Abstract:
A paper feed device includes a setting plate, a support unit, a driving unit, a power transmission mechanism, a link mechanism, and an operation lever. The support unit elevatably supports the setting plate, and elevates the setting plate when the support unit receives a driving force. The driving unit drives the support unit. The power transmission mechanism transmits the driving force from the driving unit to the support unit. The operation lever is switched between a first state and a second state. When the operation lever is in the first state, the power transmission mechanism transmits the driving force to the support unit. When the operation lever is in the second state, the link mechanism cuts off the transmission of the driving force to the support unit.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an image forming apparatus such as a printer, a facsimile machine or a copying machine and to a paper feed device for supplying paper to the image forming apparatus.  
           [0003]    2. Description of the Related Art  
           [0004]    As a paper feed device for supplying paper to an image forming apparatus such as a printer, a facsimile machine or a copying machine, there has been known a device having a configuration in which a setting plate having sheets of paper stacked thereon is suspended with a wire rope or the like to allow a large amount of sheets of paper to be stored and in which the wire rope is wound by means of a motor or the like to elevate the setting plate to control the uppermost surface of the sheets of paper at a predetermined elevation for feeding sheets of paper.  
           [0005]    In this type paper feed device, since a paper feed unit such as a pickup roller abuts on the uppermost surface of the sheets of paper placed on the setting plate, the setting plate elevated by the motor or the like needs to be once moved down in order to supply sheets of paper.  
           [0006]    In the related-art paper feed device, therefore, the setting plate is elevatably provided in a paper cassette, which can be attached/detached to/from the image forming apparatus. When the paper cassette is removed from the image forming apparatus, the setting plate in the paper cassette is separated from a driving shaft of a motor in the image forming apparatus so that the setting plate can go down because of its own weight (JP-A-Hei.8-217266).  
         SUMMARY OF THE INVENTION  
         [0007]    There is however a demand for reduction in size of the image formation apparatus. It is conceived that the paper feed device is formed without use of any paper cassette in order to reduce the size of the paper feed device. That is, the paper feed device is directly incorporated in the body of the image forming apparatus to dispense with any mechanism for attaching/detaching the paper cassette to/from the image forming apparatus to thereby attain reduction in size of the image forming apparatus.  
           [0008]    However, when the paper feed device is formed without use of any paper cassette, the setting plate cannot be moved down through the action of removing the paper cassette as described above.  
           [0009]    On the other hand, it may be conceived that current conduction of the motor is cut off in order to move down the setting plate incorporated in the body of the image forming apparatus. In this method, there is however the possibility that the setting plate may not be moved down or a long time may be required for moving down the setting plate because of friction in a driving system.  
           [0010]    Another possible method to solve the problem is to operate a switch or the like to reverse the motor to move down the setting plate when paper supply is required. This method, however, has a problem that a circuit for reversing the motor is required or paper supply cannot be made when the apparatus is supplied with no power.  
           [0011]    The invention is developed in consideration of the problems. An object of the invention is to provide a paper feed device including a setting plate, which is placed sheets of paper thereon and is elevatably incorporated in an image forming apparatus, so that the elevation of the setting plate is controlled by a motor or the like, in which the setting plate can be moved down quickly in spite of simple configuration when sheets of paper are supplied.  
           [0012]    According to an embodiment of the invention, a paper feed device includes a setting plate, a support unit, a driving unit, a power transmission mechanism, a link mechanism, and an operation lever. A plurality of sheets of paper are placed on the setting plate. The support unit elevatably supports the setting plate, and elevates the setting plate when the support unit receives a driving force. The driving unit drives the support unit so that a uppermost sheet of paper placed on the setting plate is positioned at a predetermined height for feeding the sheets of paper. The power transmission mechanism transmits the driving force from the driving unit to the support unit. The link mechanism cuts off the transmission of the driving force to the support unit. The operation lever is switched between a first state and a second state. When the operation lever is in the first state, the power transmission mechanism transmits the driving force to the support unit. When the operation lever is in the second state, the link mechanism cuts off the transmission of the driving force to the support unit. The support unit is disengaged from the driving unit by an operation of the link mechanism. According to the embodiment of the invention, an image forming apparatus includes a paper feed device and a recording device. The paper feed device feeds a sheet of paper. The recording device forms an image on the sheet of paper fed from the paper feed device. The paper feed device includes a setting plate, a support unit, a driving unit, a power transmission mechanism, a link mechanism, and an operation lever. A plurality of sheets of paper are placed on the setting plate. The support unit elevatably supports the setting plate, and elevates the setting plate when the support unit receives a driving force. The driving unit drives the support unit so that a uppermost sheet of paper placed on the setting plate is positioned at a predetermined height for feeding the sheets of paper. The power transmission mechanism transmits the driving force from the driving unit to the support unit. The link mechanism cuts off the transmission of the driving force to the support unit. The operation lever is switched between a first state and a second state. When the operation lever is in the first state, the power transmission mechanism transmits the driving force to the support unit. When the operation lever is in the second state, the link mechanism cuts off the transmission of the driving force to the support unit. The support unit is disengaged from the driving unit by an operation of the link mechanism.  
           [0013]    According to the embodiment, the paper feed device includes a setting plate, a support unit, a power transmission mechanism, a link mechanism, and an operation lever. A plurality of sheets of paper are placed on the setting plate. The support unit elevatably supports the setting plate, and elevates the setting plate when the support unit receives a driving force. The power transmission mechanism transmits a driving force, supplied from external, to the support unit. The link mechanism cuts off the transmission of the driving force to the support unit. The operation lever is switched between a first state and a second state. When the operation lever is in the first state and the driving force is supplied from the external, the power transmission mechanism transmits the driving force to the support unit. When the operation lever is in the second state, the link mechanism cuts off the transmission of the driving force to the support unit. The support unit is disengaged from the driving unit by an operation of the link mechanism. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a schematic side view of an ink jet printer having a paper feed device according to an embodiment of the invention.  
         [0015]    [0015]FIG. 2 is a side view of the paper feed device according to this embodiment in the case where a setting plate is moved up.  
         [0016]    [0016]FIG. 3 is a front view of the paper feed device according to this embodiment in the case where the setting plate moves up.  
         [0017]    [0017]FIG. 4 is a side view of the paper feed device according to this the embodiment in the case where the setting plate moves down.  
         [0018]    [0018]FIG. 5 is a side view of a paper feed device  100  according to a modification.  
         [0019]    [0019]FIG. 6 is a section view of the paper feed device  100  taken along a line VI-VI in FIG. 5.  
         [0020]    [0020]FIG. 7 is a schematic side view of an inkjet printer having the paper feed device  100  according to the modification of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]    An embodiment of the invention will be described below with reference to the drawings.  
         [0022]    [0022]FIG. 1 is a schematic side view showing an overall internal configuration of an ink jet printer  1  including a paper feed device  2  according to an embodiment of the invention.  
         [0023]    The ink jet printer  1  includes the paper feed device  2 , which supplies sheets of paper P one by one, and a recording device  3 , which prints images on the sheets of paper P supplied by the paper feed device  2 . The side on which the paper feed device  2  is attached (i.e., the left side in FIG. 1) is the front side of the ink jet printer  1 .  
         [0024]    As shown in FIG. 1, the paper feed device  2  includes a paper feeder chassis  20 , a pickup roller section  80 , and a sensor  89 . As shown in FIGS. 2 and 3, which are a side view and a front view of the paper feeder chassis  20 , the paper feeder chassis  20  includes a setting plate  23  on which sheets of paper are placed, support beams  26  and  27 , a paper stopper  28 , a stepping motor  51 , a gear  52 , a sun gear  53 , a planet gear  54 , a gear fixing plate  55 , a gear  56 , power transmission belts  57 , and a gear releasing plate  32 .  
         [0025]    [0025]FIGS. 2 and 3 are views showing a state in which a surface of the setting plate  23  on which sheets of paper P are to be placed is made horizontal after the paper feeder chassis  20  of the paper feed device  2  is removed from the ink jet printer  1 . The state after removal of the paper feeder chassis  20  is shown in FIG. 2 for facilitating understanding of the internal structure of the paper feed device  2 .  
         [0026]    The paper feeder chassis  20  is substantially shaped like a box having opened front and top sides. The paper feeder chassis  20  is attached to the recording device  3  in the condition that the paper feed chassis  20  is inclined so that the recording device  3  side of the paper feed chassis  20  is lower than the opposite side.  
         [0027]    For example, the setting plate  23  is a flat plate having a size to allow sheets of postcard-size paper P to be placed thereon. A pair of left and right flanges  24  and a pair of left and right flanges  25  are provided at the front and rear sides of the bottom of the plate, respectively. A pair of left and right flanges  21  and a pair of left and right flanges  22  are provided in the paper feeder chassis  20  so as to be opposite to the pairs of flanges  24  and  25 , respectively. The distance between the left and right flanges  21  is equal to the distance between the left and right flanges  25 . The distance between the left and right flanges  22  is equal to the distance between the left and right flanges  24  and narrower than the distance between the left and right flanges  21 . Each of the flanges  21  is pierced by a long hole  211  which is formed to extend in the front-rear direction in parallel with the surface of the setting plate  23  on which sheets of paper are placed. Similarly, each of the flanges  24  is pierced by a long hole  241  which is formed to extend in the front-rear direction in parallel with the surface of the setting plate  23  on which sheets of paper are placed. Each of the flanges  22  is pierced by a circular hole. Similarly, each of the flanges  25  is pierced by a circular hole.  
         [0028]    A pair of left and right support beams  26  and a pair of left and right support beams  27 , each of which is made of a rod-like plate material, are inserted in the holes of the flanges  22 ,  24  and  21 ,  25  through rotating shafts  65 ,  69  and  66 ,  68  so that the pair of support beams  26  and the pair of support beams  27  cross each other between the setting plate  23  and the bottom of the paper feeder chassis  20  to support the setting plate  23 . That is, each of the support beams  26  has one end fixed to the rotating shaft  69  rotatably supported in the holes of the flanges  22 , and the other end fixed to the rotating shaft  65  movably and rotatably inserted in the long holes  241  of the flanges  24 . Each of the support beams  27  has one end fixed to the rotating shaft  66  rotatably supported in the holes of the flanges  25 , and the other end fixed to the rotating shaft  68  movably and rotatably inserted in the long holes  211  of the flanges  21 . The shaft distance between the rotating shafts  65  and  69  for the support beams  26  is selected to be equal to the shaft distance between the rotating shafts  66  and  68  for the support beams  27 . The pairs of support beams  26  and  27  are rotatably connected to each other through the rotating shaft  67  in the center position of the shaft distance.  
         [0029]    Accordingly, the setting plate  23  is supported through the support beams  26  and  27  so as to be substantially parallel with the bottom of the paper feeder chassis  20  and movable in the up-down direction.  
         [0030]    Incidentally, the length of the rotating shaft  66  is larger than the width of the paper feeder chassis  20 , so that the rotating shaft  66  protrudes from long holes  20   a , which are provided in sides of the paper feeder chassis  20  to extend in the up-down direction.  
         [0031]    The stepping motor  51  is a motor, which rotates by an angle corresponding to the number of pulses in a pulse voltage received from the outside. The stepping motor  51  is provided with the gear  52  disposed on a driving shaft of the motor. The stepping motor  51  is attached to the bottom of the paper feeder chassis  20  from below.  
         [0032]    The gear  52  engages with the sun gear  53 . The sun gear  53  engages with the planet gear  54 . The planet gear  54  is held by the gear fixing plate  55  so that the planet gear  54  revolves around the sun gear  53 . The planet gear  54  engages with the gear  56  when the planet gear  54  is at a predetermined angular position relative to the sun gear  53 .  
         [0033]    A rotating shaft  64  is rotatably supported through the left and right sides of the paper feeder chassis  20 . The gear  56  is fixed to the rotating shaft  64 . Toothed pulleys  59  are fixed to opposite ends of the rotating shaft  64 , respectively. The power transmission belts (timing belts)  57  are stretched between the toothed pulleys  59  and toothed pulleys  61  provided in the left and right of the top portion of the paper feeder chassis  20  located above the pulleys  59 , respectively.  
         [0034]    Support bodies  58  to form horizontal protrusions are provided in the middle of the power transmission belts  57 . Respective top surfaces of the support bodies  58  abut on the rotating shaft  66  protruding from the long holes  20   a  in left and right sides of the paper feeder chassis  20 , from below.  
         [0035]    The paper stopper  28  is made of a plate-like member substantially shaped like a rectangle. A paper stopper knob  29  having a shape allowed to be gripped by a user is provided in the center of a plate surface of the paper stopper  28 .  
         [0036]    A paper stopper holding portion  33 , which is a plate bent so as to be L-shaped, is fixed to the paper feeder chassis  20  so that the paper stopper holding portion  33  can move back and forth in parallel with the left-right direction in the condition that one part of the bent shape abuts on the bottom of the paper feeder chassis  20  while the other part of the bent shape faces upward.  
         [0037]    The paper stopper  28  is mounted so as to be rotatable at a lower end portion  28   c  of the paper stopper  28  so that the paper stopper  28  is changed from an “erected state” to an “open state”. In the “erected state”, the upward bent part of the paper stopper holding portion  33  makes the plate surface of the paper stopper  28  be substantially perpendicular to the bottom of the paper feeder chassis  20 . In the “open state”, the plate surface of the paper stopper  28  is inclined at 90 degrees in the forward direction so as to be substantially parallel with the bottom of the paper feeder chassis  20 . The paper stopper  28  has a protrusion  28   a , which is provided at a position far from the lower end portion  28   c  held by the paper support holding portion  33  and protrudes in a direction parallel with the lower end portion  28   c.    
         [0038]    The gear releasing plate  32  is made of a plate member substantially shaped like a rectangle. The gear releasing plate  32  has one end formed as a fork portion  32   a  forked into two parts, and the other end rotatably attached to the paper feeder chassis  20  at a fixed portion  32   c  located substantially above the gear fixing plate  55 . The protrusion  28   a  of the paper stopper  28  is sandwiched between the two parts of the fork portion  32   a . Incidentally, the fork portion  32   a  has a forked shape having such a length that the protrusion  28   a  can be sandwiched between the two parts of the fork portion  32   a  regardless of the rotation of the paper stopper  28  and the back-and-forth movement of the paper stopper holding portion  33 .  
         [0039]    The gear releasing plate  32  has a protrusion  32   b , which extends downward. On the other hand, an upper portion of the gear fixing plate  55  has a protrusion  55   a , which extends upward. The protrusions  32   b  and  55   a  are disposed so that the protrusion  32   b  abuts against the protrusion  55   a  when the protrusion  32   b  rotates counterclockwise in FIG. 2.  
         [0040]    The paper stopper holding portion  33  has a flange  33   a  protruding downward from the bottom of the paper feeder chassis  20 . A side lower end portion  28   b  similar to the flange  33   a  is provided at a lower end of the paper stopper  28 . A torque spring  34  is suspended between the flange  33   a  and the side lower end portion  28   b . Incidentally, the flange  33   a  and the side lower end portion  28   b  are disposed so that an isosceles right triangle is drawn by points at which the torque spring  34  is fixed to the flange  33   a  and the side lower end portion  28   b  and a point of the lower end portion  28   c  at which the paper stopper  28  is held when the paper stopper  28  is in the “erected state”. In this arrangement, even when the paper stopper  28  is in the “open state”, a symmetric isosceles right triangle can be drawn to thereby make the mount distance of the torque spring  34  equal to that in the “erected state”. When the paper stopper  28  is at in any other position than the two positions, the distance between the fixed positions of the torque spring  34  changes so that the torque spring  34  generates torque. For this reason, the paper stopper  28  is kept in either of the “erected state” and the “open state” when the paper stopper  28  is not moved by a user.  
         [0041]    Lateral paper stoppers  74  each shaped like a flat plate for aligning the sheets of paper P stacked on the setting plate  23  in the left-right direction in the paper feeder chassis  20  are provided on the bottom of the paper feeder chassis  20  so as to be movable in the left-right direction.  
         [0042]    The pickup roller section  80  is attached to the recording device  3  through a frame  81  so as to be located above the paper feeder chassis  20 . When the sheets of paper Pare at a predetermined elevation, the pickup roller section  80  urges a roller  88  to press against the sheets of paper P. When a motor  85  of the recording device  3  rotates, a pulley  86  is rotated by a power transmission belt  87  through a gear  84  rotated by the rotation of the motor  85 . As a result, the roller  88  in contact with a sheet of paper P is rotated, so that the sheet of paper P is fed to the recording device  3  side.  
         [0043]    The sensor  89  is a photosensitive position sensor, which applies light onto the sheet of paper P perpendicularly, detects light reflected from the sheet of paper P and outputs a signal corresponding to the distance to the sheet of paper P in accordance with the intensity of the light.  
         [0044]    Next, the operation of the paper feed device  2  in each state of the paper stopper  28  will be described.  
         [0045]    When the paper stopper  28  is in the “erected state”, the protrusion  28   a  is located in a vertical direction with respect to the rotating shaft of the paper stopper  28 . Accordingly, the fork portion  32   a  of the gear releasing plate  32  is at the highest position whereas the protrusion  32   b  of the gear releasing plate  32  pivoting on the fixed portion  32   c  is in the foremost position.  
         [0046]    At this time, the protrusion  32   b  and the protrusion  55   a  of the gear fixing plate  55  do not abut against each other any more. When the stepping motor  51  rotates clockwise in FIG. 2, the gear  52  rotates clockwise, the sun gear  53  rotates counterclockwise, and the planet gear  54  revolves around the sun gear  53  counterclockwise along with the gear fixing plate  55  and engages the gear  56 . Then, the gear  56  is rotated counterclockwise by the planet gear  54 , and rear-side parts of the power transmission belts  57  are moved up through the toothed pulleys  59 . Thus, the support bodies  58  move up, and the rotating shaft  66  is lifted up accordingly to move up the setting plate  23 .  
         [0047]    When the paper stopper  28  is operated to enter the “open state”, the protrusion  28   a  moves forward and downward while drawing a circular locus as shown in FIG. 4. As a result, the fork portion  32   a  of the gear releasing plate  32  is moved down, and the protrusion  32   b  rotates counterclockwise about the fixed portion  32   c . Thus, the protrusion  32   b  and the protrusion  55   a  of the gear fixing plate  55  abut against each other, and the protrusion  55   a  is pressed rearward. Then, the gear fixing plate  55  rotates clockwise to disengage the planet gear  54  from the gear  56 . As a result, the setting plate  23  loses the retaining force given by the stepping motor  51  and goes down because of its own weight.  
         [0048]    On the other hand, the recording device  3  includes a paper transport belt  14  for transporting a sheet of paper supplied by the paper feed device  2 , ink cartridges  12  in which four kinds of color ink, i.e., cyan, magenta, yellow, and black are reserved respectively, four ink jet heads  11  for printing the four kinds of color ink on the sheet of paper P, and a control section  19  for performing various kinds of control.  
         [0049]    The paper transport belt  14  has its surface having viscosity sufficient to hold the sheet of paper P without any slip during transportation. As shown in FIG. 1, the paper transport belt  14  is stretched between a driving roller  63  and a driven roller  64 . The driving roller  63  rotates so that the sheet of paper P fed from the paper feed device  2  is transported so as to pass underneath the ink jet heads  11 .  
         [0050]    Each of the ink jet heads  11  has ejection holes through which ink is ejected when a pressure wave is generated in each nozzle by vibration of a piezoelectric element. The ejection holes are arranged to cover the width of the sheet of paper P in the paper transporting direction. Ink corresponding to one row in the direction of the width of the sheet of paper P is ejected at once to perform printing. This makes high-speed printing possible.  
         [0051]    The control section  19  controls the amounts of the four kinds of ink ejected from the ink jet heads  11 , the operation of the motor  85  for driving the pickup roller section  80 , the operation of the driving roller  63  and the operation of the stepping motor  51  of the paper feed device  2  according to external image signals received from a personal computer or the like.  
         [0052]    As described above, the control section  19  of the recording device  3  drives the stepping motor  51  to move up the setting plate  23  so that the distance to the sheet of the paper P which distance is detected by the sensor  89  of the paper feed device  2  reaches the elevation (i.e., a preset elevation) at which the sheet of paper P can be picked up by the pickup roller section  80 . When image data are input from the outside, the control section  19  drives the motor  85  to rotate the roller  88  of the pickup roller section  80  to feed one sheet of paper onto the paper transport belt  14 , and drives the driving roller  63  to transport the sheet of paper P just under the ink jet heads  11  through the paper transport belt  14 . The four kinds of ink reserved in the ink cartridges  12  are ejected from the ink jet heads  11  according to the image data while the sheet of paper P is transported, so that an image is formed on the sheet of paper P.  
         [0053]    As described above, in the paper feed device  2  according to the embodiment of the invention, a driving force is transmitted from the stepping motor  51  to the setting plate  23  when the paper stopper  28  is in the “erected state”, so that the setting plate  23  is held at a position to allow feeding of the uppermost one of sheets of paper placed on the setting plate  23 . On the other hand, when the paper stopper  28  is pulled forward so as to be in the “open state”, the planet gear  54  is disengaged from the gear  56 , so that the setting plate  23  moves down because the setting plate  23  cannot be held at that elevation any more.  
         [0054]    For this reason, the paper stopper  28  can be ordinarily set in the “erected state” to allow the setting plate  23  to be lifted up. When paper supply is required, the paper stopper  28  can be pulled so as to be in the “open state” and the setting plate  23  can be moved down to make paper P supply possible.  
         [0055]    When the paper stopper  28  is pulled forward so as to be in the “open state”, the paper stopper  28  can be retracted from sheets of paper P, so that sheets of paper P can be supplied from the front shown in FIG. 1. In this manner, the operation of supplying sheets of paper can be made easily because the action of descending the setting plate  23  and the action of retracting the paper stopper  28  can be performed simultaneously.  
         [0056]    When the positions of the paper stopper holding portion  33  and the lateral paper stoppers  74  are changed, sheets of paper different in size can be stored  
         [0057]    In the paper feed device  2  of the embodiment, the paper stopper  28  can align one end edges of the sheets of paper. That is, a function, which is required for a paper stopper plate, for aligning the sheets of paper in the paper feed device  2  can be implemented by the paper stopper  28 . It is therefore possible to eliminate a space for provision of an operation lever and reduce the number of components. Advantageously, this leads to reduction in size of the image forming apparatus  1 .  
         [0058]    In the embodiment, sheets of paper can be supplied when inserted in a direction lateral to the setting plate  23  in a condition that the paper feed section  80  is located above the setting plate  23 . In this case, it is necessary to move the paper stopper plates  74  provided on both sides of the sheets of paper. If a state where the paper stopper plates  74  are moved is chosen as the “open state” to block the transmission path of the driving force, the operation of moving the paper stopper plate  74  and the operation of moving down the setting plate  23  can be performed with a single action.  
         [0059]    (Modification)  
         [0060]    Although the embodiment of the invention has been described above, the invention is not limited to the specific embodiment but may be carried out in various modes.  
         [0061]    Although this embodiment has been described on the case where the position of the planet gear  54  is changed by the gear fixing plate  55  to thereby switch the transmission of power from the stepping motor  51  to the power transmission belts  57 , the invention may be also applied to a case where the transmission of power is switched by another method. For example, configuration may be made so that a dry type clutch for opening/closing the gap between the gears  52  and  56  in accordance with the angle of the gear releasing plate  32  is provided.  
         [0062]    Although this embodiment has been described on the case where the direction of the paper stopper  28  is changed to thereby switch power transmission, the invention may be also applied to a case where power transmission is switched through an operation of changing the direction of another component or to a case where an exclusive lever is provided for switching power transmission. However, this embodiment is preferred because it requires a smaller number of components and a smaller space for equipment.  
         [0063]    (Modification 2)  
         [0064]    In the embodiment, the paper feeder chassis  20  includes the step motor  51  the driving force of which is transmitted via the gears  52 ,  53 ,  54  to the gear  56 , thereby to drive the power transmission belts  57 . However, the step motor  51  may be omitted and the driving force of the motor  85  provided in the recording device  3  may be used via the gear  84  to drive the power transmission belts  57 . A specific example of this modification will be described below with reference to FIGS. 5-7.  
         [0065]    In the following description, parts similar to those in the embodiment will be assigned the same reference numerals and description thereto will be omitted. FIG. 5 is a side view of a paper feed device  100  according to this modification. FIG. 6 is a section view of the paper feed device  100  taken along a line VI-VI in FIG. 5. The paper feeder chassis  20  includes the sun gear  53 , the planet gear  54 , the gear fixing plate  55 , the power transmission belts  57 , an idle gear  101 , a gear  102 , a gear  103 , and toothed pulleys  104 . The gear  103  engages with the idle gear  101 . The idle gear  101  engages with the sun gear  53 . The planet gear  54  engages with the gear  102  when the planet gear  54  is at a predetermined angular position relative to the sun gear  53 . A power transmission belt (timing belt)  105  is stretched between the gear  84  and the toothed pulley  104 . When the rotating shaft  64  rotates, the toothed pulleys  59  and the gear  102  are rotated together with the rotating shaft  64 , and vice versa. On the other hand, the toothed pulley  104  is attached to the rotating shaft  64  via a bearing (not shown). Thus, the rotation shaft  64  and the toothed pulley  104  rotate independently of each other. Incidentally, the toothed pulley  104  is formed with the gear  103  integrally as shown in FIG. 6. The gear  84  is configured as follows. When the motor  85  rotates the gear  84  clockwise, the gear  84  moves the power transmission belt  87 , but does not move the power transmission belt  105 . On the other hand, when the motor  85  rotates the gear  84  counterclockwise, the gear  84  moves the power transmission belt  105 , but does not move the power transmission belt  87 . In order to implement this configuration, the gear  84  may have a clutch mechanism such as one-way clutches.  
         [0066]    Next, an operation of the paper feed device  100  according to this modification will be described. First, consider that the paper stopper  28  is in the “erected state”. At this time, the protrusion  32   b  and the protrusion  55   a  of the gear fixing plate  55  do not abut against each other. If the motor  85  rotates the gear  84  clockwise, the gear  84  rotates the pulley  86  clockwise through the power transmission belt  87 . The pick up roller  88  contacting with the uppermost sheet of paper P is rotated counterclockwise. Since the gear  84  does not move the power transmission belt  105 , the driving force of the motor  85  is not transmitted to the power transmission belts  57 . However, when the paper stopper  28  is in the “erected state”, the planet gear  55  engages with the gear  102 . Thus, the power transmission belts  57  are not moved. As a result, the setting plate  23  does not move downward, but can keep its height. Accordingly, the pickup roller  88  can pick up and feed the sheet of paper P to the recording device  3 .  
         [0067]    When the motor  85  rotates the gear  84  counterclockwise and the paper stopper  28  is in the “erected state”, the gear  84  rotates the toothed pulley  104  and the gear  103  counterclockwise through the power transmission belt  105 . The idle gear  101  is rotated clockwise; the sun gear  53  rotated counterclockwise; the planet gear  54  is rotated clockwise; and the gear  102  is rotated counterclockwise. As a result, the rear-side parts of the power transmission belts  57  are moved upward. Thus, the support bodies  58  move up, and the rotating shaft  66  is lifted up to move up the setting plate  23 . Since the gear  84  does not move the power transmission belt  87  at this time, the pickup roller  88  does not rotate during the setting plate  23  is moving up.  
         [0068]    If the paper stopper  28  is changed from the “erected state” to the “open state”, the protrusion  32   b  and the protrusion  55   a  of the gear fixing plate  55  abut against each other in a similar manner to the embodiment. Thus, the protrusion  55   a  is pressed rearward. Then, the gear fixing plate  55  rotates clockwise to disengage the planet gear  54  from the gear  102 . As a result, since the rotating shaft  64  becomes rotating freely, the setting plate  23  loses the retaining force given through the power transmission belts  57  and goes down because of its own weight.