Patent Publication Number: US-8126381-B2

Title: Transfer apparatus and image forming device having the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §119(a) from Korean Patent Application No. 10-2007-8463, filed on Jan. 26, 2007, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present general inventive concept relates to a transfer apparatus and an image forming device having the same. 
     2. Description of the Related Art 
     In general, an image forming apparatus, such as a copier, a printer, a facsimile, and a multi function machine embodying functions of the copier, printer, and facsimile as a single device, has a function, which prints an image on a printing medium. Such an image forming apparatus includes a feeding unit to feed the printing medium, a developing unit to develop an image on an photoconductive medium, a transfer apparatus to transfer the developed image onto the printing medium, a fixing unit to fix the transferred image, and a discharging unit to discharge the printing medium to the outside. Among these units, an example of the transfer unit is illustrated in  FIG. 1 . 
     Referring to  FIG. 1 , a transfer apparatus of a general image forming device includes a transfer belt  10 , which is supported and rotated by a pair of rollers  21  and  22 . The transfer belt  10  receives an image from a photoconductive medium and transfers the received image onto a printing medium while being rotated. At this time, one of the pair of rollers  21  and  22  is a driving roller  21 , which receives a driving force from a driving source, and the other is an idle roller  22 . The idle roller  22  at both ends is supported by an elastic member  30  to apply a tension to the transfer belt  10 . 
     However, the transfer belt  10  generates a shaking or floating movement in an axial direction of the idle roller  22  in rotation. Such a floating movement of the transfer belt  10  in rotation causes a transfer quality to deteriorate. 
     To address such a problem, a method, which forms the idle roller  22  in the form of a crown in which a center and both ends thereof have deferent diameters, or forms a guide projection and a guide groove on an inner side surface of the transfer belt  10  and in a portion of the idle roller  22  corresponding to the guide projection, respectively, was proposed. However, as shapes of the idle roller  22  and/or the transfer belt  10  are changed, a problem occurs, in that fabrication costs are increased and a friction at specific portions is increased to cause the specific portions to wear. 
     Also, a conventional method has been used for additionally installing a separate sensing means and a separate compensating means capable of sensing the movement of the transfer belt  10  and compensating for it. However, fabrication costs for additionally installing the separate sensing means and a separate compensating means are increased. 
     SUMMARY OF THE INVENTION 
     The present general inventive concept provides a transfer apparatus capable of compensating for a floating movement of a transfer belt, and an image forming device having the same. 
     The present general inventive concept also provides a transfer apparatus having a mechanism compensate for a floating movement of a transfer belt, with a low cost and a simple structure, and an image forming device having the same. 
     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 
     The foregoing and/or other aspects and utilities of the present general inventive concept may be achieved by providing an image forming device, including an image forming device body having an image forming unit, and a transfer apparatus to transfer an image formed by the image forming unit onto a printing medium. The transfer apparatus includes a transfer belt, a driving unit to rotate the transfer belt, and at least one regulating unit to regulate a floating movement of the transfer belt and the driving unit thus to be in position. 
     The driving unit may include a plurality of rollers to come in contact with and to rotatably support an inner side surface of the transfer belt. 
     The regulating unit may include a regulating member to interfere with an axial movement of one of the plurality of rollers, and an elastic member disposed between an axis of the one roller and the regulating member to apply an elastic force in a driving direction of the transfer belt. 
     The plurality of rollers may include at least one driving roller to rotatably support one end of the transfer belt and at least one idle roller to rotatably support the other end of the transfer belt. 
     The regulating unit may regulate a floating movement of the idle roller. 
     The regulating member may be disposed to be rotatable between a first position coming in contact with an axis of the idle roller positioned in position and a second position rotated by an axial movement of the idle roller. 
     The regulating member may include a contacting end to come in contact with the axis of the idle roller and a supporting end to move in combination with a movement of the contacting end and to support the elastic member. 
     The contacting end and the supporting end may be in right angles to each other about a rotating axis. 
     The elastic member may press a shaft of the idle roller by a rotating range of the regulating member in the rotating direction of the transfer belt. 
     The foregoing and/or other aspects and utilities of the present general inventive concept may be achieved by providing a transfer apparatus, including a transfer belt, a driving unit to rotate the transfer belt, and at least one regulating unit to regulate a floating movement of the transfer belt and the driving unit to maintain a position thereof. 
     The foregoing and/or other aspects and utilities of the present general inventive concept may also be achieved by providing a transfer apparatus usable with an image forming apparatus, including a transfer belt, a driving unit to rotate the transfer belt, and at least one regulating unit having a regulating member disposed to be movable according to a movement of the driving unit and an elastic member connected between the driving unit and the regulating member to regulate a movement of one of the transfer belt and the driving unit. 
     The movement may include a first movement in a first direction and a second movement in a second direction, and a combination of the regulating member and the elastic member may regulate the first movement and the second movement. 
     The elastic member may control the regulating member to be biased toward the driving unit. 
     The regulating member may include one end connected to the elastic member and another end extended from the one end toward the driving unit to move according to the second movement. 
     The elastic member may generate a first elastic force to the regulating member with respect to the driving unit, and a second elastic force to the driving unit to regulate the second movement. 
     The regulating member may be rotatably disposed to move according to the second movement of the one of the transfer belt and the driving unit; and the elastic member may be elastically connected between the driving unit and the regulating member to control at least one of the first movement and the second movement. 
     The at least one regulating unit may include first and second regulating units disposed opposite sides of the driving unit, the regulating member may include first and second regulating members, and the elastic member may include first and second elastic members to form the first and second regulating units with the first and second elastic members, respectively. 
     The first regulating member may move in a first direction according to the movement, the second regulating member may move in a second direction according to the movement; and the second elastic member may generate an elastic force to the one of the driving unit and the transfer belt in a third direction to regulate the movement. 
     The transfer apparatus may further include an interfering member to restrict the movement of the second regulating member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects of the present general inventive concept will become apparent and more readily appreciated from the following description of the exemplary embodiment, taken in conjunction with the accompanying drawings of which 
         FIG. 1  is a top plan view schematically illustrating a conventional transfer apparatus of a general image forming device; 
         FIG. 2  is a schematic view illustrating a construction of an image forming device having a transfer apparatus according to an exemplary embodiment of the present general inventive concept; 
         FIG. 3  is a top plan view schematically illustrating the transfer apparatus of  FIG. 2 ; and 
         FIGS. 4A and 4B  are top plan views illustrating an operation of regulating a floating movement of a transfer belt illustrated in  FIG. 3 . 
     
    
    
     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 
     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. 
     Referring to  FIG. 2 , an image forming device according to the exemplary embodiment of the present general inventive concept has a feeding unit  110  to feed a printing medium P, a photoconductive medium  120  on which an electrostatic latent image is formed, a developing unit  130  to develop the electrostatic latent image with a developer, a transfer apparatus  200  to transfer the developed image onto the printing medium P, and a fixing unit  140  to fix the image transferred on the printing medium P, which are disposed in an image forming device body  100 . Here, the photoconductive medium  120  and the developing unit  130  form an image forming unit. 
     Since technical constructions and operations of the image forming unit and the feeding unit  110  constructed as described above are well-known in the art, detailed description and illustration thereof will be omitted. 
     Referring to  FIG. 3 , the transfer apparatus  200  of the image forming device, which transfers the image developed on the photoconductive medium  120  onto the printing medium P, includes a transfer belt  210 , a driving unit  220 , and a regulating unit. The regulating may have first and second regulating units  230  and  240 , for example. 
     The transfer belt  210  receives one or more images, which are developed on the photoconductive medium  120  by the developing unit  130 . The one or more developed images overlap each other to form a full image. The images transferred onto the transfer belt  210  are transferred onto the printing medium P as the full image by a backup roller  250 , which rotates while facing the transfer belt  210  to interpose the printing medium P therebetween. Since technical constructions and operations on such an image transfer by the transfer belt  210  are well-known in the art, detailed description and illustration thereof will be omitted. 
     The driving unit  220  includes a plurality of rollers  221  and  222 , which comes in contact with and rotatably supports an inner side surface of the transfer belt  210  to drive or rotate the transfer belt  210 . 
     In the present embodiment, the plurality of rollers  221  and  222  is illustrated as a driving roller  221  and an idle roller  222 . The driving roller  221  rotatably supports one end of the transfer belt  210  and receives a driving force from a driving source (not illustrated). The idle roller  222  rotatably supports the other end of the transfer belt  210 . Here, the driving roller  221  rotates while facing the backup roller  250  to interpose the transfer belt  210  therebetween. 
     Each of the driving roller  221  and the idle roller  222  can be provided in plural to rotate the transfer belt  210 . It is possible that one of the driving roller  221  and the idle roller  222  is provided in plural to rotate the transfer belt  210   
     The regulating units  230  and  240  regulate a floating movement of the transfer belt  210  and the driving unit  220 . Here, since the regulating units  230  and  240  are correspondingly disposed to one shaft  222   a  and the other shaft  222   b  projecting from both ends of the idle roller  222  to regulate a floating movement of the idle roller  222  of the driving unit  220 . The first and second regulating units  230  and  240  include first and second regulating members  231  and  241  and first and second elastic members  232  and  242 , respectively. 
     The floating movement may include a shaking movement of at least one of the driving roller  221  and the idle roller  222  and/or the transfer unit  210 , and/or a movement generating during moving or rotating the transfer belt  210  in a rotational direction and an axial direction of the at least one of the driving roller  221  and the idle roller  222 . 
     The first and second regulating members  231  and  241  interfere with an axial movement of the idle roller  222 . To be specific, the first and second regulating members  231  and  241  come in contact with the one shaft  222   a  and the other shaft  222   b  of the idle roller  222  and rotate about first and second rotating shafts  231   c  and  241   c  by the axial movement of the idle roller  222 , respectively. 
     When the first and second rotating shafts  231   c  and  241   c  may be formed on the first and second regulating members  231  and  241 , respectively, the first and second rotating shafts  231   c  and  241   c  are rotatably supported by the main body  100 . When the first and second regulating members  231  and  241  are disposed to rotate with respect to the first and second rotating shafts  231   c  and  241   c , respectively, the first and second rotating shafts  231   c  and  241   c  are fixedly supported by the main body  100  or mounted on the main body  100 . 
     The one shaft  222   a  and the other shaft  222   b  may be formed on the opposite ends of the idle roller  222 , may rotate together with the idle roller  222 , and may have rotation axes parallel to a rotational axis of the idle roller. 
     It is possible that the rotation axes of the one shaft  222   a  and the other shaft  222   b  may be disposed on the rotational axis of the driving roller  221  or another idle roller, and the first and second regulating units  230  and  240  are disposed to correspond to the one shaft  222   a  and the other shaft  222   b  thereof. 
     As illustrated in  FIGS. 3 and 4A , the first and the second regulating members  231  and  241  are rotatable between a first position where the first and the second regulating members  231  and  241  come in contact with corresponding ones of the one shaft  222   a  and the other shaft  222   b  of the idle roller  222  which are positioned in a normal position and a second position where the first and the second regulating members  231  and  241  are moved or rotated by the axial movement of the idle roller  222  which is positioned in an abnormal position, respectively. 
     Also, the first and the second regulating members  231  and  241  include first and second contacting ends  231   a  and  241   a  and first and second supporting ends  231   b  and  241   b , respectively. The first and second contacting ends  231   a  and  241   a  come in contact with corresponding ones of the one shaft  222   a  and the other shaft  222   b  of the idle roller  222 , respectively. The first and second supporting ends  231   b  and  241   b  move according to a movement of the first and the second contacting end  231   a  and  241   a  and support first and second elastic members  232  and  242 , respectively. Here, the first and second contacting ends  231   a  and  241   a  and the first and second supporting ends  231   b  and  241   b  are in right angles with respect to each other about the first and the second rotating shafts  231   c  and  241   c , respectively. 
     The first and second elastic members  232  and  242  are disposed between the one axis  222   a  and the other axis  222   b  of the idle roller  222  and corresponding ones of the first and second supporting ends  231   b  and  241   b  the first and second regulating members  231  and  241  to apply elastic forces in a rotating direction of the transfer belt  210  or in a direction to move the idle roller  222  away from the driving roller  221 . The transfer belt  210  is rotated in a direction of arrow illustrated in  FIG. 3 . 
     That is, the first elastic member  232  is disposed between the first supporting end  231   b  and the one shaft  222   a  of the idle roller  222 , and the second elastic member  242  is disposed between the second supporting end  241   b  and the other shaft  222   b  of the idle roller  222 . The elastic forces of the first and the second members  232  and  242  cause the transfer belt  210  to be tensioned between the driving roller  221  and the idle roller  222 . 
     As illustrated in  FIGS. 4A and 4B , the first and second elastic members  232  and  242  presses the one shaft  222   a  and the other shaft  222   b  of the idle roller  222  by a rotating range R of the first and second regulating members  231  and  241  in the rotating direction of the transfer belt  210 , respectively. 
     To be more specific, if the contacting end  231   a  of the first regulating member  231  is rotated to the second position by the rotating range R while coming in contact with the one shaft  222   a  of the idle roller  222  moved in a direction of arrow A, as illustrated in  FIG. 4A , the first supporting end  231   b  extended in a right angle about first rotating axis  231   c  from the first contacting end  231   a  is also rotated by the rotating range R. Then, the first elastic member  232  supported on the first supporting end  231   b  moves the one shaft  222   a  of the idle roller  222  in a direction of arrow C with its elastic force. 
     Here, in combination with the movement of the one shaft  222   a  of the idle roller  222  by the first elastic member  232 , the other shaft  222   b  of the idle roller  222  moves in a direction of arrow D opposite to the direction of arrow C. 
     To interfere with a moving range of the first and second regulating members  231  and  241  in the direction of arrow D as illustrated in  FIG. 4B , first and second interfering member  233  and  243  are installed. To be more specific, the first and second interfering members  233  and  243  interfere with movements of the first and the second supporting ends  231   b  and  241   b  in the direction of arrow D, so that even though the one shaft  222   a  or the other shaft  222   b  of the idle roller  222  is floatingly moved in the direction of arrow D, the first and the second regulating members  231  and  241  are not rotated, but maintained in the first position. 
     That is, the first and the second regulating members  231  and  241  are returned from the second position to the first position, and the idle roller  222  is returned to its original position with respect to the driving roller  221 , thereby controlling the transfer belt  210  to be in a desired position to transfer the formed image from the photosensitive medium  120  to the printing medium P. 
     Hereinafter, a regulating operation of the transfer apparatus of the image forming device constructed as described above will be explained with reference to  FIGS. 3 through 4B . 
     As illustrated in  FIG. 3 , the transfer belt  210  is rotated in a direction of illustrated arrow with at both ends supported by the driving roller  221  and the idle roller  222 . At this time, as illustrated in  FIG. 4A , if the transfer belt  210  is moved in a direction of arrow A while rotating without a separate fixing unit, the idle roller  222  is also moved in the direction of arrow A along with the transfer belt  210  by a friction between the idle roller  222  and the inner side surface of the transfer belt  210 . 
     With such a movement of the idle roller  222  in the direction of arrow A, the first contacting end  231   a  of the first regulating member  231 , which is in the first position coming in contact with the one shaft  222   a  of the idle roller  222 , is rotated by a rotating range R. According to this, the first supporting end  231   b  connected at a right angle about the first rotating axis  231   c  to the first contacting end  231   a  is rotated by the rotating range R, and thus the first regulating member  231  is rotated to the second position. At this time, the first elastic member  232  supported by the first supporting end  231   b  presses the one shaft  222   a  of the idle roller  222  in a direction of arrow C, as illustrated in  FIG. 4B . 
     The other shaft  222   b  of the idle roller  222  is moved in a direction of arrow D by the one shaft  222   a  moved in the direction of arrow C. At this time, since the second supporting end  241   b  is interfered with the second interfering member  243 , only the second elastic member  242  is compressed, and the second regulating member  241  is not rotated. As a result, the idle roller  222  is inclined in a given angle, so that the transfer belt  210  is moved in a direction of arrow B toward the other axis  222   b , which is relatively more inclined. 
     Due to a restoration of the elastic force of the compressed second elastic member  242  with the movement of the transfer belt  210  in the direction of arrow B, the idle roller  222  is returned to a previous position, i.e., an original position. At this time, the first and second regulating members  231  and  241  are also rotated due to restored elastic forces of the first and second elastic members  232  and  242  and interferences of the one shaft  222   a  and the other shaft  222   b  of the idle roller  222 , and thus returned to the first position. 
     In the present embodiment, the first and second regulating units  230  and  240  have been explained and illustrated as regulating the movements of the idle roller  222  and the transfer belt  210  in the direction of arrow A. However, when the first and second regulating units  230  and  240  regulate the movements of the idle roller  222  and the transfer belt  210  in the direction of arrow B, operations thereof are carried out in the same principle or manner as those described above. 
     As apparent from the foregoing description, according to the exemplary embodiment of the present general inventive concept, the transfer apparatus and the image forming device having the same regulate the idle roller of the driving unit, which floatingly moves along with the transfer belt by the friction therewith. Accordingly, the transfer apparatus and the image forming device having the same according to the exemplary embodiment of the present invention can regulate the floating movement of the transfer belt and thus position the transfer belt in position with a simple structure, thereby allowing fabrication costs to reduce and allowing a transfer quality to improve. 
     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.