Fixing mechanism and image forming apparatus

Abstract

To provide a fixing mechanism that can appropriately prevent the occurrence of banding during rotation of a photoreceptor drum.SOLUTION: A fixing mechanism 100 is a mechanism that fixes a photoreceptor drum 36 to a driving shaft 76. The driving shaft is supported by a driving unit (60) at one end. The photoreceptor drum comprises a drum body 70, a first flange 72 provided at one end of the drum body, and a second flange (74) provided at the other end of the drum body. The fixing mechanism includes an attachment knob (64) that is pressed by a screw member (66) fastened to a screw hole (76c) of the driving shaft to fix the second flange to the driving shaft, and a rotation regulation part 100b that regulates the rotation of the first flange in a direction opposite to a rotation driving direction of the driving shaft.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present disclosure relates to a fixing mechanism and an image forming apparatus, and more particularly to a fixing mechanism for fixing a photosensitive drum to a drive shaft, for example, and an image forming apparatus including the same. [Background technology]

[0002] An example of this type of conventional fixing mechanism is disclosed in Patent Document 1. The technology of Patent Document 1 relates to a coupling mechanism that detachably couples a drive shaft and a photosensitive drum, and includes a drive-side coupling, a first anti-rotation portion, a drum-side coupling, and a rattle prevention mechanism. The drive-side coupling is provided on the drive shaft so as to be movable in the axial direction. The first anti-rotation portion is provided on the drive shaft and prevents the drive-side coupling from rotating. The drum-side coupling is provided on the photosensitive drum and can be connected to the drive-side coupling. The rattle prevention mechanism includes a coil spring that is compressed between the first anti-rotation portion and the drum-side coupling when the drive-side coupling and the drum-side coupling are coupled, generating a repulsive force in the rotational direction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-237734 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology of Patent Document 1, the biasing force of the coil spring is used to suppress backlash between the drive shaft and the drive-side coupling when the photosensitive drum rotates, thereby suppressing the occurrence of banding (jitter) caused by this backlash. However, with the technology of Patent Document 1, if a load fluctuation occurs during rotation of the photosensitive drum, such as an impact from paper passing, the biasing force of the coil spring may be overcome by this load fluctuation, causing the drive shaft (and therefore the photosensitive drum) to rotate relative to the drive-side coupling, which may result in banding.

[0005] Therefore, a primary object of this disclosure is to provide a novel fixing mechanism and image forming apparatus.

[0006] Another object of the present disclosure is to provide a fixing mechanism and an image forming apparatus that can appropriately suppress the occurrence of banding when a photosensitive drum rotates. [Means for solving the problem]

[0007] The first disclosure is a fixing mechanism for fixing a photosensitive drum to a drive shaft, one end of which is supported by a drive unit having a drive source and is rotatable in a first direction by the drive source, and the photosensitive drum includes a cylindrical drum body, a first flange provided at one end of the drum body and having a first insertion hole portion through which one end of the drive shaft is inserted, and a second flange provided at the other end of the drum body and having a second insertion hole portion through which the other end of the drive shaft is inserted and a protrusion protruding from the inner surface of the second insertion hole portion, and the drive shaft is The fixing mechanism includes a step portion formed by reducing the diameter of the other end portion, which restricts the movement of the second flange toward one end of the drive shaft, a mounting knob having a threaded hole formed on the other end surface extending in the axial direction, which is fitted onto the other end of the drive shaft and pressed by a screw member fastened to the threaded hole, thereby sandwiching a protrusion between the step portion and the mounting knob to fix the second flange to the drive shaft, and a rotation restriction portion provided at a position corresponding to the first insertion hole portion, which restricts the rotation of the first flange relative to the drive shaft in a second direction which is opposite to the first direction.

[0008] According to the first disclosure, both ends of the photosensitive drum can be appropriately fixed to the drive shaft with a simple configuration in which the second flange is fixed to the drive shaft using a mounting knob and a screw member, and rotation of the first flange in the second direction is restricted by a rotation restricting portion, thereby appropriately suppressing banding during rotation of the photosensitive drum.

[0009] The second disclosure is dependent on the first disclosure, and the photosensitive drum is fixed to the drive shaft by the fastening force of the screw member, with the rotation of the first flange in the second direction being restricted by the rotation restricting portion.

[0010] The third disclosure is dependent on the first or second disclosure, and the rotation restricting portion includes an interlocking portion protruding from the outer peripheral surface of the drive shaft, and an interlocking portion provided on the inner peripheral surface of the first insertion hole portion and interlocking with the interlocking portion.

[0011] The fourth disclosure is dependent on the third disclosure, and the abutment surface of the locking portion against the locked portion is inclined so as to approach the axial center of the drive shaft as it moves from one end side to the other end side of the drive shaft.

[0012] A fifth disclosure is dependent on the first or second disclosure, and the rotation restricting portion includes a one-way clutch provided between an inner circumferential surface of the first insertion hole portion and an outer circumferential surface of the drive shaft.

[0013] The sixth disclosure is an image forming apparatus comprising an apparatus main body having a drive unit with a drive shaft, a photosensitive drum detachably provided in the apparatus main body, and a fixing mechanism according to the first disclosure that fixes the photosensitive drum to the drive shaft. [Effects of the Invention]

[0014] According to this disclosure, both ends of the photosensitive drum can be fixed to the drive shaft with a simple configuration, and the occurrence of banding during rotation of the photosensitive drum can be appropriately suppressed.

[0015] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description of the embodiments, which proceeds with reference to the drawings. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram schematically illustrating the internal structure of an image forming apparatus according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a perspective view showing a process unit and a drive unit provided in the image forming apparatus. [Figure 3] FIG. 2 is an exploded perspective view showing a state in which a process unit is removed from a drive unit. [Figure 4] FIG. 2 is a cross-sectional view showing a photosensitive drum. [Figure 5] FIG. 2 is a cross-sectional view showing a process unit in a state in which a photosensitive drum is fixed to a drive shaft. [Figure 6] 10 is a perspective view showing, in partial cross section, the periphery of the other end of the photosensitive drum fixed to the drive shaft. FIG. [Figure 7] FIG. 4 is an exploded perspective view showing, in partial cross section, the other end portion and its periphery of the photosensitive drum. [Figure 8] FIG. 2 is a perspective view showing, in partial cross section, one end of the photosensitive drum fixed to a drive shaft. [Figure 9] FIG. 2 is a rear view showing one end of the photosensitive drum fixed to the drive shaft. [Figure 10] 10 is a cross-sectional view showing one end of the photosensitive drum taken along line XX in FIG. 9. [Figure 11] 10 is a perspective view showing, in partial cross section, the periphery of the other end of the photosensitive drum fixed to the drive shaft in an image forming apparatus according to a second embodiment of the present disclosure. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] [First Example] 1, an image forming apparatus 10 according to a first embodiment of this disclosure is a monochrome multifunction machine having functions such as a copy machine, a printer, a scanner, and a facsimile machine, and forms a monochrome image on paper (recording medium) by electrophotography. As will be described in detail later, the image forming apparatus 10 includes a photosensitive drum 36 and a drive unit 60 for driving the photosensitive drum 36. The photosensitive drum 36 is removably fixed to a drive shaft 76 provided on the drive unit 60 by a fixing mechanism 100.

[0018] In this specification, the front-to-rear direction (depth direction) of image forming apparatus 10 and its components is defined with the surface facing the position of a user who operates image forming apparatus 10, i.e., the surface on which an operation unit (not shown) is provided, as the front (front). The operation unit is provided on the near side of the paper in Fig. 1. The left-to-right direction (horizontal direction) of image forming apparatus 10 and its components is defined with reference to the state when image forming apparatus 10 is viewed from the front side.

[0019] First, we will explain the general configuration of the image forming apparatus 10. As shown in Figure 1, the image forming apparatus 10 includes an apparatus main body 12 and an image reading device 14 arranged above the apparatus main body 12.

[0020] The image reading device 14 includes a document table 16 made of a transparent material. A document retaining cover 18 is attached above the document table 16 via a hinge or the like so that it can be opened and closed freely. This document retaining cover 18 is provided with an ADF 24 (automatic document feeder) that automatically feeds documents placed on a document tray 20 one by one to an image reading position 22. In addition, an operation unit is provided on the front side of the document table 16 for receiving input operations such as a print start command from the user. The operation unit is provided with a touch panel display, various operation buttons, etc.

[0021] The image reading device 14 also includes an image reading unit 26 equipped with a light source, multiple mirrors, an imaging lens, a line sensor, etc. The image reading unit 26 exposes the surface of the document to light, and guides the light reflected from the document surface to the imaging lens via multiple mirrors. The imaging lens then forms an image of the reflected light on the light-receiving elements of the line sensor. The line sensor detects the luminance and chromaticity of the reflected light that forms an image on the light-receiving elements, and generates image data based on the image of the document surface. A CCD (Charge Coupled Device) or a CIS (Contact Image Sensor) is used as the line sensor.

[0022] A control unit (not shown) including a CPU and memory, etc., and an image forming unit 30, etc. are provided within the device main body 12. The control unit transmits control signals to each part of the image forming device 10 in response to input operations to the operation unit, etc., and causes the image forming device 10 to perform various operations.

[0023] The image forming section 30 includes an exposure unit 32, a developing unit 34, a photosensitive drum 36, a cleaning unit 38, a charging unit 40, a transfer roller 42, a fixing unit 44, a toner supply device 46, etc., and forms an image on paper transported from a paper feed tray 48, etc., and discharges the paper with the image formed on it to a paper discharge tray 50. Image data used to form an image on paper is image data read by the image reading section 26 or image data sent from an external computer, etc.

[0024] The photosensitive drum 36 is an image carrier having a drum main body 70 (see FIG. 4) with a photosensitive layer formed on its surface, and is provided so as to extend in the front-to-rear direction. The charging unit 40 includes a charging roller and the like, and charges the surface of the photosensitive drum 36 (specifically, the drum main body 70) to a predetermined potential. The cleaning unit 38 includes a cleaning blade, a conveying screw, and the like, and removes and collects toner remaining on the surface of the photosensitive drum 36 after development and image transfer.

[0025] The photosensitive drum 36, cleaning unit 38, and charging unit 40 are integrated (composed into a cartridge) to form a process unit 56 (also called a photosensitive cartridge). The process unit 56, including the photosensitive drum 36, is detachable from the front side of the apparatus main body 12 for maintenance, replacement, and the like. Meanwhile, a drive unit 60 (see FIG. 2) is mounted on a support frame provided on the rear side of the apparatus main body 12. When the process unit 56 is mounted on the apparatus main body 12, the photosensitive drum 36 and the drive unit 60 are connected, and the photosensitive drum 36 can receive a rotational drive force from the drive unit 60. The specific configurations of the process unit 56, including the photosensitive drum 36, and the drive unit 60 will be described later.

[0026] The exposure unit 32 is configured as a laser scanning unit (LSU) equipped with a laser diode, a polygon mirror, etc., and is disposed a predetermined distance to the left of the photosensitive drum 36. The exposure unit 32 exposes the charged surface of the photosensitive drum 36 to light, thereby forming an electrostatic latent image on the surface of the photosensitive drum 36 according to image data. The development unit 34 is equipped with a developer tank, a development roller, etc., and is disposed below the photosensitive drum 36. The development unit 34 supplies toner to the surface of the photosensitive drum 36 and visualizes the electrostatic latent image formed on the surface of the photosensitive drum 36 with the toner (forming a toner image).

[0027] The transfer roller 42 is a member for transferring the toner image formed on the surface of the photosensitive drum 36 onto paper, and is provided so as to press against the photosensitive drum 36. During image formation, a predetermined voltage is applied to the transfer roller 42, thereby forming a transfer electric field between the photosensitive drum 36 and the transfer roller 42. Then, due to the action of this transfer electric field, the toner image formed on the outer peripheral surface of the photosensitive drum 36 is transferred onto the paper as the paper passes through the nip region (transfer nip portion) between the photosensitive drum 36 and the transfer roller 42.

[0028] The fixing unit 44 includes a heating roller, a pressure roller, etc., and is disposed above the process unit 56 and the transfer roller 42. The heating roller is heated to a predetermined fixing temperature by an internal heat source. When paper passes through the nip region (fixing nip) between the heating roller and the pressure roller, the toner image transferred to the paper is melted, mixed, and pressed against the paper, thereby thermally fixing the toner image to the paper.

[0029] Also formed within the device body 12 is a first paper transport path L1 for sending paper transported from the paper feed tray 48 or the like through registration rollers 52, a transfer nip, and a fixing nip to a paper output tray 50. Also formed is a second paper transport path L2 for returning paper that has been printed on one side and passed through the fixing unit 44 to the first paper transport path L1 upstream of the transfer nip in the paper transport direction when double-sided printing is performed on the paper. A plurality of transport rollers 54 for applying auxiliary propulsion force to the paper are appropriately provided on the first paper transport path L1 and the second paper transport path L2.

[0030] Next, the configuration of the process unit 56 including the photosensitive drum 36 and the drive unit 60 will be described in detail. As shown in FIGS. 2 and 3 , the process unit 56 includes the photosensitive drum 36, a cleaning unit 38, and a charging unit 40, and is detachably mounted to the apparatus main body 12. The drive unit 60 includes a motor 62 (drive source) for driving the drive section (the photosensitive drum 36, the conveying screw, etc.) of the process unit 56, and is mounted at the rear of the apparatus main body 12. The drive unit 60 is provided with a metal drive shaft 76 (drum shaft) for driving the photosensitive drum 36 to rotate. One end (rear end) of the drive shaft 76 is supported by the drive unit 60 and is connected to the motor 62 via a gear train. The drive shaft 76 is driven to rotate by the motor 62 in a first direction X (counterclockwise when viewed from the front in this embodiment).

[0031] 4, the photosensitive drum 36 includes a drum body 70 having a photosensitive layer formed on the surface of a cylindrical conductive base. Synthetic resin flanges 72 and 74 are press-fitted into both ends of the drum body 70 and fixed thereto. That is, a first flange 72 is fixedly provided at one end (rear end) of the drum body 70, and a second flange 74 is fixedly provided at the other end (front end) of the drum body 70.

[0032] The first flange 72 includes a disk-shaped first flange body 72a. A short cylindrical first press-fit portion 72b is formed at the outer edge of the first flange body 72a. A first insertion hole 72c, into which one end of the drive shaft 76 is inserted, is formed at the center of the first flange body 72a (and therefore the first flange 72). The first insertion hole 72c is formed in a generally cylindrical shape extending in the axial direction of the drive shaft 76. A first bearing portion 72d, into which the drive shaft 76 is fitted via a fixing spacer 78 such as a sintered bearing, and a locking portion 72e, which will be described later, are formed on the inner peripheral surface of the first insertion hole 72c (see FIG. 8).

[0033] On the other hand, the second flange 74 includes a disk-shaped second flange main body 74a. A short-cylindrical second press-fit portion 74b is formed at the outer edge of the second flange main body 74a. A second insertion hole 74c, into which the other end of the drive shaft 76 is inserted, is formed at the center of the second flange main body 74a (and therefore the second flange 74). The second insertion hole 74c is formed in a generally cylindrical shape extending in the axial direction of the drive shaft 76. The inner circumferential surface of the second insertion hole 74c is formed with a second journal portion 74d into which the drive shaft 76 is fitted, and an annular protrusion 74e protruding inward from the other end (front end) of the second journal portion 74d. The second insertion hole 74c also includes a second coupling portion 74f extending further toward the other end (front side) than the protrusion 74e and having gear teeth (internal teeth) formed on its inner circumferential surface.

[0034] 2, 3, and 5, the photosensitive drum 36 as described above is integrated with the drive shaft 76 when the process unit 56 is attached to the apparatus main body 12. At this time, the drive shaft 76 is inserted so as to pass through the center of the photosensitive drum 36, and the photosensitive drum 36 is fixed to the drive shaft 76 by a fixing mechanism 100 including the mounting knob 64, the screw member 66, and the like. Therefore, when the drive shaft 76 receives a rotational force from the motor 62 and rotates in the first direction X, the photosensitive drum 36 also rotates in the first direction X. The fixing mechanism 100 that fixes the photosensitive drum 36 to the drive shaft 76 will be described in detail below.

[0035] 5, the fixing mechanism 100 includes a main fixing portion 100a provided on the other end (front side) of the photosensitive drum 36, and a rotation restricting portion 100b provided on one end (rear side) of the photosensitive drum 36. The rotation restricting portion 100b is provided at a position corresponding to the first insertion hole portion 72c of the first flange 72, and restricts rotation of the first flange 72 in a second direction Y (see FIG. 8), which is the opposite direction to the rotational drive direction (first direction X) of the drive shaft 76.

[0036] 6 and 7, the main fixing part 100a is made up of the second flange 74, the drive shaft 76, the mounting knob 64, the screw member 66, etc. As described above, the second flange 74 has the second insertion hole 74c through which the other end of the drive shaft 76 is inserted. The second insertion hole 74c is formed with the second pivot support part 74d, the protrusion 74e, the second coupling part 74f, etc.

[0037] The other end of the drive shaft 76 is formed with a small-diameter section 76a that is smaller in diameter than the other sections of the drive shaft 76. A tapered step section 76b that tapers toward the other end (front side) is formed on the outer circumferential surface of the drive shaft 76 at the base end of the small-diameter section 76a. A threaded hole 76c extending in the axial direction is formed on the other end face (front surface) of the drive shaft 76. A rotation prevention section 76d, which has two D-cut surfaces facing in opposite directions, is formed on the other end of the small-diameter section 76a.

[0038] The mounting knob 64 has a generally cylindrical shape and is fitted onto a small-diameter portion 76a formed on the other end of the drive shaft 76. An annular grip portion 64a protruding outward is formed on the other end (front end) of the mounting knob 64. A recess 64b is formed on the other end surface (front end surface) of the mounting knob 64 to accommodate the head of the screw member 66. A first coupling portion 64c having gear teeth (external teeth) on its outer circumferential surface is formed on one end (rear end) of the mounting knob 64 and meshes with a second coupling portion 74f of the second flange 74. Engagement of the first coupling portion 64c and the second coupling portion 74f connects the mounting knob 64 to the second flange 74 in a rotation-preventing state. An engagement portion 64d is formed on the other end of the mounting knob 64 to engage with a rotation-preventing portion 76d of the drive shaft 76. By engaging the engaging portion 64d with the anti-rotation portion 76d, the mounting knob 64 is connected to the drive shaft 76 in a state where it is prevented from rotating.

[0039] When fixing the photosensitive drum 36 to the drive shaft 76, the photosensitive drum 36 (process unit 56) is pushed toward one end (rear side) so that the protrusion 74e of the second flange 74 of the photosensitive drum 36 abuts against the stepped portion 76b of the drive shaft 76. As a result, the stepped portion 76b restricts movement of the second flange 74 toward the one end, and the photosensitive drum 36 is positioned in the axial direction. Thereafter, the mounting knob 64 is fitted onto the other end (small diameter portion 76a) of the drive shaft 76, and the screw member 66 is fastened to the screw hole 76c of the drive shaft 76 via the washer 68. As a result, the mounting knob 64 is pressed toward the one end by the screw member 66, and the protrusion 74e is sandwiched between the one end face of the mounting knob 64 and the stepped portion 76b, thereby fixing the second flange 74 (i.e., the other end of the photosensitive drum 36) to the drive shaft 76. Therefore, even if an impact due to paper passing occurs when the photosensitive drum 36 is rotating, the occurrence of banding at the other end of the photosensitive drum 36 is appropriately prevented.

[0040] On the other hand, the fastening force of the screw member 66 alone cannot completely secure one end of the photosensitive drum 36 to the drive shaft 76, and the drum body 70 may twist, causing circumferential movement. Therefore, if an impact such as that caused by paper passing occurs, the one end of the photosensitive drum 36 may shift circumferentially relative to the drive shaft 76, potentially causing banding. To prevent this, it is conceivable to secure the one end (first flange 72) of the photosensitive drum 36 to the drive shaft 76 with a screw. However, this would require disassembling the device body 12 to access the one end of the photosensitive drum 36 and then installing or removing the screw, which would impair serviceability.

[0041] Therefore, in this first embodiment, a rotation restricting portion 100b as described below is provided, so that one end of the photosensitive drum 36 can be properly fixed to the drive shaft 76 while maintaining serviceability.

[0042] As shown in FIGS. 8 to 10, the rotation restricting portion 100b includes a locked portion 80 provided on the outer peripheral surface of the drive shaft 76 and a locking portion 72e provided on the inner peripheral surface of the first insertion hole 72c of the first flange 72. In this embodiment, the locked portion 80 is formed by a pin inserted into and fixed in the drive shaft 76, and is provided so as to protrude outward from the outer peripheral surface of the drive shaft 76. Meanwhile, the locking portion 72e is provided so as to protrude inward from the inner peripheral surface of the first insertion hole 72c at a position closer to one end (rear side) than the first pivot support portion 72d. An abutment surface 72f of the locking portion 72e, which comes into contact with the locked portion 80, is an inclined surface that slopes toward the axial center of the drive shaft 76 as it moves from one end to the other end (from rear side to front side) of the drive shaft 76.

[0043] When fixing the photosensitive drum 36 to the drive shaft 76, the screw member 66 is fastened to the screw hole 76c of the drive shaft 76 as described above, but at this time, it is preferable to rotate the photosensitive drum 36 slightly in the second direction Y to bring the locked portion 80 into contact with the locking portion 72e and to put the first flange 72 (one end of the photosensitive drum 36) in a state where it cannot rotate any further in the second direction Y, before fastening the screw member 66. In other words, the photosensitive drum 36 is fixed to the drive shaft 76 by the fastening force of the screw member 66 in a state where the rotation of the first flange 72 in the second direction Y is restricted by the rotation restricting portion 100b.

[0044] When the photosensitive drum 36 rotates, the drive shaft 76 rotates in the first direction X, so a force acts in a direction that brings the locked portion 80 and the locking portion 72e into close contact with each other, and the rotation restricting portion 100b reliably restricts the rotation of the first flange 72 in the second direction Y. In other words, because one end of the photosensitive drum 36 is reliably fixed in the circumferential direction, banding at one end of the photosensitive drum 36 is appropriately prevented even if an impact caused by paper passing occurs.

[0045] Furthermore, by making the abutment surface 72f of the locking portion 72e that contacts the locked portion 80 an inclined surface, the fastening force of the screw member 66 also acts in a direction that brings the locking portion 72e and the locked portion 80 into close contact with each other, thereby ensuring that the locked portion 80 and the locking portion 72e are kept in close contact with each other. Furthermore, by making the abutment surface 72f an inclined surface, the photosensitive drum 36 can be fixed to the drive shaft 76 in the axial direction more reliably.

[0046] As described above, according to the first embodiment, the second flange 74 is fixed to the drive shaft 76 using the mounting knob 64 and the screw member 66, and the rotation of the first flange 72 in the second direction Y is restricted by the rotation restricting portion 100b. This simple configuration allows both ends of the photosensitive drum 36 to be appropriately fixed to the drive shaft 76. Therefore, the occurrence of banding during rotation of the photosensitive drum 36 can be appropriately suppressed while maintaining serviceability.

[0047] In the first embodiment described above, the photosensitive drum 36 is manually rotated in the second direction Y to bring the locked portion 80 and the locking portion 72e into contact with each other, and then the screw member 66 is fastened, but this is not limiting. For example, by forming the gear teeth of the coupling portions 64c, 74f into helical teeth that are inclined by several degrees with respect to the axial direction of the drive shaft 76, when the mounting knob 64 is attached to the drive shaft 76, the photosensitive drum 36 may automatically rotate in the second direction Y to bring the locked portion 80 and the locking portion 72e into contact with each other.

[0048] [Second Example] Next, a fixing mechanism 100 provided in an image forming apparatus 10 according to a second embodiment of this disclosure will be described with reference to Fig. 11. In this second embodiment, the configuration of a rotation restriction unit 100b differs from that of the first embodiment. Since the other parts are similar, parts common to the first embodiment are given the same reference numerals, and redundant descriptions will be omitted or simplified.

[0049] 11 , in the second embodiment, the rotation restricting portion 100b of the fixing mechanism 100 includes a one-way clutch 90 provided between the inner circumferential surface of the first insertion hole portion 72c of the first flange 72 and the outer circumferential surface of the drive shaft 76. The one-way clutch 90 is fixed to the first insertion hole portion 72c, for example, by being press-fitted into the first pivot support portion 72d of the first insertion hole portion 72c. The one-way clutch 90 allows rotation of the first flange 72 (one end portion of the photosensitive drum 36) in the first direction X relative to the drive shaft 76 and restricts rotation in the second direction Y.

[0050] This second embodiment also achieves the same effects as the first embodiment, and with a simple configuration, both ends of the photosensitive drum 36 can be properly fixed to the drive shaft 76, thereby maintaining serviceability and properly suppressing the occurrence of banding when the photosensitive drum 36 rotates.

[0051] Note that the specific configurations of the image forming apparatuses described in this specification are merely examples and can be changed as appropriate depending on the specifications of the actual product. For example, the image forming apparatus does not necessarily have to be a multifunction machine, but may be any of a copier, facsimile, printer, etc., or a multifunction machine that combines at least two of these. Furthermore, the image forming apparatus is not limited to a monochrome machine, but may be a color machine capable of forming multicolor images.

[0052] Furthermore, the specific part shapes and the like given above are merely examples and can be changed as appropriate according to the needs of product specifications and the like. [Explanation of symbols]

[0053] 10...Image forming device 12...Device body 30...Image forming unit 36...Photosensitive drum 56...Process unit 60...Drive unit 64...Mounting knob 66...Threaded member 70...Drum body 72...First flange 72c...First insertion hole portion 72e...Locking part 74...Second flange 74c...Second insertion hole portion 76...Drive shaft 76b...Stepped section 76c...screw hole 80...Locked part 90...One-way clutch 100…Fixing mechanism 100a...Main fixed part 100b ...Rotation restriction part

Claims

1. A fixing mechanism for fixing the photosensitive drum to the drive shaft, the drive shaft is supported at one end by a drive unit having a drive source and is rotatable in a first direction by the drive source; The photosensitive drum is A cylindrical drum body, a first flange provided at one end of the drum body and having a first insertion hole through which one end of the drive shaft is inserted; and a second flange provided at the other end of the drum body, the second flange having a second insertion hole through which the other end of the drive shaft is inserted and a protrusion protruding from an inner circumferential surface of the second insertion hole; The drive shaft is a step portion formed by reducing the diameter of the other end portion of the drive shaft, the step portion restricting movement of the second flange toward the one end of the drive shaft; and A screw hole is formed on the other end surface so as to extend in the axial direction, an attachment knob that is fitted onto the other end of the drive shaft and is pressed by a screw member fastened to the screw hole to sandwich the protrusion between itself and the stepped portion, thereby fixing the second flange to the drive shaft; and a fixing mechanism including a rotation restricting portion provided at a position corresponding to the first insertion hole portion and configured to restrict rotation of the first flange relative to the drive shaft in a second direction that is opposite to the first direction.

2. 2. The fixing mechanism according to claim 1, wherein the photosensitive drum is fixed to the drive shaft by the fastening force of the screw member while the rotation of the first flange in the second direction is restricted by the rotation restricting portion.

3. 3. The fixing mechanism according to claim 1, wherein the rotation restricting portion includes an engaged portion protruding from an outer peripheral surface of the drive shaft and an engaging portion provided on an inner peripheral surface of the first insertion hole portion and engaging the engaged portion.

4. 4. The fixing mechanism according to claim 3, wherein the abutment surface of the locking portion against the locked portion is inclined so as to approach the axial center of the drive shaft from one end side to the other end side of the drive shaft.

5. The fixing mechanism according to claim 1 or 2, wherein the rotation restricting portion includes a one-way clutch provided between an inner circumferential surface of the first insertion hole portion and an outer circumferential surface of the drive shaft.

6. an apparatus body including a drive unit having a drive shaft; a photosensitive drum detachably provided in the device body; and An image forming apparatus comprising the fixing mechanism according to claim 1 that fixes the photosensitive drum to the drive shaft.

Images