Patent Publication Number: US-2005127598-A1

Title: Sheet convey apparatus

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates to a sheet convey apparatus to convey a sheet such as a document used in a copying machine, scanner, facsimile apparatus, or the like and, more particularly, to a sheet convey apparatus having a devised removal mechanism which is used when a sheet such as a document jams in an apparatus that reads image information on each of two sides of a sheet-type document.  
      In general, in most of sheet-type documents such as a printing product, image information is printed or recorded on the two sides of the document. Various types of sheet convey apparatuses have been proposed which can read image information recorded on the two sides of a document. In most of the document-reading sheet convey apparatuses, the reading surface of the document is moved on a glass platen, and image information is read by a one-dimensional image sensor with a raster-scan scheme. To read image information recorded on the two sides of the document by a sheet convey apparatus of this type, after one reading surface of the document is read, the other reading surface must be moved while it opposes the glass platen. For this reason, an apparatus that reads the two sides of the document automatically is provided with a reversing mechanism which reverses the reading surfaces after one side of the document is read.  
      An ordinary document-reading sheet convey apparatus conveys various types of documents as a convey target. Accordingly, paper jamming (jam) of the document in a convey mechanism may occur. When the sheet convey apparatus having the reversing mechanism which reverses the reading surfaces of the document is compared to the sheet convey apparatus that reads only one side of the document, the convey path becomes complicated and jam may frequently occur. In view of this, sheet convey apparatuses provided with various types of jamming countermeasures have been proposed.  
      For example, according to the first proposal suggested by Japanese Patent Laid-Open No. 11-147634, when jamming occurs, it is solved by conveying a document backward. According to the first proposal, when the document stays on a reversal return path, the staying document is conveyed backward from the reversal return path, and is then discharged onto a discharge dray without passing through the reversal return path, so that the document can be removed from the reversal return path easily. When document non-feed jamming occurs, the document is conveyed backward and forcibly discharged onto the discharge tray.  
      The first proposal is premised on occurrence of light jamming with which a document can be conveyed backward. When the document is to be conveyed backward, if the conveyance itself is impossible as in a case wherein the document winds around a convey roller, the document that has jammed cannot be removed. Also, when the document is partly torn off upon occurrence of jamming, the torn pieces cannot be removed by conveying the document backward.  
      In view of this, the second proposal as shown in Japanese Patent Laid-Open No. 2002-348052 has been suggested, in which a convey path is divided into several convey path mechanisms in a vertical direction. According to this proposal, when jamming occurs, an upper convey path mechanism is opened by rotating it about a predetermined fulcrum as the center, to expose a lower convey path mechanism. More specifically, a discharge cover surrounding the uppermost portion and side portions of the convey path is opened. Then, a discharge guide arranged at the middle position is opened in a direction opposite to the direction to open the discharge cover, to expose a convey path mechanism arranged at the lowermost portion.  
      According to the second proposal described above, the convey path is divided into three regions in the vertical direction. The convey path mechanism at the uppermost portion and the convey path mechanism arranged at the middle position are sequentially opened in opposite directions, to expose the convey path mechanism arranged at the lowermost portion. Thus, a document jamming in a convey path formed between the convey path mechanism at the uppermost portion and the convey path mechanism at the middle position, and the document jamming in a convey path formed between the convey path mechanism at the middle position and the convey path mechanism arranged at the lowermost portion can both be removed easily. From the viewpoint of the convey path mechanism at the middle position, the convey path mechanism is provided with a roller to convey the document to the convey path facing the convey path mechanism at the uppermost portion and a roller to convey the document to the convey path facing the convey path mechanism at the lowermost portion. In other words, the convey path mechanism at the middle position is attached with the convey rollers respectively at its position closer to the upper side and its position closer to the lower side. Depending on the state of the jamming, the document sometimes partly jams into the middle position between the upper and lower rollers. In this case, the jamming document is difficult to remove.  
      To solve this problem, the convey path mechanism at the middle position may be further halved to partition the convey path into four regions in the vertical direction, and the four convey path regions may be opened or closed independently. If, however, the convey path of a particularly compact sheet convey apparatus is partitioned into four convey path mechanisms in the vertical direction, the entire mechanism becomes further complicated. This hinders downsizing and leads to an increase in cost. When jamming occurs at the lowermost side of the convey path, the operator of the sheet convey apparatus must perform a process of sequentially opening the respective convey path mechanisms and a process of sequentially closing the respective convey path mechanisms after the jamming is removed, which is cumbersome.  
      In the above description, a sheet convey apparatus which reads a document is described. The same problems arise in other sheet convey apparatuses such as a sheet convey apparatus for a printing apparatus that prints images on two sides of a sheet.  
     SUMMARY OF THE INVENTION  
      It is an object of the present invention to provide a sheet convey apparatus in which jamming can be removed more easily.  
      In order to achieve the above object, according to the present invention, there is provided a sheet convey apparatus comprising a first convey path unit which has a lower boundary surface of a first sheet convey path and rotates in one direction about one end side thereof as a rotation center, a second convey path unit which is arranged under the first convey path unit and rotates in the same direction as the first convey path unit about one end side thereof as a rotation center, the second convey path unit having an upper boundary surface of a second sheet convey path connected to the first sheet convey path, and a link member which connects the first and second convey path units and follows rotation of the first convey path unit to rotate the second convey path unit while an angle formed by the first and second convey path units is increased. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view showing the appearance of a document convey apparatus according to an embodiment of the present invention;  
       FIG. 2  is a sectional view showing the internal structure of the document convey apparatus shown in  FIG. 1 ;  
       FIG. 3  is a sectional view showing a state wherein a space above the lower unit shown in  FIG. 2  is opened;  
       FIG. 4  is a sectional view showing a dismantled state of the middle unit shown in  FIG. 2 ;  
       FIG. 5  is a sectional view showing the layout in the use state of the middle unit and lower unit shown in  FIG. 2 ;  
       FIG. 6  is a sectional view showing a state wherein the middle unit shown in  FIG. 2  is opened;  
       FIG. 7  is a perspective view of the top unit of the middle unit shown in  FIG. 2 ; and  
       FIG. 8  is a perspective view of the bottom unit of the middle unit shown in  FIG. 2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
      A document convey apparatus according to an embodiment of the present invention will be described with reference to FIGS.  1  to  8 . Referring to  FIG. 1 , a document convey apparatus  101  forms the top portion of a document reading apparatus. An apparatus main body portion which is arranged under the document reading apparatus and includes a scanner module formed of an optical system or the like to read a document, an image processing circuit, or a power supply circuit is not shown.  
      The document convey apparatus  101  has a stacker  102  which extends horizontally so as to be placed on the document reading apparatus main body described above. A document that has been read is stacked on the stacker  102 . Two rod-like projections  104  project from the bottom surface of the stacker  102  in a document discharge direction indicated by an arrow  103 . A document tray  105  is arranged above the stacker  102  at a predetermined gap. A reading target document is set on the document tray  105  such that the leading edge of the document is inserted in a document insertion port  106 . Document guides  107  movable in the widthwise direction of the document are attached before the document insertion port  106  of the document tray  105 .  
      An openable upper unit  108  is arranged on the upper deep side on the document insertion port  106 . When a handle  109  located above the center of the document insertion port  106  is lifted upward, the upper unit  108  pivots about the fulcrum as the center, to open the internal space near the inlet of the document insertion port  106 . Then, paper jamming (jam) in the apparatus can be removed.  
      As shown in  FIG. 2 , the document convey apparatus  101  has three units, i.e., the upper unit  108  and units  115  and  119  that form a document convey space. The upper unit  108  shown in  FIG. 1  is arranged at the uppermost portion of the document convey apparatus  101 . In the upper unit  108 , a total of three rollers, i.e., a guide roll  112  which guides the leading edge of the document to be inserted, a main feed roller  113  which feeds the document inward, and a convey roller  114  are arranged sequentially from the document insertion port  106  on the upper surface side of the document which is to be fed in a direction of an arrow  111  along the document tray  105 .  
      The middle unit  115  is arranged immediately under the upper unit  108 . The middle unit  115  also has a mechanism that pivots about a fulcrum as the center, as will be described later. The middle unit  115  has a retard roller  116  in rolling contact with the main feed roller  113  of the upper unit  108 , and discharge rollers  117  which discharge the document to the stacker  102  and feed the document into the apparatus again when the two sides of the document are to be read. The discharge rollers  117  are driving rollers driven by a driving source (not shown).  
      The lower unit  119  is arranged further below the middle unit  115 . A glass platen  121  is arranged in an opening formed in the bottom of the lower unit  119 . An optical system and reading element (not shown) are arranged at the apparatus main body portion under the glass platen  121 , and read the image information of the document passing on the glass platen  121 . The lower unit  119  has a convey roller  122  in rolling contact with the convey roller  114  of the upper unit  108 , a discharge roller  123  in rolling contact with the discharge rollers  117 , and two convey roller pairs, i.e., a pair of convey rollers  124  and pair of convey rollers  125 . A flapper  126  which has a wedge-shaped section and switches the document convey direction is arranged at a position before the discharge rollers  117  in the lower unit  119 .  
      A document convey state in the document convey apparatus  101  having the above structure will be described briefly.  
      An operation of reading only one side of a document will be described. When the document is set on the document tray  105 , the guide roll  112  moves downward while rotating, to come into contact with the uppermost layer of the document. Thus, the set document is fed out toward the nip region of the main feed roller  113  and retard roller  116 . The document, the leading edge of which is introduced to the nip region, is fed into the apparatus one by one by the main feed roller  113  and retard roller  116 . The retard roller  116  rotates in a direction opposite to the rotating direction of the main feed roller  113 , to prevent overlapping feed during feeding.  
      The document passing between the main feed roller  113  and retard roller  116  passes between the pair of convey rollers  114  and  122 , then between the pair of convey rollers  124 , and is conveyed on the glass platen  121 . At this time, the image information on the first surface of the document is read by using a reading element (not shown). After the reading, the document passes between the pair of convey rollers  125 , pushes up the distal end of the valve-like flapper  126  from below, passes between the pair of discharge rollers  117  and the discharge roller  123 , and is discharged onto the stacker  102 . In this manner, the document set on the document tray  105  is fed into the document convey apparatus  101  one by one, and image information on one side (the upper surface of the document set on the document tray  105 ) of each document is read sequentially.  
      A case wherein the two sides of the document are to be read will be described. In this case, of the document fed from the document tray  105  into the document convey apparatus  101 , the image information on the first surface is read in the manner as described above. As the reading proceeds, the document is fed to the stacker  102  by the pair of discharge rollers  117  and the discharge roller  123  from the leading edge of the document. At this time, the first surface of the document sheet that has been read is located on the lower side.  
      When the trailing edge of the document sheet reaches the nip region of the pair of discharge rollers  117  and the discharge roller  123 , at this timing, the pair of discharge rollers  117  and the discharge roller  123  start to rotate in opposite directions. Thus, the trailing edge of the document sheet passes on the upper surface of the flapper  126 , moves forward substantially horizontally through the boundary portion of the middle unit  115  and lower unit  119 , and passes between the pair of convey rollers  114  and  122 . Consecutively, the document passes between the pair of convey rollers  124  again and is conveyed on the glass platen  121 . At this time, the reading element (not shown) reads the image information on the second surface of the document. The document that has been read passes between the pair of convey rollers  125 , pushes up the distal end of the valve-like flapper  126  from below, passes between the pair of discharge rollers  117  and the discharge roller  123 , and is discharged onto the stacker  102 . In this manner, the image information on the two sides of the document sheet are read.  
      In the document convey apparatus  101  of this embodiment, the upper unit  108  and middle unit  115  can be sequentially opened upward like double doors. In this state, a jamming document can be removed easily, and maintenance such as component exchange can be performed. This will be described mostly concerning the mechanism of the middle unit  115 .  
      Referring to  FIG. 3 , when the handle  109  is lifted upward, the upper unit  108  is rotated counterclockwise as indicated by an arrow  131  about a fulcrum located at the lower portion of the upper unit  108  as the center. Thus, the upper unit  108  is set still to be upright as a whole at the rear portion of the apparatus. After the upper unit  108  is set upright as described above, the middle unit  115  is rotated clockwise as indicated by an arrow  132  about two rotating shafts  133  as the center. The middle unit  115  is set still as it is upright to oppose the upper unit  108 . At this time, the upper unit  108  and middle unit  115  are open like double doors.  
      The middle unit  115  includes a top unit  142  and bottom unit  144 . In the top unit  142 , the retard roller  116  is arranged on a feed guide  141 , and the top unit  142  rotates about rotating shafts  134  as the center. The bottom unit  144  includes the discharge rollers  117  and a return guide  143 , and rotates about the rotating shafts  133  as the center. The top unit  142  and bottom unit  144  are connected to each other through a link (not shown). When the operator lifts the feed guide  141  upward, the top unit  142  and bottom unit  144  both move in the direction of the arrow  132 . The rotating shafts  133  serve as a transmission shaft which transmits a load obtained from a solenoid (not shown) as a torque.  
      When the upper unit  108  and middle unit  115  constitute double doors that open apart, a document jamming between the upper unit  108  and middle unit  115  or between the middle unit  115  and lower unit  119  can be removed easily. Regarding a document jamming in the lower region of the lower unit  119 , e.g., between the lower unit  119  and glass platen  121 , if it is partly present in the upper space, it can be held with a hand and removed.  
      As shown in  FIG. 4 , the middle unit  115  includes the top unit  142  and bottom unit  144 , and removable joint arms  151  which connect the two units  142  and  144 . The feed guide  141  which forms the top unit  142  has first arm supports  152  at substantially the central portion of its surface that opposes the bottom unit  144 . Each arm support  152  has an elongated hole  154  in which a first projection  153  projecting from one end portion of the corresponding joint arm  151  is to be inserted.  
      The return guide  143  which forms the bottom unit  144  of the middle unit  115  has second arm supports  155  on its surface that opposes the top unit  142 . Each second arm support  155  has a hole  157  in which a second projection  156  projecting from the other end portion of the corresponding joint arm  151  is to be inserted.  
      The joint arms  151  connect both the first and second arm supports  152  and  155  except for a specific case. The specific case refers to a case wherein the discharge rollers  117  attached to the top unit  142  of the middle unit  115  are worn out and are to be exchanged for new ones and a case wherein a paper piece produced when removing a jamming document jams into the middle unit  115  and is to be removed.  
      Of the middle unit  115 , the top unit  142  and bottom unit  144  are pivotal about the different rotating shafts  134  and  133 , respectively, as the fulcrums. Accordingly, as shown in  FIG. 5 , when the middle unit  115  is set on the lower unit  119 , the joint arms  151  are substantially parallel to the stacker  102 , and the top unit  142  and bottom unit  144  are close to each other as a whole.  
      In this still state, a free-end-side upper portion  161  of the top unit  142  is held and lifted upward, as shown in  FIG. 6 . First, only the top unit  142  alone starts to rotate in a direction of an arrow  162  (clockwise) about the rotating shafts  134  as the fulcrum. Simultaneously, one end on the first arm support  152  side of each joint arm  151  ( FIG. 5 ) starts to move upward. Eventually, the bottom unit  144  follows the movement of the joint arms  151  to start rotation in the direction of the arrow  162  about the rotating shafts  133  as the fulcrum.  
      Therefore, when the middle unit  115  is opened widest as shown in  FIG. 6 , the angle formed by the top unit  142  and bottom unit  144  is the maximum. In this state, the operator can remove the jamming document by using a space produced above the lower unit  119 . When at least one side of each joint arm  151  is removed, the angle formed by the top unit  142  and bottom unit  144  can be further increased. In this state, for example, the operation of removing the paper piece jamming between the units  142  and  144  can be performed easily, as has been described above.  
      As shown in  FIG. 7 , a pair of retard roller guides  171  and  172  each having a U-shape are attached to substantially the center of the lower surface of the feed guide  141  which forms the top unit  115 , such that the retard roller guides  171  and  172  project at a predetermined gap from each other. Rotating shafts  173  and  174  of the retard roller  116  are urged against the inner surfaces of the retard roller guides  171  and  172  separately by the pressing forces of springs (not shown) through bearings (not shown).  
      One end of a driving shaft  175  is attached to one rotating shaft  173 . The driving shaft  175  transmits a driving force to the rotating shaft  173 . The driving shaft  175  is pivotally supported by a bearing portion  177  projecting from the lower surface of one end portion of the feed guide  141 . The rotation force of a driving force (not shown) is transmitted to the driving shaft  175  from a rotation force transmission mechanism  178  such as a gear arranged in the vicinity of the driving shaft  175 . The rotating shafts  173  and  174  are supported independently of each other by the two springs, as described above. Thus, the position and inclination of the center axis of the retard roller  116  change in accordance with a change in thickness or the like of the document inserted between the retard roller  116  and main feed roller  113  ( FIG. 2 ). However, of the driving shaft  175 , the distance from the bearing portion  177  to the rotating shaft  173  is much longer than the distance from the bearing portion  177  to the rotation force transmission mechanism  178 . Therefore, even when the position and inclination of the retard roller  116  change, the change will not substantially adversely affect the rotation force transmission mechanism  178 , and the driving force can be transmitted smoothly.  
      The pair of discharge rollers  117 , to which a driving force from one driving shaft  181  is transmitted, are attached to that side of the top unit  115  where the rotating shafts  134  are attached. The driving shaft  181  receives a driving force transmitted from another driving shaft  184  through rotation force transmission mechanisms  182  and  183  such as gears. A transmission shaft  185  is arranged, at almost the middle position of the driving shaft  184  and retard roller  116 , to be parallel to the driving shaft  184 . The transmission shaft  185  transmits a torque load that separates the discharge rollers  117  and  123  ( FIG. 2 ) from each other.  
      As shown in  FIG. 8 , the plate-like return guide  143  which forms the bottom unit  144  has the second arm supports  155  on its two end portions. Under the two end portions, bearing portions  193  and  194  axially support transmission shafts  191  and  192  coaxial with and connected to the rotating shafts  133 , respectively.  
      One transmission shaft  191  transmits a torque load through the transmission shaft  185  ( FIG. 7 ) to the pair of discharge rollers  117  and the discharge roller  123  applied with pressing forces by springs (not shown), to separate the rollers  117  and the roller  123  from each other. The other transmission shaft  192  transmits a driving force to the driving shaft  184  ( FIG. 7 ), to rotatably drive the pair of discharge rollers  117 .  
      In the document convey apparatus  101  of this embodiment having the above structure, while the upper unit  108 , middle unit  115 , and lower unit  119  are sequentially laid on each other, as shown in  FIG. 2 , the document is inserted between the main feed roller  113  and retard roller  116 . At this time, the main feed roller  113  rotates in the document convey direction, and the retard roller  116  rotates in a direction opposite to the document convey direction with a predetermined torque. The document is inserted between the upper unit  108  and middle unit  115 , and is read while it passes through the lower unit  119 . After that, the document is discharged onto the stacker  102 .  
      Assume that the two sides of the document are to be read. As soon as the trailing edge of the document passes the flapper  126 , a sensor (not shown) detects this trailing edge. At this time point, the discharge rollers  117  start to rotate backward. Thus, the document passes above the flapper  126  through the gap between the flapper  126  and the return guide  143  ( FIG. 3 ) of the middle unit  115 , and is guided to the upper portion of the glass platen  121  again. Then, the other side of the document is read. When the document passes on the flapper  126 , as the top unit  142  is arranged as the guide plate above the flapper  126 , jamming does not occur frequently at this portion. When the image information on the two sides of the document is read, the document is discharged onto the stacker  102 .  
      When the lengths of the joint arms  151  are changed, the open angle of the top unit  142  and bottom unit  144  of the middle unit can be adjusted. The longer the joint arm  151 , the larger the open angle, and the document jamming between the top unit  142  and bottom unit  144  can be removed more easily. Note that design must be performed such that when the joint arms  151  rotate, components do not interfere between the units  142  and  144 .  
      In the above embodiment, a document convey apparatus which conveys a document is described. The present invention can be similarly applied to a sheet convey apparatus which conveys a sheet other than a document by a similar mechanism.  
      In the above embodiment, the joint arms  151  are attached between the top unit  142  and bottom unit  144 , and the top unit  142  and bottom unit  144  rotate about different rotating shafts as the centers, respectively. Thus, the gap between the top unit  142  and bottom unit  144  which is formed by the joint arms  151  is changed. Alternatively, if the top unit  142  and bottom unit  144  share one rotating shaft and a stretchable elastic member is arranged between the top unit  142  and bottom unit  144 , when the top unit  142  is rotated in an opening direction in the same manner, the gap between the top unit  142  and bottom unit  144  can be enlarged.  
      Furthermore, in the above embodiment, the present invention is applied to a sheet convey apparatus including three units, i.e., the upper unit  108 , middle unit  115 , and lower unit  119 . The present invention can similarly be applied to a sheet convey apparatus including one or two units, or four or more units.  
      As has been described above, according to the present invention, a unit which should originally be formed as one convey path unit includes the first and second convey path units. When the first and second convey path units are rotated in predetermined directions and opened, the angle formed by the first and second convey path units increases. Hence, even if a sheet jams into the apparatus, it can be removed easily. In addition, as the first and second convey path units rotate together, the operation of opening/closing the first and second convey path units is not cumbersome.  
      The link member can be removed from at least one of the first and second convey path units. When the link member is removed, the angle formed by the first and second convey path units can be further increased. Then, for example, the operation of exchanging convey rollers attached to these units can be performed easily.  
      As the second convey path unit has a guide surface, the occurrence rate of jamming can be decreased. Moreover, when compared to a sheet convey mechanism that has no guide surface at this portion, the structure of the entire unit including the first and second convey path units can be simplified.