Patent Publication Number: US-9409407-B2

Title: Liquid ejection apparatus and tank

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national phase application of International Application No. PCT/JP2014/000093 filed on Jan. 10, 2014. This application claims priority to Japanese Patent Application No. 2013-006996 filed on Jan. 18, 2013. The entire disclosure of Japanese Patent Application No. 2013-006996 is hereby incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a liquid ejection apparatus and a tank or the like. 
     BACKGROUND ART 
     An inkjet printer that is one type of a liquid ejection apparatus performs printing on a printing medium such as printing paper by ejecting ink that is one example of a liquid from a liquid ejection head onto the printing medium. A conventionally known configuration of this inkjet printer includes an ink tank provided to store ink. For example, Japanese Laid-Open Patent Application Publication No. 2012-144016A discloses one exemplified configuration of increasing the capacity of an ink tank. In this configuration, in an attitude that ink is ejectable from a liquid ejection head, a liquid level in a liquid chamber is located at a higher position than a nozzle of the liquid ejection head, and a liquid inlet port communicating with the liquid chamber is sealed with a plug member. In order to take the air from outside into the liquid chamber, the other end of a communication path having one end communicating with an air hole is located at a lower position than the nozzle of the liquid ejection head in the liquid chamber. A meniscus is formed in the communication path, so as to stabilize ink supply to the liquid ejection head. 
     SUMMARY 
     In the attitude that ink is ejectable from the liquid ejection head, at some position of the liquid level, accidental removal of the plug member is likely to make the liquid chamber communicate with the outside air via the liquid inlet port and thereby deteriorate the stability of ink supply to the liquid ejection head. 
     In the configuration of Japanese Laid-Open Patent Application Publication No. 2012-144016A, the ink tank is placed in a container unit externally attached to a casing of the inkjet printer. In the course of detaching the container unit for the purpose of pouring ink into the ink tank, the liquid inlet port with the plug member placed therein is exposed outside. This configuration is more likely to cause accidental removal of the plug member. 
     An object of the invention is thus to provide a liquid ejection apparatus that employs an ink tank including a liquid chamber that maintains a liquid level at a higher position than a nozzle of a liquid ejection head and that a plug member placed in a liquid inlet port is unlikely to be accidentally removed. 
     The invention may be implemented by the following aspects or embodiments. 
     According to one aspect, there is provided a liquid ejection apparatus. The liquid ejection apparatus may comprise a tank that is configured to contain a liquid; a liquid ejection head that communicates with the tank and is configured to eject the liquid; a casing that is configured to place the tank and the liquid ejection head inside thereof and a cover that is configured to cover the casing. The tank may include a container portion that is configured to contain the liquid, an air introducing path that is arranged to introduce the air into the container portion, an inlet port that is configured to pour the liquid into the container portion, a sealing member that is configured to seal the inlet port, and an outlet port that is formed to supply the liquid through a tube into the liquid ejection head. In an attitude that the liquid is ejectable from the liquid ejection head, the liquid may be contained in the container portion such that a liquid level of the liquid in the container portion is located at a higher position than a nozzle of the liquid ejection head in a vertical direction; an inlet port that is an opening of the air introducing path on a container portion side thereof may be located at a lower position than the nozzle of the liquid ejection head in the vertical direction; and the sealing member may be covered by part of the cover. 
     In the configuration of this aspect, the casing of the liquid ejection apparatus integrally covers the tank and the liquid ejection head, and additionally the casing also covers the sealing member of the tank. In the attitude of the liquid ejection apparatus that the liquid is ejectable from the liquid ejection head, this configuration reduces the likelihood that the sealing member is accidentally removed by, for example, the operator&#39;s improper use. The inlet port configured to introduce the air outside of the tank into the container portion is located at the lower position than the nozzle of the liquid ejection head in the vertical direction. This configuration is more likely to suppress a variation in pressure applied to the liquid flowing out of the tank and thereby facilitates the pressure of the liquid supplied from the tank to the liquid ejection head to be maintained at a constant level. 
     In the liquid ejection apparatus of the above aspect, the cover may constitute part of a scanner unit. 
     In this aspect, the cover constitutes part of the scanner unit. This provides the liquid ejection apparatus with a simple configuration including the functions of the scanner. 
     In the liquid ejection apparatus of the above aspect, the tank may further include an air chamber that communicates with the container portion via the air introducing path, and an air communication port that is formed to introduce the air into the air chamber. 
     In this aspect, even when the liquid ejection apparatus is inclined to cause the liquid in the container portion to enter the air introducing path, the liquid is retained in the air chamber before being leaked out through the air communication port. This configuration accordingly suppresses leakage of ink from the liquid ejection apparatus. 
     In the liquid ejection apparatus of the above aspect, the container portion may be extended in a first direction that is a longitudinal direction of the container portion. A dimension of the container portion in the first direction may be longer than a dimension of the container portion in a direction perpendicular to the first direction. At least part of an area of the tank overlapping the container portion may have optical transparency along the first direction. At least an area of the casing overlapping the part of the area of the tank having optical transparency may have optical transparency. 
     In this aspect, the liquid in the container portion is visible via the area of the tank having optical transparency. The area of the casing having optical transparency overlaps the area of the tank having optical transparency, so that the liquid in the container portion is visible from outside of the casing. The liquid ejection apparatus of this aspect thus enables the liquid in the tank to be visually checked from outside of the casing. Additionally, in this liquid ejection apparatus, at least part of the area of the tank overlapping the container portion has optical transparency along the first direction. Accordingly, this liquid ejection apparatus causes the liquid in the tank to be visible along the longitudinal direction of the container portion. This configuration enables the liquid in the tank to be visually checked over a wide range of the container portion, thus improving the visibility of the liquid. 
     In the liquid ejection apparatus of the above aspect, the first direction may intersect with a horizontal direction. 
     In this aspect, the first direction is the direction intersecting with the horizontal direction, so that the container portion is inclined to the horizontal direction. The liquid in the container portion is thus accumulated on one end side of the container portion in the longitudinal direction. This facilitates the remaining amount of the liquid to be visually checked relative to the length of the container portion in the first direction. 
     In the liquid ejection apparatus of the above aspect, a sectional area of the container portion cut in a direction perpendicular to the first direction may be constant along the first direction. 
     In this aspect, the sectional area of the container portion cut in the direction perpendicular to the first direction is constant along the first direction. This provides a constant proportionality factor between the amount of consumption of the liquid in the container portion and the amount of displacement of the liquid level. This facilitates prediction of a change in remaining amount of the liquid. 
     In the liquid ejection apparatus of the above aspect, an optically transparent area of the casing that is the area having optical transparency may be configured on a front side of the liquid ejection apparatus. 
     In this aspect, the optically transparent area of the casing is configured on the front side of the liquid consuming apparatus. This configuration facilitates the visual recognition by the operator who faces the front of the liquid consuming apparatus. 
     According to another aspect, in a liquid ejection apparatus that includes a tank that is configured to contain a liquid; a liquid ejection head that communicates with the tank and is configured to eject the liquid; a casing that is configured to place the tank and the liquid ejection head inside thereof and a cover that is configured to cover the casing, there is configured the tank. The tank may comprise a container portion that is configured to contain the liquid; an air introducing path that is arranged to introduce the air into the container portion; an inlet port that is configured to pour the liquid into the container portion; a sealing member that is configured to seal the inlet port; and an outlet port that is formed to supply the liquid through a tube into the liquid ejection head. In an attitude that the liquid is ejectable from the liquid ejection head, the liquid may be contained in the container portion such that a liquid level of the liquid in the container portion is located at a higher position than a nozzle of the liquid ejection head in a vertical direction. In the attitude that the liquid is electable from the liquid ejection head, the sealing member may be covered by part of the cover. 
     In this aspect, the tank, along with the liquid ejection head, is placed inside of the casing of the liquid ejection apparatus. Additionally, the sealing member of the tank is covered by part of the cover. In the attitude of the liquid ejection apparatus that the liquid is ejectable from the liquid ejection head, this configuration reduces the likelihood that the sealing member is accidentally removed from the tank by, for example, the operator&#39;s improper use. 
     In the tank of the above aspect, in the attitude that the liquid is electable from the liquid ejection head, an inlet port that is an opening of the air introducing path on a container portion side thereof may be located at a lower position than the nozzle of the liquid ejection head in the vertical direction. 
     In this aspect, the inlet port configured to introduce the air outside of the tank into the container portion is located at the lower position than the nozzle of the liquid ejection head in the vertical direction. This configuration is more likely to suppress a variation in pressure applied to the liquid flowing out of the tank and thereby facilitates the pressure of the liquid supplied from the tank to the liquid ejection head to be maintained at a constant level. 
     In the tank of the above aspect, the container portion may be extended in a first direction that is a longitudinal direction of the container portion. A dimension of the container portion in the first direction may be longer than a dimension of the container portion in a direction perpendicular to the first direction. At least part of an area of the tank overlapping the container portion may have optical transparency in the first direction. A sectional area of the container portion cut in a direction perpendicular to the first direction may be constant along the first direction. 
     In this aspect, the sectional area of the container portion cut in the direction perpendicular to the first direction is constant along the first direction. This provides a constant proportionality factor between the amount of consumption of the liquid in the container portion and the amount of displacement of the liquid level. This facilitates prediction of a change in remaining amount of the liquid. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view illustrating a multifunction printer according to an embodiment; 
         FIG. 2  is a perspective view illustrating the multifunction printer of the embodiment; 
         FIG. 3  is a perspective view illustrating a printer of the embodiment; 
         FIG. 4  is a perspective view illustrating mechanics of the printer of the embodiment; 
         FIG. 5  is an exploded perspective view illustrating the schematic configuration of a tank according to a first embodiment; 
         FIG. 6  is a sectional view illustrating a communication path of the first embodiment; 
         FIG. 7  is a diagram illustrating the flow of ink from the tank to a liquid ejection head according to the first embodiment; 
         FIG. 8  is a perspective view illustrating mechanics of a printer according to a second embodiment; 
         FIG. 9  is a perspective view illustrating the mechanics of the printer of the second embodiment; 
         FIG. 10  is an exploded perspective view illustrating the schematic configuration of a tank of the second embodiment; 
         FIG. 11  is a diagram illustrating pouring of ink into the tank of the second embodiment; and 
         FIG. 12  is a sectional view illustrating another configuration of a tank according to a modification of the embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following describes a multifunction printer as one example of a liquid ejection apparatus according to an embodiment with reference to drawings. The multifunction printer  1  of the embodiment includes a printer  3  and a scanner unit  5  as shown in  FIG. 1 . In the multifunction printer  1 , the printer  3  and the scanner unit  5  are stacked. In the use state of the printer  3 , the scanner unit  5  is placed vertically on the printer  3 . XYZ axes as coordinate axes that are orthogonal to one another are shown in  FIG. 1 . The XYZ axes are also added as appropriate in subsequent drawings. In the state of  FIG. 1 , the printer  3  is placed on a horizontal plane (XY plane) defined by an X-axis direction and a Y-axis direction. A Z-axis direction is a direction orthogonal to the XY plane, and −Z-axis direction represents vertically downward. 
     The scanner unit  5  is flatbed type having an imaging element (not shown) such as an image sensor, a platen and a cover. The scanner unit  5  is capable of reading an image or the like recorded on a medium such as paper via the imaging element in the form of image data. The scanner unit  5  accordingly serves as a reader of the image or the like. As shown in  FIG. 2 , the scanner unit  5  is provided to be rotatable relative to a casing  7  of the printer  3 . A printer  3 -side surface of the platen of the scanner unit  5  also serves as a cover of the printer  3  to cover the casing  7  of the printer  3 . 
     The printer  3  performs printing on a printing medium P such as printing paper with ink as one example of liquid. As shown in  FIG. 3 , the printer  3  includes the casing  7  and a plurality of tanks  9 . The casing  7  is an integrally molded component that forms an outer shell of the printer  3  and includes mechanics  11  of the printer  3 . The plurality of tanks  9  are placed inside of the casing  7  to respectively contain inks used for printing. This embodiment provides four tanks  9 . The four tanks  9  respectively contain different inks. This embodiment employs four different inks, i.e., black, yellow, magenta and cyan. Each of the four tanks  9  is provided to contain a different ink. 
     The printer  3  also has an operation panel  12 . The operation panel  12  is provided with a power button  13 A and other operation buttons  13 B. An operator who operates the printer  3  faces the operation panel  12  to operate the power button  13 A and the operation buttons  13 B. A front face of the printer  3  is a surface where the operation panel  12  is provided. The casing  7  has a window  14  provided on the front face of the printer  3 . The window  14  has optical transparency. The four tanks  9  described above are placed at a position overlapping the window  14 . This configuration enables the operator to observe the four tanks  9  through the window  14 . 
     According to this embodiment, a region of each of the tank  9  facing the window  9  has optical transparency, so that ink contained in the tank  9  is visible through the region of the tank  9  having optical transparency. This enables the operator to observe the four tanks  9  through the window  14  and thereby visually check the amounts of inks remaining in the respective tanks  9 . According to this embodiment, the window  14  is provided on the front surface of the printer  3 . This configuration enables the operator facing the operation panel  12  to visually recognize the respective tanks  9  through the window  14 . This accordingly enables the operator to check the remaining amounts of inks in the respective tanks  9  while operating the printer  3 . 
     As shown in  FIG. 4  that is a schematic diagram of the mechanics  11 , the printer  3  includes a liquid ejection assembly  15  and supply tubes  16 . The liquid ejection assembly  15  includes a carriage  17 , a liquid ejection head  19  and four relay units  21 . The liquid ejection head  19  and the four relay units  21  are mounted on the carriage  17 . The supply tubes  16  are flexible and are provided between the tanks  9  and the relay units  21 . The tank  9  has an inlet port  61  (described later) provided with a plug  93 . The plug  93  is covered by part of the scanner unit  5  that serves as a cover of the printer  3 . The ink contained in each of the tanks  9  is supplied through the supply tube  16  to the relay unit  21 . The relay unit  21  relays the ink which is supplied from the tank  9  through the supply tube  16 , to the liquid ejection head  19 . The liquid ejection head  19  ejects the supplied ink from a nozzle  20  (described later) in the form of ink droplets. The cover of the printer  3  to cover over the plug  93  is not limited to the configuration using the platen of the scanner unit  5  but may be a cover of the scanner unit  5  itself. 
     The printer  3  also has a medium feeding mechanism (not shown) and a head carrying mechanism (not shown). The medium feeding mechanism drives a feed roller  22  by the power from a motor (not shown), so as to feed a printing medium P in the Y-axis direction. The head carrying mechanism transmits the power from a motor  23  via a timing belt  25  to the carriage  17 , so as to carry the carriage  17  along the X-axis direction. As described above, the liquid ejection head  19  is mounted on the carriage  17 . The liquid ejection head  19  is thus movable in the X-axis direction via the carriage  17  by the head carrying mechanism. The medium feeding mechanism and the head carrying mechanism cause ink to be ejected from the liquid ejection head  19  while changing the position of the liquid ejection head  19  relative to the printing medium P, so as to complete printing on the printing medium P. 
     First Embodiment 
     The tank  9  has a casing  31  and a sheet member  33  as shown in  FIG. 5 . The casing  31  is made of a synthetic resin such as nylon or polypropylene. The sheet member  33  is made of a synthetic resin (for example, nylon or polypropylene) in a film-like shape and has flexibility. The casing  31  includes a container portion  35  and an air chamber  37 . 
     The container portion  35  includes first wall  41 , a second wall  42 , a third wall  43 , a fourth wall  44  and a fifth wall  45 . The second wall  42 , the third wall  43 , the fourth wall  44  and the fifth wall  45  are arranged to intersect with the first wall  41  respectively. The second wall  42  and the third wall  43  are located to face each other across the first wall  41  in the Z-axis direction. The fourth wall  44  and the fifth wall  45  are located to face each other across the first wall  41  in the Y-axis direction. The second wall  42  intersects with both the fourth wall  44  and the fifth wall  45 . The third wall  43  also intersects with both the fourth wall  44  and the fifth wall  45 . In the printer  3  shown in  FIG. 3 , the fourth wall  44  faces the window  14 . According to this embodiment, the tank  9  is made of a material having optical transparency. 
     In the planar view, the first wall  41  shown in  FIG. 5  is surrounded by the second wall  42 , the third wall  43 , the fourth wall  44  and the fifth wall  45 . The second wall  42 , the third wall  43 , the fourth wall  44  and the fifth wall  45  are protruded from the first wall  41  in the −X-axis direction. Accordingly, the container portion  35  is formed in a recessed shape by the first wall  41  as bottom as well as the second wall  42 , the third wall  43 , the fourth wall  44  and the fifth wall  45 . A recess  35 A is formed by the first wall  41 , the second wall  42 , the third wall  43 , the fourth wall  44  and the fifth wall  45 . The recess  35 A is formed to be concave in the +X-axis direction. The recess  35 A is open in the −X-axis direction, i.e., on the sheet member  33 -side. Ink is contained in the recess  35 A. 
     According to this embodiment, in the container portion  35 , a length of the fourth wall  44  along the Z-axis direction is longer than a length of the second wall  42  along the Y-axis direction. In other words, in the container portion  35 , a dimension along the Z-axis direction is longer than a dimension along a direction perpendicular to the Z-axis direction. The container portion  35  is accordingly in a long shape along the Z-axis direction. The container portion  35  is extended in the Z-axis direction as its longitudinal direction. 
     The air chamber  37  is provided on an opposite side to a recess  35 A-side of the fifth wall  45 . The air chamber  37  is protruded from the fifth wall  45  on an opposite side to a fourth wall  44 -side of the fifth wall  45 , i.e., on a +Y-axis direction side of the fifth wall  45 . The air chamber  37  includes a first wall  41 , the fifth wall  45 , a sixth wall  46 , a seventh wall  47 , an eighth wall  48 , a ninth wall  49  and a tenth wall  50 . The first wall  41  of the container portion  35  is identical with the first wall  41  of the air chamber  37 . In other words, according to this embodiment, the container portion  35  and the air chamber  37  share the first wall  41 . The second wall  42  and the sixth wall  46  are continuous with each other. 
     The sixth wall  46  is protruded from the fifth wall  45  on the opposite side to the fourth wall  44 -side of the fifth wall  45 , i.e., on the +Y-axis direction side of the fifth wall  45 . The seventh wall  47  is located to face the sixth wall  46  across the first wall  41  of the air chamber  37  in the Z-axis direction. The sixth wall  46  and the seventh wall  47  are thus opposed to each other across the first wall  41  of the air chamber  37  in the Y-axis direction. The eighth wall  48  is located to face the fifth wall  45  across the first wall  41  of the air chamber  37  in the Y-axis direction. The ninth wall  49  is located to face the fifth wall  45  across the first wall  41  of the air chamber  37  in the Y-axis direction, on an opposite side to a sixth wall  46 -side of the seventh wall  47 , i.e., on a −Z-axis direction side of the seventh wall  47 . The ninth wall  49  is located between the fifth wall  45  and the eighth wall  48  in the Y-axis direction. The seventh wall  47  is placed between the eighth wall  48  and the ninth wall  49 . 
     The sixth wall  46  intersects with both the fifth wall  45  and the eighth wall  48 . The seventh wall  47  intersects with both the eighth wall  48  and the ninth wall  49 . The tenth wall  50  is located to face the sixth wall  46  and the second wall  42  across the first wall  41  of the air chamber  37  in the Z-axis direction, on an opposite side to a sixth wall  46 -side of the ninth wall  49 , i.e., on a −Z-axis direction side of the ninth wall  49 . The tenth wall  50  is protruded from the seventh wall  47  on a fifth wall  45 -side of the seventh wall  47 , i.e., on a −Y-axis direction side of the seventh wall  47 . The tenth wall  50  is arranged to intersect with the fifth wall  45  and to be protruded into the recess  35 A. There is a clearance provided between the tenth wall  50  and the fourth wall  44 . 
     In the planar view, the first wall  41  of the air chamber  37  is surrounded by the fifth wall  45 , the sixth wall  46 , the seventh wall  47 , the eighth wall  48 , the ninth wall  49  and the tenth wall  50 . The fifth wall  45 , the sixth wall  46 , the seventh wall  47 , the eighth wall  48 , the ninth wall  49  and the tenth wall  50  are protruded from the first wall  41  in the −X-axis direction. Accordingly, the air chamber  37  is formed in a recessed shape by the first wall  41  as bottom and the fifth wall  45 , the sixth wall  46 , the seventh wall  47 , the eighth wall  48 , the ninth wall  49  and the tenth wall  50 . A recess  37 A of the air chamber  37  is formed by the first wall  41 , the fifth wall  45 , the sixth wall  46 , the seventh wall  47 , the eighth wall  48 , the ninth wall  49  and the tenth wall  50 . The recess  37 A is formed to be concave in the +X-axis direction. The recess  37 A is open in the −X-axis direction, i.e., on the sheet member  33 -side. The recess  35 A and the recess  37 A are separated from each other by the fifth wall  45 . The amounts of protrusion of the second wall  42  to the tenth wall  50  from the first wall  41  are set to an identical protrusion amount, except a cutout  50 A of the fifth wall  45 . The cutout  50 A of the fifth wall  45  is located on the first wall  41 -side of a sheet member  33 -side end of the fifth wall  45 . 
     An inlet port  61  is provided on the second wall  42 . A supply port  63  is provided on the fifth wall  45 . An air communication port  67  is provided on the eighth wall  48 . The supply port  63  is located between the third wall  43  and the tenth wall  50  in the Z-axis direction. The inlet port  61  and the supply port  63  respectively serve to make outside of the casing  31  communicate with inside of the recess  35 A. The air communication port  67  serves to make outside of the casing  31  communicate with inside of the recess  37 A. The inlet port  61  is open in the longitudinal direction (Z-axis direction) of the fourth wall  44 . The supply port  63  and the air communication port  67  are respectively open in a direction intersecting with the longitudinal direction of the fourth wall  44 . 
     As shown in  FIG. 6 , a communication path  81  is provided in the casing  31  to make the recess  37 A and the recess  35 A communicate with each other. The communication path  81  is parted by a partition wall  82  and the tenth wall  50  in the recess  35 A. The partition wall  82  is protruded from the first wall  41  in the −X-axis direction, i.e., from the first wall  41  toward the sheet member  33 , in the recess  35 A. The partition wall  82  is continuous with the tenth wall  50  as shown in  FIG. 6 . The communication path  81  is formed as a groove in the partition wall  82 . The communication path  81  provided as a groove in the partition wall  82  is formed to be concave in a direction from an opposite side end to a first wall  41 -side of the partition wall  82  toward the first wall  41 . The amount of protrusion of the partition wall  82  from the first wall  41  is set to be equal to the protrusion amounts of the second wall  42  to the tenth wall  50 . 
     As shown in  FIG. 5 , the sheet member  33  is arranged to face the first wall  41  across the second wall  42  to the tenth wall  50  in the X-axis direction. In the planar view, the sheet member  33  has dimensions to cover the recess  35 A and the recess  37 A. The sheet member  33  is joined with respective ends of the second wall  42  to the tenth wall  50  and the partition wall  82  with keeping a clearance from the first wall  41 . The recess  35 A and the recess  37 A are accordingly sealed by the sheet member  33 . The sheet member  33  may thus be regarded as a cover for the casing  31 . 
     In the tank  9 , as shown in  FIG. 7 , ink  91  is contained inside of the recess  35 A.  FIG. 7  illustrates a section of the inlet port  61 , the supply port  63 , the air communication port  67  and the communication path  81  of the tank  9  cut along a YZ plane. The ink  91  in the recess  35 A is supplied from the supply port  63  to the liquid ejection head  19 . According to this embodiment, for example, in the use state of the printer  3  for printing, the supply tube  16  is connected with the supply port  63 , and the inlet port  61  is closed by the plug  93 . The supply tube  16  connects the supply port  63  with the relay unit  21 . The ink  91  in the recess  35 A is supplied from the supply port  63  through the supply tube  16  into the relay unit  21 . The relay unit  21  is provided with a supply path  95  connecting with the liquid ejection head  19 . The ink  91  in the relay unit  21  is flowed through a filter  94  and is supplied through the supply path  95  to the liquid ejection head  19 . 
     The amount of the ink  91  in the relay unit  21  decreases with progress in printing by means of the liquid ejection head  19 . During this time, the internal pressure of the relay unit  21  decreases to be lower than the atmospheric pressure. When the internal pressure of the relay unit  21  becomes lower than a negative pressure based on a head difference D 1  between the tank  9  and the liquid ejection head  19 , the ink  91  in the recess  35 A is supplied through the supply tube  16  into the relay unit  21  due to this pressure difference. The head difference D 1  corresponds to a difference in height in the vertical direction between an ink surface adjacent to the air chamber  37  in the tank  9  (in this embodiment, a surface  50 B of the tenth wall  50  facing the second wall  42 ) and the nozzle  20  of the liquid ejection head  19 . 
     According to this embodiment, the surface  50 B is located vertically below a lower limit line LM 1  indicating a lower limit of the amount of the ink  91  in the tank  9 . The surface  50 B is also located vertically above the supply port  63 . In the state that a liquid level  91 A of the ink  91  in the recess  35 A is located between an upper limit line LM 2  indicating an upper limit of the amount of the ink  91  in the tank  9  and the lower limit line LM 1 , this configuration reduces a variation in head difference D 1  accompanied with a change in position of the liquid level  91 A. As a result, this makes the ink  91  likely to be supplied stably to the liquid ejection head  19 . This configuration is also likely to lower the height position in the vertical direction of the liquid ejection head  19  relative to the tank  9 . Accordingly, this is likely to reduce the height dimension of the printer  3  in a configuration that the long tank  9  is stood in the vertical direction. This results in downsizing the printer  3  and the multifunction printer  1 . 
     The amount of the ink  91  in the recess  35 A decreases with progress in printing by means of the liquid ejection head  19 . During this time, the internal pressure of the recess  35 A decreases to be lower than the atmospheric pressure. When the internal pressure of the recess  35 A becomes lower than the atmospheric pressure, the air  97  in the recess  37 A is flowed through the communication path  81  into the recess  35 A. The internal pressure of the recess  35 A is thus more likely to be maintained at the atmospheric pressure. In the communication path  81 , a meniscus is formed on the boundary between the ink  91  on the recess  35 A-side and the air on the recess  37 A-side. This suppresses the ink  91  in the recess  35 A from being flowed into the recess  37 A. 
     The ink  91  in the tank  9  is thus supplied to the liquid ejection head  19  as described above. When the ink  91  in the recess  35 A of the tank  9  is consumed and the remaining amount of the ink  91  reaches the lower limit, the operator is allowed to refill the tank  9  with ink newly supplied from the inlet port  61 . In the course of newly pouring ink into the tank  9 , the air communication port  67  is closed, and the ink flow path from the supply port  63  to the nozzle  20  of the liquid ejection head  19  is closed. This suppresses the poured ink from flowing through the communication path  81  into the air chamber  37  (recess  37 A) in the course of newly pouring the ink into the tank  9 . This also suppresses the poured ink from flowing out of the supply port  63  toward the liquid ejection head  19  in the course of newly pouring the ink into the tank  9 . When the amount of ink poured from the inlet port  61  reaches the upper limit in the container portion  35 , the operator places the plug  93  in the inlet port  61  and subsequently opens the air communication port  67  and the ink flow path from the supply port  63  to the nozzle  20  of the liquid ejection head  19 . 
     In the attitude of the printer  3  that a liquid is ejectable from the liquid ejection head  19 , the plug  93  placed in the inlet port  61  is covered by the cover of the printer  3 . This configuration reduces the likelihood that the plug  93  is accidentally removed by, for example, the operator&#39;s improper use. 
     According to this embodiment, the scanner unit  5  or the cover of the printer  3  corresponds to the cover. The plug  93  corresponds to the sealing member. The supply tube  16  corresponds to the tube. The Z-axis direction corresponds to the first direction. The supply port  63  corresponds to the outlet port. The communication path  81  corresponds to the air introducing path. 
     According to this embodiment, the ink in the container portion  35  is visible through the fourth wall  44  of the tank  9 . The window  14  provided in the casing  7  of the printer  3  is located to overlap the fourth wall  44  of the tank  9 , so that the ink in the container portion  35  is visible from outside of the casing  7 . In this printer  3 , this enables the ink in the tank  9  to be visually checked from outside of the casing  7 . Additionally, in this printer  3 , the longitudinal direction of the container portion  35  is the Z-axis direction. Accordingly, in this printer  3 , the ink in the tank  9  is visible from outside of the casing  7  along the longitudinal direction of the container portion  35 . This configuration allows the operator to visually check the ink in each tank  9  over the wide range of the container portion  35 , thus improving the visibility of ink. 
     According to this embodiment, in the use state of the printer  3 , the Z-axis direction intersects with the horizontal direction. In the attitude that the Z-axis direction intersects with the horizontal direction, the longitudinal direction of the container portion  35  is inclined to the horizontal direction. When the Z-axis direction is the vertical direction, the longitudinal direction of the container portion  35  is perpendicular to the horizontal direction. The ink in the container portion  35  is accordingly accumulated on one end side of the container portion  35  in the longitudinal direction. This facilitates the remaining amount of ink to be visually checked relative to the length of the container portion  35  in the Z-axis direction. In the attitude that the Z-axis direction intersects with the horizontal direction, consumption of a fixed amount of ink  91  provides a larger amount of displacement of the liquid level  91 A, compared with in the attitude that the Z-axis direction is along the horizontal direction (i.e., the attitude that the longitudinal direction is the horizontal direction). This is attributed to a difference in sectional area of the container portion  35  in the horizontal direction. In the attitude that the Z-axis direction intersects with the horizontal direction, the remaining amount of ink is more readily recognizable with the eye, compared with the attitude that the Z-axis direction is along the horizontal direction. 
     Second Embodiment 
     A printer  3  according to a second embodiment has four tanks  101  as shown in  FIG. 8  that is a perspective view of mechanics  11 . In the use state of the printer  3 , a fourth wall  44  of each of the tanks  101  faces the front. In the second embodiment, on the other hand, when ink is to be newly poured into the tank  101 , the operator rotates the tank  101  in an illustrated direction R 1  prior to the pouring operation. In other words, the tanks  101  are configured to be rotatable in the second embodiment. 
     When the tank  101  is rotated in the direction R 1 , the attitude of the tank  101  is changed as shown in  FIG. 9 . When the tank  101  is rotated in the direction R 1 , a second wall  42  of the tank  101  faces the front, and a plug  93  provided in an inlet port  61  (described later) of the tank  9  is exposed. As described above, the configuration of the second embodiment is similar to the configuration of the multifunction printer  1  and the printer  3  of the first embodiment, except that the tanks  9  of the first embodiment are replaced with the tanks  101  and that the tanks  101  are configured to be rotatable. Accordingly, in the description below, the identical components to those of the first embodiment are expressed by the identical signs to those of the first embodiment and are not described in detail here. 
     As shown in  FIG. 10 , the tank  101  has a casing  103  and a sheet member  105 . The casing  103  is made of the same material as that of the casing  31 . The sheet member  105  is also made of the same material as that of the sheet member  33 . The casing  103  includes a container portion  35  and an air chamber  37 . The container portion  35  includes a first wall  41  to a fifth wall  45  and has a similar configuration to that of the first embodiment. The air chamber  37  includes the first wall  41  and a sixth wall  46  to a tenth wall  50  and has a similar configuration to that of the first embodiment. In the second embodiment, the second wall  42  and the sixth wall  46  form a step. In other words, in the second embodiment, the second wall  42  is not continuous with the sixth wall  46 . 
     In the longitudinal direction (Z-axis direction) of the fourth wall  44 , the sixth wall  46  is located on a third wall  43 -side of the second wall  42 . In the longitudinal direction of the fourth wall  44 , an inlet port  61  is provided in the fifth wall  45  arranged to connect the second wall  42  with the sixth wall  46 . According to the second embodiment, the inlet port  61  is open in a direction intersecting with the longitudinal direction of the fourth wall  44 . The sheet member  105  has a similar configuration to that of the sheet member  33  except a portion formed to along the step between the second wall  42  and the sixth wall  46 . The supply of ink from the tank  101  to the liquid ejection head  19  and the head difference D 1  of the second embodiment are similar to those of the first embodiment and are not specifically described here. 
     According to the second embodiment, when ink is newly poured into the tank  101 , the tank  101  is maintained in an attitude that the longitudinal direction of the fourth wall  44  and the vertical direction (Z-axis direction) intersect with each other (hereinafter called pouring attitude) as shown in  FIG. 11 . In the pouring attitude illustrated in  FIG. 11 , the longitudinal direction of the fourth wall  44  and the vertical direction (Z-axis direction) are perpendicular to each other. In the pouring attitude, the second wall  42  of the tank  101  faces the front as shown in  FIG. 9 . In the use state of the printer  3 , on the other hand, the longitudinal direction of the fourth wall  44  of the tank  101  and the horizontal direction (XY plane) of the tank  101  are maintained in such an attitude that intersect with each other (hereinafter called use attitude). In the pouring attitude shown in  FIG. 11 , the operator newly pours ink from a bottle  109  or the like filled with new ink through the inlet port  61  into the tank  101 . The second embodiment described above has the similar advantageous effects to those of the first embodiment. 
     In the attitude of the printer  3  that a liquid is ejectable from the liquid ejection head  19 , the plug  93  placed in the inlet port  61  is covered by the cover of the printer  3 . This configuration reduces the likelihood that the plug  93  is accidentally removed by, for example, the operator&#39;s improper use. 
     With regard to the tank  9  or the tank  101 , the sectional area of the container portion  35  in the horizontal direction (XY plane) is preferably constant from the upper limit line LM 2  to the lower limit line LM 1  in the vertical direction. This configuration provides a constant proportionality factor between the amount of consumption of the ink  91  in the container portion  35  and the amount of displacement of the liquid level  91 A. The constant proportionality factor between the amount of consumption of the ink  91  in the container portion  35  and the amount of displacement of the liquid level  91  facilitates a change in the remaining amount of the ink  91  in the container portion  35  to be accurately recognized. In the use attitude, the configuration of the container portion  35  is not limited to the configuration described in the first embodiment or the second embodiment, as long as the sectional area of the container portion  35  in the horizontal direction (XY plane) is constant from the upper limit line LM 2  to the lower limit line LM 1  in the vertical direction. As long as the sectional area of the container portion  35  is constant in the use attitude, the container portion  35  may employ a configuration that the fourth wall  44  and the fifth wall  45  are formed by curved surfaces as shown in  FIG. 12 . 
     In the respective embodiments described above, when the liquid ejection apparatus has the functions of the printer  3  but does not have the functions of the scanner unit  5 , the cover of the printer  3  arranged to cover the plug  93  may have any configuration that covers the casing  7 . In this modified application, the casing  7  may be formed integrally with the cover of the printer  3 . 
     In the respective embodiments described above, the liquid ejection apparatus may be a liquid ejection apparatus that sprays, ejects or applies and thereby consumes a liquid other than ink. The liquid ejected in the form of very small amounts of droplets from the liquid ejection apparatus may be in a granular shape, a teardrop shape or a tapered threadlike shape. The liquid herein may be any material consumed in the liquid ejection apparatus. The liquid may be any material in the liquid phase and may include liquid-state materials of high viscosity or low viscosity, sols, aqueous gels and other liquid-state materials including inorganic solvents, organic solvents, solutions, liquid resins and liquid metals (metal melts). The liquid is not limited to the liquid state as one of the three states of matter but includes solutions, dispersions and mixtures of the functional solid material particles, such as pigment particles or metal particles, solved in, dispersed in or mixed with a solvent. Typical examples of the liquid include ink described in the above embodiments and liquid crystal. The ink herein includes general water-based inks and oil-based inks, as well as various liquid compositions, such as gel inks and hot-melt inks. A concrete example of the liquid consuming apparatus may be a liquid ejection apparatus that ejects a liquid in the form of a dispersion or a solution containing a material such as an electrode material or a color material used for production of liquid crystal displays, EL (electroluminescent) displays, surface emission displays and color filters. The liquid ejection apparatus may also be a liquid ejection apparatus that ejects a bioorganic material used for manufacturing biochips, a liquid ejection apparatus that is used as a precision pipette and ejects a liquid as a sample, a printing apparatus or a microdispenser. Additionally, the liquid ejection apparatus may be a liquid ejection apparatus for pinpoint ejection of lubricating oil on precision machines such as machines and cameras or a liquid ejection apparatus that ejects a transparent resin solution of, for example, an ultraviolet curable resin, onto a substrate to manufacture a hemispherical microlens (optical lens) used for optical communication elements and the like. As another example, the liquid ejection apparatus may be a liquid ejection apparatus that ejects an acidic or alkaline etching solution to etch a substrate or the like. 
     REFERENCE SIGNS LIST 
       1  multifunction printer;  3  printer;  5  scanner unit;  7  casing;  9  tank;  11  mechanics;  12  operation panel;  14  window;  15  liquid ejection assembly;  16  supply tube;  17  carriage;  19  liquid ejection head;  20  nozzle;  21  relay unit;  31  casing;  35 A recess;  33  sheet member;  35  container portion;  37  air chamber;  37 A recess;  41  first wall;  42  second wall;  43  third wall;  44  fourth wall;  45  fifth wall;  46  sixth wall;  47  seventh wall;  48  eighth wall;  49  ninth wall;  50  tenth wall;  50 A cutout;  50 B surface;  61  inlet port;  63  supply port;  67  air communication port;  81  communication path;  82  partition wall;  91  ink;  91 A liquid level;  93  plug;  95  supply path;  97  the air;  101  tank;  103  casing;  105  sheet member; and P printing medium.