Patent Abstract:
A feeding tray supports a plurality of media the media thereon. A hopper is provided on the feeding tray so as to be movable in a first direction for pushing the media toward a feeding roller so that a top one of the media comes in contact with the feeding roller, and in a second direction opposite to the first direction. A separator separates a first group including at least one of the media which is situated under the top one of the media from the top one, so that only the top one is fed to the downstream section by rotation of the feeding roller. A returning lever is pivotable interlockingly with the feeding roller and adapted to return a second group including at least one of the media in the first group, which has been proceeded from a prescribed position to the downstream section together with the top one of the media, to the feeding tray. A holder supports a third group including at least one of the media in the first group which is situated under the second group. The holder is slidable in the second direction interlockingly with the movement of the hopper in the second direction to move the third group toward the feeding tray to secure a space to which the second group is returned by the returning lever.

Full Description:
BACKGROUND OF THE INVENTION 
     In a recording apparatus (liquid ejecting apparatus) provided with an automatic feeder, a plurality of recording media (target media) are stacked on a media feeding tray and a top one of the recording media is picked up by a hopper and a separator and fed to the inside of the recording apparatus. The present invention relates to a returner for returning at least one recording medium accompanied with the top one to the medium feeding tray. 
     The term “liquid ejecting apparatus” as used herein includes not only recording apparatus such as a printer, a copier, and a facsimile machine that use an ink jet recording head and perform recording on a recording material by ejecting ink from the recording head but also an apparatus that ejects liquid suitable for a purpose instead of ink from a liquid ejecting head toward a target material and thereby cause the liquid to land on the target material. 
     Examples of the liquid ejecting head other than the recording head are a colorant ejecting head used for manufacture of color filters of a liquid crystal display or the like, an electrode material (conductive paste) ejecting head used for formation of electrodes of an organic EL display, a field emission display (FED), or the like, a bioorganic material ejecting head used for manufacture of a biochip, and a sample ejecting head as precision pipettes. 
     An ink jet printer as an example of the ink jet recording apparatus or the liquid ejecting apparatus will be hereinafter described. 
     In the ink jet printer, in the event of what is called a multiple feed in which plural sheets are picked up in such a manner as to lie one on another, the single top sheet is separated from the lower sheets by a separating action of a separator such as a separation pad, a retarding roller, or the like. The ends of separated lower sheets are hooked on a hook member of a returning lever and the lower sheets are thereby returned to a feeding tray. 
     Japanese Patent Publication No. 11-71036A discloses a structure that two separation pads. A main separation pad first acts on sheets to perform a first separating operation and then an auxiliary separation pad acts on the sheets to perform a second separating operation, thereby separating the sheets reliably. Capable of rotating in both of the normal and reverse directions, the auxiliary separation pad disclosed in this publication also has a function of returning lower sheets to the feeding tray by rotating in the reverse direction when a hopper separates the sheets from a feeding roller. As such, it can be said that the auxiliary separation pad has also the sheet returning function. 
     However, in a case where many stacked sheets having a large size such as A3 sheets are subjected to the returning operation, the returning lever or the auxiliary separation pad cannot return those sheets by itself to the prescribed positions on the feeding tray because the returning force is not strong enough to sustain the weight of those sheets. More specifically, as shown in  FIG. 8 , among sheets P that are pressed against the feeding roller  102  as the hopper  101  is elevated, the single top sheet P 0  is fed into a transporting path while several top sheets P 1  are remained in such a condition as to be somewhat pulled from sheets P 2  located under themselves toward the transporting path. 
     Because of the frictional force caused by their own weight, the lower sheets P 2  also remain in close contact with the sheets P 1  without sliding down on a support frame  103  below. Even if the returning lever  104  or the auxiliary pad disclosed in this publication is caused to operate in this state, only the upper sheets P 1  are subjected to the sheet returning action. Since the lower sheets P 2  stand by behind in such a manner as to be in close contact with the upper sheets P 1  and hence there is no return space, the attempt of returning the sheets P 1  is not completed. 
     One conventional measure against the above problem is to decrease the attachment angle of a paper support attached to the feeding tray so that not all of the weight of sheets P is exerted on the support frame  103  and the returning lever  104  or the like. However, decreasing the attachment angle of the paper support leads to size increase of the ink jet printer and is a factor of disordering the arrangement of the sheets P. Further, it is not certain whether sheets P can be returned onto the feeding tray reliably even by decreasing the attachment angle of the paper support. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the invention to provide a returner which can always return remaining recording media (target media) to the prescribed positions on a medium feeding tray reliably, even in the case where heavy, large-size recording media or a large number of recording media are stacked on the medium feeding tray, and can thereby contribute to size reduction of an apparatus. 
     It is also an object of the invention to provide an automatic feeder incorporating such a returner, and a recording apparatus or a liquid ejecting apparatus provided with such an automatic feeder. 
     In order to achieve the object, according to the invention, there is provided an automatic feeder, adapted to feed a plurality of media one by one to a downstream section, comprising: 
     a feeding tray, adapted to support the media thereon; 
     a feeding roller; 
     a hopper, provided on the feeding tray so as to be movable in a first direction for pushing the media toward the feeding roller so that a top one of the media comes in contact with the feeding roller, and in a second direction opposite to the first direction; 
     a separator, adapted to separate a first group including at least one of the media which is situated under the top one of the media from the top one, so that only the top one is fed to the downstream section by rotation of the feeding roller; 
     a returning lever, pivotable about a pivot shaft interlockingly with the feeding roller and adapted to return a second group including at least one of the media in the first group, which has been proceeded from a prescribed position to the downstream section together with the top one of the media, to the feeding tray; and 
     a holder, having a supporting face on which a third group including at least one of the media in the first group which is situated under the second group is placed, the holder being slidable in the second direction interlockingly with the movement of the hopper in the second direction to move the third group toward the feeding tray to secure a space to which the second group is returned by the returning lever. 
     With this configuration, it is possible to reliably return heavy, large-size media or a large number of stacked media that would not be returned to the prescribed positions on the feeding tray by the returning lever alone. This in turn makes it possible to smoothly perform the media feeding operations that are performed successively. Further, this aspect of the invention contributes to downsizing of an apparatus because it is not necessary to change the attachment angles of the feeding tray and a paper support or the like that is attached to the feeding tray. 
     A high-friction member may be provided on the supporting face of the holder. In this case, the friction acting on the lower media, among the remaining media, whose ends are in contact with the supporting face of the holder, whereby the lower media can reliably be supported by the holder and be returned to the prescribed positions on the feeding tray. 
     The automatic feeder may further comprise a frame member having a supporting face on which the first group is placed, the frame member formed with a groove extending in the second direction. The holder may comprises a projection slidably fitted with the groove. In this case, the holder is allowed to slide smoothly in the second direction by virtue of the guide action of the projection and the groove. 
     The automatic feeder may further comprise an elastic member urging the holder in the first direction. The holder may comprise a projection adapted to engage with the hopper when the hopper is moved in the second direction. In this case, the holder is moved in the second direction because of its engagement with the hopper and is moved in the first direction by the urging action of the elastic member. Therefore, the hopper is used as a member for sliding the holder, which means efficient use of the components. 
     The automatic feeder may further comprise a rotation cam provided on the pivot shaft of the returning lever. The holder may be formed with a cam follower so that the holder is pivotable in accordance with rotation of the rotation cam, thereby varying an inclination angle of the supporting face. 
     In this case, the holder lifts up the media on the supporting face while sliding in the second direction, thereby helping the operation of returning the media onto the feeding tray. 
     According to the invention, there is also provided a recording apparatus incorporating the above automatic feeder and comprising a recording head, disposed in the downstream section and operable to record information on the top one of the media fed by the feeding roller. 
     In this case, since the transporting accuracy of recording media is increased, high-quality recording is enabled. 
     According to the invention, there is also provided a liquid ejecting apparatus incorporating the above automatic feeder and comprising a liquid ejecting head, disposed in the downstream section and operable to eject liquid toward the top one of the media fed by the feeding roller. 
     In this case, since the transporting accuracy of target media is increased, high-quality landing of the liquid on the target medium is enabled. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above objects and advantages of the present invention will become more apparent by describing in detail preferred exemplary embodiments thereof with reference to the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of an ink jet printer according to one embodiment of the invention; 
         FIG. 2  is a side section view of an internal structure of the ink jet printer; 
         FIG. 3  is an enlarged perspective view of a returner and its peripheries in the ink jet printer; 
         FIG. 4  is an enlarged side section view of the returner and its peripheries, showing a state that a sheet feeding operation begins; 
         FIG. 5  is an enlarged side section view of the returner and its peripheries, showing a state that a sheet returning action begins; 
         FIG. 6  is an enlarged side section view of the returner and its peripheries, showing a state that the sheet returning action is executing; 
         FIG. 7  is an enlarged side section view of the returner and its peripheries, showing a state that the sheet returning action is finished; 
         FIG. 8  is an enlarged side section view of a related-art returner and its peripheries; 
         FIG. 9  is a perspective view of an internal structure of an automatic feeder in the ink jet printer; 
         FIG. 10  is an enlarged perspective view of a main part of the automatic feeder; and 
         FIG. 11  is an enlarged side section view of the main part of the automatic feeder. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of the invention will be described below in detail with reference to the accompanying drawings. An ink jet printer  100  shown in  FIG. 1  is exemplified as the recording apparatus or the liquid ejecting apparatus of the invention. 
     The ink jet printer  100  comprises: a top cover  4  which occupies a front portion of the top face of a printer main body  3 ; manipulation buttons  6  located at the top-right corner of the front face of the printer main body  3 ; a disc tray cover  7  which occupies a top portion of the front face of the printer main body  3 ; an ejection stacker  50  which occupies a bottom-front portion of the printer main body  3 ; and an automatic feeder  2  which occupies a top-rear portion of the printer main body  3 . As such, the ink jet printer  100  is an ink jet printer capable of dealing with a recording medium P (hereinafter referred simply as “sheet P”) as an example of a large-size (e.g., A3) target medium. 
     The top cover  4  is a door cover in which the front side can be opened upward with a hinge portion (located on the rear side; not shown) as a pivot center. When the top cover  4  is opened, access to the inside of the printer main body  3  is enabled and maintenance work such as ink cartridge replacement can be performed. The disc tray cover  7  is a cover which covers an insertion slot of a disc tray (not shown). The disc tray cover  7  is such that its bottom side can be opened forward with a hinge portion (located on the top side; not shown) as a pivot center. 
     When the disc tray is used, the disc tray cover  7  is opened and an optical disc such as a CD-R, a CD-RW, or a DVD is set on the disc tray with its label face up and inserted through the disc tray insertion slot. When the disc tray is inserted manually to a prescribed position, then the disc tray is automatically guided into a transporting path. The top side of the ejection stacker  50  can be opened forward with a hinge portion (located on the bottom side; not shown) as a pivot center. The ejection stacker  50  is opened during execution of recording. The top face of the opened ejection stacker  50  serves as a stacking face  51  on which sheets P which have been subjected to the recording are to be stacked. 
     The automatic feeder  2  is equipped with: a feeding tray  5  on which plural sheets P can be stacked; a hopper  16  for pushing up the sheets P on the feeding tray  5 ; a feeding roller  14  for picking up upper sheets P on the feeding tray  5  by a pinched feeding action of itself and the hopper  16 ; a separation pad  8  for separating following ones of multiply-fed sheets P from the top sheet P to send out only the top sheet P finally; and a returner  1  for returning the separated following sheets P onto the feeding tray  5 . 
     As shown in  FIG. 1 , a cover  9  which also serves as the feeding tray  5  occupies a rear portion of the top face of the printer main body  3 . The front side of the cover  9  is opened upward and then obliquely rearward with a hinge portion (located on the rear side; not shown) as a pivot center, whereby the feeding tray  5  which is an inner face of the cover  9  is made usable. 
     Next, the internal structure of the ink jet printer  100  will be outlined in the same order as a sheet P goes along the transporting path. First of all, the feeding tray  5  on which sheets P are to be stacked is provided at the upstream end in the transporting direction. The feeding tray  5  is provided with edge guides (not shown) which are brought in contact with the side ends (edges) the sheets P and guide them so that they are transported smoothly in a secondary scanning direction Y which is the transporting direction of the sheet P. The sheets P on the feeding tray  5  are pushed up toward the feeding roller  14  by the hopper  16  which rises with prescribed timing as a rotary shaft  17  of the feeding roller  14  is rotated. As the feeding roller  14  rotates, sheets P are picked up in order from the top sheet P by a unit number of sheets P at a time with the aid of the separation pad  8  disposed in the vicinity of the feeding roller  14 , and then sent out downstream in the transporting direction. 
     A detection lever (not shown) for detecting passage of a sheet P is disposed downstream of the feeding roller  14 . Transporting rollers  19  that are a driving roller  19   a  and a follower roller  19   b  are disposed downstream of the detection lever. Of the transporting rollers  19 , the follower roller  19   b  is rotatably supported at the downstream end of a roller holder  18  which is provided so as to be able to pivot about a pivot shaft  18   a , and is urged by a torsion coil spring  18   b  so as to always establish a nip state that the follower roller  19   b  is in pressure contact with the driving roller  19   a.    
     An auxiliary pressing roller  18   c , which is disposed downstream of the roller holder  18  in the transporting direction, is rotatably supported by a roller holder  18   d  for the auxiliary pressing roller so as to be capable of follower rotation. The auxiliary pressing roller  18   c  is provided for such purposes as prevention of head rubbing that is caused by a rise of the tail of a sheet P. A sheet P being transported while being pinched by the transporting rollers  19  goes under the auxiliary pressing roller  18   c  and is introduced to a recording position  26 . 
     A carriage  10  which is supported by a guide shaft  12  and can reciprocate in a primary scanning direction X is provided at the recording position  26  for performing recording on a sheet P. A recording head  13  for performing recording by ejecting ink toward a sheet P or the like is mounted on the bottom face of the carriage  10 . An ink cartridge (not shown) is attached to the carriage  10 . 
     A platen  28  which is opposed to the recording head  13  and defines a platen gap PG between the head face of the recording head  13  and a sheet P or the like is disposed under the recording head  13 . Desired recording is performed on the almost entire recording face of a sheet P or the like by alternately repeating an operation of transporting the sheet P or the like by a prescribed transport length between the carriage  10  and the platen  28  in the secondary scanning direction Y which is perpendicular to the primary scanning direction X and an operation of causing the recording head  13  to eject ink toward the sheet P or the like while the recording head  13  is reciprocated once in the primary scanning direction X. The platen gap PG is a very important factor for high-precision recording and is adjusted when necessary in accordance with a variation in the thickness of the sheet P or use of the disc tray, for example. 
     Ejecting rollers  20  that are an driving roller  20   a  and a follower roller  20   b  are disposed downstream of the recording head  13 . Ejection assistance rollers  20  for assisting ejection of a sheet P is disposed downstream of the ejecting roller  20  in the transporting direction. The ejection assistance rollers  20  are a driving roller  22   a  and a follower roller  22   b . A sheet P that has been ejected by the ejection assistance rollers  22  are ejected to the stacking face  51  of the ejection stacker  50  which is disposed downstream of the ejection assistance rollers  22  in the transporting direction. 
     Each of the follower roller  20   b  and the follower roller  22   b  is a spur roller having plural teeth at the outer circumference and is rotatably supported by an individual roller holder. The follower roller  19   b  is disposed in such a manner that its axis is located somewhat downstream of the axis of the driving roller  19   a  in the transporting direction. The above-described arrangement causes a sheet P to assume, between the transporting rollers  19  and the electing rollers  20 , a curved shape commonly called “reverse warp” that the sheet P is curved slightly so as to be convex downward. As a result, the sheet P that is opposed to the recording head  13  is pressed against the platen  28 , whereby the sheet P is prevented from rising and the recording is performed normally. 
     The returner  1  is equipped with: a returning lever  31  which pivots about a rotary shaft  30  as the feeding roller  14  rotates; and a holder  32  which slides in the same direction as the hopper  16  as the hopper  16  moves in an escaping direction (obliquely downward). The free end of the returning lever  31  is provided with a hook member  33 . As shown in  FIGS. 4-7  the returning lever  31  is pivoted counterclockwise and the hook member  33  is thereby engaged with the bottom ends of upper sheets P 1  of remaining, multiply-fed sheets P. In this manner, the returning lever  31  pushes and returns the upper sheets P 1  toward the feeding tray  5 . A cam  34  is attached to the rotary shaft  30  of the returning lever  31 . The details of the cam  34  will be described later. 
     The holder  32  is a member which acts on sheets P 2  that are lower than the upper sheets P 1  and mainly serves to return the lower sheets P 2  toward the feeding tray  5 . When the lower sheets P 2  are moved toward the feeding tray  5 , an escaping space  35  for the upper sheets P 1  is secured, which allows the returning lever  31  to return the upper sheets P 1  reliably. 
     The top face of the holder  32  is a supporting face  36  which is relatively smooth and supports the bottom ends of the sheets P that are stacked on the feeding tray  5 . A high-friction material  37  which is shaped like a rectangular flat plate, for example, is stuck to the supporting face  36  to increase the ability of holding the sheets P that are stacked on the feeding tray  5 . A support frame  38  which is a part of a frame of the automatic feeder  2  and supports the bottom ends of the sheets P that are stacked on the feeding tray  5  is disposed under the feeding tray  5 . The support frame  38  is formed with a guide groove  40  which is engaged with a guide pin  39  which projects horizontally from the side face of the holder  32  at a position close to its rear end (i.e., close to the hopper  16 ). 
     The guide pin  39  is a rod-shaped member and the guide groove  40  is a groove whose width is slightly greater than the diameter of the guide pin  39 . Therefore, the holder  32  can slide approximately by the length of the guide groove  40  over which the guide pin  39  can move. An engagement projection  41  which is engaged with the hopper  16  when the hopper  16  is moved in the escaping direction projects upward from the top face of the holder  32  at a position close to its rear end. As such, the holder  32  can be moved rearward by the escaping action of the hopper  16 . 
     On the other hand, a front portion of the holder  32  is formed with a hook  42 . One end of a spring  43  which is stretched between the holder  32  and the support frame  38  is hooked on the hook  42 . The other end of the spring  43  is hooked on a hook  44  of the support frame  38 . As such, the holder  32  is always urged forward by the spring  43 . When engaged with the hopper  16 , the holder  32  is moved rearward against the urging force of the spring  43 . The holder  32  can move forward when disengaged from the hopper  16 . 
     The bottom face of the holder  32  is formed with a cam follower  45  which is brought in contact with the cam  34  and thereby transmits driving force from the cam  34  to the holder  32 . The cam  34  starts to contact the cam follower  45  at the beginning of a feeding operation of sheets P (see  FIG. 4 ). The cam height increases gradually as shown in  FIGS. 5 and 6  and reaches a maximum at the end of the operation of returning sheets P (see  FIG. 6 ). 
     In the state of  FIG. 7  in which the hopper  16  is lowered further from the position of  FIG. 6 , the cam  34  has slipped down the cam follower  45  and their contact is canceled. 
     Next, the operation of the returner  1  will be described separately for (1) at the beginning of the sheet feeding operation, (2) at the beginning of a sheet returning operation, (3) in the course of the sheet returning operation, and (4) at the end of the sheet returning operation. 
     (1) As shown in  FIG. 4 , the hopper  16  is elevated and the sheets P stacked on the feeding tray  5  are thereby lifted up. The top sheet P 0  of the sheets P stacked on the feeding tray  5  is pressed against the feeding roller  14 . Then, upper sheets P 1  including the top sheet P 0  are pulled out of the feeding tray  5  as the feeding roller  14  rotates. The upper sheets P 1  excluding the top sheet P 0  are separated from the top sheet P 0  by the separating action of the separating pad  8  and remain halfway in the transporting path.
 
(2) After an end of a contact face  14   a  of the feeding roller  14  has passed the upper sheets P 1 , as shown in  FIG. 5 , the hopper  16  starts to be lowered. The hook member  33  of the returning lever  31  goes into the transporting path and is engaged with the bottom ends of the remaining upper sheets P 1 . The holder  32  is slid rearward as the hopper  16  goes down, and is rotated counterclockwise (in  FIG. 5 ) as the cam height of the cam  34  increases.
 
(3) As the hopper  16  goes down further, as shown in  FIG. 6  the holder  32  is moved rearward with its guide pin  39  guided by the guide groove  40 . During this course, since the high-friction material  37  is stuck to the supporting face  36  of the holder  32 , the remaining lower sheets P 2  are moved rearward together with the holder  32 , as a result of which an escaping space  35  is formed between the upper sheets P 1  and the lower sheets P 2 . As the returning lever  31  is rotated in such a situation, the hook member  33  of the returning lever  31  pushes and returns the remaining upper sheets P 1 . The upper sheets P 1  reach the escaping space  35  which is formed over the supporting face  36 .
 
(4) In the above state, the inclination angle of the holder  32  is at the maximum and the centers of gravity of the upper sheets P 1  and the lower sheets P 2  on the supporting face  36  are much deviated to the feeding tray  5  side. The hopper  16  is lowered further from this position and the holder  32  is thereby moved rearward. As a result, as shown in  FIG. 7 , the cam  34  slips down the cam follower  45  and their contact is canceled. At the same time, the inclination angle of the holder  32  is decreased. Resulting impact is transmitted to the upper sheets P 1  and the lower sheets P 2  on the supporting face  36 , whereby the sheets P 1  and P 2  which have remained on the feeding tray  5  are returned to the prescribed positions on the feeding tray  5  as shown in the figure.
 
     Although the basic configurations of the returner  1  according to the invention, the automatic feeder  2  having the returner  1 , the recording apparatus  100  or the like having the returner  1  are as described above, it is naturally possible to, for example, modify or omit parts of the configurations without departing from the spirit and scope of the invention. For example, the friction of the supporting face  36  of the holder  32  may be increased by forming the supporting face  36  itself using a material having a large coefficient of friction or subjecting the supporting face  36  to proper face processing or the like. In this case, it is not necessary to stick the high-friction material  37 . 
     By modifying the shape of the guide groove  40  properly or providing plural guide pins  39  and plural guide grooves  40 , it is also possible to cause the holder  32  to not only move rearward but also rotate as the hopper  16  moves in the escaping direction. This makes it possible to omit the cam  34  and the cam follower  45 . Further, the returner  1  according to the invention and the automatic feeder  2  can be applied to, in addition to the recording apparatus  100  or the like, various kinds of transport apparatus which handle sheet-like transport objects. 
       FIG. 9  is a perspective view outlining the internal structure of an automatic feeder according to the invention.  FIG. 10  is an enlarged perspective view of an important part of  FIG. 9 .  FIG. 11  is a side section view of the important part of  FIG. 9 . A thin-plate-like friction member  60  made of a cork material is provided on the supporting face  36  in a region (a left-hand region in  FIG. 9 ) where the sheet feeding mechanism (i.e., the feeding roller  14  etc.) is not provided. A front portion  64  of the friction member  60  is slightly curved so as to convex toward a frame supporting face  36  and its rear portion  62  is slightly curved so as to be concave toward the supporting face  36 . That is, the friction member  60  is provided so as to cover the supporting face  36  in the transporting direction in a reliable manner. In this embodiment, the thin-plate-like friction member  60  is stuck to the supporting face  36 . The curvature of the convex shape of the front portion  64  is set so that its projection length does not cause an unduly heavy load during a sheet feed but the friction between the sheet ends and the supporting face  36  (see  FIGS. 10 and 11 ). The friction member  60  is provided so that sheets that have been returned by the returning lever  31  after a sheet feed operation stay reliably at the return destination positions by virtue of the friction. 
     The reason why the friction member  60  is provided in the above manner is as follows. By increasing the frictional resistance between the sheet ends and the supporting face  36  by means of the friction member  60 , it is intended to allow the sheet ends to stay at the prescribed positions reliably when sheets are returned to those positions. In a structure in which the friction member  60  is not provided at the above-mentioned position, one side (not associated with the sheet feeding mechanism) of the end (edge) of each sheet is supported only by the supporting face (free state). In a sheet feed operation, the two sides of the end of each sheet that are associated with and not associated with the sheet feeding mechanism, respectively, are not fed simultaneously; the free portion tends to be fed earlier than the intended timing. In contrast, where the friction member  60  is provided, when a sheet feed operation is started, the two sides of the end of each sheet are fed simultaneously, that is, the phenomenon that one side is fed earlier does not occur.

Technology Classification (CPC): 1