Patent Publication Number: US-9846390-B2

Title: Toner conveying device and image forming apparatus

Description:
INCORPORATION BY REFERENCE 
     This application is based on and claims the benefit of priority from Japanese Patent application No. 2016-079665 filed on Apr. 12, 2016, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     The present disclosure relates to a toner conveying device conveying a toner and an image forming apparatus including this toner conveying device. 
     An image forming apparatus of an electrographic manner includes a toner conveying device conveying a toner contained in a toner container to a developing device. 
     For example, the toner conveying device includes a horizontal conveying duct extended in a horizontal direction, a falling toner conveying duct extended in a downward direction from the horizontal conveying duct, a toner conveying member rotatably arranged inside the horizontal conveying duct, and a coil spring arranged in the falling toner conveying duct. The toner is freely fallen inside the falling toner conveying duct. An upper end of the coil spring is relative-rotatably locked on a protruding part formed on a rotation shaft of the toner conveying member. The coil spring reciprocates in upward and downward directions according to rotation of the toner conveying member. 
     Incidentally, the freely falling toner may be adhered or aggregated on an internal wall face of the falling toner conveying duct. The above-mentioned toner conveying device is configured to restrain adhesion and aggregation of the toner on the internal wall face of the falling toner conveying duct by reciprocating the coil spring in the upward and downward directions. 
     However, the falling toner may be caught by the spiral coil spring. That is, it is feared that the coil spring becomes an obstacle and resistance against the falling toner. 
     SUMMARY 
     In accordance with an embodiment of the present disclosure, a toner conveying device includes a toner replenishing tube, a loosening member, a toner conveying tube, a conveying member and a converting part. The toner replenishing tube is extended in upward and downward directions. The loosening member is provided so as to reciprocate in the upward and downward directions inside the toner replenishing tube. The toner conveying tube is extended in a direction crossing the toner replenishing tube and provided to communicate an upper portion of the toner replenishing tube and a toner containing part containing a replenishment toner. The conveying member is arranged rotatably inside the toner conveying tube to convey the toner from the toner containing part to the toner replenishing tube. The converting part converts rotating movement of the conveying member to reciprocating movement of the loosening member. The loosening member includes a straight line portion and a protruded portion. The straight line portion is engaged with the conveying member via the converting part and extended downwardly along the toner replenishing tube. The protruded portion is continuously provided from a lower end of the straight line portion and formed in a state being bent so as to protrude in a direction crossing the toner replenishing tube. 
     In accordance with an embodiment of the present disclosure, an image forming apparatus includes the toner conveying device described above and a developing device including a toner replenishment port connected to a lower end of the toner replenishing tube. 
     The above and other objects, features, and advantages of the present disclosure will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present disclosure is shown by way of illustrative example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view schematically showing an internal structure of a color printer according to an embodiment of the present disclosure. 
         FIG. 2  is a front view showing a developing device in the color printer according to the embodiment of the present disclosure. 
         FIG. 3  is a sectional view schematically showing a toner conveying device according to the embodiment of the present disclosure. 
         FIG. 4  is a front view showing a loosening member and a conveying screw in the toner conveying device according to the embodiment of the present disclosure. 
         FIG. 5  is a sectional view along a V-V line in  FIG. 2 . 
         FIG. 6  is a side view showing the loosening member in the toner conveying device according to the embodiment of the present disclosure. 
         FIG. 7  is a side view used for explaining an operation of the toner conveying device according to the embodiment of the present disclosure. 
         FIG. 8  is a side view showing the loosening member in the toner conveying device as a modified example according to the embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following, with reference to the drawings, a suitable embodiment of the present disclosure will be described. 
     With reference to  FIG. 1 , a color printer  1  as an image forming apparatus according to the embodiment will be described.  FIG. 1  is a sectional view schematically showing an internal structure of the color printer  1 . Incidentally, hereinafter, it will be described so that the front side of the color printer  1  is positioned at a near side in  FIG. 1  and others, and other sides will be based on directions shown in each figure. 
     The color printer  1  includes an apparatus body  2 , a sheet feeding cartridge  3  and an ejected sheet tray  4 . The sheet feeding cartridge  3  is attachably/detachably provided in a lower part of the apparatus body  2  formed in a roughly rectangular parallelepiped shape. Inside the sheet feeding cartridge  3 , a sheet/sheets S is/are stored. The ejected sheet tray  4  is provided in an upper part of the apparatus body  2 . Material of the sheet S is not restricted by a paper, but the sheet S may be a resin film or the like. 
     The color printer  1  includes a sheet feeding part  10 , an image forming part  11 , a fixing device  12  and a sheet ejecting part  13  inside the apparatus body  2 . The sheet feeding part  10  is arranged at an upstream end of a conveying path  15  extending from the sheet feeding cartridge  3  to the ejected sheet tray  4 . The image forming part  11  is arranged at an intermediate stream portion of the conveying path  15 . The fixing device  12  is arranged at a downstream side of the conveying path  15 . The sheet ejecting part  13  is arranged at a downstream end of the conveying path  15 . 
     The image forming part  11  includes four toner containers  20 , an intermediate transferring belt  21 , four drum units  22  and an optical scanning device  23 . The four toner containers  20  as toner containing parts are arranged in parallel in left and right directions below the ejected sheet tray  4 . The intermediate transferring belt  21  is revolvably arranged below the toner containers  20 . The four drum units  22  are arranged in parallel in the left and right directions below the intermediate transferring belt  21 . The optical scanning device  23  is arranged below the drum units  22 . 
     The four toner containers  20  contain replenishment toners (developers) of four colors (yellow, cyan, magenta, black). Each toner container  20  is attachably/detachably provided with respect to the apparatus body  2 . Incidentally, for example, the toner is a two-component developer having a carrier, but is not restricted by this and may be a one-component developer composed of a magnetic toner. The four drum units  22  is configured so as to arrange respective charging devices  25 , respective developing devices  26 , respective primary transferring rollers  27  and respective cleaning devices  28  around respective photosensitive drums  24 . Each photosensitive drum  24  is arranged below each primary transferring roller  27  across the intermediate transferring belt  21 . At the left side of the intermediate transferring belt  21 , a secondary transferring roller  29  forming a secondary transferring nip is arranged. 
     The color printer  1  is controlled by a controlling device (not shown) to execute image forming process. That is, each charging device  25  electrically charges a surface of each photosensitive drum  24 . The optical scanning device  23  exposes each photosensitive drum  24  to form an electrostatic latent image on the surface of each photosensitive drum  24 . Each developing device  26  develops the electrostatic latent image to a toner image by using the toner supplied from each toner container  20 . Toner images of four colors carried on four photosensitive drums  24  are primarily transferred onto the intermediate transferring belt  21  in order by the primary transferring rollers  27  having applied bias. Accordingly, toner image of full colors is formed on the intermediate transferring belt  21 . 
     On the other hand, the sheet feeding part  10  feeds the sheet S in the sheet feeding cartridge  3  one by one to the conveying path  15 . The toner image carried on the intermediate transferring belt  21  is secondarily transferred onto the sheet S by the secondary transferring roller  29  having applied bias. The fixing device  12  fixes the toner image onto a surface of the sheet S. The sheet ejecting part  13  feeds out the sheet S to the ejected sheet tray  4 . Each cleaning device  28  removes a toner remained on a surface of the photosensitive drum  24 . 
     Between each of the toner containers  20  and each of the developing devices  26 , each of toner conveying devices  40  is provided to convey the toner in each toner container  20  to each developing device  26 . Prior to description of the toner conveying device  40 , with reference to  FIG. 2 , the developing device  26  as a toner supply destination will be described.  FIG. 2  is a front view showing the developing device  26 . Incidentally, because the four developing devices  26  have similar structures, hereinafter, one developing device  26  will be described. 
     The developing device  26  applies so-called touch-down development system. The developing device  26  includes two mixers  31 , a magnet roller  32  and a developing roller  33  inside a case  30 . Each mixer  31 , the magnet roller  32  and the developing roller  33  are respectively supported by the case  30  so as to rotate around a rotational axis elongated in forward and backward directions. Incidentally, the developing device  26  is provided in the apparatus body  2  so as to be attachable/detachable along a rotational axis direction of the developing roller  33  and others. 
     The case  30  is formed in a roughly rectangular parallelepiped shape elongated in the forward and backward directions. Inside the case  30 , an agitation chamber  35  and a development chamber  36  are formed. The agitation chamber  35  is a space used for agitating the toner. In an upper face of the agitation chamber  35 , a toner replenishment port  37  is formed in a roughly rectangular tube shape. The development chamber  36  is formed above the agitation chamber  35  and is a space used for flying the toner to the photosensitive drum  24 . 
     The two mixers  31  are respectively rotated in the agitation chamber  35  to agitate the toner. The magnet roller  32  is arranged above the left mixer  31 . The magnet roller  32  is rotated in the development chamber  36  to hold the agitated developer by magnetism. The developing roller  33  is arranged above the magnet roller  32  and rotated in the development chamber  36 . The toner held by the magnet roller  32  is moved to the developing roller  33  to form a toner thin layer on a surface of the developing roller  33 . The toner is flown from this toner thin layer to the photosensitive drum  24  by an electric potential difference between the developing roller  33  and the photosensitive drum  24 . Thereby, the electrostatic latent image on the photosensitive drum  24  is developed to the toner image. 
     Next, with reference to  FIGS. 3 to 7 , the toner conveying device  40  will be described.  FIG. 3  is a sectional view schematically showing the toner conveying device  40 .  FIG. 4  is a front view showing a loosening member  42  and a conveying screw  44 .  FIG. 5  is a sectional view along a V-V line in  FIG. 2 .  FIG. 6  is a side view showing the loosening member  42 .  FIG. 7  is a side view used for explaining an operation of the toner conveying device  40 . Incidentally, because the four toner conveying devices  40  have similar structures, hereinafter, one toner conveying device  40  will be described. 
     As shown in  FIG. 3 , the toner conveying device  40  includes a toner replenishing tube  41 , the loosening member  42 , a toner conveying tube  43 , the conveying screw  44 , a converting part  45  and a recess part  46  (refer to  FIG. 5 ). 
     The toner replenishing tube  41  is formed in a roughly cylindrical shape and extended in upward and downward directions (a vertical direction). A lower end (a lower portion opening  41 D) of the toner replenishing tube  41  is connected to the toner replenishment port  37  of the developing device  26 . Inside the toner replenishing tube  41 , a vertical conveying path  41   a  used for freely falling the toner is formed. 
     The loosening member  42  is composed of, for example, wire material made of metal, such as stainless steel. The loosening member  42  is arranged inside the toner replenishing tube  41  (the vertical conveying path  41   a ). As described later in detail, the loosening member  42  is provided to loosen (to break) the toner adhered or aggregated on an inner circumference face of the toner replenishing tube  41 . 
     The toner conveying tube  43  is extended in the left and right directions (a direction crossing the toner replenishing tube  41 ) so as to become roughly horizontal. Moreover, the toner conveying tube  43  is extended so as to be bridged over the four developing devices  26  arranged in the left and right directions in a plane view. The toner conveying tube  43  is provided to communicate an upper portion opening  41 U of the toner replenishing tube  41  and a discharge port  20   a  of each toner container  20 . Inside the toner conveying tube  43 , a horizontal conveying path  43   a  used for conveying the toner from each toner container  20  to the toner replenishing tube  41  is arranged. 
     As shown in  FIGS. 3 and 4 , the conveying screw  44  as a conveying member includes a spiral blade  44   b  fixed on an outer circumference face of a rotation shaft  44   a . The conveying screw  44  is arranged along the toner conveying tube  43  inside the horizontal conveying path  43   a . The conveying screw  44  is arranged rotatably around an axis inside the toner conveying tube  43 . The conveying screw  44  is connected to a drive motor (not shown) via a gear train and others. The conveying screw  44  is rotated around the axis by driving the drive motor to convey the toner from each toner container  20  to the toner replenishing tube  41  (refer to a void arrow in  FIG. 3 ). Incidentally, the drive motor is controlled and driven by a controlling device. 
     As shown in  FIGS. 3 to 5 , the converting part  45  includes a crank portion  45   a  arranged at a portion shifted to the outside in a radial direction from the rotation shaft  44   a  of the conveying screw  44 . The crank portion  45   a  is formed in a state that a left end of the rotation shaft  44   a  is bent in a roughly U-shape. The crank portion  45   a  is positioned above the toner replenishing tube  41 . Incidentally, also in a right end of the rotation shaft  44   a , a crank shape is formed. 
     As shown in  FIG. 5 , the recess part  46  is recessed in a lower portion of the inner circumference face of the toner replenishing tube  41 . The recess part  46  is formed in a groove shape elongated in the upward and downward directions at a rear side of the inner circumference face of the toner replenishing tube  41 . 
     Subsequently, with reference to  FIGS. 4 to 6 , the loosening member  42  will be described. The loosening member  42  is extended over the whole length of the toner replenishing tube  41 . The loosening member  42  includes a straight line portion  50  and a protruded portion  51 . Incidentally, a length (a height h 1 ) in the upward and downward directions of the straight line portion  50  is longer than a length (a height h 2 ) in the upward and downward directions of the protruded portion  51  (refer to  FIG. 6 ). For example, the straight line portion  50  is formed to be three times higher than the protruded portion  51  (h 1 =h 2 *3). 
     As shown in  FIGS. 4 and 5 , the straight line portion  50  is formed in a bar shape (a line shape) extending straightly in the vertical direction. In an upper end of the straight line portion  50 , a hook portion  50   a  curved so as to be folded back downwardly is formed. The hook portion  50   a  is engaged with the above-described crank portion  45   a  so as to rotate relative to the crank portion  45   a . The straight line portion  50  is engaged with the conveying screw  44  via the converting part  45  and extended downwardly along the toner replenishing tube  41 . The loosening member  42  is arranged so as to hang down from the crank portion  45   a  inside the vertical conveying path  41   a.    
     As shown in  FIGS. 5 and 6 , the protruded portion  51  is continuously provided from a lower end of the straight line portion  50 . The protruded portion  51  is formed in a state being bent so as to protrude in the direction crossing the toner replenishing tube  41 . The protruded portion  51  is bent in a roughly V-shape and formed so as to be elastically deformable in the upward and downward directions. 
     In detail, the protruded portion  51  includes a first line portion  52  and a second line portion  53 . The first line portion  52  is formed in a state being bent with respect to the straight line portion  50 . In  FIG. 5  and others, the first line portion  52  is extended from the lower end of the straight line portion  50  in an oblique-forwardly downward direction. The first line portion  52  is formed so as to be bendable in the upward and downward directions around a continuing point (a first bent point B 1 ) with the straight line portion  50 . The second line portion  53  is formed in a state being bent in an opposite direction to the first line portion  52  with respect to the first line portion  52 . In  FIG. 5  and others, the second line portion  53  is extended from a lower end of the first line portion  52  in an oblique-backwardly downward direction. The second line portion  53  is formed so as to be bendable in the upward and downward directions around a continuing point (a second bent point B 2 ) with the first line portion  52 . Incidentally, the second line portion  53  is formed slightly longer than the first line portion  52 . 
     As shown in  FIG. 5 , the second line portion  53  is inserted into the recess part  46  in a state having clearance. A proximal end of the second line portion  53  comes into contact with a lower end face  46   a  of the recess part  46 . 
     Now, an action (an operation conveying the toner) of the toner conveying device  40  will be described. 
     As shown in  FIG. 3 , the toner in the toner container  20  is discharged from the discharge port  20   a  into the toner conveying tube  43  (the horizontal conveying path  43   a ). The conveying screw  44  driven and rotated by the drive motor conveys the toner in the horizontal conveying path  43   a  toward the toner replenishing tube  41 . The toner conveyed to a downstream side in the horizontal conveying path  43   a  is freely fallen from the upper portion opening  41 U of the toner replenishing tube  41  into the vertical conveying path  41   a . The fallen toner is supplied from the lower portion opening  41 D of the toner replenishing tube  41  through the toner replenishment port  37  into the agitation chamber  35 . That is, the toner is conveyed in the horizontal conveying path  43   a  and the vertical conveying path  41   a , and then, replenished to the developing device  26 . 
     Here, the straight line portion  50  of the loosening member  42  is straightly formed in roughly parallel to the toner replenishing tube  41 . Therefore, in the toner replenishing tube  41  (the vertical conveying path  41   a ), the straight line portion  50  does not obstruct the freely falling of the toner. Thereby, in the toner replenishing tube  41 , it is possible to secure smoothly falling of the toner. Moreover, the protruded portion  51  of the loosening member  42  is protruded in the direction crossing the toner replenishing tube  41 . Since the straight line portion  50  does not resist falling the toner, in the vertical conveying path  41   a , the toner is vigorously fallen, collided with the protruded portion  51  and loosened (dispersed). Thereby, it is possible to prevent the toner from adhering and aggregating on the inner circumference face of the toner replenishing tube  41 . 
     Incidentally, as shown in  FIG. 7 , if the conveying screw  44  is rotated, the crank portion  45   a  is revolved (eccentrically rotated) along a circular orbit around the rotation shaft  44   a  of the conveying screw  44  positioned away from a centroid of the crank portion  45   a . According to this, the loosening member  42  engaged with the crank portion  45   a  reciprocates in the upward and downward directions (refer to void arrows in  FIG. 7 ). Incidentally,  FIG. 7  illustrates phases of reciprocation (state transition) in the upward and downward directions of the loosening member  42  side by side. As described above, the converting part  45  (the crank portion  45   a ) converts rotating movement of the conveying screw  44  to reciprocating movement of the loosening member  42 . By arranging the crank portion  45   a  at a position shifted from the rotational shaft  44   a  to the outside in the radial direction, it is possible to actualize conversion of movement direction. 
     Moreover, the loosening member  42  is provided so as to reciprocate in the upward and downward directions in a state bringing a lower end of the protruded portion  51  (the second line portion  53 ) into contact with the lower end face  46   a  of the recess part  46 . In detail, in a state that the loosening member  42  (the crank portion  45   a ) is moved at an uppermost position, a lower end of the second line portion  53  comes into contact with the lower end face  46   a  of the recess part  46  (refer to a left illustration in  FIG. 7 ). 
     In a stage lowering the loosening member  42  (eccentrically rotating the crank portion  45   a ) from the uppermost position to a lowermost position (a stage of state transition from the left illustration to a right illustration in  FIG. 7 ), the lower end of the second line portion  53  is pressed against the lower end face  46   a  of the recess part  46 . According to this, the lower end of the second line portion  53  is slidingly moved to a direction away from the toner replenishing tube  41  (in the backward direction) on the lower end face  46   a  of the recess part  46  (refer to a void arrow of the right illustration in  FIG. 7 ). In addition, simultaneously, the protruded portion  51  is elastically deformed in a direction decreasing an angle α between the first line portion  52  and the second line portion  53 . That is, because the second line portion  53  receives reaction force from the lower end face  46   a  of the recess part  46 , the second line portion  53  is bent so as to approach the first line portion  52 . Incidentally, at this time, the protruded portion  51  is elastically deformed also in a direction slightly decreasing an angle β between the straight line portion  50  and the first line portion  52 . Incidentally, the height h 1  of the straight line portion  50  of the loosening member  42  is longer than a movement range (distance) R in the upward and downward directions of the crank portion  45   a.    
     In accordance with such a configuration, as the loosening member  42  is lowered, the lower end of the second line portion  53  is moved to the inside of the recess part  46 . Therefore, the second bent point B 2  overhung to an opposite side to the recess part  46  does not contact with a front side of the inner circumference face of the toner replenishing tube  41  facing to the recess part  46 . Thereby, it is possible to smooth reciprocation of the loosening member  42 . 
     On the other hand, in a stage heightening the loosening member  42  (eccentrically rotating the crank portion  45   a ) from the lowermost position to the uppermost position (a stage of state transition from the right illustration to the left illustration in  FIG. 7 ), pressing of the lower end of the second line portion  53  against the lower end face  46   a  of the recess part  46  is released. According to this, the lower end of the second line portion  53  is slidingly moved to a direction approaching the toner replenishing tube  41  (in the forward direction) and the protruded portion  51  is elastically deformed in a direction increasing the angle α by its own elastic force (refer to a void arrow of the left illustration in  FIG. 7 ). 
     In accordance with the above-described toner conveying device  40 , the loosening member  42  is provided to reciprocate in the upward and downward directions inside the toner replenishing tube  41  (the vertical conveying path  41   a ). Moreover, the protruded portion  51  of the loosening member  42  performs bending and stretching motion in the upward and downward directions by reaction force from the lower end face  46   a  of the recess part  46  and its own elastic force. Thereby, in the toner replenishing tube  41 , it is possible to loosen the toner and to fall the toner toward the developing device  26 . Moreover, since the protruded portion  51  performs bending and stretching motion, it is possible to shake off the toner caught by (adhered on) the protruded portion  51 . 
     Incidentally, although, in the toner conveying device  40  according to the present embodiment, the loosening member  42  is formed by bending the first bent point B 1  and the second bent point B 2 , the present disclosure is not restricted by this. For example, as shown in  FIG. 8 , the first line portion  52  may be formed in a state curved with respect to the straight line portion  50 . Similarly, the second line portion  53  may be formed in a state curved with respect to the first line portion  52 . Moreover, in the embodiment, although the protruded portion  51  of the loosening member  42  has the bent points B 1  and B 2  formed at two positions, it is not restricted by this. The protruded portion  51  may have the bent points formed at three or more positions, but its illustration is omitted. 
     Incidentally, although, the toner conveying device  40  according to the present embodiment uses the crank portion  45   a  as the converting part  45 , the present disclosure is not restricted by this. For example, the converting part  45  may be configured so that an eccentric cam integrally rotating with the conveying screw  44  is brought into contact with an upper end of the loosening member  42 . In such a case, it is preferable to provide a biasing member bringing the loosening member  42  into pressure contact with the eccentric cam. Alternatively, a drive source, such as a motor or a solenoid, driven in synchronization with rotation of the conveying screw  44  may be provided and the drive source may make the loosening member  42  reciprocate. 
     Incidentally, although, in the present embodiment, a case where the present disclosure is applied to the color printer  1  has been described as one example, the disclosure is not restricted by this, but may be applied to a monochrome printer, a facsimile, a multifunction peripheral or the like. 
     Incidentally, the above-description of the embodiments illustrates one aspect of the toner conveying device and the image forming apparatus including this according to the present disclosure, but the technical scope of the disclosure is not limited to the above-described embodiments. Components in the above-described embodiment can be appropriately exchanged and combined with existing components, and then, the above-description of the embodiments does not limit the content of the disclosure described in the claims.