Abstract:
A recording section is configured to perform a recording operation with respect to a recording medium. An ejector is configured to eject the recording medium transported from the recording section to the outside of the recording apparatus. The ejector is provided with a plurality of press members. A switcher selectively causes none or one of the press members to abut against the recording medium.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to a recording apparatus that performs a recording operation by supplying a recording medium to a recording section and ejects the recording medium from an ejecting section, as well as to a like liquid ejection apparatus.  
         [0002]     Among large-size recording apparatus capable of recording on up to a sheet (recording medium) of a relatively large size such as the A4 to A2 size of the JIS standard are ink jet printers. In such large-size ink jet printers, a sheet is supplied from and ejected to the front side for the following reason: unlike in small-size ink jet printers, it is difficult to supply a sheet from the back side and eject it to the front side because relatively heavy sheets need to be handled.  
         [0003]     An ink jet printer is known in which a sheet supply tray and a sheet ejection tray are disposed on the front side. A sheet that is accommodated in the sheet supply tray is taken out by a sheet supply roller and then fed to a platen of a recording section by transporting the sheet by a sheet feeding roller and an associated follower roller while holding it between them. Recording is performed on the sheet by discharging ink droplets from a recording head, and the sheet is then ejected to the ejection tray by transporting it by a sheet ejection roller and a spur roller as an associated follower roller while holding it between them (cf., Japanese Patent Publication No. 11-124271A).  
         [0004]     In the above ink jet printer, since the spur roller is used as the follower roller that is associated with the sheet ejection roller, scratches may be formed on the recording face of a sheet to lower the recording accuracy depending on the attribute of the sheet.  
         [0005]     Further, where the above ink jet printer performs recording on a portion of a sheet close to its trailing edge, the trailing edge of the sheet may rise though the recording is going on because the trailing edge of the sheet is no longer held between the sheet feeding roller and an associated follower roller. This may result in a problem that recording unevenness occurs because the interval between the sheet and the recording head becomes non-uniform to vary the flying distance of ink droplets or the sheet touches the recording head and is thereby stained.  
       SUMMARY OF THE INVENTION  
       [0006]     It is therefore an object of the present invention to provide a recording apparatus capable of maintaining highly accurate recording as well as a like liquid ejection apparatus.  
         [0007]     In order to achieve the above object, according to the invention, there is provided a recording apparatus, comprising: 
        a recording section, configured to perform a recording operation with respect to a recording medium;     an ejector, configured to eject the recording medium transported from the recording section to the outside of the recording apparatus, the ejector comprising a plurality of press members; and     a switcher, which selectively causes none or one of the press members to abut against the recording medium.        
 
         [0011]     With this configuration, particularly in ejecting a sheet or paper whose recording face is prone to be scratched, the recording face can be prevented from being scratched by separating the press member, whereby the recording accuracy can be kept high.  
         [0012]     Preferably, the state of the press members is selected in accordance with a property of the recording medium.  
         [0013]     With this configuration, an optimum ejecting condition can be set in accordance with the property of the recording medium. In a case where it is configured an automatic switching operation can be performed, the scratching on the recording face due to the wrong switching operation of the user can be reliably avoided.  
         [0014]     Preferably, the recoding section comprises: a guide face which supports the recording medium being transported; and a support member retractably projected from the guide face; and the switcher selectably causes the support member to be projected or retracted from the guide face.  
         [0015]     With this configuration, projecting the supporting member particularly when a trailing end of the recording medium becomes a free end, the trailing end is supported so as to prevent from being lifted up. Accordingly, it is possible to execute a recording operation with high accuracy and the termination of the recording member can be avoided.  
         [0016]     Here, it is preferable that the states of the press members and the support member are interlockingly selected in accordance a property of the recording medium.  
         [0017]     Preferably, the ejector comprises a revolver in which the press members are arranged in a circumferential direction thereof. The switcher revolves the revolver such that one of the press members or a space between the press members is selectively opposed to the recording medium.  
         [0018]     With this configuration, the mechanism of the switcher can be made simple so that the switching operation can be reliably executed.  
         [0019]     According to the invention, there is also provided a liquid ejection apparatus, comprising: 
        a liquid ejecting section, configured to eject a liquid droplet toward a target medium;     an ejector, configured to eject the target medium transported from the liquid ejecting section to the outside of the liquid ejection apparatus, the ejector comprising a plurality of press members; and     a switcher, which selectively causes none or one of the press members to abut against the target medium.        
 
         [0023]     Preferably, the state of the press members is selected in accordance with a property of the target medium.  
         [0024]     Preferably, the liquid ejecting section comprises: a guide face which supports the target medium being transported; and a support member retractably projected from the guide face. The switcher selectably causes the support member to be projected or retracted from the guide face.  
         [0025]     Here, it is preferable that the states of the press members and the support member are interlockingly selected in accordance a property of the target medium.  
         [0026]     Preferably, the ejector comprises a revolver in which the press members are arranged in a circumferential direction thereof. The switcher revolves the revolver such that one of the press members or a space between the press members is selectively opposed to the target medium.  
         [0027]     With the above configurations, it is possible to provide a liquid ejection apparatus having the respective advantages described the above. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0028]      FIG. 1  is a perspective view of an ink jet printer according to one embodiment of the invention;  
         [0029]      FIG. 2  is a perspective view of a tray unit in the printer of  FIG. 1 ;  
         [0030]      FIG. 3  is a perspective view showing a used state of the tray unit of  FIG. 2 ;  
         [0031]      FIG. 4  is a perspective view showing another used state of the tray unit of  FIG. 2 ;  
         [0032]      FIG. 5  is a schematic section view showing an internal configuration of the printer of  FIG. 1 ;  
         [0033]      FIGS. 6A and 6B  are schematic views showing a contact state of a sheet on a hopper and a sheet feeding roller in the printer of  FIG. 1 ;  
         [0034]      FIG. 7  is a schematic section view of a modified example of the internal configuration of the printer of  FIG. 1 ;  
         [0035]      FIG. 8  is a perspective view showing a follower roller driving device and its periphery in the printer of  FIG. 7 ;  
         [0036]      FIGS. 9 and 10  are section views showing a case where only a follower roller of a sub roller is operated in the printer of  FIG. 7 ;  
         [0037]      FIGS. 11 and 12  are section views showing a case where both of the follower roller of the sub roller and a follower roller of the sheet feeding roller are operated in the printer of  FIG. 7 ;  
         [0038]      FIG. 13  is a perspective view of a periphery of a carriage in the printers shown in  FIGS. 1 and 7 ;  
         [0039]      FIG. 14  is a plan view of the configuration shown in  FIG. 13 ;  
         [0040]      FIG. 15  is a section view taken along a line XV-XV in  FIG. 14 ;  
         [0041]      FIG. 16  is a perspective view showing details of a supporting member shown in  FIG. 13 ;  
         [0042]      FIG. 17  is a section view taken along a line XVII-XVII in  FIG. 16 ;  
         [0043]      FIG. 18  is a plan view showing a platen gap adjusting mechanism and its periphery in the printers shown in  FIGS. 1 and 7 ;  
         [0044]      FIG. 19A  is a right side view of the configuration shown in  FIG. 18 ;  
         [0045]      FIG. 19B  is a left side view of the configuration shown in  FIG. 18 ;  
         [0046]      FIG. 20  is a perspective view of the configuration shown in  FIG. 19A ;  
         [0047]      FIGS. 21A and 21B  are perspective views of the configuration shown in  FIG. 19B ;  
         [0048]      FIGS. 22 and 23  are perspective views showing details of a follower roller unit and a supporting rib unit in the printers shown in  FIGS. 1 and 7 ;  
         [0049]      FIG. 24A  is a left side view of the follower roller unit and the supporting rib unit;  
         [0050]      FIG. 24B  is a plan view of the follower roller unit and the supporting rib unit;  
         [0051]      FIG. 24C  is a right side view of the follower roller unit and the supporting rib unit;  
         [0052]      FIGS. 25A  to  25 C are side views showing state switching of the follower roller unit and the supporting rib unit;  
         [0053]      FIG. 26  is a table showing conditions of the state switching of the follower roller unit and the supporting rib unit;  
         [0054]      FIG. 27  is a side view showing an entire configuration of the follower roller driving device, the platen gap adjusting mechanism, and a driving mechanism for the follower roller unit and the supporting rib unit in the printer of  FIG. 7 ;  
         [0055]      FIG. 28  is a view showing a main part of the configuration shown in  FIG. 27 ;  
         [0056]      FIG. 29  is a perspective view showing an entire configuration of a mechanism for transmitting a driving force of a motor in the printer of  FIG. 7 ;  
         [0057]      FIGS. 30A and 30B  are views showing a main part of the configuration shown in  FIG. 29 ;  
         [0058]      FIG. 31  is a perspective view showing a sensor and its periphery in the printers shown in  FIGS. 1 and 7 ; and  
         [0059]      FIGS. 32A  to  33 B are schematic section views showing transporting operation of the sheet in the printer of  FIG. 7 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0060]     An embodiment of the present invention will be hereinafter described in detail with reference to the accompanying drawings.  
         [0061]     As shown in  FIG. 1 , an ink jet printer (recording apparatus)  100  according to an embodiment of the invention is a large-size, desk-top printer capable of recording on what is called cut sheets of a relatively large size such as the A4 to A2 size of the JIS standard and an equivalent roll of paper. The inside of the ink jet printer  100  is entirely covered with an housing  101  that generally assumes a rectangular parallelepiped shape that is long in the width direction.  
         [0062]     The top face of the housing  101  is formed with a rectangular window  102 , which is covered with a transparent or semi-transparent window cover  103 . The window cover  103  is attached so as to be rotatable in directions indicated by arrow a in  FIG. 1  about a rotation axis that is located on the rear side. A user can perform maintenance work or the like on the internal mechanisms through the window  102  by lifting up the window cover  103  and thereby opening the window  102 .  
         [0063]     Cartridge chambers  104  into and from which plural ink cartridges are to be inserted and removed are formed at the front-right and front-left positions of the housing  101 . Recording inks of several colors are stored in the respective ink cartridges. The cartridge chambers  104  are covered with transparent or semi-transparent cartridge covers  105 , respectively. Each cartridge cover  105  is attached so as to be rotatable in directions indicated by arrow b in  FIG. 1  about a rotation axis that is located at the bottom. The user can perform ink cartridge replacement work or the like by opening a cartridge chamber  104  by weakly pushing the cartridge cover  105  and thereby unlocking a locking portion.  
         [0064]     A control panel  110  by which to input an instruction of a printer operation is provided in a portion of the housing  101  that is located over the front-right cartridge chamber  104 . The control panel  110  is provided with buttons  111  such as a power button for turning on or off the power, buttons for operations for paper leading end positioning, ink flashing, etc., and buttons for image processing etc., a liquid crystal panel  112  for displaying various statuses, and other members. The user can manipulate the buttons  111  while watching the liquid crystal panel  112  to check displayed information.  
         [0065]     A tank chamber  106  into and from which a waste liquid tank  120  is to be inserted and removed is formed under the front-right cartridge chamber  104 . The waste liquid tank  120  stores waste ink that is discarded at the time of cleaning of a recording head  162  (see  FIG. 5 ) or replacement of an ink cartridge. The user can perform, for example, work of discarding the waste ink stored in the waste ink tank  120  by drawing out the waste ink tank  120 .  
         [0066]     A paper supplying section  130  for supplying a part of rolled paper is disposed at the rear of the housing  101  so as to project in a top-rear direction. A rolled paper holder (not shown) in which one roll of paper can be set is provided inside the paper supplying section  130 , and a flap-type rolled paper cover  131  that can be opened and closed is attached to the paper supplying section  130  on the front side so as to cover the rolled paper holder. The user can perform, for example, work of attaching or removing a roll of paper by lifting up the rolled paper cover  131  and thereby opening the paper supplying section  130 . The top face of the rolled paper cover  131  is formed into a sheet supply guide face capable of guiding cut sheets for manual feeding.  
         [0067]     A sheet supplying/ejecting section  140  into and from which a tray unit  200  to be loaded with unrecorded cut sheets and recorded cut sheets or recorded parts of rolled paper is to be inserted and removed is formed in the housing  101  at the front-center, that is, between the two cartridge chambers  104 . The sheet supplying/ejecting section  140  is formed so as to also allow manual feeding of thick sheets that cannot be bent while being transported.  
         [0068]     The tray unit  200  is fixed to the sheet supplying/ejecting section  140  in such a manner that the front portion of the tray unit  200  is inserted in the sheet supplying/ejecting section  140  and the rear portion is projected therefrom. The tray unit  200  assumes a cassette-like shape; unrecorded cut sheets are stacked and accommodated inside and recorded and ejected cut sheets or parts of rolled paper are stacked thereon. A detailed structure of the tray unit  200  will be described below with reference to  FIGS. 2-4 .  
         [0069]     As shown in  FIG. 2 , the tray unit  200  has a box-shaped sheet supply tray  210  and a lid-shaped sheet ejection tray  230  that covers the sheet supply tray  210  from above. Capable of expansion and contraction in the sheet supplying/ejecting direction, the tray unit  200  can be accommodated compactly while not in use and can accommodate cut sheets of various sizes while in use.  
         [0070]     To be mounted with cut sheets in a stacked manner, as shown in  FIG. 3 , a rolled paper guiding section  240  is made flush with the top face of a sheet ejection member  239   a  to form a flat plane together with the top face of the sheet ejection member  239   a . With this measure, cut sheets that are ejected after passing by a sheet ejection roller  155  (see  FIG. 5 ) are stacked smoothly on an ejected sheet receiving face that is formed by the rear and bottom faces of a guide portion  145  having an L-shaped cross section and the top faces of sheet ejection members  239   a - 239   d.    
         [0071]     Sponge mats  145   a  are pasted on the bottom face of the guide portion  145 . The sponge mats  145   a  have a slip-preventing function of preventing a phenomenon that when a second cut sheet comes in a state that a first cut sheet is already mounted, the head of the second cut sheet pushes the first cut sheet and makes it fall from the ejected sheet receiving face.  
         [0072]     On the other hand, to stack cut parts of rolled paper, as shown in  FIG. 4 , the user hooks his finger on a first guide plate  241  of the rolled paper guiding section  240  that is in the same plane as the top face of the sheet ejection member  239   a  and turns it rearward. As a result, second guide plates  242  are pulled by the first guide plate  241 , whereby their one ends in the longitudinal direction are lifted up and the other ends in the longitudinal direction slide rearward along respective grooves  239   aa  that are formed in the top face of the sheet ejection member  239   a . The user turns the first guide plate  241  until the first guide plate  241  and the second guide plates  242  form an acute angle.  
         [0073]     As a result, the one ends in the longitudinal direction of the second guide plates  242  come close to the top of the rear face of the guide portion  145  and the second guide plates  242  come to assume slide-like shapes. By virtue of this structure, even if a cut part of rolled paper that is ejected after passing by the sheet ejection roller  155  is curled, its tip portion does not go toward the guide portion  145  but slides on the slide-shaped second guide plates  242  and is guided onto the top faces of the sheet ejection members  239   a - 239   d . In this manner, cut parts of rolled paper are smoothly stacked on an ejected sheet receiving face that is formed by the top faces of the second guide plates  242  and the sheet ejection members  239   a - 239   d.    
         [0074]     As shown in  FIG. 5 , the sheet supplying/ejecting section  140 , a transporting section  150  and a recording section  160  that include important features of the invention, and other components are provided in the housing  101 . The sheet supplying/ejecting section  140  is equipped with a hopper  141  for supplying cut sheets, a sheet supply roller  142 , a separation member  143 , etc. The hopper  141  assumes a flat plate shape capable of being mounted with cut sheets, and is disposed in such a manner that one end is close to the sheet supply roller  142  and the separation member  143  and the other end is close to the bottom face of the sheet supply tray  210  of the inserted tray unit  200 . One end of a compression spring  144  is attached to the bottom face of the housing  101  and the other end is attached to the back face of the hopper  141  at its one end. The hopper  141  is rotated about the other end as the compression spring  144  expands or contracts.  
         [0075]     The sheet supply roller  142 , which has a D-shaped cross section having a cut, friction-transports cut sheets from the hopper  141  by rotating intermittently. The separation member  143 , which has a rough top face, friction-separates lower cut sheets from the uppermost one when plural cut sheets are supplied by the sheet supply roller  142 . A relationship between the cut sheets mounted on the hopper  141  and the sheet supply roller  142  will now be described with reference to  FIGS. 6A and 6B .  
         [0076]      FIG. 6A  shows a case that a maximum number of cut sheets P are mounted on the hopper  141 . Settings are made so that in this case when the hopper  141  is elevated the uppermost cut sheet P 1  does not touch the cut portion of the sheet supply roller  142  but touches an arc start point  142   a  or a point on the circumference that is slightly distant from the arc start point  142   a.    
         [0077]      FIG. 6B  shows a case that a minimum number (one) of cut sheet P 1  is mounted on the hopper  141 . The setting are made so that in this case when the hopper  141  is elevated the cut sheet P 1  touches a point  142   b  of the sheet supply roller  142  that is a little distant from the arc start point  142   a . The contact point  142   b  is such a point that the circumferential length between the contact point  142   b  and an arc end point  142   c  is the same as the interval a between the tip PS of the sheet P 1  and a contact point  151   a  of a sub roller  151  and an associated follower roller  152   a.    
         [0078]     With the above settings, if the number of cut sheets P mounted on the hopper  141  is smaller than or equal to the maximum number, the uppermost cut sheet P 1  is not released from the sheet supply roller  142  until the tip PS of the cut sheet P 1  reaches the contact point  151   a  of the sub roller  151  and an associated follower roller  152   a . Therefore, the cut sheet P 1  can be delivered reliably to the sub roller  151  and erroneous sheet delivery can be avoided.  
         [0079]     The transporting section  150  is equipped with the sub roller  151  and an associated follower rollers  152   a ,  152   b , and  152   c  for transporting a sheet, a sheet feeding roller  153  and an associated follower roller  154 , a sheet ejection roller  155  and an associated follower roller unit  156  that constitute an ejecting section, sensors  157   a  and  157   b  for detecting a sheet, and other components. To eject, to the sheet ejection tray  230 , a cut sheet that is supplied from the sheet supply tray  210 , the sub roller  151  transports the cut sheet along a U-shaped path (the transport direction is reversed) while holding it together with the follower rollers  152   a ,  152   b , and  152   c . To eject, to the sheet ejection tray  230 , a part of rolled paper that is supplied from the paper supplying section  130 , the sub roller  151  transports it while holding it together with the follower roller  152   c.    
         [0080]     The sheet feeding roller  153  sends out, to a platen  163 , a cut sheet that has been transported with reversal in direction or a supplied part of rolled paper while holding it together with the follower roller  154 . The sheet ejection roller  155  ejects, onto the sheet ejection tray  230 , a sheet or paper that has passed by the platen  163  while supporting it solely or together with the follower roller unit  156 . The sensor  157   a  detects a transport length of a supplied cut sheet at the time of skew taking. The sensor  157   b  detects a transport length of a cut sheet that has been transported with reversal in direction or a supplied part of rolled paper at the time of paper leading end positioning operation.  
         [0081]     The follower roller unit  156  is equipped with sets of a spur roller  11  and a smooth roller  12  that are brought in contact with or separated from the recording face of a sheet or paper being transported on the sheet ejection roller  155  and a switching shaft  14  for switching the rollers  11  and  12  between contact and separation. Having saw-toothed projections on the circumferential face, the spur roller  11  serves to transport a sheet or paper reliably by cutting into its recording face while holding it together with the sheet ejection roller  155 .  
         [0082]     Having a smooth circumferential face, the smooth roller  12  serves to transport a sheet or paper reliably by pressing on its recording face while holding it together with the sheet ejection roller  155 . The spur roller  11 , the smooth roller  12 , and a release portion  13  where neither the spur roller  11  nor the smooth roller  12  is provided are disposed around the switching shaft  14  at prescribed intervals in the circumferential direction, and plural sets of the rollers  11  and  12  and the release portion  13  are arranged in the axial direction at prescribed intervals.  
         [0083]     The above-configured follower roller unit  156  can arbitrarily switch between the spur rollers  11  and the smooth rollers  12 , between the spur rollers  11  and the release portions  13 , and between the smooth rollers  12  and the release portions  13  by rotating the switching shaft  14 . The switching between the spur rollers  11  and the release portions  13  or between the smooth rollers  12  and the release portions  13  is equivalent to bringing the spur rollers  11  or smooth rollers  12  into contact with or separating those from the recording face of a sheet or paper. Therefore, this switching makes it possible to adapt to many kinds of sheets and paper having respective attributes. Although the follower roller unit  156  is equipped with, in each set, the three kinds of single members, that is, the spur roller  11 , the smooth roller  12 , and the release portion  13 , the invention is not limited to such a case. One or more kinds of members may be combined arbitrarily, the number of members of each kind being two or more.  
         [0084]     The recording section  160  is equipped with a carriage  161 , a recording head  162 , the platen  163 , a support rib unit  164 , etc. As shown in  FIG. 13 , the carriage  161  is connected to a carriage belt  165 . As the carriage belt  165  is driven by a carriage motor  166 , the carriage  161  is moved together with the carriage belt  165  and is thereby reciprocated above a sheet or paper perpendicularly to the sheet transport direction being guided by a main guide shaft  61  and an auxiliary guide shaft  62 . The carriage  161  is mounted with the recording head  162  capable of discharging ink droplets toward an underlying sheet or paper.  
         [0085]     For example, the recording head  162  is equipped with plural black ink recording heads for discharging two kinds of black inks and plural color ink recording heads for discharging ink droplets of six colors of yellow, dark yellow, cyan, light cyan, magenta, and light magenta, respectively. The recording head  162  is provided with pressure generating chambers and nozzle orifices that communicate with the respective pressure generating chambers. Inks are stored in the pressure generating chambers and pressurized at a prescribed pressure, whereby ink droplets having a controlled size are discharged toward the sheet or paper on the platen  163 . A guide face  163   a  as the top face of the platen  163  supports and guides, by itself or together with the support rib unit  164 , a sheet or paper being transported from the sheet feeding roller  153  and the follower roller  154  to the sheet ejection roller  155  and the follower roller unit  156 .  
         [0086]     To enable recording on many kinds of sheets and paper having respective attributes (i.e., different thicknesses), a platen gap adjustment mechanism  170  for adjusting the gap between the nozzle formation face of the recording head  162  that is mounted on the carriage  161  and the recording face of a sheet or paper being transported on the guide face  163   a  of the platen  163  is provided (see  FIG. 18 ). The main guide shaft  61  and the auxiliary guide shaft  62  are rotatable about respective eccentric rotation axes. The platen gap adjustment mechanism  170  adjusts the gap so that it is always kept constant by rotating the main guide shaft  61  and the auxiliary guide shaft  62  synchronously.  
         [0087]     As shown in  FIG. 22 , the support rib unit  164  is equipped with support ribs (projections)  21  that protrude or retract from slits  163   b  that are formed in the guide face  163   a  of the platen  163  and a switching shaft  22  for switching the support ribs  21  between protrusion and retraction. Each support rib  21  is generally shaped like a triangular plate, and one arc-shaped apex portion protrudes from the guide face  163   a  and supports a sheet or paper. The two ends of the switching shaft  22  are pivotally supported by side faces  163   c  of the platen  163 . Plural support ribs  21  are fixed to the switching shaft  22  so as to be arranged in the axial direction at prescribed intervals.  
         [0088]     The above-configured support rib unit  164  makes it possible to arbitrarily switch between the one arc-shaped apex portion and the flat portion of each support rib  21  in the slit  163   b  that is formed in the guide face  163   a  of the platen  163  by rotating the switching shaft  22 . That is, the support rib  21  can be protruded by positioning the one arc-shaped apex portion of the support rib  21  with respect to the slit  163   b  that is formed in the guide face  163   a  of the platen  163 , and the support rib  21  can be retracted by positioning the flat portion of the support rib  21  with respect to the slit  163   b . Therefore, the above switching makes it possible to adapt to many kinds of sheets and paper having respective attributes (described later in detail).  
         [0089]     As shown in  FIG. 7 , a follower roller driving device  50  for controlling the operation of bringing the follower rollers  152   a ,  152   b , and  152   c  into contact with or separating those from the sub roller  151  and the operation of bringing the follower roller  154  into contact with or separating it from the sheet feeding roller  153  may be provided. This makes it possible to lower the power consumption of the ink jet printer  100  and to thereby reduce its size.  
         [0090]     As shown in  FIG. 8 , the follower roller driving device  50  is equipped with pivoting members  51  and  52 , a cam shaft  53 , and gear units  54  and  55 . The follower roller  152   c  is rotatably attached to one end of the pivoting member  51  and the other end of the pivoting member  51  is to contact the cam shaft  53 . And the pivoting member  51  is configured to pivot about a central shaft  51   a . The follower roller  154  is rotatably attached to one end of the pivoting member  52  and the other end of the pivoting member  52  is to contact the cam shaft  53 . And the pivoting member  52  is configured to pivot about a central shaft  52   a.    
         [0091]     The cam shaft  53  is separately provided with a cam  53   a  (see  FIG. 9 ) that acts on the pivoting member  51  and a cam  53   b  (see  FIG. 11 ) that acts on the pivoting member  52 . An intermittent gear  53   c  to mesh with the gear unit  54  and an intermittent gear  53   d  to mesh with the gear unit  55  are fit in the cam shaft  53  at one end. The gear unit  54  is provided with a planetary gear  54   a  for intermittently transmitting drive force of a motor (not shown) to the intermittent gear  53   c  of the cam shaft  53 . The gear unit  55  is provided with a lever  55   b  that is rotatable and can be operated manually and that is formed with a gear  55   a  to mesh with the intermittent gear  53   d  of the cam shaft  53 . How the above-configured follower roller driving device  50  operates will be described below with reference to the drawings.  
         [0092]      FIGS. 9 and 10  show a case that only the follower roller  152   c  is caused to operate.  FIG. 9  shows a state that the follower roller  152   c  is in contact with the sub roller  151  and the follower roller  154  is in contact with the sheet feeding roller  153 . In this state, the planetary gear  54   a  is separated from the intermittent gear  53   c  and the cam  53   a  is separated from the other end of the pivoting member  51 . The lever  55   b  is located at a contact position, and the cam  53   b  is separated from the other end of the pivoting member  52  (not shown in  FIG. 9 ).  
         [0093]      FIG. 10  shows a state that the planetary gear  54   a  has been driven by the motor (not shown) and is thereby meshed with the intermittent gear  53   c . As a result, the cam  53   a  pushes the other end of the pivoting member  51  and hence the follower roller  152   c  which is pivotally supported by the pivoting member  51  at the one end is separated from the sub roller  151 .  
         [0094]     When a sheet or paper is supplied, to reliably deliver it from the sub roller  151  to the sheet feeding roller  153 , it is necessary that as shown in  FIG. 9  the follower roller  152   c  be in contact with the sub roller  151  and the follower roller  154  be in contact with the sheet feeding roller  153 . On the other hand, when recording is performed on a sheet or paper, it is necessary that as shown in  FIG. 10  the follower roller  152   c  be separated from the sub roller  151  and the follower roller  154  be in contact with the sheet feeding roller  153 , because contact of the follower roller  152   c  to the sub roller  151  would adversely affect the sheet feed accuracy.  
         [0095]      FIGS. 11 and 12  show a case that the follower rollers  152   c  and  154  are caused to operate simultaneously.  FIG. 11  shows a state that the follower roller  152   c  is in contact with the sub roller  151  and the follower roller  154  is in contact with the sheet feeding roller  153 . In this state, the planetary gear  54   a  is separated from the intermittent gear  53   c  and the cam  53   a  is separated from the other end of the pivoting member  51  (not shown in  FIG. 11 ). The lever  55   b  is located at the contact position, and the cam  53   b  is separated from the other end of the pivoting member  52 .  
         [0096]      FIG. 12  shows a state that the lever  55   b  is moved manually from the contact position to a release position, whereby the gear  55   a  is meshed with the intermittent gear  53   d  and rotates the latter. As a result, the cam  53   a  (not shown in  FIG. 12 ) pushes the other end of the pivoting member  51  and hence the follower roller  152   c  which is pivotally supported by the pivoting member  51  at the one end is separated from the sub roller  151 . Further, since the cam  53   b  pushes the other end of the pivoting member  52  and hence the follower roller  152   c  which is rotatably supported by the pivoting member  52  at the one end is separated from the sheet feeding roller  153 .  
         [0097]     When a sheet or paper is supplied, to reliably deliver it from the sub roller  151  to the sheet feeding roller  153 , it is necessary that as shown in  FIG. 11  the follower roller  152   c  be in contact with the sub roller  151  and the follower roller  154  be in contact with the sheet feeding roller  153 . On the other hand, when a sheet is fed manually, it is necessary that as shown in  FIG. 12  the follower rollers  152   c  and  154  be separated from the sub roller  151  and the sheet feeding roller  153 , respectively, because the sheet would interfere with the follower rollers  152   c  and  154  if the follower rollers  152   c  and  154  were in contact with the sub roller  151  and the sheet feeding roller  153 , respectively.  
         [0098]     As shown in  FIGS. 13-15 , the main guide shaft  61  is disposed behind the carriage  161  so as to extend in the primary scanning direction and the auxiliary guide shaft  62  is disposed in front of the carriage  161  so as to extend approximately parallel with the main guide shaft  61 . The main guide shaft  61  and the auxiliary guide shaft  62  assume circular rod shapes, and both ends of each of the main guide shaft  61  and the auxiliary guide shaft  62  are supported by and fixed to side frames (not shown).  
         [0099]     The main guide shaft  61  is provided with main guide plates  63  that assume long rectangle shapes and extend from one end to the other end of the main guide shaft  61 , and the auxiliary guide shaft  62  is provided with auxiliary guide plates  64  that assume long rectangle shapes and extend from one end to the other end of the auxiliary guide shaft  62 . More specifically, two main guide plates  63  are arranged side by side in the circumferential direction so as to cover an approximately half, carriage- 161 -side circumferential face of the main guide shaft  61 , and two auxiliary guide plates  64  are arranged side by side in the circumferential direction so as to cover an approximately half, carriage- 161 -side circumferential face of the auxiliary guide shaft  62 . That is, the two main guide plates  63  and the two auxiliary guide plates  64  are arranged so as to cover top portions and bottom portions of the approximately half, confronting circumferential faces of the main guide shaft  61  and the auxiliary guide shaft  62 .  
         [0100]     Both longer-side end portions of each main guide plate  63  and those of each auxiliary guide plate  64  are slightly bent toward the main guide shaft  61  or the auxiliary guide shaft  62  so as to form a generally C-shaped cross section. With this sectional shape, when the main guide plates  63  and the auxiliary guide plates  64  are attached to the circumferential faces of the main guide shaft  61  and the auxiliary guide shaft  62 , both longer-side end portions of each main guide plate  63  and those of each auxiliary guide plate  64  contact the circumferential face of the main guide  61  or the auxiliary guide  62  and central portions of the main guide plates  63  and the auxiliary guide plates  64  are slightly separated from the circumferential faces of the main guide shaft  61  and the auxiliary guide shaft  62  to provide play between them. Both ends of each main guide plate  63  and those of each auxiliary guide plate  64  are also supported by the above-mentioned side frames, and providing play in these support portions enables sheet metal alignment.  
         [0101]     The carriage  161  is provided with slide members  70  having the same structure on the back side at the two end positions in the primary scanning direction, as well as with slide members  80  having the same structure on the front side at the two end positions in the primary scanning direction. In each slide member  70 , two radial bearings  71  are attached to a fixed seat  72  that is screwed to the carriage  161  and are arranged and oriented so as to form approximately a right angle in the vertical plane containing those. That is, the two radial bearings  71  are supported by the fixed seat  72  so as to be brought into contact with the two respective main guide plates  63  attached to the main guide shaft  61  and to be able to slide in the longitudinal direction of the main guide plates  63 .  
         [0102]     In each slide member  80 , two radial bearings  81  are attached to a movable seat  82  that is movably attached to the carriage  161  and are arranged and oriented so as to form approximately a right angle in the vertical plane containing those. That is, the two radial bearings  81  are pivotally supported by the movable seat  72  so as to be brought into contact with the two respective auxiliary guide plates  64  attached to the auxiliary guide shaft  62  and to be able to slide in the longitudinal direction of the auxiliary guide plates  64 . One end portion of each of shafts  83  is fixed to the fixed seat  72  and the other end portion penetrates through the movable seat  82  with a spring  84  interposed in between. The movable seats  82  are thus movable along the respective shafts  83 . Play that occurs when each movable seat  82  is moved can be eliminated by adjusting the length of the support portion of the shaft  83  that is close to the movable seat  82 .  
         [0103]     With the above-configured carriage  161 , the slide members  70  and  80  do not directly contact the main guide shaft  61  and the auxiliary guide shaft  62 , respectively, which prevents wear of the main guide shaft  61  and the auxiliary guide shaft  62 . Therefore, the reciprocation of the carriage  161  in the primary scanning direction can be kept highly accurate. Wear of the main guide plates  63  and the auxiliary guide plates  64  can also be reduced by making those of a material that is less prone to wear such as stainless steel, which also contributes to keeping the reciprocation of the carriage  161  in the primary scanning direction highly accurate.  
         [0104]     Since the radial bearings  81  of the slide members  80  press on the auxiliary guide plates  64  attached to the auxiliary guide shaft  62  because of the restorative forces of the springs  84 , the reaction forces cause the radial bearings  71  of the slide members  70  to press on the main guide plates  63 , whereby the main guide plates  63  are bent by an amount corresponding the play and are pressed against the main guide shaft  61 . Therefore, the carriage  161  always slides along the main guide shaft  61  and its reciprocation in the main direction is kept highly accurate. The use of the radial bearings  71  and  81  instead of conventional thrust bearings contributes to cost reduction.  
         [0105]     Since as described above both ends of the main guide shaft  61  are supported by and fixed to the side frames, the main guide shaft  61  may be bent by the loads from the springs  84  that act on the main guide shaft  61  in its radial direction. In view of this, a support member  65  for sustaining the above loads is disposed behind the center of the main guide shaft  61 . However, the main guide shaft  61  is made rotatable about an eccentric rotation axis so that the gap between the nozzle formation face of the recording head  162  mounted on the carriage  161  and the recording face of a sheet or paper being transported on the guide face  163   a  of the platen  163  is always kept constant even if the sheet or paper thickness is varied. Therefore, if a simple support member were disposed behind the center of the main guide shaft  61 , a gap might occur between the support member and the main guide shaft  61  depending on the rotation position of the main guide shaft  61 . To prevent occurrence of such a gap, the support member  65  has the following structure.  
         [0106]     As shown in  FIG. 16 , the support member  65  is provided with a press member  65   a  and an adjustment member  65   b . The press member  65   a  is screwed to a frame  107  that is disposed behind the main guide shaft  61 . The adjustment member  65   b  is partially buried in the rear side of the main guide shaft  61  at the center. The press member  65   a  and the adjustment member  65   b  contact each other and thereby sustain the loads from the springs  84  that act on the main guide shaft  61  in its radial direction.  
         [0107]     Whereas the contact face of the press member  65   a  is flat, the contact face of the adjustment member  65   b  has a curved face whose distance from the eccentric rotation axis R of the main guide shaft  61  is always kept constant, that is, does not vary depending on the rotation position. With this measure, no gap is formed between the support member  65  and the main guide shaft  61  even if the above-mentioned gap adjustment is performed by rotating the main guide shaft  61  about the eccentric rotation axis. Therefore, the support member  65  can always sustain the loads (indicated by an arrow in  FIG. 17 ) from the springs  84  that act on the main guide shaft  61  in its radial direction. The main guide shaft  61  is prevented from being bent by the loads and hence the recording accuracy can be kept high.  
         [0108]     As shown in  FIG. 18  to  FIGS. 21A and 21B , the platen gap adjustment mechanism  170  is equipped with eccentric bushings  171   a ,  171   b ,  172   a , and  172   b  that support the main guide shaft  61  and the auxiliary guide shaft  62  in an eccentric manner, a belt  173  for synchronously rotating the eccentric bushings  171   a  and  172   a  that are located on one side, and tension pulleys  174  that act on the belt  173  from both sides to give tension to it. The platen gap adjustment mechanism  170  is also equipped with a motor  175 , a gear unit  176  for coupling the motor  175  to the eccentric bushings  171   a  and  172   a , and first fixing members  177  and a second fixing member  178  that fix the main guide shaft  61  and the auxiliary guide shaft  62 .  
         [0109]     As shown in  FIG. 18  to  FIGS. 21A and 21B , the two ends of the main guide shaft  61  and the two ends of the auxiliary guide shaft  62  are fixed to the eccentric bushings  171   a ,  171   b ,  172   a , and  172   b , respectively, and the eccentric bushings  171   a ,  171   b ,  172   a , and  172   b  are attached rotatably to the two side frames (not shown). This enables eccentric rotation of the main guide shaft  61  and the auxiliary guide shaft  62 . As shown in  FIGS. 18-20 , the belt  173  is stretched between the eccentric bushings  171   a  and  172   a , which prevents backlash that would otherwise occur in the case where gears are used. The tension pulleys  174  are screwed to the side frame (not shown), which prevents a phase deviation between the main guide shaft  61  and the auxiliary guide shaft  62  when they rotate.  
         [0110]     As shown in  FIGS. 18-20 , the gear unit  176  is provided with a bushing gear  176   a  that is fitted with one end of the eccentric bushing  171   a , a first intermediate gear  176   b  that is in mesh with the motor  175 , a planetary gear  176   c  that is in mesh with the first intermediate gear  176   b , a second intermediate gear  176   d  that meshes with the planetary gear  176   c  intermittently, a third intermediate gear  176   e  that is in mesh with the second intermediate gear  176   d , and a fourth intermediate gear  176   f  that is in mesh with the third intermediate gear  176   e . The planetary gear  176   c  has a function of switching between the gap adjustment driving and the switching driving for the switching shafts  14  and  22  plus the release driving for the follower rollers  152   a ,  152   b , and  152   c  in accordance with the normal/reverse rotation of the motor  175 .  
         [0111]     As shown in  FIG. 18  to  FIGS. 21A and 21B , the first fixing members  177  are fixed to the respective eccentric bushings  171   a ,  171   b ,  172   a , and  172   b . The first fixing members  177  are screwed to the two side frames (not shown) after the horizontality of the plane defined by the first guide shaft  61  and the second guide shaft  62  is adjusted. As shown in  FIGS. 18 and 19 B and  FIGS. 21A and 21B , the second fixing member  178  is attached to the eccentric bushing  171   b  that is located on the other side. The second fixing member  178  is screwed to a flange  171   ba  that is integral with the eccentric bushing  171   b  after a gap adjustment is performed by eccentric rotation of the main guide shaft  61  and the second guide shaft  62 .  
         [0112]     During a gap adjustment, the carriage  161  is moved in the vertical direction, which may cause deviation of the main guide plates  63  and the auxiliary guide plates  64  that are provided between the main guide shaft  61  and the second guide shaft  62 . However, since the main guide plates  63  and the auxiliary guide plates  64  are attached to the side frames with some play, simplified sheet metal alignment can be performed. Complete sheet metal alignment can then be performed by leveling the main guide plates  63  and the auxiliary guide plates  64  by reciprocating the carriage  161  in the primary scanning direction.  
         [0113]     With the above-configured platen gap adjustment mechanism  170 , the carriage  161  can be moved in the vertical direction by automatically rotating the main guide shaft  61  and the auxiliary guide shaft  62  in phase in an eccentric manner. Therefore, a highly accurate gap adjustment can be performed so that the gap between the nozzle formation face of the recording head  162  mounted on the carriage  161  and the recording face of a sheet or paper being transported on the guide face  163   a  of the platen  163  is always kept constant even if the sheet or paper thickness is varied.  
         [0114]     During a gap adjustment, a recognition sensor of the carriage  161  is moved in the vertical direction in synchronism with a vertical movement of the carriage  161 . A linear encoder scale that is part of a position sensor for the carriage  161  needs to be kept out of contact with a linear encoder that is attached to the carriage  161 . Therefore, a mechanism is provided that makes it possible to adjust the position of the linear encoder scale by using levers that are attached to the two respective sides of the linear encoder scale.  
         [0115]      FIGS. 22 and 23  show a detailed structure of the follower roller unit  156 .  FIG. 23  is different from  FIG. 22  in that a lever  40  is removed. The two ends of the switching shaft  14  are pivotally supported by respective frames  15  so as to be movable in elliptical holes  15   a  that are formed in the respective frames  15 . Plural sets of a spur roller  11 , a smooth roller  12 , and a release portion  13  (see  FIG. 5 ) where neither the spur roller  11  nor the smooth roller  12  is provided are arranged in the axial direction at prescribed intervals. In each set, the spur roller  11 , the smooth roller  12 , and the release portion  13  are disposed around the switching shaft  14  at prescribed intervals in the circumferential direction.  
         [0116]     The switching shaft  14  of the follower roller unit  156  and the switching shaft  22  of the support rib unit  164  are rotated in link with each other by a gear unit  30 . The gear unit  30  is equipped with a roller gear  31  that is fitted with one end of the switching shaft  14 , a rib gear  32  that is fitted with one end of the switching shaft  22 , a first intermediate gear  33  and a second intermediate gear  34  that are in mesh with each other and with the roller gear  31  and the rib gear  32 , respectively, and a planetary gear  35  that meshes with the second intermediate gear  34  intermittently. The planetary gear  35  has a function of switching between the switching driving for the switching shafts  14  and  22  and the release driving for the follower rollers  152   a ,  162   b , and  152   c  in accordance with the normal/reverse rotation of the motor (not shown).  
         [0117]     The gear unit  30  is also equipped with an arm  37  that supports the respective shafts of the first intermediate gear  33  and the second intermediate gear  34  and is connected to the frame  15  via a spring  36 , a positioning cam  38  (see  FIG. 23 ) that is fitted with the one end of the switching shaft  14 , a positioning lever  40  that is connected to the arm  37  via a spring  39  and is locked with the cam  38 , and a limit switch  41  that is turned on or off in accordance with the position of the arm  37 . As shown in  FIGS. 24A-24C , a phase detection cam  42  that is fitted with the other end of the switching shaft  14  and a limit switch  43  that is turned on or off in accordance with the rotation position of the phase detection cam  42  are also provided.  
         [0118]     The spring  36  urges the arm  37  downward, whereby the switching shaft  14  is ordinarily placed at the bottom stationary positions in the holes  15   a . The circumferential face of the positioning cam  38  is formed with three positioning cuts  38   a  that correspond to switching positions for the switching shaft  14 , that is, switching positions for the spur rollers  11 , the smooth rollers  12 , and the release portions  13 . The positioning lever  40  is provided with, at one end, a projection  40   a  that is to engage with the positioning cuts  38   a  of the positioning cam  38 . The positioning lever  40  is slidably attached to the side face of the arm  37  so that the projection  49   a  can slide along the circumferential face of the positioning cam  38 .  
         [0119]     The spring  39  urges the positioning lever  40  in the sliding direction, whereby the projection  40   a  of the positioning lever  40  is always pressed against the circumferential face of the positioning cam  38 . The circumferential face of the phase detection cam  42  is formed with three phase detection cuts  42   a  that correspond to switching positions for the switching shaft  14 , that is, switching positions for the spur rollers  11 , the smooth rollers  12 , and the release portions  13 .  
         [0120]     With the above gear unit  30 , the drive force of the motor  175  is transmitted to the rib gear  32  via the planetary gear  35  and the second intermediate gear  34  as well as to the roller gear  31  via the planetary gear  35 , the second intermediate gear  34 , and the first intermediate gear  33 . Therefore, the switching shafts  22  and  14  are rotated in link with each other, whereby the switching between the protrusion and retraction of the support ribs  21  and the switching between the spur rollers  11 , the smooth rollers  12 , and the release portions  13  can be performed simultaneously. Alternatively, instead of the gear unit, the switching shaft  14  of the follower roller unit  156  and the switching shaft  22  of the support rib unit  164  can be rotated in link with each other by using a pulley/belt mechanism.  
         [0121]     When switching is performed between the spur rollers  11 , the smooth rollers  12 , and the release portions  13 , the positioning cam  38  and the phase detection cam  42  rotate together with the switching shaft  14 , the projection  40   a  of the positioning lever  40  is disengaged from one positioning cut  38   a  of the positioning cam  38  and slides along its circumferential face, and the lever of the limit switch  43  is disengaged from one phase detection cut  42   a  of the phase detection cam  42  and slides along its circumferential face. The fact that the switching operation is being performed can be detected reliably on the basis of a signal from the limit switch  43 . If an abnormality that the switching shaft  14  goes up from the bottom stationary positions in the holes  15   a  occurs due to a certain external cause, the arm  37  is separated from the limit switch  41 . Therefore, the occurrence of the abnormality can be detected reliably on the basis of a signal from the limit switch  41 .  
         [0122]     The switching between the spur rollers  11 , the smooth rollers  12 , and the release portions  13  is completed when the projection  40   a  of the positioning lever  40  is brought into engagement with another positioning cut  38   a  of the positioning cam  38  and the lever of the limit switch  43  is brought into engagement with another phase detection cut  42   a  of the phase detection cam  42 . Since as described above the projection  40   a  of the positioning lever  40  is engaged with the positioning cuts  38   a  of the positioning cam  38 , the spur rollers  11 , the smooth rollers  12 , and the release portions  13  can be set reliably to the prescribed phases. Further, the completion of the above switching operation can be detected reliably on the basis of a signal from the limit switch  43 .  
         [0123]      FIG. 25A  shows a state that the follower roller unit  156  is switched to the release portions  13  and the spur rollers  11  and the smooth rollers  12  are separated from the sheet ejection roller  155  and that in the support rib unit  164  the support ribs  21  are retracted from the guide face  163   a  of the platen  163 .  FIG. 25B  shows a state that the follower roller unit  156  is switched to the spur rollers  11  or the smooth rollers  12  and the spur rollers  11  or the smooth rollers  12  are in contact with the sheet ejection roller  155  and that in the support rib unit  164  the support ribs  21  are retracted from the guide face  163   a  of the platen  163 .  
         [0124]      FIG. 25C  shows a state that the follower roller unit  156  is switched to the spur rollers  11  or the smooth rollers  12  and the spur rollers  11  or the smooth rollers  12  are in contact with the sheet ejection roller  155  and that in the support rib unit  164  the support ribs  21  are protruded from the guide face  163   a  of the platen  163 . This kind of switching makes it possible to realize a sheet ejection form that is most suitable for the attribute of a sheet or paper.  
         [0125]      FIG. 26  is a table showing switching states of the follower roller unit  156  and the support rib unit  164  that correspond to respective attributes of sheets and paper. As shown in the row of condition  1 , where the sheet or paper type is a cut sheet and the sheet or paper state is “normal,” an optimum sheet ejection form can be realized by making switching to the spur rollers  11  and switching the support ribs  21  to a protruded state. This is because normal cut sheets are less prone to jag traces but tend to rise.  
         [0126]     As shown in the row of condition  2 , where the sheet or paper type is a cut sheet and the sheet or paper state is “delicate,” an optimum sheet ejection form can be realized by making switching to the smooth rollers  12  and switching the support ribs  21  to a protruded state. This is because smooth rollers having smooth circumferential faces are less prone to scratch easy-to-scratch cut sheets.  
         [0127]     As shown in the row of condition  3 , where the sheet or paper type is a roll of paper and the sheet or paper state is “normal,” an optimum sheet ejection form can be realized by making switching to the release portions  13  and switching the support ribs  21  to a retracted state. This is because normal rolled paper needs to be cut with a cutter and hence interference might occur if the spur rollers  11  or the smooth rollers  12  existed on the path, and normal rolled paper is curled and hence might rub against the support ribs  21  if they existed in the path.  
         [0128]     As shown in the row of condition  4 , where the sheet or paper type is a roll of paper and the sheet or paper state is “thin,” an optimum sheet ejection form can be realized by making switching from the release portions  13  to the spur rollers  11  only during paper ejection and always keeping the support ribs  21  in a retracted state. This is because static electricity tends to occur in thin rolled paper and hence it may stick to the platen  163  or the like to become hard to eject, and thin rolled paper is curled and hence might rub against the support ribs  21  if they existed in the path.  
         [0129]     As shown in the row of condition  5 , where the sheet or paper type is a roll of paper and the sheet or paper state is “hygroscopic,” an optimum sheet ejection form can be realized by keeping, from recording to paper ejection, a state that switching is made to the spur rollers  11  from the release portions  13  and switching the support ribs  21  to a retracted state. This is because highly hygroscopic roller paper tends to rise because of what is called cockling, and highly hygroscopic roller paper is curled and hence might rub against the support ribs  21  if they existed in the path.  
         [0130]     As shown in the row of condition  6 , where the sheet or paper type is a roll of paper and rolled paper is to be “cut shortly,” an optimum sheet ejection form can be realized by making switching from the release portions  13  to the spur rollers  11  only during paper ejection and always keeping the support ribs  21  in a retracted state. This is because a short-cut part of rolled paper may play on the platen  163  and become hard to eject, and a short-cut part of rolled paper is curled and hence might rub against the support ribs  21  if they existed in the path.  
         [0131]     As shown in the row of condition  7 , where the sheet or paper type is a manual feed sheet and the sheet or paper state is “thick,” an optimum sheet ejection form can be realized by making switching to the release portions  13  and switching the support ribs  21  to a retracted state. This is because thick manual feed sheets might interfere with the spur rollers  11 , the smooth rollers  12 , or the support ribs  21  if they existed in the path. The switching of the follower roller unit  156  and the support rib unit  164  can be performed automatically by storing the above kind of data in a control section of the ink jet printer  100  in the form of a table.  
         [0132]     In the above-described embodiment, the switching shaft  14  of the follower roller unit  156  and the switching shaft  22  of the support rib unit  164  are rotated in link with each other by means of the gear unit  30 . However, the invention is not limited to such a case. Separate gear units or the like may be provided so that the switching shaft  14  of the follower roller unit  156  and the switching shaft  22  of the support rib unit  164  are rotated independently of each other. Further, adaptation to many kinds of sheets and paper having respective attributes is possible even if only the follower roller unit  156  is provided, that is, the support rib unit  164  is not provided.  
         [0133]     As shown in  FIGS. 27 and 28 , the follower roller driving device  50  is equipped with the intermittent gear  53   c  and the planetary gear  54   a  for operating the follower roller  152   c  and an intermittent gear  53 C and a planetary gear  54 A for operating the follower rollers  152   a  and  152   b . The platen gap adjustment mechanism  170  is equipped with the belt  173 , the tension pulleys  174 , and the gear unit  176 . The follower roller unit  156  and the support rib unit  164  are coupled to the gear unit  30 . The follower roller driving device  50 , the platen gap adjustment mechanism  170 , the follower roller unit  156 , and the support rib unit  164  are driven and switched by the single motor  175 .  
         [0134]     More specifically, as shown in  FIG. 28 , if the motor  175  is rotated counterclockwise, the planetary gear  176   c  is moved to such a position as to be able to drive the follower roller driving device  50 , the follower roller unit  156 , and the support rib unit  164 . In this state, if the motor  175  rotated clockwise, the planetary gear  35  is moved to such a position as to be able to drive the follower roller unit  156  and the support rib unit  164 . If the motor  175  is rotated counterclockwise, the driving by the planetary gear  35  is suspended. On the other hand, when the motor  175  is rotated clockwise, the planetary gear  54 A is moved to such a position as to separate the follower rollers  152   a  and  152   b  from the sub roller  151  and the planetary gear  54   a  is moved to such a position as to separate the follower roller  152   c  from the sub roller  151 . When the motor  175  is rotated counterclockwise, the planetary gear  54 A is moved to such a position as to bring the follower rollers  152   a  and  152   b  into contact with the sub roller  151  and the planetary gear  54   a  is moved to such a position as to bring the follower roller  152   c  into contact with the sub roller  151 .  
         [0135]     On the other hand, if first the motor  175  is rotated clockwise, the planetary gear  176   c  is moved to such a position as to be able to drive the platen gap adjustment mechanism  170 . In this state, if the motor  175  is rotated clockwise, the platen gap (i.e., the distance between the head face and the platen  163 ) is increased. If the motor  175  is rotated counterclockwise, the platen gap is decreased.  
         [0136]     As shown in  FIG. 30A , if first a motor  93  is rotated counterclockwise, a planetary gear  91  is moved to such a position as to be able to drive an automatic sheet supply mechanism including the hopper  141  and the sheet supply roller  142 . In this state, if the motor  93  is rotated counterclockwise, the automatic sheet supply mechanism operates in the normal rotation direction. If motor  93  is rotated clockwise, the automatic sheet supply mechanism operates in the reverse rotation direction. On the other hand, if first the motor  93  is rotated clockwise, the planetary gear  91  is moved to such a position as to be able to drive a cleaning mechanism  90 . In this state, if the motor  93  is rotated counterclockwise, a wiper is driven. If motor  93  is rotated clockwise, a pump  95  is driven.  FIG. 30B  is a perspective of the mechanisms shown in  FIG. 28 .  
         [0137]     The switching between the drive subject switching operation and the drive force transmitting operation that relate to the motors  175  and  93  is made by the carriage  161  being operated by a lever  92  shown in  FIG. 29 . For the drive subject switching operation, the lever  92  is moved to an unlock position (indicated by arrow UL). For the drive force transmitting operation, the lever  92  is moved to a lock position (indicated by arrow L).  
         [0138]     As shown in  FIG. 31 , the sensor  157   b  is attached to the pivoting member  52  that supports the follower roller  154  that is associated with the sheet feeding roller  155 . A hole  163   c  is formed in the platen  163  at a position right under the sensor  157   b . A vertical wall  163   d , a wall  163   e  that forms an angle of about 135° with the wall  163   d , and a wall  163   f  that forms an angle of about 90° with the wall  163   d  are formed inside the hole  163   c.    
         [0139]     The sensor  157   b , which is generally a photoreflector, may operate erroneously due to incidence of external light (sunlight) or reflection of light generated by itself. However, light generated by the sensor  157   b  itself does not return to the sensor  157   b  because it passes through the hole  163   c , is reflected by the face of the wall  163   e  to change the path by about 90°, and is again reflected by the face of the wall  163   f  to change the path by about 90° (indicated by a broken line in  FIG. 31 ): an erroneous operation can thus be prevented. External light (sunlight) does not shine on the sensor  157   b  because it is interrupted by the back face of the wall  163   e : an erroneous operation can thus be prevented.  
         [0140]     An operation that is performed when the ink jet printer  100  having the above configuration performs recording on a normal cut sheet will be described with reference to  FIGS. 32A and 32B  and  FIGS. 33A and 33B . First, the control section automatically switches the follower roller unit  156  and the support rib unit  164  for normal cut sheets. More specifically, switching is made to the spur rollers  11  in the follower roller unit  156  and the support ribs  21  of the support rib unit  164  are retracted. The cut sheets P that are stacked and accommodated in the sheet supply tray  210  of the tray unit  200  that is inserted in the sheet supplying/ejecting section  140  are pressed against the sheet supply roller  142  because the hopper  141  is elevated by the restorative force of the compression spring  144  in synchronism with the rotation of the sheet supply roller  142  (the synchronization is achieved mechanically). Only the uppermost cut sheet P is separated by the separation member  143  and supplied to the transporting section  150 .  
         [0141]     When the thus-supplied cut sheet P reaches a contact point  151   a  of the sub roller  151  and an associated follower roller  152   a  (see  FIG. 32A ), skew taking of the cut sheet P is performed. The method of skew taking depends on the thickness of a sheet or paper. In the case of a cut sheet that is as thin as or thinner than an ordinary sheet, first, only a quite small tip portion of the cut sheet P is inserted between the sub roller  151  and an associated follower roller  152   a . The rollers  151  and  152   a  are thereafter rotated in the reverse direction to bend the cut sheet P and thereby align the tip of the cut sheet P. Then, the cut sheet P is taken.  
         [0142]     On the other hand, in the case of a thick cut sheet that is thicker than an ordinary sheet, the tip of the cut sheet P is knocked against the contact point  151   a  of the sub roller  151  and an associated follower roller  152   a  and the sheet supply roller  142  is caused to slip, whereby the tip of the cut sheet P is aligned. Then, the cut sheet P is taken. The insertion length or the knock-in length is detected by the sensor  157   a  and the skew taking is controlled on the basis of the detected length.  
         [0143]     The reason why the skew taking method depends on the sheet or paper thickness is that a thin cut sheet is brittle and hence the sheet supply roller  142  may send out the cut sheet without slipping on it, and that a thick cut sheet is a lamination of thin cut sheets and hence a thin cut sheet may peel off when the rollers  151  and  152   a  are rotated in the reverse direction.  
         [0144]     After completion of the skew taking, the cut sheet P is reversed (i.e., the traveling direction is changed to the direction opposite to the sheet supply direction) as it travels along the U-shaped path while being held between the sub roller  151  which is driven by a sheet fed motor (not shown) and an associated follower rollers  152   a ,  152   b , and  152   c . When the tip of the cut sheet P reaches a detection position DP of the sensor  157   b  (see  FIG. 32B ), paper leading end positioning (i.e., determination of a recording start position) of the cut sheet P is performed.  
         [0145]     More specifically, the transport length is detected by the sensor  157   b  until the leading end of the cut sheet P reaches the recording start position HP (see  FIG. 33A ) after passing the detection position DP and passing between the sheet feeding roller  153  and an associated follower roller  154 . The leading end positioning is controlled on the basis of the detected transport length. Conventionally, the leading end positioning is performed by using the sensor  157   a  that is located upstream of the sub roller  151 . In contrast, in this embodiment, since the leading end positioning is performed by using the sensor  157   b  that is located downstream of the sub roller  151 , a transport length to be detected is short and, in particular, the accuracy of the leading end positioning can be increased by eliminating a paper leading end positioning error due to a difference in sheet or paper thickness.  
         [0146]     The cut sheet P that has been subjected to the leading end positioning is transported to the recording section  160  while being held between the sheet feeding roller  153  which is driven by the sheet feed motor (not shown) and an associated follower roller  154 . The continuation of the holding of the cut sheet P between the sub roller  151  and an associated follower rollers  152   a ,  152   b , and  152   c  is a factor of lowering the transport accuracy, and hence the follower rollers  152   a ,  152   b , and  152   c  are released from the sub roller  151  (see  FIG. 33B ).  
         [0147]     The cut sheet P thus transported is absorbed on the platen  163  by a suction pump (not shown) and is thereby rendered flat, and recording is performed by the recording head  162  mounted on the carriage  161  which is reciprocated for scanning by the carriage motor  166  and the timing belt  165  (not shown). The control section of the ink jet printer  100  performs a high-precision ink dot control, halftone processing, etc. by supplying inks of, for example, a total of seven colors of yellow, light yellow, magenta, light magenta, cyan, light cyan, and black from ink cartridges of the respective colors to the recording head  162  and controlling the discharge timing of the inks of the respective colors and the driving of the carriage  161  and the sheet feeding roller  153 . The recorded cut sheet P is ejected onto the sheet supplying/ejecting section  140  by transporting it while holding it between the spur rollers  11  and the sheet ejection roller  155  which is driven by the sheet feed motor (not shown). The cut sheet P is placed (stacked) on the sheet ejection tray  230  of the tray unit  200 .  
         [0148]     As described above, in the ink jet printer  100  according to this embodiment, the spur rollers  11  and the smooth rollers  12  can be brought into contact with or separated from the recording face of a sheet or paper in accordance with the attribute of the sheet or paper. Therefore, particularly in ejecting a sheet or paper whose recording face is prone to be scratched, the recording face can be prevented from being scratched by separating the spur rollers  11  and the smooth rollers  12 , that is, making switching to the release portions  13 , whereby the recording accuracy can be kept high. Since the switching shaft  14  is rotated in accordance with the attribute of a sheet or paper, setting can be made to automatic switching by the control section of the ink jet printer  100 , which makes it possible to reliably prevent recording unevenness, staining of a sheet or paper, and scratching of the recording face due to a switching error of a user.  
         [0149]     The support ribs  21  can be protruded or retracted from the guide face  163   a  in accordance with the attribute of a sheet or paper. Therefore, particularly when the tail of a sheet is released from the sheet feeding roller  153  and the follower roller  154 , the sheet can be prevented from rising by supporting its tail portion by protruding the support ribs  21 , whereby highly accurate recording can be performed and staining of the sheet can be prevented. Further, since the gear unit  30  for rotating the switching shafts  14  and  22  in link with each other in accordance with the attribute of a sheet or paper, setting can be made to automatic switching by the control section of the ink jet printer  100 , which makes it possible to reliably prevent recording unevenness, staining of a sheet or paper, and scratching of the recording face due to a switching error of a user.  
         [0150]     The invention can broadly be applied to recording apparatus having a carriage such as a facsimile machine and a copier. The application field of the invention is not limited to recording apparatus. That is, the invention can be applied to liquid ejection apparatus in which liquid droplets suitable for an intended use instead of ink droplets are ejected from a liquid ejection head toward a target medium to have those liquid droplets stuck to the target medium, such as apparatus having a colorant ejection head to be used for manufacture of color filters of a liquid crystal display device or the like, an electrode material (conductive paste) ejection head to be used for formation of electrodes of an organic EL display, a field-emission display (FED), or the like, a bioorganic material ejection head to be used for manufacture of a biochip, a sample ejection head as precision pipettes, or a like liquid ejection head.