Patent Publication Number: US-7715751-B2

Title: Cleaning apparatus, and transfer unit and image forming apparatus including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims priority under 35 U.S.C. § 119(a) from Korean Patent Application No. 2007-1112 filed Jan. 4, 2007, and Korean Patent Application No. 2007-22922, filed Mar. 8, 2007, in the Korean Intellectual Property Office, the entire disclosures of which are hereby incorporated in their entirety by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present general inventive concept relates to an image forming apparatus. More particularly, the present general inventive concept relates to a cleaning apparatus having an improved structure to remove toner remaining on a transfer medium, and a transfer unit and an image forming apparatus including the same. 
   2. Description of the Related Art 
   Generally, an image forming apparatus in which an electrophotographic process is used, for example, a laser beam printer or a copier, develops an electrostatic latent image formed on a photosensitive medium using toner, and transfers the developed image onto a printing medium through a transfer unit to output a desired image. 
   The transfer unit includes a belt which is installed between at least two rollers and rotates following a regular cycle. The belt is provided so as to be in contact with the outer circumference of at least one photosensitive medium, and the image developed on the photosensitive medium is thus transferred to the belt. 
   The belt cleaning apparatus removes unnecessary toner remaining on the belt after an image primarily transferred to the belt is secondarily transferred onto paper, and accordingly keeps the belt in a clear state. 
     FIG. 1  is a view schematically showing a general belt cleaning apparatus. As illustrated in  FIG. 1 , a belt  1  is wound around a roller  2  and rotates following a regular cycle. Additionally, a leading end of a cleaning blade  3 , which is mounted on a blade bracket  4 , is in contact with the belt  1  wound around the roller  2 . Accordingly, the toner remaining on the belt  1  is removed by the cleaning blade  3 . 
   The blade bracket  4  is constituted to move to a first position and a second position by a cam (not illustrated) so that the cleaning blade  3  can be selectively in contact with the belt  1 . The first position is a position in which the cleaning blade  3  is in contact with the belt  1 , as illustrated in  FIG. 1 , and the second position (not illustrated) is a position in which the cleaning blade  3  is separated from the belt  1 . 
   When toner image formed on the photosensitive medium is transferred to the belt  1 , or toner image of the belt  1  is transferred onto the printing medium, the cleaning blade  3  may be separated from the belt  1  via the blade bracket  4  being placed in the second position. Additionally, when the transferring process is completed, the blade bracket  4  may be moved to the first position by the cam, and thus the cleaning blade  3  is placed in contact with the belt  1  to remove non-transferred toner thereon. 
   However, in the typical belt cleaning apparatus as described above, since the cam enables the cleaning blade  3  be in contact with or separated from the belt  1  by applying a relatively large force, the leading end of the cleaning blade  3  may be damaged or the cleaning blade  3  may be bent. If the cleaning blade  3  is damaged or bent, it can no longer remove toner remaining on the belt. In this situation, it would be required to replace or repair the cleaning blade. 
   SUMMARY OF THE INVENTION 
   The present general inventive concept provides a cleaning apparatus which prevents a cleaning blade from being damaged and turned over by having an improved contact structure between the cleaning blade and a transfer medium. 
   The present general inventive concept also provides a transfer unit and an image forming apparatus including the cleaning apparatus, in which a cleaning blade is brought in contact with a transfer medium through two stations to prevent damage to the cleaning blade, thereby achieving improved durability of the cleaning blade and enabling miniaturization of the cleaning blade by increasing the freedom of design. 
   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 a cleaning apparatus including a blade arm, which is installed adjacent to a transfer medium, to move to a first position and a second position, a cleaning blade, which is supported by the blade arm, to be in contact with the transfer medium when the blade arm moves to the first position, and a pressure unit to bias the cleaning blade towards the transfer medium. 
   The blade arm may pivot at a first hinge point, and may further include a driving cam to rotate and move the blade arm to the first and second positions. 
   The cleaning blade may be installed on the blade arm to pivot at a second hinge point. 
   The pressure unit may include a blade bracket which is installed between the first and second hinge points, and a spring which is interposed between a support bracket at the first hinge point and the blade bracket. 
   The foregoing and/or other aspects and utilities of the present general inventive concept may be achieved by providing a transfer unit of an image forming apparatus, the transfer unit including a transfer medium to receive an image developed on a photosensitive medium while rotating in a regular cycle and in contact with an outer circumference of at least one photosensitive medium, a transfer roller to transfer the image transferred onto the transfer medium to a printing medium, and a cleaning apparatus, as described above, to remove toner that is not transferred onto the printing medium and that remains on the transfer medium. 
   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 at least one photosensitive medium on which an electrostatic latent image is formed, a developing unit to develop the electrostatic latent image formed on the photosensitive medium, a transfer unit, as described above, to transfer the image developed on the photosensitive medium to a printing medium, a fixing unit to fix the image transferred onto the printing medium, and a discharging unit to discharge the printing medium on which the image is fixed. 
   The foregoing and/or other aspects and utilities of the present general inventive concept are also achieved by providing an apparatus to clean a continuous belt including a blade arm to oscillate over a predetermined period associated with a rotation rate of the belt, and a cleaning blade elastically coupled to the blade arm and biased against the belt over a predetermined interval in the period. 
   The foregoing and/or other aspects and utilities of the present general inventive concept are also achieved by providing a transfer unit of an image forming apparatus including a continuous belt to carry toner applied to an electrostatic image to a print medium path of the image forming apparatus, a blade arm to oscillate over a predetermined period associated with a rotation rate of the belt, and a cleaning blade coupled to the blade arm and biased against the belt over a predetermined interval in the period. 
   The foregoing and/or other aspects and utilities of the present general inventive concept are also achieved by providing an image forming apparatus including a photosensitive medium to receive an electrostatic latent image, a print medium path conveying print media therethrough, a developing unit to apply toner to the photosensitive medium to form a developed image, a continuous belt to receive the developed image thereon and to convey the developed image to the print medium path, a fixing unit to adhere the developed image to a print medium in the print medium path, a blade arm to oscillate over a period corresponding to a rate at which the developed image is received on the belt, and a cleaning blade coupled to the blade arm and biased against the belt over a predetermined interval in the period. 
   The foregoing and/or other aspects and utilities of the present general inventive concept are also achieved by providing a method to clean a continuous belt including rotating the belt at a predetermined rotation rate, contacting the belt with a cleaning blade at least once per rotation of the belt, and biasing the cleaning blade against the belt for a predetermined interval subsequent to the cleaning blade contacting the belt. 
   The foregoing and/or other aspects and utilities of the present general inventive concept are also achieved by providing an image forming method including applying toner to a photosensitive medium on which a latent image has been formed to form a developed image, positioning a cleaning blade to be removed from a transfer belt and transferring the developed image to the transfer belt, transferring the developed image to a printable medium, positioning the cleaning blade proximal to the transfer belt, and biasing the cleaning blade against the transfer belt to remove toner therefrom upon the developed image on the transfer belt being transferred to the printable medium. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     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: 
       FIG. 1  is an exemplary view schematically illustrating a general belt cleaning apparatus; 
       FIGS. 2 and 3  are views respectively illustrating a position in which a cleaning blade is in contact with a belt and a position in which the cleaning blade is separated from the belt, to explain the configuration and operation of a belt cleaning apparatus according to an exemplary embodiment of the present general inventive concept; 
       FIG. 4  is an enlarged view illustrating the pressure structure and operation of the cleaning blade of the exemplary embodiment of the present general inventive concept; and 
       FIG. 5  is an exemplary view schematically illustrating a transfer unit employing the belt cleaning apparatus according to an exemplary embodiment of the present general inventive concept, and an image forming apparatus including the transfer unit. 
   

   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. 
     FIGS. 2 and 3  are views illustrating the configuration and operation of a belt cleaning apparatus according to an exemplary embodiment of the present general inventive concept. Specifically,  FIG. 2  is a view illustrating a position in which a cleaning blade is in contact with a belt, and  FIG. 3  is a view illustrating a position in which the cleaning blade is separated from the belt. 
   In  FIGS. 2 and 3 , a transfer unit  10  includes a belt  20  and a belt cleaning apparatus  30 . 
   The belt  20  may be supported by at least two rollers  21  and  22  (referring to  FIG. 5 ) and rotates following to a regular cycle. Additionally, the belt  20  may be in contact with the outer circumference of at least one photosensitive medium  80  (referring to  FIG. 5 ), and thus toner image developed on the photosensitive medium  80  may be transferred to the belt  20 . 
   Referring to  FIG. 5 , a transfer roller  90  may be installed so as to be in contact with the exterior of the belt  20 , and the image primarily transferred to the belt  20  may be secondarily transferred onto a printing medium P which passes between the transfer roller  90  and belt  20 . 
   The belt cleaning apparatus  30  according to an exemplary embodiment of the present general inventive concept removes superfluous toner remaining on the belt  20 , that is, toner which is not transferred onto the printing medium P and that remains on the belt  20 . The belt cleaning apparatus  30  may include a blade arm  40 , a cleaning blade  50 , a driving cam  60 , and a pressure unit  70 . 
   The blade arm  40  may be mounted adjacent to the belt  20  to pivot at a first hinge point H 1 . The blade arm  40  may oscillate between at least two positions, that is, a first position and a second position. The first position may be a position in which the cleaning blade  50  is in contact with the belt  20 , and the second position may be a position in which the cleaning blade  50  is separated from the belt  20 . 
   The cleaning blade  50  may be connected to the blade arm  40  through a support bracket  42 . As the blade arm  40  moves to the first position, a leading end of the cleaning blade  50  comes in contact with the belt  20 , which is referred to herein as the “first station” of the cleaning blade  50 . 
   The driving cam  60  may be eccentric to move the blade arm  40  between the first and second positions by actuating the blade arm  40 . The driving cam  60  and the interaction thereof with the blade arm  40  imposes an oscillation of the blade arm  40  having a period corresponding to the image forming rate of the image forming apparatus implementing the present general inventive concept. 
   The cleaning blade  50  may be pivoted on the support bracket  42  about a second hinge point H 2  and biased towards the belt  20 . The pressure unit  70  relieves a shock caused by the initial contact of the cleaning blade  50  on the belt  20  when the cleaning blade  50  is in the first station, and simultaneously biases the cleaning blade  50  against the belt  20  to control the force the cleaning blade  50  applied to the belt  20  so that toner remaining on the belt  20  can be removed. Upon application of the biasing force on the cleaning blade  50 , and consequently on the belt  20 , the cleaning blade  50  is positioned in what is referred to herein as the “second station.” 
   The pressure unit  70  includes a blade bracket  71  placed between the first and second hinge points H 1  and H 2 , and a biasing element  72  interposed between the support bracket  42  and the blade bracket  71  to bias the cleaning blade  50 . In the exemplary embodiment of the present general inventive concept, a coil spring is illustrated as the biasing element  72 , but other biasing elements, such as, for example, a leaf spring may be used to bias the cleaning blade  50  towards the belt  20 . The biasing element  72  and the eccentricity of the driving cam  60  together establish a time interval during which the cleaning blade  50  remains in contact with the belt  20 . The time interval may vary by application of the present general inventive concept, as will be appreciated by the skilled artisan, and the characteristics of the biasing element, such as the spring constant, the type, the length, etc., and the eccentricity of the driving cam, such as the axle location and the peripheral contour, can be selected for the desired time interval. 
     FIG. 4  illustrates the operation of the pressure unit  70  as constructed in accordance with the exemplary embodiment described above. In  FIG. 4 , the blade arm  40  is placed in the first position, the cleaning blade  50 , indicated by a solid line, is located at the first station, i.e., the position where the cleaning blade  50  comes into contact with the belt  20  and immediately prior to application of the biasing force by the pressure unit  70 . The cleaning blade  50  at the position indicated by a dotted line is located at the second station, i.e., the position where the cleaning blade  50  is biased against the belt  20  by the pressure unit  70 . In other words, the cleaning blade  50  is brought into contact with the belt  20  through two stations. Accordingly, the cleaning blade  50  can be brought in contact with, or separated from the belt  20  in a more controlled manner than in a conventional construction in which the cleaning blade  50  is brought in contact with the belt  20  through a single motion of a rigidly mounted cleaning blade. Therefore, damage to the leading edge of the cleaning blade  50  and the problems of the cleaning blade  50  bending can be prevented. 
     FIG. 5  is an exemplary view schematically illustrating an image forming apparatus including a transfer unit  10  in which the belt cleaning apparatus  30  according to an exemplary embodiment of the present general inventive concept is employed. As illustrated in  FIG. 5 , a feeding unit  110  is placed on a lower part of a main body  100  of the image forming apparatus, and a developing unit  120  is placed on one side of the photosensitive medium  80 . The electrostatic latent image formed on the photosensitive medium  80  is developed into a visible image by the developing unit  120 . The toner image developed on the photosensitive medium  80  is primarily transferred to the transfer unit  10 . The printing medium P picked up by the feeding unit  110  is transferred between the belt  20  and transfer roller  90  of the transfer unit  10 . The toner image primarily transferred to the belt  20  is secondarily transferred onto the printing medium P. The printing medium P onto which the toner image is transferred passes through a fixing unit  130  and a discharging unit  140  to be discharged to the outside. 
   As the toner image developed on the photosensitive medium is transferred to the belt  20 , the blade arm  40  is located in the second position, as illustrated in  FIG. 3 . Accordingly, the cleaning blade  50  is separated from the belt  20 . 
   Additionally, if all toner images formed on the photosensitive medium are transferred to the belt  20 , and then the toner image on the belt  20  is finally transferred onto the printing medium P, which is fed between the belt  20  and transfer roller  90 , the driving cam  60  can be operated to pivot the blade arm  40 . Accordingly, the blade arm  40  is moved to the first position. 
   When the blade arm  40  is in the first position, as illustrated in  FIG. 2 , the leading end of the cleaning blade  50  is in contact with the belt  20 , and the toner remaining on the belt  20  is then removed. In the situation, when the cleaning blade  50  is in contact with the belt  20  in the first station by moving the blade arm  40  to the first position, the shock caused by contact in the first station between the cleaning blade  50  and the belt  20  is relieved by the pressure unit  70 , and thus damage to the leading edge of the cleaning blade is prevented as is the problem of the cleaning blade bending, which occur in the conventional systems. 
   Additionally, the pressure unit  70  biases the cleaning blade  50  while relieving the shock caused by the initial contact in the first station of the cleaning blade  50 , and accordingly, the cleaning blade  50  being brought fully in contact with the belt  20  in the second station removes the toner remaining on the belt  20  in a controlled manner. 
   In traditional image forming systems, since the cleaning blade is rigidly mounted on the blade arm and is in contact with or separated from the belt by the rotation of the blade arm through the driving cam, the cleaning blade can be damaged and bent from the significant shock caused by the contact. However, in the exemplary embodiment of the present general inventive concept, the cleaning blade  50  is in contact with the belt  20  at the first station by the blade arm  40  being pivoted by the driving cam  60 , and the pressure unit  70  relieves the shock resulting from the contact. Additionally, the pressure unit  70  maintains the contact of the cleaning blade  50  with the belt  20  in the second station, and thus the cleaning blade  50  can be protected from being damaged or bent. 
   As described above, according to exemplary embodiments of the present general inventive concept, it is possible to reduce the damage and bending of the cleaning blade, and thus the durability of the cleaning blade can be improved. In addition, the cleaning efficiency of the belt can increase to enhance the transfer quality. 
   Furthermore, contact between the cleaning blade and the belt can be controlled by the driving cam and pressure unit through two stations, and accordingly, the hinge points of the blade arm can be freely designed, thus enabling miniaturization of the cleaning blade. 
   Although the transfer unit and cleaning apparatus in which the transfer belt is used are described in the present general inventive concept above, the transfer belt is merely an example of the transfer medium, and accordingly a transfer drum may also be used as the transfer medium. Therefore, the cleaning apparatus according to the present general inventive concept can also be usefully applied to the transfer drum. 
   Although a few embodiments of the present general inventive concept have been illustrated 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.