JP2016164648A - Image forming apparatus and cartridge group - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably support an image carrier with support members.SOLUTION: When a first straight line connects the middle point of a line segment connecting a first support part and a second support part and the center of rotation of a first photoreceptor drum when viewed from a first axial direction, and a second straight line connects the middle point of a line segment connecting a third support part and a fourth support part and the center of rotation of a second photoreceptor drum when viewed from a second axial direction, the first straight line when viewed from the first axial direction and the second straight line when viewed from the second axial direction are not parallel to each other.SELECTED DRAWING: Figure 14

Description

  The present invention relates to an image forming apparatus and a cartridge group that can be attached to and detached from an apparatus main body of the image forming apparatus.

  Here, the image forming apparatus forms an image on a recording medium. Examples of the image forming apparatus include an electrophotographic copying machine using an electrophotographic image forming process, an electrophotographic printer (for example, a laser beam printer, an LED printer, etc.), a facsimile machine, and the like.

  The cartridge is a cartridge in which a part of the components of the image forming apparatus is integrally formed, and can be attached to and detached from the main body of the image forming apparatus. The cartridge group has a plurality of the cartridges.

  The image forming apparatus main body (apparatus main body) is an image forming apparatus portion excluding the cartridge.

  Conventionally, a configuration in which an electrophotographic photosensitive member (photosensitive drum) is supported by two planes is known (Patent Document 1).

  In Patent Document 1, a photoreceptor support device that rotatably supports a photoreceptor drum has two non-parallel contact surfaces for positioning the photoreceptor drum in contact with each other. The photosensitive drum is urged so as to abut on the two contact surfaces by a process means such as a charging roller and a developing roller arranged around the photosensitive drum.

Japanese Patent No. 4110128

  The present invention is a further development of the prior art. It is an object to stably support an image carrier with a support member.

In order to achieve the above object, an example of the invention according to the present application is as follows:
An image forming apparatus, comprising: a first photosensitive drum; a second photosensitive drum; a first drive input unit disposed at one end in a first axial direction of the first photosensitive drum; A second drive input unit disposed at one end portion in the second axial direction of the second photosensitive drum and a first axial end portion side of the first photosensitive drum are rotatably supported. A first support member having a first support portion and a second support portion, a third support portion for rotatably supporting the second axial end portion of the second photosensitive drum, and a second support portion A second support member having four support portions, and a midpoint of a line segment connecting the first support portion and the second support portion when viewed from the first axial direction, A first straight line connecting the rotation center of the first photosensitive drum, and the third support portion when viewed from the second axial direction and the Assuming that the second straight line connecting the midpoint of the line connecting the four support portions and the rotation center of the second photosensitive drum, the first straight line and the first straight line as viewed from the first axial direction. The second straight line seen from the axial direction of 2 is not parallel.

  As described above, according to the invention of the present application, the image carrier can be stably supported by the support member.

Sectional drawing of the image forming apparatus based on the Example of this invention 1 is a perspective view of an image forming apparatus according to an embodiment of the present invention. Sectional drawing of the image forming apparatus based on the Example of this invention Sectional drawing of the image forming apparatus based on the Example of this invention Assembly perspective view of a process cartridge according to an embodiment of the present invention Assembly perspective view of a process cartridge according to an embodiment of the present invention 1 is a schematic diagram of a drive unit of an image forming apparatus main body according to an embodiment of the present invention. Schematic diagram around the photosensitive drum portion according to an embodiment of the present invention Schematic diagram around the photosensitive drum portion according to an embodiment of the present invention Schematic diagram around the drive input unit according to an embodiment of the present invention FIG. 3 is an enlarged schematic view around the photosensitive drum portion according to the embodiment of the present invention. Schematic diagram of the drive unit of the image forming apparatus main body according to the second embodiment of the present invention. An enlarged schematic view around the photosensitive drum portion according to the third embodiment of the present invention. FIG. 3 is an enlarged schematic view around the photosensitive drum portion according to the embodiment of the present invention. Sectional drawing of the process cartridge based on the Example of this invention Sectional drawing of the process cartridge based on the Example of this invention

[General description of electrophotographic image forming apparatus]
A first embodiment of the present invention will be described below with reference to the drawings.

  In the following embodiment, a full-color image forming apparatus in which four process cartridges can be attached to and detached from the apparatus main body is illustrated as an image forming apparatus.

  Note that the number of process cartridges attached to the image forming apparatus is not limited to this. It is appropriately set as necessary.

  For example, in the case of an image forming apparatus that forms a two-color image, the number of process cartridges mounted on the main body of the image forming apparatus is two.

  In the embodiments described below, a printer is illustrated as an example of an image forming apparatus. However, a copier or a fax machine, or a multi-function machine having a copier function, a fax function, and a printer function may be used.

[Schematic configuration of image forming apparatus]
FIG. 1 is a schematic cross-sectional view of the image forming apparatus of this embodiment. FIG. 2A is a perspective view of the image forming apparatus of this embodiment. FIG. 16 is a sectional view of the process cartridge P of this embodiment. FIG. 5 is an assembled perspective view of the process cartridge P according to the present embodiment as viewed from the driving side, and FIG. 6 is an assembled perspective view of the process cartridge P according to the present embodiment as viewed from the non-driving side.

  As shown in FIG. 2, the image forming apparatus 1 is a four-color full-color laser printer using an electrophotographic image forming process, and forms a color image on a recording medium S. The image forming apparatus 1 is a process cartridge type, and a process cartridge is detachably attached to an electrophotographic image forming apparatus main body (apparatus main body) 2 to form a color image on a recording medium S.

  Here, regarding the image forming apparatus 1, the side on which the front door 3 is provided is the front surface (front surface), and the surface opposite to the front surface is the back surface (rear surface). Further, when the image forming apparatus 1 is viewed from the front, the right side is referred to as a driving side, and the left side is referred to as a non-driving side. FIG. 1 is a cross-sectional view of the image forming apparatus 1 as viewed from the non-driving side. Become the side.

  The image forming apparatus main body 2 includes four process cartridges P (PY, PM, PC, and PK), which are a first process cartridge PY, a second process cartridge PM, a third process cartridge PC, and a fourth process cartridge PK. It is arranged horizontally.

  A configuration obtained by removing the process cartridges PY, PM, PC, and PK from the image forming apparatus 1 is particularly referred to as an apparatus main body (image forming apparatus main body) 2.

  Each of the first to fourth process cartridges P (PY, PM, PC, PK) is an image forming unit having the same electrophotographic image forming process mechanism. However, the process cartridges PY, PM, PC, and PK have different colors for the developer used for image formation.

  A rotational driving force is transmitted to the first to fourth process cartridges P (PY / PM / PC / PK) from the drive output unit of the image forming apparatus main body 2. Details will be described later.

  A bias voltage (charging bias, developing bias, etc.) is supplied from the image forming apparatus body 2 to each of the first to fourth process cartridges P (PY, PM, PC, PK) (not shown).

  As shown in FIG. 16, each of the first to fourth process cartridges P (PY, PM, PC, PK) of this embodiment is a photosensitive drum (hereinafter referred to as “drum”) as an image carrier (photosensitive member). 4). The process cartridge P further includes a photosensitive unit 8 having a charging unit and a cleaning unit as process units that act on the drum 4.

  Each of the first to fourth process cartridges P (PY, PM, PC, PK) includes a developing unit 9 that includes a developing unit that develops the electrostatic latent image on the drum 4.

  The first process cartridge PY contains a yellow (Y) developer in the developing frame 29 and forms a yellow developer image on the surface of the drum 4.

  The second process cartridge PM contains a magenta (M) developer in the developing frame 29, and forms a magenta developer image on the surface of the drum 4.

  The third process cartridge PC contains a cyan (C) developer in the developing frame 29 and forms a cyan developer image on the surface of the drum 4.

  The fourth process cartridge PK contains a black (K) developer in the developing frame 29 and forms a black developer image on the surface of the drum 4.

  Above the first to fourth process cartridges P (PY, PM, PC, PK), a laser scanner unit LB as an exposure unit is provided. The laser scanner unit LB outputs a laser beam Z corresponding to the image information. Then, the laser beam Z passes through the exposure window 10 of the cartridge P and scans and exposes the surface of the drum 4.

  Below the first to fourth cartridges P (PY, PM, PC, PK), an intermediate transfer belt unit 11 as a transfer member is provided. The intermediate transfer belt unit 11 includes a driving roller 13 and tension rollers 14 and 15, and a flexible transfer belt 12 is stretched over the intermediate transfer belt unit 11.

  The lower surface of the drum 4 of each of the first to fourth cartridges P (PY, PM, PC, PK) is in contact with the upper surface of the transfer belt 12. The contact portion is a primary transfer portion. A primary transfer roller 16 is provided inside the transfer belt 12 so as to face the drum 4.

  Further, the secondary transfer roller 17 is disposed via the transfer belt 12 at a position facing the tension roller 14. A contact portion between the transfer belt 12 and the secondary transfer roller 17 is a secondary transfer portion.

  A feeding unit 18 is provided below the intermediate transfer belt unit 11. The feeding unit 18 includes a paper feeding tray 19 and a paper feeding roller 20 in which the recording media S are stacked and stored.

A fixing unit 21 and a discharge unit 22 are provided at the upper left in the apparatus main body 2 in FIG. The upper surface of the apparatus body 2 is a discharge tray 23.
The recording medium S to which the developer image is transferred is fixed by a fixing unit provided in the fixing unit 21 and then discharged to the discharge tray 23.

  The cartridge P is configured to be detachable from the apparatus main body 2 via a cartridge tray 60 that can be pulled out. FIG. 2A shows a state in which the cartridge tray 60 and the cartridge P are pulled out from the apparatus main body 2.

[Removable configuration]
Next, the attaching / detaching operation of the cartridge P (PY / PM / PC / PK) to the apparatus main body 2 will be described.

  FIG. 2A shows a state in which the cartridge tray 60 and the cartridge P are pulled out from the apparatus main body 2 as described above. FIG. 3 is a schematic cross-sectional view showing a state in which the cartridge tray 60 is pulled out from the apparatus main body 2 and the cartridge P is detachable. FIG. 4 is a schematic cross-sectional view showing the operation of attaching / detaching the cartridge P to / from the cartridge tray 60.

  A cartridge tray 60 on which the cartridge P can be mounted is provided in the apparatus main body 2. As shown in FIG. 3, the cartridge tray 60 is configured to be linearly movable (push / pull out) in the Gs1 and Gs2 directions which are substantially horizontal with respect to the apparatus main body 2. The cartridge tray 60 can take a mounting position in the apparatus main body 2 and a pull-out position pulled out from the mounting position.

  First, the mounting operation of the cartridge P (PY / PM / PC / PK) to the apparatus main body 2 will be described.

  When the front door 3 is opened and the cartridge tray 60 is moved in the direction of the arrow GS1 in FIG. 3, the cartridge tray 60 is moved to the drawer position. In this state, the cartridge P is mounted and held on the cartridge tray 60 from the direction of the arrow H1 in FIG. The cartridge tray 60 holding the cartridge P is moved in the direction of the arrow Gs2 in FIG. 3, and the cartridge tray 60 is moved to the mounting position in the apparatus main body 2. Then, by closing the front door 3, the mounting operation of the cartridge P to the apparatus main body 2 is completed.

  Meanwhile, the removal of the cartridge P from the apparatus main body 2 will be described. The cartridge tray 60 is moved to the drawer position in the same manner as the mounting operation of the cartridge P to the apparatus main body 2 described above. In this state, the cartridge P is removed in the direction of the arrow H2 in FIG. 4, and the operation of taking out the cartridge P from the apparatus main body 2 is completed. With the above operation, the cartridge P can be attached to and detached from the apparatus main body 2.

[Image forming operation]
The operation for forming a full-color image is as follows.

  The drum 4 of each of the first to fourth cartridges P (PY / PM / PC / PK) is rotationally driven at a predetermined speed (in the direction of arrow D in FIG. 16, counterclockwise in FIG. 1).

  The transfer belt 12 is also rotationally driven at a speed corresponding to the speed of the drum 4 in the forward direction of the drum (in the direction of arrow C in FIG. 1).

  The laser scanner unit LB is also driven. In synchronization with the drive of the laser scanner unit LB, the surface of the drum 4 is uniformly charged to a predetermined polarity and potential by the charging roller 5. The laser scanner unit LB scans and exposes the surface of each drum 4 with a laser beam Z according to the image signal of each color.

  Thereby, an electrostatic latent image corresponding to the image signal of the corresponding color is formed on the surface of each drum 4. This electrostatic latent image is developed by a developing roller 6 that is rotationally driven at a predetermined speed (in the direction of arrow E in FIG. 16, clockwise in FIG. 1). As a result, a developer image (toner image) is formed on the surface of each drum 4. The drum 4 is an image carrier that carries an image.

  By such an electrophotographic image forming process, a yellow developer image corresponding to the yellow component of the full-color image is formed on the drum 4 of the first cartridge PY. Then, the developer image is primarily transferred onto the transfer belt 12.

  Similarly, a magenta developer image corresponding to the magenta component of the full-color image is formed on the drum 4 of the second cartridge PM. The developer image is primary-transferred superimposed on the yellow developer image already transferred onto the transfer belt 12.

  Similarly, a cyan developer image corresponding to the cyan component of the full color image is formed on the drum 4 of the third cartridge PC. Then, the developer image is primary-transferred superimposed on the yellow and magenta developer images already transferred onto the transfer belt 12.

  Similarly, a black developer image corresponding to the black component of the full color image is formed on the drum 4 of the fourth cartridge PK. Then, the developer image is primary-transferred superimposed on the yellow, magenta, and cyan developer images already transferred onto the transfer belt 12.

  In this way, a four-color full-color unfixed developer image of yellow, magenta, cyan, and black is formed on the transfer belt 12.

  On the other hand, the recording medium S is separated and fed one by one at a predetermined control timing. The recording medium S is introduced into a secondary transfer portion which is a contact portion between the secondary transfer roller 17 and the transfer belt 12 at a predetermined control timing.

  As a result, in the course of the recording medium S being transported to the secondary transfer section, the four color superimposed developer images on the transfer belt 12 are sequentially transferred onto the surface of the recording medium S in sequence.

[Process cartridge configuration]
In the present embodiment, the first to fourth cartridges P (PY / PM / PC / PK) have the same electrophotographic image forming process mechanism, and the colors of the contained developer are different from each other. .

  The cartridge P includes a drum 4 and process means acting on the drum 4. Here, the process means includes a charging roller 5 (charging means) for charging the drum 4, a developing roller 6 (developing means) for developing a latent image formed on the drum 4, and a residual developer remaining on the surface of the drum 4. There is a cleaning blade 7 (cleaning means) or the like. The cartridge P is divided into a photosensitive unit 8 and a developing unit 9.

  As shown in FIGS. 5, 6, and 16, the photoreceptor unit 8 includes a drum 4, a charging roller 5, and a cleaning blade 7. Further, the photoreceptor unit 8 includes a cleaning container 26, a waste developer storage portion 27, and a cartridge cover member (the driving side cartridge cover member 24 and the non-driving side cartridge cover member 25 in FIGS. 5 and 6).

  The drum 4 is rotatably supported by cartridge cover members 24 and 25 as end members provided at both longitudinal ends of the cartridge P. Here, the axial direction of the drum 4 is defined as the longitudinal direction.

  The cartridge cover members 24 and 25 are also supporting members for the photosensitive drum fixed to the cleaning container 26 at both ends in the longitudinal direction of the cleaning container 26.

  As shown in FIG. 5, a coupling member 4 a for transmitting a driving force to the drum 4 is provided on one end side in the longitudinal direction of the drum 4. FIG. 2B is a perspective view of the apparatus main body 2, and the cartridge tray 60 and the cartridge P are not shown. Each coupling member 4a of the cartridge P (PY / PM / PC / PK) is engaged with a drum drive output member 61 (61Y / 61M / 61C / 61K) of the apparatus main body 2 shown in FIG. A driving force of a driving motor (not shown) of the apparatus main body is transmitted to the drum 4. That is, the coupling member 4a is a drive input unit that receives a driving force from the drum driving output member 61 and transmits the driving force to the drum 4, and is one end in the axial direction of the drum 4 of the cartridge P (the end on the driving side). ). The drum drive output member 61 is a transmission member that transmits a driving force (rotational force) to the drum 4.

  The charging roller 5 is supported by the cleaning container 26 so as to be in contact with the drum 4 and be driven to rotate.

  Further, the cleaning blade 7 is supported by the cleaning container 26 so as to contact the peripheral surface of the drum 4 with a predetermined pressure.

  The residual transfer developer removed from the peripheral surface of the drum 4 by the cleaning blade 7 is stored in a waste developer storage portion 27 in the cleaning container 26.

  The drive side cartridge cover member 24 and the non-drive side cartridge cover member 25 are provided with support portions 24a and 25a for rotatably supporting the developing unit 9 (see FIGS. 5 and 6).

[Development unit configuration]
As shown in FIGS. 5, 6, and 16, the developing unit 9 includes a developing roller 6, a developing blade 31, a developing frame 29, a bearing member 45, a developing cover member 32, and the like.

  The bearing member 45 supports the developing roller 6 so as to be rotatable. The developing roller 6 has a developing roller gear 69 at its longitudinal end. The bearing member 45 also rotatably supports an idler gear (not shown) for transmitting a driving force to the developing roller gear 69.

  The developing cover member 32 is fixed to the outside of a bearing member (not shown) in the longitudinal direction of the developing unit 9. The developing cover member 32 is configured to cover the developing roller gear 69 and the developing input coupling 74. Further, as shown in FIGS. 5 and 6, the developing cover member 32 is provided with a cylindrical portion 32 b. The drive input portion 74b of the development input coupling 74 is exposed from the opening inside the cylindrical portion 32b. When the cartridge P (PY / PM / PC / PK) is mounted on the apparatus main body 2, the drive input unit 74b is connected to the developing drive output member 62 (62Y, 62M, 62C, 62K) shown in FIG. Engage with. The drive input unit 74b is configured to receive a drive force from a drive motor (not shown) provided in the apparatus main body 2. The driving force input to the developing input coupling 74 from the apparatus main body 2 is configured to transmit driving to the developing roller gear 69 and the developing roller 6.

[Assembly of photoconductor unit and developing unit]
As shown in FIGS. 5 and 6, when the developing unit 9 and the photosensitive unit 8 are assembled, on one end side of the cartridge P, the support portion 24 a of the driving side cartridge cover member 24 is connected to the cylindrical portion 32 b of the developing cover member 32. The outer diameter part 32a is fitted. Then, on the other end side of the cartridge P, a protruding portion 29b provided to protrude from the developing frame 29 is fitted into the support hole portion 25a of the non-driving side cartridge cover member. Thus, the developing unit 9 is supported so as to be rotatable with respect to the photosensitive unit 8. Here, the rotation center of the developing unit 9 with respect to the photosensitive unit is referred to as an axis X. The axis X is a line connecting the center of the support hole 24a and the center of the support hole 25a.

[Development unit attitude]
As shown in FIGS. 5, 6, and 16, the developing unit 9 is configured to be urged by a pressure spring 95 that is an elastic member so that the developing roller 6 contacts the drum 4 about the axis X. Has been. That is, the developing unit 9 is pressed in the direction of the arrow G in FIG. 16 by the urging force of the pressure spring 95, and the moment in the direction of the arrow H acts around the axis X.
Thereby, the developing roller 6 can contact the drum 4 with a predetermined pressure. Further, the position of the developing unit 9 with respect to the photosensitive unit 8 at this time is defined as a contact position.

  FIG. 15 is a side view of the cartridge P as viewed from the drive side. In this figure, some parts are not shown for the sake of explanation. When the cartridge P is attached to the apparatus main body 2, the photosensitive unit 8 is positioned and fixed to the apparatus main body 2.

  FIG. 15A shows a state where the drum 4 and the developing roller 6 are in contact with each other.

  FIG. 15B shows a state where the drum 4 and the developing roller 6 are separated from each other. The developing unit 9 is rotated by an angle θ2 in the direction of the arrow K about the axis X by a force (not shown) from the apparatus main body. At this time, the drum 4 and the developing roller 6 are separated from each other by a distance ε2.

(First embodiment)
The drive train of the image forming apparatus main body will be described with reference to FIGS.
As shown in FIG. 2, the image forming apparatus main body 2 includes a development driving output member 62 (62Y, 62M, 62C, 62K, and the drum driving output unit 61 (61Y, 61M, 61C, 61K). It is integrally attached to the rotary body.
As shown in FIG. 7, the drum drive output unit 61 is the same for a plurality of gear trains G1, G2, G (GY, GM, GC, GK so as to distribute the drive from the motor M1 to each drum drive output unit 61. Since it is a structure, it is referred to as “G” unless otherwise specified).

  The arrangement of the photosensitive drum 4 and the drum drive output unit 61 will be described with reference to FIG.

  The photosensitive drum 4 includes a hollow columnar (drum-shaped) portion (columnar portion) 4d, a shaft portion 4a1 provided on one end side in the axial direction, and a shaft portion 4b1 provided on the other end side. A photosensitive layer is provided on the surface of the cylindrical portion 4d, and a latent image can be formed. The shaft portions 4a1, 4b1 have a smaller diameter than the cylindrical portion 4d.

  A coupling member 4a for receiving drive from the drum drive output unit 61 is integrally formed at the tip of the shaft portion 4a1. On the image forming apparatus main body 2 side, a drum drive output unit 61 that meshes with the coupling unit 4a is integrally formed with the gear G and attached. The coupling member 4a and the drum drive output unit 61 can be engaged and released.

  As will be described later, during the image forming operation after the process cartridge P is determined at a predetermined position of the image forming apparatus main body 2, the photosensitive drum 4 is coupled (engaged) with the coupling member 4a and the drum drive output unit 61 on the apparatus main body side. ) And rotate together.

  As shown in FIG. 1, in a state in which the process cartridge P is set in the image forming apparatus main body 2, the process cartridge P has a stay 80 attached integrally with the image forming apparatus main body 2 shown in FIG. Engages with the positioning portions 80Y, 80M, 80C, 80K.

  Further, as shown in FIG. 10 a, the rotation determining groove 24 d (FIGS. 6 and 10) of the process cartridge engages with a cartridge rotation positioning boss 81 c attached integrally with the image forming apparatus main body 2.

  The force acting on the drum during image formation will be described with reference to FIGS.

  First, the direction of the force applied to the photosensitive drum 4 by the drum drive output unit 61 will be described with reference to FIG.

  As described above, the drum drive output unit 61 transmits the drive so that the drive from the motor M1 is distributed to each drum drive output unit 61 via the idler gear G1 and the idler gear G2.

  Since the drum drive output unit 61 is integrated with the photosensitive drum 4 and receives the driving in the direction of arrow J as described above, the direction of the force received by the photosensitive drum 4 is the idler gear G2 and the gear G (Gy, Gm, Gc and Gk) work in the direction of the pressure angle Fy, Fm, Fc, Fk.

  As shown in FIG. 7, when a plurality of (in this case, four) photosensitive drums 4 are driven with respect to one motor M1, if the meshing force vectors are Fy, Fm, Fc, Fk, the idler gear G2 and each gear With G, the meshing force works in multiple directions. If the meshing vector directions are Fy, Fm, Fc, and Fk, in this embodiment, the meshing forces are Fy = Fc and Fm = Fk.

  That is, there are two types of vectors that act on the photosensitive drum 4.

  The reason why there are two types of vectors will be described. An engagement point at which the gear Gk meshes with the corresponding idler gear G2 when viewed from the axial direction of the photosensitive drum 4 of the cartridge Pk is MPk. A meshing point where the gear Gc meshes with the corresponding idler gear G2 when viewed from the axial direction of the photosensitive drum 4 of the cartridge Pc is MPc. Gears Gk and Gc and an idler gear G2 are arranged. The meshing points of the gears Gm and Gy are MPm and MPy. Then, the phase of the mesh point MPk in the gear Gk is different from the phase of the mesh point MPc in the gear Gc. On the other hand, the phase of the mesh point MPk in the gear Gk and the phase of the mesh point MPm in the gear Gm are the same, and the phase of the mesh point MPc in the gear Gc and the phase of the mesh point MPy in the gear Gy are the same. It is. For this reason, the directions of Fy, Fm, Fc, and Fk have the relationship described above.

  Next, the direction of the force received by all the photosensitive drums including the aforementioned meshing force will be described with reference to FIG.

  In this embodiment, the process cartridges PC and PY have a meshing force acting in the same direction, so that the process cartridges PK and PM have the same configuration with respect to the force received by each process cartridge. The process cartridges PC and PY have the same configuration. Therefore, the process cartridges PC and PY are hereinafter collectively referred to as a first image forming unit. The process cartridges PK and PM are hereinafter collectively referred to as a second image forming unit.

  In the following description, the process cartridge PC is taken as an example of the first image forming unit, and the process cartridge PK is taken as an example of the second image forming unit.

  FIG. 9 is a cross-sectional view of the process cartridge in FIG. 1 cut in a direction orthogonal to the photosensitive drum axis direction, and the periphery of the photosensitive drum 4 is enlarged and viewed from the arrow BV direction.

  In the case of the process cartridge PC, the following forces can be applied to the photosensitive drum 4 rotating in the arrow V direction. A force Fb due to the frictional resistance of the cleaning blade 7, a reaction force Fb2 generated when the cleaning blade 7 is bent, a force Fr due to the pressure applied by the charging roller 5, and a pressure Fd applied to the developing roller 6. Further, since the developing roller 6 (rotated in the direction of arrow W) has a surface speed higher than that of the photosensitive drum 4 (rotated in the direction of arrow V), the frictional force Fd2 generated there acts on the photosensitive drum 4. Furthermore, the pressure Ftr of the primary transfer roller 16 and the aforementioned engagement force Fc (= Fy) act on the photosensitive drum 4 (FIG. 9A). The cleaning blade 7, the charging roller 5, the developing roller 6, and the primary transfer roller 16 are contact members that contact the surface of the photosensitive drum 4.

  Note that the charging roller 5 and the primary transfer roller 4 have substantially the same surface speed with respect to the photosensitive drum 4, and therefore, no frictional force is generated. If there is a difference in the surface speed, it can be considered that the photosensitive drum 4 receives a frictional force therefrom.

  Similarly, in the case of the process cartridge PK, the cleaning blade 7, the charging roller 5, the developing roller 6, and the aforementioned engagement force Fk (= Fm) act on each other (FIG. 9C).

  These forces indicate forces applied during the image forming operation.

  As for the process cartridge PM, as shown in FIG. 9, all of the force except the meshing force Fk described above is applied in the same direction and the same amount as the process cartridge PK. Detailed description is omitted here.

  The resultant force acting on the process cartridges PC and PK is Fyc (FIG. 9B) and Fmk (FIG. 9D), respectively.

  That is, the resultant force acting on the photosensitive drum 4 of the process cartridge P varies in different directions (see θ1 in FIG. 9 (d)) depending on the arrangement of the gear of the drum drive output shaft from the motor M of the image forming apparatus body 2. It is suitable.

  The drive side cartridge cover 24 (24C, 24K) will be described in detail with reference to FIGS.

  FIG. 10A is an enlarged view of the periphery of the drive side cartridge cover 24C of the process cartridge PC.

  FIG. 10B is an enlarged view of the periphery of the drive cartridge cover 24K of the process cartridge PK.

  First, the drive side cartridge cover 24C will be described.

  The drive side cartridge cover 24C is provided with a hole 24hc for supporting the shaft portion 4a1 of the photosensitive drum 4 (see FIG. 10A). A pair of inclined planes are formed on a part of the inner peripheral surface of the hole. Portions 24s1 and 24s2 are provided. The plane portions 24 s 1 and 24 s 2 are support portions that support one end side (drive side) of the drum 4 in the axial direction.

  The above-mentioned resultant force Fyc is set so that the inclination of each plane portion is received by these plane portions 24s1 and 24s2. In addition, although mentioned later for details, although the force which the said plane parts 24s1 and 24s2 receive is good to distribute as evenly as possible, it does not necessarily need to be equal.

  Also, the same flat portions 24s11 and 24s12 are provided for the drive side cartridge cover 24MK of the process cartridge PK.

  The setting of the inclination of the plane portion 24 (24s1, 24s2, 24s11, 24s12) will be described with reference to FIG.

  FIG. 14A is an enlarged view of the periphery of the hole 24hc provided in the drive side cartridge cover 24C of the process cartridge PC. Specifically, FIG. 14A shows a virtual cross section of the process cartridge PC, and this cross section is orthogonal to the axial direction of the photosensitive drum 4.

  The shaft portion 4a1 of the photosensitive drum 4 is supported by contacting the flat portions 24s1 and 24s2 at the first contact point (first support portion) 24p1 and the contact point (second support portion) 24p2, respectively. Note that the contact portion between the shaft portion 4a1 and the plane portion 24s1 (24s2) is not actually a point but a straight line extending in a direction orthogonal to the cross section shown in FIG.

  In the cross section shown in FIG. 14A, the first line segment connecting the contact point 24p1 and the contact point 24p2 is L1, the midpoint 24p3 of the first line segment L1 and the point 24p4 which is the center of the photosensitive drum axis line. Let the connected 2nd line segment be L2 (1st straight line). The middle point 24p3 is an intermediate point between the first contact point 24p1 and the second contact point 24p2. The inclinations of the plane portions 24s1 and 24s2 are set so that the line segment L2 is substantially parallel to the resultant force Fyc (see FIG. 9). For this reason, the resultant force Fyc applied to the drive side cartridge cover 24C when the photosensitive drum 4 rotates is distributed in a well-balanced manner to the contact point (first support portion) 24p1 and the contact point (second support portion) 24p2. The drive side cartridge cover 24C can stably support the photosensitive drum 4.

  Similarly, in the process cartridge PK, the inclinations of the inclined surfaces 24s11 and 24s12 of the drive side cartridge cover 24K are determined in accordance with the direction of the resultant force Fmk (FIG. 14B). Details will be described later. That is, the first line segment in the process cartridge PK is L11, the second line segment is L12 (second straight line), and the second straight line L12 is substantially parallel to the line segment of the resultant force Fmk. ing. As a result, the resultant force Fmk received by the drive side cartridge cover 24K is distributed to the contact point (third support portion) 24p11 and the contact point (fourth support portion) 24p12 in a balanced manner.

  FIG. 14C is a diagram in which FIG. 14A and FIG. 14B are overlapped. In FIG. 14, the solid lines indicate the planes 24s1 and 24s2, and the two-dot chain lines indicate the planes 24s11 and 24s12.

  Then, the first straight line L2 as the second line segment in the process cartridge PC and the second straight line L12 as the second line segment in the process cartridge PK form an angle θ, and they are not parallel. In other words, the planar portion 24s (24s1, 24s2, 24s11, 24s12) of the hole 24h (hc and hk) differs depending on each process cartridge (or the position where the process cartridge is positioned).

  Of the plurality of cartridges (cartridge groups) PY, PM, PC, PK, the first straight line L2 in the cartridge PC, PY (first image forming unit) is inclined in a predetermined direction in accordance with the inclination of the resultant force Fyc. . On the other hand, the second straight line L12 in the cartridges PM and PK (second image forming unit) is inclined in a direction different from the predetermined direction in order to match the inclination of the resultant force Fmk.

  The direction of the resultant force (first resultant force) Fyc received by the drive side cartridge covers 24C and 24Y of the cartridges PC and PY and the direction of the resultant force (second resultant force) Fmk received by the drive side cartridge covers 24M and 24K of the cartridges PM and PK. Is different. That is, as can be seen from FIG. 10, the resultant force (second resultant force) Fmk received by the drive side cartridge covers 24M, 24K is compared with the resultant force (first resultant force) Fyc received by the drive side cover 24C, 24Y. Tilt in the direction of rotation. Therefore, the second straight line L12 of the drive side cartridge covers 24M, 24K is also in the clockwise direction with respect to the first straight line L2 of the drive side cover 24C, 24Y (that is, the same direction as the resultant force Fmk is inclined with respect to the resultant force Fyc). ).

  In the present embodiment, an example is shown in which the line segment L2 and the resultant force Fyc are parallel to each other, but this is a case where the reaction forces Fs1 and Fs2 received from the plane portions 24s1 and 24s2 are equal (FIG. 11). (A)).

  By doing so, since the force of Fyc is received almost evenly by the plane portions 24s1, 24s2, the deformation and scraping of the plane portions 24s1, 24s2 become even more uniform. Even if the usage time of the photosensitive drum increases, there is an effect of suppressing the fluctuation of the position of the photosensitive drum.

  As another example, the line segment L2 and the resultant force Fyc do not necessarily have to be parallel, and an effect can be obtained by relatively changing the direction of the line segment L2 in accordance with the direction of the resultant force acting on the photosensitive drum 4.

  In addition, the present embodiment can be viewed in another way. This will be described. In FIG. 10A showing the state of the photosensitive drum 4 viewed in the axial direction, a first straight line L2 parallel to the vector of the resultant force Fyc, the rotational center 24p4 of the photosensitive drum 4, and the rotational center 24p5 of the developing roller 6 Let θ3 (first angle) be an angle formed by the straight line L3 connecting the two. In FIG. 10B showing the state of the photosensitive drum 4 viewed in the axial direction, a second straight line L12 parallel to the resultant force Fmk vector, the rotational center 24p4 of the photosensitive drum 4, and the rotational center 24p5 of the developing roller 6 Let θ4 (second angle) be an angle formed by the straight line L13 connecting the two. Then, the drive side cartridge cover 24C and the drive side cartridge cover 24K are configured so that the angle θ3 and the angle θ4 are different. In this embodiment, when the absolute value of the difference between the angles θ3 and θ4 is Δθ (0 ° <Δθ ≦ 180 °), Δθ is 15 °. In this embodiment, since the straight line L3 and the straight line L13 described above are parallel, Δθ coincides with an angle θ (see FIG. 14C) formed by the vector of the resultant force Fmk and the vector of the resultant force Fyc. . Note that Δθ may be 15 ° or more.

  FIG. 11B shows the configuration of a process cartridge in which this embodiment is partially changed. In FIG. 11B, the direction of the first straight line L2 and the resultant force Fyc is not parallel. In the case of adopting such a configuration, the line segment L2 is set to be inclined upstream of the rotation direction Rt of the photosensitive drum 4 (counterclockwise in FIG. 11B) with respect to the resultant force Fyc. It is preferable to have been done. Of the two flat portions 24 s 31 and 24 s 32, it is preferable to increase the load applied to the flat portion 24 s 31 located on the downstream side in the rotation direction of the photosensitive drum 4 in order to stably support the photosensitive drum 4. It is.

  In this case, the planar portions 24s31 and 24s32 are set so that one of the reaction forces Fs31 and Fs32 does not become zero.

  In the present invention, the drive-side cartridge cover 24 has been described. However, since the meshing force does not act on the non-drive-side cartridge cover 25, it is not necessary to change the aforementioned direction for each process cartridge.

  Finally, the configuration of the present embodiment is summarized as follows.

  The image forming apparatus 1 includes a plurality of cartridges (image forming units) P (see FIG. 1).

  Each of the plurality of cartridges P includes a drum (image carrier) 4 that carries a developer image, and a cartridge cover (support member) 24 (24Y, 24M, 24C, and 24K) that supports one end of the drum 4 in the longitudinal direction. (See FIG. 5). The drum 4 has a cylindrical portion 4d having a photosensitive layer and a shaft portion 4a1 having a smaller diameter than the cylindrical portion 4d, and the cartridge cover 24 supports the shaft portion 4a1 (see FIGS. 8 and 10).

  More specifically, in the virtual cutting plane orthogonal to the axis of the drum 4, the cartridge cover 24 connects the shaft 4 a 1 of the drum 4 with contact points 24 p 1 (first support), 24 p 11 (third support). The contact points 24p2 (second support part) and 24p12 (fourth support part) respectively support (FIGS. 14A and 14B).

  On the cut surface, a line segment L1 connecting the contact point 24p1 and the contact point 24p2 is defined as a first line segment L1. On the cut surface, a line segment L11 connecting the contact point 24p11 and the contact point 24p12 is defined as a first line segment L11. In the cut surface, a straight line connecting the midpoint 24p3 of the first line segment L1 and the rotation center of the drum 4 is defined as a first straight line L2. On the cut surface, a straight line connecting the midpoint 24p3 of the first line segment L11 and the rotation center of the drum 4 is defined as a second straight line L12 (see FIGS. 14A and 14B).

  The plurality of cartridges P includes at least cartridges PC and PY serving as first image forming units and cartridges PM and PK serving as second image forming units. The photosensitive drum 4 of the cartridges PC and PY is the first photosensitive drum 4, and the coupling member 4a is the first drive input unit. The photosensitive drum 4 of the cartridges PM and PK is the second photosensitive drum 4, and the coupling member 4a is the second drive input unit. In the first image forming unit (cartridge PC, PY), the first straight line L2 is inclined in a predetermined direction (FIG. 14A). The second image forming unit (cartridge PM, PK) is one in which the second straight line L12 is inclined in a direction different from the predetermined direction (FIG. 14B).

  When the drum 4 rotates in each cartridge P, the resultant force (first resultant force) received by the cartridge cover 24C (24Y) from the drum in the cartridge PC (PY) is Fyc (FIG. 10A). In the cartridge PK (PM), the resultant force (second resultant force) received by the cartridge cover 24K (24M) from the drum 4 is Fmk (FIG. 10B). The directions of Fyc and Fmk are different.

  The direction in which the second straight line L12 of the cartridges PK and PM (second image forming unit) is inclined with respect to the first straight line L2 of the cartridges PY and PC (first image forming unit) is the second resultant force ( Fmk) is the same direction as the direction of inclination with respect to the first resultant force (Fyc). This is as shown in FIG. 10 and FIG.

  That is, the positions of the contact points 24p1 and 24p2 and the positions of the contact points 24p11 and 24p12 are determined in accordance with the directions of the resultant forces Fmk and Fyc. Since the load applied to the cartridge cover 24 that supports the drum 4 is distributed in a balanced manner at the two contact points, the durability of the cartridge cover 24 is improved and the cartridge cover 24 can stably support the drum 4 over a long period of time. become.

  The apparatus main body 2 of the image forming apparatus 1 has a plurality of drum drive output members 61 (61Y, 61M, 61C, 61K: transmission members) so as to correspond to the drums 4 of the respective process cartridges P (FIG. 2B). reference).

  The drum 4 has a coupling 4a1 that can be engaged with and released from the drum drive output member 61 on one end side (see FIG. 8). The drum 4 receives driving force from one end side through the coupling 4a1.

  The drum drive output members 61C and 61Y that transmit driving force to the cartridges PC and PY (first image forming unit) are used as the first transmitting member, and the driving force is transmitted to the cartridges PK and PM (second image forming unit). The drum drive output members 61K and 61M to be used as second transmission members. At this time, the gear Gc (Gy) provided on the first input member 61C (61Y) is the first gear, and the gear Gm (Gk) provided on the second input member 61K (61M) is the second gear. (See FIG. 7).

  The first gear Gc and the second gear Gk are engaged with a common idler gear (third gear) G2 and receive a driving force from the common idler gear G2 (see FIG. 7). That is, the idler gear G2 engages with both the first gear Gc and the second gear Gk. Similarly, the first gear Gy and the second gear Gm are engaged with a common idler gear (third gear) G2 and receive a driving force from the common idler gear G2.

  Here, the force Fc received by the first gear Gc from the idler gear G2 and the force Fk received by the second gear Gk from the idler gear G2 act in different directions. Similarly, the force Fc received by the first gear Gy from the idler gear G2 and the force Fm received by the second gear Gm from the idler gear G2 act in different directions. This is one of the reasons why the first resultant force Fyc and the second resultant force Fmk act in different directions.

(Second embodiment)
A second embodiment of the present invention will be described with reference to FIG.

  FIG. 12 is an example of a gear train (gears G11, G12, G14, G21, G22, Gy, Gm, Gc, Gk) of the image forming apparatus main body 2 using two motors M11, M12.

In this configuration, for example, one black process cartridge PK ′ is driven by the motor M1, and the remaining other process cartridges PY ′, PM ′, P′C are driven by the motor M1.
In the case of this configuration, the plane portion (not shown) of the process cartridge is set according to the direction of the resultant force including the meshing force (not shown) based on the same idea as the first embodiment.

  That is, the inclination of the flat portion (not shown) of the process cartridge PK is different from the remaining flat portions (not shown) of the process cartridges PY ′, PM ′, and PC ′.

In this embodiment, the cartridges PC ′, PM ′, and PY ′ are the first image forming unit, and the cartridge PK ′ is the second image forming unit. The photosensitive drum 4 of the cartridges PC ′, PM ′, and PY ′ is the first photosensitive drum 4, and the coupling member 4a is the first drive input unit. The photosensitive drum 4 of the cartridge PK is used as the second photosensitive drum 4, and the coupling member 4a is used as the second drive input unit. Even when three motors are used, the plane portion can be set with the same idea. That's fine.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, the shaft 4a1 of the photosensitive drum is supported so as to be rotatable on a plane. However, as another embodiment, the photosensitive drum may be supported by cylindrical surfaces 24b1 and 24b2 (see FIG. 13B). ).

  As another embodiment, the shaft portion 4a1 may be supported by ridge lines 24e1 and 24e2 formed by the surfaces 24e11 and 24e22 of the pair of plate-like members (see FIG. 13C).

  In any of these embodiments, an appropriate optimal support position is designed according to the resultant force of the photosensitive drum of each cartridge, and it is preferable to consider the reaction forces Fs1 and Fs2 as evenly as possible.

  In the present exemplary embodiment, the process cartridge that can be attached to and detached from the image forming apparatus main body has been described.

  As described above, by making the angle of the receiving surface of the photosensitive drum of each process cartridge different from that of other process cartridges, the force applied to the receiving surface receiving the photosensitive drum is distributed substantially evenly. . As a result, the receiving surface can be prevented from being scraped or deformed, and the position of the photosensitive drum can be stabilized even with a long service life.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Apparatus main body 4 Electrophotographic photosensitive drum 24 Drive side cartridge cover 61 Drum drive output part P Process cartridge

Claims (17)

An image forming apparatus,
A first photosensitive drum;
A second photosensitive drum;
A first drive input unit disposed at one end in the first axial direction of the first photosensitive drum;
A second drive input unit disposed at one end in the second axial direction of the second photosensitive drum;
A first support member including a first support portion and a second support portion that rotatably support the first axial end portion of the first photosensitive drum;
A second support member comprising a third support portion and a fourth support portion for rotatably supporting the second axial end portion of the second photosensitive drum;
Have
A first straight line connecting a midpoint of a line connecting the first support portion and the second support portion when viewed from the first axial direction and a rotation center of the first photosensitive drum. And a second point connecting the midpoint of the line connecting the third support part and the fourth support part when viewed from the second axial direction and the rotation center of the second photosensitive drum. An image forming apparatus, wherein the first straight line viewed from the first axial direction and the second straight line viewed from the second axial direction are not parallel. A first gear that includes a first drive output unit that engages with the first drive input unit and transmits a driving force, and rotates integrally with the first photosensitive drum;
A second gear that engages with the second drive input unit and transmits a driving force, and a second gear that rotates integrally with the second photosensitive drum;
Have
A meshing point that meshes with a gear that transmits driving force to the first gear of the first gear when viewed in the first axial direction, and the second gear when viewed in the second axial direction. 2. The image forming apparatus according to claim 1, wherein a meshing point that meshes with a gear that transmits a driving force to the second gear is arranged in a different phase.   The image forming apparatus according to claim 2, wherein the gear that transmits the driving force to the first gear and the gear that transmits the driving force to the second gear are the same gear. A first abutting member that abuts on the surface of the first photosensitive drum, and a second abutting member that abuts on the surface of the second photosensitive drum;
When the first photosensitive drum rotates, a vector of the resultant force of the force received by the first photosensitive drum from the first contact member and the force received by the gear meshing with the first gear The first straight lines are parallel;
When the second photosensitive drum is rotating, a vector of a resultant force of a force received by the second photosensitive drum from the second contact member and a force received from the gear with which the second gear meshes. The image forming apparatus according to claim 2, wherein the second straight lines are parallel.   5. The image according to claim 1, wherein the first drive input unit is a first coupling, and the second drive input unit is a second coupling. 6. Forming equipment.   6. The direction of the first resultant force received by the first photosensitive drum and the direction of the second resultant force received by the second photosensitive drum are different from each other. The image forming apparatus described.   The image according to claim 6, wherein the direction in which the second straight line is inclined with respect to the first straight line is the same as the direction in which the second resultant force is inclined with respect to the first resultant force. Forming equipment. The first and second photosensitive drums each have a cylindrical portion provided with a photosensitive layer, and a shaft portion having a smaller diameter than the cylindrical portion,
The image forming apparatus according to claim 1, wherein the first and second support members respectively support the shaft portions of the first and second photosensitive drums.   The first photosensitive drum, the first drive input unit, and the first support member are provided in a first cartridge that can be attached to and detached from an apparatus main body of the image forming apparatus. 2. The second photosensitive drum, the second drive input unit, and the second support member are provided in a second cartridge that is detachable from the apparatus main body. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 1, wherein toner images of different colors are formed on the first photosensitive drum and the second photosensitive drum. A group of cartridges,
(I) a first photosensitive drum; (ii) a first drive input section disposed at one end in the first axial direction of the first photosensitive drum; and (iii) the first photosensitive drum. A first support member including a first support portion and a second support portion that rotatably support the first axial end portion of the drum; and (iv) a first developing roller. 1 cartridge,
(V) a second photosensitive drum; (vi) a second drive input unit disposed at one end in the second axial direction of the second photosensitive drum; and (vii) the second photosensitive member. A second support member comprising a third support part and a fourth support part for rotatably supporting the one end side of the second axial direction of the drum; and (Viii) a second developing roller. Two cartridges;
Have
A straight line connecting a midpoint of a line connecting the first support portion and the second support portion and the rotation center of the first photosensitive drum when viewed from the first axial direction; The angle formed by the straight line connecting the rotation center of the first photosensitive drum and the rotation center of the first developing roller is defined as a first angle, and the third angle when viewed from the second axial direction. A straight line connecting the midpoint of the line connecting the support portion and the fourth support portion and the rotation center of the second photosensitive drum, the rotation center of the second photosensitive drum, and the second developing roller. A cartridge group, wherein the first angle and the second angle are different if a second angle is an angle formed by a straight line connecting the rotation centers of the first and second rotation angles. The first and second photosensitive drums each have a cylindrical portion provided with a photosensitive layer, and a shaft portion having a smaller diameter than the cylindrical portion,
12. The cartridge group according to claim 11, wherein the first and second support members support the shaft portions of the first and second photosensitive drums, respectively.   The cartridge group according to claim 11 or 12, wherein toner images of different colors are formed on the first photosensitive drum and the second photosensitive drum. The first cartridge and the second cartridge are mounted on an image forming apparatus,
The image forming apparatus includes:
A first gear that includes a first drive output unit that engages with the first drive input unit and transmits a driving force, and rotates integrally with the first photosensitive drum;
A second gear that engages with the second drive input unit and transmits a driving force, and a second gear that rotates integrally with the second photosensitive drum;
Have
A meshing point that meshes with a gear that transmits driving force to the first gear of the first gear when viewed in the first axial direction, and the second gear when viewed in the second axial direction. 14. The cartridge group according to claim 11, wherein a meshing point that meshes with a gear that transmits a driving force to the second gear is arranged in a different phase.   15. The cartridge group according to claim 14, wherein the gear that transmits the driving force to the first gear and the gear that transmits the driving force to the second gear are the same gear.   The cartridge according to claim 11, wherein the first drive input unit is a first coupling, and the second drive input unit is a second coupling. group. The cartridge group according to any one of claims 11 to 16, wherein an absolute value of a difference between the first angle and the second angle is 15 ° or more.

Images