Ink cartridge and pressure regulating device thereof

Abstract

 An ink cartridge includes a housing (31), an air bag assembly (33), a filter assembly (34) and an elastic structure (35). The housing has an ink reservoir (311), a first vent (312), a second vent (313) and an exit port (32). The first vent and the second vent are disposed at the top and bottom of the housing, respectively. The air bag assembly is disposed within the ink reservoir, includes at least two air bags adjacent to a sidewall of the ink reservoir, and is open to the exterior air via the first vent. The filter assembly is disposed at the bottom of the housing and open to the exterior air via the second vent, and includes a filter for adjusting a flow rate of the exterior air flowing into the ink reservoir so as to smoothly adjust the inflation/deflation of the air bag assembly in response to a pressure change in the ink reservoir. The elastic structure is fixed onto the filter assembly or the bottom of the ink reservoir, and comprises at least two elastic sheets disposed between the at least two air bags of the air bag assembly for applying thereon an elastic force.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to an ink cartridge, and more particularly to an ink cartridge with a pressure regulating device.

BACKGROUND OF THE INVENTION

[0002] With increasing development of a personal computer, inkjet printers become indispensable printing peripheral device for personal computers. With regard to the components of an inkjet printer, the ink cartridge is a very important expendable of the inkjet printer. For a purpose of enabling the ink cartridge to reach an optimum condition and preventing ink leakage during the printing period, the internal pressure regulating device should maintain a desirable performance, such that the back pressure of the ink cartridge can be maintained at a stable level. Therefore, a constant volume of ink can be supplied in operation. Otherwise, if the back pressure of the ink cartridge fails to be maintained at a stable level, the ink contained therein is likely to leak from the printhead or fails to be ejected out, and the service life of the ink cartridge will be reduced accordingly.

[0003] The inkjet printers are typically classified into two types, i.e. a thermal bubble inkjet printer and a piezoelectric inkjet printer. So far, the thermal bubble inkjet printer is relatively popular. The thermal bubble inkjet printer is operated by rapidly heating a small volume of ink to cause the ink to vaporize and be ejected through one of a plurality of nozzles so as to print a dot of ink on a medium such as a paper. The piezoelectric inkjet printer allows piezoelectric quartz crystals to result in a constant oscillating frequency in response to an electrical signal, thereby ejecting the ink through the one of a plurality of nozzles.

[0004] The term "back pressure" used herein indicates that a partial vacuum within the ink cartridge or the pressure that is slightly smaller than the external atmospheric pressure of the ink cartridge. The back pressure can permit the ink within the ink cartridge to be maintained at a stable state and inhibit the flow of the ink through the printhead as the printhead is inactive. Also, the back pressure permits the ink to be ejected out smoothly as the printhead is active. In order to maintain the back pressure of the ink cartridge at a stable level and prevent ink leakage or no supplied ink during the printing period, the thermal bubble inkjet printer should have a specifically designed pressure regulating device with respect to different operating conditions such as pressures, temperatures or amount of ink.

[0005] For the thermal bubble inkjet printer, the pressure regulating devices are classified into the two types, as will be illustrated in details as follows.

[0006] A pressure regulating device utilizes a porous cotton filter as the ink storing and giving element. In the beginning, a porous cotton filter is mounted in the ink cartridge. Subsequently, by a siphonal effect, the ink is absorbed in the porous cotton filter. However, since the absorption capacity of the ink is about 85% of the volume of the porous cotton filter, the ink cartridge fails to store a sufficient amount of ink. In addition, since the adsorbed ink fails to be fully released, a portion of the ink may be maintained in the porous cotton filter when the ink cartridge is discarded. On the other hand, the composition of the ink comprises several corrosive components. After a long period of time, the porous cotton filter may be corroded and the residues thereof may block the nozzles of the printhead. Furthermore, since the porous cotton filter is flexible and readily deformed by an external force, the procedure of placing the porous cotton filter in the ink cartridge is time consuming.

[0007] Another pressure regulating device utilizes an air bag, a combination of an air bag and an elastic spring, or a combination of an air bag and depressor. By using this pressure regulating device, the ink cartridge can store a larger amount of ink when compared with the porous cotton filter. Referring to Figs. 1 (a) and 1(b), a conventional air bag-type pressure regulating device used in an ink cartridge is shown. The ink cartridge comprises a housing 11, an exit port 12, two air bags 13, a pair of elastic sheets 14 and a tube 15. The housing 11 defines an ink reservoir 111 for storing ink. The neck portions of the air bags 13 are secured to the bottom of a connecting body 112. The connecting body 112 has a through hole for permitting ventilation between the air bags 13 and the exterior air. One end of each elastic sheet 14 is disposed at the connecting body 112 and the inner surface of each elastic sheet 14 is attached on the air bag 13. The tube 15 extends from the top to the bottom of the ink reservoir 111. The elastic sheets 14 work with the air bags 13 and enable the air bags 13 to inflate or deflate in response to the changes in pressure. Such inflation/deflation takes place when the pressure inside the ink reservoir 111 changes as well as when the pressure outside of the ink reservoir 111 changes.

[0008] As known from the structures of Figs. 1(a) and 1(b), the more the inflation-to-deflation ratio of the air bag 13 is, the pressure of the ink reservoir can be adjusted within a broader range. Since one end of each elastic sheet 14 is disposed at the connecting body 112 above the housing 11, the portion of the air bag 13 in the vicinity of the connecting body 112, which has a length of about 10 mm, fails to fully spread due to restriction by the elastic sheets 14. In addition, when the elastic sheets 14 spread to the maximum as the air bags 13 inflates, the tail ends of the elastic sheets 14 may be sustained against the sidewall of the ink cartridge, and thus the air bags 13 no longer inflate to further adjust pressure within the ink cartridge as well as release ink. On the other hand, the tube 15 can adjust pressure within the ink cartridge according to a siphonal effect. When the ink stored in the ink reservoir 111 is lower than a critical level, the ink remained in the tube 15 may flow out, such that the exterior air flows in the ink reservoir 111 and the back pressure is destroyed. Therefore, the ink remained in the ink cartridge may flow out from the exit port 12. Even though the critical level is changed and lowered to a recess at the bottom of the ink cartridge, the ink remained in the tube 15 may flow out and the back pressure is readily destroyed when the ink cartridge is reversed.

[0009] Referring to Fig. 2, another conventional pressure regulating device of an ink cartridge is shown. The ink cartridge 2 comprises an upper portion 22 and a lower portion 21, which together form an ink reservoir 23 for storing ink. The upper portion 22 has an ink-filling hole 221 for introducing ink therethrough. After the ink reservoir 23 is refilled with ink, the ink-filling hole 22 is closed by a plug 222.

[0010] An air bag 24 is disposed within the ink reservoir 23. Via a guide pipe 223, the air bag 24 is open to the exterior air, and thus the exterior air can be introduced into the air bag 24 so as to adjust pressure within the ink cartridge. The ink reservoir 23 has a pressing plate 25 and an elastic component 26. One end of the elastic component 26 is connected to a sidewall of the pressing plate 25, while the other end thereof is connected to a sidewall of the lower portion 21. The opposite sides of the air bag 24 are connected to another sidewall of the lower portion 21 and another sidewall of the pressing plate 25. The arrangement of the elastic component 26 will exert a force against the air bag 24 to keep a back pressure so as to form an initial value of the back pressure in the ink reservoir 23 and avoid ink leakage.

[0011] The bottom of the lower portion 21 has an exit port 211. A printhead 27 is disposed on the exit port 211 so as to eject ink to printing medium. Furthermore, the lower portion 21 further comprises a gas supplement channel 212 formed between the sidewalls 213. A block 28, for example a ball such as a steel ball, is disposed on the top of the gas supplement channel 212. The bottom of the ink reservoir 23 comprises an elastic structure 29, which has a first portion 29a in contact with the block 28 and a second portion 29b in contact with the pressing plate 25.

[0012] In the structure of Fig. 2, in a case that the air bag 24 in the ink reservoir 23 inflates to a predetermined extent as the ink is consumed, the air bag 24 will push the pressing plate 25 toward the direction B. Meanwhile, the pressing plate 25 will push the second portion 29b of the elastic structure 29 such that the first portion 29a of the elastic structure 29 is not in contact with the block 28. In such manner, air is introduced into the ink reservoir 23 via the gas supplement channel 212 and thus the volume of the air bag 24 is reduced. On the other hand, in a case that the air bag 24 deflates, the pressing plate 25 is pushed toward the direction A. Meanwhile, the pressing plate 25 will push the second portion 29b of the elastic structure 29 such that the first portion 29a of the elastic structure 29 is firmly in contact with the block 28 and the exterior air is closed by the block 28.

[0013] The pressure regulating device of Fig. 2 still has some problems. For example, since the elastic structure 29 and the gas supplement channel 212 are disposed on the bottom of the lower portion 21, the pressing plate 25 can be pushed by the air bag 24 to an insufficient extent. In addition, since the sensitivity of using the air bag 24 to control the pressing plate 25 is undesired, the exterior air flowing into the ink reservoir 23 may result in environmental change and impair maintenance of the back pressure. In other words, the ink contained therein is likely to leak from the printhead or fails to be ejected out, and the service life of the ink cartridge will be reduced accordingly.

SUMMARY OF THE INVENTION

[0014] It is an object of the present invention to provide an ink cartridge with a pressure regulating device so as to increase stability, sensitivity and adjustable pressure range thereof. It is another object of the present invention to provide an ink cartridge with a pressure regulating device for maintaining a back pressure so as to prevent ink leakage.

[0015] In accordance with a first aspect of the present invention, there is provided an ink cartridge. The ink cartridge comprises a housing, an air bag assembly, a filter assembly and an elastic structure. The housing has an ink reservoir, a first vent, a second vent and an exit port. The first vent and the second vent are disposed at the top and bottom of the housing, respectively. The air bag assembly is disposed within the ink reservoir, comprises at least two air bags adjacent to a sidewall of the ink reservoir, and is open to the exterior air via the first vent. The filter assembly is disposed at the bottom of the housing and open to the exterior air via the second vent, and comprises a filter for adjusting a flow rate of the exterior air flowing into the ink reservoir so as to smoothly adjust the inflation/deflation of the air bag assembly in response to a pressure change in the ink reservoir. The elastic structure is fixed onto the filter assembly or the bottom of the ink reservoir, and comprising at least two elastic sheets disposed between the at least two air bags of the air bag assembly for applying thereon an elastic force.

[0016] In an embodiment, the exit port is disposed at the bottom of the housing for ejecting ink to printing medium.

[0017] In an embodiment, the housing further comprises a circuitous channel communicates with the filter assembly and the second vent so as to adjust the amount of the exterior air flowing into the ink reservoir.

[0018] In an embodiment, the elastic structure further comprises a base connected with the elastic sheets.

[0019] In an embodiment, the elastic structure is fixed onto said filter assembly by engaging the base of the elastic structure with a fastening recess of the filter assembly.

[0020] In an embodiment, the elastic structure further comprises at least two extension plates in contact with respective air bags of the air bag assembly and connected to top ends of the elastic sheets.

[0021] In an embodiment, the second vent is covered with a cover plate so as to protect the filter.

[0022] In accordance with a second aspect of the present invention, there is provided a pressure regulating device of an ink cartridge. The ink cartridge comprises a housing having an ink reservoir, a first vent, a second vent and an exit port. The pressure regulating device comprises an air bag, a filter assembly and an elastic sheet. The air bag is disposed within the ink reservoir, adjacent to a sidewall of the ink reservoir, and open to the exterior air via the first vent. The filter assembly is disposed at the bottom of the housing and open to the exterior air via the second vent, and comprises a filter for adjusting a flow rate of the exterior air flowing into the ink reservoir so as to smoothly adjust the inflation/deflation of the air bag in response to a pressure change in the ink reservoir. The elastic sheet is in contact with the air bag and applies an elastic force on the air bag.

[0023] In accordance with a second aspect of the present invention, there is provided an ink cartridge. The ink cartridge comprises a housing, an air bag and an elastic sheet. The housing has an ink reservoir, a first vent, a second vent and an exit port. The air bag is disposed within the ink reservoir, adjacent to a sidewall of the ink reservoir, and open to the exterior air via the first vent. The elastic sheet is in contact with the air bag and applying an elastic force on the air bag.

[0024] The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Fig. 1(a) is a cross-sectional view illustrating a conventional pressure regulating device of an ink cartridge in a deflation state;

[0026] Fig. 1(b) is a cross-sectional view illustrating a conventional pressure regulating device of an ink cartridge in an inflation state;

[0027] Fig. 2 is a cross-sectional view illustrating another conventional pressure regulating device with an air bag;

[0028] Fig. 3(a) is a cross-sectional view illustrating a pressure regulating device of an ink cartridge according to a preferred embodiment of the present invention;

[0029] Fig. 3(b) is a cross-sectional view illustrating an air bag of the pressure regulating device of Fig. 3(a) in a deflation state;

[0030] Fig. 3(c) is a cross-sectional view illustrating the extension plate of the pressure regulating device of Fig. 3(a);

[0031] Fig. 3(d) is a partial enlarged cross-sectional view illustrating an filter assembly of the pressure regulating device of Fig. 3(a); and

[0032] Figs. 4(a)~(d) are cross-sectional views illustrating the operating mechanisms of the pressure regulating device according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0033] Referring to Figs. 3(a)~(d), a pressure regulating device of an ink cartridge according to a preferred embodiment of the present invention is shown. The ink cartridge comprises a housing 31 having therein an ink reservoir 311 for storing ink. The housing 31 has a first vent 312 and a second vent 313 disposed at the top and bottom thereof, respectively. The first vent 312 and the second vent 313 are open to the exterior air. The bottom of the housing 31 has an exit port 32 communicates with the ink reservoir 311 so as to eject ink to printing medium.

[0034] An air bag assembly 33 is disposed within the ink reservoir 311. The air bag assembly 33 comprises at least two air bags adjacent to inner sidewalls of the ink reservoir 311. The air bag assembly 33 is open to the exterior air via the first vent 312. Inflation/deflation of air bag assembly 33 takes place when the pressure inside the ink reservoir 311 changes as well as when the pressure outside of the ink reservoir 311 changes.

[0035] Furthermore, a filter assembly 34 is disposed at the bottom of the housing 31, preferably at the center thereof. The filter assembly 34 comprises a filter 341 and a fastening recess 343. The filter 341 can be made of any porous high-density polymer. The housing 31 further comprises a circuitous channel 342 communicates with the filter 341 and the second vent 313 so as to adjust the amount of the exterior air flowing into the ink reservoir 311. By means of the filter 341, the flow rate of the exterior air flowing into the ink reservoir 311 is limited and thus the inflation/deflation of the air bag assembly 33 in response to the pressure change becomes smooth. The second vent 313 is covered with a cover plate 36 so as to protect the filter 341.

[0036] An elastic structure 35 is fixed onto the filter assembly 34 or the bottom of the housing 31. The elastic structure 35 comprises a base and two elastic sheets, wherein two elastic sheets are integrally formed with the base. The base of the elastic structure 35 is fixed onto the filter assembly 34 or the bottom of the housing 31 by engaging the inner edges of the base with a fastening recess 343 of the filter assembly 34 or a fastening recess (not shown) on the bottom of the housing 31. Two elastic sheets of the elastic structure 35 are disposed between the two air bags of the air bag assembly 33, extend upwardly from the base of the elastic structure 35, and contact with respective air bag. Furthermore, the elastic structure 35 comprises two extension plates 351. The extension plates 351 are connected to the top ends of the elastic sheets and in contact with the respective air bags of the air bag assembly 33. As the air bag assembly 33 inflates, the extension plates 351 will be pushed to move from the sidewall toward the middle portion of the ink reservoir 311.

[0037] The elastic sheets and the extension plates 351 work with the air bag assembly 33 so as to enable the air bag assembly 33 to inflate or deflate in response to the changes in pressure. Figs. 4(a)~(d) illustrate the operating mechanisms of the pressure regulating device according to the present invention. For purposes of clarity, only the inflating mechanism of the left air bag cooperating with one elastic sheet and one extension plate 351 are illustrated in the drawings. In Fig. 4(a), the left air bag of the air bag assembly 33 deflates to a minimum volume. Meanwhile, the extension plate 351 is substantially in contact with a sidewall of the ink reservoir 311, and the top end of the elastic sheet is also in contact with the sidewall of the ink reservoir. In a case that the left air bag inflates as the ink is consumed, the extension plate 351 and the elastic sheet will be pushed toward right, as is shown in Fig. 4(b). Then, as shown in Fig. 4(c), the left air bag continuously inflates, and the extension plate 351 and the elastic sheet are also pushed toward right. Until the air bag inflates to a maximum volume, the elastic sheet is almost upright, as shown in Fig. 4(d). The inflation/deflation of the air bag assembly 33 is more smoothly and moderately due to cooperation of the elastic sheets and the extension plates 351.

[0038] The pressure regulating device provided by the present invention, when comparing with other previous conventional technologies, has following advantages. For example, when the air bag assembly inflates to its maximum volume, the air bag assembly can fully spread because the elastic sheets are upright without contacting with the sidewall of the ink reservoir 311. Therefore, the sensitivity of using the air bag assembly 33 to control the back pressure is higher. In addition, the arrangement of the filter 341 facilitates controlling amount of the exterior air flowing into the ink reservoir 311 such that the problem of ink leakage is avoided.

Claims

1. An ink cartridge comprising:

a housing (31) having an ink reservoir (311), a first vent (312), a second vent (313) and an exit port (32), wherein said first vent (312) and said second vent (313) are disposed at the top and bottom of said housing (311), respectively;

an air bag assembly (33) disposed within said ink reservoir (311), comprising at least two air bags adjacent to a sidewall of said ink reservoir (311), and open to the exterior air via said first vent (312);

a filter assembly (34) disposed at the bottom of said housing (31), open to the exterior air via said second vent (313), and comprising a filter (341) for adjusting a flow rate of the exterior air flowing into said ink reservoir (311) so as to smoothly adjust the inflation/deflation of said air bag assembly (33) in response to a pressure change in said ink reservoir (311); and

an elastic structure (35) fixed onto said filter assembly (34) or the bottom of said ink reservoir (311), and comprising at least two elastic sheets disposed between said at least two air bags of said air bag assembly (33) for applying thereon an elastic force.

2. The ink cartridge according to claim 1 characterized in that said exit port (32) is disposed at the bottom of said housing (31) for ejecting ink to printing medium.

3. The ink cartridge according to claim 1 characterized in that said housing (31) further comprises a circuitous channel (342) communicates with said filter assembly (34) and said second vent (313) so as to adjust the amount of the exterior air flowing into said ink reservoir (311).

4. The ink cartridge according to claim 1 characterized in that said elastic structure (35) further comprises a base connected with said at least two elastic sheets.

5. The ink cartridge according to claim 4 characterized in that said elastic structure (35) are fixed onto said filter assembly (34) by engaging said base of said elastic structure (35) with a fastening recess (343) of said filter assembly (34).

6. The ink cartridge according to claim 1 characterized in that said elastic structure (35) further comprises at least two extension plates (351) in contact with respective air bags of said air bag assembly (33) and connected to top ends of said elastic sheets.

7. The ink cartridge according to claim 1 characterized in that said second vent (313) is covered with a cover plate (36) so as to protect said filter (341).

8. A pressure regulating device of an ink cartridge, said ink cartridge comprising a housing (31) having an ink reservoir (311), a first vent (312), a second vent (313) and an exit port (32), said pressure regulating device comprising:

an air bag disposed within said ink reservoir (311), adjacent to a sidewall of said ink reservoir (311), and open to the exterior air via said first vent (312);

a filter assembly (34) disposed at the bottom of said housing (31), open to the exterior air via said second vent (313), and comprising a filter (341) for adjusting a flow rate of the exterior air flowing into said ink reservoir (311) so as to smoothly adjust the inflation/deflation of said air bag in response to a pressure change in said ink reservoir (311); and

an elastic sheet in contact with said air bag and applying an elastic force on said air bag.

9. The pressure regulating device according to claim 8 further comprising an extension plate (351) in contact with said air bag and connected to a top end of said elastic sheet.

10. An ink cartridge comprising:

a housing (31) having an ink reservoir (311), a first vent (312), a second vent (313) and an exit port (32);

an air bag disposed within said ink reservoir (311), adjacent to a sidewall of said ink reservoir (311), and open to the exterior air via said first vent (312); and

an elastic sheet in contact with said air bag and applying an elastic force on said air bag.

Drawing