Patent Publication Number: US-6991325-B2

Title: Ink replenishing device, sub ink tank, and ink jet recording apparatus

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an ink replenishing device for replenishing ink to a sub ink tank of a recording head device and an ink jet recording apparatus having the ink replenishing device. 
   2. Description of the Related Art 
   In the ink jet recording apparatus in which an ink droplet is ejected on the basis of image information from a recording head to a recording medium such as paper to record an image, there is a configuration in which the sub ink tank corresponding to each recording head is mounted on a carriage scanning the recording head, various proposals regarding replenishing of ink to the sub-ink tank have been performed. 
   For example, as shown in  FIG. 21 , an ink replenishing tank  540 , having a tank holder  541  which rotates and descends as a stepper motor is rotated, is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 10-202897. In this structure, a valve  546  having a hole for replenishing the ink, which is held operatively upward and downward by the tank holder  541  and is pressed always downward by a spring  543 - 2 , contacts an ink replenishing opening  547  of an ink tank  516  mounted on a carriage  518 . When the tank holder  541  further descends, the valve  546  moves upward in an O-ring  550  press-fitted in a supply opening  549  of an ink bag  548 , a plug member  553  held oscillatably by the supply opening  549  of the ink bag  548  is pushed up by the valve  546  in the O-ring  550  portion. This allows the ink in the ink bag  548  to be replenished by a water head pressure depending on a water level of the ink into the ink tank  516  through the valve  546 . 
   However, in the configuration described above, the ink sometimes leaks from vicinities of the ink replenishing opening  547  and the plug member  553  by contacting and separating actions to the ink replenishing opening  547  of the valve  546 , movement of the plug member  553 , or the like. Particularly, when the plenty of ink replenishment is carried out, the leaked ink is accumulated to become a large quantity, which sometimes caused other portions of the ink jet recording apparatus or paper to be dirty. 
   SUMMARY OF THE INVENTION 
   In view of the fact described above, it is an object of the present invention to obtain an ink replenishing device which can surely prevent ink dirt caused by the ink replenishing and an ink jet recording apparatus provided with the ink replenishing device. 
   According to a first aspect of the invention, there is provided an ink replenishing device which replenishes ink from a main ink tank to a sub ink tank and in which, ink to be supplied to a recording head which ejects an ink droplet to a recording medium on the basis of image information being reservoired in the sub ink tank, comprising: a first connecting member which is provided in the main ink tank; a second connecting member which is provided in the sub ink tank and connected to the first connecting member to constitute an ink channel; a sealing member which brings the first connecting member and the second connecting member into close and sealing contact with each other in a connected state thereof; an opening and closing member which is provided in the second connecting member and able to open/close the ink channel; and opening means for opening the ink channel into the atmosphere by using the opening and closing member in a connecting operation of the first connecting member and the second connecting member. 
   The first connecting member may be provided directly in the main tank or provided through a tube or a pipe. 
   In the ink replenishing device, when the first connecting member and the second connecting member are connected to form the ink channel, the ink can be replenished from the main ink tank to the sub ink tank. Because the first connecting member and the second connecting member are closely or sealingly contacted by the sealing member, the ink leak is prevented during replenishing ink. 
   The opening and closing member is provided in the second connecting member, the ink channel is opened and closed by the opening and closing member. In the connecting operation of the first connecting member and the second connecting member, the ink channel is opened into the atmosphere by the opening and closing member. Generally, in the recording head (so-called ink jet recording head) ejecting the ink droplet to the recording medium on the basis of image information, since a negative pressure is maintained in the sub ink tank, when the ink channel is opened into the atmosphere as described above, the air is sucked into the sub ink tank by the negative pressure, and the ink which remains and adheres to in the vicinity of a connecting part is also sucked into an inside of the sub ink tank. This enables a decrease in an ink leakage near the connecting members and sure prevention of the ink dirt. 
   According to a second aspect of the invention, the ink channel is opened into the atmosphere by the opening means before the first connecting member and the second connecting member are brought into close contact with each other by the sealing member. As a result, after the ink which adheres to the vicinity of the connecting part is sucked into the sub ink tank, the first connecting member is closely contacted with the second connecting member, and the ink can be supplied from the main ink tank to the sub ink tank. 
   According to a third aspect of the invention, the opening means comprises a pressed portion which is provided in the opening and closing member and pressed by one of the first connecting member and the sealing member to move the opening and closing member to an opening position in the connecting operation. 
   According to a fourth aspect of the invention, the opening means comprises a pressing portion which is provided in one of the first connecting member and the sealing member and presses the opening and closing member to move the opening and closing member to a opening position in the connecting operation. 
   In either of the third and fourth features, the opening and closing member can be formed by a simple structure in which only the pressed portion or the pressing portion is provided. 
   According to a fifth aspect of the invention, the ink replenishing device having the above-described aspects further includes pressure reducing means for sucking air inside the sub ink tank, to reduce pressure inside the sub ink tank. 
   Accordingly, as the inside of the sub ink tank is actively pressure-reduced by the pressure reducing means to maintain the negative pressure, the ink replenishing to the sub ink tank or the ink suction from the vicinity of the connecting part can be carried out efficiently. 
   According to a sixth aspect of the invention, the sub ink tank for supplying the ink to the recording head which ejects the ink droplet to the recording medium on the basis of the image information, the sub ink tank comprising a connecting member which is connected with a main ink tank, in which the ink replenished to the sub ink tank is stored beforehand, to constitute an ink channel; and an ink holding member which is arranged in the vicinity of the connecting member outside thereof. 
   The main ink tank is connected to the sub ink tank by the connecting member, the ink stored in the main ink tank can be replenished to the sub ink tank. 
   The ink holding member is arranged in the vicinity of the connecting member outside thereof. Even if the ink is leaked from the connecting member (connecting part of the main ink tank and the sub ink tank), the leaked ink is held by the ink holding member, so that scatter and spread of the leaked ink can be prevented and the ink dirt can be surely prevented. 
   With respect to the ink holding member, it suffices as long as the ink holding member is able to hold the ink. For example, the ink holding member may be a shape of a container (for example, the shape of a dish or a boat) which can store the ink inside. 
   According to a seventh aspect of the invention, the ink holding member comprises a porous body which is made of a porous material and able to absorb ink. 
   It is preferable that the ink holding member includes such a porous body as described above because the ink is stably held by absorbing the ink in the porous body. 
   According to an eighth aspect of the invention, a sintered body formed by sintering powder of polyolefine resin may be used as the porous body. 
   According to a ninth aspect of the invention, the porous body may be formed by polyurethane foam. 
   According to a tenth aspect of the invention, the porous body may be formed by fibrous felt. 
   According to an eleventh aspect of the invention, there is provided an ink jet recording apparatus comprising: a recording head unit which is provided with the recording head which ejects an ink droplet to the recording medium on the basis of the image information and the sub ink tank in which ink supplied to the recording head is stored; the main ink tank in which the ink replenished to the sub ink tank is stored beforehand; and the ink replenishing device which replenishes ink from the main ink tank to the sub ink tank and has any one of the above-described first to fifth aspects. 
   According to the ink jet recording apparatus, the ink replenished from the main ink tank to the sub ink tank is ejected as the ink droplet to the recording medium by the recording head, and the image is recorded on the recording medium. 
   Because the ink jet recording apparatus has the ink replenishing device having any one of the first to fifth aspects, the ink leakage is decreased and the ink dirt can be surely prevented. 
   According to a twelfth aspect of the invention, the sub ink tank of the ink jet recording apparatus based on the eleventh aspect is the sub ink tank having any one of the sixth to tenth aspects. 
   The sub ink tank having any one of the sixth to tenth aspects has the ink holding member. Consequently, even in the case that the ink leaks out, the leaked ink is held by the ink holding member, and the ink dirt can be surely prevented. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view showing a recording head carriage of an ink jet recording apparatus having an ink replenishing device according to an embodiment of the present invention and the vicinity of the recording head carriage. 
       FIG. 2  is a plan view showing an ink replenishing device according to an embodiment of the invention. 
       FIG. 3  is a partially ruptured side view showing a schematic configuration of an ink replenishing device according to an embodiment of the invention. 
       FIG. 4  is a partially ruptured sectional view showing in enlarged dimension an ink replenishing unit of an ink replenishing device and a sub ink tank of an ink jet recording apparatus according to an embodiment of the invention. 
       FIG. 5  is a partially ruptured plan view showing in enlarged dimension an ink replenishing unit of an ink replenishing device and a sub ink tank of an ink jet recording apparatus according to an embodiment of the invention. 
       FIG. 6  is a partially ruptured plan view showing in enlarged dimension an ink replenishing unit of an ink replenishing device and a sub ink tank of an ink jet recording apparatus according to an embodiment of the invention with a positioning arm advanced. 
       FIG. 7  is a partially ruptured plan view showing in enlarged dimension an ink replenishing unit of an ink replenishing device and a sub ink tank of an ink jet recording apparatus according to an embodiment of the invention at a state of the ink replenishing unit on its way to advance. 
       FIG. 8  is a partially ruptured plan view showing in enlarged dimension an ink replenishing unit of an ink replenishing device and a sub ink tank of an ink jet recording apparatus according to an embodiment of the invention with the ink replenishing unit reached a supply position. 
       FIG. 9  is a sectional view showing a connecting part structure of a port for replenishing ink of an ink replenishing device and an ink replenishing port of an sub ink tank according to an embodiment of the invention. 
       FIGS. 10A to 10D  are sectional views showing in order a process which a port for replenishing ink of an ink replenishing device and an ink replenishing port of an sub ink tank according to an embodiment of the invention are connected. 
       FIG. 11  is a sectional view showing a connecting part structure of a port for exhausting of an ink replenishing device and an evacuating port of an sub ink tank according to an embodiment of the invention. 
       FIG. 12  is a partially ruptured side view showing a driving system for displacing an ink replenishing unit in an ink replenishing device according to an embodiment of the invention. 
       FIG. 13  is a partially ruptured side view showing a driving system for driving a pump unit in an ink replenishing device according to an embodiment of the invention. 
       FIG. 14  is a chart showing a relationship among an angle of a cam unit, a position of a positioning arm, and a position of an ink replenishing unit in an ink replenishing device according to an embodiment of the invention. 
       FIG. 15A  and  FIG. 15B  show a state which each ink replenishing unit has advanced to the corresponding ink replenishing position in an ink replenishing device according to an embodiment of the invention respectively.  FIG. 15A  shows the ink replenishing unit corresponding to black ink,  FIG. 15B  shows the ink replenishing unit corresponding to cyan ink. 
       FIG. 16A  and  FIG. 16B  show a state which each ink replenishing unit has advanced to the corresponding ink replenishing position in an ink replenishing device according to an embodiment of the invention respectively.  FIG. 15A  shows the ink replenishing unit corresponding to magenta ink,  FIG. 15B  shows the ink replenishing unit corresponding to yellow ink. 
       FIG. 17  is a timing chart showing a connecting condition of a port for replenishing ink of an ink replenishing device and an ink replenishing port of a sub ink tank according to an embodiment of the invention. 
       FIG. 18  is a sectional view showing aport for replenishing ink and a port for exhausting of an ink replenishing device according to an embodiment of the invention. 
       FIG. 19  is a sectional view showing aport for replenishing ink and a port for exhausting of an ink replenishing device according to an embodiment of the invention. 
       FIG. 20  is a perspective view showing a sub ink tank according to an embodiment of the invention. 
       FIG. 21  is an explanatory view showing an ink replenishing device of the related art. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  shows an ink jet recording apparatus  12  of a first embodiment of the present invention. Specifically,  FIG. 1  shows in enlarged dimension a vicinity of a recording head carriage  14  of the ink jet recording apparatus  12 . 
   The ink jet recording apparatus  12  is provided with a recording medium carrying member  16  which carries a recording medium P (for example, paper and the like) in a fixed direction and a pair of guiding members  18  which is provided along a direction perpendicular to a carrying direction of the recording medium P so as to face a carrying path of the recording medium P. The recording head carriage  14  is supported by these guiding members  18 . A maintenance station  20  is placed at a position which is under the guide member  18  and adjacent to the carrying path of the recording medium P, and the maintenance station  20  carries out a maintenance operation such as capping or suction of ink by contacting with and separating from the recording head carriage  14  (in the embodiment, moving upward and downward). The maintenance operation is controlled by a control circuit which is not shown so as to be carried out on predetermined conditions or timing. 
   A home position of the recording head carriage  14  is set at a position opposite to the maintenance station  20 , the position is detected by a position sensor  22 . The recording head carriage  14 , the recording medium carrying members  16 , the guiding member  18 , the maintenance station  20 , and the position sensor  22  are held by a main body of a housing  24 . The image information is transmitted to the recording head carriage  14  through a signal line which is formed on a flexible substrate. 
   In  FIG. 1 , a traveling direction of the recording head carriage  14  (main scanning direction) is represented by an arrow M, the traveling direction of the recording medium P is represented by an arrow S respectively. 
   As also shown in  FIGS. 2 to 4 , the recording head carriage  14  includes a recording head carriage frame  26  which is provided movably along the guiding member  18 , a plurality of recording heads  28  (in the embodiment, four recording heads) which is provided to project lower than a lower face (a face opposite to the carrying path of the recording medium P) of the recording head carriage frame  26  and in which an ejection port is formed, on a lower face, and a sub ink tank  30  supplying the ink to each recording heads  28  which is provided detachably to the recording head carriage frame  26 . The recording head  28  can be produced by, for example, micro-fabricating a silicon wafer. Also, resolution of the recording head  28  can-be set according to image quality, an image recording speed or the like which is required for the ink jet recording apparatus  12 , for example, the resolution can be set to about 600 dpi. 
   The number of the sub ink tanks  30  corresponds to the number of the recording head  28 , there are four sub ink tanks in the embodiment. Accordingly, the full color image can be recorded by supplying the different color ink (for example, black ink (Bk), yellow ink (Y), magenta ink (M), and cyan ink (C)) from each sub ink tank  30  to the corresponding recording head  28 , to eject the ink droplet. The recording head  28  and its corresponding sub ink tank  30  are formed integrally into a cartridge to be a recording head unit  32 , the recording head unit  32  is exchanged as a whole when, for example, the product life has been expired. Hereinafter, when the recording head  28 , the sub ink tank  30 , an ink replenishing unit  48  mentioned below, and the like are to be particularly distinguished according to each color, these numerals are indicated by adding Bk, Y, M, or C after the numerals. 
   As shown in  FIG. 1 , in the ink jet recording apparatus  12  of the invention, the recording medium P is carried by the recording medium carrying members  16 , and while the recording head carriage  14  is traveled reciprocally, the ink droplet is ejected according to the image information to record the image on the recording medium P. 
   As shown in  FIG. 4 , in the sub ink tank  30 , a partition  174  in which an ink communicating pore  176  is formed in the lower portion thereof is provided so that the sub ink tank  30  is divided into a first ink chamber  178  and a second ink chamber  180 . A capillary member  182  is accommodated in the first ink chamber  178 , the ink is held in the capillary member  182 . In contrast, the ink is accommodated with a free state in the second ink chamber  180 . The ink in the second ink chamber  180  is supplied to the recording head  28  (manifold) through an ink communicating portion at a bottom face. A filter is placed in the ink communicating portion (i.e., an upper face portion of the recording head  28 ), so as to prevent invasion of foreign matter from the second ink chamber  180  to the recording head  28 . 
   AS shown in  FIG. 3 , a port for exhausting  34  having an exhaust opening  42  which can exhaust the air in the sub ink tank  30  and a port for replenishing ink  36  being placed below the port for exhausting  34  and having an ink replenishing opening  44  through which the ink can be replenished into the sub ink tank  30  are provided in each of the sub ink tanks  30 . In the sub ink tank  30 , an atmosphere communicating opening  38  through which the air is flown between an inside and an outside of the first ink chamber  178  is formed above the port for exhausting  34 . The sub ink tank  30  is also provided with an ink quantity sensor  40  which detects ink quantity of an inside of the second ink chamber  180 . The ink quantity sensor  40  sends the detected information of the ink quantity in the second ink chamber  180  to a control circuit which is not shown. A specific configuration of the ink quantity sensor  40  is not particularly limited, but, in the present embodiment, there is adopted a structure which includes a light emitting diode, a phototransistor (neither the light emitting diode nor the phototransistor are shown), and a prism  40 P. In the ink quantity sensor  40 , a reflection surface of the prism  40 P is designed to constitute a total reflection surface to incident light. The liquid level is detected on the basis of the result of whether the light from the light emitting diode and incident on the prism  40 P impinges on the phototransistor through the prism  40 P. That is, when the ink exists on the reflection surface of the prism  40 P inside the second ink chamber  180 , the incident light transmits the sub ink tank and is not reflected. In contrast, when the ink level falls lower than the reflection surface of the prism  40 P, the light is reflected by the reflection surface to impinge on the phototransistor, so that a small quantity of ink can be detected. In the ink quantity sensor  40  of the present embodiment, only the prism  40 P is provided in the sub ink tank  30 , and other components except the prism  40 P (a main body of the sensor such as the light emitting diode and the phototransistor) are placed in the main body of the ink jet recording apparatus  12 . Accordingly, when the ink quantity is detected, the recording head carriage  14  is moved by a predetermined distance so that the prism  40 P faces to the front of the main body of the sensor. Since, by adopting the configuration described above, it is not necessary to mount the main body of the sensor on the sub ink tank  30 , the weight of the sub ink tank  30  can be significantly reduced. It is also possible to integrally form the prism  40 P with the same material as the sub ink tank  30 . The number of parts can also be decreased by commonly forming the main body of the sensor with the prism  40 P of each sub ink tank  30 . In this case, it is recommended that the desired prism  40 P faces to the front of the main body of the sensor by adjusting movement of the recording head carriage  14 . 
   In the recording head unit  32 , in a state before being used in service, the ink is filled in the first ink chamber  178 , the second ink chamber  180  and the recording head  28 , and a constant negative pressure is maintained in the sub ink tank  30 . When the ink is consumed by the image recording, the ink is supplied from the first ink chamber  178  to the second ink chamber  180  through the ink communicating pore  176  while the air is supplied from the atmosphere communicating opening  38  to the first ink chamber  178 . Then, when the ink which has been impregnated into the capillary member  182  in the first ink chamber  178  is almost spent and the air has reached the ink communicating pore  176 , the air is supplied from the first ink chamber  178  to the second ink chamber  180  through the ink communicating pore  176 . Since the air is introduced in the shape of a bubble from the ink communicating pore  176  into the second ink chamber  180 , the pressure (negative pressure) in the second ink chamber  180  is controlled within a constant range by the bubble generating pressure at this time. 
   In this way described above, the ink level is gradually fallen by introducing the air in the second ink chamber  180  according to the ink consumption. It is detected by the ink quantity sensor  40  that a position of the ink level falls, that is, the ink quantity in the sub ink tank  30  becomes a small amount. 
   The type of a material constituting the sub ink tank  30  is not limited as long as the material has ink resistance to ink and satisfies predetermined conditions of moisture permeability and gas permeability. For example, when PPO (polyphenylene oxide) is used for the sub ink tank  30 , the moisture permeability and the gas permeability can be sufficiently suppressed. Regarding the material of the capillary member  182  in the first ink chamber  178 , a material which can hold the ink by the capillary attraction and has the resistance to ink can be used. For example, polyurethane foam is preferable to the capillary member because the polyurethane foam can adjust the capillary attraction by a change in density and has the good resistance to ink. And other materials such as porous polymer foam (so-called melanin) and felt made of polyester resin, polypropylene, acryl or the like may be used, as long as the material can properly generate the capillary attraction between the ink and has the resistance to ink. 
   As shown in  FIG. 1 , an ink replenishing device  46  comprising a plurality of ink replenishing units  48  (there are four ink replenishing units in the present embodiment) for replenishing the ink to the corresponding sub ink tanks  30  are mounted in the main body of the housing  24 , a position where the ink can be replenished to the sub ink tank  30  by the ink replenishing unit  48  is set to an ink replenishing position of the recording head carriage  14 . In the same as the home position, the ink replenishing position is also detected by the position sensor  22 . The ink replenishing position may be the same position as the home position, however, in the embodiment, the ink replenishing position differs from the home position in position. 
   As shown in  FIG. 2  and  FIG. 3 , a main ink tank  50  is arranged below the ink replenishing device  46 . In the main ink tank  50 , the ink which is used by the ink jet recording apparatus  12  is stored beforehand, and the ink is replenished to the sub ink tank  30  by the ink replenishing device  46  to be used for the image recording. The main ink tank  50  is arranged to at least partially overlap with the ink replenishing device  46  in a plan view (substantially, across the whole in the present embodiment), so that the size of the ink jet recording apparatus  12  is reduced as a whole. 
   An atmosphere communicating opening, which is not shown in the drawings, is formed in the main ink tank  50 . The atmosphere communicating opening is closed by a valve, which is not shown, either, in a state in the main ink tank  50  has not yet been attached to the ink jet recording apparatus  12 . Consequently, an airtight structure is maintained in the main ink tank  50  and ink is not carelessly leaked out. 
   When the main ink tank  50  is attached to the ink jet recording apparatus  12 , the valve is pressed by a projection of the ink jet recording apparatus to be separated from a gasket of the atmosphere communicating opening, and the main ink tank  50  is communicated with the atmosphere. This allows the ink in the main ink tank  50  to be stored in the free state. 
   Similarly to the case of the sub ink tank  30 , whatever a material having the resistance to ink and satisfying given conditions in terms of the moisture permeability and the gas permeability may be used as the material configuring the main ink tank  50  (particularly a portion which is brought into contact with the ink such as a box-shaped portion). For example, the main ink tank  50  can be made of polypropylene resin. Like the sub ink tank  30 , the PPO (polyphenylene oxide) may be used for the main ink tank  50 . 
   As shown in detail in  FIG. 4  and  FIG. 5 , the ink replenishing device  46  has a stationary frame  52  which is integrally fixed to the main body of the housing  24  of the ink jet recording apparatus  12 , and a guide frame body  54  is arranged in the stationary frame  52 . A given gap  56  is formed between the stationary frame  52  and the guide frame body  54  in the widthwise direction. In the stationary frame  52 , the guide frame body  54  is movable within a given range in the same direction as the moving direction (main scanning direction) of the recording head carriage  14 . A helical compression spring  58  is placed in the gap  56 , such that the guide frame body  54  is held at about center in a widthwise direction in the stationary frame  52 . Hereinafter, the term “the widthwise direction” will represent the same direction as the widthwise direction of the guide frame body  54 . The “widthwise direction” corresponds to the main scanning direction (in the direction of the arrow M) of the recording head carriage  14 . 
   In the vicinity of both ends in the widthwise direction of the guide frame body  54 , a pair of positioning arms  60  are provided such that the positioning arms  60  are slidable toward the recording head carriage  14 . As shown in  FIGS. 2 and 3 , the positioning arms  60  are located so as not to contact the recording head carriage  14  in a normal state. A distance between both inside faces  60 A (opposite surfaces) of the positioning arms  60  is set to be equal to a width of a recording head carriage frame  26  of the recording head carriage  14 . 
   As shown in  FIGS. 2 and 5 , in the positioning arm  60 , a tapered face  62  which is cut obliquely relative to the recording head carriage  14  is formed at an end portion of a recording head carriage  14  side. As shown by a solid line in  FIG. 2 , in the case that the recording head carriage  14  is shifted to the guide frame body  54  in the widthwise direction while the recording head carriage  14  is stopped at the ink replenishing position (the recording head carriage frame  26  at a normal position is shown by a dash-double dot line in  FIG. 2 ), either of the tapered faces  62  of the positioning arms  60  contacts a corner portion of the recording head carriage frame  26  when the positioning arms  60  approaches the recording head carriage  14 . As a result, the movement of the positioning arms  60  in this approaching direction is converted into the movement in the widthwise direction of the guide frame body  54 , when the positioning arm  60  further approaches to the recording head carriage  14 . This allows the guide frame body  54  to move in the widthwise direction against elastic force of the helical compression spring  58  (one of the gaps  56  between the stationary frame  52  and the guide frame body  54  are extended and the other is narrowed). When the positioning arm  60  further approaches the recording head carriage  14 , as shown in  FIG. 5 , a side face  26 S of the recording head carriage frame  26  is made into contact with an inside face  60 A of the positioning arm  60 , and the recording head carriage  14  and the guide frame body  54  are correctly positioned in the widthwise direction. Consequently, four ink replenishing units  48  are integrally positioned to the corresponding sub ink tanks  30 . 
   As shown in  FIGS. 5 and 6 , the inside of the positioning arm  60  is adapted to function as a pressing piece accommodating portion  64 , and a portion of a pressing piece  66  accommodated in the pressing piece accommodating portion  64  projects from the inside face  60 A of the positioning arm  60 . The pressing piece  66  is slidable inside the pressing piece accommodating portion  64 , and the pressing piece  66  is urged toward a direction of approaching the recording head carriage  14  by the helical compression spring  68 . In a state in which the side face  26 S of the recording head carriage frame  26  has been brought into contact with the inside face  60 A of the positioning arm  60  and the recording head carriage  14  and the guide frame body  54  have been correctly positioned in the widthwise direction, when the positioning arm  60  further advances toward the recording head carriage  14 , as shown in  FIG. 6 , the pressing piece  66  which receives biased force of the helical compression spring  68  presses the recording head carriage  14 . Consequently, the recording head carriage  14  is held tight between the pressing piece  66  and the guide member  18 , and play of the recording head carriage  14  is prevented. 
   In the guide frame body  54 , the ink replenishing units  48  are provided corresponding to the four sub ink tanks  30 . Each of the ink replenishing units  48  is independently slidable within an accommodating portion  70  provided in the guide frame body  54 , so that the ink replenishing units  48  approach and separate from the corresponding sub ink tank  30 , respectively. As can be seen from  FIG. 1 , a travelling area within which the ink replenishing units  48  approach or separate from the recording head carriage  14  (corresponding sub ink tank  30 ) is arranged so as not to overlap with the moving area withiin which the maintenance station  20  approaches or separates from the recording head carriage  14 . Accordingly, when either the ink replenishing unit  48  or the maintenance station  20  approaches or separates from the recording head carriage  14 , the other is not required to take shelter. 
   As shown in  FIGS. 3 and 4 , on a face of each of the ink replenishing units  48 , which is opposite to the sub ink tank  30 , a port for exhausting  74  is provided at a position corresponding to the exhaust opening  42  of the sub ink tank  30  and a port for replenishing ink  76  is provided at a position corresponding to the ink replenishing opening  44  of the sub ink tank  30 , respectively. The port for exhausting  74  is connected to the exhaust opening  42  and the port for replenishing ink  76  is connected to the ink replenishing opening  44 , respectively, as a result of the ink replenishing units  48  moving toward the sub ink tank  30 . 
   Each of the ink replenishing units  48  is provided with a cap  72  at a position corresponding to the atmosphere communicating opening  38  of the sub ink tank  30 . The shape, mounted position, and the like of the cap  72  are set in a manner that, when the ink replenishing unit  48  has approached the sub ink tank  30 , the port for exhausting  74  is connected to the exhaust opening  42 , the port for replenishing ink  76  is connected to the ink replenishing opening  44  and thereafter the ink replenishing unit  48  further approaches the sub ink tank  30  thereafter, the atmosphere communicating opening  38  is then sealed by the cap  72  to obstruct the communication of the air between the inside and the outside of the sub ink tank  30 . 
   A positioning pin  78  is provided to be projected from the ink replenishing unit  48  toward the sub ink tank  30 . On the other hand, in the sub ink tank  30 , a positioning port  80  is provided at a position corresponding to the positioning pin  78 . The positioning pin  78  includes a columnar positioning portion  82  having a predetermined outer diameter and a guide portion  84  which is formed in the shape of a cone and provided at the tip end side of the positioning portion  82 . The outer diameter of the positioning portion  82  is substantially equal to an inner diameter of the positioning port  80 . When the ink replenishing unit  48  approaches the sub ink tank unit  30 , the guide portion  84  of the positioning pin  78  on the tip end side enters the positioning port  80 . Since the guide portion  84  is formed to be the taper shape, even if a center of the positioning pin  78  is shifted relative to the center of the positioning port  80 , the positioning pin  78  enters the positioning port  80 . As the ink replenishing unit  48  further approaches the sub ink tank  30 , the positioning pin  78  and the positioning port  80  are gradually moved by the guide portion  84  to a direction in which the center of the positioning pin  78  and the center of the positioning port  80  coincide with each other. Furthermore, when the positioning portion  82  reaches the positioning port  80 , the center of the positioning pin  78  coincides with the center of the positioning port  80 , whereby the ink replenishing units  48  and the sub ink tank  30  are correctly positioned, respectively. 
   As shown in  FIGS. 3 to 5 , a gap  86  of a predetermined width is formed between an upper face, a bottom face, and both side faces of the ink replenishing unit  48  and the upper face, the bottom face, and both the side faces in the accommodating portion  70  for accommodating the ink replenishing units  48 . A guide pin  88  projects from each of the aforementioned faces of the ink replenishing units  48 . Each guide pin  88  is accommodated in a guide groove  90  which is formed at each face of the accommodating portion  70 . 
   As can be seen from  FIG. 4 , a holding portion  90 A which is slightly wider than the outer diameter of the guide pin  88  and a width-wide portion  90 B whose width is gradually increased in the vicinity of each end portion near the sub ink tank  30  are formed in the guide groove  90 . The position of the width-wide portion  90 B is set such that the guide pin  88  exists in the width-wide portion  90 B in a state in which the ink replenishing units  48  have approached the sub ink tank  30  and the positioning pin  78  has entered the positioning port  80 . Accordingly, in a state in which the positioning pin  78  has not entered the positioning port  80 , the guide pin  88  travels in the holding portion  90 A and the ink replenishing units  48  slides without play in the accommodating portion  70 . Then, in a state in which the positioning pin  78  has entered the positioning port  80 , as the guide pin  88  has reached the width-wide portion  90 B and the gap is formed between the guide pin  88  and the width-wide portion  90 B, the ink replenishing units  48  can move within a predetermined range in up and down directions and the widthwise direction in the accommodating portion  70 . Accordingly, in this state, that is, in the state in which the positioning pin  78  has entered the positioning port  80 , guidance of the ink replenishing units  48  by the guide pin  88  and guide groove  90  is substantially released, and then the correct positioning is carried out by the positioning pin  78  and the positioning port  80 . Furthermore, since the gap between the guide pin  88  and the width-wide portion  90 B is increased as the guide pin  88  closely approaches the sub ink tank  30 , the range where the ink replenishing units  48  can move in the up and down directions and the widthwise direction is also increased in accordance with the increase in the gap. 
   In the port for replenishing ink  76  which is provided in each ink replenishing unit  48 , as shown in  FIG. 9 , a pipe for replenishing ink  92  is provided. The pipe for replenishing ink  92  includes a main body of the pipe  94 , which main body is formed in substantially cylindrical shape as a whole. A communicating hole  96  for discharging the ink which is to be replenished to the sub ink tank  30  is formed in a tip end of the main body of the pipe  94 . The vicinity of the tip end portion of the main body of the pipe  94  is formed in the taper shape whose diameter is decreased in a direction of the tip end. 
   In the main body of the pipe  94 , valve body  98  is accommodated movably in the longitudinal direction thereof, and a bracket  102  is press-fitted into a back end side of the main body of the pipe  94  by way of an O-ring  100 . 
   The valve body  98  comprises a ring packing  104  formed by an elastic member, a packing holder  106  which holds the packing  104  and is slidable in the main body of the pipe  94 , and a helical compression spring  108  which is provided between the packing holder  106  and the bracket  102  and biases the packing holder  106  and the packing  104  in a direction toward the communication port  96 . Normally, the packing holder  106  and the packing  104  are urged by the helical compression spring  108  in the direction toward the communicating hole  96  and the packing  104  is press-attached to a periphery of the communicating hole  96 , whereby the communicating hole  96  is closed. However, as shown in  FIGS. 10C and 10D , when the packing holder  106  and the packing  104  slide against the urging force of the helical compression spring  108  to separate from the periphery of the communicating hole  96 , the ink can be flown. 
   A valve abutting portion  110  is formed to be projected from the packing holder  106 . The valve abutting portion  110  penetrates the packing  104  and the tip end thereof is exposed from the communicating hole  96 , so that the tip end of the valve abutting portion  110  is pressed by a valve projection portion  122  described later. 
   In the rear end of the bracket  102 , one end of a tube for replenishing ink  124  is connected by way of a cover  112 . As shown in  FIG. 3 , the other end of the tube for replenishing ink  124  is connected to the main ink tank  50  in which the ink to be used for the image recording is stored beforehand. Accordingly, the port for replenishing ink  76  (pipe for replenishing ink  92 ) is provided in the main ink tank  50  by way of the tube for replenishing ink  124 . AS described later, when the port for replenishing ink  76  is connected to the ink replenishing opening  44  of the sub ink tank  30 , an ink channel from the main ink tank  50  to the sub ink tank  30  is formed. The other end of the tube for replenishing ink  124  is connected to a lower portion of the main ink tank  50 , so that the ink in the main ink tank  50  can be used up without leaving any left-over ink therein. 
   A gasket  114  is placed inside the ink replenishing opening  44  of the sub ink tank  30  and held at a predetermined position by a gasket cover  112  so as not to be dropped out. A bulge  114 A which is bulged out in the shape of the ring is formed in an outer periphery of the gasket  114 . The bulge  114 A is press-attached to the inside face of the ink replenishing opening  44 , whereby flow of the ink or the air from the ink replenishing opening  44  is obstructed. Further, a lip portion  114 B which is projected in the shape of the ring in the radially-inner direction is also formed in the gasket  114 . As shown in  FIGS. 10C and 10D , the lip portion  114 B contacts the inserted main body of the pipe  94 , from the outside and along the full perimeter thereof, to obstruct at the gasket  114  the flow of the ink or the air through the outer surface of the pipe  94 . 
   A pressure ring  116  is provided to be projected from the gasket cover  112  toward the gasket  114 , so that, when the main body of the pipe  94  is inserted and extracted, deformation of the lip portion  114 B in the inserting and extracting direction is limited within a given range by the pressure ring  116 . Due to this, the lip portion  114 B is prevented from moving undesirably to become an obstacle against insertion and extraction or decreasing in the sealing property thereof to the outer periphery of the main body of the pipe  94 , when the main body of the pipe  94  is moved (insertion and extraction) in the ink replenishing opening  44 . 
   In the ink replenishing opening  44 , a valve  118  is placed further remote side than the gasket  114 . The valve  118  is normally urged by a helical compression spring  120  in the ink replenishing opening  44  and pressed to a ring-shaped projection portion  114 C, which is formed in the gasket  114 , to close the ink channel. However, as shown in  FIGS. 10C and 10D , when the valve  118  slides against the biasing force of the helical compression spring  120  to separate from the projection portion  114 C, the ink channel is formed. In the present embodiment, a spring constant of the helical compression spring  120  is set larger than that of the helical compression spring  108 . 
   A valve projection portion  122  is formed in a manner that the valve projection portion  122  projects from the valve  118  by way of a to-be-to-be-pressed piece  184   50  as to be opposite to the valve abutting portion  110  of the packing holder  106 . The pressed portion according to the invention is constituted of the to-be-pressed piece  184  and the valve projection portion  122 . When the main body of the pipe  94  is inserted into the ink replenishing opening  44 , as shown in  FIG. 10B , before the outer periphery of the main body of the pipe  94  contacts the lip portion  114 B, the tip end or nose of the valve abutting portion  110  contacts the nose of the valve projection portion  122  and the main body of the pipe  94  and the valve projection portion  122  press each other. This pressing force allows the valve body  98  and the valve  118  to be slid, which results in the formation of the ink channel. In the present embodiment, the spring constant of the helical compression spring  120  is set larger than that of the helical compression spring  108 . As shown in  FIG. 10B , at first the ink passage is formed in the main body of the pipe  94 , and then, as shown in  FIG. 10C , the ink channel is formed in the ink replenishing opening  44 . 
     FIG. 17  shows open/closed states of the atmosphere communicating opening  38  and the ink replenishing opening  44 , and timing of a sealing state of the outer peripheral portion of the main body of the pipe  94 . The case of the present embodiment is shown by the solid line in  FIG. 17 . In  FIG. 17 , the open/closed states of the ink replenishing opening in the case of comparative example  1  described later is shown by a dash line. Further, in  FIG. 17 , the open/closed states of the ink replenishing opening of another comparative example (comparative example 2), which does not correspond to the invention, is shown by the dash-double dot line. The comparative example 1 is an example in which the timing in starting to open the ink replenishing opening is later than that of the present embodiment (see the dash line), although the timing in the sealing of the outer periphery portion of the main body of the pipe is the same as the embodiment (see the solid line). The comparative example 2 is an example in which the timing in sealing the outer periphery portion of the main body of the pipe is earlier (see the dash-double dot line), although the timing in starting to open the ink replenishing opening is the same as the embodiment (see the solid line). In both of the comparative examples 1 and 2, the ink channel is formed after the outer peripheral portion of the main body of the pipe is sealed. In contrast, in the preset embodiment, at an initial stage of opening ink replenishing opening  44 , the outer periphery of the main body of the pipe  94  does not contact the lip portion  114 B, and the ink channel is arranged to be opened into the atmosphere. Accordingly, when the air is sucked through the gap between the outer peripheral portion of the main body of the pipe  94  and the lip portion  114 B due to the negative pressure in the sub ink tank  30 , the ink which remains in and adheres to the outer peripheral portion of the main body of the pipe  94  or the inside of the ink replenishing opening  44  is also simultaneously sucked into the sub ink tank  30 . Inserting operation of the main body of the pipe  94  continues after this absorption of the ink. Finally, as shown in  FIG. 10D , the outer peripheral portion of the main body of the pipe  94  is brought into close contact with the lip portion  114 B, and the ink replenishing unit  48  and the sub ink tank  30  are liquid-connected. At the same time, as can also be seen from  FIG. 17 , sucking operation of ink at the outer peripheral portion of the main body of the pipe  94  and at the inside of the ink replenishing opening  44  is also finished. In both the packing holder  106  and the valve  118 , communicating pores  106 D and  118 D are formed so that the flow of the ink is not obstructed during the liquid connection. 
     FIG. 18  shows the port for exhausting  74  and the exhaust opening  42 . As described later, the port for exhausting  74  and the exhaust opening  42  are used for exhausting the air in the sub ink tank  30 , and the ink is not flowed inside the port for exhausting  74  and the exhaust opening  42 . For this reason, in the port for exhausting  74 , the valve body  98  is not provided inside the main body of the pipe  94 . That is, while the communicating hole  96  of the main body of the pipe  94  is always opened, the valve abutting portion  110  which can press the valve projection portion  122  is provided at a portion of the main body of the pipe  94 . As can be understood when compared with the above-described valve  118  of the ink replenishing opening  44 , the to-be-pressed piece  184  is not formed at the valve  118  of the exhaust opening  42  and a projection length of the valve projection portion  122  is shortened by the length of the to-be-pressed piece  184 . Thus, the opening/closing timing of the exhaust opening  42  is the same as the opening/closing timing of the ink replenishing opening of the comparative example 1 shown by the dashed line in  FIG. 17 . Specifically, when the main body of the pipe  94  of the port for exhausting  74  is inserted into the exhaust opening  42 , the outer periphery of the main body of the pipe  94  is first brought into close contact with the lip portion  114 B, and then the valve abutting portion  110  presses the valve projection portion  122  to push the gasket  114 , so that a passage of the air is formed and the air in the sub ink tank  30  can be exhausted from the tube for exhausting  126 . Since the port for exhausting  74  and the exhaust opening  42  are of the same configurations as the port for replenishing ink  76  and the ink replenishing opening  44  shown in  FIG. 9  except for the features described above, the same component, member, and the like are indicated by the same numerals and signs in  FIG. 11  to abbreviate the description. 
   As shown in  FIGS. 18 to 20 , an ink absorber  186  including the porous material which can absorb the ink is placed below the gasket cover  112 . A bottom face of the ink absorber  186  is formed in the shape of a flat surface and placed in contact with a mounting face  30 S of the sub ink tank  30 . A recessed portion is formed at an upper face of the ink absorber  186 , such that a thick portion  186 A located more remote inside than the gasket cover  112  and a thin portion  186 U located more outer side of the gasket cover  112  are formed at the upper face of the ink absorber  186 . A step face  186 D between the thick portion  186 A and the thin portion  186 U contacts the gasket cover  112 , which prevents the accidental positional shift or the dropout of the ink absorber  186 . 
   As shown in  FIGS. 2 ,  12 , and  13 , the stationary frame  52  is provided with a drive motor  128  for driving the ink replenishing device  46 , a row of gears  130  for displacing the ink replenishing unit rotated by the driving force of the driving motor  128 , a row of gears  132  for driving the pump, a clutch unit  134  which changes transmission of torque to the row of gears  130  for displacing the ink replenishing unit or the row of gears  132  for driving the pump according to normal/reverse rotation of the drive motor  128 . 
   The clutch unit  134  includes an input side gear  138  which meshes with a driving gear  136  of the drive motor  128 , an oscillating arm  140  which is oscillatably arranged around a shaft of the input side-gear  138 , and an output side gear  142  which is mounted on a nose or tip end of the oscillating arm  140  and meshes with the input gear  138  to receive the torque. When the drive motor  128  rotates in the normal direction, as shown in  FIG. 12 , the oscillating arm  140  oscillates counterclockwise and the output side gear  142  meshes with the row of gears  130  for displacing the ink replenishing unit. In contrast, when the drive motor  128  reversely rotates, as shown in  FIG. 13 , the oscillating arm  140  is oscillated clockwise and the output side gear  142  meshes with the row of gears  132  for driving the pump. 
   As can be seen from  FIGS. 2 ,  3 , and  12 , a cam unit  144  which is rotated by the torque transmitted by the row of gears  130  for displacing the ink replenishing unit is placed in the stationary frame  52  so as to correspond to each ink replenishing unit  48  and positioning arm  60  (there are provided totally six cam units in the present embodiment) and integrally rotate with the same shaft. Each cam unit  144  includes a forward cam  146  which advances the corresponding ink replenishing unit  48  or positioning arm  60  and a backward cam  148  for backward movement thereof. 
   A cam follower unit  150  is also placed in the stationary frame  52 . A cam follower  152  for forward movement corresponding to the cam  146  for forward movement and a cam follower  154  for backward movement corresponding to the cam  148  for backward movement are integrally provided in the cam follower unit  150 , and the cam follower unit  150  is arranged to be slidable in the same direction as the sliding direction of the ink replenishing unit  48 . 
   Furthermore, a linkage mechanism  158  including a link  160  which is oscillatable around a supporting shaft  156  and an arm for displacing  162  whose one end is pivoted at a nose or tip end of the link  160  is provided in the stationary frame  52 . The other end of the arm for displacing  162  is pivoted at the positioning arm  60  or the ink replenishing unit  48 . The cam follower unit  150  is pivoted substantially at the center of the link  160 . Due to the aforementioned structure, when the cam follower unit  150  is slid, the magnitude of sliding is amplified by the linkage  158 , then to be transmitted to the positioning arm  60  or ink replenishing unit  48 . 
   In each cam unit  144 , positions and formation of the cam  146  for forward movement and the cam  148  for backward movement are determined such that the forward cam  146  and the backward cam  148  can advance or retreat the corresponding positioning arm  60  or ink replenishing unit  48  with a predetermined timing. The stationary frame  52  is provided with a sensor (not shown) which detects a rotational position of the cam unit  144 . On the basis of a rotational angle of the cam unit  144  which is detected by the sensor, the control circuit which is not shown in figures drives the drive motor  128  to set the initial position of the cam unit  144  or control the rotational angle thereof. 
   As shown in  FIG. 14 , when the cam unit  144  is rotated by receiving the torque from the normal rotation of the drive motor  128 , first, in the case that the rotational angle of the cam unit  144  has reached 10° (see  FIG. 5 ), the positioning arm  60  is advanced by the forward cam  146  of the cam unit  144  corresponding to the positioning arm  60 . In case that the rotational angle of the cam unit  144  has reached 40°, as shown in  FIG. 6 , the positioning arm  60  is located at the most forward position, and then the positioning arm  60  is maintained at this position until the rotational angle reaches 320°. 
   When the rotational angle of the cam unit  144  has reached 40°, the ink replenishing unit  48 Bk for the black ink starts to advance by the action of the forward cam  146  of the cam unit  144  corresponding to the ink replenishing unit  48 Bk. When the rotational angle has reached 90°, as shown in  FIG. 15A , the ink replenishing unit  48 Bk is located at the most forward position, and then the ink replenishing unit  48 Bk is maintained at this position until the rotational angle reaches 110°. At this stage, even if the rotation of the driving motor  128  is stopped or the driving motor  128  is reversely rotated, since the cam unit  144  is not rotated, the ink replenishing unit  48 Bk can be maintained at this position until the drive motor  128  is normally rotated next time. 
   When the cam unit  144  is further rotated, the ink replenishing unit  48 Bk starts to retreat by the action of the backward cam  148 . When the rotational angle reaches 140°, the ink replenishing unit  48 Bk is retreated to the initial position. When the rotational angle has reached 110° (i.e., at the same time when the ink replenishing unit  48 Bk starts to retreat), the ink replenishing unit  48 C for the cyan ink starts to advance by the action of the forward cam  146  of the cam unit  144  corresponding to the ink replenishing unit  48 C, and the ink replenishing unit  48 C is located at the most forward position at the rotational angle of 160°. Then, the most forward position is maintained during a period in which the rotational angle is in the range from 160° to 180° (see  FIG. 15B ). The ink replenishing unit  48 C starts to retreat at 180° by the action of the backward cam  148 . When the rotational angle has reached 210°, the ink replenishing unit  48 C is retreated to the initial position. Accordingly, the ink replenishing unit  48 C for cyan carries out the same actions as the ink replenishing unit  48 Bk did, later than the ink replenishing unit  48 Bk by the rotational angle of 70°. After that, in the same way, the ink replenishing unit  48 M for the magenta carries out the forward and backward movement, later than the ink replenishing unit  48 C for the cyan ink by the rotational angle of 70° (see  FIG. 16A ). The ink replenishing unit  48 Y for yellow ink carries out the forward and backward movement, later than the ink replenishing unit  48 M for the magenta ink by the rotational angle of 70° (see FIG.  16 B). As described above, in the ink replenishing device  46  of the embodiment, since a predetermined phase difference (70° in the present embodiment) is provided to the cam unit  144  corresponding to each ink replenishing unit  48 , each of the ink replenishing units  48  can be independently advanced and retreated relative to the corresponding sub ink tank  30 . 
   As shown in  FIG. 13 , when the driving motor  128  is reversely rotated, the oscillating arm  140  constituting the clutch unit  134  oscillates in the clockwise direction and the output side gear  142  meshes with the row of gears  132  for driving the pump. As a result, the torque of the drive motor  128  is transmitted to a pump shaft  166  constituting a pump unit  164 . 
   As shown in  FIG. 2 , the pump unit  164  is formed to have four roller pumps  168  corresponding to the tube for exhausting  126  extending from each ink replenishing unit  48 . As shown in  FIG. 3 , each roller pump  168  has a rotating board  170  which rotates integrally with the pump shaft  166  and one or more rollers  172  (two rollers are diagonally provided in the present embodiment) which is arranged in the vicinity of the outer periphery of the rotating board  170 . On the other hand, the tube for exhausting  126  is placed so as to partially surround a periphery of the rotating board  170 . The roller  172  locally presses the tube for exhausting  126 . Accordingly, when the rotating board  170  rotates in clockwise direction in  FIG. 3 , the roller  172  moves so as to squeeze the tube for exhausting  126  and exhausts fluid (air in the present embodiment) in the tube for exhausting  126  from the other end of the tube for exhausting  126  to the air. In each roller pump  168 , a mounting angle of each rotating board  170  is determined so that the rollers  172  are arranged as a whole with an equal space therebetween, as viewed along an axial direction of the pump shaft  166 . In the present embodiment, since the four roller pumps  168  are arranged, as is seen in  FIG. 3 , when each of rotating boards  170  is arranged with the mounting angle shifted by 45°, the rollers  172  are arranged as a whole with the equal space therebetween (with the center angle being 22.5 degree) as viewed along the pump shaft  166 . This allows resistance (in particular, rotational resistance which is generated as a result of the roller  172  being pushed by reaction force of the tube for exhausting  126 ) acting on the pump unit  164  to be dispersed, so that the pump unit  164  rotates smoothly. 
   The forward and backward movements of the ink replenishing unit  48  and the drive of the pump unit  164 , as a result of normal or reverse-direction drive by the drive motor  128 , is controlled by the control circuit which is not shown so that the timing is not overlapped with the maintenance actions of the maintenance station  20 . 
   Next effect of the ink replenishing device  46  and the ink jet recording apparatus  12  of the present embodiment and an ink replenishing method with the ink replenishing device  46  will be described. 
   The ink droplet is ejected from the recording head  28  according to the image information, and the recording head carriage  14  moves in the main scanning direction and the recording medium P moves in the sub-scanning direction, respectively, whereby the image is recorded on the recording medium P. Since the ink droplet is generated from the ink which is supplied from the sub ink tank  30  to the recording head  28 , the ink in the sub ink tank is decreased. 
   When the recording head  28  becomes a given state in which the recording head  28  requires the maintenance, the control circuit which is not shown moves the recording head carriage  14  to the home position, makes the maintenance station  20  approach the recording head  28 , and carries out the predetermined maintenance operation. This allows the recording head  28  to be recovered to an optimum state for ejecting ink, and consequently the optimum state for ejecting ink is always maintained, so that the high quality image can be recorded on the recording medium P. 
   When the ink quantity sensor  40  detects that the ink in the specific sub ink tank  30  has been decreased to the extent of a predetermined level and sends the information to the control circuit which is not shown, the control circuit moves the recording head carriage  14  to the ink replenishing position. At this stage, the maintenance station  20  is controlled by the control circuit so as not to be operated. 
   The control circuit operates to normally rotate the driving motor  128  so that the cam unit  144  is rotated by an angle corresponding to the specific sub ink tank  30 . For example, in the case that the black ink is replenished to the sub ink tank  30 Bk, as can be seen from  FIG. 14 , the drive motor  128  is normally rotated so that the rotational angle of the cam unit  144  is in a range of 90° to 110° (inclusive of both 90° and 110°). 
   At this stage, when the rotational angle of the cam unit  144  has reached 10°, the positioning arm  60  starts to advance. In the case that the recording head carriage  14  is not aligned with the guide frame body  54  in the widthwise direction, one of the tapered faces  62  of the positioning arm  60  contacts the corner portion of the recording head carriage frame  26 . In this state, when the positioning arm  60  further approaches the recording head carriage  14 , since the movement in this approaching direction is converted into the movement in the widthwise direction of the guide frame body  54 , the guide frame body  54  moves in the widthwise direction against the elastic force of the helical compression spring  58 . Then, when the positioning arm  60  further approaches the recording head carriage  14 , as shown in  FIG. 5 , the side face  26 C of the recording head carriage frame  26  is brought into contact with the inside face  60 A of the positioning arm  60 , whereby the recording head carriage  14  and the guide frame body  54  are correctly positioned or aligned in the widthwise direction. For example, even if a stop position (ink replenishing position) of the recording head carriage  14  is slightly shifted or any position shift caused by other various factors has been generated, such position shift is eliminated and the four ink replenishing units  48  are integrally positioned relative to the corresponding sub ink tank  30 . 
   When the positioning arm  60  further advances and pressing piece  66  contacts the recording head carriage frame  26 , the positioning arm  60  receives the urging force of the helical compression spring  68  to press the recording head carriage  14 . This allows the recording head carriage  14  to be held tight between the pressing piece  66  and the guide member  18 , so that the recording head carriage  14  is not carelessly rattled. 
   At this point, as can be seen from  FIG. 14 , the rotational angle of the cam unit  144  is 40°, and the forward cam follower  152  is pressed in the direction of approaching the sub ink tank  30  by the forward cam  146  of the cam unit  144  corresponding to the black ink, so that the ink replenishing unit  48 Bk advances and starts to approach the sub ink tank  30 Bk. During advancing (i.e., in a state in which the positioning pin  78  has not entered the positioning port  80  yet), the guide pin  88  moves in the support portion  90 A, and the ink replenishing unit  48  slides without rattle within the accommodating portion  70  of the guide frame body  54 . 
   As shown in  FIG. 7 , the positioning pin  78  starts to be inserted into the positioning port  80  when the ink replenishing unit  48  approaches the sub ink tank  30 . At this point, as can be seen from  FIG. 17 , in a state before inserting, the communicating hole  96  is sealed with the packing  104  in the main body of the pipe  94  (see  FIG. 10A ), and the main body of the pipe  94  is closed and sealed. Similarly, in the ink replenishing opening  44 , the valve  118  is closely contacted with the projection portion  114 C of the gasket  114 , so that the communication of the inner space with the atmosphere is obstructed. 
   Since the guide portion  84  at the nose or tip end of the positioning pin  78  is formed to be the taper shape, when the positioning pin  78  is inserted into the positioning port  80 , even if the center of the positioning pin  78  shifts off the center of the positioning port  80 , the positioning pin  78  reliably enters the positioning port  80 . At this stage, since the guide pin  88  reaches the width-wide portion  90 B and the gap is formed between the guide pin  88  and the width-wide portion  90 B. As a result, in the accommodating portion  70 , the ink replenishing unit  48  can be moved within a given range in the up and down directions and the widthwise direction. When the ink replenishing unit  48  further approaches the sub ink tank  30 , the center of the positioning pin  78  and the center of the positioning port  80  are gradually moved by the guide portion  84  in the direction which the center of the positioning pin  78  and the center of the positioning port  80  are coincided. When the positioning portion  82  reaches the positioning port  80 , as shown in  FIG. 8 , the center of the positioning pin  78  coincides with the center of the positioning port  80 , whereby the specific ink replenishing unit  48  and the sub ink tank  30  corresponding thereto are correctly positioned. 
   Then, as can be seen from  FIG. 17 , when the port for replenishing ink  36  advances, the atmosphere communicating opening  38  is closed by the cap  72 . As can be seen from  FIGS. 10 and 17 , the port for replenishing ink  36  further advances and the nose or the tip end of the main body of the pipe  94  enters the ink replenishing opening  44  (start of a pipe inserting process), and the valve abutting portion  110  contacts the valve projection portion  122 . At this stage, when the main body of the pipe  94  is further inserted, the valve abutting portion  110  and the valve projection portion  122  are pressed with each other. As the helical compression spring  108  in the main body of the pipe  94  has the spring constant which has been set to be smaller relative to that of the helical compression spring  120  in the ink replenishing opening  44 , only the main body of the pipe  94  advances while the helical compression spring  108  is being compressed (strictly speaking, valve body  98  is at rest or unmoved at this stage), whereby the communicating hole  96  is opened by the valve body  98 . At this stage, the lip portion  114 B is not in contact with the outer peripheral portion the main body of the pipe  94 . 
   When the main body of the pipe  94  is inserted into the ink replenishing opening  44 , as shown in  FIG. 10C , as the nose portion of the main body of the pipe  94  is brought into contact with the valve  118 , the helical compression spring  120  is pressed by the main body of the pipe  94  through the valve  118  to starts to be compressed (the valve body  98  and the main body of the pipe  94  integrally enter the ink replenishing opening  44 , while the valve body  98  and the main body of the pipe  94  are retained so that a substantially constant distance is maintained therebetween relative to each other). As a result, the valve  118  separates from the projection portion  114 C of the gasket  114  to start to create an opening therebetween. Even in this state, as can be seen from  FIG. 17 , the lip portion  114 B is not contacted with the outer peripheral portion of the main body of the pipe  94 . Since the inside of the sub ink tank  30  is maintained in the negative pressure, the air is sucked from the gap between the outer peripheral portion of the main body of the pipe  94  and the lip portion  114 B. Particularly, at this stage, as the atmosphere communicating opening  38  of the sub ink tank  30  is sealed by the cap  72 , undesirable entry of the air from the atmosphere communicating opening  38  into the sub ink tank  30  is prevented. Therefore, the air is securely sucked from the gap between the outer peripheral portion of the main body of the pipe  94  and the lip portion  114 B. With this suction, the ink which is remained in or adhered to the outer peripheral portion of the main body of the pipe  94  or the inside of the ink replenishing opening  44  is also sucked into the sub ink tank  30 . This sucking operation of the ink into the sub ink tank  30 , continues, as shown as “Sucking Action of Ink” in  FIG. 17 , from start of the opening operation of the ink replenishing opening  44  till the sealing of the outer peripheral portion of the main body of the pipe  94 . 
   As shown in  FIG. 10D , while the main body of the pipe  94  is advanced in the most inside position, the outer peripheral portion of the main body of the pipe  94  is closely contacted with the lip portion  114 B. The ink replenishing unit  48  is located at the ink replenishing position, the connection between the port for replenishing ink  76  and the ink replenishing opening  44  of the sub ink tank  30  is finished to be liquid-communicated, and the ink flow or channel from the main ink tank  50  to the sub ink tank  30 Bk is formed. At the same time, the connection between the port for exhausting  34  and the exhaust opening  42  is completed (completion of the pipe inserting process). Accordingly, when the drive motor  128  is normally rotated to set the cam unit  144  at the specific rotational angle, the specific the ink replenishing unit  48  to be connected with the sub ink tank  30  corresponding thereto. 
   The drive motor  128  is reversely rotated by the control circuit which is not shown. The oscillating arm  140  of the clutch unit  134  oscillates in the clockwise direction in  FIG. 12 . As shown in  FIG. 13 , the transmission of the torque of the drive motor  128  is switched so that the torque is transmitted to the row of gears  132  for driving pump instead of the row of gears  130  for displacing the ink replenishing unit. Consequently, the roller pump  168  constituting the pump unit  164  is driven, while the position of the ink replenishing unit  48 Bk is held at ink replenishing position, whereby air inside the sub ink tank  30 Bk is exhausted from the exhaust opening  42  of the sub ink tank  30 Bk by the ink replenishing unit  48 Bk. At this stage, since the atmosphere communicating opening  38  of the sub ink tank  38 Bk is sealed by the cap  72 , any accidental entry of the air from the atmosphere communicating opening  38  into the sub ink tank  30 Bk is prevented, and the air is securely exhausted from the sub ink tank  30 Bk. With respect to other the ink replenishing units  48  which have not advanced to the ink replenishing positions thereof, although the corresponding roller pump  168  is driven, the resistance against the drive of the roller pump  168  is not generated because the port for exhausting  74  is opened. 
   Since the control circuit reversely rotates the drive motor  128  only for a predetermined time, a predetermined amount of the ink is supplied to the sub ink tank  30 . This time period during which the drive motor  128  is reversely rotated may be set beforehand at a fixed value or determined by feedback control on the basis of the ink quantity information from the ink quantity sensor  40 . 
   Then, the control circuit normally rotates the drive motor  128 . The oscillating link  160  oscillates in the counterclockwise direction in  FIG. 13 . As shown in  FIG. 12 , the torque of the drive motor  128  is retransmitted to the row of gears  130  for displacing the ink replenishing unit, so that the cam unit  144  is rotated. As can be seen from  FIG. 14 , when the rotational angle of the cam unit  144  reaches 110°, the ink replenishing unit  48 Bk starts to be retreated. And then the valve  118  is brought into close contact with the projection portion  114 B of the gasket  114 , and the communicating hole  96  is sealed by the packing  104 . 
   At this point, as can be seen from  FIG. 17 , since the main body of the pipe  94  starts to retreat at the ink replenishing opening  44  (start of a pipe drawing-out process), first the outer peripheral portion of the main body of the pipe  94  is separated from the lip portion  114 B to open the ink channel into the atmosphere. Accordingly, in the same manner as described above, the ink which is remained in or adhered to the outer peripheral portion of the main body of the pipe  94  or the inside of the ink replenishing opening  44  is also sucked into the sub ink tank  30 , as the air is absorbed from the gap between the outer peripheral portion of the main body of the pipe  94  and the lip portion  114 B by the negative pressure in the sub ink tank  30 . Then, the valve  118  is slid by the elastic force of the helical compression spring  120  to approach the projection portion  114 C of the gasket  114 . When the valve  118  returns to the initial position to contact closely with the projection portion  114 C, the valve body  98  in the main body of the pipe  94  receives the elastic force of the helical compression spring  108  to be slid, and the valve body  98  moves toward the communicating hole  96 . The valve body  98  returns to the initial position to seal the communicating hole  96 , and the main body of the pipe  94  is drawn out from the ink replenishing opening  44  (completion of the drawing-out process). Finally, the cap  72  is separated from the atmosphere communicating opening  38  and the sub ink tank is opened into atmospheric pressure. 
   Further, when the drive motor  128  rotates normally and the rotational angle of the cam unit  144  reaches 140°, the retreat of the ink replenishing unit  48 Bk is completed, and the ink replenishing unit  48 Bk returns to the initial position. 
   With the aforementioned operations, the ink replenish operation for the sub ink tank  30 Bk corresponding to the black ink is completed. However, in case that the ink replenish for other sub ink tanks  30  is further required, the control circuit further normally rotates the drive motor  128  so that the rotational angle of the cam unit  144  is set at the angle corresponding to the sub ink tank  30  which requires the ink supply. For example, in the case that the ink is supplied to the sub ink tank  30 C corresponding to the cyan ink, the drive motor  128  is normally rotated until the rotational angle of the cam unit  144  is set to be not lower than 160° nor more than 180°, so that, the ink replenishing unit  48 C is set to be the ink replenishing position, as shown in  FIG. 15B . The roller pump  168  is driven by reversely rotating the drive motor  128  with this state, whereby the ink is replenished to the sub ink tank  30 C. After replenishing the predetermined quantity of the ink, the control circuit normally rotates the drive motor  128 , makes the ink replenishing unit  48 C retreat, and returns the ink replenishing unit  48 C to the initial position. 
   In case that the ink replenishing to the sub ink tank  30 C is not required, by preventing the drive motor  128  from being rotated reversely such that only the ink replenishing unit  48 C advances and retreats and the pump unit  164  is not driven, the ink will not be replenished to the sub ink tank  30 C. However, even in the case in which the ink is being replenished to the sub ink tank  30 C, as the inserting and drawing-out actions to the ink replenishing opening  44 , of the main body of the pipe  94 , is carried out by the forward and retreat of the ink replenishing unit  48 C, the ink which is remained in or adhered to the outer peripheral portion of the main body of the pipe  94  or the inside of the ink replenishing opening  44  is sucked into the sub ink tank  30  by utilizing the negative pressure in the sub ink tank  30 . 
   When the ink replenishing operation to the desired sub ink tank  30  is completed, as can be seen from  FIG. 14 , finally (strictly, simultaneously with the retreating operation of the ink replenishing unit  48 Y), the positioning arm  60  is retreated by the backward cam corresponding to the positioning arm  60 , and the sub ink tank  30  returns to the initial position. In the way described above, all the actions replenishing the ink to the sub ink tank  30  are completed. 
   As can be seen from the above-described description, in the present embodiment, the ink replenishing unit  48  corresponding to the specific sub ink tank  30  which requires the ink replenishing among the plurality of sub ink tanks  30  is selectively moved to the replenishing position, and the ink is replenished, for each color, to the sub ink tank  30 . When the main body of the pipe  94  is inserted and drawn out in the ink replenishing operation, the ink which is remained in or adhered to the outer peripheral portion of the main body of the pipe  94  or the inside of the ink replenishing opening  44  is sucked into the sub ink tank  30 , regardless that the ink is actually replenished or not. Therefore, the ink leakage can reliably be prevented and so-called ink dirt can be prevented. Furthermore, in the case that the ink is slightly leaked out, the leaked ink is sucked and held by the ink absorber  186  placed below the gasket cover  112 . Therefore, scatter and spread of the leaked ink can be prevented and the ink dirt can more reliably be prevented than the conventional model. 
   Table 1 shows the ink leakage quantity in the vicinity of the ink replenishing opening  44  after the ink replenishing, the ink leakage quantity being the value measured, in the ink replenishing device of the present embodiment, for one ink replenishing operation, after the image recording to 24000 sheets of paper (size of A4, printing duty of 5%), which task is regarded as terminating the product life of the recording head  28 . 
   
     
       
         
             
             
             
           
             
                 
               TABLE 1 
             
           
          
             
                 
                 
             
             
                 
               Average Value of Ink 
                 
             
             
                 
               leakage Quantity (mg) 
             
          
         
         
             
             
             
             
          
             
                 
                 
               After Image Recording 
               Reduction Rate of 
             
             
                 
               Per Ink 
               to 24000 Sheets of 
               Ink Leakage Quan- 
             
             
                 
               replenishing 
               Paper (Size of A4, 
               tity (Comparative 
             
             
                 
               Operation 
               Printing Duty of 5%) 
               Example = 100%) 
             
             
                 
                 
             
          
         
         
             
             
             
             
          
             
               Comparative 
               1.23 
               406 
               100% 
             
             
               Example 1 
             
             
               The present 
               0.378 
               125 
               31% 
             
             
               Embodiment 
             
             
                 
             
          
         
       
     
   
   In Table 1, the values which are shown as the comparative example 1 are the ink leakage quantity in the ink replenishing device whose configuration is the same as the present embodiment except that the to-be-pressed piece  184  of the embodiment is not formed. In the ink replenishing opening  44  of the comparative example 1, as can be seen from  FIG. 17 , the periphery of the main body of the pipe  94  is at first closely contacted with the lip portion  114 B and then the ink channel is formed in the pipe inserting process. Accordingly, the ink which is remained in or adhered to the outer peripheral portion of the main body of the pipe  94  or the inside of the ink replenishing opening  44  is not sucked into the sub ink tank  30  by the negative pressure in the sub ink tank  30 . Further, in the case of the configuration of the comparative example 2 shown by the dash-double dot line in  FIG. 17 , the structure of the comparative example 2 is similar to that of the comparative example 1 in that the outer peripheral portion of the main body of the pipe  94  is at first brought into close contact with the lip portion  114 B and then the ink channel is formed. Accordingly, it is reliably assumed that the ink leakage quantity of the comparative example 2 will be almost the same value as that of the comparative example 1. 
   In this measurement, the twenty recording heads are used for evaluation. “Average Value” of “Average Value of Ink Leakage Quantity” in Table 1 shows the average value of the values obtained from the twenty recording heads. In the actual measurement, the quantity of the leaked ink is measured for the image recording to 24000 sheets of paper, which image recording is supposed to terminate the product life of the recording head, and the measured quantity of the leaked ink is divided by the total number of the ink replenishing operations (330 times) to obtain the ink leakage quantity of “per ink replenishing operation”. 
   As can be seen from Table 1, in the present embodiment, the ink leakage quantity is decreased to 31%, as compared with the comparative example 1. 
   According to the result, the quantity of ink absorbable by the ink absorber  186  can be set properly. For example, in the case that a porous body having internal volume of 0.4 ml and absorption ratio of 40% (or more) is used, the quantity of ink absorbable by the ink absorber  186  is 0.16 ml (or more). Consequently, in the case of the present embodiment, the ink which has leaked out is securely absorbed and held throughout the product life of the recording head  28 . Examples of a porous body satisfying such conditions include Sunfine AQ (trademark, manufactured by Asahi Chemical Industry Co., Ltd.) which is a hydrophilic polyolefin porous body. However, the material of the porous body is not limited to this example. 
   In the invention, the specific structure for replenishing the ink to the sub ink tank  30  is not limited to the above-mentioned example. Other structures, for example, a structure in which the ink replenishing unit  48  is arranged above the sub ink tank  30  and the ink is dropped or flowed down from the ink replenishing unit  48  to the sub ink tank  30  utilizing gravity caused by a difference in the elevated position between the ink replenishing unit  48  and the sub ink tank  30  may be used. Alternatively, a structure in which the ink is pressurized to be forcefully sent into the sub ink tank  30  may be used. 
   The structure for evacuating the sub ink tank to a negative pressure is not limited to the above-described roller pump  168 , either. However, use of the roller pump  168  is advantageous because the inside of the sub ink tank  30  can reliably be evacuated in a relatively short time, to a negative pressure, with a simple device. Moreover, the roller pump can be used without converting the rotational movement of the drive motor  128  into other motion such as linear motion, which is highly efficient. 
   The opening means of the invention is not limited to the to-be-pressed piece  184  which is provided in the valve  118 . That is, in the inserting operation of the main body of the pipe  94 , it suffices that the opening means can open the ink channel to the atmosphere before the main body of the pipe  94  is brought into contact with the lip portion  114 B. For example, a pressing portion such as a pressing piece which presses the valve  118  at the initial stage of the inserting operation of the main body of the pipe  94  may be provided at the tip end or the nose of the main body of the pipe  94  or the tip end of the valve abutting portion  110 . A structure in which the vicinity of the tip end of the main body of the pipe  94  has the smaller outer diameter than other portions of the main body of the pipe  94  or has the larger inner diameter than the lip portion  114 B, so that the timing when the main body of the pipe  94  is brought into contact with the lip portion  114 B is delayed, may be used for the opening means of the invention. 
   In the above-described explanation, the opening means is provided only at the port for replenishing ink  36 . However, if necessary, the opening means may also be provided at the port for exhausting  34 . That is, when a structure is selected in which the ink level might reach the port for exhausting  34  in the sub ink tank  30 , it is preferable that the opening means is also provided in the port for exhausting  34  in order that the ink leakage from the vicinity of the exhaust opening  42  is prevented. On the contrary, a structure in which the ink level does not reach the port for exhausting  34  in the sub ink tank  30 , as in the present invention, is preferable because, by providing the opening means only at the port for replenishing ink  36 , there is no possibility that the air is undesirably sucked from the exhaust opening  42 , when the residual ink in the vicinity of the ink replenishing opening  44  is sucked into the sub ink tank  30 , and the sucking force of the residual ink is weakened. 
   In the invention, the types of the applicable ink are not particularly limited. If the ink contains constituents such as water which is easily dried by more than a predetermined quantity, the ink absorber  186  which has absorbed the ink is relatively quickly dried, and eventually, the ink absorber  186  can substantially absorb a larger amount of ink. For example, even if the ink jet recording apparatus  12  is used for longer than its due product life, the ink absorber  186  can still absorb the ink in a sufficient manner. For example, a water-based ink, which is expected to evaporate by the amount of 70%, can be used preferably. 
   The specific type of the material of the ink absorber  186  is not particularly limited, as long as the material is a porous body constituted of a porous material which can absorb ink. For example, the ink absorber  186  may be formed by sintering the powder of polyurethane resin. The powder of polyurethane is preferable because this material allows molding with high molding precision and maintains the shape in a stabele manner after molding. The absorber  186  may be formed of other materials such as polyuretane foam, fibrous felt or the like. 
   The ink holding member of the invention is not limited to the ink absorbers  186  described above. For example, a structure in which a container in the shape of a dish or a boat is formed by a material resistant to ink and the ink is stored in the container may be used. However, when the ink is simply reservoired, there is a possibility that the ink accidentally leaks due to a change in an attitude of the ink jet recording apparatus  12  and the like. Accordingly, it is preferable that the ink holding member is formed of the above-described porous body or the porous body is placed in at least a portion of the container so as to absorb the ink. 
   As described above, in short, the invention can reliably prevent the ink dirt because the invention adopts the above-described configuration.