JP2009199017A - Process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process cartridge that has a transfer residue toner conveyance path, in which any trouble is not caused with the lapse of time, and to provide an image forming apparatus having this process cartridge. <P>SOLUTION: The process cartridge 2 used for the image forming apparatus includes: an image carrier 20 on which toner is supplied from a developing roller 252 and a toner image is formed, after an electrostatic latent image is formed; a cleaning blade 21 that removes toner remaining on the surface of the image carrier 20 after the toner image is transferred to an intermediate transfer belt 4; a toner recovery chamber that accommodates the toner removed by the cleaning blade 21; toner conveying means 23, 24, 26, and 27 that convey the toner from the cleaning blade 21 to the toner recovery chamber. In the process cartridge 2, power is not transmitted to the toner conveying means when an image carrier 20 is rotated in a direction reverse to that assigned for image formation. Specifically, one-way clutch 28 is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a process cartridge used for a copying machine, a printer, a FAX, and the like and an image forming apparatus including the process cartridge.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer, and a facsimile machine, a process cartridge including an image carrier and an image carrier cleaning device may be detachably provided. When the process cartridge is used, the image carrier and the image carrier cleaning device can be exchanged at the same time when the toner is exchanged. In addition, since the process cartridge composed of a plurality of parts is replaced, it is not necessary to perform the replacement work every time the component parts are consumed, so that labor saving of the consumable parts replacement work can be achieved. Further, since the transfer residual toner scraped off by the image carrier cleaning device can be transported to the toner collection chamber in the process cartridge by the toner transporting means in the process cartridge, toner scattering is prevented. Conventionally, various mechanisms have been proposed and put to practical use in order to transport the transfer residual toner to the toner recovery chamber. For example, Patent Document 1 proposes a configuration in which transfer residual toner is conveyed to a toner collection chamber by a toner conveyance belt.

Incidentally, a cleaning blade is generally used in an image carrier cleaning device incorporated in a process cartridge. When the cleaning blade is used, paper dust is sandwiched between the image carrier and the edge of the cleaning blade over time. If paper dust is sandwiched between the image carrier and the edge of the cleaning blade and the paper dust remains, image defects such as black bands and black stripes occur. Therefore, after forming a predetermined number of images, the image carrier is rotated in a direction opposite to the rotation direction at the time of image formation to remove paper dust sandwiched between the image carrier and the edge of the cleaning blade. ing.
In order to reversely rotate the image carrier, it is necessary to reversely rotate a motor that is a drive source of the image forming apparatus. Therefore, when the image carrier is reversely rotated, a driving force is obtained from the motor such as a roller or a gear. The rotating body also rotates in the reverse direction. For this reason, the transfer residual toner in the middle of conveyance toward the toner recovery chamber flows backward in the transfer residual toner conveyance path, and troubles such as toner clogging occur in the transfer residual toner conveyance path.

Japanese Patent No. 3281595

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a process cartridge including a transfer residual toner conveyance path that does not cause problems over time and an image forming apparatus including the process cartridge. It is said.

The features of the present invention, which is a means for solving the above problems, are listed below.
The process cartridge of the present invention includes an image carrier on which a toner image is formed by supplying toner from a developing roller after an electrostatic latent image is formed, and an image carrier after a toner image is transferred to a transfer medium An image carrier cleaning device that removes toner remaining on the surface of the image carrier, a toner recovery chamber that stores toner removed by the image carrier cleaning device, and a toner transport that transports toner from the image carrier cleaning device to the toner recovery chamber A process cartridge for use in an image forming apparatus, wherein power is not transmitted to the toner conveying means when the image carrier is rotated in a direction opposite to that during image formation. To do.
Further, the process cartridge of the present invention is further provided with a one-way clutch so that power is not transmitted to the toner conveying means when the image carrier is rotated in a direction opposite to that at the time of image formation. And
Further, in the process cartridge of the present invention, the toner conveying means further includes a toner conveying belt stretched around a plurality of shafts including a driving shaft, and the image carrier is driven by power from the image forming apparatus main body. And the drive shaft is rotated by power from the image carrier.

In the process cartridge of the present invention, the toner conveying means further includes a toner collecting screw for conveying the toner delivered from the toner conveying belt, and the toner collecting screw is rotated by power from the image carrier. It is the structure which carries out.
Further, the process cartridge of the present invention further has a function in which a screw is formed on the drive shaft to transmit power to the toner transport belt and to transport toner passed from the toner transport belt. It is characterized by being.
In the process cartridge of the present invention, the toner conveying means further includes a toner conveying member for conveying the toner from the image carrier to the toner conveying belt and delivering the toner to the toner conveying belt. Is configured to rotate by power from the image carrier.
An image forming apparatus according to the present invention includes any one of the process cartridges described above.

  In the process cartridge and the image forming apparatus as means for solving the above problems, it is possible to provide a process cartridge including a transfer residual toner conveyance path that does not cause a problem with time and an image forming apparatus including the process cartridge.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

FIG. 1 shows an embodiment of an image forming apparatus provided with a process cartridge of the present invention. In this image forming apparatus, four process cartridges 2 (Y, M, C, K) are aligned and arranged at substantially the center of the apparatus casing. Here, Y, M, C, and K mean yellow, magenta, cyan, and black, respectively. Above the process cartridge 2, an exposure device 3 for forming an electrostatic latent image on the image carrier 20 (Y, M, C, K) is provided. Below the process cartridge 2, an intermediate transfer belt 4 as a transfer medium wound around two support rollers is provided along the horizontal direction. The intermediate transfer belt 4 is sandwiched between the primary transfer roller 5 (Y, M, C, K) and the image carrier 20 (Y, M, C, K). When an electric field is formed between the image carrier 20 and the intermediate transfer belt 4 by applying a high voltage to the primary transfer roller 5, the charged toner image on the surface of the image carrier is transferred to the intermediate transfer belt 4.
The image carrier 20 (Y, M, C, K) is black (K), cyan (C), magenta (M), and yellow (Y) in this order toward the downstream side in the endless rotation direction of the intermediate transfer belt 4. These four colors are superposed in order to form a four-color toner image. A secondary transfer roller 6 and an intermediate transfer member cleaning device 7 are provided on the right side of the intermediate transfer belt 4 in the drawing. Below the intermediate transfer belt 4, a paper feed cassette 8 that accommodates a recording medium P such as paper or a resin sheet is provided. The recording medium P is sent out from the paper feed cassette 8 by the paper feed roller 9 at a timing, and the four-color toner image is transferred from the intermediate transfer belt 4 to the recording medium P by the secondary transfer roller 6. During this transfer, a high voltage is applied to the secondary transfer roller 6, an electric field is formed between the secondary transfer roller 6 and the intermediate transfer belt 4, and the charged four-color toner image is on the recording medium P side. The four-color toner image is transferred to the recording medium P.

The recording medium P fed by the paper feed roller 9 passes between the intermediate transfer belt 4 and the secondary transfer roller 6 and is guided to the fixing device 10. Then, the four-color toner image is thermally fixed on the recording medium P in the fixing device 10. After the thermal fixing, the recording medium P is sent to the paper discharge roller 11, and the paper discharge roller 11 discharges the recording medium P onto the tray.
On the other hand, untransferred toner remaining on the intermediate transfer belt 4 without being transferred from the intermediate transfer belt 4 to the recording medium P is scraped off by the cleaning blade 71 of the intermediate transfer body cleaning device 7 and collected in the toner collection chamber. . The cleaned intermediate transfer belt 4 prepares for the transfer of the next toner image.

[First Embodiment]
FIG. 2 shows a first embodiment of the process cartridge of the present invention. As shown in the figure, an image carrier 20 is provided on the lower end side of the process cartridge 2 so as to face the intermediate transfer belt 4. The intermediate transfer belt 4 rotates clockwise in the drawing at the time of image formation. In the present specification, the clockwise rotation of the image carrier 20 is defined as a positive rotation. In addition, various members that are connected to the image carrier 20 and rotate in synchronization with the image carrier 20 rotate in the forward direction when the image carrier 20 rotates forward. In FIG. 2, the image carrier 20 has a drum shape, but may have an endless belt shape. A cleaning blade 21 is provided around the image carrier 20 as an image carrier cleaning device that removes toner remaining on the surface of the image carrier 20 after the toner image is transferred to the intermediate transfer belt 4. A charging roller 22 that uniformly charges the image carrier 20 is provided downstream of the cleaning blade 21 in the image carrier rotation direction.
Further, below the cleaning blade 21, a toner conveying member 23 for conveying the transfer residual toner scraped off by the cleaning blade 21 along the horizontal direction is provided. The transfer residual toner conveyed in the horizontal direction by the toner conveying member 23 is pumped up by the toner conveying belt 24, conveyed toward the toner collecting chamber S1 of the developing device 25, and accommodated in the toner collecting chamber S1. In the present embodiment, the toner conveying means includes a toner conveying member 23, a toner conveying belt 24, and a toner collecting screw 26 (shown in FIG. 3).

The partition member 251 serving as an element forming the toner recovery chamber S1 is made of a flexible material such as a film. An unused toner chamber S <b> 2 is formed below the partition member 251. Since a material having flexibility is used for the partition member 251, the toner recovery chamber S <b> 1 expands due to the influence of gravity as the transfer residual toner is accumulated. At this time, air flows into the toner recovery chamber S1 through the air circulation hole 25a.
That is, at the start of use of the process cartridge 2, the partition member 251 is bent upward as shown in the drawing, so that the volume of the toner collection chamber S1 is smaller than that when the partition member 251 is not bent. The volume of the unused toner chamber S2 increases. In this way, when the partition member 251 is bent upward, more unused toner can be stored in the unused toner chamber S2 in advance. As the unused toner is used for development, the amount of toner in the unused toner chamber S2 decreases. Then, since the upper space where there is no toner becomes negative pressure, the partition member 251 continuously changes so as to bend downward. As a result, the volume of the toner recovery chamber S1 increases, and a larger amount of untransferred toner can be accommodated in the toner recovery chamber S1. That is, the space in the developing device 25 can be used efficiently, and the life of the process cartridge 2 can be extended significantly without increasing the size of the process cartridge 2.

Further, the developing device 25 is arranged in contact with or in proximity to the image carrier 20 and supplies a developing roller 252 that supplies toner to the image carrier 20, and an agitator for stirring unused toner in the unused toner chamber S2. 253, a toner supply roller 254 for supplying toner to the developing roller 252, and a developing blade 255 for regulating the toner layer thickness on the developing roller 252 to a predetermined thickness.
In the present embodiment, the developing device 25 is included in the process cartridge 2, but may not be included in the process cartridge as a separate body. In other words, as long as the process cartridge 2 of the present invention includes the image carrier 20, the cleaning blade 21, the toner recovery chamber S1, and the toner conveying means including the toner conveying belt 24, the types of components are included. Is not particularly limited.

  Next, the electrophotographic image forming process will be described. In FIG. 2, the image carrier 20 is rotated forward by a driving device installed in the image forming apparatus main body, and the photosensitive layer on the surface thereof is charged to a uniform high potential by the charging roller 22. The uniformly charged photosensitive layer is exposed by a light beam L having an optical image from an exposure apparatus. By this exposure, an electrostatic latent image composed of a low potential portion where the potential is attenuated and a high potential portion by initialization is formed on the photosensitive layer. Next, when the low potential portion (or high potential portion) of the electrostatic latent image reaches a position where the image carrier 20 and the developing roller 252 face each other, the toner is imaged from the developing roller 252 having a thin toner layer formed on the surface. The toner image is formed on the surface of the image carrier 20. As the image carrier 20 rotates, the toner image is transferred to the intermediate transfer belt 4. At this time, transfer residual toner that has not been transferred to the intermediate transfer belt 4 is present on the image carrier 20, but this transfer residual toner is removed from the image carrier 20 by the cleaning blade 21. A charging roller 22 is provided downstream of the cleaning blade 21 in the rotation direction of the image carrier. Further, a neutralizing device (not shown) is provided downstream of the charging roller 22 in the rotation direction of the image carrier. ing. In the static eliminator, residual charges on the surface of the image carrier 20 are removed.

  By the way, when the image forming operation as described above is repeated many times, when the recording medium P is paper, paper dust adheres to the intermediate transfer belt 4 and the edge of the cleaning blade 71 of the intermediate transfer member cleaning device 7. Paper dust is deposited on the edge of the cleaning cartridge 21 and the cleaning blade 21 of the process cartridge 2, and the paper is deposited on the contact portion between the intermediate transfer belt 4 and the cleaning blade 71 and the contact portion between the image carrier 20 and the cleaning blade 21. A phenomenon occurs in which powder is caught. Since the size of the paper dust is larger than the toner particle size, the image carrier 20 and the cleaning are disposed in the vicinity of the paper dust sandwiched between the tips of the cleaning blades 21 and 71 and the image carrier 20 or the intermediate transfer belt 4. The contact state with the blades 21 and 71 becomes uneven, and a cleaning failure occurs. In order to prevent this phenomenon, the image carrier 20 and the intermediate transfer belt 4 rotate in the opposite direction to that during image formation by rotating the motor, which is the drive source of the image forming apparatus, in reverse for every preset number of printed sheets. Thus, the sandwiched paper powder is discharged from the edge portion, and good cleaning properties can be ensured.

FIG. 3 is a perspective view of the process cartridge 2 shown in FIG. FIG. 3 shows a transfer residual toner conveyance path until the transfer residual toner is conveyed to the toner recovery chamber S1 (shown in FIG. 2). As shown in the figure, a gear flange 20 a is fixedly provided at one end of the image carrier 20. Then, power is transmitted from a motor that is a drive source of the image forming apparatus main body, and it rotates forward in the direction of the arrow in the drawing.
The transfer residual toner scraped off from the image carrier 20 by the cleaning blade 21 as the image carrier 20 rotates is moved along the horizontal direction to the other end side of the image carrier 20 along the arrow A direction by the toner conveying member 23. Be transported. The toner conveying member 23 is provided to convey the untransferred toner to the toner conveying belt 24 and pass it to the toner conveying belt 24. A flange portion 23a is formed on the other end side of the toner conveying member 23, but the flange portion 23a and the gear flange 20a are not connected. In the present embodiment, the power of the rotating image carrier 20 is transmitted to the toner transport member 23 via the gear train 29, the one-way clutch 28, the drive shaft 27, and the toner transport belt 24.

  The untransferred toner transported to the toner transport belt 24 by the toner transport member 23 is pumped upward (in the direction of arrow B) by the toner transport belt 24. The transfer residual toner pumped up to the upper end side of the process cartridge 2 is transferred to the drive shaft 27 and the toner recovery screw 26. A screw 27 a is formed on the drive shaft 27, and the drive shaft 27 has a function of conveying the toner passed from the toner conveyance belt 24. Then, the transfer residual toner is conveyed along the direction of arrow C to the toner recovery chamber S1 (shown in FIG. 2) by the drive shaft 27 on which the screw 27a is formed and the toner recovery screw 26, and is accommodated in the toner recovery chamber S1. . The toner conveying belt 24 is stretched around two axes of a toner conveying member 23 and a driving shaft 27 arranged in parallel with the toner recovery screw 26, and the toner conveying belt 24 is endless by the rotational driving of the driving shaft 27. Rotate. Since the screw 27a is formed on the drive shaft 27, if the screw 27a is formed from the vicinity of the toner conveying belt 24 to the vicinity of the toner recovery chamber S1, it is not necessary to provide the toner recovery screw 26.

  In general, including the present embodiment, the drive source of the image carrier 20 and the drive shaft 27 is common. Therefore, when the image carrier 20 is rotated in reverse in order to remove the paper dust at the tip of the cleaning blade 21, the driving force is also transmitted to the drive shaft 27. However, in the present embodiment, a one-way clutch is provided between the drive shaft 27 and the gear train 29 so that power is not transmitted to the toner conveying means when the image carrier 20 is rotated in the opposite direction to that during image formation. 28 is provided. Therefore, even if the image carrier 20 is rotated, power is not transmitted to the drive shaft 27 when the image carrier 20 is rotated in the reverse direction. Accordingly, the transfer residual toner being conveyed to the toner recovery chamber S1 (shown in FIG. 2) does not flow backward by the drive shaft 27 on which the screw 27a is formed. The toner collecting screw 26 is configured to be driven separately from the image carrier 20. Although the drive source of the toner recovery screw 26 and the image carrier 20 can be the same, in this case, in order to prevent the backflow of the transfer residual toner, it is preferable to provide a one-way clutch on the toner recovery screw 26 as well. .

  When the process cartridge having the above-described transfer residual toner conveyance path is used and the one-way clutch 28 is not installed, a reverse rotation operation is performed. As a result, the toner delivery unit between the toner conveyance member 23 and the toner conveyance belt 24, and the toner conveyance belt In the transfer residual toner transfer portion between the toner collecting screw 26 and the toner collecting screw 26, toner clogging due to the backflow toner occurred, and abnormal noise from the process cartridge, gear skipping, and the like were confirmed. On the other hand, in the process cartridge 2 incorporating the one-way clutch 28 of the present invention, toner clogging due to the backflow of the transfer residual toner did not occur.

  In the process cartridge of the first embodiment described above, the one-way clutch 28 is provided so that power is not transmitted to the toner conveying means when the image carrier 20 is rotated in the direction opposite to that during image formation. 27, the toner conveying belt 24 and the toner conveying member 23 are not rotated in reverse. Accordingly, it is possible to form a transfer residual toner conveyance path in which toner clogging does not occur over time. Further, the image forming apparatus including the process cartridge 2 can maintain a good cleaning property for a long time.

[Second Embodiment]
FIG. 4 is an explanatory view showing a second embodiment of the process cartridge of the present invention. FIG. 5 shows the meshing form of each gear. As shown in the drawing, the gear 252 a of the developing roller 252 meshes with the gear flange 20 a of the image carrier 20. Further, the gear 252a meshes with the gear 252a, and the gear 29a meshes with the gear 29a. When the gear 29b rotates forward, the one-way clutch 28 fitted in the gear 29b also rotates, and the shaft 28a inserted through the one-way clutch 28 rotates. On the other hand, when the gear 29b rotates in the reverse direction, the shaft 28a does not rotate.
Along with the rotation of the shaft 28a, a gear 29c having the shaft 28a as a rotation shaft rotates. When the gear 29c rotates, the outer gear 26a1 and the inner gear 26a2 rotate because the outer gear 26a1 of the toner recovery screw 26 meshes with the gear 29c. When the outer gear 26a1 and the inner gear 26a2 rotate, the toner recovery screw 26 also rotates, and the gear 27b and the drive shaft 27 that mesh with the inner gear 26a2 rotate. Accordingly, when the image carrier 20 rotates in the forward direction, the drive shaft 27 and the toner recovery screw 26 rotate in synchronization with the rotation. On the other hand, when the image carrier 20 rotates in the reverse direction, the drive shaft 27 and the toner recovery screw 26 do not rotate.
The position where the one-way clutch mechanism is provided is not particularly limited as long as it is between the gear flange 20a of the image carrier 20 and the outer gear 26a1. In short, it may be configured such that power is not transmitted to the drive shaft 27 and the toner recovery screw 26 when the image carrier 20 is rotated in the reverse direction.

The process cartridge according to the second embodiment has the same effects as the process cartridge 2 according to the first embodiment.
Further, in the process cartridge of the second embodiment, the toner recovery screw 26 and the drive shaft 27 are the same drive source, and the reverse rotation of the toner recovery screw 26 and the drive shaft 27 is prevented by one one-way clutch 28. The mechanism is simple.
In general, when a one-way clutch is provided in a driving mechanism for driving an image carrier or the like, play of the gear is large. Therefore, if the reverse rotation is performed, banding corresponding to the frequency of the gear pitch occurs and the image quality is deteriorated. Therefore, the configuration provided between the gear trains for the purpose of preventing only the toner conveying unit from rotating in reverse as in the present embodiment is particularly effective from the viewpoint of preventing the deterioration of the print image quality. In the present embodiment, the one-way clutch 28 is fitted into the gear 29b, and the one-way clutch 28 is provided on the gear on the downstream side in the power transmission direction as much as possible.

FIG. 1 is an explanatory view showing an embodiment of an image forming apparatus provided with the process cartridge of the present invention. FIG. 2 is an explanatory view showing a first embodiment of the process cartridge of the present invention. FIG. 3 is a perspective view of the process cartridge of FIG. FIG. 4 is an explanatory view showing a second embodiment of the process cartridge of the present invention. FIG. 5 is an explanatory diagram showing details of the power transmission mechanism of the process cartridge of FIG.

Explanation of symbols

2 Process Cartridge 20 Image Carrier 20a Gear Flange 21 Cleaning Blade 22 Charging Roller 23 Toner Conveying Member 23a Flange 24 Toner Conveying Belt 25 Developing Device 25a Air Flow Hole 251 Partition Member 252 Developing Roller 252a Gear 253 Agitator 254 Toner Supply Roller 255 Developing Blade 26 Toner recovery screw 26a1 Outer gear 26a2 Inner gear 27 Drive shaft 27a Screw 27b Gear 28 One-way clutch 28a Shaft 29 Gear train 29a, 29b, 29c Gear 3 Exposure device 4 Intermediate transfer belt 5 Primary transfer roller 6 Secondary transfer roller 7 Intermediate Transfer body cleaning device 71 Cleaning blade 8 Paper feed cassette 9 Paper feed roller 10 Fixing device 11 Paper discharge roller L Light beam P Recording medium S1 Toner rotation Room S2 unused toner chamber

Claims (7)

An image carrier on which a toner image is formed by supplying toner from a developing roller after an electrostatic latent image is formed;
An image carrier cleaning device for removing toner remaining on the surface of the image carrier after the toner image is transferred to the transfer medium;
A toner recovery chamber for storing toner removed by the image carrier cleaning device;
Toner conveying means for conveying toner from the image carrier cleaning device to the toner recovery chamber;
In a process cartridge used in an image forming apparatus having
A process cartridge characterized in that power is not transmitted to the toner conveying means when the image carrier is rotated in a direction opposite to that during image formation. The process cartridge according to claim 1,
A process cartridge, characterized in that a one-way clutch is provided so that power is not transmitted to the toner conveying means when the image carrier is rotated in a direction opposite to that during image formation. The process cartridge according to claim 1 or 2,
The toner conveying means includes a toner conveying belt stretched around a plurality of shafts including a drive shaft,
The image carrier is rotated by power from the image forming apparatus main body,
The process cartridge, wherein the drive shaft is configured to rotate by power from an image carrier. The process cartridge according to claim 3,
The toner conveying means has a toner collecting screw for conveying toner delivered from the toner conveying belt;
The process cartridge, wherein the toner recovery screw is rotated by power from an image carrier. The process cartridge according to claim 3,
A process cartridge, wherein a screw is formed on the drive shaft to transmit power to the toner transport belt and to transport toner passed from the toner transport belt. The process cartridge according to claim 3,
The toner conveying means includes a toner conveying member for conveying toner from an image carrier to the toner conveying belt and passing the toner to the toner conveying belt;
The process cartridge, wherein the toner conveying member is rotated by power from an image carrier. An image forming apparatus comprising the process cartridge according to claim 1.

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