Abstract:
A multi-function actuator of a duplex printer selects one of movement passages of a printing medium according to whether to print one side or on both sides of the printing medium and includes a duplex guide, a jam removing mechanism, a sensor arm, and a sensor. The duplex guide is rotatably disposed above a pressure roller of a duplex printer frame and includes a hollow cylinder and a plurality of bar-shaped guide pins at one side thereof guiding the printing medium. The jam removing mechanism is rotatably disposed inside of the hollow cylinder to allow the pressure roller to be separated from the heat roller when a jammed material is removed. The sensor arm is disposed co-axially with the duplex guide and rotates by a weight thereof. The sensor is disposed at the duplex printer frame and operates by the sensor arm. Accordingly, the multi-function actuator selects the one of the movement passage and allows the jammed material to be removed by separating the pressure roller from the heat roller.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of Korean Patent Application No. 2001-76986 filed on Dec. 6, 2001, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to a duplex printer, and more particularly, to a duplex printer having a multi-function actuator selecting a movement passage of a printing medium according to one side or both sides of the printing medium and removing a jammed printing medium disposed in the movement passage.  
           [0004]    2. Description of the Related Art  
           [0005]    Generally, a duplex printer can print an image on one side or both sides of a printing medium according to a user selection.  
           [0006]    [0006]FIG. 1 shows a cross-sectional view of the duplex printer having a conventional actuator. The duplex printer includes a simplex printing passage  10  and a duplex printing passage  20 .  
           [0007]    The simplex printing passage  10  includes a development unit  11  developing a given image on a printing medium  1  fed by a feeding roller  3 , a fixing unit  14  including a pressure roller  12  and a heat roller  13  fixing the developed image on the printing medium  1 , a simplex transporting roller  16  transporting a printed printing medium  1  from the fixing unit  14 , and a discharge roller  5  discharging the printed printing medium  1  to a discharge tray  7 .  
           [0008]    A duplex printing passage  20  includes a plurality of duplex transporting rollers  21 , 22 , 23  transporting the printing medium  1 , which has been printed on the one side thereof and is transported from the discharge roller  5  to the feeding roller  3 .  
           [0009]    Also, an actuator  30  has one end  31  being hinged at a duplex printer frame and is disposed among the discharge roller  5 , the simplex transporting roller  16 , and the duplex transporting roller  21 . Therefore, the simplex printing passage  10  or the duplex printing passage  20  can be selected by moving the actuator  30 .  
           [0010]    In the duplex printer, an operation of printing one side or both sides of the printing medium  1  is described as follows.  
           [0011]    When printing on one side of the printing medium  1 , the printing medium  1  passes through the fixing unit  14  and is transported to the discharge roller  5  by the simplex transporting roller  16  and then discharged in a discharging direction to the discharge tray  7  by the discharge roller  5 . At this time, the printing medium  1 , which passes through the simplex transporting roller  16 , is freely moved into the discharge roller  5  because the actuator  30  is positioned at a first position P1.  
           [0012]    Also, when printing on both sides of the printing medium  1 , first, the printing medium  1 , which has been printed on the one side thereof through the operation described above, is moved into the discharge roller  5 . And then the discharge roller  5  is rotated in a reverse direction before the printing medium  1  moves away from the discharge roller  5  so that the printing medium  1  is moved in an opposite direction. At this time, because the actuator  30  is located at a second position P 2 , the printing medium  1 , moved in the direction opposite to the discharging direction, can be moved into the duplex printing passage  20 . And then the printing medium  1  printed on the one side thereof is transported to the development unit  11  by the duplex transporting rollers  21 ,  22 ,  23  and the feeding roller  3 . Here, the other side of the printing medium  1  is turned to face upward by the duplex transporting rollers  21 ,  22 ,  23  and the feeding roller  3 . Then the printing medium  1  printed on the one side thereof is printed on the other side by the development unit  11  and the fixing unit  14  and discharged to the discharge tray  7  by the discharge roller  5 . Accordingly, the printing medium  1  can be printed on both sides thereof by the actuator  30 .  
           [0013]    [0013]FIG. 2 shows a cross-sectional view of another type of duplex printer having another conventional actuator. The actuator  40  is rotatably disposed above the pressure roller  62  and includes a body  41 , a duplex guide  43 , a sensor arm  45 , and an actuator separator  47  independently projecting in a predetermined direction from the body  41 . Also, the duplex guide  43 , the sensor arm  45 , and the actuator separator  47  are integrally formed with the body  41 .  
           [0014]    The body  41  has a cylindrical shape, and both ends thereof are rotatably disposed at an upper part of a frame where a pressure roller  62  is disposed.  
           [0015]    The duplex guide  43  projects from the body  41 , is disposed above a heat roller  63 , and rotates upward by an interference with a front end of the printing medium  1  passing through the fixing unit  64 .  
           [0016]    The sensor arm  45  projects from a vicinity of one end of the body  41  in an upward direction relative to the duplex guide  43  at an angle of approximately 120° with respect to the duplex guide  43 . When the duplex guide  43  is in a horizontal position, an upper part of the sensor arm  45  is detected by using a sensor  49  mounted on the duplex printer frame.  
           [0017]    The actuator separator  47  projects from a vicinity of an opposite end of the body  41  in the upward direction relative to the duplex guide  43  at an angle of approximately 90°. The actuator separator  47  is used for manually rotating the duplex guide  43  by a predetermined angle to remove a jammed printing medium  1 . Accordingly, the jammed printing medium  1  to be removed from the fixing unit  64  is not blocked by the duplex guide  43  during removal of the jammed printing medium  1 .  
           [0018]    In the duplex printer having the actuator  40  constructed as above, a duplex printing operation is performed as follows.  
           [0019]    The printing medium  1  passes through the fixing unit  64  with the one side printed, the duplex guide  43  rotates by the front end of the printing medium  1  by a predetermined angle, and the printing medium  1  is moved into the discharge passage  50 .  
           [0020]    After a trailing end of the printing medium  1  moves into the discharge passage  50  and does not contact the duplex guide  43 , the discharge roller  53  is rotated in the reverse direction so that the printing medium  1  is moved in the opposite direction. At this time, because the duplex guide  43 , which rotates downward to the horizontal position by a weight thereof, blocks above the fixing unit  64  and the printing passage  60 , the printing medium  1  moves in the opposite direction into the duplex printing passage  70 .  
           [0021]    The printing medium  1  moved into the duplex printing passage  70  moves into the development unit  61  by a transfer roller  71  again, and then is printed on a non-printed side. Then the printing medium  1  printed on both sides thereof is discharged to the discharge tray  80  by the discharge rollers  51 , 53 . Accordingly, the printing medium  1  can be printed on both sides thereof by the operation of the actuator  40 .  
           [0022]    However, in the duplex printer constructed as shown in FIG. 1, there is a problem that the jammed printing medium  1  cannot be removed by the actuator  30  when the jammed printing medium  1  is jammed in the fixing unit  14 . Therefore, a separate additional apparatus removing the jammed printing medium  1  is needed.  
           [0023]    Also, in the duplex printer constructed as shown in FIG. 2, there is another problem that the jammed printing medium  1  is blocked by the duplex guide  43  when the jammed printing medium  1  is removed from the fixing unit  64  or the discharge passage  50 .  
           [0024]    There is another problem that the separate additional apparatus separating the pressure roller  62  and the heat roller  63  of the fixing unit  64  requires a free space in which the separate additional apparatus is disposed.  
         SUMMARY OF THE INVENTION  
         [0025]    Therefore, it is an object of the present invention to provide a multi-function actuator having an actuator separating a pressure roller from a heat roller by an actuator separator so that a jammed printing medium is easily removed from a fixing unit.  
           [0026]    Another object of the present invention is to provide a multi-function actuator, in which a duplex guide is disposed apart from a movement passage of a printing medium so that a jammed printing medium is easily removed from a discharge passage.  
           [0027]    Additional objects and advantages of the invention 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 invention.  
           [0028]    To achieve the above and other objects, a multi-function actuator according to an embodiment of the present invention includes a duplex guide rotatably disposed above a pressure roller of a duplex printer frame. The duplex guide includes a hollow cylinder and a plurality of bar-shaped guide pins formed at one side of the hollow cylinder and arranged in a row above a heat roller to guide a printing medium. The duplex guide is rotated by the printing medium by a guide angle in a printing medium feeding direction from a first position blocking a printing passage of the printing medium to a second position opening the printing passage. The multi-function actuator includes a jam removing mechanism rotatably disposed inside of the hollow cylinder to allow the pressure roller to be separated from the heat roller when a jammed printing medium is removed, a sensor arm disposed co-axially with the duplex guide to rotate by a weight of the sensor arm and having a low part supported by a supporting end of the duplex guide to form a first predetermined angle between the sensor arm and the guide pins, and a sensor disposed at the duplex printer frame to sense the sensor arm when the duplex guide is rotated by the printing medium.  
           [0029]    Further, the jam removing mechanism includes a jam removing lever rotatably disposed at the duplex printer frame and on a side of the pressure roller and having a penetrating hole disposed at a middle part thereof, into which a rotation shaft of the pressure roller is inserted, a jam removing shaft inserted inside of the hollow cylinder and rotatably disposed at the duplex printer frame, an actuator separator attached on one side of the jam removing shaft to rotate the jam removing shaft by a second predetermined angle in the printing medium feeding direction to allow the printing medium jammed between the pressure roller and the heat roller to be removed, and a jam removing cam disposed on another side of the jam removing shaft to contact an upper portion of the jam removing lever and formed such that if the actuator separator rotates at the second predetermined angle, the jam removing lever is rotated by the jam removing cam by a third predetermined angle in the same printing medium feeding direction to separate the pressure roller from the heat roller.  
           [0030]    Further, the actuator separator includes a rib rotating the duplex guide when the jammed printing medium is removed.  
           [0031]    Further, the duplex guide is rotated at an angle of 60 degrees in the printing medium feeding direction by the printing medium when the printing medium is printed, and further rotates at an angle of 180 degrees by a weight of the duplex guide after the duplex guide rotates at an angle of 110 degrees by the rib of the actuator separator when the jammed printing medium is removed.  
           [0032]    Further, the actuator separator is spaced apart from the jam removing cam at a predetermined distance where the printing medium passes.  
           [0033]    Further, the actuator separator and the jam removing cam project in the substantially same direction.  
           [0034]    Further, the jam removing mechanism includes a second jam removing cam disposed on a third side of the jam removing shaft opposite to the another side to be spaced-apart from the jam removing cam by a second predetermined distance so that the printing medium passes between the two jam removing cams.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]    These and other objects and advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:  
         [0036]    [0036]FIG. 1 is a cross-sectional view showing a conventional duplex printer having an actuator;  
         [0037]    [0037]FIG. 2 is a cross-sectional view showing another type of the conventional duplex printer having another actuator;  
         [0038]    [0038]FIG. 3 is a perspective view showing a multi-function actuator according to an embodiment of the present invention;  
         [0039]    [0039]FIG. 4 is a cross-sectional view of the multi-function actuator taken along line I-I of FIG. 3;  
         [0040]    [0040]FIG. 5 is a cross-sectional view of the multi-function actuator taken along line II-II of FIG. 3;  
         [0041]    [0041]FIG. 6 is a schematic showing a jam removing mechanism of the multi-function actuator of FIG. 3;  
         [0042]    [0042]FIG. 7 is a cross-sectional view showing a duplex printer having the multi-function actuator of FIG. 3;  
         [0043]    [0043]FIG. 8 is a schematic diagram showing that a duplex guide pin operates by a printing medium in the multi-function actuator of FIG. 3 ; and  
         [0044]    [0044]FIG. 9 is a schematic diagram showing a jammed printing medium and the jam removing mechanism of FIG. 3. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0045]    Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.  
         [0046]    Referring to FIGS. 3 through 7, a multi-function actuator  100  in accordance with an embodiment of the present invention includes a duplex guide  101 , a sensor arm  106 , and a jam removing mechanism having a jam removing shaft  121 , an actuator separator  123 , and a jam removing cam  125 .  
         [0047]    The duplex guide  101  includes a hollow cylinder  102  and a plurality of guide pins  103  formed in a row on the hollow cylinder  102  at predetermined intervals and projecting in one direction from a side of the hollow cylinder  102  as shown in FIG. 3. The guide pins  103  have a square bar shape, a lower part formed such that a front end of a printing medium  1  can be easily guided into a discharge passage  160  of FIG. 7 when one side of the printing medium  1  is printed, and an upper part formed such that the printing medium  1  having the one side printed can be easily guided into a duplex printing passage  150  of FIG. 7 without being obstructed when the other side of the printing medium  1  is printed. As shown in FIG. 6, the hollow cylinder  102  of the duplex guide  101  is disposed above a pressure roller  141  of a fixing unit  143 , and the guide pins  103  are disposed above a heat roller  142  of the fixed unit  143 . Therefore, the duplex guide  101  is rotated upward about an axle of the hollow cylinder  102  by the printing medium  1  moving between the pressure roller  141  and the heat roller  142 .  
         [0048]    In FIG. 4, the sensor arm  106  is disposed co-axially with the hollow cylinder  102  of the duplex guide  101  and eccentrically formed such that the sensor arm  106  always receives a force rotating about the hollow cylinder  102  downward by a weight of the sensor arm  10 . Also, a low portion of the sensor arm  106  is supported by a supporting end  104  formed on the duplex guide  101  so that the guide pins  103  of the duplex guide  101  and the sensor arm  106  are at a first predetermined angle with respect to each other. Therefore, if the duplex guide  101  is rotated upward by the printing medium  1 , the sensor arm  106  is rotated downward as much as the duplex guide  101  rotates.  
         [0049]    Also, when the guide pins  103  of the duplex guide  101  are disposed in a horizontal position R1 of FIG. 8, the duplex guide  101  and sensor arm  106  are balanced. Therefore, when each guide pin  103  of the duplex guide  101  is moved by the front end of the printing medium  1 , the duplex guide  101  rotates in the clockwise with the sensor arm  106 . The duplex guide  101  is returned to the horizontal position when the printing medium  1  is not in contact with the guide pin  103 .  
         [0050]    Also, a sensor  110  is disposed at a duplex printer frame  151  of FIG. 7 to sense an upper surface  106   a  of the sensor arm  106  when the duplex guide  101  is at the horizontal position.  
         [0051]    The jam removing mechanism separates the pressure roller  141  from the heat roller  142  in order to remove a jammed printing medium  1  from the fixing unit  143  and includes a jam removing lever  130 , the jam removing shaft  121 , the actuator separator  123 , and the jam removing cam  125  as shown in FIG. 6.  
         [0052]    The jam removing lever  130  has one end  131  hinged to the duplex printer frame  151 , at which the pressure roller  141  is disposed, and another end  135 . The jam removing lever  130  has a penetrating hole  133  formed at a middle portion between the one end  131  and another end  135 , and a rotation shaft  141   a  of the pressure roller  141  is movably inserted into the penetrating hole  133  of the jam removing lever  130 . The jam removing lever  130  can be disposed at one side of the pressure roller  141 , but the jam removing lever  130  may be disposed at each of both sides of the pressure roller  141 .  
         [0053]    The jam removing shaft  121  is inserted into the hollow cylinder  102  of the duplex guide  101 , and both ends thereof are rotatably mounted on the duplex printer frame  151 .  
         [0054]    The actuator separator  123  is disposed on a portion of one side of the jam removing shaft  121 , where there is no interference with the duplex guide  101 , and therefore, if the actuator separator  123  rotates by a second predetermined angle, the jam removing shaft  121  is rotated as much as the actuator separator  123  is rotated.  
         [0055]    In FIGS. 3 and 5, a low part of the actuator separator  123  has a rib  124  formed on another portion of the jam removing shaft  121  to be in contact with an interfering portion  105  of the duplex guide  101 . The rib  124  is formed such that, when the duplex guide  101  is in the horizontal position R1, the actuator separator  123  is almost in a vertical position, if the actuator separator  123  rotates in a clockwise direction by the second predetermined angle, the duplex guide  101  is rotated to about 180° from the horizontal position R1 by the weight of duplex guide  101  after being rotated to the second predetermined angle by the rib  124  as much as the actuator separator  123  is rotated. At this time, the actuator separator  123  is formed to rotate to about 110° from the horizontal position R1 so that the duplex guide  101  can further rotate by the weight thereof as shown in FIG. 9.  
         [0056]    The jam removing cam  125  projects from a third portion of the jam removing shaft  121  in almost the same direction as the actuator separator  123  projects from the one portion of the jam removing shaft  121 . There is no interference between the duplex guide  101  and the jam removing cam  125  or the actuator separator  123 , except the interfering portion  105  of the duplex guide  101  and the rib  124  of the actuator separator  123 . Accordingly, if the actuator separator  123  rotates, the jam removing cam  125  also rotates with the actuator separator  123  as much as the actuator separator  123  rotates.  
         [0057]    Because a cam part of the jam removing cam  125  is formed to correspond to a distal end  135  of the jam removing lever  130 , if the actuator separator  123  rotates by the predetermined angle, the jam removing cam  125  smoothly touches the another end  135  of the jam removing lever  130  and thus rotates the jam removing lever  130  by a third predetermined angle about a hinge of the one end  131 . Accordingly, the pressure roller  141  is separated from the heat roller  142  by the jam removing lever  130  to provide a free space between the pressure roller  141  and the heat roller  142 .  
         [0058]    The jam removing cam  125  is formed to allow the jam removing lever  130  to make enough space to allow the jammed printing medium  1  to be easily removed between the pressure roller  141  and the heat roller  142 .  
         [0059]    Also, because the jam removing cam  125  is disposed to correspond to the jam removing lever  130 , the jam removing cam  125  can be disposed at one side of the jam removing shaft  121 . The jam removing mechanism may include a plurality of jam removing cams  125 , and the jam removing cams  125  may be disposed at both sides of the jam removing shaft  121 .  
         [0060]    From now on, operations according to the embodiment of the present invention will be described referring to FIGS. 7 through 9.  
         [0061]    When a printing operation of printing one side of the printing medium  1  is finished, duplex printing operations are performed next.  
         [0062]    The printing medium  1  stacked in a paper cassette is moved into a development unit  145  by a feeding roller  149  and transporting rollers  147 , and thus a printing image is transferred to the one side of the printing medium  1  by the development unit  145 . Then, the printing medium  1  having the transferred printing image is passed through a fixing unit  143  and thus the transferred printing image is fixed on the one side of the printing medium  1  by the pressure roller  141  and the heat roller  142  thereof.  
         [0063]    After passing through out the fixing unit  143 , the printing medium  1  strikes and rotates the duplex guide  101  to a guiding position R2 by the front end thereof, and the printing medium  1  is moved to the discharge passage  160 . And then, when the printing medium  1  is not in contact with the duplex guide  101 , the duplex guide  101  is returned to the horizontal position R1 by the weight thereof. The printing medium  1  moving into the discharge passage  160  is discharged into a discharge tray  165 .  
         [0064]    When both sides of the printing medium  1  are printed, the next duplex printing operations are as follows.  
         [0065]    When the printing medium  1 , which has been printed on the one side thereof according to the previous printing operation described above, is moved through the discharge passage  160 , the duplex guide  101  is returned to the horizontal position R1 so that the sensor arm  106  is located at a position Q1 corresponding to the sensor  110 .  
         [0066]    If the sensor  110  senses the sensor arm  106 , the sensor  110  sends a signal to a duplex printer controller (not shown). Then the discharge roller  161  is rotated in a reverse direction by the duplex printer controller.  
         [0067]    If the discharge roller  161  rotates in the reverse direction, the printing medium  1  is moved in the opposite direction opposite to the discharge direction. At this time, because the duplex guide  101  is at the horizontal position R1, the printing medium  1  is moved over the duplex guide  101  and into the duplex printing passage  150 .  
         [0068]    The printing medium  1  is moved into the development unit  145  by transporting rollers  153 , 147 . At this time, the other side of the printing medium  1  faces upward, and then is printed by the development unit  145  and the fixing unit  143 .  
         [0069]    The printing medium  1  printed on both sides thereof rotates the duplex guide  101  upward. Next, the printing medium  1  is moved into the discharge passage  160  and discharged to the discharge tray  165  by the discharge rollers  161  and  163 .  
         [0070]    Finally, the operation of removing a jammed printing medium  1  jammed in the fixing unit  143  as shown in FIG. 9 is described as follows.  
         [0071]    When the jammed printing medium  1  is jammed in the fixing unit  143 , a user rotates the actuator separator  123  by the second predetermined angle. Here, the second predetermined angle is generally set to about 110°.  
         [0072]    If the actuator separator  123  rotates, the jam removing cam  125  is rotated by the jam removing shaft  121  as much as the actuator separator  123  rotates. The jam removing shaft  121  and the jam removing cam  125  are integrally formed with the actuator separator  123 .  
         [0073]    And then, the jam removing lever  130  is rotated at the third predetermined angle by the jam removing cam  125  contacting the another end  135  of the jam removing lever  130 . If the jam removing lever  130  rotates by the third predetermined angle, the rotation shaft  141   a  of the pressure roller  141 , which is inserted in the penetrating hole  133  of the jam removing lever  130 , rotates by the same third predetermined angle as the jam removing lever  130  about the hinge of the one end  131  of the jam removing lever  130  at the same time. Accordingly, the pressure roller  141  is separated from the heat roller  142 .  
         [0074]    Therefore, the jammed printing medium  1  jammed between the pressure roller  141  and the heat roller  142 , can be easily removed.  
         [0075]    Also, if the actuator separator  123  rotates by about 110° from the vertical position, the duplex guide  101  rotates to about 110° by the rib  124  of the actuator separator  123  and the interfering portion  105  of the duplex guide  101  from the horizontal position R1 and then further rotates to 180° from the horizontal position R1 to be positioned at a second horizontal position R3 by the weight of the duplex guide  101 . Because the duplex guide  101  is at the second horizontal position R3, the jammed printing medium  1 , not only in the fixing unit  143  but also in the discharge passage  160 , can be easily removed.  
         [0076]    According to the multi-function actuator constructed in accordance with the embodiment of the present invention, one side or both sides of the printing medium  1  can be easily printed, and the jammed printing medium  1  can be easily removed, because the pressure roller  141  is separated from the heat roller  142  and the discharge passage is not blocked by the duplex guide  101 . In other words, one actuator has multi functions, such as printing on one side of the printing medium  1 , printing on both sides of the printing medium  1 , and removing the jammed printing medium  1 .  
         [0077]    Although a few embodiments of the present invention 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 invention, the scope of which is defined in the appended claims and their equivalents.