Patent Publication Number: US-2006001712-A1

Title: Ink cartridge having projections formed on outer surface of its casing

Description:
This application is based on Japanese Patent Application No. 2004-192628 filed on Jun. 30, 2004, the content of which is incorporated hereinto by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an ink cartridge having a configuration effective to protect its casing from an impact applied thereto.  
      2. Discussion of Related Art  
      There is known an ink cartridge, as disclosed in U.S. Pat. No. 6,786,581 (corresponding to JP-2001-113723A), which is to be installed on an inkjet recording apparatus, so that an ink contained in the cartridge is consumed in a recording operation performed by the recording apparatus. The ink cartridge, which is commonly made of a resin material is breakable, for example, when it is carelessly dropped onto a floor or hit against an object after being taken out a package, namely, before or upon its installation on the recording apparatus. Where a resin-made casing of the ink cartridge is cracked or broken, an ink stored in the casing is likely to leak, getting the surrounding dirty with the ink leaking out of the casing and even causing the ink cartridge to be unserviceable.  
     SUMMARY OF THE INVENTION  
      The present invention was made in view of the background prior art discussed above. It is therefore an object of the invention to provide an ink cartridge capable of protecting its casing from an impact applied thereto, This object may be achieved according to a principle of the invention, which provides an ink cartridge including: a casing having an ink chamber for storing the ink; and a plurality of projections projecting from an outer surface of the casing and spaced apart from each other. The plurality of projections preferably includes at least three projections which are arranged at substantially the same pitch. Each of the plurality of projections is preferably provided by a projecting plate which is elongated along the outer surface of the casing. A height of each of the plurality of projections is preferably is larger than a pitch between each adjacent pair of the plurality of projections. The plurality of projections are preferably formed integrally with the casing.  
      In this ink cartridge constructed according to the invention, the plurality of projections are formed on the outer surface of the casing and are spaced apart from each other. The provision of the projections on the outer surface of the casing is effective to protect the casing from an impact applied thereto, for example, when the ink cartridge is carelessly dropped onto a floor or hit against an object. Thus, the casing of the ink cartridge is advantageously prevented from being broken or damaged, thereby avoiding the ink from leaking out of the ink chamber and failure of the ink cartridge serving as an ink supplier.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other objects, features, advantages and technical and industrial significance of the present invention will be better understood by reading the following detailed description of presently preferred embodiment of the invention, when considered in connection with the accompanying drawings, in which:  
       FIG. 1  is a view schematically showing an inkjet recording apparatus equipped with an ink cartridge which is constructed according to an embodiment of the invention;  
       FIG. 2A  is an elevational view in vertical cross section of the ink cartridge;  
       FIG. 2B  is a cross sectional view taken along line  2 B- 2 B of  FIG. 2A ; and  
       FIG. 3  is a perspective view of the ink cartridge. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      There will be described an ink cartridge  1  constructed according to an embodiment of the invention, by reference to  FIGS. 1-3 .  
      The ink cartridge  1  is to be installed on an inkjet recording apparatus in the form of an inkjet printer  2 , which is schematically shown in  FIG. 1 , including: a mount portion  3  on which the ink cartridge  1  is removably mounted; a buffer tank  5  for storing the ink supplied from the ink cartridge  1  through an ink supplying tube  4 ; a recording head  7  for ejecting the ink stored in the buffer tank  5 , toward a paper sheet  6  as a recording medium; a carriage  9  for carrying a recording head unit  8  equipped with the buffer tank  5  and the recording head  7 ; a pair of guide shafts  10  for guiding the carriage  9  which is movable along a straight line; a feeding device  11  for feeding the paper sheet  6  in a predetermined direction; and a purging device  12 . It is noted that although only the single ink cartridge  1  is illustrated in  FIG. 1 , a plurality of ink cartridges  1  are installed on the inkjet printer  2  in the present embodiment, so that a full-color printing operation is performed with four color inks (e.g., cyan, magenta, yellow and black inks) which are stored in the respective ink cartridges  1 .  
      The mount portion  3  has a base portion  3   a  and a pair of guide portions  3   b  which extend from respective opposite end portions of the base portion  3   a . An ink supplying pipe  13  and an air introducing pipe  14  are provided to project from the base portion  3   a , so that the ink stored in the ink cartridge  1  can be supplied to an exterior of the ink cartridge  1  through the ink supplying pipe  13  while an atmospheric air can be introduced into the ink cartridge  1  through the air introducing pipe  14 . Each of the pipes  13 ,  14  has an upper distal end that is made substantially flat. A cutout  13   a ,  14   a  (see  FIG. 2A ) is formed in the upper distal end of the pipe  13 ,  14 , so that inside and outside of the pipe  13 ,  14  are communicable with each other through the cutout  13   a ,  14   a  when the pipe  13 ,  14  is held in contact with a valve member that is described below.  
      The ink supplying pipe  13  is connected at its lower end to the ink supplying tube  4 , so as to be held in communication with the buffer tank  5  via the ink supplying tube  4 . The air introducing pipe  14  is connected at its lower end portion to an air introducing tube  15 , so as to be held in communication with an atmosphere via the air introducing tube  15 .  
      The recording head  7  is constituted principally by a cavity unit (not shown) and a piezoelectric actuator plate (not shown) which is bonded to an upper surface of the cavity unit. The cavity unit is a laminar structure consisting of a plurality of plates which cooperate with one another to define a plurality of cavities for accommodating the ink supplied from the buffer tank  5 . The piezoelectric actuator plate has a plurality of active portions corresponding to the respective cavities of the cavity unit. The active portions of the piezoelectric actuator plate are selectively deformable upon application of a drive voltage thereto, which is controlled by CPU (not shown), so as to eject the ink from the corresponding cavities through nozzles (not shown). It is noted that the nozzles are formed through a nozzle-defining surface of the cavity unit of the recording head  7 , which surface is to be opposed to the paper sheet  6 . The nozzles are arranged in a plurality of rows, such that the nozzles of each adjacent pair of the rows are positioned in a zigzag pattern.  
      The purging device  12  is disposed in a purging operation position located outside a printing area (within which the recording head  7  is moved for achieving the printing operation), and is opposed to the recording head  7  when the recording head  7  is positioned in the purging operation position. The purging device  12  has a purge cap  12   a , a waste ink tube  12   b  and a pump  12   c . The purge cap  12   a  is provided to cover the nozzle-defining surface of the recording head  7 . The pump  12   c  is activated to suck poor-quality or waste ink from the nozzles through the waste ink tube  12   b  which is held in communication with the purge cap  12   a.    
      Referring next to  FIGS. 2A, 2B  and  3 , there will be described a construction of the ink cartridge  1  in detail.  FIG. 2A  is an elevational cross sectional view of the ink cartridge  1 .  FIG. 2B  is a cross sectional view taken along line  2 B- 2 B of  FIG. 2A  and showing a corner of a circumferential side wall of the cartridge  1 .  FIG. 3  is a perspective view of the cartridge  1 .  
      The ink cartridge  1  is constituted by a casing  1   a ,  1   b ,  1   c  having an ink chamber  20  for storing the ink. The casing  1   a ,  1   b ,  1   c  includes an ink-chamber definer body  1   a ,  1   b  defining the ink chamber  20  therein. The ink-chamber definer body  1   a ,  1   b  includes a lid member  1   a  and a vessel member  1   b  which are connected to each other. The vessel member  1   b  has a bottom wall  21 , a circumferential side wall  22  and an upper opening which is surrounded by the circumferential side wall  22  and which is closed by the lid member  1   a . The casing further  1   a ,  1   b ,  1   c  includes a cover member  1   c  which covers a communication-passage defining wall (which is described below) of the ink-chamber definer body  1   a ,  1   b  so as to provide a bottom wall of the casing  1   a ,  1   b ,  1   c . The cover member  1   c  has a pair of communication holes  23 ,  24  formed therethrough, such that the ink chamber  20  is communicable with an exterior of the casing  1   a ,  1   b ,  1   c  through the communication holes  23 ,  24 . The ink cartridge  1  is assembled by fusing or otherwise bonding the lid member  1   a  and the cover member  1   c  to the vessel member  1   b . Each of the lid member  1   a , vessel member  1   b  and cover member Ic is made of a resin material such as polypropylene, polystyrene and polyacetal.  
      In the ink cartridge  1 , a plurality of projections are provided to project from an outer surface of the casing  1   a ,  1   b ,  1   c . In the present embodiment, each of the plurality of projections is provided by a fin or rib R (i.e., projecting plate) which is elongated along the outer surface of the casing  1   a ,  1   b ,  1   c  The plurality of ribs R are spaced apart from each other, and extend outwardly from the lid member  1   a  (which constitutes a top wall of the casing  1   a ,  1   b , ic) and the circumferential side wall  22  of the vessel member  1   b  (which constitutes a circumferential side wall of the casing  1   a ,  1   b ,  1   c ). The plurality of ribs R are formed integrally with the lid member  1   a  and the circumferential wall  22  which have inside surfaces facing the ink chamber  20 . Each of the ribs R projects from the outer surface of a corresponding portion of the casing  1   a ,  1   b ,  1   c  by a predetermined distance or height h which is larger than a pitch P between each adjacent pair of the ribs R. The height h is preferably about 5 mm, while the pitch p is preferably 3-4 mm. In the present embodiment, the number of the ribs R formed on the lid member  1   a  and extending in a widthwise direction of the lid member  1   a  (i.e, in a direction perpendicular to the drawing sheet of  FIG. 2A ) is fourteen, while the number of the ribs R formed on the circumferential side wall  22  of the vessel member  1   b  and extending in a vertical direction of the casing  1   a ,  1   b ,  1   c  (i.e., in a vertical direction in the drawing sheet of  FIG. 2A ) is forty-six.  
      The provision of the ribs R on the outer surface of the casing  1   a ,  1   b ,  1   c  is effective, when the ink cartridge  1  is carelessly dropped onto a floor or hit against an object, to avoid the casing  1   a ,  1   b ,  1   c  from being broken by an impact exerted thereto from the floor or object. It is therefore possible to prevent the floor or surrounding area from being stained with the ink having leaked through a broken portion of the casing  1   a ,  1   b ,  1   c  of the cartridge  1 . The ribs R are elastically deformable upon application of an impact thereto, so as to alleviate the impact acting on the casing  1   a ,  1   b ,  1   c , advantageously avoiding damage of the casing  1   a ,  1   b ,  1   c . It is noted that the ribs R are not formed on the cover member  1   c  which covers the communication-passage defining wall of the vessel member  1   b , since the ink chamber  20  is not likely to be broken where the impact is applied to the cover member  1   c  which cooperates with the communication-passage defining wall of the vessel member  1   b  to constitutes a double-wall structure protecting the ink chamber  20  from the exterior of the casing  1   a ,  1   b ,  1   c  of the ink cartridge  1 .  
      The vessel member  1   b  has an ink supplying port  25  and an air introducing port  26  formed in its bottom wall  21 , such that the ink stored in the ink chamber  20  can be supplied to the exterior of the ink cartridge  1  through the ink supplying port  25 , and such that the air can be introduced into the ink chamber  20  through the air introducing port  26 . The vessel member  1   b  includes integrally-formed first and second tubular walls  25   a ,  26  projecting downwardly from its bottom wall  21 . The ink supplying port  25  and the air introducing port  26  are defined in or surrounded by the first and second tubular walls  25   a ,  26   a , respectively. When the ink cartridge  1  is mounted on the mount portion  3  of the inkjet printer  2 , the ink supplying pipe  13  and the air introducing pipe  14  are introduced into the ink supplying port  25  and the air introducing port  26 , respectively.  
      The ink cartridge  1  further has first and second seals  27 ,  28  which are received in the ink supplying port  26  and the air introducing port  26 , respectively. The seals  27 ,  28  seal the supplying port  25  and the air introducing port  26 , respectively, while the ink cartridge  1  is not mounted on the mount portion  3 .  
      Further, in the bottom wall  21  of the vessel member  1   b , there are formed a plurality of communication holes  30  through which the ink chamber  20  and the ink supplying port  25  are communicable with each other. The communication holes  30  are selectively opened and closed by an inverted umbrella-shaped valve member  32  which is made of a synthetic resin having a certain degree of elasticity.  
      The valve member  32  includes a disk-shaped head portion  33  and a stem portion  34  which formed integrally with each other. The head portion  33  is opposed to lower ends of the respective communication holes  30 , and is held by the stem portion  34  which extends from substantially the center of the head portion  33  and which is slidably received in a through-hole  31  formed through the bottom wall  21 . The through-hole  31  is located at a center of a circle on which the communication holes  30  lie. The stem portion  34  has, in its axially intermediate portion, an annular protrusion  35  whose diameter is larger than that of the through-hole  31 , so that the valve member  32  is vertically movable relative to the bottom wall  21  between opposite ends which are defined by the disk-shaped head portion  33  and the annular protrusion  35  of the stem portion  84 . Owing to its own weight, the valve member  32  is normally held in its open position in which the head portion  33  is spaced apart from the communication holes  30  while the annular protrusion  35  of the stem portion  34  is held in contact with the upper surface of the bottom wall  21 , whereby the ink is allowed to flow in a direction away from the ink chamber  20  toward the ink supplying port  25 . However, when there is caused a flow of the ink in the opposite direction, the valve member  32  is placed in its closed position in which the head portion  33  is moved upwardly to close the communication holes  30 , thereby inhibiting the flow of the ink in the opposite direction. That is, the valve member  32  serves as a check valve.  
      The vessel member  1   b  further includes an integrally-formed air guiding tubular wall  40  extends upwardly from the bottom wall  21  toward the lid member  1   a  which closes the upper opening of the vessel member  1   b . The air guiding tubular wall  40  has an upper opening end  42  which is located above a level of the ink stored in the ink chamber  20 , so that the atmospheric air introduced through the air introducing pipe  14  is delivered along a guide passage  41  defined in the air guiding tubular wall  40  to an upper region of the ink chamber  20 . The guide passage  41  of the air guiding tubular wall  40  is held in communication with the air introducing port  26  via a connection passage defined in a tapered inner surface of a connection portion  43  (which is provided by a proximal end portion of the tubular wall  40 ).  
      The first seal  27  disposed in the ink supplying port  25  is constituted by an elastically-deformable holding member  50  which is provided by a single piece made of a rubber or other elastic material, and a valve member  51  which is made of a synthetic resin. The holding member  50  has a generally tubular shape, and includes a valve seat portion  52 , a biasing portion (biaser)  58 , a tubular portion  64  and an outer circumferential wall portion  55 . The valve seat portion  52  is provided by its axially intermediate portion. The biasing portion  53  is located on one of axially opposite sides of the valve seat portion  52  that is closer to the ink chamber  20  than the other of the axially opposite sides of the valve seat portion  52 . The tubular portion  54  is located on the other of the axially opposite sides of the valve seat portion  52 . The outer circumferential wall portion  55  surrounds the tubular portion  54 , such that the outer circumferential wall portion  55  is radially spaced apart the tubular portion  64  by a predetermined distance, and such that an outer circumferential surface of the tubular portion  54  and an inner circumferential surface of the outer circumferential wall portion  56  are circumferentially extend in parallel with each other. The valve member  51  is held in the holding member  50 , while being biased by the biasing portion  53  in a biased direction that causes the valve member  51  to be seated on the valve seat potion  52  so as to be placed in its closed position.  
      The outer circumferential wall portion  55  has, in one of axially opposite end portions that is remote from the biasing portion  53 , a large-diameter portion  56  which projects outwardly in the radial direction, so that the biasing portion  53  and the other portion of the outer circumferential wall portion  55  have a diameter smaller than a diameter of the large-diameter portion  56 . The ink supplying port  25  has a small-diameter region and a large-diameter region which is located on one of axially opposite sides of the small-diameter region that is remote from the ink chamber  20 . The biasing portion  63  of the holding member  50  is accommodated in the small-diameter region of the ink supplying port  25 , while the large-diameter portion  56  of the holding member  50  is accommodated in the large-diameter region of the ink supplying port  25 . In the process of assembling the ink cartridge  1 , the vessel member  1   b  and the cover member  1   c  are bonded to each other, while the holding member  50  is gripped at its large-diameter portion  56  between the cover member  1   c  and a shoulder surface if which is located between the small-diameter region and the large-diameter region of the ink supplying port  26 , for thereby preventing an ink leakage between the vessel member  1   b  and the first seal  27 .  
      The valve seat portion  52  and the tubular portion  54  of the holding member  50  have a through-hole  58  and a pipe receiver hole  59  which are both located at an axis of the holding member  60  and which are contiguous to each other. When the ink cartridge  1  is mounted on the mount portion  8 , the ink supplying pipe  18  is fluid-tightly fitted into the pipe receiver hole  59  of the tubular portion  54 . For assuring such a fluid-tight fitting, the pipe receiver hole  59  has an inside diameter smaller than an outside diameter of the ink supplying pipe  13 . Further, the through-hole  58  has an inside diameter which is larger than the inside diameter of the pipe receiver hole  59  and which is larger than the outside diameter of the ink supplying pipe  13 . It is noted that the pipe receiver hole  59  has, in its axially outside portion, a tapered portion whose diameter is increased as viewed in an axially outward direction of the hole  59 .  
      The outer circumferential wall portion  55  is radially spaced apart from the tubular portion  54  by an annular groove  60 , so that the tubular portion  54  is elastically deformable or displaceable, relative to the outer circumferential wall portion  55 , on a plane perpendicular to an axis of the pipe receiver hole  59 . The biasing portion  53  includes a side wall portion  61  which extends from a periphery of the valve seat portion  62  in a direction toward the ink chamber  20 , and an upper wall portion  62  which extends from the side wall portion  61  in a radially inward direction so as to be in contact with one of axially opposite end surfaces of the valve member  51  that is remote from the valve seat portion  52 . The upper wall portion  62  extends radially inwardly from the side wall portion  61  over a predetermined distance, so as to define an opening  63  which is surrounded by the upper wall portion  62 . Owing to an elasticity of the material forming the holding member  50 , the biasing portion  53  of the holding member  50  biases the valve member  51  in the biased direction that causes the valve member  51  to be seated on the valve seat portion  52 . Thus, the valve member  51  is normally held in close contact with the valve seat portion  52 , namely, normally placed in its closed position. However, when the ink cartridge  1  is mounted on the mount portion  3 , the ink supplying pipe  13  is introduced into the pipe receiver hole  59  and the through-hole  68 , and then forces the valve member  51  upwardly, i.e., toward the ink chamber  20 . With the valve member  51  being thus forced upwardly, the side wall portion  61  and the upper wall portion  62  of the biasing portion  53  of the holding member  50  are expanded and inclined, respectively, thereby allowing the valve member  51  to be moved upwardly. The upward movement of the valve member  51  causes formation of a spacing gap between the valve member  51  and the valve seat portion  52 , thereby allowing flow of the ink through the spacing gap.  
      The valve member  51  includes a bottom portion  70  which is to be in contact with the valve seat portion  52  of the holding member  50 , and an outer circumferential wall portion  71  which extends from a periphery of the bottom portion  70  in an upward direction (i.e., direction toward the ink chamber  20 ). The bottom portion  70  has, in its surface that is to be opposed to the valve seat portion  52  of the holding member  50 , an annular protrusion  72  which is located on a radially inner side of the outer circumferential wall portion  71  and on a radially outer side of the through-hole  58  of the holding member  50 . With the valve member  51  being accommodated in the holding member  50 , the circumferential wall portion  71  of the valve member  70  is held in close contact with a lower surface of the upper wall portion  62  of the biasing portion  53  of the holding member  50 , and is forced downwardly. Since the valve member  51  is thus forced downwardly, the valve seat portion  52  of the holding member  50  is elastically deformed by the annular protrusion  72  which is held in close contact with the valve seat portion  52 .  
      The valve member  51  has a plurality of communication apertures  73  which are formed through the bottom portion  70  and which are located between the annular protrusion  72  and the outer circumferential wall portion  71  as viewed in a radial direction of the valve member  51 . The plurality of communication apertures  73  are positioned to be spaced apart from each other as viewed in a circumferential direction of the valve member  51 .  
      The second seal  28  disposed in the air introducing port  26  is constituted by the elastically-deformable holding member  50  and a valve member  81 , which is substantially identical with the valve member  51  of the first seal  27  except for provision of a cylindrical portion  94  therein. That is, the valve member  81  has the above-described bottom portion  70 , outer circumferential wall portion  71 , annular protrusion  72  and communication apertures  73 , as the valve member  51 . The valve member  81  further has the cylindrical portion  94  which extends upwardly from substantially the center of an upper surface of the bottom portion  57 . The cylindrical portion  94  of the valve member  81  extends through the opening  63  which is surrounded by the upper wall portion  62  of the holding member  50 , with a spacing gap between an outer circumferential surface of the cylindrical portion  94  and an inner circumferential surface of the opening  63 . It is noted that the same reference signs as used in the above description of the first seal  27  are used to identify the functionally corresponding or structurally similar elements.  
      For installing the ink cartridge  1  onto the inkjet printer  2 , the cartridge  1  is moved toward the mount portion  3  in a direction indicated by arrow X (see  FIG. 1 ) so as to be mounted onto the mount portion  3 . In this instance, the ink supplying pipe  13  and the air introducing pipe  14  are introduced into the respective pipe receiver holes  59 , increasing diameters of the respective tubular portions  54 . The thus introduced pipes  13 ,  14  are brought into contact with the bottom portions  70  of the respective valve members  51 ,  81 . With further movement of the cartridge  1  in the direction indicated by the arrow X, each of the valve members  51 ,  81  is moved toward the ink chamber  20 , i.e., in a direction away from the valve seat portion  52 , whereby the communication apertures  73  of the valve members  51 ,  81  are brought into communication with the cutouts  13   a ,  14   a  of the ink supplying pipe  13  and the air introducing pipe  14  through the spacing gaps between the valve members  51 ,  81  and the valve seat portions  52 , thereby establishing an air introducing passage allowing the introduction of the air into the ink chamber  20  via the air introducing pipe  14 , communication apertures  73  and air guiding tubular wall  40 , and at the same time an ink supplying passage allowing the supply of the ink from the ink chamber  20  toward the recording head  7  via the communication holes  30 , communication apertures  73  and ink supplying pipe  13 .  
      In the present embodiment, the bottom wall  21  and the first and second tubular walls  25   a ,  26   a  of the vessel member  1   b  cooperate to constitute the above-described communication-passage defining wall through which first and second communication passages communicating between inside and outside of the ink chambers  20  are formed. The first communication passage is constituted by the above-described ink supplying port  25  and communication holes  30 , while the second communication passage is constituted by the above-described air introducing port  26  and guide passage  41 .  
      In the ink cartridge  1  constructed according to the present embodiment, the multiplicity of ribs R are substantially uniformly formed on the top wall and a majority of the circumferential side wall of the casing  1   a ,  1   b ,  1   c , namely, on the lid member  1   a  and a majority of the side circumferential surface  22  of the vessel member  1   b . When the ink cartridge  1  is carelessly dropped onto a floor or hit against an object, the ribs R formed on the outer surface of the casing  1   a ,  1   b ,  1   c  effectively absorb an impact applied thereto from the floor or object, thereby making it possible to prevent the casing  1   a ,  1   b ,  1   c  from being broken and accordingly avoid the floor or surrounding area from being stained with the ink leaking out of the casing  1   a ,  1   b ,  1   c.    
      Further, in the ink cartridge  1 , the ribs R are formed integrally with the casing  1   a ,  1   b ,  1   c , namely, each of the ribs R and a portion of the casing  1   a ,  1   b ,  1   c , from which the each of the ribs R extends, are provided by a single piece. Therefore, the ink cartridge  1  can be easily manufactured by using a smaller number of dies in an injection molding, than where the ribs R are formed independently of the casing  1   a ,  1   b ,  1   c . Further, the formation of the ribs R integrally with the casing  1   a ,  1   b ,  1   c  leads to reduction in the number of pieces required to assemble the ink cartridge  1  and accordingly reduction in the manufacturing cost.  
      Further, in the ink cartridge  1 , the projections are provided by the ribs R, i.e., projecting plates elongated along the outer surface of the casing  1   a ,  1   b ,  1   c . Since each of the projections is thus given a simple shape, the ink cartridge  1  can be easily manufactured.  
      Further, in the ink cartridge  1 , the height h by which each rib R projects from the outer surface of the casing  1   a ,  1   b ,  1   c  is adapted to be larger than the pitch P between each adjacent pair of the ribs R. This arrangement is effective to cause the ribs R to further effectively absorb an impact when the cartridge  1  is dropped or hit against an object, thereby further reliably protecting the casing  1   a ,  1   b ,  1   c.    
      Further, in the ink cartridge  1 , the ribs R are formed only on the outer surface of the lid member  1   a  and the majority of the outer surface of the vessel member  1   b , namely, only on a portion of the ink-chamber definer body  1   a ,  1   b  which portion is distant from or uncovered with the cover member  1   c . Since the ribs R are not formed on the cover member  1   c  and a covered portion of the vessel member  1   b  covered by the cover member  1   c , it is possible to reduce a projection-formed area, thereby making it possible to easily manufacture the ink cartridge  1  and reduce the manufacturing cost.  
      Further, the ribs R serving as an impact absorber for absorbing the impact applied to the ink cartridge  1  may be considered to serve also as cooling fins for dissipating heat.  
      While the presently preferred embodiment of the invention has been described above in detail, it is to be understood that the invention is not limited to the details of the illustrated embodiment, but may be embodied with various other changes, modifications and improvements.  
      For example, in the above-described embodiment, each of the projections is provided by the projecting plate projecting from the outer surface of the casing  1   a ,  1   b ,  1   c  and elongated along the outer surface of the casing  1   a ,  1   b ,  1   c . However, each of the projections may be provided by a conical projection projecting from the outer surface of the casing  1   a ,  1   b ,  1   c.    
      Further, while the ribs R are formed integrally with the lid member  1   a  and the vessel member  1   b  in the above-described embodiment, the ribs R may be bonded to the lid member  1   a  and the vessel member  1   b  after being formed independently of the lid member  1   a  and the vessel member  1   b.