Patent Publication Number: US-8534815-B2

Title: Flow path member, liquid ejecting head, and liquid ejecting apparatus

Description:
This application claims a priority to Japanese Patent Application No. 2011-006492 filed on Jan. 14, 2011 which is hereby expressly incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a flow path member, a liquid ejecting head, and a liquid ejecting apparatus. 
     2. Related Art 
     An ink jet recording head (liquid ejecting head: ink ejecting head) that ejects ink droplets from a nozzle opening using pressure generated by displacement of a piezoelectric element, for example, is known as a typical example of a liquid ejecting head. The ink ejecting head which has been known is supplied with ink from a fluid source of ink (ink cartridge), and ejects the supplied ink from nozzles by driving a pressure generating unit, such as a piezoelectric element or heat generating element. 
     An ink flow path extending from the ink cartridge is connected to the ink ejecting head, and a seal member like a rubber member is provided at the connected portion between the ink ejecting head and the ink cartridge (see, for example, JP-A-2000-218781). Sealing the connected portion between the ink ejecting head with a rubber member can prevent the ink from leaking at the connected portion with positional misalignment between the ink ejecting head and the ink cartridge being absorbed. 
     There is an ink ejecting unit constructed to have an ink ejecting head with a valve body which is opened and closed in accordance with the pressure state of a flow path on the ink ejecting head side. The valve body is provided in the flow path to supply ink to the ink ejecting head from the ink cartridge. When ink is ejected from the ink ejecting head in such an ink ejecting unit, the flow path on the ink ejecting head side has negative pressure, causing the valve body to open to supply the ink. 
     In the ink ejecting unit having the valve body which is opened and closed in accordance with the pressure state of the flow path on the ink ejecting head side, pressures in the flow path on the ink ejecting head side and the flow path on the ink cartridge side relatively vary at the connected portion between the ink ejecting head and the ink cartridge. This is likely to affect the seal member at the connected portion between the ink ejecting head the ink cartridge, and therefore the rigidity of the seal member may be enhanced to prevent ink leakage therefrom. 
     SUMMARY 
     An advantage of some aspects of the invention is to provide a flow path member capable of keeping airtightness of the members to be connected together with a simplified structure, regardless of a variation in pressure in the flow path or the like. 
     Another advantage of some aspects of the invention is to provide a liquid ejecting head and a liquid ejecting apparatus each of which includes a flow path member capable of keeping airtightness of the members to be connected together with a simplified structure, regardless of a variation in pressure in the flow path or the like. 
     According to an aspect of the invention, there is provided a flow path member including, an elastic urging member that urges and holds a fluid supply pipe having a supply path that supplies a fluid downstream, a holder having a first inner wall that defines a first opening and on which an outer wall of the elastic urging member abuts and a second inner wall that defines a second opening smaller than the first opening, the fluid supply pipe being disposed inward of the first inner wall and the second inner wall with the outer wall of the elastic urging member held against the first inner wall, and a fixing member that abuts on an inner wall of the elastic urging member to hold the elastic urging member between the fixing member and the first inner wall of the holder. 
     Accordingly, the elastic urging member is in tight contact with the first inner wall of the first opening of the holder (e.g., resin holder) by the fixing member. As a result, the fluid supply pipe is urged and held on the inner wall of the elastic urging member and is held in a predetermined position with respect to the first inner wall of the first opening and the second inner wall of the second opening of the holder, and the fluid supply pipe is held on the holder with the first opening of the holder kept airtight. Even when the pressure on the upstream side of the fluid supply pipe and the pressure on the second opening side of the holder vary relatively, i.e., regardless of a variation in pressure in the flow path or the like, the airtightness of the members which are connected together can be maintained. 
     It is preferable that a clearance be provided between a portion of the fixing member that holds the elastic urging member at the first opening, and the fluid supply pipe. 
     Accordingly, the first opening that defines the first inner wall is formed in such a way as to provide a clearance between the fixing member and the fluid supply pipe, so that urging and holding of the fluid supply pipe with the elastic urging member can be surely maintained without the interference of the fixing member with the fluid supply pipe. 
     It is preferable that the elastic urging member should include a holding section that holds the fluid supply pipe, and an edge portion formed contiguous to the holding section with a clearance provided between the edge portion and the fluid supply pipe held by the holding section, and the fixing member should abut on an inner wall of the edge portion to hold the elastic urging member between the fixing member and the first inner wall of the holder. 
     This structure allows the fluid supply pipe to be held on the holding section of the elastic urging member, and the fixing member causes the edge portion of the elastic urging member to be in tight contact with the first inner wall, so that the sealing of the first opening can be maintained with the fluid supply pipe held, without increasing the rigidity of the elastic urging member. 
     It is preferable that a liquid supplied from the fluid supply pipe urged and held by the elastic urging member should be supplied to a head body, and the head body should be provided with an opening/closing member that opens and closes a flow path between the head body and the second opening in accordance with pressure in a flow path in the head body. 
     Accordingly, even when the pressure on the second opening side of the holder varies according to the open/closed state of the opening/closing member, the tight contact of the edge portion of the elastic urging member with the first inner wall by the fixing member is maintained. Even when the opening/closing member that opens and closes the flow path between the head body and the second opening in accordance with pressure in the flow path in the head body is provided, the airtightness of the members which are connected together can be maintained. 
     It is preferable that the elastic urging member and the fixing member be formed integrally. For example, preferably, the elastic urging member and the fixing member are formed integrally to be a composite member through coinjection molding. 
     Accordingly, when the composite member of the elastic urging member and the fixing member is welded to the holder at the upper side portion of the first opening, the elastic urging member can be attached to the holder. Through only the step of attaching the composite member (single step), the elastic urging member is pressed against the first inner wall and in tight contact therewith by the fixing member while being disposed inward of the first inner wall of the holder. 
     According to another aspect of the invention, there is provided a liquid ejecting head including the aforementioned flow path member, and a head body connected to a downstream side of the holder of the flow path member and having a nozzle opening. 
     This structure provides a liquid ejecting head which includes a flow path member capable of keeping airtightness of the members to be connected together with a simplified structure, regardless of a variation in pressure in the flow path or the like. 
     According to a further aspect of the invention, there is provided a liquid ejecting apparatus including the aforementioned liquid ejecting head, and a fluid source connected to an upstream side of the fluid supply pipe held by the elastic urging member of the flow path member. 
     This structure provides a liquid ejecting apparatus which includes a flow path member capable of keeping airtightness of the members to be connected together with a simplified structure, regardless of a variation in pressure in the flow path or the like. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a schematic diagram of an ink jet recording apparatus. 
         FIG. 2  is a perspective view of an ink ejecting head. 
         FIG. 3  is a plan view of a supply pipe connecting portion. 
         FIG. 4  is a sectional view of the supply pipe connecting portion in  FIG. 3 . 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       FIG. 1  schematically shows the general configuration of an ink jet recording apparatus to which a flow path member according to an exemplary embodiment of the invention is adapted.  FIG. 2  is a perspective view of the main portions of an ink ejecting head,  FIG. 3  is a plan view of a portion of a holder to which a supply pipe is connected, and  FIG. 4  is a sectional view of the portion of the holder (along line IV-IV in  FIG. 3 ). 
     Referring to  FIG. 1 , the ink jet recording apparatus will be described. 
     As shown in  FIG. 1 , the ink jet recording apparatus  1  as a liquid ejecting apparatus has a carriage  3  on which ink cartridges  2  are mounted, and an ink ejecting head  5  as a liquid ejecting head attached to the carriage  3 . The carriage  3  is connected to a stepping motor  7  via a timing belt  6 , and is guided by a guide bar  8  to make reciprocal movement across a recording sheet  9  or in a widthwise direction thereof (main scanning direction). The carriage  3  has a box shape with an open top, so that the ink ejecting head  5  is mounted on a side (bottom surface) of the carriage  3  facing the recording sheet  9  with the nozzle surface of the ink ejecting head  5  exposed, and the ink cartridges  2  are accommodated in the carriage  3 . 
     Inks are supplied to the ink ejecting head  5  from the ink cartridges  2 , and ink droplets are ejected onto the top surface of the recording sheet  9  to print an image and characters on the recording sheet  9  in dot matrix while the carriage  3  is move. Referring to  FIG. 1 , a cap  10  seals the nozzle opening of the ink ejecting head  5  when printing does not take place to thereby prevent the nozzle from drying, and applies negative pressure onto the nozzle surface of the ink ejecting head  5  to perform a cleaning operation. A wiper blade  11  wipes out the nozzle surface of the ink ejecting head  5 . A waste ink retainer  12  retains waste ink sucked in the cleaning operation. A control unit  13  controls the ink jet recording apparatus  1 . 
     The illustrated ink ejecting head  5  includes a flow-path forming member where flow paths for supplying inks from the ink cartridges  2  are formed. Although  FIG. 1  illustrates an example where the ink cartridges  2  as fluid sources are mounted in the carriage  3 , the invention can be adapted to an ink jet recording apparatus structured such that the ink cartridges are accommodated at another location separate from the carriage  3 , and inks are supplied to the flow-path forming member of the ink ejecting head  5  via a pipe under pressure. 
     The ink ejecting head  5  will be described referring to  FIG. 2 . 
     As shown in  FIG. 2 , the ink ejecting head  5  includes a pressure generating unit, such as a piezoelectric element, to eject ink droplets from the nozzle opening of a nozzle plate  15  using the pressure generated by the displacement of the piezoelectric element. The ink ejecting head  5  is provided with a reservoir chamber, and a flow-path forming member  21  having the flow path member according to the invention is connected to the top portion of the ink ejecting head  5 . Ink as a fluid from the flow-path forming member  21  is supplied to a head flow path of the ink ejecting head  5  and supplied to the reservoir chamber from the head flow path. Inks are supplied to the flow-path forming member  21  from the ink cartridges  2 . For example, the inks are supplied to the flow-path forming member  21  from the ink cartridges  2  via a supply pipe or an ink supply probe. 
     Referring to  FIGS. 2 and 3 , the flow-path forming member  21  will be described below. 
     As shown in  FIG. 2 , the flow-path forming member  21  has the shape of a rectangular parallelepiped block having rectangular faces. Films are welded to both faces of a body  22  of a resin to form flow paths  24  on the respective faces. An outlet flow path  25  is provided contiguous to the lower portion of the flow path  24 . The outlet flow path  25  is formed to become wider toward the downstream side (lower side). A filter  27  is provided inside the outlet flow path  25 . The filter  27  is disposed on a wide portion of the face with an area substantially corresponding to the wide outlet flow path  25 , thereby securing a large area. The filter  27  mainly traps a foreign matter contained in ink flowing through a valve body  34  (mechanical component) to be described later. 
     The ink which passes through the flow path  24  is supplied to a lower portion inside the body  22  through the filter  27  from outside the face, and is supplied to the ink ejecting head  5  from a discharge hole (not shown). That is, the ink which passes through the flow path  24  to be supplied to the outlet flow path  25  moves from a narrow flow path to a wider flow path, and passes through the filter  27  to be supplied to one reservoir chamber of the ink ejecting head  5  from the discharge hole at an end. 
     Flow-in path sections  30  as holders (resin holders) for flow path members are provided at upper ends of the flow-path forming member  21 . Ink inlet holes  31  are respectively provided at the flow-in path sections  30 , and inks are respectively supplied to the ink inlet holes  31  from the ink cartridges  2 . The ink that is supplied to one ink inlet hole  31  (on the left-hand side in  FIG. 2 ) is supplied to the inlet side of the flow path  24  shown in  FIG. 2 , and the ink that is supplied to the other ink inlet hole (on the right-hand side in  FIG. 2 ) is supplied to the inlet portion of a flow path provided on the other side of the flow-path forming member  21  (on the bottom side of the sheet of  FIG. 2 ). 
     The ink that is supplied to the ink inlet hole  31  is supplied to an ink chamber  33 . Valve bodies  34  as opening/closing members are respectively provided in flow paths between the ink inlet holes  31  and the ink chambers  33 . The valve body  34  operates to permit circulation of ink when pressure in the reservoir chamber of the ink ejecting head  5  drops, i.e., when the pressure in the flow path  24  relatively drops as a result of ejection of ink. 
     That is, in the case where ink is supplied from the ink inlet hole  31  under predetermined pressure, the valve body  34  is closed when the ink is retained in the reservoir chamber of the ink ejecting head  5 , and is opened by negative pressure to supply the ink when the downstream-side pressure drops due to ejection of the ink. 
     As shown in  FIGS. 2 and 3 , a seal member  36  as an elastic urging member is fixed to the ink inlet hole  31  of the flow-in path section  30  by a fixing member  37 , and an ink supply pipe  40  as a fluid supply pipe for supplying ink supplied from an ink supply probe or the like is urged and held on the seal member  36 . The seal member  36  is inserted into ink inlet hole  31  to abut on the inner wall of the ink inlet hole  31 . Then, the fixing member  37  abuts on the inner wall of the seal member  36 , so that notched portions  38  of the fixing member  37  are fitted over projections  32  of the ink inlet hole  31  to be securely caulked. As a result, the seal member  36  is fitted into the inner wall of the ink inlet hole  31  to be fixed by the fixing member  37 . 
     Referring to  FIG. 4 , the flow-in path section  30  (holder) of the flow-path forming member  21  will be described specifically. 
     As shown in  FIG. 4 , the ink inlet hole  31  is formed in the flow-in path section  30 . The inlet portion (upstream) of the ink inlet hole  31  serves as a first opening  42  defined by a first inner wall  41 , and the downstream portion (downstream) of the ink inlet hole  31  serves as a second opening  44  defined by a second inner wall  43  contiguous to the first inner wall  41 . The second opening  44  is smaller in diameter than the first opening  42 . The ink inlet hole  31  is formed as a continuous hole extending from the first opening  42  to the second opening  44 . 
     The seal member  36  is fixed to the portion of the first opening  42 . The seal member  36  includes a holding section  45  urging and holding the outer periphery of the ink supply pipe  40 . The ink supply pipe  40  is fitted into a holding hole  46  of the holding section  45  to be held by the holding section  45 . A cylindrical edge portion  47  is formed on the upper side of and contiguous to the outer periphery of the holding section  45  with a clearance provided between the edge portion  47  and the ink supply pipe  40 . The edge portion  47  is fitted into the first inner wall  41  of the first opening  42 , so that the outer surface of the edge portion  47  abuts on the first inner wall  41 . 
     The edge portion  47  is held by the fixing member  37  to be secured between the first inner wall  41  of the first opening  42  and the fixing member  37 . That is, the fixing member  37  includes a cylindrical part  51  abutting on the inner wall of the edge portion  47 . A collar  52  which abuts on the top surface of the flow-in path section  30  and has the aforementioned notched portions  38  (see  FIGS. 2 and 3 ) formed therein is provided on the upper side of the cylindrical part  51 . The notched portions  38  (see  FIGS. 2 and 3 ) of the collar  52  are fitted over the projections  32  (see  FIGS. 2 and 3 ) of the ink inlet hole  31  to be securely caulked, and the edge portion  47  of the seal member  36  is held by the cylindrical part  51  to be fixed between the first inner wall  41  of the first opening  42  and the cylindrical part  51 . 
     A clearance S is provided in the first opening  42  between the cylindrical part  51  holding the edge portion  47  and the ink supply pipe  40 . In other words, the first opening  42  defined by the first inner wall  41  is formed in such a way as to form the clearance S between the cylindrical part  51  and the ink supply pipe  40 . 
     Accordingly, the fixing member  37  (cylindrical part  51 ) does not interfere with the ink supply pipe  40 , and the members on the upstream side and the downstream side of the ink supply pipe  40  are not misaligned with each other. Further, it is possible to keep the ink supply pipe  40  fitted into the holding hole  46  of the holding section  45 , thus preventing a clearance from being formed between the ink supply pipe  40  and the holding hole  46 . Furthermore, the edge portion  47  can be reliably held by the cylindrical part  51  between the first inner wall  41  and the cylindrical part  51 . 
     Although the seal member  36  and the fixing member  37  are formed as separate members according to the embodiment, they may be formed integrally. In this case, for example, the seal member  36  and the fixing member  37  are integrally formed (integrated) of different materials to be a composite member by coinjection molding. With the seal member  36  and the fixing member  37  integrated, the seal member  36  can be attached to the flow-in path section  30  by welding the fixing member  37  of the composite member to the flow-in path section  30  (holder) at the top surface portion of the first opening  42 . Accordingly, just the step of attaching the composite member (single step) allows the holding section  45  of the seal member  36  to be disposed inside the first inner wall  41  and allows the edge portion  47  of the seal member  36  to be pressed against and firmly in contact with the first inner wall  41 . 
     The aforementioned structure of the flow-in path section  30  causes the edge portion  47  of the seal member  36  to be firmly in contact with the first inner wall  41  of the first opening  42  by the fixing member  37 , so that the ink supply pipe  40  is urged and held into the holding hole  46  of the holding section  45  of the seal member  36  in a predetermined position with respect to the first inner wall  41  of the first opening  42  and the second inner wall  43  of the second opening  44 . This causes the ink supply pipe  40  to be held in a predetermined position of the ink inlet hole  31  with the first opening  42  of the flow-in path section  30  kept airtight. 
     Even when the pressure on the upstream side of the ink supply pipe  40  and the pressure on the second opening  44  side relatively vary, the ink supply pipe  40  and the flow-in path section  30  (ink inlet hole  31 ) which are to be connected to each other are therefore kept airtight. That is, even when the valve body  34  (see  FIG. 2 ) is open/closed by a variation in pressure due to emission of ink and pressure on the upstream side and pressure on the down stream side vary, airtightness of the ink supply pipe  40  and the flow-in path section  30  (ink inlet hole  31 ) that are the members to be connected together can be maintained. 
     When the pressure on the second opening  44  side relatively drops, for example, force acts on the seal member  36  side where the edge portion  47  of the seal member  36  is firmly in contact with the first inner wall  41  of the first opening  42  to secure the airtight condition. When the pressure on the second opening  44  side relatively rises, however, force acts on the seal member  36  side toward the interior of the first opening  42  (opposite side to the first inner wall  41 ) such that clearance is formed between the edge portion  47  and the first inner wall  41 . The aforementioned structure of the flow-in path section  30  maintains the tight contact of the edge portion  47  of the seal member  36  with the first inner wall  41  by the fixing member  37 , keeping the airtight state even when the pressure on the second opening  44  side relatively rises. 
     In addition, the ink supply pipe  40  is urged and held on the holding section  45  of the seal member  36 , and the edge portion  47  of the seal member  36  is firmly in contact with the first inner wall  41  by the fixing member  37 , so that a single seal member  36  can be provided with two functions of achieving tight contact with the ink supply pipe  40  and tight contact with the first inner wall  41 . This makes it possible to keep the sealing of the first opening  42  with the ink supply pipe  40  held without increasing the rigidity of the seal member  36 . 
     The flow-in path section  30  can maintain airtightness of the members to be connected together (ink supply pipe  40  and ink inlet hole  31 ) with a simplified structure, regardless of a variation in pressure in the flow path or the like. Further, the ink ejecting head  5  and the ink jet recording apparatus  1  can be provided with the flow-in path section  30  that can keep airtightness of the members to be connected together (ink supply pipe  40  and ink inlet hole  31 ) with a simplified structure, regardless of a variation in pressure in the flow path or the like. 
     Although the foregoing description of the embodiment has been given of an exemplary flow path member that connects the ink supply pipe  40  to the flow-path forming member  21 , the invention may be applied to a flow path member where ink flow paths (fluid flow paths) are formed on a separate member. Although the ink jet recording head has been described as an example of the liquid ejecting head, the invention is directed toward a variety of liquid ejecting heads, and may of course be applied to a liquid ejecting head which ejects a fluid other than ink. Examples of other liquid ejecting heads include various recording heads used in image recording apparatus, such as a printer, a color-material ejecting head used in manufacturing color filters for a liquid crystal display or the like, an electrode-material ejecting head used in forming electrodes of an organic EL display, FED (Field Emission Display) or the like, and a bio organic-substance ejecting head used in manufacturing bio chips.