Patent Publication Number: US-10788785-B2

Title: Document cover closer and office equipment having the same

Description:
FIELD OF THE INVENTION 
     The invention relates to a document cover closer suitable in use for openably and closably attaching a document cover mounted on various sorts of office equipment, such as copying machine, printer, facsimile and scanner, to an office equipment main body; the invention also relates to office equipment equipped with such a document cover closer. 
     A document cover for openably and closably covering an upper surface of a contact glass (document glass) provided on an upper portion of a main body is disposed in a variety of office equipment, such as copying machine, printer, facsimile and scanner, which has function of reading documents. The document cover is attached to the main body via a document cover closer composed of a pair of hinge devices provided on the right and left toward a rear portion of an upper surface of the main body, such that it is possible to open the document cover from a front side of the main body. 
     In a document cover closer, an urging portion composed of coil springs, etc. for applying an urging force in an opening direction of the document cover is provided during an opening and closing operation of the document cover, in order to make it possible to open and close the document cover using a slight operation force. Still further, the urging portion has a free stop function for stopping a rotation in a closing direction by the document cover or its own weight and maintaining the document cover at the position as it stops, even if the user has his hands off the document cover within a predetermined angle (aperture) range during an opening and closing operation of the document cover. 
     In an urging portion, the free stop function is reduced due to changes over time. To this end, a spring force adjusting portion for a spring force of an urging portion is provided on the document cover closer (JP Laid-Open Patent Application No. 2011-139317). 
     In a spring force adjusting portion, when a disc-shaped adjusting plate constituting a rotatable spring seat is rotated around an axial direction of a coil spring of the urging portion being an axis of rotation, it moves along cam surfaces of cam portions toward the axis of rotation and changes a total length of coil springs to adjust a spring force. The adjusting plate is coupled to a moving piece screwing forward on a screw shaft disposed along a forward and backward direction of the main body. When the screw shaft is rotated using jig such as hexagonal wrench from a front surface side, the adjusting plate is rotated as well via the moving piece screwing forward. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a document cover closer as well as office equipment having such a document cover closer, wherein a mechanism of a spring force adjusting portion is further developed, so that it is possible to finely adjust a spring force and set its adjusting range within a wide range. 
     The first aspect of a document cover closer to achieve the object of the invention is a document cover closer for openably and closably attaching a document cover to a main body, characterized in that the document cover closer comprises: 
     an attaching member comprising a bottom plate portion attached to the main body, as well as a right side plate and a left side plate provided on both sides of the bottom plate portion; 
     a supporting member comprising a main body plate portion, a right side plate and a left side plate provided by bending the main body plate portion downward from its both side portions, as well as a right guide plate portion and a left guide plate portion provided by bending the right side plate and the left side plate inward from their respective lower end portions, the right side plate and the left side plate being rotatably attached to the right side plate and the left side plate of the attaching member via a first hinge pin; 
     a lift member for holding said document cover, which comprises a main body plate portion, a right side plate and a left side plate provided downward from its both side portions, as well as a right attaching plate portion and a left attaching plate portion provided outward from lower end portions of the right side plate and the left side plate, the right side plate and the left side plate being attached to the right side plate and the left side plate of the attaching member on the side of their respective free ends via a second hinge pin, such that the lift member is rotatable in a direction opposite to the rotational direction of said supporting member; 
     a first spring receiving portion in contact with a first pressure receiving member attached between the right side plate and the left side plate of the attaching member and slidably provided between the right side plate and the left side plate of the supporting member; 
     a second spring receiving portion comprising a second spring receiving hole in contact with a second pressure receiving member attached at a position at which the lift member swivels about a second hinge pin and slidably attached between the right side plate and the left side plate of the supporting member; an elastic member provided between said first spring receiving portion and said second spring receiving portion; 
     a spring force adjusting portion of the elastic member provided on said second spring receiving portion; 
     wherein the spring force adjusting portion comprises: 
     a pair of cam portions respectively having a cam surface tilted in one direction and provided on both sides of the second spring receiving hole of the second spring receiving portion; 
     a spring force adjusting plate having sliding cam plate portions in contact with respective cam portions on both sides, wherein the spring force adjusting plate is slidably provided toward an upper portion from an upper wall opening, wherein a screw screwing piece with a screw hole provided on one end is provided on a top portion of the second spring receiving portion; 
     a spring sheet plate having an adjusting screw attaching hole on one end and overlapping the screw screwing piece to protrude upward from the upper wall opening, wherein the spring sheet plate is provided to overlap the elastic member in contact with the latter on a lower surface of the spring force adjusting plate; and 
     a spring force adjusting screw for adjusting sliding width of the spring force adjusting plate, wherein the spring force adjusting screw is attached to an adjusting screw hole and screwed to a screw hole of the spring force adjusting plate. 
     The second aspect of a document cover closer to achieve the object of the invention is a document cover closer for openably and closably attaching a document cover to a main body, characterized in that the document cover closer comprises: 
     an attaching member comprising a bottom plate portion attached to the main body and right side plate and left side plate provided on both sides of the bottom plate portion; 
     a supporting member comprising a main body plate portion, a right side plate and a left side plate provided by bending the main body plate portion downward from its both side portions, as well as a right guide plate portion and a left guide plate portion provided by bending the right side plate and the left side plate inward from their respective lower end portions, the right side plate and the left side plate being rotatably attached to the right side plate and the left side plate of the attaching member via a first hinge pin; 
     a lift member for holding said document cover, which comprises a main body plate portion, a right side plate and a left side plate provided downward from its both side portions, as well as a right attaching plate portion and a left attaching plate portion provided outward from lower end portions of the right side plate and the left side plate, the right side plate and the left side plate being attached to the right side plate and the left side plate of the attaching member on the side of their respective free ends via a second hinge pin, such that the lift member is rotatable in a direction opposite to the rotational direction of said supporting member; 
     a first spring receiving portion in contact with a first pressure receiving member attached between the right side plate and the left side plate of the attaching member and slidably provided between the right side plate and the left side plate of the supporting member; 
     a second spring receiving portion comprising a second spring receiving hole in contact with a second pressure receiving member attached at a position at which the lift member swivels about a second hinge pin and slidably attached between the right side plate and the left side plate of the supporting member, and a damper attaching protruding portion provided to protrude on an inner top portion of the second spring receiving hole; an elastic member provided between said first spring receiving portion and said second spring receiving portion; 
     a damper housed in said elastic member and provided between the first spring receiving portion and said second spring receiving portion, the damper starting to function from a predetermined closing angle of the document cover closer; a spring force adjusting portion of the elastic member provided on the second spring receiving portion; 
     wherein the spring force adjusting portion comprises: 
     a pair of cam portions respectively having at least a cam surface tilted in one direction and provided on both sides of the second spring receiving hole of the second spring receiving portion; 
     a spring force adjusting plate having sliding cam plate portions in contact with respective cam portions on both sides, wherein the spring force adjusting plate is slidably provided toward an upper portion from an upper wall opening, wherein a screw screwing piece with a screw hole provided on one end is provided on a top portion of said second spring receiving portion, wherein the spring force adjusting plate further comprises a guide hole into which said damper attaching protruding portion is inserted; 
     a spring sheet plate having an adjusting screw attaching hole on one end and a screw holding piece overlapping said screw screwing piece to protrude upward from said upper wall opening, as well as a hole portion into which the damper attaching protruding portion is inserted, wherein the spring sheet plate is provided to overlap said elastic member in contact therewith on a lower surface of said spring force adjusting plate; and a spring force adjusting screw for adjusting sliding width of the spring force adjusting plate, wherein the spring force adjusting screw is attached to an adjusting screw hole and screwed to a screw hole of the spring force adjusting plate. 
     The third aspect of the document cover closer to achieve an object of the invention is characterized in that the spring force adjusting portion is provided on a first spring receiving portion. 
     The third aspect of the document cover closer to achieve an object of the invention is characterized in that the cam portions are formed in a right and left direction inside the first spring receiving portion or the first spring receiving portion to face each other, wherein the spring force adjusting cam plate comprises a pair of sliding cam plate portions on the right and left each having a sliding surface which respectively slides on each of cam surfaces of the pair of sliding cam plate portions on the right and left, wherein the spring sheet plate is disposed between the pair of sliding cam plate portions on the right and left. Office equipment to achieve an object of the invention is the fifth aspect and comprises a contact glass provided on a main body, on which a document is put, a document cover for openably and closably covering the contact glass, and a document cover closer according to one of the above-described aspects for attaching the document cover to the main body. 
     According to the first and the second aspects of the invention, a spring force adjusting cam plate moves along the cam trajectory of a linear cam portion in parallel to an elastic force adjusting screw to allow for a setting of a longer movement distance of the spring force adjusting cam plate, so that an elastic force can be finely adjusted over a wide range. Moreover, an adjustment of an elastic force of an urging portion can be realized by screwing an elastic force adjusting screw while a document cover is opened. 
     According to the third aspect of the invention, cam portions of the spring force adjusting portion can be provided using a first elastic member receiving portion and a second elastic member receiving portion, so that a document cover closer can be downsized. 
     According to the fourth aspect of the invention, a movement of a spring force adjusting cam plate can be realized with a simple structure. 
     According to the fifth aspect of the invention, a document cover closer can be downsized, so that a section around a contact glass of a main body to which the document cover closer is attached can have a neat design. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic perspective view of exterior appearance illustrating an embodiment of a copying machine equipped with a document cover closer according to the invention; 
         FIG. 2  shows an exploded perspective view illustrating an embodiment of a document cover closer for the left-hand side, as shown in  FIG. 1 ; 
         FIG. 3  shows a perspective view of exterior appearance illustrating a document cover closer (in an assembled state) as shown in  FIG. 2 , in a fully-opened state; 
         FIG. 4  shows an elevation view illustrating a document cover closer (in an assembled state) as shown in  FIG. 2 , in a fully-closed state; 
         FIG. 5  shows an arrow A-A cross section of  FIG. 4 ; 
         FIG. 6  shows a perspective view of exterior appearance illustrating an attaching member shown in  FIG. 2 , as seen from a back side; 
         FIG. 7  shows a supporting member shown in  FIG. 2 , where  FIG. 7A  is its left side view, and  FIG. 7B —an arrow B perspective view of  FIG. 7A ; 
         FIG. 8  shows a lift member shown in  FIG. 2 , where  FIG. 8A  is its left side view, and  FIG. 8B —an arrow C perspective view of  FIG. 8A ; 
         FIG. 9  shows a first spring receiving portion shown in  FIG. 2 , where  FIG. 9A  is a perspective view of its exterior appearance, as seen from a back side and  FIG. 9B —an arrow D perspective view of  FIG. 9A ; 
         FIG. 10  shows a second spring receiving portion shown in  FIG. 2 , where  FIG. 10A  is a perspective view of its exterior appearance, as seen from a front side,  FIG. 10B —its bottom view,  FIG. 10C —a perspective view of an inner surface on the left hand side, and  FIG. 10D —a perspective view of an inner surface on the right hand side; 
         FIG. 11  shows a spring force adjusting cam plate of a spring force adjusting portion shown in  FIG. 2 , where  FIG. 11A  is a perspective view of its exterior appearance, as seen from a back side,  FIG. 11B —an arrow D view of  FIG. 11A  and  FIG. 11C —an arrow E view of  FIG. 11A ; 
         FIG. 12  shows a spring sheet plate of a spring force adjusting portion shown in  FIG. 2 , where  FIG. 12A  is a perspective view of its exterior appearance, as seen from a back side and  FIG. 12B —an arrow F view of  FIG. 12A ; 
       In  FIG. 13 ,  FIG. 13A  shows a bottom view of a spring force adjusting cam plate as disposed at its position relative to a second spring receiving portion, and  FIG. 13B —a bottom view of a spring sheet plate as disposed at its position relative to a second spring receiving portion; 
         FIG. 14  shows a longitudinal cross section of a spring force adjusting portion shown in  FIG. 2 , more specifically illustrating a state in which a spring force is adjusted to the minimum; and 
         FIG. 15  shows a longitudinal cross section of a spring force adjusting portion shown in  FIG. 2 , more specifically illustrating a state in which a spring force is adjusted to the maximum. 
     
    
    
     EMBODIMENTS 
     In the following, the invention is described in detail based on embodiments shown in the drawings. 
       FIG. 1  shows a schematic perspective view of exterior appearance illustrating an embodiment of a copying machine equipped with a document cover closer according to the invention;  FIG. 2  shows an exploded perspective view illustrating an embodiment of a document cover closer for the left-hand side, as shown in  FIG. 1 ;  FIG. 3  shows a perspective view of exterior appearance illustrating a document cover closer (in an assembled state) as shown in  FIG. 2 , in a fully-opened state;  FIG. 4  shows an elevation view illustrating a document cover closer (in an assembled state) as shown in  FIG. 2 , in a fully-closed state; and  FIG. 5  shows an arrow A-A cross section. In the drawings, three orthogonal axes are respectively defined as X-, Y- and Z-axis, where a right and left direction is an X-axis, a backward and forward direction is a Y-axis, and an upward and downward direction is a Z-axis. In the meantime, a front side is abbreviated to (F), and a rear side to (R). 
     In  FIG. 1 , a copying machine  1  is a piece of office equipment equipped with an image reading portion, wherein a contact glass  3  is placed on an upper portion of a copying machine main body  2  being a main body. On the upper portion of the copying machine main body  2  as well, a document cover  4  for openably and closably covering an upper surface of the contact glass  3  is disposed. The document cover  4  is attached there via a pair of document cover closers  5  disposed on the right and left on an upper portion on a rear side (back surface side)  2   b  of the copying machine main body  2 , wherein each of document cover closers  5  is composed of a hinge device such that a front side of the copying machine main body  2  is opened to the outside. 
     (Overall Structure of Document Cover Closer  5 ) 
     Though they are both denoted with reference numerals  5 ,  5 , document cover closers on the right and left may have an identical structure, or the right one and the left one may have a structure different from each other. In the following, reference is made only to a document cover closer  5  on the left hand side, and not to a document cover closer  5  on the right hand side. 
     As shown in  FIG. 2 , the document cover closer  5  comprises an attaching member  10  being a base, a supporting member  20 , a lift member  30 , an urging portion  40  and an elastic force (spring force) adjusting portion  60 . The attaching member  10  is fixed to a copying machine main body  2  via an attaching button  6  (see  FIG. 5 ) attached to the copying machine main body  2  and attaching screws (not shown). In this embodiment, the supporting member  20  and the lift member  30  constitute a document cover tiltable holding portion. 
     A rear end portion side of a supporting member  20  is rotatably attached to an attaching member  10  via a first hinge pin  81  being a first hinge shaft. A lift member  30  is outer-fitted onto the supporting member  20  and rotatably attached to a tip side of the supporting member  20  via a second hinge pin  82  being a second hinge shaft. A document cover  4  is fixed to the lift member  30 . An urging portion  40  is internally installed inside the supporting member  20 . The urging portion  40  is elastically installed between a first pressure receiving member  83  disposed on the attaching member  10  and a second pressure receiving member  84  disposed on the lift member  30 . A spring force adjusting portion  60  is disposed on the urging portion  40 . 
     As shown in  FIG. 3 , a lift member  30  stops at a position at which an urging force (spring force) acts on a second pressure receiving member  84 , so that the lift member is urged relative to a supporting member  20  in a clockwise direction (CW direction) being an opening direction of a document cover  4 , with a second pressure receiving member  84  as a fulcrum, in order to normally stop as it overlaps the supporting member  20 . 
     When a document cover  4  is lifted from a closed state shown in  FIGS. 4 and 5  in a clockwise direction (CW direction in  FIG. 5 ), a supporting member  20  and a lift member  30  integrally rotate in a document cover closer  5 , and the document cover  4  is rotated to a fully-opened position shown in  FIG. 3 . When the document cover  4  is pushed down from the fully-opened position shown in  FIG. 3  in a closing direction, the supporting member  20  and the lift member  30  integrally rotate, with a first pressure receiving member  81  as a fulcrum, and the document cover  4  is rotated in a closing direction against an urging force of the urging portion  40 . 
     When the document cover  4  is pushed up for opening operation and pushed down for closing operation, it has a free stop function for stopping a rotation in a closing direction by the document cover  4  or its own weight and maintaining the document cover at the position as it stops, even if the user has his hands off the document cover  4  within a predetermined angle range. When the free stop function is degraded, a spring force of the urging portion  40  increases by adjusting operation of the spring force adjusting portion  60 . 
     When a document (not shown) placed on a contact glass  3  is thick and thus a document cover  4  is pushed down, a supporting member  20  tilting downward abuts against an upper edge of the document, which stops a tilting movement downward of a supporting member  20 . When the document cover  4  is further pushed down, a lift member  30  starts to rotate in a closing direction (in a CCW direction) against an urging force of an urging portion  40 , with a second hinge pin  82  as a fulcrum. Then, the document cover is pushed down, until the document cover  4  is in a contact with an upper surface of a thick document. 
     In this embodiment, a document cover  4  is openable and closable respectively relative to an attaching member  10  and a supporting member  20  via two hinge pins, a first hinge pin  81  and a second hinge pin  82  by a document cover holding portion composed of a supporting member  20  and a lift member  30 ; however, it is also possible that no lift member  30  is provided, and that a document cover  4  is fixed to the supporting member  20  and configured to be openable and closable at a single step; in this case, a second pressure receiving member  84  can be provided on a tip of the supporting member  20 . In summary, whether the document cover holding portion is composed of the supporting member  20  and the lift member  30  or only of the supporting member  20 , an urging portion  40  only has to apply the urging force to the document cover  4  in the opening and closing direction. 
     (Structure of Attaching Member  10 ) 
       FIG. 6  shows a perspective view of exterior appearance illustrating an attaching member shown in  FIG. 2 , as seen from a back side. Reference is made to structure of an attaching member  10 , with reference to  FIGS. 1 to 6 . 
     An attaching member  10  comprises a bottom plate portion  11  in the shape of rectangular flat plate, a left side plate portion  12  and a right side plate portion  13  provided on the left and right sides of the bottom plate portion  11 , and a back wall plate portion  14  between the left side plate portion  12  and the right side plate portion  13  and at a rear end of the bottom plate portion  11 . The left side plate portion  12 , the right side plate portion  13  and the back wall plate portion  14  are formed integrally with the bottom plate portion  11  by bending respective portions of the latter. 
     On the bottom plate portion  11 , a through hole  11   a  through which a screw (not shown) is passed through is formed, as well as an engaging hole  11   b  in which two hole portions with different inner diameters communicate with each other. As shown in  FIG. 5 , the attaching member  10  prevents an escape in an upward and downward direction by passing an attaching button  6  on a copying machine main body  2  side through a large diameter hole of an engaging hole portion  11   b , and then further drawing it into a small diameter hole of the engaging hole portion. There is a gap between a head portion of the attaching button  6  and a surface of a bottom plate portion  11 . 
     If in case of each document cover  4  being equipped with an automatic document feeder (ADF) attaching positions of document cover closers  5 ,  5  on the right and the left are not in parallel to a main body  2 , failure sometimes occurs between the ADF and the main body  2 ; to this end, an adjustment is made to achieve parallel attaching positions, by rotating an adjusting screw  16  from a front surface side, using jig such as driver, and thus slidably moving the height adjusting plate  15  in a forward and backward direction. 
     As shown in  FIGS. 2 and 5 , a U-shaped groove  15   c  is formed on a screw receiving plate portion  15   b  erected in an upward and downward direction on a forward and backward adjusting plate  15 . Furthermore, a screw hole  14   a  corresponding to the U-shaped groove  15   c  is formed on a back wall plate portion  14 . A concave groove  16   a  of a height adjusting screw  16  is fitted into the U-shaped groove  15   c , and a screw shaft portion  16   b  is screwed into the screw hole  14   a.    
     A left side plate portion  12  and a right side plate portion  13  of an attaching member  10  are formed to be bilaterally symmetrical. Shaft receiving holes  12   a ,  13   a  are formed on respective rear end portions of the left side plate portion  12  and the right side plate portion  13 , so as to face each other along an X-axis direction. As shown in  FIG. 6 , key grooves  12   b ,  13   b  are formed on the shaft receiving holes  12   a ,  13   a  along the X-axis direction. As shown in  FIG. 2 , each of bearings  17   b , each having a flange  17   a , is installed from outside in a corresponding one of the shaft receiving holes  12   a ,  13   a , with aligning keys (not shown) to the key grooves  12   b ,  13   b . Each of bearings  17   b  on the right and left is inserted into the corresponding one of the shaft receiving holes  12   a ,  13   a , until the respective flanges  17   a  abut against respective external surfaces of the left side plate portion  12  and the right side plate portion  13 . 
     A first hinge pin  81  is passed through each of bearings  17   b  on the right and left. Washers  17   c  are respectively attached from the outside of respective bearings  17   b  to both end portions of the first hinge pin  81 . Pierced end portions of the first hinge pin  81  which have passed through respective washers  17   c  pass through shaft holes  22   a ,  23   a  formed on side plates  22 ,  23  on the right and left of a supporting member  20 , and are then fixed by caulking and so on. Therefore, the first hinge pin  81  are respectively borne by the bearings  17   b  on the right and left to rotate integrally with a supporting member  20 . 
     First pin holes  18  to which a first pressure receiving member  83  is installed and fixed are formed further to a front surface side from shaft receiving holes  12   a ,  13   a  on respective rear end portions of left side plate portion  12  and the right side plate portion  13 , so as to face each other along an X-axis direction. The first pressure receiving member  83  and a first hinge pin  81  are provided side by side. In the meantime, the first pressure receiving member  83  has a shaft-like shape in this embodiment; however, it is not limited to this shape, but may be made of resin, or a bent curved member is also applicable here. 
     (Structure of Supporting Member  20 ) 
       FIG. 7  shows a supporting member shown in  FIG. 2 , where  FIG. 7A  is its left side view, and  FIG. 7B —an arrow B perspective view of  FIG. 7A . Reference is made to a structure of a supporting member  20 , with reference to  FIGS. 1 to 7 . 
     In  FIG. 7 , a supporting member  20  comprises a main body plate portion  21  formed in the shape of rectangular flat plate, a left side plate portion  22  and a right side plate portion  23  formed in a symmetrical shape on both side ends on the left and right along an X-axis direction of the main body plate portion  21 , a short left guide plate portion  24  formed on a tip of the left side plate portion  22 , and a short right guide plate portion  25  formed on a tip of the right side plate portion  23 ; the supporting member itself is thus formed substantially in the shape of rectangular parallelepiped. In  FIG. 7 , an inner space  26  of the supporting member  20  is formed into an urging portion housing space for slidably housing an urging portion  40  along a Y-axis direction. 
     A left side plate portion  22  and a right side plate portion  23  are bent inward at a right angle relative to a main body plate portion  21  to extend along a Z-axis direction. A left guide plate portion  24  and a right guide plate portion  25  are bent inward at a right angle from respective tips of the left side plate portion  22  and the right side plate portion  23 , so as to face each other. An opening  27  for maintenance is formed between the left guide plate portion  24  and the right guide plate portion  25  facing each other. 
     A supporting member  20  is outer-fitted onto an attaching member  10 , as shown in  FIG. 3 . On the left side plate portion  22  and the right side plate portion  23  of the supporting member  20 , shaft holes  22   a ,  23   a  to which a first hinge pin  81  is fixed by caulking are formed on a rear side, and shaft bearing holes  22   b ,  23   b  facing each other for pivotally supporting a second hinge pin  82  are formed on a tip side. Both end portions of the second hinge pin  82  are fixed by caulking to shaft holes  32   a ,  33   a  formed respectively on a left side plate portion  32  and a right side plate portion  33  of a lift member  30  opposite to each other, wherein the lift member is outer-fitted onto the supporting member  20 . The lift member  30  is rotatable relative to a tip side of the supporting member  20  via the second hinge pin  82  in a direction contrary to the supporting member  20 , and integrally with supporting member  20 , it is further rotatable relative to the attaching member  10  via the first hinge pin  81 . 
     (Structure of Lift Member  30 ) 
       FIG. 8  shows a lift member shown in  FIG. 2 , where  FIG. 8A  is its left side view, and  FIG. 8B —an arrow C perspective view of  FIG. 8A . Reference is made to structure of a lift member  30 , with reference to  FIGS. 1 to 8 . 
     In  FIG. 8 , a lift member  30  comprises a main body plate portion  31  formed in the shape of rectangular flat plate, a left side plate portion  32  and a right side plate portion  33  formed on both side ends on the left and right along an X-axis direction of the main body plate portion  31 , a short left attaching plate portion  34  formed on a tip of the left side plate portion  32 , and a short right attaching plate portion  35  formed on a tip of the right side plate portion  33 ; the lift member itself is thus formed substantially in the shape of rectangular parallelepiped. A supporting member  20  is internally installed inside an inner space  36  of the lift member  30 , and a rear end portion of a document cover  4  is attached to the main body plate portion  31 , the left attaching plate portion  34  and the right attaching plate portion  35 . 
     A left side plate portion  32  and a right side plate portion  33  are bent inward at a right angle relative to the main body plate portion  31  to extend along a Z-axis direction. A left attaching plate portion  34  and a right attaching plate portion  35  are bent outward at a right angle from respective tips of the left side plate portion  32  and the right side plate portion  33 . A document cover  4  is attached to the left flange plate portion  34  and the right flange plate portion  35 . Furthermore, the document cover  4  is attached to attaching pieces  37   a ,  37   b  respectively provided on a front portion of the left side plate portion  32  and a front portion of the main body plate portion  31 . 
     A lift member  30  is outer-fitted onto a supporting member  20 , as shown in  FIGS. 3 and 4 . On a left side plate portion  32  and a right side plate portion  33  of the lift member  30 , first shaft holes  32   a ,  33   a  facing each other to which a second hinge pin  82  is fixed by caulking are formed on a front side. Furthermore, on the left side plate portion  32  and the right side plate portion  33  of the lift member  30 , second shaft holes  32   b ,  33   b  to which a shaft-shaped second pressure receiving member  84  is fixed by caulking are formed on a front side. The first shaft holes  32   a ,  33   a  and the second shaft holes  32   b ,  33   b  are formed at predetermined intervals along a Z-axis direction. The first shaft holes  32   a ,  33   a  are formed between the main body plate portion  31  and the second shaft holes  32   b ,  33   b . In the meantime, the second pressure receiving member  84  has a shaft-like shape in this embodiment; however, it is not limited to this shape, but may be made of resin, or a bent curved member is also applicable here. 
     A lift member  30  is outer-fitted onto a supporting member  20 , and shaft end portions of a second hinge pin  82  which have passed through shaft bearing holes  22   b ,  23   b  of the supporting member  20  are fixed by caulking to first shaft holes  32   a ,  33   a . The lift member  30  is rotatable relative to the supporting member  20  via the second hinge pin  82 . Shaft end portions of a second pressure receiving member  84  are fixed by caulking to second shaft holes  32   b ,  33   b , following an insertion of an urging portion  40  into the supporting member  20 . 
     As shown in  FIG. 8 , a screw hole  38  passing through a main body plate portion  31  of a lift member  30  is provided on the main body plate portion  31 . A height adjusting screw  39  is screwed with the screw hole  38 , and its screw end abuts against an outer surface of a main body plate portion  21  of a supporting member  20 . When the height adjusting screw  39  is further screwed, the lift member  30  is tilted integrally with a document cover  4  downward to the front, and when the height adjusting screw  39  is screwed back, the lift member  30  is tilted integrally with the document cover  4  upward to the front. 
     In other words, a supporting member  20  is disposed, such that it can be housed in an inner space  36 , and thus a lift member  30  is rotatable relative to the supporting member via a second hinge pin  82 . As stated above, except when a thick document is placed on a contact glass  3 , due to a spring force of an urging portion  40 , the lift member  30  integral with the document cover  4  comes to a position in which it overlaps the supporting member  20 . While the document cover  4  is placed on the contact glass  3 , a surface of the document cover  4  is required to be horizontal to a surface of the contact glass  3  in a upward and downward direction. To this end, an adjustment of the height adjusting screw  39  makes it possible to adjust the document cover  4  to be horizontal in the upward and downward direction. 
     (Structure of Urging Portion  40 ) 
       FIG. 9  shows a first spring receiving portion  41  shown in  FIG. 2 , where  FIG. 9A  is a perspective view of its exterior appearance, as seen from a back side and  FIG. 9B —an arrow D perspective view of  FIG. 9A ;  FIG. 10  shows a second spring receiving portion  42  shown in  FIG. 2 , where  FIG. 10A  is a perspective view of its exterior appearance, as seen from a front side,  FIG. 10B —its bottom view,  FIG. 10C —a perspective view of an inner surface on the left hand side, and  FIG. 10D —a perspective view of an inner surface on the right hand side; Reference is made to structure of an urging portion  40 , with reference to  FIGS. 1 to 10 . 
     As shown in  FIG. 2 , an urging portion  40  comprises a first spring receiving portion  41  being a first elastic member receiving portion, a second spring receiving portion  42  being a second elastic member receiving portion, a first coil spring  43  being an elastic member, a second coil spring  44  being an elastic member and a damper  45 . The first coil spring  43  is installed inside the second coil spring  44 . The first coil spring  43  has a smaller spring constant and is slightly shorter than the second coil spring  44 . The damper  45  exhibits a weak or no damping effect when a piston rod  45   b  moves in an expanding direction relative to a cylinder  45   a , and a strong damping effect when a piston rod  45   b  moves in a retracting direction relative to a cylinder  45   a . The expression “when a piston rod  45   b  moves in an expanding direction relative to a cylinder  45   a ” refers to a phase in which a document cover is lifted in an opening direction, and that “when a piston rod  45   b  moves in a retracting direction relative to a cylinder  45   a ” refers to a phase in which a document cover is pushed down in a closing direction. In this embodiment, two coil springs, i.e. the first coil spring  43  and the second coil spring  44 , are used as elastic members; however, the invention is not limited thereto, but a single coil spring may be also acceptable. Furthermore, the damper  45  can be omitted. 
     In the first spring receiving portion  41 , engaging stepped portions  411   a ,  411   b  are formed on the right and left on the front wall portion  411  of a main body  41   a  formed substantially in the shape of rectangular parallelepiped. The engaging stepped portions  411   a ,  411   b  on the right and left are engaged with a left guide plate portion  24  and a right guide plate portion  25  of a supporting member  20 . The main body  41   a  is housed inside an inner space  26  with no backlash, and slidable in a longitudinal direction (forward and backward direction) of the supporting member  20 . 
     As shown in  FIG. 9 , a bottomed first spring receiving hole  413  having an opening  413   a  on the center of an upper surface  412  is formed on the main body  41   a . Respective one end portions of the first coil spring  43  and the second coil spring  44  are inserted into the first spring receiving hole  413 . Furthermore, as shown in  FIG. 5 , a screw portion on one end of the cylinder  45   a  being one end of the damper  45  is screwed into a screw hole  413   b  formed on an inner bottom of the first spring receiving hole  413 . 
     An arc cam portion  415  abutting against a first pressure receiving member  83  is formed on an outer bottom wall portion  414  of the main body  41   a  of a first spring receiving portion  41 . The arc cam portion  415  is formed on a cam surface projecting along a Z-axis direction, and a first cam surface  415   b  is formed to the front adjacent to a cam top  415   a , while a second cam surface  415   c  to the rear. Furthermore, when a document cover  4  is rotated in an opening direction, a supporting member  20  is rotated in an erecting direction relative to an attaching member  10 , with a first hinge pin  81  as a fulcrum. Moreover, a stopper concave portion  416  is formed on the outer bottom wall portion  414  to engage the first hinge pin  81  with the outer bottom wall portion  414  of the first spring receiving portion  41 . 
     When a document cover  4  is closed at a fully-closed position shown in  FIG. 5 , a first pressure receiving member  83  provided on an attaching member  10  abuts against a first cam surface  415   b  of an arc cam portion  415  of a first spring receiving portion  41 . When the document cover  4  is lifted from the fully-closed position shown in  FIG. 5  in an opening direction, a supporting member  20  is rotated in a clockwise direction (CW direction), with a first hinge pin  81  as a fulcrum, and in doing so, the first cam surface  415   b  as well as the cam top  415   a  passes by the first pressure receiving member  83 , so that the second cam surface  415   c  abuts against the latter. 
     A first cam surface  415   b  and a second cam surface  415   c  are both formed to be cam surfaces, wherein the former, when abutting against a first pressure receiving member  83 , generates a reaction force on a document cover  4  in a closing direction, while the latter, when abutting against the first pressure receiving member  83 , generates a reaction force on the document cover  4  in an opening direction. 
     Therefore, a document cover  4  is pressed toward a fully-closed position due to a spring force. Still further, when the document cover  4  is lifted in an opening direction, a cam top  415   a  passes by a first pressure receiving member  83  so that a second cam surface  415   c  abuts against the latter, the document cover  4  is tilted due to a spring force in an opening direction. The document cover  4  can be rotated in an opening direction, until a stopper concave portion  416  is engaged with a first hinge pin  81 . 
     In a second spring receiving portion  42 , engaging stepped portions  421   a ,  421   b  are formed on the right and left on a front wall portion  421  of a main body  42   a  formed substantially in the shape of rectangular parallelepiped. The engaging stepped portions  421   a ,  421   b  on the right and left of the second spring receiving portion  42  are engaged with a left guide plate portion  24  and a right guide plate portion  25  of a supporting member  30 . The main body  42   a  is housed inside an inner space  26  with no backlash, and slidable in a longitudinal direction (forward and backward direction) of the supporting member  20 . 
     As shown in  FIGS. 10B to 10D , a second spring receiving hole  423  having an opening  423   a  on a lower side, as well as an upper wall portion  422  as an inner wall, is formed on the main body  41   a . Respective other end portions of a first coil spring  43  and a second coil spring  44  are inserted into the second spring receiving hole  423 . A second spring receiving portion  42  is slidably housed in the supporting member  20 , with its opening  423   a  facing an opening  413   a  of a first spring receiving portion  41 . 
     Furthermore, a circular column-shaped damper attaching protruding portion  50  is formed on an inner surface of an upper wall portion  422  of a second spring receiving hole  423 . As shown in  FIG. 5 , a piston rod attaching hole  50   a  is formed on the damper attaching protruding portion  50 , wherein a tip of a piston rod  45   b  of a damper  45  is fitted and fixed to the piston rod attaching hole  50   a . The second spring receiving hole  423  is a housing space for a spring force adjusting portion  60 . 
     As a first coil spring  43 , a second coil spring  44 , a damper  45  and a spring force adjusting portion  60  are all disposed between a first spring receiving portion  41  and a second spring receiving portion  42 , all are housed into an inner space  26  of a supporting member  20 . A second pressure receiving member  84 , as fixed to a lift member  30 , abuts against an outer surface of an upper wall portion  422  of the second spring receiving portion  42 . An urging force of an urging portion  40  is applied to the second pressure receiving member  84  via the second spring receiving portion  42 . 
     (Structure of Spring Force Adjusting Portion  60 ) 
       FIG. 11  shows a spring force adjusting cam plate of a spring force adjusting portion shown in  FIG. 2 , where  FIG. 11A  is a perspective view of its exterior appearance, as seen from a back side,  FIG. 11B —an arrow D perspective view of  FIG. 11A  and  FIG. 11C —an arrow E perspective view of  FIG. 11A ;  FIG. 12  shows a spring sheet plate of a spring force adjusting portion shown in  FIG. 2 , where  FIG. 12A  is a perspective view of its exterior appearance, as seen from a back side and  FIG. 12B —an arrow F perspective view of  FIG. 12A ; in  FIG. 13 ,  FIG. 13A  shows a bottom view of a spring force adjusting cam plate as disposed at its position relative to a second spring receiving portion, and  FIG. 13B —a bottom view of a spring sheet plate as disposed at its position relative to a second spring receiving portion. Reference is made to structure of a spring force adjusting portion  60 , with reference to  FIGS. 1 to 13 . 
     A spring force adjusting portion  60  is composed of a second spring receiving portion  42  being a second elastic member receiving portion, a spring force (elastic force) adjusting cam plate  61 , a sheet plate  70  being an elastic member sheet plate portion and a spring force adjusting screw  80 . 
     In  FIG. 11 , a spring force adjusting cam plate  61  comprises a main body plate portion  62  substantially in the shape of rectangular flat plate, a left leg portion  63 L and a right leg portion  63 R extending downward from both sides on the right and left of the main body plate portion  62  along a Z-axis and formed in the shape substantially of triangle in a plan view, a left sliding cam plate portion  64 L and a right sliding cam plate portion  64 R respectively extending outward on a right and left direction from respective tilted ends of the left leg portion  63 L and the right leg portion  63 R, and a screw screwing piece  65  extending upward from a front end edge of the main body plate portion  62 . The spring force adjusting cam plate  61  is formed to be bilaterally symmetrical with a center line L 1  passing a center in a right and left direction of the main body plate portion  62  and running along a Y-axis direction as a center. 
     When a longitudinal direction (a sliding direction of the second spring receiving position  42 ) of an inner space  26  (an urging portion housing space) of a supporting member  20  is a Z-axis direction, a main body plate portion  62  of a spring force adjusting cam plate  61  is housed in a second spring receiving hole  423  of a second spring receiving hole  42 . A left sliding cam plate portion  64 L and a right sliding cam plate portion  64 R are tilted in a Y-Z plane at a tilting angle θ relative to the main body plate portion  62 . Respective upper surfaces of the left sliding cam plate portion  64 L and the right sliding cam plate portion  64 R are a left sliding surface  66 L and a right sliding surface  66 R, which are formed on tilted surfaces running down from a rear to a front. In other words, the left sliding surface  66 L and the right sliding surface  66 R are formed on cam surfaces having cam tracks changing their height along a spring force applying direction of an urging portion  40 . 
     A guide hole  62   a  long in a Y-axis direction is formed on a main body plate portion  62  of a spring force adjusting cam plate  61 , with a center line L 1  as a center. A screw hole  65   a  into which a spring force adjusting screw  80  being an elastic force adjusting screw is screwed is formed on a screw screwing piece  65 . 
     A spring force adjusting cam plate  61  is housed in a second spring receiving hole  423 , with the guide hole  62   a  being inserted into a piston rod attaching hole  50   a  of a second spring receiving portion  42 . 
     In  FIGS. 10B to 10D , a space inside a second spring receiving hole  423  is formed to be bilaterally symmetrical with a center line L 2  passing a center in a right and left direction of the main body plate portion  42  and running along a Y-axis direction as a center. A left cam portion  51 L and a right cam portion  51 R are formed along a forward and backward direction on respective inner circumferential side walls on the left hand side and right hand side of a damper attaching protruding portion  50 . A left cam surface  52 L of the left cam portion  51 L and a right cam surface  52 R of the right cam portion  51 R are formed on tilted surfaces running downward from a rear side to a front side at tilting angle θ. 
     As shown in  FIG. 13A , in a spring force adjusting cam plate  61  as housed in a second spring receiving hole  423 , a left sliding surface  66 L of a left sliding cam plate portion  64 L abuts against a left cam surface  52 L of a left cam portion  51 L, while a right sliding surface  66 R of a right sliding cam plate portion  64 R abuts against a right cam surface  52 R of a right cam portion  51 R.  FIG. 13A  shows a state in which the left sliding cam plate portion  64 L and the right sliding cam plate portion  64 R abut against respective rear end sides of the left cam portion  51 L and the right cam portion  51 R, and a state in which the main body plate portion  62  of the spring force adjusting cam plate  61  abuts against a ceiling wall surface of the second spring receiving hole  423 . 
     As shown in  FIG. 10 , an upper wall opening  424  is formed on a front portion of a damper attaching protruding portion  50  on a upper wall portion  422  of a second spring receiving hole  42 . A U-shaped groove portion in the U-shape connected to an upper wall opening  424  is formed on a front wall portion  421  of the second spring receiving hole  42 . A left guide piece  426 L and a right guide piece  426 R are pushed upward out of an upper surface of an upper wall portion  422  on the right and left of the upper wall opening  424 . 
     As the spring force adjusting cam plate  61  is housed in a second spring receiving hole  423  of the second spring receiving portion  42 , a screw screwing piece  65  is inserted into an upper wall opening  424 . The screw screwing piece  65  is guided by a left guide piece  426 L and a right guide piece  426 R, and movable in a forward and backward direction and a Z-axis direction. The screw hole  65   a  of the screw screwing piece  65  faces a U-shaped groove portion  425 . 
     When a spring force adjusting cam plate  61  moves at a predetermined interval (Y 1 ) from a rear end position shown in  FIG. 13A  to the front relative to a left cam portion  51 L and a right cam portion  51 R, it moves downward by a predetermined height (Z 1 ). A left leg portion  63 L and a right leg portion  63 R of the spring force adjusting cam plate  61  abut against an inner side surface of the left cam portion  51 L and the right cam portion  51 R, so that the spring force adjusting cam plate  61  is restricted in movement in a left and right direction, and its movement along a forward and backward direction and a Z-axis direction is guided. 
     A spring sheet plate  70  abuts against a lower surface of a main body plate portion  62  of a spring force adjusting cam plate  61 , and abuts against respective other ends of a first coil spring  43  and a second coil spring  44 . As shown in  FIG. 12 , the spring sheet plate  70  comprises a main body plate portion  71  formed in the shape substantially of square flat plate and a screw holding piece  72  extending upward in a Z-axis direction from a front end edge of the main body plate portion  71 . A hole portion  73  into which a damper attaching protruding portion  50  is fitted with gap is formed on the main body plate portion  71 , as well as four corner portions  74  in an arc shape. As shown in  FIG. 13B , side edges  75  on the right and left of the main body plate portion  71  extends up to the inside of the left leg portion  63 L and the right leg portion  63 R. Furthermore, side edges  76  at the front and rear ends of the main body plate portion  71  protrude outward from the four corner portions  74 . 
     An inner circumferential side wall surface of a second spring receiving hole  423  of a second spring receiving portion  42  is formed in conformity with an outer shape of a main body plate portion  71  of a spring sheet plate  70  (without an outer shape of side edges  75  on the right and left) to restrict movement of the spring sheet plate  70  in a forward and backward direction, and to guide movement in a Z-axis direction. Inner circumferential side wall surfaces  427  respectively corresponding to four corner portions  74  are formed in a curved concave shape, and inner circumferential side wall surfaces  428  in a forward and backward direction are formed in a concave groove shape. 
     A screw portion  80   a  of a spring force adjusting screw  80  is passed through a screw holding piece  72  of a spring sheet plate  70 , and a screw insertion hole  72   a  engaged with a head portion  80   b  is formed. The screw holding piece  72  is inserted so as to abut against a front end inner circumferential side wall surface of an upper wall opening  424 . The spring force adjusting screw  80  is inserted into the screw insertion hole  72   a  of the screw insertion piece  72 , and screwed with a screw hole  65   a  formed on a screw screwing piece  65  of a spring force adjusting cam plate  61 . A head portion  80   b  of the spring force adjusting screw  80  engaged with the screw insertion hole  72   a  is placed in a U-shaped groove portion  425  so as to be movable in a Z-axis direction. 
     In a spring force adjusting portion  60  according to this embodiment, a spring force adjusting cam plate  61  for adjusting a spring force of an urging portion  40  moves along cam tracks of a left cam portion  51 L and a right cam portion  51 R extending in linear shape in parallel to the spring force adjusting screw  80 . The lengths of the left cam portion  51 L and the right cam portion  51 R can be set according to that of the second spring receiving portion  42  along a forward and backward direction. Therefore, it is possible to set a moving distance of the left cam portion  51 L and the right cam portion  51 R to be long, so that a spring force can be finely adjusted over a wide range. 
     Still further, if it is not necessary to set a fine adjustment range to be long, it is enough to reduce a length of the left cam portion  51 L and the right cam portion  51 R, so that it is possible to downsize a second spring receiving portion  42  and it is possible to ensure a downsizing of a document cover closer  5 . 
     Still further, it is possible to combine an urging portion  40  with a spring force adjusting portion  60  into a single unit, to easily assemble a document cover closer and to ensure a downsizing of the document cover closer. 
     On the other hand, since cam portions (left cam portion  51 L, right cam portion  51 R) are formed using a second spring receiving portion, it is possible to ensure a downsizing of a document cover closer  5 . 
     Still further, in a spring force adjusting cam plate  61 , a screw hole  65   a  of a screw screwing piece  65  is screwed with a screw portion  80   a  of a spring force adjusting screw  80  to screw forward in accordance with a rotation of the spring force adjusting screw  80 , so that it is possible to ensure a movement of the spring force adjusting cam plate  61  in a simple structure. 
     Due to downsizing of a document cover closer  5  according to this embodiment, it is possible to ensure a neat layout around a contact glass  3  of a copying machine main body  2 . 
     In the following, reference is made to a spring force adjusting method of the spring force adjusting portion  60 , with reference to  FIGS. 14 and 15 . 
       FIG. 14  shows a longitudinal cross section of the spring force adjusting portion  60 , more specifically illustrating a state in which the spring force is adjusted to the minimum, and  FIG. 15  shows a state in which the spring force is adjusted to the maximum. 
     When the document cover  4  is opened e.g. to the fully-opened position, the opening  27  is provided on the front surface side of the supporting member  20 , so that the head portion  80   b  of the spring force adjusting screw  80  faces the front surface of the copying machine main body  2 , and it is possible to rotate the head portion  80   b  using the jig such as hexagonal wrench. As shown in  FIG. 14 , when the spring force adjusting screw  80  is rotated in the screwing direction relative to the screw hole  65   a , the spring force adjusting cam plate  61  moves forward in a Y-axis direction (toward the head portion  80   b  of the spring force adjusting screw  80 ). Here, the spring force adjusting cam plate  61  moves along the cam tracks downward in the Z-axis direction, as the left sliding surface  66 L of the left sliding cam plate portion  64 L and the right sliding surface  66 R of the right sliding cam plate portion  64 R respectively slide on the left cam surface  52 L of the left cam portion  51 L and the right cam surface  52 R of the right cam portion  51 R. 
     The spring sheet plate  70  which is restricted in movement in a Y-axis direction, while sliding on the spring force adjusting cam plate  61  moving forward along a Y-axis direction and downward in a Z-axis direction, moves downward in a Z-axis direction against the spring forces of the first coil spring  43  and the second coil spring  44 . Accordingly, the spring force of the urging portion  40  increases. The spring force of the urging portion  40  can be adjusted between a state in which the left sliding surface  66 L and the right sliding surface  66 R of the spring pressure adjusting cam plate  61  abut against the left cam surface  52 L and the right cam surface  52 R of the second spring receiving portion  42  at the highest position, as shown in  FIG. 14 , and a state in which the screw screwing piece  65  abuts against the screw insertion piece  72 , as shown in  FIG. 15 . 
     In the embodiment as described above, the spring force adjusting portion  60  is disposed on the second spring receiving portion  42 , but the spring force adjusting portion  60  can be disposed on the first spring receiving portion  41 . 
     A document cover closer according to the invention is applicable to office equipment having a function of reading documents, such as copying machine, scanner, facsimile and printer.