Patent Abstract:
An ink jet recording head for ejecting, through an ink ejection outlet, ink introduced through an ink supply port includes a first ink flow path in fluid communication with the ink supply port; a second ink flow path which is branched from the first ink flow path at a branch portion and which is in fluid communication with the ink ejection outlet; and a third ink flow path for fluid communication between the branch portion and an outside.

Full Description:
FIELD OF THE INVENTION AND RELATED ART 
       [0001]    The present invention relates to an ink jet recording head capable of jetting ink, and an ink jet recording apparatus employing an ink jet recording head. Not only is the present invention applicable to an ordinary ink jet printer, but also, a copying machine, a facsimile machine having a communicating system, a wordprocessor having a printing portion, a multifunction recording apparatus capable of performing two or more of the functions of the preceding machines. 
         [0002]    An ink container remains stationary during distribution, during a period in which a recording apparatus in which an ink container is held is not used, or the like situations. If an ink container which contains pigment ink is left stationary for a long period of time, the ink in the container sometimes becomes nonuniform in pigment concentration, in terms of the vertical direction, because the pigment in the ink has a tendency to agglomerate and sediment. Thus, if the pigment ink in an ink container is supplied from the ink container to an ink jet recording head while remaining in the above-mentioned condition, ink droplets jetted from the recording head are nonuniform in pigment concentration, making it possible that the image forming apparatus will yield inferior images. 
         [0003]    One of the conventional solutions (solution in accordance with prior art) to the above-mentioned problem is as follows: Before a user mounts an ink container into a recording apparatus, the user is to manually shake the ink container in order to make the ink in the ink container uniform in pigment concentration by breaking up the agglomeration of pigment. 
         [0004]    Japanese Laid-open Patent Application 2004-216761 discloses a solution to the above-mentioned problem, which is different from the preceding solution. In this case, a recording apparatus is of the serial scan type, and an ink container is mounted on the carriage of the recording apparatus. Thus, the pigment ink in the ink container is stirred by utilizing the inertia which occurs as the carriage is moved in the manner of scanning recording medium. 
         [0005]    Further, if a recording apparatus in which an ink container is mounted is left unused for a long time after its usage, it is possible that the phenomenon that pigment in ink sediments will occur even in the ink passage which connects the ink container and ink jet recording head. As one of the solutions to this problem, some conventional ink jet recording apparatuses are designed to periodically carry out a recovery operation, that is, an operation for discharging the ink in the ink passage. 
         [0006]      FIG. 23  shows one of the conventional ink jet recording cartridges  100 , which is an integrated combination of an ink container and an ink jet recording head. Although the cartridge  100  is provided with multiple ink passages, the number of which corresponds to the number of different colors in which the cartridge  100  is capable of printing,  FIG. 23 , which is a sectional view of the cartridge  100 , shows only one ink passage. For descriptive convenience, the section of the ink passage, which extends from the ink inlet opening  105  to a bend  150 , will be called section O, and the section of the ink passage, which extends from the bend  150  to bend  160 , will be called section P. Further, the section of the ink passage, which extends from the bend  160  to a liquid chamber  108  will be called section Q. 
         [0007]    The cartridge  100  has an internal ink storage space  154 , and an ink passage  106 . The ink passage  106  outwardly extends from the internal ink storage space  154 , and is positioned so that when the cartridge  100  is in use, the ink passage  106  extends vertically downward. The ink intake opening  105  of the ink passage  106 , which is the interfacial portion between the ink storage space  154  and ink passage  106 , is fitted with a filter  104 . Further, a substantial portion of the ink storage space  154  is filled with an ink absorbing member  103 , which absorbs and internally retains pigment ink  102 . The ink passage  106  is shaped like a crank, having two bends, which are the bends  150  and  160 , at which the ink passage  106  bends 90 degrees. The ink passage  106  is in connection with the liquid chamber  108 , which is on the inward side of a heat radiating member  109 , with a joint rubber  107  fitted around the joint between the ink passage  106  and liquid chamber  108 . The heat radiating member  109  is provided with a heater board  110 , which is fixed to the heat radiating member  109  with the use of unshown adhesive. The heater board  110  is provided with driving elements and ink jetting orifices, which are not shown. The heater board  110  and heat radiating member  109  make up an ink jet recording head  151 . 
         [0008]    The pigment ink  102  is supplied from the ink absorbing member  103  to the liquid chamber  108  through the ink intake opening  150  and ink passage  106 , and is temporarily stored in the liquid chamber  108 . The recording head  151  jets the pigment ink  102  from the ink jetting orifices by applying the energy generated by the driving elements, to the pigment ink. As the pigment ink  102  is supplied to the liquid chamber  108 , the ambient air enters the ink storage space  154  of the cartridge  100  to compensate for the volumetric loss which could occur to the ink storage space  154  as the pigment ink  102  is supplied from the ink absorbing member  103 , were it not for the entry of the ambient air into the ink storage  154 . 
         [0009]    Normally, as the cartridge  100  is left unused for a certain length of time, the pigment ink in the ink passage  106  and liquid chamber  108  becomes nonuniform in pigment concentration, creating such a pigment concentration gradient that the pigment concentration is lower on top side in terms of the vertical direction, and higher in the bottom portion. Therefore, after the cartridge  100  is left unused for a certain length of time, the pigment concentration gradient of the pigment ink  102  in these sections is such that the section O of the ink passage is lower in pigment concentration and the section Q of the ink passage is higher in pigment concentration. Further, in each of the sections O and Q, the top side is lower in pigment concentration and the bottom side is higher in pigment concentration. The pigment concentration gradient (which hereafter may be referred to as “ink density”) of the ink in the horizontal section P, or the section which connects the sections O and Q, is such that the ink density gradually reduces from the bend  150 , or the border between the sections O and Q, toward the bend  160 , or the border between the section Q and P. As for the density of the body of ink in the section P, which is measured at a given cross-sectional plane of the section P, it is lower in the top side, in terms of the vertical direction, and higher in the bottom side, as it is in the sections O and Q. The reason why the ink density gradient (pigment concentration gradient) changes as described above with the elapse of time is that the pigment is easily affected by gravity, and therefore, is likely to sediment. If the ink in the above described condition is supplied to the recording head  151  to form images, images which are nonuniform in density are formed. 
         [0010]    The manner in which the pigment in ink sediments is affected by the type of pigment and the solvent density. In a cartridge which is holding such ink that is high in pigment sedimentation speed, the pigment concentration is rather high in the liquid chamber  108 . Further, in the liquid chamber  108 , the portion directly under the ink passage  106  is different in ink density (pigment concentration) from the peripheries thereof; in other words, even in the horizontal direction, the pigment ink is nonuniform in density. In some cases, there is a difference of no less than two levels, in terms of an ordinary ink density measurement scale, between the portion of the ink, which is highest in density, and the portion of the ink, which is lowest in density. 
         [0011]    Therefore, the abovementioned recovery operation is carried out at a preset interval with the use of a recovery cap with which the recording apparatus is provided. This recovery operation is an operation in which the bubbles and high viscosity ink (ink having increased in viscosity while recording head is left unused) in the recording head  151  are discharged to maintain the ink jetting performance of the recording head  151  at a preset level or higher, and also, to remove the portions of the body of ink in the recording head  151 , which have become excessively deviant in density. In the recovery operation, the recovery cap is pressed upon the recording head  151  of the cartridge  100  to hermetically seal the space surrounded by the recovery cap and recording head  151 , and then a suction pump connected to the recovery cap is driven to suction out the ink in the ink passage  106  through the ink jetting orifices of the recording head  151 . In this recovery operation, the body of ink, which is on the downstream side of the filter  104 , is discharged. 
         [0012]    As described above, if it is only the recovery operation that is employed to abolish the nonuniformity in the ink density in the ink passage  106 , the recovery operation must be very frequently carried out. Further, in the recovery operation, the body of ink, which is significantly nonuniform in density, is removed by discharging the entire body of ink, which is in the section of the ink passage  104 , which is on the downstream side of the filter  104 . Therefore, the amount by which ink is removed by the recovery operation (amount by which ink is wasted) is substantial, and accordingly, the recording apparatus must be provided with a larger waste ink absorbing member, that is, a waste ink absorbing member, the capacity of which matches the substantial amount by which the ink is wasted. Thus, it is possible that the employment of this method of abolishing the abovementioned excessive nonuniformity in the ink density by the recovery operation will require the main assembly of the recording apparatus to be increased in size. 
         [0013]    The cartridge  100 , which is a multicolor cartridge, that is, a cartridge capable of forming multicolor images, is more complicated in the shape of the ink passages  106  than a monochromatic, that is, a cartridge dedicated to monochromatic printing. Therefore, the cartridge  100  is greater in the number of sections of the ink passage  106 , which are affected by the pigment sedimentation, being therefore greater in the frequency with which the recovery operation has to be carried out, than a monochromatic cartridge. Moreover, the ink passages of the cartridge  100  are generally longer than the ink passage of a monochromatic cartridge, and therefore, the cartridge  100  is greater in the amount by which ink is discharged in the recovery operation than a monochromatic cartridge. 
       SUMMARY OF THE INVENTION 
       [0014]    The present invention was made in consideration of the above described reasons, and its primary object is to provide an ink jet recording head and an ink jet recording apparatus, which are capable of efficiently removing the sedimented ink ingredients. 
         [0015]    According to an aspect of the present invention, there is provided an ink jet recording head for ejecting, through an ink ejection outlet, ink introduced through an ink supply port, comprising a first ink flow path in fluid communication with the ink supply port; a second ink flow path which is branched from said first ink flow path at a branch portion and which is in fluid communication with said ink ejection outlet; and a third ink flow path for fluid communication between said branch portion and an outside. 
         [0016]    According to the present invention, the ink passage is structured so that the ingredients of pigment ink primarily sediment into the third section of the ink passage through the first section of the ink passage, and the body of ink in the third section of the ink passage, that is, the body of ink, into which the ingredients of pigment ink have sedimented, is removed from the third section. Therefore, the body of ink, into which the ingredients of pigment ink have sedimented, can be efficiently discharged. Thus, the present invention can reduce the amount by which ink must be discharged to eliminate the sedimented ink ingredients. Therefore, not only can the present invention reduce the operational cost of an ink jet recording apparatus, but also, can reduce in volume the waste ink absorbing member for absorbing the discharged ink, making it possible to reduce in size an ink jet recording apparatus. 
         [0017]    These and other objects, features, and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a sectional view of the ink jet recording cartridge, in the first embodiment, which is an integral combination of a recording head and an ink container (or containers). 
           [0019]      FIG. 2  is an enlarged sectional view of the essential portions of the cartridge shown in  FIG. 1 . 
           [0020]      FIG. 3  is a perspective view of a typical ink jet recording apparatus in which the cartridge shown in  FIG. 1  is mountable. 
           [0021]      FIG. 4  is a sectional view of the cartridge shown in  FIG. 1 , and the recovery cap for the cartridge. 
           [0022]      FIG. 5  is a sectional view of the recovery caps for the cartridge shown in  FIG. 1 , and the essential portions of the cartridge, which are involved in the recovery operation, showing one of the steps in the recovery operation. 
           [0023]      FIG. 6  is an enlarged sectional view of the valve mechanism shown in  FIG. 5 . 
           [0024]      FIG. 7  is a sectional view of the recovery cap for the cartridge shown in  FIG. 1 , and the essential portions of the recording head of the cartridge, which are involved in the recovery operation, showing another step in the recovery operation. 
           [0025]      FIG. 8  is a sectional view of the recovery cap for the cartridge shown in  FIG. 1 , and the essential portions of the cartridge, which are involved in the recovery operation, showing the state of the cartridge, in which the two recovery caps are kept pressed on the cartridge. 
           [0026]      FIG. 9  is a sectional view of the ink jet recording cartridge, in the second embodiment, which is an integral combination of a recording head and an ink container (or containers). 
           [0027]      FIG. 10  is a sectional view of the cartridge and recovery cap shown in  FIG. 9 . 
           [0028]      FIG. 11  is a sectional view of the recovery cap for the cartridge shown in  FIG. 9 , and the essential portions (ink passage) of the cartridge, which are involved in the recovery operation, showing one of the steps in the recovery operation. 
           [0029]      FIG. 12  is a sectional view of the recovery cap for the cartridge shown in  FIG. 9 , and the essential portions of the cartridge, which are involved in the recovery operation, showing another step in the recovery operation. 
           [0030]      FIG. 13  is a sectional view of the ink jet recording cartridge, in the third embodiment, which is an integral combination of a recording head and an ink container (or containers). 
           [0031]      FIG. 14  is a sectional view of the cartridge and recovery cap shown in  FIG. 13 . 
           [0032]      FIG. 15  is a sectional view of the recovery cap for the cartridge shown in  FIG. 13 , and the essential portions (ink passage) of the cartridge, which are involved in the recovery operation, showing one of the steps in the recovery operation. 
           [0033]      FIG. 16  is a sectional view of the recovery cap for the cartridge shown in  FIG. 13 , and the essential portions of the cartridge, which are involved in the recovery operation, showing another step in the recovery operation. 
           [0034]      FIG. 17  is a sectional view of the ink jet recording cartridge, which is an integral combination of a recording head and an ink container (or ink containers), and the recovery cap, in the fourth embodiment. 
           [0035]      FIG. 18  is an enlarged sectional view of the point of the ink passage, at which the ink passage branches, and the adjacencies of this branching point. 
           [0036]      FIG. 19  is a view of the ink passage shown in  FIG. 18 , as seen from the direction indicated by an arrow mark F in  FIG. 18 . 
           [0037]      FIG. 20  is a sectional view of the ink jet recording cartridge, which is an integral combination of a recording head and an ink container (or ink containers), and the recovery cap, in the fifth embodiment. 
           [0038]      FIG. 21  is a view of the ink passage shown in  FIG. 20 , as seen from the direction indicated by an arrow mark I in  FIG. 20 . 
           [0039]      FIG. 22  is a schematic sectional view of an ink jet recording head, and an ink container separable from the ink jet recording head, showing their structures which make them separable. 
           [0040]      FIG. 23  is a sectional view of an ink jet recording cartridge, in accordance with the prior art, which is an integral combination of a recording head and an ink container (or ink containers). 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0041]    Hereinafter, the preferred embodiments of the present invention will be described with reference to the appended drawings. 
       Embodiment 1 
       [0042]      FIG. 1  shows an ink jet recording cartridge  1 , in the first embodiment of the present invention, which is an integral combination of an ink jet recording head and one or more ink containers. The ink jet cartridge  1  in this embodiment has: an internal ink storage space  54 ; an air vent  11  which connects the internal ink storage space  54  and the ambient air; an ink passage which extends outward from the ink storage space  54 ; and an ink jet recording head  51 . The ink passage is provided with an ink intake opening  5 , which leads to the ink storage space  54 . The ink intake opening  5  is provided with a filter  4 . There is an ink absorbing member  3  in the ink storage space  54 , and the ink absorbing member  3  absorbs and internally holds pigment ink  2 . 
         [0043]    In this embodiment, the ink passage has: a section  6  (first ink passage section), which is in connection with the abovementioned ink intake opening  5 ; a section  6 B (section on ink jet recording head side: second section) which branches from the section  6  at a branching point R, and connects to the abovementioned ink jet recording head  51 ; a section  6 A (section on ink ingredient sediment recovery means side: third section), which leads outward. When the cartridge  1  is in the operational attitude (in this embodiment, “operational attitude” is an attitude in which cartridge  1  is after being mounted so that direction in which ink is jetted from its ink jetting orifices is vertically downward), the section  6 A extends vertically downward from the branching point R, and the section  6 B horizontally extends from the branching point R, bends 90 degrees at a bend  50 , and extends vertically downward to the liquid chamber  8 . The liquid chamber  8  is on the inward side of a heat radiating member  9 , which is in connection with the cartridge  1 , with the presence of a joint rubber  7  between the cartridge  1  and heat radiating member  9 . The heat radiating member  9  is provided with a heater board  10 , which is one of the components of the ink jet recording head  51 . The ink jet recording head  51  in this embodiment is made up of the heat radiating member  9  and heater board  10 . The section  6 B of the ink passage leads into the liquid chamber  8  through the internal passage of the joint rubber  7 . The bottom end of the section  6 A is sealed by a valve mechanism  53  to prevent ink from leaking therefrom. The valve mechanism  53  is made up of: a ball  15 ; a coil spring  16 ; and a ball seat  17  upon which the ball  15  is kept pressed to hermetically seal the interface between the ball  15  and ball seat  17 . 
         [0044]    Incidentally, in this embodiment, the ball seat  17  is an integral part of a plug  18 ; the two components are integrally formed by two-color injection molding. The ball seat  17  has a through hole, the axial line of which coincides with the axial line of a through whole S with which the plug  18  is provided. The plug  18  is formed of the same substance as the substance of which the cartridge  1  is formed. The plug  18  is attached to the cartridge  1  by ultrasonic welding, with the presence of no gap between the cartridge  1  and plug  18 . 
         [0045]      FIG. 2  shows the condition in which the bodies of ink in the sections of ink passage in areas A, B, and C of the cartridge  1  will be after the cartridge  1  is left unused (undisturbed) for a certain length of time after being mounted into the main assembly of the recording apparatus. The area A includes the section  6  of the ink passage, which extends from the ink intake opening  5  to the branching point, and the section  6 A which extends from the branching point to the outlet. The area B is the section of the ink passage which extends from the branching point to the bend  50 . The area C includes the section  6 B of the ink passage, which extends from the bend  50  to the liquid chamber  8 , and the liquid chamber  8 . The pigment concentration gradient in the area A is such that the pigment concentration is lower (low concentration) on the top side in terms of the vertical direction, and higher (high concentration) on the bottom side. The pigment concentration gradient of the ink in the area C is the same as that in the area A. In the area B, which is the horizontal area which connects the areas A and C, the pigment concentration gradient is such that the pigment concentration gradually reduces from the branching point R toward the bend  50 , that is, from the area A toward the area C. Further, the pigment concentration gradient of the body of ink in the area B, which is measured at a given plane perpendicular to the axial line of the ink passage, is the same as those in the areas A and C, that is, lower (low concentration) on the top side in the vertical direction, and higher (high concentration) on the bottom side. A pigment concentration gradient of ink, such as the above described one, occurs because the pigment sedimentation is greatly affected by gravity. 
         [0046]    Referring to  FIG. 1 , in this embodiment, the ink passage section  6  branches at the branching point R into two passages, that is, the passage (section)  6 A, and the passage (section)  6 B which is perpendicular to the passage (section)  6 A. The section  6 A extends vertically downward from the branching point R, making it easier for the pigment in the ink in the section to sediment. The section  6 A is provided with the valve mechanism  53 , which is made up of the ball  15 , coil spring  16 , and ball seat  17 , as described above. 
         [0047]      FIG. 3  is a perspective view of a recording apparatus  70  in which the cartridge  1  is mountable, and shows the general structure of the recording apparatus  70 . The recording apparatus  70  is a recording apparatus of the serial scan type, which has a pair of guiding shafts  71  and  72 , and a carriage  73  on which the cartridge  1  is mountable. The carriage  73  is supported by the pair of guiding shaft  71  and  72 , being enabled to move in the primary scan direction indicated by an arrow mark A. The carriage  73  is reciprocally moved in the abovementioned primary scan direction by a driving force transmitting mechanism made up of a carriage motor, a belt for transmitting the driving force of the carriage motor, etc. A sheet of paper P as a medium on which recording made is inserted into the main assembly of the recording apparatus  70  through a recording medium inlet  75  located on the front side of the apparatus main assembly, and is conveyed by a recording medium conveyance roller  76  through the apparatus main assembly in the secondary scan direction indicated by an arrow mark B. Before the leading edge of the paper P reaches the cartridge  1  on the carriage  73 , the paper P is curved so that the leading portion of the paper P move in the opposite direction from the direction in which the paper P is inserted into the apparatus main assembly. 
         [0048]    An image is formed in sections on the paper P by alternately repeating the recording operation and conveying operation. In the recording operation, the recording head  1  is made to jet ink toward the printing area of the paper P on a platen  7 , while moving the carriage  1 , on which the cartridge  1  is borne, in the primary scan direction. In the conveying operation, the paper P is conveyed in the secondary scan direction by a distance equal to the width of each section of the image which is being recorded each time the carriage  1  is moved in the primary direction during the recording operation. The recording apparatus  70  is provided with a recovery cap mechanism  52 , which is positioned at the left end of the moving range of the carriage  73 , shown in  FIG. 3 , so that when the carriage  73  is at the left end of its moving range, the recovery cap mechanism opposes the surface of the recording head  51  of the cartridge  1  on the carriage  73 , which has the opening of each ink jetting orifice. 
         [0049]    The pigment ink  2  is supplied from the ink absorbing member  3  to the ink chamber  8  through the ink intake opening  5  and ink passage sections  6  and  6 B, and is temporarily stored in the ink chamber  8 . The recording head  51  jets the pigment ink  2  through its ink jetting orifices by applying to the pigment ink the ink jetting energy which it generates by its driving elements. The ink jetting energy can be supplied with the use of an electrothermal transducer (heater), a piezoelectric element, or the like. When an electro-thermal transducer is employed, the ink is made to boil by the heat generated by the electro-thermal transducer, and the energy generated by the boiling of the ink is used to jet the ink from the ink jetting orifices of the recording head  51 . As the pigment ink is supplied to the recording head  51  as described above, the cartridge  1  takes in the ambient air through its air vent  11  to compensate for the void which would be created in the ink absorbing member  3  as the pigment ink  2  is supplied from the ink absorbing member  3 , if the ambient air were not taken in. 
         [0050]      FIG. 4  is an enlarged sectional view of the recovery cap mechanism  52  used in the recovery operation, which is an operation for recovering the performance of the recording head  51  by suctioning out the ink in the recording head  51 , and its adjacencies, and shows the structure of the recovery cap mechanism  52 . The recovery cap mechanism  52  has a pair of caps  12  and  19 , which are in connection with a suction pump. The cap  12  is for suctioning out the ink in the cartridge  1  through the ink jetting orifices of the recording head  51 . The cap  19  is for suctioning out the ink in the cartridge  1  through the section  6 A of the ink passage. The cap  19  has a sealing member  20 , which is for sealing the joint between the bottom end of the ink passage section  6 A and the cap  19 . The cap  19  is also provided with a projection  21  which projects beyond the top surface of the cap  19 , which comes into contact with the cartridge  1 . The cap  12  is provided with a discharge hole  13 , which is in connection with a discharge tube  14 . 
         [0051]    Next, the operation for recovering the performance of the cartridge  1  by suctioning out the ink in the cartridge  1  will be described. It is assumed that before the recovery operation is carried out, the cartridge  1  has been left unused (undisturbed) for a long time, and therefore, the pigment in the bodies of ink in the areas A, B, and C of the cartridge  1  has sedimented. It is the bottom portion of the area A that has become highest in the pigment concentration. There are pigment particles which have accumulated in this portion of the area A. In the recovery operation, therefore, ink is suctioned out from this portion, or the bottom portion of the area A. 
         [0052]    Referring to  FIG. 5 , next, the cap  19  is pressed on the cartridge  1  so that the sealing member  20  is placed hermetically in contact with the area of the bottom surface of the cartridge  1 , which surrounds the bottom opening of the section  6 A of the ink passage. During this step, the projection  21  of the cap  19  enters the section  6 A beyond the plug  18  and ball seat  17 , while pushing up the ball  15 . As a result, the ball  15  is separated from the ball seat  17 , creating a gap, between the ball  15  and ball seat  17 , through which ink can flow. 
         [0053]    The cap  19  is in connection with an unshown suction pump (vacuum pump) to generate negative pressure in the cap  19 . Next, referring to  FIG. 6 , as the suction pump is driven, the ink in the section  6 A is suctioned into the cap  19 . That is, the body of ink in the bottom portion of the section  6 A, into which the pigment particles have sedimented, is suctioned in the direction indicated by an arrow mark T. The amount by which the ink is suctioned out can be optimized, and also, minimized, by setting the amount according to the length of time the recording apparatus has been continuously left unused. After the preset amount of ink is suctioned out, the cap  19  is separated from the cartridge  1 . 
         [0054]    Referring to  FIG. 7 , next, the cap  12  is pressed upon the recording head  51 , whereby the space surrounded the recovery cap  12  and recording head  51  is hermetically sealed. The discharge tube  14  of the cap  12  is in connection with an unshown suction (vacuum) pump. As soon as the cap  12  becomes connected to the recording head  51 , the suction pump is driven to suction out ink from the recording head  51  by an amount large enough to remove the sedimented ink ingredients and the lingering bubbles in the areas B and C. As ink is suctioned out of the recording head  51 , it is discharged outward from the cap  12  through the discharge hole  13  and discharge tube  14 , and then, is sent to the waste ink absorbing member in the recording apparatus. As soon as the process of suctioning ink out of the recording head  51  is completed, the cap  12  is retracted (separated) from the recording head  51  (cartridge  1 ). 
         [0055]    The caps  12  and  19  are placed in contact with, or separated from, the cartridge  1  by a mechanical driving means in the recording apparatus. In this embodiment, the caps  12  and  19  can be advanced toward, or retracted from, the cartridge  1 , independently from each other. In other words, the caps  12  and  19  are individually driven. 
         [0056]    In this embodiment, the body of high density ink (high in pigment concentration) in the area D shown in  FIG. 5 , that is, the body of ink into which the pigment has sedimented, is discharged by suctioning the ink in the cartridge  1  through the ink passage sections  6  and  6 A (for convenience, this process may be simply stated as “process of suctioning ink from ink passage section  6 A”). Then, the bodies of ink in the areas B and C, which are high in density (pigment concentration) and contain the bubbles, are removed by suctioning the ink in the cartridge  1  through the ink passage section  6  and  6 B (for convenience, this process may be referred to as “process of suctioning ink from ink passage  6 B”). The amount by which ink is to be suctioned out when removing the ink in the section  6 B has only to be just enough to remove the sedimented ink ingredients in the areas B and C, because the sedimented ink ingredients in the area A are removed before the ink in the section  6 B is suctioned out. Therefore, unlike in the past, it is unnecessary to remove all the ink in the areas on the downstream side of the filter  4 . In other words, compared to the amount by which ink has to be suction out according to the prior art, the amount by which ink has to be suction out of the ink cartridge  1  in this embodiment is smaller by an amount equal to the amount of ink in the top portion of the area A, that is, the body of ink which does not need to be removed, because the pigment had not sedimented in this body of ink. Therefore, this embodiment is smaller in the amount of waste ink, and therefore, the waste ink absorbing member in the recording apparatus may be smaller. Thus, this embodiment makes it possible to reduce the recording apparatus in size. 
         [0057]    Described below are the sequential steps in the recovery operation for removing the sedimented ink ingredients with the use of the cap  19 . 
         [0058]    1) The sealing member of the cap  19  is pressed on the plug  18  to hermetically seal the space surrounded by the sealing member  20 , and the area of the bottom surface of the cartridge  1 , which is next to the bottom opening of the ink passage section  6 A. 
         [0059]    2) The projection  21  which extends from within the sealing member  20  reaches beyond the opening S of the plug  18 , and comes into contact with the ball  15 . 
         [0060]    3) The cap  19  is to be pressed hard enough for the projection  21  to push upward the ball  15  away from the ball seat  17 . 
         [0061]    4) Negative pressure is generated in the cap  19  to suction ink by a preset amount in the direction indicated by an arrow mark T. 
         [0062]    5) After the removal of the preset amount of ink, the cap  19  is moved in the direction (downward) to remove the pressure applied to the cartridge  1  by the cap  19 . 
         [0063]    Incidentally, in the above described embodiment, ink is suctioned out of the ink passage section  6 A while keeping the cap  12  pressed upon the cartridge  1 , and thereafter, ink is suctioned out from the ink passage section  6 B while keeping the cap  19  pressed upon the cartridge  1 . However, it is acceptable to suction ink out of the ink passage section  6 A while keeping both the caps  12  and  19  pressed upon the cartridge  1 , and thereafter, suction ink out of the ink passage section  6 B. Shown in  FIG. 8  is the state of the cartridge  1  and caps  12  and  19 , in which both caps  12  and  19  are kept pressed upon the cartridge  1  to keep hermetically sealed the spaces surrounded by the caps  12  and  19  and the corresponding areas of the cartridge  1 . In this case, when ink is suctioned out of the ink passage section  6 A with the use of the cap  19 , the sedimented ink ingredients in the area D can be more efficiently suctioned out, because the ink jetting orifices of the recording head  51  are kept sealed by the cap  12 . After ink is suctioned out of the ink passage section  6 A as shown in  FIG. 8 , the cap  19  is separated from the cartridge  1  as shown in  FIG. 7 . Then, the ink in the areas B and C are suctioned out through the cap  12  (by generating negative pressure in the cap  12 ). 
       Embodiment 2 
       [0064]    Next, referring to  FIGS. 9-12 , the second preferred embodiment of the present invention will be described. Incidentally, the components in this embodiment, which are identical to the counterparts in the first embodiments are given the same referential symbols as those given to the counterparts, and will not be described; only the components in this embodiment, which are not identical to the counterparts in the first embodiment, or not present in the first embodiment, will be described. In this embodiment, a heat radiating member  23 , which is the counterpart of the heat radiating member  9  in the first embodiment, is provided with a through hole  24 . Further, a sealing member  22  in this embodiment is made wider than the sealing member  22  in the first embodiment, and also, is shaped so that it can seal between the heat radiating member  9  and cartridge  1  around both the openings of the ink passage sections  6 A and  6 B. An ink jet recording head  55 , or the ink jet recording head in this embodiment, is structured to be compatible with the heat radiating member  23 . The employment of this structural arrangement makes it possible to eliminate the plug  18 , which was necessary in the first embodiment. Thus, it can eliminate the process for welding the plug  18  to the cartridge  1 . 
         [0065]    Shown in  FIG. 10  are a cap  25 , that is, the cap in this embodiment, used for the recovery operation, and the recording head  55 . 
         [0066]    The cap  25  is an integral combination of the caps  12  and  19  used in the first embodiment. The cap  25  has a projection  26  which projects from the inward side of the sealing member  20 . Incidentally, the projection  26 , which is equivalent to the projection  21  used in the first embodiment, is longer than the projection  21 , by the length equal to the thickness of the heat radiating member  23 . Further, the cap  25  has two ink passage sections  56 A and  56 B, through which ink is suctioned out. The two ink passages sections  56 A and  56 B of the cap  25  correspond to the ink passage sections  6 A and  6 B of the cartridge, respectively. The ink passage sections  56 A and  56 B are separated by a three way valve U. The provision of the three way valve U between the two ink passage sections  56 A and  56 B of the cap  25  makes it possible to switch between the two ink passage sections  56 A and  56 B when suctioning ink. 
         [0067]      FIG. 11  shows the state of the cap  25  and recording head  55 , in which the recovery operation is being carried out, with the cap  25  kept pressed on the recording head  55  so that the spaces formed by placing the cap  25  in contact with the recording head  55  remains hermetically sealed. As the cap  25  is pressed on the recording head  55  hard enough to keep the abovementioned spaces hermetically sealed, the projection  26  causes the ball  15  to separate from the sealing member  22 . In the recovery operation in this embodiment, first the three way valve U is turned so that the ink passage section  6 A becomes connected to the ink suctioning side, and the ink in the area A is suctioned out. In this step of the recovery operation, the body of ink in the area A, that is, the body of ink, in which the sedimentary ink ingredients had accumulated, is removed. 
         [0068]    Next, referring to  FIG. 12 , the three way value U is turned to connect the ink passage section  6 B to the side from ink is suctioned, while keeping the cap  25  pressed on the recording head  55 . Then, the bodies of ink in the areas B and C are suctioned out, whereby the sedimented ink ingredients are removed from the areas B and C, and also, the bubbles lingering in the ink passage section  6 B are removed. 
         [0069]    The cap  25 , that is, the recovery cap in this embodiment, is more complicated than the recovery caps in the first embodiment. However, the cap  25  is an integral combination of the two caps  12  and  19  required in the first embodiment. In other words, the cap  25  replaces the two caps  12  and  19  which were required in the first embodiment. Therefore, the employment of the cap  25  makes it unnecessary to individually advance or retract multiple (two) caps; only one cap driving means, that is, the driving means for driving the cap  25 , is necessary. Further, the cap  25  has to be advanced once and retracted once per recovery operation. Therefore, this embodiment is smaller in the number of times a capping means has to be driven (number of times cap  25  has to be driven) per recovery operation. Therefore, this embodiment is smaller in the amount of the load for driving the cap than the first embodiment. 
       Embodiment 3 
       [0070]    Next, referring to  FIGS. 13-16 , the third embodiment of the present invention will be described. Incidentally, the components in this embodiment, which are identical to the counterparts in the first or second embodiment are given the same referential symbols as those given to the counterparts, and will not be described; only the components in this embodiment, which are not identical to the counterparts in the first or embodiment, or not present in the first or second embodiment, will be described. In this embodiment, a slidable pin  27  is provided in place of the ball  15  employed in the second embodiment. The slidable pin  27  is made up of a ball portion, such as the ball  15  in the second embodiment, and a projection portion, such as the projection  26  in the second embodiment. Thus, the valve mechanism is opened or closed by the slidable pin  27 . 
         [0071]      FIG. 14  shows a cap  28 , that is, a cap in this embodiment, will be described. The cap  28  is provided with a plate  29  which comes in contact with the slidable pin  27 . As the cap  28  is pressed on a recording head  57 , which is a recording head in this embodiment, to hermetically seal the space formed between the cap  28  and recording head  57 , the plate  29  presses on the slidable pin  27 , causing thereby the slidable pin  27  to be separated from the sealing member  22 . The plate  29  is rigid enough not to deform when it presses on the slidable pin  27 . 
         [0072]    The recover operation in this embodiment, which uses the cap  28 , is the same as the recovery operation in the second embodiment.  FIG. 15  shows the state of the cartridge  1  and cap  28 , in which the ink is being suctioned out of the ink passage section  6 A in order to suction out the body of ink in the area D, which is high in pigment concentration. After the body of ink in the area D is suctioned out, the three way valve U is turned to connect the ink passage section  6 B to the side toward which ink is suctioned out, and the bodies of ink in the areas B and C are suctioned out to continue the recovery operation as shown in  FIG. 16 . 
         [0073]    In this embodiment, unlike the cap  19 , that is, the cap in the first or second embodiment, the cap  28  does not need to be provided with a projection ( 21 ). It is only the plate  29 , or the plate which comes into contact with the valve mechanism, that the cap  28  needs to be provided. Therefore, this embodiment is simpler in terms of the shape of the recovery cap ( 28 ) than the second embodiment. 
       Embodiment 4 
       [0074]    Next, referring to  FIGS. 17-19 , the fourth embodiment of the present invention will be described. This embodiment is different from the third embodiment in that the ink passage sections  6 ,  30 , and  31  of the cartridge  1  in this embodiment, which correspond to the ink passage sections  6 ,  6 A, and  6 B of the cartridge  1  in the third embodiment, are inclined. The section  6  branches into the sections  30  and  31  at a branching point G (sections  6  and  30  will be together referred to as section  30 , for convenience) in the area E. The section  31  leads into the liquid chamber  8 . The section  30  is the ink passage section in into which the pigment easily sediments, and which is provided with a valve mechanism, which is located at the bottom end of the section  30 .  FIG. 18  is an enlarged view of the area E shown in  FIG. 17 , which is the adjacency of the branching point G. 
         [0075]    Both the ink passage sections  30  and  31  are inclined relative to the vertical direction. The ink passage section  31 , which branches from the section  30 , is greater in inclination angle, relative to the vertical direction, than the section  30 .  FIG. 19  is a view of the internal wall of the ink passage, as seen from the direction indicated by an arrow mark F in  FIG. 18 . It is evident from  FIG. 19  that the ink passage section  30  is tubular and the section  31  branches out from the portion of the internal wall of the ink passage section  30  at the branching point G, in such a manner that the border line between the ink passage sections  30  and  31  curves as if the ink passages  30  were intact. Thus, the section  31  is not visible in the area of the drawing, which corresponds to the internal space of the section  30 . Based on the knowledge of the inventors of the present invention, in order to enhance the sedimentation of the pigment into the ink passage  30 , it is desired that a branching point G 2  shown in  FIG. 18  is not on the valve mechanism side of the center line H of the ink passage section  6  (left side of center line H in  FIGS. 17-19 ). That is, it is desired that the recording head  57  is structured so that the border line between the ink passage portions  30  and  31  does not intersect with the center line of the ink passage section  30 , nor is on the valve mechanism side of the center line. Pigment sediments in the direction of gravity. Therefore, structuring the cartridge  1  as described above make is possible to guide the pigment into the section  30  as the pigment sediments, while making it harder for the pigment to enter the section  31 . In this embodiment, it is desired that the cartridge  1  is structured so that the border line between the ink passage sections  30  and  31  is on the recording head side of the center line H (right-hand side of center line H in  FIGS. 17-19 ). 
         [0076]    The double-dot chain line in  FIG. 18  is for describing the case in which the cartridge  1  is structured so that a part of the section  31  is visible in the internal area of the ink passage section  30 , as the ink passage section  30  is seen from the direction indicated by the arrow mark F, and also, so that the branching point G is on the recording head side (right-hand side) of the center line H of the section  30  of the ink passage. Also in this case, the cartridge  1  is structured so that the border line between the ink passage sections  30  and  31  is on the recording head side (right-hand side) of the center line H of the section  31  and does not intersect with the center line H. Pigment sediments in the direction of gravity. Therefore, structuring the cartridge  1  as described above makes it possible to guide the pigment into the section  30  of the ink passage as it sediments, making it therefore harder for the pigment enters the section  31  of the ink passage as it sediments. 
       Embodiment 5 
       [0077]    Next, referring to  FIGS. 20 and 21 , the fifth embodiment of the present invention will be described. 
         [0078]    In this embodiment, the ink passage  6  of the cartridge  1  bifurcates into sections  32  and  33 . More specifically, the sections  33  branches out from the section  32  of the ink passage at a bifurcation point J, and leads into the liquid chamber  8 . The ink passage section  32  is the section, into which the pigment can more easily sediment than the section  33 . The section  32  is provided with a valve mechanism, which is located at the bottom end of the section  32 . 
         [0079]      FIG. 21  is a drawing of the sections  32  and  33  of the ink passage, which are seen from the direction indicated by an arrow mark I in  FIG. 20 . The section  32  of the ink passage is tubular. The section  33  of the ink passage branches from the section  32  of the ink passage, at the branching point J, which is on the recording head side of the center line H of the section  32 . Based on the knowledge of the inventors of the present invention, in order to promote the sedimentation of pigment into the section  32 , it is desired that the branching point J is on the recording head  59  side of the center line H of the section  32 . That is, it is desired that the cartridge  1  is structured so that the border line between the ink passage sections  32  and  33  does not cross the center line H. From the standpoint of ensuring that the pigment sediments into the section  32  of the ink passage, setting the position of the branching point J as described above is effective, and is more effective than adjusting the angle at which the ink passage section  6  bifurcates into the sections  32  and  33 . Pigment sediments in the direction of gravity. Therefore, structuring the cartridge  1  as described above makes it possible to guide the pigment into the section  32  of the ink passage while the pigment is sedimenting, making it harder for the pigment to enter the section  33  of the ink passage. 
       Miscellaneous Embodiments 
       [0080]    Incidentally, in each of the above described preferred embodiments of the present invention, the present invention was applied to the ink jet recording cartridge, which is an integral combination of an ink cartridge (or ink cartridges) and an ink jet recording head. However, these embodiments are not intended to limit the present invention in scope. That is, the present invention is also applicable to an ink jet recording cartridge structured so that its ink jet recording head and ink container are separable from each other. 
         [0081]      FIG. 22  is a sectional view of a recording head in accordance with the present invention, which is independent from an ink container, and shows the structure of the recording head. The structure of this recording head is the same as the structure of the recording head portion of the ink jet recording cartridge  1  shown in  FIG. 1 , except that an ink container  101 , that is, the ink container for this recording head, is removably attachable to the recording head. Therefore, the structure of this recording head will not be described in detail. 
         [0082]    Also in each of the above described preferred embodiments of the present invention, it was pigment ink (ink which contains pigment) that was jetted from the recording head. However, the liquid to be jetted from the recording head does not need to be ink; it may be liquid other than ink. Also in each of the above described embodiments, it was the pigment in ink that was discharged through the section(s) of the ink passage, which branched from the primary section of the ink passage. However, the ingredient(s) in ink, which is to be discharged, may be ingredients other than the pigment. Further, in each of the above described preferred embodiments, the recording apparatus was an ink jet recording apparatus. However, the present invention is applicable to recording apparatuses other than an ink jet recording apparatus. Further, the recording apparatus was of the serial scan type. However, the present invention is applicable to a recording apparatus of the full-line type, just as well. 
         [0083]    While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth, and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims. 
         [0084]    This application claims priority from Japanese Patent Application No. 148841/2006 filed May 29, 2006 which is hereby incorporated by reference.

Technology Classification (CPC): 1