Abstract:
A developer and a color image forming apparatus are provided. The color image forming apparatus includes a development cartridge including a photosensitive drum and a container which stores toner. A toner cartridge is configured to attach to and detach from the development cartridge which contains the toner. A toner transfer unit rotates to agitate the toner stored in the development cartridge so as to move the toner when the toner cartridge attaches to and detaches from the development cartridge.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
   This application claims the benefit under 35 U.S.C. § 119(a) of Korean Patent Application No. 10-2005-0049700, filed on Jun. 10, 2005, in the Korean Intellectual Property Office, the entire disclosure of which is hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a developer and an image forming apparatus using the same. More particularly, the present invention relates to a developer including a toner transfer unit to prevent a toner from leaking when a toner cartridge is attached to and detached from a development cartridge and a color image forming apparatus using the developer. 
   2. Description of the Related Art 
   Generally, in image forming apparatuses, a digital image signal corresponding to a desired image is received to form an electrostatic latent image onto a photosensitive medium using an exposure unit such as a laser scanning unit (LSU). Then, the electrostatic latent image is developed into a toner image by using a toner. The toner image is transferred onto a recording medium and the toner image is fused and fixed to the recording medium by applying heat and pressure to the toner image. Consequently, a desired image is formed on the recording medium. 
   According to the type of toners and carriers used therein, the image forming apparatuses can be classified into dry types and wet types. The dry type image forming apparatuses can be classified into an image forming apparatus including a one-component developer and an image forming apparatus including a two-component developer. The one-component developer forms an image by using only toners. The two-component developer forms an image by using toners and carriers. The toner particles are attached to the carriers. 
   A single pass type color image forming apparatus generally includes four photosensitive drums, four exposure units for forming electrostatic latent images onto the four photosensitive drums, and four developers for developing the electrostatic latent images formed on the four photosensitive drums by supplying toners of black K, cyan C, magenta M, and yellow Y to the electrostatic latent images, respectively. The four photosensitive drums come into contact with an intermediate transfer belt. Toner images of black K, cyan C, magenta M, and yellow Y are developed on the four photosensitive drums and are superpositionally transferred onto the intermediate transfer belt to form a color toner image. The color toner image is transferred and fixed to a sheet of paper to form a color image. 
   A built-in type developer includes a container for storing a toner so that the developer refilled with the toner can be used. Alternatively, the developer can be replaced with a split-type developer in which a toner can be supplied from a toner cartridge which is detachable from a development cartridge. 
   In the built-in type, in order to refill the developer with the toner when the toner is used up, the developer is detached from a main frame. The toner is refilled in the developer and then the developer is attached to the main frame again. Accordingly, there is a relatively small possibility that the toner filled in the developer leaks, which leads to contamination of peripheral devices. 
   In the split type, in order to refill the developer with the toner again, the toner cartridge for storing the toner is detached from the development cartridge and a new toner cartridge is refilled with toner and attached to the development cartridge. Accordingly, in the way of detaching the toner cartridge from the development cartridge or attaching the new toner cartridge to the development cartridge, the toner remaining in the toner cartridge may leak or a part of the toner filled in the development cartridge may leak out of the development cartridge. This may lead to contamination of the peripheral devices. 
   Accordingly, there is a need for an improved image forming apparatus to prevent toner from leaking by flattening the toner contained in a development cartridge when a toner cartridge is attached to and detached from the development cartridge. 
   SUMMARY OF THE INVENTION 
   An aspect of the present invention is to address at least the above problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a developer including a toner transfer unit which can prevent toner from leaking by flattening the toner contained in development cartridge when a toner cartridge is attached to and detached from the development cartridge and a color image forming apparatus having the developer. 
   According to an aspect of the present invention, there is provided a developer comprising a development cartridge including a photosensitive drum and a container which stores toner. A toner cartridge is fitted to and detached from the development cartridge and contains the toner. A toner transfer unit can rotate to vibrate the toner stored in the development cartridge so as to flatten the toner when the toner cartridge is fitted to and detached from the development cartridge. 
   Other objects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a view illustrating a structure of an embodiment of a single pass type color image forming apparatus according to an exemplary embodiment of the present invention; 
       FIG. 2  is a cross-sectional view illustrating a structure of a developer employing a toner transfer unit according to an exemplary embodiment of the present invention; 
       FIG. 3  is a perspective view illustrating a toner cartridge which detaches from a development cartridge in the developer shown in  FIG. 2 ; 
       FIG. 4  is a perspective view illustrating the toner cartridge which attaches to the development cartridge in the developer shown in  FIG. 2 ; and 
       FIGS. 5 and 6  are views illustrating a power transmission path for operations of the toner transfer unit according to an exemplary embodiment of the present invention. 
   

   Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements, features, and structures. 
   DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
   The matters defined in the description such as a detailed construction and elements are provided to assist in a comprehensive understanding of the exemplary embodiments of the invention. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications to the embodiments described herein can be made without departing from the scope and spirit of the present invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness. 
   Referring to  FIGS. 1 and 2 , a color image forming apparatus includes four exposure units  1 K,  1 C,  1 M, and  1 Y, four development units  30 K,  30 C,  30 M, and  30 Y having photosensitive drums  21 K,  21 C,  21 M, and  21 Y, respectively. The image forming apparatus also includes four transfer members  50 K,  50 C,  50 M, and  50 Y, a transfer belt  60 , and a fixing device  70 . 
   The exposure units  1 K,  1 C,  1 M, and  1 Y form an electrostatic latent image by irradiating light corresponding to image data of black K, cyan C, magenta M, and yellow Y onto the photosensitive drums  21 , respectively. 
   The development units  30 K,  30 C,  30 M, and  30 Y, which develop the electrostatic latent images on the photosensitive drums  21  by using toners of black K, cyan C, magenta M, and yellow Y, respectively, include a development cartridge  20 , a toner cartridge  30  containing toners that are detachably disposed in the development cartridge  20 , and a toner transfer unit  40 . 
   The development cartridge  20  includes a development roller  22 , a supply roller  23 , a charging roller  24 , a metering blade  25 , a cleaning blade  26 , and a stirring roller  27 . 
   The development roller  22  develops the electrostatic latent image into a toner image on the photosensitive drum  21  using the toners. The supply roller  23  supplies the toners onto the development roller  22 . 
   The charging roller  24  charges the outer circumferential surface of the photosensitive drum  21  to a predetermined electric potential. The metering blade  25  controls the thickness of the toner attached to the outer circumferential surface of the development roller  22  to a predetermined thickness. 
   The cleaning blade  26  removes toners remained on the surface of the photosensitive drum  21 . Waste toners removed by the cleaning blade  26  are stored in a waste toner storage unit  29 . 
   The stirring roller  27  disposed in a container  28  rotates so that the toner stored in the container  28  vibrates in order to prevent the toner from becoming hardened. 
   The toner cartridge  30 , as shown  FIGS. 3 and 4 , is disposed on the development cartridge  20  in a detachable manner and contains the toner. 
   At the lower part of the toner cartridge  30 , an outflow aperture  31  is formed so that the toner flows out therethrough. Moreover, at the upper part of the development cartridge  20 , an inflow aperture  32  corresponding to the outflow aperture  31  is formed so that the toner flows in therethrough. Thus, when the toner cartridge  30  is placed into the development cartridge  20 , the outflow aperture  31  and the inflow aperture  32  are connected to each other, so that the toner flows into the development cartridge  20 . When the toner cartridge  30  separates from the development cartridge  20 , the inflow aperture  32  is exposed to the outside as shown in the  FIG. 3 . 
   Meanwhile, the outflow aperture  31  is open and closed by a shutter (not shown in the drawings). When the toner cartridge  30  is placed into the development cartridge  20 , the shutter opens the outflow aperture  31  to connect to the inflow aperture  32 . When the toner cartridge  30  separates from the development cartridge  20 , the shutter closes the outflow aperture  31 . 
   The toner contained in the container  28  is transferred from the toner cartridge  30 . As shown in  FIG. 2 , the toner is loaded mainly on the underneath of the inflow aperture  32 . In some cases, if the toner is loaded to come in contact with the inflow aperture  32 , when the toner cartridge  30  separates, the toner may leak out of the inflow aperture  32 . Alternatively, when the shutter is open and closed, the toner may leak out of the inflow aperture  32 . 
   The toner transfer unit  40 , which flattens the toner loaded in the container  28  to prevent the toner from leaking out of an apparatus when the toner cartridge  30  is detached from the development cartridge  20  includes a rotation lever  41  and a toner transfer plate  43 . 
   The rotation lever  41  protrudes from one side of the toner cartridge  30  and is rotatably disposed so as to open and close the shutter (not shown). Although the shutter is not shown in the drawings, the rotation lever  41  and the shutter may be operatively connected by conventional techniques. Thus explanation thereof will be omitted for clarity and conciseness. The rotation lever  41  includes a driving gear  42 . The driving gear  42  rotates when the rotation lever  41  rotates, thereby agitating and flattening the toner piled within container  28 . 
   The toner transfer plate  43  is rotatably and longitudinally disposed in the container  28 . At an axis  45  of the toner transfer plate  43 , a driven gear  44  is provided, which protrudes from one side of the development cartridge  20 . 
   At one side of the development cartridge  20 , a transmission gear  46  engages the driven gear  44  and is provided in a rotatable manner. The transmission gear  46  engages the driving gear  42  when the toner cartridge  30  is placed into the development cartridge  20 , while separated from the driving gear  42  when the toner cartridge  30  is separated from the development cartridge  20 . 
   The toner transfer plate  43 , as shown in  FIG. 5 , rotates counterclockwise when the rotation lever  41  engages thereto and rotates counterclockwise. On the other hand, as shown in  FIG. 6 , the toner transfer plate  43  rotates clockwise when the rotation lever  41  engages thereto and rotates clockwise. Thus, the toner transfer plate  43  rotates by a predetermined angle corresponding to a rotation of the rotation lever  41 , so that the driving gear  42 , the transmission gear  46 , and the driven gear  44  can form teeth only in the portions corresponding to the angles that can be geared with each other. 
   The rotation lever  41  rotates when the toner cartridge  30  is attached into the development cartridge  20  or separates from the development cartridge  20 , and moves the shutter (not shown) so as to close the outflow aperture  31 . 
   The transfer belt  60  facing the photosensitive drums  21 K,  21 C,  21 M, and  21 Y transfer a sheet of paper P. The photosensitive drums  21 K,  21 C,  21 M, and  21 Y come in contact with the paper P or the transfer belt  60 . The paper P is attached to the transfer belt  60  by the electrostatic force. 
   Transfer members  50 K,  50 C,  50 M, and  50 Y include transfer rollers  51 K,  51 C,  51 M, and  51 Y facing the photosensitive drums  21 K,  21 C,  21 M, and  21 Y and voltage application units  52 K,  52 C,  52 M, and  52 Y for applying voltages to the transfer rollers  51 K,  51 C,  51 M, and  51 Y. 
   In the voltage application units  52 K,  52 C,  52 M, and  52 Y, if a transfer voltage having an opposite polarity of a toner image is applied to the transfer rollers  51 K,  51 C,  51 M, and  51 Y, a transfer electric field is applied to the rear side of the transfer belts  60 . The toner image of black K, cyan C, magenta M, and yellow Y formed on the photosensitive drums  21 K,  21 C,  21 M, and  21 Y overlaps and is transferred to the paper P. Thus, a color toner image is formed on the paper P. The fixing device  70  fuses the color toner image onto the paper P by applying heat and pressure. 
   While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.