Ink cartridge and ink jet printer

A casing body of an ink cartridge includes a first chamber allowing atmospheric air to enter therein, and a second chamber that stores ink. A lid within the second chamber moves vertically while partitioning the second chamber into a first space above the lid and a second space below the lid for storing ink. A gap between an outer periphery of the lid and an inner periphery of the second chamber allows a meniscus of ink to form therebetween. A partition is provided at an upper end of the second chamber to partition the first and second chambers. The partition includes a through hole at a portion which is away from the inner periphery of the second chamber, to allow the atmospheric air to enter the second chamber. An elastic member in the second chamber urges the lid upwards to maintain the second space of the second chamber at a negative pressure.

BACKGROUND OF THE INVENTION

The present invention claims foreign priority under 35 USC 119 based on Japanese Patent Application No. 2002-358386, filed Dec. 10, 2002, the contents of which are incorporated herein by reference.

The present invention relates to an ink cartridge having a plurality of ink chambers, each ink chamber having a movable member that descends with ink consumption. The invention also relates to an ink jet printer incorporating such an ink cartridge as an ink supply source.

In the related art ink cartridge for an ink jet printer, a bag-type related art ink tank is constructed such that a flexible ink bag filled with ink is in a rigid plastic case. Alternatively, a foam-type ink tank is constructed such that ink-absorbent foam or felt is in a rigid plastic case.

However, related art ink tanks have various problems and disadvantages. For example, but not by way of limitation, the efficiency of drawing ink from the bag and the foam or felt is poor. Also, the filling efficiency of the ink is low. As a result, it is difficult to reduce the size of the ink tank. Further, the bag-type ink tank has a probability of ink leakage due to poor sealing of the ink bag.

Additionally, the ink bag can break, such that ink leaks out of the bag when the ink bag and the plastic case containing the ink bag rub during transport. Related art attempts to prevent the rubbing and the bag breakage have included increasing the rigidity and strength of the flexible material forming the ink bag. However, in this modified related art ink bag, a negative pressure for supplying ink increases, and various problems arise. For example, but not by way of limitation, the amount of consumed ink increases, and the amount of residual ink varies.

Also, in the related art foam-type ink tank, foreign materials may enter the ink supplied from the foam. The foreign materials enter the ink and flow into the print head, thereby causing clogging of the printer head.

FIG. 7shows a related art ink cartridge100. Four ink chambers102(1) to102(4) are disposed side by side, with their upper ends open within a case101. An L-shaped waste ink chamber110extends from the upper parts of those ink chambers to the side parts thereof.

The ink chambers102(1) to102(4) respectively include lids103(1) to103(4), which are vertically movable along the inner peripheral surfaces102aof those chambers. Ink outlets104(1) to104(4) are formed in the bottom surfaces of the four ink chambers102(1) to102(4). Ink reservoirs105are respectively formed by bottom surfaces102band the inner peripheral surfaces102aof the ink chambers, and the movable lids103(1) to103(4).

The movable lids103(1) to103(4) are urged by spring members106in an upward direction. As a result, the ink reservoirs105experience negative pressure. The strength of an ink meniscus formed in a gap between each inner peripheral surface102aand an associated one of those movable lids103(1) to103(4) is selected such that the ink meniscus is not broken by an ink suction force of the print head, which exerts pressure on the ink outlet.

The foregoing related art ink cartridge100may be used for a multi-color ink cartridge, in which different colors of ink are stored in the four ink chambers102(1) to102(4).

However, each of the movable lids103(1) to103(4) is held within an associated one of the ink chambers102(1) to102(4) by the ink meniscus formed in a gap between the inner peripheral surface102aof the ink chamber and the outer peripheral surface of the movable lid to form the ink reservoir105in the lower side of the movable lid. Thus, the ink meniscus may break when impact is applied to the ink cartridge100, so that ink leaks to the upper side of the movable lid (i.e., the side closer to the waste ink chamber110).

When the ink leaks to the upper side of the movable lid, the leaked ink from the respective ink reservoirs105may mix with ink from other reservoirs. Then, the mixed ink may return to the respective ink reservoirs105. In addition, since the waste ink chamber110is filled with an ink absorbing member of foam or felt, fine particles contained in the ink absorbing member may mix with the leaked ink and enter the ink reservoirs105.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome at least the foregoing related art problems, as well as other problems well-known to those skilled in the art. However, the present invention is not required to be directed to solving any of the aforementioned related art problems.

It is therefore an object of the invention to provide an ink cartridge capable of preventing foreign materials from entering ink reservoirs, and avoiding mixture of ink leaked from the other ink reservoirs.

It is also an object of the invention to provide an ink jet printer incorporating such an ink cartridge as an ink supply source.

To achieve at least the above objects, according to an exemplary, non-limiting embodiment of the present invention, an ink cartridge is provided, comprising:

a casing body, including a first chamber, allowing atmospheric air to enter therein, and a second chamber storing ink therein;

a lid member, disposed within the second chamber movably in a vertical direction, while partitioning the second chamber into a first space above the lid member and a second space below the lid member for storing ink, the lid member configured such that a gap is formed between an outer periphery of the lid member and an inner periphery of the second chamber such that a meniscus of ink is formed therebetween;

a partition member, which partitions the first chamber from the second chamber, the partition member provided at an upper end of the second chamber, and having a through hole formed at a portion which is away from the inner periphery of the second chamber, the through hole allowing the atmospheric air to enter the second chamber; and

an elastic member, disposed in the second chamber to urge the lid member upwards so as to maintain the second space of the second chamber at a negative pressure.

In such a configuration, since the first chamber communicating with the atmosphere is partitioned from the second chamber, ink leaked from the second space of the second chamber via the outer periphery of the lid member hardly flows to an exterior of the ink cartridge via the first chamber.

This configuration is applicable to a multi-color ink cartridge in which a plurality of second chambers for storing plural colors of ink are provided. In such a case, even if one color of ink is leaked to the first space of the second chamber, the ink will not mix with another color of ink. Accordingly, troubles due to ink mixture can be avoided when the leaked ink returns to the second space of the second chamber.

Preferably, the ink cartridge further comprises a projection formed around the through hole so as to project from the partition member toward the first chamber.

In such a configuration, ink leaked to the first chamber will not return to the second chamber. Accordingly, it is possible to avoid problems and/or disadvantages caused by mixture of foreign matters with the leaked ink.

Preferably, the ink cartridge further comprises an ink absorber, disposed in the first chamber so as to surround an end of the through hole facing the first chamber.

In such a configuration, since ink leaked to the first chamber is absorbed by the ink absorber, at least the related art problems caused by the mixture of foreign matter with the leaked ink can be avoided.

Here, it is preferable that the ink absorber is positioned away from the end of the through hole.

If the ink absorber is in contact with the through hole, ink leaked to the first space of the second chamber may be sucked by the ink absorber.

According to the above configuration of the present invention, only the ink leaked to the first chamber is absorbed by the ink absorber, so that less ink is wasted.

Preferably, the ink cartridge further comprises a projection provided on at least one of a surface of the partition member facing the first space of the second chamber and an upper face of the lid member.

In such a configuration, since the lid member and the partition member are brought into substantially line contact with each other, adhesion of these members due to face contact therebetween is avoided.

Here, it is preferable that the projection is formed around the through hole so as to project from the partition member toward the second chamber.

Preferably, a dimension of an inner periphery of the second chamber is gradually reduced toward a lower end of the second chamber.

When the lid member closes to the lower end of the second chamber due to ink consumption, the urging force of the elastic member increases so that the meniscus formed in the gap between the outer periphery of the lid member and the inner periphery of the second chamber tends to be broken. However, according to the above configuration, the gap is narrowed in accordance with the ink consumption, so that the strength of the meniscus increases. Therefore, even when the air bubbles do not enter the second space of the second chamber.

Preferably, the ink cartridge further comprises: an inlet, connected to the first chamber and configured to supply waste ink to the first chamber; an outlet, connected to the second chamber at a lower end of the second chamber, through which the ink is supplied to an exterior of the ink cartridge; and a vent port, formed at a top portion of the ink cartridge to allow the atmospheric air to enter the first chamber. The first chamber communicates with the atmosphere at a top portion of the ink cartridge.

Preferably, the first chamber is an L-shaped space formed above and lateral to the at least one second chamber, for collection and storage of waste ink.

Preferably, the at least one second chamber comprises first through fourth supply chambers filled with black ink, cyan ink, magenta ink, and yellow ink, respectively.

According to the invention, there is also provided an ink jet printer, comprising: a print head; and the above ink cartridge, which supplies the ink from the second chamber to the print head.

Since the above ink cartridge is capable of preventing ink mixture invasion of foreign matter or air bubbles, nozzle clogging of the print head is avoided. Therefore, excellent quality of printing operation is secured.

Preferably, the ink jet printer further comprises: a platen for feeding a recording sheet in a sheet feeding direction, wherein a nozzle of the print head faces the platen; a carriage that reciprocatively moves the print head in a primary scanning direction; a cartridge holder that receives the ink cartridge and supplies ink to the print head via a nozzle; and a drive controller that controls operations of the ink jet printer.

Here, it is preferable that the cartridge holder includes an ink supply needle for removing ink from the second chamber, and an ink recovery needle that supplies a waste ink to the first chamber.

It is further preferable that the ink recovery needle receives the waste ink via a waste ink collecting passage from a nozzle cap by a pumping device positioned between the nozzle cap and the ink recovery needle.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary, non-limiting embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1schematically shows an ink jet printer according to an exemplary, non-limiting embodiment of the present invention. The ink jet printer1includes: a platen3for feeding a recording sheet2in a sheet feeding direction Y; a print head4having a nozzle face4afacing the platen3; a carriage5for reciprocatively moving the print head4in a primary scanning direction X; a cartridge holder7for receiving a multi-color ink cartridge10which supplies different colors of ink to the ink nozzles of the print head4; and a drive controller8for controlling the driving operations of related components.

The ink cartridge10includes, for example but not by way of limitation, four independent ink chambers which contain, for example, black ink, cyan ink, yellow ink and magenta ink, and an waste ink chamber14for collecting waste ink (described later in detail). The cartridge holder7is provided with ink supplying needles7(1) to7(4) for removing ink from the ink chambers, and an ink recovery needle7(5) for supplying waste ink to the waste ink chamber14. When the ink cartridge10is attached to the cartridge holder7, ink supply passages are formed, which supply different colors of ink from the ink cartridge10to the print head4.

The ink jet printer1includes a nozzle cap9located apart from the platen3in the printing direction X. The nozzle cap9is connected to the ink recovery needle7(5), through a pump6. When the ink cartridge10is attached to the cartridge holder7, a waste ink collecting passage is formed ranging from the nozzle cap9to the waste ink chamber14in the ink cartridge10, via the ink recovery needle7(5). To collect waste ink from the print head4, the nozzle face4aof the print head4is covered with the nozzle cap9. In this state, the ink pump6is driven.

As shown inFIGS. 2A through 5B, the ink cartridge10includes: a cartridge case12having a laterally elongated box shape; four ink chambers13(1) to13(4); and a waste ink chamber14. The cartridge case12includes a case body12aand a cover plate12bthat covers an opening of the top end of the case body12a. The cover plate12bis a thin plate, and its reverse side is a substantially flat surface. Ink outlets15(1) to15(4) for taking out ink from the ink chambers13(1) to13(4), and an ink inlet16for supplying waste ink into the waste ink chamber14, are formed in a bottom plate21of the case body12a.

The respective portions of the ink cartridge10will be described in detail. As shown inFIGS. 4 and 5A, the case body12aof the cartridge case12is formed with the bottom plate21having the ink outlets15(1) to15(4) and the ink inlet16, opposed side walls22and23extending from the edges of the long sides of the bottom plate21, and opposed end portions24and25extending from the edges of the short sides of the bottom plate21. The end plate portion25is arcuate in shape, and smoothly continuous to the side walls22,23.

Four ink chambers13(1) to13(4), each circular in cross section, are formed within the case body12aof the cartridge case12. Those ink chambers are open at top ends, and partitioned by four partition walls26to29, each of which connects to both of the side walls22,23. Top end openings13aof the ink chambers13(1) to13(4) are sealingly closed with a partition plate20made of a plastic material, for example but not by way of limitation.

FIGS. 6A and 6Bare perspective views showing the partition plate20as viewed from top and bottom, respectively. Four annular projections20aare provided on the lower surface of the partition plate20, while corresponding in position to circular edges13b(seeFIG. 4) of the top end openings13aof the ink chambers13(1) to13(4). The annular projections20aare thermally fused onto the edges13b, so that the partition plate20is joined to the edges13b.

Tubular projections20care formed at the centers of the annular projections20a, and tubular projections20dare formed on an upper surface20eof the partition plate20, so as to correspond to the projections20c. Air holes20bextend from upper ends of the projections20dto lower ends of the projections20cwhile penetrating through the partition plate20in its thickness direction.

As shown inFIG. 5A, a space as an ink trap is elongated laterally between the partition plate20and the cover plate12b, and a space for collecting the waste ink is elongated vertically between the side wall24and the partition wall26, so that an L-shaped space is formed as the waste ink chamber14. An ink absorbing member17, such as foam or felt, is disposed in the waste ink chamber14. An air hole12dis located at a position of the cover plate12blaterally with respect to the ink chamber13(1).

Empty spaces14a, each being circular in cross section, in which the ink absorbing member17is not present, correspond to the air holes20bof the partition plate20. By those empty spaces14a, the air holes20bare spaced from the ink absorbing member17.

The ink chambers13(1) to13(4) are filled with black ink, cyan ink, magenta ink and yellow ink, respectively. Since the structure of those ink chambers13(1) to13(4) are the same, the structure of the ink chamber13(2) will be representatively described, and in describing the remaining ink chambers13(1),13(3) and13(4), like reference numerals are used for designating like elements.

The ink chamber13(2) includes a cylindrical container31defined by the bottom plate21, the side walls22and23, and the partition walls27and28. The upper end opening of the cylindrical container31, viz., the top end openings13aof the ink chamber13(2), is sealed with the partition plate20. A coiled spring34and a movable lid33are inserted into the cylindrical container31through the top end openings13abefore the partition plate20is thermally fused to the cylindrical container. The movable lid33is upwardly urged by the coiled spring34. The ink outlet15(2) is formed at the central part of the bottom surface31bof the cylindrical container31.

An ink reservoir35which reserves the ink is defined by the bottom surface31b, the inner peripheral surface31a, and the movable lid33. An upper space38of the movable lid33communicates with the waste ink chamber14, which is open to the air via the air hole20bof the partition plate20.

The movable lid33is vertically movable along the inner peripheral surface31aof the cylindrical container31. It includes a disc-shaped lid part33aand a cylindrical part33bwhich extends downwardly from the outer peripheral edge of the lid part33a. By designing the cylindrical body part33bto have a predetermined length, the movable lid33may be smoothly moved without rattling or dragging on the inner peripheral surface31a. Filling the container31with ink, the ink advances into a gap37between the movable lid33and the inner peripheral surface31ato form an ink meniscus therein. If the gap37is designed to have an appropriate dimension, a strength of the ink meniscus formed in the gap37is larger than an ink suction force acting on the ink outlet15(2), so that the ink meniscus is not broken even at the time of ink sucking operation.

Specifically, the outer diameter of the cylindrical body part33bof the movable lids33is smaller than the inner diameter of the inner peripheral surface31aof the cylindrical container31by about 0.1 mm. When the movable lid33is inserted into the cylindrical container31in a coaxial fashion, an annular gap37of about 0.05 mm wide is formed between them. To prevent the movable lid33from dragging along the inner peripheral surface31a, the length of the cylindrical body part33bis about 8 mm.

Further, the ink reservoir35is always in a state that a predetermined negative pressure is applied by a lifting force of the movable lid33caused by the coiled spring34. Accordingly, when the ink suction force does not act on the ink outlet15(2), the ink does not leak out of the ink reservoir35via the ink outlet15(2).

A lifting force of the movable lid33caused by the coiled spring34is smaller than a strength of the ink meniscus and the ink suction force exerted by an outlet port15b. Therefore, the ink meniscus is not broken by the lifting force of the coiled spring34, and air bubbles do not advance into the ink reservoir35.

When the ink is sucked from the ink outlet15(2), the movable lids33move toward the ink outlet15(2) in accordance with an ink suction amount. For example, the lifting force by the coiled spring34is selected to fall within a range from about 5 gf to about 15 gf, in view of the strength of the meniscus in the gap37.

Since the central part of the upper surface of each movable lid33is flat, when the movable lid33moves upward, the upper surface of the movable lid33is brought into a substantially line contact with the lower end of the projection20cof the partition plate20, to stop the upward movement of the movable lid33(seeFIG. 5A).

As shown inFIG. 5B, at a part31dof the inner peripheral surface31ain the vicinity of the bottom surface31b, the inner diameter of the container31is gradually reduced such that the inner diameter of the container31is made identical with the outer diameter of the movable lid33at a lower end portion31eof the container31. The lower end portion31econtinues to the bottom surface31bvia a curved corner31f. In such a configuration, the gap between the lid33and the inner peripheral surface31ais narrowed while the movable lid33closes to the bottom surface31b, so that the strength of the meniscus formed in the gap increases. When the movable lid33reaches the lower end portion31e, the movable lid33is secured by the inner peripheral surface31a.

At a portion of the bottom wall21corresponding to the center of the bottom surface31b, a circular opening41is formed and a tubular frame42is extended downward to surround the opening41. An annular rubber packing43formed with a through hole is fitted into the cylindrical frame42so that the through hole serves as an ink outlet port15b. A tubular frame44extends upward from the bottom surface31bso as to surround the opening41to define a passage45between the ink reservoir35and the ink outlet port15b. A valve46capable of sealing the ink outlet port15bis disposed in the passage45. The valve46is always pressed against the rubber packing43by a coiled spring47to seal the ink outlet port15b.

A filter48for filtering out foreign materials is attached to an upper end of the tubular frame44. Accordingly, the filter48catches foreign materials contained in the ink supplied from the ink reservoir35to the ink supplying needle7(2), thereby preventing the foreign materials from entering the print head4.

When the ink reservoirs35of the ink chambers13(1) to13(4) are filled with the respective colors of ink, the movable lids33are placed in the vicinity of the partition plate20as shown inFIG. 5A. Specifically, the movable lids33are positioned near the upper ends of the cylindrical containers31.

Since ink meniscuses are each formed between the movable lid33and the inner peripheral surface31aof each cylindrical container31, the spaces38in the upper side of the movable lids33, which communicate with the waste ink chamber14, are partitioned from the ink reservoirs35by the movable lids33. Further, since the movable lids33are each pushed upward by the coiled spring34, the ink reservoirs35are each kept at a predetermined negative pressure.

When an ink suction force is exerted from the print head4of the ink jet printer1on each ink outlet port15b, the movable lid33moves toward the ink outlet port15bagainst the spring force of the coiled spring34. As a result, a predetermined amount of ink is supplied to the print head4, via the ink outlet port15b.

The strength of the ink meniscus formed in the gap37between the movable lid33and the inner peripheral surface31aof the cylindrical container31is larger than the ink suction force. Therefore, the ink meniscus is not broken by the ink suction force. As a result, air bubbles do not advance from the upper side of the movable lid33into the ink reservoir35, via the gap37. Further, ink does not leak from the ink reservoir35to the upper side of the movable lid33, via the gap37.

When the ink chambers13(1) to13(4) are each in an ink end state (i.e., there is substantially no more ink remaining in the chambers), the movable lids33are placed at the lower end portions31eof the cylindrical containers31, and capacities of the ink reservoirs35are reduced to the minimum. When the movable lid33descends, the coiled spring34is compressed and the force for lifting the movable lid33increases. Accordingly, the ink meniscus would be easy to break if the inner diameters remained the same.

However, since the inner diameters of the containers31are gradually reduced at tapered portions31dso that the strength of the meniscuses increases, the invasion of air bubbles to the ink reservoirs35due to the meniscus breakage can be avoided, even in the ink end state.

When the ink cartridge10is accidentally dropped, or an impact force is applied to the ink cartridge10, the movable lids33vibrate so that the ink meniscuses are broken. As a result, the ink leaks to the upper side of the movable lid33. However, since the spaces38in the upper side of the movable lids33are separated from one another by the movable lid33and the partition plate20for each of the ink chambers13(1) to13(4), the ink leaked from the respective ink reservoirs35will not mix with ink from other reservoirs35. In addition, since the air holes20bare separated from the respective inner peripheral surfaces31a, the ink leaked via the outer periphery of the movable lid33will not directly enter to the waste ink chamber14via the air holes20b. To the contrary, the ink leaked to the spaces38returns to the respective ink reservoirs35along the inner peripheral surfaces13a.

Even when ink leaks to the side of the waste ink chamber14via the air hole20bformed at the upper end of the projection20dand extended from the upper surface20eof the partition plate20, the leaked ink will not enter another ink chamber via another air hole20b. Instead, the leaked ink is absorbed by the ink absorbing member17surrounding the projections20d, and thus prevented from returning to the ink chambers13(1) to13(4) while being prevented from mixing with another color of ink. Since the leaked ink absorbed by the ink absorbing member17does not return to the ink chambers13(1) to13(4), the foreign matters derived from the ink absorbing material17will not mix with the ink leaked to the space38, and returns to the ink reservoir35.

Even when a substantial amount of ink leaks from the ink reservoir35and the space38fills with the leaked ink, since the air hole20bis separated from the ink absorbing member17, the leaked ink will not be sucked by the ink absorbing member17. Since only ink leaked to the waste ink chamber14via the air hole20bis absorbed by the ink absorbing member17, less ink is rendered useless, and ink wastage is reduced.

Further, since the movable lids33are brought into the line contact with the lower ends of the projections20c, the upper surfaces of the movable lids33are not brought into the face contact with the partition plate20and adhered thereon.

The present invention may also have various advantages, although it is not limited to these advantages, nor is it required to have these advantages. For example, but not by way of limitation, less ink is wasted, and inks of different colors are not mixed with one another. Further, foreign matter does not re-enter the reservoir, and the related art problems associated with dropping or impact of the cartridge are also substantially eliminated.

Although the present invention has been shown and described with reference to specific exemplary, non-limiting embodiments, various changes and modifications will be apparent to those skilled in the art from the teachings herein. Such changes and modifications as are obvious are deemed to come within the spirit, scope and contemplation of the invention as defined in the appended claims.

For example, but not by way of limitation, although the ink cartridge10of the above embodiment comprises four ink chambers, the number of the ink chambers may be less than or greater than four.

Further, the projections20dmay be omitted. Even in such a case, ink leaked through the air hole20bis absorbed by the ink absorbing member17surrounding the air hole20b.

In the above embodiment, a ringing phenomenon in which the partition plate20and the movable lid35are adhered is prevented by the tubular projection20c. The tubular projection20cmay be provided on at least one of the partition plate20and the movable lid35.