Abstract:
A printing medium feeder and image forming apparatus are provided. The printing medium feeder includes a pickup unit configured to pick up printing medium, and a support arranged on a lower side of the pickup unit to selectively support the pickup unit or release supporting of the pickup unit, wherein as the support releases the supporting of the pickup unit, the other end portion of the pickup unit descends by self-weight on the basis of one end portion thereof to be seated on the printing medium.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to, and claims priority benefit, under 35 U.S.C. §119(a) to Korean Patent Application No. 10-2014-0104431, filed on Aug. 12, 2014, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The present disclosure relates to a printing medium feeder and an image forming apparatus having the same, and more particularly to a swing type paper feeder that can reduce noise during paper feeding. 
         [0004]    2. Description of the Related Art 
         [0005]    To perform printing operation through an image forming apparatus, paper may be transported to a feed cassette or paper may be set in a feed tray to an inside of the apparatus, and a paper feed type may be classified as an up-down type or a swing type. 
         [0006]    An up-down type feeder includes a pickup unit that may be fixed to an upper side of a feed cassette to transport paper sheet by sheet. Accordingly, when the feed cassette including paper is mounted on the image forming apparatus, a knock-up plate that may provided on the feed cassette ascends to move the paper in a direction of an upper side on which a pickup unit exists. One end of the knock-up plate may be hinge-engaged and the other end thereof may be connected to a driving portion that may include a motor and gears. In accordance with driving of the driving portion, one side surface of the knock-up plate ascends, and thus a part of the paper can reach the pickup unit. The up-down type feeder may be used in a large-scale image forming apparatus, and a large amount of paper, for example, about 500 sheets of paper can be loaded on the paper cassette at a time. 
         [0007]    A swing type feeder includes a pickup unit that swings upward and downward to transport paper sheet by sheet. Accordingly, when a feeding operation starts after the feed cassette in which paper fills is mounted on the image forming apparatus or paper is set in a feed tray, the pickup unit may be rotated in a paper direction to reach the paper. The swing type feeder may be used in a small-scale image forming apparatus, and, for example, about 50 to 100 sheets of paper can be loaded on the paper cassette at a time. 
         [0008]    According to the swing type feeder, the pickup unit may be spaced apart from the paper without coming in contact with the paper before the printing operation, but when the printing operation starts, the pickup unit may be rotated to make a pickup roller provided on the pickup unit reach the paper. When the pickup roller reaches the paper, the paper may be transported to the inside of the image forming apparatus by a rotating force that may be transferred from a driving source. Thereafter, if one sheet of paper is transported, the driving source stops its operation, and thus the pickup roller also stops rotation to print the paper sheet by sheet. A restoring force of a return spring of a housing member returns the pickup unit to a standby state. That is, after one sheet of paper is transported, the pickup unit again becomes spaced apart from the paper. Thereafter, if the driving source re-operates to transport the next paper, the pickup unit is rotated in the paper direction, and thus the pickup roller reaches the paper. 
         [0009]    However, according to the swing type feeder in the related art, whenever one sheet of paper is transported to the inside of the image forming apparatus, the pickup roller may collide with the paper due to the rotation of the pickup unit, and impact noise is generated. The impact noise may be loud, and unpleasant to a user. 
         [0010]    The impact noise may not be generated in the up-down type feeder that does not perform the swing operation. However, the up-down type feeder is relatively expensive in comparison to the swing type feeder, and it may be difficult to adopt the up-down type feeder in a typical small-scale image forming apparatus. Accordingly, an inexpensive swing type feeder is used in a small-scale image forming apparatus regardless of the noise. 
         [0011]    The noise generated may become greater as the speed of the swing operation becomes higher and the section of the swing operation becomes longer. However, since reduction of the swing operation speed may be related to the printing speed, lowering of the paper transport speed of the pickup unit may not meet high-speed printing requirements. Further, since reduction of the swing operation section may be related to the amount of paper load, it may be required to reduce the amount of paper load to reduce the noise, or it may be required to use the up-down type in which the height of the feed cassette is varied according to the amount of paper. However, the up-down type in which the height of the feed cassette is varied may require the separate feed cassette, which may be mounted on the image forming apparatus so that the height of paper can be heightened by a spring and the driving force, and this it may be difficult to adopt the up-down type in the image forming apparatus in which only the feed tray exists without the feed cassette. 
       SUMMARY 
       [0012]    Additional aspects and/or advantages 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. 
         [0013]    According to an exemplary embodiment of the present invention, the above problems and/or disadvantages are addressed and the exemplary advantages described below are provided. Accordingly, an aspect of the present disclosure a paper feeder is provided that can reduce noise that is generated whenever a pickup unit repeatedly reaches every sheet of paper to transport the paper. 
         [0014]    According to an aspect of the present disclosure, a printing medium feeder includes a pickup unit configured to pick up printing medium, and a support arranged on a lower side of the pickup unit to selectively support the pickup unit or release supporting of the pickup unit, wherein as the support releases the supporting of the pickup unit, an other end portion of the pickup unit descends by self-weight on the basis of one end portion thereof to be seated on the printing medium. 
         [0015]    The support may swing about a lower end portion thereof to support a part of a lower side of the pickup unit through an upper end portion thereof. 
         [0016]    The support may be pressed by a feed cassette mounted on a main body or the printing medium set on a feed tray and may swing in a mounting direction of the feed cassette or in a printing medium setting direction to release the supporting of the pickup unit. 
         [0017]    The support may include an elastic member provided in the lower end portion thereof, and may return to its original position by the elastic member to support the pickup unit if the feed cassette secedes from its mounted position or the printing medium set on the feed tray is entirely consumed. 
         [0018]    The support may include a support roller provided on the upper end portion thereof to come in contact with and to slide along the part of the lower side of the pickup unit. 
         [0019]    The pickup unit may include a guide projection formed to project from the lower side thereof in a side direction, and the support may include a support roller configured to support the guide projection. 
         [0020]    The pickup unit may include a pressing member configured to elastically press the other end portion of the pickup unit so that a pickup roller arranged on the other end portion of the pickup unit presses the printing medium. 
         [0021]    The pressing member may be a torsion spring provided on a driving shaft that penetrates the one end portion of the pickup unit. 
         [0022]    The pressing member that presses the other end portion of the pickup unit in a lower direction may be a coil spring that presses from an upper portion of the pickup unit toward the lower side. 
         [0023]    The coil spring may have one end that is fixed to a part of a structure that is positioned on an upper side of the pickup unit and the other end that is fixed to an upper side of the other end portion of the pickup unit and may elastically press the pickup unit. 
         [0024]    According to an aspect of the present disclosure, a printing medium feeder includes a pickup unit configured to pick up printing medium; and a support arranged on a lower side of the pickup unit, wherein the support is selectively set to a first position in which the support supports the pickup unit or a second position in which the support is pressed by a feed cassette that is mounted on a main body or the printing medium that is set on a feed tray of an image forming apparatus to release the supporting of the pickup unit. 
         [0025]    The pickup unit may be rotated so that the other end portion thereof descends by self-weight on the basis of one end portion thereof to be seated on the printing medium as the support is rotated from the first position to the second position, and may be rotated so that the other end portion thereof ascends on the basis of the one end portion thereof as the support is rotated from the second position to the first position. 
         [0026]    The support may include an elastic member provided in a lower end portion thereof to be elastically rotated from the second position to the first position. 
         [0027]    According to an aspect of the present disclosure, an image forming apparatus includes a main body, a feed cassette detachably provided on the main body or a feed tray provided on the main body to set printing medium; and a printing medium feeder including a pickup unit configured to pick up the printing medium, and a support arranged on a lower side of the pickup unit to support the pickup unit in a first position and to release the supporting of the pickup unit in a second position, wherein the other end portion of the pickup unit swings downward from the second position by self-weight on the basis of one end portion thereof so that a pickup roller of the pickup unit is seated on the printing medium. 
         [0028]    The support may be rotated from the first position to the second position as the support is pressed by the feed cassette mounted on the main body or the printing medium that is set in the feed tray. 
         [0029]    The support may be rotated from the second position to the first position as the support is released from being pressed by the feed cassette or the printing medium of the feed tray. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    The above and other aspects, features and advantages of the present disclosure will be more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
           [0031]      FIG. 1  illustrates a paper feeder according to an embodiment of the present disclosure; 
           [0032]      FIG. 2  illustrates an exemplary paper feeder; 
           [0033]      FIGS. 3 and 4  illustrate exemplary states where a support of a paper feeder according to an exemplary embodiment of the present disclosure is set to a first position and a second position, respectively; 
           [0034]      FIG. 5  illustrates an exemplary state where a torsion spring is installed on a paper feeder according to an embodiment of the present disclosure; 
           [0035]      FIG. 6  illustrates a coil spring provided on a paper feeder according to an embodiment of the present disclosure; 
           [0036]      FIG. 7  illustrates a paper feeder according to an embodiment of the present disclosure; 
           [0037]      FIGS. 8 and 9  illustrate exemplary states where a support of a paper feeder according to an embodiment of the present disclosure is set to a first position and a second position, respectively; 
           [0038]      FIG. 10  illustrate a paper feeder according to an embodiment of the present disclosure in a state where a support is set to a first position; 
           [0039]      FIG. 11  illustrate an exemplary state where a support is set to a second position as paper is set in a feed tray; 
           [0040]      FIG. 12  illustrate an exemplary state where paper is fed by a pickup roller; 
           [0041]      FIG. 13  illustrate an exemplary paper feeder according to an embodiment of the present disclosure in a state where a support is set to a first position; 
           [0042]      FIG. 14  illustrate an exemplary state where a support is set to a second position as paper is set in a feed tray; and 
           [0043]      FIG. 15  illustrates an exemplary state where paper is fed by a pickup roller. 
       
    
    
     DETAILED DESCRIPTION 
       [0044]    Reference will now be made in detail to the embodiments, 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. 
         [0045]    Paper feeders  1 ,  1   a ,  1   b , and  1   c  according to an embodiment of the present disclosure are described in detail with reference to the accompanying drawings. Well-known functions or elements may not described or illustrated in detail if it is determined that such detailed description would obscure the present disclosure in unnecessary detail. 
         [0046]    Referring to  FIGS. 1 and 2 , a paper feeder  1  according to an embodiment of the present disclosure includes a pickup unit  100  and a support  200 . 
         [0047]    The pickup unit  100  includes a driving shaft  110 , a pickup roller  120 , a power transfer portion  130 , a housing  140 , and a feed roller  150 . 
         [0048]    The driving shaft  110  may have one end that is connected to a driving source, and receives a power from the driving source to be rotated. As the driving shaft  110  is rotated, the pickup unit  100  may be rotated in a direction in which the pickup roller  120  descends about the driving shaft  110  as a rotating shaft. The pickup roller  120  may be rotated to transport paper. 
         [0049]    The pickup roller  120  may be rotated to transport the paper, and includes a connection portion  121  and a feeder portion  122 . 
         [0050]    The connection portion  121  may be connected to the power transfer portion  130 , and receives the power of the driving shaft  110  to rotate the pickup roller  120 . 
         [0051]    The feeder portion  122  is a portion that may come in contact with the paper to transport the paper, and may be rotated to transport the paper according to the rotation of the connection portion  121 . 
         [0052]    The power transfer portion  130  may be arranged between the driving shaft  110  and the pickup roller  120 , and transfers the power of the driving shaft  110  to the pickup roller  120 . The power transfer portion  130  may include gears that can be gear-coupled to a part of the driving shaft  110  and a part of the pickup roller  120 . Accordingly, the rotating direction of the power transfer portion  130  may reverse to the rotating direction of the driving shaft  110  and the pickup roller  120 . 
         [0053]    The housing  140  is a cover of the pickup unit  100  on which the driving shaft  110 , the pickup roller  120 , and the power transfer portion  130  may be mounted. 
         [0054]    The driving shaft  110  may be coupled through a pair of first coupling holes  141  formed on both side surfaces of the housing  140 . The pickup roller  120  may be coupled through a pair of second coupling holes  142  formed on both side surfaces of the housing. 
         [0055]    The driving shaft  110  and the pickup roller  120  that are coupled to the housing  140  may be coupled to slip through the first coupling holes  141  and the second coupling holes  142  of the housing  140 , and thus can be rotated separately from the housing  140 . 
         [0056]    The housing  140  may include a supported portion  143  that is a portion that may be contacted when the support  200  supports the pickup unit  100 . According to an exemplary embodiment, a housing  140  may include a guide projection  144  that is formed to project from a side surface on which the support  200  is arranged. 
         [0057]    The feed roller  150  secondarily transports the paper that may be primarily transported by the pickup roller  120  to the inside of the image forming apparatus. The feed roller  150  may be inserted into the driving shaft  110 , and may be rotated together with the driving shaft  110 . 
         [0058]    The support  200  includes a first portion  210  that forms an upper portion and a second portion  220  that forms a lower portion. 
         [0059]    The first portion  210  is a portion that supports the pickup unit  100 , and a rear end of the first portion  210  may be connected to the second portion  220 . 
         [0060]    The first portion  210  has a first surface  211  that is provided at an upper end thereof. The first surface  211  comes in slidable contact with the supported portion  143  that may be formed on the side surface of the housing  140 . 
         [0061]    The second portion  220  may be arranged on a lower side of the first portion  210 , and includes a rotary shaft  221  that is rotated together with the first portion  210  and a fixed shaft  222  that may be rotatably coupled to the rotary shaft  221 . 
         [0062]    The first portion  210  may be formed to extend from an outside of the rotary shaft  221 , and the rotary shaft  221  may be rotated together when the first portion  210  is rotated. A hollow may be formed in the rotary shaft  221  so that the fixed shaft  222  penetrates the rotary shaft  221 . 
         [0063]    The fixed shaft  222  may be rotatably coupled to the rotary shaft  221 , and operate as a rotating shaft when the first portion  210  and the rotary shaft  221  are rotated. That is, the fixed shaft  222  may not be rotated even if the first portion  210  and the rotary shaft  221  are rotated. 
         [0064]    A process of driving the paper feeder  1  according to an embodiment of the present disclosure is described. 
         [0065]    Referring to  FIG. 3 , a feed cassette  310  is in a state where it secedes from the image forming apparatus, and the paper feeder  1  is in a standby state in which the paper feeder  1  is unable to perform feeding. The first portion  210  of the support  200  is in a first position P 1  in which the support  200  supports the pickup unit  100  so that the pickup unit  100  is maintained in a standby state, and thus the first surface  211  of the first portion  210  may come in contact with the supported portion  143  of the pickup unit  100 . 
         [0066]    As illustrated in  FIG. 4 , the feed cassette  310  including paper  311  is mounted. Since the feed cassette  310  is mounted, a pressing surface  312  of the feed cassette  310  presses the first portion  210  of the support  200 . Accordingly, the first portion  210  and the rotary shaft  221  may be rotated about the fixed shaft  222  as the rotating shaft. 
         [0067]    As the support  200  is rotated, the first portion  210  may be rotated to slide on the lower surface of the supported portion  143  from the first surface  211  to the second surface  212 . The first portion  210  secedes from the supported portion  143 . Accordingly, the pickup unit  100  is rotated in a direction A, in which the pickup roller  120  descends about the driving shaft  110  as a rotating shaft, for example, by self-weight. This rotation may be performed until the pickup roller  120  is seated on the paper  311 . The support  200  is in a second position P 2  that is pushed by the feed cassette  310 . 
         [0068]    If the paper  311 , for example, is entirely consumed, the feed cassette  310  may be separated from the image forming apparatus to provide the feed cassette  310  with paper  311 . Since the rotary shaft  221  and the fixed shaft  222  may be coupled to each other by the elastic member, the support  200  returns to the first position P 1  as the feed cassette  310  secedes from the image forming apparatus. The first portion  210  lifts the pickup unit  100  as the second surface  212  starts to come in contact with the supported portion  143 , and slides on the lower surface of the supported portion  143  to return to the first position P 1 . 
         [0069]    This process can be performed since the force by which the support  200  returns from the second position P 2  to the first position P 1  may be higher than the force by which the pickup unit  100  is rotated due to the self-weight. 
         [0070]    Referring to  FIG. 5 , the paper feeder  1  according to an exemplary embodiment of the present disclosure may include a pressing member that can apply an additional rotating force to press the paper in a direction B together with the self-weight of the pickup unit  100 . 
         [0071]    The pressing member may be a torsion spring  161  having one end  162  that is fixed to the housing  140  and the other end  163  that is fixed to a washer  111  that is fitted to slip on the driving shaft  110 . 
         [0072]    If the pickup roller  120  does not come in contact with the paper, the washer  111  and the torsion spring  161  may be rotated together with the driving shaft  110 , while if the pickup roller  120  comes in contact with the paper, the washer  111  and the torsion spring  161  slip without being rotated together with the driving shaft  110 . 
         [0073]    The washer  111  may continuously apply a rotating force in the rotating direction of the driving shaft  110  by a frictional force between the driving shaft  110  and the washer  111 , and thus the torsion spring  161  may apply a rotating force to rotate the pickup unit  100  in the direction B. 
         [0074]    Referring to  FIG. 6 , the pressing member that applies an additional rotating force together with the self-weight of the pickup unit  100  as illustrated in  FIG. 5  may be a coil spring  171  that may be positioned, for example, on an upper side of the pickup unit  100 . 
         [0075]    The coil spring may have one end  172  that is fixed to the housing  140  and the other end  173  that is fixed to a structure  174  that may be fixedly arranged on the upper portion of the pickup unit  100 . 
         [0076]    The coil spring  171  is in a compression state and applies force to push the pickup unit  100  from the structure  174 . This force makes the pickup unit  100  be rotated, for example, in a direction C in which the pickup roller  120  descends about the driving shaft  110 . 
         [0077]    In the case where the pickup unit  100  is in a feeding state, the pressing member increases the frictional force between the pickup roller  120  and the paper  311  to reduce a slip between the pickup roller  120  and the paper  311 . 
         [0078]    Referring to  FIGS. 7 to 9 , a paper feeder  1   a  according to an exemplary second embodiment of the present disclosure is described. In describing the configuration of the second embodiment, the same drawing reference numerals are used for the same elements as those according to an exemplary first embodiment as described above. The description of the same elements is omitted. 
         [0079]    Referring to  FIG. 7 , a guide projection  144  having a predetermined length may be formed to project from a side surface of the housing  140  of the pickup unit  200 . 
         [0080]    A support roller  213  to support the pickup unit  100  may be rotatably installed on the first portion  210  of the support  200  to come in contact with the guide projection  144 . 
         [0081]    A process of driving the paper feeder  1   a  according to the second embodiment of the present disclosure is described. 
         [0082]    Referring to  FIG. 8 , the feed cassette  310  is in a state where it secedes from the image forming apparatus, and the paper feeder  1   a  is in a standby state in which the paper feeder  1   a  is unable to perform feeding. 
         [0083]    The first portion  210  of the support  200  is in a first position P 1  in which the support  200  supports the pickup unit  100  so that the pickup unit  100  is maintained in a standby state, and thus the support roller  213  of the first portion  210  comes in contact with the guide projection  144  of the pickup unit  100 . 
         [0084]    Referring to  FIG. 9 , the feed cassette  310  that is filled with the paper  311  is mounted. Since the feed cassette  310  is mounted, the pressing surface  312  of the feed cassette  310  presses the first portion  210  of the support  200 . Accordingly, the first portion  210  and the rotary shaft  221  are rotated about the fixed shaft  222  as the rotating shaft. 
         [0085]    As the support  200  is rotated, the support roller  213  is rotated along the surface of the guide projection  144 , and finally secedes from the guide projection  144 . Accordingly, the pickup unit  100  is rotated in an arrow direction A, in which the pickup roller  120  descends about the driving shaft  110  as a rotating shaft, by self-weight. This rotation is performed until the pickup roller  120  is seated on the paper  311 . 
         [0086]    The support  200  is in the second position P 2  that is pushed by the feed cassette  310 . The length of the first portion  210  and the position of the guide projection  144  may be adjusted in order to prevent the driving shaft  110  from interfering with the rotating path of the support roller  213 . 
         [0087]    If the paper  311  is consumed, the feed cassette  310  may be made to secede from the image forming apparatus to allow refilling of the feed cassette  310  with the paper  311 . 
         [0088]    Since the feed cassette  310  secedes from the image forming apparatus, the support is rotated in a reverse direction to the arrow direction A to return to the first position P 1 . The support roller  213  starts to come in contact with one surface of the guide projection  144  to lift the pickup unit  100 , and may rotate along the surface of the guide projection  144  to return to the first position P 1 . 
         [0089]    This process can be performed since the force by which the support  200  returns from the second position P 2  to the first position P 1  may be greater than the force by which the pickup unit  100  is rotated due to the self-weight. 
         [0090]    The paper feeder  1   a  according to a second embodiment of the present disclosure may include a pressing member as illustrated in  FIGS. 5 and 6  to reduce a slip between the pickup roller  120  and the paper  311  through increasing of the frictional force between the pickup roller  120  and the paper  311  when the pickup unit  100  is in a feeding state. 
         [0091]    Referring to  FIGS. 10 to 12 , a paper feeder  1   b  according to a third embodiment of the present disclosure is described. In describing the configuration of the third embodiment, the same drawing reference numerals are used for the same constituent elements as those according to the first embodiment as described above. According to the third embodiment of the present disclosure, the paper feeder  1   b  is applied to the image forming apparatus on which a feed tray  320  is mounted. 
         [0092]    Referring to  FIG. 10 , the feed tray  320  may always be mounted on the image forming apparatus, and the paper feeder  1   b  is in a standby state in which the paper feeder  1   b  is unable to perform feeding. The first portion  210  of the support  200  is in a first position L 1  in which the support  200  supports the pickup unit  100  so that the pickup unit  100  is maintained in a standby state, and thus the first surface  211  of the first portion  210  comes in contact with the supported portion  143  of the pickup unit  100 . 
         [0093]    Referring to  FIG. 11 , the paper  321  is set in the feed tray  320 . Since the paper  321  is set, the front end  322  of the paper  321  presses the first portion  210  of the support  200 . Accordingly, the first portion  210  and the rotary shaft  221  are rotated about the fixed shaft  222  as the rotating shaft. 
         [0094]    As the support  200  is rotated, the first portion  210  is rotated along the lower surface of the supported portion  143  from the first surface  211  to the second surface  212 , and finally, the first portion  210  secedes from the supported portion  143 . Accordingly, the pickup unit  100  is rotated in a direction D, in which the pickup roller  120  descends about the driving shaft  110  as a rotating shaft, by the self-weight. This rotation is performed until the pickup roller  120  is seated on the paper  321 . The support  200  is in a second position L 2  that is pushed by the paper  321 . 
         [0095]    However, the second position L 2  in the case where the paper feeder  1   b  according to the present disclosure is applied to the type in which the paper  321  is inserted into the feed tray  320  is different from the second position P 2  in the type in which the feed cassette  310  is mounted, and the support  200  is rotated to the extent that the second position L 2  is pushed by the paper  321 . Accordingly, in the process of feeding the paper  321  into the image forming apparatus through the feed roller  150 , the paper  321  pushes the support  200  up to a third position L 3 . 
         [0096]    Referring to  FIG. 12 , the third position L 3  is illustrated, and the paper  321  naturally pushes the support  200  and is fed into the image forming apparatus by the feed roller  150 . 
         [0097]    If the paper  321  that presses the support  200  is entirely consumed, in a similar manner as the above-described embodiments, the support  200  returns to the first position L 1 , for example, by the elastic member that makes the rotary shaft  221  and the fixed shaft  222  coupled to each other. The first portion  210  of the support  200  lifts the pickup unit  100  as the second surface  212  starts to come in contact with the supported portion  143 , and slides on the lower surface of the supported portion  143  to return to the first position L 1 . 
         [0098]    This process can be performed since the force by which the support  200  returns from the second position L 2  to the first position L 1  is greater than the force by which the pickup unit  100  is rotated due to the self-weight. Since the force by which the paper  321  presses the support  200  is greater than the force by which the support  200  returns from the second position L 2  to the first position L 1 , the paper  321  can push the support  200 . 
         [0099]    The paper feeder  1   b  according to the third embodiment of the present disclosure may also include a pressing member as illustrated in  FIGS. 5 and 6  to reduce a slip between the pickup roller  120  and the paper  321  through increasing of the frictional force between the pickup roller  120  and the paper  321  when the pickup unit  100  is in a feeding state. 
         [0100]    Referring to  FIGS. 13 to 15 , a paper feeder  1   c  according to a fourth embodiment of the present disclosure is described. In describing the configuration of the fourth embodiment, the same drawing reference numerals are used for the same elements as those according to the second embodiment as described above. According to the fourth embodiment of the present disclosure, the paper feeder  1   c  is applied to the image forming apparatus on which a feed tray  320  is mounted. 
         [0101]    Referring to  FIG. 13 , the feed tray  320  may be always mounted on the image forming apparatus, and the paper feeder  1   c  is in a standby state in which the paper feeder  1   c  is unable to perform feeding. The first portion  210  of the support  200  is in a first position L 1  in which the support  200  supports the pickup unit  100  so that the pickup unit  100  is maintained in a standby state, and thus the support roller  213  of the first portion  210  comes in contact with the guide projection  144  of the pickup unit  100 . 
         [0102]    Referring to  FIG. 14 , the paper  321  is set in the feed tray  320 . Since the paper  321  is set, the front end  322  of the paper  321  presses the first portion  210  of the support  200 . Accordingly, the first portion  210  and the rotary shaft  221  are rotated about the fixed shaft  222  as the rotating shaft. 
         [0103]    As the support  200  is rotated, the support roller  213  is rotated along the surface of the guide projection  144 , and finally secedes from the guide projection  144 . Accordingly, the pickup unit  100  is rotated in a direction D, in which the pickup roller  120  descends about the driving shaft  110  as a rotating shaft, by the self-weight. This rotation is performed until the pickup roller  120  is seated on the paper  321 . The support  200  is in a second position L 2  that is pushed by the feed cassette  310 . 
         [0104]    However, the second position L 2  in the case where the paper feeder  1   c  according to the present disclosure is applied to the type in which the paper  321  is inserted into the feed tray  320  is different from the second position P 2  in the type in which the feed cassette  310  is mounted, and the support  200  is rotated to the extent that the second position L 2  is pushed by the paper  321 . Accordingly, in the process of feeding the paper  321  into the image forming apparatus through the feed roller  150 , the paper  321  pushes the support  200  up to a third position L 3 . The length of the first portion  210  and the position of the guide projection  144  may be adjusted in order to prevent the driving shaft  110  from interfering with the rotating path of the support roller  213 . 
         [0105]    Referring to  FIG. 15 , the third position L 3  is illustrated, and unlike the first portion  210  according to the third embodiment, the support roller  213  is provided on the first portion  210  according to the fourth embodiment. Accordingly, the paper  321  naturally pushes the support  200  and is fed into the image forming apparatus by the feed roller  150 . 
         [0106]    If the paper  321  that presses the support  200  is entirely consumed, in the same manner as the above-described embodiments, the support  200  returns to the first position L 1  by the elastic member that makes the rotary shaft  221  and the fixed shaft  222  coupled to each other. The support roller  213  starts to come in contact with one surface of the guide projection  144  to lift the pickup unit  100 , and is rotated along the surface of the guide projection  144  to return to the first position L 1 . 
         [0107]    This process can be performed since the force by which the support  200  returns from the second position L 2  to the first position L 1  is greater than the force by which the pickup unit  100  is rotated due to the self-weight. Since the force by which the paper  321  presses the support  200  is higher than the force by which the support  200  returns from the second position L 2  to the first position L 1 , the paper  321  can push the support  200 . 
         [0108]    The paper feeder  1   c  according to the fourth embodiment of the present disclosure may also include a pressing member as illustrated in  FIGS. 5 and 6  in order to reduce a slip between the pickup roller  120  and the paper  321  through increasing of the frictional force between the pickup roller  120  and the paper  321  when the pickup unit  100  is in a feeding state. 
         [0109]    As described above, according to the present disclosure, in a case where paper  311  or  321  is loaded, the pickup roller  120  always comes in contact with the paper  311  or  321 , and thus impact noise that is generated between the pickup roller  120  and the paper  311  or  321  during the feeding operation can be eliminated. 
         [0110]    While the present disclosure has been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present disclosure, as defined by the appended claims. 
         [0111]    Although a few embodiments 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.