JP2013148629A - Process cartridge and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process cartridge configured to separate a charging roller from a photoreceptor with a simple mechanism, while preventing an increase in size of a process cartridge or the image forming device.SOLUTION: A process cartridge 50 includes a photoreceptor 1, a charging roller 2, a support 21 for rotatably supporting a rotary shaft 2a of the charging roller 2, and a biasing member 25 for biasing the support 21 toward the photoreceptor 1. The support 21 includes a bearing part 21h, a contact part 21a, and a drive receiving part 21b. At the start of using the process cartridge 50, a rotating force of the photoreceptor 1 is transmitted to the drive receiving part 21b. Therefore, the support rotates around the rotary shaft of the charging roller 2 from a first position for serving as a spacer to a second position for serving as a bearing. In the first position, the support is pressed in a direction away from the photoreceptor 1. In the second position, the support is pressed in a direction toward the photoreceptor 1.

Description

  The present invention relates to a process cartridge used in an image forming apparatus such as a copying machine, a printer, and a facsimile using an electrophotographic method, and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus (electrophotographic image forming apparatus) using an electrophotographic method such as a copying machine or a laser beam printer, image formation is generally performed as follows.

  An electrophotographic photosensitive member (photosensitive member) as an image carrier is uniformly charged by charging means. The surface of the charged photoreceptor is selectively exposed by an exposure unit to form an electrostatic latent image. The electrostatic latent image is developed as a toner image by attaching toner by developing means. The toner image on the photoreceptor is transferred onto a recording material such as paper by a transfer unit. Thereafter, the recording material to which the toner image has been transferred is heated and pressurized by a fixing unit to fix the toner image on the surface thereof. After the toner image is transferred to the recording material, the transfer residual toner remaining on the surface of the photoconductor is removed by a cleaning unit and used for the next image formation.

  In addition, there are the following process cartridge type image forming apparatuses. That is, a photosensitive member, a charging unit, a developing unit, a cleaning unit, and a waste toner container are integrated into a cartridge container to form a process cartridge, and the process cartridge is detachably attached to the image forming apparatus main body. To do.

  According to this process cartridge system, maintenance of the image forming apparatus can be performed by the user himself / herself without depending on the service person, so that the operability can be remarkably improved.

  Further, by independently moving a developing device for a plurality of colors with respect to the photosensitive member to perform a developing operation, or by being fixedly arranged with respect to the photosensitive member and selectively driven. There are image forming apparatuses that form multicolor images and color images. There is also a process cartridge in which a photosensitive member, a charging unit, a cleaning unit, and a waste toner container used in such an image forming apparatus are integrated.

  Here, as the charging means incorporated in the process cartridge, a non-contact type using a corona discharger and a contact type using a charging roller which is a roller-type charging member are generally used. It is. In recent years, the latter contact-type charging means, which have the advantages of low ozone generation and low applied voltage, have come to be widely used.

  If the charging roller is left in contact with the photoconductor for a long time, a portion corresponding to a contact position in the charging means (hereinafter referred to as “contact portion”) may cause permanent deformation. . As a result, the charging ability of the charging roller changes, and image defects such as density unevenness may occur.

  Also, on the surface of the photosensitive member, the photosensitive member and the charging roller may rub against each other due to vibration during transportation or storage before the process cartridge is used, and a history as a charging memory may remain. As a result, image defects such as density unevenness may occur.

  Further, since the elastic layer of the charging roller is kept in contact with the photoconductor for a long period of time, the surface of the photoconductor may be contaminated by a substance that has exuded from the elastic layer.

  To solve the above-mentioned problems, a spacer for separating the charging roller from the photoconductor is brought into contact with the surface of the photoconductor, and the spacer is rotated or moved by rotation of the photoconductor, so that the charging roller contacts the photoconductor. A method of contacting is proposed (Patent Document 1).

JP 2003-76117 A

  According to the conventional method described above, the spacer that separates the charging roller from the photosensitive member operates by contacting the surface of the photosensitive member. Therefore, the length of the spacer mechanism is further required with respect to the longitudinal dimension of the charging roller and the photosensitive member, and the size of the process cartridge and the image forming apparatus increases.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a process cartridge and an image forming apparatus capable of separating a charging roller from a photosensitive member with a simple mechanism while suppressing an increase in the size of the process cartridge and the image forming apparatus. .

  The above object is achieved by the process cartridge and the image forming apparatus according to the present invention. In summary, the present invention provides a rotatable photosensitive member, a charging roller that contacts the photosensitive member and charges the photosensitive member, a support member that rotatably supports a rotation shaft of the charging roller, and the support member. A biasing member that biases the photosensitive member toward the photoconductor, wherein the support includes a bearing portion that slidably receives the rotating shaft, a contact portion that contacts the photoconductor, A drive receiving portion to which a driving force for rotating about the rotation shaft is transmitted, and the rotational force of the photosensitive member is transmitted to the drive receiving portion at the start of use of the process cartridge. The charging roller is in contact with the photoconductor from a first position that supports the rotating shaft in a state where the charging roller is separated from the photoconductor against the biasing force of the biasing member. A first supporting the rotating shaft; To the position of the rotation axis about the rotation axis, and in the first position, the contact portion abuts on the photoconductor, and the drive receiving portion receives the rotational force of the photoconductor on the drive receiving portion. The bearing portion is pressed in a direction away from the photoconductor against the urging force of the urging member, and in the second position, the contact portion is The process cartridge is separated from the photosensitive member, the drive receiving portion is separated from the drive transmitting portion, and the bearing portion is pressed in a direction toward the photosensitive member by an urging force of the urging member. It is.

  According to another aspect of the present invention, a rotatable photoconductor, a charging roller that contacts the photoconductor and charges the photoconductor, a support that rotatably supports a rotation shaft of the charging roller, and the support An urging member that urges the body toward the photoconductor, wherein the support includes a bearing portion that slidably receives the rotating shaft, and an abutment portion that abuts the photoconductor And a drive receiving portion to which a driving force for rotating about the rotation shaft is transmitted, and the rotational force of the photoconductor is transmitted to the drive receiving portion at the start of use of the image forming apparatus. Thus, the charging roller comes into contact with the photoconductor from a first position that supports the rotating shaft in a state where the charging roller is separated from the photoconductor against the biasing force of the biasing member. To the second position for supporting the rotating shaft Rotating about the rotation axis, and in the first position, the contact portion contacts the photoconductor, and the drive receiving portion transmits the rotational force of the photoconductor to the drive receiving portion. The bearing portion is pressed in a direction away from the photoconductor against the biasing force of the biasing member, and the contact portion is separated from the photoconductor in the second position. In addition, an image forming apparatus is provided in which the drive receiving portion is separated from the drive transmission portion, and the bearing portion is pressed in a direction toward the photoconductor by an urging force of the urging member. .

  According to the present invention, the charging roller can be separated from the photosensitive member with a simple mechanism while suppressing an increase in the size of the process cartridge and the image forming apparatus.

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. It is sectional drawing of the process cartridge which concerns on one Example of this invention. 1 is an external perspective view of a process cartridge according to an embodiment of the present invention. It is an external appearance perspective view of the state which removed the side part member of the process cartridge which concerns on one Example of this invention. It is the sectional view on the AA line of FIG. 1A is a side view showing a support provided in a process cartridge according to an embodiment of the present invention, and FIG. FIG. 4 is an assembled perspective view showing a support assembly portion in a process cartridge according to an embodiment of the present invention. FIG. 8 is an enlarged view of a portion surrounded by a circle in FIG. 7. FIG. 6 is a perspective view showing a drive transmission configuration to a support in a process cartridge according to an embodiment of the present invention. It is explanatory drawing for demonstrating operation | movement of the support body in the process cartridge which concerns on one Example of this invention. It is explanatory drawing for demonstrating operation | movement of the support body in the process cartridge which concerns on one Example of this invention.

  Hereinafter, the process cartridge and the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Example 1
1. First, the overall configuration and operation of an image forming apparatus according to an embodiment of the present invention will be described. FIG. 1 shows an overall configuration of an image forming apparatus 100 of the present embodiment.

  The image forming apparatus 100 of the present embodiment is a process cartridge type laser beam printer capable of forming a full color image using an electrophotographic method. In the present embodiment, the image forming apparatus 100 includes image forming units S for yellow, magenta, cyan, and black as a plurality of image forming units (stations) S. However, in the present embodiment, the configuration and operation of each image forming unit S are substantially the same except for the color of the toner to be used. Therefore, only one image forming unit S is shown in FIG. One image forming unit S will be described.

  The image forming unit S includes a photosensitive drum 1 that is a rotatable drum type electrophotographic photosensitive member (photosensitive member) as an image carrier. The photosensitive drum 1 is rotationally driven in the direction of arrow R1 in the figure. Around the photosensitive drum 1, the following units are provided in order along the rotation direction. First, the charging roller 2 is a roller-type charging member as charging means. Next, an exposure apparatus (laser scanner) 3 as an exposure unit. Next, there is a developing device 4 as a developing unit. Next, a primary transfer roller 5 which is a roller-type transfer member as a primary transfer unit. Next, it is the upstream brush 8 as a static elimination means. Next, the downstream brush 9 is a rotating body as a toner charging unit.

  Further, an endless intermediate transfer belt 6 as an intermediate transfer member is provided so as to face the photosensitive drum 1. The intermediate transfer belt 6 is stretched around a plurality of support rollers such as a driving roller 61 and a secondary transfer counter roller 62. The intermediate transfer belt 6 is rotationally driven in the direction of arrow R2 in the figure. The primary transfer roller 5 is disposed on the inner peripheral surface side of the intermediate transfer belt 6, presses the intermediate transfer belt 6 toward the photosensitive drum 1, and is a primary portion that is a contact portion between the intermediate transfer belt 6 and the photosensitive drum 1. A transfer portion N1 is formed. Further, on the outer peripheral surface side of the intermediate transfer belt 6, a secondary transfer roller 7 that is a roller-type transfer member as a secondary transfer unit is disposed at a position facing the secondary transfer counter roller 62. The secondary transfer roller 7 is pressed against the secondary transfer counter roller 62 via the intermediate transfer belt 6 to form a secondary transfer portion N2 that is a contact portion between the intermediate transfer belt 6 and the secondary transfer roller 7. .

  Further, the image forming apparatus 100 includes a cassette 10 for storing the recording material P, a feeding roller 11 for feeding the recording material P from the cassette 10, a registration roller 12 for controlling the conveyance timing of the recording material P, and a toner for the recording material P. The image forming apparatus includes a fixing device 13 as a fixing unit that fixes an image.

  During image formation, the surface of the rotating photosensitive drum 1 is uniformly charged to a predetermined polarity (negative polarity in this embodiment) and potential by the charging roller 2. At this time, a predetermined charging voltage (charging bias) is applied to the charging roller 2. The surface of the charged photosensitive drum 1 is exposed with information light (optical image) corresponding to image information by the exposure device 3, and an electrostatic latent image (electrostatic image) is formed on the photosensitive drum 1. The electrostatic latent image formed on the photosensitive drum 1 is supplied with toner by the developing device 4 and developed (visualized) as a toner image. The toner image formed on the photosensitive drum 1 is transferred (primary transfer) to the intermediate transfer belt 6 by the primary transfer roller 5 in the primary transfer portion N1. At this time, a positive primary transfer voltage (primary transfer bias) having a polarity opposite to the normal charging polarity of the toner (negative polarity in this embodiment) is applied to the primary transfer roller 5. For example, when forming a full-color image, yellow, magenta, cyan, and black toner images formed by a plurality of image forming portions S are sequentially transferred onto the intermediate transfer belt 6 and transferred (primary transfer). The

  The toner image formed on the intermediate transfer belt 6 is transferred (secondary transfer) to a recording material (recording medium) P such as paper by the secondary transfer roller 7 in the secondary transfer portion N2. At this time, a positive secondary transfer voltage (secondary transfer bias) having a polarity opposite to the normal charging polarity of the toner is applied to the secondary transfer roller 7.

  The recording material P onto which the toner image has been transferred is conveyed to the fixing device 13 where it is heated and pressed to fix the toner image thereon. Thereafter, the recording material P is discharged to the outside of the main body (apparatus main body) 110 of the image forming apparatus 100.

  On the other hand, the surface of the photosensitive drum 1 after the toner image is transferred to the recording material P is neutralized by the upstream brush 8, and the transfer residual toner remaining on the photosensitive drum 1 is negatively charged by the downstream brush 9. At this time, a positive voltage (static charge bias) is applied to the upstream brush 8, and a negative voltage (toner charging bias) is applied to the downstream brush 9. The transfer residual toner charged to the negative polarity on the photosensitive drum 1 is repelled by the negative development bias applied to the developing sleeve 41 of the developing device 4 and collected in the developer container 42 of the developing device 4. .

2. Next, the overall configuration of the process cartridge 50 used in the image forming apparatus 100 of this embodiment will be described.

  FIG. 2 is a cross-sectional view of the process cartridge 50 in the present embodiment, and FIG. 3 is an external perspective view of the process cartridge in the present embodiment.

  In general, a process cartridge is a cartridge in which a photosensitive member and at least one of process means that act on the photosensitive member are integrated into a cartridge that can be attached to and detached from the main body of the image forming apparatus. Examples of the process means include a charging means for charging the photosensitive member, a developing means for developing the electrostatic latent image formed on the photosensitive member, and a cleaning means for cleaning the toner remaining on the photosensitive member. . Further, the process means may include a charge removing means for discharging the photosensitive member, a toner charging means for charging the toner on the photosensitive member, and the like provided when the image forming apparatus adopts a cleanerless system.

  In this embodiment, the process cartridge 50 includes a photosensitive drum 1 that is a drum-type photosensitive member. In the photosensitive drum 1, information light (light image) based on image information from an optical system in the apparatus main body 110 is exposed through an exposure opening 58 of the process cartridge 50. In this embodiment, the process cartridge 50 includes, as process means, a charging roller 2 as charging means, a developing device 4 as developing means, an upstream brush 8 as charge eliminating means, and a downstream brush 9 as toner charging means. .

  In this embodiment, the photosensitive drum 1 is an organic photosensitive drum having a negatively chargeable OPC (organic optical conductor) photosensitive layer. In this embodiment, the outer diameter of the photosensitive drum 1 is 30 mm.

  In this embodiment, the charging roller 8 has a core metal 2a having a diameter of 8 mm and an elastic layer 2b formed on the outer periphery thereof so as to have an outer diameter of 14 mm. The elastic layer 2b can be formed of, for example, an elastic material whose resistance value is adjusted by adding an additive to ethylene propylene rubber, nitrile rubber, epichlorohydrin rubber, or the like. As will be described in detail later, the charging roller 2 is pressed toward the photosensitive drum 1 so that the elastic layer 2b is in contact with the surface of the photosensitive drum 1 during use. On the other hand, as will be described in detail later, the charging roller 2 is separated from the surface of the photosensitive drum 1 during transportation or storage before the use of the process cartridge 50 is started.

  The upstream brush 8 is a deck brush-like brush in which a brush portion 8b is formed on a base portion 8a. The upstream brush 8 is fixedly disposed so that the brush portion 8b contacts the surface of the photosensitive drum 1.

  The downstream brush 9 is a roller-like brush (brush roller) in which a brush portion 9b is formed on the outer periphery of a cored bar 9a. The brush 9b is in contact with the surface of the photosensitive drum 1 so as to be rotatable. Yes.

  The developing device 4 includes a developer accommodating portion 42 that accommodates toner as a developer. The developing device 4 is positioned as an opening of the developer accommodating portion 42 and is rotated as a developer carrying member so as to face the photosensitive drum 1. A possible developing sleeve 41 is arranged. The developing sleeve 41 contains a fixed magnet (magnet roller) as a magnetic field generating means, which is fixedly arranged with respect to the developer accommodating portion 42. A rotatable feed member 43 serving as a developer feeding means disposed in the developer accommodating portion 42 sends out the toner in the developer accommodating portion 42 toward the developing sleeve 41. Then, the developing sleeve 41 rotates, and a toner layer to which triboelectric charge is applied by the developing blade 44 is formed on the surface of the developing sleeve 41. The toner in the toner layer is transferred to the photosensitive drum 1 in accordance with the electrostatic latent image, whereby a toner image is formed on the surface of the photosensitive drum 1.

  In the present embodiment, the process cartridge 50 supports each means as described above by a plurality of frames, and these frames are combined to be integrated into a cartridge that can be attached to and detached from the apparatus main body 110 integrally. ing. That is, the process cartridge 50 includes a first support frame 51 in which the upstream brush 8 and the downstream brush 9 are incorporated. Further, the process cartridge 50 includes a second support frame 52 in which the developing blade 44 and the developing sleeve 41 of the developing device 4 are incorporated. Further, the process cartridge 50 forms a developer accommodating portion 42, rotatably supports the photosensitive drum 1, and a third support frame (hereinafter referred to as “container frame”) 53 in which the charging roller 2 is incorporated. Have Further, the process cartridge 50 has a first side member (side cover) 54 attached to one side surface in the longitudinal direction of the container frame 53. Further, the process cartridge 50 has a second side member (drum support member) 55 that rotatably supports the photosensitive drum 11 on the other side surface in the longitudinal direction of the container frame 53. Further, the process cartridge 50 includes a handle 56 for taking out the process cartridge 50 from the apparatus main body 110, and an upper cover 57 that covers the upper surface of the container frame 53.

3. Next, a mechanism for separating the charging roller 2 from the photosensitive drum 1 will be described.

  FIG. 4 is an external perspective view of the process cartridge 50 with the first side member 54 removed. FIG. 5 is a cross-sectional view taken along line AA in FIG. 4 and shows a state where the charging roller 2 is separated from the photosensitive drum 1.

  In the present embodiment, the process cartridge 50 supports the charging roller 2 rotatably, and supports the charging roller 2 away from the photosensitive drum 1 (charging) during transportation or storage before the use of the process cartridge 50 starts. Roller support) 21.

  6A is a side view of the support 21 and FIG. 6B is a perspective view of the bottom surface.

  The support 21 has an inner peripheral portion 21f formed of an arcuate surface that rotatably supports the rotation shaft 2a at the end in the longitudinal direction (rotation axis direction) of the charging roller 2. The support 21 has an abutting portion 21 a configured with an arcuate surface that contacts the surface of the cylindrical photosensitive drum 1. The contact portion 21 a is an R surface having a radius that is half the outer diameter of the photosensitive drum 1. Further, the support 21 has a drive receiving portion 21b to which the rotational force of the photosensitive drum 1 is transmitted. The drive receiving portion 21b has a tooth profile having a tooth surface that meshes with a support drive gear 22 as a drive transmission portion attached to the rotary shaft 9a at the end of the downstream brush 14 in the longitudinal direction (rotation axis direction). . Further, the support body 21 is an outer periphery formed of an arcuate surface that can slide along the surfaces (guide surfaces) of the guide portions 53a, 53b, 53c, and 53d (FIG. 8) of the container frame 53. Part (outer peripheral surface) 21d.

  More specifically, the support body 21 includes a substantially cylindrical bearing portion 21h provided with an opening 21g in a part in the circumferential direction, and a portion of the outer periphery of the bearing portion 21h from the outer side in the radial direction of the bearing portion 21h. And a separation portion 21i provided so as to protrude. The separation part 21i is provided in a substantially half circumference excluding the opening part 21g of the bearing part 21h. The spacing portion 21i has a plate-like shape having a predetermined thickness in the central axis direction of the bearing portion 21h, and the outer periphery of the bearing portion 21h is exposed on both sides of the spacing portion 21h at the coupling portion with the bearing portion 21h. It has become. In addition, the outer periphery of the bearing portion 21h is exposed on both sides of the sliding portion 21c in a joint portion between a sliding portion 21c and a bearing portion 21h, which will be described later. The inner periphery of the bearing portion 21 h is an inner peripheral portion 21 f that slidably receives the rotating shaft 2 a of the charging roller 2, and the exposed outer periphery of the bearing portion 21 h is along the guide portions 53 a to 53 d of the container frame 53. The outer peripheral portion 21d slides. A contact portion 21 a that contacts the outer peripheral surface of the photosensitive drum 1 is formed on a part of the outer surface of the separation portion 21 i. In this embodiment, the contact portion 21 a has an arcuate surface that matches the outer peripheral surface of the photosensitive drum 1. In addition, a drive receiving portion 21b to which a driving force for rotating the support 21 around the rotation shaft 2a of the charging roller 2 is formed on the other part of the outer surface of the separation portion 21i. In the present embodiment, the contact portion 21a is formed on the downstream side in the rotation direction of the charging roller 2 with respect to the drive receiving portion 21b in a state where the support body 21 is incorporated in the process cartridge 50.

  As will be described in detail later, the support 21 can take a first position (see FIG. 10A) that functions as a spacer (a separation member) that separates the photosensitive drum 1 and the charging roller 2 from each other. The support 21 can take a second position (see FIG. 10D) that functions as a bearing for the charging roller 2 so that the photosensitive drum 1 and the charging roller 2 come into contact with each other. Thus, the support 21 operates so that the position and the angle are switched with respect to the photosensitive drum 1.

  A planar bottom surface portion (planar portion) 21e is provided so that the end surface of the urging member 25 abuts when the support 21 is in the second position that functions as a bearing for the charging roller 2 (FIG. 10 ( d)). The angle of the bottom surface portion 21e is defined to be parallel to the end surface of the urging member 25. In this embodiment, a compression coil spring is used as the urging member 25.

  The opening 21g of the bearing 21h of the support 21 is positioned so that it faces the photosensitive drum 1 when the support 21 is in the second position that functions as the bearing of the charging roller 2 (FIG. 10). (See (d)). That is, the opening portion 21g and the bottom surface portion 21e are provided at positions facing each other in the circumferential direction of the bearing portion 21h. In the present embodiment, the opening 21g is provided for the following purpose. That is, the support 21 is deformed (swelled or the like) by sliding with the core metal 2 a of the charging roller 2, and the guide portions 53 a to 53 a of the support 21 provided on the core metal 2 a of the charging roller 2 or the container frame 53. This is to prevent the frictional force from increasing by biting 53d. That is, even if the support 21 is deformed (expanded or the like), a part of the shape of the support 21 is cut so that the inner peripheral portion 21f and the outer peripheral portion 21d are respectively the core metal 2a of the charging roller 2 or the container frame. It is configured such that it can abut on the guide portions 53 a to 53 d of the support body 21 provided on the body 53.

  Further, an arcuate sliding portion (arc portion) 21c is projected from a part of the outer periphery opposite to the separation portion 21i across the bottom surface portion 21e of the support 21 so as to protrude outward in the radial direction of the separation portion 21i. Is formed. The sliding portion 21c guides the end face of the urging member 25 while the support 21 moves between the first position and the second position. The sliding portion 21c is provided continuously to the bottom surface portion 21e. Thus, as shown in FIG. 11, even if the support 21 operates so that the position and the angle are switched between the first position where the support 21 functions as a spacer and the second position where the support 21 functions as a bearing, the biasing member 25 Can slide along the bottom surface portion 21e from the sliding portion 21c. Therefore, the urging force of the urging member 25 acting on the support 21 always acts in the direction toward the photosensitive drum 1. FIG. 11 shows the positional relationship between the support 21 and the urging force (indicated by an arrow) of the urging member 25 when the support 21 moves.

  Here, in this embodiment, in order to uniformly charge the surface of the photosensitive drum 1, a force for urging the charging roller 2 to the photosensitive drum 1 is required to be 7.7N. In this embodiment, one urging member 25 is provided at each end of the photosensitive drum 1 in the longitudinal direction (rotation axis direction). In this embodiment, the total weight of the charging roller 2 and the two supports 21 is 1.8 N. Accordingly, the urging force applied to the charging roller 2 by one urging member 25 is 4.75N.

  In order to obtain this predetermined urging force, in this embodiment, the urging member 25 is a spring steel having a wire diameter (diameter) of 0.45 mm, an inner diameter of 3.5 mm, a free length of 10.4 mm, and an effective number of 5.5. A closed-end coil spring having a flat end shape was used. In this embodiment, the length Ld of the urging member 25 when the support 21 is in the second position where the photosensitive drum 1 and the charging roller 2 abut (see FIG. 10D) is 6 Set to 4 mm.

  When the charging roller 2 is in contact with the photosensitive drum 1 for a long period of time under the above-described pressure, a portion corresponding to the contact position of the elastic layer 2b may be deformed. The process cartridge 50 is a consumable item that is replaced when necessary with respect to the apparatus main body 110, and a case where the storage period is longer than one year is assumed. When such deformation occurs, the charging ability may change, and image defects such as density unevenness may occur. Also, on the surface of the photosensitive drum 1, the photosensitive drum 1 and the charging roller 2 rub against each other due to vibration during transportation or storage before the use of the process cartridge 50 and the surface of the photosensitive drum 1 serves as a charging memory. History may remain. Further, when the elastic layer 2b of the charging roller 2 is kept in contact with the photosensitive drum for a long period of time, the surface of the photosensitive drum 1 may be contaminated by the material that has exuded from the elastic layer 2b. This may cause image defects such as density unevenness. Therefore, it is desirable that the photosensitive drum 1 and the charging roller 2 be separated from each other until the start of use.

  As described above, one of the objects of the present embodiment is that the charging roller 2 is kept in contact with the photosensitive drum 1 before the process cartridge 50 starts to be used. It is to suppress the occurrence of charged memory and contamination on the surface. In particular, in this embodiment, the deformation of the charging roller 2 is suppressed by a simple mechanism inside the process cartridge 50 while suppressing an increase in the size of the process cartridge 50.

  Next, a method for assembling the charging roller 2, the support body 21, and the urging member 25 to the container frame 53 will be described.

  FIG. 7 is an assembly perspective view in a state in which the charging roller 2, the support 21 and the biasing member 25 are assembled in the container frame 53. 8A is an enlarged view of a portion surrounded by a circle in FIG. 7, and FIG. 8B is a further enlarged view of the main part.

  The container frame 53 is provided with guide portions 53a, 53b, 53c, and 53d for guiding the outer peripheral portion 21d of the support 21. The guide portions 53 a to 53 d are provided upright from the bottom 53 i of the container frame 53 toward the photosensitive drum 1 side. The guide parts 53a and 53b are substantially half-circumferential outer peripheral part 21d on the side where the sliding part 21c is provided with respect to the bottom face part 21e of the support body 21, and one side and the other side of the sliding part 21c. Each outer peripheral portion 21d is guided. Further, the guide portions 53c and 53d are an outer peripheral portion 21d having a substantially half circumference on the side where the separation portion 21i is provided with respect to the bottom surface portion 21e of the support body 21, and one surface side and the other surface side of the separation portion 21i. Each outer peripheral portion 21d is guided.

  The container frame 53 is provided with a claw portion 53e that prevents the charging roller 2 from being pushed out by the biasing member 25 during assembly. The claw portion 53e is provided upright from the bottom 53i of the container frame 53 toward the photosensitive drum 1 side. The head 53e1 of the claw 53e protrudes inward in the longitudinal direction of the charging roller 2, and this head is elastically engaged with the rotary shaft 2a at the longitudinal end of the charging roller 2 during assembly. Match.

  Further, the support member placement portion 53f, which is an area surrounded by the guide portions 53a to 53d and the claw portion 53e of the bottom portion 53i of the container frame 53, includes a biasing member holding portion 53g for holding the biasing member 25, An urging member guide portion 53h is provided for guiding the urging member 25 when the urging member 25 is arranged or expanded or contracted.

  In the present embodiment, the urging member holding portions 53g are held in a plurality (four in this embodiment) in the radial direction of the urging member 25 projecting from the bottom 53i of the container frame 53 toward the photosensitive drum 1 side. The protrusions have action portions 53g1 at equal intervals. The biasing member holding portion 53g is formed such that its circumscribed circle has a diameter slightly smaller than the inner diameter of 3.5 mm of the biasing member 25 (for example, an inner diameter of about 3 mm). Further, the urging member holding portion 53g is set such that the height from the bottom (bottom surface) 53i of the container frame 53 is about 1-2 mm lower than the length in the same direction of the urging member 25 during compression ( 3 mm in this example). As a result, one end (the bottom 53i side of the container frame 53) of the urging member 25 is held by the urging member holding portion 53g, and the other end (photosensitive drum 1 side) is rubbed against the support 21. Even so, the posture of the biasing member 25 is maintained so as to be directed toward the center of the photosensitive drum 1. The biasing member guide 53h protrudes from the biasing member holding portion 53 toward the photosensitive drum 1, and is formed so that its circumscribed circle has a smaller diameter than the circumscribed circle of the biasing member holding portion 53g. The projection has a shape similar to that of the biasing member holding portion 53g.

  At the time of assembly, the urging member 25 is arranged on the support body arrangement portion 53f so that the inner periphery is fitted to the urging member holding portion 53g. From there, the rotation shaft 2a at the end in the longitudinal direction of the charging roller 2 with which the support 21 is fitted is arranged in the support arrangement portion 53f. At this time, in the support body 21, the separation portion 21i is passed through the slit 53j between the guide portions 53c and 53d, and the outer peripheral portion 21d is guided to the guide portions 53a to 53d. Then, the rotating shaft 2 a of the charging roller 2 is pressed toward the bottom 53 i of the container frame 53 against the elastic force of the urging member 25. Thereby, the claw portion 53e is engaged with the end portion of the rotating shaft 2a, and the charging roller 2 is disposed in the container frame 53 so as not to come out therefrom. Thereafter, as will be described later, the support 21 is engaged with the support drive gear 22 attached to the rotary shaft 9a at the end of the downstream brush 9 in the longitudinal direction of the downstream brush 9, and the photosensitive drum 1 and the charging roller 2 are arranged at a first position for separating them.

  In the process cartridge 50 of this embodiment, the support 21 having the same configuration is disposed at a symmetrical position with respect to the center in the longitudinal direction of the photosensitive drum 1, and is assembled by the same configuration, and the same. It is driven by the configuration.

  Next, a method for driving the support 21 in the process cartridge 50 will be described.

  FIG. 9 is a perspective view showing a drive transmission configuration when the support 21 rotates.

  The support 21 on both sides in the longitudinal direction of the photosensitive drum 1 has a drive receiving portion 21b of the separation portion 21i attached to the rotating shaft 9a at both ends in the longitudinal direction of the downstream brush 9 as a drive transmission portion. The gears 22 mesh with each other. The downstream brush drive gear 26 attached to the rotary shaft 9a at one end in the longitudinal direction of the downstream brush 9 is a flange 27 as an end member attached to one end in the longitudinal direction of the photosensitive drum 1. Meshed with the drum flange gear 27a.

  FIGS. 10A to 10D sequentially show the movement of the support 21 from the first position to the second position. The operation of the support 21 will be further described with reference to FIG.

  FIG. 10A shows an initial state in which the support 21 is incorporated in the container frame 53 and the charging roller 2 is separated from the photosensitive drum 1. In the figure, the support 21 is pressed against the photosensitive drum 1 at the abutting portion 21a by the urging force of the urging member 25, and is pressed against the support driving gear 22 at the drive receiving portion 21b. Thus, a stable state is maintained as a spacer for separating the photosensitive drum 1 and the charging roller 2 from each other. At this time, by reducing the length La of the urging member 25 to about 4 mm, the total urging force applied to the charging roller 2 becomes 14.2N. This value is about 8 times the total weight 1.8 N of the charging roller 2 and the two supports 21. Therefore, even if an impact is applied to the process cartridge 50, it can function as a spacer that keeps the separation state between the photosensitive drum 1 and the charging roller 2 stable.

  Next, as shown in FIG. 10B, when the rotational driving force is transmitted to the photosensitive drum 1, the photosensitive drum 1 starts to rotate in the direction of the arrow R1 in the figure. As a result, the drum flange gear 27a and the downstream brush drive gear 26 are engaged with each other as shown in FIG. 9, so that the support drive gear 22 mounted coaxially with the downstream brush drive gear 26 is also in the direction of arrow R3 in the figure. Rotate to. And since the support body drive gear 22 and the drive receiving part 21b of the support body 21 have meshed | engaged, the support body 21 rotates in the arrow R4 direction in the figure with the rotation of the support body drive gear 22. At this time, the support 21 is guided by guide portions 53 a to 53 d formed on the container frame 53. Therefore, the support body 21 is pushed by the tooth surface of the support body drive gear 22 and pushes the urging member 25 in the direction of arrow A1 (the direction of compression) in the figure, while the support body drive gear 22 is connected to the drive receiving portion 21b. Move while rotating until the end of the tooth profile.

  Next, as shown in FIG. 10C, the support 21 is pushed by meshing with the support drive gear 22 when the support drive gear 22 passes the end of the tooth shape of the drive receiving portion 21b. Disappear. Therefore, the support 2 is moved in the direction of arrow A2 (direction toward the photosensitive drum 1) by the pressing force of the urging member 25, whereby the charging roller 2 is also moved in the same direction and comes into contact with the photosensitive drum 1.

  Finally, as shown in FIG. 10 (d), the support 21 further rotates in the direction of the arrow R4 in the drawing until the surface of the bottom surface portion 21e becomes equal to the surface of the end portion of the biasing member 25, and is stable. Become position. At this position, the drive receiving portion 21b of the support 21 is completely separated from the support drive gear 22 with a predetermined gap G1. At this position, the contact portion 21a of the support 21 is completely separated from the surface of the photosensitive drum 1 with a predetermined gap G2. In this state, the length Ld of the urging member 25 is 6.4 mm, and the force for urging the charging roller 2 against the photosensitive drum 1 is 7.7 N as described above. As a result, the surface of the photosensitive drum 1 can be uniformly charged by the charging roller 2.

  As described above, in this embodiment, the process cartridge 50 includes the rotatable photosensitive member 1 and the charging roller 2 that contacts the photosensitive member 1 and charges the photosensitive member 1. Further, the process cartridge 50 includes a support body 21 that rotatably supports the rotating shaft 2 a of the charging roller 2, and an urging member 25 that urges the support body 21 toward the photoreceptor 1. The support 21 is a bearing 21h that slidably receives the rotating shaft 2a of the charging roller 2, a contact 21a that contacts the photosensitive member 1, and a drive for rotating about the rotating shaft 2a of the charging roller 2. Drive receiving portion 21b to which force is transmitted. Further, when the process cartridge 50 is started to be used, the support member 21 is transmitted with the rotational force of the photosensitive member 1 to the drive receiving portion 21b, so that the support member 21 resists the urging force of the urging member 25 from the first position. Then, the charging roller 2 rotates about the rotation shaft 2a to the second position. The first position is a position for supporting the rotating shaft 2 a of the charging roller 2 in a state where the charging roller 2 is separated from the photosensitive member 1. The second position is a position where the rotating shaft 2 a of the charging roller 2 is supported while the charging roller 2 is in contact with the photosensitive member 1. In the first position, the contact portion 21a contacts the photoconductor 1, and the drive receiving portion 21b engages with the drive transmission portion 22 that transmits the rotational force of the photoconductor 1 to the drive receiving portion 21b. The bearing portion 21 h is pressed in a direction away from the photoreceptor 1 against the urging force of the urging member 25. In the second position, the contact portion 21 a is separated from the photosensitive member 1, the drive receiving portion 21 b is separated from the drive transmission portion 22, and the bearing portion 21 h is driven by the urging force of the urging member 25. It is pushed in the direction toward

  In the present embodiment, the process cartridge 50 includes guide portions 53a to 53d that guide the bearing portion 21h when the support body 21 rotates, and the support body 21 has an arcuate outer periphery guided by the guide portions 53a to 53d. Part 21d. In the present embodiment, the support 21 has a flat bottom surface portion 21e with which the urging member 25 contacts. Further, in this embodiment, the support body 21 is continuous with the bottom surface portion 21e on which the biasing member 25 slides when the support body 21 rotates from the first position toward the second position. And a sliding portion 21c provided. In this embodiment, the rotational force of the photosensitive drum 1 is transmitted to the support 21 from a drive transmission unit attached to the rotating shaft of the rotating member that rotates by the rotational force of the photosensitive drum 1 being transmitted. As the rotating body, a rotating body that contacts the photosensitive drum 1 and neutralizes or charges the photosensitive drum 1 is preferable. In this embodiment, the rotating body is disposed adjacent to the upstream side of the charging roller 2 in the rotation direction of the photosensitive drum 1. A downstream brush 9 is used.

  According to the present embodiment, the newly added component may be only the support driving gear 22 for rotating the support 21. Therefore, a desired effect can be achieved with a simple configuration.

  In assembling the process cartridge 50, the support 21 may be incorporated on both sides of the charging roller 2 in the longitudinal direction instead of the conventional bearings. Therefore, the conventional assemblability is not impaired. Similarly, the conventional workability does not change when the process cartridge 50 is disassembled.

  Further, the support 21 is provided with a bottom surface portion 21e so that the end surface of the urging member 25 abuts when the support 21 is in the second position that functions as a bearing of the charging roller 2, and the angle of the bottom surface portion 21e is provided. Is defined to be parallel to the end face of the urging member 25. Further, before the angle of the bottom surface portion 21e becomes parallel to the end surface of the urging member 25, the engagement between the drive receiving portion 21b and the support driving gear 22 is released, and the support driving gear 22 with respect to the drive receiving portion 21b. The drive transmission from is completed. Therefore, finally, the support body 21 is rotated by the urging force of the urging member 25 until the bottom surface portion 21e comes into close contact with the end surface of the urging member 25 (FIG. 10D). Thereby, the drive receiving part 21b of the support body 21 is completely separated from the support body drive gear 22, and does not touch the rotating support body drive gear 22. Accordingly, when the drive receiving portion 21b of the support 21 touches the support drive gear 22 during the image forming operation, the charging roller 2 vibrates and the photosensitive drum 1 is non-uniformly charged, resulting in image defects such as density unevenness. Will not occur.

  As described above, according to this embodiment, the support 21 that functions as a bearing member of the charging roller 2 also has a function of a spacer (a separating member) for separating the charging roller 2 from the photosensitive drum 1. Therefore, in order to separate the charging roller 2 from the photosensitive drum 1, it is not necessary to use another separating member in addition to the bearing member of the charging roller 2. Accordingly, the size of the process cartridge 50 and the image forming apparatus 100 in the same direction increases because the length of the spacer mechanism is further required with respect to the longitudinal dimension of the charging roller 2 and the photosensitive drum 1. This can be suppressed. Thereby, the process cartridge 50 and the image forming apparatus 100 can be made compact. In addition, the spacer for separating the charging roller 2 from the bearing member of the charging roller 2 and the photosensitive drum 1 may be a single component. Therefore, in the case where the bearing member and the spacer are separate members, it is possible to achieve what guarantees the position between the components with one component. Accordingly, the number of parts to be managed with accuracy is reduced, the parts management is facilitated, and the performance of the process cartridge 50 and the image forming apparatus 100 is improved.

Other Embodiments Although the present invention has been described based on the specific embodiments, the present invention is not limited to the above-described embodiments.

  For example, in the above embodiment, the support driving gear is attached to the rotating shaft of the downstream brush. However, the present invention is not limited to this, and the support driving gear may be rotatably provided on a frame body that constitutes the process cartridge. Further, a gear that transmits driving to a driven member other than the support, such as the downstream brush drive gear in the above embodiment, may also be used as the support drive gear. Further, the rotational force may be transmitted from the photosensitive member to the support via a plurality of members such as a plurality of gears. As the photoconductor rotates, the rotational force of the photoconductor is transmitted to the support so that the support can be moved from the first position to the second position.

  Further, the drive transmission to the support is not limited to the gear meshing. For example, the drive may be transmitted to the support by frictional engagement between the drive receiving portion and the drive transmission portion of the support.

  Further, the support is not limited to abutting on the outer peripheral surface of the photoconductor, but is attached to an end in the longitudinal direction (rotation axis direction) of the photoconductor as an end member that rotates integrally. You may contact | abut to a flange etc.

  Further, the present invention is not limited to a mode in which the charging roller is easily attached to and detached from the main body of the image forming apparatus as a process cartridge and can be replaced as in the above embodiment. Even if the charging roller is shipped in the state where it is mounted on the image forming apparatus, the charging roller is not kept in contact with the photosensitive member during transportation or storage before the start of use. It may be desirable to ship away from the product. As described above, even when the charging roller is mounted on the image forming apparatus and separated from the photosensitive member, the present invention can be equally applied and the same effect as described above can be obtained. .

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging roller 9 Downstream brush 21 Support body 22 Support body drive gear 25 Energizing member

Claims (16)

A rotatable photoreceptor,
A charging roller that contacts the photoreceptor and charges the photoreceptor;
A support that rotatably supports the rotating shaft of the charging roller;
A biasing member that biases the support toward the photoconductor;
In a process cartridge having
The support is
A bearing portion that slidably receives the rotating shaft, an abutting portion that contacts the photoconductor, and a drive receiving portion to which a driving force for rotating about the rotating shaft is transmitted;
At the start of use of the process cartridge, the rotational force of the photosensitive member is transmitted to the drive receiving portion, so that the charging roller is separated from the photosensitive member against the urging force of the urging member. Rotating from the first position supporting the rotating shaft to the second position supporting the rotating shaft in a state where the charging roller is in contact with the photosensitive member,
In the first position, the contact portion contacts the photoconductor, and the drive receiving portion engages with a drive transmission portion that transmits the rotational force of the photoconductor to the drive receiving portion, so that the bearing The portion is pressed in a direction away from the photoreceptor against the biasing force of the biasing member,
In the second position, the contact portion is separated from the photoconductor, the drive receiving portion is separated from the drive transmission portion, and the bearing portion is applied to the photoconductor by the urging force of the urging member. A process cartridge that is pressed in the direction of the head.   The process according to claim 1, further comprising: a guide portion that guides the bearing portion when the support rotates, and the support has an arcuate outer peripheral portion that is guided by the guide portion. cartridge.   The process cartridge according to claim 1, wherein the support has a flat bottom surface portion with which the urging member comes into contact.   The support is a slide provided continuously on the bottom surface portion on which the biasing member slides when the support rotates from the first position toward the second position. The process cartridge according to claim 3, further comprising a moving part.   The rotational force of the photosensitive member is transmitted to the support member from the drive transmission unit attached to a rotating shaft of a rotating member that rotates by transmitting the rotational force of the photosensitive member. The process cartridge as described in any one of 1-4.   The process cartridge according to claim 1, wherein drive transmission between the drive transmission unit and the drive receiving unit is performed by meshing of gears.   The process cartridge according to claim 1, wherein the contact portion contacts an outer peripheral surface of the photoconductor.   The process cartridge according to claim 7, wherein the contact portion has an arcuate surface that matches the outer peripheral surface of the photosensitive member. A rotatable photoreceptor,
A charging roller that contacts the photoreceptor and charges the photoreceptor;
A support that rotatably supports the rotating shaft of the charging roller;
A biasing member that biases the support toward the photoconductor;
In an image forming apparatus having
The support is
A bearing portion that slidably receives the rotating shaft, an abutting portion that contacts the photoconductor, and a drive receiving portion to which a driving force for rotating about the rotating shaft is transmitted;
The charging roller is separated from the photosensitive member against the biasing force of the biasing member by transmitting the rotational force of the photosensitive member to the drive receiving portion at the start of use of the image forming apparatus. And rotating from the first position for supporting the rotating shaft to the second position for supporting the rotating shaft in a state where the charging roller is in contact with the photosensitive member,
In the first position, the contact portion contacts the photoconductor, and the drive receiving portion engages with a drive transmission portion that transmits the rotational force of the photoconductor to the drive receiving portion, so that the bearing The portion is pressed in a direction away from the photoreceptor against the biasing force of the biasing member,
In the second position, the contact portion is separated from the photoconductor, the drive receiving portion is separated from the drive transmission portion, and the bearing portion is applied to the photoconductor by the urging force of the urging member. An image forming apparatus, wherein the image forming apparatus is pressed in a heading direction.   The image according to claim 9, further comprising a guide portion that guides the bearing portion when the support rotates, and the support has an arcuate outer peripheral portion that is guided by the guide portion. Forming equipment.   11. The image forming apparatus according to claim 9, wherein the support has a planar bottom surface portion with which the urging member comes into contact.   The support is a slide provided continuously on the bottom surface portion on which the biasing member slides when the support rotates from the first position toward the second position. The image forming apparatus according to claim 11, further comprising a moving unit.   The rotational force of the photosensitive member is transmitted to the support member from the drive transmission unit attached to a rotating shaft of a rotating member that rotates by transmitting the rotational force of the photosensitive member. The image forming apparatus according to any one of 9 to 12.   The image forming apparatus according to claim 9, wherein drive transmission between the drive transmission unit and the drive receiving unit is performed by meshing of gears.   The image forming apparatus according to claim 9, wherein the contact portion is in contact with an outer peripheral surface of the photoconductor.   The image forming apparatus according to claim 15, wherein the contact portion has an arcuate surface that matches the outer peripheral surface of the photoconductor.

Images