BACKGROUND OF THE INVENTION
1. Field of the Invention
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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
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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.
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It is an advantage of the claimed invention that
the ink cartridge can adjust internal pressure within
the ink reservoir.
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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
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- 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.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.