Patent Publication Number: US-7710614-B2

Title: Image forming device

Description:
FIELD OF THE INVENTION 
   The present invention relates to an image forming device comprising a document transport device. 
   BACKGROUND INFORMATION 
   At the present time, it is common to use image forming devices having document reading functions such as copiers, fax machines and scanners, which are provided with document transport devices. Document transport devices comprise a multiplicity of rollers on a document transport path, and because the document transport path turns, the internal mechanisms are complex and a the documents can be in various types of paper and various formats, documents sometimes jam in the internal document transport path. At this point, in order to remove the jammed document, it is necessary to expose the document transport path within the document transport device. 
   Furthermore, in the case of copiers capable of reading both sides of the document at the same time, a document reading area is also provided within the document transport device, and it is also necessary to expose the interior of the document transport device in order to clean that document reading area. 
   In terms of means for exposing the document transport path, means have been proposed wherein an external cover is opened to expose the interior from the top, and those wherein the document transport device (automatic document transport device) is opened with respect to the transparent glass platen (contact glass) so as to expose the pressure plate on the bottom thereof, whereafter an auxiliary frame is swung open from the top, so as to expose the document transport path from the underside thereof. 
   Furthermore, conventionally, devices have been proposed wherein the document transport device is opened with respect to the transparent glass platen (glass plate) and a bottom auxiliary frame is opened to expose the document transport path. 
   Furthermore, a plastic pressure sheet, which is backed with a soft material such as sponge, is generally mounted on the underside of the document transport device, so that the document that is placed on the transparent glass platen lies closely against the platen. 
   However, in the first mentioned prior art, it is not possible to expose the document transport path without first removing the external cover, which is bothersome and requires that a space be available in which the external cover that has been removed can be placed. 
   Furthermore, in the second mentioned prior art, with devices wherein a bottom auxiliary frame is opened to expose the document transport path, if the pressure sheet (document hold-down plate) is made from a soft material, the pressure sheet is bent, and this bending crease may result in the document not being sufficiently pressed against the transparent glass platen, so that the document cannot be read properly. 
   Thus, an object of the present invention is to provide an image forming device wherein the document transport device used in the image forming device allows for exposure of the interior of the document transport device from the bottom by a single operation, and wherein the pressure sheet is not bent when the interior of the document transport device is exposed. 
   SUMMARY OF THE INVENTION 
   In order to achieve this object, in the image forming device according to the present invention are provided a transparent glass platen and a document transport device at the top thereof, the document transport device being hinged at one side thereof so as to open and close in a perpendicular plane and having a document transport unit at one end thereof in the direction of the hinging axis, a first document reading device for reading a document being disposed below the platen, and there being defined on the top side of the platen, successively from the upstream side in the direction of transport of the document which is automatically transported along a document transport path by the document transport unit, an automatic-transport document reading area and a static document reading area, for reading, by the first document reading device, an automatically transported document and a document that is statically disposed on the platen, respectively; and the image forming device comprises: on the bottom side of the document transport device, a bottom plate that covers a portion thereof that faces the static document reading area, downstream in the direction of transport of the document, from the portion facing the automatic-transport document reading area, this bottom plate being supported so as to be able to open and close at the document transport device, and having as a swing pivot a swing axis that is orthogonal to the hinging axis at the terminus thereof that is distal with respect to the automatic-transport document reading area, the bottom side thereof being a pressure face for pressing down on a document placed on the static document reading area; and a document transport path bottom member, which constitutes a bottom side of the document transport path, which is disposed downstream from the automatic-transport document reading area on the document transport path, this document transport path bottom member being swingably supported by a document transport device main body, one end thereof being the center of swing and the other end thereof being a slide engagement unit for slidably engaging in the swinging end of the bottom plate, the bottom plate swinging in conjunction with the swing of this document transport path bottom member. 
   Furthermore, in the image forming device of the present invention, a second document reading device is provided within the document transport unit for reading the surface of the document that is opposite to the surface that is read by the automatic-transport document reading area, this second document reading device being disposed in a position opposite from the document transport path bottom member. 
   Furthermore, in the image forming device of the present invention, the slide engagement unit comprises a groove formed in a side wall that is formed on the bottom plate so as to extend in parallel to the direction of swing of the bottom plate and a connecting pin provided on the end of the document transport path bottom member that connects with the bottom plate, the groove being inclined downward in the direction of the swinging end of the bottom plate. 
   Furthermore, in the image forming device of the present invention, a handle is provided on the document transport path bottom member. 
   Furthermore, the image forming device of the present invention comprises a locking means consisting of a locking pin provided on the document transport path bottom member and a hook provided on the interior side of the outer case of the document transport device for engaging with the locking pin, the locking means serving to hold the bottom plate closed. 
   Furthermore, in the image forming device of the present invention, a biasing means for biasing the bottom plate in the direction that presses down on a document statically placed on the platen are mounted in the vicinity of both ends of the swing pivot of the bottom plate of the document transport device and in the vicinity of the connecting pin of the document transport path bottom member. 
   In the image forming device of the present invention, a bottom plate covers a portion of the bottom side of the document transport device from a portion downstream in the direction of transport of the document, with respect to the portion that faces the automatic-transport document reading area, to a portion that faces the static document reading area, and this bottom plate is supported by the document transport device so as to be able to open and close. Because the swinging end of this bottom plate and the document transport device main body are connected by a swingable document transport path bottom member, when the bottom plate is opened with the document transport device open, the document transport path bottom member swings at the same time, so that the interior of the document transport unit can be exposed, and because the bottom plate is not open to a greater extent than necessary, problems such as the opened bottom plate striking the platen are avoided. Furthermore, because the bottom face of this bottom plate serves as a document pressure face, it does not bend in the manner of a pressure sheet made from a soft material. 
   Furthermore, according to the present invention, a second document reading device is provided within the document transport unit for reading the face of the document that is opposite to the face that is read by the automatic-transport document reading area, whereby both sides of the document that is automatically transported can be read at the same time. 
   Furthermore, according to the present invention, because the slide engagement unit comprises a groove formed in a side wall that is formed on the bottom plate and a connecting pin provided on that end of the document transport path bottom member that is connected to the bottom plate, and because the position of the groove is inclined downwards in the direction of the swinging end of the bottom plate, when seen with the document transport device level, it is possible to avoid a situation wherein the opening action of the bottom plate is converted to a closing action during the swing of the document transport path bottom member, when the bottom plate is opened. 
   Furthermore, according to the present invention, a handle is provided on the document transport path bottom member, whereby the bottom plate can easily be opened. 
   Furthermore, according to the present invention, a locking means for holding the bottom plate closed is provided between the document transport device and the document transport path bottom member so that, when the document transport device is opened, the bottom plate will not be opened unintentionally. 
   Furthermore, according to the present invention, a biasing means for biasing the bottom plate in the direction that presses down on the document on the platen are mounted in the vicinity of both ends of the swing pivot of the bottom plate on the document transport device and in the vicinity of the connecting pin on the document transport path bottom member, whereby the document tends to be in close contact with the platen. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic structural view of a copier. 
       FIG. 2  is an external perspective view of the upper part of a copier with the document transport device opened and the bottom plate closed. 
       FIG. 3  is an external perspective view from the bottom of a document transport device with the bottom plate opened. 
       FIG. 4  is a schematic structural view of a document transport device with the bottom plate opened. 
       FIG. 5A  to  FIG. 5D  are partial schematic structural views illustrating how the bottom plate is opened. 
       FIG. 6  is a schematic structural view as seen from the front of the periphery of the document transport path bottom member when a handle and a hook are provided. 
       FIG. 7  is a schematic structural view of the vicinity of a bottom plate pivot provided with a biasing means. 
       FIG. 8  is a partial schematic structural view of a document transport path bottom member provided with a biasing means. 
       FIG. 9  is a partial external front view of a document transport path bottom member provided with a biasing means. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereafter, a mode of embodiment of the present invention is described with reference to the drawings.  FIG. 1  is a schematic structural view of a copier according to a mode of embodiment of the image forming device of the present invention. A main housing  1  comprises an upper housing  11 , a lower housing  13  and a connecting housing  12  situated therebetween; and a document transport device  2  is mounted on the upper housing  11 . The document transport device  2  is mounted in a hinged manner with the hinge pivot at the far end of the paper face. 
   The document transport device  2  comprises a document transport device main body  21 , a document loading unit  22 , a document transport unit  23 , a document output tray  24  and a bottom plate  25 . The document output tray  24  is formed integrally with the document transport device main body  21 , as a portion of the upper face thereof. The document loading unit  22  constitutes the upstream terminus of a document transport path d, and the document output tray  24  constitutes the downstream terminus of the document transport path d. The document transport path d within the document transport unit  23  comprises, in order of the direction of document transport from the upstream end, a pickup roller  23   a , a pair of transport rollers  23   b , a pair of resist rollers  23   c , a document transport path bottom member  71 , which constitutes the bottom side of the document transport path d, and a pair of output rollers  23   d . Along the document transport path d, in the section extending from the pair of resist rollers  23   c  to the document transport path bottom member  71  are defined an automatic-transport document reading area  27   a  and an automatic-transport document backside reading area  28 , and a second document reading device  4  is provided. The automatic-transport document reading area  27   a  is defined on the top side of the transparent glass platen  27 , on top of the upper housing  11 , and the automatic-transport document backside reading area  28  is defined on the top side of the document transport path bottom member  71 . The second document reading device  4  is provided facing the document transport path bottom member  71 , within the document transport unit  23 . 
   When a copy start button (not shown in the drawing) is pressed, a document (not shown in the drawing) having images on both sides thereof, which is set in the document loading unit  22 , is transported along the document transport path d by the rollers, and the image on one side thereof is read by the first document reading device  3  at the automatic-transport document reading area  27   a  while the image on the other side thereof is read by the second document reading device  4  at the automatic-transport document backside reading area  28 , both areas being defined on this path. The bottom plate  25  is formed on the bottom of the document transport device  2 , from a point immediately downstream from the automatic-transport document reading area  27   a  on the document transport path d, to a terminus at which the document transport unit  23  of the document transport device main body  21  is not provided. Furthermore, the bottom side of the bottom plate  25  serves as a pressure face for pressing down from above on the document that has been placed on the platen  27 . Here, a pressure sheet made from soft materials, comprising a base made from sponge or the like, and a sheet made from vinyl or the like, which is fixed on the side of the base that contacts the document, may be mounted on the bottom side of the bottom plate  25 . 
   The first document reading device  3  is housed within the upper housing  11 . The first document reading device  3  comprises an exposing lamp  31 , a reflecting plate  32 , a first mirror  33 , a second mirror  34 , a third mirror  35 , a condensing lens  36  and an image sensor (for example a line type CCD)  37 . The exposing lamp  31  and the first mirror  33  are mounted on a first carriage (not shown in the drawing), and the second mirror  34  and third mirror  35  are mounted on a second carriage (not shown in the drawing). When the document image is read in what is known as the sheet-through mode, the first carriage travels to a position directly below the automatic-transport document reading area  27   a , and the document is exposed to irradiation light from the exposing lamp  31 , while it moves. This irradiation light reaches the CCD  37  by way of the first mirror  33 , the second mirror  34 , the third mirror  35  and the condensing lens  36  and is read as an electrical signal by way of photoelectric conversion processing. Meanwhile, when the document image is read in the stationery document mode, the image on a document that is placed over the static document reading area  27   b , which is defined on the transparent glass platen  27 , is scanned by the exposing lamp  31  and the first mirror  33  on the first carriage, which moves to the right in  FIG. 1 , under the platen  27 , so as to perform reduction imaging onto the CCD  37 , thereby reading the image as an electrical signal by way of photoelectric conversion processing. 
   Only when in sheet through mode, in the same manner as with the automatic-transport document reading area  27   a , the document image is likewise read as an electrical signal at the automatic-transport document backside reading area  28 , using an exposing device housed in the second document reading device  4 . 
   A paper output tray  14  is provided in the connecting housing  12  for outputting paper P on which an image has been formed. 
   The lower housing  13  houses a paper feed unit  4 , an image forming unit  5  and a fixing device  6 . First, the paper feed unit  4  will be described. The paper feed unit  4  consists of a paper feed cassette  41 , a paper feed roller  42 , a paper feed tray  43 , a paper feed roller  44  and a pair of transport rollers  45 . The paper feed cassette  41  for storing the paper P is disposed at the bottom of the lower housing  13 , and the paper P is fed out therefrom one sheet at a time to a paper transport path  46 , by the paper feed roller  42  and transported by the transport rollers  45 . Furthermore, the paper feed tray  43 , which can be opened and closed, is provided at the bottom left-hand side of the lower housing  13 , and by placing the paper P therein, the paper P is fed out one sheet at a time by the paper feed roller  44  to the paper transport path  46  and transported by the transport rollers  45  in the same manner as described above. 
   Next, the image forming unit  5  will be described. The image forming unit  5  comprises a photosensitive drum  51 , a charger  52  disposed at the periphery thereof, an optical scanning unit  53 , a developer  54 , a transfer roller  55  and a cleaner  56 . The photosensitive drum  51  rotates clockwise so that, first of all, the surface of the photosensitive drum  51  is uniformly charged by the charger  52 . Next, the surface of the photosensitive drum  51  is irradiated with laser light from the optical scanning unit  53  so as to eliminate the charge from areas corresponding to those portions of the paper P on which the image is to be formed, or corresponding to those portions of the paper P on which the image is not to be formed, so as to form an electrostatic latent image on the surface of the photosensitive drum  51 . Next, the electrostatic latent image is made manifest by supplying toner to the electrostatic latent image on the photosensitive drum  51  with the developer  54 . 
   The photosensitive drum  51  further rotates so that, when the toner image reaches a position opposite the transfer roller  55 , in coordination therewith, paper P is transported between the photosensitive drum  51  and the transfer roller  55 . At this time, by applying to the transfer roller  55  a voltage having a polarity opposite to the polarity of the toner, the toner image on the photosensitive drum  51  is transferred onto the paper P. The remaining toner on the photosensitive drum  51 , which was not transferred, is removed from the photosensitive drum  51  by the cleaner  56 . Meanwhile, the paper P onto which the toner image has been transferred is transported to the fixing device  6 , which consists of a fixing roller  61  and a pressure roller  62  that are brought into contact by pressure, where the toner image is heated and pressed so as to fix it on the paper. Thereafter, the paper P is output to the output tray  14  by way of an output path. 
   In the present invention, as shown in the external perspective view of the top of an image forming device with the document transport device  2  open in  FIG. 2 , the bottom side of the document transport device  2  is formed with a bottom plate  25  at that portion thereof that faces the static document reading area  27   b , downstream in the direction of the transport of the document with respect to the portion facing the automatic-transport document reading area  27   a.    
   As shown in  FIG. 2 , when the document transport device  2  is open, the bottom plate  25  can be opened in the manner shown in the external perspective view and the schematic structural views, seen from the front, of the document transport device  2  shown in  FIG. 3  and  FIG. 4 . The bottom plate  25  is supported by the document transport device main body  21  in a hinged manner, hinging on a pivot  25   a  at the distal terminus thereof with respect to the portion facing the automatic-transport document reading area  27   a . Furthermore, the bottom plate  25  is provided with a groove  25   c  in a side wall  25   b , which is formed so as to extend in parallel with the direction of opening and closing of the bottom plate  25 . Here, the document transport path bottom member  71 , described above, is swingably supported, at one end thereof, by the document transport device  2 , and a connecting pin  71   a  is provided at the other end thereof, this connecting pin  31   a  being slidably inserted into the groove  25   c . The groove  25   c  is provided at a downwards inclination in the direction of the swinging end of the bottom plate  25 , as seen when the document transport device  2  is level. 
   The manner in which the bottom plate  25  is opened is schematically illustrated in  FIG. 5A  through  FIG. 5D . As the bottom plate  25  is opened by hand and the document transport path bottom member  71  is swung, the connecting pin  71   a , which is provided on the document transport path bottom member  71 , slides in the groove  25   c , which is provided in the side wall  25   b , that is formed on the bottom plate  25 . It will be understood that, because the groove  25   c  is provided at a downwards inclination in the direction of the swinging end of the bottom plate  25 , as seen when the document transport device  2  is level, even if the document transport path bottom member  71  continues to swing after the connecting pin  71   a  passes the bottom dead center, the opening action of the bottom plate  25  will continue, without being converted to a closing action. 
   By virtue of this constitution, when the bottom plate  25  is opened with the document transport device  2  in the open state, the document transport path bottom member  71  swings so that the interior of the document transport unit  23  can be exposed from the bottom of the document transport device  2 , whereby a document jammed in the document transport unit  23  can easily be removed and the second document reading device  4  can easily be cleaned. Furthermore, because the document transport path bottom member  71  does not allow the bottom plate  25  to be opened more than is necessary, with respect to the document transport device  2 , problems such as the opened bottom plate  25  striking the platen  27  are eliminated. Furthermore, the bottom plate  25  does not bend, even when opened, so that there is no risk of the document being improperly read because of insufficient pressing of the document against the platen  27 , due to bending creases, such as occur when soft pressure sheets are bent by opening. 
   Furthermore, because the groove  25   c  is provided at a downwards inclination in the direction of the swinging end of the bottom plate  25 , as differs from a case in which the groove  25   c  and the bottom plate  25  are separated by a parallel interval, the movement of the bottom plate  25  is not converted to a closing movement during the swing of the bottom plate  25 , so that it is possible to sufficiently expose the interior of the document transport unit  23 , whereby documents jammed in the document transport unit  23  can easily be removed and the document reading device  4 , as well as the document transport path bottom member  71 , can easily be cleaned. 
     FIG. 6  is a schematic structural view of the vicinity of the document transport path bottom member  71 , as seen from the front. A handle  71   b  is provided on the document transport path bottom member  71 , and a locking means  72  is provided between the document transport device  2  and the document transport path bottom member  71 . 
   The handle  71   b  is located in a position whereby it does not hide behind the side wall  25   b  formed on the bottom plate  25  when the bottom plate  25  is closed. The locking means  72  consists of a hook  72   a  and a locking pin  72   b , provided on the document transport path bottom member  71 . The hook  72   a  is provided rotatably on the interior of the outer case of the document transport device  2 , with the top end thereof serving as a pivot  72   c , and is biased in the right hand rotational direction around the pivot  72   c  by a biasing means. When the bottom plate  25  is closed, the hook  72   a  is engaged with the locking pin  72   b , and when the bottom plate  25  is to be opened, the hook  72   a  is moved in the left hand rotational direction around the pivot  72   c , so as to disengage the hook  72   a  from the locking pin  72   b.    
   Thus, by providing the handle  71   b  on the document transport path bottom member  71 , the bottom plate  25  can easily be opened. Furthermore, if there is no handle  71   b , when the bottom plate  25  is to be opened, this may be opened by grasping not only the bottom plate  25 , but also the document transport path bottom member  71  with a hand, but if the handle  71   b  is present, it is not necessary to touch the paper transport surface of the document transport path bottom member  71  or the face of the bottom plate  25  that is contacted by the paper, whereby it is possible to avoid such problems as being soiled by the dirt in these places. Furthermore, because of the locking means  72 , the bottom plate  25  is not unintentionally opened when the document transport device  2  is opened. 
     FIG. 7  and  FIG. 8  are schematic structural views of the periphery of the pivot  25   a  for the bottom plate  25 , and the periphery of the document transport path bottom member  71 . In the vicinity of both ends of the pivot  25   a  and the connecting pin  71  of the document transport path bottom member  71  are mounted springs  81  and springs  82  for biasing the bottom plate  25  in the direction that presses down on the document on the platen  27 . 
   As shown in  FIG. 7 , the pivot  25   a  is provided in a floating member  83 . The floating member  83  is housed in a pocket  21   a  formed in the document transport device main body  21 , and is capable of traveling along a fixed stroke in the vertical direction as shown in the drawing. The floating member  83  is biased in the direction whereby it is pushed out from the pocket  21   a  by the spring  81 . When the floating member  83  is inserted into the pocket  21   a , hooks  83   a , which are provided on the floating member  83 , are flexed in the opening of the pocket  21   a , and when inserted to a certain degree into the pocket  21   a , the flexure returns to its original state, so that the floating member  83  is prevented from coming out of the pocket  21   a  by the hooks  83   a.    
   Likewise, the connecting pin  71   a  is provided in a floating member  84  as shown in  FIG. 8 . The floating member  84  is housed in a pocket  71   d  formed in the document transport device bottom member  71 , and is capable of traveling along a fixed stroke in the vertical direction as shown in the drawing. The floating member  84  is biased in the direction whereby it is pushed out from the pocket  71   d  by the spring  82 . When the floating member  84  is inserted into the pocket  71   d , hooks  84   a , which are provided on the floating member  84 , are flexed in the opening of the pocket  71   d , and if inserted to a certain degree into the pocket  71   d , the flexure returns to its original state, so that the floating member  84  is prevented from coming out of the pocket  71   d  by the hooks  84   a . Furthermore,  FIG. 9  is an external view of the part shown in  FIG. 8 . The connecting pin  71   a  is exposed by a groove  71   e , which is provided in the document transport path bottom member  71 . 
   The floating member  83  can move, vertically as seen in the drawing, within the range of a fixed stroke allowed by the movement of the hooks  83   a  in the pocket  21   a , and is pushed into the pocket  21   a  under bias by the spring  81  when the document transport device  2  is closed. The floating member  84  can likewise move, vertically as seen in the drawing, within the range of a fixed stroke allowed by the movements of the hooks  84   a  in the pocket  71   d . Both  FIG. 8  and  FIG. 9  show the situation when the document transport device  2  is closed. When the document transport device  2  is opened, the floating members  83  and the floating number  84  are pushed out in the downward direction as seen in the figure by the spring  81  and the spring  82 . 
   By virtue of this constitution, when a document having a fold is placed on the platen  27 , even if this does not lie flat, the bottom plate  25  is biased by the spring  81  and the spring  82  by closing the document transport device  2  so that the document is in close contact with the platen  27  and the image can be read properly. 
   In the present invention, the second document reading device  4  maybe omitted, and in this case two-sided reading of a document having images on both sides is possible by separately reading the frontside and backside of the document with the automatic-transport document reading area  27   a.