JP6311637B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that forms an image on a recording medium (for example, paper).

  In a conventional image forming apparatus, a cover is disposed so as to be openable and closable with respect to the apparatus main body, and a transport unit is disposed inside the cover (for example, Patent Document 1). In such a conventional image forming apparatus, a locking portion and a pressing portion are provided on both the left and right sides of the inner surface of the cover. The locking portion positions and locks the cover to the apparatus main body. The pressing unit presses and fixes the transport unit to the apparatus main body in a closed state of the cover with respect to the apparatus main body. The cover receives a tensile force pulled from the apparatus main body via the locking portion, and also receives a pressing force pressed from the transport unit via the pressing portion.

JP-A-8-202095

  However, in such a conventional image forming apparatus, the pressing portion does not overlap with the virtual straight line passing through the positions of the locking portions on both the left and right sides, so that the tensile force and the pressing force described above are viewed from the left and right sides of the cover. The distance between the action lines of the force increases, and the moment of force due to each force increases. As a result, the cover is distorted, and the fit between the cover and the apparatus main body is lowered.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an image forming apparatus that suppresses distortion of a cover by a force that the cover receives from the apparatus main body and the transport unit when the cover is closed with respect to the apparatus main body. There is to do.

  An image forming apparatus according to the present invention includes an apparatus main body, an image forming unit, a transport unit, a cover, a pair of locking units, and a pressing unit. The image forming unit forms an image on the conveyed paper. The transport unit is disposed in the apparatus main body and constitutes a part of a paper transport path for transporting the paper. The cover is arranged to be openable and closable with respect to the apparatus main body, and presses the transport unit in a closed state with respect to the apparatus main body. The locking portion is provided on the inner surface of the cover. The pressing portion is provided on the inner surface of the cover. The pair of locking portions are locked to the apparatus main body when the cover is closed with respect to the apparatus main body. The pressing portion includes a pressing area that presses the transport unit in a closed state of the cover with respect to the apparatus main body. In a plan view with respect to the inner surface, the pressing region overlaps an imaginary straight line that passes through each position of the pair of locking portions.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a cover is distorted by the force which a cover receives from an apparatus main body and a conveyance unit in the closed state with respect to an apparatus main body.

1 is a cross-sectional view schematically showing a cross section of an image forming apparatus according to an embodiment of the present invention. It is the perspective view which showed the open state of the cover with respect to a housing | casing. It is a perspective view of the cover with which a conveyance unit is arranged. It is a top view of the cover by which the conveyance unit is arrange | positioned. It is the perspective view which showed the inner surface side of the cover single-piece | unit. It is the side view which showed the latching | locking part provided in the inner surface of the cover. It is the perspective view which showed the latching | locking part provided in the inner surface of the cover. It is sectional drawing which showed the projection part provided in the inner surface of the cover. It is a perspective view of a conveyance unit simple substance. It is the side view which looked at the to-be-pressed part from the arrow Y7 direction of FIG. It is the perspective view which showed the state which the press part of the right side of the cover and the pressed part on the same side of the conveyance unit contact | abutted. It is the perspective view which showed the state which the press part of the left side of a cover and the pressed part of the same side of a conveyance unit contact | abutted.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof is not repeated.
<Description of configuration>
The image forming apparatus according to the present embodiment will be described with reference to FIGS. FIG. 1 is a cross-sectional view schematically showing a cross section of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a perspective view showing an open state of a cover with respect to a housing. In FIG. 2, the exterior panel attached to the outer surface of the housing is omitted for the sake of drawing.

  As shown in FIG. 1, an image forming apparatus 1 according to the present embodiment is an apparatus that forms an image on a sheet P, and includes a housing (apparatus main body) 3, an image forming unit 5, a fixing unit 7, and the like. , A paper feed cassette 9 and a paper discharge tray 11 are provided. The paper feed cassette 9 is disposed at the lower part of the housing 3, and the image forming unit 5 is disposed above the paper feed cassette 9 in the housing 3. The paper discharge tray 11 is disposed on the upper side of the image forming unit 5 and in the in-cylinder space of the upper side of the housing 3, and the fixing unit 7 is disposed on the side of the image forming unit 5 in the housing 3. Is done.

  As shown in FIG. 2, the housing | casing 3 is formed in the box shape of a bottom face rectangle, and has the four side walls 31, 32, 33, 34 as a surrounding wall. In this embodiment, for convenience of explanation, the side wall 31 is a front wall, the side wall 32 opposite to the front wall is a rear wall, the side wall 33 is a right wall, and the side wall 34 is a left wall. Hereinafter, the front wall 31, the rear wall 32, the right wall 33, and the left wall 34 are also described.

  In the present embodiment, as shown in FIG. 2, the front wall 31 side is the front side, the rear wall 32 side is the rear side, the right wall 33 side is the right side, and the left wall 34 is the image forming apparatus 1. The side is the left side. Under this front / rear / left / right setting, the fixing unit 7 is disposed on the rear side of the image forming unit 5.

  The image forming unit 5 forms a toner image on the paper P supplied from the paper feed cassette 9. The image forming unit 5 includes an image forming unit 51, an intermediate transfer belt 52, and a secondary transfer roller 53.

  The intermediate transfer belt 52 has an endless belt shape. The intermediate transfer belt 52 is stretched and supported by a driving roller 52a and a driven roller 52b, and is rotated by the rotational driving of the driving roller 52a.

  The image forming units 51 are respectively arranged corresponding to toners of a plurality of colors (for example, cyan, magenta, yellow, and black). Each image forming unit 51 forms a toner image of each color on the surface of the intermediate transfer belt 52. Each image forming unit 51 includes a photosensitive drum 51a, a charging device 51b, an exposure device 51c, a developing device 51d, a toner container 51e, a primary transfer roller 51f, and a cleaning device 51g.

  The photosensitive drum 51a has a photosensitive layer on its surface. The charging device 51b uniformly charges the surface of the photosensitive drum 51a to a predetermined potential. The exposure device 51c irradiates the charged surface of the photosensitive drum 51a with laser light based on the image information, and forms an electrostatic latent image corresponding to the image information on the surface. The toner container 51e supplies the corresponding color toner to the developing device 51d. The developing device 51d develops the electrostatic latent image formed on the surface of the photosensitive drum 51a as a toner image.

  The primary transfer roller 51 f transfers the toner image on the surface of the photosensitive drum 51 a to the surface of the intermediate transfer belt 52. The primary transfer roller 51f is supported so as to press the photosensitive drum 51a via the intermediate transfer belt 52. A primary transfer voltage is applied to the surface of the primary transfer roller 51f. Thus, when the toner image on the surface of the photosensitive drum 51a is pressed against the intermediate transfer belt 52, the toner image on the surface of the photosensitive drum 51a is transferred to the intermediate transfer belt 52 by the electrostatic attraction of the primary transfer roller 51f. Is done. The cleaning device 51g removes residual toner on the surface of the photosensitive drum 51a after the transfer.

  In this way, the image forming unit 51 corresponding to each color forms a toner image of each color on the surface of the intermediate transfer belt 52 that moves around. The toner images of each color are superimposed. As a result, a color toner image is formed on the surface of the intermediate transfer belt 52. This color toner image is conveyed to the secondary transfer roller 53 by the circular movement of the intermediate transfer belt 52.

  The secondary transfer roller 53 transfers the color toner image on the surface of the intermediate transfer belt 52 to the paper P. The secondary transfer roller 53 is supported so as to press the drive roller 52 a via the intermediate transfer belt 52. A secondary transfer voltage is applied to the secondary transfer roller 53. The sheet P passes through the secondary transfer nip area in accordance with the timing when the color toner image on the intermediate transfer belt 52 passes through the pressure contact area (secondary transfer nip area) between the driving roller 52a and the secondary transfer roller 53. After passing, the color toner image on the intermediate transfer belt 52 is transferred onto the paper P by the secondary transfer voltage applied to the secondary transfer roller 53.

  The fixing unit 7 fixes the toner image transferred onto the paper P. The fixing unit 7 includes a pressure roller 7a and a fixing roller 7b. The fixing roller 7b has a heat source for heating the paper P. The pressure roller 7a and the fixing roller 7b are pressed against each other. When the paper P to which the toner image has been transferred passes through the pressure contact region (fixing nip region) between the pressure roller 7a and the fixing roller 7b, the toner image is fixed to the paper P by heating by the fixing roller 7b. In this way, the image forming unit 5 forms a toner image on the paper P.

  The paper feed cassette 9 stacks and stores a plurality of sheets of paper P. The paper P in the paper feed cassette 9 passes through the paper transport path L1 and is sequentially discharged to the paper discharge tray 11 through the secondary transfer nip area and the fixing nip area.

  The sheet conveyance path L1 is formed from the sheet feeding cassette 9 to the inside of the rear wall 32 of the housing 3 upward and to the sheet discharge tray 11 through the secondary transfer nip area and the fixing nip area in order. Is done.

  A pickup roller 13 is disposed in the housing 3 in the vicinity of the paper feed cassette 9. In addition, a paper feed roller pair 15, a transport roller pair 17, and a registration roller pair 19 are arranged in this order from the upstream side in the paper transport direction in the paper transport path L1. The paper feed roller pair 15, the transport roller pair 17, and the registration roller pair 19 are disposed between the pickup roller 13 and the secondary transfer roller 53.

  The pickup roller 13 takes out a plurality of sheets P in the sheet feeding cassette 9 one by one in order from the top. When the pickup roller 13 picks up a plurality of sheets P, the pair of sheet feed rollers 15 conveys only the top sheet P of the plurality of sheets to the conveyance roller pair 17 and the rest to the sheet feed cassette 9. return. The transport roller pair 17 transports the paper P from the paper feed roller pair 15 to the registration roller pair 19. The registration roller pair 19 controls the timing at which the paper P from the conveyance roller pair 17 is sent to the secondary transfer nip region between the drive roller 52 a and the secondary transfer roller 53.

  The paper feed roller pair 15 includes a paper feed roller 15a and a retard roller 15b. The conveyance roller pair 17 includes a conveyance roller 17a and an intermediate roller 17b. The registration roller pair 19 includes a registration roller 19a and a registration driven roller 19b.

  The casing 3 is provided with a reverse conveyance path (paper conveyance path) L2 for reversing the front and back of the paper P. As shown in FIG. 1, the reverse conveyance path L2 branches from a branch point B on the downstream side in the conveyance direction of the fixing unit 7 in the paper conveyance path L1, passes between the paper conveyance path L1 and the rear wall 32, It joins the merging point G1 on the upstream side in the transport direction of the transport roller pair 17 in the paper transport path L1. A plurality (for example, four) of transport roller pairs 40, 41, 42, and 43 are disposed on the reverse transport path L2 at intervals.

  When the paper P that has passed through the fixing unit 7 is moved backward and is carried into the reverse conveyance path L2 from the branch point B and returned to the paper conveyance path L1 from the junction G1 through the reverse conveyance path L2, the front and back are reversed. Yes. Then, the paper P that has been turned upside down is transported along the paper transport path L1, and an image is formed on the back surface thereof as described above.

  In addition, the image forming apparatus 1 includes a cover 23 and a transport unit 25. First, the cover 23 will be described with reference to FIGS. 3 is a perspective view of the cover on which the transport unit is disposed, FIG. 4 is a plan view of the cover on which the transport unit is disposed, and FIG. 5 is a perspective view showing the inner surface side of the cover alone. .

  As shown in FIGS. 1 and 2, the cover 23 is disposed so as to be openable and closable with respect to one side wall (the rear wall 32 in the present embodiment) of the housing 3. Specifically, the rear wall 32 is provided with an opening 32a. For example, the opening 32a is formed in a rectangular shape and in a range covering the reverse conveyance path L2 in the rear wall 32. The cover 23 is disposed in the housing 3 so that the opening 32a of the rear wall 32 can be opened and closed. In the open state, the cover 23 opens the opening 32a of the rear wall 32 to expose the inside of the housing 3 (such as the fixing unit 7 and the transport unit 25) to the outside. In the closed state, the cover 32 opens the opening 32a. A part of the rear wall 32 is formed by closing.

  On both the left and right sides of the lower end portion of the cover 23, a rotation shaft portion 23a is provided (FIGS. 3 to 5). The rotation shaft portion 23a is rotatably supported by the housing 3. When the upper end side of the cover 23 is rotated rearward (in the direction of arrow Y1 in FIG. 1) with the rotation shaft portion 23a as a fulcrum, the cover 23 is in an open state with respect to the housing 3, and from this open state When rotated to the front side (in the direction of arrow Y2 in FIG. 1), the cover 23 is closed with respect to the housing 3.

  The inner surface 23b of the cover 23 has a conveyance guide region 23c. The conveyance guide region 23c constitutes a part of the conveyance guide of the reversal conveyance path L2, and functions as a conveyance guide for the reversal conveyance path L2 by being disposed facing the reversal conveyance path L2 in the closed state of the cover 23 with respect to the housing 3. .

  As shown in FIG. 1, one transport roller 40 a, 41 a, 42 a, 43 a constituting the transport roller pair 40, 41, 42, 43 is disposed in the transport guide region 23 c of the inner surface 23 b of the cover 23. . The other transport rollers 40b, 41b, and 42b constituting the transport roller pair 40, 41, and 42 are disposed on the opposing surface 25b of the transport unit 25, and the other transport roller 43b that configures the transport roller pair 43 is the housing. Arranged on the body 3.

  Next, the transport unit 25 will be described with reference to FIGS. As shown in FIG. 1, the transport unit 25 is disposed between the paper transport path L1 and the reverse transport path L2. Further, the transport unit 25 is disposed so as to be openable and closable with respect to the housing 3. In the present embodiment, as shown in FIGS. 1 and 2, the transport unit 25 is disposed on the inner surface 23 b of the cover 23, and is opened and closed with respect to the housing 3 as the cover 23 is opened and closed.

  The transport unit 25 is formed, for example, in a flat rectangular parallelepiped box shape (see FIG. 9). In the transport unit 25, one main surface 25a faces a part of the paper transport path L1, and the other main surface 25b faces a part of the reverse transport path L2. Hereinafter, the main surfaces 25a and 25b are referred to as opposing surfaces 25a and 25b, respectively.

  The facing surface 25a is curved along the paper transport path L1, and constitutes a part of the transport guide of the paper transport path L1. Further, a conveying roller 17a, a registration roller 19a, and a secondary transfer roller 53 are disposed on the facing surface 25a. The intermediate roller 17b, the registration driven roller 19b, and the driving roller 52a, which are pairs of the conveyance roller 17a, the registration roller 19a, and the secondary transfer roller 53, are disposed in the housing 3. The facing surface 25b is curved along the reverse conveyance path L2, and constitutes a part of the conveyance guide of the reverse conveyance path L2.

  The transport unit 25 is disposed to be openable and closable with respect to the inner surface 23 b of the cover 23. Specifically, as shown in FIG. 3, a rotation shaft portion 25 c is provided on the lower side in the longitudinal direction of the left and right side surfaces 25 f of the transport unit 25. The rotation shaft portion 25 c protrudes outward in the left-right direction, and is rotatably supported on both left and right sides of the conveyance guide region 23 c on the inner surface 23 b of the cover 23. When the upper end portion 25e of the transport unit 25 is rotated in the direction away from the inner surface 23b of the cover 23 (in the direction indicated by the arrow Y5 in FIG. 3) with the rotation shaft portion 25c as a fulcrum, the transport unit 25 moves relative to the cover 23. be opened. When the upper end portion 25e of the transport unit 25 is rotated in a direction approaching the inner surface 23b of the cover 23 (in the direction of arrow Y6 in FIG. 3), the transport unit 25 is closed with respect to the cover 23.

  As shown in FIG. 2, the housing 3 is provided with a locked portion 27. The locked portion 27 is detachably locked with the locking portion 23 d of the cover 23. The locked portion 27 is formed, for example, as a columnar boss portion, and protrudes in the vicinity of the opening portion 32a in the inner surfaces 34a, 33a of the left and right side walls 34, 33.

  In addition, an interlock switch 29 is disposed in the housing 3. Specifically, as shown in FIG. 2, a hole 30 into which the protrusion 23 i of the cover 23 can be inserted is provided at the periphery of the opening 32 a in the housing 3. As shown in FIG. 8, the interlock switch 29 is arranged inside the hole 30.

  The interlock switch 29 is a switch for detecting the open / closed state of the cover 23. The interlock switch 29 is, for example, a self-recovery type push button switch, which switches to an on state when pressed, and switches to an off state when the pressing is released. When the on / off state of the interlock switch 29 is detected by a predetermined detection circuit, the open / closed state of the cover 23 is detected.

  Hereinafter, the details of the cover 23 will be described. As shown in FIG. 5, a pair (that is, two) of locking portions 23 d are provided on the inner surface 23 b of the cover 23. Hereinafter, the locking portion 23d will be described with reference to FIGS. FIG. 6 is a side view showing the locking portion provided on the inner surface of the cover, and FIG. 7 is a perspective view showing the locking portion provided on the inner surface of the cover.

  Each locking portion 23d is detachably locked to the locked portion 27 of the housing 3, and positions and fixes the cover 23 at a predetermined position of the housing 3 (see FIG. 6). As shown in FIG. 5, the locking portions 23 d are disposed on the left and right sides of the transport guide region 23 c on the inner surface 23 b of the cover 23. As a result, the locking portions 23d are provided to be separated from each other. Moreover, each latching | locking part 23d is arrange | positioned in the predetermined position (for example, center) of the vertical direction (longitudinal direction) of the inner surface 23b.

  A virtual straight line K1 that passes through each position of the pair of locking portions 23d extends in the left-right direction of the cover 23. The virtual straight line K1 is parallel to the rotation axis K2 of the rotation shaft portions 23a on the left and right sides. Note that the position of the locking portion 23d is a predetermined position (for example, the center position) in the area occupied by the locking portion 23d on the inner surface 23b.

  Note that, in a state where the locking portion 23d is locked to the locked portion 27 of the housing 3, the cover 23 receives a tensile force pulled from the housing 3 via the locking portion 23d. This tensile force can be regarded as acting approximately on the position of the locking portion 23d (for example, the center position in the occupied area). That is, the virtual straight line K1 is a straight line passing through the point of action of the tensile force acting on each locking portion 23d.

  As shown in FIGS. 6 and 7, the locking portion 23 d is formed in an elongated rectangular plate shape, for example. The locking portion 23d is erected on the inner surface 23b such that one end surface 23e in the longitudinal direction is a tip surface (hereinafter referred to as a tip surface 23e) and the main surfaces 23h on both sides thereof face in the left-right direction. Is done. The locking portion 23d has a side surface 23f on one side (for example, the upper side) in the longitudinal direction of the distal end surface 23e (hereinafter, referred to as one side surface 23f). On the other hand, a recess 23g is formed on the side surface 23f. The recess 23g is a portion where the locked portion 27 of the housing 3 is locked. The recess 23g is opened on the main surfaces 23h on both sides of the locking portion 23d. The tip surface 23e is inclined toward the one side surface 23f.

  When the cover 23 is closed in the direction of the arrow Y2 in FIG. 6 due to this inclination, the distal end surface 23e is pressed against the locked portion 27, so that the distal end side of the locking portion 23d is elastically below the locked portion 27. The deformed portion is inserted and the locked portion 27 is fitted into the recess 23g. The locked portion 23d is locked to the locked portion 27 by fitting the locked portion 27 into the recess 23g. When the cover 23 is opened in the direction of the arrow Y1 in FIG. 6, the locked portion 27 is released from the recess 23g, and the locking between the locking portion 23d and the locked portion 27 is released.

  As shown in FIGS. 5 and 7, a pressing portion 23 k is provided on the inner surface 23 b of the cover 23. The pressing part 23 k is a part that presses the pressed part 25 d of the transport unit 25 in a closed state of the cover 23 with respect to the housing 3. The pressing portion 23k is formed as a suitably wide surface (for example, a flat surface). Specifically, the pressing portion 23k is elongated along the longitudinal direction of the inner surface 23b.

  The pressing part 23k has an area (hereinafter, referred to as a pressing area) 23j that comes into contact with the pressed part 25d when the pressed part 25d is pressed. The size and position of the pressing area 23j are determined according to the shape of the pressed part 25d. The pressing portion 23k is arranged so that the pressing region 23j overlaps the virtual straight line K1 in a plan view with respect to the inner surface 23b (see FIG. 5). Further, the pressing portions 23k are disposed on both the left and right sides of the conveyance guide region 23c. Specifically, as an example, the pressing portion 23k is disposed close to the inside of the locking portion 23d.

  As shown in FIG. 3, an interlocking projection 23 i is provided on the inner surface 23 b of the cover 23. Hereinafter, the protrusion 23 i will be described with reference to FIGS. 3 and 8. FIG. 8 is a cross-sectional view showing a protrusion provided on the inner surface of the cover.

  The protruding portion 23i switches between OFF and ON by pressing (that is, pressing) the interlock switch 29 of the housing 3. The protrusion 23i is formed in a plate shape, for example. The protruding portion 23i is erected on the inner surface 23b so that one end in the longitudinal direction becomes a tip and the main surfaces 23m on both sides thereof face in the left-right direction. The tip of the projection 23i is formed in a mountain shape in plan view with respect to the main surface 23m. The protrusion 23i is provided on the inner surface 23b so as to overlap the virtual straight line K1 and to be disposed next to the conveyance guide region 23c. In the present embodiment, the protrusion 23i is provided close to the outside of the locking portion 23d on one side (for example, the right side). Note that the protrusion 23i overlaps the virtual straight line K1 when the virtual straight line K1 and the area occupied by the protrusion 23i on the inner surface 23b overlap in plan view with respect to the inner surface 23b.

  Next, details of the transport unit 25 will be described with reference to FIGS. FIG. 9 is a perspective view of the transport unit alone, FIG. 10 is a side view of the pressed part viewed from the direction of the arrow Y7 in FIG. 9, and FIG. 11 is the same view of the pressing unit on the right side of the cover and the transport unit. FIG. 12 is a perspective view illustrating a state in which the pressed portion on the side is in contact with the pressed portion, and FIG. 12 is a perspective view illustrating a state in which the pressed portion on the left side of the cover is in contact with the pressed portion on the same side of the transport unit. It is.

  As shown in FIG. 9, the transport unit 25 is provided with a pressed portion 25d. The pressed part 25 d is a part that is pressed by the pressing part 23 k of the cover 23 in the closed state of the cover 23 with respect to the housing 3. The number of pressed parts 25d is the same as the number of pressing parts 23k (for example, two). The pressed portion 25d is provided at a position facing the pressing portion 23k when the cover 23 is closed with respect to the housing 3. Specifically, the pressed portion 25d is provided on the left and right sides of the facing surface 25b and on the upper end portion 25e side in the transport unit 25.

  As shown in FIG. 10, the pressed portion 25d is formed in a plate shape that is semicircular in plan view, for example. The pressed portion 25d is provided in the transport unit 25 such that the semicircle 25g side is directed to the facing surface 25b side of the transport unit 25 and the main surfaces 25h on both sides thereof are directed in the left-right direction. In the pressed part 25d having this shape, when the pressing part 23k presses the pressed part 25d, the arc center 25i of the semicircle 25g comes into contact with the pressing part 23k. This contact area on the pressing portion 23k side becomes the pressing area 23j of the pressing portion 23k. In the present embodiment, only the vicinity of the arc center 25i of the pressed part 25d is in contact with the pressing part 23k, so that the pressing area 23j of the pressing part 23k is relatively small.

  In the closed state of the transport unit 25 with respect to the cover 23, as shown in FIGS. 11 and 12, the pressing portions 23k of the cover 23 and the pressed portions 25d come into contact with each other, so that the transport guide region 23c of the cover 23 and the transport unit 25 are in contact. The opposing surface 25b is arranged to face the predetermined interval. Further, in the open state of the transport unit 25 with respect to the cover 23, the pressing portions 23k of the cover 23 and the pressed portions 25d are separated from each other, and the transport guide region 23c of the cover 23 and the facing surface 25b of the transport unit 25 are exposed to the outside. Is done.

<Description of operation>
Next, the operation of the cover 23 with respect to the housing 3 will be described with reference to FIGS. 2, 6, 8, 11, and 12.

  In the state of FIG. 2, the cover 23 is opened with respect to the housing 3, and the transport unit 25 is closed with respect to the cover 23. When closing the cover 23 from this state, the cover 23 is manually rotated in the direction of the arrow Y2 in FIG. 2 and the opening 32a of the rear wall 32 is completely closed by the cover 23. In this way, the cover 23 is closed with respect to the housing 3.

  In this closed state (closed state of the cover 23 with respect to the housing 3), each locking portion 23 d of the cover 23 is in contact with each locked portion 27 of the housing 3, as shown by the one-dot chain line state in FIG. 6. Lock. As a result, the cover 23 is closed with respect to the housing 3 while being positioned at a predetermined position of the housing 3. As a result, the transport unit 25 is positioned and fixed at a predetermined position of the housing 3.

  Further, in this closed state, as shown in FIGS. 11 and 12, each pressing portion 23 k of the cover 23 contacts and presses each pressed portion 25 d of the transport unit 25. In this pressed state, the pressing region 23j of the pressing part 23k and the arc center 25i of the pressed part 25d abut. By this pressing, nip regions are formed between the conveyance roller 17a and the intermediate roller 17b, between the registration roller 19a and the registration driven roller 19b, and between the secondary transfer roller 53 and the driving roller 52a. The

  Further, in this closed state, as shown by the one-dot chain line state in FIG. 8, the protrusion 23 i of the cover 23 is inserted into the hole 30 of the housing 3, and the interlock switch 29 is pressed to turn on. Switch.

  Further, in this closed state, the cover 23 receives a pulling force pulled from the housing 3 through the locking portion 23d, and a pressing force (that is, a pressing force from the transport unit 25 through the pressing region 23j of the pressing portion 23k (that is, the cover 23). The pressing portion 23k receives a reaction of force that presses the pressed portion 25d. Each of these forces (tensile force and pressing force) acts almost perpendicularly to the inner surface 23b of the cover 23. These force directions are parallel and opposite to each other.

  By the way, in this embodiment, the press area | region 23j of the press part 23k overlaps with the virtual straight line K1. Here, as described above, the virtual straight line K1 is a straight line that passes through the point of application of the tensile force acting on each locking portion 23d approximately. Further, it can be considered that the pressing force acting on the pressing region 23j is approximately applied to a predetermined position in the pressing region 23j. Moreover, in this embodiment, since the to-be-pressed part 25d is formed in a semicircular plate shape, the press area | region 23j becomes comparatively small.

  For this reason, in the state seen from the left and right sides of the cover 23, the interval between the lines of action of each of the above-mentioned forces (tensile force and pushing force) becomes sufficiently small, and the moment of the force due to each of the above-mentioned forces becomes sufficiently small. As a result, distortion of the cover 23 is suppressed. Further, since the pressing portion 23k is provided close to the locking portion 23d, even when viewed from the upper end portion side of the cover 23, the interval between the lines of action of the respective forces is sufficiently small, The moment of force due to force is sufficiently small, and as a result, distortion of the cover 23 is further suppressed.

  In this closed state, the cover 23 further receives a pressing force that is pressed from the interlock switch 29 via the protrusion 23 i (that is, the reaction of the force by which the protrusion 23 i presses the interlock switch 29). This pressing force (hereinafter referred to as a second pressing force) also acts substantially perpendicular to the inner surface 23b of the cover 23 and is in a direction opposite to the above-described tensile force. This second pressing force can also be regarded as acting approximately at a predetermined position in the occupied area of the protrusion 23i. By the way, the protrusion 23i overlaps the virtual straight line K1 and is provided in the vicinity of the locking portion 23d, so that the distortion of the cover 23 is suppressed when viewed from the left and right sides and the upper end side of the cover 23 as described above. .

  The embodiment of the present invention has been described above with reference to the drawings (FIGS. 1 to 12). However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof (for example, Modification 1 and Modification 2 shown below). In order to facilitate understanding, the drawings schematically show each component as a main component, and the thickness, length, number, and the like of each component shown in the drawings are different from the actual for convenience of drawing. . In addition, the material, shape, dimensions, and the like of each component shown in the above embodiment are merely examples, and are not particularly limited, and various changes can be made without departing from the effects of the present invention. is there.

<Modification 1>
In the above embodiment, the pressing part 23k is arranged so that the pressing area 23j overlaps the virtual straight line K1, but in the first modification, the center position of the pressing area 23j of the pressing part 23k is arranged on the virtual straight line K1. The The pressing force acting on the pressing area 23j can be regarded as acting approximately on the center position of the pressing area 23j. In view of this, in the first modification, the distance between the lines of action of each of the above-described forces (tensile force and pressing force) is further reduced in the state viewed from the left and right sides of the cover 23. It is further suppressed.

  Modification 1 is effective when the pressing area 23j of the pressing portion 23k is relatively large. This is because when the pressing area 23j is large, the interval between the lines of action of the above-described forces may not be sufficiently reduced if the pressing area 23j only overlaps the virtual straight line K1. On the other hand, the above embodiment is effective when the pressing region 23j is relatively small. This is because, when the pressing area 23j is relatively small, the distance between the above-mentioned action lines of each force is sufficiently small just by overlapping the pressing area 23j with the virtual straight line K1.

<Modification 2>
In the above embodiment, the protrusion 23i is arranged so as to overlap the virtual straight line K1, but in the second modification, the center position of the occupied area on the inner surface 23b of the protrusion 23i is arranged on the virtual straight line K1. Also in the second modification, the distance between the lines of action of the above-described forces (tensile force and second pressing force) is further reduced in the state viewed from the left and right sides of the cover 23, so that the distortion of the cover 23 is further suppressed. Is done. This modification 2 is effective when the occupation area on the inner surface 23b of the protrusion 23i is relatively large. This is because when the occupied area is relatively large, the distance between the action lines of the above-mentioned forces may not be sufficiently close if the occupied area only overlaps the virtual straight line K1. On the other hand, the above embodiment is effective when the occupied area is relatively small. This is because, when the occupied area is relatively small, the interval between the above-described action lines of each force is sufficiently small just by overlapping the occupied area with the virtual straight line K1.

3 Case (device main body)
23 Cover 23b Inner surface 23d Locking portion 23i Protruding portion 23j Pressing area 23k Pressing portion 25 Transport unit 29 Interlock switch K1 Virtual straight line L1 Paper transport path L2 Reverse transport path (paper transport path)
P paper

Claims (5)

The device body;
An image forming unit that forms an image on the conveyed paper;
A transport unit that is rotatably supported at the lower end of the apparatus body and forms a part of a paper transport path for transporting the paper;
A lower end portion is rotatably supported with respect to the apparatus main body and is arranged to be opened and closed, and a cover that presses the transport unit in a closed state with respect to the apparatus main body,
A pair of locking portions provided on the inner surface of the cover;
A pressing portion provided on the inner surface of the cover,
The pair of locking portions are locked to the apparatus main body in a closed state of the cover with respect to the apparatus main body,
The pressing portion has a pressing region that presses the transport unit in a closed state of the cover with respect to the apparatus main body,
In plan view with respect to said inner surface, said pressing region Ri virtual straight line Do heavy through each position of the pair of locking portions,
The image forming apparatus, wherein the pressing portion is provided in proximity to the locking portion .   The image forming apparatus according to claim 1, wherein a center position of the pressing area is arranged on the virtual straight line. The device main body is provided with an interlock switch for detecting opening and closing of the cover,
The inner surface of the cover is provided with a protrusion that presses the interlock switch in a closed state of the cover with respect to the apparatus main body.
3. The image forming apparatus according to claim 1, wherein an area occupied by the protruding portion on the inner surface overlaps the virtual straight line in a plan view with respect to the inner surface.   The image forming apparatus according to claim 3, wherein the protrusion is provided in proximity to the locking portion.   The transport unit is
  One main surface that forms the sheet conveyance path facing the image forming unit;
  The other main surface forming a reverse conveyance path for reversing the front and back of the paper on the opposite side of the one main surface;
  Including
  5. The image forming apparatus according to claim 1, wherein an inner surface of the cover includes a conveyance guide region that forms the reverse conveyance path so as to face the other main surface. 6.

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