Abstract:
A sheet conveying device with a sheet conveyance path through which a sheet is conveyed include: a sheet guide that has a first end rotatably supported to move a second end to be close to or away from the sheet conveyance path; and a sheet detecting section that has a first end protruding beyond the sheet guide and a second end rotatably supported so that the first end is pushed by the sheet and rotated. A rotation shaft of the sheet detecting section is disposed farther from the sheet conveyance path than a rotation shaft of the sheet guide, and the sheet guide is provided with a moving portion for moving the first end of the sheet detecting section to an inside of a guide face of the sheet guide.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2010-067915 filed on Mar. 24, 2010. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to a sheet conveying device and an image forming apparatus including the sheet conveying device. 
         [0004]    2. Related Art 
         [0005]    In an image forming apparatus, paper detecting means is provided everywhere in a paper conveyance path, so as to check presence of paper before performing a prescribed process on the paper. In employing paper detecting means for mechanically detecting paper by allowing paper to come into contact with a sensor such as a lever, it is necessary to be careful not to damage the sensor with paper in removing jammed paper from the paper conveyance path. 
       SUMMARY 
       [0006]    According to an aspect of the invention, a sheet conveying device with a sheet conveyance path through which a sheet is conveyed include: a sheet guide that has a first end rotatably supported to move a second end to be close to or away from the sheet conveyance path; and a sheet detecting section that has a first end protruding beyond the sheet guide and a second end rotatably supported so that the first end is pushed by the sheet and rotated, wherein a rotation shaft of the sheet detecting section is disposed farther from the sheet conveyance path than a rotation shaft of the sheet guide, and the sheet guide is provided with a moving portion for moving the first end of the sheet detecting section to an inside of a guide face of the sheet guide when the first end of the sheet guide is rotated in a direction away from the sheet conveyance path. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Exemplary embodiments of the invention will be described in detail based on the following figures, wherein: 
           [0008]      FIG. 1  is a side cross-sectional view of a printer according to an exemplary embodiment; 
           [0009]      FIG. 2  is a perspective view of the printer of the exemplary embodiment with a front cover opened. 
           [0010]      FIG. 3  is a side view illustrating a supporting mechanism of a detection lever of the exemplary embodiment taken from a direction of an arrow III of  FIG. 2 ; 
           [0011]      FIG. 4  is a side cross-sectional view of a sheet conveying device according to the exemplary embodiment; 
           [0012]      FIG. 5  is a side cross-sectional view of the sheet conveying device shifted from a state illustrated in  FIG. 4  to a state where paper comes into contact with the detection lever; 
           [0013]      FIG. 6  is a side cross-sectional view of the sheet conveying device shifted from the state illustrated in  FIG. 4  to a state where a sheet guide is rotated; 
           [0014]      FIG. 7  is a side cross-sectional view of the sheet conveying device shifted from the state illustrated in  FIG. 6  to a state where the sheet guide is further rotated; and 
           [0015]      FIG. 8  is a side cross-sectional view of the sheet conveying device shifted from the state illustrated in  FIG. 7  to a state where the sheet guide is further rotated. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    Now, a preferred exemplary embodiment of the invention will be described with reference to the accompanying drawings. 
       (1) Basic Structure and Operation of Printer 
       [0017]    First, the basic structure and the operation of a printer (i.e., an image forming apparatus) according to an exemplary embodiment will be described. 
         [0018]      FIG. 1  illustrates the internal structure of a printer  1  according to the exemplary embodiment. In this drawing, a reference numeral  10  denotes an apparatus main body including a housing  11 . The front face of the apparatus main body  10  is opened/closed by a front cover  70  described later. In the following description, a forward/backward or upper/lower direction corresponds to a direction within the apparatus main body  10  with an R direction of  FIG. 1  regarded as the backward direction and an F direction regarded as the forward direction. 
         [0019]    On the bottom of the apparatus main body  10 , a paper tray  30  is provided. Paper (a sheet) P is drawn one by one in the forward direction by a paper drawing section  41 , is elevated through a paper conveyance path  40  formed on a front side of the apparatus main body  10  and is fed to a paper output tray  14  formed on the top face of the apparatus main body  10 . 
         [0020]    The printer  1  is a tandem full-color printer, and a transfer belt  51  rotatably suspended to be inclined upward on the rear side (namely, on the left side in  FIG. 1 ) and rotating in a direction of an arrow A, image formation units  6 Y,  6 M,  6 C and  6 K of four colors arranged in a row below the transfer belt  51 , a secondary transferring section  43 , a fixing section  44  and the like are provided in the apparatus main body  10 . The image formation units (image forming sections)  6 Y,  6 M,  6 C and  6 K are arranged in parallel to the inclined direction of the transfer belt  51 . 
         [0021]    The four image formation units  6 Y,  6 M,  6 C and  6 K are used for forming toner images respectively of yellow (Y), magenta (M), cyan (C) and black (K), and have the same basic structure including a photosensitive drum  61 , a charging roller  62  and a charging roller cleaner  63  disposed around the photosensitive drum  61 , an image exposing device  64 , a developing device  65  and a photosensitive drum cleaner  66 . 
         [0022]    Color image information is input to the printer  1  from a personal computer or the like, and when the color image information is input, four light beams respectively corresponding to the four colors are emitted from the image exposing device  64 . Each of these light beams scans the surface of the photosensitive drum  61  rotating and charged by the charging roller  62 . Thus, an electrostatic latent image of each corresponding color is formed on the surface of the photosensitive drum  61 . 
         [0023]    The electrostatic latent image formed on the photosensitive drum  61  is developed by the developing device  65  with a developer including a toner of each corresponding color, and the thus developed toner image (color image) is primarily transferred onto the surface (the outer circumferential face) of the rotating transfer belt  51  by a primary transfer roller  52 . Such a primary transferring operation of development from the photosensitive drum  61  to the transfer belt  51  is performed successively in the image formation units  6 Y,  6 M,  6 C and  6 K at prescribed timing, and in passing the image formation unit  6 K disposed on the most downstream side, a full-color toner image is formed on the surface of the transfer belt  51 . 
         [0024]    In some cases, residues such as a toner and a charge product may be adhered to the surface of the photosensitive drum  61  after the primary transfer, and the residues are removed by the photosensitive drum cleaner  66 . The surface of the photosensitive drum  61  is charged again by the charging roller  62 . It is noted that residues that cannot be sufficiently removed by the photosensitive drum cleaner  66  but are adhered to the charging roller  62  are removed by the charging roller cleaner  63  rotating in contact with the charging roller  62 . 
         [0025]    The transfer belt  51  is wound around a driving roller  53  and a backup roller  54  and is rotated in the direction of the arrow A by rotating the driving roller  53 . The primary transfer rollers  52  are provided inside the transfer belt  51  so as to form nips together with the respective photosensitive drums  61  of the image formation units  6 Y,  6 M,  6 C and  6 K with the transfer belt  51  sandwiched therebetween. 
         [0026]    The full-color toner image formed on the transfer belt  51  is transferred, in the secondary transferring section  43 , onto paper P drawn from the paper tray  30  by the paper drawing section  41  to be elevated through the paper conveyance path  40  at appropriate timing. The paper drawing section  41  includes a feeding roller  41   a  and a paper separating roller  41   b , so that the paper P is separated by the paper drawing section  41  one by one in the forward direction and is conveyed once to a resist roller pair  42  disposed above and is halted there. Then, the paper P is fed to the secondary transferring section  43  by the resist roller pair  42  rotatively driven at prescribed timing. Incidentally, a paper conveying device corresponding to the feature of this exemplary embodiment is provided below the resist roller pair  42 . The detailed structure of the paper conveying device will be described later. 
         [0027]    The secondary transferring section  43  includes the backup roller  54  suspending the transfer belt  51  and a secondary transfer roller  43   a  forming a nip with the backup roller  54 , and the paper P passes between theses rollers  54  and  43   a , so that the full-color toner image formed on the transfer belt  51  may be transferred onto the paper P. In some cases, residues such as a toner may be adhered to the surface of the transfer belt  51  after the secondary transfer, the residues are removed by a transfer belt cleaner  55  disposed above a front end of the transfer belt  51 . 
         [0028]    The paper P having the transferred full-color toner image thereon passes the fixing section  44 , and the color toner image is fixed on the paper P in this fixing section  44 . The fixing section  44  includes a heating roller  44   a  and a pressure roller  44   b  forming a nip with the heating roller  44   a , and the full-color toner image is fixed on the paper P through the functions of both pressure and heating by allowing the paper P to pass between the rollers  44   a  and  44   b . Then, the paper P having passed the fixing section  44  is fed by a paper output roller pair  45  to the paper output tray  14 . The paper conveyance path  40  includes a path extending from the paper drawing section  41  through the resist roller pair  42 , the secondary transferring section  43  and the fixing section  44  to the paper output roller pair  45 . 
       (2) Structure of Paper Conveying Device 
       [0029]    Next, the paper conveying device (sheet conveying device) of this exemplary embodiment will be described with reference to  FIGS. 2 through 8 . As illustrated in  FIG. 2 , the front cover  70  is rotatably supported by a hinge  71  on the apparatus main body  10  at a lower edge portion thereof. On right and left sides in the lower edge portion of the front cover  70 , supporting pieces  72  are provided. As illustrated in  FIG. 3 , each supporting piece  72  has an inclined face  72   a  inclined downward from a top portion, and a part where the top portion and the inclined face  72   a  cross each other is in the shape of an arc. 
         [0030]    In  FIG. 4 , a reference numeral  80  denotes a paper guide (sheet guide). The paper guide  80  is provided between the paper separating roller  41   b  and the resist roller pair  42  and corresponds to a part of the paper conveyance path for guiding the paper P to the resist roller pair  42 . The paper guide  80  is rotatably supported by a rotation shaft  81  provided on the apparatus main body  10 . 
         [0031]    The paper guide  80  includes plural of guide portions  82  arranged along the direction of the shaft (that is, a direction perpendicular to the sheet surface of  FIG. 4 ). Each guide portion  82  is in the shape of a plate, one side of which works as a guide face  82   a  to be brought into contact with the paper P. Between two of the guide portions  82  adjacent to each other at substantially the center along the direction of the shaft, a beam  83  extending along the guide face  82   a  is provided. The beam  83  has, on its upper end portion, a stopper (restricting portion)  86  to be brought into contact with a tip of an actuator (sheet detecting section)  90  described later. Furthermore, a moving portion  84  for pushing and rotating the actuator  90  is formed on a lower face of the beam  83 , and a part of the moving portion  84  for pushing the actuator  90  has a curved face. 
         [0032]    Two of the guide portions  82  disposed at both ends along the direction of the shaft are provided respectively with projecting pieces  85  to be brought into contact with the corresponding supporting pieces  72  when the front cover  70  is closed. The paper guide  80  having the aforementioned structure works together with the actuator  90  described next, so as to detect the paper P and make the actuator  90  recede at time of a jam. 
         [0033]    As illustrated in  FIG. 4 , the actuator  90  is rotatably supported by a rotation shaft  91  provided on the apparatus main body  10 . The actuator  90  includes a sensor section  92  extending from the rotation shaft  91  toward the front cover  70 . On the other hand, the apparatus main body  10  is provided with a photo-interrupter (detecting means)  90   a , so as to detect a state where the sensor section  92  blocks the optical axis of the photo-interrupter  90   a  or a state where it is out of the optical axis. 
         [0034]    At the both ends of the rotation shaft  91 , connecting portions  93  extending upward and then bent laterally to be connected to each other are formed. At the center of the connection portions  93 , an arm (projecting portion)  94  extending diagonally upward and backward is formed. As illustrated in  FIG. 2 , the paper guide  80  is provided with a hole  73  for allowing the arm  94  to pass therethrough. A part of the connecting portion  93  extending upward is provided with a catch  95 . The catch  95  is a portion with which the moving portion  84  is brought into contact and has a corner with a curved face. 
         [0035]    The actuator  90  having the aforementioned structure is supplied with force for causing clockwise rotation in  FIG. 4  by an elastic member not shown. On the other hand, as illustrated in  FIG. 3 , a pin (restricting portion)  96  is fixed on the rotation shaft  91  and a stopper (restricting portion)  74  to be brought into contact with the pin  96  is fixed on the supporting piece  72 . Thus, the rotation of the actuator  90  is restricted, and in this state, the sensor section  92  is in a stand-by position for blocking the optical axis of the photo-interrupter  90   a.    
       (3) Function of Paper Conveying Device 
       [0036]    Next, the function of the paper conveying device having the aforementioned structure will be described. As illustrated in  FIG. 4 , the arm  94  of the actuator  90  protrudes beyond the guide face  82   a  of the paper guide  80  so as to block the paper conveyance path. This state corresponds to the stand-by position where the pin  96  is in contact with the stopper  74 . When the paper P is conveyed from the paper drawing section  41 , the tip of the paper P comes into contact with the arm  94 , so as to rotate the actuator  90  (as illustrated in  FIG. 5 ). Then, the arm  94  comes into contact with the stopper  86  of the paper guide  80  to be stopped, and the paper P is fed beyond the tip of the arm  94 . At this point, the sensor section  92  of the actuator  90  is out of the optical axis of the photo-interrupter  90   a , and hence, the passage of the paper P is discriminated in accordance with a signal transmitted from the photo-interrupter  90   a.    
         [0037]    Next, an operation performed at time of a paper jam will be described. When the front cover  70  is opened, the paper guide  80  inclines together with the front cover  70  due to its own weight (as illustrated in  FIG. 6 ). At this point, the actuator  90  is supplied with the force for causing the clockwise rotation and hence keeps its position. Then, when the moving portion  84  of the paper guide  80  comes into contact with the catch  95  of the actuator  90 , the actuator  90  is rotated in the counterclockwise direction (as illustrated in  FIG. 7 ). At this point, the projecting pieces  85  of the paper guide slide and move on the inclined faces  72   a  of the supporting pieces  72  of the front cover  70 . 
         [0038]    When the front cover  70  is further rotated, a positional shift between the stopper  86  of the paper guide  80  and the arm  94  of the actuator  90  is increased, and hence the arm  94  slips off from the stopper  86  so as to be hidden in the beam  83  of the paper guide  80 . Then, jammed paper P is taken out of the paper conveyance path. 
         [0039]    In the paper conveying device having the aforementioned structure, when jammed paper is removed from the paper conveyance path, since the arm  94  is hidden in the beam  83  of the paper guide  80 , the arm  94  may be prevented from being damaged by the paper P. 
         [0040]    In particular, in the aforementioned exemplary embodiment, since the moving portion  84  of the paper guide  80  comes into contact with the catch  95  of the actuator  90 , damage and abrasion of the arm  94  may be suppressed. Furthermore, in the aforementioned exemplary embodiment, since the actuator  90  is supplied with the rotating force and the rotation is restricted to keep the stand-by position by the pin  96  and the stopper  74 , the actuator  90  may be kept in the stand-by position regardless of the position of the paper guide  80 , and hence, the detection accuracy is improved. 
         [0041]    In the aforementioned exemplary embodiment, when the paper guide  80  is rotated by a large angle, the arm  94  slips off from the stopper  86  so as to be hidden in the beam  83  of the paper guide  80 , and therefore, the arm  94  never comes into contact with the paper P or a human finger. Accordingly, damage of the arm  94  may be effectively prevented. 
         [0042]    In the aforementioned exemplary embodiment, since the moving portion  84  has the curved face in its part in contact with the catch  95  of the actuator  90 , damage and abrasion of the catch  95  may be suppressed even when the paper guide  80  is repeatedly rotated. Furthermore, since the paper guide  80  inclines due to its own weight when the front cover  70  is opened, the arm  94  may be made to recede from the paper conveyance path without performing an additional operation. 
         [0043]    It is noted that the present invention is not limited to the aforementioned exemplary embodiment but may variously applied. Specifically, the present invention is applicable to any conveying device as far as it conveys something in the shape of a sheet and is applicable to, for example, a paper conveying device for conveying paper after forming an image thereon or a conveying device for conveying paper currencies. Moreover, it is applicable not only to an electrophotographic image forming apparatus but also to an image forming apparatus employing another image forming method such as an ink jet method. 
         [0044]    The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The exemplary embodiments are chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various exemplary embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.