Image formation apparatus

Abstract

To provide an image formation apparatus capable of equalizing a gap between a photoreceptor drum and a developing roller in the axial direction.SOLUTION: An image formation apparatus includes: a photoreceptor housing 20 for rotatably supporting a photoreceptor drum around the axis; a development housing 30 for rotatably supporting a developing roller around the axis; a first contact member 40 provided in both end parts of the photoreceptor housing 20 in the axial direction; and a second contact member 50 provided in both end parts of the development housing 30 in the axial direction and contacting the first contact member 40. The photoreceptor housing 20 includes first welding projections 46 and 47 projected on the outside from both end parts in the axial direction; the first contact member 40 includes a first long hole part long formed in a disconnection direction A compared with the first welding projections 46 and 47; and the first contact member 40 is fixed to the photoreceptor housing 20 by welding the first welding projections 46 and 47 to the first contact member 40 in the state of penetrating the first long hole part.SELECTED DRAWING: Figure 8

Description

[Technical field]

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

[0002] In an electrophotographic image forming apparatus, it is important to maintain the gap between the developing roller and the photosensitive drum uniform along the axial direction. For example, an image forming apparatus is known that includes a first contact member provided at both axial ends of a photosensitive housing that supports the photosensitive drum, and a second contact member provided at both axial ends of a developing housing that supports the developing roller and that contacts the first contact member (Patent Document 1). The first contact member and the second contact member each have a plurality of elongated hole portions, and are fixed to the respective housings by screws via the plurality of elongated hole portions. The positions of the first contact member and the second contact member are adjusted along the longitudinal direction of the plurality of elongated hole portions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2023-23110 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned technology, since each contact member is screwed to each housing, the contact members may rotate with the rotation of the screws and become displaced from their proper mounting positions, making it difficult to make the distance between the photosensitive drum and the developing roller uniform along the axial direction.

[0005] In consideration of the above circumstances, the present invention provides an image forming apparatus in which the distance between the photosensitive drum and the developing roller is made uniform along the axial direction. [Means for solving the problem]

[0006] The image forming apparatus according to the present invention includes a photosensitive drum that holds a latent image, a photosensitive housing that supports the photosensitive drum rotatably around an axis, a developing roller that holds a developer, a developing housing that supports the developing roller rotatably around an axis while facing the photosensitive drum, a pair of first contact members provided at both ends of the photosensitive housing in the axial direction in which the photosensitive drum extends, and a pair of second contact members provided at both ends of the developing housing in the axial direction and contacting the pair of first contact members by pressing the developing housing toward the photosensitive housing, wherein the photosensitive housing has a pair of first welding protrusions protruding outward from both ends in the axial direction, and the first contact members have a first elongated hole portion that is longer in the contact and separation direction along a straight line connecting the axial center of the photosensitive drum and the axial center of the developing roller than the first welding protrusions, and the first welding protrusions are welded to the first contact members with the first welding protrusions passing through the first elongated hole portions, thereby fixing the first contact members to the photosensitive housing.

[0007] Another image forming apparatus according to the present invention includes a photosensitive drum that holds a latent image, a photosensitive housing that supports the photosensitive drum rotatably around an axis, a developing roller that holds a developer, a developing housing that supports the developing roller rotatably around an axis while facing the photosensitive drum, a pair of first contact members provided at both ends of the photosensitive housing in the axial direction in which the photosensitive drum extends, and a pair of second contact members provided at both ends of the developing housing in the axial direction and contacting the pair of first contact members by pressing the developing housing toward the photosensitive housing, wherein the developing housing has a pair of second welding protrusions protruding outward from both ends in the axial direction, and the second contact members have a second elongated hole portion that is longer in the contact and separation direction along a straight line connecting the axial center of the photosensitive drum and the axial center of the developing roller than the second welding protrusions, and the second welding protrusions are welded to the second contact members with the second welding protrusions passing through the second elongated hole portions, thereby fixing the second contact members to the developing housing.

[0008] Another image forming apparatus according to the present invention includes a photosensitive drum for holding a latent image, a photosensitive housing for supporting the photosensitive drum rotatably about an axis, a developing roller for holding a developer, a developing housing for supporting the developing roller rotatably about an axis while facing the photosensitive drum, a pair of first contact members provided at both ends of the photosensitive housing in an axial direction in which the photosensitive drum extends, and a pair of second contact members provided at both ends of the developing housing in the axial direction and contacting the pair of first contact members by pressing the developing housing toward the photosensitive housing, wherein the photosensitive housing has a pair of first welding protrusions protruding outward from both ends in the axial direction. the developing housing has a pair of second welding protrusions protruding outward from both ends in the axial direction, the first contact member has a first elongated hole portion formed longer in the contact-separation direction along a straight line connecting the axis of the photosensitive drum and the axis of the developing roller than the first welding protrusions, and the second contact member has a second elongated hole portion formed longer in the contact-separation direction than the second welding protrusions, and the first contact member is fixed to the photosensitive housing by being welded to the first contact member with the first welding protrusions passing through the first elongated hole portions, and the second contact member is fixed to the developing housing by being welded to the second contact member with the second welding protrusions passing through the second elongated hole portions.

[0009] The welded first welded protrusion is filled into the first long hole portion, has an outer diameter larger than that of the first long hole portion on the surface of the first contact member, and sandwiches the first contact member between itself and the axial end of the photosensitive body housing.

[0010] The first oblong hole has a first tapered portion formed by chamfering a peripheral portion on a front surface side, The first welded protrusion may be filled into the first slotted hole including the first tapered portion.

[0011] The welded second welded protrusion is filled into the second long hole portion, has an outer diameter larger than that of the second long hole portion on the surface of the second contact member, and sandwiches the second contact member between itself and the axial end of the developing housing.

[0012] The second slotted hole has a second tapered portion formed by chamfering a peripheral portion on a front surface side, The second welded protrusion may be filled into the second slotted hole including the second tapered portion.

[0013] The welded first welded protrusion is filled into the first long hole portion, has a larger outer diameter than the first long hole portion on the surface of the first contact member, and sandwiches the first contact member between the first long hole portion and the axial end of the photosensitive housing, and the welded second welded protrusion is filled into the second long hole portion, has a larger outer diameter than the second long hole portion on the surface of the second contact member, and sandwiches the second contact member between the first long hole portion and the axial end of the developing housing.

[0014] The first long hole portion has a first tapered portion formed by chamfering the peripheral portion on the surface side, and the welded first welded protrusion is filled into the first long hole portion including the first tapered portion, and the second long hole portion has a second tapered portion formed by chamfering the peripheral portion on the surface side, and the welded second welded protrusion is filled into the second long hole portion including the second tapered portion. Effect of the Invention

[0015] According to the present invention, the gap between the photosensitive drum and the developing roller can be made uniform along the axial direction. [Brief description of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view (front view) showing an outline of the inside of an image forming apparatus according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing a photoconductor unit according to an embodiment of the present invention. [Diagram 3]FIG. 2 is a perspective view showing a developing device according to an embodiment of the present invention. [Figure 4] FIG. 2 is a cross-sectional view (front view) showing a schematic internal configuration of a photoconductor unit and a developing device according to one embodiment of the present invention. [Diagram 5] FIG. 2 is a perspective view showing a first contact member according to an embodiment of the present invention. [Figure 6] FIG. 4 is a perspective view showing a second contact member according to one embodiment of the present invention. [Figure 7] FIG. 2 is a perspective view showing the front portion of a photoconductor unit and a developing device according to an embodiment of the present invention. [Figure 8] 1 is a perspective view showing a gap adjustment structure according to an embodiment of the present invention; [Figure 9] 5A to 5C are cross-sectional views that diagrammatically show a process of welding a first welding protrusion to a first contact member according to an embodiment of the present invention. [Figure 10] 5 is a cross-sectional view showing a schematic state in which a first welding protrusion according to an embodiment of the present invention is welded to a first contact member. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings. Note that Fr, Rr, L, R, U, and D shown in the drawings indicate front, rear, left, right, top, and bottom. Terms indicating directions and positions are used in this specification, but these terms are used for convenience of explanation and do not limit the technical scope of the present invention.

[0018] [Image forming equipment] An image forming apparatus 1 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view (front view) showing an outline of the inside of the image forming apparatus 1.

[0019] The image forming apparatus 1 is a color printer that forms an image by transferring a full-color toner image formed by an electrophotographic method onto paper S (medium). The image forming apparatus 1 includes an apparatus main body 2 that has a substantially rectangular parallelepiped appearance. A cassette 3 that stores paper S is removably provided at the bottom of the apparatus main body 2, and a paper output tray 4 onto which paper S with an image formed thereon is output is provided on the top surface of the apparatus main body 2. Four toner containers 5 that store refill toner (developer) of four colors (magenta, cyan, yellow, and black) are removably attached below the paper output tray 4. The medium is not limited to paper S made of paper, and may be a resin sheet or the like.

[0020] On the right side inside the device body 2, a transport path 6 and a reversing transport path 7 are formed as paths for transporting the paper S. The transport path 6 is formed in a roughly S-shape along the vertical direction, and is a path for transporting the paper S from the cassette 3 to the paper output tray 4. The reversing transport path 7 branches off to the right on the downstream side of the transport path 6, extends downward, and merges with the upstream side of the transport path 6. The reversing transport path 7 is a path for reversing the paper S and transporting it again to the imaging device 11 described below. In this specification, the terms "upstream" and "downstream" refer to "upstream" and "downstream" in the transport direction of the paper S (medium).

[0021] Inside the device main body 2, there are provided a paper feeder 10, an image forming device 11, and a fixing device 12. The paper feeder 10 is provided at the upstream end of the transport path 6, and sends out the paper S stored in the cassette 3 one sheet at a time to the transport path 6. The fixing device 12 is provided on the downstream side of the transport path 6, and applies pressure to the toner image on the paper S while heating it, thereby thermally fixing the toner image onto the paper S. The imaging device 11 is provided midway between the paper feeder 10 and the fixing device 12 on the transport path 6.

[0022] <Imaging device> The imaging device 11 has an intermediate transfer belt 13, four imaging main units 14, and an optical scanning device 15. The intermediate transfer belt 13 is provided below the toner container 5, stretched over a number of rollers, and rotates in the direction indicated by the arrow in FIG. 1. The four imaging main units 14 correspond to the four colors of toner, and are arranged in the left-right direction below the intermediate transfer belt 13. The optical scanning device 15 is provided below the imaging main units 14. Note that the four imaging main units 14 have the same structure, so the following description will be given of one imaging main unit 14.

[0023] The image forming main body 14 has a photoconductor unit 16, a developing device 23, and a primary transfer roller 24. The photoconductor unit 16 has a photoconductor drum 21, a charging device 22, and a cleaning device 25. The photoconductor drum 21 rotates around its axis while contacting the underside of the intermediate transfer belt 13. The charging device 22, the developing device 23, the primary transfer roller 24, and the cleaning device 25 are arranged around the photoconductor drum 21 in the order of the image forming process. The primary transfer roller 24 faces the photoconductor drum 21 from above, sandwiching the intermediate transfer belt 13 therebetween. A secondary transfer roller 26 contacts the right end of the intermediate transfer belt 13 to form a transfer nip. A pair of registration rollers 27 is provided upstream of the secondary transfer roller 26.

[0024] [Image formation processing] Here, a description will be given of the operation of the image forming apparatus 1. For example, a control unit (not shown) executes image forming processing as follows, based on image data input from an external terminal.

[0025] The charging device 22 charges the surface of the photoconductor drum 21. The optical scanning device 15 exposes the photoconductor drum 21 to light, and forms a latent image corresponding to image data on the surface of the photoconductor drum 21. The developing device 23 develops the latent image held on the surface of the photoconductor drum 21 into a toner image using toner supplied from the toner container 5. The four-color toner images held on the four photoconductor drums 21 are sequentially transferred to the rotating intermediate transfer belt 13 by the primary transfer roller 24 to which a primary transfer bias is applied. The intermediate transfer belt 13 holds a full-color toner image in which the four-color toner images are superimposed while rotating. The cleaning device 25 removes the toner remaining on the surface of the photoconductor drum 21 after the primary transfer.

[0026] The paper feeder 10 takes out the paper S stored in the cassette 3 and sends it out to the transport path 6. The pair of registration rollers 27 temporarily blocks the paper S to correct skew, and then sends the paper S downstream. A secondary transfer roller 26 to which a secondary transfer bias is applied performs a second transfer of the toner image on the intermediate transfer belt 13 onto the surface of the paper S passing through the transfer nip. The fixing device 12 applies pressure to the toner image transferred to the paper S and heats it to thermally fix it onto the paper S. In the case of single-sided printing, the paper S with the fixed toner image (image formed) is discharged to the paper output tray 4.

[0027] When double-sided printing is performed, the paper S that has passed through the fixing device 12 switches back at the downstream end of the conveying path 6 and is sent to the reversing conveying path 7. The paper S that has been conveyed along the reversing conveying path 7 re-enters the conveying path 6, and an image is formed on the back side of the paper S in the same procedure as in the single-sided printing described above.

[0028] Next, the photoconductor unit 16 and the developing device 23 will be described with reference to Fig. 1 to Fig. 4. Fig. 2 is a perspective view showing the photoconductor unit 16. Fig. 3 is a perspective view showing the developing device 23. Fig. 4 is a cross-sectional view (front view) that shows a schematic internal configuration of the photoconductor unit 16 and the developing device 23.

[0029] <Photoconductor unit> As shown in FIG. 1, FIG. 2, and FIG. 4, the photoconductor unit 16 is a photoconductor drum 21, a charging device 22, and a cleaning device 25 housed in a photoconductor housing 20 and integrated into one unit. The photoconductor housing 20 is made of, for example, synthetic resin, and is formed in a box shape elongated in the front-rear direction (axial direction). The photoconductor housing 20 supports the photoconductor drum 21 so that it can rotate around its axis. The device main body 2 is provided with a support frame 2A, and the support frame 2A is provided with a housing support part 2B into which the lower part of the photoconductor housing 20 is fitted (see FIG. 4). The photoconductor drum 21 is formed in a cylindrical shape elongated in the front-rear direction (axial direction). The rotating shaft 21A of the photoconductor drum 21 is supported by bearings (not shown) provided at both ends of the photoconductor housing 20 in the front-rear direction. Both ends of the rotating shaft 21A in the front-rear direction protrude outward from both ends of the photoconductor housing 20 in the front-rear direction (see FIG. 2). The charging device 22 is in contact with the underside of the photoconductor drum 21, and the cleaning device 25 is in contact with the right side of the photoconductor drum 21 (see FIG. 4).

[0030] <Developing device> As shown in FIGS. 3 and 4, the developing device 23 is configured by integrating two screws 32 and a developing roller 31 housed in a developing housing 30.

[0031] (developing housing) The developer housing 30 is made of, for example, synthetic resin, and is formed in a box shape elongated in the front-rear direction (axial direction). The developer is stored in the bottom of the developer housing 30. The developer is, for example, a two-component developer containing a magnetic carrier and a non-magnetic toner. The developer housing 30 supports two screws 32 and a developer roller 31 so that they can rotate around an axis. An opening 30A is opened in the upper right part of the developer housing 30, which exposes a part of the outer circumferential surface of the developer roller 31. A blade 33 is provided on the lower edge of the opening 30A to regulate the layer thickness of the developer held by the developer roller 31.

[0032] (screw) As shown in FIG. 4, the two screws 32 are arranged in the left-right direction inside the lower side of the developer housing 30 and extend in the front-rear direction (axial direction) approximately parallel to each other. The developer housing 30 is provided with a partition wall portion 30B that separates the two screws 32. On both sides of the partition wall portion 30B in the front-rear direction, a gap (not shown) is formed to allow the developer to flow. The two screws 32 transport the developer in opposite directions. The developer circulates inside the lower side of the developer housing 30 while being stirred by the two screws 32. The developer is stirred by the screws 32, and the toner is triboelectrically charged.

[0033] (Developing roller) The developing roller 31 is disposed above the right screw 32 and extends in the front-rear direction (axial direction) so as to be approximately parallel to the screw 32. The developing roller 31 is formed into a cylindrical shape as a whole by covering a permanent magnet with a non-magnetic sleeve. The rotating shaft 31A of the developing roller 31 is supported by bearings (not shown) provided at both ends in the front-rear direction of the developing housing 30. Both ends in the front-rear direction of the rotating shaft 31A protrude outward from both ends in the front-rear direction of the developing housing 30 (see FIG. 3). The (surface of) the developing roller 31 is exposed from the opening 30A and faces the (surface of) the photoconductor drum 21 approximately parallel. The developing roller 31 holds the developer, and the developer forms a magnetic brush on the surface of the developing roller 31. The thickness of the magnetic brush is adjusted by the blade 33.

[0034] As shown in FIG. 4, the right lower portion of the developing housing 30 is rotatably supported by the support frame 2A via a fulcrum portion 34. The left lower portion of the developing housing 30 is connected to the support frame 2A via a biasing member 35. The biasing member 35 is, for example, a compression coil spring, and biases the developing housing 30 upward. The developing housing 30 is biased by the biasing member 35 and rotates around the fulcrum portion 34 in a direction approaching the photosensitive unit 16 (photosensitive drum 21) (clockwise in FIG. 4). This causes the developing roller 31 to approach (contact) the photosensitive drum 21. On the other hand, when the developing housing 30 rotates counterclockwise around the fulcrum portion 34 and compresses the biasing member 35, the developing roller 31 moves away from the photosensitive drum 21.

[0035] Incidentally, in order to develop the latent image held on the surface of the photoconductor drum 21 into an appropriate toner image, it is important to make the gap (distance) between the photoconductor drum 21 and the developing roller 31 uniform in the front-rear direction (axial direction). Therefore, the image forming apparatus 1 according to this embodiment is provided with a gap adjustment structure 18 that adjusts the gap between the photoconductor drum 21 and the developing roller 31. In this specification, "uniform" does not only mean completely equal, but also means allowing for a very slight deviation (error) that does not cause any fluctuation in image quality.

[0036] [Space adjustment structure] Next, the gap adjustment structure 18 will be described with reference to Fig. 5 to Fig. 8. Fig. 5 is a perspective view showing the first contact member 40. Fig. 6 is a perspective view showing the second contact member 50. Fig. 7 is a perspective view showing the front parts of the photoconductor unit 16 and the developing device 23. Fig. 8 is a perspective view showing the gap adjustment structure 18.

[0037] The gap adjustment structure 18 has a pair of first contact members 40 provided at both ends of the photosensitive body housing 20 in the front-rear direction (axial direction), and a pair of second contact members 50 provided at both ends of the developer housing 30 in the front-rear direction. Since the pair of first contact members 40 have a shape symmetrical in the front-rear direction, this specification will mainly describe one (front) first contact member 40. Similarly, this specification will mainly describe one (front) second contact member 50. Also, in this specification, when the first contact member 40 and the second contact member 50 are described together, the terms "first" and "second" are omitted and they are called "contact members 40, 50". Similarly, for components with the terms "first" and "second" attached, the terms "first" and "second" are omitted as appropriate. Also, in this specification, when the photosensitive body housing 20 and the developer housing 30 are described together, they are called "housings 20, 30". Further, although there are slight differences in the structures of both ends in the front-rear direction of the photoconductor unit 16, they are generally the same, and therefore, in Figures 7 and 8, only the front portion of the photoconductor unit 16 is shown. Similarly, in Figures 7 and 8, only the front portion of the developing device 23 is shown.

[0038] As shown in Fig. 5, Fig. 6 and Fig. 8, the first contact member 40 and the second contact member 50 are each formed in a substantially rectangular plate shape extending in the contact direction A along a straight line connecting the axis of the photosensitive drum 21 (rotation shaft 21A) and the axis of the developing roller 31 (rotation shaft 31A). In this embodiment, the rotation shaft 21A of the photosensitive drum 21 is located slightly above the rotation shaft 31A of the developing roller 31, so the contact direction A is inclined upward from the developing roller 31 toward the photosensitive drum 21 (see Fig. 8, etc.). Therefore, the first contact member 40 and the second contact member 50 are inclined along the contact direction A (see Fig. 8, etc.).

[0039] <First contact member> As shown in FIG. 5, the left end of the first contact member 40 is provided with a first contact surface 41, the central portion of which in the vertical direction bulges out to the left in an arch shape. The first contact member 40 is provided with a first opening 42, a first jig insertion portion 43, and a first long hole portion 44, which are formed in this order from left to right. The first contact member 40 is also provided with a portion that protrudes downward between the first contact surface 41 and the first opening 42, and a first long hole portion 45 is formed in the protruding portion. The first opening 42, the first jig insertion portion 43, and the first long hole portions 44, 45 are each a hole that penetrates the first contact member 40 in the thickness direction (front-rear direction). In this embodiment, the first long hole portion 44 is formed larger than the first long hole portion 45, but the sizes of the first long hole portions 44, 45 may be freely changed.

[0040] The first opening 42 is a generally circular hole having an inner diameter larger than the outer diameter of the rotation shaft 21A of the photoconductor drum 21. The first jig insertion portion 43 is a generally elliptical (approximately rectangular) long hole whose major axis is in a direction perpendicular to the contact / separation direction A (approximately the vertical direction).

[0041] The first oblong hole portions 44, 45 are substantially elliptical (substantially rectangular) oblong holes with the long diameter in the contact direction A (substantially left-right direction). The first oblong hole portions 44, 45 have an arc-shaped curved surface portion facing the contact direction A and a flat surface portion facing in a direction perpendicular to the contact direction A. The flat surface portion is substantially parallel to the contact direction A. The first oblong hole portions 44, 45 are formed with first tapered portions 44A, 45A by chamfering the peripheral edge portion on the front side (the outer surface side that does not contact the end of the photosensitive body housing 20). The first tapered portions 44A, 45A are formed so that the diameter (long diameter and short diameter) gradually decreases from the front side of the first oblong hole portions 44, 45 to substantially the center in the axial direction (front-rear direction). The back side (the contact surface side that comes into contact with the end of the photosensitive housing 20) of the first long hole portions 44, 45 is formed in an approximately cylindrical shape, and the front side of the first long hole portions 44, 45 is formed in an approximately conical shape widened by the first tapered portions 44A, 45A.

[0042] (First welding convex part) As shown in Fig. 7, the photoconductor housing 20 has a pair of first welded protrusions 46 and a pair of first welded protrusions 47 protruding outward from both ends in the front-rear direction (axial direction). Since the pair of first welded protrusions 46 have a shape symmetrical in the front-rear direction, this specification will mainly describe one (front) first welded protrusion 46. Similarly, this specification will mainly describe one (front) first welded protrusion 47. In this embodiment, the first welded protrusion 46 is formed larger than the first welded protrusion 47, but the sizes of the first welded protrusions 46, 47 may be freely changed.

[0043] The first welding protrusions 46, 47 are made of, for example, a synthetic resin having thermoplasticity, and are formed integrally with the photoconductor housing 20. The first welding protrusions 46, 47 are provided at positions corresponding to the first long hole portions 44, 45 of the first contact member 40. The first welding protrusions 46, 47 are formed in a substantially cylindrical shape that can be inserted into the first long hole portions 44, 45 with some play. The first welding protrusions 46, 47 are formed longer than the thickness (dimension in the front-rear direction) of the first contact member 40. The above-mentioned first long hole portion 44 is formed longer in the contact direction A than the first welding protrusion 46, and the first long hole portion 45 is formed longer in the contact direction A than the first welding protrusion 47 (see FIG. 5). The first welding protrusions 46, 47 may be formed of the same synthetic resin as the photoconductor housing 20, or may be formed of a synthetic resin different from the photoconductor housing 20.

[0044] Although the details will be described later, both ends of the rotating shaft 21A of the photosensitive drum 21 are inserted into the first opening 42 of the first contact member 40. The first welding protrusions 46, 47 are inserted into the first long hole portions 44, 45 of the first contact member 40. In FIG. 5, the rotating shaft 21A and the first welding protrusions 46, 47 are shown by two-dot chain lines. The first welding protrusions 46, 47 are disposed substantially in the center of the first long hole portions 44, 45 in the contact direction A (left-right direction), and an adjustment allowance M (margin) is provided on both sides of the first welding protrusions 46, 47 in the contact direction A (only the first long hole portion 44 is shown in FIG. 5). In addition, a gap wider than the adjustment allowance M is provided over the entire circumference between the first opening 42 and the rotating shaft 21A of the photosensitive drum 21.

[0045] <Second contact member> The second contact member 50 has a shape generally the same as that of the first contact member 40. As shown in FIG. 6, the right end of the second contact member 50 is provided with a second contact surface 51, the central portion of which in the vertical direction bulges out to the right in an arch shape. The second contact member 50 is provided with a second opening 52, a second jig insertion portion 53, and a second long hole portion 54, which are formed in this order from right to left. The second contact member 50 is also provided with a portion that protrudes downward between the second contact surface 51 and the second opening 52, and a second long hole portion 55 is formed in the protruding portion. The second opening 52, the second jig insertion portion 53, and the second long hole portions 54, 55 are each a hole that penetrates the second contact member 50 in the thickness direction (front-rear direction). In this embodiment, the second long hole portion 54 is formed larger than the second long hole portion 55, but the size of the second long hole portions 54, 55 may be freely changed.

[0046] The second opening 52 is a generally circular hole having an inner diameter larger than the outer diameter of the rotation shaft 31A of the developing roller 31. The second jig insertion portion 53 is a generally elliptical (approximately rectangular) long hole with a major axis in a direction (approximately the up-down direction) perpendicular to the contact / separation direction A. The distance between the second contact surface 51 and the second opening 52 is shorter than the distance between the first contact surface 41 and the first opening 42.

[0047] The second oblong hole portions 54, 55 are substantially elliptical (substantially rectangular) oblong holes with the long diameter in the contact direction A (substantially left-right direction). The second oblong hole portions 54, 55 have an arc-shaped curved surface portion facing the contact direction A and a flat surface portion facing in a direction perpendicular to the contact direction A. The flat surface portion is substantially parallel to the contact direction A. The second oblong hole portions 54, 55 have second tapered portions 54A, 55A formed by chamfering the peripheral edge portion on the surface side (the outer surface side that does not contact the end of the development housing 30). The second tapered portions 54A, 55A are formed so that the diameter (long diameter and short diameter) gradually decreases from the surface side of the second oblong hole portions 54, 55 to substantially the center in the axial direction (front-rear direction). The back side of the second long hole portions 54, 55 (the contact surface side that comes into contact with the end of the development housing 30) is formed approximately cylindrical, and the front side of the second long hole portions 54, 55 is formed approximately conical, widened by the second tapered portions 54A, 55A.

[0048] (Second welding convex part) 7, the development housing 30 has a pair of second welded protrusions 56 and a pair of second welded protrusions 57 protruding outward from both ends in the front-rear direction (axial direction). Since the pair of second welded protrusions 56 have a shape symmetrical in the front-rear direction, this specification will mainly describe one (front) second welded protrusion 56. Similarly, this specification will mainly describe one (front) second welded protrusion 57. In this embodiment, the second welded protrusion 56 is formed larger than the second welded protrusion 57, but the sizes of the second welded protrusions 56, 57 may be freely changed.

[0049] The second welding protrusions 56, 57 are made of, for example, a synthetic resin having thermoplasticity, and are formed integrally with the development housing 30. The second welding protrusions 56, 57 are provided at positions corresponding to the second long hole portions 54, 55 of the second contact member 50. The second welding protrusions 56, 57 are formed in a substantially cylindrical shape that can be inserted into the second long hole portions 54, 55 with some play. The second welding protrusions 56, 57 are formed longer than the thickness (dimension in the front-rear direction) of the second contact member 50. The above-mentioned second long hole portion 54 is formed longer in the contact direction A than the second welding protrusion 56, and the second long hole portion 55 is formed longer in the contact direction A than the second welding protrusion 57 (see FIG. 6). The second welding protrusions 56, 57 may be formed of the same synthetic resin as the development housing 30, or may be formed of a synthetic resin different from that of the development housing 30.

[0050] Although the details will be described later, both ends of the rotation shaft 31A of the developing roller 31 are inserted into the second opening 52 of the second contact member 50. The second welding protrusions 56, 57 are inserted into the second long hole portions 54, 55 of the second contact member 50. In FIG. 6, the rotation shaft 31A and the second welding protrusions 56, 57 are shown by two-dot chain lines. The second welding protrusions 56, 57 are disposed substantially in the center of the second long hole portions 54, 55 in the contact direction A (left-right direction), and adjustment allowances M (margins) are provided on both sides of the second welding protrusions 56, 57 in the contact direction A (only the second long hole portion 54 is shown in FIG. 6). In addition, a gap wider than the adjustment allowance M is provided over the entire circumference between the second opening 52 and the rotation shaft 31A of the developing roller 31.

[0051] [Adjusting the gap between the photoconductor drum and the developing roller] Next, referring to Figs. 8 to 10, a procedure for fixing the contact members 40, 50 to the housings 20, 30 and adjusting the gap between the photosensitive drum 21 and the developing roller 31 will be described. Fig. 9 is a cross-sectional view that typically shows the process of welding the first welding protrusion 46 to the first contact member 40. Fig. 10 is a cross-sectional view that typically shows the state in which the first welding protrusion 46 is welded to the first contact member 40. Note that the photosensitive unit 16 and the developing device 23 are both in an assembled state. In addition, the process of welding the welding protrusions 46, 47, 56, 57 to the contact members 40, 50 and the state after welding are substantially the same, so Figs. 9 and 10 only show the first elongated hole portion 44 (first welding protrusion 46) of the first contact member 40.

[0052] First, the worker supports the photoconductor unit 16 and the developing device 23 on dedicated work tables (not shown) prepared for the assembly. Next, the worker places the first contact member 40 at the end of the photoconductor housing 20 in the front-rear direction, passes the rotating shaft 21A through the first opening 42, and passes the first welding protrusions 46, 47 through the first long hole portions 44, 45. The worker also places the second contact member 50 at the end of the developing housing 30 in the front-rear direction, passes the rotating shaft 31A through the second opening 52, and passes the second welding protrusions 56, 57 through the second long hole portions 54, 55. The welding protrusions 46, 47, 56, 57 protrude outward from the surfaces of the contact members 40, 50 (see FIG. 9). The photoconductor unit 16 and the developing device 23 may be assembled separately.

[0053] Next, the worker inserts a jig (not shown) into the first jig insertion portion 43 and the second jig insertion portion 53. By inserting the jig into the jig insertion portions 43 and 53, the contact members 40 and 50 are moved in the contact / separation direction A within the range of the adjustment margin M with the welding protrusions 46, 47, 56 and 57, respectively. As a result, when the photosensitive unit 16 is supported by the housing support portion 2B of the support frame 2A and the developing device 23 is supported via the fulcrum portion 34 and the urging member 35, the second contact surface 51 of the second contact member 50 comes into contact with the first contact surface 41 of the first contact member 40, and the distance between the photosensitive drum 21 and the developing roller 31 is adjusted to an appropriate position (see FIG. 8).

[0054] Next, the worker brings the welding horn 90 into contact with the welding protrusions 46, 47, 56, 57 that penetrate the elongated hole portions 44, 45, 54, 55 of the contact members 40, 50 (see FIG. 9), and welds (ultrasonic welds) the welding protrusions 46, 47, 56, 57 to the contact members 40, 50 (see FIG. 8 and FIG. 10). The welding protrusions 46, 47, 56, 57 melt and fill the elongated hole portions 44, 45, 54, 55, and then cool and harden in a state of being in close contact with the inner circumferential surfaces of the elongated hole portions 44, 45, 54, 55 (see FIG. 10). The welded first welding protrusions 46, 47 fill the first elongated hole portions 44, 45 including the first tapered portions 44A, 45A (see FIG. 10). The welded first welding protrusions 46, 47 have an outer diameter larger than the first long hole portions 44, 45 (first tapered portions 44A, 45A) on the surface of the first contact member 40, and sandwich the first contact member 40 between the first welding protrusions 46, 47 and the end of the photosensitive housing 20 in the front-rear direction (axial direction) (see FIG. 10). As with the first welding protrusions 46, 47, the welded second welding protrusions 56, 57 are filled in the second long hole portions 54, 55 including the second tapered portions 54A, 55A. The welded second welding protrusions 56, 57 have an outer diameter larger than the second long hole portions 54, 55 (first tapered portions 44A, 45A) on the surface of the second contact member 50, and sandwich the second contact member 50 between the first welding protrusions 46, 47 and the end of the photosensitive housing 30 in the front-rear direction (axial direction). The welding protrusions 46, 47, 56, 57 that extend radially on the surfaces of the contact members 40, 50 are formed in a substantially circular plate shape (see FIG. 8).

[0055] As a result, the contact members 40, 50 are fixed to the housings 20, 30 in a positionally adjusted state (see FIG. 8). The developing housing 30 is pushed toward the photoconductor housing 20 by the biasing member 35, so that the second contact surface 51 of the second contact member 50 comes into contact (with pressure) with the first contact surface 41 of the first contact member 40. This maintains the gap between the photoconductor drum 21 and the developing roller 31 in an appropriately adjusted state. In this specification, "welding" refers to a joining technique in which the melted portion after joining cannot be identified from the outside. In addition, in this embodiment, the welding protrusions 46, 47, 56, 57 are ultrasonically welded, but this is not limiting, and other welding techniques such as high-frequency welding and heat welding may be adopted.

[0056] In the image forming apparatus 1 according to the present embodiment described above, the welding protrusions 46, 47, 56, 57 are welded to the contact members 40, 50 while passing through the long holes 44, 45, 54, 55, so that the contact members 40, 50 are fixed to the housings 20, 30 (see FIG. 8). With this configuration, the contact members 40, 50 can be fixed to the housings 20, 30 without applying an external force such as a screw rotation force to the contact members 40, 50. This prevents the contact members 40, 50 from rotating together, as occurs when the contact members 40, 50 are screwed to the housings 20, 30, and the contact members 40, 50 can be attached at appropriate positions. As a result, the distance between the photosensitive drum 21 and the developing roller 31 can be made uniform in the axial direction.

[0057] Moreover, according to the image forming apparatus 1 according to the present embodiment, the welded protrusions 46, 47, 56, 57 fill the elongated hole portions 44, 45, 54, 55 after welding (see FIG. 10), so that the movement of the contact members 40, 50 in the contact / separation direction A can be prevented. Furthermore, the welded protrusions 46, 47, 56, 57 that spread radially on the surfaces of the contact members 40, 50 sandwich the contact members 40, 50 between the housings 20, 30 (see FIG. 10), so that the movement of the contact members 40, 50 in the front-rear direction (axial direction) can be prevented. As a result, the first contact member 40 and the second contact member 50 that are firmly fixed to the housings 20, 30 can be butted against each other, so that the distance (gap) between the photosensitive drum 21 and the developing roller 31 can be kept constant.

[0058] Furthermore, according to the image forming apparatus 1 of this embodiment, the tapered portions 44A, 45A, 54A, 55A are formed in the oblong hole portions 44, 45, 54, 55 (see FIGS. 5 and 6), so that it is possible to increase the area of ​​contact between the welded welding protrusions 46, 47, 56, 57 and the inner circumferential surfaces (including the tapered portions 44A, 45A, 54A, 55A) of the oblong hole portions 44, 45, 54, 55. This makes it possible to strengthen the state in which the contact members 40, 50 are fixed to the housings 20, 30, and the force pressing the developing housing 30 toward the photosensitive member housing 20 can be firmly received by the contact members 40, 50.

[0059] In the image forming apparatus 1 according to the present embodiment, the joining means of both the first contact member 40 and the second contact member 50 are welded, but the present invention is not limited to this. For example, only the joining means of the first contact member 40 to the photosensitive housing 20 may be welded, and a screw hole may be formed in the axial end of the developing housing 30 instead of the second welding protrusions 56, 57, and the second contact member 50 may be fixed to the developing housing 30 with a screw (not shown). In this case, for example, after the second contact member 50 is fixed to the developing housing 30 with a screw, the first welding protrusions 46, 47 may be welded to the first contact member 40. Also, for example, only the joining means of the second contact member 50 to the developing housing 30 may be welded, and a screw hole may be formed in the axial end of the photosensitive housing 20 instead of the first welding protrusions 46, 47, and the first contact member 40 may be fixed to the photosensitive housing 20 with a screw (not shown). In this case, for example, after the first contact member 40 is fixed to the photoconductor housing 20 with screws, the second welding protrusions 56, 57 may be welded to the second contact member 50.

[0060] In the image forming apparatus 1 according to the present embodiment, the two first oblong holes 44, 45 are formed in one first contact member 40, but the present invention is not limited to this and it is sufficient that at least one first oblong hole 44 is formed. Similarly, it is sufficient that at least one second oblong hole 54 is formed in the second contact member 50.

[0061] In the image forming apparatus 1 according to the present embodiment, the long hole portions 44, 45, 54, 55 are formed with the tapered portions 44A, 45A, 54A, 55A, but the present invention is not limited thereto. At least one of the first tapered portions 44A, 45A and the second tapered portions 54A, 55A may be omitted (not shown). In addition, the welding protrusions 46, 47, 56, 57 that spread radially on the surfaces of the contact members 40, 50 are formed in a disk shape, but the present invention is not limited thereto. By changing the shape of the welding horn 90, for example, they may be formed in a dome shape or a polygonal plate shape (not shown).

[0062] In the image forming apparatus 1 according to the present embodiment, the rotation shaft 21A of the photoconductor drum 21 is inserted into the first opening 42 of the first contact member 40, but the present invention is not limited to this. The first contact member 40 may be fixed to the photoconductor housing 20 at a position that avoids the rotation shaft 21A (not shown). In this case, the first opening 42 may be omitted (not shown). Similarly, the second contact member 50 may be fixed to the development housing 30 at a position that avoids the rotation shaft 31A of the development roller 31, and the second opening 52 may be omitted (not shown).

[0063] The shapes and positions of the openings 42, 52, the slotted holes 44, 45, 54, 55, and the jig insertion portions 43, 53 of the contact members 40, 50 shown in the present embodiment are merely examples and may be freely changed. The first contact member 40 and the second contact member 50 have partially different shapes, but this is not limiting, and the first contact member 40 and the second contact member 50 may have the same shape (not shown) to reduce costs.

[0064] In the image forming apparatus 1 according to the present embodiment, the biasing member 35 biases the developing housing 30 toward the photoconductor housing 20, but the present invention is not limited to this. Instead of the biasing member 35, for example, an eccentric cam, a magnetic spring, or the like may be used, or the developing housing 30 may be configured to be biased toward the photoconductor housing 20 by gravity (neither of these are shown).

[0065] Furthermore, the image forming apparatus 1 according to the present embodiment is a color printer, but the present invention is not limited to this and may be applied to, for example, a monochrome printer, a copier, a facsimile, or a multifunction machine.

[0066] The above embodiment is merely an example of the image forming apparatus according to the present invention, and the technical scope of the present invention is not limited to the above embodiment. The present invention may be modified, substituted, or altered in various ways without departing from the spirit of the technical concept, and the claims include all embodiments that may be included within the scope of the technical concept. [Explanation of symbols]

[0067] 1. Image forming device 20 Photoconductor housing 21 Photoconductor drum 30 Development housing 31 Developing roller 40 First contact member 44,45 1st oblong hole 44A, 45A First taper section 46,47 First welding protrusion 50 Second contact member 54,55 2nd oblong hole 54A, 55A Second taper section 56,57 Second welding protrusion

Claims

1. A photoconductor drum that holds a latent image; a photoreceptor housing that supports the photoreceptor drum so as to be rotatable about an axis; A developing roller for holding a developer; a developing housing that supports the developing roller so as to be rotatable about an axis while facing the photosensitive drum; a pair of first contact members provided at both ends of the photoreceptor housing in an axial direction in which the photoreceptor drum extends; a pair of second contact members provided at both ends of the developing housing in the axial direction and contacting the pair of first contact members by pressing the developing housing toward the photosensitive body housing; the photoconductor housing has a pair of first welding protrusions protruding outward from both ends in the axial direction, the first contact member has a first elongated hole portion that is formed longer in a contact / separation direction along a straight line connecting an axis of the photosensitive drum and an axis of the developing roller than the first welding convex portion, an image forming apparatus comprising: a first welding protrusion that passes through the first oblong hole and is welded to the first contact member, thereby fixing the first contact member to the photosensitive member housing;

2. A photoconductor drum that holds a latent image; a photoreceptor housing that supports the photoreceptor drum so as to be rotatable about an axis; A developing roller for holding a developer; a developing housing that supports the developing roller so as to be rotatable about an axis while facing the photosensitive drum; a pair of first contact members provided at both ends of the photoreceptor housing in an axial direction in which the photoreceptor drum extends; a pair of second contact members provided at both ends of the developing housing in the axial direction and contacting the pair of first contact members by pressing the developing housing toward the photosensitive body housing; the developing housing has a pair of second welding protrusions protruding outward from both ends in the axial direction, the second contact member has a second elongated hole portion that is formed longer in a contact / separation direction along a straight line connecting an axis of the photosensitive drum and an axis of the developing roller than the second welding protrusion, the second welding protrusion is welded to the second contact member in a state in which the second welding protrusion passes through the second oblong hole portion, thereby fixing the second contact member to the developing housing.

3. A photoconductor drum that holds a latent image; a photoreceptor housing that supports the photoreceptor drum so as to be rotatable about an axis; A developing roller for holding a developer; a developing housing that supports the developing roller so as to be rotatable about an axis while facing the photosensitive drum; a pair of first contact members provided at both ends of the photoconductor housing in an axial direction in which the photoconductor drum extends; a pair of second contact members provided at both ends of the developing housing in the axial direction and contacting the pair of first contact members by pressing the developing housing toward the photosensitive body housing; the photoconductor housing has a pair of first welding protrusions protruding outward from both ends in the axial direction, the developing housing has a pair of second welding protrusions protruding outward from both ends in the axial direction, the first contact member has a first elongated hole portion that is formed longer in a contact / separation direction along a straight line connecting an axis of the photosensitive drum and an axis of the developing roller than the first welding convex portion, the second contact member has a second elongated hole portion formed longer in the contact / separation direction than the second welding protrusion, the first welding protrusion is welded to the first contact member in a state in which the first welding protrusion penetrates the first oblong hole, whereby the first contact member is fixed to the photoconductor housing; the second welding protrusion is welded to the second contact member in a state in which the second welding protrusion passes through the second oblong hole portion, thereby fixing the second contact member to the developing housing.

4. 4. The image forming apparatus according to claim 1, wherein the welded first welding convex portion is filled into the first long hole portion, has an outer diameter larger than that of the first long hole portion on the surface of the first contact member, and sandwiches the first contact member between itself and the axial end of the photosensitive body housing.

5. The first oblong hole has a first tapered portion formed by chamfering a peripheral portion on a front surface side, 5. The image forming apparatus according to claim 4, wherein the first welded protrusion is filled in the first slot including the first tapered portion.

6. 4. The image forming apparatus according to claim 2, wherein the welded second welding protrusion is filled into the second long hole portion, has an outer diameter larger than that of the second long hole portion on the surface of the second contact member, and sandwiches the second contact member between itself and the axial end of the developing housing.

7. The second oblong hole has a second tapered portion formed by chamfering a peripheral portion on a front surface side, 7. The image forming apparatus according to claim 6, wherein the second welding protrusion is filled in the second slot including the second tapered portion.

8. the first welding protrusion is filled in the first elongated hole portion, has an outer diameter larger than that of the first elongated hole portion on the surface of the first contact member, and sandwiches the first contact member between the first welding protrusion and the end portion of the photoconductor housing in the axial direction; 4. The image forming apparatus according to claim 3, wherein the welded second welding protrusion is filled into the second long hole portion, has an outer diameter larger than that of the second long hole portion on the surface of the second contact member, and sandwiches the second contact member between itself and the axial end of the developing housing.

9. The first oblong hole has a first tapered portion formed by chamfering a peripheral portion on a front surface side, The first welding protrusion is filled into the first slotted hole including the first tapered portion, The second oblong hole has a second tapered portion formed by chamfering a peripheral portion on a front surface side, 9. The image forming apparatus according to claim 8, wherein the second welding protrusion is filled in the second slot including the second tapered portion.

Images