Buffer tank for inkjet printer, and inkjet printer

A buffer tank for use in an inkjet printer wherein the buffer tank is located between one or more ink storage tanks which store one or more sorts of ink, and one or more inkjet recording heads which eject the one or more inks toward a recording medium and thereby perform recording on the recording medium. The buffer tank includes a partition wall which separates an inner space of the buffer tank into a plurality of ink delivery chambers which temporarily store the one or more inks; and a pair of flexible wall portions which are spaced from each other and which cooperate with each other to constitute a portion of the partition wall and partly define a pressure-change absorbing chamber which allows the pair of flexible wall portions to be flexed to absorb the change of pressure of the one or more inks temporarily stored by the ink delivery chambers.

The present application is based on Japanese Patent Application No. 2004-188486 filed on Jun. 25, 2004, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a buffer tank for an inkjet printer wherein the buffer tank is provided on a carriage movable for printing, and also relates to an inkjet printer.

2. Discussion of Related Art

There has conventionally been known an inkjet printer including a carriage that is movable along a recording medium such as a recording sheet, and an inkjet recording head and a buffer tank both of which are provided on the carriage. The inkjet recording head has a plurality of groups of nozzles, and ejects, from each group of nozzles, a corresponding one of a plurality of sorts of inks so as to record an image such as characters, symbols, etc. on the recording medium. The buffer tank has a plurality of delivery chambers that store the plurality of sorts of inks, respectively, that are supplied from a plurality of ink storage tanks, respectively, that are not provided on the carriage, i.e., are detachably attached to a tank supporter independent of the carriage.

The buffer tank is provided in respective ink supply passages between the ink storage tanks and the inkjet recording head, and has a plurality of ink inlets to receive the plurality of sorts of inks, respectively, and a plurality of ink outlets to output those sorts of inks, respectively. The buffer tank, provided on the movable carriage, temporarily stores the inks supplied from the ink storage tanks, and functions as a damper or buffer that damps or buffers, i.e., absorbs the changes of pressure of the inks that occur when the carriage is moved.

The inkjet recording head includes a sheet-type piezoelectric actuator that selectively applies an appropriate pressure to an arbitrary one of a plurality of pressure chambers communicating with a plurality of nozzles, respectively, so that the nozzle communicating with the one pressure chamber ejects a droplet of ink at a speed and an amount that correspond to the applied pressure, and thereby records or prints an image on the recording medium.

Thus, the stable ink-ejecting characteristic of the inkjet recording head and the excellent printing performance of the inkjet printer can be maintained by damping or absorbing the pressure changes of the inks and applying the appropriate ejecting pressure to the inks.

The ink storage tanks and the ink inlets of the buffer tank are connected by a plurality of ink supply tubes, respectively. When the carriage is moved and returned during a printing operation, an acceleration is applied to the inks present in the ink supply tubes and/or the buffer tank provided on the carriage, so that the pressure changes of inks occur.

Generally, a damper is used to absorb the above-indicated pressure changes of inks. However, if the pressure damper employs, e.g., a common film having a certain degree of flexibility, the water content (i.e., water vapor) of the inks permeates the film and vaporizes, and the ambient air permeates the film and becomes air bubbles in the inks, because the film directly contacts the ambient air.

Hence, there has been practiced to absorb the pressure changes of inks by using a pressure damper that employs a film having not only a flexibility but also a resistance to gas permeation, such that the film directly contacts the ambient air.

In addition, Japanese Patent No. 2,887,605 or its corresponding U.S. Pat. No. 5,030,973A discloses a pressure damper for an inkjet printer wherein the damper employs a flexible membrane (i.e., a damper film) such that the membrane defines an outer surface of the damper and is exposed to the ambient air.

SUMMARY OF THE INVENTION

In the case where a pressure damper for an inkjet printer employs a film that defines an outer surface of the damper, the film needs to have a high resistance to gas permeation so as to prevent the water content of the inks from permeating the film and vaporizing, and prevent the ambient air from permeating the film into the inks, because the film is always kept in contact with the ambient air.

Meanwhile, in an inkjet printer wherein a buffer tank that temporarily stores inks is provided on a carriage that is moved along a recording medium for performing printing on the medium, it is desirable to employ a small-size buffer tank for the purpose of reducing the overall size of the printer. Thus, it is not appropriate to employ, e.g., a frame member that externally covers a film that provides a flexible, outer wall portion of the buffer tank, for the purpose of preventing water vapor, ambient air, etc. from permeating the film between the buffer tank and the atmosphere, because the employment of the frame member leads to increasing the size of the buffer tank even if the frame member may prevent the permeation of water vapor or ambient air.

Moreover, since the film provides the outer wall portion of the buffer tank, the film is likely to be damaged or stained when the buffer tank is attached and detached to and from the carriage or when the tank is conveyed.

In the above-described technical background, the present invention has been developed. It is therefore an object of the present invention to provide a buffer tank for an inkjet printer, and an inkjet printer including a buffer tank, each of which is free at least one of the above-indicated problems. It is another object of the present invention to provide a buffer tank and an inkjet printer each of which can be reduced in size and/or can employ a film having not so high a resistance to gas permeation.

According to a first aspect of the present invention, there is provided a buffer tank for use in an inkjet printer wherein the buffer tank is located between at least one ink storage tank which stores at least one sort of ink, and at least one inkjet recording head which ejects the at least one ink toward a recording medium and thereby performs recording on the recording medium. The buffer tank comprises at least one partition wall which separates an inner space of the buffer tank into a plurality of ink delivery chambers which temporarily store the at least one ink; and at least one pair of flexible wall portions which are spaced from each other and which cooperate with each other to constitute at least a portion of the at least one partition wall and partly define a pressure-change absorbing chamber which allows the at least one pair of flexible wall portions to be flexed to absorb the change of pressure of the at least one ink temporarily stored by the ink delivery chambers.

In the buffer tank in accordance with the first aspect of the present invention, the inner partition wall of the tank has the pressure-change absorbing chamber defined by the pair of flexible wall portions. Thus, the two flexible wall portions are located in the buffer tank, and accordingly are effectively prevented from being damaged. In addition, since the two flexible wall portions do not directly contact the ambient air, each of the flexible wall portions can be constituted by a film having not so high a resistance to gas permeation.

According to a second aspect of the present invention, there is provided an inkjet printer, comprising at least one buffer tank according to the first aspect of the present invention; at least one inkjet recording head which ejects the at least one ink toward a recording medium; and a carriage which is moved along the recording medium and on which the at least one buffer tank and the at least one inkjet recording head are mounted.

The inkjet printer in accordance with the second aspect of the present invention includes the carriage that is moved for printing, and the buffer tank that is mounted on the carriage. The buffer tank can be reduced in size and can employ a film having not so high a resistance to gas permeation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, there will be described preferred embodiments of the present invention by reference to the drawings.

FIG. 1Ashows a buffer tank1as a first embodiment of the present invention. The buffer tank1has an inner partition wall11, and two ink delivery chambers12(12A,12B) that are opposed to each other via the partition wall11. The partition wall11has an air chamber13as a pressure-change absorbing chamber that communicates with atmosphere via a straight hole15as a communication passage.FIGS. 2A and 2Bshow, in addition to the buffer tank1, two ink supply tubes2(2A,2B) and an inkjet recording head6that are assembled with the buffer tank1.FIG. 3shows an inkjet printer employing two buffer tanks1, to which the present invention is also applied.

As shown inFIG. 3, the two buffer tanks1each in accordance with the present invention are employed by the inkjet printer that additionally employs a carriage8that is movable along a recording medium, such as a recording sheet, in a direction indicated at arrow “A” while being guided by a guide member7; and four ink storage tanks9as a plurality of ink storage tanks that are detachably attached to two tank-support members9a, each as a tank supporter, that are independent of the carriage8and are fixed to a housing, not shown, of the printer. The two buffer tanks1are mounted on the carriage8. Two ink inlets20(20A,20B) of each of the two buffer tanks1receive two sorts of inks, respectively, from corresponding two ink storage tanks9out of the four tanks9via corresponding two ink supply tubes2(2A,2B) out of the four tubes2, so that the two ink delivery chambers12(12A,12B) of the each buffer tank1temporarily store the two sorts of inks, respectively. The two sorts of inks, temporarily stored by the two ink delivery chambers12A,12B, are supplied from two ink outlets30(30A,30B) of the each buffer tank1, to a corresponding one of two inkjet recording heads6via corresponding two flow-passage members3(3A,3B) out of four flow-passage members3having respective flow passages, not shown, therein.

Thus, in the present inkjet printer, the two buffer tanks1and the corresponding two inkjet recording heads6are mounted on the carriage8, as shown inFIG. 3. Each of the two buffer tanks1receives, from the corresponding two ink storage tanks9, the corresponding two sorts of inks to be ejected by the corresponding inkjet recording head6, and has the two ink delivery tanks12A,12B that are separated from each other by the partition wall11and temporarily store the received, two sorts of inks, respectively.

More specifically described, the four ink delivery chambers12of the two buffer tanks1temporarily store four sorts of inks, i.e., a black ink, a cyan ink, a yellow ink, and a magenta ink, respectively, in the order from right toward left inFIG. 3. That is, the right-hand buffer tank1stores the black ink and the cyan ink, and the right-hand inkjet recording head6ejects respective droplets of the black and cyan inks; and the left-hand buffer tank1stores the yellow ink and the magenta ink, and the left-hand inkjet recording head6ejects respective droplets of the yellow and magenta inks.

Thus, in the present embodiment, the four inks are supplied to the two buffer tanks1via the four ink supply tubes2from the four ink storage tanks9independent of the carriage8, as shown inFIG. 3. For example, the right-hand buffer tank1receives the black ink via the ink supply tube2A and stores the black ink in the right-hand ink delivery chamber12A via the ink inlet20A, and receives the cyan ink via the ink supply tube2B and stores the cyan ink in the left-hand ink delivery chamber12B via the ink inlet20B. The black ink is supplied from the ink outlet30A to the inkjet recording head6via the flow-passage member3A communicating with the ink outlet30A, so that the black ink is ejected toward the recording sheet, from a nozzle-support surface5aof a channel unit5of the recording head6. The nozzle-support surface5asupports a plurality of nozzles, not shown. This is true with each of the other, three sorts of inks.

Thus, the present inkjet printer includes the carriage8that is moved along the recording sheet when the inkjet printer performs a recording or printing operation. During the printing operation, the carriage8is reciprocated and accordingly it is frequently returned. When the carriage8is returned, the inks present in the ink supply tubes2, and the inks present in the buffer tanks1provided on the carriage8are accelerated and accordingly respective pressure of those inks are changed.

However, since the inks are supplied to the inkjet recording heads6via respective ink supply passages including the ink delivery chambers12of the ink buffer tanks1, the changes of pressure of the inks are effectively restrained.

Each of the two inkjet recording heads6includes a sheet-type piezoelectric actuator4and the channel unit5. The channel unit5has, in the nozzle-support surface5athereof a plurality of nozzles, not shown, and additionally has, in a surface thereof opposite to the nozzle-support surface5a, a plurality of pressure chambers, not shown, that communicate with the nozzles, respectively. Moreover, the channel unit5has two ink manifolds, not shown, that store the two inks supplied from the corresponding buffer tank1, and a plurality of individual ink channels, not shown, that communicate, at respective one ends thereof, with the ink manifolds and, at respective other ends thereof with the respective nozzles via the respective pressure chambers. The sheet-type piezoelectric actuator4covers respective openings of the pressure chambers of the channel unit5. Thus, the piezoelectric actuator4can apply an appropriate pressure to an arbitrary one or ones of the pressure chambers communicating with the nozzles, so that the corresponding nozzle or nozzles may eject a droplet of ink, or respective droplets of ink or inks, toward the recording sheet.

FIGS. 5A and 5Bshow a conventional buffer tank101A including a main body110A having an inner partition wall111A and two ink delivery chambers112A,112B; and two films F2, each as a flexible wall portion, that provide two wall portions of the main body110A, respectively, so as to attenuate the above explained changes of pressure of inks to such an extent that the attenuation does not adversely influence an ink-ejecting characteristic of an inkjet recording head.

Each of the films F2is constituted by a flexible thin membrane, and functions as a pressure damper that absorbs the pressure changes of the corresponding ink. Since the films F2contact the ambient air, each of the films F2needs to have a resistance to permeation of gas therethrough, for the purpose of preventing the water content (i.e., water vapor) of the ink from permeating the each film F2and evaporating from the ink, and preventing the ambient air from permeating the each film F2and forming air bubbles in the ink.

FIG. 5Ashows, in addition to the buffer tank101A, two ink supply tubes102(102A,102B); andFIG. 5Bshows the two ink delivery chambers112A,112B of the buffer tank101A. The buffer tank101A is an intermediate tank that can temporarily store two sorts of inks supplied from two ink storage tanks, not shown. Thus, the first ink delivery chamber112A receives a first sort of ink supplied via the ink supply tube102A and an ink inlet120A; and the second ink delivery chamber112B receives a second sort of ink supplied via the ink supply tube102B and an ink inlet120B.

Thus, the two sorts of inks are temporarily stored by the two ink delivery chambers112A,112B that are separated from the ambient air by the respective films F2. Since the films F2have the flexibility, the films F2effectively absorb the changes of pressure of the inks stored by the ink delivery chambers112A,112B. In addition, since the films F2have the resistance to permeation of gas therethrough, the films F2do not allow the water content (i.e., water vapor) of the inks to permeate themselves and evaporate from the inks, and additionally do not allow the ambient air to permeate themselves into the delivery chambers112A,112B and form the air bubbles in the inks. However, since the films F2cost high, the buffer tank101A also costs high. In addition, since the films F2are exposed to the atmosphere, the films F2is likely to be damaged or stained, for example, when the buffer tank101A is attached to the inkjet recording head, or is conveyed to anywhere else.

Next, one of the buffer tanks1in accordance with the present invention will be described in detail by reference toFIGS. 1A,2A, and2B.

Like the conventional buffer tank101A shown inFIGS. 5A and 5B, the buffer tank1shown inFIG. 1Ais constituted by a main body10having the inner partition wall11and the two ink delivery chambers12A,12B. The buffer tank1additionally includes two rigid cover members14that do not have a flexibility and are attached to the main body10to cover respective side openings of the two ink delivery chambers12A,12B. However, the inner partition wall11has a flexibility, as described below.

More specifically described, an inner space of the buffer tank1is separated by the inner partition wall11into the two ink delivery chambers12A,12A as a plurality of ink delivery chambers, and at least a portion of the inner partition wall11is constituted by two films Fl as two flexible wall portions that are opposed to each other and cooperate with each other to define the air chamber13as a pressure-change absorbing chamber. Each of the films Fl may be formed of a resin.

Since the inner partition wall11of the buffer tank1has the air chamber13defined by the two flexible wall portions F1, that is, since the two flexible wall portions F1are provided in the inner space of the buffer tank1, the two flexible wall portions F1are effectively prevented from being damaged. In addition, since the two flexible wall portions F1do not directly contact the ambient air, the buffer tank1can employ, as each of the two flexible wall portions, a film having a considerably low resistance to permeation of gas.

Since the buffer tank1has the single partition wall11and at least a portion of the partition wall11is constituted by the two flexible wall portions F1that are opposed to each other via the air chamber13, the two films F1as the two flexible wall portions can be easily attached to the partition wall11through the respective side openings of the two ink delivery chambers12.

In the buffer tank1, the two ink deliver chambers12are liquid-tightly closed by the two films F1as the two flexible wall portions of the partition wall11, and the two cover members14. The partition wall11has the small-diameter straight hole15as the communication passage that communicates with the air chamber13as the pressure-change absorbing chamber. The two films F1as the two flexible wall portions are fixed to the opposite surfaces of the partition wall11such that the two films F1are opposed to each other.

The two ink delivery chambers12are separated from each other by the partition wall11which is provided between the two chambers12and at least a portion of which is constituted by the two films F1as the two flexible wall portions that are adhered to a remaining portion of the partition wall11. Thus, at least a portion of the partition wall11has the air chamber13that is fluid-tightly defined and closed by the two films F1that are remote from each other.

Thus, the buffer tank1can be easily manufactured by inserting the two films F1through the respective side openings of the two ink delivery chambers12, adhering the two films F1to the respective opposite surfaces of the inner partition wall11, and attaching the two cover members14to respective opposite side surfaces of the main body10.

Since the films F1are adhered to the inner partition wall11provided in the inner space of the buffer tank1and accordingly do not directly contact the ambient air, the water content (i.e., water vapor) of the inks can be effectively prevented from permeating the films F1and vaporizing from the inks. In addition, since the ambient air can be effectively prevented from permeating the films F1and forming the air bubbles in the inks, the buffer tank1can employ, as each of the films F1, a film having a considerably low resistance to gas permeation.

Moreover, the air chamber13of the inner partition wall11of the buffer tank1communicates with the atmosphere via the small-diameter straight hole15as the communication passage. Therefore, each of the films F1can be easily flexed or stretched and accordingly can function as a damper member that absorbs, owing to the flexibility thereof, the changes of pressure of the inks.

In the case where the air chamber13has a considerably large volume, each of the films F1can be stretched or shrunk by amounts sufficient to absorb the changes of pressure of the inks, even though the air chamber13may be an isolated space. However, since the air chamber13as the pressure-change absorbing chamber communicates with the atmosphere via the straight hole15, each of the films F1can be flexed more freely and can exhibit a more excellent damping characteristic.

Thus, the small-diameter straight hole15as the communication passage is just required to allow the pressure of the air chamber13to become substantially equal to the atmospheric pressure. Therefore, the small-diameter straight hole15shown inFIG. 1Amay be replaced with a labyrinth16, shown inFIG. 1B, that has a considerably small width and includes a plurality of turning portions.

The small-diameter straight hole15as the communication passage, shown inFIG. 1A, can be easily formed, using, e.g., an electric drilling machine, in the main body10.

The labyrinth16as the communication passage, shown inFIG. 1B, is preferably employed in the case where the main body10is assembled from a plurality of components. In this case, a thin groove having a stepped or zigzag pattern or a curved pattern may be formed in one of respective contact surfaces of the two components that are designed to contact each other, and subsequently the two components may be adhered to each other.

Even if the labyrinth16may be defined by a considerably thin groove, the labyrinth16easily allows the pressure of the air chamber13to become substantially equal to the atmospheric pressure. In addition, the stepped or zigzag pattern of the labyrinth16can effectively stop the flows of, e.g., the water content of the inks. Thus, the labyrinth16prevents the films F1and the ambient air from directly contacting each other, and thereby minimizes the respective amounts of permeation of the water content of the inks or the ambient air.

The labyrinth16is shown inFIG. 1Bthat is a longitudinal cross-section view taken along a plane that extends parallel to the partition wall11and passes between the two ink delivery chambers12A,12B. The labyrinth16is formed in a substantially middle portion of an upper portion of the partition wall11, such that the passage16has an appropriate width in a direction parallel to the delivery chambers12A,12B. The labyrinth16is defined by a groove having a small cross-section area that, however, allows the pressure of the air chamber13to be kept substantially equal to the atmospheric pressure, and communicates, at one end thereof with the air chamber13and, at the other end thereof, with the atmosphere.

The labyrinth16as the communication passage is required to allow the pressure of the air chamber13to be kept substantially equal to the atmospheric pressure. Therefore, the labyrinth16may be replaced with the above-described small-diameter straight hole15, shown inFIG. 1A.

The small-diameter straight hole15, shown inFIG. 1A, not only allows the films F1to exhibit a sufficiently excellent damping characteristic, but also prevents the films F1and the ambient air from directly contacting each other and thereby minimizes the respective amounts of permeation of the water content of the inks and the ambient air.

The air chamber13as the pressure-change absorbing chamber is required to have a size and a thickness that assure that the two films F1that are opposed to each other can be prevented from contacting each other and can exhibit a desirable damping characteristic. Therefore, it is not needed to increase the thickness of the partition wall11as compared with the thickness of the partition wall111A of the conventional buffer tank101A shown inFIG. 5B.

Thus, the size of the buffer tank1need not be increased, i.e., can be kept small. This is advantageous for a full-color inkjet printer wherein a plurality of buffer tanks1that temporarily store at least four sorts of inks including a black ink, a yellow ink, a cyan ink, and a magenta ink are mounted on a carriage that is movable along a recording medium.

Since the films F1are provided in the isolated inner space of the buffer tank1, the films F1can be effectively prevented from being damaged or stained, e.g., when the carriage8is reciprocated or when the buffer tank1is attached and detached to and from the carriage8or is conveyed.

The inks are supplied to the respective ink inlets20A,20B of the ink deliver chambers12A,12B, and are temporarily stored in the same12A,12B. The inks temporarily stored in the ink delivery chambers12A,12B are delivered from the respective ink outlets30A,30B of the same12A,12B to the inkjet recording head6via the respective flow-passage members3A,3B. Finally, the inks are ejected from the channel unit5so as to perform printing.

In the buffer tank1shown inFIG. 2A, the two cover members14are attached to the opposite side faces of the main body10. Since the cover members14are formed of a resin or a metal having a high degree of rigidity, the buffer tank1enjoys a strong structure. Therefore, when the carriage8is moved, or when the buffer tank1is attached and detached to and from the carriage8, or is conveyed, the buffer tank1is advantageously prevented from being damaged.

As shown inFIG. 2B, the opposite side faces of the main body10of the buffer tank1are open before the two cover members14are attached to the main body10. Therefore, the films F1can be easily inserted and adhered through the respective open side faces of the main body10.

Each of the films F1is required to have such an area that assures that the each film F1can absorb the pressure changes of the ink stored in the corresponding ink delivery chamber12. Therefore, the two films F1are required to provide at least a portion of the partition wall11.

Thus, the buffer tank1may be produced such that first, a portion of the partition wall11is removed as shown inFIG. 1Aso as to form a void, subsequently the two films F1are adhered to the partition wall11, on either side of the void, so as to be opposed to each other and thereby define the fluid-tight air chamber13, and the two cover members14are fixed by, e.g., adhesion to the main body10.

Thus, the buffer tank1in accordance with the present invention can be easily obtained by modifying a conventional buffer tank having a partition wall

As described above, the buffer tank1has such a construction that the two ink delivery chambers12are provided on either side of the partition wall11. Therefore, the buffer tank1can be used to temporarily store two sorts of inks. Thus, in the case where four color inks, i.e., black, yellow, cyan, and magenta inks are used, it is possible to mount two buffer tanks1on the carriage8such that the two buffer tanks1are juxtaposed with each other and the four ink delivery chambers12in total are provided. However, the ink buffer tank1may be employed by such an inkjet printer that performs printing using two specific sorts of inks only. In the latter case, the inlet printer employs only one buffer tank1and only one inkjet recording head6. The two specific sorts of inks may be two color inks having respective different colors. Alternatively, the two specific sorts of inks may be a combination of one color ink (e.g., a yellow or black ink) and a diluent to be used therewith; a combination of an ultraviolet-curing resinous ink and a curing accelerator to accelerate curing thereof; a combination of a color ink and a solution to smooth a surface of a recording medium,

FIG. 4shows another buffer tank50as a third embodiment of the present invention. The buffer tank50includes a main body60and two cover members64that cover upper and lower open ends of the main body60, respectively, so as to define four ink delivery chambers62A,62B,62C,62D. Although the three ink delivery chambers62B,62C,62D are provided above an inner horizontal partition wall52, only the ink delivery chamber62B is shown inFIG. 4. The bottom ink delivery chamber62A communicates with an ink outlet66A via a connection hole61A. The three top ink delivery chambers62B,62C,62D communicate with respective ink outlets663,66C,66D via respective connection passages61B,61C,61D. The bottom cover member64has four holes80A,80B,80C,80D that communicate, at respective one ends thereof, with the four ink outlets66A,66B,66C,66D, and communicate, at the respective other ends thereof, with four manifold chambers of one or two inkjet recording heads, not shown. The four ink delivery chambers62A,62B,62C,62D has respective ink inlets70A,70D,70C,70D that receive four sorts of inks supplied from four ink storage tanks, respectively. The buffer tank50is mounted on a carriage, not shown, and is moved in a direction indicated at arrow “A”.

The three top ink delivery chambers62B,62C,62D are separated from each other by two vertical partition walls, not shown, and the horizontal partition wall52has three pairs of horizontally extending films F1A, F1B, F1C as three pairs of flexible wall portions that define three air chambers63A,63B,63C, respectively, each as a pressure-change absorbing chamber. The three air chambers63A,63B,63C communicates with atmosphere via respective straight holes65A,65B,65C, each as a communication passage. The bottom ink delivery chamber62A and the first top ink delivery chamber62B are opposed to each other via the pair of films F1A and the air chamber63A; the bottom ink delivery chamber62A and the second top ink delivery chamber62C are opposed to each other via the pair of films F1B and the air chamber63B; and the bottom ink delivery chamber62A and the third top ink delivery chamber62D are opposed to each other via the pair of films F1C and the air chamber63C.

When the buffer tank50mounted on the carriage is returned in a printing operation and an inertia force is applied to the inks temporarily stored by the ink delivery chambers62A through62D, the changes of pressure of the inks can be effectively absorbed by the pairs of films F1A, F1B, F1C and the air chambers63A,63B,63D, like in the buffer tanks1shown inFIGS. 1A and 1B.

It is to be understood that the present invention may be embodied with various changes, modifications, and improvements that may occur to a person skilled in the art without departing from the spirit and scope of the invention defined in the appended claims.