Abstract:
An ink cartridge storage structure and method provide consistent print density and quality by mixing the ink when the cartridge is removed from the packaging and installed to a printer for use. An ink-filled ink cartridge with an ink supply port installable to the head of a printer is stored inside an individual box made to hold the ink cartridge. The ink cartridge is stored inside the individual box so that the ink supply port is at the top when the box is in the normal upright position.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a structure and method for storage of an ink cartridge used to supply ink to the recording head of a recording apparatus. 
     2. Description of Related Art 
     A related art inkjet recording apparatus (i.e., “printer”) generally has a recording head mounted on a carriage, and moves widthwise to the paper or other recording medium. The related art inkjet also includes a paper transportation mechanism for transporting the paper relative to the recording head in a direction perpendicular to the direction of recording head travel. 
     This related art inkjet printer prints to the recording medium by discharging ink droplets from the recording head based on the print data. If a recording head capable of discharging various colors of ink, such as black, yellow, cyan, and magenta, is mounted on the carriage, the inkjet printer can print in full color by adjusting the discharge ratio of the different ink colors, and is thus not limited to printing text with black ink. 
     An ink cartridge for supplying the ink to the recording head is therefore located inside the printer. In a related art inkjet printer, related art ink cartridges containing black, yellow, cyan, and magenta ink are installed to a carriage and move with the carriage. 
     The related art ink cartridges (i.e., ink-filled ink cartridges) are normally stored in the package with the side mounted to the recording head, that is, the ink supply port side, down. The package is also not vertically inverted for store display purposes and shipping. Therefore, the related art ink cartridge is left with the ink supply port positioned on the bottom for long periods of time. 
     Accordingly, the related art ink cartridge has various problems and disadvantages. For example, but not by way of limitation, when the ink cartridge inside the package is removed from the package and installed to the recording head of the printer, there is no change in the orientation of the ink cartridge between when it is stored and when it is installed to the recording head. Thus, the ink inside the cartridge is used without being mixed, that is, with the ink separated into a high density ink layer and a low density ink layer. This happens particularly when the ink is, for example, a pigment ink or other type of ink in which such a density gradient forms easily. The resulting problem is that only high density ink near the ink supply port is consumed when the ink is first used, and consistent print density and quality cannot be achieved. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to solving at least the foregoing technical problems, and an object of the invention is to provide an ink cartridge storage structure and method whereby ink inside the ink cartridge is mixed as a result of changing the orientation of the ink cartridge by inverting the ink cartridge for installation to the recording apparatus, thereby providing consistent print density and quality when the ink is used. 
     To achieve these objects an ink cartridge storage structure according to the present invention has an ink-filled ink cartridge having an ink supply port installable to a recording head of a recording apparatus and an ink storage part for holding only ink, and packaging for storing the ink cartridge. The ink cartridge storage structure stores the ink cartridge in the packaging in an orientation different from the orientation in which the ink cartridge is used. 
     When the ink cartridge is then removed from the packaging and installed to the print head of the recording apparatus, the ink cartridge is inverted and the orientation thereof is thus changed. Thus inverting the ink cartridge mixes the ink in the ink cartridge when the cartridge is installed to the print head, and thus assures consistent print density and quality when the ink is used. 
     The ink cartridge is preferably stored in the packaging so that the ink supply port is positioned at the top. 
     Further preferably, the packaging is a vacuum pack or an individual box. 
     When thus comprised the ink inside the ink cartridge is mixed when the ink cartridge is removed from the vacuum pack or individual box in which it is stored and installed to the print head of the recording apparatus. 
     Yet further preferably, the ink storage part has an ink tank chamber and an ink end chamber. 
     Yet further preferably, the packaging has a hanging part with a hole therein. This enables the ink cartridge to be displayed for display or retail purposes in a desirable orientation by passing the hole in the hanging part over a peg or hangar, for example. 
     This assures that the ink cartridges are displayed with the ink supply port positioned at the top so that the ink inside the cartridge is mixed when the ink cartridge is removed from the packaging and installed to the head of the recording apparatus. 
     Yet further preferably, the packaging is packaging enabling storage in an external box for shipping. 
     This enables the ink cartridge packages to be stored in the external box and shipped with the ink supply ports positioned at the top. This assures that when an ink cartridge package is removed from the external box and inverted, the ink cartridge is also inverted and the ink inside the cartridge is mixed. 
     Yet further preferably, a label part identifying top and bottom parts of the packaging is formed on the packaging. 
     This makes it possible to assure that the ink cartridge is stored in the packaging in an attitude different from that in which the ink cartridge is used. 
     The ink in the ink cartridge is preferably a pigment ink. Even if the pigment in the ink then settles to the bottom part of the cartridge, the ink will be mixed in the cartridge when the ink cartridge is installed to the head. 
     An ink cartridge storage method according to the present invention has an ink-filled ink cartridge with an ink supply port installable to a recording head of a recording apparatus and an ink storage part for holding only ink, and packaging for storing the ink cartridge. The ink cartridge storage method stores the ink cartridge in the packaging so that the ink cartridge is held in an orientation different from the position in which the ink cartridge is used. 
     This storage method assures that there is a change in the attitude of the ink cartridge between when it is stored in the packaging and when the cartridge is installed for use. 
     The ink inside the cartridge is thus mixed when the ink cartridge is removed from the packaging and installed to the print head of the recording apparatus, thus assuring consistent print density and quality when the ink is used. 
     The ink cartridge is preferably stored in the packaging so that the ink supply port is positioned at the top. 
     Further preferably, the packaging is a vacuum pack or an individual box. 
     As with the storage structure described above, this assures that the ink inside the ink cartridge is mixed when the ink cartridge is removed from the vacuum pack or individual box in which it is stored and installed to the print head of the recording apparatus. 
     Yet further preferably, the ink inside the ink cartridge is a pigment ink. As with the storage structure described above, this assures that even if the ink pigment then settles to the bottom part of the cartridge, the ink will be mixed in the cartridge when the ink cartridge is installed to the head. 
     Yet further preferably, the ink cartridge is placed in the packaging with reference to a label part previously formed on the packaging. This makes it possible to assure that the ink cartridge is stored in the packaging in an attitude different from that in which the ink cartridge is used. 
     Additionally, within the ink cartridge, there is an ink path and an air path, configured to release air and ink, respectively, when the cartridge is installed to the recording head. The air path releases air into the ink path based on a negative pressure in the ink path. 
     The air path comprises a zigzag airflow channel configured to increase airflow resistance, a wide, recessed channel, and an air permeable film stretched over the air path to form an air permeable chamber in the cartridge. 
     Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are included to provide a further understanding of illustrative, non-limiting embodiments of the present invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the drawings. 
     FIG. 1 is an oblique exploded view of a complete ink cartridge according to an exemplary embodiment of the invention; 
     FIGS.  2 ( a ) and ( b ) are oblique external views of an ink cartridge according to an exemplary embodiment of the invention; 
     FIG. 3 is an oblique view from above showing the internal structure of an ink cartridge according to an exemplary embodiment of the invention; 
     FIG. 4 is an oblique view from below showing the internal structure of an ink cartridge according to an exemplary embodiment of the invention; 
     FIG. 5 is a front view showing the internal structure of an ink cartridge according to an exemplary embodiment of the invention; 
     FIG. 6 is a back view showing the internal structure of an ink cartridge according to an exemplary embodiment of the invention; 
     FIG. 7 is an enlarged section view showing the third ink storage chamber in an ink cartridge according to an exemplary embodiment of the invention; 
     FIG. 8 is an enlarged section showing the valve storage chamber of an ink cartridge according to an exemplary embodiment of the invention; 
     FIG. 9 is a front view of the connection of an ink cartridge to the cartridge holder according to an exemplary embodiment of the invention; 
     FIG. 10 is an exploded oblique view describing the ink cartridge storage structure and method of an exemplary embodiment of the invention; 
     FIG. 11 shows a method of filling packages with an ink cartridge and boxing the packages for shipping according to an exemplary embodiment of the present invention; and 
     FIGS.  12 ( a ) and ( b ) show an alternative package for storing an ink cartridge according to an exemplary of the present invention for shipping and display. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the illustrative, non-limiting, exemplary embodiments of an ink cartridge storage structure and method, examples of which are illustrated in the accompanying drawings. In the present invention, the terms are meant to have the definition provided in the specification, and are otherwise not limited by the specification. Further advantages of these and the stated objects reside in the details of construction and operation as more fully hereinafter described and claimed, reference being made to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. 
     The ink cartridge  1  is described first with reference to FIG. 1 to FIG.  10 . The ink cartridge  1  shown in FIGS.  2 ( a ) and ( b ) has a main case (i.e., bottom case)  2  with a substantially square flat shape open to one side, and a cover (i.e., top case)  3  for sealing the opening to the main case  2 . The inside of the ink cartridge  1  comprises an ink path and an air path, both of which are further described below. 
     This ink cartridge  1  has ink sealed therein, and is stored in a vacuum pack  91  with the ink supply port  4  positioned at the top, as shown in FIG.  10 . The vacuum pack  91  is, for example (but not by way of limitation), a transparent bag. After the cartridge is inserted to the bag, air is removed from the bag so that the cartridge  1  is stored in the vacuum pack  91 . By thus sealing the ink cartridge  1  in the vacuum pack  91 , air is prevented from entering the cartridge until the ink cartridge  1  is removed from the ink cartridge  1  so that the ink cartridge  1  can be distributed with assured ink deaeration and cleanliness levels. 
     As also illustrated in FIG. 10, after the ink cartridge  1  is enclosed in the vacuum pack  91 , it is then stored in the same orientation in an individual box  92  (i.e., with the ink supply port  4  up). This individual box  92  has a square body  92   a  that opens at the top, and a box top  92   b  for opening and closing the body  92   a , thus forming a substantially square-sided box made of paperboard. A label area  92   c  on the outside of the individual box  92  is used to display information such as (but not limited to) a company name. 
     When the ink cartridge  1  stored in this individual box  92  and vacuum pack  91  is removed and installed to a recording head  112  illustrated in FIG. 9, the ink cartridge  1  is inverted to position the ink supply port  4  on the bottom, which causes the ink inside the cartridge to mix. 
     Provided at the bottom part of the main case  2  are the ink supply port  4 , which is connectable to the ink supply needle  72  of the recording head  112  (both shown in FIG.  9 ), and a first opening part (open hole)  85  and second opening part  86  (both shown in FIG.  4  and FIG. 5) beside the ink supply port  4 . The ink supply port  4  communicates with the ink end chamber (differential pressure value chamber) described below, and the first opening part  85  communicates with the first ink storage chamber (ink tank)  11 . 
     As shown in FIG. 1, a substantially cylindrical seal member  200  made of rubber, for example, is fit inside the ink supply port  4 . A through-hole  200   a  open in the axial direction is disposed in the middle of this seal member  200 . A spring seat (valve body)  201  that opens and closes through-hole  200   a  in conjunction with insertion and removal of the ink supply needle  72  (as illustrated in FIG. 9) is disposed inside this ink supply port  4 , and a compression spring  202  urging the spring seat  201  to the seal member  200  is fit elastically to the spring seat  201 . 
     Engaging members  5  and  6  enabling mounting to and removal from the cartridge holder are disposed at the top side part of the main case  2 . As shown in FIG.  2 ( a ), a circuit board (IC chip)  7  is disposed at the bottom part of the one engaging member  5 , and a valve chamber  8  is disposed at the bottom part of the other engaging member  6  as shown in FIGS.  2 ( a ) and ( b ). 
     The circuit board  7  contains a writable memory device for storing ink-related information such as the color, type of ink (e.g., pigment or dye based ink), remaining ink volume, serial number, expiration date, and compatible models. 
     As shown in FIG. 8, the valve chamber  8  has an internal space open to the cartridge insertion side (bottom). A valve operating rod  70  and printer-side identification piece  73  (see FIG. 9) matching the ink cartridge  1  move within this internal space. The operating arm  66  of an identification block  87  rotated in conjunction with advancement and retraction of the valve operating rod  70  is housed in the top part of this internal space. An identification protrusion  68  for determining compatibility with the printer is disposed in the bottom part of this internal space. This identification protrusion  68  is located at a position where it can determine from the valve operating rod  70  of the cartridge holder  71  (see FIG. 9) whether the ink cartridge is compatible with the cartridge holder before the printer-side ink supply needle  72  (see FIG. 9) penetrates the ink supply port  4  (i.e., before the air valve described below opens) 
     A through-hole  60  is disposed in chamber wall  8   a  of the valve chamber  8  (air chamber  501 ) as an air hole that opens and closes in conjunction with opening and closing of the air valve  601 . The operating arm  66  is disposed on one side of the opening to through-hole  60  and the air valve  601  is disposed at the opening on the other side. The operating arm  66  has an operating part  66   b  for pressing pressurization film (stretch film)  61 , and is fixed to the main case  2  at an intervening pivot point  66   a  such that the operating arm  66  proceeds diagonally above into the path of the valve operating rod  70 . 
     The pressurization film  61  is fixed to the chamber wall  8   a  so as to occlude the through-hole  60 , and is entirely formed from a rubber or other elastic sheet material. The internal space formed between this pressurization film  61  and the open edge of the through-hole  60  is open to a through-hole  67  communicating with the first ink storage chamber (ink tank)  11  (both shown in FIG. 5) 
     The air valve  601  has a valve element  65  for opening and closing the through-hole  60 , and an elastic member (leaf spring)  62  constantly urging the valve element  65  toward the opening edge of the through-hole  60 . A through-hole  62   b  is disposed in the top end part of the elastic member  62 , and a projection  64  inserted to this through-hole  62   b  restricts (guides) movement. The bottom end part is fixed to the main case  2  by way of protrusion  63 . 
     Additionally, FIG. 1 illustrates an identification label  88  applied to the top of the main case  2  corresponding to the identification block  87 , a film  89  sealing the ink supply port  4  (through-hole  200   a ), and a film  90  sealing the first opening part  85  and second opening part  86 . 
     The ink path and the air path inside this main case  2  are described below with reference to FIG. 1 to FIG.  10 . 
     Ink Path 
     As shown in FIG. 1 an internal space is formed in the ink cartridge  1  by bonding top case  3  to the front of the main case  2  through intervening internal films (impermeable films)  56 ,  502 , and by bonding protective label  83  to the back side of the main case  2  through intervening impermeable external film  57 . 
     As shown in FIG. 9, a partition wall  10  disposed so that the end at the ink supply port is slightly lower and segments this internal space into top and bottom parts as shown in FIG. 3 to FIG.  5 . The bottom part of this internal space is the first ink storage chamber  11  that is open to the air when connected to the recording head  112 . 
     As illustrated in FIGS. 3-5, two intermediate walls  300 ,  301  are disposed at different elevations inside the first ink storage chamber  11 . The one intermediate wall  300  is disposed with a specific gap to one side wall of the first ink storage chamber  11 . The other intermediate wall  301  is on the ink supply port side of the intermediate wall  300  opposite the bottom wall of the first ink storage chamber  11 . This intermediate wall  301  divides the first ink storage chamber  11  into two parallel spaces  11   a ,  11   b  in the ink injection direction (vertically). A through-hole  301   a  is disposed in this intermediate wall  301  coaxially to the first opening part  85 . 
     The top part of this internal space is segmented by a frame part  14 , of which the bottom part is partition wall  10 . The space inside this frame part  14  forms a part of the ink end chamber connecting to the recording head  112 . The front side of this ink end chamber is divided into left and right parts by a vertical wall  15  having a communication opening  15   a  formed therein. One side of the internal space thus segmented by vertical wall  15  is the second ink storage chamber  16 , and the other side is a third ink storage chamber  17 . 
     A communication path  18  communicating with the first ink storage chamber  11  is connected to the second ink storage chamber  16 . This communication path  18  has top and bottom openings  18   a ,  18   b . The communication path  18  is formed by a vertically extending channel  18   c  (see FIG. 6) open at the back of the main case  2  and an impermeable film (external film  57  as illustrated in FIG. 1) covering and sealing this channel  18   c . A partition wall  19  with two vertically arranged openings  19   a ,  19   b  communicating with the inside of first ink storage chamber  11  is disposed at the upstream side of the communication path  18 . One opening  19   a  is located at a position open to the bottom part of the first ink storage chamber  11 , and the other opening  19   b  is located at a position open to the top part of the first ink storage chamber  11 . 
     A differential pressure valve chamber  33  (see FIG. 6) for holding the differential pressure valve  52  (membrane valve) shown in FIG. 7, and a filter chamber  34  (see FIG. 5) for holding the filter  55  (felt filter) shown in FIG. 7 are formed in the third ink storage chamber  17  by a longitudinal partition wall  22  and an annular partition wall  24 . Through-holes  25   a  for conducting ink passed by the filter  55  from the filter chamber  34  to the differential pressure valve chamber  33  are disposed in partition wall  25 . 
     A partition wall  26  with a communication opening  26   a  between the partition wall  26  and partition wall  10  is disposed at the bottom of partition wall  24 , and a partition wall  27  with a communication opening  27   a  between it and the frame part  14  is disposed at the side of partition wall  24 . A vertically extending communication path  28  open to communication opening  27   a  is formed between partition wall  27  and frame part  14 . A through-hole  29  communicating with the filter chamber  34  through opening  24   a  and area  31  is formed contiguously to this communication path  28 . 
     This through-hole  29  is formed by a partition wall (annular wall)  30  contiguous to partition wall  27 . 
     Area  31  is formed by partition walls  22 ,  24 ,  30 , and  30   a  (see FIG.  6 ). This area  31  is formed so that it is deep at the end toward the side of main case  2  (the part communicating with through-hole  29 ) and shallow at the other end (the part communicating with filter chamber  34 ) 
     As shown in FIG. 7 an elastomer or other type of membrane valve  52  is housed in differential pressure valve chamber  33  as an elastically deformable differential pressure valve. This membrane valve  52  has a through-hole  52   c , is urged to the filter chamber side by a coil compression spring  50 , and the perimeter thereof is fixed through a thick annular lip  52   a  to the main case  2  by ultrasonic welding. One end of the coil compression spring  50  is supported by the spring seat  52   b  of membrane valve  52 , and the other end is supported by the spring seat  203  inside the differential pressure valve chamber  33 . 
     A frame part  54  is also formed integrally to the thick lip part  52   a  of the membrane valve  52 . 
     As also shown in FIG. 7 filter  55  is placed in filter chamber  34  to pass the ink and capture any dust or foreign matter in the ink. The opening to this filter chamber  34  is sealed by internal film  56 , and the opening to the differential pressure valve chamber  33  is sealed by the external film  57 . 
     When the pressure inside ink supply port  4  drops, membrane valve  52  separates from valve seat  25   b  in resistance to the urging force of the coil compression spring  50  and through-hole  52   c  opens. Ink passed by the filter  55  therefore passes through-hole  52   c , and flows to the ink supply port  4  through the path formed by channel  35 . When the pressure inside ink supply port  4  rises to a specific level, the membrane valve  52  is seated to the valve seat  25   b  by the force of coil compression spring  50 , and ink flow is thereby stopped. Ink is supplied to the ink supply port  4  while maintaining a specific negative pressure by repeating this operation. 
     Air Path 
     As shown in FIG. 6, a zigzag channel  36  for increasing flow resistance, a wide recessed channel  37  (shaded in the figure) open to the air, and a flat, substantially square cavity  38  (space) leading to the first ink storage chamber  11  (see FIG. 5) are disposed on the back side of the main case  2 . A frame part  39  and ribs  40  are disposed inside the cavity  38 , and an air permeable film  84  (see FIG. 1) is stretched over the aforementioned elements to form an air permeable chamber. A through-hole  41  formed in the bottom (wall part) of the cavity  38  communicates with a long narrow region  43  formed by a partition wall  42  in second ink storage chamber  16  (see FIG.  5 ). 
     Region  43  communicates through a through-hole  44  with communication channel  45  formed by partition wall  603  and with air chamber  501  (see FIG. 8) through a through-hole  46  open to the communication channel  45 . The open part of this air chamber  501  is sealed by the impermeable internal film  502  shown in FIG.  1 . 
     When an ink cartridge  1  is loaded to the cartridge holder  71  as shown in FIG. 9, the valve operating rod  70  of cartridge holder  71  contacts the operating arm  66  shown in FIG. 8, thus moving the operating part  66   b  (pressurization film  61 ) to the valve element side. The valve element  65  thus separates from the open edge of through-hole  60 , and the first ink storage chamber  11  shown in FIG. 5 opens to the cavity  38  shown in FIG. 6 (i.e., to the air) by way of through-holes  67 ,  60 , and  46 , communication channel  45 , through-hole  44 , region  43 , and through-hole  41 . The valve element  201  in ink supply port  4  is also opened by inserting the ink supply needle  72 . 
     When valve element  201  in ink supply port  4  opens, ink is consumed by the recording head  112 , and the pressure inside ink supply port  4  drops below a specified level, membrane valve  52  inside differential pressure valve chamber  33  (see FIG. 7) opens (membrane valve  52  closes when the pressure in ink supply port  4  rises to a specified level), and ink inside the differential pressure valve chamber  33  flows through ink supply port  4  to the recording head  112 . 
     As the recording head  112  continues to consume ink, ink from the first ink storage chamber  11  flows through the communication path  18  shown in FIG. 4 to the second ink storage chamber  16 . 
     As ink is consumed, air also flows in from through-hole  67  in communication with the air (see FIG.  5 ), and the ink level in the first ink storage chamber  11  drops. When ink is consumed to the point where the ink level reaches opening  19   a , ink flows together with air from the first ink storage chamber  11  (which is open to the air through through-hole  67  when ink is supplied) through the valve chamber  8  into the second ink storage chamber  16 . Because buoyancy causes the air bubble to rise, only the ink flows through communication opening  15   a  in the bottom part of vertical wall  15  and into third ink storage chamber  17 , passes from third ink storage chamber  17  through communication opening  26   a  in partition wall  26  and rises in communication path  28 , and then flows from communication path  28  through area  31  and opening  24   a  into the top part of the filter chamber  34 . 
     Ink inside the filter chamber  34  then passes filter  55  shown in FIG.  7  and flows from through-hole  25   a  to differential pressure valve chamber  33 , and after passing through-hole  52   c  of membrane valve  52  separated from valve seat  25   b , drops through channel  35  shown in FIG. 6, and flows into the ink supply port  4 . 
     Ink is thus supplied from the ink cartridge  1  to the recording head  112 . 
     If a different type of ink cartridge  1  is loaded to the cartridge holder  71 , identification protrusion  68  (shown in FIG. 8) contacts cartridge holder identification piece  73  (see FIG. 9) before the ink supply port  4  reaches the ink supply needle  72 , and thus prevents entry of the valve operating rod  70 . Problems caused by loading a different type of ink cartridge can thus be prevented. Furthermore, because the valve operating rod  70  does not reach the operating arm  66  at this time, valve element  65  is held closed and evaporation of the solvent from ink in the first ink storage chamber  11  is prevented. 
     When the ink cartridge  1  is removed from the cartridge holder  71  loading position, operating arm  66  loses the support of valve operating rod  70  and thus returns elastically. Valve element  65  also returns in conjunction with operating arm  66 , thus closing the through-hole  60  and cutting off communication between cavity  38  and first ink storage chamber  11 . 
     A storage method for ink cartridges  1  according to the present invention is described next with reference to FIG.  10 . It should be noted that after ink is injected to the ink cartridge  1 , the ink supply port  4  is sealed with film  89  and first opening part  85  and second opening part  86  are sealed (airtight) by film  90 . 
     An ink cartridge  1  according to the present invention is stored as shown in FIG. 10 by first storing the ink cartridge  1  inside vacuum pack  91  so that the ink supply port  4  is to the top, and then storing this assembly, that is, the ink cartridge sealed inside the vacuum pack, inside an individual box  92  so that the ink supply port  4  is still positioned at the top. The ink cartridge  1  is inserted to the individual box  92  with reference to the label area  92   c . It is thus possible to reliably store the ink cartridge  1  inside the individual box  92   50  that the ink supply port  4  remains positioned at the top. 
     It should be noted that while the label area  92   c  typically contains such text or numbers as the name and address of the manufacturer or a product code, other text or symbols used especially to aid correct positioning of the ink cartridge  1  in the box could also be used. 
     When an ink cartridge  1  (thus packaged is removed and loaded to the recording head  112 , the ink cartridge  1  is inverted and the orientation thereof thus changed. That is, fitting the ink cartridge  1  to the recording head  112  causes the ink supply port  4  to move from this top storage position to the bottom. This also positions the ink end chamber (including third ink storage chamber  17  and second ink storage chamber  16 ) at the top and the first ink storage chamber  11  at the bottom. Ink from the high density ink layer formed at the bottom of the ink inside the chambers thus flows to the top, ink from the low density ink layer at the top flows to the bottom, and the ink inside the chambers is thus mixed. 
     When ink supply to the recording head  112  then starts, ink inside the ink tank chamber (differential pressure valve chamber  33 ) flows through through-hole  52   c  when the differential pressure valve (membrane valve)  52  opens, passes channel  35 , and enters the ink supply port  4 . 
     In addition, ink inside the first ink storage chamber  11  flows from opening  19   a  through opening  18   a  and into communication path  18 , and from opening  19   b  through opening  18   a  and into the communication path  18 . Ink flowing into the communication path  18  thus merges and mixes, rises inside the communication path  18  and flows toward the second ink storage chamber  16 . 
     Because openings  19   a  and  18   a  are at the same height, ink is conducted from the first ink storage chamber  11  by communication path  18  to the second ink storage chamber  16  with no residual ink left in the first ink storage chamber  11 . 
     Next, ink flowing from first ink storage chamber  11  through communication path  18  into the second ink storage chamber  16  merges and mixes with ink in the second ink storage chamber  16 . This mixed ink then passes communication opening  15   a  of vertical wall  15  as it flows into and mixes in the third ink storage chamber  17 , and then passes communication opening  26   a  of partition wall  26 . The ink passed through communication opening  26   a  of partition wall  26  then passes opening  27   a  in partition wall  27 , rises through communication path  28 , and flows from opening  24   a  through filter chamber  34  into the differential pressure valve chamber  33 . 
     Ink inside ink cartridge  1  stored in individual box  92  according to the present invention is thus coincidentally mixed when the ink cartridge  1  is removed and installed to the recording head  112 . Consistent print density and quality can thus be assured when the ink is used. This is particularly beneficial when the ink is a pigment ink, for example, susceptible to a density gradient. 
     When shipping numerous individual boxes  92  each containing an ink cartridge  1 , the individual boxes  92  are placed in a shipping box  93  as shown in FIG. 11 so that the ink supply ports  4  are positioned up. This assures that when an individual box  92  is removed from the shipping box  93  and inverted, the ink cartridge  1  inside the individual box  92  is also inverted and the ink inside the ink cartridge  1  is mixed. 
     It will also be noted that while the individual box  92  is described above as being square, the present invention shall not be so limited. The individual box  96  could, for example, have a tab  95  with a hole  95   a  as shown in FIG.  12 . In this case the hole  95   a  in the tab  95  could be passed over a hanger  98  on a wall  97  or other display stand, for example, for display purposes in a display or retail store. In this case the ink cartridge  1  can be reliably displayed with the ink supply port  4  positioned at the top. 
     The ink cartridge of the present invention has been described with the inside of the cartridge segmented into top and bottom internal chambers, but the invention shall not be so limited and can be applied to an ink cartridge having only a single internal chamber. 
     The above-described exemplary embodiment and its variants as would be understood by one skilled in the art have various advantages. For example, but not by way of limitation, the ink cartridge storage structure and method of the present invention thus enables ink inside the cartridge to be mixed coincidentally with inversion of the ink cartridge for installation to the cartridge holder so that consistent print density and quality can be assured when the ink is used. 
     Although the present invention has been described in connection with the preferred embodiments thereof with reference to the accompanying drawings, it is to be noted that various changes and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as defined by the appended claims, unless they depart therefrom.