Patent Publication Number: US-8985739-B2

Title: Cap for capping ink discharge opening of nozzle head in ink-jet recording apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon, and claims the benefit of priority from, corresponding Japanese Patent Application No. 2013-014592 filed in the Japan Patent Office on Jan. 29, 2013, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section. 
     An ink-jet recording apparatus is widely used for a printer, a multi-functional peripheral, and a copier, for example, due to reasons such as its compactness, inexpensive price, and quietness of operating sound. The ink-jet recording apparatus discharges ink droplets from many nozzles provided to an inkjet head and forms an image on a recording-target medium such as paper. 
     If ink is vaporized at an ink discharge opening at a distal end of the nozzle, density of ink increases. This may result in clogging of the ink discharge opening. Therefore, the ink-jet recording apparatus includes a cap that caps the ink discharge opening. 
     At the ink-jet recording apparatus, an interface of the ink is slightly depressed at the ink discharge opening by surface tension, forming a so-called meniscus. The meniscus is broken at considerably small pressure. If the meniscus is broken, a malfunction, such as unstable discharge of the ink, occurs at the ink-jet recording apparatus. 
     If the cap internal space is sealed with the ink discharge opening capped by the cap, the meniscus is possibly broken by pressure from the internal space. Thus, a structure having the internal space of the cap that communicates with the atmosphere has been proposed. 
     With this structure, one end of a metal pipe is communicatively coupled to a venthole formed at a cap main body via a cap base to allow the internal space of the cap to communicate with the atmosphere using the metal pipe. 
     SUMMARY 
     A cap according to a first aspect of the present disclosure is a cap for capping an ink discharge opening of a nozzle head includes a cap main body and an atmosphere communication unit. The cap main body is configured to cap the ink discharge opening. The atmosphere communication unit is configured to couple an internal space of the cap main body to the atmosphere in a state where the cap main body caps the ink discharge opening. The cap main body is configured to couple the internal space to the ink discharge opening in a state where the ink discharge opening is capped. The atmosphere communication unit includes a venthole integrally formed to the cap main body, and a tube coupled to the venthole so as to couple the internal space to the atmosphere. The tube includes one end coupled to the venthole using press fitting. 
     These as well as other aspects, advantages, and alternatives will become apparent to those of ordinary skill in the art by reading the following detailed description with reference where appropriate to the accompanying drawings. Further, it should be understood that the description provided in this summary section and elsewhere in this document is intended to illustrate the claimed subject matter by way of example and not by way of limitation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a schematic diagram illustrating a schematic configuration of an ink-jet recording apparatus according to an embodiment; 
         FIG. 2A  to  FIG. 2E  are schematic views illustrating operations of a conveyance unit and a cap unit of the ink-jet recording apparatus illustrated in  FIG. 1 ; 
         FIG. 3A  and  FIG. 3B  are perspective views illustrating a state where a cap is attached to a nozzle head illustrated in  FIG. 1 ; 
         FIG. 4A  and  FIG. 4B  are perspective views illustrating a state where the cap is removed from the nozzle head; 
         FIG. 5A  and  FIG. 5B  are cross-sectional views of the cap and the nozzle head; 
         FIG. 6  is a partial cutaway perspective view of the cap; 
         FIG. 7  is a plan view of the cap; 
         FIG. 8  is a bottom view of the cap; 
         FIG. 9  is a partially enlarged cross-sectional view of a cap main body; 
         FIG. 10A  and  FIG. 10B  are explanatory views of an action and effect when a tube is bent at one end side; 
         FIG. 11A  is a perspective view illustrating a state where a tube holder is removed from the cap main body and a bottom view of the tube holder; and 
         FIG. 11B  is a bottom view of the tube holder. 
     
    
    
     DETAILED DESCRIPTION 
     Example apparatuses are described herein. Other example embodiments or features may further be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. In the following detailed description, reference is made to the accompanying drawings, which form a part thereof. 
     The example embodiments described herein are not meant to be limiting. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the drawings, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein. 
     The following describes embodiments according to this disclosure with reference to the drawings.  FIG. 1  is a schematic diagram illustrating a schematic configuration of an ink-jet recording apparatus  1  according to an embodiment. 
     The ink-jet recording apparatus  1  includes an apparatus casing  100 , a paper sheet feeder  200 , an image forming unit  300 , a paper sheet conveyor  400 , and a paper discharge unit  500 . The paper sheet feeder  200  is disposed downward inside the apparatus casing  100 . The image forming unit  300  is disposed above the paper sheet feeder  200 . The paper sheet conveyor  400  is disposed on one side of the image forming unit  300  while the paper discharge unit  500  is disposed on the other side of the image forming unit  300 . 
     The paper sheet feeder  200  includes a paper feed cassette  201  attachable/detachable to/from the apparatus casing  100 , a paper feeding roller  202 , and a guide plate  203 . The paper feeding roller  202  is disposed upward of one end side of the paper feed cassette  201 . The guide plate  203  is disposed between the paper feeding roller  202  and the paper sheet conveyor  400 . 
     The paper feed cassette  201  internally houses many stacked paper sheets P. The paper feeding roller  202  takes out a paper sheet P in the paper feed cassette  201  one by one. The guide plate  203  guides the paper sheet P taken out by the paper feeding roller  202  to the paper sheet conveyor  400 . 
     The paper sheet conveyor  400  includes an approximately C-shaped paper sheet conveyance passage  401 , a conveyance roller pair  402 , a registration roller pair  403 , and a guide plate  404 . The conveyance roller pair  402  is disposed on the entry side of the paper sheet conveyance passage  401  while the registration roller pair  403  is disposed on the exit side of the paper sheet conveyance passage  401 . The guide plate  404  is disposed between the registration roller pair  403  and the image forming unit  300 . 
     The conveyance roller pair  402  sandwiches the paper sheet P fed from the paper sheet feeder  200  and delivers the paper sheet P to the paper sheet conveyance passage  401 . The registration roller pair  403  corrects a skew of the paper sheet P supplied from the paper sheet conveyance passage  401 . The registration roller pair  403  keeps the paper sheet P temporarily waiting to synchronize the timing of printing with the conveyance of the paper sheet P, and then delivers the paper sheet P to the guide plate  404  in accordance with the printing timing. The guide plate  404  guides the paper sheet P delivered by the registration roller pair  403  to the image forming unit  300 . 
     The image forming unit  300  includes a recording unit  310 , a drying unit  330 , a cap unit  360 , and a driving mechanism (not shown). 
     The recording unit  310  includes a conveyance unit  320 , a recording head  326 , a pump unit  327 , and a tank unit  328 . The recording head  326  is disposed above the conveyance unit  320  while the tank unit  328  is disposed below the conveyance unit  320 . The pump unit  327  is disposed above the recording head  326 . 
     The conveyance unit  320  includes a supporting roller  321 , a drive roller  322 , a tension roller  323 , an endless conveyance belt  324 , and a suction unit  325 . The conveyance belt  324  is tightly stretched between the supporting roller  321 , the drive roller  322 , and the tension roller  323 . Many suction holes (not shown) are bored on the conveyance belt  324 . 
     The drive roller  322  is spaced with respect to the supporting roller  321  in the paper sheet conveying direction. The drive roller  322  is rotatably driven by a motor (not shown) and rotates the conveyance belt  324  anticlockwise. The tension roller  323  is disposed downward between the supporting roller  321  and the drive roller  322  and adds tension to the conveyance belt  324  to prevent deflection of the conveyance belt  324 . 
     The recording head  326  is constituted to include four nozzle heads  326 K,  326 C,  326 M, and  326 Y arranged side by side from upstream to downstream in the paper sheet conveying direction. 
     The pump unit  327  is constituted to include four ink supply pumps  327 K,  327 C,  327 M, and  327 Y arranged side by side from upstream to downstream in the paper sheet conveying direction. 
     The tank unit  328  is constituted to include four ink tanks  328 K,  328 C,  328 M, and  328 Y arranged side by side from upstream to downstream in the paper sheet conveying direction. 
     Each of the nozzle heads  326 K,  326 C,  326 M, and  326 Y includes many nozzles arranged in a width direction (Y direction) of the conveyance belt  324 . The recording head  326  is referred to as a line type. The line type recording head  326  is, for example, secured to the apparatus casing  100 . 
     Each of many nozzles of the nozzle head  326 K communicates with the pressurization chamber (not shown) formed in the nozzle head  326 K. The pressurization chamber communicates with the ink liquid chamber (not shown) formed in the nozzle head  326 K. The ink liquid chamber is communicatively coupled to the ink supply pump  327 K via the tube (not shown). The ink supply pump  327 K is communicatively coupled to the ink tank  328 K via the tube (not shown). 
     Each of many nozzles of the nozzle head  326 C communicates with the pressurization chamber (not shown) formed in the nozzle head  326 C. The pressurization chamber communicates with the ink liquid chamber (not shown) formed in the nozzle head  326 C. The ink liquid chamber is communicatively coupled to the ink supply pump  327 C via the tube (not shown). The ink supply pump  327 C is communicatively coupled to the ink tank  328 C via the tube (not shown). 
     Each of many nozzles of the nozzle head  326 M communicates with the pressurization chamber (not shown) formed in the nozzle head  326 M. The pressurization chamber communicates with the ink liquid chamber (not shown) formed in the nozzle head  326 M. The ink liquid chamber is communicatively coupled to the ink supply pump  327 M via the tube (not shown). The ink supply pump  327 M is communicatively coupled to the ink tank  328 M via the tube (not shown). 
     Each of many nozzles of the nozzle head  326 Y communicates with the pressurization chamber (not shown) formed in the nozzle head  326 Y. The pressurization chamber communicates with the ink liquid chamber (not shown) formed in the nozzle head  326 Y. The ink liquid chamber is communicatively coupled to the ink supply pump  327 Y via the tube (not shown). The ink supply pump  327 Y is communicatively coupled to the ink tank  328 Y via the tube (not shown). 
     The suction unit  325  is disposed on one surface side of the conveyance belt  324  so as to face the recording head  326  across the conveyance belt  324 . The suction unit  325  internally includes a suction mechanism (not shown), such as a fan and a vacuum pump. Driving the suction mechanism generates negative pressure in the suction unit  325 . The negative pressure acts on the paper sheet P placed on the other surface of the conveyance belt  324  through many suction holes on the conveyance belt  324  and then the paper sheet P is suctioned onto the conveyance belt  324 . 
     A drying unit  330  includes a conveyance unit  340 , a dryer  350 , and a guide plate  355 . The dryer  350  is disposed above the conveyance unit  340 . 
     The conveyance unit  340  includes a supporting roller  341 , a drive roller  342 , an endless conveyance belt  343 , and a suction unit  344 . The conveyance belt  343  is tightly stretched between the supporting roller  341  and the drive roller  342 . Many suction holes (not shown) are bored on the conveyance belt  343 . 
     The drive roller  342  is spaced with respect to the supporting roller  341  in the paper sheet conveying direction. The drive roller  342  is rotatably driven by a motor (not shown) and rotates the conveyance belt  343  counter-clockwise. 
     The suction unit  344  is disposed on one surface side of the conveyance belt  343  so as to face the dryer  350  across the conveyance belt  343 . The suction unit  344  internally includes a suction mechanism (not shown), such as a fan and a vacuum pump. Driving the suction mechanism generates negative pressure in the suction unit  344 . The negative pressure acts on the paper sheet P placed on the other surface of the conveyance belt  343  through many suction holes on the conveyance belt  343  and then the paper sheet P is suctioned onto the conveyance belt  343 . 
     The dryer  350  may blow hot air to the paper sheet P to dry ink droplets discharged from the recording head  326  onto the paper sheet P. 
     The guide plate  355  guides the paper sheet P delivered by the conveyance unit  340  to the paper discharge unit  500 . 
     The cap unit  360  includes a plurality of caps  361 . The plurality of caps  361  are disposed corresponding to the respective nozzle heads  326 K,  326 C,  326 M, and  326 Y. The cap unit  360  is supported by a support bracket (not shown). The support bracket is slidably guided to the X direction by a guide rail (not shown). The cap  361  will be described in detail later. 
     A driving mechanism (not shown) moves the cap unit  360  in the X direction by sliding the support bracket, which supports the cap unit  360 , along the guide rail (not shown). 
     The paper discharge unit  500  includes a discharge roller pair  501  and a discharge tray  502 . The discharge tray  502  is secured to the apparatus casing  100  so as to project outside from a discharge port  101  formed at the apparatus casing  100 . 
     The paper sheet P that has passed the dryer  350  is delivered in the direction of the discharge port  101  by the discharge roller pair  501 , guided by the discharge tray  502 , and discharged outside of the apparatus casing  100  via the discharge port  101 . 
       FIG. 2A  to  FIG. 2E  are schematic views illustrating operations of the conveyance unit  320  and the cap unit  360  of the ink-jet recording apparatus  1  illustrated in  FIG. 1 . 
     The ink-jet recording apparatus  1  further includes an elevating mechanism  381 . The elevating mechanism  381  moves up and down the conveyance unit  320  of the recording unit  310 . The elevating mechanism  381  includes a guiding member (not shown), a wire  382 , a roller  384 , a motor  386 , and a clutch  388 . 
     The guiding member extends in the vertical direction and liftably guides the conveyance unit  320  in the Z direction. 
     One end of the wire  382  is installed to the conveyance unit  320  and the other end is installed to the roller  384 . The wire  382  suspends and supports the conveyance unit  320 . 
     The roller  384  is rotatably centering a rotation shaft (not shown) extending in the X direction. By rotation of the roller  384  in one direction, the wire  382  is rolled up by the roller  384 , and by rotation of the roller  384  in the other direction, the wire  382  is wound off the roller  384 . 
     A drive shaft (not shown) of the motor  386  is coupled to the rotation shaft of the roller  384  via the clutch  388 . The motor  386  rotates the roller  384  in both directions. 
     The clutch  388  switches a state where the drive shaft for the motor  386  is coupled to the rotation shaft for the roller  384  and a state where the drive shaft for the motor  386  is detached from the rotation shaft for the roller  384 . 
     Next, operations of the conveyance unit  320  and the cap unit  360  will be described based on  FIG. 2A  to  FIG. 2E . 
       FIG. 2A  illustrates a state where an image can be formed on a paper sheet. The nozzle heads  326 K,  326 C,  326 M, and  326 Y of the recording head  326  discharge ink on the paper sheet, and the dryer  350  dries the ink on the paper sheet, thus the image is formed on the paper sheet. 
     To cap the ink discharge opening of the recording head  326 , as illustrated in  FIG. 2B , the motor  386  of the elevating mechanism  381  is driven first, the wire  382  is wound off the roller  384 , and the conveyance unit  320  moves down to a retracted position. 
     Next, as illustrated in  FIG. 2C , the driving mechanism (not shown) horizontally moves the cap unit  360  and disposes the cap unit  360  immediately below the recording head  326 . 
     Next, as illustrated in  FIG. 2D , the motor  386  for the elevating mechanism  381  is driven, the wire  382  is rolled up by the roller  384 , the conveyance unit  320  goes up, and the conveyance unit  320  contacts the cap unit  360 . 
     Next, as illustrated in  FIG. 2E , the motor  386  of the elevating mechanism  381  is driven, the wire  382  is rolled up by the roller  384 , and the conveyance unit  320  and the cap unit  360  go up. Then, the four caps  361  of the cap unit  360  contact the nozzle heads  326 K,  326 C,  326 M, and  326 Y of the recording head  326 . As a result, the ink discharge openings of the nozzle heads  326 K,  326 C,  326 M, and  326 Y are capped. 
       FIG. 3A  and  FIG. 3B  illustrate a state where the cap  361  is attached to the nozzle head  326 K illustrated in  FIG. 1 .  FIG. 3A  is viewed from upward, and  FIG. 3B  is viewed from downward.  FIG. 4A  and  FIG. 4B  illustrate a state where the cap  361  is removed from the nozzle head  326 K.  FIG. 4A  is viewed from upward, and  FIG. 4B  is viewed from downward.  FIG. 5A  and  FIG. 5B  are cross-sectional views of the cap  361  and the nozzle head  326 K.  FIG. 5A  illustrates a state where the cap  361  is attached to the nozzle head  326 K, and  FIG. 5B  illustrates a state where the cap  361  is removed from the nozzle head  326 K. 
     The cap  361  is attachably/detachably attached to the bottom surface of the nozzle head  326 K. In  FIG. 4B , four trapezoidal-shaped regions illustrated at the bottom surface of the nozzle head  326 K indicate ink discharge openings  326 Ka. Structures of the nozzle heads  326 C,  326 M, and  326 Y are basically the same as the structure of the nozzle head  326 K. Accordingly, the descriptions on the nozzle heads  326 C,  326 M, and  326 Y will not be further elaborated here. 
     As illustrated in  FIG. 4B , the cap  361  includes a cap main body  362 , a tube  366 , a guiding member  367  (see  FIG. 5A  and  FIG. 5B ), and a tube holder  368 . The cap main body  362  includes two engaging holes  365  on both side surfaces. As illustrated in  FIG. 5A , the cap main body  362  includes the four ventholes  364  (details will be described later) on the top surface. 
       FIG. 6  is a partial cutaway perspective view of the cap  361 .  FIG. 7  is a plan view of the cap  361 .  FIG. 8  is a bottom view of the cap  361 . 
     As illustrated in  FIG. 6 , the cap main body  362  is an elongated plate-shaped member. The cap main body  362  is formed of synthetic resin excellent in modulus of repulsion elasticity and deterioration resistance, such as Ethylene Propylene Diene Methylene (EPDM) and butyl rubber. The cap main body  362  includes an annular rib  363 , the four ventholes  364 , and the four engaging holes  365  (see  FIG. 4B ). 
     The annular rib  363  projects upward from the top surface of the cap main body  362  and is formed in an ellipse shape in plan view as illustrated in  FIG. 7 . By attaching the cap  361  to the nozzle head  326 K, the upper end portion of the annular rib  363  is brought into pressure contact with the bottom surface of the nozzle head  326 K. Each of the four ink discharge openings  326 Ka (see  FIG. 4B ) is positioned inside of the annular rib  363 , thus being capped by the cap main body  362 . With the ink discharge openings  326 Ka capped by the cap main body  362 , an internal space S (see  FIG. 5A ) of the cap main body  362  communicates with the ink discharge openings  326 Ka. 
     As illustrated in  FIG. 6 , the venthole  364  has a cylindrical shape and projects upward from the top surface of the cap main body  362  at the inner region of the annular rib  363 . Each of the four ventholes  364  is integrally formed with the annular rib  363 . Each of the four ventholes  364  is formed to be positioned outside of the regions where the four ink discharge openings  326 Ka (see  FIG. 4B ) are projected on the top surface of the cap main body  362 . Accordingly, ink dropped from the ink discharge openings  326 Ka is unlikely to flow into the ventholes  364 . As a result, this reduces the ventholes  364  from being blocked with ink. 
     The tube  366  is formed of low-density polyethylene, for example. Low-density polyethylene provides good barrier property against water vapor and is easily formed in a tube shape. One end of the tube  366  is coupled to the venthole  364  using press fitting and the other end is open to the atmosphere. The tube  366  causes the internal space S (see  FIG. 5A ) to communicate with the atmosphere. In this embodiment, the venthole  364  and the tube  366  constitute an atmosphere communication unit according to this disclosure. 
     It is preferred that the tube  366  and the cap main body  362  be secured with adhesive. In the case where the tube  366  is formed of low-density polyethylene and the cap main body  362  is formed of EPDM, use of cyanoacrylate-based instantaneous adhesive is preferred. Use of the cyanoacrylate-based instantaneous adhesive shortens the bonding period of the tube  366  made of low-density polyethylene and the cap main body  362  made of EPDM, which does not have good adhesive property with such tube  366 , thus improving production efficiency. 
       FIG. 9  is a partially enlarged cross-sectional view of the cap main body  362 . The venthole  364  includes a stopper  364   a  at an inner periphery at the upper end. The tube  366  includes a tip end face  366   a  at the one end. The tip end face  366   a  contacts the stopper  364   a , and then the tube  366  is restricted to a press-in direction. This allows reducing contact of the tip end face  366   a  of the tube  366  with a component other than the cap main body  362  and blocking a ventilation passage  366   b  of the tube  366 . 
     The stopper  364   a  is formed in a flange shape projecting toward the inside of the venthole  364  in the radial direction and includes a communication hole  364   b  at the center. With the tip end face  366   a  of the tube  366  contacting the stopper  364   a , the internal space S (see  FIG. 5A ) communicates with the inside of the tube  366  via the communication hole  364   b . Relationship among a diameter D1 of the communication hole  364   b , an inner diameter D2 of the tube  366 , and an inner diameter D3 of the venthole  364  is D2&lt;D1&lt;D3 in the example of  FIG. 9 . The relationship may be D1&lt;D2&lt;D3. It is only necessary to design the relationship to be D1&lt;D3. The tip end face  366   a  of the tube  366  contacting the stopper  364   a  is located inward of the cap main body  362  with respect to an inner wall surface  362   a  of the cap main body  362 . 
       FIG. 10A  and  FIG. 10B  are explanatory views of an action and effect when the tube  366  is bent at one end side.  FIG. 10A  illustrates a case where the guiding member  367  is not disposed at the cap  361 .  FIG. 10B  illustrates a case where the guiding member  367  is disposed at the cap  361 . 
     As illustrated in  FIG. 10A , when one end side of the approximately horizontal tube  366  is bent and the one end of the tube  366  is coupled to the venthole  364 , the tube  366  does not hang down in the axial direction of the venthole  364 . This allows reducing a space below the cap  361 . 
     As illustrated in  FIG. 10B , when the one end side of the approximately horizontal tube  366  is bent in a circular arc shape along a circumference surface of the guiding member  367  with cross-sectional semicolumnar shape, and the one end of the tube  366  is coupled to the venthole  364 , a cross-sectional area of the curving part of the ventilation passage  366   b  of the tube  366  becomes approximately equal to a cross-sectional area of a straight line part of the ventilation passage  366   b . Accordingly, in addition to the effect that the space below the cap  361  can be saved, pressure loss is unlikely to occur in the ventilation passage  366   b , thus achieving an action and effect of good air circulation in the tube  366 . Since a force acting on the one end of the tube  366  in the direction of exiting from the venthole  364  becomes smaller compared with the case illustrated in  FIG. 10A , the one end of the tube  366  is unlikely to be detached from the venthole  364 . Accordingly, reliability improves. 
       FIG. 11A  is a perspective view illustrating a state where the tube holder  368  is removed from the cap main body  362 .  FIG. 11B  is a bottom view of the tube holder  368 . 
     The tube holder  368  is a frame-shaped member and is formed of synthetic resin. The tube holder  368  includes four engaging claws  369  (only two of them are shown) and six tube engaging units  370 . 
     The cap main body  362  includes the two engaging holes  365  at an interval on each of both side surfaces. The engaging claw  369  of the tube holder  368  is freely engaged/disengaged with/from each of the four engaging holes  365 . The four engaging claws  369  freely engage/disengage the cap main body  362  by being urged against the cap main body  362  in a direction within a plane approximately parallel to the bottom surface of the nozzle head  326 K. This consequently saves the space below the cap  361 . The engaging claws  369  are also referred to as a cap engaging portion. 
     The four engaging claws  369  are disposed on both side surfaces of the tube holder  368  by two by two at an interval. By moving the top surface of the tube holder  368  close to the bottom surface of the cap main body  362 , each of the four engaging claws  369  engages the engaging hole  365  of the cap main body  362 , thus the tube holder  368  is secured to the cap main body  362 . By pressing each of the four engaging claws  369  inward of the cap main body  362 , the engaging claw  369  and the engaging hole  365  are disengaged, thus the tube holder  368  is detached from the cap main body  362 . 
     The tube engaging unit  370  includes a pair of protrusions  370   a  and  370   b  facing one another. The tube engaging unit  370  functions as a tube holding unit that engageably/disengageably holds the tube  366 . The tube holder  368  includes a rib  371  across the longitudinal direction of the tube holder  368 . The rib  371  and the protrusion  370   a  of the tube engaging unit  370  function as a tube holding unit that engageably/disengageably holds the tube  366 . The pair of protrusions  370   a  and  370   b  engageably/disengageably hold the tube  366  by being urged against the tube  366  in a direction within the plane approximately parallel to the bottom surface of the nozzle head  326 K. This consequently saves the space below the cap  361 . The protrusions  370   a  and  370   b  are also referred to as a tube holding portion. 
     When the tube  366  is pressed into between the protrusions  370   a  and  370   b  from the lower side of the tube holder  368 , the tube  366  engages between the protrusions  370   a  and  370   b , thus the tube  366  is securely held. When the tube  366  is pressed into between the protrusion  370   a  and the rib  371  from the lower side of the tube holder  368 , the tube  366  engages between the protrusion  370   a  and the rib  371 , thus the tube  366  is securely held. This allows securing the tube  366  to the tube holder  368  in a single operation of good work efficiency, thus enhancing work efficiency. 
     As illustrated in  FIG. 11B , the two tubes  366  among the four tubes  366  are secured with the three tube engaging units  370 . The remaining two tubes  366  are interposed between the rib  371  and the protrusions  370   a  of the three tube engaging units  370  and are secured. The four tubes  366  are held approximately parallel to the bottom surface of the nozzle head  326 K with the tube holder  368 . 
     The cap  361  and the ink-jet recording apparatus  1  according to this disclosure are described with reference to  FIG. 1  to  FIG. 11B . According to this disclosure, the one end of the tube  366  is directly coupled to the venthole  364  formed at the cap main body  362  using press fitting; and therefore no another component is interposed between the one end of the tube  366  and the cap main body  362 . Accordingly, the cap  361  has a simple structure, achieving low production cost, compared with the complicated structure of the related art that couples the metal pipe to the cap main body through a cap base, for example. 
     Compared with the case where another component is interposed between the one end of the tube  366  and the cap main body  362 , the reduced number of bonding points of components improves air tightness in the internal space S of the cap main body  362 . 
     Since the four ventholes  364  are disposed at the cap main body  362 , even if a part of the venthole  364  is blocked with, for example, a foreign object, the internal space S can be kept communicating with the atmosphere via another venthole  364 . This achieves high reliability. 
     Since the tip end face  366   a  of the tube  366  is positioned inward of the cap main body  362  with respect to the inner wall surface  362   a  of the cap main body  362 , a foreign object deposited on the inner wall surface  362   a  of the cap main body  362  is unlikely to flow into the tube  366 . Accordingly, the tube  366  is unlikely to be blocked with the foreign object, thus providing high reliability. 
     Embodiments of the disclosure are described above. It will be appreciated that the disclosure will not be limited to the embodiments described above, but various modifications can be made to the embodiments described above. 
     In the embodiment, the four ventholes are formed at the cap main body; however, equal to or less than three or equal to or more than five ventholes may be formed at the cap main body, for example. 
     In the embodiment, the cap includes four tubes; however, equal to or less than three or equal to or more than five tubes may be included. 
     In the embodiment, three tube holding units are disposed for one tube; however, equal to or less than two or equal to or more than four tube holding units may be disposed for one tube. 
     In the embodiment, the case where this disclosure is applied to the ink-jet recording apparatus with the line type recording head secured to the apparatus casing is described; however, this disclosure is not limited to such ink-jet recording apparatus. This disclosure may be applied to the ink-jet recording apparatus with a recording head moving with respect to the apparatus casing, for example. This disclosure may be applied to the ink-jet recording apparatus with a serial type recording head, for example. 
     Besides, various modifications can be made to the embodiments described above without departing from the gist of the disclosure. 
     While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.