BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention relates to an ink cartridge used in an ink jet printing device,
and more particularly, to an ink cartridge with an ability to adjust internal fluid
pressure automatically.
2. Description of the Prior Art
[0002] As personal computers become more popular, ink jet printing devices are becoming
a most common computer output / printing device used by people, families, and companies,
because a price and a quality of the ink jet printers attract customers to buy.
[0003] A typical ink jet printing device has a printing head that moves along a track, back
and forth, to print on a document. The printing head usually has at least an ink cartridge,
and the ink cartridge comprises a housing with an ink reservoir for storing ink, and
a print head connected to the ink reservoir to control the ink jetting. In a typical
ink jet printing device, flow control is usually employed to control the ink jetting
out to the document from the ink reservoir. Typical print head flow control mechanisms
are divided into two types: thermal-bubbles and pressure-waves. The thermal-bubbles
print head comprises a thin-film resister. When the resistor is heated, a trace of
ink vaporizes immediately, quickly expanding to make ink pass through the print head,
and print on the document. Although the print head using the flow control can get
ink from the ink reservoir and jet ink effectively, the flow control needs a controlling
mechanism, so that the print head does not seep ink when not in use. The controlling
mechanism usually provides a light negative pressure to prevent ink from seeping onto
the print head. The negative pressure is partial vacuum in the ink cartridge, so that
the external atmospheric pressure is slightly higher than the fluid pressure in the
ink cartridge. The negative pressure is indicated by a positive value, so an increase
in the negative pressure means an increased vacuum of the ink cartridge, and a greater
difference between the external atmospheric pressure and the fluid pressure in the
cartridge. By increasing the negative pressure, ink is prevented from seeping from
the print head.
[0004] Although increasing the negative pressure prevents ink from seeping out of the print
head, the negative pressure has an upper limit. If the negative pressure is too high,
ink cannot overcome the negative pressure and jet from the print head. On the other
hand, the ink cartridge must be able to adjust the negative pressure in the ink reservoir
automatically by changing the pressure of the surrounding environment to maintain
a suitable range. For example, when the pressure of the surrounding environment decreases,
the negative pressure causing ink not to seep through the print head is higher. Furthermore,
the "operating-effect" of the ink reservoir also affects the negative pressure of
the ink reservoir. For example, when the ink in the ink reservoir is continually consumed,
the negative pressure of the ink reservoir increases. At this time, unless the negative
pressure is adjusted appropriately, the print head ejects less ink, which affects
the printing quality, such that the print head may not even jet ink any more.
[0005] In the prior art, the negative pressure of the ink reservoir is controlled by a "regulator"
in the ink reservoir. The regulator is usually an elastic air bag. By stretching the
elastic air bag between a maximum volume and a minimum volume, the volume of stored
ink in the ink reservoir also changes to adjust to changes of the negative pressure.
For example, when the pressure of the surrounding environment decreases, the negative
pressure of the ink reservoir also decreases. At this time, the regulator starts to
increase the volume used for storing ink in the ink reservoir. Therefore, the negative
pressure is increased, and the ink does not seep.
[0006] A major shortcoming of the prior art elastic air bag regulator is that the maximum
volume of the elastic air bag has limits. When ink is consumed to a predetermined
degree, and the elastic air bag expands to the maximum volume, the volume of stored
ink in the ink reservoir does not change any more. Continued reduction of ink volume
causes the negative pressure to exceed the range, and the ink does not overcome the
negative pressure to jet from the print head, such that the ink in the ink trough
is not used completely and is wasted.
[0007] Another kind of prior art used to control the negative pressure in the ink trough
is a bubble generator. As disclosed in American Patent no. 5,526,030, the bubble generator
is set in the ink reservoir and has a jet hole through the housing of the ink cartridge.
With the jet hole, external air can enter into the ink reservoir. The controlling
mechanism in the bubble generator designed appropriately makes ink gather in the jet
hole and utilizes the capillarity of ink to form a liquid seal. When the negative
pressure of the ink reservoir rises to a predetermined degree, external air overcomes
the liquid seal and enters into the ink reservoir as a bubble. Thus, the negative
pressure of the ink reservoir decreases. Furthermore, as a result of the bubble entering
into the ink reservoir and negative pressure reducing, the liquid seal of the jet
hole rebuilds to prevent bubbles from continuing entering.
[0008] However, the bubble generator above uses surface tension of ink and static water
pressure of ink to control bubbles entering into the ink reservoir. Therefore, the
primary shortcomings of the prior art above are: 1.) When using different ink, the
surface tension of ink is different, and the bubble generator needs to be redesigned;
2.) When remaining ink is reduced, static water pressure of the ink changes, and an
pressure adjusting capability of the bubble generator is limited. 3.) For a negative
pressure of the ink reservoir as bubbles enter being the designed value, the bubble
generator must be designed precisely, increasing the difficulties of manufacturing
and assembling.
SUMMARY OF THE INVENTION
[0009] It is therefore a primary objective of the present invention to provide an ink cartridge
with an ability to adjust pressure automatically, regardless of atmospheric pressure
effects.
[0010] According to the claimed invention, the ink cartridge comprises a housing with an
ink reservoir for storing ink. The housing has a first vent, a second vent and an
opening. The opening is installed at a bottom end of the housing and is connected
to the ink reservoir. The ink cartridge further comprises an air bag installed in
the ink reservoir and connected to the first vent. The first vent enables external
air to enter the air bag, and the air bag adjusts pressure within the ink reservoir.
An elastic restricting device is installed in the ink reservoir for restricting air
in the air bag, to prevent the ink in the ink reservoir from seeping through the opening.
An elastic plugging device elastically plugs the second vent of the housing. And,
an active shaft is movably installed in the ink reservoir for pushing the elastic
plugging device. Consumption of the ink in the ink reservoir causes the air bag to
expand. When the air bag expands to a predetermined degree, the air bag moves the
active shaft, the active shaft pushes the elastic plugging device, and air enters
into the ink reservoir through the second vent to reduce the volume of the air bag.
When the air bag stops moving the active shaft, the elastic plugging device elastically
plugs the second vent.
[0011] It is an advantage of the claimed invention that the ink cartridge can adjust internal
pressure within the ink reservoir.
[0012] These and other objectives and advantages of the present invention will no doubt
become obvious to those of ordinary skill in the art after having read the following
detailed description of the preferred embodiment that is illustrated in the various
figures and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013]
Fig.1 is an overhead view of the present invention ink cartridge.
Fig.2 is a cross-sectional diagram of the ink cartridge along a tangent 2-2 shown
in Fig.1.
Fig.3 is a structural diagram of an elastic plugging device and an active shaft shown
in Fig.2.
Fig.4 is a diagram of the elastic plugging device operated by an active shaft to open
a second vent of the present invention cartridge.
Fig.5 is a diagram of the elastic plugging device of a second preferred embodiment
of the present invention cartridge.
Fig.6 is a diagram of the elastic plugging device of a third preferred embodiment
of the present invention cartridge.
Fig.7 is a diagram of the elastic plugging device of a fourth preferred embodiment
of the present invention cartridge.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0014] Please refer to Fig.1. Fig.1 is an overhead view of the present invention ink cartridge
11. The ink cartridge 11 comprises a housing 10 with an ink reservoir 20. A top 12
of the housing 10 has a first vent 30 and a ink-pour opening 16, and a bottom 14 of
the housing 10 has a second vent 50 and an ink-exit opening 200. Ink stored in the
ink cartridge 11 is poured in through the ink-pour opening 16. When the ink cartridge
10 is full of ink, there is a seal-up cover 18 to seal up the ink-pour opening 16.
The ink cartridge 11 provides ink through the ink-exit opening 200. Additionally,
the ink-exit opening 200 connects to an ink jet printing head and other relative circuitry
used to control the ink jetting to print.
[0015] Please refer to Fig.2. Fig.2 is a cross-sectional diagram of the ink cartridge 11.
As above, the present invention ink cartridge 11 uses the housing 10 to cover the
ink reservoir 20 and provides ink through the ink-exit opening 200. To prevent ink
seeping from the ink-exit opening 200 when not supplying ink, the ink reservoir 20
must keep a predetermined negative pressure. As mentioned above, although there are
several prior art mechanisms to keep negative pressure, they all have shortcomings.
To overcome the shortcomings of the prior art, the present invention ink cartridge
11 uses a new negative pressure control mechanism. The negative pressure control mechanism
comprises an air bag 32, an elastic restricting device 34, an active shaft 40, and
an elastic plugging device 100. The air bag 32 is a seal-up hollow bag and is isolated
from the fluid in the ink reservoir 20. It connects to a first vent 30 of the top
12 of the housing 11 only by a first ventilated pipe 33, so that external air can
pass in and out of the air bag 32. The elastic restricting device 34 comprises a press
board 36 and a first spring 38. One end of the first spring 38 is fixed on a wall
of the housing 10, and the other end is fixed on the press board 36, so that the spring
38 presses the air bag 32 through the press board 36. The active shaft 40 is fixed
on the bottom of the housing 14, and it is an elastic element. The detailed structure
of the elastic plugging device 100 is shown in Fig.3.
[0016] Please refer to Fig.3. Fig.3 is a detailed structural diagram of the elastic plugging
device 100. The elastic plugging device 100 is set in the ink reservoir 20 and on
the bottom of the housing 14 of the present invention ink cartridge 11 to control
the switch of the second vent 50. The elastic plugging device 100 comprises a flat
panel 102, a second spring 104, and a spherically shaped plug 106. The flat panel
102 is fixed on the housing 10 and has a round hole 103. The second spring 104 is
fixed on the flat panel 102 to elastically support the spherically shaped plug 106.
The housing 10 forms a projective edge 110 around the second vent 50. The projective
edge 110 surrounds the second vent 50 to form a round hole 111 smaller than the spherically
shaped plug 106 to limit the position of the spherically shaped plug 106. Please note
that the spherically shaped plug 106 is not fixed on the projective edge 110, and
it is only pasted tightly on the projective edge 110 by the upward thrust of the second
spring 104. Fig.3 also shows relative positions of the active shaft 40 and the elastic
plugging device 100. The active shaft 40 is fixed on the housing 10 with a fixing
latch and extends to the spherically shaped plug 106 of the elastic plugging device.
In a situation where the active shaft 40 lacks an external force, the horizontal section
46 of the active shaft keeps a fixed distance with the spherically shaped plug 106,
and both do not make contact. Therefore, the spherically shaped plug 106 is only pasted
tightly on the projective edge 110 by the upward thrust of the second spring 104,
and thus seals up the second vent 50.
[0017] The working principle of keeping the negative pressure in the present invention ink
cartridge 11 is described below. Please refer to Fig.2 again. When the ink cartridge
11 is full of ink, the air bag 32 is pressed to the right wall of the ink reservoir
20 along a direction 54 (i.e. the right direction of the figure) by the first spring
38 of the elastic restricting device 34. Please note that the press board 36 is not
in contact with the active shaft 40. By transferring the ink in the ink cartridge
11 to the printing head through the opening 200, the vacuum degree of the ink reservoir
20 also raises. At this time, the air bag 32 expands because of inhaling external
atmosphere through the first vent 30 to make up for the vacuum left by consumed ink
in the ink reservoir 20. As the air bag 32 expands along a direction 52 (i.e. the
left direction of the figure) by ink consumption, the first spring 38 of the elastic
restricting device 34 continuously exerts pressure upon the air bag 32 through the
press board 36 along a direction 54 to appropriately restrict the expansion of the
air bag 32, so that the ink reservoir 20 keeps an appropriate negative pressure.
[0018] By consuming more ink of the ink reservoir 20, the air bag 32 expands along the direction
52 and pushes the press board 36 toward the left of the figure. When the air bag 32
expands to a predetermined degree, the press board 36 contacts and pushes the active
shaft 40 to trigger the elastic plugging device 100. Please refer to Fig.4 for more
detailed information. Fig.4 is a diagram of the elastic plugging device 100 being
triggered by the active shaft 40. When the air bag 32 expands to a predetermined degree,
the press board 36 is pushed to the left of the figure along the direction 52 until
the active shaft 40 is contacted and pushed. At this time, the elastic active shaft
40 composed of reeds is bent downward by the thrust of the press board 36 along the
direction 52, and the horizontal section 46 of the active shaft 40 presses the spherically
shaped plug 106 downward. After the spherically shaped plug 106 is pressed downward
to leave the projective edge 110, the spherically shaped plug 106 and the projective
edge 110 are not closely contacted any more, and a channel allowing external atmospheric
air to enter appears. The external atmospheric air enters the ink reservoir 20 from
the second vent 50 through the round hole 103 of the flat panel 102 and the round
hole 111 of the projective edge 110 to fill in the vacuum of the ink reservoir 20
because of ink consumption. By the external atmospheric air entering into the ink
reservoir 20 through the second vent 50, the fluid pressure in the ink reservoir (i.e.
the total pressure of the air and ink in the ink reservoir) gradually increases, and
the resistance of the air bag 32, which expands along the direction 52, against the
press board is higher. Finally, the force generated by the gradually increasing fluid
pressure, as external atmospheric air enters, and by the elastic restricting device
34 in the ink reservoir 20, along the direction 54, exceeds the expanding force of
the air bag 32, along the direction 52, and the press board 36 is pushed to the right
of the figure, along the direction 54, and leaves the active shaft 40. After the force
acting on the active shaft 40 by the press board 36 disappears, the elasticity of
the active shaft restores the horizontal section 46 of the active shaft to horizontal,
and stops pressing the spherically shaped plug 111 downward. The upward elasticity
of the second spring 104 presses the spherically shaped plug 106 to tightly seal the
projective edge 110 again, to seal the second vent 50. The entire elastic plugging
device 100 is also restored to the status in Fig.3, i.e. the active shaft 40 does
not receive any force, and the spherically shaped plug 106 tightly seals the projective
edge 110 to seal the second vent 50. If ink is consumed, such that the air bag 32
expands to a predetermined degree again, the above process of opening / closing the
second vent happens repeatedly until the ink is exhausted.
[0019] In short, the main spirit of the present invention ink cartridge 11 is controlling
the elastic plugging device 100 to open or close the second vent 50 with the air bag
32 through the press board 36 and the active shaft 40 to maintain the negative pressure
of the ink reservoir 20. In the prior art method of maintaining the negative pressure
of the ink reservoir with the air bag, the vacuum in the ink reservoir because of
the ink being consumed is filled up with the air bag. However, the volume of the air
bag is limited. When the air bag expands to the maximum volume, the function of adjusting
the negative pressure cannot be produced any longer. In the present invention ink
cartridge 11, the vacuum in the ink reservoir due to the ink consumption is not only
filled up by the air bag 32, but opening the second vent 50 by the elastic plugging
device 100 to import external atmospheric air also balances the vacuum in the ink
reservoir 20. Therefore, the present invention ink cartridge can continuously maintain
the stability of the negative pressure until ink is exhausted.
[0020] The prior art bubble-generator as disclosed in American Patent No.5,526,030 also
uses a controlling mechanism to control an import air vent opening to import external
atmospheric air to maintain the negative pressure of the ink reservoir. However, the
operating key of the controlling mechanism relates to the surface tension and the
static water pressure of the ink. The structure is precise and complicated, and increases
the difficulty of production and manufacturing. If the types of ink filled in the
ink cartridge are different, the controlling mechanism must be redesigned because
the surface tensions of the ink are also different. Furthermore, as ink is consumed,
the static pressure of the ink decreases . Once reduced to a particular degree, the
controlling mechanism loses efficacy. In contrast with the negative pressure maintaining
mechanism of the prior art ink cartridge, the air bag 32 engages with the active shaft
40 through the press board 36 to control the elastic plugging device 100 to open or
prevent the external atmospheric air entering into the ink reservoir 20 through the
second vent 50. The key of the controlling mechanism is the fluid pressure of the
ink reservoir. Therefore, the negative pressure mechanism of the present invention
ink cartridge can continuously work until ink is exhausted, and it does not need to
be redesigned or remanufactured depending on the type of ink used. Furthermore, the
structure of the negative pressure keeping mechanism of the present invention ink
cartridge is simple, small, and easy to produce, manufacture, and assemble. It is
better than the prior art.
[0021] The negative pressure maintaining mechanism of the present invention ink cartridge
further includes a double protecting mechanism to maintain the closed state of the
second vent. Please refer to Fig.3 again. Please note that the negative pressure maintaining
mechanism of the present invention ink cartridge comprises two elastic components,
one is the active shaft 40, and the other elastic component is the second spring 104
pressing the spherically shaped plug 106 to tightly seal the projective edge 110.
If the external atmosphere changes frequently, in the process of maintaining the negative
pressure by the active shaft 40, the press board 36 pushes repeatedly. If the active
shaft 40 is worn down because of the repeated operations, or the external atmosphere
changes violently, so that the press board 36 pushes the active shaft 40 violently,
the active shaft may be deformed forever and lose elasticity. Even if the press board
36 leaves the active shaft 40, the horizontal section 46 of the active shaft 40 still
cannot restore a horizontal state, and continuously contact with the spherically shaped
plug. At this time, the second spring 104 supporting the spherically shaped plug 106
functions to double protect and push the spherically shaped plug 106 upward to tightly
seal the projective edge 110 and seal up the second vent 50. If not for the second
spring 104, the active shaft, losing elasticity, continuously presses the spherically
shaped plug 106 downward, and the second vent 50 cannot be sealed to let the external
atmosphere enter continuously. Finally, the negative pressure cannot be kept, and
the ink seeps from the second vent 50. The second spring 104 of the elastic plugging
device 100 in the present invention ink cartridge 11 avoid this shortcoming completely.
[0022] Please refer to Fig.5. Fig.5 is a diagram of the elastic plugging device 100 of a
second preferred embodiment of the present invention. Specifically, the bottom panel
102 and the second spring 104 are replaced with a monolithically elastic bottom panel
180 in the preferred embodiment. Like the second spring 104 of the first preferred
embodiment, the elastic bottom panel 180 elastically supports the spherically shaped
plug 106. In the situation of the elastic plugging device 100 not exerting force,
the second vent 50 is sealed.
[0023] Please refer to Fig.6. Fig.6 is a diagram of the elastic plugging device 100 of a
third preferred embodiment of the present invention. In the preferred embodiment,
the spherically shaped plug 208 is an elastic, spherically shaped plug that tightly
presses against the projective edge 110 to seal the second vent 50 with a hard bottom
panel 282. When the active shaft pushed by the press board 36 presses the spherically
shaped plug 208 downward, the spherically shaped plug 208 maintains a gap to allow
the external atmospheric air to enter the ink reservoir from the round hole 111 of
the projective edge 110 as a result of deformation.
[0024] Please refer to Fig.7. Fig.7 is a diagram of the elastic plugging device 100 of a
fourth preferred embodiment of the present invention. In this preferred embodiment,
the active shaft, which seals up the spherically shaped plug of the second vent 50
and triggers the plastic plugging device, is replaced by a monolithically plugging
cover 700. The plugging cover has a rotating axis 720, in which is installed a shearing
stress spring 730 (not shown in Fig.7), through a hole of the projective edge 710
corresponding to the axis 720, to elastically connect the plugging cover 700 to the
housing 10. When the plugging cover 700 is not triggered by the press board 36, the
shearing stress spring 730 adds a shearing stress on the plugging cover 700 in a clockwise
direction, with 720 acting as the axis, so that the plugging cover 700 tightly presses
the second vent 50 and seals it. When the press board 36 is pushed to the left (relative
to the figure) by expansion of the air bag 32, the press board 36 causes the plugging
cover 700 to rotate anticlockwise around the axis 720, so that the external atmospheric
air enters from the second vent 50 to adjust the negative pressure of the ink reservoir
20.
[0025] The basic spirit of the above mentioned preferred embodiments of the present invention
is using the air bag 32 to control the elastic plugging device 100 to open or close
the second vent 50 through the active shaft and adjust the negative pressure of the
ink reservoir 20. When the elastic plugging device 100 is not triggered by the active
shaft, the elastic design of the elastic plugging device 100 can force sealing of
the second vent. When ink is consumed in the well 20, the air bag 32 expands. When
the air bag 32 expands to a predetermined degree, the air bag 32 triggers the elastic
plugging device 100, through the press board 36 or the active shaft 40, and opens
the second vent 50 to import the external atmospheric air to increase the fluid pressure
in the well and keep the stability of the negative pressure. After the prior art air
bag expands to a predetermined degree, it is no longer able to develop the function
of keeping the negative pressure.
[0026] After the present invention air bag expands to a predetermined degree, importing
the external atmospheric air to help maintain the negative pressure. This overcomes
the shortcoming of the prior art air bag. Furthermore, with the prior art bubble generator,
the triggering mechanism relates to the surface tension and the static water pressure
of the ink. The structure is too complex and increases the difficulty of producing
and manufacturing. The design lacks of elasticity and has to change with different
kinds of ink. The operations are unavoidably affected by the operation of the ink
cartridge. In contrast, the present invention ink cartridge uses the expanding of
the air bag to trigger the elastic plugging device. The design is succinct, well-executed,
easy to produce, assemble, and manufacture. Different kinds of ink and operation effects
of the ink cartridge do not influence operation of the present invention. Finally,
the elastic design of the elastic plugging device 100 of the present invention ink
cartridge maintains sealing of the second vent 50, even if the active shaft 40 loses
efficacy and continuously triggers the elastic plugging device 100. Operation is not
affected by errors of the active shaft 40.
[0027] Those skilled in the art will readily observe that numerous modifications and alterations
of the device may be made while retaining the teachings of the invention. Accordingly,
the above disclosure should be construed as limited only by the metes and bounds of
the appended claims.
1. An ink cartridge comprising:
a housing with an ink reservoir for storing ink, the housing having a first vent,
a second vent and an opening, the opening installed at a bottom end of the housing
and connected to the ink reservoir;
an air bag installed in the ink reservoir and connected to the first vent, the first
vent enabling external air to enter into the air bag, the air bag adjusting internal
pressure within the ink reservoir;
an elastic restricting device installed in the ink reservoir for restricting air in
the air bag to prevent the ink in the ink reservoir from seeping through the opening;
an elastic plugging device for elastically plugging the second vent of the housing;
and
an active shaft movably installed in the ink reservoir for pushing the elastic plugging
device;
wherein consumption of the ink in the ink reservoir causes the air bag to expand,
and when the air bag expands to a predetermined degree, the air bag moves the active
shaft, the active shaft pushes the elastic plugging device, and air enters into the
ink reservoir through the second vent to reduce the volume of the air bag, and when
the air bag stops moving the active shaft, the elastic plugging device elastically
plugs the second vent.
2. The ink cartridge of claim 1 wherein the elastic plugging device comprises a spherically
shaped plug and a spring for elastically pushing the spherically shaped plug to the
second vent to plug the second vent, and when the air bag moves the active shaft,
the active shaft pushes the spherically shaped plug out of the second vent so that
air enters into the ink reservoir through the second vent.
3. The ink cartridge of claim 2 wherein the active shaft is an elastic element installed
in the ink reservoir, and when the air bag expands to the predetermined degree, the
air bag pushes the elastic element so that the elastic element pushes the spherically
shaped plug out of the second vent, and when the air bag contracts, the elastic element
returns to an original form, and the spring elastically pushes the spherically shaped
plug to the second vent to plug the second vent.
4. The ink cartridge of claim 1 wherein the elastic plugging device comprises a rotating
shaft rotatably fixed in the ink reservoir of the housing, the rotating shaft comprising
a plug for plugging the second vent, the elastic plugging device further comprising
a spring for elastically pushing the plug of the rotating shaft to the second vent
to plug the second vent, and when the air bag moves the active shaft, the active shaft
pushes the plug of the rotating shaft out of the second vent so that air enters into
the ink reservoir through the second vent.
5. The ink cartridge of claim 4 wherein the active shaft is monolithically installed
on one end of the rotating shaft, and when the air bag contracts, the spring elastically
pushes the plug of the rotating shaft to the second vent to plug the second vent and
pushes the active shaft back to an original position.
6. An ink cartridge comprising:
a housing with an ink reservoir for storing ink, the housing having a first vent and
a second vent;
a printing head installed at a bottom end of the housing and connected to the ink
reservoir;
an air bag installed in the ink reservoir and connected to the first vent, the first
vent enabling external air to enter into the air bag, the air bag adjusting internal
pressure within the ink reservoir;
an elastic restraining device installed in the ink reservoir for restraining air in
the air bag to prevent the ink in the ink reservoir from seeping through the printing
head;
an elastic plugging device for elastically plugging the second vent of the housing;
and
an active shaft movably installed in the ink reservoir for pushing the elastic plugging
device;
wherein consumption of the ink in the ink reservoir causes the air bag to expand,
and when the air bag expands to a predetermined degree, the air bag moves the active
shaft, the active shaft pushes the elastic plugging device, and air enters into the
ink reservoir through the second vent to reduce the volume of the air bag, and when
the air bag stops moving the active shaft, the elastic plugging device elastically
plugs the second vent.
7. The ink cartridge of claim 6 wherein the elastic plugging device comprises a spherically
shaped plug and a spring for elastically pushing the spherically shaped plug to the
second vent to plug the second vent, and when the air bag moves the active shaft,
the active shaft pushes the spherically shaped plug out of the second vent so that
air enters into the ink reservoir through the second vent.
8. The ink cartridge of claim 7 wherein the active shaft is an elastic element installed
in the ink reservoir of the housing, and when the air bag expands to the predetermined
degree, the air bag pushes the elastic element so that the elastic element pushes
the spherically shaped plug out of the second vent, and when the air bag contracts,
the elastic element returns to an original form, and the elastic element elastically
pushes the spherically shaped plug to the second vent to plug the second vent.
9. The ink cartridge of claim 6 wherein the elastic plugging device comprises a rotating
shaft rotatably fixed in the ink reservoir of the housing, the rotating shaft comprising
a plug for plugging the second vent, the elastic plugging device further comprising
a spring for elastically pushing the plug to the second vent to plug the second vent,
and when the air bag moves the active shaft, the active shaft pushes the plug out
of the second vent so that air enters into the ink reservoir through the second vent.
10. The ink cartridge of claim 9 wherein the active shaft is monolithically installed
on one end of the rotating shaft, and when the air bag contracts, the spring elastically
pushes the plug to the second vent to plug the second vent and pushes the active shaft
back to an original position.