Abstract:
There is provided a developing unit, including: a body defining a developing chamber and a developer accommodating chamber, and a developer delivery member. The body includes a sliding portion, a restoring portion and a colliding portion at the developer accommodating chamber. The developer delivery member includes an elastic member configured to be made a sliding contact with the sliding portion while being curved elastically, configured to be restored elastically at the restoring portion, and configured to collide with the colliding portion. The developer delivery member is configured so that, the elastic member which has been elastically restored at the restoring portion is collided with the colliding portion to generate an air flow and to deliver the developer in the developer accommodating chamber toward the connection port.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority from Japanese Patent Application No. 2012-078991 filed on Mar. 30, 2012, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a developing unit of an image forming apparatus including a developer container. 
         [0004]    2. Description of the Related Art 
         [0005]    A developing unit, which is provided in an image forming apparatus such as a laser printer and a digital copying machine, is generally provided with a developer container containing a developer (toner) and a developing chamber to which the developer is delivered from the developer container. A developing roller which carries the developer on a circumferential surface thereof and a supply roller which supplies the developer to the circumferential surface of the developing roller are provided in the developing chamber. 
         [0006]    As the developing container constructing this type of developing unit, for example, a developer container has been known in which a developer delivery member, which stirs the developer at a lower side of the developer container to deliver it to the developing chamber, is included. The developer delivery member is formed of a rotating base member (delivery support shaft) which rotates together with a rotational shaft and a body of the developer delivery member (sheet section) in which a base-end portion is fixed to the rotating base member and a front-end portion swings or rotates along an inner wall of the developer container. The body of the developer delivery member is formed of a plate-shaped elastic part so that the front-end portion thereof is moved slidably along the inner wall of the developer container while being curved or bended elastically. 
       SUMMARY OF THE INVENTION 
       [0007]    In the above described developer container, the developer is supplied from a bottom portion of the developer container to the developing chamber against gravitational force. Thus, there is fear that the developer is not supplied uniformly to the developing chamber to cause imbalance of the developer. Further, due to the imbalance of the developer, there is fear that the developer is not supplied to the supply roller uniformly and that the developer is not carried by the developing roller uniformly, and thereby causing image forming failure in some cases. 
         [0008]    In view of this, an object of the present teaching is to provide a developing unit of an image forming apparatus including a developer container, which is capable of improving a developer delivery capability of a developer delivery member delivering a developer and is capable of delivering the developer uniformly. 
         [0009]    In order to solve the above problem, according to an aspect of the present teaching, there is provided a developing unit of an image forming apparatus, including:
       a body defining a developing chamber and a developer accommodating chamber, the developing chamber being configured to accommodate a developing roller, and the developer accommodating chamber being configured to accommodate a developer and being connected to the developing chamber via a connection port, the body including a sliding portion, a restoring portion and a colliding portion at the developer accommodating chamber; and   a developer delivery member arranged in the developer accommodating chamber and configured to rotate in a rotating direction so that the developer in the developer accommodating chamber is delivered to the developing chamber, the developer delivery member including an elastic member configured to be made a sliding contact with the sliding portion while being curved elastically, configured to be restored elastically at the restoring portion, and configured to collide with the colliding portion,   wherein the sliding portion, the restoring portion and the colliding portion are arranged along the rotating direction,   the connection port is located on an upstream side of the colliding portion in the rotating direction, and   the developer delivery member is configured so that, the elastic member which has been elastically restored at the restoring portion is collided with the colliding portion to generate an air flow and to deliver the developer in the developer accommodating chamber toward the connection port.       
 
         [0015]    In the developing unit, the elastic member swings or rotates around a rotational axis, thereby stirring the developer contained in the developer accommodating chamber. Further, the elastic member slidably moves to rotate along the sliding portion in a state of being elastically curved toward an upstream side (rear side) in the rotating direction and the elastic member is restored elastically in the developer delivery chamber due to elastic restoring force, thereby releasing the developer into the developer accommodating chamber. Then, the elastic member collides with the colliding portion, thereby generating the air flow to deliver the developer (delivery air flow). The developer released into the developer accommodating chamber is delivered by the delivery air flow to the connection port which is open on the upstream side of the colliding portion in the rotating direction of the elastic member. In this situation, since the elastic member collides with the colliding portion to expel air between the elastic member and the colliding portion upward, a strong delivery air flow which has high energy as the air flow to deliver the developer is generated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a side sectional view of a schematic structure of a laser printer as an image forming apparatus which is provided with a developer container according to an embodiment of the present teaching. 
           [0017]      FIG. 2  is a lateral sectional view of a developing cartridge, which includes the developer container as shown in  FIG. 1 , in a direction perpendicular to an axis direction. 
           [0018]      FIG. 3  is a diagram showing an action of swing or rotation of an agitator body as shown in  FIG. 2  and showing a state in which a toner is delivered in the vicinity of a developer delivery opening. 
           [0019]      FIG. 4  is another diagram showing an action of swing or rotation of the agitator body as shown in  FIG. 2  and showing a state in which the toner is released to a developer delivery chamber by the agitator body. 
           [0020]      FIG. 5  is still another diagram showing an action of swing or rotation of the agitator body as shown in  FIG. 2  and showing a state in which the toner is delivered to the developer delivery opening by air flow to deliver the toner. 
           [0021]      FIG. 6  is a lateral sectional view of a developing cartridge which corresponds to  FIG. 2  and shows the first modified embodiment of the developer container. 
           [0022]      FIG. 7  is a lateral sectional view of a developing cartridge which corresponds to  FIG. 2  and shows the second modified embodiment of the developer container. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    Next, an explanation will be made in detail with respect to an embodiment of a developer container according to the present teaching with reference to the drawings appropriately. The developer container of the embodiment constructs a developing unit of an image forming apparatus and is embodied, for example, as a main part of a developing cartridge (developing unit)  10  which is removably installed to a laser printer  1  (image forming apparatus) as shown in  FIG. 1 . In the following description, the left side of the paper surface of  FIG. 1  is defined as “rear (backward)”, the right side of the paper surface of  FIG. 1  is defined as “front (forward)”, and the up-down direction of the paper surface of  FIG. 1  is defined as “up-down”. 
         [0024]    &lt;Schematic Structure of Laser Printer&gt; 
         [0025]    As shown in  FIG. 1 , the laser printer  1  includes a paper feed section  20  configured to feed paper sheet(s) P, an image forming section  30  configured to form an image on the paper sheet P, and the like in a main body casing  4 . Further, the laser printer  1  includes a flatbed scanner  50 , configured to read or scan a document to generate image data, on the main body casing  4 . The image forming section  30  includes a process section  60 , an exposure section  70 , a transfer section  80 , a fixing section  90 , and the like. 
         [0026]    &lt;Structure of Paper Feed Section&gt; 
         [0027]    The paper feed section  20  includes a paper feed tray  21  disposed at a lower portion of the main body casing  40 , a paper feed mechanism  22  disposed on a rear side of the paper feed tray  21 , and a paper pressing plate  23  by which each of the paper sheets P accommodated in the paper feed tray  21  is delivered to the paper feed mechanism  22 . The rear of each paper sheet P accommodated in the paper feed tray  21  is lifted upward by the paper pressing plate  23 , and the paper sheets P are separated one-by-one by the paper feed mechanism  22  to be transported upward. 
         [0028]    &lt;Structure of Process Section&gt; 
         [0029]    The process section  60  includes four process cartridges  62 , each of which is accommodated in a holding case  61  and is arranged with a predetermined spacing distance in front and rear directions. Each of the process cartridges  62  is formed of a photosensitive drum  63  having a photosensitive layer formed on the surface thereof, a charger  64  by which the photosensitive layer of the photosensitive drum  63  is uniformly charged, and a developing cartridge  10  configured to a developer to the photosensitive layer of the photosensitive drum  63 . The photosensitive drum  63  is arranged at the upper portion of the process cartridge  62 , the charger  64  is arranged on the rear side of the photosensitive drum  63 , and the developing cartridge  10  is arranged on the lower side of the photosensitive drum  63 . 
         [0030]    In each of the process cartridges  62 , the photosensitive layer formed on the surface of the photosensitive drum  63  is uniformly charged by the charger  64 , and then the photosensitive layer is exposed by high speed scanning with a laser beam emitted from the exposure section  70 . By exposing the photosensitive layer as described above, an electrostatic latent image based on image data is formed on the surface of the photosensitive drum  63 . Then, a toner, which is an example of the developer, is supplied from the developing cartridge  10  to the electrostatic latent image to form a toner image, in which the electrostatic latent image is visualized, on the surface of the photosensitive drum  63 . 
         [0031]    &lt;Structure of Exposure Section&gt; 
         [0032]    The exposure section  70  is arranged above the paper feed section  20  and below the process section  60 . The exposure section  70  includes a laser source, a polygon mirror, a lens, a reflecting mirror, and the like, those of which are not illustrated. In the exposure section  70 , the laser beam emitted from the laser source is reflected at the polygon mirror and/or the reflecting mirror to illuminate the surface of the photosensitive drum  63 , and the laser beam is subjected to the high speed scanning to expose the surface of the photosensitive drum  63 . 
         [0033]    &lt;Structure of Transfer Section&gt; 
         [0034]    The transfer section  80  is disposed above the process section  60 . The transfer section  80  includes a drive roller  81  arranged above the paper feed mechanism  22  disposed on the rear side of the main body casing  40 , a driven roller  82  arranged on the front side of the main body casing  40 , and an intermediate transfer belt  83  provided to span between the drive roller  81  and the driven roller  82 . 
         [0035]    The transfer section  80  includes four primary transfer rollers  84  and a secondary transfer roller  85 , the four primary transfer rollers  84  being arranged inside a lower path line of the intermediate transfer belt  83  while facing the respective photosensitive drums  63  so that the intermediate transfer belt  83  is pressed onto the four photosensitive drums  63  of the four process cartridge  62 , and the secondary transfer roller  85  being arranged to face the drive roller  81  so that the paper sheet P is pressed onto the intermediate transfer belt  83 . 
         [0036]    In the transfer section  80 , the toner images of respective colors formed on the photosensitive layers on the surfaces of the four photosensitive drums  63  are transferred and superimposed in order on the intermediate transfer belt  83 . Then, the paper sheet P transported upward from the paper feed mechanism  22  is pressed onto the intermediate transfer belt  83  by the secondary transfer roller  85  to transfer the toner images of respective colors transferred and superimposed on the intermediate transfer belt  83  on the paper sheet P. 
         [0037]    &lt;Structure of Fixing Section&gt; 
         [0038]    The fixing section  90  includes a heating roller  91  arranged above the drive roller  81  of the transfer section  80  and configured to heat the paper sheet P pressed by the secondary transfer roller  85  to be transported upward, and a pressurizing roller  92  arranged to face the heating roller  91  to press the paper sheet P onto the heating roller  91 . In the fixing section  90 , the toner images of respective colors transferred onto the paper sheet P from the intermediate transfer belt  83  are heated by the heating roller  91  to be thermally fixed. Then, the paper sheet P on which the toner images of respective colors have been thermally fixed is discharged on a paper discharge tray  42  by a paper discharge roller  93 . 
         [0039]    &lt;Structure of Developing Cartridge&gt; 
         [0040]    As shown in  FIG. 2  while being enlarged, the developing cartridge  10 , which is an example of the developer container, includes a container body  12  in which unillustrated toner is contained, an agitator  13  which is an example of a developer delivery member provided at a lower part of the container body  12 , a supply roller  14  provided at an upper part of the container body  12 , a developing roller  15 , a layer thickness-regulating blade  16 , and the like. 
         [0041]    &lt;Structure of Developer Container&gt; 
         [0042]    The container body  12  is a container which has an opening formed at an upper portion thereof and is elongated in left and right directions. A cross-section of the container body  12  has, for example, a raindrop shape. A colliding portion  12 A is formed at the upper portion on the rear side (left side) of the inner wall of the container body  12 ; a slide flat-surface portion  12 C is formed at the upper portion on the front side (right side) of the inner wall of the container body  12 ; and a slide curved-surface portion  12 B which is continuous to the colliding portion  12 A and the slide flat-surface portion  12 C is formed at the lower portion of the inner wall of the container body  12 . A developer delivery chamber  12 D is formed at a space between the slide flat-surface portion  12 C and the colliding portion  12 A. A developer delivery opening  12 E is open on the upstream side of the developer delivery chamber  12 D. 
         [0043]    The colliding portion  12 A of the container body  12  is a wall surface against which an agitator body  13 C of the agitator  13  as will be described later on collides in a swing or rotating direction. Here, a virtual plane, which is a plane when the agitator body  13 C is elastically restored to a free state, is defined as a free plane F. In this situation, the colliding portion  12 A is formed along an included surface which is inclined at a predetermined angle from the free plane F toward the upstream side (front side) in the swing direction of the agitator body  13 C, at a rotating position of a rotating base member  13 B at the time of collision of the agitator body  13 C with the colliding portion  12 A. 
         [0044]    The slide curved-surface portion  12 B of the container body  12  is a wall surface in a curved surface shape. The agitator body  13 C elastically contacts with the slide curved-surface portion  12 B to move slidably in a state of being elastically curved toward the upstream side in the swing direction (rear side in a movement direction). The slide flat-surface portion  12 C of the container body  12  is a wall surface in a flat surface. The agitator body  13 C elastically contacts with the slide flat-surface portion  12 C at the front-end portion thereof to move slidably in a state of being elastically curved toward the upstream side in the swing direction (rear side in the movement direction). The slide flat-surface portion  12 C is inclined so that the upper portion thereof approaches to the colliding portion  12 A. 
         [0045]    The developer delivery chamber  12 D of the container body  12  is a space in which the agitator body  13 C, which is elastically curved toward the upstream side in the swing direction (rear side in the movement direction), swings to the colliding portion  12 A while being restored elastically to the free state. In particular, the developer delivery chamber  12 D is provided above the lower end of the developer delivery opening  12 E (upper end of the slide flat-surface portion  12 C). The developer delivery opening  12 E is a delivery opening to deliver the toner from the developer delivery chamber  12 D to the supply roller  14 , and is formed to open at the upper portion of the slide flat-surface portion  12 C on the upstream side of the colliding portion  12 A in the swing direction of the agitator body  13 C. 
         [0046]    &lt;Structure of Agitator&gt; 
         [0047]    The agitator  13  is a component which is driven to rotate so that unillustrated toner contained in the container body  12  is stirred to be delivered to the developer delivery opening  12 E. The agitator  13  includes a rotational shaft  13 A extending in a longitudinal direction of left-right directions of the container body  12 , the rotating base member  13 B configured to rotate together with the rotational shaft  13 A, and the agitator body  13 C of which base-end portion is fixed to the rotating base member  13 B. 
         [0048]    A fixing part  13 D configured to fix the base-end portion of the agitator body  13 C is provided to protrude in the circumferential surface of the rotating base member  13 B. The base-end portion of the agitator body  13 C is fixed and adhered to the front surface, of the fixing part  13 D, facing the downstream side in the rotating direction with a double-faced adhesive tape etc. 
         [0049]    The agitator body  13 C is an example of a body of the developer delivery member. The agitator body  13 C is formed as an elastic part in a form of a thin-plate which has the elastic restoring force by using an appropriate synthetic resin material such as polyethylene terephthalate (PET). The length of the agitator body  13 C from the base-end portion to the front-end portion has a length to such an extent that the front-end portion of the agitator body  13 C reaches the upper portion of the colliding portion  12 A facing the developer delivery opening  12 E as shown in  FIG. 2 . 
         [0050]    As shown in  FIG. 2 , the supply roller  14  and the developing roller  15  are arranged in the vicinity of the developer delivery opening  12 E positioned at the upper portion of the container body  12  so that the circumferential surfaces of the supply roller  14  and the developing roller  15  are arranged closely to each other. The supply roller  14  is configured to supply the toner adhered to the circumferential surface of the supply roller  14  to the circumferential surface of the developing roller  15 . The supply roller  14  is disposed below the developing roller  15 . 
         [0051]    The rotating direction of each of the supply roller  14  and the developing roller  15  is a clockwise direction in an example as shown in  FIG. 2 . The supply roller  14  moves forward (rightward) and the developing roller  15  moves backward (leftward), which is opposite to the forward (rightward), at a position at which the circumferential surfaces of supply roller  14  and the developing roller  15  face each other. Accordingly, it is possible to supply the toner smoothly from the circumferential surface of the supply roller  14  to the circumferential surface of the developing roller  15 . 
         [0052]    The developing roller  15  is configured to carry the toner supplied from the supply roller  14  on the circumferential surface thereof and to supply the toner to the electrostatic latent image formed on the circumferential surface of the photosensitive drum  63  (see  FIG. 1 ). The developing roller  15  is disposed at a position nearer to the front side of the lower side of the photosensitive drum  63 . 
         [0053]    The layer thickness-regulating blade  16  is configured to regulate a layer thickness of the toner, supplied from the circumferential surface of the supply roller  14  to the circumferential surface of the developing roller  15  and carried by the circumferential surface of the developing roller  15 . The base-end portion of the layer thickness-regulating blade  16  is fixed to the upper portion of the rear side (left side) portion of the container body  12  in which the colliding portion  12 A is formed. The front-end portion, of layer thickness-regulating blade  16 , which protrudes frontward (rightward) from the base-end portion, makes contact with the circumferential surface on the lower side of the developing roller  15  rotating backward (leftward) to cope with the rotation direction of the developing roller  15 . 
         [0054]    In the developer container  11  of this embodiment configured as described above, as shown in  FIG. 3 , the rotating base member  13 B of the agitator  13  rotates leftward (in a direction shown by the arrow) together with the rotational shaft  13 A in the container body  12  and the agitator body  13 C formed as the elastic part swings leftward (in the direction shown by the arrow) with the rotational shaft  13 A as a center, thereby agitating the toner contained in the container body  12 . 
         [0055]    The agitator body  13 C swinging leftward (in the direction shown by the arrow) moves slidably along the slide curved-surface portion  12 B and the slide flat-surface portion  12 C of the container body  12  in a state of being elastically curved toward the upstream side in the swing direction (rear side in the movement direction). Then, as shown in  FIG. 4 , the agitator body  13 C releases the toner into the developer delivery chamber  12 D while being restored elastically to the free state having a flat plate-shape in the developer delivery chamber  12 D due to the elastic restoring force, and as shown in  FIG. 5 , the agitator body  13 C further swings to collide with the colliding portion  12 A. Accordingly, air flow to deliver the toner (delivery air flow R) is generated and the toner is delivered by the delivery air flow R toward the developer delivery opening  12 E. 
         [0056]    In this situation, the agitator body  13 C colliding with the colliding portion  12 A of the container body  12  collies with the colliding portion  12 A to expel air between the agitator body  13 C and the colliding portion  12 A upward, and thereby generating a strong delivery air flow R which has high energy as the air flow to deliver the toner. As a result, a toner delivery capability for delivering the toner to the developer delivery opening  12 E arranged above is improved. 
         [0057]    As described above, according to the developer container  11  of this embodiment, by swinging the agitator body  13 C in association with the rotation of the agitator  13 , it is possible to generate the strong delivery air flow which has the high energy as the air flow to deliver the toner, and thus it is possible to improve the toner delivery capability of the agitator configured to deliver the toner to the developer delivery opening  12 E arranged above. Further, it is possible to deliver the toner to the developer delivery opening  12 E arranged above in a state that the toner is dispersed by the delivery air flow to be uniformized. 
         [0058]    In the above description, although the embodiment of the developer container according to the present teaching has been described, the developer container of the present teaching is not limited thereto. The structure of the developer container can be changed appropriately. For example, as shown in  FIG. 6 , the colliding portion  12 A of the container body  12  may be formed parallel to the virtual free plane F, which is a plane when the agitator body  13 C is elastically restored to the free state having the flat plate-shape from the curved state, with a predetermined spacing distance on the downstream side in the swing direction of the agitator body  13 C, at the rotating position of the rotating base member  13 B at the time of the collision of the agitator body  13 C with the colliding portion  12 A. Alternately, the colliding portion  12 A of the container body  12  may be formed to overlap with the virtual free plane F. 
         [0059]    The predetermined distance provided when the colliding portion  12 A is formed to be parallel to the virtual free plane F with the predetermined distance is preferably a spacing distance which is smaller than an overshoot amount OS from the virtual free plane F, which is the plane when the agitator body  13 C is elastically restored from the curved state to the flat plate state. Thereby, the agitator body  13 C collides with the colliding portion  12 A reliably. 
         [0060]    As shown in  FIG. 7 , the following configuration is also allowable. That is, a space of a developing chamber is provided at the front side (right side) of the supply roller  14  and the developing roller  15  in the container body  12  and the layer thickness-regulating blade  16  is arranged in this space. In this case, it is preferable that the rotating direction of each of the supply roller  14  and the developing roller  15  is a counterclockwise direction which is a direction opposite to the rotating direction of the example as shown in  FIG. 2 ; that the base-end portion of the layer thickness-regulating blade  16  is fixed to the upper portion at the front side (right side) of the container body  12 ; and that the front-end portion, of the layer thickness-regulating blade  16 , protruding rearward (leftward) from the base-end portion makes contact with the circumferential surface on the lower side of the developing roller  15  rotating forward (rightward) to cope with the rotation direction of the developing roller  15 . 
         [0061]    Further, in the embodiment, the rotational shaft  13 A of the agitator  13  is arranged at the center of curvature of the slide curved-surface portion  12 B. The rotational shaft  13 A, however, may be arranged at a position which is eccentric from the center of curvature of the slide curved-surface portion  12 B. For example, the rotational shaft  13 A can be arranged eccentrically to a position closer to the slide flat-surface portion  12 C. In this case, when the agitator body  13 C slidably moves along the slide curved-surface portion  12 B while being elastically curved, degree of curve of the agitator body  13 C is increased gradually. Thus, the elastic restoring force generated when the agitator body  13 C is elastically restored along the slide flat-surface portion  12 C is increased, and thereby increasing an amount of the toner to be delivered by the agitator body  13 C. 
         [0062]    The developer container  11  of this embodiment is configured as a container placed vertically in which the toner is delivered upward by the agitator  13 . The developer container of the present teaching, however, may be configured as a container placed horizontally in which the toner is delivered in the front and rear directions by the agitator. 
         [0063]    The developer container of the present teaching may be configured as a toner cartridge, which is a separated member separated from the supply roller  14 , the developing roller  15 , and the layer thickness-regulating blade  16 .