Electrophotography – Control of electrophotography process – Control of developing
Reexamination Certificate
2000-05-23
2001-09-11
Chen, Sophia S (Department: 2852)
Electrophotography
Control of electrophotography process
Control of developing
C118S689000, C399S064000
Reexamination Certificate
active
06289184
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for measuring the concentration of developer used in a liquid printer, and more particularly, to an apparatus for measuring the concentration of developer used in a liquid printer developer by forming a developer film and measuring the amount of light transmitted through the developer film.
2. Description of the Related Art
In general, a liquid electrophotographic printer is a device for forming an electrostatic latent image by selectively scanning a laser beam onto a photoreceptor medium such as a photoreceptor web or a photoreceptor drum and developing a toner image from the electrostatic latent image with developer which is a mixture of toner and a liquid carrier in a predetermined ratio.
A color liquid electrophotographic printer, as shown in
FIG. 1
, includes a plurality of development units
20
for developing an electrostatic latent image formed on the image recording surface of a photoreceptor web
1
which is one of photoreceptor media by a laser beam selectively scanned by a laser scanning unit (LSU)
10
.
As shown in the drawing, the development units
20
are typically arranged to form a toner image in order of yellow (Y), magenta (M), cyan (C) and black (K) colors. Each development unit includes a container
21
for developer corresponding to the respective yellow (Y), magenta (M), cyan (C) and black (K) colors, and a developing portion
25
for receiving developer supplied from the container
21
by a developer supply apparatus
23
and for developing a toner image from the electrostatic latent image formed on the photoreceptor web
1
.
The toner image developed at the developing portion
25
is dried at a drying unit
30
and transferred to a transfer roller
41
. The transferred image is printed on a sheet of paper
45
supplied between the transfer roller
41
and the fusing roller
43
. Any remaining developer after the development is collected in the container
21
through the developing portion
25
.
Also, the liquid electrophotographic printer generally includes a concentration measuring apparatus
50
for measuring whether the concentration of the developer is appropriate. The concentration measuring apparatus
50
measures the concentration of developer by emitting light to the developer supplied to the developing portion
25
and measuring the light transmittance thereof.
However, as the toner image may not be completely transferred onto the transfer roller
41
during the transfer process, some toner may remain on the photoreceptor web
1
. As the photoreceptor web
1
rotates, any remaining color toner is carrier along through the developing portions
25
. In doing so, the remaining color toner may enter inside the developing portion
25
for developing a color different from the remaining color and be collected to the container
21
so as to contaminate the original developer color contained in the container
21
. Also, even before the toner image reaches the drying unit
30
, some of the developer adhering to the photoreceptor web
1
at the developing portion
25
enters the subsequent developing portions to contaminate the developers there.
When the developer is contaminated, the concentration measuring apparatus
50
detects a different concentration value from the actual concentration value due to the difference in the light transmittance of the different color toners. For example, in the case of yellow developer contaminated by a small amount of black developer, the concentration value detected by the concentration measuring apparatus
50
is greater than the actual value as the black contaminant causes the light transmittance of the yellow developer to sharply decrease. This is because the light color developers such as yellow, magenta and cyan have light transmittances of about 70-80% or more except for a particular wavelength range corresponding to the color of the developer, whereas black developer exhibits very low light transmittance with respect to light of most wavelengths.
Thus, when developer is contaminated by a different color, in particular, black toner, the concentration measuring apparatus
50
measures an incorrect concentration which is different from the actual concentration value. Also, if the sample of developer to be measured is thick and the developer is contaminated by black toner, the light transmittance approaches zero so that the concentration measurement cannot be performed.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide an apparatus which is less affected by mixed toner of other colors and measures the concentration of developer used in a liquid printer close to an actual concentration of developer although the developer is contaminated.
Accordingly, to achieve the above objective, there is provided an apparatus for measuring the concentration of developer in a liquid printer includes a housing, a developer film forming device installed in the housing for forming a developer film, and a sensing device including a light source unit for emitting colored light corresponding to a range of wavelengths for which the light transmissivity is relatively low to a developer film of a selected color developer, and a photodetector installed corresponding to the light source unit and receiving the light emitted by the light source unit and transmitted through the developer film.
Here, it is preferred in the present invention that the selected color developer is yellow, magenta or cyan color developers, and the color light is blue, green and red light in respect to yellow, magenta and cyan developer, respectively.
Also, it is preferred in the present invention that the blue, green and red light have wavelength ranges of about 400-470 nm, 500-580 nm and 630-700 nm, respectively, and that the blue, green and red light have wavelength ranges of about 436 nm, 546 nm and 700 nm, respectively.
Also, it is preferred in the present invention that the light source unit is a light emitting diode emitting blue, green or red light.
Also, it is preferred in the present invention that the light source unit comprises a white light source and a filter for passing blue, green or red light of the light emitted from the white light source.
Also, it is preferred in the present invention that the light source unit comprises a white light source, a spectrum member for splitting the light emitted from the white light source according to the wavelengths of the light, and an optical cable through which light spilt by the spectrum member is guided to the developer film, wherein the light is of a predetermined wavelength for which the light transmissivity of a selected color developer is relatively low.
Also, it is preferred in the present invention that the developer film forming device comprises a roller rotatably installed in the housing, a driving source for driving the roller to rotate, and a developer supply device for supplying developer to the roller so that a developer film can be formed according to the rotation of the roller.
Also, it is preferred in the present invention that a reflection member is provided on at least a part of the surface of the roller, and the light source unit and the photodetector are installed outside the roller to correspond to each other.
Also, it is preferred in the present invention that at least a part of the roller is formed of a transparent member, and the light source unit and the photodetector are installed inside and outside the roller, respectively, or vice versa such that they are facing each other through the transparent member.
REFERENCES:
patent: 4204766 (1980-05-01), Harada
patent: 5933685 (1999-08-01), Yoo
patent: 6091914 (2000-07-01), Yoo
patent: 04-251274 (1992-09-01), None
patent: 05-332926 (1993-12-01), None
Kwak Hee-Guk
Shin Kyu-cheol
Yoo Yong-Baek
Chen Sophia S
Samsung Electronics Co,. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
LandOfFree
Apparatus for measuring concentration of developer of liquid... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for measuring concentration of developer of liquid..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for measuring concentration of developer of liquid... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2457178