Patent Publication Number: US-9891576-B2

Title: Feeding device, cleaning device, process cartridge and image forming apparatus

Description:
FIELD OF THE INVENTION AND RELATED ART 
     The present invention relates to a feeding device, a cleaning device, a process cartridge, and an image forming apparatus. 
     Here, a process cartridge is a cartridge equipped with at least an image bearing member such as an electrophotographic photosensitive drum, or a cartridge equipped with both an image bearing member and processing means for processing the image bearing member. These types of cartridge are removably installable in the main assembly of an image forming apparatus. 
     An example of cartridge which can be listed as a process cartridge is a cartridge which integrally holds an electrophotographic photosensitive drum, and at least one of the abovementioned processing means, more specifically, a developing means, a charging means, and a cleaning means. Further, an electrophotographic image forming apparatus is an apparatus which forms an image on a recording medium with the use of an electrophotographic image forming method. 
     Examples of electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (LED printer, laser beam printer, and the like), an electrophotographic facsimile machine, an electrophotographic word processing machine, etc. 
     An image forming apparatus  100  such as an electrophotographic printer which uses an electrophotographic process forms an image on a recording medium through the following steps. That is, it uniformly charges a photosensitive drum, which is an image bearing member, and forms a latent image on the photosensitive drum by selectively exposing numerous points of the uniformly charged peripheral surface of the photosensitive drum. Then, it develops the latent image into a visible image (which hereafter may be referred to as toner image) with the use of toner (developing agent: developer), and transfers the image formed of developer (toner image) onto the recording medium. Further, it fixes the developer image to the recording medium by applying heat and pressure to the developer image on the recording medium. 
     Various processing means for an image forming apparatus such as those mentioned above have to be maintained. However, if an electrophotographic image forming apparatus is designed so that it employs a process cartridge, the apparatus can be maintained by a user himself or herself. Thus, an image forming apparatus designed to employ a process cartridge is significantly superior in terms of operational efficiency. Thus, a process cartridge is widely in use in the field of an electrophotographic image forming apparatus. 
     In the image forming operation of an image forming apparatus which uses an electrophotographic process, a certain amount of developer (toner) fails to be transferred from a photosensitive drum onto a recording medium, and remains on the photosensitive drum. Then, it is removed from the photosensitive drum by a cleaning member, and is stored as waste toner in the waste toner storage section of a cleaning unit. Then, the waste toner is conveyed by a feeding mechanism from the waste toner storage section to a replaceable waste toner box, which is externally attached to the cleaning unit (Japanese Laid-open Patent Applications Nos. 2006-139084, and 2012-128250). 
     SUMMARY OF THE INVENTION 
     However, an image forming apparatus such as those described above has an issue regarding how to ensure that the developer (waste toner) removed by a cleaning member is reliably guided to a feeding device. Thus, it has been desired that an image forming apparatus is improved to deal with this issue. 
     Thus, the primary object of the present invention is to provide a feeding device which is superior to any conventional feeding device in terms of reliability and efficiency with which the developer removed by a cleaning member is conveyed to a feeding device, and also, to provide a cleaning device, a process cartridge, and an image forming apparatus which employ such a feeding device. 
     According to an aspect of the present invention, there is provided a feeding device for feeding a developer, said feeding device comprising a cleaning member contacted to an image bearing member configured to carry a developer image to remove a developer from said image bearing member; an accommodating portion configured to accommodate the developer removed by said cleaning member; a feeding member configured to feed the developer from said accommodating portion; a sheet contacted to said image bearing member; and a guiding portion forming a part of a wall surface of said accommodating portion at a position in a side of said sheet with respect to a line connecting a rotation center of said image bearing member and a rotation center of said feeding member, as seen in a direction of an axial direction of said image bearing member; wherein said guiding portion extends in a acute angle range formed between a first line which extends vertically through the rotation center of the feeding member and a second line extending in a direction of an angle of rest of the developer through the rotation center of said feeding member, said guiding portion having such a shape so as to approach a linear shape as a distance of said feeding member decreases. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of the waste toner storage section of the feeding device in the first embodiment of the present invention, which is for describing the structure of the waste toner storage section. 
         FIG. 2  is a schematic sectional view of the electrophotographic color image forming apparatus, in the first embodiment, equipped with the feeding device which is in accordance with the present invention. 
         FIG. 3  is an external perspective view of the process cartridge, in the first embodiment, equipped with the feeding device which is in accordance with the present invention. 
         FIG. 4  is a schematic sectional view of the process cartridge, in the first embodiment, equipped with the feeding device which is in accordance with the present invention. 
         FIG. 5  is a perspective view of the waste toner feeding section of the feeding device in the first embodiment, which is for describing the structure of the waste toner feeding section. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Embodiment 1 
     Hereinafter, an image forming apparatus and a process cartridge, which are in accordance with the present invention, are described with reference to appended drawings. 
     (Image Forming Apparatus) 
     To begin with, referring to  FIG. 2 , an electrophotographic color image forming apparatus equipped with a feeding device which is in accordance with the present invention is described about its overall structure. Referring to  FIG. 2 , which is a schematic sectional view of the apparatus, the image forming apparatus  100  has multiple image forming sections, more specifically, the first, second, third, and fourth image forming sections SY, SM, SC and SK for forming yellow (Y), magenta (M), cyan (C) and black (K) images, respectively. In this embodiment, the first to fourth image forming sections SY, SM, SC and SK are aligned in a single line in the direction which is intersectional to the vertical direction (indicated by arrow marks Y 1  and Y 2 ) in such an attitude that their lengthwise direction becomes intersectional to the vertical direction. 
     By the way, in this embodiment, process cartridges  7  ( 7 Y,  7 M,  7 C and  7 K) are practically the same in structure and operation, although they are different in the color of the image they form. Hereafter, therefore, suffixes Y, M, C and K are eliminated so that the four process cartridges  7  can be described together, unless they need to be differentiated. That is, in this embodiment, the image forming apparatus  100  has multiple image bearing members, more specifically, four photosensitive drums  1 , which are aligned in a single line in the direction which is intersectional to the vertical direction, in such an attitude that their lengthwise direction become intersectional to the vertical direction. Each photosensitive drum  1  has also a charge roller  2  and a scanner unit  3  (exposing device), which are disposed in the adjacencies of the peripheral surface of the photosensitive drum  1  as an image bearing member for bearing a developer image. 
     Here, the charge roller  2  is a charging means for uniformly charging the peripheral surface of the photosensitive drum  1 . The scanner unit  3  (exposing device) is an exposing means for forming an electrostatic image (electrostatic latent image) on the peripheral surface of the photosensitive drum  1  by projecting a beam of laser light upon the uniformly charged area of the peripheral surface of the photosensitive drum  1  while modulating the beam according to the information about the image to be formed. The process cartridge  7  is also provided with a developing device  4  (which hereafter will be referred to as development unit) and a cleaning blade  6  as a cleaning member (cleaning means), which also are disposed in the adjacencies of the peripheral surface of the photosensitive drum  1 . 
     Further, the image forming apparatus  100  is provided with an intermediary transfer belt  5 , which is an intermediary transferring member for transferring the toner image on the photosensitive drum  1  onto a sheet  12  of recording medium. The intermediary transfer belt  5  is disposed so that it opposes four photosensitive drums  1 . 
     By the way, in this embodiment, the development unit  4  uses nonmagnetic single-component developer, that is, pure toner, as development agent. Also in this embodiment, the development unit  4  develops the electrostatic latent image on the photosensitive drum  1  by placing the development roller  17 , which is a developer bearing member, in contact with the photosensitive drum  1  as a developer bearing member (contact development). 
     In this embodiment, the photosensitive drum  1 , and the processing means, more specifically, the charge roller  2 , are integrally attached to the development unit frame  14 , forming thereby a cleaning unit  13 . By the way, referential codes  61  and  86  stand for a waste toner feeding passage, and a waste toner box, respectively, which are described later in detail. 
     Further, referring to  FIG. 4 , in this embodiment, the development unit  4  and cleaning unit  13  are integrated as the process cartridge  7 , which can be installed into, or uninstalled from, the image forming apparatus  100  by way of unshown installation guide, positioning member, etc., with which the main assembly of the image forming apparatus  100  is provided. 
     Also in this embodiment, the four process cartridges  7  for the aforementioned four colors, one for one, are the same in shape, and contain yellow (Y), magenta (M), cyan (C) and black (K) toners, one for one. 
     The intermediary transfer belt  5  is disposed in contact with the photosensitive drum  1 . It circularly moves in the direction indicated by an arrow mark B. It is suspended by multiple supporting members (driver roller  51 , belt backing roller  52 , idler roller  53 ), in such a manner that it bridges adjacent two supporting members. There are disposed in parallel four primary transfer rollers  8  as primary transferring means, on the inward side of the loop which the intermediary transfer belt  5  forms. The four primary transfer rollers  8  are disposed in a manner to oppose the four photosensitive drums  1 , one for one. There is also disposed the secondary transfer roller  9  as the secondary transferring means, on the outward side of the loop which the intermediary transfer belt  5  forms. The secondary transfer roller  9  is disposed in a manner to oppose the belt backing roller  52 . 
     In an image forming operation, first, the peripheral surface of the photosensitive drum  1  is uniformly charged by the charge roller  2 . Then, the charged peripheral surface of the photosensitive drum  1  is scanned by (exposed to) a beam of laser light emitted from the scanner unit  3  while being modulated according to the information of the image to be formed. Consequently, an electrostatic latent image, which reflects the information of the image to be formed, is effected on the photosensitive drum  1 . Then, the electrostatic latent image on the photosensitive drum  1  is developed by the development unit  4  into a toner image. The four toner images formed on the four photosensitive drums  1 , one for one, are transferred (primary transfer) onto the intermediary transfer belt  5  by the function of the primary transfer rollers  8 . 
     In an operation for forming a full-color image, for example, the above-described process is sequentially carried out by the four process cartridges  7 . Thus, four monochromatic toner images, different in color, are sequentially transferred in layers onto the intermediary transfer belt  5 . Meanwhile, a sheet  12  of recording medium is conveyed to the secondary transferring section in synchronism with the movement of the four toner images on the intermediary transfer belt  5 . Then, while the sheet  12  and the toner images, different in color, on the intermediary transfer belt  5  are conveyed through the secondary transferring section, the four toner images are transferred together (secondary transfer) onto the sheet  12  by the function of the secondary transfer roller  9 . 
     After the transfer of the toner images onto the sheet  12  of recording medium, the sheet  12  is conveyed to a fixing device  10  as a fixing means, in which heat and pressure are applied to the sheet  12  and the toner images thereon, whereby the toner images are fixed to the sheet  12 . By the way, the primary transfer residual toner, which is the toner remaining on the peripheral surface of the photosensitive drum  1  after the primary transfer, is removed by the cleaning blade  6 , and is recovered as waste toner. 
     The secondary transfer residual toner, which is the toner remaining on the intermediary transfer belt  5  after the secondary transfer process, is removed by an intermediary transfer belt cleaning device  11 . 
     By the way, the image forming apparatus  100  is enabled to form a monochromatic or multi-color image, with the use of only a specific image forming section or two or more (not all of four) of its image forming sections. 
     (Process Cartridge) 
     Next, referring to  FIGS. 3 and 4 , the process cartridge  7  which is installable (insertable) into the image forming apparatus  100  in this embodiment is described about its overall structure.  FIG. 3  is an external perspective view of the process cartridge  7 . First, referring to  FIG. 3 , hereafter, the direction which is parallel to the rotational axis of the photosensitive drum  1  is referred to as direction Z (indicated by arrow marks Z 1  or Z 2 ). Next, referring to  FIG. 2 , the horizontal direction (indicated by arrow mark X 1  or X 2 ), and vertical direction (indicated by arrow mark Y 1  or Y 2 ), are referred to as directions X and Y, respectively.  FIG. 4  is a schematic sectional view of the process cartridge  7  as seen from the direction Z, when the process cartridge  7  is in the image forming apparatus  100  and the photosensitive drum  1  and development roller  17  are in contact with each other. 
     Referring to  FIG. 4 , the development unit  4  has a development unit frame  18  which supports various internal members of the development unit  4 . The development unit  4  is provided with the development roller  17 , as a developer bearing member, which rotates in the direction indicated by the arrow mark D in the drawing (counterclockwise direction), while remaining in contact with the photosensitive drum  1 . The development roller  17  is rotatably supported by the development unit frame  18  by its ends in terms of its lengthwise direction (parallel to its rotational axis), with the placement of a pair of development roller bearings  19  ( 19 R and  19 L), one for one, between the development roller  17  and the development unit frame  18 . In this embodiment, the development roller bearings  19  are attached to the front and rear walls of the development unit frame  18 , one for one. 
     Further, the development unit  4  has a developer storage chamber  18   a  (toner storage chamber), and a development chamber  18   b  in which the development roller  17  is disposed. There are disposed in the development chamber  18   b , a toner supply roller  20  and a development blade  21 . The toner supply roller  20  is a developer supplying member, and rotates in the direction indicated by an arrow mark E while remaining in contact with the development roller  17 . The development blade  21  is a developer regulating member for controlling the toner layer on the development roller  17  in thickness. The development blade  21  is attached to a development blade holding member  22 , to which it is welded with the use of YAG laser, for example. 
     Further, there is in the toner storage chamber  18   a  of the development unit frame  18 , a stirring member  23  for feeding the toner in the toner storage chamber  18   a  to the toner supply roller  20  while stirring the toner. The development unit  4  is in connection to the cleaning unit  13  in such a manner that it is rotatable about a shaft  24  ( 24 R and  24 L) fitted in the holes  19 Ra and  19 La with which the bearings  19 R and  19 L, respectively, are provided. Further, the development unit  4  is kept under the pressure generated by a pair of tension springs  25 . Thus, as the process cartridge  7  begins to be used for an image forming operation, the development unit  4  rotates in the direction indicated by an arrow mark F about the shafts  25 , causing thereby the development roller  17  to come into contact with the photosensitive drum  1 . 
     The cleaning unit  13  has a cleaning unit frame  14  as a frame for supporting various internal members of the cleaning unit  13 . The cleaning unit  13  has the cleaning blade  6 , a waste toner storing section  14   a  for storing the recovered transfer residual toner, and a waste toner feeding member  27 . It is the cleaning unit frame  14  that the photosensitive drum  1  is attached so that the photosensitive drum  1  is rotatable in the direction indicated by an arrow mark A in  FIG. 4 . Also attached to the cleaning unit frame  14  is a pair of charge roller bearings  15  in such a manner that the rotational axis of the charge roller  2  becomes parallel to the rotational axis of the photosensitive drum  1 . 
     Here, the charge roller  2  is attached to the cleaning unit frame  14  so that they are allowed to move in the direction indicated by an arrow mark C in  FIG. 4 . The rotational axle  2   a  of the charge roller  2  is rotationally borne by the pair of charge roller bearings  15 , which are under the pressure generated by a pair of charge roller pressing springs  16 , as pressure applying means, in the direction to press the charge roller  2  toward the photosensitive drum  1 . 
     The cleaning unit frame  14  is provided with the cleaning blade  6  as a cleaning means for removing the toner remaining on the peripheral surface of the photosensitive drum  1  (image bearing member). The cleaning blade  6  integrally comprises an elastic section  6   a  which is placed in contact with the peripheral surface of the photosensitive drum  1  to remove the toner on the photosensitive drum  1 , and a metallic section  6   b  for supporting the elastic section  6   a . The metallic section  6   b  is formed of a sheet of metallic substance. In this embodiment, the supporting section  6   b  is fixed to the cleaning unit frame  14  with the use of small screws. 
     Here, a vector which is parallel to a tangential line to the peripheral surface of the photosensitive drum  1 , and opposite in direction from the direction indicated by the arrow mark A which shows the rotational direction of the photosensitive drum  1 , is referred to as a tangential vector. Thus, the photosensitive drum contacting section  6   c  of the cleaning blade  6 , that is, the tip of the elastic section  6   a , is in contact with the photosensitive drum  1 , in an area where the tangential vector has an upward component in terms of the vertical direction. 
     (Waste Toner Feeding) 
     Next, referring to  FIGS. 1 and 5 , the cleaning unit  13  is described about its waste toner feeding structure in the cleaning unit frame  14 .  FIG. 1  shows in detail the adjacencies of the photosensitive drum contacting section  6   c  of the cleaning blade  6  shown in  FIG. 4 . It is a sectional view of the waste toner feeding section of the cleaning unit  13 .  FIG. 5  is a partially broken perspective view of one of the lengthwise end portions of the process cartridge  7 . It is for describing the structure of the lengthwise end portion. 
     1) Overall Structure of Waste Toner Storage Section  14   a    
     In the image forming apparatus, the developer (toner) remaining on the peripheral surface of the photosensitive drum  1  after the primary transfer is removed from the peripheral surface of the photosensitive drum  1  by the cleaning blade  6  (made up of elastic section  6   a , and supporting section  6   b  which supports elastic section  6   a ), as a cleaning means. That is, the elastic section  6   a  of the cleaning blade  6  removes from the peripheral surface of the photosensitive drum  1 , the developer (toner) remaining on the peripheral surface of the photosensitive drum  1 , in the area in which the photosensitive drum contacting section  6   c  of the cleaning blade  6  contacts the photosensitive drum  1 . 
     Next, referring to  FIG. 1 , the cleaning unit frame  14  is provided with the waste toner storage section  14   a  for storing the waste toner removed from the peripheral surface of the photosensitive drum  1  by the elastic section  6   a  of the cleaning blade  6 . Thus, the waste toner removed by the photosensitive drum contacting section  6   c  is cumulatively stored in the waste toner storage section  14   a.    
     Further, there is provided a waste toner feeding member  27  in the waste toner storage section  14   a . Next, referring to  FIG. 5 , the waste toner feeding member  27  has a rotational shaft  27   a  and a spiral feeding blade  27   b . It is supported by the waste toner feeding member supporting section  14   g , with which the waste toner storage section  14   a  is provided, so that it can be rotated about the rotational axis  27   c  ( FIG. 1 ) of the waste toner feeding member  27 . 
     Further, the waste toner storage section  14   a  is provided with a waste toner sealing member  31 , which is in the form of a piece of sheet and is placed in contact with the photosensitive drum  1  to keep the waste toner storage section  14   a  sealed so that the waste toner in the waste toner storage section  14   a  does not leak. 
     The waste toner storage section  14   a  has a wall section  14   b  ( FIG. 1 ) for preventing the waste toner from leaking from the cleaning unit frame  14 , a waste toner seal supporting section  14   c  by which a waste toner sealing member  31  is supported, and a waste toner guiding section  14   d  which guides the waste toner. The waste toner guiding section  14   d  is has an inward surface  14   d   0  which is a part of the inward surface of the waste toner storage section  14   a  and serves as a waste toner guiding section. Moreover, the waste toner storage section  14   a  has a waste toner feeding passage  14   f  ( FIGS. 1 and 5 ) in which the waste toner feeding member  27  is disposed. 
     As described above, in this embodiment, the waste toner sealing member  31  is adhered to the waste toner sealing member supporting section  14   c  with the use of a piece of two-sided adhesive tape. Next, referring to  FIG. 1 , by the way, a referential code  31   a  stands for the area of contact between the waste toner sealing member supporting member  31  and photosensitive drum  1 , and a referential code  31   b  stands for the connective section of the waste toner sealing member  31 , by which the waste toner sealing member  31  is connected to the waste toner sealing member supporting section  14   c.    
     2) Angle of Inward Surface  14   d   0  of Waste Toner Guiding Section  14   d    
     In this embodiment, the inward surface  14   d   0  of the waste toner guiding section  14   d  is provided with such an angle that is described next. First, referring to  FIG. 1 , a straight line which coincides with the rotational axis  27   c  of the waste toner feeding member  27 , and is parallel to the direction Y, or the vertical direction, is referred to as the first straight line L 1 . Further, a straight line which coincides with the rotational axis  27   c  of the waste toner feeding member  27 , and is parallel to the angle of repose of the waste toner is referred to as the second straight line L 2 . Here, “angle of repose” means the angle of the lateral surface of a body of toner, relative to a horizontally placed piece of flat plate, at the moment when a body, which toner forms as it is made to vertically fall down onto a horizontally placed piece of flat plate, begins to naturally collapse. 
     Referring to  FIG. 1 , in this embodiment, the inward surface  14   d   0  of the waste toner guiding section  14   d  has such an angle that its angle relative to the horizontal surface is no less than the angle of the second straight line L 2 , and no more than the angle of the first straight line L 1 . That is, the inward surface  14   d   0  extends in the direction which is between the first straight line L 1  and second straight line L 2  which form an acute angle (θ). Since the inward surface  14   d   0  of the waste toner guiding section  14   d  is given an angle which is greater than the angle of repose of the developer (toner), it is possible to ensure that the waste toner is reliably guided to the waste toner feeding member  27 . 
     Further, in this embodiment, the inward surface  14   d   0  of the waste toner guiding section  14   d  extends straight in the direction indicated by an arrow mark L 4 , which indicates also the direction in which the waste toner moves from the waste toner sealing member supporting section  14   c  to the waste toner feeding member  27 . That is, the cleaning unit frame  14  is structured to make the inward surface  14   d   0  of the waste toner guiding section  14   d  tilted so that the closer it is to the waste toner feeding member  27 , the narrower the distance between the inward surface  14   d   0  and a straight line L 0  (straight line which coincides with rotational axis  1   a  of photosensitive drum  1  and rotational axis  27   c  of waste toner feeding member  27 ). In other words, the closer it is to the waste toner feeding member  27 , the narrower the waste toner storage space of the waste toner storage section  14   a . Therefore, it is ensured that the waste toner is reliably guided to the waste toner feeding member  27 . 
     3) Position of Bottom End of Inward Surface  14   d   0  of Waste Toner Guiding Section  14   d  in Terms of Vertical Direction 
     In this embodiment, the cleaning blade  6  is disposed so that the area of contact (photosensitive drum contacting section  6   e  of the cleaning blade  6 ) between the elastic section  6   a  and photosensitive drum  1  is positioned higher than the bottom end  14   e  of the inward surface  14   d   0  of the waste toner guiding section  14   d  in terms of the vertical direction. Therefore, it is prevented that the developer (waste toner) remains in the adjacencies of the photosensitive drum contacting section  6   c , and fails to be conveyed. 
     4) Position of Area of Contact  6   c  Between Elastic Section  6   a  and Photosensitive Drum  1   
     It is desired that the development unit  4  is structured so that the area of contact  6   c  between the elastic section  6   a  and photosensitive drum  1  is positioned within the space between the above-described the first and second straight lines L 1  and L 2  which form an acute angle (θ). In this embodiment, the development unit  4  is structured so that the area of contact  6   c  is positioned on the opposite side of the straight line L 0  (which coincides with rotational axis  1   a  of photosensitive drum  1 , and rotational axis  27   c  of waste toner feeding member  27 ), from the waste toner sealing member  31 . 
     5) Movement of Waste Toner in Waste Toner Storage Section  14   a    
     As described above, the waste toner removed by the photosensitive drum contacting section  6   c  is accumulated in the waste toner storage section  14   a . As a printing operation is continued, the photosensitive drum  1  is repeatedly scraped by the cleaning blade  6 , whereby the waste toner is scraped away from the peripheral surface of the photosensitive drum  1 , and accumulates in the waste toner storage section  14   a . Then, the waste toner having accumulated in the waste toner storage section  14   a  is conveyed by the pressure from the additional (new supply of) waste toner from the area of contact  6   c , in the direction indicated by an arrow mark L 3  in  FIG. 1 . As the waste toner in the waste toner storage section  14   a  is conveyed in the direction indicated by the arrow mark L 3 , it comes into contact with the inward surface  14   d   0  of the waste toner guiding section  14   d , whereby it is guided in the direction indicated by an arrow mark L 4  in  FIG. 1 . 
     6) Waste Toner Feeding by Waste Toner Feeding Member  27   
     As the waste toner is guided in the above-described direction indicated by the arrow mark L 4 , it comes to the largest diameter section  27   b   1  of the spiral feeding blade  27   b , which is greater in diameter than the shaft portion  27   a  of the waste toner feeding member  27 , and is conveyed by the waste toner feeding member  27  which has the shaft portion  27   a  and spiral feeding blade  27   b . Then, as the waste toner feeding member  27  continues to rotate, the waste toner is conveyed in the direction indicated by an arrow mark Z 1  ( FIGS. 3 and 5 ) by the spiral feeding blade  27   b.    
     As the waste toner is conveyed in the direction indicated by the arrow mark Z 1  ( FIGS. 3 and 5 ), it falls in the direction indicated by an arrow mark Y 2 , through a through hole  45 , with which one of the lengthwise end portions of the process cartridge is provided, and which connects the waste toner feeding passage  14   f  and the feeding passage  61  of the apparatus main assembly. Then, as the waste toner lands in the feeding passage  61  of the apparatus main assembly, it is conveyed in the direction indicated by an arrow mark  61 Y in  FIG. 5 , by the waste toner feeding member  62  of the apparatus main assembly, which is provided in the feeding passage  61 , and ends up being discharged into the waste toner box  86  ( FIG. 2 ) of the apparatus main assembly. 
     Effects of this Embodiment 
     As described above, the development unit  4  is structured so that the inward surface  14   d   0  of the waste toner guiding section  14   d  is positioned in the space between the first and second straight lines L 1  and L 2 , and extends in the direction indicated by the arrow mark L 4 , in which the waste toner moves from the waste toner sealing member supporting section  14   c  to the waste toner feeding member  27 . Thus, it is ensured that the waste toner is reliably guided to the waste toner feeding member  27 . Therefore, it is ensured that the waste toner is desirably conveyed in the waste toner storage section  14   a , in the direction indicated by the arrow mark Z 1  ( FIGS. 3 and 5 ). 
     Since it is ensured that the waste toner is reliably conveyed in the direction indicated by the arrow mark Z 1  ( FIGS. 3 and 5 ), it is possible to prevent the waste toner removed from the peripheral surface of the photosensitive drum  1 , in the area of contact  6   c  between the cleaning blade  6  and photosensitive drum  1 , from accumulating by an excessive amount in the adjacencies of the area of contact  6   c . Therefore, it is possible to prevent the waste toner storage section  14   a  from being punctured by the waste toner. By preventing the waste toner storage section  14   a  from being punctured by the waste toner, it is possible to prevent the waste toner feeding member  27  from excessively increasing in the amount of torque necessary to rotate the waste toner feeding member  27 , and also, to prevent the waste toner from leaking from the development unit  4  through the area of contact between the waste toner sealing member  31  and photosensitive drum  1 . 
     Modifications of First Embodiment 
     In the foregoing, one of the preferred embodiments of the present invention was described. However, the above-described embodiment is not intended to limit the present invention in scope. That is, the embodiment is variously modifiable within the scope of the present invention. By the way, the preceding embodiment is not intended to limit the image forming apparatus and its developing device in terms of the function, material, and shape of their structural members, and also, the positional relationship among the structural members, unless specifically noted. 
     (Modification 1) 
     In the above-described embodiment, the feeding device which includes the waste toner feeding section  27  for feeding the developer was disposed within the process cartridge which is insertable in the main assembly of the image forming apparatus. However, the present invention is applicable also to an image forming apparatus, which does not employ a process cartridge, and the feeding device of which is within the main assembly of the apparatus. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2015-037861 filed on Feb. 27, 2015, which is hereby incorporated by reference herein in its entirety.