Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2001-12-28
2003-11-11
Nguyen, Judy (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S101000
Reexamination Certificate
active
06644799
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a combination of ink jet color ink set and a porous ink jet recording element for ink jet printing that provides images with improved gloss difference in imaged and non-imaged areas as well as inter-color gloss difference.
BACKGROUND OF THE INVENTION
In a typical ink jet recording or printing system, ink droplets are ejected from a nozzle at high speed towards a recording element or medium to produce an image on the medium. The ink droplets, or recording liquid, generally comprise a recording agent, such as a dye or pigment, and a large amount of solvent. The solvent, or carrier liquid, typically is made up of water and an organic material such as a monohydric alcohol, a polyhydric alcohol or mixtures thereof.
An ink jet recording element typically comprises a support having on at least one surface thereof an ink-receiving or image-receiving layer, and includes those intended for reflection viewing, which have an opaque support, and those intended for viewing by transmitted light, which have a transparent support.
An important characteristic of ink jet recording elements is their need to dry quickly after printing. To this end, porous recording elements have been developed which provide nearly instantaneous drying as long as they have sufficient thickness and pore volume to effectively contain the liquid ink. For example, a porous recording element can be manufactured by cast coating, in which a particulate-containing coating is applied to a support and is dried in contact with a polished smooth surface.
One of the major disadvantages of the current ink jet recording element is “differential gloss”, particular on images printed using pigment-based inks. In pigment-based inks, the colorant exists as discrete particles. These pigment particles are usually treated with addenda known as dispersants or stabilizers which serve to keep the pigment particles from agglomerating and/or settling out. Therefore, when the pigment-based inks are printed on recording elements having glossy surfaces, the inks on the imaged areas tend to stay on the surface of the receiver. “Differential gloss” may include both include both “image and non-image differential gloss” and “inter-color differential gloss”. “Image and non-image differential gloss” describes the image artifact where the gloss of the non-imaged areas is very different from that of imaged areas. “Inter-color differential gloss” describes the image artifact where the gloss levels of imaged areas of different colors are very different from each other. Both types of image quality defects can be quite noticeable, even to ordinary observers. Although not designed to improve “differential gloss”, one possible solution to this problem is to cover the entire receiver with a protective layer through techniques such as laminating the printed image, or fusing the top fusible polymeric layer in receivers to a continuous overcoat layer, such as those disclosed in U.S. patent application, Ser. No. 09/954,779, filed on Sep. 18, 2001 of Wexler, or coating a protective layer on the imaged areas as described in EP1057646 and EP1048466. However, all these approaches involve separate steps after printing, making the entire process complex and costly.
What the art needs is a way to minimize gloss level variations in imaged and non-imaged areas as well as those among different colors when the various inks are deposited and dried on a receiver. This should be done as part of the printing process and not as a separate step after printing.
SUMMARY OF THE INVENTION
The present invention provides a method for selecting ink jet color ink set and receiver combination that is capable of producing images wherein the gloss level variations between imaged and non-imaged areas as well as that among different colors in the color image are simultaneously minimized. The gloss variation is judged after the ink is deposited and dried on a receiver, but the invention is a part of the ink and receiver selection and printing process; not a separate step after printing.
In accordance with the invention, the gloss level of the ink is predetermined, as measured from single color patches on a receiver. The gloss level of the receiver is also determined under a similar measurement condition. The gloss level variability among different inks as well as the relative gloss difference between the imaged and non-imaged areas are both calculated. By simultaneously keeping the relative gloss difference of the ink and receiver combination as well as the gloss variability with a certain range, the quality of the image is improved.
Hence, the present invention discloses a method of selecting pigment ink set and a receiver combination for inkjet color printing comprising:
a) providing at least two color inks, each ink comprising a carrier and a pigment;
b) printing the above inks onto a set of receivers using test images consisting of single color patches of a Dmax density (100% dot coverage);
c) measuring the gloss level of each patch and the receiver at a predefined specular angle,
d) calculating the Relative Gloss Difference (RGD%) values of the ink set and receiver combination, and
e) selecting the ink set and receiver combination such that RGD value is less than 40% when 60° is used as the specular angle, and the RGD value is calculated according to Equations (A):
RGD
%
=
∑
I
=
1
N
&LeftBracketingBar;
Gloss
(
Imaged
Areas
)
I
-
Gloss
(
Non
-
Imaged
Areas
)
&RightBracketingBar;
∑
I
=
1
N
Gloss
(
Imaged
Areas
)
I
Equation
(
A
)
where
I is a variable which identifies a certain color patch used in the evaluation,
N is the total number of color patches used in the evaluation
Another embodiment discloses a method of selecting pigment ink set and a receiver combination for inkjet color printing comprising:
a) providing at least two color inks, each ink comprising a carrier and a pigment;
b) printing the above inks onto a set of receivers using test images consisting of single color patches of a Dmax density (100% dot coverage);
c) measuring the gloss level of each patch and the receiver at a predefined specular angle;
d) calculating the Relative Gloss Difference (RGD%) and Relative Gloss Variability (RGV%) values of the ink set and receiver combination, and
e) selecting the inks for the color set and receiver combination such that RGD value is less than 40% and RGV value among inks is less than 10% when 60° is used as the specular angle, and the RGD and RGV values are calculated according to Equations (A) and (B), respectively:
RGD
%
=
∑
I
=
1
N
&LeftBracketingBar;
Gloss
(
Imaged
Areas
)
I
-
Gloss
(
Non
-
Imaged
Areas
)
&RightBracketingBar;
∑
I
=
1
N
Gloss
(
Imaged
Areas
)
I
Equation
(
A
)
RGV
(
%
)
=
∑
I
=
1
N
&LeftBracketingBar;
(
Gloss
(
Imaged
Areas
)
I
-
AG
)
&RightBracketingBar;
AG
N
Equation
(
B
)
where
AG
=
∑
I
=
1
N
Gloss
(
Imaged
Area
)
I
N
I is a variable which identifies a certain color patch used in the evaluation,
N is the total number of color patches used in the evaluation.
Yet another embodiment discloses a method of selecting pigment ink set and a receiver combination for inkjet color printing comprising:
a) providing at least two color inks, each ink comprising a carrier and a pigment;
b) adjusting the sizes of the pigment particle of the inks to achieve the desired gloss;
c) printing the above inks onto a set of receivers using test images consisting of single color patches of a Dmax density (100% dot coverage);
d) measuring the gloss level of each patch and the receiver at a predefined specular angle;
e) calculat
Chen Huijuan D.
Han-Adebekun Gang C.
Reczek James A.
Eastman Kodak Company
Nguyen Judy
Shah Manish
Wells Doreen M.
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