Patent Publication Number: US-10308454-B2

Title: Sheet conveying apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority from Japanese Patent Application No. 2017-005569, which was filed on Jan. 17, 2017, the disclosure of which is herein incorporated by reference in its entirety. 
     BACKGROUND 
     Technical Field 
     The following disclosure relates to a sheet conveying apparatus configured to covey sheets such as paper. 
     Description of Related Art 
     There is known an apparatus configured to convey sheets and having a first supply roller (roller) supported at a distal end of a pivotable arm. The roller is rotated while being held in contact with a front surface of an uppermost one of the sheets stored in a supply tray, so that the uppermost sheet is conveyed. 
     SUMMARY 
     In the known apparatus, an angle defined by the arm and the sheets in the supply tray on an upstream side of the sheets in a sheet conveyance direction, namely, a contact angle, changes in a time period from a fully loaded state of the supply tray in which a maximal amount of the sheets are loaded on the supply tray to a near empty state of the supply tray in which a minimal amount of the sheets are loaded on the supply tray. Specifically, the contact angle increases with a decrease in the amount of the sheets loaded on the supply tray. As a result, a pressing force applied by the roller to the sheets becomes large, so that a plurality of sheets are likely to be conveyed in an overlapping state, namely, multiple feeding of the sheets tends to occur. 
     Accordingly, one aspect of the disclosure relates to a sheet conveying apparatus capable of preventing or reducing an occurrence of multiple feeding of sheets in a time period from the fully loaded state to the near empty state. 
     In one aspect of the disclosure, a sheet conveying apparatus including: a container for storing a stack of a plurality of sheets; a roller rotatable about a rotation shaft parallel to the plurality of sheets stored in the container and configured to convey the plurality of sheets one by one in a conveyance direction by rotating about the rotation shaft while being held in contact with a front surface of the plurality of sheets stored in the container, an arm including a supporter that rotatably supports the roller, the arm being pivotable about an arm pivot shaft parallel to the rotation shaft while the supporter is located downstream of the arm pivot shaft in the conveyance direction, and a presser plate configured to press the plurality of sheets stored in the container toward the roller and to be pivotable about a presser-plate pivot shaft parallel to the rotation shaft, wherein the presser plate includes a bend portion disposed between: a downstream end of the presser plate in the conveyance direction; and the presser-plate pivot shaft, the bend portion being bent or bendable, wherein a distal portion which is a portion of the presser plate ranging from the downstream end to the bend portion and which faces the roller and a basal portion which is a portion of the presser plate ranging from the bend portion to the presser-plate pivot shaft define a bend angle when the distal portion and the basal portion are bent, the bend angle being an angle defined on one side of the presser plate that is farther from the arm, the bend angle being maintained at an obtuse angel when a state of the container is a first-amount loaded state in which a first amount of the plurality of sheets are loaded on the container, and wherein a contact angle of the arm and the plurality of sheets at a contact position, at which the arm and the plurality of sheets on the presser plate contact, is smaller than a maximum angle in a time period in which the state of the container changes from a maximally loaded state in which a maximal amount of the plurality of sheets are loaded on the container to the first-amount loaded state, the maximum angle being an angle defined by: (i) the basal portion in the maximally loaded state; and (ii) the arm the roller of which contacts the presser plate which is the presser plate in the maximally loaded state and on which it is assumed that the plurality of sheets are not loaded in the maximally loaded state. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects, features, advantages, and technical and industrial significance of the present disclosure will be better understood by reading the following detailed description of embodiments, when considered in connection with the accompanying drawings, in which: 
         FIG. 1  is a cross-sectional view of a printer according to a first embodiment, the view being taken along a plane parallel to a vertical direction; 
         FIG. 2  is a cross-sectional view showing a fully loaded state of a sheet supply tray of the printer according to the first embodiment, the view being taken along the plane parallel to the vertical direction; 
         FIG. 3  is a cross-sectional view showing a state of the sheet supply tray of the printer according to the first embodiment in a time period from the fully loaded state till before reaching a near empty state, the view being taken along the plane parallel to the vertical direction; 
         FIG. 4  is a cross-sectional view showing the near empty state of the sheet supply tray of the printer according to the first embodiment, the view being taken along the plane parallel to the vertical direction; 
         FIG. 5  is a cross-sectional view showing the fully loaded state of the supply tray of a printer according to a second embodiment, the view being taken along the plane parallel to the vertical direction; 
         FIG. 6  is a cross-sectional view showing a state of the supply tray of the printer according to the second embodiment in the time period from the fully loaded state till before reaching the near empty state, the view being taken along the plane parallel to the vertical direction; 
         FIG. 7  is a cross-sectional view showing the near empty state of the sheet supply tray of the printer according to the second embodiment, the view being taken along the plane parallel to the vertical direction; 
         FIG. 8  is a cross-sectional view showing the fully loaded state of the supply tray of a printer according to a third embodiment, the view being taken along the plane parallel to the vertical direction; 
         FIG. 9  is a cross-sectional view showing a state of the sheet supply tray of the printer according to the third embodiment in the time period from the fully loaded state till before reaching the near empty state, the view being taken along the plane parallel to the vertical direction; and 
         FIG. 10  is a cross-sectional view showing the near empty state of the sheet supply tray of the printer according to the third embodiment, the view being taken along the plane parallel to the vertical direction. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     First Embodiment 
     As shown in  FIG. 1 , a printer  1  according to a first embodiment includes: a supply tray  10  capable of storing a stack of a plurality of sheets  100 ; a conveyor  20  configured to convey an uppermost one of the sheets  100  stored in the supply tray  10  along a conveyance path R; a recording portion  30  configured to perform recording on the sheet  100  conveyed by the conveyor  20 ; a platen  40  which is opposed to the recording portion  30 ; an output tray  50  for receiving the sheet  100  which has been conveyed by the conveyor  20 ; a controller  60  configured to control the conveyor  20 , the recording portion  30 , and other devices; and a sensor  70  configured to detect an amount of the sheets  100  loaded or stacked on the supply tray  10 . 
     The conveyor  20  includes: a roller  11  disposed so as to be in contact with an uppermost one of the sheets  100  stored in the supply tray  10 ; a roller pair  21  disposed upstream of the recording portion  30  in the conveyance path R; a roller pair  22  disposed downstream of the recording portion  30  in the conveyance path R; and guide plates  20   g  that define the conveyance path R. 
     The roller  11  has a rotation shaft  11   x  parallel to the sheets  100  stored in the supply tray  10 . The roller  11  rotates about the rotation shaft  11   x  while being in contact with a front surface of the uppermost one of the sheets  100  stored in the supply tray  10 , so as to convey the uppermost sheet  100  in a conveyance direction. 
     The supply tray  10  has a separation wall  10   w . The separation wall  10   w  is constituted by one of four walls of the supply tray  10  that is located downstream of the roller  11  in the conveyance direction. When a plurality of sheets  100  are supplied by rotation of the miler  11 , the separation wall  10   w  contacts one of the plurality of sheets  100  which is farthest from the roller  11  and gives the farthest sheet  100  to a resistance, so as to separate the uppermost sheet  100  from other sheets. To this end, the separation wall  10   w  is provided with a separation member and separation rollers (not shown). The separation member may be a plate member formed of a material having a high frictional resistance such as cork or rubber or may be a member having a plurality of protrusions formed of resin or metal. Feed rollers are disposed so as to be opposed to the separation rollers. The feed rollers always rotate forwardly to convey the sheet  100  in the conveyance direction. The separation rollers rotate forwardly when one sheet  100  is nipped between the separation rollers and the feed rollers and rotate reversely when a plurality of sheets  100  are nipped therebetween. 
     The rotation shaft  11   x  of the roller  11  is rotatably supported by a distal end (i.e., a supporter  12   a ) of the arm  12 . The arm  12  is pivotable about a pivot shaft  12   x  provided at a basal end of the arm  12  located opposite to the distal end while the supporter  12   a  is located downstream of the pivot shaft  12   x  in the conveyance direction. The pivot shaft  12   x  is parallel to the rotation shaft  11   x  and is rotatably supported by a housing (not shown) of the printer  1 . 
     The arm  12  supports gears  12   g   1 - 12   g   9 . The gears  12   g   1 - 12   g   9  are in mesh with one another. The gear  12   g   1  is fixed to the rotation shaft  11   x , the gear  12   g   9  is in mesh with a shaft  11 Mx of a drive motor  11 M, and the gears  12   g   2 - 12   g   8  connect the gear  12   g   1  and the gear  12   g   9 . When the drive motor  11 M is driven, the gears  12   g   1 - 12   g   9  are rotated, so that a drive force of the drive motor  11 M is transmitted to the roller  11 , and the roller  11  is rotated. 
     The supply tray  10  pivotably supports: a presser plate  13  for pressing the sheets  100  stored in the supply tray  10  toward the roller  11 ; and a push-up member  14  for pushing up the presser plate  13  from below so as to pivot the presser plate  13 . A pivot shaft  13   x  of the presser plate  13  and a pivot shaft  14   x  of the push-up member  14  are parallel to the rotation shaft  11   x  and are rotatably supported by the supply tray  10 . The presser plate  13  is pivotable about the pivot shaft  13   x  while its downstream end  13   t  is located downstream of the pivot shaft  13   x  in the conveyance direction. The push-up member  14  is pivotable about the pivot shaft  14   x  while its downstream end  14   t  is located downstream of the pivot shaft  14   x  in the conveyance direction. 
     The presser plate  13  includes, between the downstream end  13   t  and the pivot shaft  13   x , a bend portion  13   c  which is bendable. The presser plate  13  includes a distal member  13   a  shaped like a plate and having the downstream end  13   t  and a basal member  13   b  shaped like a plate and at which the pivot shaft  13   x  is provided. A boundary between the distal member  13   a  and the basal member  13   b  corresponds to the bend portion  13   c.    
     Front surfaces  13   a   1 ,  13   b   1  of the distal member  13   a  and the basal member  13   b  which face the roller  11  respectively constitute a distal region  13 A and a basal region  13 B. The distal region  13 A is a region ranging from the downstream end  13   t  to the bend portion  13   c . The basal region  13 B is a region ranging from the bend portion  13   c  to the pivot shaft  13   x.    
     A rotation shaft  13   ax  is provided at an upstream end of the distal member  13   a  which is located opposite to the downstream end  13   t  in the conveyance direction and at which the bend portion  13   c  is provided. The rotation shaft  13   ax  is rotatably supported by a downstream end of the basal member  13   b  which is located opposite to an upstream end of the basal member  13   b  in the conveyance direction at which the pivot shaft  13   x  is provided. That is, the distal member  13   a  and the basal member  13   b  are connected to each other through the bend portion  13   c  such that a bend angle α is changeable. In the present embodiment, the bend angle α is an angle defined, on one side of the presser plate  13  that is farther from the arm  12 , by a portion of the presser plate  13  corresponding to the distal region  13 A and a portion of the presser plate  13  corresponding to the basal region  13 B. 
     An extending portion  13   ae  is provided on a back surface  13   a   2  (opposite to the front surface  13   a   1 ) at the upstream end of the distal member  13   a . The extending portion  13   ae  extends in a direction which intersects the distal region  13 A and which is directed from the bend portion  13   c  toward the pivot shaft  13   x.    
     The push-up member  14  is configured to pivot about the pivot shaft  14   x  by control of the controller  60  while its downstream end  14   t  is held in contact with the back surface  13   b   2  of the basal member  13   b , so as to cause the basal member  13   b  to be pivoted about the pivot shaft  13   x . The controller  60  is configured to receive a signal from the sensor  70  and to drive the pivot shaft  14   x  in accordance with the amount of the sheets  100  stacked on the supply tray  10 , thereby controlling a posture of the push-up member  14  and accordingly a posture of the presser plate  13 . 
     Referring next to  FIGS. 2-4 , there will be explained operations of the presser plate  13  and the push-up member  14  in a time period in which a state of the supply tray  10  changes from a state in which a maximal amount of the sheets  100  are loaded on the supply tray  10  (hereinafter referred to as “fully loaded state” where appropriate) to a state in which a first amount of the sheets  100  are loaded on the supply tray  10 , namely, a single sheet is loaded on the supply tray  10  in the present embodiment (hereinafter referred to as “mar empty state” where appropriate). The fully loaded state is one example of “maximally loaded state”, and the near empty state is one example of “first-amount loaded state”. 
     As shown in  FIG. 2 , the bend angle α is equal to 180° in the fully loaded state. In this instance, the downstream end  14   t  of the push-up member  14  is held and sandwiched by and between the extending portion  13   ae  and the basal member  13   b.    
     In a time period from the fully loaded state till before reaching the near empty state, as the amount of the sheets  100  stacked on the supply tray  10  decreases, the push-up member  14  is pivoted by control of the controller  60 , as shown in  FIG. 3 . In this instance, the downstream end  14   t  of the push-up member  14  moves in a direction directed from the bend portion  13   c  toward the pivot shaft  13   x  along the back surface  13   b   2  of the basal member  13   b  while the downstream end  14   t  is interposed between the extending portion  13   ae  and the basal member  13   b . The push-up member  14  pushes up the downstream end of the basal member  13   b , whereby the basal member  13   b  is pivoted about the pivot shaft  13   x  toward the arm  12 . The downstream end  14   t  and the extending portion  13   ae  are shaped such that, in the time period from the fully loaded state till before reaching the near empty state, the distal member  13   a  is moved upward with its posture kept horizontal and the bend angle α gradually becomes smaller. More specifically, in the time period from the fully loaded state till before reaching the near empty state, the downstream end  14   t  of the push-up member  14  nearer to the bend portion  13   c  is held in contact with both of the basal member  13   b  and the extending portion  13   ae  while being sandwiched therebetween. In this instance, a force received by the distal member  13   a  from the sheets  100  acts on the basal member  13   b  through the extending portion  13   ae  and the push-up member  14 . Thus, the posture of the distal member  13   a  is kept horizontal. As shown in  FIGS. 2 and 3 , in the time period from the fully loaded state till before reaching the near empty state, the downstream end  14   t  of the push-up member  14  is located at a height level higher than the extending portion  13   ae , and the downstream end of the basal member  13   b  nearer to the bend portion  13   c  is located at a height level higher than the downstream end  14   t  of the push-up member  14 . According to the positional relationship among the distal member  13   a , the basal member  13   b , and the push-up member  14 , the downstream end  14   t  of the push-up member  14  is sandwiched between the basal member  13   b  and the extending portion  13   ae  with high reliability. 
     At the same time when the near empty state is established, the push-up member  14  moves away from between the extending portion  13   ae  and the basal member  13   b , and the bend angle α is kept defined by contact of the extending portion  13   ae  and the basal member  13   b , as shown in  FIG. 4 . That is, the downstream end  14   t  of the push-up member  14  is spaced apart from the extending portion  13   ae  and is held in contact with the lower surface (the back surface  13   b   2 ) of the basal member  13   b.    
     Thus, the push-up member  14  functions as an angle adjuster for adjusting the bend angle α defined by the distal member  13   a  and the basal member  13   b.    
     In the time period in which the state of the supply tray  10  changes from the fully loaded state to the near empty state, namely, in the time period from the fully loaded state to the near empty state, the bend angle α is maintained at an obtuse angle, and the distal region  13 A is kept opposed to the roller  11 . 
     In the time period from the fully loaded state to the near empty state, a contact angle β, i.e., an angle defined, on the upstream side in the conveyance direction, by the arm  12  and a roller-contacting portion  100   a  of the sheets  100  on the presser plate  13  which is in contact with the roller  11 , is constant (The contact angle β may be referred to as an angle defined by the arm and the sheets at a contact position of the arm and the sheets.) That is, the contact angle β is equal to a minimum angle βmin (which is the contact angle in the fully loaded state and is equal to 0° in the present embodiment). Further, the contact angle β is kept less than a maximum angle βmax which is an angle defined, on the upstream side in the conveyance direction, by: (i) the portion of the presser plate  13  corresponding to the basal region  13 B in the fully loaded state; and (ii) the arm  12  the roller  11  of which contacts the presser plate  13  which is the presser plate  13  in the fully loaded state and on which it is assumed that the sheets  100  are not loaded in the fully loaded state, i.e., the arm  12  indicated by the long dashed double-short dashed line in  FIG. 2 . 
     An angle γ defined by the portion of the presser plate  13  corresponding to the distal region  13 A and the separation wall  10   w  is also kept constant in the time period from the fully loaded state to the near empty state. 
     As described above, according to the present embodiment, the contact angle β is kept less than the maximum angle βmax in the time period from the fully loaded state to the near empty state, so that it is possible to prevent a plurality of sheets from being conveyed in an overlapping state. In other words, an occurrence of multiple feeding of the sheets is obviated. 
     In the time period from the fully loaded state to the near empty state, the angle γ defined by the portion of the presser plate  13  corresponding to the distal region  13 A and the separation wall  10   w  is kept constant, enabling the sheets to be conveyed with high stability. 
     In the time period from the fully loaded state to the near empty state, the contact angle β is larger than the minimum angle βmin. When the contact angle β becomes smaller, a pressing force of the roller  11  with respect to the sheets  100  becomes smaller, so that the sheet  100  cannot be conveyed due to a slippage between the roller  11  and the sheet  100  even when the roller  11  is rotated, namely, a feeding failure is likely to occur. According to the configuration in which the contact angle β is larger than the minimum angle βmin in the time period from the fully loaded state to the near empty state, it is possible to prevent or reduce an occurrence of the feeding failure. 
     In the near empty state, the contact angle β is larger than the minimum angle βmin. In this case, it is possible to prevent or reduce an occurrence of the multiple feeding of the sheets with high reliability in a situation in which the amount of the sheets  100  stacked on the supply tray  10  is small and the multiple feeding of the sheets accordingly tends to occur. 
     In the time period from the fully loaded state to the near empty state, the contact angle β is larger than the minimum angle βmin. In this case, it is possible to prevent or reduce an occurrence of the multiple feeding of the sheets with high reliability in the time period from the fully loaded state to the near empty state. 
     The presser plate  13  includes the distal member  13   a  having the distal region  13 A and the basal member  13   b  having the basal region  13 B. The printer  1  further includes the angle adjuster (which is a mechanism including the push-up member  14 ) for adjusting the bend angle α defined by the distal member  13   a  and the basal member  13   b . In this case, the contact angle β can be maintained at an angle less than the maximum angle βmax in the time period from the fully loaded state to the near empty state, with a relatively simple configuration. 
     The angle adjuster is configured such that, in the time period from the fully loaded state till before reaching the near empty state, the bend angle α is gradually decreased by pivoting the push-up member  14  such that the downstream end  14   t  of the push-up member  14  is moved in the direction directed from the bend portion  13   c  toward the pivot shaft  13   x  while the downstream end  14   t  is interposed between the extending portion  13   ae  and the basal member  13   b . Further, the angle adjuster is configured such that, when the near empty state is established, the push-up member  14  is moved away from between the extending portion  13   ae  and the basal member  13   b , and the bend angle α is kept defined by contact of the extending portion  13   ae  and the basal member  13   b . With this configuration, it is possible to prevent or reduce an occurrence of the feeding failure in the near empty state due to an excessive decrease of the bend angle α. In the first embodiment, at the same time when the near empty state is established, the push-up member  14  is moved away or spaced apart from the extending portion  13   ae . The push-up member  14  may be spaced apart from the extending portion  13   ae  at other timing. For instance, the push-up member  14  may be spaced apart from the extending portion  13   ae  at a time point earlier than a time point when the state of the supply tray  10  reaches the near empty state. More specifically, in a time period from a first time point at which the state of the supply tray  10  is the fully loaded state to a third time point at which a second amount of the sheets  100  larger than the first amount are loaded on the supply tray  10  and which is earlier than a second time point at which the state of the supply tray  10  reaches the near empty state, the downstream end  14   t  of the push-up member  14  may be held in contact with the basal member  13   b  and the extending portion  13   ae  while being kept interposed therebetween. In a time period from the third time point to the second time point, the downstream end  14   t  of the push-up member  14  may be spaced apart from the extending portion  13   ae . Also in this configuration, the posture of the distal member  13   a  is kept horizontal from the first time point to the second time point, and the bend angle α of the presser plate  13  is maintained. With this configuration, it is possible to prevent or reduce an occurrence of the feeding failure in the near empty state due to an excessive decrease of the bend angle α. 
     Second Embodiment 
     Referring next to  FIGS. 5-7 , there will be explained a printer according to a second embodiment. The printer of the second embodiment differs from the printer of the first embodiment in structures of the presser plate and the push-up member, and other structures are the same as in the first embodiment. 
     The supply tray  10  pivotably supports: a presser plate  213  for pressing the sheets  100  stored in the supply tray  10  toward the roller  11 ; and a push-up member  214  for pushing up the presser plate  213  from below so as to pivot the presser plate  213 . A pivot shaft  213   x  of the presser plate  213  and a pivot shaft  214   x  of the push-up member  214  are parallel to the rotation shaft  11   x  and are rotatably supported by the supply tray  10 . The presser plate  213  is pivotable about the pivot shaft  213   x  while its downstream end  213   t  is located downstream of the pivot shaft  213   x  in the conveyance direction. The push-up member  214  is pivotable about the pivot shaft  214   x  while its downstream end  214   t  is located downstream of the pivot shaft  214   x  in the conveyance direction. 
     The presser plate  213  includes, between the downstream end  213   t  and the pivot shaft  213   x , a bend portion  213   c  which is bendable. The presser plate  213  includes a distal member  213   a  shaped like a plate and having the downstream end  213   t  and a basal member  213   b  shaped like a plate and at which the pivot shaft  213   x  is provided. A boundary between the distal member  213   a  and the basal member  213   b  corresponds to the bend portion  213   c.    
     Front surfaces  213   a   1 ,  213   b   1  of the distal member  213   a  and the basal member  213   b  which face the roller  11  respectively constitute a distal region  213 A and a basal region  213 B. The distal region  213 A is a region ranging from the downstream end  213   t  to the bend portion  213   c . The basal region  213 B is a region ranging from the bend portion  213   c  to the pivot shaft  213   x.    
     A rotation shaft  213   ax  is provided at an upstream end of the distal member  213   a  which is located opposite to the downstream end  213   t  in the conveyance direction and at which the bend portion  213   c  is provided. The rotation shaft  213   ax  is rotatably supported by a downstream end of the basal member  213   b  which is located opposite to an upstream end of the basal member  213   b  in the conveyance direction at which the pivot shaft  213   x  is provided. That is, the distal member  213   a  and the basal member  213   b  are connected to each other through the bend portion  213   c  such that a bend angle α is changeable. In the present embodiment, the bend angle α is an angle defined by a portion of the presser plate  213  corresponding to the distal region  213 A and a portion of the presser plate  213  corresponding to the basal region  213 B, on one side of the presser plate  213  that is farther from the arm  12 . 
     The push-up member  214  is configured to pivot about the pivot shaft  214   x  by control of the controller  60  while its downstream end  214   t  is held in contact with a back surface  213   a   2  of the distal member  213   a  (which is opposite to the front surface  213   a   1 ), so as to push up the distal member  213   a . The controller  60  is configured to receive a signal from the sensor  70  and to drive the pivot shaft  214   x  in accordance with the amount of the sheets  100  stacked on the supply tray  10 , thereby controlling a posture of the push-up member  214  and accordingly a posture of the presser plate  213 . 
     The pivot shafts  213   x ,  214   x  are connected through the gears  215   g   1 - 215   g   5 . The gears  215   g   1 - 215   g   5  are in mesh with one another. The gear  215   g   1  is fixed to the pivot shaft  214   x , the gear  215   g   5  is fixed to the pivot shaft  213   x , and the gears  215   g   2 - 215   g   4  connect the gear  215   g   1  and the gear  215   g   5 . When the pivot shaft  214   x  is driven, the gears  215   g   1 - 215   g   5  are rotated, and rotation of the pivot shaft  214   x  is transmitted to the pivot shaft  213   x , so that the pivot shaft  213   x  is rotated. While the pivot shaft  214   x  is driven in the present embodiment, the pivot shaft  213   x  may be driven. In this case, when the pivot shaft  213   x  is driven, the gears  215   g   1 - 215   g   5  are rotated, and rotation of the pivot shaft  213   x  is transmitted to the pivot shaft  214   x , so that the pivot shaft  214   x  is rotated. 
     In other words, the gears  215   g   1 - 215   g   5  correspond to a transmission member configured to perform: transmission of a pivotal movement of the push-up member  214  about the pivot shaft  214   x  to a pivotal movement of the basal member  213   b  about the pivot shaft  213   x ; and transmission of the pivotal movement of the basal member  213   b  about the pivot shaft  213   x  to the pivotal movement of the push-up member  214  about the pivot shaft  214   x . The drive force is transmitted by the gears  215   g   1 - 215   g   5 , so that the basal member  213   b  and the push-up member  214  operate in conjunction with each other. 
     There will be next explained operations of the presser plate  213  and the push-up member  214  in the time period from the fully loaded state (in which the maximal amount of the sheets  100  are loaded on the supply tray  10 ) to the near empty state (in which the first amount of the sheets  100  are loaded on the supply tray  10 , namely, a single sheet is loaded on the supply tray  10  in the present embodiment). 
     As shown in  FIG. 5 , the bend angle α is equal to 180° in the fully loaded state. 
     In the time period from the fully loaded state till before reaching the near empty state, as the amount of the sheets  100  stacked on the supply tray  10  decreases, the push-up member  214  is pivoted by control of the controller  60 , as shown in  FIG. 6 . In this instance, the downstream end  214   t  of the push-up member  214  moves in a direction directed from the downstream end  213   t  toward the bend portion  213   e  along the back surface  213   a   2  of the distal member  213   a . The gears  215   g   1 - 215   g   5  transmit the drive force of the pivot shaft  214   x  to the pivot shaft  213   x , so that the basal member  213   b  is pivoted about the pivot shaft  213   x  toward the arm  12 . The gear ratio is set such that, in the time period from the fully loaded state till before reaching the near empty state, the distal member  213   a  is moved upward with its posture kept horizontal and the bend angle α gradually becomes smaller. 
     Thus, the push-up member  214  and the gears  215   g   1 - 215   g   5  function as an angle adjuster for adjusting the bend angle α defined by the distal member  213   a  and the basal member  213   b.    
     In the time period from the fully loaded state to the near empty state, the bend angle α is maintained at an obtuse angle, and the distal region  213 A is kept opposed to the roller  11 . 
     In the time period from the fully loaded state to the near empty state, a contact angle β, i.e., an angle defined, on the upstream side in the conveyance direction, by the arm  12  and the roller-contacting portion  100   a  of the sheets  100  on the presser plate  213  which is in contact with the roller  11 , is constant. That is, the contact angle β is equal to the minimum angle βmin (which is the contact angle in the fully loaded state and is equal to 0° in the present embodiment). Further, the contact angle β is kept less than a maximum angle βmax which is an angle defined, on the upstream side in the conveyance direction, by: (i) the portion of the presser plate  213  corresponding to the basal region  213 B in the fully loaded state; and (ii) the arm  12  the roller  11  of which contacts the presser plate  213  which is the presser plate  213  in the fully loaded state and on which it is assumed that the sheets  100  are not loaded in the fully loaded state, i.e., the arm  12  indicated by the long dashed double-short dashed line in  FIG. 5 . 
     An angle γ defined by the portion of the presser plate  213  corresponding to the distal region  213 A and the separation wall  10   w  is also kept constant in the time period from the fully loaded state to the near empty state. 
     As described above, the present embodiment offers the same advantages as those offered by the first embodiment according to the same configuration as employed in the first embodiment. The second embodiment further offers the following advantages. 
     The angle adjuster includes the gears  215   g   1 - 215   g   5  that permit the basal member  213   b  and the push-up member  214  to operate in conjunction with each other. With this configuration, it is not necessary to individually drive the basal member  213   b  and the push-up member  214 , resulting in a decrease in the number of drive sources. 
     Third Embodiment 
     Referring next to  FIGS. 8-10 , there will be explained a printer according to a third embodiment. The printer of the third embodiment differs from the printer of the first embodiment in structures of the presser plate, the push-up member, and the supply tray, and other structures are the same as in the first embodiment. 
     A supply tray  310  has: a protruding portion  310   p  (as one example of “limiter”) that protrudes outward from an upper end of the separation wall  310   w ; and a through-hole  310   q  formed in the separation wall  310   w.    
     The supply tray  310  pivotably supports: a presser plate  313  for pressing the sheets  100  stored in the supply tray  310  toward the roller  11 ; and a push-up member  314  for pushing up the presser plate  313  from below so as to pivot the presser plate  313 . A pivot shaft  313   x  of the presser plate  313  and a pivot shaft  314   x  of the push-up member  314  are parallel to the rotation shaft  11   x  and are rotatably supported by the supply tray  310 . The presser plate  313  is pivotable about the pivot shaft  313   x  while its downstream end  313   t  is located downstream of the pivot shaft  313   x  in the conveyance direction. The push-up member  314  is pivotable about the pivot shaft  314   x  while its downstream end  314   t  is located downstream of the pivot shaft  314   x  in the conveyance direction. 
     The presser plate  313  includes, between the downstream and  313   t  and the pivot shaft  313   x , a bend portion  313   c  which is bendable. The presser plate  313  includes a distal member  313   a  shaped like a plate and having the downstream end  313   t  and a basal member  313   b  shaped like a plate and at which the pivot shaft  313   x  is provided. A boundary between the distal member  313   a  and the basal member  313   b  corresponds to the bend portion  313   c.    
     Front surfaces  313   a   1 ,  313   b   1  of the distal member  313   a  and the basal member  313   b  which face the roller  11  respectively constitute a distal region  313 A and a basal region  313 B. The distal region  313 A is a region ranging from the downstream end  313   t  to the bend portion  313   c . The basal region  313 B is a region ranging from the bend portion  313   c  to the pivot shaft  313   x.    
     A rotation shaft  313   ax  is provided at an upstream end of the distal member  313   a  which is located opposite to the downstream and  313   t  in the conveyance direction and at which the bend portion  313   c  is provided. The rotation shaft  313   ax  is rotatably supported by a downstream end of a basal member  313   b  which is located opposite to an upstream end of the basal member  313   b  in the conveyance direction at which the pivot shaft  313   x  is provided. That is, the distal member  313   a  and the basal member  313   b  are connected to each other through the bend portion  313   c  such that a bend angle α is changeable. In the present embodiment, the bend angle α is an angle defined by a portion of the presser plate  313  corresponding to the distal region  313 A and a portion of the presser plate  313  corresponding to the basal region  313 B, on one side of the presser plate  313  that is farther from the arm  12 . 
     The rotation shaft  313   ax  is provided with a spring  313   s  (as one example of “biasing member”). The spring  313   s  biases the distal member  313   a  and the basal member  313   b  in a direction to increase the bend angle α. A stopper (not shown) is disposed at the bend portion  313   c  of the presser plate  313  for preventing the bend angle α from becoming larger than 180°. 
     The push-up member  314  is configured to pivot about the pivot shaft  314   x  by control of the controller  60  while its downstream end  314   t  is held in contact with a back surface  313   b   2  of the basal member  313   b  (which is opposite to the front surface  313   b   1  thereof), so as to cause the basal member  313   b  to be pivoted about the pivot shaft  313   x . The controller  60  is configured to receive a signal from the sensor  70  and to drive the pivot shaft  314   x  in accordance with the amount of the sheets  100  stacked on the supply tray  310 , thereby controlling a postured of the push-up member  314  and accordingly a posture of the presser plate  313 . 
     There will be next explained operations of the presser plate  313  and the push-up member  314  in the time period from the fully loaded state (in which the maximal amount of the sheets  100  are loaded on the supply tray  310 ) to the near empty state (in which the first amount of the sheets  100  are loaded on the supply tray  310 , namely, a single sheet is loaded on the supply tray  10  in the present embodiment). 
     As shown in  FIG. 8 , the bend angle α is equal to 180° in the fully loaded state. In this instance, the distal member  313   a  is supported by a lower surface that defines the through-hole  310   q  formed in the separation wall  310   w.    
     In the time period from the fully loaded state till before reaching the near empty state, as the amount of the sheets  100  stacked on the supply tray  310  decreases, the push-up member  314  is pivoted by control of the controller  60 , as shown in  FIG. 9 . In this instance, the downstream end  314   t  of the push-up member  314  moves in a direction directed from the bend portion  313   c  toward the pivot shaft  313   x  along the back surface  313   b   2  of the basal member  313   b . The push-up member  314  pushes up the downstream end of the basal member  313   b , whereby the basal member  313   b  is pivoted about the pivot shaft  313   x  toward the arm  12 . 
     In a process in which the state of the supply tray  10  changes from the fully loaded state to the near empty state, the distal member  313   a  is moved upward with its posture kept parallel to the basal member  313   b  until the downstream end  313   t  of the presser plate  313  comes into contact with the protruding portion  310   p . The bend angle α is constant until the downstream end  313   t  of the presser plate  313  comes into contact with the protruding portion  310   p . In a time period from a time point when the downstream end  313   t  comes into contact with the protruding portion  310   p  till before reaching the near empty state, the basal member  313   b  is pushed up by the push-up member  314  in a state in which the downstream end  313   t  of the distal member  313   a  is inhibited from moving upward by the protruding portion  310   p , whereby the bend angle α is gradually decreased against the biasing force of the spring  313   s , as shown in  FIG. 10 . 
     Thus, the spring  313   s , the push-up member  314 , and the protruding portion  310   p  function as an angle adjuster for adjusting the bend angle α defined by the distal member  313   a  and the basal member  313   b.    
     In the time period from the fully loaded state to the near empty state, the bend angle α is maintained at an obtuse angle, and the distal region  313 A is kept opposed to the roller  11 . 
     In the time period from the fully loaded state to the near empty state, a contact angle β, i.e., an angle defined, on the upstream side in the conveyance direction, by the arm  12  and the roller-contacting portion  100   a  of the sheets  100  on the presser plate  313  which is in contact with the roller  11 , is kept less than a maximum angle βmax but is not constant. Here the maximum angle βmax is an angle defined, on the upstream side in the conveyance direction, by (i) the portion of the presser plate  313  corresponding to the basal region  313 B in the fully loaded state and (ii) the arm  12  the roller  11  of which contacts the presser plate  313  which is the presser plate  313  in the fully loaded state and on which it is assumed that the sheets  100  are not loaded in the fully loaded state, i.e., the arm  12  indicated by the long dashed double-short dashed line in  FIG. 8 . In the present embodiment, the contact angle β is gradually increased from the fully loaded state till the time point when the downstream end  313   t  comes into contact with the protruding portion  310   p  and becomes larger than the minimum angle βmin (which is the contact angle in the fully loaded state and is equal to 0° in the present embodiment). However, the contact angle is gradually decreased in the time period from the time point when the downstream end portion  313   t  comes into contact with the protruding portion  310   p  till before reaching the near empty state, and becomes equal to the minimum angle βmin in the near empty state. 
     In the present embodiment, an angle γ defined by the portion of the presser plate  313  corresponding to the distal region  313 A and the separation wall  10   w  is not constant, either, from the fully loaded state to the near empty state. The angle γ is gradually increased from the fully loaded state till the time point when the downstream end  313   t  comes into contact with the protruding portion  310   p , and is gradually decreased in the time period from the time point when the downstream end  313   t  comes into contact with the protruding portion  310   p  till before reaching the near empty state. The angle γ in the near empty state is equal to the angle γ in the fully loaded state. 
     As described above, the present embodiment offers the same advantages as those offered by the first embodiment according to the same configuration as employed in the first embodiment. The third embodiment further offers the following advantages. 
     The angle adjuster includes the spring  313   s  provided at the bend portion  313   c , the push-up member  314  configured to pivot the basal member  313   b  about the pivot shaft  313   x , and the protruding portion  310   p  configured to limit the movement of the downstream end  313   t  With this configuration, the bend angle α is effectively adjusted by a cooperative operation of the spring  313   s , the push-up member  314 , and the protruding portion  310   p.    
     While the embodiments of the disclosure have been described above, it is to be understood that the disclosure is not limited to the details of the illustrated embodiments, but may be embodied with other various changes and modifications, which may occur to those skilled in the art, without departing from the scope of the disclosure. 
     The presser plate does not necessarily have to support the entirety of the sheets, but may support a part of the sheets (including a portion facing the roller). In this case, other part of the sheets may be supported directly by the container. 
     The contact angle is an angle defined, on the upstream side in the conveyance direction, by a plane that includes the arm and a plane along the roller-contacting portion of the sheets on the presser plate which is in contact with the roller. The contact angle is equal to 0° when these planes are in parallel with each other as shown in  FIGS. 2-8 and 10 . The contact angle may be a positive value ( FIG. 9 ) or a negative value. 
     The distal region need not necessarily extend in the horizontal direction in the near empty state. 
     In the second embodiment, the gears  215   g   1 - 215   g   5  (the transmission member) perform both of: transmission of the pivotal movement of the push-up member  214  about the pivot shaft  214   x  to the pivotal movement of the basal member  213   b  about the pivot shaft  213   x ; and transmission of the pivotal movement of the basal, member  213   b  about the pivot shaft  213   x  to the pivotal movement of the push-up member  214  about the pivot shaft  214   x . The transmission member may perform only one of the transmissions. 
     In the second embodiment, the transmission member may be omitted, and the basal member and the push-up member may be individually driven. In this case, it is preferable to individually control driving of the basal member and driving of the push-up member such that, in the time period from the fully loaded state to the near empty state, the distal member  213   a  moves upward with its posture kept horizontal and the bend angle α is gradually decreased. 
     In place of the sensor  70  for detecting the amount of the sheets  100  loaded on the supply tray, a sensor for detecting an angle of the arm  12  may be used, for instance. In this case, the controller  60  may be configured to receive a signal from the sensor and to control the postures of the push-up member and the presser plate such that the angle of the arm  12  is kept constant, namely, the arm  12  is kept horizontal, for instance. 
     The push-up member may be omitted, and the rotation shaft of the basal member provided at the distal member and the presser-plate pivot shaft provided at the basal member may be coupled to gears. In this case, when the presser-plate pivot shaft is driven and the basal member pivots about the presser-plate pivot shaft, the drive force of the presser-plate pivot shaft is transmitted to the rotation shaft by the gears, so that the distal member pivots about the rotation shaft. 
     It is not necessarily required that the presser plate is constituted by a plurality of members connected to each other and the bend angle is adjustable. The presser plate may be constituted by a single member, and the bend angle may be kept constant. 
     In the illustrated embodiments, the arm is supported by the housing of the sheet conveying apparatus. The arm may be supported by the container. 
     The recording portion may be an ink-jet type, a thermal type, or a laser type. The sheet conveying apparatus according to the disclosure is not limited to the printer, but may be a facsimile, a copying machine, or a multi-function peripheral (MFP), for instance. The sheet conveying apparatus does not necessarily have to have the recording portion. The sheet is not limited to paper but may be a cloth, for instance.