Electrophotography – Control of electrophotography process – Control of developing
Reexamination Certificate
2002-02-01
2004-02-17
Tran, Hoan (Department: 2852)
Electrophotography
Control of electrophotography process
Control of developing
C399S058000
Reexamination Certificate
active
06694113
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink delivery system of delivering ink used for development in a liquid-type electrophotographic printer, and an ink delivery method thereof.
2. Description of the Related Art
In general, a liquid-type electrophotographic printer is an apparatus in which an electrostatic latent image is formed on a photosensitive medium by scanning the photosensitive medium with a plurality of laser beams, thereafter, the electrostatic latent image is developed with ink and the developed image is transferred onto a paper sheet. The ink used in development is a mixture of a powder toner and a liquid solvent.
FIG. 1
shows a portion of a liquid type electrophotographic printer. As shown in
FIG. 1
, a liquid type electrophotographic printer includes developing units
20
for developing respective electrostatic latent images with ink having predetermined colors to form a visible image, a drying unit
30
for drying the developed image to an extent appropriate for transferring the developed image onto a paper sheet at a transfer unit (not shown), and an ink delivery system
40
for supplying ink having a concentration and a quantity which are appropriate for development to the developing units
20
, and for resupplying the solvent recovered by the drying unit
30
to circulation tanks
45
.
FIG. 1
shows a conventional liquid-type electrophotographic, color printer. In
FIG. 1
, only a developing unit corresponding to a black developer is shown, and other developing units corresponding to yellow (Y), magenta (M), and cyan (C) developers are omitted.
Ink used in development is made by mixing concentrated ink supplied from ink tanks
41
and a liquid solvent supplied from a solvent cartridge
44
or a condensing tank
39
connected to the drying unit
30
in a predetermined ratio to dilute the concentrated ink.
The ink delivery system
40
includes ink tanks
41
for storing concentrated ink, a solvent tank
42
for storing a solvent, concentrated ink refill cartridges
43
of pressurized-can-type refill cartridges for refilling the respective ink tanks
41
with respective new supplies of concentrated ink when the concentrated ink in the ink tanks
41
is consumed, a solvent refill cartridge
44
of a pressurized-can-type refill cartridge for refilling the solvent tank
42
with a new supply of a solvent when the solvent in the solvent tank
42
is consumed, circulation tanks
45
for storing appropriately mixed mixtures of ink supplied from the ink tanks
41
and the solvent supplied from the solvent tank
42
, supply portions
47
for supplying the ink in the circulation tanks
45
to the developing units
20
and a waste ink tank
49
for temporarily storing ink drained from the circulation tanks
45
through respective waste ink recovery passages
48
.
The circulation tanks
45
are installed below the respective developing units
20
and they supply ink to the respective developing units
20
. The circulation tanks
45
also circulate, receive and resupply the ink which does not take part in development. Concentration sensors
46
are installed at the respective circulation tanks
45
for sensing respective concentrations of developers contained in the circulation tanks
45
.
The ink tanks
41
and the solvent tank
42
store concentrated ink and a solvent supplied from the pressurized-can-type ink cartridges
43
and solvent cartridge
44
which can discharge the contained liquid with pressurized air as described above, and supply the concentrated ink and the solvent to the circulation tanks
45
in predetermined ratios. When any one of the corresponding concentration sensors
46
detects that the concentration of the ink in a corresponding one of the circulation tanks
45
is out of a predetermined range, the corresponding ink tank
41
and the solvent tank
42
supply the concentrated ink and the solvent to the corresponding circulation tank
45
in a controlled manner so that the concentration of the ink in the corresponding circulation tank
45
can be within the desired range. Reference numerals
41
a
and
42
a
denote level sensors for detecting remaining quantities of the ink and the solvent stored in the ink tanks
41
and the solvent tank
42
, respectively. When the level sensors
41
a
and
42
a
detect that the ink and the solvent in the tanks
41
and
42
are consumed, the consumed tanks
41
and
42
are refilled with new supplies of the ink and the solvent from the ink cartridges
43
and the solvent cartridge
44
.
However, in the above-described ink delivery system, since the concentrated ink and the solvent contained in the ink cartridges
43
and the solvent cartridge
44
are first transferred to the ink tanks
41
and the solvent tank
42
provided with the level sensors
41
a
and
42
a,
respectively, and then supplied to the circulation tanks
45
in order to control ink and solvent supplies and refills in the system, it's disadvantageous that the number of containers installed in a printer is large.
In addition, the above level sensors
41
a
and
42
a
usually employ a level measuring method in which ink levels are measured by detecting varying capacitances of the ink. As a matter of course, there are other level sensors, employing a floater, or an ultrasonic wave, besides the level sensor employing the capacitance measuring method. However, those level sensors are not employed in this application. A floater may malfunction if it adheres to an inner wall of a container, and a level sensor using an ultrasonic wave is very expensive and is too large for this application. Also, in the above capacitance measuring method, the level sensor may respond to ink adhering to the inner wall of a container, and detect an ink level erroneously. Therefore, in order to enhance the operational stability of an ink delivery system, it is desirable that the number of such level sensors is reduced as much as possible.
Consequently, if exhaustion of ink filled in a container can be known without a level sensor, the number of parts can be reduced, possibility of erroneous operations of level sensors can be reduced, and, in addition, the number of containers in an ink delivery system can be reduced since concentrated ink and a solvent need not be transferred to containers having level sensors. Therefore, new types of ink delivery system and ink delivery method are required for realizing the above.
SUMMARY OF THE INVENTION
To solve the above problem, it is an objective of the present invention to provide an ink delivery system and an ink delivery method of a liquid-type electrophotographic printer which are adapted to detect whether or not liquid in any one of containers which supply ink and a solvent to circulation tanks is exhausted without installing separate level sensors.
Accordingly, to achieve the above objective, there is provided an ink delivery method of a liquid-type electrophotographic printer for supplying concentrated ink and a solvent to circulation tanks receiving ink to be supplied to respective developing units including the steps of: (a) preparing ink cartridges which store concentrated ink to be supplied to the circulation tanks; (b) preparing a solvent cartridge which stores a solvent to be supplied to the circulation tanks; (c) detecting an ink concentration of each circulation tank using predetermined concentration sensors which correspond to respective circulation tanks; (d) adjusting the ink concentration of any one of the circulation tanks by supplying the concentrated ink from a corresponding one of the ink cartridges to a corresponding one of the circulation tanks when the ink concentration of the corresponding circulation tank is lower than a predetermined range; (e) generating a message, even after a preset number of the ink concentration adjusting steps are repeated, signaling that the concentrated ink in the corresponding ink cartridge is consumed when the ink concentration is not within the predetermined range; (f) adjusting the ink concentration of any one of th
Jung Woo-chul
Kim Yong-su
Lee Hyong-gu
Park Geun-yong
Shin Hyun-seong
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