Abstract:
A printer has a carriage being movable between a first end and a second end of a reciprocating path; and a driving force transmitting path selecting mechanism provided at the second end of the reciprocating path. The selecting mechanism has: a common driving force outputting member; a plurality of force receiving members; a selecting member; and a position retainer for keeping the position of the selecting member. The selecting member connects the force outputting member to one of the plurality of force receiving members, and moves in association with the carriage when the carriage moves in a vicinity of the second end in a first direction extending from the first end to the second end. The position retainer keeps the position of the selecting member when the carriage moves in a second direction extending from the second end to the first end. The force receiving member connected to the force outputting member via the selecting member is selected in accordance with a movement of the carriage along the reciprocating path.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims priority to Japanese Patent Applications No. 2005-252136 filed on Aug. 31, 2005, No. 2005-285287 filed on Sep. 29, 2005, and No. 2005-286155 filed on Sep. 30, 2005, and the contents of them are hereby incorporated by reference into the present application. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a printer for printing on a sheet. The printer of the present invention is generic name of a device comprising: a sheet sending mechanism which successively sends cut sheets; and a printing mechanism which successively prints characters, graphics, photographic images or the like on the sheets sent by the sheet sending mechanism. Not only a printer with a single function, but also a copying device, a facsimile device, a composite device (or a multifunction device) and the like comprising the sheet sending mechanism and printing mechanism also are the printer described herein. 
         [0004]    In one type of printer of the present invention, a sheet sending mechanism is operated in a plurality of operation modes. In order to operate the sheet sending mechanism in the plurality of operation modes, the printer of the present invention comprises a plurality of force transmitting paths and a selecting mechanism for activating any of the force transmitting paths. 
         [0005]    Other type of the printer of the present invention comprises a plurality of sheet sending mechanisms. In order to operate the plurality of sheet sending mechanisms, the printer of the present invention comprises a plurality of force transmitting paths and a selecting mechanism for activating any of the force transmitting paths. 
         [0006]    Yet further type of the printer of the present invention comprises a maintaining mechanism for a printing head. In order to operate the maintaining mechanism and the sheet sending mechanism, the printer of the present invention comprises a plurality of force transmitting paths and a selecting mechanism for activating any of the force transmitting paths. 
         [0007]    2. Description of the Related Art 
         [0008]    There has been conventionally known printers with single function which can print on a plurality of sizes of sheets, and printers such as copying machines, facsimile devices, composite devices, and the like. These types of printers use a plurality of cassettes that store a plurality of sheets having the same size in a stacked manner. The sizes of the sheets stored in each cassette are different from one another. The plurality of cassettes are stored in the printer in a stacked manner. A cassette is selected in accordance with a command for designating the size of the sheet or an image command. The uppermost sheet of the sheets stacked in a selected cassette is sent by a supply roller. The sheet which is sent from the cassette is conveyed toward a printing region secured in a lower section of a printing head via a conveying path. This type of printer comprises a plurality of sheet sending mechanisms. 
         [0009]    As disclosed in Japanese Patent Application Laid-Open Publication No. H8-174958 or Japanese Patent Application Laid-Open Publication No. 2003-89244, there is known a printer which comprises an ink-jet type printing head for printing a graphic pattern configured with dot patterns. In the ink-jet type printing head, ejection failure of the inks occurs due to the structure of the printing head, thus the ink-jet type printing head is provided with a maintaining mechanism in the printer in order to cope with such ink ejection failure. The printing head is moved to a position facing the maintaining mechanism, and the printing head is treated by the maintaining mechanism at this position. This type of printer comprises the maintaining mechanism and the sheet sending mechanism. 
         [0010]    Among printers, there is a printer which can switch between a mode for continuously and successively sending sheets from a cassette and a mode for intermittently sending sheets from a cassette. This type of printer comprises a plurality of driving force transmitting paths in order to operate the sheet sending mechanism using a plurality of operation modes. 
         [0011]    A driving force needs to be transmitted to the sheet sending mechanism or maintaining mechanism. 
         [0012]    The printer disclosed in Japanese Patent Application Laid-Open Publication No. H8-174958 employs a structure of moving a kick member by using a movement of a carriage which moves the printing head. By means of a movement of the kick member, switching is made between a state in which an idle gear is engaged with a gear driving the maintaining mechanism, and a state in which the idle gear is engaged with a gear driving a sheet sending roller. In the printer disclosed in Japanese Patent Application Laid-Open Publication No. H8-174958, when the carriage is separated from a purge position, the idle gear is engaged with the gear driving the maintaining mechanism. When the carriage is at the purge position, the idle gear is engaged with the purge gear. 
         [0013]    The printer disclosed in Japanese Patent Application Laid-Open Publication No. 2003-89244 comprises: a supply gear which rotates a supply gear sending one sheet from a plurality of stacked sheets; a feed gear which rotates a feed-in roller sending a sheet to a printing region and a feed-out roller drawing the sheet from the printing region; a maintenance gear which drives a maintaining mechanism; and a drive motor. Also, there is provided a slider which moves after the carriage moves so that power is transmitted to any of the supply gear, feed gear, and maintenance gear from the drive motor. The slider comprises a switching gear. When the slider slides, the switching gear is engaged with any one of the supply gear, feed gear, and maintenance gear. 
         [0014]    In this printer, if the carriage is positioned within a width of a sheet, the switching gear and supply gear are engaged with the feed gear. When the printer executes a maintenance work, the carriage is moved to a maintenance position. Accordingly, the switching gear is engaged with the maintenance gear. When the printer discharges the last page of the sheets, the carriage is moved to an intermediate position between the abovementioned two positions. Accordingly, the switching gear is engaged with the feed gear. 
       BRIEF SUMMARY OF THE INVENTION  
       [0015]    However, in the conventional configuration, the position of the idle gear or switching gear changes in conjunction with the position of the carriage. In other words, the position of the carriage determines the position of the idle gear or switching gear. Therefore, the carriage has to be moved every time when executing a processing of sending a sheet from the cassette or a process of conveying the sheet which is sent from the cassette, requiring time for moving the carriage and excessive time for making a connection (engagement) between the gears. Therefore, there is a problem that continuous printing cannot be performed promptly and efficiently. 
         [0016]    Further, the conventional configuration cannot respond to a printer comprising a plurality of cassettes and a plurality of sheet sending mechanisms. 
         [0017]    The present invention is to solve the abovementioned problems. 
         [0018]    An object of the present invention is to realize a structure capable of switching a power transmitting path by moving a carriage. 
         [0019]    Other object of the present invention is to provide a printer in which, by switching a power transmitting path by means of a movement of the carriage, thereafter the switched power transmitting path can be maintained even when the carriage is separated from its position, and the carriage can be moved for an original purpose. 
         [0020]    Yet another object of the present invention is to provide a printer which can response to a case in which a plurality of cassettes are disposed to configure a plurality of steps. 
         [0021]    A printer of the invention comprises a printing head and a carriage. The printing head is mounted on the carriage, and the carriage is movable between a first end and a second end of a reciprocating path. The reciprocating path extends along a width direction of a sheet to be printed. 
         [0022]    The printer of the invention also has a driving force transmitting path selecting mechanism. This mechanism is provided at the second end of the reciprocating path. 
         [0023]    The selecting mechanism comprises a common driving force outputting member, a plurality of force receiving members, and a selecting member for connecting the force outputting member to one of the plurality of force receiving members via the selecting member. The selecting member moves in association with the carriage when the carriage moves in a vicinity of the second end in a first direction extending from the first end to the second end. The selecting mechanism also has a position retainer that keeps the position of the selecting member when the carriage moves in a second direction extending from the second end to the first end. The force receiving member connected to the force outputting member via the selecting member is selected in accordance with a movement of the carriage along the reciprocating path. 
         [0024]    According to this printer, the carriage is moved in the first direction in order to change the position of the selecting member. Once the selecting member is positioned to a desired position so that the desired force receiving member is connected to the force outputting member, then the carriage may be moved in the second direction. Because the position retainer keeps the position of the selecting member when the carriage moves in the second direction, the selected force receiving member continues to be connected to the force outputting member. Once the selection is completed, then the carriage can move freely for its own purpose of printing on sheet. 
         [0025]    According to this printer, the force receiving member connected to the force outputting member is determined by a nearest position to the second end during the reciprocating movement of the carriage. For instance, in case that a first point is the first point from the second end, a second point is the second point from the second end, the force receiving member corresponding to the first point is selected by moving the carriage in the first direction up to the first point and then moving in the second direction. On the other hand, the force receiving member corresponding to the second point is selected by moving the carriage in the first direction up to the second point and then moving in the second direction. 
         [0026]    According to this printer, since the selection is maintained even the carriage is moved to a far position from the second end, the carriage may stay in a printing region (region of opposing the sheet) for printing. The occasion for the carriage to travel to the vicinity of the second end for changing the selection may be reduced. Waste of time for changing the selection of driving force transmitting path is prevented. 
         [0027]    It is preferred that the printer have a sheet sending mechanism for sending the sheet to be printed from a cassette to a printing region; and a maintaining mechanism for maintaining the printing head. In this case, it is preferred that one of the force receiving members activate the sheet sending mechanism and the other of the force receiving members activate the maintaining mechanism. 
         [0028]    According to this printer, once the force receiving member for activating the sheet sending mechanism is selected, then the carriage may be moved to the printing region (region of opposing the sheet) for printing. The carriage may stay in the printing region until the maintaining operation becomes necessary. 
         [0029]    It is also preferred that the printer have a first sheet sending mechanism for sending the sheet to be printed from a first cassette to a printing region, a second sheet sending mechanism for sending the sheet to be printed from a second cassette to the printing region, and a maintaining mechanism for maintaining the printing head. In this case, it is preferred that first force receiving member activate the first sheet sending mechanism, second force receiving member activate the second sheet sending mechanism, and third force receiving members activate the maintaining mechanism. 
         [0030]    It is also preferred that the printer have a first-first sheet sending mechanism for sending the sheet to be printed from a first cassette to a printing region intermittently, a first-second sheet sending mechanism for sending the sheet to be printed from the first cassette to the printing region sequentially, a second sheet sending mechanism for sending the sheet to be printed from a second cassette to the printing region, and a maintaining mechanism for maintaining the printing head. In this case, it is preferred that first-first force receiving member activate the first-first sheet sending mechanism, first-second force receiving member activate the first-second sheet sending mechanism, second force receiving member activate the second sheet sending mechanism, and third force receiving members activate the maintaining mechanism. 
         [0031]    According to this printer, the sheet is sent to the printing region from the first cassette by two ways. When the first-first sending mechanism is selected and activated, the sheet sent from the first cassette is aligned to a predetermined position, and the sheet is send to the printing region from the aligned position. According to this way of sending the sheet, the relation between the position of the sheet and timing of the printing head operation is adjusted to a predetermined relation, therefore intended graphic pattern can be printed at intended position of the sheet. When the first-second sending mechanism is selected and activated, pieces of sheets are continuously sent out from the first cassette. According to this way of sending the sheet, continuous printing operation becomes possible for multiple sheets; therefore printing operation for multiple sheets can be completed quickly. 
         [0032]    The common force outputting member may be a spur gear. The selecting member may be also a spur gear that is in mesh with the spur gear forming the common force outputting member. Each of the force receiving members may also be a spur gear. In this case, it is preferred that spur gears forming the force receiving members be arranged along a line, and one of the spur gear forming the force receiving members is in mesh with the spur gear forming the selecting member. 
         [0033]    According to this structure, the driving force transmitting path selecting mechanism is simplified. 
         [0034]    The position retainer may have a first slider that moves in association with the carriage when the carriage moves in a vicinity of the second end. The first slider moves the selecting member when first slider moves in the first direction. The position retainer may also have a position retaining member that keeps the position of the first slider at a plurality positions. 
         [0035]    The first slider may have an arm that abuts the carriage and the position retaining member. 
         [0036]    The position retaining member may have a guide groove. The arm of the first slide member is inserted into the groove. 
         [0037]    The guide groove may have steps for engaging with the arm. 
         [0038]    The guide groove may have a lateral portion extending along the reciprocating path and an inclined portion inclined with respect to the reciprocating path. 
         [0039]    The guide groove may have a first wall and a second wall. In this case, the arm travels along the first wall when the carriage travels in the first direction, and the arm travels along the second wall when the carriage travels in the second direction. The first wall may have a step for retaining the position of the arm, and the second wall has no step for retaining the position of the arm. 
         [0040]    According to this guide groove, when the carriage is returned toward the first end while the carriage travels under the condition that the arm travels along the first wall, then the arm is engaged with a step formed on the first wall, and the force receiving member connected to the force outputting member is determined by a nearest position to the second end during the reciprocating movement of the carriage. When the carriage is moved up to the second end, then the arm is rotated and inserted into the lateral portion. When the carriage is returned toward the second end after the arm is inserted into the lateral portion, the arm travels along the second wall. Because, the second wall does not have a step, then the arm is returned to the step formed on the first wall which is nearest to the first end. Then the selection is cleared up, and new selection becomes possible. 
         [0041]    The selecting member and the first slider may be mounted to a common axis. It is preferred that the selecting member and the first slider can rotate and slide with respect to the axis independently. 
         [0042]    It is preferred that the carriage has a step for preventing the arm from rotating. 
         [0043]    It is preferred that the position retainer further comprise a second slider that applies a rotating force to the first slider such that the arm is biased against the first wall while the carriage moves in the first direction. 
         [0044]    It is preferred that the selecting member, the first slider and the second slider be mounted to a common axis, and the selecting member, the first slider and the second slider can slide with respect to the axis independently. 
         [0045]    It is preferred that the second slider be prohibited to rotate with respect to the axis. 
         [0046]    It is preferred that the position retaining member be fixed to a flame for guiding reciprocation of the carriage. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0047]      FIG. 1  is a perspective view showing the entirety of a multifunction device of a first embodiment; 
           [0048]      FIG. 2  is a perspective view in which a lower section case, excluding an upper section case, is viewed from the back; 
           [0049]      FIG. 3  is a top view of  FIG. 2 ; 
           [0050]      FIG. 4  is a cross-sectional view of a substantial part in which a paper cassette is installed in the multifunction device; 
           [0051]      FIG. 5  is a cross-sectional view showing an enlarged side view in the vicinity of a printing region; 
           [0052]      FIG. 6  is a side view of the paper cassette and a supply unit; 
           [0053]      FIG. 7  is a plan view of a cut-out section in which the paper cassette is installed in the multifunction device; 
           [0054]      FIG. 8  is a perspective view of a printing unit in which a guide plate and platen on a back side thereof are removed; 
           [0055]      FIG. 9  is a figure taken along the line IX-IX of  FIG. 7 ; 
           [0056]      FIG. 10  is a schematic diagram showing power transmission switching means; 
           [0057]      FIG. 11  is a front view showing a state in which modes are switched by the power transmission switching means; 
           [0058]      FIG. 12  is a plan view showing a state in which the modes are switched by the power transmission switching means; 
           [0059]      FIG. 13  is a figure showing power transmission in an intermittent feeding mode (first mode) when a sheet is fed; 
           [0060]      FIG. 14  is a figure showing power transmission in the intermittent feeding mode at the time of printing; 
           [0061]      FIG. 15  is a figure showing power transmission in a continuous feeding mode (second mode) when a sheet is fed; 
           [0062]      FIG. 16  is a figure showing power transmission in the continuous feeding mode at the time of printing; 
           [0063]      FIG. 17  is a figure showing power transmission in the continuous feeding mode when feeding a subsequent sheet P 1 ; 
           [0064]      FIG. 18  is a figure showing a first embodiment of a sheet-returning process in the continuous feeding mode; 
           [0065]      FIG. 19  is a figure showing a second embodiment of the sheet-returning process in the continuous feeding mode; 
           [0066]      FIG. 20  is a functional block diagram of a control unit; 
           [0067]      FIG. 21  is a flowchart for controlling the printing operation; 
           [0068]      FIG. 22  is a flowchart for controlling of returning a sheet in the continuous feeding mode; 
           [0069]      FIG. 23  is a perspective view of the entire multifunction device of a second embodiment; 
           [0070]      FIG. 24  is a cross-sectional view of a substantial part in which the paper cassette is installed in the multifunction device; 
           [0071]      FIG. 25  is a perspective view of the power transmission switching means and a power transmission mechanism for a second supply unit; 
           [0072]      FIG. 26  is a front view showing power transmission in the intermittent feeding mode (first mode) when a sheet is fed; 
           [0073]      FIG. 27  is a perspective view showing power transmission in the intermittent feeding mode (first mode) when a sheet is fed; 
           [0074]      FIG. 28  is a side view showing power transmission in the intermittent feeding mode (first mode) when a sheet is fed; 
           [0075]      FIG. 29  is a perspective view of a first slider (first block) and a second slider (second block); 
           [0076]      FIG. 30  is a perspective view in which the first block and the second block are combined; 
           [0077]      FIG. 31  is a front view in which the first block and the second block are shallowly geared with each other; 
           [0078]      FIG. 32  is a front view in which the first block and the second block are deeply geared with each other; 
           [0079]      FIG. 33  is a front view showing power transmission in the continuous feeding mode (second mode) when a sheet is fed; 
           [0080]      FIG. 34  is a perspective view showing power transmission in the continuous feeding mode (second mode) when a sheet is fed; 
           [0081]      FIG. 35  is a side view showing power transmission in the continuous feeding mode (second mode) when a sheet is fed; 
           [0082]      FIG. 36  is a front view showing power transmission in a state in which a sheet is supplied by the second supply unit; 
           [0083]      FIG. 37  is a perspective view showing power transmission in a state in which a sheet is supplied by the second supply unit; 
           [0084]      FIG. 38  is a side view showing power transmission in a state in which a sheet is supplied by the second supply unit; 
           [0085]      FIG. 39  is a front view showing power transmission in a maintenance operation mode; 
           [0086]      FIG. 40  is a perspective view showing power transmission in the maintenance operation mode; 
           [0087]      FIG. 41  is a side view showing power transmission in the maintenance operation mode; 
           [0088]      FIG. 42  is a schematic diagram showing the power transmission switching means; 
           [0089]      FIG. 43  is a front view schematically showing a state in which the modes are switched by the power transmission switching means; and 
           [0090]      FIG. 44  is a plan view showing a state in which the modes are switched by the power transmission switching means. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First Embodiment  
       [0091]    The first embodiment which crystallizes the present invention is described in detail with reference to the drawings.  FIG. 1  shows a perspective view showing an exterior of a multifunction device  1  which comprises a facsimile function, print function, copy function, and scanner function. The multifunction device.  1  comprises a sheet sending mechanism for sending a sheet and a printing mechanism for printing characters, graphics, photographic images or the like (generically referred to as “graphic pattern” hereinafter) on the sheet which is sent by the sheet sending mechanism, and provides the sheet printed with the graphic pattern to a user. 
         [0092]    The multifunction device  1  has a lower section case  2  and an upper section case  3 . The lower section case  2  is substantially in the form of a box in which an upper surface thereof is opened. The upper section case  3  is connected to a left side face of the lower section case  2  via a hinge (not shown), and can be rotated from the position thereof shown in  FIG. 1 , in a direction of the arrow  202  around a rotation axis  200 . When the upper section case  3  is rotated in the direction of the arrow  202 , the inside of the lower section case  2  can be viewed from the outside. The lower section case  2  and the upper section case  3  are injection-molded articles made of synthetic resin. 
         [0093]    It should be noted that in the following description art X-direction in  FIG. 1  is referred to as “front-and-back direction”, a Y-direction is referred to as “horizontal direction”, and a Z-direction is referred to as “vertical direction”. 
         [0094]    An operation panel  30  is disposed on an upper face front section of the upper section case  3 . The operation panel  30  is provided with various buttons such as a numeric button, a start button, and a function section button so that various operations can be performed by pressing these buttons. The operation panel  30  is further provided with a liquid crystal display (LCD)  31  on which the setting status of the multifunction device  1 , various operation messages and the like are displayed according to need. 
         [0095]    A scanner device  33  is disposed inside the upper section case  3 . The scanner device  33  comprises a glass plate (not shown) for placing a script, a graphic pattern reading section (not shown) disposed directly below the glass plate, and a cover body  34  for covering an upper face of the glass plate. The cover body  34  can be rotated from the position thereof shown in  FIG. 1 , in a direction of the arrow  206  around a rotation axis  204 . When the cover body  34  is rotated in the direction of the arrow  206 , the glass plate is exposed so that a script can be placed on the glass plate. The graphic pattern reading section comprises a contact image sensor (CIS), which extends in the X direction in the figure, is guided by a rail which is not shown, and can reciprocally be moved in a direction of a Y-axis. The graphic pattern reading section uses the contact image sensor to read a graphic pattern on a script which is placed on the glass plate. 
         [0096]    When the facsimile function is selected, information which is read by the graphic pattern reading section is transmitted to a facsimile device through a telephone line, the facsimile device being a transmission destination. When the copy function is selected, information which is read by the graphic pattern reading section is transmitted to the printing mechanism incorporated in the multifunction device  1 , and the graphic pattern which is read by the graphic pattern reading section is printed on a sheet. When the scanner function is selected, information which is read by the graphic pattern reading section is transmitted to a computer which is not shown. 
         [0097]    Position holding means is provided in order to rotate the upper section case  3  significantly around the rotation axis  200  and maintain the state where the interior of the lower section case  2  is exposed. The position holding means comprises a supporting rod (not shown) and a guide rail (not shown). One end of the supporting rod is installed in the vicinity a point  208  of the lower section case  2  and can be oscillated with respect to the lower section case  2 . The guide rail extends in the Y-direction along a lower surface on the back, edge of the upper section case  3 . A groove extending in the Y-direction is formed on the guide rail. A guide pin is fixed on the other end of the supporting rod and inserted in the groove. An engaging section (not shown) for inhibiting the guide pin from sliding is formed in the vicinity of the point  208  of the groove. When the upper section case  3  is rotated significantly around the rotation axis  200 , the guide pin of the supporting rod is buried in the engaging section of the guide rail, whereby the upper section case  3  is inhibited from rotating downward. 
         [0098]    Next, the configuration of the sheet sending mechanism incorporated in the lower section case  2  is explained. As shown in  FIG. 1 , a paper cassette  5  is provided at the central section in the horizontal direction of the lower section case  2 . The paper cassette  5  is configured such that it can be withdrawn with respect to an opening section  2   a  formed on a front surface of the lower section case  2 . As shown in  FIG. 6 , a plurality of sheets P are stored in a stacked fashion in the paper cassette  5 . Sheets, which are not printed with the graphic patterns, are stored in the paper cassette  5 . A separating inclined surface  8 , which is formed of a material having a high frictional coefficient, is prepared on a front wall of the paper cassette  5 . When a supply roller  7 , which is described later, is rotated in a counterclockwise direction, one piece of sheet P is taken out from the paper cassette  5  and sent to the printing mechanism incorporated in the lower section case  2 . A sheet P, which is printed with the graphic pattern by the printing mechanism, is sent to a position located in an upper section of the paper cassette  5  by the sheet sending mechanism. The user can take out the sheet P, which is printed with the graphic pattern, from the opening section  2   a  shown in  FIG. 1 . 
         [0099]    The sheet sending mechanism is stored in the lower section case  2 . As shown in  FIG. 4 , the sheet sending mechanism comprises a supply unit  6 , a sheet guide  9 , a pair of feed-in rollers  20   a,    20   b,  a tabular platen  11 , and a pair of feed-out rollers  21   a,    21   b.  The printing mechanism is stored in the lower section case  2  as well. A printing unit  10  is disposed in an upper part of the platen  11 . A space through which the sheet P can pass is secured between the printing unit  10  and the platen  11 , and this space is a printing region  210 . 
         [0100]    The supply unit  6  comprises the supply roller  7 . When the supply roller  7  is rotated in a counterclockwise direction, one piece of sheet P is taken out from the paper cassette  5  and the taken sheet is send to the right in  FIG. 4 . The sheet guide  9  extends in U shape and guides the sheet P, which is sent from the paper cassette  5  by the supply roller  7 , toward a space between the pair of feed-in rollers  20   a  and  20   b.  The pair of feed-in rollers  20   a,    20   b  causes the sheet P to pass through the printing region  210  which is secured between the printing unit  10  and the platen  11 , and sends the sheet P to a space between the pair of feed-out rollers  21   a  and  21   b.  The pair of feed-out rollers  21   a,    21   b  sends the sheet P to the position located above the paper cassette  5 . The pair of feed-in rollers  20   a,    20   b  is positioned on an upstream side of the printing unit  10  and platen  11 , and the pair of feed-out rollers  21   a,    21   b  is positioned on a downstream side of the printing unit  10  and platen  11 . 
         [0101]    The printing unit  10  sprays ink droplets onto the sheet P which passes through the space  210  between the printing unit  10  and the platen  11  to print the graphic pattern on the sheet P. The printing unit  10  sprays the ink droplets onto the sheet P to print the graphic pattern thereon while the sheet P passes through the printing region  210 . 
         [0102]    As shown in  FIG. 2  and  FIG. 3 , the printing unit  10  comprises a frame  39  formed of a metal plate, a carriage  13 , a timing belt  25  which reciprocates the carriage  13  in the Y-direction, and a carriage motor  24  (“CR motor” hereinafter) for rotating the timing belt  25 . As shown in  FIG. 4 , a printing head  12  is mounted on the carriage  13 . 
         [0103]    As shown in  FIG. 2  and  FIG. 3 , the frame  39  is disposed on the upper section of the paper cassette  5  on the back of the lower section case  2 . The frame  39  is made of metal plate and comprises, as shown in  FIG. 3  and  FIG. 4 , a bottom surface  39   a  extending in the Y-axis direction, a left wall  39   b  which is standing upward from a left end of the bottom surface  39   a,  a right wall  39   c  which is standing upward from a right end of the bottom surface  39   a,  a front side guide place  41  which connects the left wall  39   b  and the right wall  39   c,  and a backside guide plate  40  which connects the left wall  39   b  and the right wall  39   c.  The front side guide place  41  and the backside guide plate  40  extend in the Y-direction. 
         [0104]    As shown in  FIG. 7 , the timing belt  25 , which is wrapped around pulleys  25   a  and  25   b,  is disposed on an upper surface of the guide plate  41 . The timing belt  25  extends in a main scanning direction (Y-axis direction). The carriage  13  is coupled on a part of the timing belt  25 . As shown in  FIG. 3 , the pulley  25   a  is rotated by the CR motor  24 . The carriage  13  and the printing head  12  are caused to reciprocate in the Y-direction by a reciprocal rotation of the CR motor  24 . 
         [0105]    As shown in  FIG. 7 , a linear encoder (encoder strip)  37  extending in the main scanning direction (Y-axis direction) is disposed on the upper surface of the guide plate  41 . The linear encoder  37  detects the position of the carriage  13  in the Y-axis direction. The linear encoder  37  has a strip-like shape, and a control surface thereof is formed with slits which are disposed at regular intervals in the Y-axis direction. The control surface of the linear encoder  37  is disposed along a vertical surface. 
         [0106]    As shown in  FIG. 4 , the platen  11  is fixed onto the bottom surface  39   a  of the frame  39 . As shown in  FIG. 6 , a drive shaft  14  of the supply unit  6  is rotatably attached to the bottom surface  39   a  of the frame  39 . The supply unit  6  comprises an arm  6   a  which is rotatable around the drive shaft  14 , a torsion spring  38  which biases the arm  6   a  in a clockwise direction, the supply roller  7  which is rotatably attached to a front end of the arm  6   a,  and a mating gear train  50  for transmitting torque from the drive shaft  14  to the supply roller  7  (see  FIG. 4 ). 
         [0107]    Since the arm  6   a  is rotatable around the drive shaft  14 , it does not interfere with a sliding motion of the paper cassette  5 . When the paper cassette  5  is pushed into the lower section case  2 , the supply roller  7  contacts with the upper surface of the uppermost sheet P of the plurality of sheets stored in the paper cassette  5 . When the supply roller  7  is rotated in a counterclockwise direction, the uppermost sheet P is taken out from the paper cassette  5 , guided by the sheet guide  9  and travels toward the space between the pair of feed-in rollers  20   a  and  20   b.    
         [0108]    Both end sections of the pair of feed-in rollers  20   a,    20   b  are supported rotatably by the left wall  39   b  and right wall  39   c  of the frame  39 . Both end sections of the pair of feed-out rollers  21   a,    21   b  are supported rotatably by the left wall  39   b  and right wall  39   c  of the frame  39 . 
         [0109]    Of the pair of feed-in rollers  20   a,    20   b,  the feed-in roller  20   a,  which is positioned above, is rotated by a motor which is described later. The feed-in roller  20   b,  which is positioned below, is pressed against the feed-in roller  20   a  by a certain force. When the feed-in roller  20   a  rotates, the feed-in roller  20   b  also rotates with the rotation of the feed-in roller  20   a.  The feed-in roller  20   a  is a feed-in drive roller  20   a,  and the feed-in roller  20   b  is a feed-in driven roller  20   b.    
         [0110]    Similarly, of the pair of feed-out rollers  21   a,    21   b,  the feed-out roller  21   a,  which is positioned below, is rotated by the motor which is described later. The feed-out roller  21   b,  which is positioned above, is pressed against the feed-out roller  21   a  by a certain force. When the feed-out roller  21   a  rotates, the feed-out rollers  21   b  also rotates with the rotation of the feed-out roller  21   a.  The feed-out roller  21   a  is a feed-out drive roller  21   a,  and the feed-out roller  21   b  is a feed-out driven roller  21   b.    
         [0111]    When the feed-in drive roller  20   a  rotates in a clockwise direction in a state where a sheet P is held between the pair of feed-in rollers  20   a  and  20   b,  the sheet P is sent to the printing region  210  between a lower surface of the printing head  12  and the platen  11 . When the feed-in drive roller  20   a  rotates in a clockwise direction and the feed-in driven roller  20   b  rotates in a counterclockwise direction, the sheet is sent to the printing region  210 . This situation is called “forward rotation of the pair of feed-in rollers”. The power of the pair of feed-in rollers  20   a,    20   b  to send the sheet P is stronger than the power of supply roller  7  to send the sheet P. The speed of the pair of feed-in rollers  20   a,    20   b  to send the sheet P is faster than the speed of the supply roller  7  to send the sheet P. Since the power of the pair of feed-in rollers  20   a,    20   b  to send the sheet P is stronger than the power of the supply roller  7  to send the sheet P, when a piece of sheet P is sent by both the pair of feed-in rollers  20   a,    20   b  and the supply roller  7 , the sheet P is sent at the sending speed of the pair of feed-in rollers  20   a,    20   b.  The sheet P slides with respect to the supply roller  7 . The sending speed of the pair of feed-in rollers  20   a,    20   b  to send the sheet P is equal to the sending speed of the pair of feed-out rollers  21   a,    21   b  to send the sheet P. 
         [0112]    On the lower surface of the printing head  12 , a plurality of nozzles for injecting black ink droplets, a plurality of nozzles for injecting cyan ink droplets, a plurality of nozzles for injecting magenta ink droplets, and a plurality of nozzles for injecting yellow ink droplets are formed. The printing head  12  is mounted on the carriage  13  and moves in the Y-direction. The sheet P, onto which the ink droplets are sprayed, is sent in the upper section of the platen  11  in the X-direction by the pair of feed-in rollers  20   a,    20   b.  By combining the sending of the sheet P in the X-direction and the sending of the printing head  12  in the Y-direction, any color of ink droplets can be sprayed onto any position on the sheet P, and thereby any graphic pattern can be printed on the sheet P. 
         [0113]    As shown in  FIG. 2  and  FIG. 3 , ink cartridges  26  for supplying inks to the printing head  12  are stored in the lower section case  2 . The ink cartridges  26  are configured so as to be detachable from above with respect to a storage section  27  (see.  FIG. 2  and  FIG. 3 ) which is formed in a position far away from the rotation axis  200  shown in  FIG. 1 . In the present embodiment, an ink cartridge storing the black ink, an ink cartridge storing the cyan ink, an ink cartridge storing the magenta ink, and an ink cartridge storing the yellow ink are used. More ink cartridges may be used. Each of the ink cartridges  26  and the printing head  12  is connected with each other by a flexible ink tube  28 . 
         [0114]    As shown in  FIG. 3 , an ink receiving section  35  is provided in a section which is located outside the width of a sheet P to be conveyed (short side of the sheet P) and in the vicinity of the left wall  39   b  of the frame  39 . A maintaining mechanism  36  is provided in a section which is located outside the width of the sheet P to be conveyed and in the vicinity of the right wall  39   c  of the frame  39 . 
         [0115]    The printing head  12  periodically discharges ink to the ink receiving section  35  in order to prevent clogging of the nozzles. The ink, which is discharged to prevent the clogging, is received at the ink receiving section  35 . 
         [0116]    When the printing head  12  is not used, the printing head  12  is moved to a position facing the maintaining mechanism  36 . In this position, a cap section  36   a  (see  FIG. 8 ) covers a nozzle surface of the printing head  12  from below to prevent the ink from drying in the nozzles of the printing head  12 . Moreover, at a required timing, a recovery process and the like are performed in which a suction pump (not shown) is activated to draw the ink from the nozzles and air bubbles are removed from a buffer tank (not shown) provided on the printing head  12 . It should be noted that when the carriage  13  moves from a position facing the mechanism  36  toward the printing region  210  in a lateral direction (Y direction), cleaning of the printing head  12  is performed by wiping the nozzle surface thereof using a wiper blade  36   b  (see  FIG. 8 ). 
         [0117]    The carriage  13  travels, in the Y-direction, back and forth between a position existing in an upper section of the ink receiving section  35  and a position existing on an upper section of the maintaining mechanism  36 . The position existing in the upper section of the ink receiving section  35  is called “first end”, and the position existing in the upper section of the maintaining mechanism  36  is called “second end”. 
         [0118]    The feed-in drive roller  20   a,  feed-out drive roller  21   a,  supply roller  7 , and maintaining mechanism  36  are driven by the same motor (LF motor)  42 . 
         [0119]    As shown in  FIG. 8 , the LF motor  42  is disposed at a left end section of the frame  39 . A shaft of the LF motor  42  penetrates through the left wall  39   b  of the frame  39  and extends to the outside of the frame  39 . As shown in  FIG. 9 , a pinion  43   a  is fixed to the shaft of the LF motor  42 . Gears  43   b,    43   c  and  43   d  are rotatably supported outside of the left wall  39   b.    
         [0120]    As shown in  FIG. 9 , the gear  43   b  is geared with the pinion  43   a.  As shown in  FIG. 10 , the feed-in drive roller  20   a  is fixed to the gear  43   b.  When the LF motor  42  rotates, the feed-in drive roller  20   a  rotates. As shown in  FIG. 9 , the gear  43   d  is geared with the pinion  43   a  via the intermediate gear  43   c.  The feed-out drive roller  21   a  is fixed to the gear  43   d.  When the LF motor  42  rotates, the feed-out drive roller  21   a  rotates. 
         [0121]    The gear  43   b  and the gear  43   d  rotate in the counter direction. Therefore, the feed-in drive roller  20   a  and the feed-out drive roller  21   a  also rotate in the counter direction. The feed-in drive roller  20   a  abuts on the top surface of the sheet P and the feed-out drive roller  21   a  abuts on the bottom surface of sheet P. Therefore, if the direction of rotation of the feed-in drive roller  20   a  and the feed-out drive roller  21   a  is reversed, the sending direction of the sheet P by the feed-in drive roller  20   a  and the sending direction of the sheet P by the feed-out drive roller  21   a  become the same direction. 
         [0122]    The LF motor  42  is a DC motor and can rotate in both forward and reverse directions. 
         [0123]    As shown in  FIG. 10 , a gear  101  is fixed to the feed-in drive roller  20   a  within a range located at a right end section of the feed-in drive roller  20   a,  i.e. the upper section of the maintaining mechanism  36 . The gear  101  is geared with one of three gears  113 ,  114  and  115  disposed adjacent to the gear  101 , and rotates one of the three gears  113 ,  1 - 14  and  115 . Power transmission switching means  100  selects a gear to be engaged with the gear  101 . A movement of the carriage  13  in the Y-direction is used to select the gear to be engaged with the gear  101  by means of the power transmission switching means  100 . 
         [0124]    When the gear  113  is engaged with the gear  101 , and the LF motor  42  rotates in the reverse direction, the supply roller  7  is rotated in the forward direction. When the gear  114  is engaged with the gear  101 , and the LF motor  42  rotates in the forward direction, the supply roller  7  is rotated in the forward direction. When the gear  115  is engaged with the gear  101 , the LF motor  42  moves the maintaining mechanism  36 . 
         [0125]    When the LF motor  42  rotates in the reverse direction, the feed-in drive roller  20   a  rotates in the reverse direction and in a direction of returning the sheet to the sheet guide  9 . When the LF motor  42  rotates in the forward direction, the feed-in drive roller  20   a  rotates in the forward direction and in a direction of sending the sheet to the printing region  210 . When the supply roller  7  rotates in the forward direction, the sheet is taken out from the cassette and sent to the sheet guide  9 . When the supply roller  7  rotates in the reverse direction, the sheet is returned to the cassette  5 . 
         [0126]    When the LF motor  42  rotates in the forward direction in a state where the gear  113  is engaged with the gear  101 , the pair of feed-in rollers  21   a,    21   b  rotates in the forward direction, and the supply roller  7  rotates in the reverse direction. When the LF motor  42  rotates in the reverse direction in the state where the gear  113  is engaged with the gear  101 , the pair of feed-in rollers  21   a,    21   b  rotates in the reverse direction, and the supply roller  7  rotates in the forward direction. When the LF motor  42  rotates in the forward direction in a state where the gear  114  is engaged with the gear  101 , the pair of feed-in rollers  21   a,    21   b  rotates in the forward direction, and the supply roller  7  rotates in the forward direction. 
         [0127]    As shown in  FIG. 8 , a rotary encoder  44  which rotates integrally with the gear  43   b  is provided. The amount of sheet P conveyed by the feed-in roller  20   a  can be detected by the rotary encoder  44 . It should be noted that the CR motor  24  and LF motor  42  can be rotated in forward and reverse directions. 
         [0128]    Next, the configuration of the power transmission switching means  100  is explained with reference to  FIG. 10  and  FIG. 11 . The power transmission switching means  100  selects any of an intermittent feeding mode, a continuous feeding mode, and a maintenance mode. In the intermittent feeding mode, when the LF motor  42  rotates in the reverse direction, the supply roller  7  is rotated in the forward direction. In the continuous feeding mode, when the LF motor  42  rotates in the forward direction, the supply roller  7  is rotated in the forward direction. In the maintenance mode the torque of the LF motor  42  is transmitted to the maintaining mechanism  36 . 
         [0129]    In the intermittent feeding mode, when the LF motor  42  rotates in the reverse direction, the feed-in drive roller  20   a  rotates in a direction of returning the sheet to the sheet guide  9 , and the supply roller  7  rotates in a direction of taking the sheet out from the cassette and sending it to the sheet guide  9 . Thereafter, in the intermittent feeding mode, the LF motor  42  rotates in the forward direction. In the intermittent feeding mode, when the LF motor  42  rotates in the forward direction, the feed-in drive roller  20   a  rotates in a direction of sending the sheet to the printing region  210 , and the supply roller  7  rotates in a direction of returning the sheet to the cassette. 
         [0130]    When the LF motor  42  rotates in the reverse direction in the intermittent feeding mode, the sheet is sent to the pair of feed-in rollers  20   a,    20   b  by the supply roller  7 . Since the pair of feed-in rollers  20   a,    20   b  is rotated in the reverse direction, the sheet cannot enter between the feed-in drive roller  20   a  and the feed-in driven roller  20   b.  The front edge of the sheet is aligned with a contact line with which the feed-in drive roller and the feed-in driven roller contact. The pair of feed-in rollers  20   a,    20   b  rotating in the reverse direction exerts a function providing the front edge of the sheet in a certain position. When the LF motor  42  rotates in the forward direction in the intermittent feeding mode, the sheet is sent to the printing region  210  by the pair of feed-in rollers  20   a,    20   b.  In this state, the sheet slides with respect to the supply roller  7 . 
         [0131]    In the continuous feeding mode, the LF motor  42  rotates in the forward direction, the supply roller  7  rotates in the direction of taking out the sheet from the cassette and sending it to the sheet guide  9 , and the feed-in drive roller  20   a  rotates in a direction of sending the sheet to the printing region  210 . 
         [0132]    As described above, the torque of the LF motor  42  is transmitted to the feed-in drive roller  20   a  via deceleration gear  43   b.  The gear  101  is fixed to a right end section of the feed-in drive roller  20   a  (upper section of the maintaining mechanism  36 ). A switching gear  102 , which is always engaged with the gear  101 , is provided at a position adjacent to the gear  101 . The switching gear  102  is slidable with respect to a spindle  103  extending in the Y-axis direction. 
         [0133]    A first block  104  (first slider) and a second block  105  (second slider) are slidable with respect to the spindle  103 . The switching gear  102 , first block  104 , and second block  105  are slidable with respect to the spindle  103  independently of other members. The first block  104  contacts with or separates from the switching gear  102 . The second block  105  contacts with or separates from the first block  104 . The switching gear  102  and the first block  104  are rotatable with respect to the spindle  103 , and the second block  105  is prohibited to rotate with respect to the spindle  103 . 
         [0134]    A surface with which the first block  104  and the second block  105  contact is inclined to the spindle  103 . When the second block  105  approaches the first block  104 , the first block  104  rotates around the spindle  103 . An abutting piece  104   a  protruding upward is fixed to the first block  104 . When the second block  105  approaches the first block  104  and the first block  104  rotates around the spindle  103 , the abutting piece  104   a  moves from top to bottom, in  FIG. 11 . 
         [0135]    As shown in  FIG. 29  through  FIG. 32 , a plate-like engaging plate  104   b  is provided between a base section  104   c  of the first block  104  and the abutting piece  104   a  extending from the base section  104   c  in a radial outer direction. In the second block  105 , a section facing the engaging plate  104   b  in the base section  105   a  is provided with a notch section  105   b  in which the engaging plate  104   b  is buried. One surface of the notch section  105   b  is formed as an abutting surface  105   c  inclining from the center of radius of the base section  105   a  to the outside the radius of same. Further, the second block  105  is provided with a pair of corner sections  105   d  extending in the radial outer direction from the base section  105   a.  The pair of corner sections  105   d  is provided so as to be able to abut on a bottom surface of the guide plate  41  on the downstream side so that the second block  105  does not rotate around the spindle  103 . The base section  104   c  of the first block  104  is formed so as to be buried in an inner diameter of the base section  105   a  of the second block  105 . 
         [0136]    During a period between a state where the first block  104  and the second block  105  approach each other and the engaging plate  104   b  abuts against a section on the outer radius side in the abutting surface  105   c  of the notch section  105   b  (see  FIG. 31 ) and a state where the space between the first block  104  and the second block  105  becomes narrow and the engaging plate  104   b  abuts against a section on the center side of the radius in the abutting surface  105   c  of the notch section  105   b  (see  FIG. 32 ), the position of the first block  104  is forcibly caused to rotate in the direction of the arrow D (see  FIG. 30 ). If the first block  104  rotates, the abutting piece  104   a  also rotates. When the first block  104  rotates in the direction of the arrow D, the abutting piece  104   a  moves from top to bottom in  FIG. 11 . 
         [0137]    As shown in  FIG. 10 , a first biasing spring  106   a  is disposed around the spindle  103 . The first biasing spring  106   a  presses the second block  105  in the direction of the arrow C. A second biasing spring  106   b  is disposed around the spindle  103 . The second biasing spring  106   b  presses the switching gear  102  in the direction of the arrow E. The biasing force of the first biasing spring  106   a  is larger than the biasing force of the second biasing spring  106   b.    
         [0138]    As shown in  FIG. 11 , a first engaging step section  13   a  and a second engaging step section  13   b  are formed in the carriage  13 . When the carriage  13  moves in the direction of the arrow E, the abutting piece  104   a  of the first block  104  is engaged with either the first engaging step section  13   a  or the second engaging step section  13   b.    
         [0139]    As shown in  FIG. 8 , a guide block  107  is fixed to the frame  39 . A guide groove  109  is formed in the guide block  107 , and the abutting piece  104   a  of the first block  104  is buried in the guide groove  109 . As shown in  FIG. 11 , the guide groove  109  comprises a horizontal groove section  109   a  which is elongated in the direction indicated by the arrows C and E (Y axis), and an inclined groove section  109   b  which is communicated with a left end section of the horizontal groove section  109   a.  A regulating piece  110  which extends downward from an upper section of the guide block  107  is inserted in a central section of the inclined groove section  109   b.  The regulating piece  110  is elongated in the direction indicated with the arrows C and E. The inclined groove section  109   b  is provided with a stair-like first set section  111  and second set section  112 . A first wall  216 , which is provided with the first set section  111  and second set section  112 , and a second wall  218  extending to the opposite side are formed on the inclined groove section  109   b.  The first set section  111  and the second set section  112  are formed on the first wall  216 , while no set section is formed on the second wall  218 . 
         [0140]    As shown in  FIG. 11 , when the carriage  13  is located in a position facing the sheet P, the carriage  13  is away from the maintaining mechanism  36  and does not press the abutting piece  104   a  in the direction of the arrow E. In this state, the first biasing spring  106   a  causes the second block  105 , first block  104  and switching gear  102  to slide along the spindle  103  in the direction of the arrow C. The abutting piece  104   a  is positioned at the first set section  111 . This position is called “position  1 ” (Po 1 ). At this moment, the switching gear  102  is engaged with the intermittent feeding gear  113 . 
         [0141]    When the carriage  13  moves in the direction of the arrow E, the first engaging step section  13   a  of the carriage  13  presses the abutting piece  104   a  in the direction of the arrow E. As a result, the switching gear  102 , the first block  104 , and the second block  105  are caused to slide along the spindle  103  in the direction of the arrow E. Since the first block  104  is pressed by the second block  105  from the right side, the abutting piece  104   a  is pressed against a lower wall (first wall  216 ) of the inclined groove  109   b.  When the carriage  13  presses the abutting piece  104   a  up to the position corresponding to the second set section  112 , the abutting piece  104   a  is moved down to enter the second set section  112 . The position where the abutting piece  104   a  enters the second set section  112  is called “position  2 ” (Po 2 ). In the case of the position  2 , the switching gear  102  is engaged with the continuous feeding gear  114 . This state is shown in  FIG. 10 . 
         [0142]    When the carriage  13  further moves in the direction of the arrow E, the first engaging step section  13   a  of the carriage  13  presses the abutting piece  104   a  in the direction of the arrow E. The pressed abutting piece  104   a  proceeds to the horizontal groove section  109   a  from the inclined groove section  109   b.  Once the abutting piece  104   a  enters the horizontal groove section  109   a,  the second engaging step section  13   b  of the carriage  13  presses the abutting piece  104   a.  When the abutting piece  104   a  is in the position immediately after entering the horizontal groove section  109   a  (this position is called “position  3 ” (Po 3 )), the switching gear  102  is engaged with the maintenance gear  115 . 
         [0143]    The switching gear  102 , intermittent feeding gear  113 , continuous feeding gear  114  and maintenance gear  115  are all spur gears, and a bevel gear  115   a  having a large diameter is fixed to a side surface of the maintenance gear  115 . When the carriage  13  further moves from the position  3  (Po 3 ) in the direction of the arrow E, a side surface of the switching gear  102  abuts on the bevel gear  115   a,  whereby the switching gear  102  is inhibited from moving any further in the direction of the arrow E and thus continues to be engaged with the maintenance gear  115 . The abutting piece  104   a  is pressed by the second engaging step section  13   b  of the carriage  13  and then positioned at a back end section of the horizontal groove section  109   a  (right end section shown in  FIG. 11  and  FIG. 12 ). This position is called “position  4 ” (Po 4 ) and is a home position (original position). In this state, the switching gear  102  and the first block  104  are separated from each other. 
         [0144]    Contrary to the above state, when the carriage position  13  moves from the position  4  (Po 4 ) in the direction of the arrow C, the abutting piece  104   a  moves from the horizontal groove section  109   a  to the inclined groove section  109   b.  At this moment, the abutting piece  104   a  is received by a step between the first engaging step section  13   a  and the second engaging step section  13   b  of the carriage  13 , thus the abutting piece  104   a  moves above the regulating piece  110  of  FIG. 11  in the direction of the arrow C. The abutting piece  104   a  abuts on a left inclined surface of the inclining groove section  109   b  shown in  FIG. 11  while sliding on the regulating piece  110 , thereafter moves along the left inclined surface (second wall  218 ) and then is engaged with the first set section  111 . A set section does not exist on an upper wall (second wall  218 ) of the guide groove  109 , thus the abutting piece  104   a  moves from the position  4  to the position  1 . 
         [0145]    After the carriage  13  moves to the right end in the E direction and then moves in the C direction, the abutting piece  104   a  moves from the position  1  to the position  2 , from the position  2  to the position  3 , from the position  3  to the position  4 , and from the position  4  to the position  1 . The carriage  13  repeats the movement of moving to the right end in the E direction and then moving in the C direction, while the abutting piece  104   a  repeats the cycle of moving from the position  1 → 2 → 3 → 4 → 1 . When the carriage  13  moves in the E direction to the position  1  and then in the C direction, the switching gear  102  is held at the position  1 . When the carriage position  13  moves to the position  2  in the E direction and then in the C direction, the switching gear  102  is held in the position  2 . 
         [0146]    The position  3  (Po 3 ) is both stand-by position and maintenance position. In a state where power is not applied to the multifunction device  1 , the carriage  13  stops at an upper position of the maintaining mechanism  36  and the power transmission switching means  100  is at the position  3 . When the power transmission switching means  100  is at the position  3 , the maintenance gear  115  is geared with the feed-in drive roller  20   a  via the switching gear  102 . When the LF motor  42  rotates in this state, the cap section  36   a  of the maintaining mechanism  36  rises and covers the nozzle surface of the printing head  12  from below. Accordingly, the ink is prevented from drying in the nozzles of the printing head  12 . Moreover, the maintaining mechanism  36  is provided with a suction pump (not shown), and when the LF motor  42  rotates in the state where the power transmission switching means  100  is at the position  3  and the maintenance gear  115  is geared with the feed-in drive roller  20   a  via the switching gear  102 , the LF motor  42  activates the suction pump. When the suction pump of the maintaining mechanism  36  is activated, air bubbles which are mixed in the buffer tank provided on the printing head  12  are removed, thus the ability of discharging the ink from the nozzles is maintained. 
         [0147]    The position  1  (Po 1 ) where the switching gear  102  is geared with the intermittent feeding gear  113  is configured such that, as shown in  FIG. 13  and  FIG. 14 , the torque of the LF motor  42  is transmitted to the drive shaft  14  provided at a rear end of the arm  6   a,  via two intermediate gears  119   a  and  119   b,  and the supply roller  7  is rotated via the gear train  50 . In this state, when the LF motor  42  rotates in the reverse direction, the supply roller  7  rotates in the forward direction. 
         [0148]    The position  2  (Po 2 ) where the switching gear  102  is geared with the continuous feeding gear  114  is configured such that, as shown in  FIG. 15  through  FIG. 17 , the torque of the LF motor  42  is transmitted to the drive shaft  14  provided at the rear end of the arm  6   a,  via one intermediate gear  120 , and the supply roller  7  is rotated via the gear train  50 . In this state, when the LF motor  42  rotates in the forward direction, the supply roller  7  rotates in the forward direction. 
         [0149]    As shown in  FIG. 5 , a roller  50  is disposed between the printing head  12  and the feed-out rollers  21   a,    21   b.  The roller  50  presses the sheet P against the platen  11 . Since the roller  50  is provided, the sheet P is not brought into contact slidingly with the nozzle surface of the printing head  12 , thus the sheet P is prevented from being stained. 
         [0150]    Furthermore, a sheet sensor  116  for sensing the presence of the sheet P is provided on an upstream side of the feed-in rollers  20   a,    20   b.  The sheet sensor  116  detects a point of time at which the front edge of the sheet P reaches the sheet sensor  116  and a point of time at which the back edge of the sheet P separates from the sheet sensor  116 . 
         [0151]    A control section (control means) of the multifunction device  1  is described next with reference to  FIG. 20 . The control section is for controlling the entire operation of the multifunction device  1 . 
         [0152]    The control section is configured as a computer comprising mainly as a CPU  300 , ROM  301 , RAM  302 , and EEPROM  303 , and is connected to an application specific integrated circuit (ASIC)  306  via a bus  305 . 
         [0153]    The ROM  301  has stored therein a program and the like for controlling various operations of the multifunction device  1 , and the RAM  302  is used as a storage region for temporarily storing various data items which are used when the CPU  300  executes these programs. 
         [0154]    An NCU (Network Control Unit)  317  is connected to the ASIC  306 , and a communication signal which is inputted from a public circuit via the NCU  317  is demodulated by a MODEM  318  and then inputted to the ASIC  306 . Furthermore, when the ASIC  306  transmits image data to the outside by means of facsimile transmission or the like, the image data is modulated by the MODEM  318  and then outputted to the public line via the NCU  317 . 
         [0155]    The ASIC  306  generates a phase excitation signal and the like which are communicated with, for example, the LF motor  42  in accordance with a command from the CPU  300 . These signals are provided to a drive circuit  311  of the LF motor  42  or a drive circuit  312  of the CR motor  24 , and a drive signal is communicated to the LF motor  42  or CR motor  24  via the drive circuit  311  or drive circuit  312  to control forward and reverse operation, stoppage and the like of the LF motor  42  and CR motor  24 . 
         [0156]    Further, the scanner device  33  (CIS, for example) for reading images or characters on a script, a panel interface  313  for performing transmission of signals with a keyboard  30   a  and a liquid crystal display (LCD)  31  of the operation panel  30 , a parallel interface  315  for performing transmission of data with external equipment such as a personal computer via a parallel cable or USB cable, a USB interface  316 , and the like are connected to the ASIC  306 . 
         [0157]    Moreover, a switch  118  for detecting a rotation position of a cam (not shown) of the maintaining mechanism  36 , the sheet sensor  116  for detecting the front edge position and the back edge position of the sheet P when the sheet P is fed so as to approach the printing region  210  via the sheet guide  9 , the rotary encoder  44  for detecting the amount of rotation of the feed-in roller  20   a,  the linear encoder  37  for detecting the position (present position) of the carriage  13  in the Y-direction, and the like are connected to the ASIC  306 . 
         [0158]    A driver  314  is for selectively discharging the ink from the printing head  12  at a predetermined timing. The driver  314  receives a signal, which is generated in the ASIC  306  on the basis of a drive control procedure outputted from the CPU  300  and is then outputted, and drive-controls the printing head  12 . 
         [0159]    Next, sending of sheets by means of the above control means and control of the printing operation are described with reference to the flowchart shown in  FIG. 21 . In the control shown in  FIG. 21 , a pattern of feeding the sheet P is changed to either the first mode or the second mode. In the first mode, a plurality of sheets are sent intermittently to the printing region  210 . The first mode is an accurate mode in which printing precision is prioritized. In the second mode, a plurality of sheets is sent to the printing region  210  continuously and sequentially. The second mode is a speedy mode in which the printing speed is prioritized. 
         [0160]    When power is applied to the multifunction device  1 , control is started. The user presses a mode setting button of the operation panel  30  (not shown) to select either the first mode or the second mode. When the user wishes to print precisely, the first mode is selected. When the first mode is selected, the front edge of a sheet P, which is sent by the supply roller  7 , is aligned with a contact line  212  (see  FIG. 5 ) between the pair of feed-in rollers  20   a,    20   b  rotating in the reverse direction, in which state sending of the sheet P is stopped once. Even if the front edge of the sheet P is sent by the supply roller  7  such that the front edge of the sheet P is inclined with respect to the contact line  212  between the pair of feed-in rollers  20   a,    20   b,  the front edge of the sheet P is aligned with the contact line  212  between the pair of feed-in rollers  20   a,    20   b.  In a state where the front edge of the sheet P is aligned with the contact line  212  between the pair of feed-in rollers  20   a,    20   b,  the pair of feed-in rollers  20   a,    20   b  starts to send the sheet P toward the printing region  210 . This timing is sent to the CPU  300 , and the CPU  300  controls the printing head  12  on the basis of this timing. When the first mode (accurate mode) is selected, the front edge of the sheet P is not sent toward the printing region  210  in the inclined state, and the position of the front edge of the sheet P and the control on the printing head  12  are synchronized, whereby a desired graphic pattern is printed on a desired location of the sheet P. 
         [0161]    The control section first checks the set mode (S 1  in  FIG. 21 ). The control section then determines whether the set mode is the accurate mode (intermittent feeding mode) (S 2 ). If the set mode is the accurate mode (S 2 : yes), the flag is switched to the first mode (S 3 ), and the power transmission switching means  100  is set to the accurate mode (S 4 ). Specifically, the carriage  13 , which is stopped at the stand-by position indicated by the Po 3  in  FIG. 12 , is moved significantly to the printing region  210  in the direction of the arrow C. Accordingly, the first block  104  which is pressed by the biasing spring  106   a  is moved in the direction of the arrow C along the regulating piece  110  inside the inclining groove  109   b  shown in  FIG. 11 , then received by the first set section  111  and held at this position (position  1  (Po 1 ). In this state, the switching gear  102  is geared with the intermittent feeding gear  113 . 
         [0162]    Once the switching gear  102  is geared with the intermittent feeding gear  113 , rotation of the feed-in drive roller  20   a  is transmitted to the drive shaft  14  of the supply unit  6  via the intermediate gear  119   a,    119   b,  as shown in  FIG. 13 . In this state, when the LF motor  42  is rotated in the reverse direction, the feed-in drive roller  20   a  is rotated in the reverse direction (counterclockwise direction in  FIG. 13 ). On the other hand, the supply roller  7  is rotated in the forward direction (counterclockwise direction in  FIG. 13 ) by the gear train  50  inside the arm  6   a.  When the supply roller  7  is rotated in the forward direction, the plurality of sheets P, which are stacked on the paper cassette  5 , are caused to abut on a separating member (not shown) of the separating inclined surface  8  provided at the front edge of the paper cassette  5 , the separating member having a high frictional coefficient. Then, only one uppermost sheet P is taken out from the paper cassette  5  and sent toward the sheet guide  9  (S 5  in  FIG. 21 ). At this moment, since the feed-in roller  20   a  is rotated in the reverse direction (counterclockwise direction in FIG.  4 ), the sheet P which is sent by the supply roller  7  cannot pass through between the feed-in drive roller  20   a  and the feed-in driven roller  20   b.  The front edge of the sheet P is aligned with the contact line  212  (see  FIG. 5 ) between the pair of feed-in rollers  20   a,    20   b.  Even if the front edge of the sheet P sent by the supply roller  7  is inclined, the front edge of the sheet P is aligned with the contact line  212  between the pair of feed-in rollers  20   a,    20   b.    
         [0163]    Next, as shown in  FIG. 14 , the LF motor  42  rotates in the forward direction through an appropriate number of steps, the feed-in drive roller  20   a  rotates in the forward direction (clockwise rotation in  FIG. 14 ), and the sheet P between the feed-in drive roller  20   a  and the feed-in driven roller  20   b  is sent toward the printing region  210 . The sheet P is sent by a predetermined distance after the LF motor  42  started rotation in the forward direction. As a result, the front edge of the sheet P is set at a print starting position inside the printing region  210 . This process is called “heading process”. 
         [0164]    The supply roller  7  rotates in the reverse direction (clockwise direction in  FIG. 14 ) during the heading process. However, since the power of the feed-in drive roller  20   a  and the feed-in driven roller  20   b  sending the sheet P is set larger than the power of the supply roller  7  sending the sheet P, the sheet P is sent by the pair of feed-in rollers  20   a,    20   b,  and the arm  6   a  is oscillated in the counterclockwise direction around the drive shaft  14 . When the arm  6   a  is oscillated in the counterclockwise direction around the drive shaft  14 , the power for pressing the sheet against the supply roller  7  weakens, thus the power for sending the sheet is not transmitted to the sheet even when the supply roller  7  is rotated. The sheet is caused to slide with respect to the supply roller  7  and released from the supply roller  7 . 
         [0165]    Subsequently, when a printing command is inputted from an external computer or the like, which is not shown, the carriage  13  is caused to move in the Y-direction and at the same time the ink is discharged from the nozzles of the printing head  12  onto a surface of the sheet P to print a graphic pattern thereon (S 6  in  FIG. 21 ). While the carriage  13  moves in the Y-direction, the supply roller  7 , the feed-in rollers  20   a,    20   b  and the feed-out rollers  21   a,    21   b  are stopped, therefore, the sheet P is stopped. When the carriage moves from one end to the other end in the Y-direction, and a printing operation along a single path of the carriage is completed, the feed-in rollers  20   a,    20   b  and the feed-out rollers  21   a,    21   b  are rotated in the forward direction by the predetermined distance, which is equal to a length of the printing region along X axis printed by the single path of the carriage. Movement of the carriage  13  and rotation of the feed-in rollers  20   a,    20   b  and the feed-out rollers  21   a,    21   b  are performed alternately. 
         [0166]    When the feed-in rollers  20   a,    20   b  and the feed-out rollers  21   a,    21   b  are rotated in the forward direction during the heading operation or printing operation, the drive shaft  14  is rotated in the reverse direction, and the arm  6   a  is oscillated upward. The power for pressing the sheet against the supply roller  7  weakens, thus the power for sending the sheet is not transmitted from the supply roller  7  to the sheet. Although the supply roller  7  rotates in a reverse direction while the feed-in rollers  20   a,    20   b  and the feed-out rollers  21   a,    21   b  rotate in the forward direction, the sheet is caused to slide with respect to the supply roller  7  and the sheet P is sent in the forward direction. 
         [0167]    In this heading process, the front edge of the sheet P was aligned with the contact line  212  between the pair of, feed-in rollers  20   a,    20   b  when the LF motor  42  started the forward rotation. Therefore the position of the front edge of the sheet P during the forward rotation of the pair of feed-in rollers  20   a,    20   b  is determined from elapsed time since the timing when the pair of feed-in rollers  20   a,    20   b  started the forward rotation. When the operation of the printing head  12  is controlled based on that timing, the position of the front edge of the sheet P and the operation of the printing head  12  are synchronized, whereby a desired graphic pattern is printed on a desired location of the sheet P. 
         [0168]    When printing one page is finished (S 7  in  FIG. 21 : yes), feeding out of the printed sheet P is started (S 8  in  FIG. 21 ). In doing so, the LF motor  42  rotates in the forward direction through the number of steps (S 9  in  FIG. 21 : yes), and then the rotation of the LF motor  42  is stopped (S 10  in  FIG. 21 ). As a result, feed-in rollers  20   a,    20   b  and the feed-out rollers  21   a,    21   b  rotate a predetermined number of times in a direction of sending the sheet and then stops. The printed sheet P is sent out to the upper position in the cassette  5 . 
         [0169]    Next, it is determined whether printing data for a sheet (next page), which is described hereinafter, is present or not (S 11 ). If the print data exists or is stored (S 11  in  FIG. 21 : yes), the process from the step S 5  through S 11  is repeated. In this manner, the sheets P are sent to the printing region  210  one by one. In this mode, a color picture, for example, can be printed accurately. 
         [0170]    Next, a case in which the second mode is set is explained. When the user needs printing at high speed, the second mode is set. 
         [0171]    When it is determined in the step S 2  in  FIG. 21  that the set mode is not the first mode, the flag is set to the second mode (S 12  in  FIG. 21 ). Specifically, the flag showing the second mode is stored in a predetermined region inside the RAM  302 . Next, the power transmission switching means  100  is set to the second mode (S 13 ). In the second mode, the quality of a print it not important, but the printing speed is prioritized, thus a plurality of sheets P are continuously and sequentially sent to the printing region  210 . Therefore, the power of the feed-in roller  20   a  and the feed-in roller  20   b  sending the sheets is set larger than the power of the supply roll  7  sending the sheets, and the circumferential speed of the feed-in roller  20   a  is set higher than the circumferential speed of the supply roller  7 . The speed reduction ratio between the continuous feeding gear  114  and the intermediate gear  120  shown in  FIG. 15  through  FIG. 17  is set such that the circumferential speed of the feed-in roller  20   a  is higher than the circumferential speed of the supply roller  7 . 
         [0172]    In order to set the power transmission switching means  100  to the second mode (S 13  in  FIG. 21 ), the carriage  13  is moved a predetermined amount in the direction of the arrow E, as shown in  FIG. 12 . Accordingly, as shown in  FIG. 11 , the abutting piece  104   a  is pressed in the E direction at the first engaging step section  13   a  of the carriage  13 . The abutting piece  104   a  is positioned at the second set section  112  (position  2 , Po 2 ) while moving the carriage  13  in the direction of the arrow E. By positioning the abutting section  104   a  at the second set section  112  (position  2 , Po 2 ), even if the carriage  13  is moved in the direction of the arrow C thereafter, the abutting piece  104   a  can be held at the second set section  112 . During the period in which the abutting piece  104   a  is positioned at the second set section  112 , the switching gear  102  and the continuous feeding gear  114  are geared with each other, as shown in  FIG. 15  through  FIG. 17 , and the power is transmitted to the drive shaft  14  of the rear end of the arm  6   a  via one intermediate gear  120 . 
         [0173]    As shown in  FIG. 15 , when the LF motor  42  rotates in the forward direction in order to start feeding a sheet P, the feed-in drive roller  20   a  rotates in the forward direction (clockwise direction in  FIG. 15 ), and the supply roller  7  also rotates in the forward direction. The supply roller  7  separates only one uppermost sheet P and sends it to the sheet guide  9  (S  14  in  FIG. 21 ). When the front end section of the sheet P reaches the contact line  212  between the feed-in drive roller  20   a  and the feed-in driven roller  20   b,  the front end of the sheet P is drawn into between the feed-in drive roller  20   a  and the feed-in drive roller  20   b  since the feed-in roller  20   a  is rotated in the forward direction, and is then sent toward the printing region  210 . 
         [0174]    When one piece of sheet P is held between the pair of feed-in rollers  20   a,    20   b  and is in contact with the supply roller  7  (see  FIG. 16 ), since the power of the pair of feed-in rollers  20   a,    20   b  sending the sheet is set larger than the power of the supply roller  7  sending the sheet, and the circumferential speed of the feed-in drive roller  20   a  is set higher than the circumferential speed of the supply roller  7 , thus the sheet P is sent toward the printing region  210  at the sending speed of the feed-in roller  20   a.  The sheet P slides with respect to the supply roller  7 . Since the preceding sheet is sent by the pair of feed-in rollers  20   a,    20   b  with faster speed, and the subsequent sheet is sent by the supply roller  7  with slower speed, there is provided a space between the preceding sheet and the subsequent sheet when the preceding sheet and the subsequent sheet reach the pair of feed-in rollers  20   a,    20   b.    
         [0175]    In the continuous feeding mode, the printing operation onto the sheet P (S 15  in  FIG. 21 ) is started when the amount of rotation of the pair of feed-in rollers  20   a,    20   b  reaches a predetermined amount after the front edge of the sheet P is sensed by the sheet sensor  116 . When the pair of feed-in rollers  20   a,    20   b  rotates by the predetermined amount after the sheet sensor  116  detected the front edge of the sheet P, the pair of feed-in rollers  20   a,    20   b  stops rotation. At this timing the sheet is located at a print start position. The printing operation is stared (S 15  in  FIG. 21 ) when the sheet is adjusted at the print start position. 
         [0176]    In the printing operation, the carriage  13  is caused to move in the Y-direction and at the same time the ink is discharged from the nozzles of the printing head  12  onto a surface of the sheet P to print a graphic pattern thereon (S 15  in  FIG. 21 ). While the carriage  13  moves in the Y-direction, the supply roller  7 , the feed-in rollers  20   a,    20   b  and the feed-out rollers  21   a,    21   b  are stopped, therefore, the sheet P is stopped. When the carriage  13  moves from one end to the other end in the Y-direction, and a printing operation along a single path of the carriage is completed, the feed-in rollers  20   a,    20   b  and the feed-out rollers  21   a,    21   b  are rotated in the forward direction by the predetermined distance, which is equal to a length of the printing region along X axis printed by the single path of the carriage. Movement of the carriage  13  and rotation of the feed-in rollers  20   a,    20   b  and the feed-out rollers  21   a,    21   b  are performed alternately. 
         [0177]    Next, when a command indicating that print data to be printed on the next page (subsequent sheet) exists is received from the external device (S 16 : yes), the process proceeds to S 17 . In this case, when printing of the preceding sheet P is ended (S 17 : yes), it is determined whether the current flag is the first mode or the second mode (S 18 ). When the fag is the second mode (S 18 : second), the LF motor  42  continues to rotate in the forward direction and the feed-in drive roller  20   a,  feed-out drive roller  21   a  and supply roller  7  are continued to rotate in the forward direction (S 19 ). The controller has an additional procedure that starts continuous rotation of the supply roller  7  and the pair of feed-in rollers  20   a,    20   b  at a timing when printing operation of a preceding sheet is completed (S 17 ). Accordingly, the preceding sheet (preceding page) is discharged, and the following sheet (subsequent page) is conveyed to the print starting position. When the pair of feed-in rollers  20   a,    20   b  rotates by the predetermined amount after the sheet sensor  116  detected the front edge of the subsequent sheet P, the sheet is positioned at the print starting position. The supply roller  7  and the pair of feed-in rollers  20   a,    20   b  continues to rotate without stoppage until the pair of feed-in rollers  20   a,    20   b  rotates by the predetermined amount after the sheet sensor  116  detected the front edge of the sheet P. After this process, the step returns to S 15 , and printing on the next page (subsequent page) is started. 
         [0178]    This continuous rotation of the supply roller  7  and the pair of the feed-in roller makes the printing operation for a plurality of sheets faster. However, it is not essential, and the cyclic change that the supply roller  7  and the feed-in rollers  20   a,    20   b  rotate and stop alternately may be repeated continuously. In this case, the same cyclic change is repeated while the contact point between the roller and the sheet moves from the front edge of the preceding sheet through the intermediate portion and the back edge of the preceding sheet to the front edge of the subsequent sheet. The same cyclic change of the supply roller  7  and the feed-in rollers  20   a,    20   b  is repeated while the printing operation for a plurality of sheets is performed in the cautious feeding mode. 
         [0179]      FIG. 17  shows a state in which the preceding sheet P is discharged and the following sheet P is conveyed to the print starting position. During the period in which the second mode is set, the plurality of sheets P are continuously and sequentially fed/discharged without temporarily stopping sending of the sheet P by the feed-in drive roller  20   a  and the feed-in driven roller  20   b,  thus high-speed printing process can be performed. 
         [0180]    Next, a case in which control is performed when the print data for the subsequent sheet does not exist during execution of the second mode is explained. In step S 16  in  FIG. 21 , when the command indicating that the print data to be printed on the next page exists is not received (S 16 : no), that is, when the print data for the subsequent sheet P no longer exist, the sheet P (sheet) positioned at the printing region  210  is conveyed a predetermined distance in a feed-out direction (S 20 ). This predetermined distance is approximately three printing lines. When the sheet is sent by the predetermined distance (S 20 : yes), the flag is switched to the first mode (S 21 ). In this state, printing is executed on the sheet P positioned in the printing region  210  (S 17 ). When this printing operation is ended (S 17 : yes), the current flag is questioned (S 18 ). 
         [0181]    When it is determined in the step S 18  that the flag is the first mode (S 18 : first), the process control is executed on the subsequent sheet (S 30 ). The detail of this control is shown in the flowchart of  FIG. 22 . 
         [0182]    First, at a point of time when the printing of the one page of the preceding sheets P is ended (when the S 17  in  FIG. 21  is YES), it is determined whether the sheet sensor  116  is ON or not (S 31  in  FIG. 22 ). Specifically, it is determined whether the front edge section of the subsequent sheet P passes a section where the sheet sensor  16  exists. When the sheet sensor  116  is OFF (S 31 : no), that is, when the front edge of the subsequent sheet P does not yet reach the sheet sensor  116  (see  FIG. 18 ), the first half of the subsequent sheet P is positioned within the sheet guide  9  and the last half of this sheet P is positioned within the cassette  5 , thus the processing time is reduced if the subsequent sheet P 1  is returned to the paper cassette  5 . Further, when a sheet P which is not recorded is discharged through the printing region  210 , it involves an effort to set the sheet P 1  in the paper cassette  5  again, thus it is preferred that the subsequent sheet P 1  be returned to the paper cassette  5 . 
         [0183]    In the above case, in order to return the subsequent sheet P 1  to the paper cassette  5 , the supply roller  7  is rotated in the reverse direction (S 32  in  FIG. 22 ). In this case, the carriage  13  is moved in the direction of the arrow E in  FIG. 12  from the position of the printing region and the abutting piece  114   a  is positioned at the position  1  (Po 1 ). In this position, the switching gear  102  is geared with the intermittent feeding gear  113 , as shown in  FIG. 14 . When the LF motor  42  is rotated in the forward direction, the feed-in drive roller  20   a  and the feed-out driven roller  21   a  are rotated in the forward direction, thus the preceding sheet P is sent in the feed-out direction. On the other hand, the supply roller  7  is rotated in the reverse direction. When the supply roller  7  is rotated a predetermined amount in the reverse direction (S 33  in  FIG. 22 ) and then stopped (S 34 ), the subsequent sheet P 1  is returned to the stacking position in the paper cassette  5  (see  FIG. 19 ). 
         [0184]    At a point of time when printing of one page of the preceding sheet P is ended (when S 17  in  FIG. 21  is YES), when the sheet sensor  116  is ON (S 31  in  FIG. 22 : yes), the front edge section of the subsequent sheet P 1  passes the position where the sheet sensor  116  is present. In this case, the LF motor  42  is rotated in the reverse direction, the supply roller  7  is rotated forward, and the feed-in drive roller  20   a  is rotated in the reverse direction (S 35  in  FIG. 22 ). When executing S 35  in  FIG. 22 , the abutting piece  114   a  is positioned at the position  1  (Po 1 ) and is in a connection state shown in  FIG. 13 . In this state, the LF motor  42  is rotated a predetermined amount (S 36  in  FIG. 22 ), and the front edge of the subsequent sheet P 1  is aligned with the contact line  212  between the feed-in drive roller  20   a  and the feed-in driven roller  20   b.  In this state, the rotation of the LF motor  42  is stopped once and the rotation of the feed-in roller  20   a  and of the supply roller  7  is also stopped (S 37  in  FIG. 22 ). Subsequently, by rotating the LF motor  42  in the forward direction and the feed-in drive roller  20   a  and the feed-out drive roller  21   a  are rotated in the forward direction to discharge the sheet P 1 . In this state, the supply roller  7  is rotated in the reverse direction (see  FIG. 19 ), thus when the supply roller  7  is rotated a predetermined amount in the reverse direction (S 39 ), a subsequent sheet P 2  which follows the sheet P 1  is returned to the paper cassette  5 . 
         [0185]    It should be noted that, as shown in  FIG. 16 , the distance from a contact line  214  between the stacked sheets P on the paper cassette  5  and the supply roller  7  to the contact line  212  between the feed-in drive roller  20   a  and feed-in driven roller  20   b  along the sheet guide  9  is L 1 , and the distance from the contact line  214  between the stacked sheets P on the paper cassette  5  and the supply roller  7  to the separating member in the separating inclined surface  8  is L 2 . 
         [0186]    In a case of the continuous feeding operation, at the moment when the back edge of a preceding sheet P is removed from the contact line  214  between the sheet P and the supply roller  7 , the subsequent sheet P 1  is conveyed by the rotation of the supply roller  7 , thus the distance L 2  becomes a lapping amount (overlapping amount) along the direction of conveyance of the preceding sheet P and a subsequent sheet P 1 . The difference between the L 2  and L 1  is set so as t to be longer than a predetermined value, and the difference between the circumferential speed V 1  of the feed-in roller  20   a  and the circumferential speed V 2  of the supply roller  7  (V 1 &gt;V 2 ) (V 1 −V 2 ) is set so as to be at least a predetermined value, whereby when the back edge of the preceding sheet P passes through the contact line  212  between the feed-in drive roller  20   a  and the feed-in driven roller  20   b,  the front edge of the subsequent sheet P 1  does not reach the contact line  212  between the feed-in drive roller  20   a  and the feed-in driven roller  20   b.  Specifically, when passing through between the feed-in drive roller  20   a  and the feed-in driven roller  20   b,  an appropriate space (sheet interval) can be formed between the back edge of the preceding sheet P and the front edge of the subsequent sheet P 1 . Therefore, even when a plurality of sheets P are fed/conveyed continuously, all print data corresponding to each sheet P can be printed completely in the printing region  210 . Specifically, in the printing region  210 , the back edge of the preceding sheet P and the front edge of the subsequent sheet P 1  do not overlap with each other, thus printing is not performed on the space between the both sheets. In the above case, when the back edge of the preceding sheet P is removed from the supply roller  7  and the conveyed by only the pair of feed-in rollers  20   a,    20   b,  control is performed such that a supply process for the subsequent sheet P 1  is started by the supply roller  7 , whereby an effect is obtained in which the above sheet interval can be obtained more securely. 
         [0187]    According to the present invention, as described above, in the configuration in which the sheets P which are stacked on the paper cassette  5  can be supplied to the sheet guide  9  one by one by the supply roller  7 , and this supplied sheet P is conveyed to the printing region  210  by the pair of feed-in rollers  20   a,    20   b,  the pair of feed-in rollers  20   a,    20   b  is configured by the feed-in drive roller  20   a  driven by the LF motor  42  and the feed-in driven roller  20   b  pressurized by the feed-in drive roller  20   a.  Further, the power of the pair of feed-in rollers  20   a,    20   b  sending the sheets is set larger than the sending power of the supply roller  7 , and the circumferential speed of the feed-in drive roller  20   a  is set higher than the circumferential speed of the supply roller  7 . Moreover, the control means is provided so that control is performed such that, when the print data for the subsequent sheet P 1  exists, the feed-in roller  20   a  and the supply roller  7  are continuously rotary driven in the same direction. Therefore, the plurality of sheets P can be continuously and successively conveyed to the printing region  210  and printed continuously and successively, thus an effect is obtained in which the printing operation on the plurality of sheets P can be executed at high speed. 
         [0188]    Further, the feed-in drive roller  20   a  and the supply roller  7  are configured so as to be rotary driven by the single drive motor (LF motor)  42 , thus an effect is obtained in which a configuration for feeding and supplying the sheets can be made simple. 
         [0189]    In the present embodiment, since the front end of the arm  6   a  is provided with the supply roller  7 , drawing operation of the paper cassette  5  does not obstruct the supply roller  7 . Further, when a piece of sheet is in contact with the feed-in dive roller  20   a  and the supply roller  7 , the arm  6   a  is oscillated, whereby the supply roller  7  is prevented from obstructing the pair of feed-in rollers  20   a,    20   b  sending the sheets. 
         [0190]    Since the power transmission switching means  100  is provided, switching can be performed between an intermittent feeding operation for positioning the cut sheets one by one and sending them to the printing region  210 , and a high-speed feeding operation for continuously and successively sending the plurality of cut sheets. The operation for this switching is executed using the movement of the carriage  13 , thus excess mechanisms are not required. 
       Second Embodiment  
       [0191]    Hereinafter, only the differences between the first embodiment and the second embodiment are described and the overlapping explanations are omitted. 
         [0192]    The multifunction device  1  in the second embodiment comprises, as shown in  FIG. 23 , the lower section case.  2  in which a first lower section case  2   a  and a second lower section case  2   b  are stacked. An opening section  2   c  is formed on a front side of the first lower section case  2   a  and, as shown in  FIG. 24 , a first paper cassette  5 A is inserted therein such that it can be drawn. As shown in  FIG. 23 , an opening section  2   d  is formed on a front side of the second lower section case  2   b  and, as shown in  FIG. 24 , a second paper cassette  5 B is inserted therein such that it can be drawn. 
         [0193]      FIG. 23  shows a state in which the first paper cassette  5 A is removed from the lower section case  2  and the second paper cassette  5 B is stored in the lower section case  2 . 
         [0194]    The upper section case  3  is disposed on an upper side of the lower section case  2 . The upper section case  3  is provided with a script automatic sending device  32 . 
         [0195]    A discharge space is secured on a lower section of the operation panel section  30 . The discharge space is configured with a space located higher than the paper cassette  5 A in the opening section  2   c.    
         [0196]    As shown in  FIG. 24 , a first supply unit  6  having a first supply roller  7  is disposed on an upper section of the first paper cassette  5 A. An U-shaped first conveying path  9  is disposed on a rear section of the first paper cassette  5 A. Further, an inclined separating board  15  for separating sheets is disposed on a front side of the first paper cassette  5 A. This inclined separating board  15  protrudes forward at a center in a width direction (Y-axis direction) of a sheet P, and is formed into a convex shape so as to step backward as it approaches right and left end sections in the width direction of the sheet P. Further, a central section in the width direction of the sheet P is provided with a saw-like elastic separating pad (not shown) which abuts on the front edge of the sheet P and promotes separation of the sheet P. 
         [0197]    An upper end section of the arm  6   a  of the first supply unit  6  is swingably installed on the bottom surface  39   a  of the frame  39  in a vertical direction, and the supply roller  7  is provided at a lower end (free end section) of the arm  6   a.  One uppermost sheet of a plurality of sheets stacked on the first paper cassette  5 A is taken out from the first paper cassette  5 A and sent to the first conveying path  9  by a cooperation between the supply roller  7  and the elastic separating pad of the inclined separating board  15 . 
         [0198]    As shown in  FIG. 24 , the second paper cassette  5 B is disposed in a lower section of the first paper cassette  5 A. A front side of the second paper cassette  5 B is also provided with an inclined separating board  16  having an elastic separation pad for separating sheets, the inclined separating board  16  having the configuration same as that in the first paper cassette  5 A. An upper end of an arm  17   a  of a second supply unit  17  is installed in the second lower section case  2   b  so as to be able to swing around a drive shaft  18  in the vertical direction. A train  51  of a plurality of mating gears for transmitting a torque from the drive shaft  18  to a second supply roller  19  disposed on a front end of the arm  17   a  is disposed on the arm  17   a.    
         [0199]    A second conveying path  22  is formed astride the first lower section case  2   a  and the second lower section case  2   b.  One uppermost sheet of a plurality of sheets stacked on the second paper cassette  5 B is taken out from the second paper cassette  5 B and sent to the second conveying path  22  by a cooperation between the second supply roller  19  and the elastic separating pad of the inclined separating board  16 . 
         [0200]    The sheet which is sent to the first conveying path  9  and the sheet which is sent to the second conveying path  22  are both sent to a space between a pair of feed-in rollers  20  and further sent to the printing region  210  between a lower surface of the printing head  12  and the platen  11 . 
         [0201]    In the second embodiment, as shown in  FIG. 25 , a torque from the LF motor  42  is selectively transmitted from a right end section of the feed-in drive roller  20   a  via the power transmission switching means  100  to any of the first supply roller  7  of the first supply unit  6 , the second supply roller  19  of the second supply unit  17 , and the maintaining mechanism  36 . 
         [0202]    Next, a configuration of the power transmission switching means  100  is explained with reference to  FIG. 25  through  FIG. 44 . The power transmission switching means  100  selects any of an intermittent feeding mode of an upper cassette, a continuous feeding mode of the upper cassette, a continuous feeding mode of a lower cassette, and a maintenance mode. In the intermittent feeding mode of the upper cassette, when the LF motor  42  rotates in the reverse direction the supply roller  7  is rotated in the forward direction. In the continuous feeding mode of the upper cassette, when the LF motor  42  rotates in the forward direction the supply roller  7  is rotated in the forward direction. In the continuous feeding mode of the lower cassette, when the LF motor  42  rotates in the forward direction the second supply roller  19  is rotated in the forward direction. In the maintenance mode the torque of the LF motor  42  is transmitted to the maintaining mechanism  36 . 
         [0203]    In the intermittent feeding mode of the upper cassette, when the LF motor  42  rotates in the reverse direction, the feed-in drive roller  20   a  rotates in a direction of returning a sheet to the sheet guide  9 , and the first supply roller  7  rotates in a direction of taking the sheet out from the upper cassette  5 A and sending it to the sheet guide  9 . Thereafter, the LF motor  42  rotates in the forward direction, the feed-in drive roller  20   a  rotates in a direction of sending the sheet toward the printing region  210 , and the first supply roller  7  rotates in a direction of returning the sheet to the upper cassette  5 A. 
         [0204]    In the continuous feeding mode of the upper cassette, the LF motor  42  rotates in the forward direction, the feed-in drive roller  20   a  rotates in a direction of sending the sheet toward the printing region  210 , and the first supply roller  7  rotates in a direction of taking the sheet out from the upper cassette  5 A and sending the sheet toward the sheet guide  9 . 
         [0205]    In the continuous feeding mode of the lower cassette, the LF motor  42  rotates in the forward direction, the feed-in drive roller  20   a  rotates in a direction of sending the sheet toward the printing region  210 , and the second supply roller  19  rotates in a direction of taking the sheet out from the lower cassette  5 B and sending the sheet toward the sheet guide  22 . 
         [0206]    As long as the modes are not switched by the power transmission switching means  100 , the selected mode is maintained. 
         [0207]    As described in the first embodiment, the torque from the LF motor  42  is transmitted to the feed-in drive roller  20   a.  A right end section of the feed-in drive roller  20   a  (upper section of the maintaining mechanism  36 ) is provided with a long gear  101  (see  FIG. 42 ) configuring the power transmission switching means  100 . A position adjacent to the gear  101  is provided with the switching gear  102  which is always engaged with the gear  101 . The switching gear  102  is slidable with respect to the spindle  103  extending in the Y-axis direction. 
         [0208]    As shown in  FIG. 44 , when the carriage  13  is located at a position facing a sheet P, the carriage  13  is separated from the maintaining mechanism  36 , thus the carriage  13  does not press the abutting piece  104   a  in the direction of the arrow E. In this state, the first biasing force  106   a  causes the second block  105 , the first block  104  and the switching gear  102  to slide in the direction of the arrow C along the spindle  103 . The abutting piece  104   a  is positioned at the first set section  111 . This position is called “position  1 ” (Po 1 ). At this moment, the switching gear  102  is engaged with the intermittent feeding gear  113  of the upper cassette. 
         [0209]    When the carriage  13  moves in the direction of the arrow E, the first engaging step section  13   a  of the carriage  13  presses the abutting piece  104   a  in the direction of the arrow E. As a result, the switching gear  102 , first block  104  and second block  105  slide in the direction of the arrow E along the spindle  103 . The position where the carriage  13  is positioned at the second set section  112  of the abutting section  104   a  is called “position  2 ” (Po 2 ). In the case of the position  2 , the switching gear  102  is engaged with the continuous feeding gear  114  of the upper cassette. This state is shown in  FIG. 42 . 
         [0210]    When the carriage  13  further moves in the direction of the arrow E, the first engaging step section  13   a  of the carriage  13  presses the abutting piece  104   a  in the direction of the arrow E. The pressed abutting piece  104   a  climbs over a convex section  108   a  and reaches the position  3  (Po 3 ). In the case of the position  3 , the switching gear  102  is engaged with a continuous feeding gear  121  of the lower cassette. 
         [0211]    When the carriage  13  further moves in the direction of the arrow E, the first engaging step section  13   a  of the carriage  13  presses the abutting piece  104   a  in the direction of the arrow E. The pressed abutting piece  104   a  proceeds to the horizontal groove section  109   a  from the inclined groove section  109   b.  Once the abutting piece  104   a  enters the horizontal groove section  109   a,  the second engaging step section  13   b  of the carriage  13  presses the abutting piece  104   a.  When the abutting piece  104   a  is in the position immediately after entering the horizontal groove section  109   a  (this position is called “position  4 ” (Po 4 )), the switching gear  102  is engaged with the maintenance gear  115 . 
         [0212]    The switching gear  102 , intermittent feeding gear  113 , continuous feeding gear  114  and maintenance gear  115  are all spur gears, and the bevel gear  115   a  having a large diameter is fixed to a side surface of the maintenance gear  115 . When the carriage  13  further moves from the position  4  (Po 4 ) in the direction of the arrow E, a side surface of the switching gear  102  abuts on the bevel gear  115   a,  whereby the switching gear  102  is inhibited from moving any further in the direction of the arrow E and thus continues to be engaged with the maintenance gear  115 . The abutting piece  104   a  is pressed by the second engaging step section  13   b  of the carriage  13  and then positioned at a back end section of the horizontal groove section  109   a  (right end section shown in  FIG. 44  and  FIG. 43 ). This position is called “position  5 ” (Po 5 ) and is a home position (original position). In this state, the switching gear  102  and the first block  104  are separated from each other. 
         [0213]    Contrary to the above state, when the carriage position  13  moves from the position  5  (Po 5 ) in the direction of the arrow C, the abutting piece  104   a  moves from the horizontal groove section  109   a  to the inclined groove section  109   b.  At this moment, the abutting piece  104   a  is received by a step between the first engaging step section  13   a  and the second engaging step section  13   b  of the carriage  13 , thus the abutting piece  104   a  moves above the regulating piece  110  of  FIG. 44  in the direction of the arrow C. The abutting piece  104   a  abuts on a left inclined surface of the inclining groove section  109   b  shown in  FIG. 44  while sliding on the regulating piece  110 , thereafter moves to the left inclined surface and then is engaged with the first set section  111 . After the carriage  13  moves to the position  5  in the E direction and then moves in the C direction, the abutting piece  104   a  moves from the position  1  to the position  2 , from the position  2  to the position  3 , from the position  3  to the position  4 , from the position  4  to the position  5 , and from the position  5  to the position  1 . The carriage  13  repeats the movement of moving to the right end in the E direction and then moving in the C direction, while the abutting piece  104   a  repeats the cycle of moving from the position  1 → 2 → 3 → 4 → 5 → 1 . 
         [0214]    When the carriage  13  moves in the E direction to the position  1  and then moves in the C direction, the switching gear  102  is held at the position  1 . When the carriage position  13  moves to the position  2  in the E direction and then moves in the C direction, the switching gear  102  is held in the position  2 . When the carriage  13  moves in the E direction to the position  3  and then moves in the C direction, the switching gear  102  is held at the position  3 . 
         [0215]    At the position  1  (Po 1 ) where the switching gear  102  is engaged with the intermittent feeding gear  113  of the upper cassette, the same phenomena as in the first embodiment are obtained. 
         [0216]    At the position  2  (Po 2 ) where the switching gear  102  is engaged with the continuous feeding gear  114  of the upper cassette, the same phenomena as in the first embodiment are obtained. 
         [0217]    At the position  3  (Po 3 ) where the switching gear  102  is engaged with the continuous feeding gear  121  of the lower cassette, rotation of the feed-in drive roller  20   a  is transmitted to the drive shaft  18  of the second supply unit  17  via a gear train  122  having a plurality of gears, as shown in  FIG. 25 . In this state, the LF motor  42  rotates in the forward direction, the feed-in drive roller  20   a  rotates in a direction of sending a sheet toward the printing region  210 , and the second supply unit  19  rotates in a direction of taking the sheet out from the lower cassette  5 B and sending the sheet toward the sheet guide  22 . 
         [0218]    At the position  4  (Po 4 ) where the switching gear  102  is engaged with the maintenance gear  115 , the same phenomena as in the case of the position  3  (Po 3 ) in the first embodiment are obtained. 
         [0219]    The power transmission switching means  100  of the present embodiment comprises: a plurality of drive power transmission sections (intermittent feeding gear  113  of the upper cassette, the continuous feeding gear  114  of the upper cassette, the continuous feeding gear  121  of the lower cassette, and the maintenance gear  115 ); the switching gear  102 , which is a switching section for causing the carriage  13  to alternatively transmit power from the drive gear  101 , which is a drive output section, to the drive power transmitting section, in accordance with the position of movement along the main scanning direction; and the position holding means (first, second, third set sections  111 ,  112 ,  108 ) for holding the position of movement along the main scanning direction of the switching gear  102 . The switching gear  102  is biased along the main scanning direction from both directions, the switching gear  102  is moved and selectively engaged with one of the plurality of drive power transmission sections by simply moving the carriage  13  in the main scanning direction. Further, in the present invention, the position holding means exists every selected engaging section between the switching gear  102  and the drive power transmission section. Therefore, even if the carriage  13  separates from the switching gear  102  and moves to the image recording region, the above engagement, i.e. the power transmission state, can be held. As a result, even in either the continuous feeding operation or intermittent feeding operation, the drive power transmission state is selected, thus an effect is obtained in which the time required in operations for moving the carriage  13  and the like is reduced and the image recording operation can be performed at high speed and efficiently. 
         [0220]    In the intermittent feeding mode, switching is performed between a state in which the supply roller  7  is rotated in the forward direction and the feed-in drive roller  20   a  is rotated in the reverse direction, and a state in which the supply roller  7  is rotated in the reverse direction and the feed-in drive roller  20   a  is rotated in the forward direction. In the continuous feeding mode, the feed-in drive roller  20   a  and the supply roller  7  are continuously rotary driven in the same direction. In either mode, even when the carriage  13  returns to the image recording region, the power transmission switching means  100  is held in the selected mode, thus it is not necessary to move the carriage and select a mode every time one sheet is printed. When executing the intermittent feeding mode using a conventional technology, it is necessary to move the carriage  13  to operate the power transmission switching means  100  every time when the position of a sheet is aligned using the feed-in roller which is rotated in the reverse direction. In the present embodiment as well, such an operation is required and effective printing can be executed. 
         [0221]    Moreover, the pair of feed-in rollers  20   a,    20   b  is disposed on an upstream side of a conveying direction of a sheet P, which is higher than the carriage  13 , the first supply roller  7  and the second supply roller  19  are disposed on the further upstream side, and these components are rotated by a single LF motor  42 , thus an effect is obtained in which the configuration of feeding/conveying the sheet can be made simple. 
         [0222]    The present invention is not limited to the embodiments explained by the above descriptions and the figures, and thus can be changed and implemented in various ways without departing from the scope of the principles of the present invention. For example, the paper cassette may be disposed to configure a plurality of steps (at least three steps), whereby a plurality of operation modes such as the above continuous feeding operation and intermittent feeding operation may be executed when feeding sheets for each step. The number of position holding sections provided in the power transmission switching means  100  may be increased. 
         [0223]    Moreover, one paper cassette may be provided and an operation mode may be selected from at least three modes. The position holding section corresponding to each operation mode may be provided. In the above case as well, an operation mode for performing a maintenance work may be added. 
         [0224]    The present invention is not limited to the embodiments explained by the above descriptions and the figures, and thus can be changed and implemented in various ways without departing from the scope of the principles of the present invention. For example, the paper cassette may be disposed to configure a plurality of steps, whereby the above continuous feeding operation may be executed when feeding sheets for each step.