Patent Publication Number: US-2019193970-A1

Title: Sheet conveying apparatus, image reading apparatus and image forming apparatus

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an apparatus having a rotating member for detecting the presence or absence of a sheet. 
     Description of the Related Art 
     An image forming apparatus that performs recording on a sheet using an electro-photographic method, such as an electro-photographic copying machine, has an image reading apparatus having an image reading portion, an image forming portion that forms a toner image on an image bearing member such as a photosensitive drum, and a sheet conveying apparatus for conveying a sheet from a feeding tray or the like. 
     Such a sheet conveying apparatus has a mechanism for detecting whether sheets are stacked on the sheet stacking tray. Such sheet detection mechanism has, for example, a detection flag rotatable by its own weight provided in the sheet conveyance path. When a sheet is set on the sheet stacking tray, the sheet detection flag is pushed by the leading end of the sheet and is rotated to release light shielding of the photo interrupter to recognize the presence of the sheet. Conversely, when there are no sheets, the sheet detection flag blocks the light of the photo interrupter to recognize the sheet absence state. In this way it is possible to determine the presence or absence of a sheet. 
     Further, in the sheet conveying apparatus as described above, when a situation occurs in which a sheet is jammed during conveyance, the sheet conveying path can be exposed so that the jammed sheet can be removed. For this purpose, the sheet conveying path is configured by the apparatus main body and an opening and closing member rotatable with respect to the apparatus main body. When the sheet is jammed, the jammed sheet can be removed by exposing the conveying path by rotating the opening and closing member. 
     In the above configuration, when the opening and closing member is rotated to expose the sheet conveying path, the sheet detection flag rotates by its own weight and retracts to come into contact with the surface of the opening and closing member. However, when the opening and closing member opens excessively, the opening and closing member may collide with peripheral objects such as a wall surface of an installation place. Thus, the rotational angle is limited to a predetermined range. In such a case, even if the opening and closing member is rotated and the sheet conveying path is completely exposed, the sheet detection flag may not be retracted inside the surface of the opening and closing member and may remain projected from the surface of the opening and closing member. In such a state, if a replacement operation or the like of a member located in the vicinity of the sheet detection flag is performed, the sheet detection flag may be damaged. 
     In order to solve the above problem, the configuration is proposed by Japanese Patent Application Laid-Open No. 2010-64851, for example, in which a weight portion for generating a rotational moment about a rotational axis is provided in a sheet detection flag. When the sheet conveying path is exposed by rotating the opening and closing member, a rotational moment is generated by the weight portion so that the sheet detection flag abuts against the surface of the opening and closing member to retract the sheet detection flag inside the surface of the opening and closing member. 
     However, as disclosed in Japanese Patent Application Laid-Open No. 2010-64851, when the weight portion is provided on the sheet detection flag, it is necessary to adjust the inclination angle of the flag based on the relationship of the rotational moment occurring on the flag, and the angle formed by the sheet detection flag and the sheet stacking tray may become small. In such a case, the reactive force of the sheet detection flag due to its own weight becomes large, and the sheet may easily buckle when the thin sheet is set. 
     Another method for preventing the sheet detection flag from protruding from the surface of the opening and closing member at the time of an operation of maintenance may be considered, in which when the opening and closing member is closed, the sheet detection flag is provided such that the center of rotation of the detection flag is located at an upper position of the opening and closing member. In this manner, when the opening and closing member is rotated to expose the conveying path, the sheet detecting flag is easily hidden by the opening and closing member. 
     However, when the center of rotation of the sheet detection flag is located at an upper position of the opening and closing member, the distance between the sheet detection flag and the sheet stacking tray becomes large so that it is necessary to lengthen the sheet detection flag. Especially, if the feeding tray has a lift-up configuration, it becomes necessary to further lengthen the sheet detection flag. When the rotating radius of the sheet detection flag becomes large, it is necessary to provide a cutout in the guide member such as the opening and closing member in order to avoid the trajectory of the rotation of the flag, which causes a decrease in strength. 
     SUMMARY OF THE INVENTION 
     According to the present invention, 
     an apparatus comprising: 
     an opening and closing member configured to be rotatable and configured to be located at a closed position and an open position; 
     a rotating member rotatablely provided on the opening and closing member and configured to be rotatable by a sheet; and 
     an assist member provided on the opening and closing member, the assist member being configured to be located at a first position when the opening and closing member is located at the closed position and configured to be located at a second position when the opening and closing member is located at the open position, wherein the assist member is configured to be displaceable from the first position to the second position by a weight of the assist member with a rotation of the opening and closing member from the close position toward the open position, 
     wherein the assist member is configured to urge the rotating member toward a side of the opening and closing member when the assist member is located at the second position. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view schematically showing an overall configuration of an image reading apparatus with a sheet conveying apparatus. 
         FIG. 2  is a view schematically showing a configuration of a document tray and a conveying unit of the sheet conveying apparatus. 
         FIG. 3  is a plan view of a feeding portion and a separating portion of the sheet conveying apparatus. 
         FIG. 4  is a perspective view of a vicinity of a document setting detection sensor of the sheet conveying apparatus. 
         FIG. 5  is a cross-sectional view of an assist member in the vicinity of the document setting detection sensor of the sheet conveying apparatus. 
         FIG. 6  is a perspective view of an abutting portion of a flag member and an assist abutting portion of an assist member when the opening and closing guide of the sheet conveying apparatus is closed. 
         FIGS. 7A, 7B and 7C  are views showing movements until a document is set and fed to a document tray of the sheet conveying apparatus. 
         FIG. 8  is a view schematically showing a state in which the opening and closing guide of the sheet conveying apparatus is opened. 
         FIG. 9A  is a view schematically showing the positions of a flag member and an assist member in a state in which the opening and closing guide of the sheet conveying apparatus is closed, and  FIG. 9B  a view schematically showing the positions of a flag member and an assist member in a state in which the opening and closing guide of the sheet conveying apparatus is opened. 
         FIG. 10  is a perspective view showing a positional relationship between a conveying unit and a flag member in a state in which the opening and closing guide of the sheet conveying apparatus is opened. 
         FIG. 11A  is a view schematically showing the positions of a flag member and an assist member in a state in which the opening and closing guide of the sheet conveying apparatus is closed in the second embodiment, and  FIG. 11B  is a view schematically showing the positions of a flag member and an assist member in a state in which the opening and closing guide of the sheet conveying apparatus is opened in the second embodiment. 
         FIG. 12A  is a view schematically showing the positions of a flag member and an assist member in a state in which the opening and closing guide of the sheet conveying apparatus is closed in the third embodiment, and  FIG. 12B  is a view schematically showing the positions of a flag member and an assist member in a state in which the opening and closing guide of the sheet conveying apparatus is opened in the third embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     First Embodiment 
     In the first embodiment, an image reading apparatus including a sheet conveying apparatus that conveys a document, which is a sheet, will be described by way of an example. 
     &lt;Image Reading Apparatus&gt;  FIG. 1  schematically shows the overall configuration of the image reading apparatus. This image reading apparatus has the image reading portion  200  and the sheet conveying apparatus  80 . 
     The sheet conveying apparatus  80  feeds the documents S one by one onto the platen  18  made of transparent glass. Further, the sheet conveying apparatus  80  is configured to be openable and closable with respect to the image reading portion  200 , and operates to press a document placed on the platen  18 . 
     The image reading portion  200  optically reads an image of a document conveyed by the sheet conveying apparatus  80  or an image of a document placed on the platen  18 , photo-electrically converts the image, and inputs the image as image information. The image reading unit  200  has the contact image sensor  24  as a first reading portion that reads an image of one side of a moving document conveyed on the platen  18 . The contact image sensor  24  is fixed at a predetermined position (the position shown in  FIG. 1 ) on the sheet conveying apparatus  80 , and reads an image of one side of a document conveyed on the platen  18 . 
     Further, the image reading apparatus has a second reading portion that reads an image of the other side of the document. The second reading portion includes the movable scanner unit  204  with the lamp  202 , the mirror  203 , etc., the mirrors  205  and  206 , the lens  207 , the image sensor  208 , and the like. The second reading portion is provided on the image reading portion  200 . The second reading portion stops the scanner unit  204  at a predetermined position (solid line position shown in  FIG. 1 ), and reads an image of the other side of the document conveyed on the platen  18  above the scanner unit  204 . Further, while moving the scanner unit  204  along the platen  18 , the second reading portion reads an image of the other side of the document placed on the platen  18 . 
     &lt;Sheet Conveying Apparatus&gt; The sheet conveying apparatus  80  has the document tray  11  at an upper position. The document tray  11  serves as a sheet supporting portion on which documents S are placed, and the documents S placed on the document tray  11  are sequentially fed from the uppermost document by the feeding roller  1 . The fed documents S are separated and fed one by one by the conveying roller  3  and the separation roller  4 . When separately fed document S passes over the platen  18  of image reading portion  200 , an image of document S is read by either or both of the scanner unit  204  and the contact image sensor  24 . The document S from which the image has been read is discharged onto the discharge tray  19  by the discharge roller  16 . 
       FIG. 2  schematically shows the configuration of the document tray  11  and the conveying unit. On the document tray  11 , the document width regulating plate  10  for regulating the movement of the stacked document S in the width direction of the document S is provided. Further, the document tray  11  is configured to be able to be lifted up and down by a driving portion (not shown). The feeding roller  1  is rotatable around the shaft  13 . Further, the roller  1  is also rotatable about the shaft  5  by the arm  2  so as to be capable of being lifted up and down with respect to the document S stacked on the document tray  11 . 
     The opening and closing guide  6 , which is an opening and closing member, is provided with the flag member  100  serving as an actuator of the document setting detection sensor  102  for detecting the presence or absence of a document on the document tray  11 . The document setting detection sensor  102  uses a photo interrupter and detects that a sheet has been set on the document tray  11  when the optical axis is blocked by the flag member  100  (hereinafter referred to as sensor ON). Conversely, when the optical axis is not blocked by the flag member  100  (hereinafter referred to as sensor OFF), it is detected that a document is not set on the document tray  11 . 
     The arm  2  is provided with the actuator  90  of the feeding position detection sensor  91  which determines a lifted position (document feeding position) of the document tray  11 . The feed position detection sensor  91  uses a photo interrupter, and when the sensor is ON, the sheet feeding is possible. Conversely, when the sensor is OFF, it is necessary to lift up the document tray  11  by a driving portion (not shown). 
       FIG. 3  is a plan view of the feeding portion and the separating portion. The pulleys  8  and  9  are provided on the feeding roller  1  and the conveying roller  3 , respectively. The timing belt  7  is stretched on the pulleys  8  and  9  and transmits the driving force of the motor M (see  FIG. 2 ) to the feeding roller  1 . The arm  2  is urged by the spring clutch  12 . When the motor M rotates forward, the arm  2  descends and contacts the top surface of the documents on the document tray  11 . Further, when the motor M rotates forward, the feeding roller  1  and the conveying roller  3  rotate in the direction for feeding the documents and feed the documents. When the motor M rotates in the reverse direction, the spring clutch  12  is locked to lift up the arm  2 . 
     (Document Setting Detection Mechanism) Next, a document setting detection mechanism provided in the sheet conveying apparatus will be described.  FIG. 4  is a perspective view of the vicinity of the document setting detection sensor. 
     The document setting detection sensor  102  is held by the opening and closing guide  6 . The flag member  100  has two flag shaft portions  101  held by the opening and closing guide  6 . The flag shaft portions  101  are held by the bearing portion  103  of the opening and closing guide  6  such that one of the flag shaft portions  101  can freely rotate and the other of the flag shaft portions  101  can freely rotate and move upward. The flag member  100  has the actuator portion  104 . When the document S is set, the actuator portion  104  is pressed by the leading end of the document S so that the flag member  100  rotates about the flag shaft portions  101 . 
     The flag member  100  has the detection portion  105  which detects that the document S has been set by the detection portion  105  blocking the light of the document set detection sensor  102  when the detection portion  105  rotates about the flag shaft portions  101 . In addition, the flag member  100  has the protruding portion  107 . The position of the center of gravity of the flag member  100  is determined such that a rotational moment is generated around the flag shaft portion  101  in the clockwise direction (direction of arrow A) in  FIG. 4  when the opening and closing guide  6  is closed. As a result, the protruding portion  107  contacts the flag stopper portion  108  provided on the opening and closing guide  6 , whereby the posture of the flag member  100  in the rotational direction is determined. 
     The flag member  100  has the cylindrical flag abutting portion  109 . As will be described later, the flag abutting portion  109  is pressed by the assist member  110 . Further, the center of gravity position of the flag member  100  is located at a position slightly away (about 0.2 mm) from the flag shaft portions  101  (the center of rotation of the flag member  100 ) in the horizontal direction. Therefore, the moment generated at the flag member  100  is extremely small. 
     The assist member  110  is rotatably attached to the opening and closing guide  6  and the assist member  110  is displaceable between a first position and a second position in accordance with opening and closing operations of the opening and closing guide  6 . The assist member  110  has two assist shaft portions  111  held by the opening and closing guide  6 . The assist shaft portions  111  are rotatably held by the bearing portions  112  of the opening and closing guide  6 . The assist member  110  has the cylindrical assist abutting portion  113 . As will be described later, the assist abutting portion  113  has a function of pressing the flag abutting portion  109  when the opening and closing guide  6  is opened. 
     Two weights  114  are attached to the assist member  110 . The weights  114  in the present embodiment are made of SUM material having a diameter of 6 mm and a length of 12 mm. The two weights  114  are disposed on both sides of the assist shaft portions  111  such that the direction of the rotational moment of the assist member  110  by one of the weights  114  is opposite to that by the other of the weights  114 . 
       FIG. 5  is a cross-sectional view of the assist member  110  in the vicinity of the document setting detection sensor  102 . The position of the center of gravity of the assist member  110  is so determined that a moment is generated in the counterclockwise direction (direction of arrow B) with respect to the assist shaft portion  111  as shown in  FIG. 5  when the open and close guide  6  is closed. The assist abutting portion  115  provided on the assist member  110  abuts against the stopper portion  116  provided on the opening and closing guide  6 , whereby the posture of the assist member  110  in the rotational direction is determined. At this time, the assist member  110  is located at the first position, and the position of the center of gravity is located at a position slightly away (about 0.2 mm) from the center of rotation of the assist shaft portions  111  in the horizontal direction. As a result, the moment generated to the assist shaft portions  111  is extremely small. 
       FIG. 6  is a perspective view of the flag abutting portion  109  of the flag member  100  and the assist abutting portion  113  of the assist member  110  when the opening and closing guide  6  is closed. 
     The flag abutting portion  109  is provided at a position distant from the rotational center axis of the flag shaft portions  101 . The flag abutting portion  109  has a cylindrical shape with a diameter of 3 mm, and is provided in parallel with the flag shaft portions  101 . The assist abutting portion  113  is provided at a position away from the center axis of the assist shaft portions  111 . The assist abutting portion  113  has a cylindrical shape with a diameter of 8 mm, and is provided in parallel with the assist shaft portions  111 . 
     When the opening and closing guide  6  is closed, the flag abutting portion  109  and the assist abutting portion  113  are separated from each other while keeping a constant clearance without coming into contact with each other. In this state, the assist member  110  does not act on the flag member  100 . As the opening and closing guide  6  is opened, the relative positional relationship between the flag shaft portions  101  and the assist shaft portions  111  is changed as described later. As a result, the flag abutting portion  109  and the assist abutting portion  113  abut against each other. 
       FIGS. 7A, 7B and 7C  are schematic views showing movements until a document is set and fed to the document tray  11 . 
     Before the document S is set, the flag member  100  is held with an inclination of about 83° with respect to the stacking surface of the document tray  11  ( FIG. 7A ). When the document S is set by a user, the flag member  100  starts to rotate in the clockwise direction about the flag shaft portions  101  by the actuator portion  104  being pressed by the document S. 
     When the flag member  100  rotates by about 25°, the document S goes under the flag member  100  ( FIG. 7B ). At this time, the detection portion  105  blocks the light of the document setting detection sensor  102 , thereby detecting that the document S has been set. By making the angle of the flag member  100  with respect to the setting direction of the document S as close to 90° as possible, it is easy to detect even a document with low stiffness such as a thin paper without buckling. 
     When the document S is detected, the document tray  11  is lifted up by a document tray lifting motor (not shown) and is moved to a predetermined position ( FIG. 7C ). Thereafter, the feeding operation is performed by the feeding roller  1 . After a predetermined number of sheets are fed, the document tray  11  is lifted down by the document tray lifting motor (not shown) and is moved to the initial position. The flag member  100  also returns to the initial position and the operations are completed. During this series of operations, the flag member  100  and the assist member  110  are not brought into contact with each other. The reason is that when the sheet is detected, since the flag member  100  rotates in the clockwise direction in  FIG. 7 , the flag abutting portion  109  rotates in a direction to retract from the assist abutting portion  113 . 
     Further, in the present embodiment, as shown in  FIG. 7 , the flag shaft portions  101 , which are the center of rotation of the flag member  100 , are positioned at lower positions of the opening and closing guide  6  in the vertical direction in a state where the opening and closing guide  6  is located at the closed position. With this configuration, even if the angle of the flag member  100  with respect to the setting direction of the document is made as close as possible to 90°, it is not necessary to lengthen the flag member  100 . 
     (Operations of Flag Member When Opening and Closing Guide is Opened) Next, the operations of the flag member  100  when the opening and closing guide  6  is opened will be described. For example, when a paper jam occurs in the reading apparatus, or when replacing parts during maintenance, the work is done with the opening and closing guide  6  being opened upward.  FIG. 8  is a schematic diagram showing a state in which the opening and closing guide  6  is opened. The opening and closing guide  6  is held so as to be rotatable around the rotational shaft  117  with respect to the reading apparatus main body. When a user rotates the opening and closing guide  6  to open it, the document conveying path is exposed. At this time, the opening angle should be large enough because a certain amount of space is required from the viewpoint of workability, but if the opening angle is too large, the opening and closing guide  6  may collide with peripheral objects such as a wall surface of an installation place. Therefore, the opening angle of the opening and closing guide  6  is set to an angle at which the work is possible and the collision with surrounding objects is avoided. Then, the opening and closing guide  6  is held in a self-standing state for work to be easily done when the opening and closing guide  6  is opened. 
     With the opening operations of the opening and closing guide  6 , the assist member  110  acts on the flag member  100 . When the opening and closing guide  6  is located at the open position, the assist member  110  presses the flag member  100  so that the flag member  100  is urged toward the opening and closing guide  6 . Next, the action of the assist member  110  on the flag member  100  when the opening and closing guide  6  is opened and closed will be described in detail. 
       FIGS. 9A and 9B  are schematic views showing the positions of the flag member  100  and the assist member  110  when the opening and closing guide  6  is closed and opened.  FIG. 9A  shows a state in which the opening and closing guide  6  is located at a closed position, and  FIG. 9B  shows a state in which the opening and closing guide  6  is located at an open position. 
     In a state where the opening and closing guide  6  is closed, as described above, the flag member  100  and the assist member  110  are held in a state in which a slight moment is generated in the counterclockwise direction (direction of arrow C) due to their own weights without contacting each other. 
     As the opening and closing guide  6  is opened, the position of the assist shaft portion  111  with respect to the flag shaft portion  101  relatively moves in the counterclockwise direction, and the position of the assist shaft portion  111  in the vertical direction becomes almost the same as the position of the flag shaft portion  101 . On the other hand, the flag member  100  and the assist member  110  try to maintain the posture determined by the position of the center of gravity. Therefore, the assist member rotates in the clockwise direction because of the gravity, and the assist abutting portion  113  abuts against the flag abutting portion  109  to generate a force in the direction perpendicular to each tangent (direction of arrow D). As a result, a moment is generated at the flag member  100  in the clockwise direction (the direction of the arrow E) with respect to the flag shaft portion  101  and the flag member  100  rotates against the moment in the counterclockwise direction (the direction of the arrow F) due to its own weight. 
     The flag member  100  continues to rotate until the assist member  110  abuts against the assist stopper portion  118  provided on the top surface of the opening and closing guide  6 . At this time, the assist member  110  is located at the second position, and as shown in  FIG. 9B , the flag member  100  is completely retracted inside the guide surface of the opening and closing guide  6 . Even if the opening and closing guide  6  is opened further, since the rotation of the assist abutting portion  113  is restricted by the assist stopper portion  118 , the flag abutting portion  109  is never pushed further. When the opening and closing guide  6  is completely opened and the opening and closing guide  6  becomes in the self-standing state, the operation of opening is completed. When closing the opening and closing guide  6 , the opening and closing guide  6  returns to the initial state by the reverse procedure. 
     Since both the flag abutting portion  109  of the flag member  100  and the assist abutting portion  113  are formed in a circular arc configuration, the contact points are gradually moved while rotating as the opening and closing guide  6  is opened. 
     As described above, when the opening and closing guide  6  is opened, the flag member  100  is pressed and moved by the assist member  110  so that the flag member  100  is completely retracted inside the guide surface of the opening and closing guide  6 . Therefore, it is possible to reduce the risk that the worker damages parts by contacting the flag member  100  with hands or other parts during jam recovering or maintenance operations. 
     As a specific example, the effect of replacing the conveying unit  121  for conveying a sheet will be described.  FIG. 10  is a perspective view showing the positional relationship between the conveying unit  121  and the flag member  100  when the opening and closing guide  6  is opened. 
     When the opening and closing guide  6  is opened, the flag member  100  retracts inside the surface of the opening and closing guide  6  as described above. In the embodiment of  FIG. 10 , an accommodating portion for accommodating the flag member  100  is formed in the opening and closing guide  6  with the groove portion  119  and the protection rib  120 . When the opening and closing guide  6  is opened, the flag member  100  is pressed by the assist member  110 , so that the flag member  100  is retracted into the groove portion  119  provided in the opening and closing guide  6 , and the flag member  100  is protected by the protection rib  120  which surrounds the flag member  100 . 
     The conveying unit  121  has conveying members such as the feeding roller  1 , the arm  2  and the conveying roller  3 . The conveying unit  121  requires maintenance when it is used for a long time. Therefore, the conveying unit  121  is detachably attachable to the opening and closing guide  6 . At the time of maintenance, the opening and closing guide  6  is opened, the conveying unit  121  is pulled out in the direction substantially perpendicular to the plane of the drawing in the figure, and each roller is exchanged. In pulling out the conveying unit  121 , if the flag member  100  protrudes from the guide surface, the flag member  100  may collide with the conveying unit  121  so that the flag member  100  may be damaged. However, in the configuration of the above-described embodiment, since the flag member  100  is retracted inside the guide surface of the opening and closing guide  6 , the risk thereof can be reduced. Therefore, in the present embodiment, the flag member  100  is disposed in the vicinity of the conveying unit  121  so as to reduce the size of the apparatus. 
     The flag member  100  is retracted inside the guide surface of the opening and closing guide  6  by the assist member  110 , and the flag shaft portion  101 , which is the center of rotation of the flag member  100 , is arranged to a lower position in the vertical direction when the opening and closing guide  6  is closed, so that the length of the flag member  100  can be reduced. 
     In the present embodiment, the conveying unit  121  is taken as an example, but the above configuration is also effective when other replacement parts such as other conveying rollers and sensors are present in the vicinity of the flag member  100 . The above configuration is also effective not only at the time of maintenance but also when there is an operation to open the opening and closing guide  6  such as jam recovering. 
     In this embodiment, the flag member  100  is completely retracted inside the guide surface of the opening and closing guide  6 , but a certain effect can be obtained even when the flag member  100  is not completely retracted. 
     Further, in the present embodiment, an example in which the document tray  11  has the lift-up configuration is described, but a similar effect can be obtained with a fixed tray which does not have the lift-up configuration. 
     Further, in the present embodiment, the assist member  110  has the weight  114 . However, a certain effect can be obtained even when the weight is not provided. 
     Further, in the present embodiment, the sheet conveying apparatus having the flag member  100  and the assist member  110  is used for the image reading apparatus. However, the sheet conveying apparatus can be used for an image forming apparatus having an image forming portion for forming an image on a sheet. 
     Second Embodiment 
     In the embodiment described above, when the opening and closing guide  6  is opened, the assist member  110  presses the flag member  100  while the assist member  110  and the flag member  100  are rotating in the same direction. However, the flag member  100  can be retracted while the assist member  110  and the flag member  100  are rotating in the opposite directions with each other as described next. 
       FIGS. 11A and 11B  are schematic views showing the positions of the flag member  100  and the assist member  110  when the opening and closing guide  6  is located at the closed position and at the open position in the second embodiment.  FIG. 11A  shows a state in which the opening and closing guide  6  is closed, and  FIG. 11B  shows a state in which the opening and closing guide  6  is opened. 
     When the opening and closing guide  6  is closed, the flag member  100  is held by a stopper portion (not shown) in a state in which a slight moment is generated in the counterclockwise direction (direction of arrow C) by its own weight. On the other hand, the assist member  110  is held by the second stopper portion  122  in a state in which a moment is generated in the clockwise direction (direction of arrow G) by its own weight. The flag member  100  and the assist member  110  are held without contacting each other. 
     As the opening and closing guide  6  is opened, the relative position of the assist shaft portion  111  in the vertical direction with respect to the position of the center of gravity of the assist member  110  changes. When the opening and closing guide  6  is opened to a predetermined angle, the rotational moment due to the position of the center of gravity of the assist member  110  is switched from the clockwise direction (the direction of the arrow G) to the counterclockwise direction (the direction of the arrow H). 
     Therefore, the assist abutting portion  113  abuts against the flag abutting portion  109 , so that a force is generated in the direction perpendicular to each tangent (direction of arrow I). As a result, a moment is generated at the flag member  100  in the clockwise direction (the direction of the arrow E) with respect to the flag shaft portion  101  so that the flag member rotates against the moment in the counterclockwise direction (the direction of the arrow F) due to its own weight. The flag member  100  rotates until the assist member  110  abuts against the assist stopper portion  118 . At this time, the flag member  100  is completely retracted inside the guide surface of the opening and closing guide  6 . 
     As described above, similarly to the first embodiment, when the opening and closing guide  6  is opened, the flag member  100  is completely retracted inside the guide surface of the opening and closing guide  6  by being pressed and moved by the assist member  110 . With this configuration, it is possible to reduce the risk that the flag member  100  is damaged due to a worker contacting the flag member  100  with a hand or a part during jam recovery or maintenance operations. 
     Third Embodiment 
     In the embodiment described above, the direction of the rotational moment due to the weight of the assist member  110  is switched while the opening and closing guide  6  is moving from the closed position to the open position. However, when the opening and closing guide  6  is opened, the direction of the rotational moment due to the weight of the assist member  110  may continue to be the same. 
       FIGS. 12A and 12B  are views for explaining the operations of the flag member  100  and the assist member  110  provided in the opening and closing guide  6  in the third embodiment.  FIG. 12A  shows a state in which the opening and closing guide  6  is located at a closed position, and  FIG. 12B  shows a state in which the opening and closing guide  6  is located at an open position. 
     As shown in  FIGS. 12A and 12B , the flag member  100  is configured to be rotatable around the flag shaft portion  101 , and the assist member  110  is configured to be rotatable around the assist shaft portion  111 . When the opening and closing guide  6  is located at the closed position, the assist abutting portion  113  of the assist member  110 , which is suspended by its own weight is located at a position where the assist abutting portion  113  does not act on the flag abutting portion  109  of the flag member  100 . 
     When the opening and closing guide  6  moves from the closed position of  FIG. 12A  to the open position of  FIG. 12B , both the assist member  110  and the flag member  100  rotate in the clockwise direction, and the assist abutting portion  113  presses the flag abutting portion  109  so that the flag member  100  is retracted inside the guide surface of the opening and closing guide  6 . With this configuration, it is possible to obtain the same effect as the above-described embodiment. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2017-247537, filed Dec. 25, 2017, which is hereby incorporated by reference herein in its entirety.