Ink cartridge

An ink cartridge including: an ink chamber storing ink; a communication chamber communicating the ink chamber with the exterior of the ink cartridge; a valve member disposed in the communication chamber such that the valve member is displaceable between a first position to shut off communication between the ink chamber and the exterior, and a second position to permit the communication; a biasing member including a side wall portion surrounding the valve member, and an engaging portion extending inward from an end of the side wall portion and engaging with the valve member, the biasing member normally holding the valve member at the first position but allowing the valve member to be placed at the second position by an elastic deformation of at least one of the side wall portion and the engaging portion, and generating a biasing force to restore the valve member to the first position; and a disengagement preventer which prevents the valve member from disengaging from the engaging portion when the valve member is abnormally operated toward the second position.

INCORPORATION BY REFERENCE

The present application is based on Japanese Patent Applications Nos. 2004-359730 and 2004-359742, both filed on Dec. 13, 2004, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an ink cartridge for supplying ink to a recording apparatus.

2. Description of Related Art

JP-2001-113723 (especiallyFIG. 4) discloses an ink cartridge for supplying ink to a recording apparatus such as inkjet printer, which cartridge is constructed such that the ink does not leak upon removal of the cartridge from the recording apparatus. This ink cartridge has an ink chamber where the ink is stored, an ink outlet through which the ink is supplied to the exterior, and an ink communication chamber.

In the ink communication chamber is accommodated a valve member, and in the ink outlet is fitted a tubular packing. The valve member is biased by a compression spring and held in contact with the tubular packing so as to close an ink passage, thereby preventing leakage of the ink from the ink chamber. When the ink cartridge is attached to the recording apparatus, an ink inlet tube disposed on the recording apparatus enters the tubular packing to push the valve member to the side of the ink chamber against the biasing force of the compression spring, so as to open the ink passage and enables ink supply.

However, in the ink cartridge described above, the displacement of the valve member is realized by use of the compression spring, and thus an internal structure of the ink cartridge using the compression spring is complex. Further, the compression spring is of metal and the ink cartridge can not be discarded as it is. That is, upon disposal of a used ink cartridge, the compression spring should be detached from the ink cartridge to be discarded separately from the other part of the ink cartridge, thereby pushing up the cost of the disposal.

To solve the above-described problems, the present applicant has proposed to replace the compression spring with a biasing member formed of an elastic material to integrally include an elastic side wall portion that surrounds the valve member and is capable of deforming in a direction of the displacement of the valve member, and an engaging portion that extends inward from an end of the side wall portion to be in contact with a surface of the valve member which surface is opposite to a valve hole. An elastic, contracting force of the side wall portion biases the valve member to a position to close the ink passage or the valve hole.

The employment of the biasing member enables to omit the compression spring, thereby preventing the internal structure of the ink cartridge from being complex. Further, being formable of an elastic material such as rubber, the biasing member needs not to be detached from the ink cartridge upon disposal of the ink cartridge. Thus, the disposal cost is not increased.

When the ink cartridge including the biasing member is attached to the recording apparatus, the ink inlet tube disposed on the recording apparatus pushes the valve member as closing the ink passage to displace the valve member by stretching the side wall portion of the biasing member against the elastic biasing force thereof so as to open the ink passage. Hence, a space for allowing expansion of the side wall portion of the biasing member should be provided.

However, a user may attach the ink cartridge to the recording apparatus in an improper manner or tamper with the ink cartridge, such that the valve member is pushed by an amount larger than a normal amount by which the valve member is expected to be pushed, or in a direction different from a normal direction in which the valve member is expected to be pushed. In the event of this, the side wall portion of the biasing member is stretched excessively, or the engaging portion is deformed into an irregular shape by locally deforming more at a part than the other part, resulting in disengagement of the valve member from the engaging portion of the biasing member, that is, the valve member gets out of the biasing member into the above-mentioned space and become incapable of getting back to a position to close the ink passage in a valve chamber defined inside the biasing member. This causes leakage of the ink from the ink cartridge and evaporation of water or other components from the ink.

SUMMARY OF THE INVENTION

This invention has been developed in view of the above-described situations and it is therefore an immediate object of the invention to provide an ink cartridge including a valve member which can maintain functioning even when the valve member is pushed by an amount larger than a normal amount or in a direction different from a normal direction, in order to prevent leakage of ink from the ink cartridge and evaporation of water and other components from the ink.

To attain the object, the invention provides an ink cartridge including:an ink chamber storing ink;a communication chamber communicating the ink chamber with the exterior of the ink cartridge;a valve member disposed in the communication chamber such that the valve member is displaceable between a first position to shut off communication between the ink chamber and the exterior, and a second position to permit the communication;a biasing member including a side wall portion surrounding the valve member, and an engaging portion extending inward from an end of the side wall portion and engaging with the valve member, the biasing member normally holding the valve member at the first position but allowing the valve member to be placed at the second position by an elastic deformation of at least one of the side wall portion and the engaging portion, and generating a biasing force to restore the valve member to the first position; anda disengagement preventer which prevents the valve member from disengaging from the engaging portion when the valve member is abnormally operated toward the second position.

According to this arrangement, when the ink cartridge is not mounted on a recording apparatus, the valve member is biased in a direction to be held in a first position where the valve member shuts off communication between the ink chamber and the exterior. When the ink cartridge is mounted on the recording apparatus, the valve member is displaced, while stretching the biasing member against a biasing force thereof, to a second position to establish communication between the ink chamber and the exterior.

Where the valve member is pushed by an amount larger than a predetermined, normal or expected amount upon mounting or attaching of the ink cartridge to the recording apparatus, or in a direction other than a normal, expected direction, the valve member tends to disengage from the engaging portion. According to this invention, however, such disengagement is prevented by the disengagement preventer. Thus, it does not occur that the valve member disengages from the engaging portion and becomes incapable of returning to the first position to shut off the communication between the ink chamber and the exterior, which would otherwise cause leakage of the ink from the ink cartridge or evaporation of water or other components from the ink.

An ink cartridge according to the invention is not limited to the above-described one that includes the biasing member integrally formed of an elastic material to include the side wall portion and the engaging portion, but the invention is also applicable to an ink cartridge including a biasing member having a structure more general. Further, the invention is applicable to not only a communication chamber on an ink supply side, i.e., an ink communication chamber formed to supply the ink in the ink chamber to the exterior therethrough, but also a communication chamber on an air introduction side, i.e., an air communication chamber formed in the ink cartridge to introduce the outside air into the inside of the ink cartridge therethrough.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, there will be described several presently preferred embodiments of the invention, by referring to the accompanying drawings.

Referring toFIGS. 1 to 7, there will be described an ink cartridge according to the first embodiment. In a schematic view ofFIG. 1, reference numerals1and2denote the ink cartridge and an inkjet recording apparatus to which the cartridge is attached.

The ink cartridge1is removably attachable to the ink jet recording apparatus2including a printhead7for ejecting ink droplets, and stores ink to be supplied to the printhead7.

The ink cartridge1includes a casing1awhich is a hollow box-like member open in its upper side, and a lid1bclosing the upper open side of the casing1a. The ink to be supplied to the printhead7is stored in an ink chamber16(shown inFIG. 2) in the casing1a. A plurality of the ink cartridges1, each containing ink of one of four colors, namely, cyan, magenta, yellow, and black, are attached to the inkjet recording apparatus2.

The inkjet recording apparatus2includes a mounting portion3at which each ink cartridge1is removably attached, a tank5which stores ink as supplied from the ink cartridge1via a flexible ink supply tube4, the printhead7which ejects droplets of the ink stored in the tank5onto a recording sheet6, a carriage on which the tank5and the printhead7are mounted and which is reciprocated in a horizontal direction, carriage shafts9serving as a guide along which the carriage8reciprocates, a feeding mechanism10for feeding the recording sheet6, and a purging device11.

The mounting portion3has a base portion3aand two guide portions3bstanding upright from opposite ends of the base portion3a. In the base portion3ainterposed between the guide portions3b, there are disposed a hollow ink inlet tube12via which the ink stored in the ink cartridge1is drawn into the ink supply tube4, and an air supply passage13through which air is supplied into the ink cartridge1.

The ink supply tube4is connected to an end of the ink inlet tube12so that the ink inlet tube12is communicated with the tank5via the ink supply tube4. One of opposite ends of an air supply tube15is connected to the air supply passage13, and the other end of the air supply tube15is communicated with the atmosphere.

In a surface of the printhead7to be opposed to the recording sheet6, a plurality of nozzles are arranged. Hereinafter, this surface will be referred to as “the nozzle surface”. By driving an actuator constituted by a piezoelectric element, the ink stored in the tank5is ejected in the form of droplets through the nozzles toward the recording sheet6. Recording or printing on the recording sheet6is performed while the carriage8on which the printhead7is mounted is being reciprocated.

The printhead7is located above the mounting portion3so that the ink inside the nozzles is applied with a negative back pressure due to a head difference between the nozzles and the ink cartridge1as attached at the mounting portion3.

The purging device11is disposed to be opposed to the printhead7at a position outside a recording area, and includes a purge cap11ato cover the nozzle surface of the printhead7, a waste ink tube11bin communication with the purge cap11a, and the pump11cwhich sucks the ink from the nozzles via the waste ink tube11b.

When a purging operation is implemented, the carriage8is moved to a purging position, and the nozzle surface of the printhead7is covered by the purge cap11a. In this state, the pump11cis driven to suck bad ink containing bubbles and others and accumulated inside the printhead7. The sucked bad ink is drawn via the waste ink tube11binto a waste ink tank (not shown) to be stored therein. Recording and purging is controlled by a central processing unit or a CPU (not shown) in the inkjet recording apparatus2.

Referring now to cross-sectional views ofFIGS. 2 and 3, there will be described a structure of a joint portion as indicated by reference symbol A inFIG. 1, at which the ink cartridge1is attached to the inkjet recording apparatus2.FIG. 2shows a state before the ink cartridge1is attached to the inkjet recording apparatus2, andFIG. 3shows a state in which the ink cartridge1is attached thereto.

The ink cartridge1includes the casing1a, the lid1b, and a cap1e. The casing1ahas a bottom wall1cand a side wall1ithat partially define the ink chamber16, and is open at an upper side. The lid1bcovers the upper open side of the casing1a, and the cap1ecaps the bottom wall1cof the casing1a. The ink cartridge1is formed by fusing and bonding the lid1band the cap1eto the casing1a. Through the cap1eare formed two exposing holes1f,1gthrough which valve devices23,24(described later) are respectively exposed.

On a lower side of the bottom wall1c, there are formed an ink communication chamber30and an air communication chamber50. The ink in the ink chamber16is supplied to the exterior through the ink communication chamber30, and the atmospheric air is introduced into the ink chamber16through the air communication chamber50. The communication chambers30,50are respectively partially defined inside tubular wall portions1h,1kthat extend from the lower surface of the bottom wall1c.

In the bottom wall1care formed an ink inlet port1dfor communication between the ink communication chamber30and the ink chamber16, and an air introducing port1jfor communication between the air communication chamber50and the ink chamber16. The air introducing port1jhas an internal diameter substantially the same as that of the air communication chamber50. On an upper surface of the bottom wall1cat a position corresponding to the air introducing port1j, a tubular member62extends in the ink chamber16.

Inside the tubular member62is defined an internal passage having a first portion62aand a second portion62b. The first portion62aof the internal passage extends from the air introducing port1jin a direction into the ink chamber16and gradually narrows in this direction in cross-sectional view, and the second portion62bextends substantially straight from the first portion62afurther into the ink chamber16. The air communication chamber50is open in the ink chamber16over an ink surface via the first and second portions62a,62bof the internal passage.

A plurality of ribs70are formed continuously from an inner surface of the first portion62aof the internal passage to an upper portion of the air communication chamber50that is contiguous with the internal passage, such that each rib70extends toward a guide bar66of a valve member65described later. The number of the ribs70is three or more. A distance T1between a lower end surface70aof each rib70and an engaging portion73of a biasing member63(described later) is determined such that when the ink cartridge1is attached to the inkjet recording apparatus2as shown inFIG. 3, the engaging portion73is spaced from the lower end surface70aof the rib70with a clearance smaller than the distance T1therebetween.

On an inner surface of the ink communication chamber30, there is formed a predetermined number of ribs71extending from a lower surface of the bottom wall1ctoward an engaging portion37of a biasing member46and accommodated in the ink communication chamber30as described later. The number of the ribs71is three or more. A distance T2between a lower end surface71aof each of the ribs71and the engaging portion37is determined such that when the ink cartridge1is attached to the inkjet recording apparatus2as shown inFIG. 3, the engaging portion37is spaced from the lower end surface71aof the rib71with a clearance smaller than the distance T2therebetween.

Valve devices23,24are disposed in the ink and air communication chambers30,50, respectively. Hereinafter, the side associated with the ink communication chamber30may be referred to as “the ink supply side”, while the side associated with the air communication chamber50may be referred to as “the air introduction side”. The valve device23on the ink supply side includes the biasing member46integrally formed of elastic material, and a valve member54of resin. An outer shape of the biasing member46is substantially cylindrical. The biasing member46includes a valve seat portion46a, a biasing portion46bon a side of the valve seat portion46anear the ink chamber16, and an attaching portion33around the valve seat portion46a, that46a,46b,33are integrally formed. The valve member54is accommodated in a valve chamber defined inside the biasing portion46band biased by the biasing portion46bin a direction to be held in contact with the valve seat portion46a.

An outer diameter of the attaching portion33is larger than that of the biasing portion46b. The ink communication chamber30has an enlarged portion44where the diameter of the ink communication chamber30is larger than the other part. The attaching portion33is fitted in this enlarged portion44. The biasing member46is fixed in position with the attaching portion33held between the inner surface of the ink communication chamber30and the cap1e.

The valve seat portion46ahas a through-hole formed at a center thereof. The through-hole includes an upper portion41, an insertion portion35under the upper portion41, and a tapered guide passage40under the insertion portion35. The insertion portion35is formed in a size to allow fitting insertion of the ink inlet tube12when the ink cartridge1is attached to the mounting portion3.

The biasing portion46bincludes a cylindrical side wall portion36standing from a circumference of the valve seat portion46atoward the ink chamber16, and the engaging portion37extending from the side wall portion36inward, namely, to a side of the valve member54near the ink chamber16. The engaging portion37has at its center an opening37a, whose diameter d1is smaller than a diameter d2(shown inFIG. 4C) of a protrusion57a(described later) of the valve member54.

The biasing portion46bbiases the valve member54toward the valve seat portion46a, by an elastic force of the side wall portion36and the engaging portion37. Normally, the valve member54is held in close contact with the valve seat portion46a. When the ink inlet tube12is inserted into the insertion portion35, the ink inlet tube12pushes the valve member54toward the ink chamber16, and the pushed valve member54in turn pushes the engaging portion37upward with the side wall portion36stretched, thereby forming a clearance between a lower surface of the valve member54and the valve seat portion46aso as to allow passage of the ink.

According to the present embodiment where the biasing member46,63is integrally formed to include the valve seat portion46a,63a, the side wall portion36,72, and the engaging portion37,73, the number of components can be reduced, thereby enabling to simplify a production process of the ink cartridge1. Further, since the valve seat portion46a,63ais formed of an elastic material, sealability between the valve seat portion46a,63aand the valve member54,65(68) is improved, thereby making it possible to reliably shut off communication between the ink chamber16and the exterior of the ink cartridge1when the valve member54,65(68) is in contact with the valve seat portion46a,63a.

As shown inFIGS. 4A-4D, the valve member54includes a bottom portion57, a cylindrical side wall portion56extending perpendicularly upward from a circumference of the bottom portion57, and a communication passage58continuously formed from the bottom portion57to the side wall portion56. The bottom portion57has the protrusion57a, which is annular, at a side thereof opposed to the valve seat portion46a. The protrusion57ais formed radially inside of the communication passage58, but on an outer side of an open end of the upper portion41or the through-hole formed in the valve seat portion46a. With the valve member54pressed by the biasing portion46bonto the valve seat portion46a, the protrusion57aof the valve member54elastically deforms and closely contacts an upper surface of the valve seat portion46a. The diameter d2(shown inFIG. 4C) of the protrusion57ais larger than the diameter d1(shown inFIG. 2) of the opening37aformed at the center of the engaging portion37.

Similarly to the valve device23on the ink supply side, the valve device24on the air introduction side includes a biasing member63integrally formed of an elastic member, and a valve member65of resin. The biasing member63is similar to the biasing member46of the ink supply side, that is, the biasing member63includes a valve seat portion63a, a biasing portion63b, an attaching portion63e, that are integrally formed. The biasing portion63bis similar to the biasing portion46bof the ink supply side, and includes a cylindrical side wall portion72standing upright from a circumference of the valve seat portion63atoward the ink chamber16, and the engaging portion73extending from the side wall portion72inward, namely, to a side of the valve member65near the ink chamber16. The engaging portion73has at its center an opening74, whose diameter d3(shown inFIG. 2) is smaller than a diameter d4(shown inFIG. 5C) of a protrusion157a(described later) of the valve member65. The functions of the respective parts of the biasing member63are the same as those of the biasing member46at the ink supply side, and description thereof is dispensed with.

The valve seat portion63ahas a through-hole63c, through which an operating portion67(described later) of the valve member65is inserted. Under the valve seat portion63a, a cylindrical sealing portion63dis integrally formed to around an open end of the through-hole63c.

As shown inFIGS. 5A-5C, the valve member65includes a guide bar66at its upper side, the operating portion67at its lower side, and a valve portion68substantially at its middle portion. Similarly to the valve member54shown inFIGS. 4A-4D, the valve portion68includes a bottom portion157, a side wall portion156, a communication passage158, and a protrusion157aon a lower surface of the bottom portion157. The valve portion68is similar in structure as the valve member54, and the parts or elements corresponding to those of the valve member54will be denoted by the same reference numerals and description thereof is omitted. That is, at the air introduction side, the valve portion of the valve member65corresponds to a valve member as defined in the appended claims.

The guide bar66is cylindrical and stands upright from the bottom portion157. The guide bar66is inserted through the opening74of the biasing portion63bwith a clearance between the guide bar66and an inner circumferential surface of the opening74, such that the guide bar66is located at a position to be surrounded by the ribs70.

The operating portion67is a part vertically or downward extending from the bottom portion157, through the through-hole63cformed in the valve seat portion63awith a clearance between an inner circumferential surface of the through-hole63cand the operating portion67to allow passage of the air.

In the mounting portion3at which the ink cartridge1is attached, the ink inlet tube12protrudes on the ink supply side, and an elastic porous material3csuch as sponge material is embedded around a lower base portion of the ink inlet tube12. The elastic porous material3cis disposed there to absorb ink leaking from the ink cartridge1, although such ink leakage is to be prevented by the arrangement according to the present invention. That is, the elastic porous material3cis disposed to provide for some extreme situations.

A communication opening12ain the form of a cutout is formed at an upper end of the ink inlet tube12so as to communicate, in a radial direction of the ink inlet tube12, an internal passage formed inside the ink inlet tube12and a space around the ink inlet tube12. When the ink inlet tube12is brought into contact with the valve member54, the communication opening12aensures communication between the internal passage defined in the ink inlet tube12and the ink chamber16.

At the air introduction side of the mounting portion3, a recess3dis formed at a position corresponding to the sealing portion63dof the biasing member63of the ink cartridge1. In the recess3d, the air supply passage13is open at a position not to be completely covered by a lower end of the operating portion67. When the ink cartridge1is attached on the mounting portion3as shown inFIG. 3, the sealing portion63dis fitted in the recess3dwith an end portion of the sealing portion63delastically deformed to be held in close contact with a bottom of the recess3d, thereby establishing sealed communication between the air supply passage13and the air introducing port1j.

Referring toFIGS. 2 and 3, there will be described a state when the ink cartridge1is attached to the mounting portion3. Before the ink cartridge1is attached to the mounting portion3, as shown inFIG. 2, at the air introduction side the operating portion67protrudes downward from the cap1ewith a lower end of the operating portion67located slightly above an extreme lower end of the sealing portion63d, and the valve member65is biased by the biasing portion63bto be held in close contact with the valve seat portion63a. Meanwhile, at the ink supply side the valve member54is biased by the biasing portion46bto be held in close contact with the valve seat portion46a.

When the ink cartridge1is attached on the mounting portion3as shown inFIG. 3, at the ink supply side an upper end of the ink inlet tube12pushes the valve member54upward, thereby stretching the side wall portion36of the biasing portion46bso that the valve member54separates away from the valve seat portion46a, placing the valve device23in an open state where the valve member54is at a first position to permit communication between the ink chamber16and the exterior of the ink cartridge. Hence, the ink stored in the ink chamber16is supplied into the ink inlet tube12via the ink inlet port1d, the ink communication chamber30, the opening37aformed in the engaging portion37, the communication passage58(shown inFIGS. 4A-4D) in the valve member54, and the communication opening12aat the end of the ink inlet tube12.

Meanwhile, at the air introduction side, in a state where an end of the operating portion67is held in contact with the bottom of the recess3dto fix the valve member65in position, the valve seat portion63aof the biasing member63is displaced downward relatively to the valve member65, in other words, the valve member65is pushed upward relatively to the valve seat portion63a, with the side wall portion72of the biasing portion63bstretched so that the valve member65separates away from the valve seat portion63a, thereby placing the valve device24in an open state where the valve member65is placed in a first position to communicate the inside of the ink cartridge with the exterior thereof. The guide bar66of the valve member65moves along vertically extending end surfaces of the ribs70which surfaces are opposite to an inner surface of the air introducing port1j, such that even when a direction in which the valve member65is pushed deviates from an exactly vertical direction which is a normal direction in which the valve member65is expected to move by being pushed (hereinafter, the normal direction in which the valve member65is expected to be pushed may be referred to as “the normal direction in which the valve member65is expected to move”), the deviation is limited by the ribs70that make the valve member65move in a substantially vertical direction. That is, the vertically extending end surfaces of the ribs70correspond to a guiding portion. Thus, the side wall portion72is stretched substantially uniformly over an entire circumference thereof, thereby inhibiting the conventionally seen local stretch at the side wall portion which makes the valve member to tend to get out of the engaging portion, and enabling to have the valve member operate normally.

When the valve device24is placed in the open state, the ink chamber16is communicated with the space outside the recording apparatus2, via the air supply passage13, the clearance between the operating portion67and the through-hole63c, the communication passage158(shown inFIGS. 5A-5C) in the valve member65, the clearance between the guide bar66and an internal circumferential surface of the opening74in the engaging portion73, the air communication chamber50, a space between each adjacent two ribs70in the first portion62aof the internal passage defined in the tubular member62, and the second portion62bof the internal passage.

Referring next toFIG. 6, there will be described how each valve device23,24operates when the valve member54,65is pushed upward by an amount larger than a normal, expected amount, in a case where the ink cartridge1is improperly attached or where a user tampers with the ink cartridge1, for instance.

The biasing members46,63respectively supporting the valve members54,65are formed of elastic material. Hence, when the valve member54,65is pushed upward, the side wall portion36,72is stretched to be longer, thereby making the engaging portion37,73inclined to widen the opening37,73of the engaging portion37,73. When the side wall portion36,72is further stretched upward, the valve member54,65makes the engaging portion37,73greatly inclined to enlarge the opening37a,74so that the valve member54,65disengages from, or gets out of, the biasing member46,63through the opening37a,74. The valve member54,65once having gotten out of the biasing member46,63in this way can not return to the position to be held in close contact with the valve seat portion46a,63a.

In the ink cartridge according to the present embodiment, the lower end surfaces71a,70aof the ribs71,70function as a limiter for inhibiting each of the valve members54,65from moving by an excessively large amount. That is, the distance T1, T2between an upper surface of the engaging portion37,73and the lower end surface71a,70aof the rib71,70is determined such that before the opening37a,74enlarges to a size larger than the valve member54,65to allow the valve member54,65to come out of the engaging portion37,73, the upper surface of the engaging portion37,73is brought into contact with the lower end surface71a,70aof the rib71,70, as shown inFIG. 6.

Hence, even when the valve member54,65is pushed upward by an amount beyond a normal, expected amount, the valve member54,65does not disengage from the biasing member46,63, that is, does not get out of the biasing member46,63through the opening37a,74, thereby preventing the valve device23,24from being left in their open state which may be otherwise caused and lead to problems such as leakage of the ink to the exterior of the ink cartridge, and increase in the viscosity of the ink due to evaporation of water or other components from the ink.

According to the present ink cartridge, a limiter is constituted by a surface (namely, the lower end surface of each rib) with which the engaging portion is brought into contact before the valve member disengages from the engaging portion. That is, that surface can serve as a limiter by suitably determining the distance between the surface and the engaging portion, thereby enabling to simplify an internal structure of the ink cartridge.

It is noted that the place where ink leakage occurs is not limited to the valve device23on the ink supply side. That is, it may happen that the ink is introduced into the first and second portions62a,62bof the internal passage, for instance when a user falls the ink cartridge while carrying the ink cartridge, and thereafter the ink leaks from the valve device24upon placing the valve device24on the air introduction side in the open state. Similarly, components of the ink such as water may evaporate at the valve device23on the ink supply side.

When the valve member54,65is pushed in an obliquely upward direction that is deviated from a normal, vertical direction in which the valve member54,65is expected to move by being pushed, a part of the side wall portion36,72is greatly stretched to accordingly deform the opening37a,74, making the valve member54,65prone to get out of the biasing member46,63through the opening37a,74. At the valve member24on the air introduction side, the guide bar66slides on the ribs70and is thus guided in a substantially vertical direction, as described above. Hence, it does not occur that only a part of the side wall portion72is greatly stretched, and thus the possibility of the disengagement of the valve member65from the biasing member63through the opening74is reduced. In this embodiment, since the air communication chamber has an internal passage communicating with the ink chamber, at a position to allow the valve member to enter the internal passage when the valve member is pushed upward, and a guiding portion constituted by the ribs extending from the inner surface of the internal passage toward the guide bar cooperates with the guide bar to constitute a guide device, a fluid passage is formed between the inner surface of the internal passage and the guide bar, and the guide bar can be properly guided along the ribs.

In the present embodiment, this guiding of the valve member65to prevent local great stretch of the engaging portion73is implemented at the valve device24on the air introduction side, but a guide bar may be employed in the valve device23on the ink supply side, too, so as to have the valve member54guided by the ink inlet port1dor the ribs71.

According to this embodiment, even where the valve member54,65disengages from the biasing member46,63through the opening37a,74when pushed abruptly since the biasing member46,63has a dimension smaller than a nominal dimension because of a manufacturing error or for other reasons, or since the side wall portion36,72does not sufficiently stretch accordingly to pushing of the valve member54,65, it is prevented that the valve device23,24of the ink cartridge is kept in the open state, for the following reason.

That is, as described above, the diameter d2, d4of the protrusion57a,157aof the valve member54,65is larger than the diameter d1, d3(shown inFIG. 2) of the opening37a,74, and the distance T1, T2(shown inFIG. 2) is substantially equal to or slightly smaller than a height or thickness of the valve member54,65in a direction parallel to the direction in which the valve member54,65moves, i.e., a dimension from a lower end of the protrusion57a,157ato a lower surface of the engaging portion37,73when not stretched. Hence, when the valve member54,65disengages from the biasing member46,63or gets out through the opening37a,74, as shown inFIG. 7, the side wall portion36,72contracts such that the engaging portion37,73changes its shape along a lower surface of the valve member54,65back to its original shape. Consequently, the valve member54,65is sandwiched between the upper surface of the engaging portion37,73and the lower end surface71a,70aof each rib71,70, so that the lower surface of the valve member54,65closes the opening37a,74. Thus, in the event of the disengagement of the valve member54,65from the biasing member46,63through the opening37a,74, the valve device23,24is prevented from being left in the open state. In the conventional arrangement, on the other hand, the valve device23,24can not be restored from this open state to a closed state where the valve member54,65is placed in a second position to shut off the communication between the ink chamber and the exterior of the cartridge. Thus, according to the present embodiment, the problems due to the valve device23,24left in the open state, such as ink leakage, are prevented.

According to the first embodiment, a guiding portion of a guide device and a limiter are constituted by the same element, namely, the ribs. Hence, the number of components of the ink cartridge can be reduced.

Referring next toFIG. 8, there will be described an ink cartridge according to a second embodiment of the invention. The parts and elements corresponding to those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

In the first embodiment, the ribs70,71limit the displacement of the valve member65,54. However, according to the second embodiment, in place of the ribs70on the air introduction side and the ribs71on the ink supply side, engaging portions73,37are brought into abutting contact with a ceiling surface50aof the air communication chamber50and a ceiling surface30aof the ink communication chamber30, respectively, to limit the displacement of the valve members65,54, as shown inFIG. 8.

As shown inFIG. 8, an inner surface of a first portion62aof an internal passage is cylindrical and spaced from an outer circumferential surface of a guide bar66by a small distance, so that the guide bar66is guidable along the inner surface of the first portion62aof the internal passage in sliding contact therewith.

According to the second embodiment, since the air communication chamber has an internal passage communicating with the ink chamber, at a position to allow the valve member to enter in the internal passage when the valve member is pushed upward, the valve member, and a guiding portion constituted by the inner surface of the internal passage cooperates with the guide bar to constitute a guide device, an internal structure of the ink cartridge is simplified.

According to the ink cartridge of the second embodiment, a limiter is constituted by a surface (namely, the ceiling surface of the air communication chamber and the ink communication chamber) with which the engaging portion is brought into contact before the valve member disengages from the engaging portion. That is, that surface can serve as a limiter by suitably determining the distance between the surface and the engaging portion, thereby enabling to simplify an internal structure of the ink cartridge.

Referring toFIG. 9, there will be described an ink cartridge according to a third embodiment of the invention. The parts and elements corresponding to those in the first embodiment will be denoted by the same reference numerals and description thereof is omitted.

As shown inFIG. 9, a plurality of ribs76, each having a downward protruding portion76a, extend from a ceiling surface of an ink communication chamber30to meet at a substantially central portion, in plan view, of the ink communication chamber30. The protruding portions76acooperate to constitute a protrusion whose lower end surface is directly opposed to the valve member54through an opening37aformed in an engaging portion37, so that when the valve member54is lifted, the protrusion made up of the protruding portions of the ribs76enters the opening37aof the engaging portion37to directly contact the valve member54so as to prevent an excessive displacement of the valve member54. It is noted that a horizontally extending part of the group of the ribs76corresponds to a bridge, and the protrusion made up of the protruding portions76aof the ribs76corresponds to a direct contact portion.

An upper end of a guide bar66of a valve member65is directly brought into contact with a ceiling surface of an air communication chamber50, so as to prevent an excessive movement of the valve member65. One of the ceiling surface75and the guide bar66has a communication passage66awhich allows air communication while the guide bar66is in contact with the ceiling surface75.

According to the ink cartridge of the third embodiment, a limiter is constituted by a surface (namely, the ceiling surface75, and the lower end surface of the protrusion made up of the protruding portions76aof the ribs76) with which the valve member is directly brought into contact before the valve member disengages from the engaging portion. That is, that surface can serve as a limiter by suitably determining the distance between the surface and the engaging portion, thereby enabling to simplify an internal structure of the ink cartridge.

In each of the above-described embodiments, the opening37a,74are formed in the biasing members46,63to open in the direction of the displacement of the valve members54,65so as to permit communication of the ink and the air. However, a position at which the opening37a,74is formed in the biasing member46,63is not limited to this. For instance, as long as communication between the valve chamber accommodating the valve member54,65and the ink or air communication chamber30,50can be established, the opening37a,74may be formed in the side wall portion36,72of the biasing member46,63. When the opening37a,74is formed in the side wall portion36,72, the communication passage58,158of the valve member54,65can be omitted.

Each of the embodiments may be modified such that the air supply passage13in the mounting portion takes the same form as the ink inlet tube12, namely, a tubular form extending upward from the mounting portion, and the valve device24on the air introduction side has the same structure as the valve device23on the ink supply side. Alternately, each embodiment may be modified such that the ink supply tube12does not protrude from the mounting portion and the valve device23on the ink supply side has the same structure as the valve device24on the air introduction side.

Although several embodiments of the present invention have been described above, it is to be understood that the invention is not limited to the details of the embodiments, but may be otherwise embodied with various changes and modifications which may occur to those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.