Fluid cartridge for a fluid supply system

[0001] The present disclosure relates generally to fluid cartridges, and more specifically, to a fluid cartridge for a fluid supply system.

[0002] Inkjet printers often use replaceable fluid cartridges to supply ink and / or other fluids to the printing device to form an image on the print substrate. Some fluid cartridges contain one or more internal chambers configured to store ink, these chambers often being separated by a wall having an air / ink exchange port formed therein. This air / ink exchange port provides air and / or ink communication between the chambers. The ink is selectively drawn from one or more chambers and is fed and ejected through the print head nozzles and then onto the print substrate. In some cases, however, fluid may continue to flow through the printhead even when the printhead is not activated by the printer.

[0003] To prevent free flow of ink when the print head is not in use, negative or back pressure is created inside the cartridge, which overcomes the pressure on the print head when this print head is not in use. Thus, a vacuum is created in the free ink chamber of the cartridge and the ink is held inside. The back pressure inside the free ink chamber of the cartridge is generally maintained due to capillary forces as well as the flow of air and / or ink back and forth through the air / ink exchange port. However, there may be difficulties in maintaining back pressure in the cartridge when additional, unforeseen air enters the air / ink exchange port from various areas of leakage that may occur during the construction of the fluid cartridge.

[0004] Further difficulties may arise due to the lack of the desired back pressure. For example, if one cartridge does not provide sufficient back pressure, the ink may leak from the nozzles onto the nozzle plate and then be sucked through the back pressure by a cartridge of a different color. This can result in unwanted color mixing.

[0005] US 6505923 discloses a fluid cartridge for a printing device, comprising a housing, a wall dividing the housing into the first and second chambers, and an air / ink exchange port providing fluid communication between the two chambers.

The present invention relates to a fluid cartridge according to claim 1. Preferred embodiments of this invention are defined in the dependent claims.

Description of the drawing figures [0007] The features and benefits of the embodiment (s) of the present disclosure will become apparent from reference to the following detailed description and the drawing figures, in which similar reference numerals correspond to similar, but not necessarily identical, components. The reference numerals having the function described above need not be described in connection with the other figures in which they appear.

[0008] Fig. 1 is a top perspective view of an embodiment of a fluid cartridge as disclosed in this document;

[0009] Fig. 2 is an enlarged, perspective cutaway view of an embodiment of a fluid cartridge showing an air / ink exchange port made therein;

[0010] Fig. 3A is a cross-sectional side view of an embodiment of a fluid cartridge taken along lines 3-3 in Fig. 1;

[0011] Fig. 3B is a cross-sectional side view of the fluid cartridge taken along lines 3-3 in Fig. 1 illustrating an alternative embodiment thereof;

[0012] Fig. 4 is a bottom view of an embodiment of a fluid cartridge showing a longitudinal path of air flow;

[0013] Fig. 5 is a perspective view of an embodiment of a fluid cartridge showing a transverse air flow path (s);

[0014] Fig. 6 is an enlarged perspective view, cut away, of another embodiment of a fluid cartridge; and [0015] Fig. 7 is another enlarged perspective view, cut out, of an embodiment of the fluid cartridge of Fig. 6.

Detailed Description [0016] In the example (s) of implementing the fluid cartridge for the fluid supply system as disclosed in this invention, it is preferable that the air flow to the air / ink exchange port from various undesirable air flow paths is restricted or otherwise restricted. form in a liquid cartridge. This narrowing of the air flow substantially maintains the level of back pressure in the cartridge, and thus reduces unwanted fluid flow through the nozzle (s). This novel air flow narrowing is preferably achieved by positioning the air restricting members adjacent the air / ink exchange port. Incorporation of these members into the cartridge structure may also advantageously widen the margin of error to precisely dimension and position the ink-absorbing materials within the cartridge.

[0017] Referring now to the drawings, Fig. 1 illustrates a fluid cartridge 10 for an inkjet printing device (not shown). Some non-limiting examples of printing devices include thermal spray printers, piezoelectric spray printers, continuous spray printers and / or combinations thereof. The fluid cartridge 10 comprises a housing 12 formed by any suitable means and from any suitable material, such as, for example, through integral molding of a polymeric material. The housing 12 includes an internal space defined by the base 14 and a continuous sidewall 16 extending around the perimeter of the base 14. The cover 18 (illustrated in Fig. 3) containing the vent 20 is welded, glued or otherwise attached to the side wall 16 and closes the inner space of the housing 12. The housing 12 and the cover 18 can be formed of similar or different polymeric materials, which can also be opaque or transparent. Non-limiting examples of suitable polymeric materials include polypropylenes, alloy-bonded polypropylenes with polystyrenes, polyphenylene oxide, polyurethanes, and combinations thereof.

[0018] The wall 22 is located inside the housing 12, located substantially perpendicular to the base 14 and extends outwards from the base 14. The wall 22 also abuts the opposite side walls 16, thereby forming the first and second chambers 24, 26 in the housing 12. A joint or edge 28 is formed between the wall 22 and the base 14, as well as between the wall 22 and the adjacent opposite side wall 16.

[0019] The ink outlet or port 30 is formed in a base 14 located in the second chamber 26. The ink outlet 30 is generally coupled to a printhead manifold (not shown) comprising a number of ink nozzles. The ink outlet 30 is also coupled to the first and / or second chamber 24, 26, and thus fluid communication between the ink outlet 30 and the chambers 24, 26 is provided.

[0020] Referring now to Fig. 2, the air / ink exchange port 32 is defined at the bottom of wall 22 and is located adjacent to base 14. This port 32 is essentially a gap or aperture formed in wall 22 at connection 28, and thus in principle, the connection of the wall and the base is essentially revealed. Port 32 is designed to facilitate the movement of air and the movement of ink between the first and second chambers 24, 26.

[0021] Referring now to Fig. 3, the first chamber 24 is configured to store a certain volume of free flowing liquid ink, and will also be referred to in this document as the free ink chamber (FIC) 24. For type printing "Drop on demand", e.g. in thermal spray printers or piezoelectric spray printers, capillary strength of capillary agents (e.g. absorber 40, 40a, described below) generally contributes to drawing ink out of the FIC chamber 24 through the air / ink exchange port 32, but this is balanced by the negative pressure generated in the FIC chamber 24. When air bubbles enter the FIC chamber 24 through air / ink exchange port 32, then the ink is sucked into the material / absorbent 40, 40a until the vacuum in the FIC chamber 24 is stabilized again. Material / absorbent ink 40, 40a comes out of the ink outlet 30 to feed the ink to the printing device. When the volume of ink is depleted in the free ink chamber 24, air is sucked into the cartridge 10 via a vent 20 formed in the cover 18, and also passes through the second chamber 26 and into the air / ink exchange port 32. To enter the FIC chamber 24, it is generally desirable for air from vent 20 to pass through the saturated capillary materials / absorbents 40, 40a, 40b and not through wrinkles and voids around the perimeter of the capillary materials / absorbents 40, 40a, 40b.

[0022] In one embodiment, as better illustrated in Fig. 1, a number of grooves 34 may be formed in a portion of the side 36 of the wall 22 facing the second chamber 26 and substantially directly above the air / ink exchange port 32 and this is used to facilitate the movement of air from vent 20 to port 32. The grooves 34 generally extend up the wall 22 in such a way that when the level of ink saturation in the capillary materials / absorbents 40, 40a, 40b reaches the top of the grooves 34, the air can start to pass into the FIC chamber 24, thereby allowing ink to enter the materials / absorbents 40, 40a, 40b. The air then moves into the free ink chamber 24 through the ink in such a way that the air is above the ink in the upper part 38 of the chamber 24. In this way, the free ink chamber 24 has approximately the same volume of fluid (i.e., ink and air) because the volume of ink in the free ink chamber 24 is replaced by air when the ink is removed from the cartridge 10 by the printhead.

[0023] Basically, when the print head is started, the print head forces ink to flow through the nozzles. When the printhead is turned off, this printhead limits the flow of ink through it. The nozzles are still open when the print head is turned off, but the pores are small enough that the capillary forces at the nozzles essentially prevent air from entering the cartridge through the nozzles. Because the nozzles are open, in some cases, unwanted ink leakage may occur if the cartridge 10 does not provide the desired back pressure.

[0024] To substantially prevent ink from dripping and / or leaking through the nozzles, back pressure is generated at the printhead when the printhead is inactive, as mentioned briefly above. As used herein, the term "back pressure" refers to a partial vacuum created inside the ink cartridge 10 to resist the flow of ink through the printhead. In this way, the increase in back pressure can be referred to as a partial vacuum increase, and it can be measured by the height of the water column. It is generally desirable to maintain a sufficiently strong back pressure at the printhead to substantially prevent ink from dripping. It should be understood, however, that the back pressure should be a suitable pressure such that the print head overcomes the back pressure and ejects the ink when activated.

[0025] In an ideal system, the desired level of back pressure is continuously maintained in the ink cartridge 10 at the print head. However, changes in back pressure can often occur, for example, when the surrounding environment changes or the printhead is operating. When the print head ejects a drop of ink, the depletion of ink in the free ink chamber 24 increases the back pressure of the chamber 24, thereby creating a greater vacuum.

[0026] In one embodiment, and with reference to Figs. 1 and 3A, the second chamber 26, also referred to in this document as the absorbent chamber 26, is filled with an absorbent 40 configured to absorb ink from the free ink chamber 24, and thereby creating back pressure in the free ink chamber 24. This back pressure (underpressure) in the FIC 24 chamber is mitigated by the ingress of air bubbles into the FIC 24 chamber. It should be noted that the absorbent 40 has been removed in Fig. 1 due to the clarity of the message. Absorbent 40 is a porous material with strong capillary action

- (e.g. a highly capillary material) and generally a layered texture that is compressible at its edges, without creating wrinkles or gaps in the porous material. In one embodiment, the absorbent 40 is selected in such a way that it has the desired capillary properties. Suitable capillary forces for absorbent 40 can range from about 2 "WC (water column) to about 6" WC; while in an alternative embodiment, the appropriate capillary force is about 4 "WC. As the ink pressure increases in the free ink chamber 24, the ink is transferred to the absorbent 40 and stored in its pores. To balance the back pressure in the cartridge 10, the ink stored in the pores may in some cases be transferred back to the free ink chamber 24. For example, when falling from a higher level or cooling from a higher temperature, the ink will flow from the absorbent 40 into the FIC chamber 24. In cases like this, the air in the FIC chamber 24 shrinks. During normal printing, the ink will be sucked into the absorbent 40 and the air will be sucked into the FIC 24 chamber by the negative pressure present in the FIC 24 chamber.

[0027] In another embodiment, and also now with reference to Fig. 3B, the second chamber 26 may be filled with the first absorbent 40a located adjacent the second absorbent 40b. The first absorbent 40a is configured similarly to absorbent 40 as illustrated in Fig. 3A. The second absorbent 40b is also a porous material but has low capillary action. As a non-limiting example, the first ink absorbent 40a is located below the second absorbent 40b and in fluid communication with it. In one embodiment, the second absorbent 40b (e.g., low capillary material (LCM)) has capillary forces of about 3 "WC, while the first absorbent 40a (e.g., high capillary material (HCM)) has capillary forces of about 4 "toilet. The lower capillary forces of the second absorbent 40b essentially ensure that substantially all of the ink is withdrawn from the second absorbent 40b before the first absorbent 40a is drained of the ink.

[0028] Although some exemplary capillary forces are used above for the first absorbent 40a and the second absorbent 40b, it should be understood that any suitable capillary material having suitable capillary forces can be used herein. Generally, the second absorbent 40b provides sufficient back pressure to prevent leakage from the nozzles. The first absorbent 40a should have higher capillary forces than the second absorbent 40b. Some suitable example capillary forces for the second absorbent 40b range from about 2 "WC to about 5" WC; and also for the first absorbent 40a range from about 3 "WC to about 6" WC.

[0029] Without imposing restrictions by any theory, it is believed that it is desirable for the cartridge 10 to empty substantially all of the second absorbent 40b first and then to empty a small amount of the first absorbent 40a to open the bubble path for air entering the FIC chamber 24 , followed by consistent emptying of substantially the integrals of the FIC chamber 24 prior to removing any additional ink from the first absorbent 40a. One of the reasons why this method is thought to be desirable is the applicability

- low ink detection (LOID) system (not illustrated). A sensor configured to detect when the FIC chamber 24 is emptied allows the printer to be notified that essentially the only ink remaining in the cartridge 10 is in the first absorbent 40a. This generally allows the printer to more accurately predict when to stop printing, to prevent dry running of the nozzles and potential damage to the print head. However, if the first absorbent 40a is sometimes emptied halfway when the FIC chamber 24 is emptied, due to e.g. delayed air path opening via the air / ink exchange port 32 to the FIC chamber 24; while at other times the first absorbent 40a and part of the second absorbent 40b are full of ink when the FIC chamber 24 is emptied, e.g. as a result of an immeasurable path to the 32 bubble / air / ink exchange port, the LOID system may become less useful.

[0030] Because the back pressure level of the cartridge 10 may be affected by environmental changes, performance, etc., it is generally beneficial to prevent any undesirable fluids, especially air, from entering the air / ink exchange port 32. As shown in Figs. 4 and 5, potentially foreign air paths 44, 46 (generally represented by arrows illustrating their direction) essentially result from the design of the cartridge 10 itself. These air paths 44, 46 could get into the air / ink exchange port 32 and negatively affect the level of back pressure in the cartridge 10 between the chambers 24, 26. The first air path 44 (illustrated in Fig. 4) is a substantially longitudinal air path formed in the absorption chamber 26 along the base 14, between the ink outlet 30 and the air / ink exchange port 32. A first air path 44 can be formed when the absorbent 40 is located inside the enclosure 12, and thus there remain small air gaps between the absorbent 40 and the base 14.

[0031] The other potential air path (s) 46 are essentially transverse air paths formed at the connection or edge 28, and also extend transversely from the connection 28 to both transverse sides 48, 50 of the air / ink exchange port 32. The air path (air paths) 46 can be formed when the wall 22 is located inside the enclosure 12, but is not integrally formed with it, and thus small gaps are left at connection 28, which may leak to port 32. For example, the air path (s) 46 may be formed by a crease, gap or miter in the absorbent 40, 40a that allow air to flow along the corner between the absorbent 40, 40a and the housing 12.

[0032] Referring again to Fig. 1, the air path 44 can be narrowed or otherwise restricted by positioning the longitudinal flow restricting member 52 having two opposite sides 54, 56 adjacent to the air / ink exchange port 32 on base 14. Longitudinal the air restricting member 52 extends substantially outwardly from the wall 22 and from the air / ink exchange port 32 a predetermined distance to the absorption chamber 26.

[0033] In an alternative embodiment (examples), the air path (air paths) 46 may also be narrowed by positioning a transverse airflow restricting member 60 supporting / adjacent to one of the two opposing sides 54, 56 of the longitudinal member restricting air flow 52.

[0034] It should be understood that the elongated airflow limiting member (members) 52 may be of any suitable size, shape and / or configuration, may be formed of any suitable material for that purpose, and may be located in any suitable for this purpose in place sufficiently to advantageously restrict / narrow the longitudinal air flow as described in this document.

[0035] Still making reference to Fig. 1, in one embodiment, the elongate airflow limiting member 52 is essentially a threshold such as an insert, step or other kind of raised element that is located inside the absorbent chamber 26 between the base 14 and the absorbent 40 , 40a (shown in Figs. 3A and 3B) and located at the air / ink exchange port 32. In one embodiment, the elongate airflow limiting member 52 extends through the air / ink exchange port 32 and ends in a substantially planar face of the wall 22 towards the cavity 24 (as best seen in Fig. 7).

[0036] It is within the scope of the present disclosure that the longitudinal airflow limiting member 52 can be attached to the cartridge 10 by any suitable member having any suitable thickness as well as any suitable width.

[0037] In one embodiment, the member 52 is integrally formed with the housing 12. The thickness of the member 52 may generally be less than about 2 mm, this thickness preferably causing local compression of the adjacent absorbent 40, 40a. The member 52 is generally as wide as the air / ink exchange port 32; nevertheless, it may in some cases be advantageous for the member 52 to be wider (as illustrated by the dashed lines in Fig. 6) than port 32. In one embodiment, the member 52 is about 3 mm wider, on each side, than port 32. It is believed that in some implementations, such a wider threshold 52 may result in more uniform capillary material at the air / ink exchange port 32.

[0038] In general, the thickness of the member 52 is relatively small, but thick enough to squeeze the absorbent capillaries 40, 40a when the member 52 is located and installed in the cartridge 10. This results in reduced pore size / local compression of the capillaries in the absorbent 40, 40a adjacent to member 52. Without imposing restrictions by any theory, it is believed that this reduced pore size can generate a relatively high capillary force, e.g. of about 8 "WC, thereby maintaining the capillary pores filled with ink, as well as preventing air from moving between the base 14 and the absorbent 40, 40a until reaching the air / ink exchange port 32.

[0039] As with the longitudinal airflow limiting member (members) 52, it should be understood that the transverse airflow limiting member (members) 60 (as long as it is used) can be of any suitable size, shape and / or configuration for this purpose, may be formed of any suitable material for this purpose, and may also be located in any suitable place for that purpose, to preferably restrict / narrow transverse airflow as described in this document.

[0040] In one embodiment, one transverse airflow limiting member 60 is located in the absorbent chamber 26 adjacent the wall 22 and side 54 of the longitudinal airflow limiting member 52. If desired, the second member 60 (substantially identical and constituting mirror image of one member 60) may be located on the other side 56 limiting the longitudinal air flow of the member 52. In one embodiment, the member (members) 60 are substantially triangular-shaped inserts (e.g., corners), substantially rectangular-shaped inserts, essentially quarter-circle or wedge-shaped inserts, and oh combinations. The member (members) 60 may be located substantially perpendicular to the side 36 of the wall 22 towards the second chamber 26 and substantially parallel to the air / ink exchange port 32 and thereby restricting or otherwise restricting the air flow through the transverse airflow paths 46 and to port 32.

[0041] Referring now to Figs. 6 and 7, this embodiment does not include a transverse airflow limiting member 60. In this embodiment, as well as in any of the embodiments disclosed in this document, fluid cartridge 10 may further include one or more ribs 62 formed on / in the base 14, on / in the longitudinal airflow limiting member 52, or on / in combinations thereof. Without imposing restrictions by any theory, it is believed that the fins 62 form capillary pathways to facilitate or otherwise support the flow of ink fluid between the free ink chamber 24 and the absorbent chamber 26 when air flows through it, or remains stationary at the exchange port 32 air / ink. In one embodiment (as best seen in Fig. 6), the ribs 62 are formed on / in the threshold 52, which extends by the convexity of the wall surface 22 into the chamber 26. As best seen in Fig. 7, in one embodiment, the ribs 62 can further extend on the threshold 52 through the exchange port 32 air / ink and partly to the FIC 24 chamber.

[0042] It is desirable that the edges formed at the base of the fins 62 are relatively sharp and not substantially curved, since the bubbles are believed to hardly adapt to the sharp corners. It should be understood that the ribs 62 may be of any suitable size, however, in one embodiment, the ribs 62 may be from about 0.2 mm to about 0.6 mm wide; and from about 0.2 mm to about 0.6 mm in height. In one embodiment, the fins 62 are about 0.4 mm wide and about 0.4 mm high. The space between the ribs 62 may range from about 0.2 mm to about 0.6 mm. In one embodiment, the space between the ribs is about 0.4 mm.

[0043] The ribs 62 can also operate so that they substantially prevent air from passing through the air / ink exchange port 32, breaking the fluid connection between the absorbent 40, 40a and the free ink chamber 24. For example, when the air is fast

Drawn into the FIC 24 chamber, it can suddenly reduce the underpressure in the FIC 24 chamber and disconnect fluid in the FIC 24 chamber from the absorbent / material / HCM 40, 40a. When this happens, the ink in the FIC chamber 24 is blocked because the absorbent 40, 40a cannot draw it into the ink 40, 40a. Nevertheless, thanks to the ribs 62, it is believed that the capillaries are held so as to allow the absorbent 40, 40a to draw ink from the FIC chamber 24. This ink drawn from the FIC 24 chamber gradually increases the negative pressure in the FIC 24 chamber, which creates a pressure difference to draw more air into the FIC 24 chamber. As more air is drawn into the 32 air / ink exchange port, any blocking bubbles port 32 is generally shifted and flows into the FIC chamber 24, thereby restoring proper operation. Moreover, although a single rib 62 may function appropriately in some cases, it is believed that the additional ribs 62 may advantageously reduce the possibility that all of the capillary path potentials along the edge between threshold 52 and ribs 62 will be blocked by air bubbles.

[0044] In one embodiment, the fluid chamber may be formed by using a housing 12 including a base 14, a free ink chamber 24, and an absorbent chamber 26. The wall 22, containing the air / ink exchange port 32 defined in its lower part, is located in the housing and extends outwardly from and substantially perpendicular to the base 14, thereby separating the free ink chamber 24 and the absorbent chamber 26. The longitudinal airflow limiting member 52 is located in the absorption chamber 26 adjacent the air / ink exchange port 32 and extends outwardly from it a certain predetermined distance. The absorbent 40, 40a can then be placed inside the absorption chamber 26 and at the member 52 in such a way that the capillary edges of the absorbent 40 are compressed, thereby limiting unwanted air flow through it from the longitudinal air flow path 44.

[0045] If the transverse airflow limiting member (s) 60 is used in one embodiment, they may be located in the absorption chamber 26, adjacent sides 54, 56 of member 52, respectively, and also adjacent to an air / ink exchange port 32 . This can be done by any suitable method, however, in one embodiment, the transverse airflow limiting members 60 are formed within the housing 12, while the insertion of the absorbent 40, 40a causes the members 60 to pierce the capillary or porous absorbent material 40, 40a essentially without deforming the capillaries. The member (members) 60 are thus formed inside the chamber 26, adjacent to the air / ink exchange port 32, and also substantially restrict undesirable airflow from the airflow transverse path (s) 46. If desired, a second absorbent 40b (formed from e.g. a low-capillary material) can then be placed in contact with and in fluid communication with the first absorbent 40a (formed e.g. high capillary material) before the cover 18 is attached to the housing 12.

[0046] The present disclosure provides many advantages, some of which include the following. The airflow limiting members 52, 60 may advantageously substantially narrow / restrict unwanted airflow from eg air paths 44, 46. Without imposing restrictions by any theory, it is believed that limiting air flow from air paths 44, 46 through e.g. operatively placing / forming members 52, 60 allows conveniently regulating the back pressure in the cartridge 10 between the free ink chamber 24 and the absorption chamber 26. This can substantially prevent leakage through the nozzles. The members 52, 60 may also allow the structure of absorbents 40, 40a, 40b to be simplified. For example, to prevent additional unwanted air flow through the air / ink exchange port 32 from different paths (non-limiting examples of which are defined in this document), absorbents 40, 40a, 40b may require very specific dimensioning and trimming as well as complicated installation procedures to prevent the creation of such potential air paths. The members 52, 60 can advantageously eliminate this need for precision when producing and installing absorbents 40, 40a, 40b.

[0047] Although several embodiments have been described in detail, it will be understood by those skilled in the art that the embodiments disclosed herein may be modified, and are within the scope of the claimed invention.

- 11 PZ / 2095 / AG

EP 2 136 997 B1