Patent Publication Number: US-11650535-B2

Title: Toner collection device and image forming apparatus therewith

Description:
INCORPORATION BY REFERENCE 
     This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2021-040402 filed on Mar. 12, 2021, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The present disclosure relates to a toner collection device and an image forming apparatus provided with a toner collection device. 
     Conventionally common image forming apparatuses using an electrophotographic process (copiers, printers, facsimiles, etc.) typically use a process involving visualizing an electrostatic latent image formed on an image carrying member such as a photosensitive drum using toner (powdery developer) in a developing device, transferring the toner image to a recording medium directly or via an intermediate transfer member, and then fixing the image. Such image forming apparatuses incorporate a cleaning device for removing unused toner left on the surface of the image carrying member or the intermediate transfer member. The unused toner removed by the cleaning device is conveyed into a toner collection container to be stored there as waste toner. The toner collection container is replaceable and is replaced by an operator (a user, a maintenance worker, etc.). 
     The cleaning device includes a waste toner conveying unit for conveying waste toner. The waste toner conveying unit includes a toner conveying passage and a conveying screw for conveying toner. In a downstream-side end part of the toner conveying passage, an opening is formed. The opening and a toner collection port formed in a top part of the toner collection container are arranged over each other. Waste toner in the toner conveying passage is conveyed to the opening by the conveying screw and is fed through the opening and the toner collection port into the toner collection container. The step of removing unused toner on the image carrying member is performed continuously while the image forming apparatus is forming images. During the step of removing unused toner, waste toner is constantly fed into the toner collection container. 
     Also known are toner collection devices provided with a detection sensor that can sense the amount of toner in the toner collection container. 
     Such a detection sensor is arranged around the toner collection port so as to sense a state of a sufficient amount waste toner being stored in the toner collection container. The detection sensor is an optical sensor such as a photointerruptor and includes a light emitting portion that emits light and a light receiving portion that receives the light emitted from the light emitting portion. The light emitting portion and the light receiving portion are arranged so as to sandwich, at a predetermined position in the toner collection container in the up-down direction, the toner collection container from both sides in its width direction (the direction perpendicular to the up-down direction). The detection sensor is connected to a control portion provided in an appropriate part of the image forming apparatus. The detection sensor senses the presence or absence of waste toner between the light emitting portion and the light receiving portion (the predetermined position mentioned above) and transmits the sensing result to the control portion. 
     When waste toner accumulates gradually in the toner collection container and reaches the predetermined position mentioned above, the light emitted from the light emitting portion is intercepted by waste toner and the light reception condition in the light receiving portion changes. When the sensing result is transmitted to the control portion, the control portion displays an indication about the time for replacement of the toner collection container on an operation screen or the like of the image forming apparatus. 
     SUMMARY 
     According to one aspect of the present disclosure, a toner collection device includes a toner collection container, a toner conveying passage, a side wall, a recessed sensing portion, and a detection sensor. The toner collection container has a toner collection port formed in it through which waste toner on a toner carrying member is fed in. The toner collection container can store in it the waste toner fed in through the toner collection port. The toner conveying passage includes a first inclined portion that is provided right under the toner collection port and that is inclined downward leftward in the left-right direction perpendicular to the up-down direction and a second inclined portion that is connected to a bottom end part of the first inclined portion and that is inclined downward frontward in the front-rear direction perpendicular to the up-down and left-right directions such that an end part of the second inclined portion on the left side makes contact with the inner wall face of the toner collection container on the left side. The toner conveying passage conveys the waste toner fed in through the toner collection port toward a bottom portion of the toner collection container along the first and second inclined portions. The side wall rises from an end part of the second inclined portion on the right side. The recessed sensing portion has an opening between a top end part of the side wall and the inner wall face of the toner collection container. The recessed sensing portion communicates with the second inclined portion on the rear side. The detection sensor senses the presence or absence of waste toner at a predetermined position in the recessed sensing portion in the up-down direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic sectional view of an image forming apparatus mounted with a toner collection device according to the present disclosure; 
         FIG.  2    is a perspective view of the toner collection device and a waste toner conveying unit according to the present disclosure; 
         FIG.  3    is a sectional front view (a sectional view cut along section line A-A′ in  FIG.  1   ) showing the internal structure of the toner collection device according to the present disclosure; 
         FIG.  4    is a sectional view of the toner collection device according to the present disclosure shown in  FIG.  3    cut along section line B-B′; 
         FIG.  5    is a sectional view of the toner collection device shown in  FIG.  3    cut along section line C-C′; 
         FIG.  6    is a sectional view of the toner collection container cut along section line D-D′ in  FIG.  5   ; 
         FIG.  7    is a sectional view of the toner collection container showing a state where waste toner is stored in it; 
         FIG.  8    is a sectional view of the toner collection container shown in  FIG.  7    cut along section line E-E′; and 
         FIG.  9    is a sectional view of the toner collection container showing a state where waste toner is stored in a recessed sensing portion. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, with reference to the accompanying drawings, embodiments of the present disclosure will be described.  FIG.  1    is a schematic sectional view of an image forming apparatus  100  mounted with a toner collection device  21  according to the present disclosure. In the main body of the image forming apparatus  100  (here, a color printer), four image forming portions, Pa, Pb, Pc and Pd are arranged in this order from the upstream side in the conveying direction (from the right side in  FIG.  1   ). The image forming portions Pa to Pd correspond to images of four different colors (magenta, cyan, yellow, and black) and sequentially form images of the different colors through the steps of charging, exposure to light, development, and transfer. 
     In the image forming portions Pa to Pd, photosensitive drums (toner image carrying members)  1   a  to  1   d  are rotatably arranged which carry visible images (toner images) of the different colors. An intermediate transfer belt  8  is provided adjacent to the image forming portions Pa to Pd. A secondary transfer roller  9  is provided adjacent to the intermediate transfer belt  8 . 
     The intermediate transfer belt  8  is formed of a sheet of dielectric resin and is an endless belt made by superposing and bonding together the opposite ends of the sheet or a seamless belt (belt with no seam). The intermediate transfer belt  8  is stretched around a driven roller  10 , a driving roller  11 , and a tension roller  20  to rotate together with the driving roller  11  as this rotates. 
     The secondary transfer roller  9  faces the driving roller  11  across the intermediate transfer belt  8 . A nip (secondary transfer nip) is formed between the intermediate transfer belt  8  and the secondary transfer roller  9 . On the downstream side of the secondary transfer roller  9  in the rotation direction of the intermediate transfer belt  8 , a blade-form belt cleaner  19  is arranged for removing toner left on the surface of the intermediate transfer belt  8 . 
     In a lower part of the image forming apparatus  100 , a sheet cassette  16  is provided. Sheets S are stored in the sheet cassette  16 . The sheets S in the sheet cassette  16  are conveyed to the secondary transfer nip via a sheet feeding roller  12   a  and a registration roller  12   b.    
     Next, a description will be given of the image forming portions Pa to Pd. Provided around and under the photosensitive drums  1   a  to  1   d  are chargers  2   a  to  2   d , an exposure unit  4 , developing units  3   a  to  3   d , and cleaning portions  5   a  to  5   d.    
     The chargers  2   a  to  2   d  electrically charge the photosensitive drums  1   a  to  1   d . The exposure unit  4  exposes the photosensitive drums  1   a  to  1   d  to light carrying image information. The developing units  3   a  to  3   d  form toner images on the photosensitive drums  1   a  to  1   d . The developing units  3   a  to  3   d  include developing rollers (developer carrying members) which are arranged opposite the photosensitive drums  1   a  to  1   d . The developing units  3   a  to  3   d  include toner cartridges (not shown) loaded with predetermined amounts of toner of magenta, cyan, yellow, and black respectively. The cleaning portions  5   a  to  5   d  remove developer (toner) left on the photosensitive drums  1   a  to  1   d.    
     When a user enters an instruction to start image formation, first, the chargers  2   a  to  2   d  electrostatically charge the surfaces of the photosensitive drums  1   a  to  1   d  uniformly. Next, the exposure unit  4  irradiates the photosensitive drums  1   a  to  1   d  with light to form on them electrostatic latent images reflecting the image data. Next, the toner in the toner cartridge is fed by the developing rollers in the developing units  3   a  to  3   d  to the photosensitive drums  1   a  to  1   d  respectively, and electrostatically attaches to them. In this way, toner images corresponding to the electrostatic latent images are formed. 
     Then, an electric field with a predetermined transfer voltage is applied to the intermediate transfer belt  8 , and the toner images on the photosensitive drums  1   a  to  1   d  are primarily transferred to the intermediate transfer belt  8  by primary transfer rollers  6   a  to  6   d . The toner images of four colors to be primarily transferred are formed in a predetermined positional relationship with each other that is prescribed for formation of a predetermined full-color image. Then, in preparation for the subsequent formation of new electrostatic latent images, toner left on the surface of the photosensitive drums  1   a  to  1   d  are removed by the cleaning portions  5   a  to  5   d.    
     As the intermediate transfer belt  8  starts to rotate clockwise, a sheet S is conveyed from the registration roller  12   b  to the secondary transfer nip with predetermined timing. Then, a full-color image is secondarily transferred from the intermediate transfer belt  8  to the surface of the sheet S by the secondary transfer roller  9 . The sheet S to which the toner images have been transferred is conveyed to a fixing portion  7 . 
     The sheet S conveyed to the fixing portion  7  is heated and pressed as it passes through a nip (fixing nip) of the fixing roller  13 . Then, the secondarily-transferred toner images are fixed on the surface of the sheet S, and thus the predetermined full-color image is formed on it. The sheet S on which the full-color image has been formed has its conveyance direction switched by a branch portion  14  branching into a plurality of directions. When an image is formed only on one side of the sheet S, the sheet S is directly discharged onto a discharge tray  17  by a discharge roller  15 . 
     In contrast, when images are formed on both sides of the sheet S, part of the sheet S that has passed through the fixing portion  7  is momentarily stuck out of the apparatus through the discharge roller  15 . In that state, by rotating the discharge roller  15  backward, the sheet S is directed, at the branch portion  14 , to a sheet conveying passage  18  with the image face (the face on which the image is formed) reversed, and is conveyed again to the secondary transfer nip. Then, the next image formed on the intermediate transfer belt  8  is transferred by the secondary transfer roller  9  to the face of the sheet S on which no image has yet been formed. The sheet S is then conveyed to the fixing portion  7  to have the toner images fixed on it, and is discharged to the discharge tray  17 . 
     In a lower part of the apparatus, a toner collection device  21  is arranged. The toner collection device  21  collects and stores waste toner scraped off at the cleaning portions  5   a  to  5   d  and the belt cleaner  19 . The toner collection device  21  is coupled to the cleaning portions  5   a  to  5   d  and the belt cleaner  19  via a waste toner conveying unit  25  (waste toner conveying portion). 
     The waste toner conveying unit  25  includes a conveying screw  24  inside and has a discharge port  32  formed in it (see  FIG.  2   ). The conveying screw  24  conveys waste toner. The discharge port  32  is located in a downstream-side end part of the waste toner conveying unit  25  in the waste toner conveying direction. The waste toner conveying unit  25  conveys the waste toner collected at the cleaning portions  5   a  to  5   d  and the belt cleaner  19  to the toner collection device  21  through the discharge port  32 . 
       FIG.  2    is a perspective view of the toner collection device  21  and the waste toner conveying unit  25  according to the present disclosure.  FIG.  3    is a sectional front view (a sectional view cut along section line A-A′ in  FIG.  1   ) showing the internal structure of the toner collection device  21  according to the present disclosure.  FIG.  4    is a sectional view of the toner collection device  21  shown in  FIG.  3    cut along section line B-B′.  FIG.  5    is a sectional view of the toner collection device  21  shown in  FIG.  3    cut along section line C-C′. 
     In the following description, of the directions perpendicular to the up-down direction (arrow Z-Z′ direction in  FIGS.  1 ,  2 ,  3 , and  5   ), the direction along the width direction of the image forming apparatus  100  is taken as the left-right direction (arrow X-X′ direction in  FIGS.  1 ,  2 ,  4 , and  5   ). The direction perpendicular to both the up-down and left-right directions is taken as the front-rear direction (arrow Y-Y′ direction in  FIGS.  2 ,  3 , and  4   ). Furthermore, one side in the front-rear direction (arrow Y direction in the drawings) is taken as the “front side” and the other side (arrow Y′ direction in the drawings) is taken as the “rear side”. One side in the left-right direction (arrow X direction in the drawings) is taken as the “left side” and the other side (arrow X′ direction in the drawings) is taken as the “right side”. 
     As shown in  FIGS.  1  to  3   , the toner collection device  21  includes a toner collection container  23 , a toner conveying passage  27 , a side wall  28 , a recessed sensing portion  29 , and a detection sensor  30 . The toner collection container  23  is a bottomed container that can store in it the waste toner conveyed by the waste toner conveying unit  25 . In the top face of the toner collection container  23 , a toner collection port  31  is formed. The toner collection port  31  is a through hole that penetrates, in the up-down direction, a top face part of the toner collection container  23 . The toner collection port  31  is arranged below the discharge port  32  of the waste toner conveying unit  25 . Through the toner collection port  31 , the waste toner discharged from the discharge port  32  is fed into the toner collection container  23 . 
     The toner conveying passage  27  is arranged below the toner collection port  31  and conveys the waste toner fed in through the toner collection port  31  into the toner collection container  23 . The toner conveying passage  27  includes a first inclined portion  33  provided right under the toner collection port  31  and a second inclined portion  34  coupled with the first inclined portion  33 . 
     As shown in  FIGS.  4  and  5   , the first inclined portion  33  is a plate-form member that is inclined downward leftward (arrow X direction in  FIGS.  4  and  5   ) in the left-right direction. The waste toner fed in through the toner collection port  31  falls on the first inclined portion  33  to slide down to a bottom end part of the first inclined portion  33 . The inclination angle of the first inclined portion  33  (the inclination of the first inclined portion  33  relative to the horizontal plane) is larger than the angle of repose of waste toner. 
     As shown in  FIGS.  3  and  4   , the second inclined portion  34  is a plate-form member that is inclined downward frontward (arrow Y direction in  FIGS.  3  and  4   ) in the front-rear direction. The second inclined portion  34  is connected at a top end part of it to the inner wall face of the toner collection container  23  on the rear side and extends frontward from the top end part to a bottom end part. The inclination angle of the second inclined portion  34  (the inclination of the second inclined portion  34  relative to the horizontal plane) is larger than the angle of repose of waste toner. The top end part of the second inclined portion  34  is connected to the bottom end part of the first inclined portion  33 . The waste toner that has slid down on the first inclined portion  33  leftward slides down frontward on the second inclined portion  34  and then falls from the bottom end part of the second inclined portion  34  to a bottom portion  35  of the toner collection container  23 . 
       FIG.  6    is a sectional view of the toner collection container  23  cut along section line D-D′ in  FIG.  5   . As shown in  FIGS.  5  and  6   , the side wall  28  is formed so as to rise from an end part of the second inclined portion  34  on the right side. The side wall  28  extends from the top end part to the bottom end part of the second inclined portion  34  along the conveying direction of waste toner (see  FIG.  5   ). 
     The side wall  28  has a third inclined portion  36  that is connected to an end part of the second inclined portion  34  on the right side. The third inclined portion  36  is inclined downward from its top end (the top of the side wall  28 ) leftward. 
     The waste toner that slides down on the second inclined portion  34  passes through a region surrounded by the second inclined portion  34 , the inner wall face of the toner collection container  23  on the left side, and the third inclined portion  36 . The cross-sectional area of the region surrounded by the side wall  28 , the second inclined portion  34 , and the toner collection container  23  substantially equals the cross-sectional area of the toner conveying space (the space which is partitioned by the helical blade and the rotary shaft of the conveying screw  24  and in which waste toner is conveyed as the helical blade rotates) of the conveying screw  24  cut on a plane perpendicular to its axis. 
     As shown in  FIG.  6   , the recessed sensing portion  29  has an opening  38  between the top of the side wall  28  and the inner wall face of the toner collection container  23  on the right side (in the arrow X′ direction) and is recessed from the opening  38  rearward (in the arrow Y′ direction). The recessed sensing portion  29  communicates with the internal space of the toner collection container  23  through the opening  38 . Waste toner in the toner collection container  23  enters through the opening  38  the recessed sensing portion  29  and accumulates there. 
     As shown in  FIG.  6   , the detection sensor  30  is an optical sensor such as a photointerruptor and includes a light emitting portion  39  that emits light and a light receiving portion  40  that receives the light emitted from the light emitting portion  39 . The detection sensor  30  is arranged outside the toner collection container  23  so as to overlap with the recessed sensing portion  29  in the front-rear direction. The light emitting portion  39  and the light receiving portion  40  are arranged so as to be located opposite each other across the recessed sensing portion  29  in the left-right direction. The detection sensor  30  is connected to a control portion (omitted from illustration) provided at a predetermined position in the image forming apparatus  100 . The result of sensing by the detection sensor  30  is transmitted to the control portion. 
     The detection sensor  30 , based on the light reception condition in the light receiving portion  40 , senses the presence or absence of waste toner between the light emitting portion  39  and the light receiving portion  40 . Specifically, the light reception condition in the light receiving portion  40  when there is no waste toner between the light emitting portion  39  and the light receiving portion  40  (the state shown in  FIG.  6   ) is taken as a reference state. When waste toner accumulates between the light emitting portion  39  and the light receiving portion  40  (see  FIG.  9   ), the light emitted from the light emitting portion  39  is intercepted by the waste toner and the light reception condition changes from the reference state described above. This sensing result is transmitted to the control portion, and the control portion displays on an operation screen or the like of the image forming apparatus  100  that a predetermined amount of waste toner is stored in the toner collection container  23 . 
     As described above, the waste toner fed in through the toner collection port  31  is, by sliding down on the first and second inclined portions  33  and  34 , conveyed through the toner conveying passage  27  to the bottom portion  35  of the toner collection container  23 . In the end part of the second inclined portion  34  on the right side, the side wall  28  is provided. Thus, the waste toner fed in through the toner collection port  31  is, while being inhibited from entering the recessed sensing portion  29  by the side wall  28 , conveyed through the second inclined portion  34  to the bottom portion  35  of the toner collection container  23 . 
       FIG.  7    is a sectional view of the toner collection container  23  in a state where waste toner is stored in it.  FIG.  8    is a sectional view of the toner collection container  23  shown in  FIG.  7    cut along section line E-E′.  FIG.  9    is a sectional view of the toner collection container  23  showing a state where waste toner is stored in the recessed sensing portion  29 . 
     As shown in  FIG.  7   , when the amount of waste toner stored in the toner collection container  23  increases until waste toner has accumulated higher than the bottom end part of the second inclined portion  34 , waste toner starts to accumulate in the toner conveying passage  27 . As described above, waste toner in the toner conveying passage  27  is inhibited from entering the recessed sensing portion  29  by the side wall  28 . However, as shown in  FIG.  9   , when the amount of waste toner stored in the toner collection container  23  becomes larger than a predetermined amount and the amount of waste toner in the toner conveying passage  27  exceeds a predetermined amount, the waste toner goes over the side wall  28  to enter the recessed sensing portion  29  through the opening  38  and starts to be stored in the recessed sensing portion  29 . 
     The storing of waste toner in the recessed sensing portion  29  proceeds, as the amount of waste toner stored in the toner collection container  23  increases, gradually from the bottom. When the waste toner accumulates up to a predetermined position in the recessed sensing portion  29  in the up-down direction, the light emitted from the light emitting portion  39  is intercepted and the light reception condition in the light receiving portion  40  changes. Then, the control portion displays on the operation screen or the like of the image forming apparatus that a predetermined amount of waste toner is stored in the toner collection container  23 . 
     As described above, the waste toner fed in through the toner collection port  31 , while being inhibited from entering the recessed sensing portion  29  by the side wall  28 , gradually accumulates in the toner collection container  23 . In this way, it is possible to prevent erroneous sensing by the detection sensor  30  due to waste toner attaching to around the detection sensor  30  in the recessed sensing portion  29 . Until the amount of waste toner stored in the toner collection container  23  becomes larger than a predetermined amount (at least the amount enough to reach the bottom end part of the second inclined portion  34 ), waste toner is inhibited from entering the opening  38  by the side wall  28 . This helps prevent the detection sensor  30  from sensing waste toner before enough of it is stored in the toner collection container  23 . Thus, it is possible to replace the toner collection container  23  efficiently. 
     As described above, the third inclined portion  36  is formed on the side wall  28 . Thus, even when waste toner that has entered the second inclined portion  34  from the first inclined portion  33  collides against the side wall  28 , it easily falls onto the second inclined portion  34  along the third inclined portion  36 . This helps prevent waste toner from adhering to the side wall  28 . In addition, owing to waste toner sliding down on the third inclined portion  36 , waste toner in the toner conveying passage  27  concentrates on the second inclined portion  34  more easily. In this way, when a predetermined amount of waste toner is stored in the toner collection container  23 , waste toner gradually accumulates starting in the second inclined portion  34  that is located in a bottom portion of the toner conveying passage  27 . Thus, it is possible to reduce what is called a dead space where no waste toner accumulates and thereby efficiently store waste toner in the toner collection container  23 . 
     As described above, the inclination angles of the first and second inclined portions  33  and  34  are set to be larger than the angle of repose of waste toner. Thus, the waste toner that has fallen onto the first and second inclined portions  33  and  34  does not stay at where it has fallen but is conveyed to the downstream side of the toner conveying passage  27 . This helps prevent the problem of waste toner attaching to the first inclined portion  33  or to the second inclined portion  34  and blocks the toner conveying passage  27  to interfere with the storing of waste toner in the toner collection container  23 . 
     The embodiment described above is in no way meant to limit the present disclosure, which thus allows for many modifications and variations within the spirit of the present disclosure. For example, the present disclosure is applicable not only to tandem-type color printers like the one shown in  FIG.  1    but to various types of image forming apparatuses having a waste toner collection mechanism, such as color copiers and printers of a rotary type, monochrome copiers, monochrome printers, digital multifunction peripherals, and facsimile machines. 
     By mounting a toner collection device according to the present disclosure, it is possible to provide an image forming apparatus that allows replacement of a toner collection container with appropriate timing and with which it is possible to reduce the frequency of replacement of the toner collection container and prevent backflow of waste toner.