JP2008268685A - Process cartridge with gear train and assembly method for the gear train - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear train easily assembled, an assembly method for the gear train, and a process cartridge using it. <P>SOLUTION: The process cartridge attachable to and detachable from the main body of an image forming apparatus includes: a photoreceptor drum; a developing roller for developing an electrostatic latent image formed on the photoreceptor drum; and a developer supply roller disposed in contact with the developing roller and used for supplying developer to the developing roller. The process cartridge also includes: a first gear 23 for transmitting driving force to the developing roller; a second gear 24 for transmitting the driving force to the developer supply roller; and a third gear 25 that engages with the first gear 23 and the second gear 24. Before fitted in a mounting shaft 28 in assembling, the third gear 25 is engaged with the first and second gears 23 and 24 mounted on the rotating shafts 23 and 24, respectively. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a process cartridge having an easily assembled gear train and a method for assembling the gear train.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus using an electrophotographic image forming process, an electrophotographic photosensitive drum and a developing roller acting on the electrophotographic photosensitive drum are integrated so as to be detachable from the main body of the electrophotographic image forming apparatus. A process cartridge system is adopted. According to this process cartridge system, the apparatus can be maintained by the user himself / herself without depending on the service person, so that the operation can be remarkably improved. For this reason, this process cartridge system is widely used in electrophotographic image forming apparatuses.

  Such process cartridges often have rotating members having different rotational speeds, and may be assembled by simultaneously engaging a plurality of gears.

  In this case, an assembly method is disclosed in which the gears are moved only in a direction parallel to the rotation axis of the gears with the shafts of the gear train fixed, and a plurality of gears are engaged with one gear (patent) Reference 1).

  Here, a method for assembling the gear train according to the conventional example will be described with reference to FIG. As shown in FIG. 7a, when assembling a gear train for driving transmission from one gear 100 to the two gears 101, 102, the two gears 101, 102 are assembled to the rotating shafts, and then engaged with these gears. Assemble 100. At this time, the gear 100 is moved in the direction of arrow J in FIG. Thereafter, the meshing with the gear 101 is completed while rotating the gear 100 (see FIG. 7b), and the meshing with the gear 102 is performed while further rotating the gear 100. Then, the assembly is completed by moving the gear 100 to a predetermined position and fixing it (see FIG. 7c).

Patent No. 3658202

  However, in the above-described gear train assembling method, in order to mesh each gear, it is necessary to rotate the gear 100 each time and further move the gear 100 in a direction parallel to the rotation shaft 103. there were. Further, if the timing of meshing with each gear is not changed, simultaneous meshing occurs, and it may be difficult to mesh depending on the phase of the gear teeth.

  In particular, when members such as rollers attached to the rotation shafts of the gears 101 and 102 shown in FIG. 7a are in contact with each other, when the gear 100 is assembled, the gears 101 and 102 are engaged with each other. Then, the rollers in contact with each other try to follow and rotate on the principle of the friction roller. For this reason, the load which rotates a gear becomes very large, and assembly workability | operativity will fall.

  Further, in order to prevent simultaneous meshing of a plurality of gears, it is necessary to set the order of meshing. When the tooth width of one gear is increased, an assembly space is required accordingly.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a process cartridge using a gear train with good assembling workability of the gear train and a method for assembling the gear train.

  Another object of the present invention is to provide a process cartridge using a gear train that can be assembled in a compact space, and a method for assembling the gear train.

  A typical means in the present invention for solving the above problems is that the process cartridge is detachably mounted on the electrophotographic image forming apparatus main body, and is formed on the electrophotographic photosensitive drum and the electrophotographic photosensitive drum. A developing roller for developing an electrostatic latent image; a developer supplying roller that contacts the developing roller and supplies the developer to the developing roller; and a first gear that transmits a driving force to the developing roller; A second gear that transmits a driving force to the developer supply roller; and a third gear that meshes with the first gear and the second gear. Before engaging with the attachment shaft, the first gear and the second gear attached to the respective rotation shafts can be engaged with each other.

  In the present invention, when assembling the third gear, since the first gear and the second gear are engaged with each other and fitted to the rotary shaft, the meshing workability with each gear is greatly improved. As a result, the assembly efficiency can be improved.

  Further, since the assembling operation is simple, when the assembling by the automatic machine is to be performed, the automatic machine device can be simplified, and the assembling cost can be further reduced.

  Further, it is not necessary to worry about the order of meshing of gears, the degree of freedom of design is increased, and a compact gear layout can be realized with respect to a gear for driving the developer supply roller and a gear for driving the developer supply roller.

[First Embodiment]
Next, a gear train and an assembling method thereof according to an embodiment of the present invention will be described when applied to a process cartridge used in an electrophotographic image forming apparatus.

[Electrophotographic image forming apparatus]
First, an electrophotographic image forming apparatus (hereinafter referred to as “image forming apparatus”) that forms an image using the process cartridge of the present embodiment will be described together with an image forming operation with reference to FIG. FIG. 1 is an overall schematic explanatory diagram of the image forming apparatus.

  The image forming apparatus A of the present embodiment is a laser beam printer in which four process cartridges (hereinafter referred to as “cartridges”) Py, Pm, Pc, and Pk are detachably attached to the apparatus main body 1. Each of the cartridges Py, Pm, Pc, and Pk constitutes an image forming unit that forms each color image of yellow (y), magenta (m), cyan (c), and black (k). Each of the cartridges is detachably attached to the apparatus main body 1 of the image forming apparatus A by a user.

  As shown in FIG. 1, the apparatus main body 1 is irradiated with laser light based on an image signal on the surface of each electrophotographic photosensitive drum (hereinafter referred to as “photosensitive drum”) 3 by a laser scanner 2. An electrostatic latent image is formed. The electrostatic latent image is developed by a developer (hereinafter referred to as “toner”) by each developing means, and a toner image is formed on the surface of each photosensitive drum 3. This toner image is formed by applying a voltage to the transfer rollers 4y, 4m, 4c, and 4k, and sequentially transferring the toner images of the respective colors on the intermediate transfer belt 5 to form a color image.

  In synchronization with the image formation, the sheet S is conveyed from the sheet cassette 6 mounted at the lower part of the apparatus main body to the secondary transfer unit by the feeding roller 7 and the conveying roller 8. The toner image on the intermediate transfer belt 5 is transferred to the sheet S by applying a bias to the secondary transfer roller 9 in the secondary transfer portion. Thereafter, the sheet S is conveyed to the fixing unit 10 where the toner image is heated and fixed, and is discharged by the discharge roller 11 to the discharge unit 12 at the upper part of the apparatus main body.

[Process cartridge]
Next, the cartridges Py, Pm, Pc, and Pk of this embodiment will be described with reference to FIGS. 2 is a schematic explanatory view of the process cartridge, and FIG. 3 is a perspective explanatory view of a drive transmission structure of the process cartridge.

  Each cartridge Py, Pm, Pc, Pk has the same configuration except that it stores toners of different colors. Therefore, here, the description will be made using the cartridge Py.

  The cartridge Py includes a photosensitive drum 3 and process means that acts on the photosensitive drum 3. Here, as process means, charging means 13 for charging the photosensitive drum 3, developing means 14 for developing the electrostatic latent image on the photosensitive drum 3, and cleaning means 15 for cleaning the toner remaining on the photosensitive drum 3. Etc. The charging means of the present embodiment is constituted by a charging roller 13 that is in contact with the photosensitive drum 3 and is driven to rotate.

  Further, the developing means 14 has a toner supply roller 14b and a developing roller 14c rotatably provided in the toner storage portion 14a, and regulates the layer thickness of the toner supplied to the roller 14c on the peripheral surface of the developing roller 14c. The developing blade 14d is in contact. Then, the toner is supplied to the developing roller 14c by the rotation of the toner supply roller 14b, and the toner is supplied from the developing roller 14c to the photosensitive drum 3 for development.

  The cleaning means 15 is for scraping off the toner remaining on the photosensitive drum 3 after transferring the toner image with a cleaning blade 15a and collecting it in the waste toner storage portion 15b.

  Here, the cartridge Py is divided into a cleaner unit 16 as a first frame and a developing unit 17 as a second frame.

  As shown in FIGS. 2 and 3, the cleaner unit 16 includes a photosensitive drum 3, a charging unit 13, a cleaning blade 15 a, a waste toner storage unit 15 b, a drum frame 18, and a cover member 19. One end side of the photosensitive drum 3 in the longitudinal direction is rotatably supported by a support portion 19a of a cover member 19 as shown in FIG.

  The cover member 19 is fixed to the drum frame 18 at both ends in the longitudinal direction of the drum frame 18. A coupling member 20 for transmitting a driving force to the photosensitive drum 3 is provided on one end side in the longitudinal direction of the photosensitive drum 3. The coupling member 20 engages with a main body coupling member (not shown) when the cartridge Py is mounted on the apparatus main body 1. Then, the driving force from a driving motor (not shown) provided in the apparatus main body 1 is transmitted to the coupling member 20, whereby the photosensitive drum 3 rotates. Further, the charging means 13 is supported by the drum frame 18 so as to be in contact with the photosensitive drum 3 and can be driven to rotate. Further, the cleaning means 15 is supported by the drum frame 18 so as to come into contact with the peripheral surface of the photosensitive drum 3 with a predetermined pressure.

  As shown in FIGS. 2 and 3, the developing unit 17 includes a developing roller 14c, a developing blade 14d, a developing frame 21, and a cover member 22. The developing frame 21 includes a developing roller 14c, a toner storage portion 49, and a developing blade 14d. Further, the developing unit 17 rotatably supports a developing roller 14c having a developing roller gear 23 attached to the end of the rotating shaft. Further, a toner supply roller 14b having a toner supply roller gear 24 attached to the end of the rotating shaft is rotatably supported.

  Further, the developing unit 17 has an input gear 25. The input gear 25 is configured as a step gear having a large-diameter gear portion 25a and a small-diameter gear portion 25b coaxially. The large-diameter gear portion 25a meshes with the developing roller gear 23, and the small-diameter gear portion 25b meshes with the toner supply roller gear 24, so that the driving force of the input gear 25 is transmitted to the developing roller 14c and the toner supply roller 14b. ing.

  In this embodiment, since the developing roller 14c and the toner supply roller 14b have different rotational peripheral speeds, the input gear 25 is a stepped gear. However, the input gear 25 may not be a stepped gear depending on the relationship of the peripheral speed.

  In the present embodiment, the developing roller 14c and the toner supply roller 14b have the same rotation direction as shown in FIG. For this reason, a gear train configuration is used to drive the developing roller gear 23 and the toner supply roller gear 24 from the same input gear 25.

  Here, when the cartridge Py is mounted on the apparatus main body 1, the input gear 25 meshes with a main body gear (not shown), and a driving force from a drive motor (not shown) provided on the apparatus main body 1 is transmitted. The

[Gear train configuration]
Here, the gear train structure of the input gear 25, the developing roller gear 23, and the toner supply roller gear 24 will be described with reference to FIGS. 4 and 5 are explanatory diagrams of the assembly structure of the gear train.

  As described above, the developing roller gear 23 serving as the first gear is attached to the end of the rotating shaft (first rotating shaft) 26 of the developing roller 14c serving as the first rotating body. A driving force is transmitted to the developing roller 14c. Similarly, a toner supply roller gear 24 as a second gear is attached to the end of the rotation shaft (second rotation shaft) 27 of the toner supply roller 14b as the second rotating body, A driving force is transmitted to the toner supply roller 14b.

  An input gear 25 that is a third gear for transmitting a driving force to each of the gears 23 and 24 is attached to the attachment shaft 28.

  In assembling the gear train, first, the developing roller gear (hereinafter referred to as “first gear”) 23 is attached to the rotating shaft 26, and the toner supply roller gear (hereinafter referred to as “second gear”) 24 is attached to the rotating shaft 27. Thereafter, an input gear (hereinafter referred to as “third gear”) 25 is attached so as to mesh with both the gears 23, 24.

  At this time, the relationship between the third gear 25 and the first and second gears 23 and 24 is such that the first gear 23 and the second gear 23 attached to the respective rotary shafts 26 and 27 as shown in FIG. Even when meshed with the gear 24, the third gear 25 is not fitted to the mounting shaft 28. In this embodiment, the meshing width k1 between the large-diameter gear portion 25a of the third gear 25 and the first gear 23 and the meshing width k2 between the small-diameter gear portion 25b and the second gear 24 are each about 1 mm. The length of the mounting shaft 28 is set so that the third gear 25 and the mounting shaft 28 have a gap d1 = 1 mm when engaged.

  Since the gear train is in the relationship as described above, when the third gear 25 is assembled, the gear portions 25a and 25b are engaged with the first gear 23 and the second gear 24, and then the engagement state is changed. The third gear 25 can be fitted and attached to the attachment shaft 28 while being maintained. Therefore, the gear train of this embodiment can be assembled by a robot.

  That is, as shown in FIG. 5, the third gear 25 is gripped by the robot arm 29 and moved in a direction perpendicular to the axial direction of the mounting shaft 28 (in the direction of arrow X in FIG. 5).

  Then, the large diameter gear portion 25 a is engaged with the first gear 23 attached to the rotating shaft 26, and the small diameter gear portion 25 b is engaged with the second gear 24 attached to the rotating shaft 27. The meshing widths k1 and k2 at this time are sufficient as described above. At this time, the third gear 25 is not fitted to the mounting shaft 28 because it has a gap d1.

  Thereafter, the robot arm 29 moves the third gear 25 in the direction parallel to the axial direction of the mounting shaft 28 (in the direction indicated by the arrow Y in FIG. 5) while maintaining the above-mentioned meshing state, and moves the third gear 25 to the mounting shaft. Fit to 28, move to a predetermined position and fix.

  By assembling as described above, a plurality of gears can be engaged from the side of the gear surface. Thereby, it is not necessary to rotate the third gear 25 for the gear alignment when the gear train is assembled, and the work efficiency of the gear alignment can be improved. This is because it is easier to engage and assemble the gears in the radial direction of the gear than in the case of assembling the teeth from the rotational thrust direction of the gear.

  In addition, also when assembling the gear from the rotation radial direction of a gear like this embodiment, the case where tooth-tip contact arises is assumed. However, since the third gear 25 is not fitted to the mounting shaft 28 when the gears are engaged, even if the third gear 25 is slightly rotated, the first gear 23 and the second gear 24 are It does not rotate.

  If the first and second gears 24 must be rotated in order to align the teeth when the third gear 25 is assembled as in the prior art, the developing roller 14c and the toner supply roller 14b are in contact with each other. And rotating in the same direction, the rotational load is about 2 to 3 kg · cm, and a large load is applied.

  On the other hand, in this embodiment, as described above, it is not necessary to rotate the developing roller 14c and the toner supply roller 14b for the tooth alignment, so that no load is applied for the tooth alignment. Therefore, when assembling the third gear 25, the third gear 25 may be configured to be slightly rotatable by the robot arm 29 in order to escape the tooth tip contact.

  Further, since the assembly can be performed simply by moving the third gear 25 in the direction orthogonal to the axial direction of the mounting shaft 28 and in the direction parallel thereto, the assembly space is small.

  Moreover, tooth tip contact at the time of assembly can be avoided also by sharpening the tooth tip. In the assembling method of this embodiment, there is no need to worry about the order of gear engagement. For this reason, the freedom degree of design increases and a compact gear layout is realizable.

[Second Embodiment]
Next, an apparatus according to the second embodiment will be described with reference to FIG. Note that the basic configuration of the apparatus of this embodiment is the same as that of the above-described embodiment, and thus a duplicate description is omitted. Here, a configuration that is a feature of this embodiment will be described. Moreover, the same code | symbol is attached | subjected to the member which has the same function as embodiment mentioned above.

  FIG. 6 is an explanatory diagram of the assembly configuration of the gear train according to the second embodiment. This embodiment is different from the first embodiment in the mounting shaft configuration of the third gear 25. That is, in the first embodiment, an attachment shaft 28 for attaching the third gear 25 to the developing frame 21 is provided, and a fitting hole (not shown) provided in the third gear 25 is fitted to the attachment shaft 28 for attachment. It was like that.

  On the other hand, in the present embodiment, as shown in FIG. 6, the third gear 25 is provided with a shaft portion 25c, and the mounting shaft 28 provided on the developing device frame 21 is provided with a hole portion 28a. Then, the third gear 25 can be fitted to the mounting shaft 28 by fitting the shaft portion 25c into the hole portion 28a.

  When the gear portions 25a and 25b of the third gear 25 are engaged with the first and second gears 23 and 24, there is a gap d2 between the shaft portion 25c and the hole portion 28a. The gear 25 is not fitted to the mounting shaft 28.

  Therefore, even in the present embodiment, it is possible to engage a plurality of gears from the side of the gear surface, and it is not necessary to rotate the third gear 25 for gearing when the gear train is assembled, It is possible to improve the working efficiency of the tooth alignment.

  In the present embodiment, since the shaft portion 25c for fitting is provided in the third gear 25, the fitting state can be stabilized even if the gear is reduced in size. That is, when the fitting hole is formed on the third gear 25 side, if the gear is downsized, the fitting hole must also have a small diameter, and the fitting shaft portion also has a small diameter in accordance with this. However, when the fitting protrusion is provided on the gear side as in the present embodiment, the diameter of the shaft portion 25c can be made relatively large even when the gear is downsized. For this reason, since it can be made to fit, without reducing the intensity | strength of a fitting shaft, the fitting state of a gear is stabilized.

[Other Embodiments]
In the above-described embodiment, the first, second, and third gears are illustrated as spur gears. However, even if these gear trains are helical gears, they can be assembled in the same manner, and the same effects can be obtained. be able to.

  In the above-described embodiment, the case of assembling using a robot has been described. However, the present invention can also be effectively used for so-called hand assembly that is assembled by an operator.

1 is an overall schematic explanatory diagram of an image forming apparatus. It is a schematic explanatory view of a process cartridge. It is a perspective explanatory view of a drive transmission configuration of a process cartridge. It is assembly structure explanatory drawing of a gear train. It is assembly structure explanatory drawing of a gear train. It is assembly structure explanatory drawing of the gear train which concerns on 2nd Embodiment. It is explanatory drawing of a prior art.

Explanation of symbols

A: Electrophotographic image forming apparatus Py, Pm, Pc, Pk ... Cartridge 1 ... Apparatus body 3 ... Photosensitive drum 4y, 4m, 4c, 4k ... Transfer roller
13… Charging means
14 ... Developing means
14a: Toner storage
14b ... Toner supply roller
14c ... Developing roller
14d ... Developing blade
15… Cleaning means
15a ... Cleaning blade
23… Developing roller gear (first gear)
24 ... Toner supply roller gear (second gear)
25… Input gear (third gear)
25a… Large diameter gear
25b ... Small diameter gear
25c ... Shaft
26, 27… rotating shaft
28… Mounting shaft
28a ... hole
29… Robot arm

Claims (4)

In the process cartridge that is detachably mounted on the electrophotographic image forming apparatus main body,
An electrophotographic photosensitive drum;
A developing roller for developing the electrostatic latent image formed on the electrophotographic photosensitive drum;
A developer supply roller that contacts the developing roller and supplies the developer to the developing roller;
A first gear for transmitting a driving force to the developing roller;
A second gear for transmitting a driving force to the developer supply roller;
A third gear meshing with the first gear and the second gear;
Have
The third gear is capable of meshing with the first gear and the second gear attached to the respective rotary shafts before being fitted to the attachment shafts during assembly. cartridge.   2. The process cartridge according to claim 1, wherein the first gear, the second gear, and the third gear are helical gears. A process cartridge that is detachably attached to an electrophotographic image forming apparatus main body, the electrophotographic photosensitive drum, a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, A developer supply roller that contacts the developing roller and supplies the developer to the developing roller, a first gear that transmits a driving force to the developing roller, and a driving force that is transmitted to the developer supplying roller In the assembly method of the gear train for attaching the second gear and the third gear meshing with the first gear and the second gear to the attachment shaft,
An assembly method of a gear train, wherein the third gear is engaged with the first gear and the second gear, and then the meshed state is maintained and the gear train is fitted.   The third gear is moved in a direction perpendicular to the axial direction of the mounting shaft, meshed with the first gear and the second gear, and then moved in a direction parallel to the axial direction of the mounting shaft. 4. The gear train assembling method according to claim 3, wherein the gear train is fitted to the third gear.

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