JPH10128990A - Ink tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent ink from leaking when a sealing member is separated from an ink supply port. SOLUTION: The tank is configured so as to have a tank body where a depression 18 deeper than the outside of the bottom wall 1 of the tank where an ink inlet 14 is formed and a circular inside adhesion area 19 which is formed of a flexible sheet sealing the ink supply port 14 to prevent ink from leaking and neighbors the circumferential edge of the ink supply port 14, and the inside adhesion area 19 and the outside adhesion area 22 are adhered to the outside of the bottom wall 1 of the tank and form a space for disconnecting ink between the depression 18 and the non-adhesion area 21 of the sealing material 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink tank used in an ink jet recording apparatus, and more particularly to an ink tank detachably mounted on an ink jet recording head.

[0002]

2. Description of the Related Art Conventionally, there has been known an ink jet cartridge used in an ink jet recording apparatus, which comprises a head cartridge having an ink jet recording head and a tank holder, and an ink tank detachable from the tank holder. . In such an ink-jet cartridge, only the ink tank needs to be replaced when the ink is consumed, which is advantageous in reducing the cost as compared with an ink-jet cartridge in which the head cartridge and the ink tank are irremovably integrated. However, in an ink jet recording apparatus using such an ink tank, when the ink tank is mounted at the time of replacing the ink tank, the ink leaks from an ink supply hole provided at a lower portion of the ink tank, and the ink enters the ink jet recording apparatus main body. There are problems such as adhesion of the toner and soiling of the user's hand.

[0003] As a method of solving such a problem,
Conventionally, the following techniques are known. (J01) (Technology described in Japanese Patent Application Laid-Open No. 6-328714) In the technique described in this publication, the inside of the ink supply hole sealed with a sealing material is provided on the wall surface around the ink supply hole provided at the lower part of the ink tank. A technology is described in which a concave portion is provided to reduce the volume of the space, and the amount of ink scattered from the ink supply hole is minimized when the sealing material is peeled off. (J02) (Technique described in Japanese Patent Application Laid-Open No. Hei 7-31537) In the technique described in this publication, at least a part of a sealing material for sealing an air communication hole and an ink tank supply hole provided at a lower portion of an ink tank is provided. The shape for relaxing the peeling force is formed. A technique is described in which the sealant is peeled off from the air communication hole side to prevent the ink from scattering.

[0004]

[Problems to be solved by the invention]

(Problem of (J01)) According to the technique of (J01), the volume of the space in the opening formed by the sealing material that seals the ink supply hole is small. Although there is a decrease, there is no measure against the ink bridge (ink film and pool formed in the wedge-shaped space between the ink tank and the seal material) when the seal material to be sealed is peeled off. Therefore, when the last part of the sealing material is peeled off,
There is a problem that the ink of the formed ink bridge is scattered. (Problem of (J02)) Even in the technique of (J02), there is no measure against the ink bridge when peeling off the sealing material to be sealed.

In view of the above circumstances, the present invention provides the following (O01)
Is the subject of the description. (O01) To prevent the occurrence of ink leakage when the sealing material is peeled off from the ink supply holes.

[0006]

Next, the configuration of the present invention devised to solve the above-mentioned problem will be described. The components of the present invention correspond to the components of the embodiments described later. For the sake of simplicity, the reference numerals of the components of the embodiment are enclosed in parentheses. The reason why the present invention is described in correspondence with the reference numerals of the embodiments described below is to facilitate understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

(Invention) In order to solve the above problems, an ink tank for an ink jet recording apparatus according to the invention,
01) A tank body (Tk, TI) having an ink supply hole (14) formed in the tank bottom wall (1) for supplying the ink filled therein to the ink jet recording head when connected to the ink jet recording head. A02) In order to prevent the ink filled in the tank body (Tk, TI) from leaking out, it is formed of a flexible sheet which is adhered to the outer surface of the tank bottom wall (1) and seals the ink supply hole (14). Sealing material (17), (A
03) An annular inner adhesive area (19) adjacent to the outer peripheral edge of the ink supply hole (14), a non-adhesive area (21) provided outside the inner adhesive area (19), and the non-adhesive area (21). Outside bonding area (22) further provided outside
Wherein the inner bonding area (19) and the outer bonding area (22) are bonded to an outer surface of the tank bottom wall (1), (A04) the sealing material (17). A concave portion recessed from the outer surface of the tank bottom wall (1) to which the outer bonding region (22) of the sealing material (17) is bonded on the outer surface of the tank bottom wall (1) facing the non-bonding region (21). The tank body (Tk, TI) provided with (18), and a space for cutting ink is formed between the concave portion (18) and the non-adhesion region (21) of the sealing material (17).

(Operation of the Present Invention) Next, the operation of the present invention having the above-mentioned features will be described. In the ink tank for an ink jet recording apparatus according to the present invention having the above-described features, when connected to the ink jet recording head, the ink filled therein flows from the ink supply hole (14) formed in the tank bottom wall (1). The ink is supplied to the ink jet recording head.
The sealing material (17) formed of a flexible sheet has an annular inner adhesive region (19) adjacent to the outer peripheral edge of the ink supply hole (14), and a non-adhesive material provided outside the inner adhesive region (19). Region (21) and the non-adhesive region (2
It has an outer bonding area (22) provided further outside of (1). An inner adhesive area (19) and an outer adhesive area (22) of the sealing material (17) are adhered to an outer surface of the tank bottom wall (1), and leakage of ink filled in the tank body (Tk, TI) is performed. The ink supply hole (1)
4) Seal. Thus, the effect of preventing the leakage of the ink can be enhanced by the double adhesive area inside and outside the sealing material (17). Outside the tank bottom wall (1) to which the outer bonding area (22) of the sealing material (17) is bonded to the outer surface of the tank bottom wall (1) facing the non-bonding area (21) of the sealing material (17). Concave recessed from the side (1
8), the recess (18) and the sealing material (17) are provided.
A space for cutting ink is formed between the non-adhesive region (21). When the sealant (17) is peeled off when the ink tank is mounted on the ink jet recording head, first, one side of the outer bonding area (22) is peeled off, and then the inner bonding area (19) moves from one side to the other side. Peel off. When the sealing material (17) in the inner bonding area (19) is peeled off, an ink bridge is formed in a wedge-shaped space formed between the sealing material (17) and the outer surface of the tank bottom wall (1).
When the sealing material (17) is peeled off from the inner bonding area (19), the sealing material (17) is formed by the ink cutting space.
The ink bridge formed by the ink adhered to the ink or accumulated in the ink supply hole (14) is cut off.

When the sealing material (17) is peeled off from the inner bonding area (19), the other side of the outer bonding area (22) is in a bonded state, so that it acts on the ink bridge when the ink bridge breaks. The force is reduced.
By reducing the adhesive strength of the inner adhesive area (19), the force acting on the ink bridge when the ink bridge breaks can be further reduced. As described above, when the force acting on the ink bridge when the ink bridge breaks becomes small, the amount of ink scattered when the ink bridge breaks can be reduced. The outer bonding area (22) after the ink bridge is broken
When the other side is peeled off, since the ink bridge is not formed in the sealing material (17), even if the sealing material (17) is pulled and peeled from the outer bonding area (22), the ink is not removed. It does not scatter and does not stain the user or peripheral devices. As described above, since the bonding regions are arranged in a double manner, even if the bonding force of the inner bonding region (19) is weakened, the effect of preventing the ink from leaking is small.

[0010]

Next, an embodiment of the present invention will be described. (Embodiment 1) An ink tank for an ink jet recording apparatus according to Embodiment 1 of the present invention is characterized by satisfying the following requirements in the present invention (A05).
The outer surface of the tank bottom wall (1) facing the inner bonding area (19) and the non-bonding area (21) of the sealing material (17) faces the outer bonding area (22) of the sealing material (17). The tank body (Tk, TI) wherein the tank bottom wall (1) is formed so as to be recessed from an outer surface and a step is formed at an outer peripheral edge of the recessed portion.

(Operation of the First Embodiment of the Present Invention) In the first embodiment of the ink tank for an ink jet recording apparatus according to the present invention having the above-described configuration, the sealing material (Tk, TI) is used in the tank body (Tk, TI). 17) The inner bonding area (1)
9) and the outer surface of the tank bottom wall (1) opposed to the non-adhesion area (21) is more concave than the outer surface of the tank bottom wall (1) opposed to the outer adhesion area (22) of the sealant (17). Is formed. Further, a step is formed on the outer peripheral edge of the recessed portion. Therefore, a space for cutting ink is formed between the non-adjacent area (21) adjacent to the step and the sealing material (17). Therefore, when the sealing material (17) is peeled off when the ink tank is mounted on the ink jet recording head, the sealing material (17) is formed by the ink cutting space on the outer peripheral portion of the concave portion on the outer surface of the tank bottom wall (1).
The ink bridge formed by the ink adhered to the ink or accumulated in the ink supply hole (14) is cut off. For this reason, since ink does not scatter, the user and peripheral devices are not stained.

(Embodiment 2 of the present invention) Embodiment 2 of the ink tank for an ink jet recording apparatus of the present invention is as follows.
(A06) The inner bonding area (19) and the outer bonding area (22) are outside the tank bottom wall (1), wherein any one of the present invention and the first embodiment has the following requirements. The sealing material (17) bonded to a side surface by heat fusion.

(Operation of the Second Embodiment of the Present Invention) In the second embodiment of the ink tank for an ink jet recording apparatus of the present invention having the above-described structure, the inner bonding area (19) ) And the outer adhesive area (2
2) is bonded to the outer surface of the tank bottom wall (1) by heat fusion. Thereby, the bonding operation is easy, and since no adhesive is used, the adhesive does not mix into the ink. Therefore, it is possible to prevent the ink from being deteriorated due to the adhesive mixed into the ink. Further, the sealing material (1)
7) can be easily peeled off from the outer surface of the tank bottom wall (1).

[0014]

Next, examples (embodiments) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

FIG. 1 is an explanatory view of an ink tank according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a black ink tank among the ink tanks of the embodiment.
FIG. 2 is a sectional view taken along line II-II. FIG. 3 is an explanatory view of a color ink ink tank among the ink tanks of the embodiment.
FIG. 3B is a sectional view taken along the line IIIA-IIIA of FIG. 1, and FIG.
FIG. 3 is a diagram showing a state in which an ink supply hole is not sealed with a sealing material when viewed from an arrow IIIB of A. FIG. 4 is an enlarged explanatory view of an ink supply hole of the ink tank of the embodiment.
FIG. 5 is a diagram illustrating a state in which the ink supply holes of the ink tank according to the embodiment are sealed with a sealing material. FIG.
FIG. 3 is an enlarged explanatory view of a main part showing a state where the ink tank of the embodiment is mounted on a recording head. FIG. 7 is an overall explanatory diagram of a recording head to which the ink tank of the embodiment is mounted.
FIG. 8 is an overall explanatory diagram showing a state in which the ink tank of the embodiment is mounted on a recording head. FIG. 9 is an operation explanatory view showing a state in which the sealing material for sealing the ink supply holes of the ink tank of the embodiment is peeled off.

1 and 2, the ink tank Tk for black ink includes a bottom wall 1, a side wall 2, and a top wall 3 which closes the upper end of the side wall 2 and has a rib protruding inward. Inside the side wall 2, a partition wall 2a that partitions upper and lower spaces and is inclined toward the center is integrally formed, and a communication hole 4 is formed at the center thereof.
The side wall 2, the bottom wall 1 and the top wall 3 are fused to each other by, for example, vibration fusion or ultrasonic fusion. An ink holder 6 made of a material such as felt for holding the ink to be filled is accommodated in the space above the partition 2a. The top wall 3 has a top wall communication hole 7 communicating with the atmosphere.
Is provided. An ink outflow prevention member 8 for preventing ink from flowing out from the top wall communication hole 7 is arranged on an upper end surface of the ink holding body 6 connected to the top wall communication hole 7. A plurality of ribs are formed on the ink outflow prevention member 8 on the side opposite to the ink holding body 6 side, and an air communication path is formed between the ribs on the top wall 3. Then, a small amount of outside air flows through the communication hole 8 of the ink loss prevention member 8.
The ink flows into the space in which the ink holding member 6 is arranged via a and the air communication passage. The side wall 2 is provided with a protrusion 2b for preventing erroneous insertion.

A first meniscus forming member 9 is disposed in the upper opening of the communication hole 4. The first meniscus forming member 9 is formed of a mesh filter, and has a function of forming and holding an ink meniscus (ink film) and holding the downstream pressure at a negative pressure with respect to the atmospheric pressure. The first
Below the meniscus forming member 9, a core 12 supported by a core supporting member 11 is arranged. The core member 12 is formed of a member in which resin fibers are solidified. When ink is depleted on the upstream side of the first meniscus forming member 9, the first meniscus forming member 9 is wetted by capillary action from the downstream side to wet the first meniscus forming member 9. It is a member that sucks and supplies ink.
The lower end of the core member 12 is in contact with an ink supply member 13 supported on the upper surface of the bottom wall 1. An ink supply hole 14 is formed in the bottom wall 1, and a second meniscus forming member 16 that is in contact with the lower surface of the ink supply member 13 is disposed at an upper end thereof. The ink supply member 13 is formed of a member such as a sponge that easily holds ink, and does not destroy the meniscus of the second meniscus forming member 16 even when the remaining amount of ink is small or the posture of the ink tank is changed. To supply ink. In addition, the second
The meniscus forming member 16 has a function of preventing ink from leaking from the ink supply hole 14 in a normal state (a state where environmental fluctuation and impact are not applied).

4 and 5, a concave portion 18 is formed on the outer peripheral end face side of the opening of the ink supply hole 14 formed in the bottom wall 1. As shown in FIG. The recess 18 is formed so as to be recessed from the bottom wall 1, and the amount of the recess may be small. In this embodiment, t = 0.5 mm. The concave portion 18 has a concave bottom surface 18a at a position corresponding to a bottom surface of the concave portion, and has a concave side surface 18b at an outer peripheral edge thereof. The recess 1
It is necessary that the seal member 17 that is adhered to the seal 8 and seals the ink supply hole 14 be formed of a member that can be easily peeled off by the user. In this embodiment, as the sealing material 17, a heat sealing tape material is used in which polyethylene is disposed on the bonding surface side as an adhesive and polyethylene terephthalate is attached on the outside thereof. The sealing material 17 is provided in the ink supply hole 1.
4 has an annular inner adhesive region 19 corresponding to the outer peripheral edge of the ink supply hole 14, a non-adhesive region 21 on the outer periphery of the inner adhesive region 19, and an outer adhesive region 22 on the outer periphery. The inner bonding area 19 and the outer bonding area 22 are formed by the outer peripheral edge of the ink supply hole 14 and the recess 18.
Is thermally fused to the outer periphery. One end of the heat-sealed sealing material 17 protrudes from the longitudinal direction of the bottom wall 1 of the ink tank to make it easy for a user to peel off the ink tank when the ink tank is mounted on the recording head.

In FIGS. 1 and 3, the ink tanks TI for color ink are Y (yellow), M (magenta),
(Cyan) ink tanks Ty, Tm, Tc. Each of the ink tanks Ty, Tm, T
In c, components having the same functions as those of the black ink tank Tk are denoted by the same reference numerals, and detailed description thereof will be omitted. In FIG. 3B, the ink supply holes 14 of the ink tanks Ty, Tm, Tc are formed in a zigzag shape in the longitudinal direction of the ink tank TI. As shown in FIG. 3A, the ink supply holes 14 are integrally sealed from the outer end face side of the bottom wall 1 by a sealing material 17.

Each of the ink supply holes 1 of the color ink tank TI having the ink tanks Ty, Tm, Tc.
The configuration of the lower surface 4 is the same as that of the black ink tank Tk. Further, the method of bonding the ink supply holes 14 with one sealing material 17 is the same as that of the black ink tank Tk. 6, 7 and 8, the recording head H to which the ink tanks Tk and TI are mounted has a housing 23. The housing 23
Has a black ink tank mounting portion 24 at the left end and a color ink tank mounting portion 26 at its right end. The ink flow path forming members 27, 2 are provided on the bottom surface of the housing 23 below the mounting portions 24, 26.
7 'is arranged. The ink flow path forming member 27,
Grooves 27a, 27a 'through which ink flows are formed on the upper surface of 27', and ink communication holes 28, 28 'are formed on the left end side of the grooves 27a, 27a'.

Tank mounting members 28, 28 'are arranged on the upper end surfaces of the ink flow path forming members 27, 27'. One and three ink inflow passage forming cylindrical portions 30 are formed on the tank mounting members 28 and 28 ', respectively.
Each of the ink inflow passage forming cylindrical portions 30 is formed at a position corresponding to each of the ink supply holes 14 of the ink tanks Tk and TI to be mounted.
a is formed. The cylindrical portion 3 for forming the ink inflow path
A disc-shaped filter 31 is arranged at the upper end of the zero.
A cylindrical elastic member 32 is disposed around the cylindrical portion 30 for forming the ink inflow passage. At the upper end of the cylindrical elastic member 32, when the ink tanks Tk and TI are mounted on the recording head H, the concave bottoms 18a of the concave portions 18 (see FIG. 6) formed in the ink tanks Tk and TI are formed. For the close contact, as the cylindrical elastic member 32, a member having elasticity, such as rubber, which bends easily is used. An ink inlet 32 a is formed at the center of the cylindrical elastic member 32, and receives ink from the ink supply hole 14.

(Operation of the Embodiment) The sealing material 17 adhered to the bottom wall 1 of the ink tank Tk is
When storing and transporting the ink tank alone,
Ink leakage is prevented even when the ink tank is subjected to environmental changes or impact. Further, since the inner bonding area 19 of the sealing material 17 is bonded to the vicinity of the outer peripheral edge of the ink supply hole 14, when an external force is applied, it leaks from the second meniscus forming member 16 and enters the ink supply hole 14. The amount of accumulated ink I can be small. In FIG.
In order to mount the ink tank Tk on the recording head H, the user peels off the sealing material 17 from the bottom wall 1 of the ink tank Tk. At this time, one side of the outer region 22 is first peeled, and then one side of the inner region 19 is peeled toward the other side.
When the sealing material 17 in the inner bonding area 19 is peeled off, the ink I attached to the sealing material 17 forms an ink bridge in a wedge-shaped space formed between the sealing material 17 and the concave bottom surface 18a of the concave portion 18. . The ink bridge, as the user peels off the sealing material 17,
Move in the peeling direction.

However, when the ink reaches the space for cutting ink surrounded by the concave bottom surface 18a and the concave side surface 18b of the concave portion 18, the ink I separates from the sealing material 17, and no ink bridge is formed. Further, when the sealing material 17 is peeled off from the inner bonding region 19, the other side of the outer bonding region 22 is in a bonded state.
The force acting on the ink bridge when the ink bridge breaks, which occurs when pulling, is reduced. By reducing the adhesive strength of the inner adhesive area 19, the force acting on the ink bridge when the ink bridge breaks can be further reduced. As described above, when the force acting on the ink bridge when the ink bridge breaks becomes small, the amount of ink scattered when the ink bridge breaks can be reduced. When the other side of the outer bonding region 22 is peeled off after the ink bridge is cut, since the ink bridge is not formed in the sealing material 17, the sealing material 17 is pulled to pull the outer bonding region 22 Even when peeled off, the ink does not scatter and does not stain the user or peripheral devices.

The ink tanks Tk and TI from which the sealing material 17 has been removed in this manner are mounted on the recording head H. At this time, the upper portion of the cylindrical elastic member 32 is in close contact with the concave bottom surface 18a of the concave portion 18 formed on the bottom wall of the ink tanks Tk and TI, and the ink flowing from the ink supply hole 14 into the ink inflow hole 32a is moved. Do not leak. In order to maintain the adhesion so that the ink does not leak, the polyethylene as the adhesive of the sealing material 17 does not remain at the position where the upper portion of the cylindrical elastic member 32 abuts on the concave bottom surface 18a of the concave portion 18. preferable. In the present embodiment, the sealing material 1 is located at a position where the upper part of the cylindrical elastic member 32 contacts, so that the polyethylene as the adhesive does not remain.
Even if the inner bonding area of 7 is weakly bonded, almost no adhesive remains in the inner bonding area because the outer bonding area can withstand the impact of transportation or the like. The ink inlet 3
The ink that has flowed into 2a flows into the ink inflow path 30a and the ink communication holes 28 and 28 'via the filter 31, and is sent to the ink ejection nozzle.

As described above, when peeling off the adhered sealing material 17, the ink bridge formed by the ink leaking into the ink supply hole 14 is formed by the ink tanks Tk and TI.
Is cut by the concave portion 18 formed in the bottom wall 1 of the printer, so that the user is not scattered by the ink. Also, the ink tank T
When the ink in the ink tanks Tk and TI is used up and the ink tanks Tk and TI are removed from the recording head for replacement, the ink attached near the opening of the ink supply hole 14 is removed from the ink tanks Tk and TI. It may flow over the entire bottom wall. However, since the ink accumulates in the concave portion 18, the bottom wall 1
The ink does not flow over the entire surface, and the user needs to replace the ink tank T for replacement.
When removing k and TI from the recording head, the ink and the like do not stain hands and clothes.

(Modifications) Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, but falls within the scope of the present invention described in the appended claims. Thus, various small design changes can be made. next,
The modification of this invention is illustrated. (H01) Although the ink tank for color ink of this embodiment is divided in the short direction for each color, it can be divided in the long direction. (H02) Although the ink supply holes of the color ink ink tank of this embodiment are formed in a zigzag shape on the bottom wall, they may be formed in a line.

[0027]

According to the present invention, the following effects can be obtained. (E01) It is possible to prevent the ink from scattering when the sealing material is peeled off from the ink supply holes.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an ink tank according to an embodiment of the present invention.

FIG. 2 is a sectional view of the ink tank for black ink among the ink tanks of the embodiment, and is a sectional view taken along the line II-II of FIG.

FIG. 3 is an explanatory view of a color ink ink tank among the ink tanks of the embodiment, and FIG.
FIG. 3B is a sectional view taken along the line IIIA-IIIA, and FIG.
FIG. 4 is a diagram illustrating a state in which the ink supply holes are not sealed by a seal material when viewed from above.

FIG. 4 is an enlarged explanatory view of an ink supply hole of the ink tank according to the embodiment.

FIG. 5 is a diagram illustrating a state in which an ink supply hole of the ink tank according to the embodiment is sealed with a sealing material.

FIG. 6 is an enlarged explanatory view of a main part showing a state where the ink tank of the embodiment is mounted on a recording head.

FIG. 7 is an overall explanatory diagram of a recording head to which the ink tank of the embodiment is mounted.

FIG. 8 is an overall explanatory diagram showing a state in which the ink tank of the embodiment is mounted on a recording head.

FIG. 9 is an operation explanatory view showing a state in which a seal member sealing an ink supply hole of the ink tank of the embodiment is peeled off.

[Explanation of symbols]

(Tk, TI) ... tank body, 1 ... bottom wall, 14 ... ink supply hole, 17 ... sealing material, 18 ... concave portion, 19 ... inner adhesive area, 21 ... non-adhesive area, 22 ... outer adhesive area,

Claims (3)

[Claims] An ink tank for an ink jet recording apparatus, characterized by having the following requirements: (A01) an ink tank for supplying an ink filled therein to the ink jet recording head when connected to the ink jet recording head; A tank body having an ink supply hole formed in the tank bottom wall, (A
02) a sealing material formed of a flexible sheet that is adhered to the outer surface of the tank bottom wall and seals the ink supply holes to prevent leakage of the ink filled in the tank body; (A03) the ink supply An annular inner adhesive region adjacent to an outer peripheral edge of the hole, a non-adhesive region provided outside the inner adhesive region, and an outer adhesive region provided further outside the non-adhesive region; (A04) an outer bonding area of the sealing material is bonded to an outer surface of the tank bottom wall opposite to the non-bonding area of the sealing material; The tank main body, wherein a concave portion that is recessed from the outer surface of the tank bottom wall is provided, and a space for cutting ink is formed between the concave portion and the non-adhesive region of the sealant. 2. The ink tank according to claim 1, further comprising the following requirements: (A05) an outer surface of the tank bottom wall which faces the inner adhesive area and the non-adhesive area of the seal material, The tank main body, wherein the tank body is formed so as to be recessed from an outer surface of the tank bottom wall facing an outer bonding area of a sealing material, and a step is formed at an outer peripheral edge of the recessed portion. 3. The ink tank according to claim 1, wherein said ink tank has the following requirements: (A06) said inner bonding area and said outer bonding area are bonded to the outer surface of the tank bottom wall by heat fusion. Said sealing material.