Abstract:
Provided are a process cartridge and an image forming apparatus having the process cartridge. The process cartridge is constituted as one of at least two types of cartridges, a first cartridge and a second cartridge, and used selectively by being made detachably attachable to a main body of an identical image forming apparatus. The first cartridge includes: a cleaning unit which removes toner remaining on a surface of a medium; a cleaning frame which receives toner recovered by the cleaning unit and has an opening; and a waste toner carrying unit which is provided in the opening and carries the toner in the cleaning frame. The second cartridge includes: a cleaning unit which removes toner remaining on a surface of a medium; a cleaning frame which receives toner recovered by the cleaning unit and has an opening; and a sealing member which seals the opening without the waste toner carrying unit being provided in the opening.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a process cartridge which includes cleaning means for removing toner used for image formation by an electrophotographic process, and to an image forming apparatus.  
           [0003]    2. Related Background Art  
           [0004]    Conventionally, an image forming apparatus using an electrophotographic image forming process adopts a process cartridge system. In the process cartridge system, an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrated into a cartridge which is provided detachably attachable to a main body of the electrophotographic image forming apparatus. According to this process cartridge system, a user of the image forming apparatus can perform maintenance of the apparatus independently without relying upon a serviceman. Thus, operability can be improved remarkably. Such a process cartridge system is widely used in the field of the electrophotographic image forming apparatus.  
           [0005]    In addition, a single process cartridge is often selected for an image forming apparatus, in which case a large cleaning frame is used. Even in the case in which plural kinds of process cartridges can be selected, a cleaning frame is enlarged as an amount of toner is increased. The enlarged cleaning frame is also adopted even if the amount of toner is small.  
           [0006]    However, when it is attempted to increase a capacity for containing toner, not only a toner frame of a large capacity process cartridge but also a cleaning frame has to be enlarged. In accordance with the increase in the size of the cleaning frame, the process cartridge is enlarged. Moreover, a size of an image forming apparatus main body is also increased in order to receive the enlarged process cartridge.  
           [0007]    In addition, in the case in which a cartridge of a small capacity type with a small amount of toner is set for the enlarged cartridge, even if the cleaning frame still has room in its capacity for receiving the toner, the cleaning frame has to be replaced once the toner contained in the toner frame is fully consumed. Thus, for a user who performs a large quantity of image formation, the number of times of cartridge replacement increases. On the other hand, for a user who performs a small quantity of image formation, the large capacity process cartridge is expensive, and the user continues to use one process cartridge for a long period of time. Thus, image degradation or the like is liable to occur.  
         SUMMARY OF THE INVENTION  
         [0008]    It is an object of the present invention to provide a cleaning device of two types, namely, a first cleaning device provided with carrying means for carrying toner to a cleaning frame and a second cleaning device not provided with the carrying means, each being detachably attachable to an identical apparatus, to thereby allow a user to select a cleaning device of a long life or a low price depending on usage.  
           [0009]    In addition, it is another object of the present invention to provide a process cartridge of two types, namely, a first process cartridge using a first cleaning frame provided with carrying means for carrying toner to a cleaning frame and a second process cartridge using a second cleaning frame not provided with the carrying means, each being detachably attachable to an identical apparatus, to thereby allow a user to select a process cartridge of a long life or a low price depending on usage.  
           [0010]    In order to attain the above-mentioned objects, the present invention provides a process cartridge and an image forming apparatus, the process cartridge including: an image bearing member; developing means; a toner frame which contains toner to be supplied to the image bearing member; cleaning means which removes toner remaining on the image bearing member; and a cleaning frame which receives the toner on the image bearing member recovered by the cleaning means, an opening being formed in the cleaning frame. The process cartridge and the image forming apparatus are characterized in that at least one of a first cleaning device, which is provided with waste toner carrying means for carrying the toner of the cleaning frame in the opening and a second cleaning device, which is not provided with the waste toner carrying means but is provided with a sealing member in the opening, is constituted, and the process cartridge provided with the first cleaning device and the process cartridge provided with the second cleaning device are each detachably attachable to a main body of an identical image forming apparatus. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a side view showing an embodiment of an electrophotographic image forming apparatus according to the present invention;  
         [0012]    [0012]FIG. 2 is a side sectional view showing an embodiment of a process cartridge according to the present invention;  
         [0013]    [0013]FIG. 3 is a perspective view showing an embodiment of a cleaning unit according to the present invention;  
         [0014]    [0014]FIG. 4 is a perspective view showing a positional relation among waste toner carrying means, driving means, and a partition member according to the present invention;  
         [0015]    [0015]FIG. 5 is a sectional view showing engagement of a waste toner carrying member and a drive member according to the present invention;  
         [0016]    [0016]FIG. 6 is a side sectional view showing another embodiment of the process cartridge according to the present invention; and  
         [0017]    [0017]FIG. 7 is a longitudinal sectional view showing through-hole sealing which is used in another embodiment of the process cartridge according to the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    First, an embodiment of an image forming apparatus (laser beam printer) to which the present invention is applied will be described with reference to FIG. 1.  
         [0019]    An image forming apparatus A forms an image on a recording medium (e.g., recording paper, an OHP sheet, or cloth) with an electrophotographic image forming process.  
         [0020]    A predetermined voltage is applied to a charging roller  8 , which is in contact with an electrophotographic photosensitive member of a drum shape (hereinafter referred to as “photosensitive drum”)  7 , to uniformly charge the photosensitive drum  7 , and the photosensitive drum  7  is exposed to light using an exposure device  1 , which uses a laser beam source or the like, to form a latent image thereon. Toner contained in a toner frame  11  is deposited on a portion of the photosensitive drum  7 , where the latent image is formed, by developing means  9  to form a toner image.  
         [0021]    On the other hand, in synchronization with the formation of the toner image, a recording medium  2  set in a sheet feeding cassette  3   a  is conveyed by a pickup roller  3   b  and a conveyance guide  3   c.  Timing for appropriately transferring the toner image on the photosensitive drum  7  to the recording medium  2  is taken by registration rollers  3 , and the recording medium  2  is conveyed to a transfer roller  4  at appropriate timing. The toner image formed on the photosensitive drum  7  provided in a process cartridge B is transferred to the recording medium  2  by applying a voltage to the transfer roller  4  serving as transfer means.  
         [0022]    Thereafter, the recording medium  2 , to which the toner image has been transferred, is conveyed to fixing means  5  by a conveyance guide  3   f.  This fixing means  5  has a drive roller  5   c  and a fixing roller  5   b  incorporating a heater  5   a.  The fixing means  5  applies heat and pressure to the recording medium  2 , which passes through the fixing means  5 , to fix the transferred toner image. Then, the recording medium  2  is conveyed by a discharge roller pair  3   i  to be discharged to a discharge tray  6 .  
         [0023]    (First Embodiment)  
         [0024]    Next, the process cartridge B will be described.  
         [0025]    FIGS.  2  to  5  show the process cartridge B including waste toner carrying means for forcibly carrying waste toner, which is removed from the photosensitive drum  7  by a cleaning blade  10   a,  into a cleaning frame  13 .  
         [0026]    A laser beam corresponding to image information from an optical system  1  is irradiated on the photosensitive drum  7  via an exposure opening  1   e  to form a latent image.  
         [0027]    Toner in a toner container  11  is carried to a developing roller  9   a  by rotation of a toner carrying member  9   c.  Then, the developing roller  9   a  incorporating a fixed magnet is rotated, while a toner layer is formed on a surface of the developing roller  9   a.  The toner layer is given a triboelectric charge by a development blade  9   b  that regulates an amount of toner on a circumferential surface of the developing roller  9   a  and gives a triboelectric charge. Such toner is supplied to a development area of the photosensitive drum  7 . Then, the toner is transferred to the photosensitive drum  7  in correspondence with the latent image to thereby visualize the toner image.  
         [0028]    Subsequently, a voltage of a polarity opposite to that of the toner image is applied to the transfer roller  4  to transfer the toner image formed on the photosensitive drum  7  to the recording medium  2 , and then waste toner remaining on the photosensitive drum  7  is removed by the cleaning blade  10   a  which is attached to a support member. Then, the removed waste toner is recovered in the cleaning frame  13 .  
         [0029]    In addition, FIG. 3 shows a perspective view of a cleaning unit C of the process cartridge. The cleaning unit C includes the photosensitive drum  7 , cleaning means  10  including the cleaning blade  10   a,  and the cleaning frame  13  mounted with the cleaning means  10  and the charging roller  8 . The cleaning unit C is rotatably coupled with a development unit D, which holds the toner frame  11  having a toner containing portion for containing toner and developing means such as the developing roller  9   a,  using a coupling member  22 , whereby the process cartridge B is constituted. Further, the process cartridge B is removably mounted to cartridge mounting means provided in a main body of the image forming apparatus.  
         [0030]    Note that a drum shutter member (not shown) is attached to the main body of the image forming apparatus so as to cover the photosensitive drum  7  for the purpose of preventing exposure to light for a long time period, contact with a foreign matter, and the like when the process cartridge B is removed from the main body of the image forming apparatus.  
         [0031]    Next, a detailed structure of a first cleaning unit C of this embodiment will be described.  
         [0032]    [0032]FIG. 4 shows a detail view of waste toner carrying means  16  provided in the cleaning frame  13  of the process cartridge B. FIG. 5 shows an enlarged view of a drive portion of the waste toner carrying means  16 . The cleaning frame  13  has a through hole  24 , which serves as an opening for setting the waste toner carrying means  16 , in a longitudinal direction thereof. The waste toner carrying means  16  includes a waste toner carrying member  16   b  and a drive member  16   a  serving as a driving force receiving member for driving the waste toner carrying member  16   b.  This waste toner carrying member  16   b  rotates to forcibly carry waste toner to the cleaning frame  13 . In addition, the driving force of the waste toner carrying member  16   b  is transmitted from a drum gear crimped to the photosensitive drum  7  while being decelerated via idler gears  16   c,    16   d,  and  16   e.  The drive member  16   a  is attached to an end face in a longitudinal direction of the process cartridge B while being pierced through the through-hole  24  provided on a side of the cleaning frame  13  from an outside to an inside of the cleaning frame  13 . Further, a seal member  25  such as an oil seal is provided in the through-hole  24 .  
         [0033]    Note that a partition plate  17  acting as eaves is attached above the waste toner carrying member  16   b  so as to prevent the waste toner carried by the waste toner carrying member  16   b  from falling on the waste toner carrying member  16   b  to cause a drive failure due to adhesion of toner.  
         [0034]    Next, an operation for carrying waste toner into the cleaning frame  13  with the waste toner carrying means  16  will be described in detail. After image formation, waste toner remaining on the photosensitive drum  7  is removed by the cleaning blade  10   a  which is in abutment against the photosensitive drum  7 . The removed waste toner is gradually accumulated in the cleaning frame  13  but is liable to be recovered in the vicinity of a lower part of the cleaning blade  10   a.  Thus, the waste toner recovered in the vicinity of the lower part of the cleaning blade  10   a  is forcibly carried in a downstream direction of the cleaning frame  13  by the rotation of the waste toner carrying member  16   b.  The waste toner forcibly carried into the cleaning frame  13  is deposited in a vertical downward direction in the cleaning frame  13 . However, since the waste toner is in a state in which a bulk density thereof is increased, an amount of the waste toner to be received in the cleaning frame  13  can be made larger than an amount of waste toner to be received in a cleaning frame of the same volume.  
         [0035]    A portion of the waste toner forcibly carried into the cleaning frame  13  is carried in a direction of the waste toner carrying means  16  again by a circulating flow generated in the cleaning frame  13  by the toner carrying operation. When the circulated waste toner is deposited on the waste toner carrying member  16   b,  a driving force of the waste toner carrying member  16   b  is increased to cause an increase in load with respect to a drive source (not shown). Thus, in order to prevent the circulated waste toner from depositing on the waste toner carrying member  16   b,  the partition member  17  is provided above the waste toner carrying member  16   b  such that the circulated waste toner is deposited on the downstream side in the toner carrying direction.  
         [0036]    In addition, a drive source for giving a driving force to the drive member  16   a  from the main body of the image forming apparatus is the same as the drive source giving a driving force to the photosensitive drum  7 . When the waste toner removed by the cleaning blade  10   a  is carried into the cleaning frame  13 , fluctuation in torque may occur with respect to the drive source, causing driving fluctuation with respect to the photosensitive drum  7 . Thus, an image failure due to the fluctuation in torque can be prevented by adopting a torque limiter or the like such that a driving torque transmitted from the drive source to the photosensitive drum  7  is always fixed at the time of image formation.  
         [0037]    With the above-mentioned structure, by using the waste toner carrying member  1   b,  it is possible to increase a bulk density of the waste toner in the cleaning frame  13  and forcibly carry the waste toner to the downstream side of the cleaning frame, thereby allowing much waste toner to be received in the cleaning frame compared with a frame body of the same volume. Further, since the partition plate  17  is used, the waste toner received in the cleaning frame  13  never prevents the drive of the waste toner carrying member.  
         [0038]    Note that the waste toner is carried to the downstream side of the cleaning frame by rotating the waste toner carrying member used for the cleaning unit C used in the embodiment during the image forming operation. However, the same effect can be obtained even if the waste toner is carried before image formation, during an intermittent operation of the image formation, after the image formation, or according to an instruction from a user.  
         [0039]    Alternatively, in the case in which drive sources giving driving forces to the photosensitive drum  7  and the drive member  16   a  are provided separately, or in the case in which a mechanism for mechanically switching a drive mechanism of the same drive source is provided, an effect is achieved regarding the problem of the fluctuation in torque with respect to the photosensitive drum.  
         [0040]    (Second Embodiment)  
         [0041]    [0041]FIGS. 6 and 7 show a process cartridge of a low price and low capacity type using a second cleaning unit C′ which does not adopt the waste toner carrying member  16  used in the cleaning unit C described in the first embodiment. Note that the same components as those in the first embodiment are denoted by the same reference symbols.  
         [0042]    The cleaning unit C′ includes the photosensitive drum  7 , the cleaning frame  13 , the cleaning means  10  including the cleaning blade  10   a . The cleaning unit C′ is rotatably coupled with the development unit D using the coupling member  22 , whereby the process cartridge B is constituted.  
         [0043]    In the cleaning unit C′, the through-hole  24  serving as an opening for mounting a waste toner carrying member is unnecessary because the waste toner carrying member  16  is not adopted. Thus, a toner sealing member  23  is pressed in or welded to the through-hole  24  provided in the cleaning frame  13  to seal the through-hole  24  such that waste toner does not leak therefrom.  
         [0044]    Instead of forming the toner sealing member  23  with the same material as the cleaning frame, it is possible to form the toner sealing member  23  with an elastic body in order to make welding work easy.  
         [0045]    In addition, the toner sealing member  23  is formed so as to be recessed toward the inside of the cleaning frame  13  from the external circumferential surface thereof, and the drive member  16   a  is received in the central part of the toner sealing member  23 . Consequently, it becomes possible to provide a process cartridge which, even in the case in which the drive member  16   a  is provided in the main body of the image forming apparatus, compatibility is improved in mounting and dismounting the cleaning unit C′.  
         [0046]    Note that the toner frame  11  described in this embodiment is the same as the toner frame  11  described in the first embodiment. However, since the process cartridge is of a low price and low capacity type, an amount of toner contained in the toner frame  11  is smaller than that in the toner frame  1  of the first embodiment.  
         [0047]    Thus, the process cartridge using the cleaning unit C′, in which the waste toner carrying member of the cleaning unit C is sealed, has a simplified cleaning unit structure. Therefore, it is possible to provide a process cartridge of a low price.  
         [0048]    In addition, since the cleaning frames used in the cleaning units C and C′ are the same, sizes of the process cartridge provided with the cleaning unit C and the process cartridge provided with the cleaning unit C′ are the same whether the capacity for receiving toner is large or small. Thus, the process cartridges are detachably attachable to the main body of an identical image forming apparatus, respectively. Accordingly, it is sufficient to select one of the process cartridges depending on usage.  
         [0049]    In the first and second embodiments, waste toner on the surface of the photosensitive drum  7  is removed. However, the same effect can be obtained even if a cleaning device, which removes waste toner remaining on a surface of not only the photosensitive drum but also a sheet conveyor belt, an intermediate transfer member, or the like, is used as a cartridge.  
         [0050]    In addition, the same effect can be obtained even if a cartridge is separately provided from a developer or separately provided from an image bearing member and a developer.