JP2008292517A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize a nip pressure for a pair of conveying rolls by increasing positioning accuracy of a conveying unit, thereby smoothly conveying a sheet. <P>SOLUTION: The conveying unit held between a front side of an image forming apparatus body and a front cover is opened and closed with an opening and closing action of the front cover and composes a sheet conveying path by being arranged in a closed position, and is arranged in an open position to open the sheet conveying path, so that taking out of jammed paper is facilitated. The front cover has a freely turnable shaft member 82 and a hook member 83 integral with the shaft member 82. When the opened front cover is arranged in the closed position and the conveying unit is arranged in the closed position, the conveying unit is positioned by engaging the shaft member with an engaging recess in the conveying unit and the front cover is positioned by causing the hook member integral with the shaft member to engage with a locking member on the image forming apparatus body side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention includes an openable / closable front cover disposed on the front side of the image forming apparatus main body, and an openable / closable transport unit disposed between the front side of the image forming apparatus main body and the front cover. The present invention relates to an image forming apparatus.

  2. Description of the Related Art Image forming apparatuses such as printers, copiers, facsimiles, and multi-function machines of these types are known that include an openable front cover and a transport unit on the front side (or the left and right side surfaces) of the image forming apparatus main body. (For example, refer to Patent Document 1).

Each of the front cover and the conveyance unit is supported by the front side of the main body of the image forming apparatus so that the lower end of each of the front cover and the conveyance unit is swingable. A sheet conveying path is formed between the units, and a sheet reconveying unit used when forming an image on the back surface of the sheet is also formed between the conveying unit and the front cover. In this image forming apparatus, when a paper jam occurs, the transport unit is also opened as the front cover is opened. That is, when the front cover is opened, the transport unit is opened while being supported by the front cover from below. By opening the front cover and the conveyance unit, the sheet conveyance path and the sheet re-conveyance path are opened and exposed, so that jammed paper can be easily found and removed. After the jam processing, when the front cover is moved toward the closed position, the transport unit is moved toward the closed position so as to be pushed up by the middle portion of the front cover, and is arranged at the upper part on the front cover side. The hook member is engaged with the engaging portion on the image forming apparatus main body side and the front cover is disposed at the closed position, and at the same time, is pressed by the intermediate portion and disposed at the closed position. When the transport unit is placed in the closed position, the transport roller pair in the sheet transport path and the sheet re-transport path that are separated from each other in the open position is pressed to form a transport nip for nipping and transporting the sheet. It has come to be.
JP 2005-138967 A

  However, according to the above-mentioned Patent Document 1, it is difficult to dispose the transport unit in the closed position with high accuracy, and there is a problem that the nip pressure in the transport nip becomes unstable.

  That is, the front cover is positioned at the closed position by engaging the upper hook with the engaging portion on the image forming apparatus main body side, while the transport unit is positioned at the intermediate portion of the front cover positioned at the closed position. It is pressed and positioned at the closed position to form a transport nip. For this reason, even if the front cover can be positioned with high accuracy directly by the hook with respect to the image forming apparatus main body, the transport unit is different from the upper hook in the front cover and is located in the middle away from the hook. Since it is indirectly positioned by the part, it is easily affected by the manufacturing and assembly accuracy of each member and the deformation of the front cover, and it is difficult to position with high accuracy. As a result, the nip pressure becomes unstable in the pair of conveyance rollers in the sheet conveyance path and the sheet re-conveyance path, and the sheet conveyance accuracy is lowered.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of improving the positioning accuracy of a transport unit using a front cover.

  The invention according to claim 1 relates to an image forming apparatus including a sheet conveying unit that conveys a sheet and an image forming unit that forms a toner image on the sheet conveyed by the sheet conveying unit. The image forming apparatus according to the present invention is supported by the image forming apparatus main body in which the image forming unit is disposed and the lower end side of the image forming apparatus main body so as to be swingable, and on the front side of the image forming apparatus main body. An openable and closable front cover that takes a closed position that covers the front side and an open position that opens the front side of the image forming apparatus main body, and a lower end side that is swingably supported by the image forming apparatus main body. Between the front cover disposed on the front side of the image forming apparatus main body and the front side of the image forming apparatus main body, and a closed position that forms the sheet conveying unit, and an opening that opens the sheet conveying unit when the front cover is opened. And a lock mechanism interposed between the image forming apparatus main body and the front cover, and the lock mechanism is disposed on the image forming apparatus main body side. And a shaft member that is disposed on the front cover side in the left-right direction, and presses the transport unit and positions the front cover when the front cover is moved from the open position to the closed position. And a hook member that is integrally formed with the shaft member and that can be engaged with and disengaged from the locking member and that positions the front cover at the closed position when engaged.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the conveyance unit is configured such that the shaft unit on the front cover side disposed at the closed position is engaged with the conveyance unit. It has the engagement recessed part positioned in the said closed position, It is characterized by the above-mentioned.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the hook members are respectively disposed at both left and right ends of the shaft member, and the locking members are respectively disposed on the image forming apparatus main body side. It is arrange | positioned in the position corresponding to the said hook member.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the lock mechanism is one of the entrance of the engaging recess on the transport unit side and the shaft member. A cam portion formed on the other side and a cam follower portion formed on the other side, and the cam portion and the cam follower portion are configured to move the cam when the front cover is moved from the open position toward the closed position. It is characterized in that the hook member is formed in a shape to rotate in the engaging direction via the shaft member by the relative movement of the cam follower portion and the cam follower portion.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the sheet conveying unit includes the conveying unit disposed at the closed position and a front side of the image forming apparatus main body. A sheet conveyance path configured between the sheet transport path and the sheet transport unit disposed at the closed position and the front cover to guide the image-formed sheet to the image forming unit again. It is characterized by having a road.

  According to the first aspect of the present invention, the front cover is positioned in the closed position with respect to the image forming apparatus main body by engaging the hook member of the lock mechanism with the engaging portion on the image forming apparatus main body side. The transport unit is positioned at the closed position with respect to the image forming apparatus main body by the shaft member integrated with the hook member of the lock mechanism. That is, the front cover and the transport unit are positioned at the closed position and the closed position by the hook member and the shaft member that are integral with each other with respect to the image forming apparatus main body, respectively. The transport unit can be positioned with high accuracy.

  According to the invention of claim 2, the shaft member on the front cover side is engaged with the engaging recess on the transport unit side, so that the relative positional accuracy between the front cover and the transport unit can be ensured with high accuracy. it can.

  According to the invention of claim 3, since the hook members are arranged at both ends in the left-right direction (longitudinal direction) of the shaft member, the closed position is obtained when the left end side and the right end side of the front cover or the transport unit are shifted. It can be prevented from being placed in the closed position.

  According to invention of Claim 4, the cam follower part (or cam follower part) formed in the shaft member by the side of the front cover moved toward a closed position is formed in the entrance of the engagement recessed part of a conveyance unit ( Or the cam member), the hook member is rotated in the direction of engagement with the locking member via the shaft member integral with the cam portion (or cam follower portion). Without providing, the hook member is smoothly engaged with the engagement member.

  According to the invention of claim 5, in the state where the front cover is disposed at the closed position and the conveyance unit is disposed at the closed position, the sheet conveyance path is configured between the front side of the image forming apparatus main body and the conveyance unit. In addition, a sheet reconveying path is formed between the conveying unit and the front cover, and high positional accuracy of the sheet conveying path and the sheet reconveying path can be ensured. For this reason, for example, a pair of conveyance rollers is arranged in the sheet conveyance path and the sheet re-conveyance path, and the pair of conveyance rollers is a pair of rollers that are separated from each other when the front cover is open and the conveyance unit is open. When configured, the front cover is arranged at the closed position, and the nip pressure at the conveyance nip of the conveyance roller pair when the conveyance unit is arranged at the closed position can be set to an appropriate magnitude. The sheet can be smoothly conveyed.

  Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. In addition, in each drawing, the member etc. which attached | subjected the same code | symbol are the same structures, The duplication description about these shall be abbreviate | omitted suitably. Moreover, in each drawing, members and the like that are not necessary for the description are omitted as appropriate.

<Embodiment 1>
An image forming apparatus 1 according to the present invention will be described with reference to FIGS. In FIGS. 1 to 3 and FIGS. 7 to 9, front, rear, left, right, upper and lower of the image forming apparatus 1 are indicated by arrows. 1 to 10, FIG. 1 is a perspective view of the entire image forming apparatus 1 as viewed from the upper left side of the front side thereof. FIG. 2 is a perspective view of the entire image forming apparatus 1 as viewed from the rear and obliquely upward on the left side. FIG. 3 is a diagram schematically showing the internal structure of the image forming apparatus 1 as viewed from the left side. 4 shows a perspective view of the front cover 3 removed from the state of FIG. However, the manual feed tray 16, which will be described later, is removed in FIG. 5A and 5B are schematic diagrams for explaining the front cover 3 and the transport unit 73. FIG. 5A shows the closed position A1 of the front cover 3 and the closed position B1 of the transport unit 73, and FIG. A position A2 and an open position B2 of the transport unit 73 are shown. 5A and 5B, the left side plate 76 and the right side plate 77 constituting a part of the main body frame 6 of the image forming apparatus main body 2 are illustrated by two-dot chain lines. The left side plate 76 covers the left side surface of the transport unit 73 and the front cover 3 described above, and the right side plate 77 is disposed so as to cover the right side surface of the transport unit 73 and the front cover 3. FIG. 6 is a diagram illustrating the position of the hook member 83 in a state where the front cover 3 is disposed at the open position A1 and the transport unit 73 is disposed at the open position. FIG. 7 is a perspective view illustrating the shaft member 82 on the front cover 3 side, the hook member 83, the cam follower portion 84, and the locking member 81 on the image forming apparatus main body 3 side of the lock mechanism 80. In the figure, members unnecessary for explanation are omitted as appropriate. FIG. 8 is a perspective view for explaining the engaging recess 87 and the cam portion 85 formed at the entrance thereof on the transport unit 73 side. FIG. 9 is a perspective view illustrating a state in which the shaft member 82 is engaged with the engaging recess 87. 10A, 10 </ b> B, and 10 </ b> C schematically show that the shaft member 82 is engaged with the engaging recess 87 and the hook member 83 is engaged with the locking member 81. FIG.

  Here, examples of the image forming apparatus 1 include a printer, a copier, a facsimile machine, and a multifunction machine of these. In the following description, a case where the image forming apparatus 1 is a printer will be described as an example. The image forming apparatus 1 shown in FIGS. 1 to 3 is a four-color full-color image forming apparatus 1 adopting an electrophotographic system, an intermediate transfer system, and a tandem system.

  With reference to FIGS. 1 and 2, the configuration of the entire image forming apparatus 1 as viewed from the outside will be described. The image forming apparatus 1 includes a substantially box-shaped (cuboid) image forming apparatus main body 2 and a front cover 3 supported by the image forming apparatus main body 2 so as to be freely opened and closed.

  The image forming apparatus main body 2 has a front surface covered with a front cover 3 and a left side surface and a right side surface covered with a left exterior panel 4 and a right exterior panel 5 made of synthetic resin. On the rear surface of the image forming apparatus main body 2, a part 7 of a sheet metal constituting the main body frame 6 is exposed as a structure. The upper surface of the image forming apparatus main body 2 is covered with a front cover 3 at the front, and is covered with a paper discharge tray 10 having a sheet stacking surface 8 that is raised from the middle to the rear.

  The front cover 3 is configured by the front exterior panel 11 and a part of a sheet conveying unit 24 described later that is configured on the inner side. The front exterior panel 11 includes a front panel 12, a rear upper panel 13 that continues from the upper end, and an inverted “L” -shaped left panel 14 and right panel 15. A rectangular manual feed tray 16 is disposed on the front panel 12. The manual feed tray 16 has a swing center on the lower end side, and forms a part of the front panel 12 at the closed position of the standing posture shown in FIG. In an open position (not shown) in a downwardly inclined posture, a sheet feeding table on which the sheet is placed is provided. An operation panel (operation unit) 17 is disposed on the upper panel 13. The operation panel 17 is arranged so as to be inclined substantially upward so that the rear end side is slightly higher so that an operator (for example, a user) who operates standing on the front side of the image forming apparatus 1 can easily see. A touch panel type liquid crystal display unit and various buttons are arranged on the operation panel 17, and the operator stands on the front of the image forming apparatus 1 and the entire image forming apparatus 1 is operated by the operation panel 17. It can be operated. The left panel 14 and the right panel 15 are disposed so as to cover a part of the sheet conveying unit 24 configured inside the front cover 3 from the left side and the right side, respectively.

  As will be described later, the front cover 3 is supported by the image forming apparatus main body 2 in a swingable manner at the lower end side, so that the entire front cover 3 can be opened and closed. As shown in FIG. 2, a release lever (release member) 74 with a button 75 that is operated when opening the front cover 3 is located at the upper end side and the rear end side inside (right side) of the left panel 14 and the right side. The panel 15 is disposed on the upper end side and on the inner side (left side) of the rear end side. The front cover 3 having the above-described configuration is opened when the operator pulls the front cover 3 toward the front side while pulling the button 75 forward from the front side of the image forming apparatus 1, thereby releasing the lock mechanism 80 described later. can do. As a result, it is possible to perform jam processing (operation for removing a sheet having a paper jam). Further, as will be described later, the paper feed cassette 25 in which a sheet to be subjected to image formation is accommodated can also be detached from the front side. As described above, the operator performs the entire operation of the image forming apparatus 1 using the operation panel 17, the jam processing when the jam occurs, the sheet replenishment to the sheet feeding cassette 25 when the sheet runs out, and the like. All can be performed from the front side of the image forming apparatus 1. The front cover 3 will be described in detail later.

  This is the end of the description of the configuration of the entire image forming apparatus 1 viewed from the outside.

  Next, the internal structure of the image forming apparatus 1 will be described with reference to FIG. The image forming apparatus 1 includes a sheet storage unit 20, a substrate storage unit 21, an image forming unit 22, a toner supply unit 23, and a paper discharge tray (sheet discharge unit) 10 in order from the lower side to the upper side of the image forming apparatus main body 2. Is provided. A sheet conveying unit 24 is provided between the front side of the image forming apparatus main body 2 and the front cover 3.

  A sheet cassette 25 is disposed in the sheet storage unit 20. The sheet feeding cassette 25 stores a plurality of sheets in a stacked state, and biases the leading end side (the right side in the figure) of the stacked sheets upward by a lift plate 26 disposed at the bottom. Yes. As a result, the uppermost sheet in the sheet feeding cassette 25 is fed by a pickup roller 27 of a sheet transport unit 24 described later, and further, the feeding roller 28 and the retard roller 30 prevent double feeding, and only one sheet is downstream. To the side. The paper feed cassette 25 can be inserted and removed from the front side (front side) of the image forming apparatus 1. A substrate storage unit 21 is disposed above the paper feed cassette 25.

  The substrate storage unit 21 is provided with a substrate and electrical components (not shown) that control the entire image forming apparatus 1. An image forming unit 22 is disposed above the substrate storage unit 21.

  The image forming unit 22 includes an intermediate transfer belt 31 and four (four color) image forming stations having the same configuration along the rotation direction (direction of arrow R31) of the intermediate transfer belt 31, that is, yellow (Y). An image forming station 32, a magenta (M) image forming station 33, a cyan (C) image forming station 34, and a black (Bk) image forming station 35 are provided. The yellow image forming station 32 includes a photosensitive drum 36, a charging device 37, an exposure device 38, a developing device 40, and a primary device which are arranged around the photosensitive drum 36 in the order of rotation (arrow direction). A transfer roller 41, a drum cleaner 42, and the like are included. The photosensitive drum 36 is driven to rotate in the direction of the arrow at a predetermined process speed. The surface (outer peripheral surface) of the photosensitive drum 36 is uniformly (uniformly) charged to a predetermined polarity / potential by the charging device 37 and then exposed based on image information sent from a personal computer (not shown) or the like. By the exposure of 38, the electric charge in the exposed portion is removed and an electrostatic latent image is formed. The electrostatic latent image is developed as a toner image with the toner in the developer attached thereto by the developing device 40. In the present embodiment, a two-component developer mainly composed of toner and carrier is used as the developer.

  The toner image formed on the surface of the photosensitive drum 36 as described above is transferred to the intermediate transfer belt 31. The intermediate transfer belt 31 is stretched around a driving roller 43 and a driven roller 44, and rotates in the direction of arrow R31 by the rotation of the driving roller 43 in the direction of the arrow. The yellow toner image formed on the photosensitive drum 36 is primarily transferred onto the intermediate transfer belt 31 by the primary transfer roller 41 in the primary transfer portion T1. The toner (primary transfer residual toner) remaining on the surface of the photosensitive drum 36 after the primary transfer of the toner image is removed by the drum cleaner 42.

  The remaining three color (cyan, magenta, and black) image forming stations 33, 34, and 35 have the same configuration as the above-described yellow image forming station 32, and the photosensitive drums 36 of these image forming stations 33, 34, and 35 are provided. Similarly, cyan, magenta, and black toner images are formed on the surface of the toner image and sequentially transferred onto the intermediate transfer belt 31. Thus, the four color toner images are superimposed on the intermediate transfer belt 31. The four-color toner images on the intermediate transfer belt 31 are secondarily transferred collectively to a sheet conveyed by a sheet conveying unit 24 described later by a secondary transfer roller 45 in a secondary transfer unit T2. Toner remaining on the surface of the intermediate transfer belt 31 after the secondary transfer of the toner image (secondary transfer residual toner) is removed by a belt cleaner 46 disposed in the vicinity of the driven roller 44. A toner replenishing unit 23 is provided above the image forming unit 22.

  The toner replenishing unit 23 is provided with four toner containers 47, 48, 50, and 51 for yellow, magenta, cyan, and black, which individually store toner of each color. The developing devices 40 of the color image forming stations 32 to 35 described above are provided with a remaining amount sensor (not shown) for detecting the remaining amount of the developer. When it is detected that the amount of the developer is less than a predetermined value, toner is supplied to the developing device 40 of each color from the toner containers 47, 48, 50, 51 of each color. A paper discharge tray 10 is provided above the toner supply unit 23.

  The paper discharge tray 10 is formed so as to cover the upper surface of the image forming apparatus main body 2, and the intermediate portion in the front-rear direction is inclined so that the rear end side is positioned upward, and the rear end side is the intermediate portion. It is formed flat so as to be continuous. On the sheet stacking surface 8 on the upper surface of the sheet discharge tray 10, sheets discharged backward from a sheet discharge port 55 of a sheet conveying unit 24 described below are stacked.

  In the present embodiment, the sheet conveyance unit 24 is provided between the front side of the image forming apparatus main body 2 and the front cover 3, and a sheet conveyance path 52 that guides a sheet from below to above, and the sheet conveyance unit. It has a sheet re-conveying path 53 that is disposed on the front side of the path 52 and guides the sheet from the upper side to the lower side, and further has a manual feeding unit 54. In the present embodiment, the sheet re-conveying path 53 is a sheet conveying path that is directly opened by opening the front cover 3 described later. On the other hand, the sheet conveyance path 52 is a sheet conveyance path that is indirectly opened through a conveyance unit 73 described later when the front cover 3 is opened.

  The sheet conveyance path 52 rises upward from the vicinity of the above-described feeding roller 28, extends upward while gently curving backward, and extends upward in the vicinity of the intermediate transfer belt 31 by changing the bending direction to the front. The sheet extends obliquely upward toward the rear and reaches the sheet discharge port 55. The sheet conveyance path 52 includes a rear guide 52a and a front guide 52b facing each other, and a part of the front guide 52b is formed in a conveyance unit 73 described later. In the sheet conveyance path 52, the pickup roller 27, the feeding roller 28, the retard roller 30, the conveyance roller pair 56, the registration roller pair 57, and the intermediate transfer belt 31 are sandwiched between the driving roller 43 in this order from the bottom. A secondary transfer roller 45, a fixing device (fixing unit) 58, a conveyance roller pair 60, a switching flapper 61, a paper discharge roller pair 62, and the like are provided. The above-described fixing device 58 includes a fixing roller (fixing member) 63 having a built-in heater (not shown), and a pressure roller (pressure member) 64 that forms a fixing nip N in pressure contact therewith.

  The sheet fed by the pickup roller 27, the feeding roller 28, and the retard roller 30 from the sheet feeding cassette 25 is conveyed by the conveying roller pair 56 and the registration roller pair 57, and is transferred to the secondary transfer portion T2. The four color toner images on the intermediate transfer belt 31 are secondarily transferred at once and heated and pressurized when passing through the fixing nip N to fix the toner images on the surface. The sheet on which the toner image has been fixed is guided to the lower surface of the switching flapper 61 by the conveying roller pair 60 and conveyed to the paper discharge roller pair 62, and the sheet discharge roller pair 62 moves rearward from the sheet discharge port 55 facing the back side. The sheet is discharged and stacked on the sheet stacking surface 8 of the sheet discharge tray 10. In the figure, the sensor flag 65 of the paper discharge sensor disposed immediately downstream of the paper discharge roller pair 62 is operating with the sheet P being discharged.

  The sheet re-conveying path 53 extends obliquely from the upper side to the front side of the above-described sheet discharge port 55, and gently slopes and extends to the rear side with a steep slope, and protrudes downward at the lower end portion. Then, the sheet merges with the sheet conveyance path 52 described above. The sheet re-conveying path 53 includes a rear guide 53a and a front guide (guide portion) 53b that face each other. A part of the rear guide 53a is formed in a transport unit 73 described later. Further, most of the front guide 53 b is incorporated inside (rear end side) of the front exterior panel 11 and constitutes the front cover 3 together with the front exterior panel 11. In the sheet re-conveying path 53, the reverse roller pair 66, the switching flapper 61, the first, second, third and fourth re-conveying roller pairs 67, 68, 70 and 71 are arranged.

  When images are formed on both sides of the sheet, the switching flapper 61 is switched to the position indicated by the two-dot chain line, and the sheet on which the toner image is fixed is conveyed to the conveying roller pair 60 and the switching flapper 61 It is conveyed along the upper surface and further conveyed rearward by the reverse roller pair 66. Then, the rear end of the sheet passes through the conveying roller pair 60, and the reverse roller pair 66 is reversely rotated before passing through the reverse roller pair 66, and the first to fourth re-conveying roller pairs 67, 68, 70, 71 The sheet is conveyed downward and conveyed to the sheet conveyance path 52. Then, the toner image is transferred and fixed on the rear surface of the sheet in the same manner as on the front surface, and is discharged rearward from the sheet discharge port 55 and stacked on the sheet stacking surface 8 of the discharge tray 10. The Note that a manual feed roller 72 is disposed immediately in front of the conveyance roller pair 56 in the sheet conveyance unit 24, and the manual feed tray 16 constituting a part of the front cover 3 is pulled out in the closed state. The sheet set on the manual feed tray 16 is fed toward the conveying roller pair 56 side.

  A part of the sheet conveying unit 24 described above constitutes a conveying unit 73 that can be opened and closed. The transport unit 73 is disposed between the sheet transport path 52 and the sheet re-transport path 53, and a part of the front guide 52 b in the sheet transport path 52 and a part of the rear guide 53 a in the sheet re-transport path 53. And the first roller 57a of the registration roller pair 57, the secondary transfer roller 45, and the first and second rollers 70a and 71a of the third and fourth re-conveying roller pairs 70 and 71, respectively. Yes. The transport unit 73 has a swing center on the lower end side and is supported by the image forming apparatus body 2 so as to be freely opened and closed. As will be described later, the upper end side of the transport unit 73 is opened to the front side by opening the front cover 3, and a part of the sheet transport path 52 and a part of the sheet re-transport path 53 are opened. ing.

  This completes the description of the internal structure of the image forming apparatus 1.

  Next, the front cover 3 will be described with reference to FIGS.

  As shown in FIG. 4, the front cover 3 has a swing center 78 at the lower end, and the swing center 78 is supported by the image forming apparatus body 2 so as to be swingable. As shown in FIGS. 5A and 5B, the image forming apparatus main body 2 extends the left side plate 76 and the right side plate 77 of the main body frame 6 made of a sheet metal to the front side and extends the front cover 3. A part of the left side surface and the right side surface and the left side surface and the right side surface of the transport unit 73 are covered. A shaft 79 is projected from the lower end of the left side plate 76 and the right side plate 77 on the front end side, and the swing center 78 of the front cover 3 is swingably supported by the shaft 79. Thereby, the front cover 3 can take the closed position A1 shown to Fig.5 (a), and the open position A2 shown to FIG.5 (b). The above-described transport unit 73 also has a swing center (not shown) on the lower end side, and swings by a shaft (not shown) protruding from the left side plate 76 and the right side plate 77 on the image forming apparatus main body 2 side. It is supported freely. Thereby, the conveyance unit 73 can take the closed position B1 shown to Fig.5 (a), and the open position B2 shown to FIG.5 (b).

  In the present embodiment, the transport unit 73 is not required to be actively opened and closed by the operator, and is opened and closed in conjunction with the opening and closing operation of the front cover 3. That is, an operator is positioned on the front side of the image forming apparatus 1 and pulls the button 75 of the operation lever 74 (see FIG. 2) toward the front side, thereby fixing the front cover 3 to the image forming apparatus main body 2. A hook member 83 (see FIG. 7) described later is released, and the front cover 3 can be opened. When the front cover 3 is opened in the direction of arrow R3a in FIG. 5A, the transport unit 73 is also opened accordingly. On the other hand, when the front cover 3 is closed in the direction of arrow R3b in FIG. 5B and a hook member 83 described later is engaged with the image forming apparatus main body 2, the transport unit 73 is also closed. Note that the front cover 3 and the transport unit 73 are appropriately adjusted as shown in FIG. 5B by a regulating member (not shown) such as a stopper, a string-like member, or a spring provided between the image forming apparatus main body 2. These are held at the open position A2 and the open position B2 in the inclined posture. When the front cover 3 and the conveyance unit 73 are opened, the sheet conveyance path 52 and the sheet re-conveyance path 53 are largely opened, so that the jammed paper can be easily removed.

  In the present invention, a lock mechanism 80 is interposed between the image forming apparatus main body 2 and the front cover 3, and the front cover 3 and the conveyance unit 73 are positioned with respect to the image forming apparatus main body 2 by the lock mechanism 80. Like to do. Hereinafter, this point will be described in detail with reference to FIGS. Note that, as described above, in FIGS. 7 to 10, members unnecessary for explanation are omitted as appropriate.

  In this embodiment, as shown in FIG. 7, the lock mechanism 80 includes a locking member 81 provided on the image forming apparatus main body 2 side, a shaft member 82 provided on the front cover 3 side, a hook member 83, and As shown in FIGS. 8 and 9, the cam follower portion 84 and a cam portion 85 provided on the transport unit 73 side are provided. Of the above-described components of the lock mechanism 80, components other than the shaft member 82 are disposed on both the left end side and the right end side of the image forming apparatus main body 2, but these are the same configuration. Only the right end side will be described below, and the description of the left end side will be omitted.

  The locking member 81 is configured to protrude inward from a right side wall 77 constituting a part of the main body frame 6. As shown in FIGS. 5A and 5B, the right side wall 77 is disposed so as to substantially cover the right end side of the front cover 3 and the transport unit 73. The lower end of the locking member 81 is configured by a curved surface 81a so that an engaging portion 83a of a hook member 83 engaged from below is easily engaged as will be described later. The locking member 81 is provided on the image forming apparatus main body 2 side as described above, and serves as a reference when positioning the front cover 3.

  The shaft member 82, the hook member 83, and the cam follower portion 84 are integrally configured in the present embodiment. Of these, the shaft member 82 is disposed in the left-right direction, and both ends thereof are rotatably supported by the front cover 3. As will be described later, when the front cover 3 disposed at the open position A2 is closed, the transport unit 73 is pushed by the front cover 3, but the closed position A1 of the front cover 3 (the closed position B1 of the transport unit 73). In the vicinity of), the above-described shaft member 82 directly pushes the transport unit 73 and finally positions it.

  The hook member 83 is provided on the right end side of the shaft member 82 so as to face substantially rearward. A concave engaging portion 83a that opens upward is formed at the upper part of the rear end side of the hook member 83. As will be described later, the engaging portion 83a is engaged and disengaged with respect to the locking member 81 from below substantially by the rotation of the shaft member 82.

  The cam follower portion 84 is formed slightly inside the shaft member 82 from the hook member 83 described above. The cam follower portion 84 is formed with a planar copying surface 84 a formed by cutting out a part of the outer peripheral surface 82 a of the cylindrical shaft member 82. The copying surface 84a moves following a cam portion 85 described later. As shown in FIG. 9, a notch 86 having the same shape as the cam follower portion 84 is formed on the opposite side of the cam follower portion 84, that is, at a position rotated 180 degrees in the circumferential direction of the shaft member 82. When the shaft member 82 is engaged with an engagement recess 87 described later, the notch 86 is guided by lower portions facing each other in the opening.

  The shaft member 82, the hook member 83, and the cam follower portion 84 described above are integrally configured, and the shaft member 82 is rotatably supported by the front cover 3 as described above. Therefore, when a force is applied to the cam follower portion, the shaft member 82 is rotated by this force, and the hook member 83 swings as the shaft member 82 rotates.

As shown in FIGS. 8 and 9, the cam portion 85 is formed at the entrance of the engaging recess 87 of the transport unit 73. The engaging recess 87 is formed in a circular shape having an opening 88. An inner diameter L1 of the engaging recess 87 is set to be slightly larger than an outer diameter L2 of the shaft member L2 (see FIG. 7). The opening 88 is configured between a cam portion 85 formed on the upper side and a convex guide portion 90 disposed on the lower side and facing the cam portion 85. The positions where the cam portion 85 and the guide portion 90 are formed in the left-right direction, that is, the positions along the longitudinal direction of the shaft member 82 are formed at positions corresponding to the cam follower portion 84 and the notch 86 described above. The cam portion 85 is formed in a flat shape whose front end side is highly inclined, and the width dimension L3 between the cam portion 85 and the guide portion 90 is larger than the inner diameter L1 of the engaging recess 87 and the outer diameter L2 of the shaft member 82. Is set to be slightly larger than the width dimension L4 of the cam follower portion 84 and the notch 86 in the shaft member 82 shown in FIG. Here, when arranging the magnitude relationship of L1 to L4, the inner diameter L1 of the engaging recess 87, the outer diameter L2 of the shaft member 82, the width dimension L3 of the opening 88, and the width dimension L4 of the cam follower section 84 and the notch 86 are arranged in descending order. It becomes. That is, L1 <L2 <L3 <L4. Since such a dimensional relationship is set, as will be described later, when the shaft member 82 is engaged with the engagement recess 87, the inclination direction of the cam follower portion 84 and the inclination direction of the cam portion 85 are Can be engaged with the engaging recess 87 through the opening 88 only when they match, and when rotated during or after the engagement, the inclination direction of the cam follower 84 and the inclination of the cam 85 Since the direction is shifted, it does not fall off from the engaging recess 87. A convex portion 91 is formed at the boundary between the engaging concave portion 87 and the cam portion 85, and the shaft member 82 at the time of engagement engages the hook member 83 by the convex portion 91 as will be described later. It is made to rotate in the direction of engagement with the stop portion 81. Another engaging recess 92 is formed on the left side of the engaging recess 87 along the left-right direction. The engaging recess 92 is formed in a substantially semicircular shape, and a guide portion 93 that is inclined in the same direction as the cam portion 85 is provided on the upper end side. The guide portion 93 guides the outer peripheral surface of the shaft member 82 when engaged. See FIGS. 5A, 5B, 6, and 10A, 10B, 10C. The operation of the locking mechanism 80 described above, particularly the operation of engaging the hook member 83 with the locking member 81 will be described.

  As shown in FIG. 5B, in the state where the front cover 3 is disposed at the open position A2 and the transport unit 73 is disposed at the open position B2, the sheet transport path 52 and the sheet re-transport path 53 are opened. . For this reason, jammed paper in the sheet conveyance path 52 or the sheet re-conveyance path 53 can be easily found and removed. After removing the jammed paper, the front cover 3 that has been in the open position A2 is moved in the direction of arrow R3b toward the closed position A1 as shown in FIG. 5B. The front cover 3 pushes up the transport unit 73 that was in the open position B2 during the closing operation. That is, as shown in FIG. 6, the abutting portion 94 on the front cover 3 side abuts on the abutting portion 95 on the conveying unit 73 side and pushes it up so that it is lifted from below, so Is moved toward the closed position B1. When the front cover 3 approaches the closed position A1 and the transport unit 73 approaches the closed position B1, the front cover 3 side and the transport unit 73 side contact portions 94 and 95 that have been in contact with the front cover 3 change to FIG. As shown in FIG. 10A, the cam follower portion 84 of the shaft member 82 on the front cover 3 side and the cam portion 85 at the entrance of the engaging recess 87 on the transport unit 73 side come into contact with each other. When the front cover 3 further moves toward the closed position A1 in this state, the shaft member 82 moves so that the cam follower portion 84 is guided by the cam portion 85, and the cam follower portion 84 and the notch 86 are opened. Pass through. When the cam follower portion 84 passes through the convex portion 91 at the boundary between the cam portion 85 and the engaging concave portion 87, the cam follower portion 84 is inclined with respect to the convex portion 91 as shown in FIG. A moment in the direction of the arrow R82 acts on the member 82. Due to this moment, a moment in the direction of arrow R 83, that is, the direction of engagement with the locking member 81 acts on the hook member 83 integrated with the shaft member 82. Then, as shown in FIG. 10C, the engaging portion 83 a of the hook member 83 is engaged with the locking member 81 almost simultaneously with the engagement of the shaft member 82 with the engaging recess 87.

  Since the shaft member 82 engaged with the engagement recess 87 as described above is engaged with the cam follower portion 84 and the notch 86 slightly rotated with respect to the angle at which the cam follower portion 84 and the notch 86 can pass through the opening portion 88. Unless the shaft member 82 is rotated from the outside and the directions of the cam follower portion 84 and the notch 86 and the opening portion 88 are matched, the shaft member 82 will not fall out of the engaging recess 87. That is, the engagement state (lock state) of the hook member 83 with respect to the locking member 81 is not released.

  As described above, the front cover 3 is positioned at the closed position A1 with respect to the image forming apparatus main body 2, and the transport unit 73 is positioned at the closed position B1. In order to release the engaged state (locked state) of the hook member 83 with respect to the locking member 81, the button 75 of the front cover 3 is pulled toward the front side as described above. As a result, the hook member 83 is rotated in a release direction opposite to the engagement direction via a connecting member (not shown), the engagement of the hook member 83 is released, and the front cover 3 can be opened. The hook member 83 released from the engagement is held at the engagement release position shown in FIG. 10A by a restricting member (not shown) such as a stopper.

  According to the image forming apparatus 1 described above, the hook member 83 that positions the front cover 3 with respect to the image forming apparatus body 2 and the shaft member 82 that positions the transport unit 73 with respect to the image forming apparatus body 2 are integrated. Since it is configured, the positioning accuracy of the front cover 3 and the transport unit 73 with respect to the image forming apparatus main body 2 can be increased. As a result, the nip pressure in the registration roller pair 57, the drive roller 43 and the secondary transfer roller 45, and the re-conveying roller pair 70 and 71 shown in FIG. Can be conveyed. Further, the locking member 81 on the image forming apparatus main body 2 side serving as the positioning reference for the front cover 3 and the shaft member 82 serving as the positioning reference for the transport unit 73 are connected to the closed position A1 of the front cover 3 and the transport unit 73 closed. At the position B1, the image forming apparatus main body is located at substantially the same height, or on a circumference with a radius from the center of the front member 3 to the center of the shaft member 82 as a reference. Since the two-side locking member 81 is substantially located, this also increases the positioning accuracy. Furthermore, in this embodiment, since the cam follower portion 84 is provided on the shaft member 82 and the cam portion 85 is provided on the transport unit 73, the front cover 3 is moved from the open position A2 toward the closed position A1, and the shaft member 82 is moved. Slightly before engaging the engaging recess 87, the cam follower portion 84 and the cam portion 85 exert a moment on the shaft member 82 to rotate the hook member 83 in the engaging direction. Since the engaging portion 83a is engaged with the locking member 81, a biasing member such as a tension spring that biases the hook member 83 in the engaging direction is actively omitted, and the configuration is simplified accordingly. be able to.

  In the above embodiment, an example in which the cam follower portion 84 is provided on the shaft member 82 side and the cam portion 85 is provided on the conveyance unit 73 side has been described. Conversely, the cam portion is provided on the shaft member 82 side, and the conveyance unit 73 is provided. You may make it provide a cam follower part in the side. That is, the closing operation of the front cover 3 causes the cam follower portion disposed on one of the front cover 3 and the transport unit 73 and the cam portion disposed on the other to abut against each other and move relative to each other. As long as a moment that rotates the hook member 83 in the engaging direction can be generated with respect to the member 82, the cam follower portion and the cam portion may be arranged in either the front cover 3 or the transport unit 73. Good.

  In the above description, the case where the front cover 3 and the conveyance unit 73 are disposed on the front side of the image forming apparatus main body has been described as an example. However, the present invention is not limited to this and the same cover is used. The present invention can be similarly applied to the case where the conveyance unit is disposed on the left side, the right side, or the rear side of the image forming apparatus main body 2, and when applied, the same effect can be achieved. .

  In the above description, the case where the present invention is applied to the front cover and the transport unit of the image forming apparatus has been described. However, the present invention generally includes an inner cover and an outer cover on the side surface of the apparatus main body, The present invention can be applied to the case where the inner cover is opened and closed in conjunction with the opening and closing operation of the outer cover.

FIG. 2 is a perspective view of the entire image forming apparatus as viewed from the diagonally upper left side on the front side. FIG. 2 is a perspective view of the entire image forming apparatus as viewed from the rear and obliquely upward on the left side thereof. FIG. 2 is a diagram schematically showing an internal structure of the image forming apparatus as viewed from the left side. It is a perspective view of the front cover of the state removed from the state of FIG. It is a schematic diagram explaining a front cover and a conveyance unit, (a) shows the closed position of a front cover and the closed position of a conveyance unit, (b) is a figure which shows the open position of a front cover, and the open position of a conveyance unit. is there. It is a figure explaining the position of a hook member in the state where a front cover is arranged in an open position, and a conveyance unit is arranged in an open position. 4 is a perspective view illustrating a shaft member, a hook member, a cam follower portion on the front cover side, and a locking member on the image forming apparatus main body 3 side in the lock mechanism. FIG. It is a perspective view explaining the engaging recessed part by the side of the conveyance unit 3, and the cam part formed in the entrance. It is a perspective view explaining the state by which the shaft member was engaged with the engagement recessed part. (A), (b), (c) is an operation explanatory view schematically showing how the shaft member is engaged with the engaging recess and the hook member is engaged with the locking member. It is.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Image forming apparatus main body, 3 ... Front cover, 22 ... Image forming part, 24 ... Sheet conveyance part, 52 ... Sheet conveyance path, 53 ... Sheet re-conveyance path, 73: Conveying unit, 78: Center of swing of front cover, 80 ... Lock mechanism, 81 ... Locking member, 82 ... Shaft member, 83 ... Hook member, 84 ... Cam follower, 85 ... Cam portion, 87... Engaging recess, 88... Opening portion, A1... Closed position, A2... Open position, B1... Closed position, B2.

Claims (5)

An image forming apparatus comprising: a sheet conveying unit that conveys a sheet; and an image forming unit that forms a toner image on the sheet conveyed by the sheet conveying unit.
An image forming apparatus main body provided with the image forming unit;
The lower end side is swingably supported by the image forming apparatus main body, and can be opened and closed in a closed position that covers the front side of the image forming apparatus main body and an open position that opens the front side of the image forming apparatus main body. A front cover,
The lower end side is swingably supported by the image forming apparatus main body, and is sandwiched between the front cover arranged at the closed position and the front side of the image forming apparatus main body to constitute the sheet conveying unit A transport unit that takes a closed position to be opened, and an open position to open the sheet transport unit when the front cover is opened;
A locking mechanism interposed between the image forming apparatus main body and the front cover,
The locking mechanism includes a locking member disposed on the image forming apparatus main body side,
A shaft member disposed on the front cover side in the left-right direction, and when the front cover is moved from the open position to the closed position, the shaft member presses the transport unit and is positioned at the closed position.
A hook member configured integrally with the shaft member and detachable from the locking member and positioning the front cover at the closed position when engaged.
An image forming apparatus. The transport unit has an engagement recess for positioning the transport unit at the closed position by engaging the shaft member on the front cover side disposed at the closed position.
The image forming apparatus according to claim 1. The hook members are respectively disposed on the left and right ends of the shaft member,
The locking member is disposed at a position corresponding to each hook member on the image forming apparatus main body side.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The lock mechanism includes a cam portion formed on one of the entrance of the engagement recess on the transport unit side and the shaft member, and a cam follower portion formed on the other,
When the front cover is moved from the open position toward the closed position, the cam part and the cam follower part contact the cam part and the cam follower part to move relative to each other. The hook member is formed in a shape that rotates in the engagement direction via
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The sheet transport unit includes a sheet transport path configured between the transport unit disposed at the closed position and a front side of the image forming apparatus main body, the transport unit disposed at the closed position, and the front surface. A sheet re-conveying path configured between the cover and guiding the image-formed sheet to the image forming unit again.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

Images