JP7237562B2 - photoreceptor unit - Google Patents

Description

The present invention relates to a photoreceptor unit having a photoreceptor.

As an image forming apparatus, there has been conventionally known a configuration in which a photosensitive member such as a photosensitive drum and parts such as a charging roller for charging the surface of the photosensitive member are integrally formed so that a photosensitive member unit is detachably attached to the main body of the apparatus. ing. In the case of a method in which the charging roller is brought into contact with the photoreceptor to charge, if the charging roller is left in contact with the photoreceptor for a long period of time, the charging roller is deformed. For this reason, there has been conventionally known a configuration in which the photoreceptor and the charging roller are separated from each other until the photoreceptor unit is attached to the apparatus main body.

For example, a configuration has been proposed in which a spacing member is arranged between the photoreceptor and the charging roller to separate the charging roller from the photoreceptor against the biasing force that urges the charging roller toward the photoreceptor (for example, , Patent Document 1). In the case of the configuration described in Patent Document 1, a gear (rotating member) that rotates together with the photoreceptor is provided, and the engaging portion of the spacing member is engaged with the gear to separate the photoreceptor and the charging roller. there is When the gear rotates together with the photoreceptor, the engagement between the gear and the spacing member is released, and the separation state of the charging roller and the photoreceptor by the spacing member is released.

Further, when the photoreceptor unit is being transported, the spacing member may move due to vibration applied to the photoreceptor unit, and the engagement between the spacing member and the gear may be disengaged. For this reason, in the configuration described in Patent Document 1, the spacing member has a concave portion, and in the spaced state, the concave portion is brought into contact with a photosensitive drum as a photoreceptor so that the spacing member is less likely to move due to vibration. are doing.

JP 2012-18265 A

However, in the case of the configuration described in Japanese Patent Application Laid-Open No. 2002-200310, when the photoreceptor unit is strongly vibrated and the spacing member moves away from the gear, there is a risk that the engaging portion of the spacing member and the gear will be disengaged. There is If the spacing member rotates while the engagement portion and the gear are disengaged, it may not be possible to prevent the photoreceptor from being released from the charging roller.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a structure capable of reducing unintentional release of the separated state between a photoreceptor and a charging roller even when a strong vibration is applied to the photoreceptor unit.

The photoreceptor unit of the present invention is provided movably at a rotatable photoreceptor, a contact position in contact with the surface of the photoreceptor, and a spaced position apart from the surface of the photoreceptor, and a voltage is applied at the contact position. a charging roller that charges the surface of the photoreceptor when a voltage is applied thereto; a bearing member that supports a rotating shaft of the charging roller; A force means, a rotating member that rotates when a driving force is input, a first engaging portion that can be engaged with the rotating member, and a second engaging portion that is provided at a position different from the first engaging portion. a separation holding position for holding the charging roller at the separation position against the biasing force of the biasing means in a state where the first engaging portion is engaged with the rotating member; and a separation release position where the charging roller is released from being held at the separation position when the engagement between the first engaging portion and the rotating member is disengaged. a spacing member that moves in a predetermined direction from the separation holding position to the separation release position when the rotary member is rotated by the input of the driving force; When the driving force is not input to the rotation member and the first engaging portion is disengaged and the separating member attempts to move in the predetermined direction, the engagement with the second engaging portion is disengaged. When the driving force is input to the rotary member at the separation holding position and the separation member tries to move in the predetermined direction, the separation member is prevented from moving in the predetermined direction. an engaged portion that allows the separation member to move toward the separation release position when the engagement is released , wherein the second engagement portion extends from the separation member along the rotation axis direction of the charging roller. the engaged portion is a bearing member-side projection projecting from the bearing member in a direction along the rotation axis direction of the charging roller; and the separation holding position When the driving force is not input to the rotating member and the engagement between the rotating member and the first engaging portion is disengaged and the separating member tries to move in the predetermined direction, the side collision of the bearing member occurs. The portion is capable of engaging with the spacer-member-side protrusion .

According to the present invention, even if a strong vibration is applied to the photoreceptor unit, it is possible to reduce unintentional release of the separated state between the photoreceptor and the charging roller.

1 is a cross-sectional view of a schematic configuration of an image forming apparatus according to a first embodiment; FIG. 1 is a cross-sectional view of a schematic configuration of a drum cartridge according to a first embodiment; FIG. FIG. 2 is a partial perspective view showing a schematic configuration of a drum cartridge according to the first embodiment; FIG. 2 is a partial perspective view showing the schematic configuration of the drum cartridge according to the first embodiment, omitting the spacing member and the frame. FIG. 4 is a partial perspective view showing the separated state of the drum cartridges according to the first embodiment; FIG. 6 is a partial perspective view showing the separated state of the drum cartridges according to the first embodiment, partly omitted from the left side of FIG. 5 ; 5A and 5B are schematic cross-sectional views respectively showing (a) a separated state and (b) a state in which the separated state is released, of the spacing member according to the first embodiment; FIG. 4 is a cross-sectional perspective view, partly omitted, showing the separated state of the drum cartridges according to the first embodiment. FIG. 4 is a cross-sectional perspective view, partly omitted, showing a state in which the separated state of the drum cartridges according to the first embodiment is released; FIG. 4 is an enlarged plan view showing the separated state of the drum cartridges according to the first embodiment, centering on the separating member; FIG. 4 is an enlarged plan view showing a state in which the separated state of the drum cartridges according to the first embodiment is released, centering on the separating member; FIG. 4 is a partial perspective view showing, with some parts omitted, how a gap is formed between the spacing member and the gear when the drum cartridge receives an impact; FIG. 11 is a partial perspective view showing a separated state of the drum cartridges according to the second embodiment, partly omitted. FIG. 11 is a partial perspective view showing a state in which the separated state of the drum cartridges according to the second embodiment is released, with a portion omitted; The perspective view seen from the arrow C direction of FIG. The perspective view seen from the arrow D direction of FIG. FIG. 12 is a partial perspective view showing a separated state of the drum cartridges according to the third embodiment, partly omitted. FIG. 11 is a partial perspective view showing a state in which the separated state of the drum cartridges according to the third embodiment is released, with a portion omitted; The perspective view seen from the arrow E direction of FIG. The perspective view seen from the arrow F direction of FIG.

<First embodiment>
A first embodiment of the present invention will be described with reference to FIGS. 1 to 12. FIG. First, the schematic configuration of the image forming apparatus of this embodiment will be described with reference to FIG.

[Image forming apparatus]
The image forming apparatus 1 is a tandem image forming apparatus that employs an intermediate transfer method and is capable of forming a full-color image using an electrophotographic method. That is, the image forming apparatus 1 includes image forming units 10 for Y (yellow), M (magenta), C (cyan), and K (black). This is a so-called tandem type configuration in which they are arranged side by side in the direction of rotation. The configuration and operation of each image forming section 10 are substantially the same except that the colors of toners used are different.

The image forming unit 10 has a photosensitive drum 11 that is a cylindrical electrophotographic photosensitive member (photosensitive member). The photosensitive drum 11 is rotationally driven at a process speed (peripheral speed) of 100 mm/sec by transmission of a driving force from a driving means (not shown) provided in the apparatus main body 1a. In the image forming section 10, around the photosensitive drum 11, a charging roller 12, a developing device 14, a primary transfer roller 17, and a drum cleaning device 15 are arranged in order along the rotation direction. An exposure device 16 is arranged below each image forming section 10 . The image forming apparatus 1 also has an intermediate transfer belt 61 formed of an endless belt body as an intermediate transfer member so as to be in contact with the photosensitive drums 11 of the image forming units 10 .

The charging roller 12 as charging means is a rotatable roller-shaped charging member, is arranged to contact the photosensitive drum 11 , and charges the surface of the photosensitive drum 11 . An exposure device (laser scanner device) 16 as exposure means exposes the charged surface of the photosensitive drum 11 to form an electrostatic latent image on the surface of the photosensitive drum 11 .

The developing device 14 as a developing means accommodates toner as a developer therein, and develops the electrostatic latent image formed on the photosensitive drum 11 into a toner image using the toner. Such a developing device 14 has a developing sleeve 14a as a developer carrying member that carries toner and conveys it to a portion facing the photosensitive drum 11 (developing position). The developing sleeve 14a is rotationally driven.

A primary transfer roller 17 as a primary transfer means is a roller-shaped primary transfer member, and primarily transfers the toner image formed on the photosensitive drum 11 to the intermediate transfer belt 61 . The drum cleaning device 15 cleans transfer residual toner remaining on the photosensitive drum 11 after the primary transfer.

The intermediate transfer belt 61 is formed endlessly from a dielectric resin such as polyimide. The intermediate transfer belt 61 is stretched around a plurality of support rollers (tension rollers) with a predetermined tension. The above-described primary transfer roller 17 is arranged at a position facing each photosensitive drum 11 on the inner circumferential surface side (back side) of the intermediate transfer belt 61 . The primary transfer roller 17 is pressed against the photosensitive drum 11 via the intermediate transfer belt 61 to form a primary transfer portion (primary transfer nip portion) N1 where the intermediate transfer belt 61 and the photosensitive drum 11 are in contact. The primary transfer roller 17 rotates following the rotation of the intermediate transfer belt 61 .

A secondary transfer roller 35, which is a roller-shaped secondary transfer member as a secondary transfer means, is arranged at a position facing the secondary transfer facing roller 62 on the outer peripheral surface side (surface side) of the intermediate transfer belt 61. ing. The secondary transfer roller 35 is pressed against the secondary transfer opposing roller 62 via the intermediate transfer belt 61, and the secondary transfer portion (secondary transfer nip portion) where the intermediate transfer belt 61 and the secondary transfer roller 35 are in contact with each other. ) N2. The toner image transferred to the intermediate transfer belt 61 is secondarily transferred to the recording material P at the secondary transfer portion N2.

A belt cleaning device 70 as an intermediate transfer body cleaning means is arranged at a position facing the tension roller 64 on the outer peripheral surface side of the intermediate transfer belt 61 . The belt cleaning device 70 cleans transfer residual toner remaining on the intermediate transfer belt 61 after the secondary transfer.

Next, the image forming operation will be described. During image formation, the surface of the rotationally driven photosensitive drum 11 is uniformly charged to a predetermined potential with a predetermined polarity by the charging roller 12 . In the present embodiment, only a DC voltage of −1300 V is applied to the charging roller 12 from a high voltage power supply (charging power supply) (not shown), and discharge is generated on the surface of the photosensitive drum 11 . is charged to about -700V.

After the surface of the photosensitive drum 11 is uniformly charged, the exposure device 16 scans and exposes the surface of the photosensitive drum 11 based on the signal of image information to form an electrostatic latent image (electrostatic image) on the photosensitive drum 11 . is formed. Note that the image forming apparatus 1 of the present embodiment includes an image reading apparatus 2, and the image information described above includes image information of a document read by the image reading apparatus 2 and a personal computer connected to the image forming apparatus 1. There is image information sent from an external terminal such as a computer.

The electrostatic latent image formed on the photosensitive drum 11 is developed into a toner image by the developing device 14 using toner as developer. In this embodiment, the normal charge polarity of the toner is negative. During development, a predetermined development voltage (development bias) is applied to the development sleeve 14a from a high-voltage power source (not shown) as a development power source. As the development voltage, an oscillating voltage in which a DC voltage (DC component) and an AC voltage (AC component) are superimposed is used. Further, toner is supplied to the developing device 14 from a toner bottle 19 as a toner storage container through a toner conveying path (not shown).

The toner image formed on the photosensitive drum 11 is transferred (primarily transferred) onto the surface of the intermediate transfer belt 61 by the action of the primary transfer roller 17 at the primary transfer portion N1. At this time, the primary transfer roller 17 is supplied with a primary transfer voltage (primary transfer voltage), which is a DC voltage having a polarity opposite to the charging polarity of the toner during development (positive polarity in this embodiment), from a primary transfer power supply (high voltage power supply) (not shown). transfer bias) is applied. When forming a full-color image, the above-described operation is performed in each image forming unit 10, and the yellow, magenta, cyan, and black toner images formed on the respective photosensitive drums 11 are sequentially superimposed on each other to form an intermediate image. It is transferred onto the transfer belt 61 . After the transfer, a small amount of untransferred toner remaining on the photosensitive drum 11 is removed by the drum cleaning device 15 and collected in the collecting section.

On the other hand, the recording material P is fed one by one from the feeding cassette 20 and conveyed to the registration roller pair 23 . The recording material P is, for example, a sheet such as paper or a plastic sheet. After that, the registration roller pair 23 conveys the recording material P between the intermediate transfer belt 61 and the secondary transfer roller 35 in synchronization with the toner image on the intermediate transfer belt 61 .

The color toner image on the intermediate transfer belt 61 is transferred (secondary transfer) onto the surface of the recording material P by the action of the secondary transfer roller 35 at the secondary transfer portion N2. When the recording material P passes through the secondary transfer portion N2, the secondary transfer roller 35 is supplied with a DC voltage having a polarity opposite to the charging polarity of the toner during development from a secondary transfer power supply (high voltage power supply) (not shown). A secondary transfer voltage (secondary transfer bias) is applied. After the transfer, a small amount of residual toner remaining on the intermediate transfer belt 61 is removed and collected by the belt cleaning device 70 to prepare for the next image formation.

The toner image transferred onto the recording material P is fixed by being heated and pressed at the nip portion between the heating roller 41 and the pressure roller 42 of the fixing device 40 , and is discharged onto the discharge tray 51 by the discharge roller pair 50 . be done.

[Drum cartridge]
Next, a schematic configuration of the drum cartridge 100 as a photosensitive unit will be described with reference to FIGS. 2 to 4. FIG. In the case of this embodiment, the drum cartridge 100 having the photosensitive drum 11 is detachable from the apparatus main body 1a (FIG. 1) so that it can be replaced for maintenance or the like. For example, the drum cartridge 100 can be detachably attached to the apparatus main body 1a by moving the apparatus main body 1a along the longitudinal direction (the rotation axis direction of the photosensitive drum 11).

As shown in FIG. 2, the drum cartridge 100 includes a photosensitive drum 11 as a photosensitive member, a charging roller 12, a cleaning roller 13 as a cleaning member, a drum cleaning device 15, a spacing member 200, and the like. These are integrally held by a drum container 30 as a frame.

The photosensitive drum 11 is held in the drum container 30 so as to be rotatable about its rotation axis via a bearing (not shown). That is, as shown in FIG. 3, the drum container 30 has side walls 30a arranged on both sides of the photosensitive drum 11, the charging roller 12, and the cleaning roller 13 in the rotation axis direction, and connecting portions 30b connecting the side walls 30a on both sides. . Both ends of the photosensitive drum 11 in the direction of the rotation axis are rotatably supported by the side walls 30a on both sides in the direction of the rotation axis via bearings.

Further, the photosensitive drum 11 is provided with a coupling 39 (FIG. 4) for receiving driving force from a motor (not shown) as a driving source provided in the apparatus main body 1a in a state of being attached to the apparatus main body 1a, and rotating the photosensitive drum 11. It is When the drum cartridge 100 is attached to the apparatus main body 1a, the coupling 39 is coupled with a coupling provided on the apparatus main body 1a side, and a driving force is transmitted from a motor provided on the apparatus main body 1a.

Further, the drum container 30 is provided with a drum cleaning device 15 , and the drum cleaning device 15 has a cleaning blade 15 a , a collecting portion 15 b and a toner conveying screw 38 . The cleaning blade 15a is fixed to the drum container 30, contacts the surface of the photosensitive drum 11 in a direction counter to the rotational direction β of the photosensitive drum 11 during image formation, and cleans the surface of the photosensitive drum 11. FIG.

The collection unit 15b is provided near the cleaning blade 15a, and collects transfer residual toner removed from the surface of the photosensitive drum 11 by the cleaning blade 15a. A toner conveying screw 38 serving as a conveying portion conveys the toner collected by the collecting portion 15 b to the outside of the drum cartridge 100 . The toner conveyed outside the drum cartridge 100 by the toner conveying screw 38 is collected in a waste toner container (not shown) provided in the apparatus main body 1a.

A gear 36 (FIG. 3, FIG. 3, FIG. 3) is fixed to a longitudinal end (rotational axis direction end) of the photosensitive drum 11 so as to rotate integrally with the photosensitive drum 11 around the rotational axis of the photosensitive drum 11. 4) is provided. That is, the gear 36 is provided on the rotating shaft of the photosensitive drum 11 so as to rotate together with the photosensitive drum 11 . The gear 36 rotates integrally with the photosensitive drum 11 when a driving force is input to the photosensitive drum 11 via the coupling 39 . The rotational force of gear 36 is transmitted to toner conveying screw 38 . As a result, the toner conveying screw 38 rotates, and the transfer residual toner collected in the collecting section 15 b can be conveyed out of the drum cartridge 100 .

The charging roller 12 as a charging member is a roller-shaped member having a rotating shaft 12a which is a conductive support (core metal, core material), and one or more elastic layers 12b formed around the rotating shaft 12a. is. The charging roller 12 is brought into contact with the surface of the photosensitive drum 11 with a predetermined pressing force by a pressure spring 32 (FIG. 4) as an urging means, and rotates following the rotation of the photosensitive drum 11. .

More specific description will be given. The charging roller 12 is rotatably supported by a charging roller bearing 31 as a bearing member that holds a rotary shaft 12a. Also, the charging roller bearing 31 is slidably supported with respect to the drum container 30 . Specifically, the charge roller bearing 31 is slidably guided in the direction toward the rotation axis of the photosensitive drum 11 by a slide guide portion 30c provided in the drum container 30. As shown in FIG. In the illustrated example, the charging roller bearing 31 is formed with a groove 31c along its sliding direction. It is guided in the direction towards the axis of rotation.

The charging roller 12 supported by the charging roller bearing 31 is movable along the direction toward the rotation axis of the photosensitive drum 11 on a plane perpendicular to the rotation axis of the photosensitive drum 11 . Accordingly, the charging roller 12 is provided movably between a contact position where it contacts the surface of the photosensitive drum 11 and a separated position where it is separated from the surface of the photosensitive drum 11 . The charging roller 12 charges the surface of the photosensitive drum 11 by applying a voltage at the contact position.

Further, a pressure spring 32 as a biasing means is provided between the drum container 30 and the charging roller bearing 31 . The pressure spring 32 biases the charging roller 12 in a direction (biasing direction) toward the rotation axis of the photosensitive drum 11 on a plane perpendicular to the rotation axis of the photosensitive drum 11 . That is, the pressure spring 32 urges the charging roller bearing 31 in the same direction as the charging roller bearing 31 slides. Therefore, the charging roller 12 is pressed against the photosensitive drum 11 and comes into contact therewith. That is, the pressure spring 32 urges the charging roller 12 in the direction from the separated position toward the contact position.

A cleaning roller 13 as a cleaning member contacts the charging roller 12 to clean the surface of the charging roller 12 . The cleaning roller 13 has a rotating shaft 13a which is a bar-shaped support portion (core metal, core material), and an elastic layer 13b formed around the rotating shaft 13a. It is a roller-shaped member. The cleaning roller 13 is brought into contact with the surface of the charging roller 12 with a predetermined pressing force by a pressure spring 34 (FIGS. 3 and 4) as a cleaning member biasing means, and is driven as the charging roller 12 rotates. to rotate.

More specific description will be given. The cleaning roller 13 is rotatably supported by a cleaning roller bearing 33 that supports a rotary shaft 13a. Also, the cleaning roller bearing 33 is slidably supported with respect to the charging roller bearing 31 . Specifically, the cleaning roller bearing 33 faces the rotation axis of the charging roller 12 so that the cleaning roller 13 can move along the direction toward the rotation axis of the charging roller 12 in a plane perpendicular to the rotation axis of the charging roller 12 . It is configured to be slidable in any direction. In this embodiment, the rotation axis of the charging roller 12 and the rotation axis of the spacing member 200, which will be described later, are common.

Thus, the cleaning roller 13 is provided movably between a roller contact position where it contacts the surface of the charging roller 12 and a roller separation position where it is separated from the surface of the charging roller 12 . The cleaning roller 13 cleans the charging roller 12 at the roller contact position.

Further, a pressure spring 34 is provided between the charging roller bearing 31 and the cleaning roller bearing 33 as a cleaning member biasing means. The pressure spring 34 biases the cleaning roller 13 in a direction (biasing direction) toward the rotation axis direction of the charging roller 12 on a plane perpendicular to the rotation axis of the charging roller 12 . Therefore, the cleaning roller 13 is pressed against the charging roller 12 and comes into contact therewith. That is, the pressure spring 34 urges the cleaning roller 13 in the direction from the roller separation position to the roller contact position. In other words, the cleaning roller 13 is supported by the cleaning roller bearing 33 so as to be movable along the biasing direction of the pressure spring 34 . Further, in this embodiment, the biasing direction of the pressure spring 32 and the biasing direction of the pressure spring 34 are substantially the same.

Also, the cleaning roller 13 is supported by the charging roller bearing 31 via a cleaning roller bearing 33 and a pressure spring 34 . Therefore, as described below, when the charging roller 12 is moved away from the photosensitive drum 11 by the spacing member 200, the cleaning roller 13 moves in the moving direction of the charging roller 12 in conjunction with this movement.

With the above configuration, when the photosensitive drum 11 receives a driving force from a driving source such as a motor provided in the apparatus main body 1 a and rotates, the charging roller 12 is driven to rotate by frictional force with the photosensitive drum 11 . Further, when the charging roller 12 rotates, the cleaning roller 13 is driven to rotate by frictional force with the charging roller 12 . Further, the toner conveying screw 38 receives a driving force (rotational force) from the gear 36 and rotates.

[Spacing member]
Next, the spacing member 200 will be described with reference to FIGS. 5 to 7. FIG. The drum cartridge 100 is provided with a separating member 200 for securing clearance by separating the charging roller 12 and the photosensitive drum 11 and between the charging roller 12 and the cleaning roller 13 during transportation for distribution. ing.

The spacing member 200 is provided swingably on the rotating shaft of the charging roller 12 . In this embodiment, the spacing members 200 are provided at both ends of the rotating shaft 12a of the charging roller 12 so as to be swingable about the rotating shaft 12a. In other words, the spacing member 200 is supported by the charging roller 12 so as to be swingable around the rotation axis of the charging roller 12 . Therefore, the spacing member 200 can move in conjunction with the movement of the charging roller 12 . Since the configuration of the spacing member 200 is the same at both ends of the charging roller 12, only one side of the charging roller 12 will be described below.

The spacing member 200 has two spacing holding portions 210 and 220 and a swing support portion 230, as shown in FIGS. The swing support portion 230 is fitted to the rotating shaft 12a of the charging roller 12 so as to swing freely as described above. Thereby, the spacing member 200 is supported so as to be swingable with respect to the rotating shaft 12a. The separation holding unit 210 is arranged between the gear 36 provided on the photosensitive drum 11 and the rotating shaft 12a of the charging roller 12 to separate the photosensitive drum 11 and the charging roller 12 and to secure a clearance. The separation holding portion 220 is arranged between the rotating shaft 12a of the charging roller 12 and the rotating shaft 13a of the cleaning roller 13 to separate the charging roller 12 and the cleaning roller 13 and to secure a clearance.

Also, the two separation holding portions 210 and 220 and the swing support portion 230 are integrally formed. Therefore, when the spacing member 200 is positioned at the first phase (separation holding position) with respect to the swinging direction, the separation holding portions 210 and 220 hold the photosensitive drum 11 and the charging roller 12 together, and the charging roller 12 and the cleaning roller 12 are separated from each other. The rollers 13 are held apart from each other. This state is called a separated state (or separated state). On the other hand, when the spacing member 200 swings from the first phase to the second phase (separation release position) in the swing direction, as will be described later, the separation state between the photosensitive drum 11 and the charging roller 12 and the charging roller 12 and the separated state of the cleaning roller 13 are released at the same time. This state is defined as a separation release state.

When the photosensitive drum 11 and the charging roller 12 are separated from each other, the separation holding unit 210 is configured to rotate the rotating shaft 12a (the rotating shaft of the separating member 200) of the charging roller 12 and the gear 36 by the pressing force (biasing force) of the pressure spring 32. is sandwiched between Further, when the charging roller 12 and the cleaning roller 13 are separated from each other, the separation holding portion 220 maintains the space between the rotation shaft 13a of the cleaning roller 13 and the rotation shaft 12a of the charging roller 12 by the pressing force (biasing force) of the pressure spring 34. is sandwiched between

Further, as shown in FIG. 7A, the spacing holding portion 210 of the spacing member 200 has a first engaging portion 211 that can be engaged with the gear 36 . The first engaging portion 211 is formed with gear teeth 211a as an engaging protrusion on the side surface of the separation holding portion 210 facing the gear 36 in the separated state. In addition, an engaging concave portion 36a that can be engaged with the gear teeth 211a is formed on the outer peripheral surface of the gear 36 over the entire circumference. That is, the engagement recesses 36a between the gear teeth of the gear 36 are provided. The gear teeth 211a are formed at the same pitch as the pitch of the engaging recesses 36a of the gear 36 (the pitch of the gear teeth of the gear 36). In the separated state in which the photosensitive drum 11 and the charging roller 12 are separated, the gear teeth 211a of the first engaging portion 211 are engaged with the engaging concave portions 36a of the gear 36 . The spacing member 200 moves the charging roller 12 against the urging force of the pressure spring 32 in a state where the first engaging portion 211 is engaged with the gear 36 as a rotating member, thereby separating the photosensitive drum 11 and the charging roller 12 . and are held at a separated position.

Further, the separation holding portion 220 of the separation member 200 has an engaging portion 221 as a cleaning member engaging portion capable of engaging with the rotation shaft 13a of the cleaning roller 13 as a part of the cleaning member. The engaging portion 221 is provided on the side surface of the separation holding portion 220 facing the rotary shaft 13a in the separated state, and is a concave portion having a radius of curvature substantially the same as the outer diameter of the outer peripheral surface of the cylindrical rotary shaft 13a. be. When the charging roller 12 and the cleaning roller 13 are separated from each other, the engaging portion 221 is engaged with the rotating shaft 13a. In other words, at this time, the spacing member 200 pushes the cleaning roller 13 against the urging force of the pressure spring 34 while the engaging portion 221 is engaged with the rotating shaft 13a as a part of the cleaning member. , the charging roller 12 and the cleaning roller 13 are held at a separated position.

The engagement portion 221 of the space holding portion 220 is formed to engage with the rotation shaft 13 a of the cleaning roller 13 while the first engagement portion 211 of the space holding portion 210 is engaged with the gear 36 . there is Therefore, when the spacing member 200 is positioned at the first phase in the swinging direction, the first engaging portion 211 engages with the gear 36 and the engaging portion 221 engages with the rotating shaft 13a. Then, the charging roller 12 and the cleaning roller 13 are kept separated from each other. As a result, when the drum cartridge 100 is transported, for example, the elastic layer 12b of the charging roller 12 and the photosensitive drum 11 are separated from each other, and the charging roller 12 and the cleaning roller 13 are separated from each other to secure a mutual clearance.

[Separation hold automatic release]
Next, with reference to FIGS. 7A and 7B, description will be made regarding the automatic release of automatically releasing the separated state between the photosensitive drum 11 and the charging roller 12, and between the charging roller 12 and the cleaning roller 13, by the separating member 200. FIG. . When the image forming apparatus 1 (FIG. 1) is started by installing a new drum cartridge 100 in the apparatus main body 1a (FIG. 1), the initial operation performed by the image forming apparatus 1 causes the photosensitive drum 11 to be prepared for the apparatus main body 1a. A driving force (rotational force) is input from the motor provided.

When the drum cartridge 100 is attached to the apparatus main body 1a, as shown in FIG. 7A, the photosensitive drum 11 and the charging roller 12 and the charging roller 12 and the cleaning roller 13 are separated from each other. It is in a separated state. Then, when the rotation of the photosensitive drum 11 is started from this separated state, the gear 36 rotates in the direction of the arrow β as the photosensitive drum 11 rotates, as shown in FIG. Then, the first engaging portion 211 engaged with the gear 36 receives the rotational force of the gear 36, and the spacing member 200 swings in the predetermined direction α (arrow direction in FIG. 7B). That is, when the drive force is input and the gear 36 rotates, the spacing member 200 moves (rocks in this embodiment) in the predetermined direction α from the separation holding position toward the separation release position.

By swinging the spacing member 200 in this manner, the engagement between the first engaging portion 211 and the gear 36 is disengaged, and the spacing holding portion 210 moves toward the rotation shaft 12a of the charging roller 12 (swing shaft of the spacing member 200). and the gear 36. As a result, the state in which the charging roller 12 is held at the separated position is automatically released.

In addition, when the spacing member 200 swings, the engaging portion 221 is disengaged from the rotating shaft 13 a of the cleaning roller 13 , and the spacing holding portion 220 moves between the rotating shaft 12 a of the charging roller 12 and the rotating shaft of the cleaning roller 13 . It is released from the state sandwiched between 13a. As a result, the state in which the cleaning roller 13 is held at the roller separation position is automatically released. That is, in this embodiment, when the gear 36 is rotated by the initial operation of the image forming apparatus 1 after the drum cartridge 100 is attached to the apparatus main body 1a, the separating member 200 swings to separate the charging roller 12 and the cleaning roller 13 from each other. The state is automatically released at the same time.

[Structure for keeping distance]
Next, the configuration for maintaining the separation will be described with reference to FIGS. 8 to 12. FIG. For example, even if the drum cartridge 100 is subjected to strong vibration during transportation, the first engaging portion 211 of the spacing member 200 and the gear 36 are prevented from being unintentionally disengaged. In this embodiment, the second engaging portion 212 of the spacing member 200 and the engaged portion 31a of the charging roller bearing 31 allow the spacing member 200 to remain at the separation release position even when strong vibration is applied to the drum cartridge 100 . It regulates going to Inadvertent disengagement between the first engaging portion 211 and the gear 36 is suppressed.

That is, the second engaging portion 212 and the engaged portion 31a are disengaged from the gear 36 and the first engaging portion 211 for some reason because the driving force is not input to the gear 36 at the separated holding position. , the spacing members 200 are engaged with each other when they try to swing in the predetermined direction α. This restricts the spacing member 200 from swinging toward the spacing release position, and prevents the first engaging portion 211 from accidentally disengaging from the gear 36 . On the other hand, when the driving force is input to the gear 36 and the spacing member 200 tries to swing in the predetermined direction .alpha. The engagement with the engaging portion 31a is released. Then, the spacing member 200 is allowed to move toward the spacing release position. As a result, the separated states between the photosensitive drum 11 and the charging roller 12 and between the charging roller 12 and the cleaning roller 13 are automatically released as described above. A specific description will be given below.

8 and 9 are cross-sectional perspective views of the spacing member 200 and its surroundings, with FIG. 8 showing the separated state and FIG. 9 showing the separated state. Since the spacing member 200 is rotatably fitted to the rotating shaft 12a of the charging roller 12, it can swing around the rotation center axis of the rotating shaft 12a.

The spacing member 200 has a second engaging portion 212 provided at a position different from that of the first engaging portion 211 . The second engaging portion 212 is provided on the opposite side of the space holding portion 210 to the first engaging portion 211 , that is, on the charging roller 12 side. In the present embodiment, the second engaging portion 212 is a projection (spacing member-side projection) projecting from the spacing member 200 in the radial direction of the charging roller 12 .

On the other hand, the charging roller bearing 31 that supports the rotating shaft 12 a of the charging roller 12 is formed integrally with the charging roller bearing 31 with an engaged portion 31 a. In the present embodiment, the engaged portion 31 a is a projection (bearing member side projection) projecting from the charging roller bearing 31 in the radial direction of the charging roller 12 . The engaged portion 31a is located downstream of the second engaging portion 212 in the predetermined direction when the spacing member 200 is in the separation holding position. Thereby, the engaged portion 31a can be engaged with the second engaging portion 212 when the spacing member 200 attempts to move in a predetermined direction.

Such an engaged portion 31 a is formed so as to protrude radially from a portion of the outer peripheral portion of the arc-shaped portion 31 b formed in the charging roller bearing 31 . The center of the circular arc portion 31b is coaxial with the rotating shaft 12a, and the outer diameter of the circular arc portion 31b is the same as or slightly larger than the rotating shaft 12a.

In addition, the second engaging portion 212 of the spacing member 200 and the engaged portion 31a of the charging roller bearing 31 are formed at the same position in the axial direction of the rotating shaft 12a. Therefore, when the spacing member 200 rotates around the rotation shaft 12a, the second engaging portion 212 and the engaged portion 31a interfere with each other in a certain phase, restricting the rotation of the spacing member 200. be done.

For details of the positional relationship between the second engaging portion 212 and the engaged portion 31a, the A portion (inside the dotted line circle) of FIG. 8 is shown in FIG. , respectively. The separation holding portion 210 of the separation member 200 is in the separation holding position in FIG. 10, and in the separation release position (the state where the surface of the charging roller 12 and the surface of the photosensitive drum 11 are in contact) in FIG. there is

As shown in FIG. 10, when the photosensitive drum 11 rotates in the direction of the arrow β due to the driving force input to the photosensitive drum 11 from the separated state, the gear 36 and the first engaging portion 211 also rotate together. The spacing member 200 swings in the direction of the arrow α due to the meshing with the . At this time, the engaged portion 31a of the charging roller bearing 31 is arranged on the outer peripheral surface of the arc-shaped portion 31b on the downstream side where the second engaging portion 212 integrally formed with the spacing member 200 swings. Therefore, the second engaging portion 212 interferes with the engaged portion 31a to restrict the swinging movement of the spacing member 200. As shown in FIG.

Here, the amount of interference between the second engaging portion 212 and the engaged portion 31a is about 0.1 to 0.5 mm. On the other hand, the amount of meshing between the gear 36 and the first engaging portion 211 is set larger than the amount of interference between the second engaging portion 212 and the engaged portion 31a. For example, it is about 1.5 to 3 mm. Also, the rotational drive torque input to the photosensitive drum 11 is set to be sufficiently large. Therefore, when the photosensitive drum 11 is rotationally driven, the second engaging portion 212 overcomes the interference with the engaged portion 31a, and the spacing member 200 swings to the separation release position shown in FIG. It will be in the separated state.

In the present embodiment, in order for the second engaging portion 212 to climb over the engaged portion 31a, the second engaging portion 212 side is formed in a shape that bends so as to allow elastic deformation. Specifically, a hole 213 is formed in the separation holding portion 210 in which the second engaging portion 212 is formed, so that the separation holding portion 210 is easily elastically deformed. The bending shape may be provided on the side of the charging roller bearing 31 on which the engaged portion 31a is provided, or may be provided on both sides. That is, when at least one of the spacing member 200 and the charging roller bearing 31 is driven by the gear 36 and the spacing member 200 tries to move in a predetermined direction, the second engaging portion 212 is engaged. It is formed to be elastically deformable so that it can ride over the portion 31a.

Further, the configuration that enables the second engaging portion 212 to climb over the engaged portion 31a is not limited to the elastic deformation described above. For example, when at least one of the second engaging portion 212 and the engaged portion 31a is driven by the gear 36 and the spacing member 200 attempts to move in a predetermined direction, the second engaging portion 212 may move relative to each other so that it can get over the engaged portion 31a. For example, the second engaging portion 212 is provided so as to protrude and retract in the radial direction with respect to the space holding portion 210 . Alternatively, the engaged portion 31a is provided so as to protrude and retract in the radial direction with respect to the charging roller bearing 31 .

FIG. 12 shows a state in which a gap S is formed between the spacing member 200 and the gear 36, especially when a strong impact is received in the separated state. Consumable parts to be replaced, such as drum cartridges, may be subjected to unexpected strong impacts, such as being dropped during transportation. Even if the drum cartridge is packed in individual shipping boxes such as corrugated paper or styrofoam, it may be subjected to an impact of about 50 to 100G when dropped from a height of about 1m. At this time, an inertial force acts on the photosensitive drum 11, the charging roller 12, and the like, so that the frame of the drum cartridge itself may momentarily undergo elastic deformation.

Normally, the pressure spring 32 that urges the charging roller bearing 31 toward the photosensitive drum 11 presses the rotating shaft 12a together with the spacing member 200 against the photosensitive drum 11 side, whereby the first engagement of the spacing holding portion 210 is performed. The joint portion 211 is biased by the gear 36 . Therefore, the engagement between the first engaging portion 211 and the gear 36 is not easily released. However, when a strong impact is applied as described above, the first engaging portion 211 and the gear 36 are separated from each other as shown in FIG. 12, creating a gap S, albeit momentarily.

Here, a case where the above-described second engaging portion 212 and engaged portion 31a are not provided will be described. Since the spacing member 200 is rotatably fitted and supported by the rotation shaft 12a, if the first engaging portion 211 and the gear 36 are separated from each other, the spacing member 200 can be disengaged by applying even a small amount of force in the rotating direction. 200 easily rotates in the direction of the arrow in FIG. 12 due to its own weight, for example. In this case, even if the spacing member 200 and the charging roller 12 return to the direction of the photosensitive drum 11 at the next moment, the spacing member 200 has already rotated, resulting in the separation released state.

On the other hand, in this embodiment, the second engaging portion 212 is arranged on the spacing member 200, and the engaged portion 31a is arranged on the charging roller bearing 31, respectively, as described above. Therefore, by engaging the second engaging portion 212 and the engaged portion 31a, the rotation of the spacing member 200 by the inertial force due to its own weight is restricted, and the first engaging portion 211 and the gear 36 are instantaneously engaged. The posture of the spacing member 200 can be maintained even if the two do not engage with each other. Therefore, when the charging roller 12 and the spacing member 200 return to the positions where they are urged by the photosensitive drum 11, the first engaging portion 211 and the gear 36 are engaged again, and the separated state is maintained.

As described above, according to the present embodiment, even if the charging roller 12 and the spacing member 200 are moved away from the photosensitive drum 11 due to vibration or impact applied to the drum cartridge 100, the spacing member 200 is inadvertently separated. Rotation to the release position can be suppressed. As a result, it is possible to reduce the unintentional release of the separated state between the photosensitive drum 11 and the charging roller 12 .

<Second embodiment>
A second embodiment will be described with reference to FIGS. 13 to 16. FIG. In the above-described first embodiment, the configuration having the cleaning roller 13 has been described, but the present embodiment has a configuration without the cleaning roller 13 . Further, in the case of this embodiment, the spacing member 300 is provided swingably with respect to the charging roller bearing 400 as a bearing member. Other configurations and actions are the same as those of the first embodiment described above, so the same reference numerals are given to the same configurations, the description is omitted or simplified, and the portions different from the first embodiment are described below. Mainly explained.

Unlike the drum cartridge 100 of the first embodiment, the drum cartridge as the photoreceptor unit in the present embodiment does not have the cleaning roller 13 which is the cleaning member for the charging roller 12 . Further, the drum cartridge of the present embodiment does not have the cleaning roller bearing 33 and the pressure spring 34 either.

Further, the charging roller 12 is rotatably supported by a charging roller bearing 400 as a bearing member that holds the rotation shaft 12a. Also, the charging roller bearing 400 is slidably supported with respect to a drum container (not shown) as in the first embodiment. Further, similarly to the first embodiment, a pressure spring 32 is provided between the drum container and the charging roller bearing 400 as a biasing means. The pressure spring 32 biases the charging roller 12 in a direction (biasing direction) toward the rotation axis of the photosensitive drum 11 on a plane perpendicular to the rotation axis of the photosensitive drum 11 .

[Spacing member]
Next, the spacing member 300 will be described with reference to FIGS. 13 and 14. FIG. 13 shows the separated state, and FIG. 14 shows the separated state. The drum cartridge is provided with a spacing member 300 for securing clearance by spacing the charging roller 12 and the photosensitive drum 11 during transportation for distribution.

The spacing member 300 is provided swingably on a charging roller bearing 400 that supports the charging roller 12 . In this embodiment, the spacing member 300 is swingably provided on a cylindrical shaft 410 provided in the charging roller bearing 400 substantially parallel to the rotating shaft 12 a of the charging roller 12 . The cylindrical shaft 410 may be coaxial with the rotating shaft 12a, or may be offset from the central axis of the rotating shaft 12a. In this embodiment, the central axis of the cylindrical shaft 410 is shifted from the central axis of the rotating shaft 12a. Also in the case of this embodiment, the spacing member 300 is movable in conjunction with the movement of the charging roller 12 . Since the configuration of the spacing member 300 is the same at both ends of the charging roller 12, only one side of the charging roller 12 will be described below.

The spacing member 300 has a spacing holding portion 310 and a swing support portion 320 . The rocking support portion 320 is fitted to the cylindrical shaft 410 of the charging roller bearing 400 so as to be rockable as described above. The separation holding unit 310 is arranged between the gear 36 provided on the photosensitive drum 11 and the rotating shaft 12a of the charging roller 12 to separate the photosensitive drum 11 and the charging roller 12 and to secure a clearance.

Also, the separation holding portion 310 and the swing support portion 320 are integrally formed. Therefore, when the separation member 300 is positioned at the first phase (separation holding position) in the swing direction, the separation holding portion 310 holds the photosensitive drum 11 and the charging roller 12 in a separated state. This state is called a separated state (or separated state). On the other hand, when the separation member 300 swings from the first phase to the second phase (separation release position) in the swing direction, the separation state between the photosensitive drum 11 and the charging roller 12 is released. This state is defined as a separation release state.

The separation holding portion 310 is sandwiched between the charging roller bearing 400 and the gear 36 by the pressure (biasing force) of the pressure spring 32 when the photosensitive drum 11 and the charging roller 12 are separated. Thereby, for example, when the drum cartridge is transported, the elastic layer 12b of the charging roller 12 and the photosensitive drum 11 are separated from each other to secure a mutual clearance.

7(a) described in the first embodiment, the surface of the space holding portion 310 facing the gear 36 in the space holding state has a gear tooth surface pitch same as the gear tooth surface pitch of the gear 36. A first engaging portion 311 having teeth is provided.

[Separation hold automatic release]
Next, the automatic release of the separation holding state will be described with reference to FIG. 14 . When the image forming apparatus 1 (see FIG. 1) is started with a new drum cartridge installed in the apparatus main body 1a, the initial operation performed by the image forming apparatus 1 causes the motor provided in the apparatus main body 1a to move to the photosensitive drum 11. driving force is input from

When the drum cartridge is attached to the apparatus main body 1a, the photosensitive drum 11 and the charging roller 12 are separated from each other as shown in FIG. When the rotation of the photosensitive drum 11 is started from this separated state, the gear 36 rotates in the direction of the arrow β as the photosensitive drum 11 rotates, as shown in FIG. Then, the first engaging portion 311 of the spacing member 300 engaged with the gear 36 receives the rotational force of the gear 36, and the spacing member 300 swings in the predetermined direction α. That is, when the gear 36 is rotated by the driving force input, the spacing member 300 moves (rocks in this embodiment) in the predetermined direction α from the separation holding position to the separation release position.

By swinging the spacing member 300 in this manner, the engagement between the first engaging portion 311 and the gear 36 is released, and the spacing holding portion 310 is sandwiched between the cylindrical shaft 410 of the charging roller bearing 400 and the gear 36 . to be released from the state of As a result, the state in which the charging roller 12 is held at the separated position is automatically released.

[Structure for keeping distance]
Next, the configuration for maintaining the separation will be described with reference to FIGS. 15 and 16. FIG. 15 is a perspective view seen from the direction of arrow C in FIG. 13, showing the separated state. FIG. 16 is a perspective view seen from the direction of arrow D in FIG. 14, showing the separation released state. Since the spacing member 300 is rotatably fitted to the cylindrical shaft 410 of the charging roller bearing 400, the spacing member 300 can swing around the cylindrical shaft 410 as the central axis.

As shown in FIG. 15, the spacing member 300 is provided with a second engaging portion 330 at a position different from that of the first engaging portion 311 . The second engaging portion 330 is formed in a shape protruding in the axial direction of the cylindrical shaft 410 on the surface facing the charging roller bearing 400 . That is, the second engaging portion 330 is a spacing member-side protrusion that projects from the spacing member 300 in the direction along the rotation axis direction of the charging roller 12 .

On the other hand, the charging roller bearing 400 is provided with an engaged portion 420 that is integrally formed. The engaged portion 420 is formed in a convex shape at a position facing the spacing member 300 so as to protrude in the same direction as the cylindrical shaft 410 of the charging roller bearing 400 protrudes. That is, the engaged portion 420 protrudes from the charging roller bearing 400 in a direction along the rotation axis direction of the charging roller 12, and engages with the second engaging portion 330 when the spacing member 300 attempts to move in the predetermined direction α. It is a protrusion on the bearing member side that can be combined.

The second engaging portion 330 has a distance from the center of the cylindrical shaft 410 so that it interferes with the engaged portion 420 at a certain rotational phase when the spacing member 300 rotates about the cylindrical shaft 410 . It is arranged so as to be the same as the engaged portion 420 . As a result, as in the first embodiment, the engagement between the second engaging portion 330 and the engaged portion 420 restricts the rotational movement of the spacing member 300 .

The amount of interference between the second engaging portion 330 and the engaged portion 420 is about 0.1 to 0.5 mm, as in the first embodiment. The amount of interference between the second engaging portion 330 and the engaged portion 420 is set smaller than the amount of engagement between the gear 36 and the first engaging portion 311 (for example, about 1.5 to 3 mm). ing. Also, the rotational drive torque input to the photosensitive drum 11 is set to be sufficiently large. Therefore, when the photosensitive drum 11 is rotationally driven, the second engaging portion 330 overcomes the interference with the engaged portion 420, and the spacing member 300 swings to the separation release position shown in FIG. It will be in the separated state.

In the present embodiment, elastic deformation of at least one of the second engaging portion 330 side and the engaged portion 420 side is allowed in order for the second engaging portion 330 to ride over the engaged portion 420 in this way. It is shaped so that it bends. That is, when at least one of the spacing member 300 and the charging roller bearing 400 is driven by the gear 36 and the spacing member 300 tries to move in a predetermined direction, the second engaging portion 330 is engaged. It is formed to be elastically deformable so that it can ride over the portion 420 .

Also in the case of the present embodiment, as in the first embodiment, the second engaging portion 212 may climb over the engaged portion 31a by relative movement. That is, at least one of the second engaging portion 330 and the engaged portion 420 moves when the driving force is input to the gear 36 and the spacing member 300 attempts to move in a predetermined direction. may move relative to each other so that it can get over the engaged portion 420 . For example, in the case of this embodiment, the spacing member 300 provided with the second engaging portion 330 may retract in the axial direction of the cylindrical shaft 410 . That is, when the second engaging portion 330 engages with the engaged portion 420 , the spacing member 300 retreats in the direction away from the charging roller bearing 400 , so that the second engaging portion 330 moves toward the engaged portion 420 . can be overcome.

As a result, in this embodiment, as in the first embodiment, the rotation of the spacing member 300 is restricted to the extent of the inertial force due to its own weight, and the first engaging portion 311 and the gear 36 are instantaneously disengaged. However, the posture of the spacing member 300 can be maintained. Therefore, when the charging roller 12 and the spacing member 300 return to the positions where they are urged by the photosensitive drum 11, the first engaging portion 311 and the gear 36 are engaged again, and the separated state is maintained.

Further, in this embodiment, the spacing member 300 is not directly supported by the rotating shaft 12 a of the charging roller 12 , but is supported by a cylindrical shaft 410 integrally formed with the charging roller bearing 400 . Therefore, the spacing member 300 does not become a rotational load of the charging roller 12 in the state of use after the separation is released. As a result, even if the charging roller 12 is set to have a small frictional force with respect to the photosensitive drum 11 , the charging roller 12 does not become a rotational load.

As described above, according to the present embodiment, even if the charging roller 12 and the spacing member 300 move away from the photosensitive drum 11 due to vibration or impact applied to the drum cartridge, the spacing member 300 is inadvertently released from the separation. Rotation to the position can be suppressed. As a result, it is possible to reduce the unintentional release of the separated state between the photosensitive drum 11 and the charging roller 12 .

<Third Embodiment>
A third embodiment will be described with reference to FIGS. 17 to 20. FIG. This embodiment also does not have the cleaning roller 13, like the second embodiment. Further, in the case of the present embodiment, unlike the first and second embodiments, the engaging portion for rotation of the spacing member 500 is configured by driving input different from the rotation of the photosensitive drum 11 . Other configurations and actions are the same as those of the first embodiment described above, so the same reference numerals are given to the same configurations, the description is omitted or simplified, and the portions different from the first embodiment are described below. Mainly explained.

Unlike the drum cartridge 100 of the first embodiment, the drum cartridge as the photoreceptor unit in the present embodiment does not have the cleaning roller 13 which is the cleaning member for the charging roller 12 . Further, the drum cartridge of the present embodiment does not have the cleaning roller bearing 33 and the pressure spring 34 either.

Also, the charging roller 12 is rotatably supported by a charging roller bearing 600 as a bearing member that holds the rotating shaft 12a. Also, the charging roller bearing 600 is slidably supported with respect to a drum container (not shown) as in the first embodiment. Further, similarly to the first embodiment, a pressure spring 32 is provided between the drum container and the charging roller bearing 600 as a biasing means. The pressure spring 32 biases the charging roller 12 in a direction (biasing direction) toward the rotation axis of the photosensitive drum 11 on a plane perpendicular to the rotation axis of the photosensitive drum 11 .

Further, in the case of this embodiment, the surface of the photosensitive drum 11 is cleaned by a cleaning brush roller 700 as another rotating body. The cleaning brush roller 700 is arranged substantially parallel to the photosensitive drum 11 and is rotationally driven by a drive source (not shown). The cleaning brush roller 700 contacts the surface of the photosensitive drum 11 to clean the surface of the photosensitive drum 11 after primary transfer. The cleaning brush roller 700 is driven by a drive source separate from the photosensitive drum 11 .

A gear 710 as a rotating member is fixed to the longitudinal end (rotational axis direction end) of the cleaning brush roller 700 so as to rotate integrally with the cleaning brush roller 700 about the rotation axis of the cleaning brush roller 700 . is provided. That is, the gear 710 is provided on the rotating shaft of the cleaning brush roller 700 so as to rotate together with the cleaning brush roller 700 .

[Spacing member]
Next, the spacing member 500 will be described with reference to FIGS. 17 and 18. FIG. 17 shows the separated state, and FIG. 18 shows the separated state. The drum cartridge is provided with a spacing member 500 for securing clearance by spacing the charging roller 12 and the photosensitive drum 11 during transport for distribution.

The spacing member 500 is provided swingably on the rotating shaft of the charging roller 12 . In this embodiment, the spacing members 500 are provided at both ends of the rotating shaft 12a of the charging roller 12 so as to be swingable about the rotating shaft 12a. In other words, the spacing member 500 is supported by the charging roller 12 so as to be swingable around the rotation axis of the charging roller 12 . Therefore, the spacing member 500 can move in conjunction with the movement of the charging roller 12 . Since the configuration of the spacing member 500 is the same at both ends of the charging roller 12, only one side of the charging roller 12 will be described below.

The spacing member 500 has a spacing holding portion 510 and a swing support portion 520 . The swing support portion 520 is fitted to the rotating shaft 12a of the charging roller 12 so as to swing freely as described above. The separation holding portion 510 is arranged between the photosensitive drum 11 and the rotating shaft 12a of the charging roller 12 to separate the photosensitive drum 11 and the charging roller 12 and to secure a clearance.

Further, the separation holding portion 510 and the swing support portion 520 are integrally formed. Therefore, when the separation member 500 is positioned at the first phase (separation holding position) in the swing direction, the separation holding portion 510 holds the photosensitive drum 11 and the charging roller 12 in a separated state. This state is called a separated state (or separated state). On the other hand, when the spacing member 500 swings from the first phase to the second phase (separation release position) in the swing direction, the separation state between the photosensitive drum 11 and the charging roller 12 is released. This state is defined as a separation release state.

The separation holding portion 510 has a first engaging portion 511 and a drum-side engaging portion 512 provided at a position different from that of the first engaging portion 511 with respect to the swinging direction of the spacing member 500 . The first engaging portion 511 is formed on the surface of the space holding portion 510 facing the gear 710 in the space holding state, and has gear teeth having the same pitch as the gear tooth surface pitch of the gear 710 .

The drum-side engaging portion 512 is a recess having a diameter substantially equal to or slightly larger than the outer diameter of the photosensitive drum 11 , which is formed on the surface facing the photosensitive drum 11 in the spaced-apart state. Also, the shortest distance from the rotation center axis of the charging roller 12 to the drum side engaging portion 512 is larger than the radius of the elastic layer 12b.

In such a spaced holding portion 510 , the drum side engaging portion 512 contacts the outer peripheral surface of the photosensitive drum 11 via the charging roller bearing 600 that receives the pressure (biasing force) of the pressure spring 32 in the spaced holding state. are in contact. In this state, the separation holding portion 510 is sandwiched between the outer peripheral surface of the photosensitive drum 11 and the rotating shaft 12 a of the charging roller 12 . At this time, the drum-side engaging portion 512 where the separation holding portion 510 abuts against the photosensitive drum 11 is provided outside the image forming area with respect to the rotation axis direction of the photosensitive drum 11 . The image forming area is the maximum area in which an image can be formed on the surface of the photosensitive drum 11 .

In the present embodiment, the separation holding portion 510 is sandwiched between the photosensitive drum 11 and the rotating shaft 12a in this way, so that the elastic layer 12b of the charging roller 12 and the photosensitive drum 11 are separated when the drum cartridge is transported, for example. and ensure mutual clearance.

In this embodiment, the cleaning brush roller 700 is provided with a gear 710 as a rotating member with which the first engaging portion 511 provided on the spacing member 500 engages. However, such a rotating member may be provided on another member as long as it is a member that rotates around the photosensitive drum 11 . For example, a rotating member such as a gear may be provided simply to drive the spacing member 500 . Alternatively, if the drum cartridge has a developing device, a rotating member may be provided so as to rotate together with the developing sleeve of the developing device.

[Separation hold automatic release]
Next, the automatic release of the separated state will be described with reference to FIG. 18 . When the image forming apparatus 1 (see FIG. 1) is started by installing a new drum cartridge in the apparatus main body 1a, the initial operation performed by the image forming apparatus 1 causes the cleaning brush roller 700 provided in the apparatus main body 1a. A driving force is input from the motor.

When the drum cartridge is attached to the apparatus main body 1a, the photosensitive drum 11 and the charging roller 12 are separated from each other as shown in FIG. When the cleaning brush roller 700 starts rotating from this separated state, the gear 710 rotates in the direction of the arrow X as the cleaning brush roller 700 rotates, as shown in FIG. Then, the first engaging portion 511 of the spacing member 500 engaged with the gear 710 receives the rotational force of the gear 710, and the spacing member 500 swings in the predetermined direction Y. As shown in FIG. That is, when the drive force is input and the gear 710 rotates, the spacing member 500 moves (rocks in this embodiment) in the predetermined direction Y from the separation holding position to the separation release position.

By swinging the spacing member 500 in this manner, the engagement between the first engaging portion 511 and the gear 710 is released, and the spacing holding portion 510 is sandwiched between the photosensitive drum 11 and the rotating shaft 12 a of the charging roller 12 . to be released from the state of As a result, the state in which the charging roller 12 is held at the separated position is automatically released.

[Structure for keeping distance]
Next, the configuration for maintaining the separation will be described with reference to FIGS. 19 and 20. FIG. 19 is a perspective view seen from the direction of arrow E in FIG. 17, showing the separated state. FIG. 20 is a perspective view seen from the direction of arrow F in FIG. 18, showing the separation released state. Since the spacing member 500 is rotatably fitted to the rotating shaft 12a of the charging roller 12, it can swing about the rotating shaft 12a.

As shown in FIG. 19, the spacing member 500 is provided with a second engaging portion 530 at a position different from that of the first engaging portion 511 . The second engaging portion 530 is formed on the surface facing the charging roller bearing 400 so as to protrude in the axial direction of the rotary shaft 12a. That is, the second engaging portion 530 is a spacing-member-side projection projecting from the spacing member 500 in a direction along the rotation axis direction of the charging roller 12 .

On the other hand, the charging roller bearing 600 is provided with an engaged portion 610 integrally formed therewith. The engaged portion 610 is formed in a convex shape so as to protrude in the same direction as the axial direction of the rotary shaft 12a at a position facing the spacing member 500. As shown in FIG. That is, the engaged portion 610 protrudes from the charging roller bearing 400 in a direction along the rotation axis direction of the charging roller 12, and engages with the second engaging portion 530 when the spacing member 500 attempts to move in the predetermined direction Y. It is a protrusion on the bearing member side that can be combined.

The second engaging portion 530 has a distance from the center of the rotating shaft 12a so that it interferes with the engaged portion 610 at a certain rotational phase when the spacing member 500 rotates about the rotating shaft 12a. It is arranged so as to be the same as the engaged portion 610 . As a result, as in the first embodiment, the engagement between the second engaging portion 530 and the engaged portion 610 restricts the rotational movement of the spacing member 500 .

The amount of interference between the second engaging portion 530 and the engaged portion 610 is about 0.1 to 0.5 mm, as in the first embodiment. The amount of interference between the second engaging portion 530 and the engaged portion 610 is set smaller than the amount of engagement between the gear 710 and the first engaging portion 511 (for example, about 1.5 to 3 mm). ing. Also, the rotational drive torque input to the cleaning brush roller 700 is set to be sufficiently large. Therefore, when the cleaning brush roller 700 is rotationally driven, the second engaging portion 530 overcomes the interference with the engaged portion 610, and the spacing member 500 swings to the separation release position shown in FIG. , the separation released state.

In the present embodiment, elastic deformation of at least one of the second engaging portion 530 side and the engaged portion 610 side is allowed in order for the second engaging portion 530 to climb over the engaged portion 610. It is shaped so that it bends. That is, when at least one of the spacing member 500 and the charging roller bearing 600 is driven by the gear 710 and the spacing member 500 tries to move in a predetermined direction, the second engaging portion 530 is engaged. It is formed to be elastically deformable so that it can ride over the portion 610 .

Also in the case of the present embodiment, as in the first embodiment, the second engaging portion 530 may be allowed to climb over the engaged portion 610 by relative movement. That is, at least one of the second engaging portion 530 and the engaged portion 610 is moved when the driving force is input to the gear 710 and the spacing member 500 attempts to move in a predetermined direction. may move relative to each other so that it can get over the engaged portion 610 . For example, in the case of this embodiment, the spacing member 500 provided with the second engaging portion 530 may retract in the axial direction of the rotary shaft 12a. That is, when the second engaging portion 530 engages with the engaged portion 610 , the spacing member 500 retreats in the direction away from the charging roller bearing 600 , so that the second engaging portion 530 can be overcome.

As a result, in this embodiment, as in the first embodiment, the rotation of the spacing member 500 is limited to the extent of the inertial force due to its own weight, and the first engaging portion 511 and the gear 710 are instantaneously disengaged. However, the posture of the spacing member 500 can be maintained. Therefore, when the charging roller 12 and the spacing member 500 return to the positions where they are urged by the photosensitive drum 11, the first engaging portion 511 and the gear 710 are engaged again, and the separated state is maintained.

Further, in the present embodiment, the driving source for releasing the separation of the spacing member 500 is not the driving source for driving the photosensitive drum 11, but a separate driving source for rotating the cleaning brush roller 700, which is a rotating body separate from the photosensitive drum 11. is the driving source for Therefore, the present embodiment can also be applied to a configuration in which the photosensitive drum 11 can be easily replaced as a single unit. Also, since the photosensitive drum 11 itself does not have gears, it is less likely that unnecessary vibrations will be applied, and it is also suitable for drum cartridges that require high image quality (with reduced pitch streaks due to vibration) that emphasizes rotation accuracy. , the present embodiment can be applied.

As described above, according to the present embodiment, even if the charging roller 12 and the spacing member 500 are moved away from the photosensitive drum 11 due to vibration or impact applied to the drum cartridge, the spacing member 500 is released inadvertently. Rotation to the position can be suppressed. As a result, it is possible to reduce the unintentional release of the separated state between the photosensitive drum 11 and the charging roller 12 .

<Other embodiments>
In each of the above-described embodiments, the spacing member is provided swingably on the rotating shaft of the charging roller or on the charging roller bearing. It's okay to be.

Further, in each of the above-described embodiments, the engaged portion is arranged downstream of the second engaging portion in the predetermined direction, and when the driving force is input to the rotating member and the separating member swings in the predetermined direction, the 2 The engaging part is made to climb over the engaged part. However, the relationship between the engaged portion and the second engaging portion is not limited to this.

For example, the engaged portion is brought into contact with the second engaging portion with a predetermined pressure in the radial direction of the charging roller, and the separating member attempts to move in a predetermined direction in a state in which no driving force is input to the rotating member. In this case, the engaged portion is kept in contact with the second engaging portion with a predetermined pressure. This restricts the movement of the spacing member. On the other hand, when the driving force is input to the rotating member and the spacing member attempts to move in a predetermined direction, the second engaging portion contacts the engaged portion regardless of the contact pressure of the engaged portion. After moving from the contact position, the contact state between the second engaging portion and the engaged portion is released. This allows the spacing member to move. Therefore, "engagement" in the present invention is a concept including "abutment".

Alternatively, the engaged portion and the second engaging portion are connected. For example, the engaged portion and the second engaging portion are adhered with an adhesive. Alternatively, the engaged portion and the second engaging portion are integrally formed via a breakable connecting portion. In the former case, when the spacing member attempts to move in a predetermined direction while no driving force is being input to the rotating member, the engaged portion and the second engaging portion are maintained in a bonded state. This restricts the movement of the spacing member. On the other hand, when a driving force is input to the rotating member and the separating member attempts to move in a predetermined direction, the adhesion between the engaged portion and the second engaging portion is broken, and the second engaging portion is disengaged. The second engaging portion and the engaged portion are released from the adhered state. This allows the spacing member to move.

In the latter case, when the separating member attempts to move in a predetermined direction while no driving force is being input to the rotating member, the connection state of the connecting portion between the engaged portion and the second engaging portion is changed. maintained. This restricts the movement of the spacing member. On the other hand, when a driving force is input to the rotating member and the spacing member attempts to move in a predetermined direction, the connecting portion breaks, and the second engaging portion moves from the position of connection with the engaged portion. The connection state between the second engaging portion and the engaged portion is released. This allows the spacing member to move. Therefore, "engagement" in the present invention is a concept including "connection" such as "adhesion" and "integral formation".

Further, the first embodiment may be configured without the cleaning roller 13, and the second and third embodiments may be configured with the cleaning roller 13. FIG.

Further, the photoreceptor may be a photoreceptor belt instead of the photoreceptor drum. In addition to the drum cartridge described above, the photoreceptor unit includes a process cartridge in which a drum cartridge and a developing device are combined. Further, the image forming apparatus may be any one that forms an image using a photoreceptor such as a copier, printer, facsimile machine, or multifunction machine having a plurality of these functions.

DESCRIPTION OF SYMBOLS 1... Image forming apparatus/1a... Apparatus main body/11... Photosensitive drum (photoreceptor)/12... Charging roller/12a... Rotating shaft/12b... Elastic layer/13...・Cleaning roller (cleaning member)/13a Rotating shaft (part of cleaning member)/30 Drum container/31, 400, 600 Charging roller bearing (bearing member)/31a, 420, 610 Engaged portion (bearing member side projection)/32 Pressure spring (biasing means)/34 Pressure spring (cleaning member biasing means)/36, 710 Gear (rotating member)/100 drum cartridge (photoreceptor unit)/200, 300, spacing member/211, 311, 511 first engaging portion/212, 330, 530 second 2 Engaging portion (separating member side protrusion)/221 Engaging portion (cleaning member engaging portion)/700 Cleaning brush roller (another rotating body)

Claims (7)

a rotatable photoreceptor;
A charging device that is movably provided between a contact position that contacts the surface of the photoreceptor and a separation position that is separated from the surface of the photoreceptor, and charges the surface of the photoreceptor by applying a voltage at the contact position. Laura and
a bearing member that supports the rotating shaft of the charging roller;
urging means for urging the charging roller in a direction from the separated position toward the contact position;
a rotating member that rotates when a driving force is input;
It has a first engaging portion engageable with the rotating member and a second engaging portion provided at a position different from the first engaging portion, wherein the first engaging portion engages with the rotating member. In the engaged state, the separation holding position for holding the charging roller at the separation position against the biasing force of the biasing means and the engagement between the first engaging portion and the rotating member are disengaged. and a separation release position where the charging roller is released from being held at the separation position. a spacing member that moves in a predetermined direction from the holding position toward the spacing release position;
Provided on the bearing member, when the driving force is not input to the rotating member at the separation holding position, the engagement between the rotating member and the first engaging portion is disengaged, and the spacing member moves in the predetermined direction. In such a case, the movement of the spacing member is restricted by engagement with the second engaging portion, and the driving force is input to the rotation member at the separation holding position to move the spacing member in the predetermined direction. an engaged portion that disengages from the second engaging portion and allows the spacing member to move toward the separation release position when the device is about to move;
the second engaging portion is a spacing member-side projection projecting from the spacing member in a direction along the rotation axis direction of the charging roller;
the engaged portion is a bearing member-side protrusion that protrudes from the bearing member in a direction along the rotation axis direction of the charging roller;
When the driving force is not input to the rotating member at the separation holding position and the engagement between the rotating member and the first engaging portion is disengaged and the spacing member attempts to move in the predetermined direction, the The bearing member-side projection is engageable with the spacing member-side projection,
A photoreceptor unit characterized by: The engaged portion is positioned downstream of the second engaging portion in the predetermined direction when the spacing member is in the spaced holding position.
2. The photoreceptor unit according to claim 1, characterized by: At least one of the spacing member and the bearing member is configured such that when the driving force is input to the rotating member and the spacing member attempts to move in the predetermined direction, the second engaging portion is engaged with the engaged portion. elastically deform to overcome joints,
3. The photoreceptor unit according to claim 2, characterized by: At least one of the second engaging portion and the engaged portion engages the second engaging portion when the driving force is input to the rotating member and the separating member attempts to move in the predetermined direction. Relatively moves so that the part can get over the engaged part,
3. The photoreceptor unit according to claim 2, characterized by: The spacing member is provided swingably with respect to the bearing member,
5. The photosensitive unit according to any one of claims 1 to 4 , characterized by: The rotating member is provided on a rotating shaft of the photoreceptor so as to rotate together with the photoreceptor.
6. The photosensitive unit according to any one of claims 1 to 5 , characterized by: a cleaning member that is movably provided between a roller contact position that contacts the surface of the charging roller and a roller separation position that is separated from the surface of the charging roller, and that cleans the charging roller at the roller contact position;
cleaning member biasing means for biasing the cleaning member in a direction from the roller separation position toward the roller contact position;
the spacing member has a cleaning member engaging portion that can be engaged with a part of the cleaning member;
The cleaning member engaging portion is
When the spacing member is at the spacing holding position, the cleaning member is held at the roller spacing position against the urging force of the cleaning member urging means by engaging with a part of the cleaning member. ,
When the separation member moves from the separation holding position in the predetermined direction to the separation release position, the cleaning member is disengaged from a part of the cleaning member and held at the roller separation position. to release the
7. The photosensitive unit according to any one of claims 1 to 6 , characterized by:

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