Patent Publication Number: US-9411294-B2

Title: Bypass feeder and door on an image forming apparatus

Description:
This patent application is a continuing application of and claims priority under 35 U.S.C. §120/121 to U.S. application Ser. No. 14/151,874, filed Jan. 10, 2014, which claims priority to 35 U.S.C. §119 to Japanese Patent Application No. 2013-015655, filed on Jan. 30, 2013 in the Japan Patent Office, which are hereby incorporated by reference herein in their entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     Example embodiments relate to a bypass feeder in which a bypass tray is attached to an opening/closing unit of an apparatus body of an image forming apparatus to be movable between an open position and a closed position, and an image forming apparatus including the bypass feeder. 
     2. Related Art 
     Image forming apparatuses such as printers and copiers generally include a bypass feeder to feed sheets such as recording sheets and OHP (overhead projector) films loaded on a bypass tray to a sheet conveying path of an apparatus body. Known bypass feeders include a bypass tray attached to an opening/closing unit that opens a sheet conveying path of an apparatus body of an image forming apparatus. 
     The opening/closing unit includes a fulcrum at a lower part thereof, and therefore an upper part (a free end) of the opening/closing unit can open and close with respect to the apparatus body of the image forming apparatus. The opening/closing unit stands in an upright attitude in a unit closed state and remains in an inclined attitude in a unit open state. By changing the opening/closing unit from the unit closed state to the unit open state, a sheet or sheets jammed in the sheet conveying path can be removed easily. 
     The bypass tray includes a fulcrum at a lower part thereof, and therefore an upper part (a free end) of the bypass tray can open and close with respect to the opening/closing unit. The bypass tray stands in an upright attitude in a tray closed state and remains in an inclined attitude in a tray open state. By changing the bypass tray from the tray closed state to the tray open state, the bypass tray can load a sheet or sheets to be fed to the sheet conveying path. 
     However, in the bypass feeder of this type, when the opening/closing unit is changed to the unit open state while a sheet is or sheets are loaded on the bypass tray in the tray open state, the upper part of the bypass tray becomes lower than the lower part thereof wherein the fulcrum is disposed, and the sheet falls off the bypass tray. 
     Japanese Patent Application Publication No. JP 2008-308329-A discloses a technique to prevent sheets from falling off a bypass tray. In this technique, an apparatus body of an image forming apparatus and the bypass tray are connected by a connecting member to regulate an angle of inclination of the bypass tray. With this configuration, the angle of inclination of the bypass tray does not become too great, and therefore the sheets loaded on the bypass tray are prevented from falling off the bypass tray. 
     However, in the configuration in JP 2008-308329-A employing the technique, one end of the connecting member is connected to the apparatus body of the image forming apparatus. Therefore, various units and components are disposed in the middle of a connecting path. Consequently, a complicated link mechanism is used in the configuration. 
     SUMMARY 
     At least one example embodiment provides a bypass feeder attached to an apparatus body of an image forming apparatus and including an opening/closing unit, a bypass tray, a linkage, and a flexible member. The opening/closing unit has an upper part and a lower part in a vertical direction. The opening/closing unit rotates the upper part about a fulcrum provided at the lower part and opens and closes between a unit closed state in which the opening/closing unit is disposed at a position close to the apparatus body and a unit open state in which the opening/closing unit is disposed at a position separated from the apparatus body. The bypass tray has a sheet loading surface on which a sheet is loaded, and has an upper part and a lower part having a fulcrum in a vertical direction. The bypass tray rotates the upper part about the fulcrum and opens and closes with respect to the opening/closing unit between a tray closed state in which the bypass tray is disposed at a position close to the opening/closing unit and a tray open state in which the bypass tray is disposed at a position separated from the opening/closing unit. The linkage includes a flexible-member fixing member and openably connects the opening/closing unit to the apparatus body. The flexible member has one end fixed to the flexible-member fixing member and the other end fixed to the bypass tray. When the opening/closing unit is changed from the unit closed state to the unit open state while the bypass tray rotates in a direction away from the opening/closing unit to the tray open state in which the sheet is loadable on the sheet loading surface thereof, the flexible-member fixing member of the linkage shifts by pulling the flexible member to hold the bypass tray at a substantially horizontal line with respect to the sheet loading surface. 
     Further, at least one example embodiment provides an image forming apparatus including an image forming unit to form an image on a recording medium, and the above-described bypass feeder. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the invention and many of the advantages thereof will be obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a vertical cross-sectional view illustrating a front side of a bypass feeder and an image forming apparatus according to an embodiment; 
         FIG. 2  is a side view illustrating a state in which both an opening/closing unit and a bypass tray of the bypass feeder of the image forming apparatus of  FIG. 1  are closed; 
         FIG. 3  is a side view illustrating a state in which the opening/closing unit is closed and the bypass tray is open; 
         FIG. 4  is a side view illustrating a state in which the opening/closing unit is open and the bypass tray is closed; 
         FIG. 5  is a side view illustrating a state in which both the opening/closing unit and the bypass tray are open; 
         FIG. 6  is a perspective view illustrating a state in which the bypass tray is open; 
         FIG. 7  is a perspective view illustrating an inner configuration of the opening/closing unit with the bypass tray open; 
         FIG. 8  is a perspective view illustrating a configuration of the bypass tray; 
         FIG. 9  is an enlarged perspective view illustrating the configuration of the bypass tray of  FIG. 8 ; 
         FIG. 10  is a perspective view illustrating an inner configuration of the bypass tray; and 
         FIG. 11  is a table showing test results of a relation of angles of inclination of the bypass tray to a horizontal line and the number of falls of sheets loaded on the bypass tray. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
     It will be understood that if an element or layer is referred to as being “on”, “against”, “connected to” or “coupled to” another element or layer, then it can be directly on, against, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, if an element is referred to as being “directly on”, “directly connected to” or “directly coupled to” another element or layer, then there are no intervening elements or layers present. Like numbers referred to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper” and the like may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements describes as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, term such as “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors herein interpreted accordingly. 
     Although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers and/or sections, it should be understood that these elements, components, regions, layer and/or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. 
     The terminology used herein is for describing particular embodiments and is not intended to be limiting of exemplary embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “includes” and/or “including”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Descriptions are given, with reference to the accompanying drawings, of examples, exemplary embodiments, modification of exemplary embodiments, etc., of an image forming apparatus according to exemplary embodiments. Elements having the same functions and shapes are denoted by the same reference numerals throughout the specification and redundant descriptions are omitted. Elements that do not demand descriptions may be omitted from the drawings as a matter of convenience. Reference numerals of elements extracted from the patent publications are in parentheses so as to be distinguished from those of exemplary embodiments. 
     Example embodiments are applicable to any image forming apparatus, and is implemented in the most effective manner in an electrophotographic image forming apparatus. 
     In describing preferred embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of the present invention is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes any and all technical equivalents that have the same function, operate in a similar manner, and achieve a similar result. 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, preferred example embodiments are described. 
     A description is given of a configuration of a bypass feeder and a configuration of an image forming apparatus including the bypass feeder according to an embodiment, with reference to  FIGS. 1 through 11 . 
     To make  FIGS. 4 and 5  more visible, a sheet (or sheets) loaded on a bypass tray described below is not illustrated. 
       FIG. 1  is a side view illustrating a schematic configuration of an image forming apparatus  1  according to an example embodiment. 
       FIG. 1  is a vertical cross sectional view illustrating a schematic configuration of an image forming apparatus  1  according to an example embodiment. The image forming apparatus  1  may be a copier, a facsimile machine, a printer, a multifunction peripheral or a multifunction printer (MFP) having at least one of copying, printing, scanning, facsimile, and plotter functions, or the like. According to the present embodiment, the image forming apparatus  1  is an electrophotographic color printer that forms color and monochrome toner images on recording media by electrophotography. 
     As illustrated in  FIG. 1 , the image forming apparatus  1  includes an apparatus body  2 , an image reading device  3 , a sheet feeding device  4 , and an automatic document feeder (ADF)  5 . The image reading device  3  is disposed above the apparatus body  2 . The sheet feeding device  4  of table type is disposed below the apparatus body  2 . The ADF  5  is openably disposed above the image reading device  3 . The image forming apparatus  1  further includes a switchback unit  42  and a bypass feeder  70 . 
     The apparatus body  2  includes a drum-shaped photoconductor  10  that functions as an image carrier provided therein. Image forming units and components are disposed around the photoconductor  10 . For example, the units and components are a charger  11 , a development unit  12 , a transfer unit  13 , and a cleaning unit  14  disposed in this order along a rotation direction of the photoconductor  10 . In this case, the photoconductor  10  rotates counterclockwise as indicated by arrow A in  FIG. 1 . The transfer unit  13  includes a transfer belt  17  that is wound about rollers  15  and  16 . The transfer belt  17  is pressed against a surface of the photoconductor  10  at a transfer position B. 
     A toner supply unit  20  is disposed at a left side of the charger  11  and the cleaning unit  14  in  FIG. 1  to supply new toner to the development unit  12 . 
     The apparatus body  2  further includes a sheet conveying unit C therein to feed a sheet functioning as a recording medium such as a regular paper and an overhead projector (OHP) sheet from a sheet feeding position and convey the sheet to a sheet stacking position via the transfer position B. 
     The sheet conveying unit C includes a sheet feeding path R 1 , a bypass sheet feeding path R 2 , and a sheet conveying path R 0 . The sheet conveying path R 0  extends upwardly through a portion between the photoconductor  10  and the transfer unit  13  and turns left in  FIG. 1 , which forms a substantially L shape. 
     As described above, the sheet conveying path R 0  includes a registration roller pair  21  disposed upstream from the photoconductor  10  in a sheet conveying direction. 
     A fixing unit  22  is disposed downstream from the photoconductor  10  in the sheet conveying direction. The fixing unit  22  includes a pair of fixing rollers (fixing roller bodies)  31  and  32 . A fixing heater is disposed inside the fixing roller  31  and a pressure spring and a pressure arm are disposed around the fixing roller  32 . Due to pressure applied from the pressure spring and the pressure arm, the fixing roller  32  is pressed against the fixing roller  31 . The fixing roller  31  includes a thermistor and a thermostat. 
     Based on the temperature of the fixing roller  31  measured by the thermistor, the thermostat turns the fixing heater on or off. According to this operation, the fixing roller  31  is maintained at a given constant temperature. 
     A sheet discharging/separating claw  34 , a sheet discharging roller  35 , a first pressure roller  36 , a second pressure roller  37 , and a decurl roller  38  are disposed downstream from the fixing unit  22 . A sheet discharging stacker  39 , which corresponds to the sheet discharging position, is disposed beyond these components in the sheet conveying direction, so that a sheet with an image fixed thereto is discharged thereto. 
     A laser writing unit  47  is disposed on the left side of the development unit  12  in  FIG. 1 . The laser writing unit  47  includes a laser light source, a rotational polygon mirror  48  for scanning, a polygon motor  49 , and optical scanning system  50  including an f-θ (f-theta) lens. 
     The image reading device  3  includes a light source  53 , multiple mirrors  54 , an optical imaging lens  55 , and image sensor  56  such as charge coupled device (CCD). A contact glass  57  is provided on an upper surface of the image reading device  3 . 
     The ADF  5  has one end that is connected at one end on the upper surface of the image reading device  3  by a connector having a hinge structure. The ADF  5  is openably attached to the image reading device  3  so that the ADF  5  turns from a substantially horizontal state in which a lower surface of the ADF  5  pressed an original document down onto a top surface of the contact glass  57  to an open state in which the lower surface of the ADF  5  opens at an angle of inclination of 90 degrees at maximum, for example, with respect to the top surface of the contact glass  57 . 
     The ADF  5  includes a document loading tray at an original document loading position a document discharging tray at an original document discharging position, and a document conveying unit that includes a document conveying path through which a sheet such as an original document is conveyed from the document loading tray to the document discharging tray via a document reading position on the contact glass  57  of the image reading device  3 . The document conveying unit includes multiple sheet conveying rollers (multiple sheet conveying rotary bodies) by which the sheet such as the document is conveyed. 
     The sheet feeding device  4  includes multiple sheet separating units  61  arranged along a vertical direction. The respective sheet separating units  61  correspond to sheet feeding positions of the sheet S. Each sheet separating unit  61  includes a pickup roller  62  and a feed roller  63 , both functioning as sheet feed rollers, and a reverse roller  64  functioning as a separation roller. The sheet feeding path R 1  is defined on the right side of the sheet separating units  61  disposed in the vertical direction in  FIG. 1  to the sheet conveying path R 0  of the apparatus body  2 . The sheet feeding path R 1  includes multiple sheet conveyance rollers  66  functioning as sheet conveying rotary bodies to convey the sheet forward. 
     The apparatus body  2  further includes a switchback unit  42  on the right side thereof in  FIG. 1 . 
     The switchback unit  42  includes a sheet conveying unit D that branches from the sheet discharging/separating claw  34  of the sheet conveying path R 0 . The switchback unit  42  includes a sheet reversing path R 3  and a re-entry path R 4 . The sheet reversing path R 3  conveys the sheet S to a switchback position  44  that includes a switchback roller pair  43 . The re-entry path R 4  extends from the switchback position  44  to guide the sheet S to the registration roller pair  21  disposed in the sheet conveying path R 0 . 
     Further, the sheet conveying unit D includes the multiple sheet conveyance rollers (the multiple sheet conveyance rotary bodies)  66  functioning as sheet conveying rollers to convey the sheet forward. 
     In an example embodiment, the switchback unit  42  is attached to an opening/closing unit  71 , which will be described below. 
     The bypass feeder  70  is disposed openably closable to the right side surface of the apparatus body  2  of the image forming apparatus  1  in  FIG. 1 . The bypass feeder  70  includes a pickup roller  67 A, a feed roller  67 B, and a reverse roller  67 C, each functioning as a sheet feed roller, to feed the sheet S loaded on the bypass tray  72  to the sheet conveying path R 0  of the apparatus body  2 . 
     Next, a description is given of image forming operations of the image forming apparatus  1 . 
     To produce a copy of an image of an original document, a main switch is pressed and an original document is set on the ADF  5 . Alternatively, the ADF  5  is opened to place the original document directly on the contact glass  57  of the image reading device  3 . Closing the ADF  5  presses the original document on the image reading device  3 . 
     As the start button is pressed, the sheet conveying roller causes the original document set on the ADF  5  to pass through a document conveying path. After the original document has moved onto the contact glass  57 , the image reading device  3  is driven to read image data of the original document and discharge the original document to the document discharging tray. 
     By contrast, the image reading device  3  is driven immediately after the original document is set on the contact glass  57  directly. 
     When the image reading device  3  starts driving, the light source  53  is moved along the contact glass  57 . Light emitted from the light source  53  is reflected on a document surface placed on the contact glass  57 . The reflected light is then reflected by the multiple mirrors  54  and passes through the optical imaging lens  55 . Then, the light enters the image sensor  56  to form an image. Accordingly, the image sensor  56  reads data on the document surface of the document. 
     At the same time, a photoconductor drive motor rotates the photoconductor  10 . In the configuration of the image forming apparatus  1  illustrated in  FIG. 1 , as the photoconductor  10  rotates, the charger  11  uniformly charges the surface of the photoconductor  10 . Then, based on image data obtained by the image reading device  3 , the laser writing unit  47  emits the laser light to optically write an electrostatic latent image on the charged surface of the photoconductor  10 . Thereafter, the development unit  12  supplies toner to be attracted to the surface of the photoconductor  10  to develop the electrostatic latent image to a visible toner image. 
     At the same time the start switch is pressed, the sheet S is fed by the pickup roller  62  from a corresponding one of the sheet separating units  61  disposed in the vertical direction in the sheet feeding device  4 . The reverse roller  64  separates an uppermost sheet S from the subsequent sheets accommodated in the sheet separating unit  61 , so that multi-feeding of the subsequent sheets can be prevented. Subsequently, the feed roller  63  conveys the sheet S to the sheet feeding path R 1 , then the sheet conveyance roller  66  guides the sheet S to the sheet conveying path R 0 , and the registration roller pair  21  abuts against the sheet S to stop further conveyance of the sheet S. In synchronization with movement or rotation of the photoconductor  10  with the visible toner image formed on the surface thereof, the registration roller pair  21  is rotated to convey the sheet S to the right side of the photoconductor  10  in  FIG. 1 . 
     Alternatively, when the bypass feeder  70  is used, the bypass tray  72  of the bypass feeder  70  is changed from a tray closed state in which the bypass tray  72  is upright and disposed at a position close to the apparatus body  2  in an upright attitude to a tray open state in which the bypass tray  72  is inclined and disposed at a position separated from the apparatus body  2  in an inclined attitude, so as to load the sheet S on a sheet loading surface  72 B of the bypass tray  72 . 
     When the start switch is pressed, the pickup roller  67 A picks up one sheet, followed by the feed roller  67 B to feed the sheet S forward. When multiple sheets S are picked up and fed, the reverse roller  67 C separates an uppermost sheet S from the subsequent sheets to prevent the subsequent sheets from being fed together with the uppermost sheet S. Then, the sheet conveyance rollers  66  conveys and guides the sheet S conveyed to the bypass sheet feeding path R 2  to the sheet conveying path R 0 . Thereafter, similar to the operation in the sheet feeding device  4 , the sheet S fed from the bypass tray  72  is conveyed to the right side of the photoconductor  10  at the registration roller pair  21  in  FIG. 1  in synchronization with rotation of the photoconductor  10 . 
     Then, the transfer device  13  transfers the toner image formed on the surface of the photoconductor  10  onto the sheet S sent to the right side of the photoconductor  10  at the transfer position B to form the image on the sheet S. 
     Residual toner remaining on the surface of the photoconductor  10  after image transfer by the transfer device  13  is removed by the cleaning unit  14 . Then, an electric charge remover removes residual charge remaining on the surface of the photoconductor  10 , so that the photoconductor  10  is prepared for the subsequent image forming operations that start from the charging by the charger  11 . 
     Then, the sheet S after receiving the image from the transfer device  13  is conveyed by the transfer belt  17  and passes through the fixing roller pair  30  and  32  of the fixing unit  22  to fix the image to the sheet S by application of heat and pressure in the fixing unit  22 . The sheet S with the toner image fixed thereto is conveyed by the first pressure roller  36 , the sheet discharging roller  35 , the second pressure roller  37 , and the decurl roller  38  to be slightly curved for preventing the sheet S from being curled. Then, the sheet S is discharged to the sheet discharging stacker  39 . 
     It is to be noted that, when the image is transferred onto both sides of the sheet S, the sheet discharging/separating claw  34  is switched to guide the sheet S having an image on a front side thereof from the sheet conveying path R 0  to the sheet reversing path R 3 , and is conveyed by the multiple sheet conveyance rollers  66  to the switchback position  44 . Then, the sheet S is conveyed to the re-entry path R 4  to reverse the sides thereof, and is conveyed by the multiple sheet conveyance rollers  66 . Accordingly, similar to the transfer operation onto the front side of the sheet S, the sheet S is guided to the sheet conveying path R 0  to transfer the image formed on the surface of the transfer belt  17  onto a reverse side of the sheet S. 
     In  FIGS. 2 through 5 , the bypass feeder  70  includes the opening/closing unit  71  and the bypass tray  72 . The opening/closing unit  71  as illustrated in  FIG. 3  includes a fulcrum  71 A at a lower part thereof, and therefore an upper part (a free end) of the opening/closing unit  71  can open and close with respect to the apparatus body  2  of the image forming apparatus  1 . The bypass tray  72  as illustrated in  FIG. 4  includes a fulcrum  72 A at a lower part thereof, and therefore an upper part (a free end) of the bypass tray  72  can open and close with respect to the opening/closing unit  71 . 
     The bypass feeder  70  includes a link unit  73  and a linear member  81 . 
     The link unit  73  links the opening/closing unit  71  to be openable and closable with respect to the apparatus body  2 . The link unit  73  has a linear-member fixing member  80  that is a fixing member attached thereon. 
     The linear member  81  is a flexible member having one end fixed to the linear member fixing member  80  of the link unit  73  and an opposite end fixed to the bypass tray  72 . The flexible linear member  81  is a wire in the present embodiment. 
     To easily perform removal of a jammed sheet or jammed sheets jammed in the sheet conveying path R 0  and/or the re-entry path R 4  or maintenance of units and components inside the apparatus body  2 , the opening/closing unit  71  is moved to the tray open state to expose the sheet conveying path R 0  and the re-entry path R 4 , as illustrated in  FIG. 3 . Specifically, the bypass feeder  70  can expose the sheet conveying path R 0  and the re-entry path R 4  by changing the position of the opening/closing unit  71  from the tray closed state in the upright attitude as illustrated in  FIG. 2  to the tray open state in the inclined attitude as illustrated in  FIG. 3 . By so doing, removal of a jammed sheet and maintenance provided inside the apparatus body  2  can be performed easily. 
     Further, by changing the position of the bypass tray  72  from the tray closed state in the upright attitude as illustrated in  FIG. 2  to the tray open state in the inclined attitude as illustrated in  FIG. 4  to load the sheet S on the sheet loading surface  72 B of the bypass tray  72 , the bypass feeder  70  can feed and convey the sheet S to the sheet conveying path R 0 . 
     The link unit  73  employs a leg open linkage including two arms  74  having a first arm and a second arm. One end of the first arm of the arms  74  is openably connected to one end of the second arm of the arms  74  using the fulcrum  74 A. The other end of the first arm of the arms  74  is connected rotatably about the fulcrum  74 B with respect to the apparatus body  2 . The other end of the second arm of the arms  74  is connected rotatably about the fulcrum  74 C with respect to the opening/closing unit  71 . 
     The link unit  73  is disposed on a side surface of the opening/closing unit  71  when the opening/closing unit  71  is in the tray closed state, as illustrated in  FIG. 7 . The other end of the second arm of the arms  74  is connected rotatably about the fulcrum  74 C to the side surface of the opening/closing unit  71 . 
     By opening and closing the two arms  74 , the link unit  73  can open and close the opening/closing unit  71 . As the two arms  74  open and stretch, the opening/closing unit  71  can remain the position and angle of inclination in the tray open state as illustrated in  FIG. 3 . 
     The linear-member fixing member  80  of the link unit  73  is provided at the intermediate part of one of the arms  74 . In the present embodiment, the linear-member fixing member  80  of the link unit  73  is provided at the intermediate part of the second arm of the arms  74 , which is rotatably connected to the side surface of the opening/closing unit  71 . 
     The bypass feeder  70  has a configuration in which, when the opening/closing unit  71  is moved from a unit closed state in which the opening/closing unit  71  is in the upright attitude (as illustrated in  FIG. 4 ) to a unit open state in which the opening/closing unit  71  is in the inclined attitude (as illustrated in  FIG. 5 ), the linear-member fixing member  80  of the link unit  73  moves to a direction to stretch the linear member  81 , so that the bypass tray  72  retains an angle of inclination to the horizontal line, which is sufficient to prevent the sheet S loaded on the sheet loading surface  72 B of the bypass tray  72  from falling off the bypass tray  72 . A travel amount of the linear-member fixing member  80  can be adjusted depending on a position to fix one end of the linear member  81  to the link unit  73 . 
     As illustrated in  FIGS. 6 and 7 , the opening/closing unit  71  includes a through hole  71 B through which the linear member  81  passes. One end of the linear member  81  is fixed to the link unit  73  through the through hole  71 B. 
     In the bypass tray  72 , the other end of the linear member  81  is connected to a spring  82  that is an elastic member to pull the linear member  81 . One end of the spring  82  is fixed to the other end of the linear member  81 . The other end of the spring  82  is fixed to the bypass tray  72 . As an example of the spring  82 , an extendable coil spring is used. 
     A position fixing member  83  is disposed at the other end of the linear member  81 . A stopper  84  is provided on the bypass tray  72 . The bypass tray  72  includes a pulley  85  to change an extending direction of the linear member  81 . By contacting the position fixing member  83  to the stopper  80 , the bypass feeder  70  has a configuration in which the angle of inclination of the bypass tray  72  to the horizontal line. 
     The bypass tray  72  has a rectangular shaped surface as illustrated in  FIG. 8 . As illustrated in  FIG. 9 , the bypass tray  72  includes a through hole  86  formed on one side of two opposite lines disposed separated in a direction perpendicular to the sheet feeding direction of the sheet S loaded on the sheet loading surface  72 B. The through hole  86  extends the linear member  81  from the inside of the bypass tray  72  to the outside thereof. The linear member  81  passes through the through hole  86 . 
     As illustrated in  FIG. 10 , the spring  82 , the position fixing member  83 , the stopper  84 , and the pulley  85  are disposed along one line of the bypass tray  72 , which is similar to the through hole  86 . 
     Next, relations of the unit open state and the unit closes state of the opening/closing unit  71 , the tray open state and the tray closed state of the bypass tray  72 , the linear member  81 , the spring  82 , and the position fixing member  83  are described. 
     A detailed description is given of the states of the opening/closing unit  71  and the bypass tray  72  with reference to  FIGS. 2 through 5 . 
     In  FIG. 2 , the opening/closing unit  71  is in the upright attitude in the unit closed state with respect to the apparatus body  2  and the bypass tray  72  is in the upright attitude in the tray closed state with respect to the opening/closing unit  71 . At this time, the linear member  81  is slackened and the spring  82  is contracted. The position fixing member  83  of the linear member  81  is separated from the stopper  84  of the bypass tray  72 . 
     In  FIG. 3 , the opening/closing unit  71  is in the inclined attitude in the unit open state with respect to the apparatus body  2  and the bypass tray  72  is in the upright attitude in the tray closed state with respect to the opening/closing unit  71 . At this time, the linear-member fixing member  80  of the link unit  73  is shifted from the unit closed state to the unit open state in a direction in which the opening/closing unit  71  pulls the linear member  81 . However, the linear member  81  is sagged without being tensioned. The spring  82  remains contracted. The position fixing member  83  of the linear member  81  is separated from the stopper  84  of the bypass tray  72 . The position and angle of inclination of the opening/closing unit  71  in the unit open state with respect to the apparatus body  2  are held by opening and stretching the arms  74  of the link unit  73 . 
     In  FIG. 4 , the opening/closing unit  71  is in the upright attitude in the unit closed state with respect to the apparatus body  2  and the bypass tray  72  is in the inclined attitude in the tray open state with respect to the opening/closing unit  71 . At this time, the linear-member fixing member  80  of the link unit  73  is not moved from the unit closed state. However, the linear member  81  pulls the spring  82 . Therefore, the linear member  81  is not slackened. The position fixing member  83  of the linear member  81  is separated from the stopper  84  of the bypass tray  72 . The position and angle of inclination of the bypass tray  72  in the tray open state with respect to the opening/closing unit  71  are held by a positioning mechanism that is different from the linear member  81 . 
     In  FIG. 5 , the opening/closing unit  71  is in the inclined attitude in the unit open state with respect to the apparatus body  2  and the bypass tray  72  is in the inclined attitude in the tray open state with respect to the opening/closing unit  71 . At this time, the linear-member fixing member  80  of the link unit  73  is shifted from the unit closed state to the unit open state in the direction in which the opening/closing unit  71  pulls the linear member  81 . The position fixing member  83  of the linear member  81  contacts the stopper  84  of the bypass tray  72 . The position and angle of inclination of the bypass tray  72  to the horizontal line in the tray open state with respect to the opening/closing unit  71  is held due to contact of the position fixing member  83  with the stopper  84 . 
     Generally, the bypass tray  72  can open to a given angle of inclination with respect to the opening/closing unit  71  by the positioning mechanism different from the linear member  81 . However, in the configuration according to the present embodiment, the bypass tray  72  is supported by the link unit  73  with assistance of the linear member  81 . With this configuration, as the bypass tray  72  turns to open, the linear member  81  gradually stretches. When the bypass tray  72  reaches the angle of inclination where the position fixing member  83  of the linear member  81  contacts the stopper of the bypass tray  72 , the linear member  81  is stretched with tension, where the bypass tray  72  is stopped. Therefore, the bypass tray  72  stops at an intermediate position that is different from a tray stop position where the bypass tray  72  stops when the bypass tray  72  is in the tray open state and the opening/closing unit  71  is in the unit closed state. 
     At this time, the bypass feeder  70  holds the bypass tray  72  at the angle of inclination that can prevent the sheet S loaded on the bypass tray  72  from falling off the bypass tray  72 . Therefore, the sheet S remains on the bypass tray  72 . 
     Specifically, when the opening/closing unit  71  is changed from the unit closed state (shown in  FIG. 4 ) to the unit open state (shown in  FIG. 5 ) while the bypass tray  72  is in the tray open state (shown in  FIG. 4 ), the linear-member fixing member  80  of the link unit  73  is moved in the direction in which the linear member  81  is stretched. Consequently, the linear member  81  maintains the bypass tray  72  inclined to a substantially horizontal line in which the sheet S does not slidably fall from the bypass tray  72 . By so doing, the sheet S can be prevented from falling off the bypass tray  72 . 
     Here, a description is given of the angle of inclination of the bypass tray  72  to the horizontal line, with reference to  FIG. 11 . 
     In  FIG. 11 , a table shows results of a test on various angles of inclination of the bypass tray  72 . Positive angles of inclination in  FIG. 11  show angles to the horizontal line when the upper part (the free end) of the bypass tray  72  is located higher than the lower part thereof near the fulcrum  72 A. Negative angles of inclination in  FIG. 11  show angles to the horizontal line when the upper part (the free end) of the bypass tray  72  is located lower than the lower part thereof near the fulcrum  72 A. 
     The table shows that when the angle of inclination is minus 10 (−10) degrees to the horizontal line, the result is accepted because frictional forces are exerted between the bypass tray  72  and the sheet S and between the sheets S loaded on the sheet loading surface  72 B of the bypass tray, and therefore the sheet S does not slide to fall from the bypass tray  72  due to gravitating. 
     According to the test results shown in  FIG. 11 , the sheet S slides to fall from the bypass tray  72  when the angle of inclination of the bypass tray  72  reaches minus 12 (−12) degrees or above. This is because the bypass tray  72  is inclined by minus 12 degrees or above, a sliding force caused by gravitating becomes greater than the static friction force, and the sheet S cannot help from falling off the bypass tray  72 . Consequently, it is preferable that the bypass tray  72  is inclined by minus 10 degrees or below to prevent the sheet S loaded on the bypass tray  72  from sliding and falling from the sheet loading surface  72 B of the bypass tray  72 . 
     In the present embodiment, one end of the linear member  81  of the bypass feeder  70  is fixed in an intermediate position of the second arm of the arms  74  of the link unit  73 . With this configuration, the bypass feeder  70  does not include various units and components in the middle of a connecting path as provided in the apparatus body  2  of the image forming apparatus  1 . 
     Further, the bypass feeder  70  has a configuration in which the link unit  73  and the bypass tray  72  are connected by the linear member  81  having a simple link mechanism. With this configuration, when the opening/closing unit  71  is changed from the unit closed state (shown in  FIG. 4 ) to the unit open state (shown in  FIG. 5 ) while the bypass tray  72  is in the tray open state (shown in  FIG. 4 ), the linear-member fixing member  80  is moved in the direction in which the linear member  81  is stretched. Consequently, the linear member  81  maintains the bypass tray  72  to be inclined to a substantially horizontal line in which the sheet S does not slidably fall from the bypass tray  72 . 
     As described above, the image forming apparatus  1  according to the present embodiment can achieve the following effects. 
     The bypass feeder  70  has a configuration in which, when the opening/closing unit  71  is changed from the unit closed state to the unit open state while the bypass tray  72  is in the tray open state, the linear-member fixing member  80  of the link unit  73  is moved in the direction in which the linear member  81  is stretched. Consequently, the bypass tray  72  is maintained at the angle of inclination to the horizontal line in which the sheet S does not slidably fall from the bypass tray  72 . Accordingly, even when the opening/closing unit  71  is changed from the unit closed state to the unit open state while the bypass tray  72  is in the tray open state, the sheet S loaded on the sheet loading surface  72 B of the bypass tray  72  does not slide and fall from the bypass tray  72 . 
     Further, the bypass feeder  70  does not include various units and components in the middle of the connecting path that connects the link unit  73  and the bypass tray  72  by the linear member  81 . Accordingly, when the opening/closing unit  71  is changed from the unit closed state to the unit open state while the bypass tray  72  is in the tray open state, the bypass tray  72  is held at the angle of inclination at which the sheet S does not slide and fall form the bypass tray  72 . This maintenance mechanism can be achieved with a simpler configuration compared with a configuration in which the apparatus body  2  of the image forming apparatus  1  and the bypass tray  72  are connected by a known connecting member. 
     As a result, the bypass feeder  70  and the image forming apparatus  1  according to the present embodiment can be provided to prevent the slidably falling of the sheet S from the sheet loading surface  72 B of the bypass tray  72 . 
     Further, in the bypass feeder  70  according to the present embodiment, one end of the linear member  81  is fixedly connected to the link unit  72 . Therefore, the length of the linear member  81  can be reduced when compared with a known configuration in which one end of a link member is connected to an apparatus body of an image forming apparatus. As a result, the bypass feeder  70  and the image forming apparatus  1  incorporating the bypass feeder  70  can reduce costs. 
     Further, in the bypass feeder  70  according to the present embodiment, when the opening/closing unit  71  is changed from the unit closed state to the unit open state while the bypass tray  72  is in the tray open state, the link unit  73  employs a leg open linkage that moves in a direction to stretch the linear member  81 . With this configuration, the angle of inclination of the bypass tray  72  with respect to the opening/closing unit  71  in the unit open state is smaller than the angle of inclination of the bypass tray  72  with respect to the opening/closing unit  71  in the unit closed state. As a result, the angle of inclination of the bypass tray  72  to the horizontal line can be held at an angle of inclination of the bypass tray  72  at which the sheet S loaded on the sheet loading surface  72 B of the bypass tray  72  does not slidably fall from the bypass tray  72 . 
     In the bypass feeder  70  according to the present embodiment, the opening/closing unit  71  includes the through hole  71 B through which the linear member  81  passes. Therefore, when the bypass tray  72  is in the upright attitude with respect to the opening/closing unit  71  in the tray closed state, the linear member  81  can be stored between the opening/closing unit  71  and the bypass tray  72 . As a result, this configuration can reduce the size of the bypass feeder  70  and the image forming apparatus  1  including the bypass feeder  70 . 
     In the bypass feeder  70  according to the present embodiment, the other end of the linear member  81  is connected to the spring  82  that pulls the linear member  81 . With this configuration in which the linear member  81  is pulled by the spring  82 , the amount of sagging of the linear member  81  can be reduced. 
     In the bypass feeder  70  according to the present embodiment, the position fixing member  83  is disposed at the other end of the linear member  81  and the stopper  84  is provided on the bypass tray  72 . Further, the position fixing member  83  contacts the stopper  84 , so that the angle of inclination of the bypass tray  72  is adjusted. Specifically, a contact of the position fixing member  83  to the stopper  84  can adjust the angle of inclination of the bypass tray  72 . With this configuration, the angle of inclination of the bypass tray  72  with respect to the opening/closing unit  71  is controlled. 
     In the above-described embodiments, the other end of the linear member  81  is fixed to the bypass tray  72  via the spring  82 . However, the configuration according to example embodiments is not limited thereto. For example, the other end of the linear member  81  can be connected to the bypass tray  72  directly. This configuration can achieve the same effect as the configuration of the above-described embodiment. However, when the opening/closing unit  71  is in the unit closed state and the bypass tray  72  is in the tray open state, the linear member  81  may be slackened. 
     In the above-described embodiments, the image forming apparatus  1  corresponds to a copier. However, as previously described, the image forming apparatus  1  is not limited to the copier. For example, a printer can be the image forming apparatus  1 . 
     In the above-described embodiments, the sheet reversing path R 3  and the re-entry path R 4  are provided in the opening/closing unit  71 . However, the configuration is not limited thereto. For example, the sheet reversing path R 3  can be provided in the apparatus body  2 . 
     The above-described simple configuration of the bypass feeder described in the present embodiment can provide the effect that a simple configuration prevents sheets from falling off the bypass tray, and therefore is useful to the bypass feeder and the image forming apparatus according to the example embodiment. 
     The above-described example embodiments are illustrative and do not limit the present invention. Thus, numerous additional modifications and variations are possible in light of the above teachings. For example, elements at least one of features of different illustrative and exemplary embodiments herein may be combined with each other at least one of substituted for each other within the scope of this disclosure and appended claims. Further, features of components of the embodiments, such as the number, the position, and the shape are not limited the embodiments and thus may be preferably set. It is therefore to be understood that within the scope of the appended claims, the disclosure of the present invention may be practiced otherwise than as specifically described herein.