.
The color image formed under the above conditions was evaluated in
smoothness, glossiness, etc. as follows.
Smoothness Evaluation:
In order to measure the smoothness of the image surface, the
surface roughness meter, Perthometer C5D (manufactured by Perthen)
of the process black image, in which cyan, magenta, and yellow
image signals are 50% respectively, was used. The ten-point average
roughness Rzi(.mu.m) was measured by a stylus having a tip diameter
of 2 .mu.m under the measuring conditions that the scanning speed
is 0.5 mm/sec, the measured length is 1.0 mm, the measured pitch is
1 .mu.m, and the cutoff is 0.8 mm. Rz1 to Rz50 were measured by
repeating this measurement 50 times at the measuring pitch of 5
.mu.m in the direction perpendicular to the scanning direction, and
then the average value was designated by Rz(.mu.m). The image
analyzing apparatus SAS-2010 (manufactured by Meishin Koki Co.,
Ltd.) was used to calculate the average value. The evaluation was
based on the following criterions. x . . . the case where Rz is not
less than 3 .mu.m .DELTA. . . . the case where Rz is not less 1.5
.mu.m and less than 3 .mu.m .smallcircle. . . . the case where Rz
is less than 1.5 .mu.m Measurement of Glossiness Difference:
In order to measure the glossiness (gloss) of the image, Gloss
Meter GM-26D (manufactured by Murakami Color Research Institute)
was used. An incident angle of the light into the image was set to
75 degree. As the evaluated images, the image of four types, e.g.,
the uniform cyan images in which the cyan image signal is set at
10%, 50% and 100%, the process gray image in which the color toner
is developed by setting the cyan image signal, the magenta image
signal, and the yellow image signal to 50% respectively, the
process black image in which the color toner is developed by
setting the cyan image signal, the magenta image signal, and the
yellow image signal to 100% respectively, and the image in which
all image signals of the color toner are set to 0%, were used.
Then, the maximum value of the glossiness difference of these
images was calculated and then evaluation was made based on the
following criterions. x . . . the case where the glossiness
difference is not less than 30 .DELTA. . . . the case where the
glossiness difference is not less than 15 and less than 30
.smallcircle. . . . the case where the glossiness difference is
less than 15 Subjective Evaluation of the Image:
The subjective evaluation of the overall image preference was made
visual on a portrait. At this time, 20 evaluators were involved in
the evaluation, and the five-category evaluation was made as
follows. 1. very bad 2. bad 3. normal 4. good 5. very good
Then, the average value was calculated and then evaluated based on
following criterions. x . . . the case where the average value is
less than 2 .DELTA. . . . the case where the average value is not
less than 2 and less than 4 .smallcircle. . . . the case where the
average value is not less than 4
Also, the evaluation of the toner material used was carried out in
the following manner.
Gel permeation chromatography was used to measure the molecular
weight. Tetrahydrofuran was used as the solvent.
The average size of toner was measured by using a coulter counter,
and the weight average of d50 was applied.
Example 2
An unfixed color toner image was transferred onto the base material
by using the same device as Example 1, and then was heated/fixed
once by the A Color roller fixing device. Then, the fixed toner
image was loaded on the carrying device, and then the transparent
toner image was provided by using the same device as Example 1.
Example 3
A color image was formed by using the same device as Example 1
except that the driving speed of the transparent toner
image-carrying body was set to 30 mm/s and that the fixing speed
and the developing speed of the transparent toner image-developing
device were set to 30 mm/s.
Comparative Example 1
An unfixed color toner image was transferred onto the base material
by using the same device as Example 1, and then the color image was
formed by heating/fixing this toner image by the A Color roller
fixing device.
Comparative Example 2
A thermoplastic polyester resin (molecular weight 10000) was coated
on the same base material as Example 1 to have a thickness of 15
.mu.m. An unfixed color toner image was transferred onto the base
material by using the same device as Example 1, and then the color
image was formed by heating/fixing this toner image by the A Color
roller fixing device.
FIG. 7 is a table showing the evaluation results of the color
images obtained in the Examples 1 to 3 and comparative examples 1,
2. As apparent from FIG. 7, in the case of Example 1, the values of
smoothness and the subjective evaluation were good, nevertheless
the glossiness difference was slightly large but at the negligible
level.
Also, in the case of Example 2, the result of the subjective
evaluation was good. However, since the fixing process was applied
previously, the smoothness values and the glossiness difference
were slightly large but at the negligible level.
Further, in the case of Example 3, the fixing speed was as slow as
30 mm/s, and all the results of the smoothness values, the
glossiness difference, and the subjective evaluation were good.
In contrast, in the case of Comparative Example 1 showing a prior
art, all the smoothness, the glossiness difference, and the
subjective evaluation were poor.
Also, in the case of Comparative Example 2, the base material
coated with the transparent resin was used. In this case, both the
results of the glossiness difference and the subjective evaluation
were very good or good, nevertheless the smoothness was bad since
the difference in unevenness of the color toner images appeared on
the surface as they are.
As described above, according to the present invention, it is
possible to provide a gloss-imparting device capable of forming
images, whose surface is smooth over its entire area and which has
a high gloss independent of the image density, at the high speed
not to make height difference at the boundary between the high
density portion and the low density portion prominent, and the
color image-forming apparatus using the same.
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