Liquid container for ink jet recording apparatus with structure to promote gas-liquid exchange

A liquid container includes a negative pressure producing member accommodating chamber accommodating a negative pressure producing member for absorbing and retaining the liquid, and a liquid containing chamber for containing the liquid. The liquid containing chamber is in fluid communication with the negative pressure producing member accommodating chamber through a communicating portion, and is substantially sealed except for the communicating portion. A partition wall partitions the liquid container into the negative pressure producing member accommodating chamber and the liquid containing chamber except for the communicating portion. The negative pressure producing member is provided with a recess at a position corresponding to the communicating portion, wherein the recess forms a space and a ceiling portion of the space provided functions as a gas introduction surface which is substantially horizontal when the liquid container is in an in-use orientation.

FIELD OF THE INVENTION AND RELATED ART

The present invention relates to an ink cartridge or a liquid container for accommodating ink to be supplied to the ink jet recording head, and a manufacturing method therefor.

Generally, the ink cartridge or liquid container in the field of ink jet recording, is provided with a structure for adjusting an ink retaining force for the ink accommodated in the ink cartridge in order to satisfactorily supply the ink to a recording head for ejecting the ink. The retaining force is called “negative pressure” since it is effective to maintain a negative pressure at the ink ejection portion of the recording head with respect to the ambient pressure.

In U.S. Pat. No. 5,509,140 which has been assigned to the Assignee of the present application, for example, a proposal has been made as to an ink cartridge having a liquid containing chamber, wherein an ink accommodation capacity per unit volume of the ink cartridge is increased, while using an ink negative pressure producing member, and wherein the ink supply is stabilized.

FIG. 18, (a) shows a schematic sectional view of an ink cartridge of such a structure. The inside of the ink cartridge10is separated into two spaces by a partition wall having a communication port (communicating portion)40. One of the two spaces is a liquid containing chamber36which is hermetically sealed except for the communication port40of the partition wall38and which accommodate the ink25directly (substantially without ink retaining foam or the like), and the other space is a negative pressure producing member accommodating chamber34for accommodating the negative pressure producing member32. A wall surface defining the negative pressure producing member accommodating chamber34is provided with an air vent (air vent)12for introducing the ambient air into the ink cartridge10in accordance with consumption of the ink, and a supply port14for supplying the ink out to a recording head portion (unshown). InFIG. 18, the region in which the negative pressure producing member32retain the ink is indicated by hatching lines. The ink accommodated in the space is indicated by dots.

With this structure, the ink in the negative pressure producing member32is consumed by an unshown recording head, and when the ink interface61shown inFIG. 18, (a) is reached, the air is introduced from the air vent12into the negative pressure producing member accommodating chamber34with the consumption of the ink, and the ink enters the liquid containing chamber36through the communication port40formed in the partition wall38. In place of the air, the ink is supplied into the negative pressure producing member32in the negative pressure producing member accommodating chamber34through the communication port40of the partition wall from the liquid containing chamber36(gas-liquid exchanging operation). Therefore, even if the ink is consumed by the recording head, the ink is supplied into the negative pressure producing member32correspondingly to the consumption of the ink, so that negative pressure producing member32retains a constant amount of the ink (that is, the position of the interface61is maintained, by which the negative pressure relative to the recording head is kept substantially at a constant level, thus stabilizing the ink supply to the recording head. Such a downsized ink cartridge providing a high use efficiency has been commercialized by the Assignee of the present application and is still practically used.

In the example ofFIG. 18, (a), air introducing groove or grooves50are provided adjacent the communicating portion for fluid communication between the negative pressure producing member accommodating chamber and the ink reservoir chamber as a structure for promoting the ambient air introduction, and adjacent the neighborhood of the air vent, there is provided a space (buffer chamber)44which is free of negative pressure producing member32, by ribs42.

On the other hand, in the U.S. Pat. No. 6,137,512 which has been assigned to the Assignee of the present application, a proposal has been made as to an ink cartridge using fibers of olefin resin material having a thermoplastic property as the negative pressure producing member in the above-described ink cartridge. The ink cartridge is excellent in keeping the stability of the ink in storage, and is also excellent in the recycling property since the ink cartridge casing and the fibrous material are made of similar kind materials.

SUMMARY OF THE INVENTION

Recently, the recording speed of the ink jet recording apparatus is increased, and therefore, the ink supply amount per unit time from the ink cartridge into the ink jet head is increased. When the ink continues to be supplied at a high rate with the above-described structure of the ink cartridge, the supply of the air into the liquid containing chamber does not catch up the high rate ink supply with the result that liquid surface (interface) in the absorbing material lowers, and the ink supply does not meet the requirement to keep the ink level, in some cases. If this occurs, the ink supply may become disconnected with some ink remaining in the liquid containing chamber (this will be called “ink disconnection”).

Referring toFIG. 18, the description will be made as to a mechanism of the ink disconnection in the conventional ink cartridge.FIG. 18, (a) illustrates gas-liquid exchange in an ink container used with a conventional ink jet recording apparatus when the ink supply amount to the ink jet recording head is relatively small;FIG. 18, (b) illustrates the same when the ink supply amount to the ink jet recording head is increased;FIG. 18, (c) illustrates the same when the ink supply amount to the ink jet recording head continues to increase.

In the case ofFIG. 18, (a), the ink supply amount from the ink container to the ink jet recording head (unshown) is relatively small, so that amount of the ink discharged from the liquid containing chamber36matches the amount of the air introduced into the liquid containing chamber36. Namely, the gas-liquid interface61in the negative pressure producing member32is maintained substantially at a constant position which is adjacent a point51where the upper end of the air introducing groove50contacts the negative pressure producing member32.

However, the case that ink supply amount for ink jet recording head (unshown) is increased will be considered. The path of the air which is subjected to the gas-liquid exchange is a part or entirety of the region of a line at which the upper end of the air introducing groove50(a line extending in the widthwise direction in the sectional view ofFIG. 18, (a)) and the negative pressure producing member32(indicated by point51in the sectional view), and therefore, the introduction of the air into the ink accommodating chamber is not enough to meet the increased ink supply amount or rate. Therefore, the ink retained in the negative pressure producing member is supplied out in addition to such an amount of the ink supplied out of the ink accommodating chamber as meets the amount of the air introduced through the path of the air (operation A), and the gas-liquid interface61in the negative pressure producing member32lowers as shown inFIG. 18, (b).

With the reduction of the gas-liquid interface61, the area of the gas introduction surface33of the negative pressure producing member32which is contacted to the air introducing groove50expands, so that wider air path is provided, thus tending to introduce the air at a higher rate into the liquid containing chamber36(operation B).

These operation An and operation B are combined, and the gas-liquid interface61lowers to expand the area of the surface33for gas introduction until the introduction of such an amount of the air into the liquid containing chamber as meets the ink supply amount. Finally, the lowering gas-liquid interface is stabilized at a position when the ink discharge rate and the ink supply rate through the ink supply port are balanced, by which the increased amount of the ink can be supplied continuously.

However, in such a case, the negative pressure (absolute value) increases due to the lowering of the gas-liquid interface61with the result that stabilized ink supply with the proper negative pressure to the ink jet recording head is not carried out, and therefore, the printing may be disturbed. In addition, if the ink supply amount increases to such an extent as 3 times, 5 times or like the normal in supply rate, as is not expected conventionally, the above-described lowering of the gas-liquid interface61is not enough to each of the balance point, and the gas-liquid interface61in the negative pressure producing member32continues to lower beyond the effect of expansion of the area of the gas introduction surface33, with the result that gas-liquid interface61lowers down to the ink supply port14, thus causing the ink disconnection.

In the conventional ink cartridge, as described hereinbefore, the gas introduction surface is substantially perpendicular to the gas-liquid interface in the negative pressure producing member. More particularly, the gas introduction surface opens in the direction of capillary force gradient (substantially vertical direction) of the negative pressure producing member32, and therefore, the gas-liquid exchange effect corresponding to the opening area (increase of the rate of the air introduction).

Accordingly, it is a principal object of the present invention to provide an ink cartridge and an ink jet recording apparatus wherein the ink supply is stabilized so as not to cause ink disconnection or printing disturbance or the like in ink jet recording at high speed.

According to an aspect of the present invention, the position of the gas introducing portion (gas introduction surface) for gas-liquid exchanging operation is substantially horizontal in the attitude of the container in use, by which when the gas-liquid interface in the negative pressure producing member reaches the gas introduction surface as a result of ink consumption through the ink supply port, the area of the air path into the ink accommodating chamber is drastically increases, so that amount of the air meeting the amount over the ink discharge can be introduced into the ink accommodating chamber without delay. Therefore, the stabilized ink supply to the ink jet recording head is accomplished without occurrence of ink disconnection as in the conventional ink jet recording. By this, a highly reliable ink cartridge and ink jet recording apparatus suitable for high speed operation can be provided.

According to another aspect of the present invention, there is provided a liquid container comprising a negative pressure producing member accommodating chamber accommodating a negative pressure producing member for absorbing and retaining the liquid, said negative pressure producing member accommodating chamber having a supply port for supplying the liquid to liquid an ejection recording head and an air vent for fluid communication with ambient air; a liquid containing chamber for containing the liquid, said liquid containing chamber being in fluid communication with said negative pressure producing member accommodating chamber through said communicating portion and being substantially sealed except for said communicating portion; and a partition wall for partitioning said liquid container into said negative pressure producing member accommodating chamber and said liquid containing chamber except for said communicating portion; wherein said negative pressure producing member is provided with a recess at a position corresponding to said communicating portion; wherein a ceiling portion of a space provided by said recess functions as a gas introduction surface which are substantially horizontal when said liquid container takes a position in use.

According to a further aspect of the present invention, there is provided a liquid container, wherein said negative pressure producing member includes a first and second negative pressure producing members which are press-contacted to each other; a capillary force of said first negative pressure producing member is higher than a capillary force of said second negative pressure producing member; an interface of a press-contact portion between said first and second negative pressure producing members crosses with said partition wall; said first negative pressure producing member is in fluid communication with said communicating portion and with said supply port; and the interface of the press-contact portion between said first and second negative pressure producing members is disposed above said gas introduction surface.

According to a further aspect of the present invention, there is provided a liquid container, wherein the ink is retained over an entire area of the interface of the press-contact portion between the first and the second negative pressure producing member irrespective of an attitude taken by said liquid container.

According to a further aspect of the present invention, there is provided a liquid container, further comprising a structural member provided in a space formed by said recess and contacted to said negative pressure producing member, said structural member being disposed on an extension of a contact plane between a surface of an inner wall constituting said negative pressure producing member accommodating chamber and a surface of said negative pressure producing member.

According to a further aspect of the present invention, there is provided a liquid container, further comprising a projection provided in a space formed by said recess and disposed on an extension of a contact plane between a surface of an inner wall constituting said negative pressure producing member accommodating chamber and a surface of said negative pressure producing member, said projection being effective to block a direct fluid communication between a surface of said negative pressure producing member directly contacting the liquid and said contact surface.

According to a further aspect of the present invention, there is provided a liquid container, further comprising a structural member disposed on an extension of an apex line where inner walls constituting said negative pressure producing member accommodating chamber cross with each other, said structural member has a dimension in a direction crossing with said apex line.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the accompanying drawings, the description will be made as to the preferred embodiments of the present invention.

In the following descriptions, the liquid used with the liquid supply method, the liquid supplying system and the liquid container according to the present invention is ink, but the present invention is applicable with the liquid other than ink. For example, in the field of the ink jet recording, the liquid may be processing liquid.

In each of the sectional views referred to in the following descriptions, such regions in the negative pressure producing member as retain the ink are indicated by hatching lines, and the ink accommodated in a space (directly) is indicated by dots.

All of the sectional views show the state in which the ink has been consumed from the negative pressure producing member and the ink is consumed from the liquid containing chamber (gas-liquid exchange occurs).

The reference numerals in the Figures are fundamentally common.

First Embodiment

FIG. 1is a schematic sectional view of an ink cartridge according to the first embodiment of the present invention, wherein (a) shows a state in which the ink consumption amount per unit time (ink consumption rate) is relatively small, and (b) shows a state in which the ink consumption amount per unit time is relatively large.

The description will be made as to the structure of the ink cartridge (liquid container).

InFIG. 1, (a), the liquid container (ink cartridge)100is partitioned by a partition138into a negative pressure producing member accommodating chamber134which accommodates a negative pressure producing member132and which is in fluid communication with the ambient air through an air vent112provided at an upper portion thereof and which is in40combination with an ink supply port114at the lower portion thereof, and a liquid containing chamber136which accommodates the liquid (ink125) in which is substantial hermetically sealed. The negative pressure producing member accommodating chamber134and liquid containing chamber136are in fluid communication with each other only through the communicating portion140formed in the partition138adjacent the bottom portion of the ink cartridge100. The inner upper wall of the ink cartridge100defining the negative pressure producing member accommodating chamber134is provided with a plurality of ribs142extended inwardly of the container, ribs142being in contact with the negative pressure producing member132which is accommodated in the negative pressure producing member accommodating chamber134in a compressed state. By the provision of the ribs142, an air buffer chamber144is formed between the upper wall and the upper surface of the negative pressure producing member.

In an ink supply tube having the supply port114, there is provided a press-contact member146which has a capillary force higher than that of the negative pressure producing member and which has a physical strength which is higher than that of the negative pressure producing member. The press-contact member146is press-contacted to the negative pressure producing member132.

The gas introduction surface will be described.

A part of the negative pressure producing member132is provided with a recess which has been formed by cutting a part of the negative pressure producing member into a V-shape. By doing so, a gas introduction surface200is substantially horizontal. Therefore, when the liquid surface height of the ink125in the liquid containing chamber is higher than the level of the gas introduction surface200, the ink125in the liquid containing chamber directly contacts the gas introduction surface200.

When the liquid surface height of the ink125in the liquid containing chamber becomes lower than the gas introduction surface200, the ink125in the liquid containing chamber reaches the gas introduction surface200through the negative pressure producing member132.

The description will be made as to the material of the negative pressure producing member.

The material of the negative pressure producing member may be porous material such as polyurethane foam, fibrous material or the like and another material capable of producing capillary force. The use of fibrous materials is advantageous in that latitude of material selection is wider than the latitude in the porous material porous material or the like such as urethane, and therefore, the selection can be made in consideration of the ink hydrophilic property. In addition, the material of the fibers may be thermoplastic resin material which are the same as or similar to the material of the main assembly of the ink cartridge. In this case, the ink cartridge is of high recycling property. In addition, the fiber may comprise a core-sleeve structure with which in the crossing parts of the fibers can be assuredly fixed, so that the ink retention force (capillary force) is stabilized, and the ink holding particularly property, and therefore, the negative pressure property are stabilized. In this embodiment, the fiber of the fibrous material of the negative pressure producing member comprises a core portion of polypropylene and a sheath portion of olefin resin material of polyethylene, and the fibers re provided by heat molding. Then, the difference in the melting point between the polyethylene and the polypropylene is effectively used by setting the temperature during the heat molding at a level between the melting point of the material having a low melting point and the melting point of the material having a high melting point (for example, setting it at the level higher than the melting point of the polyethylene and lower than the melting point of the polypropylene). By doing so, the fibrous material having the low melting point can be used as adhesive material, so that crossing portions between the fibers can be fixed by melting the polyethylene having the relatively low melting point. Therefore, the ink cartridge of the present invention can be easily manufactured.

Confounded fibrous material effective to produce a predetermined capillary force, particularly, the confounded fibrous material comprising as a base material of polyolefin resin material represented by the polyethylene or polypropylene, exhibits a high absorption speed as compared with a foam member effective to produce the same capillary force, and therefore, even if the ink consumption occurs such that ink liquid surface height in the liquid containing chamber136is lower than the gas introduction surface200, the ink quickly reaches the gas introduction surface200through the negative pressure producing member132. By this, the meniscus in the gas introduction surface200which has been broken (the state in which the gas introduction path for the gas-liquid exchange is open) is quickly regenerated (the gas introduction path for the gas-liquid exchange is closed).

In the embodiment, this is provided by cutting the negative pressure producing member to form recess. Doing so is particularly effective in the case of the negative pressure producing member of fibrous material. However, the present invention is not limited to such a recess. For example, when the fibrous material is subjected to the heat molding, a mold corresponding to the recess is used, and heat molding using it can form the recess without cutting the negative pressure producing member after molding.

The description will be made as to gas-liquid exchanging operation.

The negative pressure producing member (negative pressure producing member)132accommodated in the negative pressure producing member accommodating chamber134can be deemed to have a great number of capillary tubes, which function to produce the negative pressure by the meniscus forces. Normally, a sufficient amount of ink is retained in the negative pressure producing member immediately after start of use of the liquid container, and therefore, the potential heads of the respective capillary tubes are sufficiently high.

With the consumption of the ink through the ink supply port114, the pressure at the bottom portion of the negative pressure producing member accommodating chamber134lowers, and the potential heads of the capillary tubes also lowers. Namely, the gas-liquid interface161of the negative pressure producing member132lowers in accordance with the consumption of the ink.

When the ink is further consumed, the gas-liquid interface161lowers to such an extent shown inFIG. 1, (a). With even further consumption of the ink, the meniscus of the gas introduction surface200provided in the negative pressure producing member is broken, and the ambient air is introduced into the liquid containing chamber136while the gas-liquid interface161hardly lowers from the position shown inFIG. 1, (a).

When the ambient air is introduced into the liquid containing chamber136, the pressure in the liquid containing chamber136becomes higher than the pressure at the bottom portion of the negative pressure producing member accommodating chamber, and the ink is supplied into the negative pressure producing member accommodating chamber134from the liquid containing chamber136so as to cancel the pressure difference.

The gas introduction surface is substantially horizontal in this embodiment, and therefore, the gas introduction surface is substantially parallel with the gas-liquid interface, so that meniscus force in the ambient air introduction surface200is substantially constant. So, in the case that ink consumption amount per unit time further increases, the meniscus are broken one after another as shown inFIG. 1, (b), and a wide gas introduction surface200are drastically provided. Namely, numerous air introduction paths are assuredly provided, so that large amount of the air can be speedily introduced into the ink accommodating chamber to meet the discharge of the ink without lowering of the gas-liquid interface in the negative pressure producing member. When the ink consumption amount through the ink supply port114decreases or the ink consumption is interrupted, the gas-liquid interface rises, and the meniscus of the gas introduction surface is regenerated, thus stopping the gas-liquid exchanging operation.

Therefore, the gas-liquid exchanging operation is possible without lowering of the gas-liquid interface from the beginning of the gas-liquid exchanging operation, as described hereinbefore, the ink can be supplied into the ink jet recording head stably without the conventional ink disconnection. By this, a highly reliable ink cartridge and ink jet recording apparatus suitable for high speed operation can be provided.

The description will be made as to flow resistance during ink supply to the ink jet recording head.

FIG. 2is a graph showing flow resistance during ink supply into the ink jet recording head, wherein the ordinate is a dynamic negative pressure (total negative pressure) including flow resistance during the ink supply, and the abscissa is a total consumption amount of the ink from the ink cartridge. There are shown the total negative pressure in a conventional ink cartridge, the total negative pressure of the ink cartridge of this embodiment from the beginning to the end of the ink consumption, the total negative pressure when the gas-liquid exchange in the conventional ink cartridge are assumed to be enough, and the changes in the negative static pressure in the conventional ink cartridge and in the embodiment of the present invention. The ink supply flow rate per unit time is common for all cases.

The total negative pressure in the conventional ink cartridge increases with the consumption of the ink. This is because the gas-liquid exchange is not enough to meet the ink supply flow rate per unit time.

The graph of the predicted negative pressure is the negative pressure on the assumption that gas-liquid exchange is enough to meet the ink consumption in the conventional ink cartridge. When this is compared with the total negative pressure in the ink cartridge of this embodiment, the ink cartridge of this embodiment can supply the ink with the negative pressure which is lower than in the conventional ink cartridge.

This is because, the ink cartridge of this embodiment is capable of drastically expand the gas introduction surface as described hereinbefore, so that large amount of the air can be quickly supplied into the ink accommodating chamber to meet the ink discharge without lowering the gas-liquid interface in the negative pressure producing member. In other words, the conventional ink cartridge requires longer time to provide the gas introduction area necessary to meet the gas-liquid exchange than in the ink cartridge of this embodiment. In the ink cartridge of this embodiment, the stabilized gas-liquid exchanging operation starts before the timing at which the conventional ink cartridge stabilizes the gas-liquid exchange by the expansion of the area of the gas introduction. Therefore, in the ink cartridge of this embodiment, the flow resistance is stabilized more quickly (with less ink consumption amount) than in the conventional ink cartridge, and therefore, the stabilized ink supply is reached with a lower negative pressure.

The description will be made as to the case in which the liquid surface in the ink accommodating chamber lowers beyond the gas introduction surface.

When the ink consumption stops with the state in which the liquid surface in the ink accommodating chamber136is lower than the gas introduction surface200, the ink is supplied from the liquid containing chamber136into the negative pressure producing member accommodating chamber134so as to cancel the difference between the pressure in the liquid containing chamber136and the pressure at the bottom portion of the negative pressure producing member accommodating chamber.

The ink in the ink accommodating chamber136supplied from the negative pressure producing member accommodating chamber134absorbs the ink up by the capillary force of the negative pressure producing member, and therefore, the broken meniscus is regenerated, thus stopping the air introduction into the ink accommodating chamber. Namely, the ink discharge from the ink accommodating chamber is stopped, and therefore, no pressure is applied to the ink jet recording head by leakage of the ink from the ink cartridge.

Second Embodiment

FIG. 3is a schematic sectional view of a liquid container according to the second embodiment of the present invention, wherein (a) shows a state in which the ink consumption amount per unit time (ink consumption rate) is relatively small, and (b) shows a state in which the ink consumption amount per unit time is relatively large.

The basic structures and operations are similar to those in first embodiment, and therefore, the detailed description of the common parts is omitted for simplicity.

What is different from the first embodiment is in the configuration (recess configuration) S of a cut-away portion of the negative pressure producing member for providing the gas introduction surface200. In the first embodiment, the cut-away portion has a V-shaped cross-section, and in this embodiment, the cut-away portion has a rectangular cross-section as shown inFIG. 3.

This embodiment is effective to provide an additional advantage. The length from the portion210where the negative pressure producing member contacts the ink to the ink supply port114is shorter than in the first embodiment. Therefore, the flow resistance during the ink supply to the ink jet recording head is shorter than in the first embodiment, as is preferable.

Third Embodiment

FIG. 4is a schematic sectional view of a liquid container according to a third embodiment of the present invention, wherein (a) shows an example in which the amount of a cut-away portion is increased to elongate the gas introduction surface in the horizontal direction; (b) is a sectional view taken along X-X and seen in a direction A; (c) is a sectional view of an example in which a problem which may arise in the example ofFIG. 4, (a); (d) a sectional view taken along X-X and seen in a direction A; (e) and (f) are modifications corresponding toFIG. 4, (c).

The basic structures and operations are similar to those in first embodiment, and therefore, the detailed description of the common parts is omitted for simplicity.

What is different from the foregoing embodiments is in that negative pressure producing member is cut away so as to make the gas introduction surface200longer in the horizontal direction inFIG. 4, (a).

With this structure, the negative pressure producing member above the cut-away portion may be pressed down by the ribs142or become slack down (toward the gas introduction surface) due to shock upon falling of the ink cartridge. An example of counter measurements against this problem will be described.

As shown inFIG. 4, (c), a projection is formed on an inner wall of the negative pressure producing member accommodating chamber at a position in the direction of the height matching the depth of the cut-away portion in the direction of height so as to hold the negative pressure producing member at the portion indicated by Y, by which the negative pressure producing member can be retained at the desired position. By doing so, the slacking of the negative pressure producing member or positional deviation can be prevented. Here, as shown inFIG. 4, (d) which is a sectional view taken along a line X-X, the projection is integrally molded with the wall of the ink cartridge. This is not limiting, and the projection may be provided by a separate member extending into the cut-away portion of the negative pressure producing member. In the example ofFIG. 4, (c), the length of the projection at the Y portion is small, but may be the same as the length of the cut-away portion.

With this structure, the portion230where the negative pressure producing member contacts the ink is opposed to the ink supply port114, and therefore, an additional advantageous effect is provided. The length from the portion230where the negative pressure producing member contacts the ink to the ink supply port114is further smaller than in the foregoing embodiment, the flow resistance during ink supply to the ink jet recording head is further small.

(Relation Between Partition Wall and Gas Introduction Surface)

FIG. 5is a schematic sectional view of a liquid container wherein a position of a bottom end portion of a partition wall is higher than the position of the gas introduction surface in the present invention, when (a) illustrates a state in which the amount of the ink consumption per unit time is relatively small, and (b) illustrates a state in which the amount of the ink consumption per unit time is relatively large. The basic structures and operations are similar to the second embodiment, and therefore, the detailed descriptions of the common parts are omitted for simplicity.

With this structure, as shown inFIG. 5, (a), in the case that ink consumption amount per unit time is small, the gas is introduced through the portion240where the negative pressure producing member contacts the ink at the bottom end portion138aof the partition wall138, at the time when the gas-liquid interface161reaches the bottom end portion138aof the partition wall138. In the case that ink consumption amount per unit time is larger, the air path is short as shown inFIG. 5, (b), the gas-liquid interface161lowers to the gas introduction surface200. Thereafter, similarly to the foregoing embodiment, the gas introduction area drastically expands, and the gas-liquid exchange is sufficiently performed with hardly lowering the gas-liquid interface any more.

FIG. 6, (a) is a schematic sectional view of a liquid container of the present invention when the position138aof the bottom end portion of the partition wall138is lower than the gas introduction surface200. With this structure, when the air introduced through the gas introduction surface200reaches the bottom end portion138aof the partition wall138, the air is introduced into the liquid containing chamber136. The advantageous effects of the foregoing embodiments are substantially provided. However, if the position138aof the bottom end portion is so low that opening of the communicating portion140is too narrow to permit smooth passage of the air, the air coming out through the gas introduction surface200may stagnate there to disturb the speedy introduction of the air into the liquid containing chamber136. In view of this, the communicating portion140has a properly large size. When the bottom end portion138ais lower than the gas introduction surface200, the air may be liable to stagnate between the bottom end portion138aand the space formed by the cut-away portion of the negative pressure producing member. Therefore, the structure in which the bottom end portion138aof the partition wall and the gas introduction surface200are near to each other as shown inFIG. 6, (b), is desirable since then the speedy gas-liquid exchange is possible with the stabilized ink supply.

Fourth Embodiment

FIG. 7is a schematic sectional view of a liquid container according to a fourth embodiment of the present invention, wherein (a) illustrates a state in which the amount of the ink consumption per unit time is relatively small, and (b) illustrates a state in which the amount of the ink consumption per unit time is relatively large.

The basic structures and operations are similar to those in first embodiment, and therefore, the detailed description of the common parts is omitted for simplicity.

What is different from the first embodiment is in that negative pressure producing member is divided into two parts.

The negative pressure producing member accommodating chamber134accommodates first and second negative pressure producing members132aand132bwhich are press-contacted to each other. The capillary force of the first negative pressure producing member132ais higher than that of the second negative pressure producing member132b. The interface in the press-contact portion160between the first and the second negative pressure producing members132aand132bextends in the direction crossing with the partition wall138. The first negative pressure producing member132ais in fluid communication with the communicating portion140, and is communicable with the air vent112only through the interface in the press-contact portion160. The second negative pressure producing member132bis communicable with the communicating portion140only through the interface in the press-contact portion160. The gas introduction surface200is disposed at a position below the interface in the press-contact portion160between the two negative pressure producing members.

With this structure, the capillary force of the first negative pressure producing member132ais higher than the capillary force of the second negative pressure producing member132b, and therefore, during the lowering of the gas-liquid interface in the negative pressure producing member with the consumption of the ink, it is assured that ink retained in the first negative pressure producing member132ais consumed only after the ink retained in the second negative pressure producing member132bthereabove is consumed. For this reason, only after the gas-liquid interface becomes once substantially horizontal at the interface in the press-contact portion160between the first negative pressure producing member132aand the second negative pressure producing member132b, the gas-liquid interface lowers to the position of the gas introduction surface200, so that gas-liquid interface upon the beginning of the gas-liquid exchange is more assuredly horizontal, as desired, as indicated by the gas-liquid interface300(broken line) as compared with the foregoing embodiments. In addition, during transportation of the ink cartridge wherein the orientation of the ink cartridge is not controllable, the ink leakage can be avoided, thus improving the reliability. This may be combined with any of the foregoing embodiments.

The ink is filled such that it exists above the recess (gas introduction surface) further to the entirety of the interface between the first negative pressure producing member132aand the second negative pressure producing member132b, and this is desirable. During the transportation process after the manufacturing of the ink reservoir and before the start of the use, the air adjacent the air vent112may enter the ink reservoir chamber136through the negative pressure producing member132aor132b, and correspondingly, the ink may discharge into the air vent portion. By the filling so as to retain the ink at the interface, such a problem can be avoided.

Other Embodiments

In the first, second and third embodiments of the present invention, a gap may occur between surface portion of the inner wall of the negative pressure producing member accommodating chamber and the surface portion of the negative pressure producing member, and the air enters the gap with the result of unintended gas-liquid exchanging operation. The description will be made as to this.

Such a gap results by yielding of a part of negative pressure producing member. This will be called “wall surface path”.

Referring toFIG. 8, the description will be made as to such a gap.

FIG. 8, (a) is a schematic sectional view of the container in which the negative pressure producing member132is accommodated in the negative pressure producing member accommodating chamber. At this time of setting the negative pressure producing member132in the negative pressure producing member accommodating chamber, it is desirable that no gap is formed between the negative pressure producing member132and the inner wall of the negative pressure producing member accommodating chamber, and that is contacted to the inner wall of the negative pressure producing member accommodating chamber in a proper state, from the standpoint of prevention of ink leakage or the like. Therefore, it is desirable that sizes of the negative pressure producing member before it is accommodated in the negative pressure producing member accommodating chamber are larger than the corresponding inner sizes of the negative pressure producing member accommodating chamber.

However, as described hereinbefore, in the case that sizes of the negative pressure producing member are larger than the sizes of the negative pressure producing member accommodating chamber, the negative pressure producing member is subjected to forces tending to compress the negative pressure producing member from the inner wall of the negative pressure producing member accommodating chamber. The compression forces are applied from the negative pressure producing member accommodating chamber on a surface A and a surface B of the negative pressure producing member132as shown inFIG. 8. If the stress caused in the negative pressure producing member132is concentrated at a part (where the configuration of the cross-section of the negative pressure producing member changes drastically), the negative pressure producing member, there occurs a portion where the negative pressure producing member132deforms inwardly at the stress-concentrated position (the deformation is a dimple150bresulting from yielding150a).

The yielding150aleads to production of the above-described wall surface path, with the result that ink existing in the space formed by the cut-away portion of the negative pressure producing member may be easily brought into fluid communication with the ambient air. If this occurs, the ink may leak from the liquid container.

In consideration of such a problem, it is desirable to provide an ink container with which the gas-liquid exchanging operation is stable even when the dimple150bis produced by the yielding150a.

An example of solving the problem will be described.

FIG. 9, (a) is a schematic sectional view of an ink cartridge of the second embodiment wherein the means for solving the problem is incorporated. The negative pressure producing member132of the second embodiment is accommodated in the negative pressure producing member accommodating chamber.FIG. 9, (b) is a substantial perspective view of the negative pressure producing member only, which is used inFIG. 9, (a) and has a dimple150bon the surface of the negative pressure producing member as shown.

A side wall of the projection151which is formed so as to be in close contact with the inner wall of the negative pressure producing member accommodating chamber, is disposed at an end of the gap produced at the dimple150bof the surface of the negative pressure producing member and the inner wall of the negative pressure producing member accommodating chamber corresponding thereto, as shown inFIG. 9, (c). By doing so, the ink existing in such a space is blocked from flowing into the gap, by which the communication between the ambient air and the ink existing in the space can be prevented.

FIG. 9, (d) is a substantial enlarged view illustrating a relation between the gap existing between the surface of the negative pressure producing member and the internal wall surface and the projection151formed close-contacted to the inner wall of the negative pressure producing member accommodating chamber, wherein the projection151formed close-contacted to the inner wall of the negative pressure producing member accommodating chamber is close-contacted to the end of the gap formed between the surface of the negative pressure producing member and the internal wall surface.

In the case that there is a liability of production of the gap by which the ink existing in the space formed by the cut-away portion of the negative pressure producing member becomes in fluid communication with the ambient air with the result of unintended gas-liquid exchanging operation, the projection formed close-contacted to the inner wall of the negative pressure producing member accommodating chamber is close-contacted to the end of the gap produced on the surface of the negative pressure producing member so that communication between the ambient air and the ink existing in the space formed by the cut-away portion of the negative pressure producing member, occurrence of the wall surface path is prevented. Thus, the ink leakage caused by the gap due to the yielding can be prevented.

FIG. 10is a schematic sectional view of an ink cartridge according to the second embodiment of the present invention wherein the problem is solved, andFIG. 11is a schematic perspective view of the negative pressure producing member only, which is used in the negative pressure producing member accommodating chamber of the ink cartridge ofFIG. 10. This embodiment is different in the position of the dimple150bproduced in the surface of the negative pressure producing member (gap formed with the internal wall surface).

Similarly to the example ofFIG. 9, the end of the gap formed between the internal wall surface and the surface of the negative pressure producing member is sealed by the projection151formed close-contacted to the inner wall of the negative pressure producing member accommodating chamber so as to block the communication between the ambient air and the ink existing in the space formed by the cut-away portion of the negative pressure producing member. By doing so, production of the wall surface path and therefore the ink leakage is prevented.

As described in the foregoing referring toFIGS. 9,10and11, in order to prevent the ink leakage through the air vent of the liquid container as a result of occurrence of unintended gas-liquid exchange (occurrence of the wall surface path) by fluid communication between the air in the negative pressure producing member of the portion above the desired position of the gas-liquid interface and the ink existing in the space at the negative pressure producing member side through the gap formed between the inner wall and the surface of the negative pressure producing member, the end of the gap formed between the internal wall surface and the surface of the negative pressure producing member is sealed by the projection151formed close-contacted to the inner wall of the negative pressure producing member accommodating chamber, by which the introduction of the air through the wall surface path into the ink existing in the space formed by the cut-away portion of the negative pressure producing member.

When the occurrence of the gap leading to the communication between the ink existing in the space at the negative pressure producing member side and the ambient air in the negative pressure producing member above the position of the desired gas-liquid interface and therefore leading to the unintended gas-liquid exchange (surface path), is predicted, the projection151is disposed so as to seal the end of the predicted gap. By doing so, even if the gap is produced, the establishment of the wall surface path can be prevented.

Referring toFIG. 12, an example will be described.

As shown inFIG. 12, (a), the projection151is formed close-contacted to the inner wall of the negative pressure producing member accommodating chamber and is disposed, as shown inFIG. 12, (b) so as to seal the end of the predicted gap produced between the internal wall surface of the negative pressure producing member accommodating chamber and the surface of the negative pressure producing member when the negative pressure producing member132is partly cut away as shown inFIG. 12, (a). By doing so, the production or establishment of the wall surface path due to the dimple150bcan be prevented.

In the case that ink existing in the space at the negative pressure producing member side may become in fluid communication with the ambient air in the negative pressure producing member above the position of the desired gas-liquid interface with the result of unintended gas-liquid exchange, a projection151close-contacted to the inner wall of the negative pressure producing member accommodating chamber is formed, as shown inFIG. 12, (b), by which the influence of the dimple150bis prevented. By this, even if a dimple is produced in the surface of the negative pressure producing member by yielding, the stabilized gas-liquid exchanging operation can be performed, and the ink leakage can be prevented.

Referring toFIG. 12, (b), this will be further described. The projection151is in the form of a frame having a thickness of d is contacted to the surfaces facing the liquid containing chamber136, namely, to the both of the horizontal ceiling surface (gas introduction surface200) of the cut-away portion and the perpendicular surfaces210of the cut-away portion.

As regards the material of the negative pressure producing member and the yielding, the dimple150band therefore the wall surface path tend to occur in the fibers of polyester, or the like, particularly in the case of the fibers having a directional feature, than in polyurethane foam, although it is dependent on the material and structure of the negative pressure producing member.

The member constituted by fibers extending in a predetermined direction may be poorer in the follow ability and isotropic property than the foam member such as urethane foam or the like, and therefore, the stress concentration tends to occur.

The description will be made as to the ink cartridge of the second embodiment wherein the negative pressure producing member is made of fibers extended unidirectionally, which is subject to the yielding.

FIG. 13, (a) andFIG. 13, (b) are perspective views of the negative pressure producing member only provided in the ink cartridge of the second embodiment.

A maximum area sides (major sides) of the liquid container are opposed to each other with respect to the direction in which the containers are arranged in use, and therefore, it is desirable that negative pressure producing member132accommodated therein has a flexibility against compression and a repelling elasticity in a direction perpendicular to the sides. From this standpoint, the fibers may extend in the directions shown inFIG. 13, (a) and (b).

In such cases, wherein the direction of fibers is different, the position where the yielding, namely, the dimple150btends to occur is different. Since the expansion and contraction property is relatively poor in the direction of the fibers, the dimple150btends to produce in the direction perpendicular to the direction of fibers.

For example, it is predicted that when the fiber direction is as shown inFIG. 13, (a), the dimple150bshown inFIG. 9, (b) tends to result, and when the fiber direction is as shown inFIG. 13, (b), the dimple150bshown inFIG. 10, (b) tends to result. In either case, the predicted yielding can be avoided by the concept described in conjunction withFIG. 12, (b). More particularly, the end of the gap150cformed between the internal wall surface and the surface of the negative pressure producing member is sealed by the projection151formed close-contacted to the inner wall of the negative pressure producing member accommodating chamber so as to blocking the communication between the ambient air and the ink existing in the space formed by the cut-away portion of the negative pressure producing member, by which the occurrence of the wall surface path is suppressed to prevent the ink leakage attributable to the gap.

Referring toFIG. 14, the description will be made as to a fourth embodiment wherein the negative pressure producing member is divided into two portions.

FIG. 14, (a) is a schematic sectional view of an ink cartridge wherein a first negative pressure producing member132aand a second negative pressure producing member132bare accommodated in the negative pressure producing member accommodating chamber.FIG. 14, (b) is an example in which such a gap150c(dimple150b) as communicating the ink existing in the space formed by the cut-away portion with the second negative pressure producing member132b, is produced.

In such a case with the two negative pressure producing members, similarly to the case of one negative pressure producing member, when a gap continuously formed in the first and second negative pressure producing members is produced to cause a fluid communication between the ink existing in the space formed by the cut-away portion of the negative pressure producing member and the ambient air, a wall surface path may occur to cause ink leakage from the liquid container. As another problem, there is a liability of production of such a gap150cas to cause a fluid communication between the second negative pressure producing member132band the ink existing in the space formed by the cut-away portion of the negative pressure producing member, as shown in FIG.14, (b).

This problem includes two aspects which tend to result when the ink is consumed to a certain extent. In the first aspect, when the air becomes present in the ink accommodating chamber by the gas-liquid exchange, the air in the ink accommodating chamber expands or contracts by changes of the ambient temperature. When this is repeated, the ink leakage may occur. The mechanism is as follows. When the ambient temperature when the ink cartridge is used, the air in the ink accommodating chamber expands, and the amount of the ink corresponding to the expansion is discharged into the negative pressure producing member accommodating chamber. If the first negative pressure producing member132ahas the dimple150bas shown inFIG. 14, (b), a part of the ink discharged from the ink accommodating chamber is moved through the gap150cformed by the internal wall surface and the dimple150band is absorbed in the second negative pressure producing member132b. If the ambient temperature lowers then during the use of the ink cartridge, the air in the ink accommodating chamber contracts, the ink accommodating chamber tends to suck the amount of the ink absorbed in the negative pressure producing member corresponding to the volume of contraction back into the ink accommodating chamber. In this occasion, the flow resistance in sucking the air in the negative pressure producing member is smaller than the flow resistance in sucking the ink in the negative pressure producing member, with the result that air is also sucked together with the ink back into the ink accommodating chamber from the negative pressure producing member. If the expansion and the contraction are repeated, the amount of the ink corresponding to the sucked-back air remains in the negative pressure producing member accommodating chamber, so that amount of the ink retained in the negative pressure producing member accommodating chamber gradually increases to such an extent the ink leaks out.

Another aspect relates to the existence of the gap150cin the second negative pressure producing member132bas shown inFIG. 14, (b). In such a case, the gas-liquid exchange starts between the gap150cand the interface of the press-contact portion160of the first and second negative pressure producing members before the gas-liquid interface lowers to the gas introduction surface200. In other words, the gas-liquid exchanging operation starts as if the position of the gas introduction surface200were set at the position of the press-contact portion160. As a result, when the emptiness of the ink cartridge is detected, the amount of the ink still retained in the negative pressure producing member132ais larger than expected, so that ink remainder at the end of the service life of the ink container is larger than the normal remainder.

As regards the amount of the gas introduction through the gap150c, since the gas-liquid exchange may be insufficient under the large ink supply flow rate (per unit time), the gas-liquid interface temporarily lowers, but after the ink supply stops, the air is introduced into the liquid containing chamber through the150c. Correspondingly, the ink moves into the negative pressure producing member, and the ink interface rises up to the interface of the press-contact portion160which is the top end portion of the gap150c, and therefore, the ink remainder at the end of the life is larger, irrespective of the ink supply rate.

As described in the foregoing with respect to fourth embodiment, the second negative pressure producing member132bis supposed to be in fluid communication with the ink existing in the space formed by the cut-away portion of the negative pressure producing member only through the press-contact portion relative to the first negative pressure producing member132a. Therefore, in such a case, the adverse influence of the yielding if any can be avoided by sealing the end of the gap150cby the projection151formed close-contacted to the inner wall of the negative pressure producing member accommodating chamber so as to block the fluid communication between the second negative pressure producing member and the ink existing in the space formed by the cut-away portion of the negative pressure producing member.

The projection provided to prevent occurrence of the wall surface path provides a secondary effect, that is, by the projection contacting the surface of the cut-away portion of the negative pressure producing member accommodated in the negative pressure producing member accommodating chamber, the area of the negative pressure producing member which receives the compressive force (cause of the yielding) from the internal wall surface, the yielding per se is suppressed. When the negative pressure producing member is made of fibers with the directionality, for example, the surface of the cut-away portion which is substantially perpendicular to the direction of the fibers works effectively.

As regards the sealing of the end of the gap in the surface of the negative pressure producing member by the projection151formed close-contacted to the inner wall of the negative pressure producing member accommodating chamber, the occurrence of the wall surface path can be prevented irrespective of the sealing position of the extending gap. However, the sealing at one or both of the gaps is preferable since it is simple.

The projection151may be integrally molded with the liquid container, or may be formed as a separate member and bonded to the liquid container, for example.

The first to fourth embodiments of the present invention may be incorporated with the structure described here, that is, the structure in which the end of the gap produced in the surface of the negative pressure producing member is sealed, and the projection is formed close-contacted to the inner wall of the negative pressure producing member accommodating chamber so as to block introduction of the air into the ink existing in the space formed by the cut-away portion of the negative pressure producing member.

The description has been made as to the solution to the occurrence of the wall surface path with respect to the first to fourth embodiments. The description will be made as to the occurrence of a path at an apex line portion.

First, the apex line path will be described. A gap may be produce between an apex line of the inner wall of the negative pressure producing member accommodating chamber and the corresponding portion of the negative pressure producing member. If the air enters into such a gap, an unintended gas-liquid exchanging operation may occur through the gap (path). This is called “apex line path”FIG. 15, (b) shows the occurrence of the apex line path in the ink container according to the second embodiment, wherein the gap170is produced at the apex line portion of a part (side surface) of the negative pressure producing member, as is shown also inFIG. 15, (a). This defect may appear in the case that when the negative pressure producing member is inserted into the negative pressure producing member accommodating chamber, for example, the negative pressure producing member is not properly contacted to the apex line portion of the inner wall. If the apex line path is brought into fluid communication with the ambient air through the communicating portion, an unintended gas-liquid exchange occurs with the result of leakage of the ink from the liquid container.FIG. 15, (a) is a schematic view illustrating the apex line path.

FIG. 16is a schematic enlarged view of a neighborhood of a communicating portion of a liquid container wherein a projection is formed to match the configuration of the cut-away portion of the negative pressure producing member which projection is formed in order to prevent the apex line path. In this Figure, (a) is a schematic enlarged perspective view of the neighborhood of the communicating portion as seen from the negative pressure producing member accommodating chamber; (b) is a schematic enlarged sectional view of the neighborhood of the communicating portion as seen from a lateral side; and (c) illustrates the state in which the gap (apex line path) is produced at the apex line portion formed between the inner wall of the negative pressure producing member chamber and the negative pressure producing member when the negative pressure producing member is inserted into the negative pressure producing member chamber, for example.

InFIG. 16, (a), the liquid containing chamber is provided at a righthand side of the partition wall138, and the negative pressure producing member accommodating chamber is formed with the partition wall138therebetween. A projection151is provided so as to contact the apex line portion formed between the surface constituting the gas introduction surface and the inner wall connecting thereto and also the apex line portion formed between the surface constituting the communication surface and the inner wall connecting thereto.

When the negative pressure producing member132is inserted into the negative pressure producing member accommodating chamber having such a structure, the situation becomes as shown inFIG. 16, (b) (ideal situation). However, when the negative pressure producing member is not properly inserted, the apex line path170is produced as shown inFIG. 16, (c). By the formation of the projection151shown inFIG. 16, (a), however, even if the apex line path150shown inFIG. 16, (c) is produced, the negative pressure producing member is contacted to the projection151to seal the neighborhood (hatched portion inFIG. 17) of the circumference of the cut-away portion, so that ink existing in the space formed by the cut-away portion of the negative pressure producing member is prevented from fluid communication with the apex line path.

In this description, only the lateral side of the negative pressure producing member has been dealt with, but the same applies to the bottom surface of the negative pressure producing member.

In summary, as shown inFIG. 17, the end and the neighborhood (hatched portion) of the surface of the negative pressure producing member having the cut-away portion can be sealed, and even if the apex line path is produced, the projection formed is effective to prevent the fluid communication with the ink existing in the space of the cut-away portion of the negative pressure producing member.

With such a structure, even when an air path were produced at the apex line portion between the negative pressure producing member and the inner wall constituting the negative pressure producing member chamber, the ink existing in the space of the cut-away portion of the negative pressure producing member is prevented from fluid communication with the ambient air. By this, unintended gas-liquid exchanging operation can be avoided, and in addition, the ink leakage from the liquid container can be prevented.

The projection may be integrally molded with the liquid container, or may be a separate member which may be mounted to the liquid container by bonding, for example.

Any of the foregoing embodiments may incorporate the structure described here for prevention of the apex line path (the projection is formed so as to contact the negative pressure producing member so as to match the configuration of the cut-away portion of the negative pressure producing member).

As described in the foregoing, according to the embodiments of the present invention, the negative pressure producing member132is provided with a cut-away portion corresponding to the communicating portion140, and the ceiling portion of the space defined by the cut-away portion is substantially horizontal (when the ink container is set in the recording apparatus, for example, for operation) and functions as a gas-liquid introduction surface200. By doing so, the gas-liquid introduction surface200is substantially parallel with the gas-liquid interface161in the negative pressure producing member immediately before start of the gas-liquid exchange. Even in the case that ink supply per unit time to the ink jet recording head is large, the gas-liquid interface161in the negative pressure producing member132drastically expand upon arrival of the gas-liquid interface161at the gas introduction surface200to assure the wide gas introduction portion. Therefore, the amount of the air meeting the ink discharge can be speedily introduced into the ink accommodating chamber136, so that gas-liquid interface161in the negative pressure producing member132does not improperly lower, and therefore, the ink supply is stabilized without conventional ink disconnection. By this, a highly reliable ink cartridge and ink jet recording apparatus suitable for high speed operation can be provided.

The negative pressure producing member accommodating chamber134preferably accommodate first and second negative pressure producing members132aand132bwhich are press-contacted to each other, and the gas introduction surface200is disposed below the interface of the press-contact portion160between the two negative pressure producing members. With such a structure, in addition to the above-described advantageous effects, the gas-liquid interface in the negative pressure producing member is once reset by the interface in the press-contact portion160between the two negative pressure producing members, so that position of the gas-liquid interface upon the start of the gas-liquid exchange is stabilized, that is, the variation of the position of the gas-liquid interface is minimized, thus stabilizing the absolute value of the negative pressure during the gas-liquid exchange period.

This application claims priority from Japanese Patent Application No. 173472/2004 filed Jun. 11, 2004 which is hereby incorporated by reference.