Abstract:
A collecting unit to be used in an image forming apparatus having a waste toner storing chamber and a development chamber, the collecting unit including a collection passage connecting the waste toner storing chamber and the development chamber; and a movable first transfer unit provided in the collection passage to move waste toner from the waste toner storing chamber to the development chamber.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of Korean Patent Application No. 10-2004-0078549, filed on Oct. 2, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an image forming apparatus, and, more particularly, to an image forming apparatus having a transfer unit to forcibly transfer toner so as to prevent a toner collection passage from being blocked by collected toner that is hardened when the wasted toner is collected for reuse.  
         [0004]     2. Description of the Related Art  
         [0005]     In general, image forming apparatuses receive a digital image signal and form an electrostatic latent image on a photosensitive medium coated with a conductive material, by using an exposure unit like a laser scanning unit. The electrostatic latent image is developed into a toner image using toner. The toner image is transferred to a recording medium. By applying heat and pressure to the toner image on the recording medium, the toner image is fused thereon so that a desired image is obtained.  
         [0006]     The image forming apparatus can be generally classified into a dry type or a wet type according to the state of toner and carrier being used. The dry type can also be classified into an image forming apparatus having a 1-phase developing unit or an image forming apparatus having a 2-phase developing unit.  
         [0007]     In the 1-phase developing unit, only toner is provided to form an image. In the 2-phase developing unit, toner and a carrier to which toner particles are attached are provided to form an image.  
         [0008]     In the 1-phase developing unit, the toner is provided to the photosensitive medium to develop the toner image, and then the toner remaining on a surface of the photosensitive medium is removed by a cleaning blade and collected by a collecting unit for reuse. Also, in the 2-phase developing unit, the carrier is collected without being provided to the photosensitive medium, while the toner particles only are provided to the photosensitive medium to develop the toner image. Thereafter, the toner particles remaining on the surface of the photosensitive medium are removed by a cleaning blade and collected by the collecting unit for reuse. The above descriptions relate to a case of forming a black and white image. When a color image is formed, since a color toner image on the surface of the photosensitive medium is a mixture of toner of various colors, the toner remaining on the photosensitive medium is difficult to be reused.  
         [0009]     The following descriptions relate to only a case in which toner is collected for reuse in the 1-phase developing unit or 2-phase developing unit.  
         [0010]     As described above, in the process of collecting the toner removed from the photosensitive medium by the cleaning blade, when toner formed of light powder particles are accumulated and hardened on a toner collection passage, the toner collection passage may become blocked. When the toner collection passage is blocked, the toner collected for reuse is not provided into a development chamber and discharged out of the developing unit, and therefore a main body may be contaminated. Also, since the rotational torque of a toner transfer apparatus is increased, the toner transfer apparatus can be damaged.  
         [0011]     Furthermore, since the toner collection passage is blocked, the developing unit having an otherwise sufficient life span needs to be replaced earlier, which is disadvantageous to an aspect of cost saving.  
       SUMMARY OF THE INVENTION  
       [0012]     To solve the above and/or other problems, the present invention provides a developing unit having a transfer unit which can forcibly transfer toner on a toner collection passage to prevent the toner collection passage from being blocked by the toner during the collection of the toner for reuse, and an image forming apparatus adopting the same.  
         [0013]     Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention.  
         [0014]     According to an aspect of the present invention, a collecting unit to be used in a developing unit of an image forming apparatus having a waste toner storing chamber and a development chamber is provided, the collecting unit including a first transfer unit provided in the waste toner storing chamber; a second transfer unit provided in the development chamber; a collection passage connecting the waste toner storing chamber and the development chamber; and a third transfer unit provided in the collection passage, rotatable by being coupled to the second transfer unit, to transfer waste toner to the development chamber.  
         [0015]     According to another aspect of the present invention, a collecting unit to be used in an image forming apparatus having a waster toner storing chamber and a development chamber is provided, the collecting unit including a collection passage connecting the waste toner storing chamber and the development chamber; and a movable first transfer unit provided in the collection passage to move waste toner from the waste toner storing chamber to the development chamber.  
         [0016]     The collecting unit may further include a second transfer unit provided in the development chamber, wherein the first transfer unit is coupled to the second transfer unit.  
         [0017]     The second transfer unit may include a rotation shaft coupled to the first transfer unit, and the rotation shaft may rotate the first transfer unit.  
         [0018]     A plurality of protrusions may be provided on the rotation shaft, the protrusions interacting with the first transfer unit to rotate the first transfer unit.  
         [0019]     The first transfer unit may be divided into a plurality of sections to move the waste toner in separated portions.  
         [0020]     According to another aspect of the present invention, a collecting unit to be used in an image forming apparatus having a waste toner storing chamber and a development chamber is provided, the collecting unit including a collection passage connecting the waste toner storing chamber and the development chamber, and a movable unit provided in the collection passage to agitate waste toner as the waste toner moves form the waste toner storing chamber to the development chamber. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]     These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:  
         [0022]      FIG. 1  is a cross-sectional view illustrating the configuration of an image forming apparatus adopting a developing unit according to an embodiment of the present invention;  
         [0023]      FIG. 2  is a perspective view illustrating the developing unit according to an embodiment of the present invention;  
         [0024]      FIG. 3  is a partially exploded perspective view illustrating the developing unit of  FIG. 2 ;  
         [0025]      FIG. 4  is a magnified perspective view illustrating the transfer unit shown in  FIG. 3 ; and  
         [0026]      FIG. 5  is a cross-sectional view illustrating the operation of the transfer unit of  FIG. 3 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]     Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below to explain the present invention by referring to the figures.  
         [0028]     Referring to  FIG. 1 , an image forming apparatus  100  according to an embodiment of the present invention includes a cassette  110 , a toner container  120 , a developing unit  130 , an exposure unit  150 , a transfer roller  160 , a fusing unit  170 , and a paper eject unit  180 .  
         [0029]     The cassette  110 , into which a recording medium S is loaded, is detachably installed in a main body  101 . A pickup roller  111  to pick up the recording medium S sheet by sheet is rotatably installed in the main body  101  above the cassette  110 .  
         [0030]     The toner container  120  is detachably installed in the main body  101  and contains the toner  121 , which is a developer. A plurality of agitating rollers  122  are provided in the toner container  120  to agitate the toner  121 , so that the toner  121  is not hardened. When all of the toner  121  is used, the toner container  120  can be replaced with another toner container containing new toner.  
         [0031]     The developing unit  130  is detachably installed in the main body  101  to develop an electrostatic latent image into a toner image. The developing unit  130  is housed by a housing  131 , and includes a photosensitive drum  132 , a magnet roller  133 , a mixing roller  134 , and a collecting unit  135 .  
         [0032]     An inlet  1311  is provided in the housing  131  at a portion facing the toner container  120 . The inlet  1311  is provided to align with an outlet  1201  provided in the toner container  120  so that the toner  121  contained in the toner container  120  enters into a development chamber  136 .  
         [0033]     The photosensitive drum  132  is rotatably installed so that a portion of the photosensitive drum  132  is exposed outside of the housing  131 . The photosensitive drum  132  is charged to a predetermined electric potential, and an electrostatic latent image is formed thereon using a difference in the electric potential by light emitted from the exposure unit  150 .  
         [0034]     The magnet roller  133  rotates close to the photosensitive drum  132  to attach the toner  121  to the photosensitive drum  132  using repulsion that is generated due to a voltage difference.  
         [0035]     The mixing roller  134  is rotatably installed in the development chamber  136 , and mixes new toner, provided from the toner container  120  through the inlet  1311 , with waste toner, collected from the photosensitive drum  132 , in the development chamber  136 .  
         [0036]     Referring to  FIG. 3 , the collecting unit  135  collects for reuse the waste toner which remains on the surface of the photosensitive drum  132  without being transferred to the recording medium S. The collecting unit  135  includes a waste toner storing chamber  1351 , a collection screw  1352 , a collection passage  1353 , a transfer screw  1354 , and a transfer unit  1355 .  
         [0037]     The waster toner storing chamber  1351  temporarily stores the waste toner removed from the photosensitive drum  132  by a cleaning blade  139  which is installed above the photosensitive drum  132 .  
         [0038]     The collection screw  1352  is rotatably installed in the waste toner storing chamber  1351 , and transfers the waste toner stored in the waste toner storing chamber  1351  toward the collection passage  1353 . As shown in  FIG. 3 , a wing  1352   a  is spirally arranged on the collection screw  1352 . Thus, as the collection screw  1352  rotates, the waste toner is transferred to the collection passage  1353  along the lengthwise direction of the collection screw  1352 .  
         [0039]     The collection passage  1353  connects the waste toner storing chamber  1351  and the development chamber  136  so as to transfer the waste toner stored in the waste toner storing chamber  1351 . The collection passage  1353 , as shown in  FIGS. 1 and 2 , is declined from the waste toner storing chamber  1351  down to the development chamber  136 . The waste toner transferred by the collection screw  1352  slides down along the collection passage  1353  by the weight thereof, and is transferred toward the development chamber  136 .  
         [0040]     The transfer screw  1354  is rotatably installed in the development chamber  136 , and transfers the waste toner transferred through the collection passage  1353  to the development chamber  136 . As shown in  FIG. 4 , a wing  1354   b  is spirally formed on a rotation shaft  1354   a  of the transfer screw  1354 .  
         [0041]     Since the development chamber  136  is connected to the toner container  120 , as shown in  FIG. 1 , new toner provided from the toner container  120  is mixed by the transfer screw  1354  with the waste toner transferred through the collection passage  1353 .  
         [0042]     The transfer unit  1355 , as shown in  FIGS. 3 and 4 , is rotatably installed in the collection passage  1353  in a lengthwise direction of the collection passage  1353 , to smoothly transfer the waste toner from the waste toner storing chamber  1351  to the development chamber  136 . The transfer unit  1355  may be a belt  1356  having one end connected to the rotation shaft  1354   a  and the other end supported by an idle shaft  1359  rotatably installed in the collection passage  1353 , having a closed curve shape as a whole.  
         [0043]     A plurality of bosses  1354   c  may be provided at one side of the rotation shaft  1354   a  to protrude in a symmetrical form. A plurality of holes  1357  may be formed in the belt  1356  at a predetermined interval so that the bosses  1354   c  are inserted therein during rotation of the transfer screw  1354 . Accordingly, as the rotation shaft  1354   a  rotates, the bosses  1354   c  are inserted in the holes  1357  so that the belt  1356  rotates with the rotation shaft  1354   a.    
         [0044]     In the present embodiment, although the bosses  1354   c  and the holes  1357  are provided at the rotation shaft  1354   a  and the belt  1356 , respectively, to rotate the belt  1356 , the present invention is not limited thereto, and various modified examples can be applied to rotate the belt  1356 . For example, sawteeth may be formed on the inner circumferential surface of the belt  1356 , and the outer circumferential surfaces of the rotation shaft  1354   a  and the idle shaft  1359 , so that the belt  1356  is rotated as the belt  1356  is engaged with the rotation shaft  1354   a  and the idle shaft  1359 .  
         [0045]     A plurality of protrusions  1358  having a predetermined area may be provided on the outer circumferential surface of the belt  1356  to transfer the waste toner. The protrusions  1358  are preferably, though not necessarily, disposed between the neighboring holes  1357  so as not to overlap the holes  1357 . The protrusions  1358  transfer the waste toner in a separated fashion, and agitate the waste toner to prevent hardening of the waste toner.  
         [0046]     In the present embodiment, although bosses to be inserted in the holes  1357  are not separately provided at the idle shaft  1359 , the present invention is not limited thereto, and bosses may be provided at the idle shaft  1359 , either alternatively or in coexistence with the bosses  1354   c  provided at the rotation shaft  1345   a.    
         [0047]     The exposure unit  150  emits light onto the photosensitive drum  132 , which is charged to a predetermined electric potential, to lower the electric potential of a portion receiving the light to be not more than the predetermined electric potential so as to form the electrostatic latent image. Generally, a laser scanning unit (LSU) is used as the exposure unit  150 .  
         [0048]     The transfer roller  160  is installed to contact the photosensitive drum  132  so as to press the recording medium S passing through a contact portion normally contacting the photosensitive drum  132 . Thus, the toner image formed on the surface of the photosensitive drum  132  is transferred to the recording medium S.  
         [0049]     The fusing unit  170  fuses the toner image on the recording medium S, and includes a heating roller to generate and apply heat to the toner image, and a press roller to press the toner image against the recording medium S.  
         [0050]     The paper eject unit  180  ejects the recording medium S, on which the toner image is fused, out of the main body  101 . As a plurality of rollers are rotated by being engaged with each other, the recording medium S is ejected outside. The recording medium S ejected by the paper eject unit  180  is loaded on a paper receiving plate  181 .  
         [0051]     Referring to  FIGS. 1 through 5 , when the developing unit  130  is installed in the main body  101 , the respective rollers constituting the developing unit  130  may be rotated by being connected to a drive unit (not shown) provided in the main body  101 .  
         [0052]     When the rotation shaft  1354   a  rotates, as the bosses  1354   c  are inserted in the holes  1357  of the belt  1356 , a rotational force is transferred to the belt  1356  so that the belt  1356  rotates in a direction indicated by arrows. While the belt  1356  rotates, the protrusions  1358  transfer the waste toner toward the development chamber  136  so that the waster toner can be prevented from being hardened in the collection passage  1353 .  
         [0053]     As described above, in the developing unit according to the present invention, since the belt, or other movable member, which is rotated by receiving a rotational force from the transfer screw, is installed in the collection passage to transfer waste toner, the waste toner is prevented from being hardened in the collection passage.  
         [0054]     Although a few embodiments of the present invention have been shown and described, it would 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 invention, the scope of which is defined in the claims and their equivalents.