JP4630421B2 - Process cartridge - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic apparatus such as a copying machine, a printer, a recorded image display apparatus, and a facsimile machine that develops an electrostatic latent image formed on an image carrier by an electrophotographic system, an electrostatic recording system, and the like to form a visible image. The present invention relates to a process cartridge and an assembling method thereof in an image forming apparatus.
[0002]
Here, the electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming system. Examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, etc.), a facsimile machine, a word processor, and the like.
[0003]
The process cartridge is a cartridge in which a charging unit, a developing unit or a cleaning unit and an electrophotographic photosensitive drum are integrally formed, and the cartridge can be attached to and detached from the image forming apparatus main body. In addition, at least one of the charging unit, the developing unit, and the cleaning unit and the electrophotographic photosensitive drum are integrally formed into a cartridge that can be attached to and detached from the main body of the image forming apparatus. Further, it means that at least the developing means and the electrophotographic photosensitive drum are integrally formed into a cartridge so as to be detachable from the apparatus main body.
[0004]
[Prior art]
Conventionally, in this type of image forming apparatus, a consumable part such as a photosensitive drum is configured to be replaceable by an operator, and when the life of the image forming apparatus reaches the end of life, the operator replaces it with a new one. An image with stable quality can be obtained.
[0005]
On the other hand, as a developing device, a two-component developing device using a developer in which toner particles and a magnetic carrier are mixed at a certain ratio is used because of a demand for high-quality image quality. In the two-component development method, the magnetic carrier deteriorates due to durability and the quality of the image deteriorates.Therefore, only the developer has been exchanged, but the development device itself has to be replaced to improve the efficiency of maintenance work. It has come to be configured to be replaced as a consumable part.
[0006]
Further, in an image forming apparatus using an electrophotographic image forming process, the electrophotographic photosensitive member and the process means acting on the electrophotographic photosensitive member are integrally formed into a cartridge, and the cartridge can be attached to and detached from the image forming apparatus main body. The process cartridge method 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 operability can be remarkably improved. Therefore, this process cartridge system is widely used in image forming apparatuses.
[0007]
In such a process cartridge, it is necessary to keep a fine gap between the surface of the developing sleeve and the surface of the photosensitive member at a high precision in order to maintain good development characteristics. Therefore, conventionally, a roller having a larger diameter than that of the developing sleeve is provided at both ends in the axial direction of the developing sleeve, and the roller is abutted against the surface of the photosensitive drum so as to maintain a space.
[0008]
However, in the configuration in which the spacer roller is in contact, vibration generated when the developing sleeve is driven is transmitted to the photosensitive drum, which causes various image defects. Therefore, the image forming apparatus main body is provided with a support shaft for pivotally supporting the photosensitive drum, and when the process cartridge is mounted on the apparatus main body, the photosensitive drum and the developing device are respectively positioned with respect to the support shaft so that the high accuracy In order to maintain the interval, a configuration has been adopted (see Japanese Patent Application Laid-Open No. 07-077849).
[0009]
The process cartridge having such a configuration is particularly effective in improving color unevenness and color misregistration for a full-color image forming apparatus that performs color matching using a plurality of process cartridges.
[0010]
[Problems to be solved by the invention]
In the process cartridge having the above-described configuration, the position of the photosensitive drum is not determined when the process cartridge is not attached to the apparatus main body, so that the surface of the photosensitive member may come into contact with the surface of the developing sleeve or the like. In recent years, along with miniaturization of the main body of the apparatus, the process cartridge itself has also been miniaturized, and the photosensitive drum is provided in a very small space. In particular, the assembly of the photosensitive drum so that it does not come into contact with other parts during assembly It has become very difficult.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides an electrophotographic photosensitive drum, a charging member that carries a carrier and is disposed in non-contact with the drum, and a charging member that charges the electrophotographic photosensitive drum, and a carrier And a developing means for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, and having a developing sleeve disposed in a non-contact manner with the drum, and the electrophotographic photosensitive drum A process cartridge that can be attached to and detached from an image forming apparatus main body having a holding shaft into which the electrophotographic photosensitive drum can be inserted and removed.
The support member is provided with a flange holding portion that holds a flange of the electrophotographic photosensitive drum, and a guide portion that is continuous with the flange holding portion and guides attachment / detachment of the electrophotographic photosensitive drum across the flange. The gap between the guide portions is smaller than the outer diameter of the flange, the gap between the flange support portions is larger than the outer diameter of the flange, and the clearance between the flange and the flange support portion is determined by the process cartridge. The image forming apparatus main body is set to be smaller than a clearance between the developing sleeve and the electrophotographic photosensitive drum and smaller than a clearance between the charging sleeve and the electrophotographic photosensitive drum. .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view of a process cartridge 100 according to the present invention.
[0017]
FIG. 6 is a cross-sectional view showing a state in which the process cartridges 100a to 100d according to the present invention are mounted on the image forming apparatus main body. Here, a, b, c, and d represent yellow, magenta, cyan, and black in an image forming apparatus in which known image forming units are arranged in parallel, and may be omitted if not necessary for explanation.
[0018]
The photosensitive drum 12 is rotatably supported on the cartridge frame 13 of the process cartridge 100 by the drum holder 2. When the photosensitive drum 12 is mounted on the apparatus main body, it is rotated clockwise in the drawing by a driving means (not shown). An image is formed in accordance with the image forming process (FIG. 1 shows a state in which the photosensitive drum 12 is detached).
[0019]
Further, a developing device 14 and a charging device 15 are supported and fixed to the cartridge frame 13 in the process cartridge 100. A transfer opening 3 is provided between the developing container 45 of the developing device 14 and the charging container 55 of the charging device 15 downward. The transfer opening 3 is larger in the longitudinal direction than the length of the photosensitive drum 12 to which the front flange 21 and the rear flange 22 are attached. The width of the transfer opening 3 is larger than the diameter of the photosensitive drum 12.
[0020]
A developing sleeve 41 is supported on the developing device 14 so as to be rotatable with respect to the developing container 45, and is disposed at a position that maintains a predetermined clearance of about 300 to 600 μm from the photosensitive drum 12. The developer container 45 is further provided with a screw 42 and a screw 43 so that the developer in which the toner and the magnetic carrier are mixed at a predetermined ratio is stirred and conveyed. Further, the developing blade 44 is fixed so that the clearance with the developing sleeve 41 is about 300 to 500 μm, and regulates the amount of developer coated on the surface of the developing sleeve 41. When the developing sleeve 41 is attached to the apparatus main body, the developing sleeve 41 is rotated clockwise in the drawing by a driving means (not shown) and a high voltage is applied, so that the developer held in the magnet provided therein becomes the developer drum 12. Then, it is conveyed to a nip portion opposite to the surface and subjected to a known development process.
[0021]
A charging sleeve 51 is supported on the charging device 15 so as to be rotatable with respect to the charging container 55, and is disposed at a position that maintains a predetermined clearance of about 400 to 700 μm from the photosensitive drum 12. The charging container 55 contains a charging agent made of a magnetic carrier. The charging blade 54 is fixed so that the clearance with the charging sleeve 51 is about 500 to 700 μm, and regulates the amount of the charging agent coated on the surface of the charging sleeve 51. When the charging sleeve 51 is mounted on the apparatus main body, the charging sleeve 51 is rotated clockwise in the drawing by a driving means (not shown) and a high voltage is applied, so that the charging agent held in the magnet provided therein is the photosensitive drum 12. Then, it is conveyed to a nip portion opposite to the surface and subjected to a known charging process.
[0022]
In FIG. 6, the recording paper 205 that is a recording medium conveyed by the paper supply roller 206 is attracted to the transfer belt 202 and passes through the process cartridges 100 a to 100 d of each color of yellow, magenta, cyan, and black. The yellow station will be described as a representative. Image data 201a which is laser light sent by an exposure device (not shown) forms a latent image on the surface of the photosensitive drum 12, is developed by the developing device 14, and is further transferred to a transfer blade. An image is transferred to the recording paper 205 at 203a. This process is sequentially performed for each color at each station, and the four colors are superimposed to form a full-color toner image. Next, the recording paper 205 passes through the fixing device 207 to fix the toner image, and is discharged to the outside by the paper discharge roller 208.
[0023]
The process cartridges 100a to 100d can be pulled out to the front side of the apparatus main body by the accumulating rails 66 and 67 attached to the right side plate 68 and the left side plate 69 of the support frame 16 (see FIG. 7) that supports the process cartridge. Is possible. When the operator replaces the process cartridge 100, as shown in FIG. 7, the process cartridge 100 is replaced with respect to the support frame 16 with the support frame 16 pulled out to the front side. At this time, the drum shaft 11 that is the holding shaft that holds the electrophotographic photosensitive drum 12 is left on the apparatus main body 5 side, and the photosensitive drum 12 is accommodated by housing the support frame 16 in the apparatus main body. The cartridge frame 13 is positioned on the drum shaft 11 independently. On the other hand, the developing sleeve 41 and the charging sleeve 51 are positioned and supported by a bearing (not shown) with respect to the cartridge frame 13, and as a result of the cartridge frame 13 being positioned on the drum shaft 11, each of the developing sleeve 41 and the charging sleeve 51 is relative to the photosensitive drum 12. The above-described clearance is maintained.
[0024]
FIG. 4 is a cross-sectional view of the process cartridge 100 accommodated in the apparatus main body, and FIG. 5 is a cross-sectional view of the non-mounted state.
[0025]
The drum shaft 11 is rotatably supported by a bearing 74 provided on the rear plate 72 of the apparatus main body and a bearing (not shown) provided on the back side of the apparatus main body with respect to the bearing 74, and is connected to a driving source (not shown).
[0026]
The inner diameters of the front flange 21 and the rear flange 22 of the photosensitive drum 12 are fitted and positioned on the drum shaft 11. The groove 21a provided on the front flange 21 engages with the protrusion 11a provided on the drum shaft 11, and the movement in the rotational direction and the axial direction is restricted. On the other hand, the pressing pin 82 which is a compression coil spring provided inside the knob 83 presses the front flange 21 in the left direction in the drawing to fix the engaging portion with the protruding portion 11a. Here, a slit 11e is provided at the end of the drum shaft 11 across the diameter. A protrusion 21e provided on the inner periphery of the front flange 21 is fitted in the slot 11e. A yoke portion 81e at the tip of the push pin 81 is movably fitted in the slot 11e. The shaft portion 81f of the push pin 81 is inserted into the center hole 11f at the tip of the drum shaft 11 and partially protrudes toward the front side. A parallel pin 81g is driven into the protruding portion of the push pin 81 over the diameter. A washer-like spring seat member 81h is fitted to the shaft portion 81f of the push pin 81 on the front side of the parallel pin 81g. A knob 83 having a hook portion 83e whose tip engages with a groove 11g provided on the outer periphery of the end portion of the drum shaft 11 is provided. The pressing spring 82 is contracted between the bottom 83 f of the hole of the knob 83 and the spring seat member 81 h and inserted into the shaft portion 81 f of the pressing pin 81.
[0027]
Bearings 33 and 34 are fixed to the front side plate 31 and the rear side plate 32 forming the cartridge frame 13 of the process cartridge 100, respectively. The bearings 33 and 34 are fitted to the drum shaft 11, and the cartridge frame 13 is positioned with respect to the apparatus main body. Yes. Further, the pin 35 provided on the front plate 31 is fitted into the hole of the front plate 61 of the support frame 16, and the pin 36 provided on the rear plate 32 of the process cartridge 100 is fitted to the hole of the rear plate 72 of the apparatus main body. A rotation stopper is provided to prevent rotation of the process cartridge 100 around the drum shaft 11. Further, when the process cartridge 100 is urged to the right side in the drawing by an urging means (not shown), the projection 37 provided on the front plate 31 comes into contact with the front plate 61 of the support frame 16 and the thrust of the cartridge frame 13 is thrust. The position is restricted. Thus, the relative thrust positional relationship between the developing device 14 and the charging device 15 with respect to the photosensitive drum 12 is determined at a predetermined position.
[0028]
A pin 65 is provided on the front plate 61 of the support frame 16 and is fitted and positioned in a hole in the front plate 71 of the apparatus main body. On the other hand, a bearing 63 is fixed to the front plate 61 of the support frame 16 and supports the tip of the drum shaft 11. A bearing 64 is fixed to the rear side plate 62 of the support frame 16 and is suspended from the drum shaft 11. The bearing 64 only needs to have a function as a guide when the support frame 16 is pulled out, and the fitting between the bearing 64 and the drum shaft 11 may have a gap enough to cause backlash. In this case, it is preferable to separately fit a positioning pin (not shown) provided on the rear end plate 62 of the support frame 16 to the apparatus main body rear side plate 72.
[0029]
On the other hand, drum holders 1 and 2 are provided on the front side plate 31 and the rear side plate 32 of the process cartridge 100, respectively.
[0030]
Since the drum holders 1 and 2 are different only in whether they are attached to the front side or the rear side, and the configuration is the same, the drum holder 2 will be described here. The photosensitive drum 12 has a front flange 21 and a rear flange 22 fitted and fixed as drum flanges at both ends of an aluminum hollow drum cylinder having a photosensitive layer on the outer periphery.
[0031]
For the sake of explanation, FIG. 2 shows a sectional view in the axial direction of the photosensitive drum 12 with respect to the front view of the drum holder 2. The drum holder 2 has a drum support 2b. When the process cartridge 100 is not attached, the drum holder 2 holds the photosensitive drum 12 with a backlash. That is, the inner diameter φD of the drum support portion 2b is set to be slightly larger than the outer diameter φd of the front end portion 22e of the drum rear flange 22. The amount of play is set smaller than the clearance between the photosensitive drum 12 and the developing sleeve 14e or the photosensitive drum 12 and the charging sleeve 15e when the process cartridge 100 is mounted on the apparatus main body. For example, if the clearance is 500 μm, the play amount is set to 200 μm. Therefore, even when the process cartridge 100 is not attached and the drum shaft 11 is not positioned, the photosensitive drum 11 contacts the developing sleeve 41 or the charging sleeve 51 and damages the surface of the photosensitive member. There is nothing. On the other hand, even if an error occurs in the attachment position of the drum holder 2 due to the presence of play, the drum rear flange 22 and the drum support portion 2b may interfere when the process cartridge 100 is mounted on the apparatus main body. Absent.
[0032]
In the drum holder 2, a drum guide 2a extends in a groove shape in the downward direction in FIG. That is, it extends from the inner side to the outer side in the direction of the transfer opening 3 in a direction perpendicular to the drum shaft 11 as a holding shaft. The groove width W of the drum guide 2a is narrower than the inner diameter φD of the drum support portion 2b, slightly smaller than the outer diameter φd of the front end portion 22e of the drum rear flange 22, or slightly larger. It is in between. Therefore, although the front end portion 22e of the drum rear flange 22 can pass through the drum guide 2a by lightly pushing the drum guide 2a, the movement in the left-right direction in the drawing of FIG. The trajectory along which the body surface moves is limited to the area indicated by broken lines A and B in FIG. Therefore, when the photosensitive drum 12 is assembled, there is no risk that the operator will accidentally contact the surface of the photosensitive member with the components of the developing device 14 or the charging device 15 even though the insertion opening is narrow.
[0033]
Here, the conductive brush 52 is planted with a soft conductive material, and there is no problem even if it comes into contact with the photosensitive drum 12 when it is assembled.
[0034]
On the other hand, as shown in FIG. 3, a drum stopper 4 is attached to the drum holder 2 to hold the incorporated photosensitive drum 12 so as not to come off.
[0035]
FIG. 3 shows a state in which the process cartridge 100 is not mounted and placed on the flat surface 301 outside the apparatus main body. The rear plate 32 of the cartridge frame 13 is provided with legs 32a. On the other hand, the photosensitive drum 12 does not fall below a predetermined height by the drum stopper 4, so that the surface of the photosensitive member contacts the flat surface 301. There is nothing to do. The backlash amount of the front end 22e of the rear flange 22 relative to the drum stopper 4 at the fixed position of the drum stopper 4 is that the inner diameter φD of the drum support 2b has the outer diameter φd of the front end 22e of the rear flange 22. The amount of play is equivalent.
[0036]
The drum stopper 4 shown in FIG. 3 has a yoke shape that is press-fitted between the opposing surfaces of the drum guide 2a of the drum holder 2, and is provided with reverse claws 4e at the front end portions thereof, respectively. The reverse claw 4e is inserted into the groove on the opposite surface of the drum guide 2a, thereby stopping the drum stopper 4 from moving outward.
[0037]
Therefore, the drum stopper 4 is made of resin and is fixed by hooking the reverse claw 4e in the groove provided on the inner surface of the drum guide 2a, so that it can be removed relatively easily by bending the claw tip. It is. Therefore, when it is necessary to replace the photosensitive drum 12 earlier than the life of the process cartridge 100, the drum stopper 4 is removed, the used photosensitive drum 12 is removed, and a new photosensitive drum 12 'is removed. Can also be incorporated along the drum guide 2a.
[0038]
【The invention's effect】
As described above, in the present invention, when the electrophotographic photosensitive drum is assembled to the process cartridge, the electrophotographic photosensitive drum is inserted along the guide member, so that the surface of the photosensitive member is not damaged. An electrophotographic photosensitive drum can be incorporated.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a process cartridge according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a dimensional relationship between a drum guide and a drum flange.
FIG. 3 is a longitudinal sectional view when a process cartridge is placed on a flat surface.
FIG. 4 is a horizontal sectional view showing a state in which a process cartridge is accommodated in the apparatus main body.
FIG. 5 is a horizontal sectional view of a process cartridge that is not attached.
FIG. 6 is a longitudinal sectional view showing a part of the image forming apparatus according to the embodiment of the present invention.
7 is a perspective view of the image forming apparatus in FIG. 6. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Drum holder 2 ... Drum holder 2a ... Drum guide 2b ... Drum support part 3 ... Transfer opening 4 ... Drum stopper 4e ... Reverse claw 5 ... Apparatus main body 11 ... Drum axis | shaft 11a ... Protrusion part 11e ... Slot groove 12, 12 ' ... photosensitive drum 13 ... cartridge frame 14 ... developing device 15 ... charging device 16 ... support frame 21 ... front flange 21a ... groove 22 ... rear flange 22e ... tip 31 ... front plate 32 of cartridge frame ... cartridge frame Rear plate 32a ... Leg 33 ... Bearin 34 ... Bearing 35 ... Pin 37 ... Projection 41 ... Development sleeve 42 ... Screw 43 ... Screw 44 ... Development blade 45 ... Development container 51 ... Charging sleeve 52 ... Conductive brush 54 ... Charging blade 55 ... Charging container 61 ... Front side plate 62 of support frame ... Rear side plate 63 of support frame ... Bearing 64 ... Bearing 6 ... Pin 66 ... Accuride rail 67 ... Accuride rail 68 ... Right side plate 69 ... Left side plate 71 ... Front side plate 72 of the apparatus main body ... Rear side plate 74 of the apparatus main body ... Bearing 81 ... Push pin 81e ... Yoke part 81f ... Shaft part 81g ... Parallel pin 81h ... Spring seat member 82 ... Pressing spring 83 ... Knob 100 ... Process cartridge 100a to 100d ... Process cartridge 201a ... Image data 202 ... Transfer belt 203a ... Transfer blade 205 ... Recording paper 206 ... Feed roller 207 ... Fixing device 208: paper discharge roller 301 ... flat surface

Claims (7)

An electrophotographic photosensitive drum, a charging sleeve that carries a carrier and is disposed in non-contact with the drum , a charging member that charges the electrophotographic photosensitive drum, and a carrier that is disposed in non-contact with the drum. has a developing means for developing the electrostatic latent image formed on the developing sleeve having the electrophotographic photosensitive member drum, a support member for supporting and loosely fitted to said electrophotographic photosensitive drum, the that the In a process cartridge that can be attached to and detached from an image forming apparatus main body having a holding shaft into which an electrophotographic photosensitive drum can be inserted and removed,
Wherein the flange holding portion for holding a flange of said electrophotographic photosensitive drum to the support member, the guide portion for guiding the attachment and detachment of said electrophotographic photosensitive drum across the flange is continuous with the flange holding section provided is the spacing between the guide portion the small fence than the outer diameter of the flange, distance of the flange support portion is larger than the outer diameter of the flange,
The clearance between the flange and the flange support portion is smaller than the clearance between the developing sleeve and the electrophotographic photosensitive drum in a state where the process cartridge is mounted on the image forming apparatus main body, and the charging sleeve and the electrophotographic photosensitive member. A process cartridge which is set to be smaller than a clearance of a body drum .   The guide member extends from the inner side to the outer side in a direction perpendicular to the holding shaft when the process cartridge is mounted on the image forming apparatus main body, and in a direction of a transfer opening provided in the process cartridge. The process cartridge according to claim 1, wherein the process cartridge extends toward the front.   When the electrophotographic photosensitive drum is guided by the guide member, the surface of the photosensitive member provided on the outer periphery of the electrophotographic photosensitive drum is not in contact with the component parts of the process cartridge. The process cartridge according to any one of claims 1 and 2.   The process cartridge according to claim 1, wherein the guide member is provided on a frame of the process cartridge.   5. The process cartridge according to claim 1, wherein the process cartridge includes a retaining member that prevents the electrophotographic photosensitive drum from being detached from the support member. 6.   6. The apparatus according to claim 5, wherein the retaining member holds the surface of the electrophotographic photosensitive drum at a position not in contact with the flat surface when the process cartridge is placed on a flat surface outside the apparatus. Process cartridge.   The process cartridge according to claim 1, wherein the guide portion is provided between the charging member and the developing unit.

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