Abstract:
A sheet transfer apparatus for an image reading apparatus includes a sheet supply tray for storing a sheet; a sheet supply device for drawing out the sheet on the sheet supply tray; a transfer device for receiving the sheet from the sheet supply means and placing the sheet at a predetermined position on a platen of an image reading apparatus for reading the image thereon; a discharge device for discharging the sheet on the platen after reading the image thereon; and a discharge tray for receiving the sheet discharged by the discharge device. A switchback device is disposed above the platen for reversing the sheet when necessary, and includes a switchback path for receiving the sheet to reverse the same. The switchback path includes a first opening portion for opening a first area near an inlet side, and a second opening portion for opening a second area away from the inlet side of the switchback path. The switchback path is easily accessible when the sheet is jammed.

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
     This invention relates to a sheet transfer apparatus for an image reading apparatus, which is used with an image forming apparatus such as a copier, facsimile, printer and scanner. The sheet transfer apparatus continuously draws or receives a series of sheets on a sheet supply tray, and aligns and stacks the sheets after images thereupon have been read. 
     Conventionally, a set of the sheets placed on the sheet supply tray is read sequentially, and is discharged to a discharge tray. When the sheets stacked on the discharge tray, or the sheets after being read on both sides, are required to be reorganized into their original order, a switchback path disposed in the sheet transfer apparatus reverses the sheet from front to back thereof. 
     Examples of the sheet transfer apparatus having such a switchback path are disclosed in Japanese Patent Publication (KOKAI) No. 09-292742 and Japanese Patent Publication (KOKAI) No. 05-30724. 
     An automatic document feeder apparatus disclosed in Japanese Patent Publication No. 09-292742 sequentially draws the sheets stacked on the sheet supply tray, transfers the sheets to a platen glass by a transfer belt, and sets the sheets on the platen glass to read images on the sheets. The apparatus is structured to reverse and transfer the sheets via the switchback path to organize the page order of the sheets. The switchback path is formed between the transfer belt and the discharge tray. 
     The sheet transfer apparatus disclosed in Japanese Patent Publication No. 05-30724 is structured to arrange the switchback path below the sheet supply tray. Vertical positions of the sheet supply tray and discharge tray are reversed from those in Japanese Patent Publication No. 09-292742. 
     However, in the switchback path for reversing the sheet from a front side to a back side, paper jam occurs easily, because the sheet is forced to bend and is subjected to back and forth movement in a narrow path. However, in the sheet transfer apparatus relating to the aforementioned prior art, there has been no consideration regarding measures of recovering from the paper jam that occurs in the switchback path between the transfer belt and the discharge tray. 
     Measures to remove such paper jam include opening the switchback transfer path with one edge of a guide portion of the switchback transfer path as a pivot. However, enough opening angle is not available because a sheet supply tray or the like is disposed at an upper portion. 
     This type of sheet transfer apparatus is capable of handling sheet sizes up to A3 or B4. However, since the most commonly used sheet size is A4, it is possible to deal with the paper jam by opening a sheet transfer inlet of the switchback path, if the switchback path is designed to be capable of being opened. 
     For this reason, it is proposed that only a sheet transfer inlet of the switchback path corresponding to the A4 size is designed to be capable of being opened. However, since the larger size sheet such as A3 or B4 size uses far deeper areas of the switchback path, the entire switchback path is required to be opened to handle the paper jam. 
     An object of the present invention is to provide the sheet transfer apparatus that makes it extremely easy to handle the sheet jam at the sheet transfer inlet of the switchback path where the sheet jam occurs relatively easily, and even if the sheet jam occurs at a deeper area, an operator can handle the sheet jam easily. 
     Further objects and advantages of the invention will be apparent from the following description of the invention. 
     SUMMARY OF THE INVENTION 
     The first aspect of the present invention provides a sheet transfer apparatus including sheet supply means for drawing out a sheet on a sheet supply tray; transfer means for receiving the sheet from the sheet supply means and for placing it at a predetermined location on a platen of an image reading apparatus; discharge means for receiving the sheet after images thereon being read on the platen and for discharging it to a discharge tray arranged below the sheet supply tray; and a switchback path disposed inside the discharge tray for reversing the sheet as needed after reading images thereon. The switchback path is structured to have the first opening portion for opening a sheet inlet of the switchback path, which is a part of the discharge tray, and the second opening portion adjacent to the first opening portion. 
     Here, the first and second opening portions are connected to an apparatus frame such that they can rotate around shafts. One end of the second opening portion is connected to an apparatus frame such that the second opening portion can rotate around the shaft. The other end of the second opening portion hinged to the first opening portion. Furthermore, an opening angle of the first opening portion is configured to be larger than that of the second opening portion. 
     This configuration makes it easier to handle paper jam that occurs at the sheet inlet of the switchback path, and also makes it easier to handle the paper jam farther from the sheet inlet when necessary. 
     Further, in the sheet transfer apparatus, the first opening portion and the second opening portion are provided with opening locking means for controlling the opening operation so that the opening portions will not open inadvertently in a normal state. 
     The second aspect of the present invention provides a sheet transfer apparatus including sheet supply means for drawing out sheets on the sheet supply tray; transfer means for receiving the sheet from the sheet supply means and for placing it at a predetermined location on the platen of the image reading apparatus; discharge means for receiving the sheet after images thereon being read on the platen and for discharging it to the discharge tray arranged below the sheet supply tray; and the switchback path disposed inside the sheet supply tray for reversing the sheet as needed after reading images thereupon. The switchback path is structured to have a first opening portion for opening a sheet inlet of the switchback path, which is a part of the sheet supply tray, and a second opening portion adjacent to the first opening portion. 
     Here, in the first opening portion, an end portion of the switchback path is supported on a shaft such that the first opening portion can rotate around the shaft. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top perspective view of a sheet transfer apparatus according to the present invention; 
     FIG. 2 is a view showing a cross section of a sheet transfer apparatus according to the present invention; 
     FIG. 3 is a view showing a state where only the first opening portion opens; 
     FIG. 4 is a view showing a state where the second opening portion opens accompanied by the first opening portion to which the second opening portion is connected by a hinge; 
     FIG. 5 is a view showing a modification of the present invention; 
     FIG. 6 is a plan view showing a cross section of another embodiment of the present invention; 
     FIGS.  7 ( a )- 7 ( j ) are views showing operations of reading images on one side of a sheet in the sheet transfer apparatus according to the present invention; and 
     FIGS.  8 ( a )- 8 ( h ) are views showing operations of reading images on both sides of a sheet in the sheet transfer apparatus according to the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Hereunder, preferred embodiments of the present invention will be explained with reference to the accompanied drawings. A sheet transfer apparatus  1  according to the present invention is mounted to a reading apparatus body via a hinge, and the like (not shown), to be capable of opening and closing a platen disposed on the upper portion of an image forming apparatus  8 . 
     FIG. 1 is a top perspective view of the sheet transfer apparatus  1  according to the present invention. FIG. 2 is a sectional view of the sheet transfer apparatus seen from the front. In the sheet transfer apparatus according to this invention, sheet supply means, transfer means and discharge means are configured as units. 
     On the sheet transfer apparatus  1 , as shown in FIG.  1  and FIG. 2, there are formed a support frame  2 ; a sheet supply tray  10 ; a sheet supply unit  3  disposed on one end of the support frame  2  for drawing sheets stacked on the sheet supply tray  10 ; a transfer unit  5  for receiving the sheets drawn from the sheet supply unit  3  and for transferring them to a predetermined position on a platen of an image reading apparatus (not shown in the drawings) located below the sheet supply unit  3 ; discharge means  4  disposed on the other end of the support frame  2  for discharging the sheets after reading images; and a discharge tray  11  for stacking the discharged sheets. A switchback path  25  for reversing the sheet after reading images is situated under the discharge tray. Also, a front cover  6  and a rear cover  7  are disposed to protect a main body of the apparatus. The sheet supply unit  3 , the transfer unit  5 , and the discharge unit  4  are mounted to predetermined mounting locations on the support frame  2 . 
     The sheet supply unit  3 , the discharge unit  4  and the transfer unit  5  are provided with a sheet supply motor, a discharge motor, and a transfer motor (not shown), which are capable of rotating in forward and reverse directions, to drive rollers of each unit, respectively. 
     The sheet is stacked with a surface with images upward on the sheet supply tray  10 , as shown in FIG.  2 . The sheet supply unit  3  draws the stacked sheet. After the sheet is reversed approximately 180 degrees, the sheet stops at a predetermined reading position under a transfer belt  18  of the transfer means  5  with facing downward. After the sheet is read, the sheet is discharged on the discharge tray  11  by the discharge unit  4 . 
     However, when the sheets stacked on the sheet supply tray  10  are a set of a plurality of sheets, a page order of the set is reversed if using the above sheet discharging method because the sheets are drawn out and read continuously from the upper most sheet. To prevent this, the discharge unit does not discharge the sheets after reading to the discharge tray as they are, but first the discharge unit transfers the sheet into the switchback path  25  situated on a backside (an inner-side) of the discharge tray  11 , then discharges the sheet on the discharge tray  11  from the trailing edge thereby maintaining the original page order of the set. 
     Note that, operations of supply, transfer, switchback and discharge of the sheets in the sheet transfer apparatus according to the present invention are described below, including an operation for reading both sides of the sheets. 
     When the sheets are transferred into the switchback path  25 , sheet jam (paper jam) can easily occur since the sheets are bent by the discharge means before the transfer inlet and there are forward and subsequent backward movements of the sheets inside the switchback path. For that reason, the switchback path must be structured to be capable of opening so that any operators can easily remove the jammed paper. 
     FIG. 2 illustrates the first embodiment of the sheet transfer apparatus according to the present invention. According to the first embodiment, the sheet supply tray  10  is mounted on an upper portion of the apparatus, and the sheet supply unit  3  disposed at a left side supplies the sheets to the transfer unit  5  sequentially from the uppermost sheet stacked on the sheet supply tray  10 . The discharge tray  11  is disposed below the sheet supply tray  10 . As described above, after reading the images, the sheet must be reversed as needed. For this purpose, the switchback path  25  is established inside the discharge tray. 
     The discharge tray  11  is divided into two main portions. The first main portion is a first opening portion  11 A that opens a sheet inlet of the switchback path. The second main portion is a second opening portion  11 B adjacent to the first opening portion  11 A. The discharge tray  11  is structured to be opened by using the first opening portion  11 A and the second opening portion  11 B. This structure enables the switchback path  25  to be opened to remove the jammed sheet. 
     FIG. 3 shows a state in which only the first opening portion  11 A opens. The first opening portion is hinged to the second opening portion in a way that the first opening portion can rotate around a shaft  12 . The second opening portion is hinged to the apparatus frame such that the second opening portion can rotate around a shaft  13 . 
     As shown in FIG. 3, a rotating angle of the first opening portion  11 A is approximately 45 degrees according to this embodiment. This angle provides enough space to remove any jammed sheet. If it is opened any further, it will reach an angle where it will hit the upper sheet supply tray  10 . An opening angle of the second opening portion  11 B is approximately 25 degree. Normally, the approximately 25 degree opening angle is enough because the paper jams mainly occurs in the first opening portion  11 A and the first opening portion  11 A can open wider. This configuration makes it easier to handle the paper jam at the sheet inlet of the switchback path, and it is also possible to handle the paper jam at farther from the sheet inlet. 
     A sheet magnet is attached to a top of a free opening portion of the first opening portion  11 A. Also, a steel piece  27  is disposed on a portion corresponding thereto at the apparatus frame. The magnet portion  26  and the steel piece  27  magnetically attract each other. They form opening lock means  14  of the first opening portion  11 A and the second opening portion  11 B. This opening lock means  14  prevents the problems such that the first opening portion  11 A and the second opening portion  11 B open inadvertently when the sheet transfer apparatus  1  closes or opens the platen. Therefore, only when an operator tries to open, the first opening portion  11 A and the second opening portion  11 B open. While the magnet system is employed to control the opening operation of the switchback path, any other means instead of the magnet, such a latch or a VELCRO tape, or a detachable tape, having substantially the same effect is equally acceptable. 
     One end of the second opening portion  11 B is attached to the apparatus frame such that the second opening portion  11 B can rotate around the shaft  13 , and the other end of the second opening portion  11 B is connected to the first opening portion  11 A with a hinge  15 . With this structure, the operator can open the second opening portion  11 B simultaneously by lifting the first opening portion  11 A upward, thus making it easier to remove larger size sheets extending to a bottom of the second opening portion  11 B. Note that the support shaft  12  and the hinge  15  are mounted on ends of the opening portions  11 A and  11 B (edges thereof in a direction perpendicular to the direction of sheet transfer). Thus, the support shaft  12  and the hinge  15  are not located in a position where they interfere with the sheet entering the switchback path  25 . 
     In FIG. 4, the entire switchback path  25  is opened by lifting the first opening portion  11 A, which accompanies the lifting of the second opening portion  11 B. In this state, an operator can easily remove the jammed sheets even if they are deep in the switchback path. Furthermore, because the second opening portion  11 B is pulled simultaneously by lifting the first opening portion  11 A due to the hinge, the operator is able to easily lift these opening portions with one hand, and remove the jammed sheet with the other hand. 
     FIG. 5 is a view showing a modification of the first embodiment of the present invention. In this modification of the first embodiment, the first opening portion  11 A can rotate around the support shaft  12  on the apparatus frame, and the second opening portion  11 B can also rotate around the support shaft  13  on the apparatus frame. These two opening portions are not mutually interlocked, but such a structure allows easy retrieval and removal of jammed sheets. 
     FIG. 6 is showing an example of the second embodiment of the present invention. In this example, the discharge tray  11  for stacking the sheets from the discharge unit  4  is arranged above the sheet supply tray  10  from which the sheets are transferred to the sheet supply unit  3  on the left side. The switchback path  25  is formed at a backside (or an inner side) of the sheet supply tray  10 . 
     For this reason, the switchback path  25  according to this example can be opened by rotating the sheet supply tray  10 . The sheet supply tray  10  is composed of the first opening portion  10 A that opens the sheet inlet of the switchback path  25 , and the second opening portion  10 B adjacent to the first opening portion  10 A. 
     The first opening portion  10 A is situated at a sheet inlet side of the switchback path such that the first opening portion  10 A can rotate around a support shaft  16 . The second opening portion is supported on a support shaft  17  at an opposite end side to the sheet inlet of the switchback path such that the second opening portion can rotate around the support shaft. This configuration allows the switchback path  25  formed inside the sheet supply tray  10  to be opened, and makes it easy to retrieve and remove the jammed sheet. 
     The following describes general operations of the sheet transfer apparatus described above. First, a single side reading mode of the image reading apparatus will be explained with reference to FIGS.  7 ( a )- 7 ( j ). 
     Sheets  100  are placed on a sheet supply tray  10  (FIG.  7 ( a )). When an empty sensor S 5  detects the sheets  100 , a sheet supply motor rotates forward to drive a draw-out roller  43  and a sheet supply roller  45 . The sheets  100  are drawn out by the draw-out roller  43  and separated into a single sheet by the sheet supply roller  45  and a separating member  44  so that the single sheet can be supplied. After a register sensor S 1  detects a leading edge of the single sheet  100 , the sheet supply motor drives by a predetermined amount thereby driving the leading edge of the sheet  100  to a nip of a register roller  47  to correct skew of the sheet, then the sheet supply motor stops (FIG. 7 ( b )). Then, a sheet supply motor is driven in reverse and the register roller  47  is driven to supply the sheet toward a platen  31 . At the same time, a transfer motor is rotated forward to rotate the transfer belt  18  for transferring the sheet  100  fed from the register roller  47  along a platen  31  (FIG.  7 ( c )). After a timing sensor S 2  detects a trailing edge of the single sheet  100 , the sheet is transferred by a predetermined distance, and then the transfer motor stops to stop the register roller  47  and the transfer belt  18 . The sheet  100  is placed at a predetermined position on an upper surface of the platen  31  where the reading means reads the sheet  100  (FIG. 7 ( d )). 
     At this point, while the first sheet  100  is being read, if the empty sensor S 5  detects a second sheet  101 , or if the second sheet  101  is set on the sheet supply tray  10 , the sheet supply motor rotates forward to drive the draw-out roller  43  and the sheet supply roller  45  to draw out the second sheet  101  in the same way as the first sheet  100 . Then, the second sheet is separated into a single sheet, and after a leading edge of the second sheet abuts against the nip of the register roller  47 , the second sheet stops and stays there (FIG. 7 ( e )). 
     Upon completion of the reading of the first sheet, the transfer motor again rotates forward, and at the same time, a discharge motor also rotates forward. The transfer belt  18  and the inversion roller  55  are driven forward for transferring the first sheet  100  out from the top of the platen  31  (FIG.  7 ( f )). 
     Here, when a reverse/discharge sensor S 4  detects the leading edge of the first sheet  100 , the sheet supply motor rotates in reverse to drive the resist roller  47 . The second sheet  101 , which stays at the nipping point of the register roller  47 , is transferred toward the platen  31 . In the same way as the case of the first sheet  100 , the sheet is transferred to the predetermined position on the platen  31  and stops thereat. 
     The first sheet  100  discharged from the top of the platen  31  is guided to the switchback path  25  (FIG.  7 ( g )) by a discharge flapper  54  and an reverse flapper  57 . The sheet  100  is transferred by a predetermined distance after the reverse/discharge sensor S 4  detects a trailing edge thereof. Then, the discharge motor stops to stop a reverse roller  55  temporarily. At this time, at a position passing a free-falling flapper  60 , the trailing edge of the sheet  100  is nipped by the reverse roller  55  and a pinch roller  56   b  and stopped (FIG. 7 ( h )). Then, the discharge roller M 2  rotates in reverse to switch back the sheet  100  nipped and stopped by the reverse roller  55  and the pinch roller  56   b.  The sheet is discharged to the discharge tray  11  by a pair of discharge rollers  53   a  and  53   b  (FIG.  7 ( i )). 
     The same procedure for discharging the first sheet  100  is performed to discharge the second sheet  101 . Similarly, the same process for feeding and discharging is repeated for the other sheets that remain on the sheet supply tray  10  (FIG.  7 ( j )). 
     (Note that there is a free-falling flapper  60  hanging downward by own weight and being configured to rotate upward when pushed by the leading edge of the sheet as it passes therethrough. Also, the discharge roller  53   b  has a drive mechanism to rotate only in one direction, regardless of forward or reverse rotation of the discharge motor. 
     An operation of reading both sides of a sheet in this sheet transfer apparatus will be explained with reference to FIGS.  8 ( a )- 8 ( h ). The sheet supply and transfer are the same operation as that of the single side reading mode from supplying the first sheet  100  to reading the top surface thereof. (FIGS.  7 ( a )- 7 ( e )) 
     In a state shown in FIG.  8 ( a ), after reading its front side, the first sheet  100  is discharged from the top of the platen  31  (FIG.  8 ( b )) by the transfer belt  18  and the reverse roller  55  through the forward drive of the transfer motor and the discharge motor. 
     After the reverse sensor S 4  detects the leading edge of the sheet  100  discharged from the platen  31 , the sheet  100  is transferred by a predetermined distance to pass through the discharge flapper  54  and the free-falling flapper  60 . The sheet stops at a position where the leading edge of the sheet is nipped by the reverse roller  55  and the pinch roller  56   b , and the transfer motor and the discharge motor stop (FIG.  8 ( c )). The transfer motor rotates in reverse at the same time when the reverse flapper  57  switches in a direction to guide the sheet  100  to the platen  31  again, and the discharge motor again rotates in forward. Through these steps, the sheet  100  is reversed and fed to the platen  31  again, and is transferred to a predetermined position on the platen  31  (FIG.  8 ( d )). 
     The backside of the sheet  100  transferred to a predetermined position on the platen  31  is read by the reading means. When the reading is completed, the transfer motor drives forward and the discharge motor rotates forward at the same time. This makes the transfer belt  18  move forward and the reverse roller  55  rotate forward for transferring the first sheet  100  out from the top of the platen  31  (FIG.  8 ( e )). 
     Here, when the reverse sensor S 4  detects the leading edge of the first sheet  100 , the sheet supply motor rotates in reverse to drive the register roller  47 . The second sheet  101 , which is nipped and stays at the nipping point of the register roller  47 , is controlled to be sent toward the platen  31 . In the same way as for the first sheet  100 , the sheet is transferred to a predetermined position on the platen  31  and stopped there. 
     When the reverse sensor S 4  detects the leading edge of the first sheet  100  discharged from the top of the platen  31 , the discharge flapper  54  switches to a position to guide the sheet  100  directly into a pair of the discharge rollers  53 . This allows a pair of the discharge rollers  53   a  and  53   b  to discharge the first sheet  100  to the discharge tray  11  (FIGS.  8 ( f )- 8 ( g )). 
     After that, the same procedure for discharging the first sheet  100  is performed to discharge the second sheet  101 . Similarly, the same processes of feeding and discharging are repeated for other sheets that remain on the sheet supply tray (FIG.  8 ( h )). 
     As described above, in the present invention, the switchback path can be easily opened by lifting the first and the second opening portions, each of which is structured to enable rotational movement around the shaft on the apparatus frame. It is possible to retrieve and remove the sheet jammed at the inlet of the switchback path or deeper inside, resulting in superior operability and improved maintainability of the sheet transfer apparatus. 
     While the invention has been explained with reference to the specific embodiment of the invention, the explanation is illustrative and the invention is limited only by the appended claims.