JP2005115236A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which surface deflection accuracy of an image carrier or positioning accuracy of each part attached to a process cartridge are improved without bringing on increases in the size and the cost of the process cartridge and in which the process cartridge can be easily attached to and detached from an apparatus main body without unintentionally increasing the attaching and detaching force by preventing abutting of a rotational shaft on an anti-friction bearing, etc. <P>SOLUTION: Flange members are provided on both axial end parts of the image carrier, the flange members are engaged with the rotational shaft provided in the apparatus main body and the flange members of the image carrier are freely rotatably supported through the anti-friction bearing members respectively by the respective side plates of the process cartridge. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic method, a process cartridge that can be attached to and detached from the main body of the image forming apparatus, and an electrophotographic photosensitive drum.

Japanese Patent Laid-Open No. 1-079401 Japanese Patent No. 3315451

  Conventionally, in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine to which this type of electrophotographic method is applied, a photosensitive drum as an image carrier and a charger disposed around the photosensitive drum The image forming member is integrally configured as a process cartridge, and the process cartridge can be freely attached to and detached from the apparatus main body so that the user can replace the photosensitive drum and the like, thereby improving the maintainability. ing. The photosensitive drum is configured to be fitted and rotated with respect to a rotation shaft provided in the apparatus main body by mounting the process cartridge in the apparatus main body.

  As described above, as an image forming apparatus configured so that the photosensitive drum can be rotated by mounting the process cartridge in the apparatus main body, for example, Japanese Patent Laid-Open No. 1-079401 and Japanese Patent No. 3315451 are disclosed. Is disclosed.

  A rotating body support device according to Japanese Patent Laid-Open No. 01-079401 is provided with a rotating body support in which a supporting shaft of the rotating body is fitted along a rotation axis of the rotating body, and this shaft is mounted on an immovable main body. In the apparatus, a portion where the rotating body is locked to the shaft is formed in a conical surface such that the diameter of the rotating body is reduced in the center direction of the rotating body, and is inserted into the shaft and slidable in the axial direction. A member having a conical surface corresponding to the conical surface and having at least one slit formed in the axial direction thereof; and a member for detachably engaging and disengaging the conical surface of the member with the conical surface of the rotating body; And a means for relatively rotating the two is disposed between the stationary main body portion and the shaft or between the rotating body and the shaft.

  In addition, the image forming apparatus according to Japanese Patent No. 3315451 can attach and detach a process cartridge having an image carrier, and the image carrier of the process cartridge is fitted to a rotation shaft provided in the apparatus body. In the image forming apparatus in which the process cartridge is attached to the apparatus main body, the rotating shaft has a connecting portion for rotating integrally with the image carrier, and the connecting portion is provided on one end side of the rotating shaft. A projecting portion that projects in a radial direction of the rotating body and engages with an engaging portion provided on the image carrier, and the diameter of the other end side of the rotating shaft is larger than the rotation locus of the projecting portion, The process cartridge has side plates respectively provided on the sides of the image carrier, and the first cartridge is fitted to the other end side of the rotation shaft larger than the rotation trajectory of the protrusion with respect to one side plate. The rolling bearing is provided with a second rolling bearing having an inner diameter smaller than that of the first rolling bearing with respect to the other side plate and fitted to the one end side of the rotating shaft, and the rotating shaft from the first rolling bearing side is provided. It is comprised so that it may mount | wear to the said one end side of a thrust in a thrust direction.

  However, the conventional technique has the following problems. That is, in the case of the rotating body support device according to the above-mentioned Japanese Patent Laid-Open No. 01-079401, from the conical surface (tapered surface) that is reduced in diameter toward the center of the rotating body at the portion where the rotating body is locked to the shaft. By using the engaging means, it is possible to reduce the change in the surface runout accuracy of the rotating body due to the environment (temperature change) and component accuracy. Since accuracy is required, there is a problem that the process cartridge is increased in size and cost.

  In the case of the image forming apparatus according to Japanese Patent No. 3315451, the first and second rolling bearings provided on one side plate and the other side plate of the process cartridge are provided with a rotating shaft provided on the apparatus main body. It is possible to improve the surface shake accuracy of the image carrier and the positional accuracy of each component mounted on the process cartridge.

  However, in the case of the image forming apparatus according to Japanese Patent No. 3315451, since there are a plurality of rolling bearings with respect to the rotating shaft along the thrust direction, the first side plate and the other side plate of the process cartridge are provided. The positional accuracy of the first and second rolling bearings must be maintained with high accuracy in the state before mounting with respect to the center line, and is attached to the side plates provided at both ends of the long process cartridge. For process cartridges in which it is difficult to obtain the positional accuracy of the rolling bearing, the surface of the rotating shaft and the fitting portion of the rolling bearing or the image carrier abuts when attaching to or detaching from the apparatus main body, and the attachment / detachment force Has an unreasonable increase, and in some cases, it is difficult to attach and detach the process cartridge to the apparatus main body.

  Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and the object of the present invention is to avoid the increase in the size and cost of the process cartridge and the surface shake of the image carrier. It is possible to improve the accuracy and position accuracy of each component mounted on the process cartridge, as well as prevent the rotating shaft and rolling bearings from abutting, and the attachment / detachment force increases unnecessarily. An object of the present invention is to provide an image forming apparatus in which a process cartridge can be easily attached to and detached from an apparatus main body.

  In order to solve the above-mentioned problems, the invention described in claim 1 is configured such that a process cartridge having an image carrier is detachably attached to an apparatus main body, and the process cartridge is attached to the apparatus main body. In an image forming apparatus that drives an image carrier of a cartridge by being fitted to a rotation shaft provided in the apparatus main body, flange members are provided at both ends in the axial direction of the image carrier, and the flange member is provided in the apparatus main body. The flange members of the image carrier are rotatably supported on the side plates of the process cartridge via bearing members, respectively.

The flange member of the image carrier is made of a thermoplastic resin, and the linear expansion coefficient of the thermoplastic resin is 5 × 10 ⁻⁵ or less. Yes.

  Furthermore, the invention described in claim 3 is configured so that the pressure position of the bearing member, the flange member of the image carrier, and the pressure position of the tracking member of the developing unit are at least in the thrust direction. .

According to a fourth aspect of the present invention, the flange member of the image carrier includes a press-fit portion of the image carrier to the cylindrical base, a fitting portion of the bearing member, and a fitting portion to the rotating shaft. Are integrally formed.

Further, the invention described in claim 5 is configured such that one flange member of the image carrier is integrally provided with a connecting portion that engages with the rotation shaft and transmits the rotational driving force. .

  According to a sixth aspect of the present invention, in the process cartridge having an image carrier and configured to be detachable from the apparatus main body, flange members are provided at both ends in the axial direction of the image carrier, The flange member is fitted to a rotation shaft provided in the apparatus main body, and each flange member of the image carrier is rotatably supported on each side plate of the process cartridge via a bearing member. ing.

  Furthermore, the invention described in claim 7 is an electrophotographic photosensitive drum rotatably mounted on a process cartridge configured to be detachable from the apparatus main body. The electrophotographic photosensitive drum has an axial direction thereof. Flange members are provided at both ends of the electrophotographic photosensitive drum, and the electrophotographic photosensitive drum is configured to be freely engageable with a rotation shaft provided in the apparatus main body via the flange member, and each of the flange members of the electrophotographic photosensitive drum. Is rotatably supported on each side plate of the process cartridge via a bearing member.

  According to the present invention, it is possible to improve the surface shake accuracy of the image carrier and the positional accuracy of each component mounted on the process cartridge without increasing the size and cost of the process cartridge. Of course, it is possible to provide an image forming apparatus that prevents the rotating shaft and the rolling bearings from colliding with each other, and can easily attach / detach the process cartridge to / from the apparatus main body without increasing the attaching / detaching force unnecessarily. can do.

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
FIG. 2 is a block diagram showing a tandem digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention. This tandem digital color copier is the size of a normal office copier and can produce full-color and black-and-white images with high productivity comparable to a large high-speed copier. It has become.

  Although the tandem digital color copying machine includes an image reading device, the printer does not include the image reading device and forms an image based on image data output from a personal computer (not shown). Of course, this image forming apparatus may be used.

  In FIG. 2, reference numeral 1 denotes a main body of a tandem digital color copying machine. The digital color copying machine main body 1 has an image reading apparatus (IIT: Image Input Terminal) for reading an image of an original 2 on the upper portion thereof. 3 is provided. In the digital color copying machine main body 1, image data output from the image reading device 3 or a personal computer (not shown) or image data sent via a communication line such as a telephone line or a LAN is stored. An image processing apparatus (IPS: Image Processing System) 4 that temporarily accumulates as necessary and performs predetermined image processing on the image data, and processing in a color copying machine that includes a CPU, ROM, RAM, etc. And an image output device (IOT) that outputs an image based on image data that has been subjected to predetermined image processing by the image processing device 4. Image Output Terminal) 6 is arranged.

  Inside the digital color copying machine main body 1, as a plurality of image forming means constituting the image output device 6, it corresponds to each color of yellow (Y), magenta (M), cyan (C), and black (K). The image forming units 7Y, 7M, 7C, and 7K are arranged at regular intervals along the horizontal direction. Further, below the four image forming units 7Y, 7M, 7C, and 7K, an intermediate transfer member serving as an intermediate transfer member that transfers toner images of respective colors sequentially formed by these image forming units in a state of being superimposed on each other. The transfer belt 8 is disposed so as to be able to circulate along the arrow direction. The toner images of each color transferred onto the intermediate transfer belt 8 in a multiple manner are collectively transferred onto a recording paper 10 as a recording medium fed from a paper feed tray 9 or the like, and then the fixing device 11. As a result, the recording paper 10 fixed on the recording paper 10 and having a color image formed thereon is discharged to the outside.

  Further, the configuration of the tandem digital color copying machine will be described in detail with reference to FIG.

  As shown in FIG. 2, on the upper end of one end side of the digital color copying machine main body 1 is an image for reading a platen glass 12 on which the document 2 is placed and an image of the document 2 placed on the platen glass 12. A reading device 3 is provided. The image reading apparatus 3 illuminates a document 2 placed on a platen glass 12 with two light sources 13, and reflects a reflected light image from the document 2 with a full-rate mirror 14, half-rate mirrors 15 and 16, and an image. Scanning exposure is performed on an image reading element 18 formed of a CCD sensor or the like via a scanning optical system including a lens 17, and the reflected light image of the document 2 is read with a predetermined resolution by the image reading element 18. .

  The reflected light image of the document 2 read by the image reading device 3 is, for example, the image processing device 4 as document reflectance data of three colors of red (R), green (G), and blue (B) (each 8 bits). The image processing apparatus 4 sends shading correction, position shift correction, brightness / color space conversion, gamma correction, frame erasing to the reflectance data of the document 2 as necessary. Predetermined image processing such as color / movement editing is performed.

The image data subjected to the predetermined image processing by the image processing apparatus 4 as described above is four colors of yellow (Y), magenta (M), cyan (C), and black (K) (for example, 8 bits each). As described below, yellow (Y), magenta (M), cyan (C), and black (K) image forming units 7Y, 7M, 7C, and 7K Are sent to ROSs (Raster Output Scanners) 19a and 19b, and the ROSs 19a and 19b perform image exposure with a laser beam in accordance with the gradation data of the corresponding color.

  Incidentally, inside the tandem type digital color copying machine main body 1, as described above, four image forming portions 7Y, 7M of yellow (Y), magenta (M), cyan (C), and black (K) are provided. , 7C, 7K are arranged in parallel at a certain interval in the horizontal direction.

  Of these four image forming units 7Y, 7M, 7C, and 7K, the three color image forming units 7Y, 7M, and 7C are all configured in the same manner except that the colors of the images to be formed are different. Broadly speaking, the photosensitive drum 20 that rotates at a predetermined rotational speed along the direction of the arrow, a charging roll 21 that uniformly charges the surface of the photosensitive drum 20, and the surface of the photosensitive drum 20 ROS 19 as an exposure device that exposes an image corresponding to each color to form an electrostatic latent image, a developing device 22 that develops the electrostatic latent image formed on the photosensitive drum 20, and the developing device 22 The toner supply device 23 supplies toner of a predetermined color and a cleaning device 24.

  The black image forming unit 7K is roughly divided into a photosensitive drum 20 that rotates at a predetermined rotational speed in the direction of the arrow, and a scorotron 25 as a charging unit that uniformly charges the surface of the photosensitive drum 20. ROS 19 as an exposure device that forms an electrostatic latent image by exposing an image corresponding to each color on the surface of the photosensitive drum 20 and development for developing the electrostatic latent image formed on the photosensitive drum 20 The apparatus 26, a toner supply device 27 that supplies toner of a predetermined color to the developing device 22, and a cleaning device 28 are configured.

  From the image processing apparatus 4, image data (raster data) of each color is supplied to the ROS 19 of each of the yellow (Y), magenta (M), cyan (C), and black (K) image forming units 7Y, 7M, 7C, and 7K. Are sequentially output, and the laser beam emitted from the ROS 19 according to the image data is scanned and exposed on the surface of each of the photosensitive drums 20Y, 20M, 20C, and 20K to form an electrostatic latent image.

  The ROS 19 is not separately provided corresponding to each of the image forming units 7Y, 7M, 7C, and 7K, but ROS 19a for the yellow (Y) and magenta (M) image forming units 7Y and 7M. The cyan (C) and black (K) image forming units 7C and 7K ROS 19b are configured in common. As shown in FIG. 3, these ROSs 19 a and 19 b include a semiconductor laser 70 that emits a laser beam LB modulated according to image data. The laser beam LB emitted from the semiconductor laser 70 is collimated by the collimator lens 71, reflected by the two plane mirrors 72 and 73, and then irradiated on the surface of the polygon mirror 74. The polygon mirror 74 is rotationally driven at a predetermined speed along the arrow direction, and the laser beam LB applied to the surface (mirror surface) of the polygon mirror 74 is along the main scanning direction (axial direction of the photosensitive drum). Are deflected and scanned. The laser beam LB deflected and scanned by the polygon mirror 74 is adjusted in dot length on the photosensitive drum 20 via the folding mirror 77 after the focal length is adjusted by the f-θ lenses 75 and 76 according to the deflection angle. It is designed to irradiate in the state of being focused on. Further, at one end of the photosensitive drum 20 in the axial direction, a scanning start position detection sensor 78 is located at a position corresponding to an end on the scanning start side (SOS: Start Of Scan) in the scanning direction of the laser beam LB. Is arranged.

  In the ROS 19a and 19b shown in FIG. 3, it is described that the semiconductor laser 70 emits only one laser beam LB. However, actually, one semiconductor laser 70 has two laser beams LB. And image exposure corresponding to an image of a predetermined color is performed corresponding to the two image forming units.

As shown in FIG. 2, the electrostatic latent images formed on the photosensitive drums 20Y, 20M, 20C, and 20K are respectively yellow (Y) and magenta (M) by developing devices 22Y, 22M, 22C, and 22K. ), Cyan (C), and black (K) toner images.

  Yellow (Y), magenta (M), cyan (C), and black (K) sequentially formed on the photosensitive drums 20Y, 20M, 20C, and 20K of the image forming units 7Y, 7M, 7C, and 7K. The toner images of the respective colors are respectively transferred to primary transfer rolls 25Y, 25M, 25C, and 25K as primary transfer units on an intermediate transfer belt 8 as an intermediate transfer member disposed below the image forming units 7Y, 7M, 7C, and 7K. Are transferred in a superimposed state. The intermediate transfer belt 8 is wound around the drive roll 29, the idler roll 30, the tension roll 31, the idler roll 32, the backup roll 33, and the idler roll 34 with a constant tension. The drive roll 29 is rotationally driven by a dedicated drive motor with excellent constant speed and is circulated at a predetermined speed in the direction of the arrow. As the intermediate transfer belt 8, for example, a flexible synthetic resin film such as polyimide is formed in a strip shape, and both ends of the synthetic resin film formed in a strip shape are connected by means such as welding, thereby being endless. A belt-shaped one is used.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred onto the intermediate transfer belt 8 in multiple layers are pressed against the backup roll 33 at a predetermined timing. The recording paper 10 that has been secondarily transferred onto the recording paper 10 by a pressure contact force and electrostatic force by a secondary transfer roll 39 as a transfer means, and onto which the toner images of these colors have been transferred, is fixed by a not-shown transport belt or transport roll. It is conveyed to the device 11. The recording paper 10 onto which the toner images of the respective colors have been transferred undergoes a fixing process with heat and pressure by the fixing device 11 and is discharged onto a discharge tray (not shown) provided outside the copying machine main body 1.

  As shown in FIG. 2, the recording paper 10 having a desired size from the paper feed tray 9 is a paper transport path provided with a paper feed roller 36, a paper separation roller pair 37, and a paper transport roller pair 38. The paper is once transported to the resist roll 40 through a state 38a and is stopped. The recording paper 10 supplied from the paper feed tray 9 is sent onto the intermediate transfer belt 8 by a registration roll 40 that is driven to rotate at a predetermined timing in synchronization with the toner image on the intermediate transfer belt 8.

  Prior to that, in the four image forming units 7Y, 7M, 7C, and 7K for yellow, magenta, cyan, and black, as described above, the yellow, magenta, cyan, and black toner images are respectively generated at predetermined timings. They are formed sequentially.

  Further, the upper surface of the tandem digital color copying machine main body 1 configured as described above includes a display 41 for displaying messages and a keyboard 42 for an operator to input various commands. An operation unit 43 is provided.

  The photosensitive drums 20Y, 20M, 20C, and 20K, after the toner image transfer process is completed, the residual toner and paper dust are removed by the cleaning devices 24Y, 24M, 24C, and 24K, and the next image formation is performed. Prepare for the process. Further, residual toner and the like are removed from the intermediate transfer belt 8 by the belt cleaner 44.

  By the way, in this embodiment, a process cartridge having an image carrier is configured to be detachable from the apparatus main body, and the process cartridge is attached to the apparatus main body so that the image carrier of the process cartridge is attached to the apparatus main body. In an image forming apparatus that is driven by being fitted to a provided rotation shaft, flange members are provided at both ends in the axial direction of the image carrier, and the flange member is fitted to a rotation shaft provided in the apparatus main body. At the same time, each flange member of the image carrier is rotatably supported on each side plate of the process cartridge via a bearing member.

In this embodiment, the flange member of the image carrier is made of a thermoplastic resin, and the linear expansion coefficient of the thermoplastic resin is 5 × 10 ⁻⁵ or less.

  Further, in this embodiment, the bearing member, the flange member of the image carrier, and the pressurizing position of the tracking member of the developing unit are configured to coincide at least in the thrust direction.

  Further, in this embodiment, the flange member of the image carrier integrally forms the press-fitting part of the image carrier to the cylindrical base, the fitting part of the bearing member, and the fitting part to the rotating shaft. It is comprised so that it may have.

  Further, in this embodiment, one flange member of the image carrier is integrally provided with a connecting portion that engages with the rotation shaft and transmits the rotational driving force.

That is, in this embodiment, as shown in FIGS. 4A and 4B, in each of the yellow, magenta, cyan, and black image forming portions 7Y, 7M, 7C, and 7K, a photoconductor as an image carrier. The drum 20, the charging devices 21 and 25, and the cleaning device 24 are integrally provided to constitute a process cartridge 45 that can be attached to and detached from the apparatus main body 1. As shown in FIGS. 4A and 4B, the process cartridge 45 includes a photosensitive drum 20, and the photosensitive drum 20 includes, for example, a cylindrical cored bar 46 made of metal such as aluminum. The surface is coated with a photoconductive material 47 such as OPC. Among the photosensitive drums 20, the yellow, magenta, and cyan color photosensitive drums 20 have a diameter φ set to 40 mm, for example, and the black photosensitive drum 20K has a diameter φ of, for example, Is set to 60 mm.
FIG. 5 is an external perspective view showing the process cartridge 45 for black.

As shown in FIGS. 1 and 6, flange members 48 and 49 are provided at both ends of the photosensitive drum 20, and the flange members 48 and 49 are cylindrical core bars 46 of the photosensitive drum 20. It is attached in a state in which it is fitted and fixed to both ends. The flange members 48 and 49 are made of, for example, a thermoplastic resin. As the thermoplastic resin that constitutes the flange members 48 and 49, one having a linear expansion coefficient that is significantly smaller than that of metal is used. . As the thermoplastic resin whose linear expansion coefficient is significantly smaller than that of metal (for example, aluminum), for example, PC filled with glass fiber, modified PPO, or the like is used. The linear expansion coefficient of these thermoplastic resins is about 1.5 to 2.5 × 10 ⁻⁵ , and is 5 × 10 ⁻⁵ or less.

  Of these flange members 48 and 49, the flange member 43 disposed on the front side of the apparatus main body 1 is fitted to the end portion of the cylindrical metal core 41 of the photosensitive drum 20, as shown in FIG. A large-diameter portion 50 having a large diameter, a tapered portion 51 projecting in a tapered shape toward the outside in the axial direction of the large-diameter portion 50, and a diameter projecting outward in the axial direction at the tip portion of the tapered portion 51 And a small-diameter portion 52 having a small diameter. The small-diameter portion 52 is provided with a fixing portion 52a whose inner diameter is set substantially equal to the outer diameter of the rotating shaft 53, and the rotating shaft 53 is configured to be fitted and fixed to the fixing portion 52a. ing. A bearing portion 52b is provided at the tip of the small diameter portion 52, and a rolling bearing 54 as a bearing member is fitted to the outer periphery of the bearing portion 52b. The fixing portion 52a and the bearing portion 52b of the flange member 43 are provided adjacent to each other along the axial direction of the flange member 43, and the load received by the fixing portion 52a is provided substantially outward in the radial direction. It can be supported by the bearing portion 52b.

  As shown in FIG. 1, the outer periphery of the rolling bearing 54 is attached in a state of being fitted to the side plate 55 of the process cartridge 45. A cover member 56 is attached to the side plate 55 of the process cartridge 45.

  On the other hand, among the flange members, the flange member 49 disposed on the back side of the apparatus main body 1 has a diameter fitted to the end portion of the cylindrical cored bar 41 of the photosensitive drum 20 as shown in FIG. A large large-diameter portion 57, a tapered portion 58 having an outer surface tapered toward the outside in the axial direction of the large-diameter portion 57, and a small-diameter portion 59 having a small diameter provided at the tip of the tapered portion 58. It consists of and. The small diameter portion 59 is provided with a fixing portion 59a whose inner diameter is set to be substantially equal to the outer diameter of the rotating shaft 53, and the rotating shaft 53 is fitted and fixed to the fixing portion 59a. ing. A bearing portion 59b is provided on the outer periphery of the fixed portion 59a of the small diameter portion 59, and a rolling bearing 60 as a bearing member is fitted on the outer periphery of the bearing portion 59b. . In the flange member 49 shown in FIG. 6, the tapered portion 58 is formed in a solid shape, but the tapered portion 58 may be formed in a hollow shape.

  As shown in FIG. 6, the outer periphery of the rolling bearing 60 is attached in a state of being fitted to the side plate 61 of the process cartridge 45. A cover member 62 is attached to the side plate 61 of the process cartridge 45.

  Further, as shown in FIG. 6, a rotating shaft 53 that is rotationally driven by a drive motor 66 is attached to the apparatus main body 1 side in a fixed state on the apparatus main body 1 side. The rotating shaft 53 has a base end portion 53a attached to the drive motor 66. For example, the base end portion 53a has a diameter of 15 mm, and an intermediate portion 53b inside the flange member 48 on the back side of the apparatus main body 1 has a diameter. 1 mm, the tip 53c shown in FIG. 1 has a diameter of 10 mm so that the tip 53c becomes thinner gradually or stepwise toward the tip.

  Further, as shown in FIG. 6, a movable engaging portion 63 as a connecting portion that engages with the rotating shaft 53 and transmits the rotational driving force is integrally formed with one flange member 49 of the photosensitive drum 20. Is provided. As shown in FIG. 7, four engaging recesses 64 are provided along the circumferential direction at the distal end of the small diameter portion 59 of the flange member 49, and the engaging recesses 64 rotate the photosensitive drum 20. The end surface 64a along the direction is formed in a planar shape along the axial direction, and the end surface along the direction opposite to the rotation direction is formed into an inclined curved surface.

  Further, as shown in FIG. 6, the rotary shaft 53 is provided with a movable engagement member 65 that relatively engages with the engagement portion 64 provided on the flange member 49 of the photosensitive drum 20. . The movable engagement member 65 is urged toward the tip end of the rotation shaft 53 by a spring (not shown), and the engagement member 65 is provided on the flange member 49 in a state where the process cartridge 45 is mounted on the apparatus main body 1. The photosensitive drum 20 is integrally rotated by the rotating shaft 53 by being relatively engaged with the joint portion 64.

  Further, as shown in FIG. 2, the developing rolls of the developing devices 22 and 26 are opposed to the photosensitive drum 20 of the process cartridge 45 through a predetermined gap DRS when mounted on the apparatus main body 1. It is arranged.

  Therefore, as shown in FIGS. 8 and 9, the process cartridge 45 is configured such that the developing devices 22 and 26 retract to the photosensitive drum 20 side with the process cartridge 45 mounted on the apparatus main body 1. Has been. A tracking roll 81 is rotatably attached to the developing devices 22 and 26 so that the gap DRS between the developing roll 80 and the photosensitive drum 20 is set to a predetermined value. The tracking roll 81 is disposed so as to contact the surface of the gap holding block 82 provided on the side plate of the process cartridge 45. The tracking roll 81 is arranged such that the rolling bearing, the small diameter portion of the flange member of the photosensitive drum, and the pressure position of the tracking roll of the developing device substantially coincide with each other in the thrust direction.

  As a result, even when the developing roll 80 of the developing devices 22 and 26 is brought into contact with the gap holding block 82 of the process cartridge 45 as described above, the load from the developing devices 22 and 26 is applied to the rolling bearings 54 and 60, It can be directly received by the rotating shaft 53 via the small diameter portions 52a and 59a of the flange members 48 and 49 of the photosensitive drum 20, and deformation such as bending may occur in the flange members 48 and 49 of the photosensitive drum 20. Absent. Therefore, the photosensitive drum 20 can be rotationally driven with high rotational accuracy.

  With the above configuration, in the image forming apparatus according to this embodiment, as described below, the size of the process cartridge is not increased and the cost is not increased, and the surface shake accuracy of the image carrier and the process cartridge are mounted. In addition to being able to improve the positional accuracy of each of the parts, it is possible to prevent the rotating shaft and rolling bearings from colliding with each other, and the attachment / detachment force does not increase unnecessarily, and the process cartridge is installed in the apparatus. It can be easily attached to and detached from the main body.

  That is, in the tandem digital color copying machine according to this embodiment, as shown in FIG. 2, yellow, magenta, cyan, and black image forming units 7Y, 7M, 7C, and 7K Cyan and black toner images are formed, and the toner images of these colors are once transferred onto the intermediate transfer belt 8 in a multiple manner, and then transferred onto the recording paper 10 from the intermediate transfer belt 8 in a secondary transfer. And fixed to form a color image or a black and white image.

  In the tandem digital color copying machine, the photoconductive layer of the photoconductive drum 20 of each of the image forming units 7Y, 7M, 7C, and 7K is worn while repeating many image forming operations. It may be necessary to replace the photosensitive drum 20.

  In this case, the photosensitive drum 20 constitutes the process cartridge 45 for each of the yellow, magenta, cyan, and black image forming units 7Y, 7M, 7C, and 7K, and therefore, the photosensitive drum 20 needs to be replaced. A user removes a certain process cartridge 45 from the apparatus main body 1 and attaches a new process cartridge 45 to the apparatus main body 1.

  At that time, as shown in FIGS. 1 and 6, the photosensitive drum 20 is mounted on the process cartridge 45, and the photosensitive drum 20 has flange members 48 and 49 provided at both ends thereof. And it is rotatably attached to the process cartridge 45 via a bearing member. Then, by mounting the process cartridge 45 at a predetermined position of the apparatus main body 1, the photosensitive drum 20 has a small diameter of flange members 48 and 49 provided at both ends thereof as shown in FIGS. The parts 52 and 59 are fitted and fixed to the rotary shaft 53 provided in a state fixed to the apparatus main body 1, and the engaging concave part 64 of the movable engaging part 63 and the movable engaging member 65 are relative to each other. The rotating shaft 53 and the photosensitive drum 20 are integrally connected, and the photosensitive drum 20 is driven to rotate.

  Thus, in the above-described embodiment, there is no need to provide an engagement means having a conical surface on the rotary shaft 53 as in the prior art, so that the process cartridge does not increase in size or cost, and The photosensitive drum 20 only needs to fit and fix the flange members 48 and 49 provided at both ends of the photosensitive drum 20 to the rotating shaft 53 provided in the apparatus main body 1. The position accuracy of each component mounted on the process cartridge 45 can be improved, the rotation shaft 53 and the rolling bearings 54 and 60 can be prevented from colliding with each other, and the attachment / detachment force does not increase unnecessarily. Can be easily attached to and detached from the apparatus main body 1.

  In the above embodiment, as described above, even when the developing roll 80 of the developing devices 22 and 26 is brought into contact with the gap holding block 82 of the process cartridge 45, the load from the developing devices 22 and 26 is reduced. It can be directly received by the rotating shaft 53 via the rolling bearings 54 and 60 and the small diameter portions 52a and 59a of the flange members 48 and 49 of the photosensitive drum 20, and the flange members 48 and 49 of the photosensitive drum 20 are bent. No deformation occurs. Therefore, the photosensitive drum 20 can be rotationally driven with high rotational accuracy.

FIG. 1 is a block diagram showing a main part of a process cartridge used in a tandem type digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a tandem type digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 3 is a block diagram showing the ROS. FIGS. 4A and 4B are configuration diagrams showing color and black process cartridges used in a tandem type digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 5 is a perspective view showing a black process cartridge used in a tandem type digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 6 is a block diagram showing a main part of a process cartridge used in a tandem type digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 7 is a block diagram showing the movable engaging portion of the process cartridge. FIG. 8 is a block diagram showing a main part of a process cartridge used in a tandem type digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention. FIG. 9 is a block diagram showing a main part of a process cartridge used in a tandem type digital color copying machine as an image forming apparatus according to Embodiment 1 of the present invention.

Explanation of symbols

  20: photosensitive drum (image carrier), 45: process cartridge, 48, 49: flange member, 53: rotating shaft, 54, 60: rolling bearing, 56, 61: side plate.

Claims (7)

A process cartridge having an image carrier is configured to be detachable from the apparatus main body, and the process cartridge is attached to the apparatus main body so that the image carrier of the process cartridge is fitted to a rotation shaft provided in the apparatus main body. In the image forming apparatus to be driven, flange members are provided at both ends in the axial direction of the image carrier, and the flange members are fitted to rotation shafts provided in the apparatus main body. An image forming apparatus, wherein a flange member is rotatably supported on each side plate of the process cartridge via a bearing member. 2. The image forming apparatus according to claim 1, wherein the flange member of the image carrier is made of a thermoplastic resin, and the linear expansion coefficient of the thermoplastic resin is 5 × 10 ⁻⁵ or less. 3. The image forming apparatus according to claim 1, wherein the bearing member, the flange member of the image carrier, and the pressure position of the tracking member of the developing unit are configured to coincide with each other at least in the thrust direction. apparatus. The flange member of the image carrier integrally includes a press-fitting portion of the image carrier to the cylindrical base, a fitting portion of the bearing member, and a fitting portion to the rotating shaft. The image forming apparatus according to claim 1. 5. The image according to claim 1, wherein one of the flange members of the image carrier is integrally provided with a connecting portion that engages with a rotation shaft and transmits a rotational driving force. Forming equipment. In a process cartridge having an image carrier and configured to be detachable from the apparatus main body, flange members are respectively provided at both ends in the axial direction of the image carrier, and the flange member is a rotation shaft provided in the apparatus main body. And a flange member of the image carrier is rotatably supported on each side plate of the process cartridge via a bearing member. An electrophotographic photosensitive drum rotatably mounted on a process cartridge configured to be detachable from the apparatus main body, wherein the electrophotographic photosensitive drum is provided with flange members at both ends in the axial direction thereof, The photographic photosensitive drum is configured to be freely engageable with a rotary shaft provided in the apparatus main body via a flange member, and each flange member of the electrophotographic photosensitive drum is respectively a bearing member on each side plate of the process cartridge. An electrophotographic photosensitive drum, characterized in that it is supported so as to be freely rotatable via a roller.

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