Ink cartridge

Abstract

 An ink cartridge comprises a housing (11) defining an ink chamber (12) and a negative pressure chamber (13). The negative pressure chamber (13) receives therein a porous body (14) impregnated with liquid ink and having a mound (41) at the top surface for defining a space (15) between the top surface and the inner wall of the negative pressure chamber (13). A vent (18) communicated with the space (15) through a uniform passage (17) and an ink outlet port (19) are disposed at the bottom of said negative pressure chamber for alignment in a plane and sealed by a common seal tape (21).

Description

BACKGROUND OF THE INVENTION

(a) Field of the Invention

[0001] The present invention relates to an ink cartridge and, more particularly, to an ink cartridge having a negative pressure chamber.

(b) Description of the Related Art

[0002] Referring to Fig. 1, a first conventional ink cartridge generally designated by 120 comprises a housing 124 having an ink outlet port 128, a cap 126 having a vent 125, a porous body 123 impregnated with liquid ink and installed inside the housing 124, and a filter 122 disposed between the ink outlet port 128 and the porous body 123 for removing dust from the ink to be supplied through the ink outlet port 128. The ink cartridge is described in JP-A-2(1990)-34351. A space 127 is disposed between the porous body 123 and the cap 126 for preventing the liquid ink from being contacted with the vent 125. The structure of the ink cartridge 120 is effective for prevention of the leakage of the liquid ink due to oscillation or vibration caused by the movement of the associated recording head.

[0003] Assuming that the maximum amount of the liquid ink which can be impregnated in the porous body 123 is 100 (%), the liquid ink is generally impregnated in the porous body 123 in an amount of around 80 (%) for prevention of the ink leakage from the porous body 123 through the vent 125, which may be caused by the movement of the recording head. The prevention of ink leakage is effective for the arrangement, so long as the housing 124 is laid down, as shown in Fig. 1.

[0004] Installation of the ink cartridge may be generally effected by the following two processes: one in which the porous body 123 is installed after impregnation with liquid ink and the other in which the liquid ink is impregnated in the porous body 123 after the installation of the porous body 123 in the housing 124. In the former case, the cap 126 is generally screwed to the housing 124 by using an O-ring for sealing instead of adhesion or ultrasonic bonding technique because of the difficulty of the adhesion or ultrasonic bonding. In the latter case, adhesion or ultrasonic bonding technique can be used for the mounting of the cap 126 to the housing. However, in the latter case, application of an adhesive should be used after mounting for assuring the seal between the cap and the housing. Then, the liquid ink is injected by an injector needle through the filter into the porous body.

[0005] In the first conventional ink cartridge, if the ink cartridge is placed with the cap 126 downward for a long time, if a vibration is applied to the housing 124 in the direction of the axis of the housing, if the amount of liquid ink impregnated in the porous body 123 is nearly equal to the amount of 100 (%), or if the amount of ink exceeding 100 (%) is injected in the housing 124, then it is likely that the liquid ink leaks through the vent 125 passing on the surface of the inner wall of the cap 126, which causes a pollution inside the recording device or on the recording sheet.

[0006] Referring to Fig. 2, a second conventional ink cartridge generally designated by 100 comprises a housing 101, a cap 108 having a vent 106, a porous body 104 made of urethane, for example, for impregnating liquid ink therein, a water-repellent porous body 103 made of polyethylene foam disposed between the porous body 104 and the vent 106 and in contact with the vent 106. Since the liquid ink is not impregnated in the water-repellent porous body 103 and the circulation of air is secured thereby through the three-dimensional structure thereof, the possibility of the ink leakage is extremely small. Further, the circulation of air is secured by the porous structure of the water-repellent porous body 103, even if some portion of the water-repellent porous body 103 may be blocked by fixing of ink.

[0007] There is a disadvantage in the first and second conventional ink cartridges as described above in that the presence of the porous body in the entire ink chamber increases the volume of the ink cartridge, wherein the liquid ink can be received in an amount at most several tens of percents of the total volume of the cartridge.

[0008] A third conventional ink cartridge, described in JP-A-8(1996)-174858, has a smaller volume for the porous body. Specifically, referring to Fig. 3, the third conventional ink cartridge 200 comprises a housing 201 defining an ink chamber 203 for receiving liquid ink therein, and a negative pressure chamber 202 communicated with the ink chamber 203 through an internal port 205 and receiving therein a porous body 204 impregnated with liquid ink. The housing 201 has an ink port 207 and a vent 212 communicated with the negative pressure chamber 202 through a passage 206 having a enlarged passage portion 211. The enlarged passage portion 211 prevents the ink leakage from the vent 21, whereas the ink chamber 203 without the porous body increases the amount of liquid ink to be received in the ink cartridge.

SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to provide an ink cartridge capable of preventing an ink leakage from the vent with a simplified structure of the housing.

[0010] In accordance with the present invention, there is provided an ink cartridge comprising a housing defining a first chamber for receiving liquid ink therein and a second chamber communicated with the first chamber, a porous body received in the second chamber and having a mound at a top surface thereof for defining a space between the top surface and an inner wall of the second chamber, the housing having a vent for communicating the space and outside the housing and an ink outlet port for supplying liquid ink.

[0011] In accordance with the ink cartridge of the present invention, the mound of the porous body maintain the space between the porous body and the inner wall of the housing, which prevents contact between the porous body and the passage for the vent. As a result, an ink leakage is prevented from the vent.

[0012] The above and other objects, features and advantages of the present invention will be more apparent from the following description, referring to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] 

Fig. 1 is a sectional view of a first conventional ink cartridge;

Fig. 2 is a sectional view of a second conventional ink cartridge;

Fig. 3 is a sectional view of a third conventional ink cartridge;

Fig. 4 is a sectional view of an ink cartridge according to an embodiment of the present invention;

Fig. 5 is a detailed sectional view of the porous body shown in Fig. 4; and

Figs. 6A and 6B are partial enlarged views of ink cartridges according to modified embodiments of the present invention.

PREFERRED EMBODIMENTS OF THE INVENTION

[0014] Now, the present invention is more specifically described with reference to accompanying drawings.

[0015] Referring to Fig. 4, an ink cartridge 10 according to an embodiment of the present invention comprises a housing 11 defining a first chamber or ink chamber 12 for receiving liquid ink therein and a second chamber or negative pressure chamber 13 separated from the ink chamber 12 by a separating wall 22 having a communication port 23 communicating the ink chamber 12 with the negative pressure chamber 13, and a porous body 14 received in the negative pressure chamber 13 for impregnating liquid ink therein. The porous body 14 is disposed to leave a space 15 between the top surface of the porous body 14 and the inner wall of the housing 11. The entire area of each of the other surfaces of the porous body 14 is substantially in contact with the inner wall of the housing 11.

[0016] The housing 11 has an ink outlet port 19 at the central portion of the bottom of the negative pressure chamber 13. The ink outlet port 19 is communicated to the porous body 14 through a filter 20 for discharge of the liquid ink impregnated in the porous body 14 in the negative pressure chamber 13. The housing 11 also has a vent 18 disposed at an edge of the housing 11 and communicated with the space 15 in the negative pressure chamber 13 through an air passage 17 having an opening 16 at the space 15. The ink outlet port 19 and the vent 18 are disposed substantially in a plane at the bottom of the housing 11, and sealed by a seal tape 21 before the ink cartridge is in use. The passage 17 has a uniform cross section.

[0017] In operation of the ink cartridge according to the present embodiment, after some liquid ink is discharged through the ink outlet port 19, the pressure in the space 15 within the negative pressure chamber 13 falls to a negative pressure, which allows the air to be introduced through the vent 18 and the passage 17. The negative pressure in the space prevents the liquid ink in the porous body 14 from leaking outside the ink cartridge through the passage 17 and the vent 18.

[0018] Referring to Fig. 5, the porous body 14 is substantially of a hexahedron except for a mound 31 disposed at the top surface thereof. The porous body 14 has a maximum height of h1 and a minimum height of h3, as shown in the solid line, just after it is fabricated, and has a maximum height of h2, as shown in the broken line, wherein h3<h2<h1, after the porous body 14 is installed in the negative pressure chamber 13. The portion 32 between the height h1 and the height h2 is thrust downward by the inner wall of the housing 11 to allow the porous body 14 to have a truncated pyramid shape at the top portion of the porous body 14, which allows the space 15 to be left in the negative pressure chamber 13.

[0019] The portion of the bottom of the porous body 14 disposed right under the top 31a of the mound 31 and in the vicinity of the ink outlet port 19 is most strongly thrust by the inner wall of the chamber, as a result of which the capillary function of the porous body 14 is intensified therein. This helps the liquid ink impregnated in the porous body 14 to be directed to the ink outlet port 19.

[0020] Referring to Figs. 6A and 6B showing modifications of the ink cartridge according to the embodiment of Fig. 4 in partial sectional views, the vent 41 and 42 are disposed at the top surface and side surface, respectively, of housing outside the negative pressure chamber 13. The elements similar to those in Fig. 4 are designated by the same reference numerals in Figs. 6A and 6B, and detailed description thereof are omitted herein. These modifications also achieve the advantages similarly to the embodiment of Fig. 4, although a single seal tape does not provide a seal for both the ink outlet port and the vent.

[0021] Since the above embodiments are described only for examples, the present invention is not limited to the above embodiments and various modifications or alterations can be easily made therefrom by those skilled in the art without departing from the scope of the present invention.

Claims

1. An ink cartridge comprising a housing (11) defining a first chamber (12) for receiving liquid ink therein and a second chamber (13) communicated with said first chamber (12), a porous body (14) received in said second chamber (13), said housing (11) having a vent (18) for communicating said second chamber (13) and outside said housing (11) and an ink outlet port (19) for supplying the liquid ink, characterized in that:

said porous body (14) has a mound (41) at a top surface thereof for leaving a space (15) between said top surface and an inner wall of said second chamber (13).

2. An ink cartridge as defined in claim 1, wherein said vent (18) is communicated with said space through a passage (17) having a substantially uniform cross-section.

3. An ink cartridge as defined in claim 1 or 2, wherein said ink outlet port (19) is disposed substantially right under a top portion of said mound (41).

4. An ink cartridge as defined in one of claims 1 to 3, wherein said vent (18) and said ink outlet port (19) are disposed substantially in a plane.

5. An ink cartridge as defined in claim 4, wherein said vent (18) and ink outlet port (19) are sealed by a single seal member (21).

6. An ink cartridge as defined in one of claims 1 to 5, wherein said mound (41) is thrust by the inner wall of said second chamber (13).

Drawing