Patent Publication Number: US-10322585-B2

Title: Inkjet printer

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to Japanese Patent Application No. 2017-150156 filed on Aug. 2, 2017 and Japanese Patent Application No. 2018-107668 filed on Jun. 5, 2018. The entire contents of these applications are hereby incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to inkjet printers. 
     2. Description of the Related Art 
     An inkjet printer known in the related art includes an ink head provided at its nozzle surface with a plurality of nozzles and is configured to effect predetermined printing on a recording medium in an inkjet mode. Such an inkjet printer is provided with a cap unit in order to maintain discharge performance of the nozzles at a suitable level. The cap unit includes a cap to cover the nozzle surface when no printing is being effected. 
     The cap unit covers the nozzle surface with the cap so as to define an enclosed space between the nozzle surface and the cap. The cap unit includes a suction pump connected to the cap. The suction pump is driven, with the enclosed space defined, so that ink remaining in the nozzles is forcedly discharged to the cap. This prevents ink from solidifying in the nozzles and thus precludes clogging of the nozzles. A suction operation to discharge ink remaining in the ink head is generally referred to as “main suction”. 
     After main suction, the suction pump is driven again, with the enclosed space exposed to atmospheric pressure, in order to discharge ink remaining in the cap unit, such as ink remaining in the cap or suction path. This makes it possible to discharge ink remaining in the cap unit without applying any excessive negative pressure to the ink head. A suction operation to discharge ink in the cap unit is generally referred to as “idle suction”. A combination of main suction and idle suction may be referred to as “suction cleaning”. Japanese Patent No. 3981502, for example, discloses a technique involving performing idle suction, with the cap detached from the nozzle surface, or performing idle suction after the enclosed space is exposed to atmospheric pressure through an atmospheric pressure exposure element, with the cap in intimate contact with the nozzle surface. 
     To meet recent demands for printers that are able to effect colorful, high-resolution printing, the number of types of ink used in each printer and the number of ink heads of each printer tend to increase. A cap unit, such as one described above, is usually provided for each ink head. Thus, an increase in the number of ink heads unfortunately increases the number of components of ink supply paths leading to the ink heads. In addition, the number of components of the cap unit also increases, resulting in an increase in size of a printer. 
     When a cap is detached from a nozzle surface so as to perform idle suction described above, ink discharged toward the cap may keep adhering to the nozzle surface. The ink adhering to the nozzle surface is naturally sucked into a nozzle owing to the negative pressure of an ink supply path. This may make it impossible to prevent nozzle clogging. When two or more types of ink are supplied to a single ink head, ink adhering to the nozzle surface becomes ink of mixed colors that unfavorably contaminates the nozzle. To solve such a problem, an atmospheric pressure exposure element is desirably provided for each cap. An inexpensive atmospheric pressure exposure element, however, is likely to take up space, making it difficult to design a layout of the atmospheric pressure exposure element. 
     SUMMARY OF THE INVENTION 
     Accordingly, preferred embodiments of the present invention provide inkjet printers each including a cap unit including an atmospheric pressure exposure element without any excessive increase in overall size of the inkjet printer and that is readily adaptable to an increase in the number of ink heads. 
     An inkjet printer according to a preferred embodiment of the present invention includes a plurality of ink heads, an ink head conveyor, a plurality of caps, a cap conveyor, a plurality of suction devices, a plurality of cap valves, a plurality of first passages, and a plurality of second passages. The ink head conveyor moves the ink heads in a main scanning direction. The main scanning direction includes a first direction and a second direction opposite to the first direction. The caps are each detachably attachable to an associated one of the ink heads. The cap conveyor supports the caps. The cap conveyor moves the caps between a cap attaching position at which the caps are attached to the ink heads and a retracted position at which the caps are detached from the ink heads. The suction devices are each provided for an associated one of the caps. The first passages each connect an associated one of the caps to an associated one of the cap valves. The second passages each connect an associated one of the caps to an associated one of the suction devices. The cap conveyor includes a base, a movable table, a support wall, and a table urging member. The movable table supports the caps. The support wall stands vertically or substantially vertically on the base. The support wall supports the movable table such that the movable table is movable between the cap attaching position and the retracted position. The table urging member urges the movable table to the retracted position. The movable table includes a table wall extending upward from an end of the movable table facing in the first direction. The first direction is a direction extending to the cap attaching position in the main scanning direction. The cap valves are disposed on a surface of the table wall facing in the first direction. 
     In this preferred embodiment, the movable table of the cap conveyor includes the table wall on which the cap valves functioning as atmospheric pressure exposure elements are disposed such that the cap valves are located above the movable table supporting the caps and do not interfere with movement of the ink heads. Thus, if the ink heads and the cap valves are increased in number, this preferred embodiment would make it possible to dispose the cap valves without increasing the area occupied by the cap valves in a plan view. Consequently, this preferred embodiment provides a cap unit including the cap valves without entailing an increase in overall size of the inkjet printer. 
     Various preferred embodiments of the present invention provide inkjet printers each including a cap unit including an atmospheric pressure exposure element without any excessive increase in overall size of the inkjet printer and that is readily adaptable to an increase in the number of ink heads. 
     The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an inkjet printer according to a preferred embodiment of the present invention, with the inkjet printer partially cut out. 
         FIG. 2  is a front view of a cap unit according to a preferred embodiment of the present invention. 
         FIG. 3  is a schematic diagram illustrating ink discharge paths according to a preferred embodiment of the present invention. 
         FIG. 4  is a partial perspective view of the cap unit according to a preferred embodiment of the present invention. 
         FIG. 5  is a cross-sectional view of a cap according to a preferred embodiment of the present invention, illustrating the structure of the cap. 
         FIG. 6  is a front view of a composite cap valve according to a preferred embodiment of the present invention, illustrating the closed state of the composite cap valve. 
         FIG. 7A  is a cross-sectional view of the cap valve according to a preferred embodiment of the present invention, illustrating the open state of the cap valve. 
         FIG. 7B  is a cross-sectional view of the cap valve according to a preferred embodiment of the present invention, illustrating the closed state of the cap valve. 
         FIG. 8  is a perspective view of lifters of a conveyor according to a preferred embodiment of the present invention, illustrating the structure of each lifter. 
         FIG. 9A  is a front view of main components of the cap unit located at a standby position. 
         FIG. 9B  is a front view of the main components of the cap unit located at a cap attaching position. 
         FIG. 9C  is a front view of the main components of the cap unit located at a valve opening position. 
         FIG. 10  is a block diagram illustrating the configuration of a controller according to a preferred embodiment of the present invention. 
         FIG. 11  is a flow chart illustrating the procedure of suction cleaning according to a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Inkjet printers according to preferred embodiments of the present invention will be described below with reference to the drawings. The preferred embodiments described below are naturally not intended to limit the present invention in any way. Components or elements having the same functions are identified by the same reference signs, and description thereof will be omitted or simplified if deemed redundant. 
       FIG. 1  is a perspective view of an inkjet printer  1  according to the present preferred embodiment. The inkjet printer  1  will hereinafter be referred to as a “printer  1 ”. The printer  1  effects printing in an inkjet mode. As used herein, the term “inkjet mode” refers to an inkjet mode that involves techniques including various continuous methods, such as a binary deflection method and a continuous deflection method, and various on-demand methods, such as a thermal method and a piezoelectric method. In the following description, the reference signs F, Rr, R, L, U, and D in the drawings respectively represent front, rear, right, left, up, and down with respect to a user facing the front of the printer  1 . The reference signs F, Rr, R, L, U, and D in the drawings may respectively represent a front side, a rear side, a right side, a left side, an upper side, and a lower side. The reference signs F, Rr, R, L, U, and D in the drawings may respectively represent a forward direction, a rearward direction, a rightward direction, a leftward direction, an upward direction, and a downward direction. The reference sign Y in the drawings represents a main scanning direction. The main scanning direction Y corresponds to a direction in which an ink head unit  30  (which will be described below) moves. In the present preferred embodiment, the main scanning direction Y is a right-left direction. The main scanning direction Y includes the rightward direction R and the leftward direction L. For the sake of convenience, the rightward direction R may be referred to as a “first direction Y 1 ”, and the leftward direction L may be referred to as a “second direction Y 2 ”. The reference sign X in the drawings represents a sub-scanning direction. The sub-scanning direction X corresponds to a direction in which a recording medium  8  is to be conveyed. The sub-scanning direction X is a direction intersecting the main scanning direction Y. In one example, the sub-scanning direction X intersects the main scanning direction Y at right angles in a plan view. In the present preferred embodiment, the sub-scanning direction X is a front-rear direction. The reference sign Z in the drawings represents a height direction. In the present preferred embodiment, the height direction Z is an up-down direction. These directions are defined merely for the sake of convenience of description and do not limit in any way how the printer  1  may be installed. 
     As illustrated in  FIG. 1 , the printer  1  is structured to effect printing on the recording medium  8 . The printer  1  includes a body  2 , legs  4 , a guide rail  10 , a cap unit  40 , a conveyor  50 , and a controller  100  (see  FIG. 10 ). The body  2  is supported by the legs  4 . The legs  4  are provided on the lower surface of the body  2 . The front portion of the body  2  is provided with a platen  6 . The recording medium  8  is placed on the platen  6 . 
     In the present preferred embodiment, the recording medium  8  is rolled recording paper or “rolled paper”. The recording medium  8 , however, is not limited to rolled recording paper. The recording medium  8  may be any medium other than paper (e.g., plain paper and inkjet printing paper). Examples of the recording medium  8  include: a resin sheet or film made of polyvinyl chloride or polyester, for example; a plate material; and a fabric, such as a woven fabric or a nonwoven fabric. The recording medium  8  may be any other suitable medium. In the present preferred embodiment, a material for the recording medium  8  is not limited to any particular material. 
     The printer  1  includes the platen  6  on which the recording medium  8  is to be placed. The platen  6  is provided with cylindrical grit rollers  16  that define and function as components of a recording medium conveyor. The grit rollers  16  are embedded in the platen  6 , with the upper surfaces of the grit rollers  16  exposed. The grit rollers  16  are driven by a feed motor (not illustrated). 
     The guide rail  10  is disposed above the platen  6 . The guide rail  10  is disposed in parallel or substantially in parallel with the platen  6 . The guide rail  10  extends in the main scanning direction Y. The printer  1  further includes a plurality of pinch rollers  18  disposed below the guide rail  10 . The pinch rollers  18  are located at equal or substantially equal intervals. The pinch rollers  18  each face an associated one of the grit rollers  16 . The position of each pinch roller  18  in the up-down direction Z is adjustable in accordance with the thickness of the recording medium  8 . The recording medium  8  is sandwiched between each pinch roller  18  and the associated grit roller  16 . Rotating the grit rollers  16  by the feed motor enables the grit rollers  16  and the pinch rollers  18  to convey the recording medium  8  in the sub-scanning direction X, with the recording medium  8  sandwiched between each grit roller  16  and the associated pinch roller  18 . The grit rollers  16 , the pinch rollers  18 , and the feed motor are an example of the recording medium conveyor to move the recording medium  8  and the ink head unit  30  (which will be described below) relative to each other in the sub-scanning direction X. 
     The printer  1  includes the ink head unit  30 . As illustrated in  FIG. 2 , the ink head unit  30  includes ink heads  32 , a case  34 , a head plate  36 , and a carriage  31  (see  FIG. 1 ). To meet recent demands for printers to effect high speed, high quality printing, the number of ink heads included in each printer is increasing. The number of ink heads  32  included in the printer  1  is eight in total. The head plate  36  retains the ink heads  32 . The head plate  36  is secured to the carriage  31 . A region above the head plate  36  and the ink heads  32  are covered with the case  34 . The case  34  is disposed on the carriage  31 . An end of the carriage  31  facing in the first direction Y 1  includes an engagement portion  31 A that comes into engagement with the cap unit  40  (which will be described below). The back surface of a rear portion of the carriage  31  is provided with a recess  31 B (see  FIG. 1 ) recessed forward. 
     As illustrated in  FIG. 1 , the upper portion of the guide rail  10  supports a timing belt  12  extending in the main scanning direction Y. The timing belt  12  is an annular endless belt. The timing belt  12  is wound around a timing pulley and a driven pulley (which are not illustrated). The timing pulley is disposed on one of the right and left ends of the guide rail  10 , and the driven pulley is disposed on the other one of the right and left ends of the guide rail  10 . The timing pulley is connected to a scan motor (not illustrated). Rotating the scan motor causes the timing belt  12  to run around the timing pulley and the driven pulley. The guide rail  10  includes an engagement portion  14  protruding forward. The engagement portion  14  of the guide rail  10  and the recess  31 B of the carriage  31  are in slidable engagement with each other. Running of the timing belt  12  moves the carriage  31  in the main scanning direction Y along the guide rail  10 . The movement of the carriage  31  enables the ink head unit  30  to move in the main scanning direction Y along the guide rail  10 . The ink head unit  30  is disposed above the platen  6 , with the carriage  31  located between the ink head unit  30  and the platen  6 . The guide rail  10 , the timing belt  12 , the timing pulley, the driven pulley, and the scan motor are an example of a carriage conveyor to move the ink head unit  30  relative to the recording medium  8  in the main scanning direction Y. The carriage  31 , the carriage conveyor, and the engagement portion  31 A are an example of an ink head conveyor. 
     As illustrated in  FIG. 2 , the head plate  36  is provided with through holes  36   a  through which the ink heads  32  are secured in position. The through holes  36   a  are provided in accordance with the arrangement of the ink heads  32 . The ink heads  32  are disposed in the head plate  36  such that the ink heads  32  are arranged at regular intervals in the main scanning direction Y. In order to effect high-resolution printing in a short time, the present preferred embodiment involves disposing the ink heads  32  such that the ink heads  32  having the same functions are provided in pairs and the ink heads  32  of each pair are adjacent to each other and out of alignment with each other in the front-rear direction. This enables the printer  1  to effect high speed printing with a doubled print span in the sub-scanning direction X. The lower surface of each ink head  32  is a nozzle surface. The nozzle surface of each ink head  32  is provided with a large number of nozzles. Each nozzle discharges ink onto the recording medium  8 . In the present preferred embodiment, the nozzle surface of each ink head  32  is provided with two nozzle rows each including a plurality of nozzles. Each nozzle row extends in the sub-scanning direction X. The nozzle surface of each ink head  32  is located below the lower surface of the head plate  36 . 
     The printer  1  includes an ink feeder (not illustrated). The ink feeder feeds ink from ink tanks  21  to the nozzles arranged in the ink heads  32 . Each ink tank  21  stores ink. The ink stored in the ink tanks  21  is fed to the ink heads  32  through ink passages (not illustrated). Each ink passage is not limited to any particular type or material. In one example, each ink passage is a flexible silicon tube. In the present preferred embodiment, the number of ink tanks  21  is equal to the number of ink heads  32 . The ink tanks  21  according to the present preferred embodiment are each connected to two of the ink heads  32 . A single passage connected to each ink tank  21  is split into two passages at some point. Ink stored in two of the ink tanks  21  is fed to four different nozzle rows provided in an associated pair of the ink heads  32 . Thus, two different types of ink are fed to each ink head  32  from the associated two ink tanks  21 . The ink tanks  21  normally store ink of different colors. Alternatively, some of the ink tanks  21  may store ink of the same color. The ink stored in each ink tank  21  is not limited to any particular color. In one example, the ink stored in each ink tank  21  may be any one of: process color ink, such as cyan ink, magenta ink, yellow ink, black ink, light cyan ink, light magenta ink, and light black ink; and spot color ink, such as white ink, metallic ink, and clear ink. 
     A feed pump (not illustrated) is provided at a location somewhere along each ink passage connected to the associated ink tank  21 . Each feed pump sends a fluid (e.g., ink) in the ink passage from the upstream side to the downstream side. Each feed pump is provided on a portion of the associated ink passage located upstream of the point where the ink passage is split into two passages. During operation, the feed pumps send ink from the ink tanks  21  to the ink heads  32 . Each feed pump is not limited to any particular type. In one example, each feed pump is a tube pump. The tube pump internally includes an inner tube and a roller. The tube pump rotates the roller in a planetary manner while the roller crushes the inner tube, so that ink is sent in the direction of travel of the roller. The tube pump may send ink from the downstream side to the upstream side by rotating the roller in a planetary manner in a reverse direction. 
     A portion of the ink passage located between each ink tank  21  and the feed pump is provided with a pressure control valve (not illustrated). Each pressure control valve maintains the inside of the nozzles of the associated ink heads  32  at a negative pressure when no ink is being discharged. As used herein, the term “negative pressure” refers to a pressure lower than an external pressure (which is typically atmospheric pressure). Maintaining the inside of the ink heads  32  at a negative pressure prevents ink in the ink heads  32  from trickling down to the outside through the nozzles. Each pressure control valve maintains ink in the nozzles of the ink heads  32  at about −1 kPa. Each pressure control valve includes: a passage through which ink flows; and a valve operating mechanism to open and close the passage. The valve operating mechanism opens and closes in accordance with the fluid pressure in a region downstream of the valve operating mechanism. The valve operating mechanism receives the pressure of ink upstream of the valve operating mechanism, the pressure of ink downstream of the valve operating mechanism, a mechanical force that will close the valve operating mechanism, and a mechanical force that will open the valve operating mechanism. When the printer  1  is not in use, these pressures and forces keep their balance. In such a balanced state, the valve operating mechanism seals the passage. The pressure of ink in this state is the pressure of ink at rest, which is maintained at about −1 kPa. The mechanical force that will close or open the valve operating mechanism is, for example, a restoring force of a spring. Activating a suction pump  46  sucks out ink from a region downstream of the valve operating mechanism. This reduces the pressure of ink on the downstream side so as to disturb the balance, causing the valve operating mechanism to open. Once the valve operating mechanism opens, the passage is opened so as to feed ink in the downstream direction. With such a mechanism, each pressure control valve maintains ink at a negative pressure when the printer  1  is not in use, and sends ink to the associated ink heads  32  when the printer  1  is in use. 
     A damper (not illustrated) is provided at a location somewhere along each ink passage connected to the associated ink tank  21 . The dampers are provided immediately upstream of the ink heads  32 . The dampers store ink to be sent to the ink heads  32  so as to reduce variations in ink pressure and stabilize discharge operation of the ink heads  32 . Each of the dampers according to the present preferred embodiment includes: a storage chamber to store ink; and a sensor to detect the pressure of ink stored in the storage chamber. The pressure of ink stored in the storage chamber is equal or substantially equal to the pressure inside the nozzles. The sensor is an example of a detector to detect the pressure inside the nozzles. During printing, each damper keeps the pressure of ink stored in the storage chamber within a predetermined range so as to reduce variations in ink pressure. In one example, the sensor of each damper is a photosensor for position detection. One of wall surfaces of the storage chamber of each damper is a film that expands and contracts so as to deform in a concavo-convex manner in response to the pressure of ink stored in the storage chamber. The sensor of each damper detects the pressure of ink inside the storage chamber in accordance with the concavo-convex deformation of the film. When the film expands beyond a first reference position, the sensor transmits an upper limit signal to the controller  100 . When the film contracts to a second reference position, the sensor transmits a lower limit signal to the controller  100 . Upon receiving the upper limit signal or the lower limit signal, the controller  100  rotates the feed pump in a forward direction or a reverse direction so as to start or stop feeding ink. The pressure detector of each damper may naturally be any detector other than the sensor described above. 
     As illustrated in  FIG. 1 , the printer  1  includes the cap unit  40 . The cap unit  40  protects the ink heads  32  from drying of ink and adhesion of foreign matter when the printer  1  effects no printing. The cap unit  40  also performs suction cleaning for the ink heads  32 . The cap unit  40  is disposed in a side cover  15  located rightward of the platen  6 . The cap unit  40  is disposed below the ink head unit  30 .  FIG. 3  is a schematic diagram illustrating ink discharge paths of the cap unit  40 . As illustrated in  FIGS. 2 and 3 , the cap unit  40  includes a movable table  41 , caps  42 , passages  44 , cap valves  45 , the suction pumps  46 , a waste liquid bottle  49 , and the conveyor  50 . 
     As illustrated in  FIG. 4 , the number of caps  42  included in the cap unit  40  is eight in total, for example. In other words, the number of caps  42  is equal to the number of ink heads  32 . The caps  42  are basically identical in configuration. A set of the passage  44 , the cap valve  45 , and the suction pump  46  is provided between each of the caps  42  and the waste liquid bottle  49 . The arrangements of components between the waste liquid bottle  49  and the caps  42  are substantially the same. Thus, for the sake of simplification of description, the components provided between the waste liquid bottle  49  and the caps  42  and having the same functions are identified by the same reference signs. 
     Each cap  42  is detachably attachable to the associated ink head  32  so as to cover the nozzle surface of the associated ink head  32 . As used herein, the phrase “to cover the nozzle surface” refers to not only covering an entirety of the nozzle surface but also covering at least the nozzle rows of the nozzle surface. The caps  42  are disposed in the movable table  41 . The caps  42  are each fitted into an associated one of openings  41   a  provided in the movable table  41 . The movable table  41  is made of a single steel plate. The openings  41   a  are provided by punching. The openings  41   a  of the movable table  41  are provided at predetermined locations such that the arrangement of the caps  42  corresponds to the arrangement of the ink heads  32  disposed in the head plate  36 . Specifically, four of the eight caps  42  are arranged at equal or substantially equal intervals in the main scanning direction Y and disposed in a relatively forward portion of the movable table  41 . The other four of the eight caps  42  are arranged at equal or substantially equal intervals in the main scanning direction Y and disposed in a relatively rearward portion of the movable table  41 . Each of the relatively forwardly disposed caps  42  pairs up with an adjacent one of the relatively rearwardly disposed caps  42 . An end of the movable table  41  facing in the first direction Y 1  includes a table wall  41   b . The table wall  41   b  is provided by sheet metal processing. In one example, the table wall  41   b  is provided by bending, in the upward direction U, the right end of the steel plate that defines the movable table  41 . An end of the movable table  41  facing in the first direction Y 1  and located on the rear side Rr includes a movement stopper  41   c . The movement stopper  41   c  comes into engagement with the engagement portion  31 A (see  FIG. 2 ) of the carriage  31  that moves in the main scanning direction Y. The lower end of the movement stopper  41   c  is secured to the upper surface of the steel plate that defines the movable table  41 . A lateral surface of the movable table  41  on the front side F is provided with a guide pin  48   a  located on the right side R and a guide pin  48   b  located on the left side L. A lateral surface of the movable table  41  on the rear side Rr is provided with a guide pin  48   c  located on the right side R and a guide pin  48   d  located on the left side L. With the guide pins  48   a ,  48   b ,  48   c , and  48   d , the movable table  41  is supported by the conveyor  50 . 
     As illustrated in  FIG. 5 , each cap  42  includes a body case  43   a , a lip  43   d , and an absorber  43   h . Each cap  42  is detachably attachable to the associated ink head  32  so as to cover the nozzle surface of the associated ink head  32 . Attaching each cap  42  to the associated ink head  32  defines an enclosed space S between each cap  42  and the nozzle surface of the associated ink head  32 . 
     The body case  43   a  includes a bottom and a side wall. The body case  43   a  has a box shape having an upwardly facing opening. The side wall of the body case  43   a  has a shape conforming to the nozzle surface of the associated ink head  32 . In one example, the side wall of the body case  43   a  has an oval shape in the plan view. The side wall of the body case  43   a  is structured such that the nozzle surface of the associated ink head  32  is fitted into the body case  43   a . The bottom of the body case  43   a  is provided with a protrusive hole  43   b  protruding upward, and a through hole  43   c . The lower ends of the protrusive hole  43   b  and the through hole  43   c  are each provided with a protrusion protruded in the downward direction D from the bottom of the body case  43   a  such that the protrusive hole  43   b  and the through hole  43   c  are connectable to the associated passage  44 . The lower ends of the protrusive hole  43   b  and the through hole  43   c  are protruded in the downward direction D from the movable table  41 . The protrusive hole  43   b  is connected with an associated one of opening passages  44   a  (which will be described below). The upper end of the protrusive hole  43   b  is located at the same height as the upper surface of the absorber  43   h  or above the upper surface of the absorber  43   h . The upper end of the protrusive hole  43   b  is located below the upper end of the lip  43   d . The lower end of the through hole  43   c  is connected with an associated one of suction passages  44   b  (which will be described below). The protrusive hole  43   b  defines and functions as a portion of a first passage. The through hole  43   c  defines and functions as a portion of a second passage. 
     The lip  43   d  is held in the opening of the body case  43   a . The lip  43   d  includes a bottom and a side wall. The lip  43   d  is provided with an opening facing upward. The upper end of the side wall of the lip  43   d  decreases in thickness (or width) as it extends upward. The lip  43   d  is made of an elastically deformable material. In one example, the lip  43   d  is made of rubber. The lip  43   d  is provided in the body case  43   a  such that the lip  43   d  elastically comes into contact with the nozzle surface of the associated ink head  32 . Bringing the lip  43   d  into contact with the nozzle surface of the associated ink head  32  defines the enclosed space S. The bottom of the lip  43   d  is provided with a through hole  43   g  and a through hole  43   f . The protrusive hole  43   b  passes through the through hole  43   g . The through hole  43   f  is in communication with the through hole  43   c  and the suction passage  44   b . The upper surface of the bottom of the lip  43   d  is provided with a groove  43   e  recessed in the downward direction D. The groove  43   e  is in communication with the through hole  43   f . The groove  43   e  extends across the entire or substantially the entire surface of the bottom of the lip  43   d.    
     The absorber  43   h  is held in the opening of the lip  43   d . The absorber  43   h  is made of an air-permeable porous material capable of absorbing ink. Examples of the porous material include a sponge, a woven fabric, and a nonwoven fabric. The absorber  43   h  includes a through hole  43   i . The protrusive hole  43   b  passes through the through hole  43   i . The upper surface of the absorber  43   h  is located below the upper end of the lip  43   d . The upper surface of the absorber  43   h  is located at the same height as the upper end of the protrusive hole  43   b  or below the upper end of the protrusive hole  43   b.    
     As illustrated in  FIG. 3 , each passage  44  includes the opening passage  44   a  and the suction passage  44   b . As previously mentioned, the upstream end of each opening passage  44   a  is connected to the protrusive hole  43   b  of the associated cap  42 , and the upstream end of each suction passage  44   b  is connected to the through hole  43   c  of the associated cap  42 . The downstream end of each suction passage  44   b  is inserted into the waste liquid bottle  49 . Each suction passage  44   b  connects an associated one of the caps  42  to an associated one of the suction pumps  46  (which will be described below). Each passage  44  is made of a flexible tube (e.g., a silicon tube). 
     Each cap valve  45  is provided at a location somewhere along the associated opening passage  44   a  or on an end of the associated opening passage  44   a . Each cap valve  45  performs switching between an open state where the inside of the associated opening passage  44   a  is in communication with the outside of the associated opening passage  44   a  and a closed state where the inside of the associated opening passage  44   a  is out of communication with the outside of the associated opening passage  44   a . Each cap valve  45  is not limited to any particular configuration or operating mechanism. Each cap valve  45  may be a “control valve” that switches between the open state and the closed state using at least one of water (i.e., vapor), air, electricity, magnetism, and hydraulic pressure to be supplied separately. Each cap valve  45  may be a valve that switches between the open state and the closed state by a mechanical operation. Each cap valve  45  according to the present preferred embodiment is, for example, a piston valve openable and closable by a small actuating force. The cap unit  40  includes a plurality of composite cap valves  47 . Each of the composite cap valves  47  includes two of the cap valves  45  integral with each other. One of the two cap valves  45  included in each composite cap valve  47  may hereinafter be referred to as a “first cap valve  45 ”. The other one of the two cap valves  45  included in each composite cap valve  47  may hereinafter be referred to as a “second cap valve  45 ”. The number of composite cap valves  47  included in the cap unit  40  is four, for example. 
       FIG. 6  is a front view of the composite cap valve  47 .  FIGS. 7A and 7B  are cross-sectional views of the composite cap valve  47 . Each composite cap valve  47  includes a composite valve case  47   a . Components of two cap valves  45  are held in the composite valve case  47   a  of each composite cap valve  47 . Each composite cap valve  47  includes the composite valve case  47   a , a piston valve element  45   f  (which may hereinafter be referred to as a “first piston valve element  45   f ”), a piston valve element  47   f  (which may hereinafter be referred to as a “second piston valve element  47   f ”), a spring  45   j , and a spring  47   j . The composite valve case  47   a  includes an inlet  45   c  (which may hereinafter be referred to as a “first inlet  45   c ”), an inlet  47   c  (which may hereinafter be referred to as a “second inlet  47   c ”), an outlet  45   d , an outlet  47   d , an opening  45   e , and an opening  47   e . The composite valve case  47   a  internally includes: an inner passage  45   b  through which the inlet  45   c  and the outlet  45   d  are in communication with each other; and an inner passage  47   b  through which the inlet  47   c  and the outlet  47   d  are in communication with each other. The inner passage  45   b  may hereinafter be referred to as a “first inner passage  45   b ”. The inner passage  47   b  may hereinafter be referred to as a “second inner passage  47   b ”. The inlets  45   c  and  47   c  are each protruded in the downward direction D from the lower surface of the composite valve case  47   a . The outlets  45   d  and  47   d  are each protruded rearward from the back surface of the composite valve case  47   a . The openings  45   e  and  47   e  are disposed in the front face of the composite valve case  47   a . The openings  45   e  and  47   e  are each elongated in the up-down direction Z. 
     A large portion of each of the piston valve elements  45   f  and  47   f  is held in the composite valve case  47   a . The piston valve elements  45   f  and  47   f  are movable in the up-down direction Z inside the composite valve case  47   a . When the piston valve elements  45   f  and  47   f  are located at closing positions (i.e., lowermost positions), the piston valve elements  45   f  and  47   f  respectively close the inner passages  45   b  and  47   b  (see  FIG. 7B ). With the piston valve elements  45   f  and  47   f  located at the closing positions, the lower ends of the piston valve elements  45   f  and  47   f  respectively intersect and block at least portions of the inner passages  45   b  and  47   b . The lower end of the piston valve element  45   f  is provided with a gasket  45   g  to tightly seal the inner passage  45   b , with the piston valve element  45   f  located at the closing position. The lower end of the piston valve element  47   f  is provided with a gasket  47   g  to tightly seal the inner passage  47   b , with the piston valve element  47   f  located at the closing position. When the piston valve elements  45   f  and  47   f  are located on the upper side U relative to the closing positions, the piston valve elements  45   f  and  47   f  respectively open the inner passages  45   b  and  47   b  (see  FIG. 7A ). With the piston valve elements  45   f  and  47   f  located on the upper side U relative to the closing positions, the upper ends of the piston valve elements  45   f  and  47   f  protrude out of the composite valve case  47   a . The springs  45   j  and  47   j  are held in the composite valve case  47   a . Each of the springs  45   j  and  47   j  is a compression coil spring including one end secured to an inner wall of the composite valve case  47   a . The piston valve elements  45   f  and  47   f  are respectively disposed inside the coils of the springs  45   j  and  47   j . The piston valve element  45   f  is urged by gravity and the spring  45   j  such that the piston valve element  45   f  is located at the closing position under normal conditions. The piston valve element  47   f  is urged by gravity and the spring  47   j  such that the piston valve element  47   f  is located at the closing position under normal conditions. The spring  45   j  urges the piston valve element  45   f  to the closing position and guides movement of the piston valve element  45   f  in the up-down direction Z. The spring  47   j  urges the piston valve element  47   f  to the closing position and guides movement of the piston valve element  47   f  in the up-down direction Z. 
     The piston valve element  45   f  includes a rod  45   h  (which may hereinafter be referred to as a “first rod  45   h ”) protruding in the main scanning direction Y. The piston valve element  47   f  includes a rod  47   h  (which may hereinafter be referred to as a “second rod  47   h ”) protruding in the main scanning direction Y. A first end of the rod  45   h  is secured to the piston valve element  45   f . A first end of the rod  47   h  is secured to the piston valve element  47   f . The rod  45   h  is secured to the lower portion of the piston valve element  45   f . The rod  47   h  is secured to the lower portion of the piston valve element  47   f . A second end of the rod  45   h  extends out of the composite valve case  47   a  through the opening  45   e . A second end of the rod  47   h  extends out of the composite valve case  47   a  through the opening  47   e . The second end of the rod  45   h  includes an inclined surface  45   i  extending obliquely upward to the right such that the second end of the rod  45   h  tapers to its upper tip. The second end of the rod  47   h  includes an inclined surface  47   i  extending obliquely upward to the right such that the second end of the rod  47   h  tapers to its upper tip. At normal times, the piston valve element  45   f  is urged to the closing position by the spring  45   j , so that the rod  45   h  of the piston valve element  45   f  passes through a lower region of the opening  45   e . At normal times, the piston valve element  47   f  is urged to the closing position by the spring  47   j , so that the rod  47   h  of the piston valve element  47   f  passes through a lower region of the opening  47   e . Lifting the rod  45   h  in the upward direction U moves the rod  45   h  in the upward direction U through the opening  45   e . Lifting the rod  47   h  in the upward direction U moves the rod  47   h  in the upward direction U through the opening  47   e . In accordance with the movement of the rod  45   h  in the upward direction U, the piston valve element  45   f  moves in the upward direction U against the elastic force of the spring  45   j . In accordance with the movement of the rod  47   h  in the upward direction U, the piston valve element  47   f  moves in the upward direction U against the elastic force of the spring  47   j . The movement of the piston valve elements  45   f  and  47   f  in the upward direction U opens the composite cap valve  47 . The rods  45   h  and  47   h  are liftable independently or in conjunction with each other. Thus, the two cap valves  45  of each composite cap valve  47  are openable and closable independently or in conjunction with each other. 
     The composite valve case  47   a  may be divided into: a first cap valve area A including the inner passage  45   b , the piston valve element  45   f , the rod  45   h , and the spring  45   j ; and a second cap valve area B including the inner passage  47   b , the piston valve element  47   f , the rod  47   h , and the spring  47   j . The first cap valve area A defines and functions as one of the two cap valves  45  of the composite cap valve  47 . The second cap valve area B defines and functions as the other one of the two cap valves  45  of the composite cap valve  47 . The composite valve case  47   a  includes a through hole  47   k  between the first cap valve area A and the second cap valve area B. The through hole  47   k  passes through the composite valve case  47   a  in the up-down direction Z. 
     As illustrated in  FIG. 4 , the four composite cap valves  47  are disposed on the right surface of the table wall  41   b  (i.e., a surface of the table wall  41   b  facing in the first direction Y 1 ). Each cap valve  45  is disposed such that the front of each cap valve  45  faces in the first direction Y 1 . The rods  45   h  and  47   h  are disposed such that the rods  45   h  and  47   h  protrude in the first direction Y 1  of the main scanning direction Y. The table wall  41   b  is provided with through holes at locations where the cap valves  45  are to be attached to the table wall  41   b . The outlets  45   d  and  47   d  of the cap valves  45  are inserted into the through holes of the table wall  41   b  (see  FIGS. 9A to 9C ). As illustrated in  FIG. 8 , two of the four composite cap valves  47  are disposed on a relatively upper portion of the table wall  41   b  and in alignment with each other in the front-rear direction X. The other two of the four composite cap valves  47  are disposed on a relatively lower portion of the table wall  41   b  and in alignment with each other in the front-rear direction X. The two composite cap valves  47  on the upper side U are deviated from the other two composite cap valves  47  on the lower side D in the front-rear direction X by one-half of the dimension of the first cap valve area A or the second cap valve area B in the front-rear direction X. Thus, the inlets  45   c  and  47   c  of the two composite cap valves  47  on the upper side U are inserted into the through holes  47   k  of the two composite cap valves  47  on the lower side D. Although not illustrated in detail, the opening passages  44   a  connected to the inlets  45   c  and  47   c  of the two composite cap valves  47  on the upper side U are also inserted into the through holes  47   k  of the two composite cap valves  47  on the lower side D. The dimension of each of the inlets  45   c  and  47   c  in the plan view (e.g., the outer diameter of each of the inlets  45   c  and  47   c ) is smaller than the dimension of each through hole  47   k  in the plan view (e.g., the inner diameter of each through hole  47   k ). The dimension of each through hole  47   k  in the plan view is larger than the dimension of each of the inlets  45   c  and  47   c  in the plan view. Thus, the four composite cap valves  47  are arranged in a “hound&#39;s tooth pattern”. As used herein, the term “hound&#39;s tooth pattern” refers to a pattern in which the composite cap valves  47  are disposed in a staggered configuration. Accordingly, the term “hound&#39;s tooth pattern” may refer to a gingham check pattern, a zigzag arrangement, a staggered arrangement, and other similar arrangements and patterns. 
     Each opening passage  44   a  connected to the associated cap  42  extends in the rightward direction R (i.e., the first direction Y 1 ) from a location below the movable table  41 . The opening passages  44   a  extending from an associated pair of the caps are connected to the inlets  45   c  and  47   c  of the associated composite cap valve  47 . As illustrated in  FIGS. 7A and 7B , the inlets  45   c  and  47   c  disposed on the lower ends of the cap valves  45  define and function as downstream connections connected to the associated opening passages  44   a . The inlets  45   c  and  47   c  of each composite cap valve  47  are connected, through the associated opening passages  44   a , for example, to an associated pair of the caps  42  adjacent to each other. 
     Each suction pump  46  includes an inlet on the upstream side, and an outlet on the downstream side. Each suction pump  46  sucks, through the inlet, a fluid (e.g., gas such as air or liquid such as ink) in a portion of the associated suction passage  44   b  connected to the upstream inlet of the suction pump  46 , and sends the fluid to the outlet. This reduces the pressure inside the portion of the associated suction passage  44   b  connected to the upstream inlet of the suction pump  46 . Thus, with each cap  42  attached to the associated ink head  32 , driving each suction pump  46  reduces the pressure inside the associated enclosed space S and sucks the fluid inside the associated enclosed space S. Each suction pump  46  sends the sucked fluid to a downstream portion of the associated suction passage  44   b . Each suction pump  46  is not limited to any particular configuration. In one example, each suction pump  46  is a cylinder type suction pump. Each suction pump  46  is an example of a suction device. The waste liquid bottle  49  is a container to contain liquid (such as ink) discharged to the downstream side from each suction pump  46 . The waste liquid bottle  49  may be attachable to and detachable from the lower portion of the side cover  15 , for example. 
     As illustrated in  FIG. 2 , the conveyor  50  moves the movable table  41 . The conveyor  50  includes a base  51 , a right side wall  52 , a guide wall  53 , and a spring  55 . 
     The base  51  defines and functions as a base for an entirety of the conveyor  50 . The right side wall  52  stands vertically or substantially vertically in the up-down direction Z on an end of the base  51  facing in the first direction Y 1 . The upper end of the right side wall  52  includes lifters  52 A each extending obliquely downward to the left. In other words, each lifter  52 A includes an inclined surface extending obliquely upward to the right. Each lifter  52 A is a member to lift the rod  45   h  or  47   h  of the associated cap valve  45 . Each lifter  52 A is provided by sheet metal processing. In one example, each lifter  52 A is provided by bending the upper end of the right side wall  52 . 
     In the present preferred embodiment, each lifter  52 A is disposed on a portion of the right side wall  52  that faces the rod  45   h  or  47   h  in the second direction Y 2 . Because the four composite cap valves  47  are disposed in a hound&#39;s tooth pattern, the rods  45   h  and  47   h  are also disposed in a hound&#39;s tooth pattern. Thus, the lifters  52 A according to the present preferred embodiment are also disposed in a hound&#39;s tooth pattern. Specifically, the right side wall  52  includes a first right side wall  52   d  and a second right side wall  52   u . With the composite cap valves  47  in the closed state, the first right side wall  52   d  is located below the rods  45   h  and  47   h  of the two composite cap valves  47  disposed on the relatively lower portion of the table wall  41   b . With the composite cap valves  47  in the closed state, the second right side wall  52   u  is located above the rods  45   h  and  47   h  of the two composite cap valves  47  disposed on the relatively lower portion of the table wall  41   b.    
     The first right side wall  52   d  is made of a sheet of steel connected to the base  51 . The lifters  52 A include first lifters  52 A 1 . The first lifters  52 A 1  are provided on the upper end of the first right side wall  52   d  by sheet metal processing. Specifically, the first lifters  52 A 1  are provided by bending the upper end of the first right side wall  52   d  such that the first lifters  52 A 1  extend toward the composite cap valves  47  (i.e., substantially in the second direction Y 2 ). Each first lifter  52 A 1  is provided on a portion of the first right side wall  52   d  that faces the rod  45   h  or  47   h , but no lifter  52 A 1  is provided on a portion of the first right side wall  52   d  that does not face the rod  45   h  or  47   h . Whether a portion of the first right side wall  52   d  faces the rod  45   h  or  47   h  does not necessarily have to be determined based on whether the portion of the first right side wall  52   d  faces the rod  45   h  or  47   h  in the main scanning direction Y in a strict sense. For example, suppose that distances are measured between each rod  45   h  or  47   h  and points on an imaginary line extending in the front-rear direction X on the first right side wall  52   d  (which may be the second side wall  52   u ) at a height at which the first right side wall  52   d  faces the rods  45   h  and  47   h . In this case, the present preferred embodiment involves defining, in accordance with the distances measured, first points Q 1  each located closest to the associated rod  45   h  or  47   h  and second points Q 2  each located farthest away from the associated rod  45   h  or  47   h . An intermediate point Qm is located between each first point Q 1  and the associated second point Q 2 , for example in the center. Thus, a portion of the first right side wall  52   d  located closer to the first point Q 1  relative to the intermediate point Qm may be determined as a “portion of the first right side wall  52   d  that faces the rod  45   h  or  47   h ”, and a portion of the first right side wall  52   d  located closer to the second point Q 2  relative to the intermediate point Qm may be determined as a “portion of the first right side wall  52   d  that does not face the rod  45   h  or  47   h ”. Accordingly, the first right side wall  52   d  has a saw-toothed shape having projections and recesses arranged alternately in the plan view, with the first lifters  52 A 1  defining the projections. 
     The second right side wall  52   u  made of a sheet of steel is connected to the upper portion of the first right side wall  52   d . A portion of the first right side wall  52   d  and a portion of the second right side wall  52   u  are flush or substantially flush with each other in the up-down direction Z. The lifters  52 A include second lifters  52 A 2 . The second lifters  52 A 2  are provided on the upper end of the second right side wall  52   u  by sheet metal processing. Specifically, the second lifters  52 A 2  are provided by bending the upper end of the second right side wall  52   u  such that the second lifters  52 A 2  extend toward the composite cap valves  47  (i.e., substantially in the second direction Y 2 ). Each second lifter  52 A 2  is provided on a portion of the second right side wall  52   u  that faces the rod  45   h  or  47   h , but no second lifter  52 A 2  is provided on a portion of the second right side wall  52   u  that does not face the rod  45   h  or  47   h . A portion of the second right side wall  52   u  that faces the rod  45   h  or  47   h  and a portion of the second right side wall  52   u  that does not face the rod  45   h  or  47   h  may be determined in a manner similar to that used for the first right side wall  52   d . Accordingly, the second right side wall  52   u  has a saw-toothed shape having projections and recesses arranged alternately in the plan view, with the second lifters  52 A 2  defining the projections. 
     As previously described, the rods  45   h  and  47   h  are arranged in a hound&#39;s tooth pattern. Thus, the first and second lifters  52 A 1  and  52 A 2  are also arranged in a hound&#39;s tooth pattern. In one example, the first and second lifters  52 A 1  and  52 A 2  are arranged such that each first lifter  52 A 1  is located between the second lifters  52 A 2  in the plan view. In the plan view, the rods  45   h  and  47   h  of the two composite cap valves  47  disposed on the relatively lower portion of the table wall  41   b  are each located between the second lifters  52 A 2  protruding from the right side wall  52 . 
     The guide wall  53  stands vertically or substantially vertically on the base  51  and extends in the main scanning direction Y. The guide wall  53  includes: a guide wall  53   a  disposed on the front portion of the base  51 ; a guide wall  53   b  disposed on the front portion of the base  51 ; a guide wall  53   c  disposed on the rear portion of the base  51 ; and a guide wall  53   d  disposed on the rear portion of the base  51 . The guide walls  53   a  and  53   c  face each other in the front-rear direction X on the base  51 . The guide walls  53   b  and  53   d  face each other in the front-rear direction X on the base  51 . The four guide walls  53   a ,  53   b ,  53   c , and  53   d  are identical or substantially identical in shape. The four guide walls  53   a ,  53   b ,  53   c , and  53   d  are provided with guide holes  54 . As illustrated in  FIGS. 9A to 9C , each guide hole  54  is an elongated hole that extends obliquely upward from a lower left position P 1  to an upper right position P 2  and then extends in the rightward direction R from the position P 2  to a position P 3 . The position P 1  is located at a height H 1 . The positions P 2  and P 3  are each located at a height H 2 . The height H 2  is higher than the height H 1  by a distance Δh. The positions P 1  and P 2  have a distance Δr 1  therebetween in the right-left direction Y. The positions P 2  and P 3  have a distance Δr 2  therebetween in the right-left direction Y. The guide pins  48   a ,  48   b ,  48   c , and  48   d  of the movable table  41  of the cap unit  40  are respectively inserted into the guide holes  54  of the guide walls  53   a ,  53   b ,  53   c , and  53   d . Thus, the movable table  41  is supported by the guide wall  53 . The guide holes  54  define a path along which the movable table  41  is movable. 
     The spring  55  is connected to the upper surface of the base  51  and the lower surface of the movable table  41 . The connection between the spring  55  and the movable table  41  is located obliquely above and rightward of the connection between the spring  55  and the base  51 . In one example, a helical tension spring is usable as the spring  55 . The spring  55  is connected, under predetermined tension, to the base  51  and the movable table  41 . The spring  55  urges the movable table  41  downward to the left at all times. 
     The conveyor  50  moves the movable table  41  in conjunction with movement of the ink head unit  30 . In other words, the conveyor  50  moves the cap unit  40  in conjunction with movement of the ink heads  32 . The conveyor  50  is an example of a cap conveyor to move the cap unit  40  between a cap attaching position and a retracted position. 
     As illustrated in  FIG. 9A , the movable table  41  is supported by the conveyor  50  such that the guide pins  48   a ,  48   b ,  48   c , and  48   d  are each located at the position P 1  at normal times owing to the tension of the spring  55 . In this state, the cap unit  40  is located at the “retracted position”. In one example, the cap unit  40  is located at the retracted position during printing effected by the printer  1 . With the cap unit  40  located at the retracted position, the upper ends of the caps  42  are located below the lower ends of the ink heads  32 , and the left lateral surface of the movement stopper  41   c  of the movable table  41  is located at a first location R 1 . 
     Once the printer  1  has stopped printing, the ink head unit  30  is held in the side cover  15 . After printing, the ink head unit  30  placed on the carriage  31  is moved along the guide rail  10  to the “cap attaching position” defined in the side cover  15 . In the course of this movement, the engagement portion  31 A (see  FIG. 2 ) of the carriage  31  abuts against the movement stopper  41   c  of the movable table  41  at the retracted position so as to press the movement stopper  41   c  rightward. This moves the movable table  41  in the first direction Y 1  (i.e., the rightward direction R) against the tension of the spring  55 . As illustrated in  FIG. 9B , the engagement portion  31 A of the carriage  31  moves the movement stopper  41   c  of the movable table  41  in the first direction Y 1  by the distance Δr 1 . As a result of this movement, the left lateral surface of the movement stopper  41   c  of the movable table  41  is located at a second location R 2 . The movement of the movable table  41  in the first direction Y 1  is restricted by the guide holes  54 . The movement of the movable table  41  in the first direction Y 1  by the distance Δr 1  causes each of the guide pins  48   a ,  48   b ,  48   c , and  48   d  to move from the position P 1  and the position P 2 . In accordance with the movement of the movable table in the first direction Y 1  by the distance Δr 1 , the movable table  41  moves in the upward direction U by the distance Δh. The movement of the movable table  41  just described causes the caps  42  secured to the movable table  41  to be attached to the ink heads  32 . In other words, moving the carriage  31  to the “cap attaching position” causes the cap unit  40  to attach the caps  42  to the ink heads  32 . 
     As illustrated in  FIG. 9C , the carriage  31  is allowed to move to a “valve opening position” located in the first direction Y 1  relative to the “cap attaching position”. The “valve opening position” is located in the first direction Y 1  relative to the “cap attaching position” by the distance Δr 2 . During movement of the carriage  31  from the “cap attaching position” to the “valve opening position”, the engagement portion  31 A of the carriage  31  presses the movement stopper  41   c  of the movable table  41  at the cap attaching position further rightward. This moves the movable table  41  in the first direction Y 1  by the distance Δr 2  against the tension of the spring  55 . The guide pins  48   a ,  48   b ,  48   c , and  48   d  each move from the position P 2  to the position P 3 . Because the position P 2  and the position P 3  are located at the same height, the ink heads  32  and the caps  42  move in the first direction Y 1 , with each cap  42  kept attached to the associated ink head  32 . As a result of the movement of the carriage  31  to the “valve opening position”, the left lateral surface of the movement stopper  41   c  of the movable table  41  is located at a third location R 3 . The movement of the carriage  31  to the “valve opening position” just described first causes the rods  45   h  and  47   h  of the composite cap valves  47 , disposed on the right surface of the table wall  41   b  of the movable table  41 , to abut against the lifters  52 A of the right side wall  52  of the conveyor  50 . More specifically, the rods  45   h  and  47   h  of the two composite cap valves  47 , disposed on the relatively lower portion of the table wall  41   b , abut against the first lifters  52 A 1 , and the rods  45   h  and  47   h  of the two composite cap valves  47 , disposed on the relatively upper portion of the table wall  41   b , abut against the second lifters  52 A 2 . An end of each of the rods  45   h  and  47   h  facing in the first direction Y 1  includes an oblique surface extending obliquely upward to the right. An end of each of the first and second lifters  52 A 1  and  52 A 2  facing in the second direction Y 2  includes an oblique surface extending obliquely upward to the right. Thus, the rods  45   h  and  47   h  and the first and second lifters  52 A 1  and  52 A 2  define a slider through which the rods  45   h  and  47   h  abut against the first and second lifters  52 A 1  and  52 A 2  so as to convert movement of the rods  45   h  and  47   h  in the right-left direction Y into movement of the rods  45   h  and  47   h  in the up-down direction Z. Accordingly, further movement of the movable table  41  in the first direction Y 1  causes the rods  45   h  and  47   h  to move upward along the inclined surfaces of the first and second lifters  52 A 1  and  52 A 2 , so that the rods  45   h  and  47   h  are lifted in the upward direction U. As a result, the two cap valves  45  included in each composite cap valve  47  are switched from the closed state to the open state. In other words, the movement of the carriage  31  to the “valve opening position” enables the cap valves  45  to switch to the open state, with the caps  42  attached to the ink heads  32 . The rods  45   h  and  47   h  included in the four composite cap valves  47  simultaneously abut against the first and second lifters  52 A 1  and  52 A 2 , so that all of the rods  45   h  and  47   h  are simultaneously lifted in the upward direction U. Consequently, the eight cap valves  45  are simultaneously switched to the open state. 
     Movement of the carriage  31  in the second direction Y 2  toward a position leftward of the “valve opening position” or the “cap attaching position” causes the engagement portion  31 A of the carriage  31  to stop applying a pressing force to the movement stopper  41   c  of the movable table  41  or reduce the pressing force applied to the movement stopper  41   c . The movable table  41  is urged downward to the left by the spring  55 . Thus, the movable table  41  is moved to the “retracted position” from the “valve opening position” or the “cap attaching position”. 
     The controller  100  is configured or programmed to comprehensively control operations of the components of the printer  1 . The controller  100  is not limited to any particular configuration. In one example, the controller  100  is a microcomputer. The microcomputer is not limited to any particular hardware configuration. In one example, the microcomputer includes: an interface (I/F) to transmit and receive information, such as print data, to and from an external device, such as a host computer; a central processing unit (CPU) to execute commands included in a printing control program; a read-only memory (ROM) storing programs to be executed by the CPU; a random-access memory (RAM) to be used as a working area where the programs are to be expanded; and a memory storing various data, such as the printing control program. The controller  100  may include a rewritable programmable logic device, such as a field-programmable gate array (FPGA). In one example, the FPGA may include a CPU core provided by an integrated circuit, a multiplier, a RAM, and related peripheral circuitry. 
       FIG. 10  is a block diagram of the controller  100 . The controller  100  according to the present preferred embodiment is configured or programmed to include a first controller  101 , a second controller  102 , a third controller  103 , a fourth controller  104 , a fifth controller  105 , and a printing controller  106 . The first to fifth controllers  101  to  105  control suction cleaning for the ink heads  32 , which is to be performed by the cap unit  40 . The first to fifth controllers  101  to  105  cause the printer  1  to perform suction cleaning for the ink heads  32  by following the procedure illustrated in  FIG. 11 , for example. The printing controller  106  controls basic printing operations to be performed by the printer  1 . The functions of each of the controllers of the controller  100  may be implemented by hardware (e.g., a circuit and/or a microprocessor) or may be implemented by executing a computer program by the CPU. 
     The printing controller  106  is electrically connected to the ink heads  32 , the feed motor, and the scan motor. In accordance with the printing control program and the print data stored in the memory, the printing controller  106  causes the scan motor to move the carriage  31  in the main scanning direction Y at a predetermined speed. The printing controller  106  then causes the ink heads  32  mounted on the carriage  31  to discharge ink from predetermined positions based on the print data. This operation and movement of the recording medium  8  in the sub-scanning direction X caused by the feed motor are repeatedly carried out in an alternating manner. Thus, the printer  1  effects printing in accordance with the print data. 
     The first controller  101  performs capping (S 1  in  FIG. 11 ). The first controller  101  is electrically connected to the scan motor to move the ink heads  32 . Suction cleaning for the ink heads  32 , which is to be performed by the printer  1 , first involves actuating the scan motor by the first controller  101  so as to move the carriage  31  to the cap attaching position. Thus, the carriage  31  causes the cap unit  40  located at a standby position to move to the cap attaching position. As a result, the caps  42  are attached to the ink heads  32 . The enclosed space S is defined between each cap  42  and the associated ink head  32 . 
     The second controller  102  performs main suction (S 2  in  FIG. 11 ). The second controller  102  is electrically connected to the suction pumps  46 . After the caps  42  are attached to the ink heads  32  by the first controller  101 , the second controller  102  drives the suction pumps  46 . This reduces the pressure inside each enclosed space S. In one example, the second controller  102  reduces the pressure inside each enclosed space S such that the pressure inside each enclosed space S is in the range of about −20 kPa to about −35 kPa. The second controller  102  may reduce the pressure inside each enclosed space S to about −30 kPa, for example. In one example, the second controller  102  drives the suction pumps  46  at a flow velocity between about 3 cc/sec and about 10 cc/sec inclusive. The second controller  102  may drive the suction pumps  46  at a flow velocity of about 7.3 cc/sec, for example. The flow velocity may vary depending on the capacity of each cap  42 . In one example, the time required for such pressure reduction is about 10 seconds to about 20 seconds. The time required for such pressure reduction may be about 13.7 seconds, for example. Thus, ink remaining in the nozzles of the ink heads  32  is dischargeable to the caps  42  and the passages  44 . The ink discharged to the caps  42  and the passages  44  from the ink heads  32  is collectable into the waste liquid bottle  49 . 
     The third controller  103  makes a pressure equalizing adjustment (S 3  in  FIG. 11 ). The third controller  103  is electrically connected to the suction pumps  46 . The third controller  103  deactivates the suction pumps  46  activated by the second controller  102  and maintains the deactivated state of the suction pumps  46 . Deactivating the suction pumps  46  by the third controller  103  ends main suction in suction cleaning. The third controller  103  subsequently maintains the deactivated state of the suction pumps  46 , with the caps  42  attached to the ink heads  32 . In one example, the depressurized state is maintained by the third controller  103  for about 3 seconds to about 10 seconds. The depressurized state may be maintained by the third controller  103  for about 5 seconds, for example. Thus, the depressurized state of the enclosed spaces S and the nozzles of the ink heads  32  is maintained such that the pressures inside the enclosed spaces S and the nozzles of the ink heads  32  are equalized. 
     The fourth controller  104  performs idle suction (S 4  in  FIG. 11 ). The fourth controller  104  switches the composite cap valves  47  to the open state and drives the suction pumps  46 , with the caps  42  attached to the ink heads  32 . The fourth controller  104  is electrically connected to the scan motor and the suction pumps  46 . The fourth controller  104  activates the scan motor so as to move the carriage  31  to the valve opening position. Thus, the cap unit  40  and the ink head unit  30 , located at the cap attaching position, are moved to the valve opening position, with the caps  42  kept attached to the ink heads  32 . As a result, the rods  45   h  and  47   h  of the composite cap valves  47  abut against the first and second lifters  52 A 1  and  52 A 2 , so that the rods  45   h  and  47   h  are lifted in the upward direction U and the composite cap valves  47  are switched to the open state. The movement of the carriage  31  to the valve opening position simultaneously switches all of the composite cap valves  47  to the open state. Driving the suction pumps  46  by the fourth controller  104  reduces the pressure of a portion of each suction passage  44   b  upstream of the associated suction pump  46 . In one example, the fourth controller  104  causes each suction pump  46  to suck the fluid in a portion of the associated suction passage  44   b  upstream of the suction pump  46  and discharge the fluid to a portion of the suction passage  44   b  downstream of the suction pump  46  (or external atmosphere) at a transfer rate higher than that for main suction. The transfer rate may vary depending on the capacity of each cap  42 . In one example, the fourth controller  104  drives the suction pumps  46  at a flow velocity between about 40 cc/sec and about 80 cc/sec inclusive. The fourth controller  104  may drive the suction pumps  46  at a flow velocity of about 65.6 cc/sec, for example. In one example, the time required for such pressure reduction is about 1 second to about 10 seconds. The time required for such pressure reduction may be about 5 seconds, for example. The fourth controller  104  may simultaneously carry out the movement of the carriage  31  effected by the scan motor and the suction effected by the suction pumps  46  or may drive the suction pumps  46  after moving the carriage  31  to the valve opening position. Thus, ink remaining in the opening passages  44   a , the enclosed spaces S, the caps  42 , and portions of the suction passages  44   b , which are upstream of the suction pumps  46 , is discharged downstream of the suction pumps  46 . The ink discharged is collectable into the waste liquid bottle  49 . 
     The fifth controller  105  performs de-capping (S 5  in  FIG. 11 ). The fifth controller  105  deactivates the suction pumps  46 , brings the composite cap valves  47  to the closed state, and moves the cap unit  40  to the retracted position. The fifth controller  105  is electrically connected to the suction pumps  46  and the scan motor. The fifth controller  105  deactivates the suction pumps  46  so as to end idle suction in suction cleaning. The time required for idle suction is about 1 second to about 10 seconds, for example, as previously mentioned. The fifth controller  105  activates the scan motor so as to move the carriage  31  to a position leftward of the cap attaching position. The position leftward of the cap attaching position may be a home position. Thus, the rods  45   h  and  47   h  of the composite cap valves  47  move away from the first and second lifters  52 A 1  and  52 A 2  of the conveyor  50  in the leftward direction L, so that the rods  45   h  and  47   h  return to lower positions. In other words, the composite cap valves  47  are switched to the closed state. Because the movable table  41  is urged downward to the left by the spring  55 , the cap unit  40  is moved to the retracted position. This ends suction cleaning. 
     In the present preferred embodiment, the cap unit  40  includes the table wall  41   b  standing vertically or substantially vertically on the end of the movable table  41  facing in the first direction Y 1 . The composite cap valves  47  are disposed on the table wall  41   b . The number of composite cap valves  47  increases in accordance with an increase in the number of ink heads  32 . The table wall  41   b  is disposed such that the table wall  41   b  does not interfere with movement of the ink head unit  30 . The composite cap valves  47  are disposed on the table wall  41   b  such that the composite cap valves  47  are arranged not only in a horizontal or substantially horizontal direction but also in a vertical or substantially vertical direction. Accordingly, if the number of ink heads  32  is increased, disposing the composite cap valves  47  on the table wall  41   b  standing vertically or substantially vertically in the up-down direction Z would provide the cap unit  40  without excessively increasing the area where the printer  1  is to be installed. Consequently, the present preferred embodiment provides the printer  1  that is readily adaptable to an increase in the number of ink heads  32 . 
     In the present preferred embodiment, the table wall  41   b  of the movable table  41  is provided by bending a single steel plate that defines the movable table  41 . Providing the table wall  41   b  in this manner enables the table wall  41   b  to be securely disposed on the movable table  41 . Providing the table wall  41   b  in this manner reduces the number of components of the cap unit  40 . This is advantageous in terms of manufacturing the printer  1  and keeping the printer  1  in a good condition. 
     In the present preferred embodiment, the movable table  41  includes the movement stopper  41   c  protruding upward. The ink head conveyor includes: the carriage  31  supporting the ink heads  32 ; the carriage conveyor to move the carriage  31  in the main scanning direction Y; and the engagement portion  31 A disposed on the carriage  31  to come into engagement with the movement stopper  41   c . With the engagement portion  31 A in engagement with the movement stopper  41   c , the carriage conveyor moves the carriage  31  from the first location R 1  to the second location R 2  (which is located in the first direction Y 1  relative to the first location R 1 ) in the first direction Y 1 . This moves the movable table  41  from the retracted position to the cap attaching position. With the engagement portion  31 A in engagement with the movement stopper  41   c , the carriage conveyor moves the carriage  31  from the second location R 2  to the first location R 1  in the second direction Y 2 . This moves the movable table  41  from the cap attaching position to the retracted position. Thus, the carriage conveyor to move the carriage  31  in the main scanning direction Y enables movement of the movable table  41  between the retracted position and the cap attaching position. Consequently, the present preferred embodiment makes it possible to move the cap unit  40  without providing power to be used exclusively for the cap unit  40 . 
     In the present preferred embodiment, the cap unit  40  includes the composite cap valves  47  each including the first cap valve  45  and the second cap valve  45  integral with each other. Each composite cap valve  47  includes the composite valve case  47   a , the first piston valve element  45   f , the first rod  45   h , the spring  45   j , the second piston valve element  47   f , the second rod  47   h , and the spring  47   j . The composite valve case  47   a  includes the first inner passage  45   b  and the second inner passage  47   b . The first piston valve element  45   f  is held in the composite valve case  47   a  to move in the up-down direction Z so as to switch the first inner passage  45   b  between the open state and the closed state. The first rod  45   h  protrudes from the first piston valve element  45   f  in the main scanning direction Y and at least partially extends out of the composite valve case  47   a . The spring  45   j  is held in the composite valve case  47   a  and defines and functions as a first elastic member to urge the first piston valve element  45   f  upward or downward so as to close the first inner passage  45   b . The second piston valve element  47   f  is held in the composite valve case  47   a  to move in the up-down direction Z so as to switch the second inner passage  47   b  between the open state and the closed state. The second rod  47   h  protrudes from the second piston valve element  47   f  in the main scanning direction Y and at least partially extends out of the composite valve case  47   a . The spring  47   j  is held in the composite valve case  47   a  and defines and functions as a second elastic member to urge the second piston valve element  47   f  upward or downward so as to close the second inner passage  47   b . Thus, the two cap valves  45  included in each composite cap valve  47  and in communication with associated two of the caps  42  to be attached to the ink heads  32  are integral with each other. Accordingly, when the ink heads  32  are arranged in pairs in the sub-scanning direction X so as to effect printing with a print span doubled for each round of scanning, two of the opening passages  44   a  are connected to an associated one of the composite cap valves  47 , so that the opening passages  44   a  connect the associated pair of caps  42  to the associated pair of cap valves  45 . This simplifies the arrangement of the passages. Such an arrangement makes it possible to reduce the number of components. Consequently, the present preferred embodiment provides the printer  1  that is readily adaptable to an increase in the number of ink heads  32 . 
     In the present preferred embodiment, the composite valve case  47   a  includes the through hole  47   k  passing through the composite valve case  47   a  in the up-down direction Z. The through hole  47   k  is located between the first cap valve area A and the second cap valve area B. The first cap valve area A includes the first inner passage  45   b , the first piston valve element  45   f , the first rod  45   h , and the spring  45   j  (i.e., the first elastic member). The second cap valve area B includes the second inner passage  47   b , the second piston valve element  47   f , the second rod  47   h , and the spring  47   j  (i.e., the second elastic member). The composite cap valves  47  include at least first composite cap valves  47  and second composite cap valves  47 . The first composite cap valves  47  are disposed on the table wall  41   b  such that the first composite cap valves  47  are located above the second composite cap valves  47  and out of alignment with the second composite cap valves  47  in a direction perpendicular to the up-down direction Z. The opening passages  44   a  (i.e., the first passages) each connected to at least one of the first inlet  45   c  and the second inlet  47   c  of the associated first composite cap valve  47  is inserted through the through hole  47   k  of the associated second composite cap valve  47 . Thus, when the composite valve cases  47   a  are arranged on the table wall  41   b  in a vertical or substantially vertical direction, for example, the passages (or tubes) connected to the upper composite valve cases  47   a  are allowed to extend to a region below the movable table  41  through the through holes  47   k  of the lower composite valve cases  47   a . This saves space occupied by the cap unit  40 . The present preferred embodiment prevents the passages connected to the composite valve cases  47   a  from interfering with the opening and closing of the composite cap valves  47  during movement of the movable table  41  between the cap attaching position and the valve opening position. 
     In the present preferred embodiment, the base  51  of the conveyor  50  includes the right side wall  52 . The right side wall  52  is a side wall standing vertically or substantially vertically on the end of the base  51  facing in the first direction Y 1 . The right side wall  52  includes the lifters  52 A at locations where the right side wall  52  faces the first and second rods  45   h  and  47   h  of the first composite cap valve  47  and the first and second rods  45   h  and  47   h  of the second composite cap valve  47 . Each lifter  52 A defines and functions as a valve opening surface that extends between a height corresponding to the height of the rods  45   h  and  47   h  of the associated composite cap valve  47  including inner passages  45   b  and  47   b  that are respectively closable by the piston valve elements  45   f  and  47   f  and a height corresponding to the height of the rods  45   h  and  47   h  of the associated composite cap valve  47  including inner passages  45   b  and  47   b  respectively opened by the piston valve elements  45   f  and  47   f , such that the valve opening surface inclines upward as it extends in the first direction Y 1  and intersects the main scanning direction Y and the up-down direction Z. The valve opening surfaces are not located over the first rods  45   h  or the second rods  47   h . For example, suppose that the first and second composite cap valves  47  are detached, together with the movable table  41 , from the conveyor  50  for maintenance of the cap unit  40 . In such a case, the first and second rods  45   h  and  47   h  protruding from the first and second composite cap valves  47  are prevented from being caught by the valve opening surfaces. Thus, the present preferred embodiment facilitates detachment of the movable table  41  from the conveyor  50  and prevents the first and second rods  45   h  and  47   h  from being damaged during detachment of the movable table  41 . 
     Although the preferred embodiments of the present invention have been described thus far, the foregoing preferred embodiments are only illustrative and the present invention may be embodied in various other forms. 
     In the foregoing preferred embodiments, the printer  1  includes the composite cap valves  47  each including the first and second cap valves  45  that are preferably integral with each other, for example. The printer  1 , however, does not necessarily have to include the composite cap valves  47 . When the printer  1  includes no composite cap valves  47 , each of the cap valves  45  may include: a valve case (not illustrated) including the inner passage  45   b ; the piston valve element  45   f  held in the valve case and movable in the up-down direction Z so as to switch the inner passage  45   b  between the open state and the closed state; the rod  45   h  protruding from the piston valve element  45   f  in the main scanning direction Y and at least partially extending out of the valve case; and the spring  45   j  held in the valve case and defining and functioning as an elastic member to urge the piston valve element  45   f  upward or downward so as to close the inner passage  45   b . In other words, each of the cap valves  45  may be a valve to switch a single passage between the open state and the closed state. The base  51  may include the right side wall  52  that is a side wall standing vertically or substantially vertically on the end of the base  51  facing in the first direction Y 1 . The right side wall  52  includes the lifters  52 A at locations where the right side wall  52  faces the cap valves  45 . Each lifter  52 A defines and functions as a valve opening surface that extends between a height corresponding to the height of the rod  45   h  of the associated cap valve  45  including an inner passage  45   b  closable by the piston valve element  45   f  and a height corresponding to the height of the rod  45   h  of the associated cap valve  45  including an inner passage  45   b  opened by the piston valve element  45   f , such that the valve opening surface inclines upward as it extends in the first direction Y 1  and intersects the main scanning direction Y and the up-down direction Z. With the engagement portion  31 A in engagement with the movement stopper  41   c , the carriage conveyor may move the carriage  31  from the second location R 2  to the third location R 3  (which is located in the first direction Y 1  relative to the second location R 2 ) in the first direction Y 1 . This causes the rods  45   h  to abut against the valve opening surfaces and lifts the rods  45   h  along the valve opening surfaces so as to open the cap valves  45 . With the engagement portion  31 A in engagement with the movement stopper  41   c , the carriage conveyor may move the carriage  31  from the third location R 3  to the second location R 2  in the second direction Y 2 . This lowers the rods  45   h  along the valve opening surfaces so as to close the cap valves  45 . Similarly to the preferred embodiments described above, such an arrangement enables movement of the movable table  41  and opening and closing of the cap valves  45  without providing power to be used exclusively for the cap unit  40 . 
     In the foregoing preferred embodiments, the conveyor  50  moves the movable table  41  in the main scanning direction Y and the up-down direction Z. The conveyor  50 , however, may move the movable table  41  in any suitable direction(s). In one example, the conveyor  50  may move the movable table  41  only in the up-down direction Z. In another example, the conveyor  50  may move the movable table  41  in the main scanning direction Y, the up-down direction Z, and the sub-scanning direction X. 
     In the foregoing preferred embodiments, the right side wall  52  includes the first right side wall  52   d  and the second right side wall  52   u . The second right side wall  52   u  is connected to the upper portion of the first right side wall  52   d . The first lifters  52 A 1  are provided on the first right side wall  52   d  by bending the upper end of the first right side wall  52   d . The second lifters  52 A 2  are provided on the second right side wall  52   u  by bending the upper end of the second right side wall  52   u . The first and second lifters  52 A 1  and  52 A 2 , however, may be provided in any other manner. In one example, the second lifters  52 A 2  may be provided by bending the upper end of the right side wall  52  that extends to a height corresponding to the height of the rods  45   h  and  47   h  of the upper composite cap valves  47  in the closed state. In such an example, the first lifters  52 A 1  may be separate from the right side wall  52  and connected to the right side wall  52  at a height corresponding to the height of the rods  45   h  and  47   h  of the lower composite cap valves  47  in the closed state. Such an arrangement makes it possible to strengthen the right side wall  52  and provide the right side wall  52  and the lifters  52 A without increasing the number of components. 
     The printer  1  may include a cleaner (not illustrated) to wipe the nozzle surfaces of the ink heads  32  and/or clean a member used to wipe the nozzle surfaces. The cleaner may be disposed inside the side cover  15  and leftward of the cap unit  40  such that the cleaner is located side by side with the cap unit  40 . Thus, the cleaner performs additional cleaning after suction cleaning. Specifically, the cleaner wipes the nozzle surfaces of the ink heads  32  that have undergone suction cleaning. 
     In the foregoing preferred embodiments, the printer  1  includes the platen  6 , on which the recording medium  8  is to be placed, such that the recording medium  8  is conveyed in the sub-scanning direction X by the grit rollers  16 . The printer  1 , however, is not limited to such a configuration. In one example, the printer  1  may be a “flatbed printer”. The printer  1  may include a table to move the recording medium  8  in the main scanning direction Y and the sub-scanning direction X. 
     The terms and expressions used herein are for description only and are not to be interpreted in a limited sense. These terms and expressions should be recognized as not excluding any equivalents to the elements shown and described herein and as allowing any modification encompassed in the scope of the claims. The present invention may be embodied in many various forms. This disclosure should be regarded as providing preferred embodiments of the principles of the present invention. These preferred embodiments are provided with the understanding that they are not intended to limit the present invention to the preferred embodiments described in the specification and/or shown in the drawings. The present invention encompasses any of preferred embodiments including equivalent elements, modifications, deletions, combinations, improvements and/or alterations which can be recognized by a person of ordinary skill in the art based on the disclosure. The elements of each claim should be interpreted broadly based on the terms used in the claim, and should not be limited to any of the preferred embodiments described in this specification or referred to during the prosecution of the present application. 
     While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.