Abstract:
An image recorder includes a driving source generating any of a first-direction force and a second-direction force, a function executing mechanism executing a functional operation, a switching mechanism switching between a first state to allow the function executing mechanism to execute the functional operation and a second state to forbid the function executing mechanism to execute the functional operation, a transmission mechanism transmitting the first-direction force to a feed roller unit and the function executing mechanism and transmitting the second-direction force to the feed roller unit and the switching mechanism, and a controller that after detection of a sheet on a tray, controls the driving source to generate the second-direction force such that the switching mechanism switches to the second state, and thereafter controls the driving source to generate the first-direction force such that the feed roller unit nips the sheet on the tray.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 from Japanese Patent Application No. 2009-201050 filed on Aug. 31, 2009. The entire subject matter of the application is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The following description relates to one or more image recorders configured to record an image on a sheet, in particular, to one or more image recorders configured such that a user makes a leading end of a sheet directly contact a pair of feed rollers disposed on a sheet feeding path. 
     2. Related Art 
     Image recorders have been known that are configured such that a user makes a sheet contact a nipping point between two feed rollers as a set reference position. As an example of such image recorders, a printer has been known, in which a user makes a sheet contact a nipping point between two feed rollers while manually feeding the sheet along a sheet guide. Then, using a sheet insertion detector, a control circuit detects the insertion of the sheet between the feed rollers. In response to the detection of the sheet inserted between the feed rollers, the control circuit controls a motor driver to drive the feed rollers, so as to feed the sheet. 
     Thus, according to the aforementioned printer, since the user can make a sheet contact the nipping point between the feed rollers, a pickup roller (to be provided separately from the feed rollers) for conveying the sheet from a tray to the nipping point are not required. Therefore, it is possible to save the manufacturing cost of the printer. 
     SUMMARY 
     Further, an image recorder has been known that has a single driving source used in common for driving a pair of feed rollers and another mechanism. 
     In the aforementioned printer, a sheet is required to be nipped in the nipping point between the feed rollers. Therefore, to nip the sheet between the feed rollers, for instance, a control mechanism may be provided that is configured to rotate the feed rollers in a forward direction by a predetermined distance (e.g., several millimeters) after the user makes the sheet contact the nipping point between the feed rollers. 
     However, when such a structure that a single driving source is used in common for driving the feed rollers and another mechanism is applied to the aforementioned printer, the following problem might be caused. 
     For example, it is assumed that a driving source for driving the feed rollers is employed as well for driving a suction mechanism configured to suck ink from one or more nozzles for discharging drops of ink onto a sheet. In this case, each time the feed rollers are driven to nip a sheet, the suction mechanism sucks some ink from the nozzles. Thus, it results in an increased amount of ink consumption. Furthermore, it is assumed that the driving source for driving the feed rollers is employed as well for driving a pickup roller configured to feed a sheet forward from a tray. In this case, each time the feed rollers are driven to nip a sheet, the pickup roller feeds another sheet from the tray. 
     Aspects of the present invention are advantageous to provide one or more improved image recorders configured to control feed rollers to nip a sheet that is manually rendered in contact with a nipping point between the feed rollers, without exerting on the image recorder a negative influence that could be caused by driving any other mechanism with a driving source used in common for driving the feed rollers. 
     According to aspects of the present invention, an image recorder is provided, which includes a first tray configured such that a sheet is placed thereon, a driving source configured to generate a driving force in any of a first direction and a second direction different from the first direction, a feed roller unit configured to, in response to receipt of the driving force in the first direction from the driving source, nip a leading end of the sheet placed on the first tray, a function executing mechanism configured to, in response to receipt of the driving force in the first direction from the driving source, execute a predetermined functional operation, a switching mechanism configured to switch between a first state to allow the function executing mechanism to execute the predetermined functional operation, and a second state to forbid the function executing mechanism to execute the predetermined functional operation, a transmission mechanism configured to transmit the driving force in the first direction from the driving source to the feed roller unit and the function executing mechanism, and transmit the driving force in the second direction from the driving source to the feed roller unit and the switching mechanism, a sheet detector configured to detect the sheet placed on the first tray, and a controller configured to, in response to the sheet detector detecting the sheet placed on the first tray, control the driving source to generate the driving force in the second direction such that the switching mechanism, which receives the driving force in the second direction from the driving source via the transmission mechanism, switches to the second state, and thereafter control the driving source to generate the driving force in the first direction such that the feed roller unit, which receives the driving force in the first direction from the driving source via the transmission mechanism, nips the sheet on the first tray. 
    
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
         FIG. 1  is a perspective view schematically showing an external configuration of a multi-function peripheral (MFP) in an embodiment according to one or more aspects of the present invention. 
         FIG. 2  is a cross-sectional side view schematically showing an internal configuration of a printing unit of the MFP in the embodiment according to one or more aspects of the present invention. 
         FIG. 3  is a cross-sectional partial top view showing the internal configuration of the printing unit of the MFP in the embodiment according to one or more aspects of the present invention. 
         FIG. 4  is a perspective view of a maintenance unit in the embodiment according to one or more aspects of the present invention. 
         FIG. 5A  is a cross-sectional front view of a purge mechanism in a state where a cap is not lifted up in the embodiment according to one or more aspects of the present invention. 
         FIG. 5B  is a cross-sectional front view of the purge mechanism in a state where the cap is lifted up in the embodiment according to one or more aspects of the present invention. 
         FIG. 6  is a perspective view of the maintenance unit to show an external configuration of a port switching mechanism in the embodiment according to one or more aspects of the present invention. 
         FIG. 7A  is a top view of the port switching mechanism in a state where an inlet port does not communicate with any other ports in the embodiment according to one or more aspects of the present invention. 
         FIG. 7B  is a top view of the port switching mechanism in a state where the inlet port communicates with a Bk port in the embodiment according to one or more aspects of the present invention. 
         FIG. 7C  is a top view of the port switching mechanism in a state where the inlet port does not communicate with any other ports in the embodiment according to one or more aspects of the present invention. 
         FIG. 7D  is a top view of the port switching mechanism in a state where the inlet port communicates with a Co port in the embodiment according to one or more aspects of the present invention. 
         FIG. 8  is a block diagram schematically showing a configuration of a controller connected with other elements in the embodiment according to one or more aspects of the present invention. 
         FIG. 9  is a flowchart showing a procedure of a nip control process to be executed by the controller in the embodiment according to one or more aspects of the present invention. 
         FIG. 10  is a flowchart showing a procedure of a nip control process to be executed by the controller in a modification according to one or more aspects of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     It is noted that various connections are set forth between elements in the following description. It is noted that these connections in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. Aspects of the invention may be implemented in computer software as programs storable on computer-readable media including but not limited to RAMs, ROMs, flash memories, EEPROMs, CD-media, DVD-media, temporary storage, hard disk drives, floppy drives, permanent storage, and the like. 
     Hereinafter, an embodiment according to aspects of the present invention will be described with reference to the accompany drawings. 
     In the following description, as depicted in  FIG. 1 , the directions indicated by the reference numerals “ 7 ,” “ 8 ,” and “ 9 ” will be defined as an up-to-down direction, a front-to-rear direction, and a left-to-right direction, respectively. 
     A multi-function peripheral (MFP)  10  of an embodiment includes an image reading unit  12  disposed at an upper side of the MFP  10 , an operation panel  121  disposed at a front side of an upper surface of the MFP  10 , and an inkjet printing unit  11  disposed at a lower side of the MFP  10 . The MFP  10  has various functions such as a facsimile function, a printer function, a scanner function, and a copier function. In the embodiment, the MFP  10  has a single-side image recording function as a printer function. However, the MFP  10  may have a double-side image recording function. 
     [Configuration of Image Reading Unit] 
     The image reading unit  12  is disposed above the printing unit  11  and provided with a scanner section  122 . The scanner section  122  includes a flatbed scanner (FBS) and an automatic document feeder (ADF). In the embodiment, the scanner section  122  may be configured in any fashion as far as the scanner section  122  reads an image recorded on a document sheet. Therefore, a detailed explanation about a configuration of the scanner section  122  will be omitted. 
     [Configuration of Operation Panel] 
     The MFP  10  has the operation panel  121  for operating the printing unit  11  and the scanner section  122  which operation panel is provided at the front side of the upper surface of the MFP  10 , i.e., on an upper surface of a front side of the scanner section  122 . The operation panel  121  includes various kinds of operation buttons and a liquid crystal display (LCD) unit. The MFP  10  is operated by an instruction input through the operation panel  121 . 
     [Configuration of Printing Unit] 
     As illustrated in  FIG. 1 , the printing unit  11  has a casing  14  with an opening formed at each of a front side and a back side thereof. Inside the casing  14 , constituent elements of the printing unit  11  are disposed. A container is secured to successively extend from the front opening (not shown) of the printing unit  11  to the inside of the casing  14 . A sheet feed cassette  78  is attached inside the container. The sheet feed cassette  78  is configured to be inserted into and ejected from the casing  14  via the front opening. The sheet feed cassette  78  is configured to hold various sizes of recording sheets. In the embodiment, the MFP  10  is configured such that the sheet feed cassette  78  is only attached thereto. However, the MFP  10  may have a plurality of sheet feed cassette  78  attached thereto. 
     At a back surface  14 A of the printing unit  11 , a manual sheet feed tray  20  is disposed, in an openable and closable manner, at a height level between the scanner section  122  and the sheet feed cassette  78 . As indicated by dashed-line arrows in  FIG. 2 , the manual sheet feed tray  20  is opened and closed while rotating around a rotation shaft  21 . In  FIG. 1 , the manual sheet feed tray  20  is closed. In  FIG. 2 , an opened state and a closed state of the manual sheet feed tray  20  are indicated by a solid line and a dashed line, respectively. The manual sheet feed tray  20  is configured to be loaded with various sizes of recording sheets in the opened state. At the back surface of the printing unit  11 , a rear opening  13  is provided to face a lower base end of the manual sheet feed tray  20 . A recording sheet is inserted by a user forward from the rear opening  13  while being supported by a sheet loading surface of the manual sheet feed tray  20 . 
     Subsequently, referring to  FIG. 2 , a more detailed explanation will be provided about the configuration of the printing unit  11 . In  FIG. 2 , a front side relative to the sheet feed cassette  78  is not shown. In addition to the sheet feed cassette  78 , the printing unit  11  includes a feeder section  15  configured to pick up a recording sheet from the sheet feed cassette  78  and feed the recording sheet, and an inkjet recording section  24  configured to form an image on the recording sheet fed by the feeder section  15  by discharging drops of ink onto the recording sheet. 
     [Feeding Path] 
     As depicted in  FIG. 2 , inside the printing unit  11 , a feeding path  65  is formed to extend from the sheet feed cassette  78  and the manual sheet feed tray  20  to a catch tray  79  via the recording section  24 . The feeding path  65  includes a curved path  65 A formed between a rear end of the sheet feed cassette  78  and the recording section  24 , a conveying path  65 B formed between a front end of the manual sheet feed tray  20  and a converging point  65 D between the curved path  65 A and the conveying path  65 B, and a sheet ejecting path  65 C formed between the recording section  24  and the catch tray  79 . It is noted that the catch tray  79  may be configured to be integrated with the sheet feed cassette  78  or to be fixed to a frame of the printing unit  11 . 
     The curved path  65 A is bent to extend from around an upper end of a tilted plate separator  22  provided to the sheet feed cassette  78  to the recording section  24 . A recording sheet is conveyed backward from the sheet feed cassette  78 . Then, the recording sheet is U-turned upward from a downside of the MFP  10  at the back surface side of the MFP  10 . Thereafter, the recording sheet is conveyed forward. The curved path  65 A is defined by an outside guide member  18  and an inside guide member  19  which are disposed to face each other across a predetermined distance. It is noted that the outside guide member  18 , the inside guide member  19 , and a below-mentioned first lower guide member  180 , first upper guide member  181 , second upper guide member  182 , lower guide member  183 , and third upper guide member  184  extend along the left-to-right direction  9  (see  FIG. 1 ). 
     The conveying path  65 B is formed to linearly extend from the rear opening  13  of the printing unit  11  to the converging point  65 D. A recording sheet is inserted so as to contact a nipping point  60 A between a first feed roller  60  and a pinch roller  61  via the rear opening  13  and the conveying path  65 B. The conveying path  65 B is defined by a first lower guide member  180  and a first upper guide member  181  which are disposed to face each other across a predetermined distance. There is a second upper guide member  182  provided downstream relative to the first upper guide member  181  in a feeding direction. It is noted that the feeding direction denotes a direction (indicated by a chain double-dashed line with arrows in  FIG. 2 ) in which a recording sheet is conveyed on the feeding path  65 . The second upper guide member  182  is formed to extend from a front end of the first upper guide member  181  to around an upper side of the converging point  65 D. Further, the second upper guide member  182  is configured to guide the recording sheet inserted from the manual sheet feed tray  20  to the nipping point  60 A via the converging point  65 D. In the embodiment, the first lower guide member  180  and the outside guide member  18  are separately formed. However, the first lower guide member  180  and the outside guide member  18  may be formed in an integrated manner. 
     The sheet ejecting path  65 C is defined by a second lower guide member  183  and a third upper guide member  184  that are disposed downstream relative to the recording section  24  in the feeding direction. The sheet ejecting path  65 C is configured to guide a recording sheet with an image recorded thereon that is fed by a second feed roller  62  toward a downstream side in the feeding direction while supporting a lower surface of the recording sheet. The third upper guide member  184  is disposed above the second lower guide member  183 . The third upper guide member  184  and the second lower guide member  183  are disposed to face each other across such a predetermined distance that a recording sheet passes therebetween. 
     [Feeder Section] 
     The feeder section  15  is configured to feed recording sheets placed in the sheet feed cassette  78  to the curved path  65 A. The feeder section  15  includes a pickup roller  25 , a pickup arm  26 , and a feeder driving mechanism  27 . The pickup roller  25  is disposed above the sheet feed cassette  78 . The pickup roller  25  is configured to pick up a recording sheet placed in the sheet feed cassette  78  and feed the recording sheet to the curved path  65 A. The pickup roller  25  is rotatably supported by a leading end of the pickup arm  26 . The pickup roller  25  is rotated by a driving force that is transmitted by a motor for sheet feeding via the feeder driving mechanism  27 . The feeder driving mechanism  27  includes a plurality of gears that are rotatably supported by the pickup arm  26  and arranged substantially in a linear manner along a longitudinal direction of the pickup arm  26 . The pickup roller  25  is configured to rotate around a rotation shaft  28  and establish pressure-contact with a top recording sheet placed in the sheet feed cassette  78 . 
     [Registration Sensor] 
     A registration sensor  110  is disposed on the curved path  65 A. The registration sensor  110  is configured to detect a leading end of a recording sheet which is fed on the curved path  65 A from the sheet feed cassette  78  or inserted from the manual sheet feed tray  20  via the conveying path  6513 . For instance, the registration sensor  110  includes a rotational body having detectors  112 A and  11213 , and an optical sensor  111  such as a photo-interrupter having a light emitter (e.g., a light emitting diode) and a light receiver (e.g., a photodiode) configured to receive light from the light emitter. The rotational body is configured to rotate around a rotation shaft  113 . The detector  112 A protrudes from the rotation shaft  113  into the curved path  65 A. In a state where an external force is not applied to the rotational body  112 , the detector  112 B is placed so as to block an optical path that extends from the light emitter to the light receiver of the optical sensor  111 . 
     [Recording Section] 
     The recording section  24  is disposed above the sheet feed cassette  78 . As shown in  FIGS. 2 and 3 , the recording section  24  includes a carriage  31  that is mounted with a recording head  30  and configured to reciprocate in a main scanning direction. To the recording head  30 , ink of each color of cyan (C), magenta (M), yellow (Y), and black (Bk) is supplied from an ink cartridge (not shown) through an ink tube  33 . The head carriage  31  reciprocates along guide rails  35  and  36  extending in the main scanning direction. Thereby, the recording head  30  is scanned relative to a recording sheet, so as to record an image on the recording sheet that is conveyed on a platen  34  disposed under the recording section  24 . 
     As illustrated in  FIG. 2 , the recording head  30  is exposed to face down at a lower side of the carriage  31 . The recording head  30 A includes a plurality of nozzles (not shown) disposed on a nozzle surface  48  thereof. Each of the nozzles is provided for a corresponding one of the ink colors C, M, Y, and Bk. A micro-drop of ink of a corresponding color is discharged from each nozzle. There are four exhaust holes (not shown), each of which is provided on a left or right side of the nozzles for a separate one of the ink colors C, M, Y, and Bk. Each exhaust hole communicates with an air bubble storage room (not shown) provided inside the recording head  30 . 
     Between a terminal end of the curved path  65 A and the recording section  24 , the first feed roller  60  and the pinch roller  61  are disposed to be paired. The pinch roller  61  is disposed beneath the first feed roller  60 . The pinch roller  61  is urged by an elastic member such as a spring (not shown) to come into pressure-contact with a roller surface of the first feed roller  60 . The first feed roller  60  and the pinch roller  61  pinch a recording sheet carried on the curved path  65 A and the conveying path  65 B while feeding the recording sheet onto the platen  34 . Further, between the recording section  24  and a start end of the sheet ejecting path  65 C, the second feed roller  62  and a spur roller  63  are disposed to be paired. The second feed roller  62  and the spur roller  63  pinch a recording sheet with an image recorded thereon while feeding the recording sheet downstream in the feeding direction (toward the catch tray  79 ). 
     The first feed roller  60  and the second feed roller  62  are driven to rotate when a driving force is transmitted thereto by a feed motor  76  (see  FIG. 8 ) via a transmission mechanism  500  (see  FIG. 8 ). The first feed roller  60  and the second feed roller  62  are intermittently driven in an image recording operation. Therefore, the image recording operation is performed while a recording sheet is being conveyed by predetermined linefeed widths. 
     [Transmission Mechanism] 
     The transmission mechanism  500  is provided with a planet gear and configured to transmit, to a below-mentioned pump  54 , a rotational driving force of the feed motor  76  rotating in a first one of forward and backward directions. Further, the transmission mechanism  500  is configured to transmit, to a below-mentioned port switching mechanism  59 , a rotational driving force of the feed motor  76  rotating in a second one of the forward and backward directions. It is noted that the first feed roller  60  and the second feed roller  62  are rotated by the feed motor  76 , which is rotating in the first one of the forward and backward directions, in such a direction as to feed a recording sheet downstream in the feeding direction. Further, the first feed roller  60  and the second feed roller  62  are rotated by the feed motor  76 , which is rotating in the second one of the forward and backward directions, in such a direction as to feed a recording sheet upstream in the feeding direction. 
     [Maintenance Unit] 
     As shown in  FIG. 3 , a maintenance unit  80  is disposed in an area on a right side of the platen  34  in the left-to-right direction  9 , which area a recording sheet does not pass through. As depicted in  FIG. 4 , the maintenance unit  80  includes a purge mechanism  44  and a waste liquid tank  81 . It is noted that the waste liquid tank  81  is not shown in  FIG. 3  as being disposed under the guide rail  36 . 
     The purge mechanism  44  is configured to suck and remove air bubbles and foreign material from the nozzles of the recording head  30 . As shown in  FIGS. 4 ,  5 A, and  5 B, the purge mechanism  44  includes a cap  46  that covers the nozzles of the recording head  30 , an exhaust cap  53  that covers the exhaust holes of the recording head  30 , a pump  54  that is connected with the cap  46  or the exhaust cap  53  and configured to perform a suction operation, a lift-up mechanism  55  (see  FIGS. 5A and 5B ) that moves the cap  46  and the exhaust cap  53  into contact with or apart from the recording head  30 , and a pump tube  82  that connects the pump  54  with the waste liquid tank  81 . 
     The cap  46  is formed from rubber. The cap  46  is brought into close contact with the nozzle surface (see  FIG. 2 ) by the lift-up mechanism  55 , forms a space between the nozzle surface  48  and the cap  46 , and surrounds the nozzles. Inside the cap  46 , there are two spaces sectioned separately for color-ink (C, M, and Y) nozzles and the black-ink ( 3   k ) nozzle. Namely, one of the spaces is formed between the cap  46  and a part of the nozzle surface  48  corresponding to the color-ink nozzles while the other thereof is formed between the cap  46  and a part of the nozzle surface  48  corresponding to the black-ink nozzle. An intake hole (not shown) is formed at a bottom of each space of the cap  46 , and each intake hole is connected with the pump  54  via the port switching mechanism  59 . It is noted that the port switching mechanism  59  will be described below. 
     The exhaust cap  53  is formed from rubber. The exhaust cap  53  is configured to contact closely with the nozzle surface  48  (see  FIG. 2 ) and surround the exhaust holes of the recording head  30 . Inside the exhaust cap  53 , there are four pushrods  50  provided to stand upward in the vertical direction, which pushrods correspond separately to the ink colors C, M, Y, and Bk. When the pushrods  50  are inserted into the exhaust holes, respectively, a return check valve provided to each exhaust hole is released. An intake hole (not shown) is formed at a bottom of the exhaust cap  53 , and connected with the pump  54  via the port switching mechanism  59 . 
     The pump  54  is a rotary tube pump. In the embodiment, the pump  54  includes a casing having an inner wall surface, and a roller configured to move while rotating along the inner wall surface. The pump tube  82  is disposed between the roller and the inner wall surface. When the roller is driven, the pump tube  82  is compressed such that ink inside the pump tube  82  is pushed out from an upstream side (the cap  46  and the intake hole) to a downstream side (the waste liquid tank  81 ). 
     As illustrated in  FIG. 5A , the lift-up mechanism  55  includes a pair of isometric links  64  disposed at each side thereof in the left-to-right direction. When the isometric links  64  are turned, a holder  90  is translated between a waiting position and a close-contact position. In  FIG. 5A , the holder  90  is in the waiting position. Meanwhile, in  FIG. 5B , the holder  90  is in the close-contact position. The holder  90  includes a contact lever  91  configured to protrude upward in the vertical direction. When the carriage  31  pushes the contact lever  91  rightward in  FIGS. 5A and 5B , the holder  90  is moved to the close-contact position. The cap  46  and the exhaust cap  53  are mounted on the holder  90 . When the holder  90  is moved to the close-contact position, the cap  46  and the exhaust cap  53  are brought into close contact with circumferences of the nozzles of the recording head  30  and circumferences of the exhaust holes of the recording head  30 , respectively (a first position). Meanwhile, when the holder  90  is moved to the waiting position, the cap  46  and the exhaust cap  53  are taken away from the recording head  30  (a second position). It is noted that the carriage  31  is moved by a motor (e.g., a carriage (CR) driving motor  311 , see  FIG. 8 ). Further, the cap  46  may be moved by any mechanism other than the lift-up mechanism  55  as far as the cap  46  can be moved between the first position and the second position. 
     Near the cap  46 , a position detector  461  (see  FIG. 8 ) is disposed to detect the position of the cap  46 . For instance, the position detector  461  may include a slider configured to slide up and down depending on the position of the cap  46 , and an optical sensor such as a photo-interrupter having a light emitter (e.g., a light emitting diode) and a light receiver (e.g., a phototransistor). When the cap  46  is in the first position, the slider is located to block an optical path extending from the light emitter to the light receiver. Namely, based on whether the optical path is blocked or not, the position of the cap  46  can be detected. 
     [Port Switching Mechanism] 
     The port switching mechanism  59  (see  FIGS. 5 and 6 ) is configured to switch a state established between the cap  46  (the exhaust cap  53 ) and the pump  54 , between a connected state and an unconnected state. As depicted in  FIGS. 6 and 7 , the port switching mechanism  59  includes a cover  99  having six pots  93  to  98 , and a disk-shaped switching member  92  disposed inside the cover  99 . The switching member  92  is rotated by the feed motor (see  FIG. 8 ) to control connection among the ports  93  to  98  as described later. The cover  99  is made of resin and formed in a shape of a cylinder having a bottom wall. The cover  99  has the inlet port  93  formed at the center of the bottom wall of the cover  99 . The inlet port  93  is connected with the pump tube  82 . The pump tube  82  is connected with a tube joint  105  of the waste liquid tank  81  via the pump  54  and a tube joint  82 A. 
     The other five ports  94  to  98  are disposed circumferentially on a side wall of the cover  99  at intervals of a predetermined distance. The exhaust port  94  communicates with the exhaust cap  53  (see  FIG. 4 ) via a tube  100 . The Bk port  95  communicates with the cap  46  (see  FIG. 4 ) via a tube  101 . Specifically, the Bk port  95  communicates with the space for the black-ink nozzle that is formed between the cap  46  and the nozzle surface  48 . The Co port  96  communicates with the cap  46  (see  FIG. 4 ) via a tube  102 . Specifically, the Co port  96  communicates with the space for the color-ink nozzles that is formed between the cap  46  and the nozzle surface  48 . The air ports  97  and  98  are open to atmospheric air. 
     Ink, which is sucked by the maintenance unit  80  from the recording head  30 , is conveyed to the waste liquid tank  81  in accordance with the following procedure. Hereinafter, an explanation will be provided about the procedure of an ink suction process with reference to  FIG. 7 . 
     When the carriage  31  is moved in a sliding manner and thereby the contact lever  91  is pressed rightward, the holder  90  is moved to the close-contact position. Namely, the cap  46  is brought into close contact with the nozzle surface  48  by the lift-up mechanism  55 . The switching member  92  is driven, and the inlet port  93  is connected with none of the other ports  94  to  98  (see  FIG. 7A ). In other words, the space formed between the cap  46  and the nozzle surface  48  is cut off from the atmospheric air and does not communicate with the pump  54  (a second state). In this state, the pump  54  is driven, and the inside of the pump tube  82  is depressurized. The switching member  92  is driven, and the inlet port  93  comes to communicate with the Bk port  95  (see  FIG. 7B ). Namely, the portion, of the space formed between the cap  46  and the nozzle surface  48 , which corresponds to the black-ink nozzle, is connected to the pump  54  (a first state). Consequently, black ink, which is stored in the portion of the space formed between the cap  46  and the nozzle surface  48  that corresponds to the black-ink nozzle, is sucked at a burst toward the pump  54 . The sucked ink is stored into the waste liquid tank  81  via the tube pump  82 . 
     The switching member  92  is driven, and the inlet port  93  comes to communicate with none of the other ports  94  to  98  (see  FIG. 7C ). Namely, the space formed between the cap  46  and the nozzle surface  48  is cut off from the atmospheric air, and does not communicate with the pump  54  (the second state). In this state, the pump  54  is driven, and the inside of the pump tube  82  is depressurized. The switching member  92  is driven, and the inlet port  93  comes to communicate with the Co port  96  (see  FIG. 7D ). Namely, the portion, of the space formed between the cap  46  and the nozzle surface  48 , which corresponds to the color-ink nozzles, is connected with the pump  54  (the first state). Consequently, color ink, which is stored in the portion of the space formed between the cap  46  and the nozzle surface  48  that corresponds to the color-ink nozzles, is sucked at a burst toward the pump  54 . The sucked ink is stored into the waste liquid tank  81  via the tube pump  82 . Thereafter, when the carriage  31  is set apart from the contact lever  91  in a sliding manner, the cap is restored to the second position by the lift-up mechanism  55 . 
     As indicated by a dashed line in  FIG. 7A , above or under the switching member  92 , a rotational body  92 A configured to rotate integrally with the switching member  92  is provided. The rotational body  92 A includes protruding sections  92 B,  92 C, and  92 D that protrude outward in a radial direction. The protruding sections  92 B,  92 C, and  92 D are disposed in respective positions of different phases in a rotational direction of the rotational body  92 A. The protruding sections  92 B,  92 C, and  92 D are placed to be apart from each other by a predetermined rotation angle. Further, a sensor  92 E is disposed to face an outer circumference of the rotational body  92 A. When facing one of the protruding sections  92 B,  92 C, and  92 D, the sensor  92 E outputs an electric signal “ON.” When not facing any of the protruding sections  92 B,  92 C, and  92 D, the sensor  92 E outputs an electric signal “OFF.” Based on a periodical change of the output (ON/OFF) from the sensor  92 E, it is possible to grasp a rotational phase of the switching member  92 . 
     [Controller] 
     Hereinafter, referring to  FIG. 8 , a configuration of a controller  130  of the MFP  10  will be described. When the controller  130  takes nip control in accordance with a below-mentioned flowchart, the controller  130  can establish a control mechanism according to aspects of the present invention. 
     The controller  130  is adapted to control overall operations of the MFP  10 . The controller  130  is configured as a microcomputer that includes a CPU  131 , a ROM  132 , a RAM  133 , an EEPROM  134 , and an ASIC  135 . The CPU  131 , the ROM  132 , the RAM  133 , the EEPROM  134 , and the ASIC  135  are interconnected via an internal bus. 
     The ROM  132  stores programs for the CPU  131  to control various operations of the MFP  10  and a program for executing a below-mentioned state determining process. The RAM  133  is employed as a storage area for temporarily storing data or signals used for the CPU  131  to execute the aforementioned programs, or as a work area for data processing by the CPU  131 . The EEPROM  134  stores settings and flags that are to be held even after the MFP  10  is powered off. 
     The ASIC  135  is connected with various elements such as the optical sensor  111  and the feed motor  76 . The ASIC  135  has a drive circuit incorporated therein, which is configured to control the feed motor  76 . When a driving signal for rotating the feed motor  76  is transmitted by the CPU  131  to the drive circuit, a drive current responsive to the drive signal is transmitted by the drive circuit to the feed motor  76 . Thereby, the feed motor  76  is rotated at a predetermined rotational speed in one of a forward direction and a backward direction. By the rotation of the feed motor  76 , the switching member  92 , the first feed roller  60 , and the second feed roller  62  are rotated. 
     The optical sensor  111  outputs an analog electric signal (an electric voltage signal or an electric current signal) responsive to an intensity of light received by the light receiver. The output signal is transmitted to the controller  130 , and the controller  130  determines whether an electric level (an electric voltage value or an electric current value) of the signal is equal to or higher than a predetermined threshold. When the signal is equal to or higher than the predetermined threshold, the signal is determined as a HIGH-level signal. When the signal is lower than the predetermined threshold, the signal is determined as a LOW-level signal. 
     [Nip Control Process] 
     In the printing unit  11  configured as above, the controller  130  performs a nip control process to nip a recording sheet, which is in contact with the nipping point  60 A, between the first feed roller  60  and the pinch roller  61 . Hereinafter, referring to a flowchart shown in  FIG. 9 , the procedure of the nip control process will be described. The nip control process is performed, e.g., when the registration sensor  110  detects a recording sheet in a standby state where the pickup roller  25  or the first feed roller  60  is not driven (the controller  130  does not issue a sheet feeding command to feed a recording sheet from the sheet feed cassette  78  or a print command). In the following description, for the sake of simpler explanation, it is assumed that when the feed motor  76  is rotated in the forward direction, a recording sheet is fed downstream in the feeding direction, and the purge mechanism  44  sucks ink from the nozzles of the recording head  30 . Further, it is assumed that when the feed motor  76  is rotated in the backward direction, a recording sheet is fed upstream in the feeding direction. and the port switching mechanism  59  sets the cap  46  and the pump  54  to the connected state or the unconnected state. 
     In the standby state, when the user of the MFP  10  places a recording sheet on the manual sheet feed tray while inserting the recording sheet until the recording sheet contacts the nipping point  60 A, a leading end of the recording sheet is detected by the registration sensor  110  (S 10 ). 
     After a leading end of the recording sheet is detected by the registration sensor  110  in S 10 , the controller  130  waits for a predetermined time period (e.g., two seconds) before performing a subsequent step (S 20 ). Thereafter, when determining that the MFP  10  has a skew correction function for correcting skew of the recording sheet (S 30 : Yes), the controller  130  performs skew correction for the recording sheet inserted (S 40 ). Specifically, the controller  130  controls the feed motor  76  to rotate in the backward direction by a predetermined phase such that the recording sheet, which is inserted to contact the nipping point  60 A with a skew angle, recedes from the nipping point  60 A. Thereafter, the recording sheet contacts the nipping point  60 A in a state where the skew angle is corrected owing to the weight of the recording sheet. 
     Further, when the feed motor  76  is rotated in the backward direction, the port switching mechanism  59  is driven. When the port switching mechanism  59  is driven, the inlet port  93  is set to a state where the inlet port  93  does not communicate with any of the other ports  94  to  98  (S 50 ). 
     When determining in S 30  that the MFP  10  does not have a skew correction function for correcting skew of the recording sheet (S 30 : No), the controller  130  determines whether the switching member  92  of the port switching mechanism  59  is in the second state, through detection using the rotational body  92 A and the sensor  92 E (S 60 ). When determining that the switching member  92  is not in the second state (S 60 : No), the controller  130  determines whether the cap  46  is in the second position where the cap  46  is apart from the recording head  30 , through detection using the position detector  461  (S 70 ). When determining that the cap  46  is not in the second position (S 70 : No), the controller  130  sets the port switching mechanism  59  to the second state (S 50 ). 
     When determining that the switching member  92  is in the second state (S 60 : Yes) or that the cap  46  is in the second position (S 70 : Yes), or after setting the port switching mechanism  59  to the second state (S 50 ), the controller  130  performs a nipping operation (S 80 ). Specifically, the controller  130  controls the feed motor  76  to rotate in the forward direction by a predetermined phase, such that the recording sheet, which contacts the nipping point  60 A, is nipped between the first feed roller  60  and the pinch roller  61  by an amount corresponding to the rotation of the feed roller  76  in the forward direction. 
     After that, the controller  130  informs the user of information that the recording sheet placed on the manual sheet feeding tray  20  is normally nipped, i.e., normally fed (S 90 ). For instance, a message about the information is displayed on the LCD unit of the operation panel  121 . 
     [Effects] 
     The recording sheet placed on the manual sheet feed tray  20  is detected by the registration sensor  110 . When confirming the detection, the controller  130  drives the feed motor  76  to rotate in the second one of the forward direction and the backward direction, such that the port switching mechanism  59  is switched to the second state (where the inlet port  93  does not communicate with any of the other ports  94  to  98 ). Thereafter, the controller  130  drives the feed motor  76  to rotate in the first one of the forward direction and the backward direction, such that the pump  54  is driven. Even though the pump  54  is driven, since the inlet port  76  does not communicate with any of the other ports  94  to  98 , the pump  54  cannot suck any ink. Meanwhile, the first feed roller  60  and the pinch roller  61  are driven by the driving force transmitted by the feed motor  76  rotating in the first one of the forward direction and the backward direction, so as to nip the recording sheet (in contact with the nipping point  60 A between the first feed roller  60  and the pinch roller  61 ) between the first feed roller  60  and the pinch roller  61 . 
     When the cap  46  is in the first position, the nozzles are covered and sealed by the cap  46 . Therefore, when the pump  54  is driven, ink is sucked. Meanwhile, when the cap  46  is in the second position, the nozzles are not sealed. Therefore, even when the pump  54  is driven, ink is not sucked. Accordingly, the controller  130  switches the state of the port switching mechanism  59  when the cap  46  is in the first position. 
     In the case where the port switching mechanism  59  is in the first position when the driving force is transmitted by the feed motor  76  to the pump  54 , ink is sucked from the nozzles as the cap  46  communicates with the pump  54 . Meanwhile, in the case where the port switching mechanism  59  is in the second position when the driving force is transmitted by the feed motor  76  to the pump  54 , ink is not sucked from the nozzles as the cap  46  does not communicate with the pump  54 . 
     When the recording sheet placed on the manual sheet feed tray  20  is detected by the registration sensor  110 , and the cap  46  is in the first position, the controller  130  drives the feed motor  76  to rotate in the second one of the forward direction and the backward direction, such that the port switching mechanism  59  is switched to the second state. Thereafter, the controller  130  drives the feed motor  76  to rotate in the first one of the forward direction and the backward direction. However, since the port switching mechanism  59  is switched to the second state, ink is not sucked from the recording head  30 . Meanwhile, the first feed roller  60  and the pinch roller  61  are driven by the driving force transmitted by the feed motor  76  rotating in the first one of the forward direction and the backward direction, so as to nip the recording sheet (in contact with the nipping point  60 A between the first feed roller  60  and the pinch roller  61 ) between the first feed roller  60  and the pinch roller  61 . According to the aforementioned configuration, it is possible to nip the recording sheet between the first feed roller  60  and the pinch roller  61  while preventing ink from being wastefully consumed. 
     When detecting that the port switching mechanism  59  is in the second state, using the rotational body  92 A and the sensor  92 E, the controller  130  does not drive the feed motor  76  to switch the port switching mechanism  59  from the first state to the second state. Namely, the controller  130  drives the feed roller  76  to rotate in the first one of the forward and backward directions without rotating the feed roller  76  in the second one of the forward and backward directions. Hence, it is possible to expedite an operation of nipping the recording sheet between the first feed roller  60  and the pinch roller  61 . 
     When the position detector  461  detects that the cap  46  is in the second position, the cap  46  is apart from the recording head  30 . Therefore, even though the pump  54  is driven when the port switching mechanism  59  is in the first state, ink is not sucked from the nozzles. Namely, even though the port switching mechanism  59  is not switched to the second state, it is possible to avoid wasteful consumption of ink. Thus, the controller  130  does not drive the feed motor  76  to switch the port switching mechanism  59  to the second state. In other words, the controller  130  drive the feed motor  76  to rotate in the first one of the forward and backward directions without rotating the feed motor  76  in the second one of the forward and backward directions. Accordingly, it is possible to expedite an operation of nipping the recording sheet between the first feed roller  60  and the pinch roller  61 . 
     Hereinabove, the embodiment according to aspects of the present invention has been described. The present invention can be practiced by employing conventional materials, methodology and equipment. Accordingly, the details of such materials, equipment and methodology are not set forth herein in detail. In the previous descriptions, numerous specific details are set forth, such as specific materials, structures, chemicals, processes, etc., in order to provide a thorough understanding of the present invention. However, it should be recognized that the present invention can be practiced without reapportioning to the details specifically set forth. In other instances, well known processing structures have not been described in detail, in order not to unnecessarily obscure the present invention. 
     Only an exemplary embodiment of the present invention and but a few examples of their versatility are shown and described in the present disclosure. It is to be understood that the present invention is capable of use in various other combinations and environments and is capable of changes or modifications within the scope of the inventive concept as expressed herein. For example, the following modifications are possible. 
     In the aforementioned embodiment, the transmission mechanism  500  is configured to transmit a driving force to the pump  54  and the port switching mechanism  59  (see  FIG. 8 ). However, the transmission mechanism  500  may be configured to transmit a driving force to the pickup roller  25  and the pickup arm  26 . 
     In this modification, the driving force of the feed motor  76  is transmitted to the pickup arm  26 . The pickup arm  26  is rotated around the rotation shaft  28  by a rotational driving force that is transmitted by the feed motor  76  rotating in the second one of the forward and backward directions. Consequently, the pickup arm  26  is switched between a first state where the pickup roller  25  contacts a recording sheet placed in the sheet feed cassette  78  and a second state where the pickup roller  25  is apart from the recording sheet. 
     Further, an arm state detector (not shown) configured to detect the state of the pickup arm  26  may be provided. The arm state detector may be configured in the same manner as the aforementioned position detector  461 . In the aforementioned embodiment, the sensor  92 E detects whether the port switching mechanism  59  is in the second state. However, in the modification, the arm state detector may detect whether the pickup arm  26  is in the second state. Namely, the arm state detector of the modification may serve as the sensor  92 E of the aforementioned embodiment. 
     In the printing unit  11  of the modification, the controller  130  may perform a nip control process in accordance with a procedure as shown in  FIG. 10 . Hereinafter, referring to  FIG. 10 , the nip control process of the modification will be described. It is noted that explanations about the same steps as shown in  FIG. 9  will be omitted. 
     Operations executed in steps S 210  to S 250  are the same as those in the steps S 10  to S 50 . In S 230 , when the MFP  10  does not have a skew correction function for correcting skew of a recording sheet (S 230 : No), the controller  130  determines whether the pickup arm  26  is in the second state, through detection using the arm state detector (S 260 ). When determining that the pickup arm  26  is not in the second state (S 260 : No), the controller  130  sets the pickup arm  26  to the second state (S 250 ). When determining that the pickup arm  26  is in the second state (S 260 : Yes), or after setting the pickup arm  26  to the second state (S 250 ), the controller  130  performs a nipping operation (S 280 ). Operations executed in S 280  and S 290  are the same as those in S 80  and S 90  as shown in  FIG. 9 . 
     Even though the feed motor  76  is driven to rotate in the first one of the forward and backward directions, when the pickup arm  26  is switched to the second state, the pickup roller  25  is apart from the recording sheet placed in the sheet feed cassette  78 . Therefore, the recording sheet is not conveyed from the sheet feed cassette  78 . Meanwhile, the first feed roller  60  and the pinch roller  61  are driven by a driving force that is transmitted by the feed motor  76  rotating in the first one of the forward and backward directions, so as to nip a recording sheet (in contact with the nipping point  60 A between the first feed roller  60  and the pinch roller  61 ) between the first feed roller  60  and the pinch roller  61 . Thus, it is possible to nip the recording sheet between the first feed roller  60  and the pinch roller  61  while preventing a recording sheet from being wrongly fed from the sheet feed cassette  78 . 
     Further, the same registration sensor  110  performs an operation of detecting a recording sheet placed on the manual sheet feed tray  20  that contacts the nipping point  60 A between the first feed roller  60  and the pinch roller  61  and an operation of detecting a recording sheet placed in the sheet feed cassette  78  that is brought by the pickup roller  25  into contact with the nipping point  60 A. Therefore, it is possible to decrease the number of detectors for detecting a recording sheet (e.g., the registration sensor  110 ) that are provided to the MFP  10 .