JP2019032488A - Separation pawl holding device, rotor device, and image formation device - Google Patents

Abstract

To provide an easy configuration which prevents a tension coil spring 73 for energizing a separation pawl 72 from being detached by impact.SOLUTION: A separation pawl 72 rotates by being energized by a tension coil spring 73, so as to be in a contact state with a photoreceptor drum 31. A pressing part 80 of a separation pawl cover 79 rotates the separation pawl 72 in a direction away from the photoreceptor drum 31, and holds it in a state where energizing force of the tension coil spring 73 is larger than that in the contact state. Thus, the tension coil spring 73 for energizing the separation pawl 72 is difficult to be detached by impact with a simple configuration.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a separation claw holding device that moves and holds a separation claw.

  2. Description of the Related Art Image forming apparatuses having a separation claw for separating a sheet adsorbed from a rotating body such as a photosensitive drum or a fixing roller are widely used. The separation claw is urged by the urging means and makes contact with the adsorbed sheet front end in a state where the front end of the claw is in contact with the surface of the rotary body to separate the sheet from the rotary body.

  Here, if an impact or the like is received during packaging and transport of the image forming apparatus, the urging means may be removed. Therefore, Patent Document 1 proposes a configuration in which the separation claw is made difficult to come off due to impact or the like by increasing the contact pressure of the separation claw to the fixing roller.

JP 2008-83694 A

  However, as in Patent Document 1, if the contact pressure of the separation claw with respect to the rotating body is increased in order to make it difficult to remove the separation claw due to an impact or the like, the surface of the rotating body that always rotates in contact with the separation claw may be damaged. is there. In addition, the wear at the contact points of both sliding due to the rotation of the rotating body increases, leading to a shortened life.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a configuration in which an urging means that urges a separation claw by an impact or the like can be easily removed with an easy configuration.

  The separation claw holding device of the present invention rotates the separation claw in contact with the rotating body by being urged by the urging means to rotate in a direction away from the rotating body. And a holding means for holding the urging force of the urging means in a large state.

  According to the present invention, the urging means for urging the separation claw by an impact or the like can be easily removed with an easy configuration.

1 is an explanatory diagram of an overall structure of a copying machine according to a first embodiment. It is sectional drawing of a photosensitive drum unit. (A) is a photosensitive drum unit, and (b) is a sheet separation mechanism. It is a perspective view of a photosensitive drum unit. It is explanatory drawing of a sheet separation mechanism. (A) is an overall view of the sheet separating mechanism, and (b) is a partially enlarged view. It is explanatory drawing of the attachment procedure of a sheet separation mechanism. (A) is a disassembled state, (b) is an assembled state, and (c) is an attachment process. It is sectional drawing of the drum unit equipped with the separation claw cover. (A) is a photosensitive drum unit, and (b) is a sheet separation mechanism. It is explanatory drawing of operation | movement of a separation nail | claw cover. (A) is before the separation claw cover is mounted, and (b) is after the separation claw cover is mounted. It is explanatory drawing of the installation procedure of a separation nail | claw cover. (A) is a mounting process, and (b) is a mounting state.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Embodiment 1>
In the first embodiment, an embodiment of a separation claw holding device that also serves as a separation claw cover that can be attached to and detached from the photosensitive drum unit of the image forming apparatus will be described.

(Copier)
FIG. 1 is an explanatory diagram of the overall structure of the copying machine according to the first embodiment. As shown in FIG. 1, a copying machine 1 as an example of an image forming apparatus is equipped with an image reading device 6 that reads an image of a document on the upper part of an apparatus main body 1A that executes an image forming process. In the image reading device 6, a document pressing plate 63 is disposed on a transparent glass 61 on which the document G is placed so as to be opened and closed. The reading unit 62 reads the image of the original G by moving below the transparent glass 61.

  The image forming unit 3 and the fixing device 4 that are examples of image forming units execute image formation on the sheet P that is supplied from the sheet feeding unit 2 that is disposed below the apparatus main body 1A that is an example of the main body casing. To do. The copying machine 1 is detachably equipped with a photosensitive drum unit 30 (rotating body unit) in a shipping state in the apparatus main body 1A.

(Paper Feeder)
The sheet feeding unit 2 supplies the sheet P stored in the cassette 21 to the image forming unit 3. The pickup roller 22 feeds the sheets P stacked on the cassette 21 to the separation unit 23. The separation unit 23 forms a nip with the normal rotation roller and the reverse rotation roller. The normal rotation roller of the separation unit 23 transfers the uppermost sheet P to the conveyance roller 10 disposed on the downstream side and conveys it to the registration roller 11. The reversing roller of the separation unit 23 separates the multi-feed sheet overlapped with the uppermost sheet P and pushes it back to the cassette 21. The registration roller 11 corrects the skew of the sheet P by bringing the leading end of the sheet P into contact with the nip in the stopped state. The registration roller 11 starts to rotate in synchronization with the toner image on the photosensitive drum 31, and conveys the sheet P to the transfer nip portion N1.

  When the sheets stacked on the manual feed tray 25 are used, the uppermost sheet is separated one by one by the supply roller 26 and the separation pad 24 and is transferred to the conveyance roller 27 disposed on the downstream side. The conveyance roller 27 conveys the sheet to the registration roller 11. The registration roller 11 corrects the skew of the sheet P in the same manner as when the sheet P is fed from the cassette 21, and then conveys the sheet P to the transfer nip portion N1.

(Image forming part)
The image forming unit 3 includes a charging roller 32, an exposure device 33, a developing device 34, a transfer roller 35, and a drum cleaning device 36 around the photosensitive drum 31. The photosensitive drum 31 has a photosensitive layer formed on the surface of a metal cylinder, and rotates at a peripheral speed equal to the process speed of the electrophotographic process.

  The charging roller 32 applies a charging voltage to charge the peripheral surface of the photosensitive drum 31 to a uniform potential. The exposure device 33 scans the peripheral surface of the charged photosensitive drum 31 with a laser beam to reduce the potential of the exposed region, thereby forming an electrostatic latent image of the image on the peripheral surface of the photosensitive drum 31. . The exposure device 33 controls the output of the laser beam based on the image data of the original G read by the image reading device 6 and the image data transmitted from an external computer.

  The developing device 34 develops the electrostatic latent image formed on the photosensitive drum 31 with toner to form a toner image. The developing device 34 carries the charged toner on the rotating developing roller 14 and develops the electrostatic latent image on the opposing photosensitive drum 31 into a toner image.

  The transfer roller 35 contacts the photosensitive drum 31 to form a transfer nip portion N1. The transfer roller 35 is applied with a DC voltage having a polarity opposite to the charging polarity of the toner, and transfers the toner image on the photosensitive drum 31 onto the sheet P passing through the transfer nip portion N1.

  The sheet P on which the toner image is transferred at the transfer nip portion N1 is conveyed to the fixing device 4. The fixing device 4 forms a fixing nip portion N2 between a fixing belt unit 41 provided with a heating element and a pressure roller 42 provided with an elastic layer. The fixing device 4 is a so-called on-demand fixing method in which a heating element heats the sheet P via an endless belt. The fixing device 4 fixes the image on the sheet P by melting the toner image by heat and pressure in the process in which the sheet P to which the toner image is transferred at the transfer nip portion N1 passes through the fixing nip portion N2.

  The sheet P on which the image is fixed by the fixing device 4 is conveyed to the sheet discharge unit 5. The sheet discharge unit 5 discharges and stacks the sheet P on which the image is fixed to the discharge tray 52 by the discharge roller 51.

  On the right side of the image forming unit 3 and the fixing device 4, a sheet refeeding unit 50 for performing double-sided printing on the sheet P is provided. When the double-sided printing mode is selected by the user, the sheet P on which the image is fixed on the first surface in the fixing device 4 is conveyed to the reverse roller 53. The reverse roller 53 reverses the conveyance direction of the sheet P from the arrow D1 direction to the arrow D2 direction. When the flapper 54 connects the conveyance path to the double-sided conveyance path 55 in conjunction with the reversal of the conveyance direction, the sheet P is fed into the double-sided conveyance path 55 in a reversed state in which the leading edge and the trailing edge are switched. The sheet P is conveyed again to the registration roller 11, passes through the transfer nip portion N1 in a reversed state, and the toner image is also transferred to the second surface.

(Photosensitive drum unit)
FIG. 2 is a sectional view of the photosensitive drum unit. 2A shows a photosensitive drum unit, and FIG. 2B shows a sheet separating mechanism.

  As shown in FIG. 2A, the photosensitive drum 31, the charging roller 32, and the drum cleaning device 36 constitute a photosensitive drum unit 30. The photosensitive drum unit 30 is provided as a consumable replacement part, a maintenance part, or a spare part that can be integrally attached to and detached from the apparatus main body 1A of the copying machine 1 shown in FIG.

(Sheet separation mechanism)
FIG. 3 is a perspective view of the photosensitive drum unit. FIG. 4 is an explanatory diagram of the sheet separating mechanism. 4A is an overall view of the sheet separating mechanism, and FIG. 4B is a partially enlarged view. As shown in FIG. 3, a sheet separation mechanism 70 is attached to the outer wall of the drum cleaning device 36 of the photosensitive drum unit 30. FIG. 2A shows a state in which the CC cross section shown in FIG.

  As shown in FIG. 2A, the toner image is transferred from the photosensitive drum 31 to the sheet P while the sheet P passes through the transfer nip portion N1. The sheet P is normally separated from the photosensitive drum 31 by the curvature on the downstream side of the transfer nip portion N1. However, the separability is lowered depending on the use environment and the type of the sheet, and the drum P that is electrostatically attracted to the surface of the photosensitive drum 31 at the transfer nip portion N1 is rotated around the photosensitive drum 31 without being separated. When entering the inside of the sheet 36, sheet jam occurs and image formation is urgently stopped.

  Therefore, the photosensitive drum unit 30 is provided with a sheet separating mechanism 70 on the downstream side in the arrow E direction from the transfer nip portion N1 on the peripheral surface of the photosensitive drum 31. The sheet separation mechanism 70 separates the leading end of the sheet P conveyed in the direction of arrow E from the peripheral surface of the photosensitive drum 31 by the separation claw 72. As shown in FIG. 2B, the separation pawl 72 is urged by a tension coil spring 73 which is an example of an urging means, so that the tip 75 (contact portion) is a photosensitive drum 31 which is an example of a rotating body. Is in contact with The separation claw 72 inserts the leading end 75 between the sheet adhering to the photosensitive drum 31 and the photosensitive drum 31 to forcibly separate the sheet from the peripheral surface of the photosensitive drum 31.

  As shown in FIG. 4A, the sheet separation mechanism 70 is provided with three sets of separation claws 72, a tension coil spring 73, and a spur 74 on a support substrate 71. A support substrate 71 to which three separation claws 72 are attached is attached to the photosensitive drum unit 30, and the three separation claws 72 are in contact with the cylindrical peripheral surface of the photosensitive drum 31. The separation claws 72 are provided at the center portion and both end portions of the support substrate 71 in the longitudinal direction. The separation claws 72 at both ends are arranged at a distance a of 100 mm from the separation claws 72 at the center so that the B5 size sheet can be separated by the three separation claws 72.

  As shown in FIG. 4B, the separation claw 72 is attached to the support substrate 71 by a rotation shaft 76 so as to be rotatable in a direction in which the tip 75 (contact portion) contacts and separates from the photosensitive drum 31. It has been. The support substrate 71 is provided with a spur 74 near the separation claw 72.

  As shown in FIG. 2B, the spur 74 is interposed between the sheet separated from the photosensitive drum 31 by the separation claw 72 and the support substrate 71, and the sheet P contacts the separation claw 72 and is fixed. This prevents the previous toner image from being disturbed. The position of the spur 74 is arranged so that the sheet P separated by the separation claw 72 does not thrust into the spur 74 at an acute angle in order to avoid sheet jam.

  As shown in FIG. 4B, the stopper 78 of the support substrate 71 abuts on the separation claw 72 rotated from the photosensitive drum 31 to regulate the rotation angle of the separation claw 72. In the present embodiment, the angle range in which the separation claw 72 can be rotated is restricted to 41 ° by the stopper 78. The stopper 78 comes into contact with the rotating end of the separation claw 72 through a notch formed in the support substrate 71.

(Assembly of sheet separation mechanism)
FIG. 5 is an explanatory diagram of the attachment procedure of the sheet separating mechanism. 5A is an exploded state, FIG. 5B is an assembled state, and FIG. 5C is an attachment process. As shown in FIG. 5A, three sets of separation claws 72, a tension coil spring 73, and a spur 74 are assembled on one support substrate 71, and the sheet separation as shown in FIG. 5B is performed. A mechanism 70 is obtained. As shown in FIG. 5C, the sheet separating mechanism 70 is attached to the female screw 38 of the photosensitive drum unit 30 by passing the mounting screws 84 through the fixing holes 77 of the support substrate 71 at three locations at the center and both ends. It is attached to the photosensitive drum unit 30.

(Tension coil spring)
As shown in FIG. 2B, the tension coil spring 73, which is an example of an urging unit, urges the separation claw 72 to bring the tip 75 (contact portion) into contact with the photosensitive drum 31. The tension coil spring 73 is disposed downstream of the rotation shaft 76 in the direction of arrow E (sheet conveyance direction), and both ends thereof are respectively attached to the attachment portion 82 on the separation claw 72 side and the attachment portion 83 on the support substrate 71 side. Yes. Since the length of the tension coil spring 73 is as small as about 10 mm, considering the workability, the hook shape is a round hook or a square hook, and the attachment portion 82 on the separation claw 72 side and the attachment portion on the support substrate 71 side. 83, hooks at both ends of the spring are hooked. The tension coil spring 73 urges the separation claw 72 in the clockwise direction in the drawing around the rotation shaft 76 to bring the tip 75 of the separation claw 72 into contact with the peripheral surface of the photosensitive drum 31. In the present embodiment, the angle A formed by the line F connecting the tip 75 and the rotation shaft 76 and the horizontal direction with the tip 75 of the separation claw 72 in contact with the photosensitive drum 31 is set to 98 °. ing.

  The peripheral surface of the photosensitive drum 31 is coated with a surface layer of a resin material such as a photosensitive layer in order to form an electrostatic latent image. Since the surface layer of the resin material is soft and easily damaged, the sheet separating mechanism 70 makes the tip 75 of the separation claw 72 abut against the peripheral surface of the photosensitive drum 31 with a small pressure. The separation claw 72 is in contact with the photosensitive drum 31 with a light pressure of 5 gf (0.049 N) or less so as not to damage the surface layer of the peripheral surface of the photosensitive drum 31. Specifically, the urging force of the tension coil spring 73 is set to 0.5 gf (0.0049 N). The total pressure exerted on the photosensitive drum 31 by the tip 75 of the separation claw 72 is 0.05 gf (0.00049 N) due to the moments at both ends of the separation claw 72 around the rotation shaft 76 and the inclination angle of the tension coil spring 73. It is weakened.

  For this reason, if vibration or impact is applied during transportation of the photosensitive drum unit 30 while the separation claw 72 is in contact with the photosensitive drum 31 with such a light pressure, a round hook or a square hook is taken into consideration in consideration of workability. There is a possibility that the tension coil spring 73 that is hooked in the normal hook shape is detached from the attachment portion 82 on the separation claw 72 side or the attachment portion 83 on the support substrate 71 side.

  Therefore, in the first embodiment, at the time of shipment or transportation, the separation claw 72 is retracted from the photosensitive drum 31 while being pulled away from the photosensitive drum 31 by the separation claw cover 79 that is a protective member that is attached to the photosensitive drum unit 30 and covers the separation claw 72. A mechanism for pulling the coil spring 73 and increasing the urging force was provided. This prevents the tension coil spring 73 from coming off due to vibration or impact applied during transportation or the like without increasing the contact pressure of the separation claw 72 in contact with the photosensitive drum 31 during image formation. The separation claw cover 79 is removed from the photosensitive drum unit 30 at the start of use.

(Separate nail cover)
FIG. 6 is a sectional view of the photosensitive drum unit 30 to which the separation claw cover 79 is attached. 6A shows the entire photosensitive drum unit, and FIG. 6B shows an enlarged view of the sheet separating mechanism 70. As shown in FIG. 6A, a separation claw cover 79 is attached to the outer wall of the drum cleaning device 36 of the photosensitive drum unit 30 so as to cover the sheet separation mechanism 70. The separation claw cover 79 is attached to the photosensitive drum unit 30 and covers and protects the support substrate 71, separation claw 72, tension coil spring 73, and spur 74 of the sheet separation mechanism 70.

  As shown in FIG. 6B, the separation claw cover 79, which is an example of a separation claw holding device, includes a cover part 79A, which is an example of a cover means, and a pressing part 80, which is an example of a holding means. The separation claw cover 79 is attached to the photosensitive drum unit 30, and the separation claw 72 is separated from the photosensitive drum 31, and is pulled more than the contact state where the tip 75 (contact portion) is in contact with the photosensitive drum 31. The urging force of the coil spring 73 is held in a large state. For this reason, the tension coil spring 73 is difficult to come off when vibrations or impacts are applied during transportation of the photosensitive drum unit 30 or the copying machine 1 including the photosensitive drum unit 30.

  The separation claw 72 is rotatable about a rotation shaft 76. The pressing portion 80 pulls the separation claw 72 on the side opposite to the tip 75 sandwiching the rotation shaft 76 so as to resist the urging force of the coil spring 73. The separation claw 72 is rotated by being pressed by the pressing portion 80, whereby the urging force of the tension coil spring 73 becomes larger than the contact state where the tip 75 is in contact with the photosensitive drum 31. For this reason, the tension coil spring 73 can be made difficult to come off with a simple structure in which the pressing portion 80 is provided on the separation claw cover 79. Further, the tip 75 of the separation claw 72 can be retracted from the circumferential surface of the photosensitive drum 31 with a simple mechanism while supporting the separation claw 72 with a simple mechanism.

  The separation claw cover 79 can be attached to and detached from the photosensitive drum unit 30 as a rotating body unit including the photosensitive drum 31 and the separation claw 72. The pressing portion 80 moves the separation claw 72 with the attachment or removal of the separation claw cover 79 to increase or decrease the urging force of the tension coil spring 73. The rotating body device 90 is configured with the separation claw cover 79 attached to the photosensitive drum unit 30.

  The cover portion 79 </ b> A, which is an example of cover means, covers the photosensitive drum unit 30 including the tension coil spring 73 in a state where the pressing portion 80 is mounted on the photosensitive drum unit 30. For this reason, the tension coil spring 73 with increased urging force can be held inside the separation claw cover 79, and surrounding objects and operator's fingers interfere with the tension coil spring 73 when the photosensitive drum unit 30 is transported or stored. Can be prevented.

  The pressing portion 80 is a protruding portion that protrudes from the cover portion 79 </ b> A toward the separation claw 72 and moves the separation claw 72 as the separation claw cover 79 is attached to the photosensitive drum unit 30. That is, on the inner side of the cover portion 79A, rod-like (boss-like) pressing portions 80 are provided for the plurality of separation claws 72 of the photosensitive drum unit 30, respectively. For this reason, a mechanism for increasing the biasing force of the tension coil spring 73, such as a slight design change from the existing separation claw cover 79, can be realized at low cost.

  Thus, the cover portion 79 </ b> A provided with the pressing portions 80 corresponding to the plurality of separation claws 72 on the inside moves the plurality of separation claws 72 together with the attachment of the separation claw cover 79. For this reason, it is possible to simultaneously increase or decrease the urging forces of the plurality of tension coil springs 73 by mounting or removing one member, the separation claw cover 79.

  As described above, when the separation claw cover 79 is attached to the photosensitive drum unit 30, the pressing portion 80 provided on the separation claw cover 79 is positioned on the downstream side in the sheet conveyance direction with respect to the rotation shaft 76 of the separation claw 72. Press. As a result, the urging force of the tension coil spring 73 is increased, and at the same time, the tip 75 of the separation claw 72 is separated from the photosensitive drum 31. When the pressing portion 80 presses the separation claw 72, the length of the coil portion of the tension coil spring 73 is extended. The urging force F of the tension coil spring 73 is 0.5 gf when the separation claw cover 79 is removed, but 0.7 gf (0.0069 N) when the separation claw cover 79 is attached. However, the urging force F in the mounted state of the separation claw cover 79 may be larger than 0.7 gf.

  The pressing portion 80 is set in length so that the tip 75 of the separation claw 72 is separated from the photosensitive drum 31 when the separation claw cover 79 is attached to the photosensitive drum unit 30. When the separation claw cover 79 is attached to the photosensitive drum unit 30, the pressing unit 80 pushes the separation claw 72 by 0.4 mm, and the angle B formed by the line connecting the tip 75 and the rotation shaft 76 with the horizontal direction is 115. Designed to be °. As a result, the tip 75 of the separation claw 72 is separated from the circumferential surface of the photosensitive drum 31 by a distance c = 3.5 mm, and is prevented from coming into contact with the circumferential surface of the photosensitive drum 31.

  In order to prevent the pressing portion 80 from pushing the passive portion 86 of the separation claw 72 too much, an abutting portion 81 against the photosensitive drum unit 30 is provided on the upper portion of the separation claw cover 79. In this embodiment, a clearance of a distance d of 0.2 mm is secured between the separation claw cover 79 and the photosensitive drum unit 30 in a state where the abutting portion 81 is abutted against the outer wall of the drum cleaning device 36. The amount by which the pressing unit 80 presses the separation claw 72 is 0.6 mm at the maximum.

(Photosensitive drum unit as shipped)
As shown in FIG. 6A, the photosensitive drum unit 30 that is a replacement part is shipped as a rotating body device 90 with a separation claw cover 79 attached thereto. The separation claw cover 79 is attached when the photosensitive drum unit 30 is manufactured at the factory, and protects the photosensitive drum 31 and the separation claw 72 during transportation, storage, and unpacking at the site. The separation claw cover 79 is removed before the photosensitive drum unit 30 is attached to the copying machine 1 shown in FIG.

  When the copying machine 1 is shipped or transported, the photosensitive drum unit 30 may be removed from the apparatus main body 1A and packed separately from the apparatus main body 1A. Further, after the photosensitive drum unit 30 is assembled as shown in FIG. 5, the photosensitive drum unit 30 is shipped alone as a replacement part, and stored for a long time as a stock at the user's office. The photosensitive drum unit 30 is attached to the separation claw cover 79 as a rotating body device 90 so that the photosensitive drum unit 30 can be connected to the separation claw 72 at the time of single shipment, stock storage, attachment to the copying machine 1, and maintenance such as replacement. The photosensitive drum 31 is prevented from being damaged by the collision.

  Further, in the copying machine 1 of FIG. 1 shipped as a new product, a separation claw cover 79 may be attached to the photosensitive drum unit 30 mounted on the apparatus main body 1A as shown in FIG. As shown in FIG. 1, a photosensitive drum unit 30 that is an example of a rotating body unit may be detachably mounted on the apparatus main body 1A that forms an image on a sheet.

  At the installation destination of the image forming apparatus 1, the photosensitive drum unit 30 is taken out from the apparatus main body 1A, the separation claw cover 79 is removed from the photosensitive drum unit 30, and the photosensitive drum unit 30 is attached to the apparatus main body 1A again. When the copier 1 shipped as a new product is set up at the shipping destination, a service person or a user takes it out of the photosensitive drum unit 30 from the apparatus main body 1A and removes the separation claw cover 79. The service person returns the photosensitive drum unit 30 from which the separation claw cover 79 has been removed to the apparatus main body 1A to complete the setup of the apparatus main body.

(Attaching the separation claw cover)
FIG. 7 is an explanatory view of the operation of the separation claw cover. FIG. 8 is an explanatory diagram of a procedure for attaching the separation claw cover. FIG. 7A is before the separation claw cover is attached, and FIG. 7B is after the separation claw cover is attached. FIG. 7 is an enlarged view of the cross section I shown in FIG. FIG. 8A shows a mounting process, and FIG. 8B shows a mounting state. FIG. 6A shows the state of the DD cross section shown in FIG.

  As shown in FIG. 7A, the tip 75 of the separation claw 72 is in contact with the peripheral surface of the photosensitive drum 31 by the urging force of the tension coil spring 73 before the separation claw cover 79 is attached. As shown in FIG. 7B, the pressing portion 80 presses the passive portion 86 on the downstream side in the direction of arrow E against the rotation shaft 76 of the separation claw 72 as the separation claw cover 79 is attached. As a result, the tip 75 of the separation claw 72 is separated from the surface of the photosensitive drum 31 in the direction of arrow H against the urging force of the tension coil spring 73, and a gap is formed between the photosensitive drum 31 and the tip 75. In a state where the separation claw cover 79 is attached, the state where the pressing portion 80 of the separation claw cover 79 presses the passive portion 86 is maintained, and the gap between the tip 75 and the photosensitive drum 31 is also maintained.

  As shown in FIG. 7A, when the separation claw cover 79 is removed from the photosensitive drum unit 30, the pressing unit 80 releases the pressing of the separation claw 72. Then, the tip 75 of the separation claw 72 comes into contact with the surface of the photosensitive drum 31 again by the urging force of the tension coil spring 73.

  As shown in FIG. 8A, a sheet separation mechanism 70 is attached to the photosensitive drum unit 30. An internal thread portion 37 is provided in the vicinity of the outer end portion of the sheet separating mechanism 70 in the longitudinal direction of the photosensitive drum unit 30.

  The separation claw cover 79 is provided with through holes 87 at both ends in the longitudinal direction. The separation claw cover 79 is attached to the photosensitive drum unit 30 by superimposing the through hole 87 on the female screw part 37 and inserting the attachment screw 85 through the through hole 87 and fastening it to the female screw part 37. Then, as shown in FIG. 8B, the sheet separation mechanism 70 is covered with a separation claw cover 79. Thereby, the separation claw cover 79 covers and protects the support substrate 71, the separation claw 72, the tension coil spring 73, and the spur 74.

(Effect of Embodiment 1)
In the case of the present embodiment, the tension coil spring 73 that biases the separation claw 72 by impact or the like can be made difficult to come off without increasing the contact pressure of the separation claw 72 with respect to the photosensitive drum 31. That is, the separation claw 72 is in contact with the peripheral surface of the photosensitive drum 31 with a small pressure during image formation or the like. For this reason, the peripheral surface of the photosensitive drum 31 is hardly damaged, and the life of the photosensitive drum 31 can be extended. On the other hand, when the copying machine 1 or the photosensitive drum unit 30 is transported, the separation claw cover 79 is attached to the photosensitive drum unit 30 to increase the urging force of the tension coil spring 73 while separating the tip 75 of the separation claw 72 from the photosensitive drum 31. doing. For this reason, it is possible to make it difficult to remove the tension coil spring 73 due to an impact applied during transportation or the like.

<Embodiment 2>
In the first embodiment, the embodiment in the sheet separating mechanism 70 that separates the sheet from the photosensitive drum 31 has been described. In contrast, in the second embodiment, an embodiment of a sheet separating mechanism attached to a rotating body other than the photosensitive drum 31 in the image forming apparatus will be described.

(Intermediate transfer belt)
An intermediate transfer type image forming apparatus that transfers a toner image formed on a photosensitive drum to an intermediate transfer belt, conveys the toner image transferred to the intermediate transfer belt to a transfer nip portion, and transfers it to a sheet is widely used. . The intermediate transfer type image forming apparatus is equipped with a sheet separation mechanism that uses a tension coil spring to slide the separation claw against the intermediate transfer belt in order to separate the sheet stuck to the intermediate transfer belt downstream of the transfer nip. May be. Also in such a sheet separating mechanism, it is possible to increase the urging force of the tension coil spring by mounting the same separation claw cover as in the first embodiment.

(Transfer belt)
2. Description of the Related Art A transfer belt type image forming apparatus that transfers a toner image formed on a photosensitive drum onto a sheet adsorbed on a transfer belt is widely used. In the transfer belt type image forming apparatus, a sheet separation mechanism is provided on the downstream side of the transfer belt to slidably contact the separation claw with the intermediate transfer belt using a tension coil spring in order to separate the sheet stuck to the transfer belt. There is a case. Also in such a sheet separating mechanism, it is possible to increase the urging force of the tension coil spring by mounting the same separation claw cover as in the first embodiment.

(Transfer roller)
In an image forming apparatus that transfers a toner image on a photosensitive drum to a sheet using a transfer roller, a sheet separation is made by sliding a separation claw using a tension coil spring to separate the sheet from the transfer roller on the downstream side of the transfer nip. A mechanism may be equipped. Also in such a sheet separating mechanism, it is possible to increase the urging force of the tension coil spring by mounting the same separation claw cover as in the first embodiment.

(Fixing device)
Even in a fixing device that heats a sheet at a fixing nip portion where the fixing roller and the pressure roller are in pressure contact, a separation claw is slidably contacted to the downstream side of the fixing nip portion of the fixing roller (pressure roller) using a tension coil spring. A sheet separation mechanism may be equipped. Also in such a sheet separating mechanism, it is possible to increase the urging force of the tension coil spring by mounting the same separation claw cover as in the first embodiment. The same applies to a fixing device that forms a fixing nip portion by pressing the fixing belt and the pressure belt.

<Other embodiments>
The separation claw holding device, the image carrier unit, and the image forming apparatus of the present invention are not limited to the specific configurations described in the first and second embodiments. Another embodiment in which a part or all of the configuration of the first and second embodiments is replaced with an equivalent configuration is also possible.

  In the first embodiment described above, the configuration using the tension coil spring as the biasing means for biasing the separation claw has been described. However, the urging means is not limited to the tension spring, and may be a spring that urges by extending from an elastically contracted state. In this case, for example, the urging means urges the distal end side from the rotation center of the separation claw, and the holding means urges the opposite side of the distal end across the rotation center. Furthermore, the urging means is not limited to a coil spring, but may be other configurations such as rubber or a leaf spring.

  In the above-described first embodiment, the configuration in which the separation claw is rotatably supported with respect to the rotation shaft has been described. However, the separation claw may be supported so as to be capable of other movements such as a slide movement, for example, as long as the separation claw can be moved in contact with and away from the rotating body such as a photosensitive drum.

  In the first embodiment, the embodiment of the photosensitive drum unit that can be replaced independently of the developing unit has been described. However, the present invention may be implemented as a process cartridge in which the developing device is integrated with the photosensitive drum unit. Alternatively, the present invention may be implemented as an integrated image forming unit including a transfer roller and a registration roller.

  In the first embodiment, the embodiment of the separation claw holding device that is detached from the photosensitive drum unit 30 when the photosensitive drum unit 30 is mounted on the apparatus main body 1A of the copying machine 1 has been described. However, the separation claw holding device may be incorporated into the photosensitive drum unit 30 so that it cannot be removed. This is because by incorporating the separation claw holding device into the photosensitive drum unit 30, the separation claw holding device can be operated manually or automatically as necessary to separate the separation claw 72 from the photosensitive drum 31.

  In the first embodiment, the embodiment of the separation claw holding device that also serves as the separation claw cover 79 that protects the separation claw 72 during transportation and storage of the photosensitive drum unit 30 has been described. However, the separation claw holding device may be configured as a dedicated member or mechanism independent of the separation claw cover that protects the separation claw 72.

  In the first embodiment, the embodiment in which the separation claw 72 is always in contact with the photosensitive drum 31 after the photosensitive drum unit 30 is mounted on the apparatus main body 1A of the copying machine 1 has been described. However, the separation claw 72 comes into contact with the photosensitive drum 31 when the standby state in which image formation can be performed, and the separation claw holding device is controlled so that the separation claw 72 is separated from the photosensitive drum 31 when the sleep mode state for waiting for image formation is entered. May be.

1: copier (image forming apparatus), 1A: apparatus main body, 2: paper feeding unit, 3: image forming unit (image forming unit), 4: fixing device (image forming unit), 5: sheet discharge unit, 11: Registration roller, 21: cassette, 22: pickup roller, 23: separation unit, 30: photosensitive drum unit (rotating body unit), 31: photosensitive drum (rotating body, image carrier), 32: charging roller, 35: transfer roller, 36: drum cleaning device, 37: female screw part, 38: female screw, 70: sheet separation mechanism, 71: support substrate, 72: separation claw, 73: tension coil spring (biasing means), 74: spur, 75: tip, 76 : Rotating shaft, 77: fixing hole, 78: stopper, 79: separation claw cover (separation claw holding device), 79A: cover part (cover means), 80: pressing part (holding means), 81: abutting part, 82 Mounting portion, 83: mounting portion, 84: mounting screw, 85: mounting screw, 86: driven mechanism, 90: rotational body device

Claims (7)

The separation claw that is in contact with the rotating body by rotating by being biased by the biasing means is rotated in a direction away from the rotating body, so that the biasing force of the biasing means is greater than that in the contact state. With holding means for holding in an enlarged state,
Separation claw holding device characterized by that. The separation claw is rotatable about a rotation axis, and is in contact with the rotating body at a contact portion,
The holding means presses the separation claw in a direction away from the rotating body on the side opposite to the contact portion across the rotation shaft.
The separation claw holding device according to claim 1 characterized by things. The separation claw holding device can be attached to a rotary body unit including the rotary body and the separation claw,
The holding means makes the urging force of the urging means larger than the contact state with the mounting.
3. The separation claw holding device according to claim 1 or 2, Cover means for attaching to the rotating body unit and covering the rotating body unit is further provided,
The holding means is a protruding part that protrudes from the cover means and moves the separation claw with the attachment.
The separation claw holding device according to claim 3 characterized by things. The holding means is provided for each of the plurality of separation claws,
The cover means integrally moves the plurality of separation claws with the attachment.
The separation claw holding device according to claim 4 characterized by things. The separation claw holding device according to any one of claims 1 to 5,
A rotating body,
A separation claw for separating a sheet from the rotating body by bringing a tip into contact with the rotating body;
Urging means for urging the separation claw so that the tip comes into contact with the rotating body,
The separation claw holding device holds the separation claw in a state where the urging force of the urging means is larger than the contact state.
A rotating body device characterized by that. An image forming unit for forming an image on a sheet;
The rotator device according to claim 6, which is detachably mounted on the image forming unit.
An image forming apparatus.

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