Patent Publication Number: US-8529037-B2

Title: Ink tank and production process of ink tank

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ink tank for storing an ink used in an ink jet recording apparatus and a production process for the ink tank. 
     2. Description of the Related Art 
     An ink tank used in an ink jet recording apparatus is constructed detachably from the recording apparatus to facilitate replacement when ink has been consumed. 
     Such an ink tank has a casing  501  storing an ink and a joint member  502  for joining the tank to a recording apparatus body like an ink tank  500  described in Japanese Patent Application Laid-Open No. 2009-298153 and illustrated in, for example,  FIG. 7 . The ink tank  500  is fixed by welding an outer peripheral edge of the joint member  502  to the casing  501  of the ink tank. 
     As described above, the joint member of the conventional ink tank forms a “weld ridgeline” along the outer peripheral edge by being welded at its outer peripheral edge, so that the “weld ridgeline” tends to become long as the size of the ink tank becomes large. 
     However, when an engaged portion with a connection member of the recording apparatus is arranged in the inside of the “weld ridgeline” with the outer peripheral edge of the joint member regarded as the “weld ridgeline” as described above, the reliability of seal property at a welding portion is lowered as the length of the outer peripheral edge forming the “weld ridgeline” becomes long when the ink tank is enlarged. The lowering of the reliability of seal property at the welding portion may cause such a problem that it cannot withstand impact upon falling to cause ink leakage. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to maintain reliability of seal property of an ink tank without lengthening the length of a weld ridgeline even when the ink tank is enlarged. 
     The above object is achieved by the present invention described below. More specifically, the present invention provides an ink tank for being installed in an ink jet recording apparatus to supply an ink to the ink jet recording apparatus, the ink tank comprising an ink storage portion storing the ink; one side surface of a casing of the ink tank in which side surface an opening for supplying the ink to the ink jet recording apparatus is formed; and a joint member for joining the one side surface to the ink jet recording apparatus be engaging with a connection member of the ink jet recording apparatus, wherein the joint member has a welding portion for being welded to the one side surface along a peripheral portion of the opening, the welding portion corresponding to the peripheral portion; and a hollow portion forming a positioning hole for inserting therein and engaging therewith the connection member for positioning of determining a relative position of the ink jet recording apparatus and the one side surface which are to be joined to each other, and wherein the hollow portion is provided on the outside of the welding portion and abuts to the one side surface without being welded. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of an ink tank according to an embodiment of the present invention, and  FIG. 1B  is an exploded perspective view of the ink tank. 
         FIG. 2  is an enlarged view of a portion  2  illustrated in  FIG. 1B  in a joint member. 
         FIG. 3  is a typical sectional view taken along line  3 - 3  of the ink tank in  FIG. 1A . 
         FIG. 4  typically illustrates an engaged state between the ink tank according to the embodiment and a recording apparatus. 
         FIGS. 5A ,  5 B and  5 C typically illustrate a process of welding the joint member to a casing of the ink tank in the embodiment. 
         FIG. 6  illustrates a heating step for welding the joint member in the embodiment. 
         FIG. 7  is a perspective view illustrating a conventional ink tank. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings. 
     Construction of Ink Tank 
     The construction of the ink tank according to this embodiment is described with reference to  FIGS. 1A and 1B .  FIG. 1A  is a perspective view of the ink tank according to this embodiment, and  FIG. 1B  is an exploded perspective view of the ink tank. 
     As illustrated in  FIG. 1B , the ink tank is mainly constructed by a casing  110  storing an ink, a joint member  120  joining to a recording apparatus body and a cover  180  for protecting the joint member  120 . The ink tank is detachably installed in the recording apparatus by the joint member  120 . 
     Incidentally, regarding the recording apparatus body, only a connection member connected to the ink tank is illustrated, and the construction of the body is not illustrated. 
     As illustrated in  FIG. 3 , a connection unit  200  of the recording apparatus is provided with a connection member  202  (connection member for positioning) for determining a relative position with respect to the ink tank upon installation of the ink tank and an ink supply needle  201  to be inserted into an opening  111  for supplying an ink in the ink tank. 
     The ink supplied to the recording apparatus by the ink supply needle  201  from the ink tank is ejected from an ink ejection head (not illustrated) of the recording apparatus toward a recording medium to form a recorded image on the recording medium. 
     Main constructive members of the ink tank will hereinafter be described in detail. 
     Casing  110 : 
     The casing  110  is a container capable of directly storing a liquid such as an ink and produced by blow molding. As a resin forming the casing  110 , polyethylene is used in this embodiment. However, any resin such as polypropylene may also be used so far as it is not dissolved out in an ink. 
     As illustrated in  FIG. 1B , the casing  110  forms an ink storage portion  100  for storing an ink and has an opening  111  for supplying the ink stored in the ink storage portion  100  on one side surface on a side for being connected to the recording apparatus. The casing  110  further has a rib  111   a  projecting from a side surface toward the side of the recording apparatus for welding to the joint member  120  at a peripheral edge of the opening  111 . 
     Joint Member  120 : 
     The joint member  120  is a member produced by injection molding and is formed of polyethylene as in the molding of the casing  110  in this embodiment. Incidentally, regarding the resin used in this production, polypropylene or any other resin may also be used as in the molding of the casing  110 . However, the same resin as in the casing  110  is favorably used. 
     The same resin as in the casing  110  is used to weld the casing  110  to the joint member  120  by a production process which will be described subsequently, thereby inhibiting an interface between different resins from causing a rip to cause cracking. 
     As illustrated in  FIG. 1B , an information memory medium  170  for storing information on the ink stored in the ink storage portion, such as physical properties of the ink and the amount of remaining ink, to enables information transmission to the outside is installed in the joint member  120 . 
     A first feature of the technical points in this embodiment is to weld the joint member  120  to the casing  110  at a peripheral edge of the opening  111  formed in one side surface of the casing  110  for supplying an ink.  FIG. 3  typically illustrates the ink tank in cross section taken along line  3 - 3  in  FIG. 1A  and the connection unit  200  of the recording apparatus engaged with this ink tank. The joint member  120  has a substantially circular welding portion  121  corresponding to the rib  111   a  provided at a peripheral portion of the opening  111  and is welded to one side surface of the casing  110  at the welding portion  121  to form a substantially circular “weld ridgeline”. 
     The joint member  120  welded to the casing  110  forms an ink supply portion  122  that is an ink supply portion for supplying an ink stored in the ink storage portion  100  on the inside of the “weld ridgeline” formed in the substantially circular form. Here, “inside” means an interior of a circle of the weld ridgeline formed in the substantially circular form, and “outside” means an exterior of the circle. 
     With the first feature of the technical points in this embodiment, the joint member  120  is provided with a positioning hole  123  for inserting the connection member  202  for positioning of determining a relative position of the recording apparatus and the ink tank on the outside of the “weld ridgeline” formed by the substantially circular welding portion  121 . 
     Incidentally, one of the two positioning holes ( 123 ,  124 ) illustrated in  FIG. 1B  is illustrated in  FIG. 3 . However, the same construction as described above is also provided on the side of the positioning hole  124 . 
     As illustrated in  FIG. 3 , the positioning hole  123  is arranged on the outside of the “weld ridgeline” formed by the weld portion  121  of the joint member  120 . 
     A second feature of the technical points in this embodiment is that the one forming the positioning hole  123  in the joint member  120  abuts to one side surface of the casing  110  without being welded. Specifically, an end portion  123   d  of a hollow portion forming the positioning hole  123  is melted and deformed, thereby forming an abutting surface with respect to the one side surface of the casing  110 . However, it abuts to the one side surface in a non-welded state. 
     The end portion  123   d  of the hollow portion forming the positioning hole  123  is not fixed to the casing  110  as described above, thereby inhibiting the ink tank from being cracked by mechanical stress applied to the ink tank due to mutual rubbing between an inner side surface of the positioning hole  123  and an outer side surface of the connection member  202  when the connection member  202  is inserted into the positioning hole  123  upon installation of the ink tank in the recording apparatus. 
     As described above, in this embodiment, the joint member  120  is welded to the casing  110  of the ink tank along the peripheral edge of the opening  111  for supplying the ink to form the “weld ridgeline” along the opening  111 , whereby the positioning hole  123  is arranged on the outside of the “weld ridgeline”. In addition, the end portion  123   d  of the hollow portion forming the positioning hole  123  abuts to the casing  110  without being welded. By such construction, the peripheral length of the opening  111  becomes the whole length of the “weld ridgeline”, whereby the length of the “weld ridge” can be shortened, and the breakage of a connection portion caused by rubbing with the connection member  202  for positioning to be inserted into the positioning hole  123  can be inhibited. 
     More specifically, by the construction like this embodiment, the length of the “weld ridgeline” can be minimized even in an enlarged large-volume ink tank, the breakage that forms a cause of ink leakage can be inhibited, and the seal property of the ink tank can be improved. 
     The ink supply portion  122  provided on the inside of the “weld ridgeline” is provided with a cylindrical frame  135  formed in the joint member  120 . The frame  135  is arranged in the interior of the ink storage portion  100  so as to extend in the inward of the opening  111 . 
     In the frame  135 , a first opening opened on the side of the recording apparatus for communicating with the joint member  120  is formed, and a second opening for communicating the interior of the frame  135  with the interior of the ink storage portion  100  is formed in a cylinder side surface of the frame  135 . A spring  130 , a valve  140  and a seal member  150  that form a valve mechanism capable of opening and closing the opening  111  are incorporated into the interior of this frame  135 . 
     As illustrated in  FIG. 3 , the valve  140  is biased by the spring  130  for closing a hole of the seal member  150  within the frame  135  when the ink tank is not connected to the recording apparatus body, so that the valve  140  is pressed against the seal member  150 . 
     A cap  160  is put on the seal member  150  so as to prevent coming off of the seal member  150  by the force of the spring  130  as described above, whereby the seal member  150  is fixed. An opening through which the ink supply needle  201  is inserted is formed in the center of the cap  160 . 
     The seal member  150  is fixed to the joint member  120  in this manner, and the valve  140  is surely pressed against the seal member  150 , whereby ink leakage from the casing  110  and denaturalization of the ink caused by evaporation are suppressed. 
       FIG. 2  is an enlarged view of the portion  2  that is the positioning hole  123  illustrated in  FIG. 1B . As illustrated in  FIG. 2 , the connection member (portion indicated by the dotted line) for positioning on the side of the recording apparatus to be engaged with the positioning hole  123  is columnar in this embodiment as illustrated in  FIG. 2 . On the other hand, the opening of the positioning hole  123  is set to be a substantially circular form slightly larger than the connection member  202  for positioning for the purpose of reducing rubbing resistance with the connection member  202  for positioning on the side of the recording apparatus. 
     Cover  180 : 
     As illustrated in  FIG. 1B , a cover  180  is installed on the side where the joint member  120  of the casing  110  is welded. The cover  180  favorably does not abut on the outer peripheral portion of the joint member  120  in such a manner that no falling impact is directly applied to the ink supply portion  122  and positioning hole  123  of the joint member  120  even when the side of the cover  180  is impacted on a floor upon falling of the ink tank. Ink leakage and misalignment of the positioning hole  123  are thereby inhibited. 
     Installation of Ink Tank in Recording Apparatus 
     A manner that the ink tank  1  is installed in the recording apparatus body is described with reference to  FIG. 4 .  FIG. 4  typically illustrates an enlarged state between the ink supply portion  122  and positioning hole  123  of the joint member  120  in the ink tank and the connection unit  200  of the recording apparatus body that is engaged therewith. 
     As illustrated in  FIG. 4 , the connection unit  200  on the side of the recording apparatus is provided with a connection member  202  for positioning to be inserted into the positioning hole  123  of the joint member  120  and an ink supply needle  201  to be inserted into the ink supply portion  122  for supplying an ink from the ink tank to the recording apparatus. In addition, the connection unit  200  is also provided with a connection member  202  (not illustrated) for positioning to be engaged with the positioning hole  124  (see  FIG. 1B ). Two connection members  202  for positioning that are located side by side along a horizontal direction are inserted into their corresponding positioning holes  123  and  124 , whereby a relative position of the ink tank to the recording apparatus is determined, and the ink supply needle  201  is also surely inserted into the ink supply portion  122 . Incidentally, the positioning hole  124  has the same structure as the positioning hole  123 , so that it will hereinafter be described as the positioning hole  123 . 
     The positioning hole  123  has a portion forming a hollow portion as an insertion space  123   a  into which the connection member  202  for positioning is inserted, and a bumping-receiving portion  123   b  with which the connection member  202  for positioning inserted into the hollow portion bumps to be positioned. On the other hand, the connection member  202  for positioning has an insertion portion  202   a  to be inserted into the hole of the insertion space  123   a  and a bumping portion  202   b  formed with a diameter larger than the insertion portion  202   a  and bumped against the bumping-receiving portion  123   b  to be positioned. The positioning hole  124  also has the same structure as the positioning hole  123 . 
     When the ink tank is installed in the recording apparatus in a direction indicated by the arrow in  FIG. 4 , the insertion portion  202   a  of the connection member  202  for positioning on the side of the recording apparatus is engaged with the insertion space  123   a  in the positioning hole  123  of the joint member  120 , thereby determining the relative positions of the ink tank and the recording apparatus. 
     The positioning hole  123  abuts to the one side surface of the casing  110 , thereby being supported at a predetermined position, so that the connection member  202  for positioning is inserted into the positioning hole  123  to engage them with each other, whereby the ink tank is positioned to the recording apparatus with sufficiently good accuracy. 
     Welding Process of Joint Member  120   
     Some processes for welding the joint member  120  to the casing  110  are exemplified. 
     Welding Process  1  of Joint Member: 
     An example of a process for welding the joint member  120  to the casing  110  is described with reference to  FIGS. 5A to 5C . 
       FIGS. 5A to 5C  typically illustrate a process of welding the joint member  120  to the casing  110  of the ink tank, in which  FIG. 5A  illustrates a state where the joint member  120  and the casing  110  are heated,  FIG. 5B  illustrates a state where the joint member  120  is pressed against the casing  110 , and  FIG. 5C  illustrates a state after welding. Incidentally, only the positioning hole  123  of the  2  positioning holes illustrated in  FIG. 1B  is illustrated. However, the positioning hole  124  also takes the same state as in the following description. 
     As illustrated in  FIG. 5A , the joint member  120  has a projection portion  123   c  having a wall thinner than that of another portion of the positioning hole  123  at an end portion of the insertion space  123   a  of the positioning hole  123 . 
     The casing  110  is fixed with its side on which the rib  111   a  is provided upward, and the joint member  120  is held over it. In this arrangement, the joint member  120  is held by a holding part  400  as illustrated in  FIG. 5A , the welding portion  121  of the joint member  120  and the rib  111   a  of the casing  110  are heated by a heater block  300 , and at the same time the projection portion  123   c  of the positioning hole  123  is heated by another heater block  301 . 
     In this manner, heaters for melting are separately provided on a side where the welding portion  121  and the rib  111   a  are melted and on a side where the projection portion  123   c  of the positioning hole  123  is melted, whereby the heating temperatures on both sides can be controlled separately. By such construction, the heating temperature of the projection portion  123   c  can be made higher than the heating temperature of the welding portion  121 , and so the projection portion  123   c  can be sufficiently melt-deformed. The projection portion  123   c  is sufficiently melted in this manner, whereby the form of the projection portion  123   c  is easily deformed when the welding portion  121  is welded and joined to the rib  111   a  with the descending of the holding part  400  in a vertical direction as illustrated in  FIG. 5B , so that the cumulative height C of the melt-deformed projection portion  123   c  and the insertion space  123   a  as illustrated in  FIG. 5C  can be precisely controlled. 
     In this embodiment, the welding portion  121  and the projection portion  123   c  of the joint member  120  and the rib  111   a  of the casing  110  are not brought into contact with the heater blocks  300  and  301  for avoiding adhesion of the resin to the heater blacks  300  and  301  and are heated with radiant heat. However, the heater blocks  300  and  301  are coated in order for the resin not to adhere thereto, and the welding portion  121  and the projection portion  123   c  of the joint member  120  and the rib  111   a  of the casing  110  may be brought into contact with the heater blocks  300  and  301  to heat them. 
     The heating temperature may be set to a temperature not lower than the melting point of the resin, and the heating time may be set to a time required to sufficiently melt the resin according to the heating temperature. When the heating temperature is made sufficiently higher than the melting point of the resin, the heating time required for the melting can be shortened, so that the process time can be shortened. 
     In this embodiment, the heating temperature of the welding portion  121  and the rib  111   a  is set to 450° C., the heating temperature of the projection portion  123   c  is set to 480° C., the heating time of the rib  111   a  by the heater blocks  300  and  301  is set to 10 seconds, and the heating time of the welding portion  121  and the projection portion  123   c  of the joint member  120  is set to 6 seconds. The reason why the heating time of the joint member  120  is shorter than the heating time of the casing  110  is that the radiation heat from the heater blocks  300  and  301  more easily travels to the joint member  120  than to the casing  110  because the joint member  120  is held above the heater blocks  300  and  301 . 
     Upon such heating, the distance between the projection portion  123   c  in the joint member  120  and the heater block  301  is favorably made sufficiently wide. The projection portion  123   c  in the joint member  120  does not come into direct contact with the heater block  301  by doing so, and a melted surface  123   d  formed is not sufficiently melted. In this embodiment, the distance between the heater block  301  and the melted surface  123   d  of the projection portion  123   c  in the joint member  120  is set to about 6.5 mm. The melted surface  123   d  of the projection portion  123   c  in the joint member  120  is thereby not heated to the melting point of polyethylene that is a raw material of the casing  110  and not sufficiently melted. 
     As illustrated in  FIG. 5B , the holding part  400  then descends toward the casing  110 , whereby the joint member  120  is pressed against the rib  111   a  of the opening  111  formed in the one side surface of the casing. As a result, the welding portion  121  of the joint member  120  and the rib  111   a  (see  FIG. 5A ) of the casing  110  are welded to each other because they are respectively melted. The melted surface  123   d  of the projection portion  123   c  abuts to the casing  110  without being welded because it is not sufficiently melted as described above. 
     In this embodiment, the welding portion  121  is cooled for 2 seconds after the holding part  400  has reached a descending end while retaining the state where the joint member  120  has been pressed against the casing  110  for the purpose of sufficiently welding the welding portion  121  and the rib  111   a  to each other. Thus, the welding portion  121  is cured in the state of being welded with the rib  111   a , and so sufficient strength is imparted to the welding portion  121 . 
     In the joint member  120 , the cumulative height C (see  FIG. 5C ) between the melted surface  123   c  and the insertion space  123   a , from the melted surface  123   d  of the projection portion  123   c  in the joint member  120 , becomes lower than the height A+B (see  FIG. 5A ) of the positioning hole  123  before the welding. 
     Welding Process  2  of Joint Member: 
     Another process for welding the joint member  120  to the casing  110  is then described. In this embodiment, a heater block  302  obtained by integrating a heater block on the side of the welding portion  121  with a heater block on the side of the positioning hole  123  is used for the purpose of simplifying the construction of the apparatus used in “Welding process  1  of joint member” described above, thereby heating them at an equal heating temperature. 
     In this embodiment, the projection portion  123   c  (see  FIG. 5A ) of the positioning hole  123  shown in Welding process  1  described above is made thinner than that used in Welding process  1  described above (see  123   e  in  FIG. 6 ). In short, the of the projection portion  123   e  has such a wall thickness and form as to be easily melt-deformed, compared with the projection portion  123   c  in Welding process  1  described above. The projection portion  123   e  can thereby be surely and easily melt-deformed so as not to affect the joint of the welding portion and the rib  111   a.    
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2011-021793, filed Feb. 3, 2011, which is hereby incorporated by reference herein in its entirety.