Patent Publication Number: US-9849679-B2

Title: Liquid jetting apparatus, power transmission apparatus, and recording apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priorities from Japanese Patent Application Nos. 2015-228417 and 2016-063322 filed on Nov. 24, 2015 and Mar. 28, 2016, the disclosures of which are incorporated herein by reference in its entirety. 
     BACKGROUND 
     Field of the Invention 
     The present invention relates to a liquid jetting apparatus, a power transmission apparatus, and a recording apparatus. 
     Description of the Related Art 
     Japanese Patent Application laid-open No. H11-138830 discloses an ink-jet printing apparatus with a power transmission apparatus that selectively transmits power from a motor to drive targets. In this power transmission apparatus, the motor is rotated normally to swing a planet gear constituting a pendulum transmission gear right, thereby causing the planet gear to engage with a cam gear. The motor is rotated reversely in a state where a cap is in a capping state to swing the planet gear left, thereby causing the planet gear to engage with a gear of a pump roll holder. 
     SUMMARY 
     In the ink-jet printing apparatus described in Japanese Patent Application laid-open No. H11-138830, in order to prevent ink in each discharge port from drying, the cap is typically brought into close contact with a printing head during a standby state in which no recording is performed. When recording is performed, the motor is rotated normally in the state where the cap is brought into close contact with the printing head to separate the cap from the printing head. The planet gear described in Japanese Patent Application laid-open No. H11-138830 is configured to selectively engage with any of the cam gear and the gear of the pump roll holder after moving depending on the rotation direction of the motor. This configuration might cause a situation in which some sort of external force is applied on the planet gear in the standby state to disengage the planet gear from the cam gear. When the motor is rotated normally to separate the cap from the printing head in the state where the planet gear is disengaged from the cam gear, movement of the cap is started from a point of time at which the planet gear reaches an engagement position with the cam gear. In that case, the time that elapses before completion of the cap movement is longer than that of a case in which the motor is rotated normally in a state where the planet gear is engaged with the cam gear. As described above, when a drive target is driven in the configuration in which a movement gear such as the planet gear is moved to switch power transmission, the movement gear such as the planet gear might be disengaged from the cam gear transmitting power to the drive target. In that case, the time to engage the cam gear with the movement gear is required. Namely, power transmission is started after the cam gear engages with the movement gear, thereby lengthening the time that elapses before the start of power transmission. 
     An object of the present teaching is to provide a liquid jetting apparatus, a power transmission apparatus, and a recording apparatus that are capable of reducing, as much as possible, the time that elapses before power transmission to a drive target is started. 
     According to a first aspect of the present teaching, there is provided a liquid jetting apparatus, including: 
     a head unit having a liquid jetting surface with nozzles; 
     a cap configured to cover the nozzles in a state of being in contact with the head unit; 
     a cap lifter configured to move the cap between a capping position in which the cap is in contact with the head unit to cover the nozzles and an uncapping position in which the cap is separated from the head unit; 
     a motor; 
     a driven device; 
     a first transmission gear connected to the cap lifter and configured to transmit power of the motor to the cap lifter; 
     a second transmission gear connected to the driven device and configured to transmit the power of the motor to the driven device; and 
     a movement gear connected to the motor and configured to be moved between a position at which the movement gear engages with the first transmission gear and a position at which the movement gear engages with the second transmission gear depending on a rotation direction of the motor, 
     wherein at least one of the first transmission gear and the movement gear is made of a synthetic resin material containing glass fiber. 
     According to a second aspect of the present teaching, there is provided a liquid jetting apparatus, including: 
     a head unit having a liquid jetting surface with nozzles; 
     a cap configured to cover the nozzles in a state of being in contact with the head unit; 
     a cap lifter configured to move the cap between a capping position in which the cap is in contact with the head unit to cover the nozzles and an uncapping position in which the cap is separated from the head unit; 
     a motor; 
     a driven device; 
     a first transmission gear configured to transmit power of the motor to the cap movement device; 
     a second transmission gear configured to transmit the power of the motor to the driven device; and 
     a movement gear connected to the motor and configured to be moved between a position at which the movement gear engages with the first transmission gear and a position at which the movement gear engages with the second transmission gear depending on a rotation direction of the motor, 
     wherein a maximum friction force between the first transmission gear and the movement gear obtained in a state where the first transmission gear is engaged with the movement gear is greater than a maximum friction force between the second transmission gear and the movement gear obtained in a state where the second transmission gear is engaged with the movement gear. 
     According to a third aspect of the present teaching, there is provided a power transmission apparatus, including: 
     a motor; 
     a first driven device and a second driven device; 
     a first transmission gear connected to the first driven device and configured to transmit power of the motor to the first driven device; 
     a second transmission gear connected to the second driven device and configured to transmit the power of the motor to the second driven device; and 
     a movement gear connected to the motor and configured to be moved between a position at which the movement gear engages with the first transmission gear and a position at which the movement gear engages with the second transmission gear depending on a rotation direction of the motor, 
     wherein a maximum friction force between the first transmission gear and the movement gear obtained in a state where the first transmission gear is engaged with the movement gear is greater than a maximum friction force between the second transmission gear and the movement gear obtained in a state where the second transmission gear is engaged with the movement gear. 
     According to the first to third aspects, engagement between the first transmission gear and the movement gear is not released easier than engagement between the second transmission gear and the movement gear. Thus, it is possible to shorten the time that elapses before power transmission to the drive target is started as much as possible. 
     In the present teaching, the wording “connected to the cap movement device” includes not only the case in which the first transmission gear is directly connected to the cap movement device but also the case in which the first transmission gear is connected to the cap movement device via anther gear or the like. The wording “connected to the driven device” includes not only the case in which the second transmission gear is directly connected to the driven device but also the case in which the second transmission gear is connected to the driven device via another gear or the like. Similarly, the wording “connected to the motor” includes not only the case in which the movement gear is directly connected to the motor but also the case in which the movement gear is connected to the motor via another gear or the like. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic side view of a printer according to an embodiment of the present teaching. 
         FIG. 2  is a schematic plan view of a printing unit and a maintenance unit. 
         FIG. 3A  depicts an arrangement of a cap lifting device, a switch valve, and gears to be connected to them as viewed from the right in a scanning direction, and  FIG. 3B  is an enlarged view depicting surroundings of a groove of a slide cam of  FIG. 3A . 
         FIG. 4  is a plan view of the slide cam. 
         FIG. 5  is a cross-sectional view of the switch valve of  FIG. 3A  taken along the line V-V. 
         FIG. 6A  is a diagram corresponding to  FIG. 3A  and depicting a state in which a nozzle cap is in a capping position, and  FIG. 6B  is a diagram corresponding to  FIG. 3A  and depicting a state in which the nozzle cap is in an uncapping position. 
         FIG. 7A  is a diagram corresponding to  FIG. 3A  and depicting a state in which the nozzle cap is lowered to an intermediate position, and  FIG. 7B  is a diagram corresponding to  FIG. 3A  and depicting a state in which the nozzle cap is raised to the intermediate position. 
         FIGS. 8A to 8G  are diagrams depicting changes of a position of the slide cam and a detection state of a sensor. 
         FIG. 9  is a diagram corresponding to  FIG. 3A  and depicting a state in which the switch valve is being driven. 
         FIG. 10  is a diagram indicating a material used in a planet gear, a crank gear, and a valve drive gear, the planet gear selectively engaged with the crank gear and the valve drive gear. 
         FIG. 11  depicts an arrangement of a suction pump and gears to be connected to the suction pump as viewed from the right in the scanning direction. 
         FIGS. 12A to 12C  are diagrams each illustrating a connection relation between a PF motor and a feed roller and a PF input gear and a PF switch gear,  FIG. 12A  depicting a state in which an ASF switch gear is engaged with a feed gear,  FIG. 12B  depicting a state in which the PF switch gear fails to engage with a pump drive gear and the ASF switch gear is engaged with a selective drive gear,  FIG. 12C  depicting a state in which the PF switch gear is engaged with the pump drive gear and the ASF switch gear is engaged with the selective drive gear. 
         FIGS. 13A to 13C  are diagrams each illustrating a connection relation between an ASF motor and an ASF input gear and the ASF switch gear as well as the switching of connection by the ASF switch gear,  FIG. 13A  depicting a state corresponding to  FIG. 12A ,  FIG. 13B  depicting a state corresponding to  FIG. 12B ,  FIG. 13C  depicting a state corresponding to  FIG. 12C . 
         FIG. 14A  is an exploded perspective view of a clutch gear depicted in  FIGS. 13A to 13C , and  FIG. 14B  depicts the clutch gear depicted in  FIG. 14A  as viewed in a direction of an arrow B. 
         FIG. 15  is a block diagram depicting an electrical configuration of the printer. 
         FIG. 16A to 16F  are diagrams each depicting a communication relation between the nozzle cap and the switch valve and the suction pump,  FIG. 16A  depicting a standby state,  FIG. 16B  depicting a state in which valve cleaning is being performed,  FIG. 16C  depicting a state in which a suction purge for black ink is being performed,  FIG. 16D  depicting a state in which a suction purge for color inks is being performed,  FIG. 16E  depicting a state in which idle suction for black ink is being performed,  FIG. 16F  depicting a state in which idle suction for color inks is being performed. 
         FIG. 17  is a flowchart of printing procedure performed by the printer. 
         FIG. 18  is a flowchart of maintenance procedure. 
         FIG. 19A  is a diagram of a first modified example corresponding to  FIG. 10 ,  FIG. 19B  is a diagram of a second modified example corresponding to  FIG. 10 ,  FIG. 19C  is a diagram of a third modified example corresponding to  FIG. 10 ,  FIG. 19D  is a diagram of a fourth modified example corresponding to  FIG. 10 , and  FIG. 19E  is a diagram of a fifth modified example corresponding to  FIG. 10 . 
         FIG. 20A  depicts an exemplary relation between the content rate of glass fiber in the crank gear and the content rate of glass fiber in the planet gear in each of the second and fifth modified examples, and  FIG. 20B  depicts an exemplary relation between the content rate of glass fiber in the crank gear and the content rate of glass fiber in the valve drive gear in each of the third and fifth modified examples. 
         FIG. 21  is a schematic side view of a printer according to a sixth modified example. 
         FIG. 22  is a schematic side view of a printer according to a seventh modified example. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Preferred embodiments of the present teaching will be described below. 
     &lt;Overall Configuration of Printer&gt; 
     As depicted in  FIGS. 1 and 2 , a printer  1  of this embodiment (a “liquid jetting apparatus” of the present teaching) includes, for example, a printing unit  2 , a feed part  3 , and a maintenance unit  7 . 
     &lt;Printing Unit&gt; 
     The printing unit  2  includes, for example, a carriage  11 , an ink-jet head  12  (a “liquid jetting head” of the present teaching), conveyance rollers  13 ,  14 , and a platen  15 . The carriage  11  is movably supported in a scanning direction by two guide rails  16  extending in the scanning direction. The carriage  11 , which is connected to a carriage motor  156  (see  FIG. 15 ) via an unillustrated belt and pulley, is driven by the carriage motor  156  so as to reciprocate in the scanning direction. In the following, the right and the left in the scanning direction are defined as indicated in  FIG. 2 . 
     The ink-jet head  12 , which is carried on the carriage  11 , jets ink from nozzles  17  formed in an ink jetting surface  12   a  (a “liquid jetting surface” of the present teaching) which is a lower surface of the ink-jet head  12 . The nozzles  17 , which are disposed to align in a conveyance direction orthogonal to the scanning direction, form nozzle rows  18 . The ink-jet head  12  includes four nozzle rows  18  arranged in the scanning direction. Inks of black, yellow, cyan, and magenta are jetted from nozzles  17  of the four nozzle rows  18  respectively, in the order of the nozzle rows  18  from the right side in the scanning direction. The carriage  11  and the ink-jet head  12  correspond to a “head unit” of the present teaching. 
     The conveyance rollers  13  are disposed upstream of the carriage  11  in the conveyance direction, which is parallel to the ink jetting surface  12   a  and orthogonal to the scanning direction. The conveyance rollers  13  include a drive roller  13   a  and a driven roller  13   b  disposed on the upper side of the drive roller  13   a . As will be described later, the drive roller  13   a  is connected to a PF motor  101  (see  FIG. 12 ). Driving the PF motor  101  reversely (counterclockwise) transmits power from the PF motor  101  to the drive roller  13   a , thereby rotating the drive roller  13   a  in a clockwise direction in  FIG. 1 . This conveys a recording sheet P in the conveyance direction in a state where the sheet P is nipped by the drive roller  13   a  and the driven roller  13   b . Driving the PF motor  101  normally (clockwise) rotates the drive roller  13   a  in a counterclockwise direction in  FIG. 1 . 
     The conveyance rollers  14  are disposed downstream of the carriage  11  in the conveyance direction. The conveyance rollers  14  include a drive roller  14   a  and a driven roller  14   b  disposed on the upper side of the drive roller  14   a . The drive roller  14   a  is connected to the drive roller  13   a  via unillustrated gears. Thus, when power is transmitted from the PF motor  101  to the drive roller  13   a , drive force is transmitted also to the drive roller  14   a  to rotate the drive roller  14   a . In this situation, the drive rollers  13   a ,  14   a  have the same rotation direction. Accordingly, rotating the PF motor  101  reversely (counterclockwise) conveys the recording sheet P in the conveyance direction in a state where the recording sheet P is nipped by the drive roller  14   a  and the driven roller  14   b.    
     The platen  15  is disposed between the conveyance rollers  13 ,  14  in the conveyance direction to face the ink jetting surface  12   a . The platen  15  supports, from below, the recording sheet P conveyed by the conveyance rollers  13 ,  14 . 
     &lt;Feed Part&gt; 
     The feed part  3  is disposed below the platen  15 . The feed part  3  includes a sheet cassette  21  and a feed roller  22 . The sheet cassette  21  accommodates recording sheets P stacked vertically. As will be described later, the feed roller  22  is connectable to an ASF motor  102  via gears including a feed gear  131  (see  FIG. 12 , illustration of the gears is omitted except for the feed gear  131 ). Rotating the ASF motor  102  normally in a state where the feed roller  22  is connected to the ASF motor  102  transmits power from the ASF motor  102  to the feed roller  22  to rotate the feed roller  22  in the clockwise direction in  FIG. 1 . This rotation conveys the recording sheet P accommodated in the feed cassette  21  toward the upstream side in the conveyance direction. A supply route  10  is provided upstream of the feed cassette  21  in the conveyance direction to guide the recording sheet P fed from the downstream side in the conveyance direction to a position upstream of the conveyance rollers  13  in the conveyance direction. The recording sheet P conveyed by the feed roller  22  is conveyed upstream of the conveyance rollers  13  in the conveyance direction along the supply route  10  and then supplied to the printing unit  2 , as indicated by an arrow A 1  in  FIG. 1 . 
     &lt;Maintenance Unit&gt; 
     Subsequently, the maintenance unit  7  will be explained. As depicted in  FIGS. 2 to 11 , the maintenance unit  7  includes a wiper  59 , a nozzle cap  61 , a switch valve  62  (a “driven device” of the present teaching), a suction pump  63 , and a waste liquid tank  64 . 
     &lt;Wiper&gt; 
     The wiper  59  is disposed on the right of the platen  15 . The wiper  59  is moved up and down by a wiper lifting unit  157  (see  FIG. 15 ). The upper end of the wiper  59  is positioned above the ink jetting surface  12   a  in a state where the wiper  59  is raised by the wiper lifting unit  157 . When the carriage  11  moves in a state where the wiper  59  is raised, the wiper  59  makes contact with the ink jetting surface  12   a . Meanwhile, the upper end of the wiper  59  is positioned below the ink jetting surface  12   a  in a state where the wiper  59  is lowered by the wiper lifting unit  157 . When the carriage  11  moves in a state where the wiper  59  is lowered, the wiper  59  does not make contact with the ink jetting surface  12   a.    
     &lt;Nozzle Cap&gt; 
     The nozzle cap  61 , which is made of a rubber material, is disposed on the right of the wiper  59  in the scanning direction. The nozzle cap  61  includes two caps  61   a  and  61   b . The caps  61   a  and  61   b  are disposed adjacent to each other such that the cap  61   a  is on the right side of the cap  61   b  in the scanning direction. When the carriage  11  moves to a position where the ink jetting surface  12   a  faces the nozzle cap  61 , the rightmost nozzle row  18  overlaps with the cap  61   a  and three nozzle rows  18  on the left of the rightmost nozzle row  18  overlap with the cap  61   b . The nozzle cap  61  is movable up and down by a cap lifting device  70  as described later. When the cap lifting device  70  moves the nozzle cap  61  upward in a state where the ink jetting surface  12   a  faces the nozzle cap  61 , the nozzle cap  61  makes contact with the ink jetting surface  12   a  so that the cap  61   a  covers the rightmost nozzle row  18  and the cap  61   b  covers the three nozzle rows  18  on the left side of the rightmost nozzle row  18 . 
     &lt;Cap Lifting Device&gt; 
     The cap lifting device  70  moving the nozzle cap  61  up and down (a “cap lifter” of the present teaching) will be explained. As depicted in  FIGS. 3 to 5 , the cap lifting device  70  includes a cap holding part  71  and a slide cam  72 . 
     The cap holding part  71  includes a cap holder  67 , a support member  68 , and a spring  69 . The cap holder  67 , which supports the nozzle cap  61  from below, increases the rigidity of the nozzle cap  61 . The support member  68 , which is disposed below the cap holder  67 , supports the cap holder  67  from below. A guide member  58  is disposed to surround the support member  68 . Protruding parts  68   a  extending in an up-down direction are formed at both end surfaces of the support member  68  in the conveyance direction. The guide member  58  has guide grooves  58   a  extending in the up-down direction and engaging with the protruding parts  68   a . The support member  68  and the nozzle cap  61  supported thereby can move up and down by moving the protruding parts  68   a  of the support member  68  along the guide grooves  58   a . The guide member  58  is fixed to an unillustrated frame provided in a body of the printer  1 . 
     Protruding parts  68   b  protruding downward are provided in the vicinities of both ends of the lower surface of the support member  68  in the scanning direction. Protruding parts  68   c  extending in the scanning direction are formed at outer side surfaces of the protruding parts  68   b  in the scanning direction, respectively. The spring  69 , which is disposed between the cap holder  67  and the support member  68 , urges the cap holder  67  upward. 
     The slide cam  72  includes two parts  76  and  77 . The part  76  is disposed below the support member  68  to extend in the conveyance direction. Grooves  76   a  are formed at both ends of the part  76  in the scanning direction. The protruding parts  68   c  of the support member  68  are inserted into the grooves  76   a , thereby connecting the support member  68  and the slide cam  72 . As depicted in  FIG. 3B , each groove  76   a  includes three parallel parts  76   b ,  76   c , and  76   d  and two inclined parts  76   e ,  76   f . For easy understanding of the structure of the groove  76   a , the length of the slide cam  72  in the conveyance direction in  FIG. 3B  is longer than that of  FIG. 3A . 
     The parallel part  76   b  is disposed at an upstream end of the part  76  in the conveyance direction and extends parallel to the conveyance direction. The parallel part  76   c  is disposed below the parallel part  76   b , disposed downstream of the parallel part  76   b  in the conveyance direction, and extends parallel to the conveyance direction. The parallel part  76   d  is disposed between the parallel parts  76   b ,  76   c  in the conveyance direction and an up-down direction and extends parallel to the conveyance direction. The inclined part  76   e  is disposed between the parallel parts  76   b  and  76   d  in the conveyance direction, extends in the conveyance direction while being inclined thereto, and connects the parallel parts  76   b  and  76   d . The inclined part  76   f  is disposed between the parallel parts  76   c  and  76   d  in the conveyance direction, extends in the conveyance direction while being inclined thereto, and connects the parallel parts  76   c  and  76   d . The inclined part  76   e  has the inclined angle relative to the conveyance direction and the length in the conveyance direction that are substantially the same as those of the inclined part  76   f.    
     The part  77  is narrower than the part  76  in width and extends downstream in the conveyance direction from the center of the downstream end of the part  76  in the conveyance direction. An arm supporting part  77   a  is provided at the downstream end of the part  77  in the conveyance direction. The arm supporting part  77   a  extends in the scanning direction to support an arm  74  as described later. A gear  77   c  extending in the conveyance direction is formed in a left side surface  77   b  of the part  77  in the scanning direction. The slide cam  72  includes an oil damper  78  engaging with the gear  77   c . The oil dumper  78  prevents the slide cam  72  from sliding (moving suddenly) in the conveyance direction as will be described later. A protruding part  77   d  extending in the conveyance direction is provided at a part, of the left side surface  77   b  of the part  77  in the scanning direction, which is upstream of the gear  77   c  in the conveyance direction. A guide member is provided on the left of the part  77  in the scanning direction. A groove extending in the conveyance direction is formed on a right surface of the guide member in the scanning direction. The protruding part  77   d  is inserted into the groove of the guide member. Moving the protruding part  77   d  along the groove moves the slide cam  72  in the conveyance direction. The guide member is fixed to an unillustrated frame provided in the body of the printer  1 . 
     The slide cam  72  includes a sensor  79  detecting a position in the conveyance direction. The sensor  79  includes a light emitting element  79   a  and a light receiving element  79   b . The light emitting element  79   a  is disposed on the left of the part  77  in the scanning direction, and the light receiving element  79   b  is disposed on the right of the part  77  in the scanning direction. The light emitting element  79   a  emits light to the light receiving element  79   b . The light receiving element  79   b  receives the light emitted from the light emitting element  79   a . Further, a light blocking part  77   e , which operates in connection with the sensor  79 , is provided in the lower surface of the part  77 . Whether or not the light blocking part  77   e  blocks the light emitted from the light emitting element  79   a  is switched when the slide cam  72  moves in the conveyance direction, as described later. The sensor  79  becomes an off state, in which no signal is outputted, when the light receiving element  79   b  receives the light emitted from the light emitting element  79   a , and the sensor  79  becomes an on state, in which the signal is outputted, when the light receiving element  79   b  does not receive the light emitted from the light emitting element  79   a . The position of the slide cam  72  and the switching of the sensor  79  between the on and off states will be described later in detail. 
     The slide cam  72  is connected to the crank gear  73  (a “first transmission gear” of the present teaching) via the arm  74 . More specifically, the crank gear  73  is a gear of which axis direction is parallel to the scanning direction. An arm supporting part  73   a  extending in the scanning direction is provided at a part, of a side surface of the crank gear  73 , deviated from the center of the crank gear  73 . A first end of the arm  74  is swingably supported by the arm support part  77   a  of the slide cam  72  and a second end of the arm  74  is swingably supported by the arm support part  73   a  of the crank gear  73 . Accordingly, the slide cam  72  and the crank gear  73  are connected via the arm  74 . 
     &lt;Switch Valve&gt; 
     As depicted in  FIG. 5 , the switch valve  62  includes an accommodating member  81  and a channel member  82 . The accommodating member  81  is a cylindrical member of which lower end is closed. The accommodating member  81  includes two cap communicating ports  84   a ,  84   b , an atmosphere communicating port  84   c , and a pump communicating port  84   d . The communicating ports  84   a  to  84   d  communicating with an internal space  81   a  protrude outward in a radial direction of the accommodating member  81  in mutually different directions. The cap communicating port  84   a  communicates with the cap  61   a  via a tube  86   a . The cap communicating port  84   b  communicates with the cap  61   b  via a tube  86   b . The atmosphere communicating port  84   c  communicates with the waste liquid tank  64  via a tube  86   c . The pump communicating port  84   d  communicates with the suction pump  63  via a tube  86   d.    
     The channel member  82 , which is a cylindrical member made of a rubber material, is rotatably accommodated in the internal space  81   a  of the accommodating member  81 . The channel member  82  includes, for example, unillustrated grooves forming ink channels to make the communicating ports  84   a  to  84   d  communicate with each other. The channel member  82  is mounted on a valve cam  85 . The valve cam  85  is connected to a valve drive gear group  134  including a valve drive gear  134   a  (a “second transmission gear” of the present teaching). The valve drive gear  134   a  is a gear of which axis direction is parallel to the scanning direction. Since the structure of the switch valve  62  is the same as that of conventional ones, the more detailed explanation thereof is omitted. 
     &lt;Selective Gear Mechanism&gt; 
     In this embodiment, power can be selectively transmitted from the ASF motor  102  to any one of the cap lifting device  70  and the switch valve  62  via a selective gear mechanism  136 . More specifically, as depicted in  FIG. 3A , the selective gear mechanism  136  includes a selective drive gear  137  and a planet gear mechanism  139 . The selective drive gear  137  is a gear of which axis direction is parallel to the scanning direction. The selective drive gear  137  is engageable with an ASF switch gear  122  as described later. Power from the ASF motor  102  is transmitted to the selective drive gear  137  engaging with the ASF switch gear  122 . The planet gear mechanism  139  includes a sun gear  139   a , a planet gear  139   b , and a connection member  139   c . The sun gear  139   a  is a gear of which axis direction is parallel to the scanning direction. The sun gear  139   a  engages with the selective drive gear  137 . The planet gear  139   b  is a gear of which axis direction is parallel to the scanning direction. The planet gear  139   b  engages with the sun gear  139   a . The connection member  139   c  connects the sun gear  139   a  and the planet gear  139   b . The sun gear  139   a  and the planet gear  139   b  are rotatably supported by the connection member  139   c . In the planet gear mechanism  139 , rotation of the sun gear  139   a  makes the planet gear  139   b  rotate about its own axis and an axis of the sun gear  139   a . In this situation, the planet gear  139   b  rotates about the axis of the sungear  139   a  by being guided by the sun gear  139   a  and the connection member  139   c . Namely, in this embodiment, the sun gear  139   a  and the connection member  139   c  correspond to a “guide part” of the present teaching. 
     When the ASF motor  102  rotates normally (clockwise) in a state where the selective drive gear  137  is connected to the ASF motor  102 , power of the ASF motor  102  is transmitted to the gears  137 ,  139   a , and  139   b . This rotates the sun gear  139   a  in the counterclockwise direction in  FIGS. 6A to 7B  and rotates the planet gear  139   b  about the axis of the sun gear  139   a  in the clockwise direction in  FIGS. 6A to 7B . This moves the planet gear  139   b  upward, so that the planet gear  139   b  engages with the crank gear  73  from below. The planet gear  139  engaging with the crank gear  73  is positioned below the crank gear  73 . 
     When the normal rotation of the ASF motor  102  is continued further in the state where the planet gear  139  is engaged with the crank gear  73 , power of the ASF motor  102  is transmitted to the crank gear  73  to rotate the crank gear  73  in the counterclockwise direction in  FIG. 6A . Interlocked with the rotation of the crank gear  73 , the slide cam  72  reciprocates in the conveyance direction. 
     When the slide cam  72  moves upstream in the conveyance direction, the protruding part  68   c  of the support member  68  slides on the parallel part  76   b , the inclined part  76   e , the parallel part  76   d , the inclined part  76   f , and the parallel part  76   c , of a sliding surface  76   a   1  of the groove  76   a , in that order. This lowers the cap holding part  71  and the nozzle cap  61 . When the slide cam  72  moves downstream in the conveyance direction, the protruding part  68   c  of the support member  68  slides on the parallel part  76   c , the inclined part  76   f , the parallel part  76   d , the inclined part  76   e , and the parallel part  76   b , of the sliding surface  76   a   1  of the groove  76   a , in that order. This raises the cap holding part  71  and the nozzle cap  61 . In that case, the oil damper  78  rotates while being interlocked with the movement of the slide cam  72 . Accordingly, the cap lifting device  70  converts the rotation of the crank gear  73  in one direction into the reciprocating movement of the slide cam  72  in the conveyance direction to make the protruding part  68   c  of the support member  68  slide on the sliding surface  76   a   1  of the groove  76   a  of the slide cam  72 , thereby moving the cap holding part  71  and the nozzle cap  61  up and down. 
     As depicted in  FIG. 6A , when the protruding part  68   c  is in the parallel part  76   b , the nozzle cap  61  makes contact with the ink jetting surface  12   a  to cover nozzles  17  (in the following, this position of the nozzle cap  61  is to be referred to as a “capping position”). As depicted in  FIG. 6B , when the protruding part  68   c  is in the parallel part  76   c , the nozzle cap  61  is separated from the ink jetting surface  12   a  (in the following, this position of the nozzle cap  61  is to be referred to as an “uncapping position”). As depicted in  FIGS. 7A and 7B , when the protruding part  68   c  is in the parallel part  76   d , although the nozzle cap  61  is separated from the ink jetting surface  12   a , the distance between the nozzle cap  61  and the ink jetting surface  12   a  is shorter than that of the case in which the protruding part  68   c  is in the parallel part  76   c  (in the following, this position of the nozzle cap  61  is to be referred to as an “intermediate position”). 
     Here, an explanation will be made about control of the ASF motor  102  for moving the nozzle cap  61  between the capping position and the uncapping position and the intermediate position. In this embodiment, the light blocking part  77   e  does not face the light emitting element  79   a  and the light emitting element  79   b  when the protruding part  68   c  is positioned downstream (on the side opposite to the inclined part  76   f ) of a predetermined point of the parallel part  76   c  (a point at which the protruding part  68   c  in  FIG. 8B  is positioned) in the conveyance direction as depicted in  FIG. 8A  and when the protruding part  68   c  is positioned upstream of a predetermined point of the parallel part  76   b  (a point at which the protruding part  68   c  in  FIG. 8F  is positioned) in the conveyance direction as depicted in  FIG. 8G . As depicted in  FIGS. 8B to 8F , the light blocking part  77   e  faces the light emitting element  79   a  and the light receiving element  79   b  when the protruding part  68   c  is positioned upstream (on the side of the inclined part  760  of the predetermined point of the parallel part  76   c  in the conveyance direction and downstream (on the side of the inclined part  76   e ) of the predetermined point of the parallel part  76   b  in the conveyance direction. For easy understanding, the length of the slide cam  72  in the conveyance direction depicted in  FIGS. 8A to 8G  is longer than that depicted in  FIG. 3A . 
     On the basis of the above, in this embodiment, the ASF motor  102  is rotated normally in a state where the nozzle cap  61  is in the capping position as depicted in  FIG. 6A , thereby moving the slide cam  72  in the conveyance direction. When the sensor  79  switches from the off state to the on state due to the movement of the slide cam  72 , the ASF motor  102  is rotated further by a predetermined amount to move the nozzle cap  61  from the capping position to the intermediate position as depicted in  FIG. 7A . In this situation, since the parallel part  76   d  extends parallel to the conveyance direction, even if the rotation amount of the ASF motor  102  after the sensor  79  switches from the off state to the on state varies slightly, the protruding part  68   c  is positioned in the parallel part  76   d  and the nozzle cap  61  is in the intermediate position reliably. Thus, even if the rotation amount of the ASF motor  102  after the sensor  79  switches from the off state to the on state varies slightly, the distance between the nozzle cap  61  and the ink jetting surface  12   a  does not vary. 
     In this embodiment, the ASF motor  102  is rotated further normally in the state where the nozzle cap  61  is in the intermediate position. When the sensor  79  switches from the on state to the off state, the ASF motor  102  is rotated still further by a predetermined amount to move the nozzle cap  61  from the intermediate position to the uncapping position as depicted in  FIG. 6B . Since the parallel part  76   c  extends parallel to the conveyance direction, even if the rotation amount of the ASF motor  102  after the sensor  79  switches from the on state to the off state varies slightly, the protruding part  68   c  is positioned in the parallel part  76   c  and the nozzle cap  61  is in the uncapping position reliably. 
     In this embodiment, the ASF motor  102  is rotated further normally to move the slide cam  72  downstream in the conveyance direction in the state where the nozzle cap  61  is in the uncapping position. When the sensor  79  switches from the off state to the on state, the ASF motor  102  is rotated still further by a predetermined amount to move the nozzle cap  61  from the uncapping position to the intermediate position as depicted in  FIG. 7B . Since the parallel part  76   d  extends parallel to the conveyance direction, even if the rotation amount of the ASF motor  102  after the sensor  79  switches from the off state to the on state varies slightly, the protruding part  68   c  is positioned in the parallel part  76   d  and the nozzle cap  61  is in the intermediate position reliably. Namely, even if the rotation amount of the ASF motor  102  after the sensor  79  switches from the off state to the on state varies slightly, the distance between the nozzle cap  61  and the ink jetting surface  12   a  does not vary. 
     In this embodiment, the ASF motor  102  is rotated further normally in the state where the nozzle cap  61  is in the intermediate position. When the sensor  79  switches from the on state to the off state, the ASF motor  102  is rotated still further by a predetermined amount to move the nozzle cap  61  from the intermediate position to the capping position as depicted in  FIG. 6A . Since the parallel part  76   b  extends parallel to the conveyance direction, even if the rotation amount of the ASF motor  102  after the sensor  79  switches from the on state to the off state varies slightly, the protruding part  68   c  is positioned in the parallel part  76   b  and the nozzle cap  61  is in the capping position reliably. 
     When the ASF motor  102  is rotated counterclockwise in the state where the selective drive gear  137  is connected to the ASF motor  102 , power of the ASF motor  102  is transmitted to the gears  137 ,  139   a , and  139   b . This rotates the sun gear  139   a  in the clockwise direction in  FIG. 9  and rotates the planet gear  139   b  about the axis of the sun gear  139   a  in the counterclockwise direction in  FIG. 9 , thereby engaging the planet gear  139   b  with the valve drive gear  134   a  from above. When the ASF motor  102  is further rotated counterclockwise in the state where the planet gear  139   b  is engaged with the valve drive gear  134   a , power of the ASF motor  102  is transmitted to the valve drive gear  134   a  to rotate respective gears constituting the valve drive gear group  134 . This results in rotations of the valve cam  85  and the channel member  82 . The rotation of the channel member  82  switches communication relations between the communicating ports  84   a  to  84   d  of the switch valve  62 , such as the communication and non-communication between the cap communicating ports  84   a ,  84   b  and the pump communicating ports  84   d.    
     &lt;Material of Gear&gt; 
     An explanation will be made about materials of the planet gear  139   b , the crank gear  73 , and the valve drive gear  134   a , the crank gear  73  and the valve drive gear  134  engageable with the planet gear  139   b . In this embodiment, as shown in  FIG. 10 , the crank gear  73  is made of a synthetic resin material, such as polyacetal resin (POM), containing, for example, glass fiber. The crank gear  73  contains, for example, approximately 25% by weight of glass fiber. Meanwhile, the planet gear  139   b  and the valve drive gear  134   a  are made of a synthetic resin material, such as polyacetal resin, containing no glass fiber.  FIG. 10  shows whether or not respective gears contain glass fiber. In the printer  1 , any other gears than the planet gear  139   b , the crank gear  73 , and the valve drive gear  134   a  are made, for example, of the synthetic resin material containing no glass fiber similar to the planet gear  139   b  and the valve drive gear  134   a.    
     The crank gear  73  made of the synthetic resin material containing glass fiber has a coefficient of dynamic friction greater than those of the planet gear  139   b  and the valve drive gear  134   a  made of the synthetic resin material containing no glass fiber. For example, the coefficient of dynamic friction, of polyacetal resin containing no glass fiber, against the same material is approximately 0.3. Meanwhile, the coefficient of dynamic friction, of polyacetal resin containing 25% by weight of glass fiber, against the same material is approximately 0.5. Further, for example, DURACON (trade name) M90-44 produced by Polyplastics Co., Ltd., which is a POM resin containing no glass fiber, has a coefficient of dynamic friction against carbon steel of approximately 0.46; DURACON (trade name) GH20 produced by Polyplastics Co., Ltd., which is a POM resin containing 20% by mass of glass fiber, has a coefficient of dynamic friction against carbon steel of approximately 0.55; and DURACON (trade name) GH25 produced by Polyplastics Co., Ltd., which is a POM resin containing 25% by mass of glass fiber, has a coefficient of dynamic friction against carbon steel of approximately 0.60. 
     Thus, a maximum friction force between the planet gear  139   b  and the crank gear  73  obtained when the planet gear  139  is engaged with the crank gear  73  is greater than a maximum friction force between the planet gear  139   b  and the valve drive gear  134   a  obtained when the planet gear  139   b  is engaged with the valve drive gear  134   a.    
     The suction pump  63  is a tube pump. As described above, the suction pump  63  communicates with the pump communicating port  84   d  of the switch valve  62  via the tube  86   d  and communicates with the waste liquid tank  64  via the tube  86   e  on the side opposite to the switch valve  62 . As depicted in  FIG. 11 , the suction pump  63  includes a gear  63   a . The gear  63   a , which is connected to a pump drive gear group  141  including a pump drive gear  141   a , is connectable to the PF motor  101  via the pump drive gear group  141  as will be described later. When the PF motor  101  is rotated normally in a state where the suction pump  63  is connected to the PF motor  101 , power of the PF motor  101  is transmitted to the suction pump  63  to make the suction pump  63  the non-communication state in which the tube  86   d  does not communicate with the tube  86   e . When the PF motor  101  is rotated further normally, the suction pump  63  performs suction. When the PF motor  101  is rotated reversely, power of the PF motor  101  is transmitted to the suction pump  63  to make the suction pump  63  the communication state in which the tube  86   d  communicates with the tube  86   e . Since the tube pump that switches between the non-communication state and the communicating state according to the rotation direction is well known, more detailed explanation thereof is omitted here. 
     The waste liquid tank  64  receives, for example, the ink discharged through a suction purge, etc., as described later. The space of the waste liquid tank  64  for receiving the ink communicates with the atmosphere. Thus, the atmosphere communicating port  84   c , which communicates with the waste liquid tank  64  via the tube  86   c , communicates with the atmosphere. Further, when the suction pump  63  is in the communication state, the pump communicating port  84   d  communicates with the atmosphere via the tubes  86   d ,  86   e , the suction pump  63 , and the waste liquid tank  64 . 
     &lt;Switching of Motor Connection&gt; 
     Subsequently, an explanation will be made about the switching of connection of each of the PF motor  101  and the ASF motor  102  with reference to  FIGS. 12A to 12C  and  FIGS. 13A to 13C . 
     As depicted in  FIGS. 12A to 12C  and  FIGS. 13A to 13C , the PF motor  101  is connected to a drive shaft  105 . The drive roller  13   a  is mounted on the drive shaft  105 . Further, a PF input gear  111  is mounted on the drive shaft  105 . Driving the PF motor  101  rotates the drive shaft  105 , the drive roller  13   a , and the PF input gear  111  integrally. 
     The PF input gear  111  is engaged with a PF switch gear  112 . The PF switch gear  112  is rotatably supported by a shaft  106  extending in the scanning direction. The PF switch gear  112  is movable, while being interlocked with movement of the carriage  11  in the scanning direction, along the shaft  106  in the scanning direction. Thus, the PF switch gear  112  can selectively move to any of the positions depicted in  FIGS. 12A to 12C . The PF switch gear  112  does not engage with the pump drive gear  141   a  in the positions depicted in  FIGS. 12A and 12B , and the PF switch gear  112  is engaged with the pump drive gear  141   a  in the position depicted in  FIG. 12C . The PF input gear  111  extends in the scanning direction, and the PF switch gear  112  is engaged with the PF input gear  111  in all of the positions depicted in  FIGS. 12A to 12C . 
     As depicted in  FIGS. 12A to 12C  and  FIGS. 13A to 13C , the ASF motor  102  is connected to an ASF input gear group  120 . The ASF input gear group  120  includes a clutch gear  121 . As depicted in  FIGS. 13A to 13C ,  FIG. 14A , and  FIG. 14B , the clutch gear  121  includes two gears  121   a  and  121   b . The gear  121   a  (a “first gear” of the present teaching) is a gear of which axis direction is parallel to the scanning direction. The gear  121   a  is connected to the ASF motor  102  via any other gear constituting the ASF input gear group  120 . The gear  121   b  (a “second gear” of the present teaching), which is disposed coaxially with the gear  121   a , is engaged with the ASF switch gear  122  while extending in the scanning direction. 
     The gear  121   a  is connected to the gear  121   b  with play in its rotation direction. More specifically, as depicted in  FIGS. 14A and 14B , a side surface of the gear  121   a  is provided with two protruding parts  121   a   1 . The two protruding parts  121   a   1  are disposed to be deviated in its circumferential direction of the gear  121   a  by approximately 180°. Each of the protruding parts  121   a   1  extends in the circumferential direction of the gear  121   a  while having an angle smaller than 90°. The interior of the gear  121   b  is provided with a cylindrical rib  121   b   1  extending in the scanning direction and four ribs  121   b   2  extending outward from an outer circumferential surface of the rib  121   b   1  in a radial direction of the gear  121   b . Of the four ribs  121   b   2 , the ribs  121   b   2  adjacent to each other in the circumferential direction of the gear  121   b  are disposed to be deviated from each other in the circumferential direction of the gear  121   b  by approximately 90°. The gear  121   a  is connected to the gear  121   b  by inserting each of the protruding parts  121   a   1  of the gear  121   a  into a space  121   b   3  between the two ribs  121   b   2  disposed adjacent to each other in the circumferential direction of the gear  121   b . The rotation of the ASF motor  102  rotates the gear  121   a . The gear  121   a  rotates independently before downstream ends of the protruding parts  121   a   1  in the rotation direction of the gear  121   a  make contact with the ribs  121   b   2 , and the gear  121   a  and the gear  121   b  rotate integrally in a state where the downstream ends of the protruding parts  121   a   1  are in contact with the ribs  121   b   2 . 
     The ASF switch gear  122  is mounted on the shaft  106  such that the positional relation between the ASF switch gear  122  and the PF switch gear  112  in the scanning direction is always kept. Thus, when the PF switch gear  112  moves in the scanning direction while being interlocked with movement of the carriage  11  in the scanning direction, the ASF switch gear  122  also moves in the scanning direction. 
     In this embodiment, the ASF switch gear  122  can be selectively moved to any of the positions depicted in  FIGS. 13A to 13C  during its movement in the scanning direction. The ASF switch gear  122  in the position depicted in  FIG. 13A  is engaged with the feed gear  131 . The ASF switch gear  122  in the position depicted in  FIGS. 13B and 13C  is engaged with the selective drive gear  137 . Since the gear  121   b  extends in the scanning direction, the ASF switch gear  122  in any of the positions depicted in  FIGS. 13A to 13C  is engaged with the gear  121   b.    
     Before the ASF switch gear  122  is moved between the positions depicted in  FIGS. 13A to 13C  to switch the gear to be engaged with the ASF switch gear  122 , the ASF motor  102  is driven to alternately rotate the ASF switch gear  122  and the gear to be engaged with the ASF switch gear  122  in both directions by a very small angle. This helps release of the gear engagement. In this embodiment, the clutch gear  121  is disposed between the ASF motor  102  and the ASF switch gear  122 , and the gear  121   a  of the clutch gear  121  is relatively rotatable to the gear  121   b  of the clutch gear  21  within the play. This allows the ASF switch gear  122  and the gear to be engaged with the ASF switch gear  122  to rotate smoothly. Accordingly, the number of times the operation for disengagement is performed is reduced, thereby making it possible to reduce the time required for the switching of the gear to be engaged with the ASF switch gear  122 . 
     &lt;Controller&gt; 
     Subsequently, an explanation will be made about a controller  150  that controls operation of the printer  1 . As depicted in  FIG. 15 , the controller  150  includes a Central Processing unit (CPU)  151 , a Read Only Memory (ROM)  152 , a Random Access Memory (RAM)  153 , an Application Specific Integrated Circuit (ASIC)  154 , and the like. They work cooperatively to control the operation of the carriage motor  156 , the ink-jet head  12 , the PF motor  101 , the ASF motor  102 , the wiper lifting unit  157 , and the like. 
     The controller  150  may include the single CPU  151 , as depicted in  FIG. 15 , to make the CPU  151  perform processing collectively or include a plurality of CPUs  151  to make the CPUs  151  perform processing in a shared manner. The controller  150  may include the single ASIC  154 , as depicted in  FIG. 15 , to make the ASIC  154  perform processing collectively or include a plurality of ASICs  154  to make the ASICs  154  perform processing in a shared manner. 
     &lt;Printing Operation&gt; 
     Subsequently, an explanation will be made about a method of performing printing with the printer  1 . When the printer  1  is in a standby state in which no printing and no maintenance which will be described later are performed, the nozzle cap  61  is in the capping position. This brings the nozzle cap  61  contact with the ink jetting surface  12   a  to prevent ink in nozzles  17  from being dried. In the standby state, the planet gear  139   b  is maintained in the engaging state with the crank gear  73 . In the standby state, as depicted in  FIG. 16A , the cap communicating ports  84   a  and  84   b  of the switch valve  62  communicate with the pomp communicating port  84   d  of the switch valve  62 . In the standby state, the suction pump  63  is in the communicating state. Thus, the caps  61   a  and  61   b  of the nozzle cap  61  covering nozzles  17  communicate with the atmosphere via the suction pump  63  in the standby state. In the standby state, the PF switch gear  112  and the ASF switch gear  122  are in the positions depicted in  FIG. 12C . In  FIG. 16A , the two-headed arrow indicates the communicating state of the suction pump  63 . 
     To make the printer  1  perform printing, at first, the ASF motor  102  is rotated normally to lower the nozzle cap  61  from the capping position to the uncapping position (S 101 ), as depicted in  FIG. 17 . Then, the carriage motor  156  is driven to move the carriage  11 , thereby moving the PF switch gear  112  and ASF switch gear  122  to the position depicted in  FIG. 12A . Then, the ASF motor  102  is rotated normally to supply the recording sheet P from the sheet cassette  21  to the printing unit  2  (S 102 ). 
     Then, rotating the PF motor  101  normally makes the conveyance rollers  13  and  14  convey each supplied recording sheet P in the conveyance direction. The carriage motor  156  is driven to move the carriage  11  reciprocatively in the scanning direction and the ink-jet head  12  is driven to jet ink from nozzles  17 , thereby performing printing on the recording sheet P (S 103 ). After completion of printing, the printer  1  returns to the standby state (S 104 ). In particular, the carriage motor  156  is driven to move the carriage  11  to a position where the ink jetting surface  12   a  faces the nozzle cap  61 , and the ASF motor  102  is rotated normally in a state where the carriage  11  is in the above position to move the nozzle cap  61  from the uncapping position to the capping position. Further, the ASF motor  102  is rotated normally until the nozzle cap  61  reaches the capping position, and then the ASF motor  102  is stopped. This maintains engagement between the planet gear  139  and the crank gear  73 . 
     When printing is performed, the gear to be engaged with the ASF switch gear  122  is switched before start of printing, as described above. Before the gear to be engaged with the ASF switch gear  122  is switched, the ASF motor  102  is driven to alternately rotate the ASF switch gear  122  and the gear to be engaged with the ASF switch gear  122  in both directions by a very small angle, thereby helping the release of the gear engagement. In this embodiment, since the clutch gear  121  is disposed between the ASF motor  102  and the ASF switch gear  122 , the time required for switching of the gear to be engaged with the ASF switch gear  122  can be reduced. Accordingly, the time that elapses before the start of printing is shortened. 
     &lt;Maintenance Process&gt; 
     Subsequently, an explanation will be made about a maintenance process using the maintenance unit  7  with reference to  FIG. 18 . In the maintenance process, the controller  150  first determines whether the channel member  82  is fixed so firmly to the accommodating member  81  that the channel member  82  can not rotate (S 201 ). When the channel member  82  is not fixed firmly to the accommodating member  81  (S 201 : No), the controller  150  performs S 203 . When the channel member  82  is fixed firmly to the accommodating member  81  (S 201 : Yes), the controller  150  performs valve cleaning (S 202 ) and then performs S 203 . In S 201 , for example, the determination is made as follows. Namely, when the ASF motor  102  is rotated reversely for a prescribed time period with the printer  1  being in the standby state, the channel member  82  may not rotate. In that case, a current flowing through the ASF motor  102  will exceed a predetermined threshold value, which makes it possible for the controller  150  to determine that the channel member  82  is fixed firmly to the accommodating member  81 . 
     In valve cleaning, as depicted in  FIG. 16B , rotating the PF motor  101  normally with the printer  1  being in the standby state allows the suction pump  63  to perform suction. The ink accumulating in the ink-jet head  12  is discharged from nozzles  17  through suction, flowing into the switch valve  62 . The ink solidified in the switch valve  62  dissolves by absorbing moisture or water of ink flowing into the switch valve  62 , thereby eliminating firm fixation of the channel member  82  to the accommodating member  81 . Further, the ASF motor  102  is rotated reversely during suction with the suction pump  63  to rotate the channel member  82 . This rotation allows the ink flowing into the switch valve  62  to spread over respective parts in the switch valve  62  uniformly, thereby making it possible to eliminate firm fixation of the channel member  82  to the accommodating member  81  efficiently. In  FIG. 16B , down arrows indicate a state in which the suction pump  63  in the non-communication state performs suction. The same is true on  FIGS. 16C to 16F . 
     When the suction purge or idle suction which will be described later is performed, ink flows into the switch valve  62 . If the ink flowing into the switch valve  62  is left for a long time, it may solidify to cause the channel member  82  to be firmly fixed to the accommodating member  81 . The firm fixation of the channel member  82  to the accommodating member  81  may fail to rotate the channel member  82  during the suction purge or the idle suction. In this embodiment, valve cleaning eliminates firm fixation of the channel member  82  to the accommodating member  81 . 
     In S 203 , the controller  150  performs the suction purge. More specifically, in S 203 , the controller  150  successively performs the suction purge for black ink in which viscous black ink accumulating in the ink-jet head  12  is discharged and the suction purge for color inks in which viscous color inks accumulating in the ink-jet head  12  are discharged. 
     In the suction purge for black ink, the ASF motor  102  is rotated reversely to rotate the channel member  82  in a state where the nozzle cap  61  is in the capping position and the switch gears  112 ,  122  are in the positions depicted in  FIG. 12C . The rotation of the channel member  82  allows the cap communicating port  84   a  to communicate with the pump communicating port  84   d  and allows the cap communicating port  84   b  to communicate with the atmosphere communicating port  84   c , as depicted in  FIG. 16C . In this situation, the PF motor  101  is rotated normally to make the suction pump  63  perform suction. Accordingly, the viscous black ink accumulating in the ink-jet head  12  is discharged from nozzles  17  forming the rightmost nozzle row  18 . The reason why the cap communicating port  84   b  is allowed to communicate with the atmosphere communicating port  84   c  is that this prevents the increase in pressure in the cap  61   b  which would be otherwise caused when deformation of the nozzle cap  61  during suction reduces the volume of the space in the cap  61   b.    
     In the suction purge for color inks, the ASF motor  102  is rotated reversely to rotate the channel member  82  in the state where the nozzle cap  61  is in the capping position and the switch gears  112 ,  122  are in the positions depicted in  FIG. 12C . The rotation of the channel member  82  allows the cap communicating port  84   b  to communicate with the pump communicating port  84   d  and allows the cap communicating port  84   a  to communicate with the atmosphere communicating port  84   c , as depicted in  FIG. 16D . In this situation, the PF motor  101  is rotated normally to make the suction pump  63  perform suction. Accordingly, the viscous color inks accumulating in the ink-jet head  12  are discharged from nozzles  17  forming the three nozzle rows  18  on the left of the rightmost nozzle row  18 . The reason why the cap communicating port  84   a  is allowed to communicate with the atmosphere communicating port  84   c  is that this prevents the increase in pressure in the cap  61   a  which would be otherwise caused when deformation of the nozzle cap  61  during suction reduces the volume of the space in the cap  61   a.    
     Subsequently, the controller  150  performs the idle suction in which the ink accumulating in the nozzle cap  61  is discharged through the suction purge (S 204 ). More specifically, in S 204 , the controller  150  successively performs the idle suction for black ink in which the black ink accumulating in the cap  61   a  is discharged by the suction purge for black ink and the idle suction for color inks in which the color inks accumulating in the cap  61   b  are discharged by the suction purge for color inks. 
     In the idle suction for black ink, the ASF motor  102  is rotated normally to rotate the crank gear  73  in a state where the switch gears  112 ,  122  are in the positions depicted in  FIG. 12C . The rotation of the crank gear  73  lowers the nozzle cap  61  from the capping position to the intermediate position, as depicted in  FIG. 7A . Subsequently, the ASF motor  102  is rotated reversely to rotate the channel member  82 . The rotation of the channel member  82  allows the cap communicating port  84   a  to communicate with the pump communicating port  84   d , as depicted in  FIG. 16E . In this situation, the PF motor  101  is rotated normally to make the suction pump  63  perform suction. Accordingly, the black ink accumulating in the cap  61   a  is discharged. 
     In the idle suction for color inks, the ASF motor  102  is rotated reversely to rotate the channel member  82  in a state where the nozzle cap  61  is in the intermediate position as depicted in  FIG. 7A . The rotation of the channel member  82  allows the cap communicating port  84   b  to communicate with the pump communicating port  84   d , as depicted in  FIG. 16F . In this situation, the PF motor  101  is rotated normally to make the suction pump  63  perform suction. Accordingly, the color inks accumulating in the cap  61   b  are discharged. 
     In some cases, except this embodiment, the ink (bridge) between the nozzle cap  61  and the ink jetting surface  12   a  may be broken when the nozzle cap  61  is lowered from the capping position to the uncapping position in idle suction to separate the nozzle cap  61  from the ink jetting surface  12   a . This might cause ink to be scattered around the nozzle cap  61 . In this embodiment, the nozzle cap  61  is lowered to the intermediate position in idle suction, and the height of the intermediate position of the nozzle cap  61  is designed such that the ink bridge is not broken when the nozzle cap  61  is lowered to the intermediate position. Thus, in this embodiment, it is possible to prevent ink from being scattered around the nozzle cap  61  which would be otherwise caused by the destruction of ink bridge in idle suction. 
     Subsequently, the controller  150  performs wiping by which ink adhering to the ink jetting surface  12   a  is wiped with the wiper  59  (S 205 ). To perform wiping, the ASF motor  102  is rotated normally to rotate the crank gear  73 . The rotation of the crank gear  73  lowers the nozzle cap  61  to the uncapping position, as depicted in  FIG. 6B . Further, the wiper lifting unit  157  is driven to move the wiper  59  upward, and the carriage motor  156  is driven to move the carriage  11  in the scanning direction. Accordingly, ink adhering to the ink jetting surface  12   a  is wiped with the wiper  59 . If the nozzle cap  61  is in the intermediate position during wiping, the ink jetting surface  12   a  may make contact with the nozzle cap  61  during movement of the carriage  11  in the scanning direction, because the distance between the nozzle cap  61  and the ink jetting surface  12   a  in the state where the nozzle cap  61  is in the intermediate position is smaller than that of the case in which the nozzle cap  61  is in the uncapping position. In this embodiment, in order to prevent the ink jetting surface  12   a  from making contact with the nozzle cap  61 , the nozzle cap  61  is lowered from the intermediate position to the uncapping position before the start of wiping. 
     Subsequently, the controller  150  performs flushing to discharge ink flowing from nozzles  17  through wiping (S 206 ). To perform flushing, the carriage motor  156  is driven to return the carriage  11  to the position where the ink jetting surface  12   a  faces the nozzle cap  61 . Then, the ASF motor  102  is rotated normally to rotate the crank gear  73 . The rotation of the crank gear  73  raises the nozzle cap  61  up to the intermediate position, as depicted in  FIG. 7B . In this situation, ink is discharged from nozzles  17  of the ink-jet head  12  to the nozzle cap  61 . 
     In some cases, except for this embodiment, flushing may be performed in a state where the nozzle cap  61  is in the uncapping position. In that case, ink jetted from nozzles  17  through flushing might be spattered on the nozzle cap  61  to fly out of the nozzle cap  61 . In this embodiment, during flushing, the nozzle cap  61  is in the intermediate position that is closer to the ink jetting surface  12   a  than the uncapping position. This prevents ink jetted from nozzles  17  through flushing from being spattered on the nozzle cap  61  to fly out of the nozzle cap  61 . 
     Subsequently, the controller  150  performs idle suction similar to S 204  to discharge ink accumulating in the nozzle cap  61  through flushing (S 207 ). After completion of the idle suction in S 207 , the ASF motor  102  is rotated normally to move the nozzle cap  61  to the capping position as depicted in  FIG. 6A , and the printer  1  returns to the standby state (S 208 ). In this situation, engagement between the planet gear  139   b  and the crank gear  73  is maintained by stopping the ASF motor  102  after the ASF motor  102  is rotated normally until the nozzle cap  61  reaches the capping position. Then, maintenance is completed. 
     To shorten the time from the standby state to the start of printing as much as possible, the printer  1  is required to shorten, as much as possible, the time required for movement of the nozzle cap  61  from the capping position to the uncapping position. In this embodiment, the planet gear  139   b  is movable between the engagement position with the crank gear  73  and the engagement position with the valve drive gear  134   a . Thus, if external force is applied on the planet gear  139   b  engaging with the crank gear  73 , the planet gear  139   b  might disengage from the crank gear  73 . 
     When the ASF motor  102  is driven to move the nozzle cap  61  from the capping position to the uncapping position in the state where the planet gear  139   b  is disengaged from the crank gear  73 , rotation of the crank gear  73 , namely, downward movement of the nozzle cap  61  is started at a point of time at which the planet gear  139  reaches the engagement position with the crank gear  73 . In that case, the nozzle cap  61  does not move downward while the planet gear  139   b  is moving to the engagement position with the crank gear  73 , thus lengthening the time required for movement of the nozzle cap  61  from the capping position to the uncapping position. This lengthens the time that elapses before the start of printing. 
     In this embodiment, since the planet gear  139   b  engages with the crank gear  73  from below, gravity might cause the planet gear  139  to disengage from the crank gear  73 . 
     In this embodiment, the clutch gear  121  is disposed between the ASF motor  102  and the ASF switch gear  122 . This reduces the time required for switching of the gear to be engaged with the ASF switch gear  122 , thus reducing the time that elapses before the start of printing. On the other hand, when the clutch gear  121  is disposed between the ASF motor  102  and the ASF switch gear  122 , relative rotation of the gears  121   a  and  121   b  of the clutch gear  121  within the play might cause the planet gear  139   b  to disengage from the crank gear  73 . Disengagement of the planet gear  139  from the crank gear  73  lengthens the time that elapses before the start of printing. 
     Thus, the crank gear  73  in this embodiment is made of the synthetic resin material containing glass fiber. This makes the maximum friction force between the planet gear  139   b  and the crank gear  73  greater than that of the case in which both of the planet gear  139   b  and the crank gear  73  are made of the synthetic resin material containing no glass fiber, thereby making it harder for the planet gear  139  to disengage from the crank gear  73 . As a result, the time required for movement of the nozzle cap  61  from the capping position to the uncapping position can be shortened. 
     Unlike this embodiment, not the crank gear  73  but the planet gear  139   b  may be made of the synthetic resin material containing glass fiber. In that case, the maximum friction force between the planet gear  139   b  and the valve drive gear  134   a  is greater than that of the case in which both of the planet gear  139   b  and the valve drive gear  134   a  are made of the synthetic resin material containing no glass fiber, thereby making it harder for the planet gear  139   b  to disengage from the valve drive gear  134   a . When the planet gear  139   b  moves from the engagement position with the valve drive gear  134   a  to the engagement position with the crank gear  73 , disengagement of the planet gear  139   b  from the valve drive gear  134   a  is helped by driving the ASF motor  102  to alternately rotate the planet gear  139   b  and the valve drive gear  134   a  in both directions by a very small angle. If it is difficult to release engagement between the planet gear  139   b  and the valve drive gear  134   a , the number of times the operation for disengagement is performed increases, thus lengthening the time that elapses before movement of the planet gear  139   b  is started. 
     In this embodiment, the crank gear  73  is made of the synthetic resin material containing glass fiber, and the planet gear  139   b  and the valve drive gear  134   a  are made of the synthetic resin material containing no glass fiber. This eliminates the difficulty in releasing engagement between the planet gear  139   b  and the valve drive gear  134   a.    
     In this embodiment, the ASF motor  102  is stopped after normal rotation of the ASF motor  102  moves the nozzle cap  61  to the capping position, thereby maintaining engagement between the planet gear  139   b  and the crank gear  73 . This enables the nozzle cap  61  to move downward immediately after the ASF motor  102  is rotated normally to move the nozzle cap  61  from the capping position to the uncapping position, for example, for the next printing. Thus, the time required for moving the nozzle cap  61  from the capping position to the uncapping position is shortened. 
     Subsequently, an explanation will be made about modified examples in which various modifications are added to the above embodiment. The constitutive parts or components, which are the same as or equivalent to those of the embodiment described above, are designated by the same reference numerals, any explanation of which will be omitted as appropriate. 
     In the above embodiment, of the crank gear  73  and the planet gear  139   b  that are engageable with each other, only the crank gear  73  is made of the synthetic resin material containing glass fiber, and the planet gear  139   b  is made of the synthetic resin material containing no glass fiber. The present teaching, however, is not limited thereto. 
     In a first modified example, as indicated in  FIG. 19A , the planet gear  139   b  is made of the synthetic resin material containing glass fiber, and the crank gear  73  and the valve drive gear  134   a  are made of the synthetic resin material containing no glass fiber. In that case, like the above embodiment, disengagement of the planet gear  139  from the crank gear  73  is harder than the case in which both of the crank gear  73  and the planet gear  139   b  are made of the synthetic resin material containing no glass fiber. 
     In a second modified example, as indicated in  FIG. 19B , the crank gear  73  and the planet gear  139   b  are made of the synthetic resin material containing glass fiber, and the valve drive gear  134   a  is made of the synthetic rein material containing no glass fiber. In that case, disengagement of the planet gear  139   b  from the crank gear  73  is much harder than the cases, like the above embodiment and the first modified example, in which only one of the crank gear  73  and the planet gear  139   b  is made of the synthetic resin material containing the glass fiber. 
     In the above embodiment and the first and second modified examples, the valve drive gear  134   a  is made of the synthetic resin material containing no glass fiber. The present teaching, however, is not limited thereto. 
     In a third modified example, as indicated in  FIG. 19C , the crank gear  73  and the valve drive gear  134   a  are made of the synthetic resin material containing glass fiber, and the planet gear  139   b  is made of the synthetic resin material containing no glass fiber. 
     In a fourth modified example, as indicated in  FIG. 19D , the planet gear  139   b  and the valve drive gear  134   a  are made of the synthetic resin material containing glass fiber, and the crank gear  73  is made of the synthetic resin material containing no glass fiber. 
     In a fifth modified example, as indicated in  FIG. 19E , all of the crank gear  73 , the planet gear  139   b , and the valve drive gear  134   a  are made of the synthetic resin material containing glass fiber. 
     Like the above embodiment and the first and second modified examples, the third to fifth modified examples make it harder for the planet gear  139   b  to disengage from the crank gear  73 . 
     Note that, when at least one of the planet gear  139   b  and the valve drive gear  134   a  is made of the synthetic resin material containing glass fiber as in the first to the fifth modified examples, disengagement of the planet gear  139   b  from the valve drive gear  134   a  is harder than the above embodiment. 
     In the second to fifth modified examples, two or more of the crank gear  73 , the valve drive gear  134   a , and the planet gear  139   b  may be made of the synthetic resin material containing glass fiber. In that case, gears containing the glass fiber may have a content rate of glass fiber identical to each other or content rates of glass fiber different from each other. 
     Note that, when both of the crank gear  73  and the planet gear  139   b  are made of the synthetic resin material containing glass fiber as in the second and fifth modified examples, it is preferred that a content rate R 1  of glass fiber in the crank gear  73  be higher than a content rate R 2  of glass fiber in the planet gear  139   b , as indicated in  FIG. 20A . 
     Regarding the gear made of the synthetic resin material containing glass fiber, the coefficient of dynamic friction increases as the content rate of glass fiber is higher. For example, NOVALLOY (trade name) B2504 produced by Daicel Polymer Ltd., which is an ABS/PBT resin containing 20% by mass of glass fiber, has a coefficient of dynamic friction against the same material of approximately 0.32. NOVALLOY (trade name) B2509 produced by Daicel Polymer Ltd., which is an ABS/PBT resin containing 45% by mass of glass fiber, has a coefficient of dynamic friction against the same material of approximately 0.36. As described above, DURACON (trade name) GH20 produced by Polyplastics Co., Ltd., which is a POM resin containing 20% by mass of glass fiber, has a coefficient of dynamic friction against carbon steel of approximately 0.55. DURACON (trade name) GH25 produced by Polyplastics Co., Ltd., which is a POM resin containing 25% by mass of glass fiber, has a coefficient of dynamic friction against carbon steel of approximately 0.60. 
     Thus, when the content rate R 1  of glass fiber in the crank gear  73  is higher than the content rate R 2  of glass fiber in the planet gear  139   b , engagement between the valve drive gear  134   a  and the crank gear  73  can be released as easily as possible in a state where engagement between the crank gear  73  and the planet gear  139   b  is not released easily. 
     When both of the crank gear  73  and the valve drive gear  134   a  are made of the synthetic resin material containing glass fiber as in the third and fifth modified examples, it is preferred that a content rate R 3  of glass fiber in the crank gear  73  be higher than a content rate R 4  of glass fiber in the valve drive gear  134   a , as indicated in  FIG. 20B . 
     As described above, regarding the gear made of the synthetic resin material containing glass fiber, the coefficient of dynamic friction increases as the content rate of glass fiber is higher. Thus, when the content rate R 3  of glass fiber in the crank gear  73  is higher than the content rate R 4  of glass fiber in the valve drive gear  134   a , engagement between the valve drive gear  134   a  and the crank gear  73  can be released as easily as possible in state where engagement between the crank gear  73  and the planet gear  139   b  is not released easily. 
     In the embodiment and the first to fifth modified examples, engagement between the crank gear  73  and the planet gear  139   b  is not released easily by using the synthetic resin material containing glass fiber in at least one of the crank gear  73  and the planet gear  139   b . The present teaching, however, is not limited thereto. For example, the maximum friction force between the crank gear  73  and the planet gear  139   b  obtained when the crank gear  73  is engaged with the planet gear  139   b  can be improved by performing a surface treatment for the crank gear  73  and the planet gear  139   b  so that concavities and convexities are formed on their gear surfaces. In that case, it is not indispensable that both of the crank gear  73  and the planet gear  139   b  are made of the synthetic resin material. For example, one of the crank gear  73  and the planet gear  139   b  may be made of the synthetic resin material, and the other of the crank gear  73  and the planet gear  139   b  may be made of metal. 
     In the above embodiment, the clutch gear  121  is provided between the ASF switch gear  122  and the ASF motor  102  to be engageable with the ASF switch gear  122 . The present teaching, however, is not limited thereto. The clutch gear  121  may be provided between the ASF switch gear  122  and the ASF motor  102  to be engageable with the ASF switch gear  122  via another gear. Or, the clutch gear  121  may be a gear, of gears provided between the ASF motor  102  and the crank gear  73 , disposed on the side closer to the crank gear  73  than the ASF switch gear  122 , such as a gear provided between the ASF switch gear  122  and the sun gear  139   a . Or, the clutch gear  121  may not be provided between the ASF motor  102  and the crank gear  73 . 
     In the above embodiment, the planet gear  139   b  engages with the crank gear  73  from below. The present teaching, however, is not limited thereto. The planet gear  139   b  may engage with the crank gear  73  from a horizontal direction, or the planet gear  139   b  may engage with the crank gear  73  from above. In those cases, it is possible to prevent disengagement of the planet gear  139   b  from the crank gear  73  which would be otherwise caused when some reason causes external force in a direction in which the planet gear  139   b  separates from the crank gear  73  to act on the planet gear  139   b.    
     In the above embodiment, the planet gear  139   b  is engageable with the crank gear  73  connected to the slide cam  72 . The present teaching, however, is not limited thereto. The planet gear  139   b  may be connected to the crank gear  73  via another gear. In that case, the another gear corresponds to the “first transmission gear” of the present teaching. 
     In the above embodiment, the valve drive gear  134   a  engageable with the planet gear  139   b  is connected to the valve cam  85  via another gear constituting the valve drive gear group  134 . The present teaching, however, is not limited thereto. The planet gear  139   b  may be engageable with a gear that is directly connected to the valve cam  85 . In that case, the gear directly connected to the valve cam  85  corresponds to the “second transmission gear” of the present teaching. 
     In the above embodiment, the planet gear  139   b  is movable between the position where it engages with the crank gear  73  to move the nozzle cap  61  upward and the position where it engages with the valve drive gear  134   a  to rotate the valve cam  85 . The present teaching, however, is not limited thereto. The planet gear  139   b  is movable between the position where it engages with the crank gear  73  and a position where it engages with a gear (the “second transmission gear” of the present teaching) for transmitting power to a driven device except for the valve cam  85 . 
     In the above embodiment, the planet gear  139   b  is guided by the sun gear  139   a  and the connection member  139   c  to move between the engagement position with the crank gear  73  and the engagement position with the valve drive gear  134   a . The present teaching, however, is not limited thereto. The planet gear  139   b  may be guided by a guide part configured to be different from that of the above embodiment. 
     In the above embodiment, rotating the planet gear  139   b  around the shaft of the sun gear  139   a  depending on the rotation direction of the sun gear  139   a  (the rotation direction of the ASF motor  102 ) enables movement of the planet gear  139   b  between the engagement position with the crank gear  73  and the engagement position with the valve drive gear  134   a . The present teaching, however, is not limited thereto. It is allowable to provide a gear (a “movement gear” of the present teaching) that has a configuration different from that of the planet gear mechanism  139  and is movable between an engagement position with the crank gear  73  and an engagement position with the valve drive gear  134   a  by moving in different directions depending on the rotation direction of the ASF motor  102 . In that case, the movement gear moving between the two positions is guided by a guide part configured to be different from the sun gear  139   a  and the connection member  139   c  of the above embodiment. 
     In the above embodiment, power from the ASF motor  102  drives the cap lifting device  70 . The present teaching, however, is not limited thereto. For example, a motor different from the ASF motor, such as the PF motor  101 , may drive the cap lifting device  70 . 
     The configuration of the cap lifting device moving the nozzle cap  61  upward and downward is not limited to the configuration of the cap lifting device  70  in the above embodiment. A device having a configuration different from that of the cap lifting device  70  may move the nozzle cap  61  upward and downward. 
     As depicted in  FIG. 21 , a printer  200  of a sixth modified example includes a feed roller  222  (a “feeder” of the present teaching) feeding the recording sheet P accommodated in the sheet cassette  21  as well as a drive roller  213   a  (a “conveyer” of the present teaching) and a driven roller  213   b  that nip the recording sheet P fed from the feed roller  222  therebetween. A motor  201  drives both of the feed roller  222  and the drive roller  213   a . The motor  201  is connected to an intermediate gear  238 , and power from the motor  201  is transmitted to the intermediate gear  238 . The intermediate gear  238  is engaged with a sun gear  239   a , and the sun gear  239   a  is engaged with a planet gear  239   b . The drive roller  213   a  is connected to a roller drive gear  250  via the intermediate gear  248 , and the feed roller  222  is connected to a feed drive gear  270  via the intermediate gear  268 . The roller drive gear  250  is disposed above the feed drive gear  270 , and the roller drive gear  250  and the feed drive gear  270  are disposed to sandwich the planet gear  239   b  in an up-down direction. The planet gear  239   b  is movable in the up-down direction. The planet gear  239   b  moves upward to engage with the roller drive gear  250 , and the planet gear  239   b  moves downward to engage with the feed drive gear  270 . The motor  201  and the intermediate gear  238  may be configured such that power is transmitted to them via gears. In  FIG. 21 , illustration of the configuration between the motor  201  and the intermediate gear  238  is omitted. 
     The coefficient of dynamic friction of the planet gear  239   b  against the roller drive gear  250  is greater than the coefficient of dynamic friction of the planet gear  239   b  against the feed drive gear  270 . In particular, the roller drive gear  250  is made of the synthetic resin material containing glass fiber as described above. Meanwhile, the planet gear  239   b  and the feed drive gear  270  are made of the synthetic resin material containing no glass fiber, such as polyacetal resin. 
     For example, when the printer  200  receives a printing data that is large in data size from a PC, a tablet, or the like and performs printing, the printer  200  may come into a standby state during printing because of reception of the printing data. In that case, in order to restart the printing quickly after the printer  200  finishes reception of necessary printing data, it is preferred that the motor  201  and the drive roller  213   a  be maintained in a state where power can be transmitted to them. In the printer  200 , the planet gear  239   b  is positioned below the roller drive gear  250  due to the layout or arrangement of the drive roller  213   a  and the feed roller  222 . This might cause disengagement of the planet gear  239   b  from the roller drive gear  250 , for example, when the printer  200  has vibration. In the printer  200 , however, the planet gear  239   b  is made of the synthetic resin material containing glass fiber, thus increasing the coefficient of dynamic friction of the planet gear  239   b  against the roller drive gear  250 . This makes it harder for the planet gear  239   b  to disengage from the roller drive gear  250 . 
     When the recording sheet P is conveyed, the planet gear  239   b  can be switched to engage with the roller drive gear  250  quickly after the feed roller  222  is driven with the planet gear  239   b  and the feed drive gear  270  engaged with each other. The feed drive gear  270  is positioned below the planet gear  239   b , and thus disengagement of the planet gear  239   b  from the feed drive gear  270  is not caused accidentally. When printing for a printing data that is large in data size is performed, a part of the recording sheet P is typically positioned below the ink-jet head  12 . This means that the feed roller  222  is less likely to be used at the time of restart of the printing. Thus, the feed drive gear  270  can disengage from the planet gear  239   b  quickly, achieving quick switching of power transmission in printing. 
     In the sixth modified example, only the roller drive gear  250  is made of the synthetic resin material containing glass fiber. The present teaching, however, is not limited thereto. For example, both of the roller drive gear  250  and the planet gear  239   b  may be made of the synthetic resin material containing glass fiber, and the feed drive gear  270  may be made of the synthetic resin material containing no glass fiber. 
     As depicted in  FIG. 22 , a printer  300  of a seventh modified example includes two sheet cassettes  320 ,  321  that are disposed in parallel in an up-down direction to accommodate recording sheets P. The recording sheet P is fed from the sheet cassette  320  by the feed roller  323  (a “second feeder” of the present teaching), and the recording sheet P is fed from the sheet cassette  321  by the feed roller  322  (a “first feeder” of the present teaching). In the printer  300 , the PF motor  101  selectively drives the feed roller  322  and the feed roller  323 . The feed roller  322  is connected to a feed drive gear  370  via a belt  372  and an intermediate gear  371 . The feed roller  323  is connected to a feed drive gear  380  via a belt  384 . The feed drive gear  370  is disposed above the feed drive gear  380 . The printer  300  includes a sun gear  339   a  to be driven by the PF motor  101  and a planet gear  339   b  engaged with the sun gear  339   a . The planet gear  339   b  is positioned between the feed drive gear  370  and the feed drive gear  380  in the up-down direction. When the recording sheet P is fed from the sheet cassette  321 , the PF motor  101  is driven to drive the feed roller  322  in a state where the planet gear  339   b  is engaged with the feed drive gear  370 . When the recording sheet P is fed from the sheet cassette  320 , the PF motor  101  is driven to drive the feed roller  323  in a state where the planet gear  339   b  is engaged with the feed drive gear  380 .  FIG. 22  depicts only some parts of the printer  300 , and illustration of the constitutive parts or components, which are the same as or equivalent to those of the embodiment described above, is omitted. Although not depicted in  FIG. 22 , for example, the feed drive gears  370  and  380  may be disposed not to overlap with each other in the scanning direction in order to prevent the gears  370  and  380  from interfering with the recording sheet P. Or, it is allowable to provide, for example, ribs forming a conveyance route of the recording sheet P, as appropriate. 
     For example, when the printer  300  is designed such that, of the two sheet cassettes  320  and  321 , the sheet cassette  321  is used as a standard cassette, the feed drive gear  370  to be connected to the feed roller  322  is made of the synthetic resin material containing glass fiber. The planet gear  339   b  and the feed drive gear  380  are made of the synthetic resin material containing no glass fiber. 
     Thus, the coefficient of dynamic friction of the planet gear  339   b  against the feed drive gear  370  is greater than the coefficient of dynamic friction of the planet gear  339   b  against the feed drive gear  380 . This makes it easier to maintain engagement between the planet gear  339   b  and the feed drive gear  370  when the printer  300  is in a standby state in which no printing is performed. 
     In the seventh modified example, only the feed drive gear  370  is made of the synthetic resin material containing glass fiber. The present teaching, however, is not limited thereto. For example, both of the planet gear  339   b  and the feed drive gear  370  may be made of the synthetic resin material containing glass fiber, and the feed drive gear  380  may be made of the synthetic resin material containing no glass fiber. 
     The above description explains the examples in which the nozzle cap makes contact with the ink jetting surface to cover the nozzles in the capping position. The present teaching, however, is not limited thereto. Provided that the nozzle cap can cover the nozzles, the nozzle cap may make contact with other part than the ink jetting surface in the capping position. 
     The above description explains the examples in which the present teaching is applied to the printer that discharges ink from nozzles to perform printing on the recording sheet. The present teaching, however, is not limited thereto. The present teaching may be applied, in addition to the printer, to liquid jetting apparatuses jetting liquid other than ink. 
     The above description explains the examples in which the present teaching is applied to the printer. The present teaching, however, is not limited thereto. The present teaching may be applied to any other apparatus, provided that it includes a power transmission mechanism that selectively drives one motor and two driven targets.