Image forming device

Abstract

To easily and accurately perform positioning of a developing device with a simple configuration.SOLUTION: An image forming apparatus 100 comprises: a drum unit that has a photoreceptor drum; a developing device 14 that has a developing roller arranged opposite to the photoreceptor drum at their outer peripheral surfaces; a developing holder 70 that is removably attached with the developing device 14 and swings the developing roller to approach and separate from the photoreceptor drum; and a lower stage rail 42 that slides in an axial direction of the developing roller. The developing holder 70 swings such that the developing roller approaches the photoreceptor drum in conjunction with the slide of the lower stage rail 42 from a first position to a second position. The developing holder 70 swings such that the developing roller separates from the photoreceptor drum in conjunction with the slide of the lower stage rail 42 from the second position to the first position.SELECTED DRAWING: Figure 15

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] An electrophotographic image forming apparatus includes a photosensitive drum and a developing device. The photosensitive drum needs to be replaced when it reaches the end of its life. The developing device needs regular maintenance. For this reason, it is common to configure the drum unit including the photosensitive drum and the developing device to be individually detachable from the image forming apparatus main body. For example, the image forming apparatus described in Patent Document 1 includes a unit support frame that supports the drum unit and the developing device individually and detachably, and a developing holder that is provided on the unit support frame and holds the developing device so that it can be swung in a direction that moves the developing roller toward or away from the photosensitive drum. The developing holder includes a drive gear that transmits power to the developing device, and a pair of swinging shafts that have a rotation axis that extends parallel to the axial direction of the developing roller and are rotatably supported by the unit support frame. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-201459 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the image forming apparatus described in Patent Document 1 includes a cam that rocks the developing device and a gear that links the opening and closing of the cover with the operation of the cam, which increases the number of parts and increases costs.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In consideration of the above circumstances, an object of the present invention is to provide an image forming apparatus in which the positioning of a developing device can be easily and accurately performed with a simple configuration. [Means for solving the problem]

[0006] In order to solve the above problem, the image forming apparatus of the present invention comprises a drum unit having a photosensitive drum, a developing device having a developing roller arranged with its outer peripheral surface facing the photosensitive drum, a developing holder to which the developing device is attached and detached and which swings to move the developing roller closer to and away from the photosensitive drum, and a slide member that slides in the axial direction of the developing roller, wherein the developing holder swings in conjunction with the sliding of the slide member from a first position to a second position so that the developing roller approaches the photosensitive drum, and the developing holder swings in conjunction with the sliding of the slide member from the second position to the first position so that the developing roller moves away from the photosensitive drum.

[0007] The slide member may be provided below the developing holder, the developing holder having a first convex portion protruding downward, and the slide member having a second convex portion protruding upward, and when the slide member is located at the first position, the first convex portion does not contact the second convex portion, and when the slide member slides from the first position to the second position, the first convex portion pushes aside the second convex portion, thereby oscillating the developing holder so that the developing roller approaches the photosensitive drum.

[0008] The image forming device may include an opening into which the developing device is inserted, and a cover connected to the opening via a hinge and to which the sliding member is coupled, and may be configured such that the sliding member slides from the first position to the second position in conjunction with an operation of closing the cover, and that the sliding member slides from the second position to the first position in conjunction with an operation of opening the cover.

[0009] The image forming apparatus may include a boss protruding from the cover side end of the sliding member in the axial direction of the hinge, a link member provided inside the cover and swinging together with the cover when the cover is opened and closed, and a groove provided on the link member and sliding against the tip of the boss when the cover is opened and closed, wherein the groove includes a first section having an arc shape centered on the axis of the hinge, and a second section that is continuous with the cover side end of the first section and has a smaller radius of curvature than the first section, and wherein when the cover is swung within a range from a fully open position to a predetermined position between the fully open position and the fully closed position, the first section slides against the boss while the sliding member remains in the first position, and when the cover is swung within a range from the predetermined position to the fully closed position, the second section slides against the boss, thereby causing the sliding member to slide between the first position and the second position. Effect of the Invention

[0010] According to the present invention, the developing device can be positioned easily and accurately with a simple structure. [Brief description of the drawings]

[0011] [Figure 1] 1 is a perspective view showing an external appearance of an image forming apparatus according to an embodiment of the present invention; [Diagram 2] 1 is a front view showing a schematic internal configuration of an image forming apparatus according to an embodiment of the present invention; [Diagram 3] FIG. 2 is a perspective view of an imaging device and an inner cover according to an embodiment of the present invention. [Figure 4] FIG. 2 is a perspective view of an imaging device and an inner cover according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a perspective view of a drum unit according to an embodiment of the present invention. [Figure 6] FIG. 2 is a perspective view of a developing device according to an embodiment of the present invention. [Figure 7] 1 is a front view showing a schematic configuration of an image forming device according to an embodiment of the present invention; [Figure 8]1 is a front view showing a schematic configuration of an image forming device according to an embodiment of the present invention; [Figure 9] FIG. 2 is a perspective view showing a state in which a developing holder is attached to a unit support frame according to an embodiment of the present invention. [Figure 10] FIG. 2 is a perspective view of a unit support frame according to an embodiment of the present invention. [Figure 11] FIG. 2 is a perspective view of a developer holder and a lower rail according to an embodiment of the present invention. [Figure 12] FIG. 2 is a perspective view of a developing holder, an upper rail, and a lower rail according to an embodiment of the present invention. [Figure 13] FIG. 2 is a cross-sectional view of a lower rail and a developing device according to an embodiment of the present invention. [Figure 14] FIG. 2 is a cross-sectional view of a lower rail and a developing device according to an embodiment of the present invention. [Figure 15] FIG. 2 is a cross-sectional view of a lower rail and a developing device according to an embodiment of the present invention. [Figure 16] FIG. 4 is a side view of a link member according to one embodiment of the present invention. [Figure 17] FIG. 4 is a side view of a link member according to one embodiment of the present invention. [Figure 18] FIG. 4 is a side view of a link member according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an image forming apparatus 100 according to an embodiment of the present invention will be described with reference to the drawings.

[0013] First, the overall configuration of image forming apparatus 100 will be described. Fig. 1 is a perspective view showing the external appearance of image forming apparatus 100. Fig. 2 is a front view showing a schematic internal configuration of image forming apparatus 100. In the following description, the front side of the paper in Fig. 2 is the front side (front side) of image forming apparatus 100, and the left and right directions are described based on the direction when image forming apparatus 100 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr respectively indicate up, down, left, right, front, and rear.

[0014] The image forming apparatus 100 includes a printer 1, a scanner 110, and a document transport device 120. The scanner 110 is provided above the printer 1, and the document transport device 120 is provided above the scanner 110. The document transport device 120 transports a document along a transport path that passes through a reading position of the scanner 110. The scanner 110 is a flatbed type image scanner that reads a document and generates image data. The printer 1 forms an image on a sheet S based on the image data.

[0015] The printer 1 and the scanner 110 are integrated into a housing 3. At the bottom inside the housing 3, there are provided a paper feed cassette 4 in which sheets S are stored, and a paper feed roller 5 that sends the sheets S from the paper feed cassette 4 to the right. Above the paper feed cassette 4, there is provided an imaging device 6 that forms a toner image by electrophotography, and above the upper right of the imaging device 6, there is provided a fixing device 7 that fixes the toner image to the sheets S. Above the fixing device 7, there are provided a paper discharge roller 8 that discharges the sheets S on which the toner image has been fixed, and a paper discharge tray 9 on which the discharged sheets S are stacked.

[0016] Inside the housing 3, a transport path 10 is provided that runs from the paper feed roller 5 through the imaging device 6 and the fixing device 7 to the paper discharge roller 8. The transport path 10 is mainly formed of plate-like members that face each other with a gap therebetween to allow the sheet S to pass through, and transport rollers 17 that hold and transport the sheet S are provided at multiple locations in the transport direction Y. A registration roller 18 is provided upstream of the imaging device 6 in the transport direction Y. To the right of the fixing device 7, a reversing transport path 10R is provided that branches off from the transport path 10 downstream of the fixing device 7 in the transport direction Y and joins the transport path 10 upstream of the registration roller 18 in the transport direction Y.

[0017] The image forming device 6 includes a photoconductor drum 11 whose potential changes when irradiated with light, a charging device 12 that charges the photoconductor drum 11, an exposure device 13 that emits laser light according to image data, a developing device 14 that supplies toner to the photoconductor drum 11, an intermediate transfer unit 15 that transfers a toner image from the photoconductor drum 11 to a sheet S, and a cleaning device 16 that removes toner remaining on the photoconductor drum 11. The intermediate transfer unit 15 includes an endless intermediate transfer belt 15B wrapped around a driving roller 15D and a driven roller 15N, a primary transfer roller 151 that faces the inner peripheral surface of the intermediate transfer belt 15B at a position corresponding to the photoconductor drum 11 and generates a primary transfer bias, and a secondary transfer roller 152 that faces the outer peripheral surface of the intermediate transfer belt 15B at a position corresponding to the driving roller 15D and generates a secondary transfer bias. A toner container 20 that supplies toner to the developing device 14 is connected to the developing device 14.

[0018] The image forming device 6 includes four sets of photoconductor drums 11, charging devices 12, exposure devices 13, developing devices 14, primary transfer rollers 151, cleaning devices 16, and toner containers 20, and forms a color image by superimposing four color toner images on the intermediate transfer belt 15B. Note that the present invention may be applied to an image forming device that forms a color image with toners of three or less colors or five or more colors.

[0019] The control unit 2 includes a calculation unit and a storage unit. The calculation unit is, for example, a CPU (Central Processing Unit). The storage unit includes storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an EEPROM (Electrically Erasable Programmable Read Only Memory). The calculation unit performs various processes by reading and executing a control program stored in the storage unit. The control unit 2 may be realized by only an integrated circuit without using software.

[0020] An operation panel 19 is provided on the front side of the scanner 110. The operation panel 19 includes a display panel, a touch panel superimposed on the display surface of the display panel, and a keypad adjacent to the display panel. The control unit 2 displays screens showing operation menus and statuses of the printer 1 and scanner 110 on the display panel, and controls each part of the printer 1 and scanner 110 in response to operations detected by the touch panel and the keypad.

[0021] The basic image forming operation of the printer 1 is as follows. When a print job for single-sided printing is input to the printer 1 from an external computer or the like, the paper feed roller 5 feeds the sheet S from the paper feed cassette 4 to the transport path 10, the registration roller 18, whose rotation has been stopped, corrects the skew of the sheet S, and the registration roller 18 feeds the sheet S to the image forming device 6 at a predetermined timing. In the image forming device 6, the charging device 12 charges the photosensitive drum 11 to a predetermined potential, the exposure device 13 writes a latent image on the photosensitive drum 11, the developing device 14 develops the latent image using toner supplied from the toner container 20 to form a toner image, the primary transfer roller 15A transfers the toner image to the intermediate transfer belt 15B, and the secondary transfer roller 15C transfers the toner image to the sheet S. Next, the fixing device 7 melts the toner image while clamping and transporting the sheet S to fix the toner image to the sheet S, and the paper discharge roller 8 discharges the sheet S to the paper discharge tray 9. The cleaning device 16 removes toner remaining on the photoconductor drum 11. In the case of double-sided printing, the sheet S with a toner image fixed on its first surface is sent into the transport path 10 via the inverted transport path 10R, whereby the toner image is transferred to the second surface.

[0022] Next, the imaging device 6 will be described in detail. Fig. 3 is a perspective view of the imaging device 6 and the inner cover 3C (inner cover 3C is closed). Fig. 4 is a perspective view of the imaging device 6 and the inner cover 3C (inner cover 3C is open). Fig. 5 is a perspective view of the drum unit 50. Fig. 6 is a perspective view of the developing device 14. Figs. 7 and 8 are front views showing the configuration of the imaging device 6 (excluding the exposure device 13).

[0023] [Inner cover] An opening 3A and an outer cover 3B that covers the opening 3A are provided above the paper feed cassette 4 on the front side of the housing 3 (see FIG. 1). By opening (or removing) the outer cover 3B, the opening 3A is opened and an inner cover 3C (an example of a cover) is exposed (see FIGS. 3 and 4). The lower end of the inner cover 3C is connected to the opening 3A via a hinge 3H whose axial direction is the left-right direction. Four detachable sets of drum units 50 and developing devices 14 are provided behind the inner cover 3C.

[0024] [Drum unit] Drum unit 50 (see FIGS. 5 and 7) integrates photoconductor drum 11, charging device 12, and cleaning device 16. The lower part of drum unit 50 is formed into a box shape with the longitudinal direction being the front-to-rear direction, and houses charging device 12 inside. Photoconductor drum 11 is provided above charging device 12, and cleaning device 16 is provided to the right of photoconductor drum 11.

[0025] [Developing device] The developing device 14 (see FIGS. 6 and 7) includes two screws 33 that rotate around their axes to agitate the developer, a developing roller 32 that holds the developer above the screws 33, a housing 31 that houses the screws 33 and the developing roller 32 and has an opening 35 through which part of the outer circumferential surface of the developing roller 32 is exposed, and a blade 34 that is disposed below the opening 35 and regulates the layer thickness of the developer held by the developing roller 32. The developing roller 32 and the screws 33 are both disposed with their axial direction aligned in the front-to-rear direction.

[0026] The developer is, for example, a two-component developer containing a magnetic carrier and a non-magnetic toner. The two screws 33 are arranged parallel to each other on the left and right inside the housing 31, and transport the developer in opposite directions. A partition 36 is provided between the two screws 33. A gap is provided between the front end of the partition 36 and the inner surface of the housing 31, and between the rear end of the partition 36 and the inner surface of the housing 31, and the developer circulates around the partition 36 through the gap. The developer is stirred by the screw 33, causing the toner to become triboelectrically charged.

[0027] The developing roller 32 is disposed above and in parallel with the right screw 33. The developing roller 32 includes a permanent magnet and a developing sleeve formed of a non-magnetic material that covers the periphery of the permanent magnet (not shown). A driven gear 32G is provided at the rear end of the developing roller 32. The opening 35 is formed on the right side of the upper part of the housing 31, and the outer circumferential surface of the developing roller 32 exposed from the opening 35 faces the outer circumferential surface of the photosensitive drum 11. The developer forms a magnetic brush layer on the surface of the developing roller 32. The blade 34 is disposed with its tip end spaced a predetermined distance from the developing roller 32, and adjusts the layer thickness of the magnetic brush to a predetermined thickness.

[0028] An annular gap regulating member 32S having a diameter larger than that of the developing sleeve is provided on both ends of the developing roller 32. The gap regulating member 32S comes into contact with the outer circumferential surface of the photosensitive drum 11, so that the outer circumferential surface of the developing sleeve and the outer circumferential surface of the photosensitive drum 11 face each other with a predetermined gap therebetween.

[0029] Next, a configuration for positioning the developing device 14 will be described. FIG. 9 is a perspective view showing the state in which the developing holder 70 is attached to the unit support frame 60. FIG. 10 is a perspective view of the unit support frame 60. FIG. 11 is a perspective view of the developing holder 70 and the lower rail 42. FIG. 12 is a perspective view of the developing holder 70, the upper rail 41, and the lower rail 42. FIG. 13 is a cross-sectional view of the lower rail 42 and the developing device 14 (inner cover 3C is in a fully closed state). FIG. 14 is a cross-sectional view of the lower rail 42 and the developing device 14 (inner cover 3C is in a predetermined position between fully closed and fully open). FIG. 15 is a cross-sectional view of the lower rail 42 and the developing device 14 (inner cover 3C is in a fully open state). Note that FIGS. 13 to 15 show a cross section along the axis of the left screw 33. FIGS. 16 to 18 are side views of the link member 43.

[0030] The image forming apparatus 100 comprises a drum unit 50 having a photosensitive drum 11, a developing device 14 having a developing roller 32 arranged with its outer peripheral surface facing the photosensitive drum 11, a developing holder 70 to which the developing device 14 is attached and detached, which swings to move the developing roller 32 closer to and away from the photosensitive drum 11, and a lower rail 42 (an example of a sliding member) which slides in the axial direction of the developing roller 32, the developing holder 70 swinging in conjunction with the sliding of the lower rail 42 from a first position to a second position so that the developing roller 32 approaches the photosensitive drum 11, and the developing holder 70 swinging in conjunction with the sliding of the lower rail 42 from the second position to the first position so that the developing roller 32 moves away from the photosensitive drum 11.

[0031] [Unit support frame] The unit support frame 60 (see FIGS. 9 and 10) is a member that supports four drum units 50 and the developing device 14. The unit support frame 60 has a generally rectangular plate-shaped bottom portion 60B, and is fixed to the housing 3. On the upper surface of the unit support frame 60, a drum unit support portion 62, a holder support portion 61, and a lower rail support portion 63 are provided.

[0032] The drum unit support portion 62 is a concave portion into which the lower portion of the drum unit 50 fits. A developing holder 70 that supports the developing device 14 that is paired with the drum unit 50 is provided to the left of the drum unit support portion 62. The developing holder 70 is supported by the holder support portion 61. The holder support portion 61 has a first fulcrum 611 and a second fulcrum 612 that support the developing holder 70 at two points in the front-rear direction. A wall portion 60W that stands upright upward is provided at the rear end portion of the unit support frame 60. The first fulcrum 611 is a cylindrical shaft that protrudes forward from the wall portion. The second fulcrum 612 is an upright plate-like member provided forward of the first fulcrum 611 and has a circular hole that penetrates in the front-rear direction. The center line of the shaft of the first fulcrum 611 passes through the center of the hole of the second fulcrum 612. The lower rail support portion 63 is provided on the left side portion of the upper surface of the holder support portion 61 and supports the lower rail 42 slidably in the front-rear direction by contacting the left and right side surfaces of the lower rail 42 described below.

[0033] [Developer holder] The developer holder 70 (see FIGS. 11 and 12) includes an axial connection portion 71 to which the rear end of the developing device 14 is connected, and a bottom support portion 72 that supports the bottom of the developing device 14. The axial connection portion 71 faces the rear end of the developing device 14 and includes a drive gear 71G. The drive gear 71G is driven by a motor via a reduction gear (not shown). The bottom support portion 72 is a roughly rectangular plate-like member whose longitudinal direction is the front-rear direction, and includes a wall portion that regulates left-right positional deviation of the developing device 14.

[0034] A first fulcrum 721 and a second fulcrum 722 are provided at the right end of the bottom support portion 72. The first fulcrum 721 is a circular hole into which the first fulcrum 611 of the unit support frame 60 fits. The second fulcrum 722 is a cylindrical shaft that fits into the second fulcrum 612 of the unit support frame 60. A fulcrum 37 is provided at the lower right of the front end of the housing 31 of the developing device 14. The fulcrum 37 is, for example, a hole that penetrates in the front-rear direction. The fulcrum 37 is fitted onto the outside of the second fulcrum 722 of the developing holder 70. The developing holder 70 and the developing device 14 are swingable about the first fulcrum 721 and the second fulcrum 722.

[0035] The developing device 14 is attached to the developing holder 70 by pushing it into the developing holder 70 from the front. At this time, the driven gear 32G of the developing roller 32 meshes with the driving gear 71G of the developing holder 70. The developing device 14 is removed from the developing holder 70 by pulling it out forward from the developing holder 70.

[0036] [Upper rail, lower rail] The upper rail 41 and the lower rail 42 (see FIGS. 11 to 15) are rod-shaped members whose overall longitudinal direction is the front-rear direction. The upper rail 41 is fixed to the left side portion of the lower surface of the developing holder 70. As described above, the lower rail 42 is slidably provided on the upper surface of the unit support frame 60. The upper rail 41 and the lower rail 42 face each other in the vertical direction.

[0037] The upper rail 41 has a main body 41M with a rectangular cross section. A first protrusion 41T protruding downward is provided on the bottom surface of the main body 41M at a position slightly rearward of the center of the developer holder 70 in the front-rear direction. The first protrusion 41T has left and right side surfaces, a front surface, a rear surface, and a bottom surface, and the front surface is inclined so that the upper end is located forward of the lower end. A recess 41U that is elongated in the front-rear direction is provided adjacent to the front of the first protrusion 41T. The width of the recess 41U in the left-right direction is narrower than the width of the first protrusion 41T.

[0038] A guide member 41G is provided on the underside of the upper rail 41, forward of the recess 41U. The guide member 41G includes a groove member 41GU and a rod-shaped member 41GB with the longitudinal direction being the left-right direction. The groove member 41GU has a top plate portion and left and right sidewall portions, and the top plate portion is fixed to the underside of the upper rail 41. The rod-shaped member 41GB is provided inside the groove member 41GU, and both left and right ends of the rod-shaped member 41GB are supported by the left and right sidewall portions of the groove member 41GU.

[0039] The lower rail 42 has a main body 42M with a rectangular cross section. The front end of the main body 42M is bent downward and has a boss 42B protruding to the right. The upper surface of the lower rail 42 is provided with a second protrusion 42T protruding upward. The second protrusion 42T has left and right side surfaces, a front surface, a rear surface, and an upper surface, and the rear surface is inclined so that the upper end is located forward of the lower end. The width of the second protrusion 42T in the left-right direction is slightly narrower than the width of the recess 41U of the upper rail 41, and the second protrusion 42T can enter the recess 41U.

[0040] The lower rail 42 is provided with a notch 42K into which the rod-shaped member 41GB of the guide member 41G of the upper rail 41 can be inserted. The notch 42K includes an axial portion 42KA extending in the front-rear direction (the axial direction of the developing roller 32) and an inclined portion 42KS inclined in the same manner as the front surface of the first convex portion 41T and the rear surface of the second convex portion 42T.

[0041] [Link member] The link member 43 (see Figs. 16 to 18) is fixed to the inside of the inner cover 3C and swings together with the inner cover 3C when the inner cover 3C is opened or closed. The link member 43 has an axial hole portion 43A supported coaxially with the hinge 3H of the inner cover 3C and a groove 43V that slides against the tip of the boss 42B when the inner cover 3C is opened or closed. The groove 43V has a first section 43V1 that is an arc centered on the axis of the hinge 3H, and a second section 43V2 that is continuous with the first section 43V1 and has a smaller radius of curvature than the first section 43V1. The second section 43V2 is connected to the end of the first section 43V1 on the inner cover 3C side.

[0042] Next, the opening and closing operation of the inner cover 3C will be described. Figures 15 and 18 show the inner cover 3C in a fully open state. The developing device 14 is attached and detached with the inner cover 3C in a fully open state. The boss 42B of the lower rail 42 is located at the end of the first section 43V1 of the groove 43V of the link member 43 on the developing device 14 side. At this time, the lower rail 42 is in a position pulled out to the frontmost position. This position is called the first position.

[0043] In the first position, the second protrusion 42T of the lower rail 42 is located forward of the first protrusion 41T of the upper rail 41 and enters the recess 41U of the upper rail 41. In other words, the second protrusion 42T is not in contact with the first protrusion 41T. Also, the rod-shaped member 41GB of the guide member 41G of the upper rail 41 is located at the axial portion 42KA of the notch 42K of the lower rail 42. At this time, the upper rail 41 is closest to the lower rail 42, and the developing roller 32 is furthest from the photosensitive drum 11 as shown in FIG. 8.

[0044] 14 and 17 show a state in which the boss 42B is located near the boundary between the first section 43V1 and the second section 43V2 of the 43V groove. The position of the inner cover 3C at this time is called the predetermined position. When the inner cover 3C is swung within a range from the fully open position to the predetermined position, the first section 43V1 slides against the boss 42B while the lower rail 42 remains in the first position. Since the lower rail 42 does not move, the relative positional relationship with the upper rail 41 does not change, and the attitude of the developer holder 70 does not change either.

[0045] 13 and 16 show the inner cover 3C in a fully closed state. When the inner cover 3C is closed from a predetermined position to a fully closed position, the boss 42B enters the second section 43V2 of the groove 43V, so that the boss 42B is pushed rearward by the outer periphery of the second section 43V2, and the lower rail 42 also moves rearward. When the inner cover 3C is fully closed, the lower rail 42 is pushed all the way to the rear. This position is called the second position.

[0046] When the lower rail 42 moves from the first position (see FIG. 15) to the second position (see FIG. 13), the rear surface of the second protrusion 42T slides backward against the front surface of the first protrusion 41T. Also, the rod-shaped member 41GB of the guide member 41G of the upper rail 41 moves backward against the inclined portion 42KS of the notch 42K of the lower rail 42. Therefore, the upper rail 41 is gradually pushed up, the lower surface of the first protrusion 41T rides on the upper surface of the second protrusion 42T, and the rod-shaped member 41GB rides on the upper surface of the lower rail 42. At this time, the upper rail 41 is in a state farthest from the lower rail 42, and the developing roller 32 is closest to the photosensitive drum 11 as shown in FIG. 7.

[0047] When the inner cover 3C is opened from the fully closed position (see FIG. 13) to a predetermined position (see FIG. 14), the boss 42B is pushed forward by the inner periphery of the second section 43V2 of the groove 43V, and the lower rail 42 also moves forward. When the inner cover 3C reaches the predetermined position, the lower rail 42 reaches the first position. When the lower rail 42 moves from the second position to the first position, the rear surface of the second convex portion 42T moves forward while sliding against the front surface of the first convex portion 41T. The rod-shaped member 41GB moves forward while sliding against the inclined portion 42KS of the cutout portion 42K. Therefore, the upper rail 41 gradually descends and returns to the fully open position (see FIG. 15).

[0048] According to the image forming apparatus 100 according to the present embodiment described above, the image forming apparatus 100 includes a drum unit 50 having a photosensitive drum 11, a developing device 14 having a developing roller 32 arranged with the outer circumferential surfaces of the photosensitive drum 11 facing each other, a developing holder 70 to which the developing device 14 is attached and detached and which swings to move the developing roller 32 closer to and farther from the photosensitive drum 11, and a lower rail 42 (an example of a sliding member) which slides in the axial direction of the developing roller 32, and the developing holder 70 swings in conjunction with the sliding of the lower rail 42 from the first position to the second position so that the developing roller 32 approaches the photosensitive drum 11, and the developing holder 70 swings in conjunction with the sliding of the lower rail 42 from the second position to the first position so that the developing roller 32 moves away from the photosensitive drum 11. Thus, the positioning of the developing device 14 can be easily and reliably performed with a simple configuration.

[0049] Moreover, according to the image forming apparatus 100 of this embodiment, the lower rail 42 is provided below the developing holder 70, the developing holder 70 has a first convex portion 41T protruding downward, and the lower rail 42 has a second convex portion 42T protruding upward, and when the lower rail 42 is located at the first position, the first convex portion 41T does not contact the second convex portion 42T, and when the lower rail 42 slides from the first position to the second position, the first convex portion 41T pushes aside the second convex portion 42T, thereby swinging the developing holder 70 so that the developing roller 32 approaches the photosensitive drum 11. Thus, the developing holder 70 can be swung in conjunction with the sliding of the lower rail 42 with a simple configuration.

[0050] Furthermore, the image forming apparatus 100 according to this embodiment includes an opening 3A into which the developing device 14 is inserted, and an inner cover 3C (one example of a cover) that is coupled to the opening 3A via a hinge 3H and to which a lower rail 42 is connected, and the lower rail 42 slides from the first position to the second position in conjunction with the operation of closing the inner cover 3C, and the lower rail 42 slides from the second position to the first position in conjunction with the operation of opening the inner cover 3C. Therefore, the positioning of the developing device 14 can be easily and accurately performed simply by opening and closing the inner cover 3C.

[0051] Furthermore, the image forming apparatus 100 according to the present embodiment includes a boss 42B protruding in the axial direction of the hinge 3H from the end of the lower rail 42 on the inner cover 3C side, a link member 43 provided on the inside of the inner cover 3C and swinging together with the inner cover 3C when the inner cover 3C is opened or closed, and a groove 43V provided in the link member 43 and sliding against the tip of the boss 42B when the inner cover 3C is opened or closed. The groove 43V includes a first section 43V1 having an arc shape centered on the axis of the hinge 3H and a second section 43V1 on the inner cover 3C side. and a second section 43V2 continuous with the end of the first section 43V1 and having a smaller radius of curvature than the first section 43V1, and when the inner cover 3C is swung within a range from the fully open position to a predetermined position between the fully open position and the fully closed position, the first section 43V1 slides against the boss 42B while the lower rail 42 is located at the first position, and when the inner cover 3C is swung within a range from the predetermined position to the fully closed position, the second section 43V2 slides against the boss 42B, causing the lower rail 42 to slide between the first position and the second position. Therefore, the sliding of the lower rail 42 is performed in a state where the axial component force of the force for opening and closing the inner cover 3C is large, and therefore the effort required for opening and closing the inner cover 3C can be reduced.

[0052] The above embodiment may be modified as follows.

[0053] In the above embodiment, an example was shown in which the rear surface of the second protrusion 42T slides against the front surface of the first protrusion 41T, but the rear end of the lower rail 42 may be inclined in the same manner as the rear surface of the second protrusion 42T, and the rear end of the lower rail 42 may be configured to slide against the front surface of the first protrusion 41T. In this case, the second protrusion 42T is not necessary. With this configuration, the same function as in the above embodiment is achieved.

[0054] In the above embodiment, an example was shown in which the first protrusion 41T was provided on the lower surface of the upper rail 41, but the first protrusion 41T may be provided on the lower surface of the developer holder 70 without providing the upper rail 41. With this configuration, the same function as in the above embodiment is achieved.

[0055] In the above embodiment, the link member 43 has the shaft hole 43A that is supported coaxially with the hinge 3H of the inner cover 3C, but the link member 43 does not have to have the shaft hole 43A. This configuration achieves the same function as the above embodiment. Incidentally, the provision of the shaft hole 43A can suppress deformation of the inner cover 3C when it is opened and closed.

[0056] In the above embodiment, an example is shown in which the inner cover 3C is provided behind the outer cover 3B, but the outer cover 3B may also serve as the inner cover 3C. [Explanation of symbols]

[0057] 100 Image forming device 11 Photoconductor drum 14 Developing device 3A opening 3C Inner cover (cover) 3H Hinge 32 Developing roller 41T First protrusion 42 Lower rail (slide member) 42T 2nd protrusion 42B Boss 43 Link member 43V groove 43V1 1st Section 43V2 2nd Section 50 Drum Unit 70 Developing Holder

Claims

1. a drum unit having a photosensitive drum; a developing device having a developing roller disposed so that the outer circumferential surfaces of the photosensitive drum and the developing roller face each other; a developing holder to which the developing device is attached and detached, the developing roller being swung to move toward and away from the photosensitive drum; a slide member that slides in an axial direction of the developing roller; an opening into which the developing device is inserted; a cover coupled to the opening via a hinge and to which the slide member is connected; 、 The sliding member slides from a first position to a second position in conjunction with an operation of closing the cover, and the sliding member slides from the second position to the first position in conjunction with an operation of opening the cover, the developing holder swings in conjunction with the sliding of the sliding member from the first position to the second position so that the developing roller approaches the photosensitive drum; the developing holder swings in conjunction with the sliding of the sliding member from the second position to the first position so that the developing roller is separated from the photosensitive drum; a boss protruding from an end of the slide member on the cover side in an axial direction of the hinge; a link member provided inside the cover and swinging together with the cover when the cover is opened or closed; a groove provided in the link member and adapted to slide against the tip of the boss when the cover is opened or closed; The groove is A first section having an arc shape centered on an axis of the hinge; a second section that is continuous with the end of the first section on the cover side and has a smaller radius of curvature than the first section, When the cover is swung within a range from a fully open position to a predetermined position between the fully open position and the fully closed position, the first section slides relative to the boss while the slide member is positioned at the first position, An image forming apparatus characterized in that when the cover is pivoted within a range from the specified position to the fully closed position, the second section slides against the boss, causing the sliding member to slide between the first position and the second position.

2. the slide member is provided below the developing holder, the developing holder includes a first protrusion protruding downward, The slide member includes a second protrusion protruding upward, When the slide member is located at the first position, the first protrusion is not in contact with the second protrusion, 2. The image forming apparatus according to claim 1, wherein when the sliding member slides from the first position to the second position, the first convex portion pushes aside the second convex portion, thereby oscillating the developing holder so that the developing roller approaches the photosensitive drum.

Images