Electrophotography – Control of electrophotography process – Of plural processes
Reexamination Certificate
2002-07-08
2004-11-02
Royer, William J. (Department: 2852)
Electrophotography
Control of electrophotography process
Of plural processes
C399S057000
Reexamination Certificate
active
06813452
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit of Korean Application No. 2001-75676, filed Dec. 1, 2001, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of determining a time to replace a developing solution using a color difference depending on the degree of contamination of the developing solution in a printer.
2. Description of the Related Art
A developing solution of a printer is a mixed solution of a toner and a carrier to dissolve the toner and provides a developing agent used to develop a latent electrostatic image.
FIG. 1
is a sectional view of a conventional wet color printer. Referring to
FIG. 1
, the wet color printer includes a photoreceptor belt
14
, a charger
15
to charge the photoreceptor belt
14
, laser scanning units
16
to scan light onto the charged photoreceptor belt
14
to form a latent electrostatic image, developers
30
to develop the latent electrostatic image, a drier
18
to absorb a liquid carrier on the photoreceptor belt
14
and to evaporate the liquid carrier, and a transfer unit
20
to transfer an image to a sheet
23
.
The photoreceptor belt
14
is entrained about a plurality of rollers including a drive roller
11
and driven rollers
12
and
13
. The sheet
23
is led into the transfer unit
20
by the rotation a transfer roller
21
and a fusing roller
22
, and an image is transferred to the sheet
23
. The laser scanning units
16
scan color information of yellow (Y), cyan (C), magenta (M), and black (K) onto the photoreceptor belt
14
. The corresponding developers
30
supply developing solutions of corresponding colors to the photoreceptor belt
14
. Each of the developers
30
includes a developing solution supplier
32
to supply a developing solution to the photoreceptor belt
14
, and a developer tank
31
to collect the developing solution that drops from the photoreceptor belt
14
. The developer tank
31
includes a developer roller
36
, a brush roller
37
to remove the developing solution from the developer roller
36
, a squeeze roller
34
to extract a liquid carrier which does not form an image from the developing solution supplied onto the photoreceptor belt
14
, and a plate
35
to guide the carrier extracted through the squeeze roller
34
to the developer tank
31
.
The developing solution supplier
32
is provided with a developing solution of an appropriate concentration. The developing solution is made by mixing a solvent (i.e., a liquid carrier (NORPAR)) and a developer (i.e., a toner) from a developing solution providing unit
38
and a developing solution from the developer tank
31
, and supplies the developing solution to the photoreceptor belt
14
.
In such a conventional wet electrophotographic color printer, a carrier dissolves a toner attached to the photoreceptor belt
14
to develop a latent electrostatic image during development. The carrier may not be collected into a developer tank
31
provided for a color corresponding to the carrier, but may be transported attached to the photoreceptor belt
14
to a developer tank
31
provided for other colors. In addition, when some of a toner is not transferred to the sheet
23
and remains on the photoreceptor belt
14
even after transferring performed by transfer unit
20
, the toner may be collected into a developer tank
31
which does not correspond to the color of the toner while the photoreceptor belt
14
circulates. In this case, different colors are mixed within the developing solution suppliers
32
, so an image of desired colors cannot be obtained and a picture quality deteriorates. Particularly, when a black toner is mixed with a yellow toner, it is very difficult to present a normal yellow color, which fatally affects the quality of printing.
SUMMARY OF THE INVENTION
To solve the above and other problems, it is an object of the present invention to provide a method of determining a time to replace a developing solution by simply measuring the degree of contamination of the developing solution.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
To achieve the above and other objects of the present invention, there is provided a method of determining a time to replace a developing solution in a wet electrophotographic printer including developing solutions of predetermined colors according to an embodiment of the invention, the method comprising providing a reference card in which sample patches of standard colors for the predetermined colors of the developing solutions, sample patches of test colors into which the standard colors change due to contamination, and standard color differences &Dgr;E* calculated from standard color values E
s
* corresponding to the respective standard colors and measured standard contamination values E
c
* corresponding to the respective test colors are arranged; inputting information about test patches for the predetermined colors into the printer and printing the test patches; and comparing the sample patches with the test patches to determine whether to replace the developing solutions.
According to an aspect of the invention, the providing the reference card includes setting the standard colors for the predetermined colors and the test colors into which the standard colors change depending on contamination; calculating the standard color values E
s
* corresponding to the respective standard colors and the measured standard contamination values E
c
* corresponding to the respective test colors; calculating the standard color differences &Dgr;E* from the standard color values E
s
* and the measured standard contamination values E
c
*; and providing the reference card in which the sample patches corresponding to the standard colors and the sample patches corresponding to the test colors are arranged in order of the standard color differences &Dgr;E*.
According to another aspect of the invention, in the setting the standard colors, each of the standard color values E
s
* is defined by three variable values including a standard value of lightness L
s
*, a standard value of red-greenness a
s
*, and a standard value of yellow-blueness b
s
*, and each of the measured standard contamination values E
c
* is defined by three variable values including a measured standard contamination value of lightness L
c
*, a measured standard contamination value of red-greenness a
c
*, and a measured standard contamination value of yellow-blueness b
c
*.
According to yet another aspect of the invention, in the calculating the standard differences &Dgr;E*, the standard color differences &Dgr;E* satisfy Equation (1).
&Dgr;
E
*={(&Dgr;
L
*)
2
+(&Dgr;
a
*)
2
+(&Dgr;
b
*)
2
}
1/2
&Dgr;
L*=L
s
*−L
c
*
&Dgr;
a*=a
s
*−a
c
*
&Dgr;
b*=b
s
*−b
c
* (1)
According to still another aspect of the invention, the inputting the information about the test patches includes inputting the information about the test patches into the printer; commanding the printer to print the test patches; and printing the test patches in response to the command.
According to a further aspect of the invention, in the printing the test patches, measured contamination values E
c
of the respective test patches are printed together with the test patches.
According to a still further aspect of the invention, each of the measured contamination values E
c
is defined by three variable values including a measured contamination value of lightness L
c
, a measured contamination value of red-greenness a
c
, and a measured contamination value of yellow-blueness b
c
.
According to a yet further aspect of the invention, in the printing the test patches, measured color differences &Dgr;E corresponding to the measured contamination values E
c
of the respective test patch
Jung Sun-hae
Lee Seung-wan
Royer William J.
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
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