Abstract:
An automatic document feed device having reading means for stopping a conveyed document to a reading position on a platen and sequentially reading images of two sides of the document one side by one, includes an adjusting unit, provided upstream of the reading position on the platen, for adjusting an edge of the document, wherein the adjusting unit have a function for adjusting the edge of the document which is fed to read one side, and for reversing the document through the platen and adjusting the edge of the document which is fed again to read the other side of the document. A feed unit includes one of feed guide members and a feed roller in the feed path. The feed path unit is rotatably supported, thereby enabling the feed path to open.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an automatic document feed device in an image reading apparatus and, more particularly, to an automatic document feed device having a conveyer path in which documents are discharged one by one, automatically fed to an image reading position, thereafter, reversed, and fed again to the image reading position so as to read out images of two sides of the document. 
   2. Description of the Related Prior Art 
   In automatic document feed devices used for image forming apparatuses such as a copying machine, facsimile, and image scanner, at least one document set in a feed tray is automatically fed to an image reading unit and is discharged into the feed tray after completing the image reading operation. In general, adjusting means for correcting a skew of the document is provided in a conveyer path ranging from the feed tray to the image reading unit. More specifically, a pair of rollers is provided in the conveyer path ranging from the feed tray to the image reading unit, and the adjusting means corrects the skew of the document in a conveying direction thereof by nipping a predetermined amount of the edge of the document during the stop state of the pair of rollers. 
     FIG. 25  shows a conventional automatic document feed device which has been proposed, capable of reading images of double sides of document. In the proposed automatic document feed device, a large-sized conveyer roller  101  carries documents discharged from a feed tray  100  to an document reading unit  102  which is opposed to reading means  111  in an image reading apparatus main body  110 . Then, the reading means  111  in the document reading unit  102  reads out a front side of the document. The document is reversed through a switch-back path  103  which is arranged onto the downstream, and the reversed document is carried on a peripheral surface of the conveyer roller  101  again, thereby reading the rear surface of the document. Further, the document of which front and rear sides are read is reversed through the switch-back path  103  and the document reading unit  102 , and is discharged on a discharge tray  104  so as to sequentially arrange pages in order upon discharging the documents. 
   In the automatic document feed apparatus  110 , the document reeled from the feed tray  100  is nipped between a pair of rollers  106  by using a feed roller  105  arranged upstream so as to correct the skew of the document. Then, the edge of the document is abutted to a roller  107  pressed against the conveyer roller  101  by using the switch-back roller  108  while carrying the document whose front side is read from the switch-back path  103  to the document reading unit  102 , thereby correcting the skew of the document. 
   An example of the above-mentioned automatic document feed devices is disclosed in Japanese Unexamined Patent Application Publication No. 8-133551. In this disclosure, an document on the feed tray  100  is fed onto a platen and is shifted on the platen. Reading means stopped downstream of the platen reads out an image of the front side of the document. The document after the reading operation on the platen is switched back on a discharge tray and is reversed and supplied again on the platen. The back-side image of the document is read. The discharge tray is arranged downstream of the feed tray and the document is switched back between the feed tray and the discharge tray, thus reducing in size of the automatic document feed device. 
   However, in the above conventional automatic document feed device, a position of the document fed from the feed tray  100  is provided independently of that to correct the document which is fed to the document reading unit  102  again via the switch-back path  103  after reading the front side of the document by the document reading unit  102 . Therefore, a feed path is prolonged and the device has a large size. As a result, the structure becomes complicated. 
   Also, in the above-mentioned conventional document feed devices, a jammed document in a feed path is removed by opening/closing a part of the feed path, excluding a drive roller, etc., ranging from the feed tray to the platen. The automatic document feed device is opened/closed to the platen and, thereby, the jammed document is removed from a conveyer and discharge path. 
   However, the device disclosed in the Japanese Patent Application Publication No. 8-133551 has a problem in that the jammed document cannot be easily removed depending on a position of the jammed document because a conveyer path of the document is complicated. In particular, in case of jammed document having a short length in the conveying direction, frequently, only a part of the document is exposed and is sandwiched between a pair of rollers, as components forming the conveyer path, for moving the document. Even if the exposed part can be caught, the document is frequently broken to be forcedly pull out because the document is nipped between the rollers. 
   Further, it has been extremely difficult to remove the document jammed in a re-feed path which includes a switchback path to change the direction of the document move in order to feed the other surface of the document onto the platen again by turning over the document, because the document is not exposed at all in the re-feed path (referred often as “a switch-back path” thereafter). 
   As described above, to remove the jammed document in the cycle path for feeding the document again by switching the document to back, a part of the path is opened/closed. However, since feed means such as the feed rollers cannot be arranged to the feed path in the upper direction of the opened/closed cycle, the feed means must be disposed while preventing the upstream of the opened/closed cycle path so as to have the above structure. Consequently, there is a problem in that the device becomes large-sized. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide an automatic document feed device with a simple structure and a compact size that resets a status of a document nipped between a pair of resist rollers for carrying and sending the document, and facilitates an operation for pulling out a jammed document without damaging it, if the document is jammed at any position in a document transmitting path. 
   Accordingly, according to a first aspect of the present invention, there is provided an automatic document feed device having reaming means for stopping a document to be conveyed at a reading position on a platen and sequentially reading images of two sides of the document one side by one, comprising: adjusting means, provided upstream of the reading position on the platen, for adjusting an edge of the document, wherein the adjusting means has functions for adjusting the edge of the document which is fed to read one side of the document, and reversing the document through the platen and adjusting the edge of the document which is fed again to read the other side of the document. 
   Herein, the adjusting means comprises a first resist roller and a second resist roller, whereby rotation for conveyance of the document and stop for the adjustment are controlled. The document is abutted at a nip portion between the pair of resist rollers, thereby adjusting the document. 
   According to a second aspect of the present invention, there is also provided an automatic document feed device for reading one side of an a document to be conveyed, reversing and re-feeding the document onto a platen, and reading the other side of the document at a reading position on the platen, comprising: a feed tray for setting the document; a feed path for feeding the document on the feed tray to the platen; first and second resist rollers, provided on the document feed path, for adjusting the edge of the document the first and second resist rollers guided in the feed path; a conveyer path, connected to the document feed path, for conveying the fed document at the reading position of the platen; and a switch-back path for reversing the conveying direction of the document passing through the platen and guiding the document to the first and second resist rollers, wherein the first and second resist rollers adjust the edge of the document guided in the switch-back path and re-feeds the document to the platen. Herein, the feed path is overlappingly provided above the switch-back path. 
   According to a third aspect of the present invention, there is further provided an automatic document feed device for reading one side of a document to be conveyed, reversing and re-feeding the document onto a platen, and reading the other side of the document at a reading position on the platen, comprising: a feed tray for setting a document; a feed path for guiding the document on the feed tray to a platen; feed means for feeding the document along the document feed path; a conveyer path, connected to the document feed path, for guiding the fed document at the reading position on the platen; conveying means for conveying the document on the platen along the feed path; a switch-back path for reversing the conveying direction of the document passing through the platen and guiding the document to the feed path; a switch-back roller, provided to the switch-back path; and adjusting means, provided near the downstream of a junction point of the switch-back path, for adjusting the edge of the document guided by the feed means and adjusting the edge of the document guided in the switch-back path. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a vertical cross-sectional view of an automatic document feed device in an image reading apparatus according to the present invention; 
       FIG. 2  is an enlarged vertical cross-sectional view of the automatic document feed device shown in  FIG. 1 ; 
       FIG. 3  is a diagram showing a status upon opening an document conveyer path in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 4  is a diagram showing a status upon opening the document conveyer path in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 5  is a diagram showing parts for driving the automatic document feed device shown in  FIG. 1 ; 
       FIG. 6  is a diagram showing parts for driving the automatic document feed device shown in  FIG. 1 ; 
       FIG. 7  is a cross-sectional view for illustrating main portions of the automatic document feed device shown in  FIG. 1 ; 
       FIG. 8  is a diagram showing a connecting part when a document route is opened/closed in the automatic document feed device show in  FIG. 1 ; 
       FIG. 9  is a flowchart ( 1 ) for control operation of conveyance in a one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 10  is a flowchart ( 2 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 11  is a flowchart ( 3 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 12  is a flowchart ( 4 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 13  is a flowchart ( 5 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 14  is a flowchart ( 6 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 15  is a flowchart ( 7 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 16  is a flowchart ( 8 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 17  is a flowchart ( 9 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 18  is a flowchart ( 10 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 19  is a flowchart ( 11 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 20  is a flowchart ( 12 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 21  is a flowchart ( 13 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIG. 22  is a flowchart ( 14 ) for control operation of conveyance in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIGS. 23A to 23E  are schematic diagrams showing a conveying status of the document in the one-side mode in the automatic document feed device shown in  FIG. 1 ; 
       FIGS. 24A to 24F  are schematic diagrams showing a conveying status of the document in a double-side mode in the automatic document feed device shown in  FIG. 1 ; and 
       FIG. 25  is a cross-sectional view showing a conventional art of automatic document feed devices. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereinbelow, an automatic document feed device according to the present invention will be described in detail with reference to the drawings. 
     FIG. 1  is a vertical cross-sectional view showing an automatic document feed device provided in an image reading apparatus according to the present invention.  FIG. 2  is an enlarged vertical-sectional view showing a main portion in the automatic document feed device in  FIG. 1 . 
   Referring to  FIG. 1 , reference numeral  10  denotes an automatic document feed device provided in an image reading apparatus main body  1 , and functions to convey a document to pass through an upper surface of a contact glass  2  in the image reading apparatus main body  1 . In the image reading apparatus main body  1 , light from a light source  3  such as a lamp is irradiated through the contact glass  2  and its reflection light is reflected on a mirror  4 . Thereby, reading means such as a CCD reads out an image of the document by photoelectrically converting the reflected light of the document. 
   That is, the upper surface of the contact glass  2  forms a reading unit. Incidentally, the image reading apparatus main body  1  further comprises a contact glass  5  having an area capable of placing the document. The automatic document feed device  10  is opened, and the document is placed on the contact glass  5 . The image of the placed document can be read through the contact glass  5  by shifting a light source unit comprising the light source  3 , the mirror  4 , etc. in a sub-scan direction. 
   The automatic document feed device  10  comprises: a feed tray  15  on which a plurality of documents can be set; a feed unit (feed means)  11  for separating the documents on the feed tray  15  one by one and feeding each document to the contact glass  2 ; a conveyer unit  12  for transmitting the document along the upper surface of the contact glass  2 ; a discharge unit  13  for receiving the document transmitted through the upper surface of the contact glass  2  and discharging it; and a discharge tray  16  for enclosing the document that is discharged from the discharge unit  13 , of which the image is read out. Further, the automatic document feed device  10  comprises a switch-back unit  14  in which the discharge unit  13  switches back the document discharged from the upper surface of the contact glass  2 , and the document is transmitted to the feed unit  11  again and is fed onto the upper surface of the contact glass  2 . Herein, the feed tray  15  is arranged to ensure a space over the discharge tray  16  with a certain degree of an inclined angle. 
   A side guide  17  controls the side portion of the documents set on the feed tray  15  and a stopper  60  controls the edge portion of the documents. The feed tray  15  is rotatably mounted on an edge portion  15   a  of the set document as a fulcrum. 
   The feed unit  11  comprises a reel roller  18 , capable of elevating, which falls down, comes into contact with the uppermost document on the feed tray  15 , and thus reels out the document; separate means having a feed roller  19  for feeding the document reeled from the reel roller  18  and a separate pat  20  for transmitting only one uppermost document and preventing the document sequential to a second-uppermost document to be fed; and a pair of resist rollers  21  for abutting the edge of one document which is separated by the separating means, adjusting it, and transmitting it downstream. The document is fed along a feed path  25 . 
   Downstream the feed roller  19 , the edge of the document is abutted to the pair of resist rollers  21  and thus is bent (a loop is formed). A first loop space  30   a  is provided to receive the loop of the document. The document is abutted at a nip portion between the pair of the resist rollers  21  and a flection is formed. Thereby, the edge of the document is adjusted and the document is carried to prevent it from being transmitted in the inclined direction. 
   As shown in  FIG. 3 , the feed path  25  comprises an up-guide plate  25   a  and a down guide for feed  25   b  which are opposed each other. The up-guide plate  25   a  is fixed to a casing  10   a  which is rotatably supported to a rotational fulcrum  10   c , and it is opened/closed by integral rotation with the casing  10   a  in the counterclockwise direction. To the casing  10   a , arranged are the reel roller  18 , the feed roller  19 , a follower roller  21   b  of the pair of the resist rollers  21   b , and a stopper  60 . All of them are integrally rotated. Thus, the jammed document can be easily removed by entirely opening the feed path  25  from a feed port of the feed tray  15  to the contact glass  2  to be continuously exposed. 
   The conveyer unit  12  comprises: a pair of conveyer rollers  22  for supplying the document to the contact glass  2  to a portion in the up direction of the contact glass  2 ; and a pair of conveyer rollers  23  for discharging the document from the contact glass  2  to a portion in the down direction of the contact glass  2 . The document is conveyed along a conveyer path  26  formed of the contact glass  2 , a scoop guide  6  on the image reading apparatus main body  1  side, and a back-up guide  26   a  on the automatic document feed device  10 . 
   The discharge unit  13  and the switch-back unit  14  shares a part of the discharge tray  16 . A pair of discharge rollers  24  for discharging the document to the discharge tray  16  is provided to the shared portion. In a double-side mode, which will be described later, the pair of discharge rollers  24  is controlled to switch the document back in the nipped state of the bottom-edge of the document by their reverse rotation and controlled to transmit the document to the feed unit  11 . Further, the pair of discharge rollers  24  comprise a discharge drive roller  24   a  and a discharge follower roller  24   b  which are apart from each other to convey the document without fail, when the document is circulated from the switch-back unit  14  through the document feed unit  11  and the conveyer unit  12  and the top and bottom edges of the document cross. A flapper  29  for guiding the document to the feed unit  11  is provided at the shared portion of the discharge unit  13  and the switch-back unit  14 . The flapper  29  is always energized downward by an energizing spring (not shown). When the document is sent to the pair of discharge rollers  24  along the discharge path  27 , the discharge rollers  24  are pressed up by the edge of the discharged document to allow the document to be transmitted. When the document is switched back by the pair of the discharge rollers  24 , they exist downward and close the discharge path  27 , thereby guiding the document to the switch-back path  28 . 
   The discharge path  27  comprises: a discharge up-guide  27   a  which is formed by extending the back-up guide  26   a  provided opposed to the contact glass  2 ; and a discharge guide  27   b , made up of resin, which is formed integrally with the discharge tray  16 . The switch-back path  28  comprises an up guide for switch back  28   a  and a down guide for switch back  28   b  which are continuously provided to an document-guiding surface of the flapper  29 , and both of them guide the document to the nip portion of the pair of resist rollers  21 . 
   As mentioned above, a first loop space  30   a  is arranged downstream of the feed roller  19  to receive the flection (loop). Further, a second loop space  30   b  is arranged to the switch-back path  28  to form the flection of the document by abutting the edge of the document guided, through the switch-back path  28 , to the pair of the resist rollers  21 . The document is abutted at the nip portion between the pair of the resist rollers  21 , thus forming the flection. Then, the edge of the document is adjusted and a skew is removed. The document can be accurately nipped at the nip portion of the pair of the resist rollers  21  by a press force due to the flection of the document. 
   The aforementioned first loop space  30   a  and second loop space  30   b  are formed to bend the document to the outside. 
   Moreover, the switch-back path  28  is joined the feed path  25  at the nip portion of the pair of the resist rollers  21 . The pair of the resist rollers  21  adjusts the document fed through the feed path  25  and the document re-fed through the switch-back path  28 . As described above, the adjusting positions of the document (in the pair of the resist rollers  21 ) are commonly used, consequently, the document feed path in the overall device is simplified and becomes compact, and an operation for controlling the conveyance of the document is also simple. 
   The switch-back path  28  is jointed to the feed path  25  at the nip portion of the pair of the resist rollers  21 . A mylar  28   c  is extended to the conjunction position to introduce the document to the nip portion of the pair of the resist rollers  21 . 
   Here, the up guide for switch back  28   a  is formed integrally with the down guide for feed  25   b  as shown in  FIG. 4 . The integrated guides are rotatably supported in the clockwise direction with a rotational axis of the discharge drive roller  24   a  as a fulcrum. The separate pat  20  and the energizing spring  20   a  of the separating pat  20  are attached to the guides formed integrally with the up guide for switch back  28   a  and the down guide for feed  25   b , thus realizing the integral rotation. The switch-back path  28  from the pair of discharge rollers  24  to the pair of resist rollers  21  is entirely opened to be sequentially exposed. Therefore, the jammed document can be easily removed. 
   Only if the casing  10   a  opens the feed path  25 , the switch-back path  28  can be opened. Therefore, a proper process can be performed depending on the position of the jammed document. 
   The driving structure of each roller will be described with reference to  FIGS. 5 and 6 . In the automatic document feed device  10 , each roller is driven by a feed motor M 1  and a conveyer motor M 2  which can be driven forward and backward.  FIG. 5  shows a drive transmitting system of the feed motor M 1 , and  FIG. 6  shows a drive transmitting system of the conveyer moor M 2 . 
   First, in the drive transmitting system of the feed motor M 1 , as shown in  FIG. 5 , a forward drive of the feed motor M 1  is transmitted to a pulley P 36  from a pulley P 16  through a timing belt T 16 . The drive of the pulley P 36  is transmitted to a gear Z 17 , a gear Z 19 , and a gear Z 18  which is attached to a driving shaft of the feed roller  19 . Then, the feed roller  19  rotates in a direction to feed the document. A pulley P 18  is provided for the driving shaft of the feed roller  19 , and drive force is transmitted to the reel roller  18  via a timing belt T 2  which is tightly stretched to the pulley P 11  which is provided to the shaft of the reel roller  18 . One end of an elevating arm  18   a  for supporting the reel roller  18  is attached to the driving shaft of the feed roller  19 . The elevating arm  18   a  rotates and the reel roller  18  drops by the rotation of the driving shaft of the feed roller  19  in the feed direction (forward drive of the feed motor M 1 ). Then, when the reel roller  18  comes into contact with the document, the driving shaft of the feed roller  19  is raced to the elevating arm  18   a  by effect of spring clutches A and B. In this case, a resist drive roller  21   a  is connected to a pulley P 28  provided to the driving shaft of the resist drive roller  21   a  through a timing belt T 3  which is tightly stretched to a pulley P 22  provided to the same shaft as that of the pulley P 36 . The resist drive roller  21   a  does not rotate by effect of a one-way clutch OW 1  which is arranged in the pulley P 28 . 
   Backward drive of the feed motor M 1  is transmitted to the pulley P 36  from the pulley  16  through the timing belt T 16 , and is transmitted to a pulley P 28  attached to the shaft of the resist drive roller  21   a  from the pulley P 22  provided to the same shaft as that of the pulley P 36  through a timing belt T 3 , thus rotating the resist drive roller  21   a  in the document feed direction. In this case, the backward drive of the feed motor M 1  is also transmitted to the driving shaft of the feed roller  19 . The elevating arm  18   a  is rotated in the counterclockwise direction and then the reel roller  18  is elevated. However, the feed roller  19  does not rotate by effect of a one-way clutch OW 2  provided therein. The elevating arm  18   a  is elevated and is abutted to a restricting member (not shown). The driving shaft of the feed roller  19  is raced to the elevating arm  18   a  by effect of a spring clutch C. 
   With this arrangement, the gear Z 18  which is attached to the driving shaft of the feed roller  19  is arranged to the casing  10   a  together with the reel roller  18  and the feed roller  19 , thereby realizing their integral rotation. As shown in  FIG. 7 , the gear Z 18  exists away from the gear Z 19  by rotating the casing  10   a  and opening the feed path  25 . The gear Z 18  upon closing the casing  10   a  is meshed with the gear Z 19  by closing the feed path  25 . The center of the gear Z 18  is located at a position on a linear line joining the center of the gear Z 19  to a rotational fulcrum  10 C of the casing  10   a  (shown by a dotted oblique line in  FIG. 7 ) so that the gear Z 18  is meshed with the gear Z 19  smoothly and accurately when the feed path  25  is closed. Incidentally, referring to  FIG. 7 , line and a dotted line show a state in which the casing  10   a  is closed and a state in which it is opened, respectively. 
   As shown in  FIG. 6 , in the drive transmitting system of the conveyer motor M 2 , drive force is transmitted to a pulley P 46  from a pulley P 26  arranged to the driving shaft of the conveyer motor M 2  through a timing belt T 4 . The drive force is transmitted to a pulley P 32  attached to a shaft of a conveying drive roller  23   a  from a pulley P 33  provided to the shaft of the pulley P 46  through a timing belt T 6 . Thus, the conveying drive roller  23   a  is rotated forward or backward. In addition, the drive force transmitted to the pulley P 32  is transmitted to a pulley P 31  attached to the shaft of a conveying drive roller  22   a  via a timing belt T 7  and, thus, the conveying drive roller  22   a  is rotated forward or backward. Drive force of the conveyer motor M 2  transmitted to a pulley P 46  through the timing belt T 4  is transmitted to a pulley P 48  attached to a shaft of a discharge drive roller  24   a  from the shaft of the pulley P 46  via a timing belt T 5 . Thus, the discharge drive roller  24   a  is rotated forward or backward. 
   In addition, a solenoid SOL for press and contact as an electromagnetic solenoid is arranged as a drive source to make the pair of discharge rollers  24  spaced from each other. The solenoid SOL for press and contact moves the discharge follower roller  24   b  to be pressed against the discharge drive roller  24   a  by exciting (turning ON) the solenoid SOL for press and contact. By resetting (turning OFF) the excitation of the solenoid SOL for press and contact, the discharge follower roller  24   b  is moved apart from the discharge drive roller  24   a  by effect of an energization spring to energize the discharge follower roller  24   b  to be away from the discharge drive roller  24   a.    
   Herein, when the casing  10   a  is rotated and the feed path  25  is opened, an interlock switch stops the driving operation of the feed motor M 1  and the conveyer motor M 2  for driving each roller and the excitation of the solenoid SOL is off. As mentioned above, the feed motor M 1  and the conveyer motor M 2  are intermitted and, thus, the security can be ensured when removing the jammed document. Moreover, since the excitation of the solenoid SOL for press and contact is off, the document is not damaged due to the prevention of forcedly pulling out the document from the pair of discharge rollers  24  when the pair of the discharge rollers  24  is located apart from each other and the switchback path  28  is opened so as to remove the jammed document. 
   Although the interlock switch is adopted to forcedly shut off the driving operation of the feed motor M 1 , conveyer motor M 2 , and solenoid SOL for press and contact as stated above, each motor may be controlled to stop each roller by detecting the opened/closed status of the casing  10   a  and the solenoid SOL for press and contact can be controlled so that the pair of discharge rollers  24  are far from each other. 
   The driving operation of the feed motor M 1  may be shut off by opening the feed path  25  with an interlock switch which is operated by opening the switch-back path  28 . Further, the driving operation of the conveyer motor M 2  and the solenoid SOL for press and contact may be stopped by opening the switch-back path  28 . 
   A plurality of sensors S 1 , S 2 , and S 3  (shown in  FIG. 1 ) are arranged to the feed tray  15  in the document feed direction. The length of the document put on the feed tray  15  is detected by ON/OFF of the sensors S 1 , S 2 , and S 3 . The width of the document put on the feed tray  15  is detected by a volume an output of which changes depending on a moving amount of the side guide  17 . Thus, the size of the document is determined by the width, as the detected result, and the length of the document which is detected by the sensors S 1 , S 2 , and S 3 . 
   In the route for guiding the document, provided are an empty sensor S 4  for detecting that the document has been set on the feed tray  15 , a resist sensor S 5  for detecting the edge of the document that is fed in the feed path  25 , a lead sensor S 6 , provided in front of the contact glass  2 , for detecting the edge of the document (shown in  FIG. 6 ), and a discharge sensor S 7  for detecting the edge of the document which is discharged from the contact glass  2 . 
   Then, all of the resist sensor S 5 , lead sensor S 6 , and discharge sensor S 7  for detecting the document transmitted in the route are arranged in a space inside the route like a loop starting from the feed path  25  through the conveyer path  26 , the discharge path  27 , and the switch-back path  28  and, again, returning to the conveyer path  26 . This arrangement needs to ensure no space to which the sensors are attached and the device can be made compact. 
   Herein, the resist sensor S 5  uses a lever-type sensor as shown in  FIG. 8 . A sensor lever S 5   a  of the resist sensor S 5  is projected to both the feed path  25  and the switch-back path  28 . Since the single sensor can detect both the document sent through the feed path  25  and the document sent through the switch-back path  28  in the above arrangement, the number of sensors used as units can be reduced. Although the present embodiment employs the lever-type sensor as a sensor for detecting the document sent through the feed path  25  and the switch-back path  28 , the document in both the above paths can be detected by using a transmission-type sensor. 
   The sensors S 1  to S 7  are connected to a CPU for controlling the overall operation for driving the device. Based on detection signals from the sensors S 1  to S 7 , the feed motor M 1  and the conveyer motor M 2  are driven and the solenoid SOL for press and contact can be excited. 
   Next, a specific description is given of an operation for controlling the conveyance of the document in the above-structured automatic document feed device with reference to  FIGS. 9 to 22 . Incidentally, as needed,  FIGS. 23A to 24F  are referred in which conveyance statuses of the document are schematically shown. 
   First, a description is given of a one-side mode for reading one side of the document with reference to  FIGS. 9 to 13 . 
   In an ON status of the empty sensor S 4 , that is, when it is detected that the document is set on the feed tray  15 , the feed motor M 1  is driven forward, thereby feeding a first document D 1  (in steps S 1  and S 2 ). In this case, the reel roller  18  and the feed roller  19  are rotated in the document feed direction. However, the pair of the resist rollers  21  is not rotated by the effect of the one-way clutch OW 1 . When the resist sensor S 5  detects the edge of the fed document, the feed motor M 1  is temporarily stopped after a predetermined time t 1  from the detection (in steps S 3  to S 5 ). When the feed motor M 1  is stopped, the edge of the document is nipped at the nip portion of the pair of resist rollers  21 . Thus, a flection is formed, the edge of the document is adjusted, and a skew is removed (refer to  FIG. 23A ). After the intermission, the feed motor M 1  is driven backward, the conveyer motor M 2  is driven, and the solenoid SOL for press and contact is excited (in steps S 6  and S 7 ). In this case, the reel roller  18  elevates to be separate from the document. The feed roller  19  is intermitted by the effect of the one-way clutch OW 2 , and the resist drive roller  21   a  of the pair of resist rollers  21  is rotated in the document feed direction. 
   The document D 1  is carried to the conveyer path  26  from the feed path  25  by the rotation of the feed motor M 1  and the conveyer motor M 2 . When the lead sensor S 6  detects the transmission of the edge of the document D 1 , the feed motor M 1  is stopped after a predetermined time t 3  passes and the conveyer motor M 2  is temporarily stopped (in steps S 8  to S 10 ) (refer to  FIG. 23B ). A read conveying signal is received from the image reading device main body  1  and, then, the conveyer motor M 2  is driven again. The front side (one side) of the document D 1  is subscanned and read by the reading means (in steps S 11  and S 12 ). In this case, the document D 1  is conveyed onto the discharge tray  16  to press up the edge of the flapper  29  disposed for closing the discharge path  27 . 
   When the document D 1  is transmitted and the resist sensor S 5  detects the passage of a bottom edge of the document D 1 , it is detected whether or not there is a next document in the feed tray  15 . If there is a next document in the feed tray  15 , a second document D 2  starts to be fed, similarly to the manner of the first document D 1  (in steps S 13  to  15 ). When the second document D 2  is fed, in the above-mentioned manner of the document D 1 , the feed motor M 1  is driven forward, thereby, the reel roller  18  and the feed roller  19  are rotated, the document D 2  is nipped at the nip portion of the pair of the resist rollers  21 , and a skew is removed (in step S 16  to S 19 ) (refer to  FIG. 23C ). Then, the feed motor M 1  is driven backward, the predetermined time t 3  passes after the lead sensor S 6  detects the edge of the next document, the feed motor M 1  is stopped, and the conveyer motor M 2  is also stopped (in steps S 20  to S 23 ). Herein, the document D 2  is stopped so that the edge thereof is in front of the contact glass  2 . The first document D 1  is stopped by nipping the bottom edge thereof between the pair of discharge rollers  24  (refer to  FIG. 23D ). 
   A reading and conveying signal is received from the image reading apparatus main body  1  and, then, the conveyer motor M 2  is driven again. The front side of the document D 2  is subscanned and read by the above reading means (in steps S 24  and  25 ). During the reading operation of the second document D 2 , the first document D 1  is discharged onto the discharge tray  16  (refer to  FIG. 23E ). 
   When the resist sensor S 5  detects that the bottom edge of the document D 2  is transmitted, the empty sensor S 4  checked to see if there is a next document. If it is detected that there is a next document, similarly to the manner of the second document D 2 , a third document D 3  starts to be fed. Thereafter, so long as the empty sensor S 4  detects that there is an document (in steps S 14  to S 25 ), documents D 4 , D 5 , . . . are subjected to the above-described processes. 
   In the case of the final document, in step S 14 , the empty sensor S 4  enters the OFF status, a predetermined time t 5  for discharging the document to the discharge tray  16  passes after the discharge sensor S 7  detects the bottom edge of the final document, the conveyer motor M 2  is stopped, the excitation of the solenoid SOL for press and contact is off, and a process for all documents ends (in step S 26  to S 28 ). 
   Next, a description is given of a double mode for reading one side of the document with reference to  FIGS. 14 to 22 . 
   In the above-described manner in steps S 1  to S 10  in the one-side mode, the empty sensor S 4  detects that the documents are set on the feed tray  15 , the feed motor M 1  is driven forward, thereby rotating the reel roller  18  and the feed roller  19 , a first document D 1  is nipped at the nip portion between the pair of the resist rollers  21 , and a skew is removed. The first document D 1  is conveyed by the backward driving of the feed motor M 1  and the forward driving of the conveyer motor M 2 . The edge of the first document D 1  is detected by the lead sensor S 6 . After that, the feed motor M 1  and the conveyer motor M 2  are temporarily stopped and, thus, the document D 1  is stopped so that the edge thereof is in front of the contact glass  2 . In this case, the solenoid SOL for press and contact is excited and the pair of discharge rollers  24  are pressed and in contact (in steps S 51  to S 60 ) (refer to  FIG. 24A ). 
   The reading and conveying signal is received from the image reading apparatus main body  1  and, then, the conveyer motor M 2  is driven forward. Thereby, the front side of the document D 1  is transmitted onto the contact glass  2 , and is subscanned and read by the reading means. The document D 1  through the reading process by the contact glass  2  is guided to the discharge path  27  (in steps S 61  and S 62 ). 
   The document D 1  guided to the discharge path  27  is conveyed onto the discharge tray  16  to press up the edge of the flapper  29  disposed for closing the discharge path  27 . In the conveyed state, the discharge sensor  27  detects the bottom edge of the document D 1 . After a predetermined time t 11  for the transmission of the bottom edge of the document D 1  through the flapper  29 , the conveyer motor M 2  is stopped. The document D 1  is stopped by nipping the bottom edge thereof between the pair of discharge rollers  24  (in steps S 63  to  65 ) (refer to  FIG. 24B ). 
   Thereafter, the conveyer motor M 2  is driven backward (in steps S 66  and  67 ). Thus, the discharge drive roller  24   a  is rotated backward, and the document D 1  is switched and transmitted to backward. In association with the transmission, the document D 1  is guided into the switchback path  28  along an document leading surface of the flapper  29  which is moved to close the discharge path  27 . After the resist sensor S 5  detects the edge of the document D 1  which is guided to the switch-back path  28 , a flection is formed at the nip portion between the pair of the resist rollers  21 , a skew is removed, the conveyer motor M 2  driven backward is stopped after a predetermined time t 1  (in steps S 68  to S 70 ) (refer to  FIG. 24C ). Although in the embodiment of the present invention, the pair of discharge rollers  24  simultaneously functions as switch-back rollers for switching the document to back, the switch-back rollers can be independently provided. 
   To feed the document D 1  again, the feed motor M 1  is driven backward (in step S 71 ). The resist drive roller  21   a  is rotated in the document feed direction by the backward driving of the feed motor M 1 . After a predetermined time t 12  for certainly nipping the edge of the document D 1  between the pair of resist rollers  21 , the excitation of the solenoid SOL for press and contact is turned off. The discharge follower roller  24   b  is moved downward, it is thus made separate from the discharge drive roller  24   a , and the conveyer motor M 2  is driven forward (in steps S 72  and S 73 ). 
   The document D 1  is reversed and fed along the feed path  25 . When the edge of the document D 1  is detected by the lead sensor S 6 , the conveyer motor M 2  is stopped after the predetermined time t 3  and the feed motor M 1  is stopped (in steps S 74  to  76 ). Then, the conveyer motor M 2  is driven again by the reading and conveying signal from the image reading apparatus main body  1 , and the back side of the document D 1  is subscanned and read by the reading means (in steps S 77  and S 78 ). In this case, the top edge of the document D 1  to be transmitted to the discharge tray  16  crosses to the bottom edge of the document D 1  to be re-fed in a common portion between the discharge path  27  including the pair of discharge rollers  24  and the switch-back path  28 . Since the discharge drive roller  24   a  is apart from the discharge follower roller  24   b , the document D 1  can be carried without fail (refer to  FIG. 24D ). 
   Thereafter, the resist sensor S 5  detects the bottom edge of the document D 1 , then, the solenoid SOL for press and contact is excited, and the pair of discharge rollers  24  is pressed and contact with each other. The predetermined time t 11  passes after the discharge sensor S 7  detects the bottom edge of the document D 1  and, then, the conveyer motor M 2  is stopped. The bottom edge of the document D 1  is nipped between the pair of discharge rollers  24  (in steps S 79  to S 83 ) (refer to  FIG. 24E ). 
   To arrange pages in numerical order and discharge the documents to the discharge tray  16 , the conveyer motor M 2  is driven backward, the edge of the document D 1  is nipped at the nip portion between the pair of resist rollers  21  in the switch-back path  28 , and a skew is removed. The document D 1  is reversed and fed along the feed path  25  by the backward driving of the feed motor M 1 . The lead sensor S 6  detects the edge of the document D 1 , thereby stopping the feed motor M 1  (in steps S 84  to S 90 ). 
   The conveyer motor M 2  is driven forward, the excitation of the solenoid SOL for press and contact is off, and the document D 1  is conveyed onto the contact glass  2 . Herein, the document D 1  is not stopped in front of the contact glass  2  and is carried to the discharge path  27  because the document D 1  is not read by scanning (in steps S 91  to S 94 ). 
   During the process for carrying the document D 1  to the discharge path  27 , the resist sensor S 5  detects the bottom edge of the document D 1  (in step S 95 ). Then, the solenoid SOL for press and contact is excited, thereby, the pair of discharge rollers  24  is pressed and contact with each other, and it is checked whether or not there is an document in the feed tray  15  (in step S 96 ). If there is a second document D 2 , it starts to be fed in the same manner as that of the first document D 1 . 
   Steps of controlling the feed operation of the second document D 2  are performed similarly to the document D 1 . In other words, the reel roller  18  and the feed roller  19  are rotated by the forward driving of the feed motor M 1 . The document D 2  is abutted at the nip portion between the pair of resist rollers  21  and a skew is removed (in steps S 94  to S 101 ) (refer to  FIG. 24F ). 
   The feed motor M 1  is driven backward and the document D 2  is transmitted along the feed path  25 . The first document D 1  is discharged to the discharge tray  16  during the operation for reading the second document D 2  (in step S 102 ). 
   Sequentially, in the above manner of the first document D 1 , the second document D 2  is processed in control steps S 58  to S 96 . So long as the empty sensor S 4  detects that there is an document, documents D 3 , D 4 , . . . , are similarly processed. 
   Incidentally, in step S 100 , since the empty sensor S 4  is in the Off status, the discharge sensor S 7  detects the final document. Then, after the predetermined time t 5  for discharging the final document to the discharge tray  16 , the conveyer motor M 2  is stopped. The excitation of the solenoid SOL for press and contact is off and the processes for all documents end (in steps S 103  to S 105 ). 
   In the present embodiment, the document feed route is structured so that at the single position, the edge of the document fed from the feed tray is adjusted to that of the document which is switched back and is fed again. Consequently, the document feed route is shortened and simplified, thereby enabling efficient conveyance. 
   In the present embodiment, the up-guide plate  25   a  is fixed to the casing  10   a  and, by the integral rotation thereof in the counterclockwise direction, it can be opened/closed. Further, the reel roller  18 , feed roller  19 , follower roller  21   b  of the pair of resist rollers  21  are arranged to the casing  1   a , and are integrally rotated. As a consequence, the feed path  25  is successively exposed and opened, entirely from the feed port of the feed path  25  to the contact glass  2 . The jammed document can be easily removed from the feed path  25 . 
   The up guide for switch back  28   a  and the down guide for feed  25   b  are integrally formed, and the integrated guides are rotatably supported. In addition, since the separate pat  20  and the energizing spring  20   a  thereof are attached to the integrated guides, thereby realizing the integral rotation. The switch-back path  28  is sequentially exposed and opened, completely from the pair of discharge rollers  24  to the pair of resist rollers  21 . The jammed document can be easily removed from the switch-back path  28  Further, the excitation of the solenoid SOL for press and contact is off and the pair of discharge rollers  24  is located apart from each other by opening the casing  10   a . Therefore, there is not any danger in that the document is not damaged when removing the jammed document from the path for switch back  28 . 
   As discussed above, according to the present invention, if the document is jammed in any portion of the document transmitting path, the status of the document nipped between the pair of carrying and transmitting rollers is set. The jammed document can be easily removed without damaging the document. 
   The adjusting position of the edge of the document is a branch position between the feed path for guiding the document fed from the feed tray and the switch-back path for guiding the document which is switched back and transmitted. Therefore, the feed path and the switch-back path can be made almost linear upstream of the adjusting position. The document can be adjusted without fault. Moreover, a flexible film member is provided at the branch position to lead the edge of the document to the adjusting position. Accordingly, the edge of the document can be certainly led to the adjusting position, thus ensuring the adjustment of the document.