Abstract:
A toner supplying device which is capable of individually supplying toners of different colors. The toner supplying device can include a driving source; a plurality of toner receptacles in which different color toners are contained and respective toner discharging members are provided in order to discharge toners while being driven by power transmitted from the driving source; and a plurality of spring clutches to selectively transmit power from the driving source to the toner discharging members. The toner supplying device according to the present general inventive concept can be advantageously employed in toner-refill type color image forming apparatuses in view of the miniaturization of the apparatus and reduction in the manufacturing costs.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 10-2006-0081154, filed on Aug. 25, 2006, in the Korean Intellectual Property Office, the entire disclosure of which is hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present general inventive concept relates to a color toner supplying device of a toner-refill type color image forming apparatus and a developing device having the same, and an image forming apparatus having the developing device. 
         [0004]    2. Description of the Related Art 
         [0005]    Toner-refill type color image forming apparatuses comprise four toner receptacles for storing respective color toners, such as yellow, magenta, cyan and black. The four toner receptacles include augers, which are toner discharging members for discharging toners from inside the toner receptacles to the outside. 
         [0006]    The augers may be rotated by power transmitted from a driving source. Accordingly, the augers are connected to the driving source using electric clutches, so that only the auger of the toner receptacle containing an insufficient amount of a color toner is rotated to supply the corresponding color toner to the developing device. At the same time, the augers of the other three toner receptacles containing sufficient amounts of the three other color toners are not rotated because the electric clutches are turned off. 
         [0007]    However, when using the above electric clutches as a power control unit in the toner supplying device, which is capable of supplying each color toner individually, the size of the developing device is large due to the required size of the electric clutches. Additionally, the manufacturing costs of the developing device and/or the image forming apparatus is large due to the expensive electric clutches. 
       SUMMARY OF THE INVENTION 
       [0008]    The present general inventive concept provides a toner supplying device which is capable of reducing manufacturing costs and achieving miniaturization of a developing device and/or an image forming apparatus by employing an inexpensive and small spring clutch as a power control unit. 
         [0009]    The present general inventive concept also provides a developing device and an image forming apparatus having the toner supplying device described above. 
         [0010]    Additional aspects and utilities of the present general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the general inventive concept. 
         [0011]    The foregoing and/or other aspects and utilities of the present general inventive concept are achieved by providing a toner supplying device including a driving source, a plurality of toner receptacles, in which different color toners are contained and respective toner discharging members are provided in order to discharge the toner while being driven by power transmitted from the driving source, and a plurality of spring clutches to selectively transmit power from the driving source to the toner discharging members. 
         [0012]    In an exemplary implementation, the spring clutches may include a driving shaft connected to the driving source, a clutch hub connected to the driving shaft so as to rotate together with the driving shaft, a clutch collar mounted on the driving shaft so as to be selectively rotated, a first gear member mounted on the driving shaft so as to be selectively rotated, a spring of which one end is fixed to the clutch collar and the other end is fixed to the first gear member to connect the clutch hub to the first gear member, and a solenoid to stop rotation of the clutch collar to release the connection of the spring and the clutch hub. 
         [0013]    In an exemplary implementation, a second gear member meshed with the first gear member may be provided. The first and second gear members have power transmission structures of worms and worm gears. 
         [0014]    In an exemplary implementation, the driving shaft and the clutch hub can be engaged with splines or serrations. 
         [0015]    Four toner receptacles and four spring clutches may be provided. The spring clutches control power transmitted to the toner discharging members of each toner receptacle. 
         [0016]    A developing device may include a developing case comprising a plurality of toner containers containing toners of different colors, a developing roller mounted to each end of the toner containers of the developing case, and a toner supplying device as described above which is capable of individually supplying each toner to the corresponding toner containers. 
         [0017]    The developing device may include a toner amount detecting sensor unit to detect the amount of toner contained in each toner container, and a controller to receive information from the toner amount detecting sensor unit to drive the solenoid corresponding to the toner container containing toner in insufficient amounts. 
         [0018]    The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an image forming apparatus including a photosensitive medium on which an electrostatic latent image is formed, a developing device to develope the electrostatic latent image formed on the photosensitive medium in which toners of different colors are transferred and attached, an intermediate transfer belt on which developed toner images on the photosensitive medium are overlapped and transferred, and a transfer unit to transfer the toner images to a printing medium. The developing device may include a developing case including a plurality of toner containers to contain toners of different colors, a developing roller mounted to each end of the toner containers of the developing case, and a toner supplying device as described above which is capable of individually supplying each toner to the corresponding toner containers. 
         [0019]    The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing an image forming apparatus including a toner supplying device including a plurality of toner receptacles in which different color toners are contained and respective toner discharging members are provided in order to discharge toners from corresponding toner receptacles when driven by a driving source, and a plurality of driving shafts connected along a line by universal joints, each driving shaft corresponding to a respective one of the toner receptacles, each one of the plurality of driving shafts driven independently of the others to drive the respective discharging member. 
         [0020]    The image forming apparatus may further include a plurality of spring clutches, each spring clutch connected with a respective one of the drive shafts to selectively transmit power from the driving source to a respective one of the toner discharging members via the respective connected drive shaft. 
         [0021]    The spring clutches may include a respective drive shaft connect to the driving source, a clutch hub connected to the respective drive shaft to rotate together with the drive shaft, a clutch collar and first gear member mounted on the driving shaft to be selectively rotated, a spring selectively connecting the clutch hub to a first gear member to transmit power; and a solenoid to stop the rotation of the clutch collar to release the connection between the spring and the clutch hub. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    These and/or other aspects and utilities of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
           [0023]      FIG. 1  is a schematic perspective view of a toner supplying device according to an exemplary embodiment of the present general inventive concept; 
           [0024]      FIG. 2  is a perspective view of the toner supplying device without the toner receptacles illustrated in  FIG. 1 ; 
           [0025]      FIG. 3  is a detailed view of the main parts of the exemplary embodiments of the present general inventive concept; 
           [0026]      FIGS. 4A to 4B  are assembled perspective views and exploded perspective views of the spring clutch which is an important part of the exemplary embodiments of the present general inventive concept; 
           [0027]      FIG. 5  is a view explaining the operation of the spring clutch which is an important part of the exemplary embodiments of the present general inventive concept, and 
           [0028]      FIG. 6  is a schematic view of an image forming apparatus having a developing device that employs the toner supplying device according to an exemplary embodiment of the present general inventive concept. 
       
    
    
       [0029]    Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features and structures. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present general inventive concept by referring to the figures. 
         [0031]      FIGS. 1 to 3  are views illustrating a toner supplying device of an image forming apparatus according to an exemplary embodiment of the present general inventive concept. In  FIGS. 1 to 3 , reference numeral  10  represents a driving source, reference numeral  20  represents toner receptacles, reference numeral  30  represents spring clutches, and reference numeral  40  represents a developing case. 
         [0032]    The driving source  10  may include a driving gear rotatably installed on one side of the developing case  40 . In this case, power may be transmitted by connecting the driving source to other power devices through a gear train (not illustrated) or the like. Alternatively, the driving source  10  may comprise a separate motor or the like. 
         [0033]    The four toner receptacles  20  respectively store yellow, magenta, cyan, and black color toners, and are detachably disposed on appropriate positions of the developing case  40 . Specifically, each of the toner receptacles  20  includes a toner discharging member (not illustrated) such as an auger to discharge toners from inside the toner receptacles to the outside while being driven by power transmitted from the driving source  10 . The toners that are discharged from the toner receptacles by driving the toner discharging member are supplied to toner containers  110  (referring to  FIG. 6 ) containing four respective color toners in the developing case  40 . 
         [0034]    The four spring clutches  30  are provided corresponding to the respective toner receptacles  20  in order to selectively transmit power from the driving source  10  to the respective toner discharging member. The toner discharging members of the toner receptacles  20  corresponding to the respective spring clutches  30  are driven so that only toner which is required can be supplied to the corresponding toner container  110  (referring to  FIG. 6 ) of a developing device  100  (referring to  FIG. 6 ). 
         [0035]    As illustrated in  FIGS. 3 ,  4 A and  4 B, each of the spring clutches  30  includes a driving shaft  31  connected to the driving source  10 , a clutch hub  32  connected to the driving shaft  31  so as to rotate together with the driving shaft  31 , a clutch collar  33  and a first gear member  34  which are mounted on the driving shaft  31  so as to be selectively rotated, a spring  35  selectively connecting the clutch hub  32  to the first gear member  34  so that power is transmitted, and a solenoid  36  to stop the rotation of the clutch collar  33  to release the connection between the spring  35  and the clutch hub  32 . 
         [0036]    The exemplary embodiments of the present general inventive concept illustrate a structure in which a first shaft  31   a  and a second shaft  31   b  of the driving shaft  31  are connected by a universal joint  31   c  by disposing the four toner receptacles  20  on an incline, but the present general inventive concept is not limited to this structure. For example, in this structure, when one driving shaft  31  is employed and an idle gear (not illustrated) is disposed between the driving shaft  31  and toner receptacles  20 , power can be transmitted. Additionally, when the four toner receptacles  20  are disposed in a straight line unlike the above structure, power can be transmitted using one driving shaft without a separate idle gear. 
         [0037]    The clutch hub  32  and the driving shaft  31  engage with splines or serrations, and accordingly the clutch hub  32  can rotate together with the driving shaft  31  when the driving shaft  31  rotates. The clutch hub  32  includes a drum unit  32   a.    
         [0038]    The clutch collar  33  includes a drum unit  33   a  and a latch unit  33   b , and is selectively rotated on the driving shaft  31 . The clutch hub  32  is disposed on the interior of the clutch collar  33 , and the inner circumference of the clutch collar  33  is spaced at a predetermined interval from the outer circumference of the clutch hub  32 . 
         [0039]    The first gear member  34  includes a worm  34   d  and a drum unit  34   a . The first gear member  34  is selectively rotated on the driving shaft  31  similarly to the clutch collar  33 . Additionally, a second gear member  37  (see  FIG. 5 ) is provided to mesh with the first gear member  34  at the worm  34   d , and includes a worm gear to engage with the worm  34   d . Furthermore, as illustrated in  FIG. 3 , the second gear member.  37  may mesh with the idle gear  38 , and the idle gear  38  may mesh with a third gear member  39  having a connecter  39   a  which connects to the toner discharging members inside the toner receptacles  20 . 
         [0040]    As illustrated in  FIG. 3 , since the black toner receptacle  20  (not illustrated, but connects with the connecter  39   a ) is disposed far apart from the driving shaft  31 , power is transmitted to the toner discharging member of the black toner receptacle  20  using the idle gear  38  and the third gear member  39 . However, when the toner receptacle  20  is not disposed apart from the driving shaft  31 , it is possible to form a connector of the toner discharging member in the second gear member  37  or the idle gear  38  without using the third gear member  39 . 
         [0041]    The clutch spring  35  encloses the drum unit  32   a  of the clutch hub  32  and the drum unit  34   a  of the first gear member  34 . One end  35   a  of the clutch spring  35  fixes to a fixing groove  33   c  of the clutch collar  33 , and the other end  35   b  thereof fixes to a fixing groove  34   c  of the first gear member  34 . For example, when the clutch spring  35  is rotated in a counterclockwise direction, the clutch spring  35  attaches to the drum unit  32   a  of the clutch hub  32  while being wound so that the rotational force of the clutch hub  32  may be transmitted to the first gear member  34 . In this case, the clutch collar  33  also rotates together with the clutch spring  35 . However, when stopping the rotation of the clutch collar  33 , the clutch spring  35  may be unwound and released from the clutch hub  32  so that the rotational force transmitted to the first gear member  34  from the clutch hub  32  can be cut off. 
         [0042]    The solenoid  36  releases the connection between the clutch spring  35  and clutch hub  32  by selectively stopping the rotation of the clutch collar  33 , and includes a locking projection  36   a  (see for example  FIG. 5 ). When the solenoid  36  is turned off, the locking projection  36   a  is lifted up and comes into contact with the latch unit  33   b  of the clutch collar  33  to stop the rotation of the clutch collar  33 . Additionally, when the solenoid  36  is turned on, the locking projection  36   a  moves away from the clutch collar  33  and unlocks the clutch collar  33  to allow it to be rotated. 
         [0043]    The solenoid  36  as described above is turned on or off by a controller  50  as illustrated in  FIG. 5 . The controller  50  receives information from a toner amount sensor unit  60  to drive the solenoid  36 . The toner amount sensor unit  60  detects the amount of toner stored in each toner container  110  of the developing device  100  and transmits the information on the toner amount to the controller  50 . The controller  50  determines which color toner currently has an insufficient amount based on the information, and as a result, the corresponding solenoid  36  is turned on, so that the toner discharging member of the corresponding toner receptacle  20  containing the required toner is driven. 
         [0044]      FIG. 6  is a schematic view of an image forming apparatus having the developing device  100  that employs the above toner supplying device. The developing device  100  includes the developing case  40  (referring to  FIGS. 1 and 2 ) including the four toner containers  110  storing toners of four respective colors, a developing roller  120  rotatably installed at each end of the toner containers  110 , and the toner supplying device as described above. 
         [0045]    In  FIG. 6 , reference numeral  200  is a photosensitive medium. On the photosensitive medium  200 , a predetermined electrostatic latent image is formed by scanning a laser beam using an exposure unit (not illustrated). The developing device  100  develops the electrostatic latent image on the photosensitive medium  200  wherein a required color toner is transferred and attached. 
         [0046]    A predetermined color toner image developed on the photosensitive medium  200  is primarily transferred by a T1 transfer roller  300  onto an intermediate transfer belt  400  sequentially. Accordingly, four color toner images overlap on the intermediate transfer belt  400  and a full color image is then transferred. 
         [0047]    The full color image transferred on the intermediate transfer belt  400  is then transferred by a T2 transfer roller  500  onto a printing medium P. The color image transferred onto the printing medium P is completely fixed by the fixing unit (not illustrated), and the printing medium P on which the color image is fixed is discharged. 
         [0048]    During this printing operation as described above, the toner amount sensor unit  60  (referring to  FIG. 5 ) detects the amount of toner stored in each toner container  110  and transmits the information on the toner amount to the controller  50 . The controller  50  determines which toner container  110  currently has an insufficient amount of color toner therein, based on the information from the toner amount sensor unit  60 . 
         [0049]    As the result of the determining of the amount of toner, if it is determined that black toner has an insufficient amount, as in  FIG. 5 , the corresponding solenoid  36  may be turned on by the spring clutch  30  for the black toner so that power can be transmitted to the respective toner discharging member of the black toner receptacle  20 . In detail, if it is determined that the toners are sufficient in the toner containers  110  for all colors, all power may be cut off by the four spring clutches  30 , that is, the solenoid  36  may stop the rotation of the clutch collar  33 . Accordingly, the first gear member  34  is not rotated, and only the driving shaft  31  is rotated. 
         [0050]    In this case, when the solenoid  36  of the spring clutch  30  for the black toner is turned on, the solenoid  36  unlocks the clutch collar  33 , and accordingly the clutch spring  35  is wound momentarily by the elasticity of the clutch spring  35 . Therefore, the clutch spring  35  comes into contact with the drum unit  32   a  of the clutch hub  32 , and the clutch spring  35  and the drum unit  32   a  of the clutch hub  32  then adhere more closely to each other. Accordingly, the clutch spring  35  rotates together with the clutch hub  32 . This rotational force is transmitted to the first gear member  34 , and the first gear member  34  rotates accordingly. 
         [0051]    When the first gear member  34  rotates, the second gear member  37  meshed with the first gear member  34  rotates, and the idle gear  38  and the third gear member  39  rotate. Accordingly, the toner discharging member in the toner receptacle  20  rotates to supply the toner in the toner receptacle to the toner container  110 . At this time, the solenoids  36  of the spring clutches  30  for the other color toners are turned off, so that power transmission to the toner discharging members of the other toner receptacles is cut off. 
         [0052]    When the black toner is supplied in the toner container  110  to the level required, the amount of toner is detected by the toner amount sensor unit  60 , and information on the amount of toner is transmitted to the controller  50  to turn off the solenoid  36 . Accordingly, the rotation of the clutch collar  33  is stopped, and the connection between the clutch spring  35  and the clutch hub  32  is released by unwinding the clutch spring  35  winding around the drum unit  32   a  of the clutch hub  32 . In other words, the first gear member  34  does not rotate any more. 
         [0053]    Using the above method, only the color toner that has an insufficient amount can be supplied to the corresponding toner container. The method of supplying only one color toner is described above, but if it is determined that two or three color toners have insufficient amounts, the solenoids of the spring clutches for the corresponding color toners are turned on so that it is possible to supply two or three color toners that have insufficient amounts to the corresponding toner containers simultaneously. 
         [0054]    As described above, according to the exemplary embodiments of the present general inventive concept, since an inexpensive and small spring clutch is used, it is possible to achieve miniaturization of the developing device and the image forming apparatus. Additionally, manufacturing costs can be reduced. 
         [0055]    Although a few embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.