Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2001-05-09
2003-02-25
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S087000
Reexamination Certificate
active
06523946
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an ink-jet cartridge for being used for a thermal ink-jet printer, and more particularly to an ink-jet cartridge containing a back pressure-adjusting device therein for being used for a thermal ink-jet printer.
BACKGROUND OF THE INVENTION
Currently, three kinds of printers, i.e. dot-matrix printer, thermal ink-jet printer and laser printer, are commercially available for adapting to be used for a computer. In spite of that a dot-matrix printer has an advantage of the lowest price among them, which has the disadvantages of the slowest printing speed and the most inferior printing quality among them. Although a laser printer has an advantage of the best printing quality among them, which, particularly for a color laser printer, has the disadvantage of the highest price among them. Therefore, up to the present, the thermal ink-jet printer is the most popular one for the general public.
Please refer to
FIG. 1
which is a schematic diagram illustrating a structure of a conventional ink-jet cartridge
10
adapted to be used for a thermal ink-jet printer. Conventionally, an ink-jet cartridge
10
includes a housing
11
for storing the ink
13
in an interior
12
thereof, and a printhead
14
having a plurality of orifices (not shown) thereon for allowing the ink
13
to be jetted therethrough when the thermal ink-jet printer is printing. According to the ideal-gas law,
PV=nRT
where P: pressure, V: volume, n: mole number of the gas molecules, R: ideal-gas constant, T: temperature
if the temperature is maintained at a constant value, the pressure would inversely change with the volume. Certainly, when the thermal ink-jet printer is printing under the environmental temperature, the volume of the space
121
unfilled with the ink
13
will gradually increase because of consumption of the ink
13
. That is, if the volume of the space
121
unfilled with the ink
13
increases when the thermal ink-jet printer is printing, a back pressure of the space
121
would lower simultaneously. On the other hand, if the environmental changes, the back pressure of the space
121
might change as well. Once the back pressure changes, it might be so easy or so hard for the ink
13
to be jetted through the orifices and therefore the printing quality is influenced.
Please refer to FIG.
2
(
a
) which is a schematic diagram illustrating another structure of a conventional ink-jet cartridge
20
adapted to be used for a thermal ink-jet printer. Comparing the ink-jet cartridge
20
of FIG.
2
(
a
) with that of
FIG. 1
, in addition to a housing
21
for storing the ink
23
in an interior
22
thereof and a printhead
24
having a plurality of orifices (not shown) thereon for allowing the ink
23
to be jetted therethrough when the thermal ink-jet printer is printing, the ink-jet cartridge
20
further includes a hollow tube
25
. Preferably, a diameter of the hollow tube
22
is ranged from 0.5 to 2.0 mm. The hollow tube
22
is used for regulating the back pressure of the space
221
by a capillary action of the ink
231
contained in the hollow tube
25
. Even if the volume of the space
221
increases when the thermal ink-jet printer is printing, the back pressure of the space
221
would not lower. However, as shown in FIG.
2
(
b
), when the ink-jet cartridge
20
is inverted unwarily during transportation, owing to the low value of the surface tension of the ink
231
contained in the hollow tube
25
, it is easy for the ink
231
to flow out of the hollow tube
25
or the atmosphere
26
might pass into the hollow tube
25
such that the back pressure of the space
221
unfilled with the ink
231
will not be controlled at a desired suitable range any more. Although a much thinner hollow tube, which provides a higher value of the surface tension of the ink
231
contained in the hollow tube
25
, can be provided to solve the problem, the yield for manufacturing such a much thinner hollow tube is so low that the manufacturing cost thereof is very high.
Accordingly, it is attempted by the present applicant to overcome the above-described problems encountered in the prior arts.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an ink-jet cartridge containing a back pressure-adjusting device therein for being used for a thermal ink-jet printer.
Another object of the present invention is to provide an easily-manufactured back pressure-adjusting device of an ink-jet cartridge for being used for a thermal ink-jet printer.
According to the present invention, the ink-jet cartridge adapted to be used for a thermal ink-jet printer is disclosed. The ink-jet cartridge includes a housing for storing the ink in an interior thereof, a printhead having a plurality of orifices thereon for allowing the ink to be jetted therethrough when the thermal ink-jet printer is printing, and a pressure-adjusting device disposed in the housing for regulating a back pressure of the interior of the housing, wherein the pressure-adjusting device includes a first opening fixed on an upper portion of the housing and exposed to an ambient atmosphere, and a second opening disposed at a bottom of the interior of the housing and having at least one regulating hole thereon, wherein the regulating hole has a cross-sectional area being smaller than that of the first opening for maintaining the back pressure when the ink-jet cartridge is inverted.
Preferably, the back pressure of the interior of the housing is regulated by a capillary action of the ink contained in the pressure-adjusting device.
Preferably, the second opening of the pressure-adjusting device is fixed at the bottom of the interior of the housing.
Preferably, the second opening of the pressure-adjusting device is hung over the bottom of the interior of the housing.
Preferably, the pressure-adjusting device is a hollow tube.
Preferably, a diameter of the hollow tube is identical except a portion adjacent to the second opening.
Preferably, the diameter is ranged from 0.5 to 2.0 mm.
Preferably, the hollow tube is made of stainless.
Preferably, the second opening is pressed such that one regulating hole is formed thereon and the second opening is plane-shaped in cross-section.
Preferably, the second opening is pressed such that a plurality of regulating holes are formed thereon.
Preferably, the pressure-adjusting device is made of plastic.
Preferably, the pressure-adjusting device is formed by injection molding.
Preferably, the pressure-adjusting device is integrally formed with the housing by injection molding.
REFERENCES:
patent: 3661078 (1972-05-01), Hammel
patent: 4412232 (1983-10-01), Weber et al.
patent: 5409134 (1995-04-01), Cowger et al.
patent: 5600358 (1997-02-01), Baldwin et al.
patent: 5801737 (1998-09-01), Sato et al.
patent: 5988803 (1999-11-01), Komplin et al.
Chou Chin-Yi
Ho Jing-Yuan
Hsueh Ta-Wei
Leu Yi-Jing
Lin Fu-San
Michael Best & Friedrich LLC
Microjet Technology Company, Ltd.
Vo Anh T. N.
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