Abstract:
An image forming apparatus is provided. The image forming apparatus, in a case in which a toner on a transfer belt is checked through a sensing unit, is capable of preventing a rotation of a guide roller, which is configured to guide the transfer belt, by use of a regulation device, so that a check error occurring due to vibration of the guide roller is reduced. Thus, the toner on the transfer belt is checked with increased accuracy and precision.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to, and claims priority to, Korean Patent Application No. 10-2013-0032128, filed on Mar. 26, 2013 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Embodiments of the present disclosure relate to an image forming apparatus having a sensing unit configured to check a toner on a transfer belt. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, an image forming apparatus is an apparatus designed to form an image on a printing medium. Types of image forming apparatus include a printer, a copy machine, a facsimile, and a multifunctional device having the functionalities of two or more of the printer, the copy machine, and the facsimile. 
         [0006]    Such an image forming apparatus may include a body provided at one side thereof with an opening, and a side cover rotatably installed at the body to open and close the opening. The body may be provided at an inside thereof with a plurality of developing units to develop electrostatic latent images to visible images through toners according to colors, an exposure device to form an electrostatic latent image on a photoconductor of each of the developing units by irradiating light onto the photoconductor of the developing units, a transfer device to transfer the visible image developed on the photoconductor to the printing medium, and a fusing device to fix the toner to the printing medium. 
         [0007]    The transfer device includes a transfer belt to receive a toner from the plurality of developing units to transfer the toner to the printing medium, a driving roller and a driven roller that may be disposed at an inner side of the transfer belt to rotate the transfer belt, and a guide roller to guide a portion of the transfer belt which moves toward the driving roller. A sensing unit may be disposed at a lower side of one portion of the transfer belt to check the toner on the transfer belt. 
       SUMMARY 
       [0008]    Therefore, it is an aspect of the present disclosure to provide an image forming apparatus capable of checking a toner on a transfer belt through a sensor unit in a precise and an accurate manner. 
         [0009]    Additional aspects of the disclosure 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 disclosure. 
         [0010]    In accordance with an embodiment of the present disclosure, an image forming apparatus includes a developing unit, a transfer belt, a guide roller and a regulation device. The developing unit may be configured to develop an electrostatic latent image to a visible image through a toner. The transfer belt may be configured to transfer the visible image developed by the developing unit on a printing medium. The guide roller may be configured to guide the transfer belt by supporting one side of an inner surface of the transfer belt. The regulation device may be configured to regulate a rotation of the guide roller. 
         [0011]    The image forming apparatus may include a sensing unit configured to check a tone transferred on the transfer belt. The regulation device may restrict the guide roller from rotating when the sensing unit checks the toner transferred on the transfer belt. 
         [0012]    The guide roller may include a roller part and a first coupling part. The roller part may be configured to support the inner surface of the transfer belt. The first coupling part may be provided at one side of the roller part so as to be connected to the regulation device. The regulation device may include a regulation member installed so as to be movable in a first longitudinal direction. The regulation member may be provided at one side surface thereof with a second coupling part engaged with the first coupling part. 
         [0013]    The regulation device may include an elastic member configured to elastically support the regulation member in a second longitudinal direction opposite to the first longitudinal direction. 
         [0014]    The regulation device may include a driving motor, a worm being rotated by the driving motor, and a worm wheel teethed with the worm. The worm wheel may be provided at one side surface thereof with a first cam part having a crest and a trough alternately formed in a circumferential direction of the first cam part. The regulation member may be provided at other side surface thereof with a second cam part having a crest and a trough alternately formed in a circumferential direction of the second cam part so as to correspond to the first cam part. 
         [0015]    The image forming apparatus may include a driving roller and a driven roller that may be disposed at opposite sides of inside of the transfer belt. The guide roller may guide a portion of the transfer belt that moves toward the driving roller. The sensing unit may check a portion of the transfer belt that moves toward the guide roller. 
         [0016]    The image forming apparatus may include a transfer device frame to which the regulation member is movably installed. The guide roller may include a locking part configured to restrict a rotation of the guide roller by being locked with the transfer device frame. The transfer device frame may include a locking protrusion configured to be locked with the locking part. 
         [0017]    The worm wheel may be provided at an other side surface thereof with a sensed part extending in a circumferential direction of the worm wheel. The regulation device may include a position detecting sensor to sense the sensed part. 
         [0018]    The position detecting sensor may include a light emitting part and a light receiving part that may be disposed while being spaced apart from each other. The sensed part may pass through an area between the light emitting part and the light receiving part according to rotation of the worm wheel. 
         [0019]    In accordance with an aspect of the present disclosure, an image forming apparatus includes a developing unit, a transfer belt, a guide roller and a regulation member. The developing unit may be configured to develop an electrostatic latent image to a visible image through a toner. The transfer belt may be configured to transfer the visible image developed by the developing unit on a printing medium. The guide roller may be configured to guide the transfer belt by supporting one side of an inner surface of the transfer belt. The regulation member may be movably installed and configured to restrict a rotation of the guide roller by being coupled to the guide roller depending on a position thereof while in motion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    These and/or other aspects of the disclosure will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
           [0021]      FIG. 1  illustrates an image forming apparatus in accordance with an embodiment of the present disclosure. 
           [0022]      FIG. 2  illustrates a transfer device and a regulation device of an image forming apparatus in accordance with an embodiment of the present disclosure. 
           [0023]      FIG. 3  illustrates a regulation device of an image forming apparatus in accordance with an embodiment of the present disclosure. 
           [0024]      FIG. 4  is an exploded view illustrating a regulation device of an image forming apparatus in accordance with an embodiment of the present disclosure. 
           [0025]      FIG. 5  illustrates an exemplary state before a guide roller is regulated by a regulation device of an image forming apparatus in accordance with an embodiment of the present disclosure. 
           [0026]      FIG. 6  illustrates an exemplary state of a guide roller regulated by a regulation device of an image forming apparatus in accordance with an embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
         [0028]    As illustrated in  FIG. 1 , an image forming apparatus in accordance with an embodiment of the present disclosure includes a body  10  forming an external appearance of the image forming apparatus, a printing medium storage unit  20  to store printing medium, a plurality of developing units  30 C,  30 M,  30 Y and  30 K to develop electrostatic latent images to visible images according to colors by use of toner, an exposure unit  40  to form electrostatic latent images by irradiating light onto photoconductors  31  of the charged developing units  30 C,  30 M and  30 Y and  30 K, a transfer device  50  to transfer the visible image formed on the photoconductors  31  to the printing medium, which is being delivered from the printing medium storage unit  20 , a fusing unit  60  to fix the toner, which is transferred to the printing medium, to the printing medium, and a sensing unit  70  to check the toner on a transfer belt  51  of the transfer device  50 . 
         [0029]    The body  10  may be provided at an upper portion thereof with a loading part  10   a  on which the printing medium completed with the image formation is loaded. A discharge port  10   b  may be provided at one side of the loading part  10   a  to allow the printing medium completed with the image formation to be discharged therethrough. An opening  10   c  may be provided at one side of the body  10  to allow repair of components or replacement of expendable materials inside the body  10 . A side cover  11  may be included having a lower end rotatably installed at the body  10  so as to open and close the opening  10   c  while rotating on the lower end thereof. 
         [0030]    The printing medium storage unit  20  includes a printing medium cassette  21  movably installed at the body  10 , a knock-up plate  22  to load the printing media while being disposed in the printing medium cassette  21 , and a knock up spring  23  to elastically support the knock-up plate  22 . 
         [0031]    Each of the developing units  30 C,  30 M,  30 Y and  30 K includes a photoconductor  31 , on a charged surface of which an electrostatic latent image is formed by the exposure unit  40 , a developing roller  32  to supply toner to the photoconductor  31 , and a charging unit  33  to charge the surface of the photoconductor  31 . 
         [0032]    The developing units  30 C,  30 M,  30 Y and  30 K in accordance with an embodiment of the present disclosure include four developing units  30 C,  30 M,  30 Y and  30 K each storing one of toners of cyan C, magenta M, yellow Y and black K at an inside thereof, to develop one of cyan C, magenta M, yellow Y and black K colors. The four developing units  30 C,  30 M,  30 Y and  30 K may be disposed at a lower portion of the transfer device  50  side by side. 
         [0033]    The exposure unit  40  forms the electrostatic latent images on the surfaces of the photoconductors  31  by irradiating light including image information to the photoconductors  31  provided at the developing units  30 C,  30 M,  30 Y and  30 K, respectively. 
         [0034]    The transfer device  50  includes a transfer belt  51  on which visible images developed on the photoconductors  31  of the developing units  30 C,  30 M,  30 Y and  30   k  are transferred in an overlapping manner, a driving roller  52  and a driven roller  53  disposed at opposite sides of inside the transfer belt  51  to rotate the transfer belt  51 , a plurality of first transfer rollers  54  disposed opposite to the photoconductors  31  of the developing units  30 C,  30 M,  30 Y and  30 K, respectively, while interposing the transfer belt  51  therebetween, such that the visible images formed on the photoconductors  31  are transferred to the transfer belt  51 , a guide roller  56  disposed on a path between the first transfer rollers  54  and the driving roller  52  and configured to guide a portion of the transfer belt  51  moving toward the driving roller  52  by supporting an inner surface of the transfer belt  51 , and a transfer device frame  57  on which both ends of each of the first transfer rollers  54 , the driving rollers  52  and the driven rollers  53  are rotatably installed. 
         [0035]    A second transfer roller  55  may be disposed at the side cover opposite to the driving roller  52  while interposing the transfer belt  51  therebetween, to press the printing medium toward the transfer belt  51  to transfer the visible image of the transfer belt  51  to the printing media. 
         [0036]    The fusing unit  60  includes a heating roller  61  to generate heat, and a pressing roller  62 , an outer circumferential surface of which is formed of elastically deformable material to press the printing medium onto an outer circumferential surface of the heating roller  61 . 
         [0037]    At the body  10 , a pick-up roller  12  may be disposed at an upper side of the printing medium storage unit  20  to pick up the printing media loaded on the knock-up plate  22  one by one, a delivery roller  13  to guide the printing medium, which is picked up by the pick-up roller  12 , upward, and a discharge roller  14  disposed at an upper side of the fusing unit  60  while being adjacent to the discharge port  10   b  to allow the printing medium passing through the fusing unit  60  to be discharged through the discharge port  10   b.    
         [0038]    The body  10  may be provided at an inside thereof with frames configured to install and support various elements. The frames include a body frame  15 , which may be disposed at a lower portion of an inner side of the opening  10   c  and on which the sensing unit  70  may be installed. 
         [0039]    The sensing unit  70  may be disposed at a lower side of the transfer belt  51  and installed opposite to a lower surface of the transfer belt  51  to check the toner on the transfer belt  51 . The sensing unit  70  in accordance with an embodiment of the present disclosure checks a portion of the transfer belt  51  passing through the first transfer rollers  54  and moving toward the guide roller  56 . 
         [0040]    The guide roller  56  includes a roller part  56   a  provided in a cylindrical shape to support the inner surface of the transfer belt  51 , a first coupling part  56   b  provided at one side of the roller part  56   a  so as to be coupled to a second coupling part  84   a  of a regulation device  80 , and a shaft part  56   c  connecting the roller part  56   a  to the first coupling part  56   b . The guide roller  56  may be configured to rotate by receiving a force from the transfer belt  51  through the roller part  56   a , which makes contact with the inner surface of the transfer belt  51 , according to the movement of the transfer belt  51 . In a rotation of the guide roller  56 , the guide roller  56  is usually vibrated. 
         [0041]    The sensing unit  70  may be configured to check a portion of the transfer belt  51  passing through the first transfer rollers  54  and moving toward the guide roller  56 . In a case in which the guide roller  56  vibrates while rotating, a portion of the transfer belt  51  adjacent to the guide roller, that is, the portion of the transfer belt  51  to be sensed by the sensing unit  70  may be vibrated together with the guide roller  56 , and may result in an inaccurate sensing by the sensing unit  70 . 
         [0042]    As illustrated in  FIGS. 2 and 3 , the image forming apparatus includes the regulation device  80  configured to restrict the rotation of the guide roller  56  while the toner on the transfer belt  51  is being checked by the sensing unit  70 . 
         [0043]    As illustrated in  FIG. 4 , the regulation device  80  includes a driving motor  81  to generate a rotating force, a worm  82  being rotated by the driving motor  81 , and a worm wheel  83  being rotated according to the rotation of the worm  82  while being teethed with the worm  82 . A regulation member  84  may be installed so as to rotate in a first circumferential direction  100  and configured to restrict the rotation of the guide roller  56  by being coupled to a first coupling part  56   b  while rotating in the first circumferential direction  100  according to a rotation of the worm wheel  83 . An elastic member  85  may elastically support the regulation member  84  in a second longitudinal direction  400  opposite to a first longitudinal direction  300 . Accordingly, the regulation member  84  may be coupled to the guide roller  56  by moving in the first longitudinal direction  300  so as to limit the rotation of the guide roller  56 , and is separated from the guide roller  56  while moving in a second longitudinal direction  400  opposite to the first longitudinal direction  300  so as to allow the rotation of the guide roller  56 . 
         [0044]    The worm wheel  83  may be provided at one side surface thereof with a first cam part  83   a  having a crest and a trough alternately formed in a circumferential direction of the first cam part  83   a . The worm wheel  83  may be provided at the other side surface thereof with a sensed part  83   b  that is provided in an arc shape and extends in a circumferential direction of the worm wheel  83 . The regulation device  80  includes a position detecting sensor  86  including a light emitting part  86   a  and a light receiving part  86   b . The sensed part  83   b  in accordance with an embodiment of the present disclosure includes one pair of sensed parts  83   b  being spaced apart from each other. The sensed parts  83   b  may be configured to pass through an area between the light emitting part  86   a  and the light receiving part  86   b.    
         [0045]    Accordingly, in a case in which the sensed part  83   b  is disposed at an area between the light emitting part  86   a  and the light receiving part  86   b  of the position detecting sensor  86 , the sensed part  83   b  may be sensed by the position detecting sensor  86 . In a case in which the sensed part  83   b  is not in the area between the light emitting part  86   a  and the light receiving part  86   b  of the position detecting sensor  86 , the sensed part  83   b  is not sensed by the position detecting sensor  86 . In this manner, a rotation position of the worm wheel  83  and a position of the first cam part  83   a  provided on the worm wheel  83  may be checked. 
         [0046]    The regulation member  84  may be installed to pass through the transfer device frame  57  so as to be movable in the first longitudinal direction and the second longitudinal direction. The regulation member  84  may be provided at one side surface thereof with a second coupling part  84   a  engaged with the first coupling part  56   b  of the guide roller  56 , and provided at the other side surface thereof with a second cam part  84   b  having a crest and a trough alternately formed in a circumferential direction of the second cam part  56   b  so as to correspond to the first cam part  83   a . In accordance with an embodiment of the present disclosure, each of the first cam part  83   a  and the second cam part  84   b  may have two crests and two troughs in an alternating manner, so that the regulation member  84  moves in the first longitudinal direction according to the interaction between the first cam part  83   a  and the second cam part  84   b.    
         [0047]    The regulation member  84  includes a locking part  84   c  that is configured to restrict a rotation of the regulation member  84  by being locked with the transfer device frame  57 , and the transfer device frame  57  includes a locking protrusion  57   a  that is provided at a position corresponding to the locking part  84   c  so as to be locked with the locking part  84   c . Accordingly, the regulation member  84  is installed at the transfer device frame  57  so as to be movable in the first and second longitudinal directions while being prevented from rotating, so that the force transmitted to the second cam part  84   b  in a circumferential direction through the first cam part  83   a  is converted to have the first longitudinal direction as an active direction of force, which leads to the regulation member  84  moving in the first longitudinal direction. 
         [0048]    The elastic member  85  has one end supported by the transfer device frame  57 , and the other end supported by the locking part  84   c  of the regulation member  84 , thereby elastically supporting the regulation member  84  in the second longitudinal direction. 
         [0049]    An exemplary operation of an image forming apparatus in accordance with the present disclosure is described with reference to the accompanied drawings in detail. 
         [0050]    In a state that the toner on the transfer belt  51  is not checked through the sensing unit  70 , as illustrated in  FIG. 5 , the crest of the first cam part  83   a  may be inserted into the trough of the second cam part  84   b , and the crest of the second cam part  84   b  may be inserted into the trough of the first cam part  83   a . Thus, the regulation member  84  is kept in a state moved in the second longitudinal direction  400 , by an elastic restoring force of the elastic member  85 . 
         [0051]    Accordingly, the second coupling part  84   a  is kept in a state of being spaced apart from the first coupling part  56   b , and the guide roller  56  guides the transfer belt  51  while rotating according to the movement of the transfer belt  51 . 
         [0052]    In a state that the toner on the transfer belt  51  is checked through the sensing unit  70 , as illustrated in  FIG. 6 , the worm  82  and the worm wheel  83  are rotated by the driving motor  81 , and the first cam part  83   a  provided at the worm wheel  83  transmits force to the regulation member  84  through the second cam part  84   b  according to the rotation of the worm wheel  83 , and thus the regulation member  84  is moved in the first longitudinal direction  300 . 
         [0053]    In this case, the worm wheel  83  may be rotated at a predetermined angle at which the crest of the first cam part  83   a  makes contact with the crest of the second cam part  84   b . The rotation of the predetermined angle may be determined by the sensed part  83   b  and the position detecting sensor  86 . 
         [0054]    As the worm wheel  83  rotates at the predetermined angle, the regulation member  84  moves in the first longitudinal direction, and accordingly, the second coupling part  84   a  provided at the regulation member  84  is coupled to the first coupling part  56   b  of the guide roller  56 . The locking part  84   c  and the locking protrusion  57   a  prevent the regulation member  84  from rotating, and therefore, in the state of the first coupling part  56   b  coupled to the second coupling part  84   b , the guide roller  56  is also prevented from rotating and stops rotating. 
         [0055]    Accordingly, in a state that the sensing unit  70  checks the toner on the transfer belt  51 , the guide roller  56  does not rotate, so that vibration occurring during a rotation of the guide roller  56  is not generated, thereby precisely and accurately checking the toner on the transfer belt  51  through the sensing unit  70 . 
         [0056]    When a toner on the transfer belt is checked through the sensing unit, the guide roller is restricted from rotating by way of a regulation device, so that vibration occurring during a rotation of the guide roller is prevented from exerting influence on checking the toner on the transfer belt, and thus the toner on the transfer belt is precisely and accurately checked. 
         [0057]    Although a few embodiments of the present disclosure 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 disclosure, the scope of which is defined in the claims and their equivalents.