Conveyance apparatus, image reading apparatus, and image forming apparatus

A conveyance apparatus includes a separation unit configured to separate and convey a sheet, a detection unit configured to detect a floating of the sheet passing through the separation unit, and a control unit configured to stop separate conveyance by the separation unit if the detection unit detects the sheet for not less than a predetermined time and/or a predetermined count.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a conveyance apparatus, an image reading apparatus, and an image forming apparatus.

Description of the Related Art

A feeding device included in a copying machine, a scanner, a facsimile apparatus, or the like is provided with a separation mechanism configured to separate a plurality of sheets and convey them one by one to prevent the sheets from being conveyed in an overlapping state. With such a separation mechanism, documents on a document stack table can continuously be fed one by one, and images on the documents can sequentially be read. On the other hand, a bundle of documents that are bound by a staple or the like so as to be hard to separate is sometimes erroneously stacked on the document stack table. If such a bundle of documents passes through the separation mechanism, the documents may be deformed by the separating action and damaged. As a measure against this, Japanese Patent Laid-Open No. 2004-182449 discloses an apparatus provided with a sensor that detects an abnormal shape state of a document on the document stack table.

One of the behaviors of a bundle of bound documents passing through the separation mechanism is the floating of the document on the upper side. The bundle of bound documents can be detected by detecting the floating of the document. On the other hand, a document that is originally folded in a Z shape cannot be flat and remains wavy even if it is spread out and stacked on the document stack table. Such a document can be normally read if it is passed through the separation mechanism and separated and conveyed one by one, like a normal document. If it is determined whether a document is a bundle of bound documents or not based on only the floating of the document, the folded document may erroneously be detected as a bundle of bound documents.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided a conveyance apparatus comprising: a separation unit configured to separate and convey a sheet; a detection unit configured to detect a floating of the sheet passing through the separation unit; and a control unit configured to stop separate conveyance by the separation unit if the detection unit detects the sheet for not less than a predetermined time and/or a predetermined count.

DESCRIPTION OF THE EMBODIMENTS

First Embodiment

FIG. 1is a view showing the overall arrangement of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus includes an image reading apparatus1, and a printing unit300configured to print an image read by the image reading apparatus1on a sheet (printing medium) such as paper.

In this embodiment, the printing unit300is an image printing unit using electrostatic latent image formation. Sheets stacked and stored on an upper cassette100are separated and fed one by one by the action of separation grippers and a feed roller101and guided to a registration roller106. A lower cassette102also includes separation grippers and a feed roller103. From a manual feed guide104, sheets are guided one by one to the registration roller106via a roller105. A deck-type sheet stacking device108includes an inner plate108ato be vertically moved by a motor or the like. Sheets on the inner plate108aare separated and fed one by one by the action of separation grippers and a feed roller109and guided to a conveyance roller110.

A developer114, a transfer charger115, and a split charger116are arranged around a photosensitive drum112to form an image forming unit. A toner image developed on the photosensitive drum112is transferred to a sheet conveyed by the registration roller106. After that, the sheet is conveyed to a fixing device118by a conveying belt117to fix the image, and then conveyed to a diverter120by a conveyance roller119.

To discharge the sheet, the sheet is guided to a discharge roller121via the diverter120and conveyed into a sorter122. The sorter122includes a non-sort tray122a, a sort bin tray122b, a non-sort tray discharge roller122c, and a sort bin tray discharge roller122d. The non-sort tray122aand the sort bin tray122bvertically move to sort the sheets for each stage. Note that a discharge tray may be attached in place of the sorter.

When performing double-sided copy or multiple copy, a sheet after fixing is diverted by the diverter120and conveyed by a conveyance roller201. In double-sided copy, the sheet is discharged to an intermediate tray200via belts202and204, a path206, and a discharge roller205. In multiple copy, the sheet is discharged to the intermediate tray200by a diverter203. The intermediate tray200includes half-moon rollers209and210configured to feed the sheet, a separation roller pair211, and conveyance rollers213,214, and215configured to convey the sheet to the registration roller106.

The arrangement of the image reading apparatus1will be described with reference toFIG. 2in addition toFIG. 1.FIG. 2is a view showing the overall arrangement of the image reading apparatus1. The image reading apparatus1includes an automatic document feeder (to be referred to as a feeding device hereinafter)2serving as a sheet conveyance apparatus, and a reading device150that reads a document fed by the feeder2. The feeding device2is provided to open/close with respect to the reading device150.

The reading device150includes a reading unit151, a glass document table156, and a platen glass157. The reading device150can select a normal reading mode or a flow reading mode as a document reading mode. The glass document table156forms a light transmitting unit for the normal reading mode. The platen glass157forms a light transmitting unit for the flow reading mode.

The normal reading mode is a mode in which the reading unit151is moved in a sub-scanning direction H under the glass document table156, thereby scanning a document placed on the glass document table156and reading an image on the document. The flow reading mode is a mode in which the reading unit151is kept at rest at a reading position under the platen glass157, and an image on a document is read while conveying the document such that it passes on the platen glass157.

The reading unit151is, for example, a contact type image sensor, and includes line sensors arranged in the main scanning direction orthogonal to the sub-scanning direction H. As the guide structure of the reading unit151, the reading device150includes a guide member152such as a shaft body extending in the sub-scanning direction H. The reading unit151can reciprocally move in the sub-scanning direction H along the guide member152.

The reading device150includes a belt transmission mechanism as a drive mechanism configured to move the reading unit151. More specifically, the reading device150includes a driving pulley153and a driven pulley154which are spaced apart in the sub-scanning direction H. A belt155is wound around them. The driving pulley153is rotated by a motor153a. As the driving pulley153rotates, the belt155travels. The reading unit151is attached to the belt155. The reading unit151moves as the belt155travels.

The feeding device2will be described with reference toFIGS. 2, 3, and 4. The feeding device2conveys a sheet (document) as a reading target in the flow reading mode. In the following explanation, an upstream side and a downstream side are defined based on the sheet conveyance direction.

FIGS. 3 and 4are explanatory views of the internal arrangement of the feeding device2. The feeding device2includes a stacking unit30on which sheets are stacked. Documents D (sheets D) that are image reading targets are stacked on a stack surface30aof the stacking unit30.

A pickup roller31conveys an uppermost document D of the documents D stacked on the stacking unit30to a separation unit32. The feeding device2includes a lifting mechanism for the pickup roller31. At the time of feed, the pickup roller31lowers and contacts the uppermost document D, as shown inFIG. 4. The uppermost document D is conveyed to the separation unit32by the rotation of the pickup roller31. At all times other than the time of feed, the pickup roller31is lifted, as shown inFIG. 3. As the lifting mechanism, a known mechanism can be used.

The separation unit32is a unit arranged on the downstream side with respect to the pickup roller31and configured to separate and convey the documents stacked on the stacking unit30one by one. In this embodiment, the separation unit32includes a feed roller32aand a retard roller (separation member)32bthat pressure-contacts the feed roller32a. The feed roller32ais rotated to convey the sheet to the downstream side. The retard roller32bis provided with a torque limiter, and is dragged by the feed roller32awhen a predetermined load acts. If the documents are conveyed to the separation unit32in an overlapping state, the retard roller32bis not dragged by the feed roller32a. The document on the side of the feed roller32ais conveyed, and the document on the side of the retard roller32bis not conveyed. The documents are thus separated and conveyed one by one.

Note that as the arrangement of the separation unit32, an arrangement that inputs a driving force to the retard roller32bvia the torque limiter to reverse the retard roller32bor an arrangement that uses another separation member such as a separation pad in place of the retard roller32bcan also be employed.

The retard roller32bis rotatably supported by a holder23. The holder23includes a main body portion23aand a support portion23bconnected to the main body portion23aand having the retard roller32bmounted on it. A coil spring24intervenes between the main body portion23aand the support portion23b. The retard roller32bis brought into pressure-contact with the feed roller32aby the biasing force of the coil spring24.

The holder23is supported to be swingable in the direction of an arrow d2about an axis23c. The feeding device2includes a driving unit25capable of separating the feed roller32aand the retard roller32b. The driving unit25includes a motor25aand a cam25bthat is caused to pivot by the motor25a. As the cam25bpivots, the holder23swings about the axis23c. Unusually, the holder23is held at a position where the retard roller32bpressure-contacts the feed roller32a. If a paper jam or the like occurs, the driving unit25makes the holder23pivot counterclockwise inFIG. 3to separate the retard roller32bfrom the feed roller32a. It is therefore possible to easily extract the jammed document to the side of the stacking unit30.

A conveyance unit33is arranged on the downstream side with respect to the separation unit32and conveys a sheet passing through the separation unit32. The conveyance unit33includes registration rollers33aand33bthat are conveyance rollers. They pressure-contact each other to form a nip portion. One of the registration rollers33aand33bis a driving roller, and the other is a driven roller. The leading edge of a document is abutted against the nip portion in a state in which the registration rollers33aand33bare at rest, thereby correcting a skew of the document.

A platen roller35is arranged to face the platen glass157. A read roller pair36is arranged on the upstream side of the platen roller35, and a read roller pair37is arranged on the downstream side. The document passing through the conveyance unit33is conveyed by the read roller pair36, the platen roller35, and the read roller pair37so as to pass on the platen glass157.

A reversing discharge roller pair38conveys the document passing through the read roller pair37to a discharge unit39. The document is stacked on the discharge unit39. A flapper34that switches the conveyance path is provided between the read roller pair37and the reversing discharge roller pair38.

Detection units SR1to SR7included in the feeding device2will be described next. The detection unit SR1is a registration sensor arranged between the separation unit32and the conveyance unit33at a point before the conveyance unit33. The detection unit SR1includes a flag11athat freely pivots about an axis11c, and a photosensor (photointerrupter) that detects the pivot of the flag11a. The flag11ais biased clockwise inFIG. 3by a spring (not shown). If the document arrives at the conveyance unit33, the flag11ais pushed by the document and pivots, and the arrival of the document at the conveyance unit33can be detected. Then, the conveyance unit33is controlled based on the detection result of the detection unit SR1to correct the skew of the document. More specifically, the rotation of the conveyance unit33is stopped until a predetermined time elapses from document detection by the detection unit SR1. After the elapse of the predetermined time, control is done to rotate the conveyance unit33to do conveyance, thereby correcting the skew of the document.

The detection units SR2and SR3are sensors having the same arrangement as the detection unit SR1. The detection unit SR2is a read sensor that detects that the leading edge of the document passes through the read roller pair36. The start/end of reading of the reading unit151is controlled based on the detection result of the detection unit SR2. The detection unit SR3is a discharge sensor that detects that the leading edge of the document reaches a point before the flapper34.

The detection unit SR4is a sensor that detects multi feed of documents, and is sometimes called a multi feed detection sensor. The detection unit SR4detects multi feed of documents on the downstream side of a sheet-conveying position of the separation unit32and on the upstream side of a sheet-conveying position of the conveyance unit33. In this embodiment, the detection unit SR4is an ultrasonic sensor. A transmitter14aand a receiver14bare arranged on both sides of a conveyance path RT1. If multi feed is detected by the detection unit SR4, conveyance of the document D is stopped.

Each of the detection units SR5and SR6is a sensor that detects a deformation of the sheet, and is sometimes called a deformation detection sensor. Details will be described later. The detection unit SR7is a post-separation sensor that is arranged immediately after the nip portion of the separation unit32and detects that the leading edge of the document passes through the separation unit32. The detection unit SR7can be, for example, a sensor having the same arrangement as the detection unit SR1.

The detection unit SR8is a document detection sensor that detects whether the document D is stacked on the stacking unit30. In this embodiment, its detection position is set on the downstream side of a sheet-conveying-conveying position of the pickup roller31and on the upstream side of the sheet-conveying-conveying position of the separation unit32. The detection unit SR8can be, for example, a sensor having the same arrangement as the detection unit SR1.

Each of the detection units SR9and SR10is a document length sensor that detects the length of the document D. In this embodiment, their detection positions are set apart in the conveyance direction in the stacking unit30. The detection units SR9and SR10are, for example, reflection photosensors. As for the document length, for example, if both the detection units SR9and SR10detect the document D, the size can be determined to be large. If only the detection unit SR9detects the document D, the size can be determined to be small.

The feeding device2includes a main body unit20and a cover member21. The cover member21covers the above-described components such as the pickup roller31, the separation unit32, and the conveyance unit33from above. The cover member21is connected to the main body unit20via a hinge portion22and freely pivots in the direction of an arrow d1about the hinge portion22serving as the pivot center. Accordingly, as the cover member21pivots, the feeding device2can be opened/closed, and maintenance can be done if a paper jam or the like occurs. In addition, the pickup roller31, the feed roller32a, and the like are supported by the cover member21. When the cover member21is opened, these components move together with the cover member21. As a result, the maintainability further improves.

An example of the operation of the feeding device2in the flow reading mode will be described next. If the detection unit SR8detects the document D placed on the stacking unit30by the user, the document D is pulled into the apparatus by the pickup roller31and conveyed to the separation unit32. Even if a plurality of documents are conveyed in a multi feed state, the separation unit32separates the documents and conveys them one by one to the conveyance unit33.

If the detection unit SR1detects the leading edge of the document D, the leading edge of the document D conveyed by the separation unit32is abutted against the conveyance unit33that has stopped rotating, thereby correcting a skew of the document D. The detection unit SR1can be used not only to measure the timing of correcting the skew of the document D but also to measure the feed timing for the next document by the pickup roller31in accordance with detection of the trailing edge of the document D.

The document D that has undergone the skew correction is conveyed to the read roller pair36. Image reading by the reading unit151is started at a reading timing based on detection of the leading edge of the document D by the detection unit SR2. At this time, the reading unit151reads the image of the document D that is conveyed in a state in which the floating amount from the upper surface of the platen glass157is regulated by the platen roller35that rotates at a predetermined rotational speed.

The document D is conveyed by the read roller pairs36and37while its image is read by the reading unit151. When reading only one surface of the document D, the document D that has undergone the image reading is conveyed by the read roller pair37to the reversing discharge roller pair38and discharged to the discharge unit39.

When reading both surfaces of the document D, after the reading of the first surface, the reversing discharge roller pair38that is discharging the document D is stopped. After that, the reversing discharge roller pair38is rotated in the reverse direction to bring the document D back into the apparatus. Then, the flapper34switches the conveyance path to a reversing conveyance path RT2to feed the document D to the conveyance path RT1again. The reading unit151reads the second surface in accordance with the same procedure as described above. After that, the document is discharged to the discharge unit39, as in the single-sided reading.

<Detection of Sheet Deformation>

In this embodiment, the detection units SR5and SR6are arranged to detect a deformation, in particular, floating of the document which occurs when a bundle of documents bound by a staple or the like passes through the separation unit32. The floating of the sheet means a deformation of the sheet in a height direction at a side of the feed roller32aof the separation unit32. The detection units SR5and SR6are arranged so as to detect a sheet at a level higher than a level where a conveyed sheet passes in a normal state, and therefore the detection units SR5and SR6detect a sheet conveyed by the separation unit32in an abnormal state.FIG. 5is an explanatory view of the detection units SR5and SR6. Referring toFIG. 5, an arrow X represents the conveyance direction of the document (the path direction of the conveyance path RT1), and an arrow Y represents the widthwise direction of the conveyance path RT1.

The detection unit SR5is a sensor that detects the deformation of the sheet passing through the separation unit32at a position on the downstream side of the sheet-conveying position of the separation unit32and on the upstream side of the sheet-conveying position of the conveyance unit33. Thus, the detecting position of the detection sensor SR5is set at a position on the downstream side of the sheet-conveying position of the separation unit32and on the upstream side of the sheet-conveying position of the conveyance unit33. In this embodiment, the detection unit SR5detects the deformation of the sheet at a position closer to the separation unit32than the conveyance unit33. This enables quicker detection of the sheet deformation that occurs on the downstream side of the sheet-conveying position of the separation unit32.

The detection unit SR6is a sensor that detects the deformation of the sheet passing through the sheet-conveying position of the separation unit32at a position on the upstream side of the sheet-conveying position of the separation unit32. Thus, the detecting position of the detection unit SR6is set at a position on the downstream side of the sheet-conveying position of the separation unit32. In this embodiment, the detection unit SR6is arranged to detect the deformation of the sheet at a position on the upstream side of the sheet-conveying position of the pickup roller31. It is therefore possible to more quickly detect the sheet deformation that occurs on the upstream side of the sheet-conveying position of the separation unit32.

In this embodiment, the detection units SR5and SR6are transmission-type photosensors. However, these sensors may be sensors of another type. For example, they may be flag-type sensors like the detection unit SR1.

The detection unit SR5includes a light-emitting portion15aand a light-receiving portion15b. The light-emitting portion15aand the light-receiving portion15bare arranged on one lateral side and the other lateral side of the conveyance path RT1in the widthwise direction Y, and face each other. The light-emitting portion15aand the light-receiving portion15bare arranged at an interval larger than the width of a document in the maximum size. An optical path L5from the light-emitting portion15ato the light-receiving portion15bis set to cross the conveyance path RT1. In this embodiment, the optical path L5is parallel to the widthwise direction Y. However, the optical path L5may tilt with respect to the widthwise direction Y.

The optical path L5is set at a position apart upward from the conveyance plane of the conveyance path RT1. This can prevent a document that is normally conveyed from being erroneously detected.

In this embodiment, the detection unit SR6is formed like the detection unit SR5. The detection unit SR6includes a light-emitting portion16aand a light-receiving portion16b. The light-emitting portion16aand the light-receiving portion16bare arranged on one lateral side and the other lateral side of the stacking unit30in the widthwise direction Y, and face each other. The light-emitting portion16aand the light-receiving portion16bare arranged at an interval larger than the width of a document in the maximum size. An optical path L6from the light-emitting portion16ato the light-receiving portion16bis set to cross the stack surface30aof the stacking unit30. In this embodiment, the optical path L6is parallel to the widthwise direction Y. However, the optical path L6may tilt with respect to the widthwise direction Y.

The optical path L6is set at a position apart upward from the stack surface30aand set at a position higher than the upper limit height of stacked documents. This can prevent a document that is normally conveyed from being erroneously detected.

Examples of document deformation detectable by the detection units SR5and SR6will be described next. Types of a bundle of documents bound by staples and examples of deformation will be described first with reference toFIGS. 6A to 6EandFIGS. 7A to 8B. InFIGS. 6A to 6E, arrows indicate the document conveyance direction.

FIG. 6Ashows a bundle of documents bound by a plurality of staples ST along the edge on the trailing edge side in the conveyance direction.FIG. 7Ashows the behavior of the bundle of documents passing through the separation unit32. In the bundle of documents bound on the trailing edge side, the conveyance of the document D (uppermost document) on the side of the feed roller32aprogresses, and the conveyance of the document D on the side of the retard roller32bstops due to the separation action of the separation unit32on the leading edge side. For this reason, the trailing edge side of the bundle of documents bound by the staples ST floats in a loop shape. In this example, since the bundle of documents is bound by the plurality of staples ST along the edge, the trailing edge side of the bundle of documents floats in a wavy pattern almost evenly in the widthwise direction. Such a deformation can be detected by the detection unit SR6.

FIG. 6Bshows a bundle of documents bound by the staple ST at one corner on the trailing edge side in the conveyance direction.FIG. 7Bshows the behavior of the bundle of documents passing through the separation unit32. In the bundle of documents bound on the trailing edge side, the conveyance of the document D (uppermost document) on the side of the feed roller32aprogresses, and the conveyance of the document D on the side of the retard roller32bstops due to the separation action of the separation unit32on the leading edge side. For this reason, the trailing edge side of the bundle of documents bound by the staple ST floats in a loop shape. In this example, since the bundle of documents is bound by the staple ST at one corner, the trailing edge side of the bundle of documents floats unevenly in the widthwise direction, and the side of the staple ST floats higher. Such a deformation can be detected by the detection unit SR6.

FIG. 6Cshows a bundle of documents bound by the plurality of staples ST along the edge on the leading edge side in the conveyance direction.FIG. 8Ashows the behavior of the bundle of documents passing through the separation unit32. For the bundle of documents bound on the leading edge side, the separation action of the separation unit32tends to be effective after the staples ST pass through the separation unit32. Additionally, on the trailing edge side of the bundle of documents, the documents are not restrained. For this reason, the leading edge side of the bundle of documents bound by the staples ST floats in a loop shape on the downstream side of the sheet-conveying position of the separation unit32. In this example, since the bundle of documents is bound by the plurality of staples ST along the edge, the leading edge side of the bundle of documents floats in a wavy pattern almost evenly in the widthwise direction. Such a deformation cannot be detected by the detection unit SR6. In this embodiment, however, the detection unit SR5or SR4can detect the deformation.

FIG. 6Dshows a bundle of documents bound by the staple ST at one corner on the leading edge side in the conveyance direction.FIG. 8Bshows the behavior of the bundle of documents passing through the separation unit32. As in the example shown inFIGS. 6C and 8A, the leading edge side of the bundle of documents bound by the staple ST floats in a loop shape on the downstream side of the sheet-conveying position of the separation unit32. In this example, since the bundle of documents is bound by the staple ST at one corner, the leading edge side of the bundle of documents floats unevenly in the widthwise direction, and the side of the staple ST floats higher. Such a deformation cannot be detected by the detection unit SR6. The detection unit SR4can detect the deformation in some cases. However, depending on the deformation pattern, the document D does not overlap at the detection position of the detection unit SR4, and the deformation may be undetectable. In this embodiment, however, the detection unit SR5can detect the deformation.

FIG. 6Eshows a bundle of documents bound by the staples ST on a lateral side in the conveyance direction. The behavior of the bundle of documents passing through the separation unit32is the same as in the example ofFIG. 8B. The detection unit SR5can detect the deformation.

As described above, in this embodiment, since the detection unit SR5is provided, the bundle of documents bound on the leading edge side in the conveyance direction can be detected more quickly.

<Determination of Bundle of Bound Documents and Folded Document>

A document folded in a Z shape cannot be flat and remains wavy even if it is spread out and stacked on the stacking unit30.FIGS. 10A and 10Bshow an example of such a folded document.FIG. 10Ashows a document folded in a Z shape, andFIG. 10Bshows a state in which the document shown inFIG. 10Ais spread out. Even in the spread state as shown inFIG. 10B, a mountain-shaped crease remains.

Such a folded document normally passes through the separation unit32without any problem. However, if the folded document is fed, the mountain portion passes on the optical path L6of the detection sensor SR6, as shown inFIG. 11A, and is detected by the detection sensor SR6. Hence, if it is determined that the document is a folded document only based on the detection of the floating of the document by the detection sensor SR6, a detection error can occur.

To prevent this, a bundle of bound documents and a folded document are discriminated based on their behaviors.FIG. 11Bis a view showing an example of conditions to discriminate between a bundle of bound documents and a folded document. The continuous time (continuous ON time T) of detection by the detection sensor SR6changes between the bundle of bound documents and the folded document. More specifically, in the bundle of bound documents, the document on the upper side floats, as shown inFIGS. 7A and 7B. Additionally, by the action of the separation unit32, the floating state is maintained on the upstream side of the sheet-conveying position of the separation unit32. Hence, the detection time of the detection sensor SR6becomes relatively long. On the other hand, in the folded document, conveyance of the document is not impeded by the separation unit32. Since the mountain portion passes through the optical path L6in accordance with feeding, the detection time of the detection sensor SR6becomes relatively short. It is therefore possible to make a discrimination between the bundle of bound documents and the folded document based on the continuous ON time T of the detection unit SR6.

The continuous ON time T serving as a threshold to discriminate between the bundle of bound documents and the folded document can be changed depending on the document conveyance speed, the document length, or the document type (thickness or the like). In the example shown inFIG. 11B, the time serving as the threshold to discriminate between the bundle of documents and the folded document is changed depending on the document length. For a small size, if the continuous ON time T of the detection unit SR6is 100 ms or more, the document is determined to be a bundle of bound documents. If the continuous ON time T is less than 100 ms, the document is determined to be a folded document. For a large size, if the continuous ON time T of the detection unit SR6is 200 ms or more, the document is determined to be a bundle of bound documents. If the continuous ON time T is less than 200 ms, the document is determined to be a folded document. The size of the document stacked on the stacking unit30can be determined based on the detection results of the detection units SR9and SR10, as described above.

In addition, the detection count (intermittent ON count N) of the detection sensor SR6per unit time changes between the bundle of bound documents and the folded document. More specifically, in the bundle of bound documents, the document on the upper side floats, as shown inFIGS. 7A and 7B. Additionally, by the action of the separation unit32, the floating state is maintained on the upstream side of the sheet-conveying position of the separation unit32. At this time, the floating portion vibrates in a swinging manner due to the separation operation of the separation unit32for the bundle of documents. For this reason, the floating portion tends to cross the optical path L6a plurality of times, and the count of repetitive ON-OFF of the detection sensor SR6becomes relatively large. On the other hand, in the folded document, since the separation unit32performs a normal separation operation, the vibration factor is small. Since the climbing and descending portions of the mountain pass through the optical path L6, the detection count is 2. For this reason, if the detection count of the detection sensor SR6is 2 or less, the document can be determined to be a folded document. If the detection count is 3 or more, the document can be determined to be a bundle of bound documents. It is therefore possible to make a discrimination between the bundle of bound documents and the folded document based on the intermittent ON count N of the detection unit SR6.

The intermittent ON count N serving as a threshold to discriminate between the bundle of bound documents and the folded document can be changed depending on the document conveyance speed, the document length, or the document type (thickness or the like). In the example shown inFIG. 11B, the count serving as the threshold to discriminate between the bundle of documents and the folded document is changed depending on the document length. For a folded document whose document length is long (document size is large), the detection count may be large because of a swing or floating on the upstream side of the mountain portion. Even so, the detection count is probably about 4. Hence, for a large document size, if the detection count N of the detection sensor SR6is 2 to 4 or less, the document is determined to be a folded document. If the detection count N is 5 or more, the document can be determined to be a bundle of bound documents.

When a bundle of documents and a folded document are discriminated in this way, it is possible to accurately detect a bundle of bound documents and execute corresponding control (for example, feeding stop). Note that such a discrimination between a bundle of documents and a folded document can also be applied to the detection result of the detection sensor SR5.

A control system provided in the feeding device2will be described with reference toFIG. 9. The control circuit of the feeding device2is formed with a control unit40as the main component. The control unit40is, for example, a microcomputer including a CPU, a memory for storing data and programs to be executed by the CPU, and an interface to an external device. The detection units SR1to SR10are connected to the input ports of the control unit40. A motor44, a pick lowering solenoid41, a feed clutch42, and a registration clutch43are connected to the output ports. The motor44includes various kinds of motors. The various kinds of motors include, for example, motors serving as the driving sources of the pickup roller31, the feed roller32a, and the registration roller33aor33band the motor25a. In this embodiment, an arrangement in which the pickup roller31, the feed roller32a, and the registration roller33aor33bare driven by a common conveyance motor is assumed.

The pick lowering solenoid41is a solenoid configured to lower the pickup roller31. The pickup roller31is biased to the rising position by a spring (not shown). When the pick lowering solenoid41is driven, the pickup roller31lowers to the lowering position and abuts against the document D stacked on the stacking unit30. The feed clutch42is an electromagnetic clutch that interrupts the driving force of the conveyance motor to the feed roller32aand the pickup roller31. The registration clutch43is an electromagnetic clutch that interrupts the driving force of the conveyance motor to the registration roller33aor33b.

An example of feed control executed by the control unit40will be described with reference toFIG. 12. Control to make a discrimination between a bundle of documents and a folded document based on the detection result of the detection unit SR6and switch processing in a case in which the document D is fed from the stacking unit30to the downstream side of the conveyance unit33will be exemplified here.

When the user sets the document D on the stacking unit30, and the document detection sensor SR8detects the document (step S100), in step S101, the document length is detected based on the detection results of the document length detection sensors SR9and SR10. The size is determined as small if only the detection unit SR9is ON or as large if both the detection units SR9and SR10are ON, as described above. In step S102, feeding is started. More specifically, the pick lowering solenoid41is driven to lower the pickup roller31and abut it against the uppermost document D stacked on the stacking unit30. In addition, the feed clutch42is connected to transmit the driving force of the conveyance motor to the pickup roller31and the feed roller32a, and feeding is started.

If the deformation detection sensor SR6detects a floating of the document D during conveyance of the document D, the process advances to step S104. If a floating is not detected, the process advances to step S114to perform a reading operation. In steps S104to S106, the conditions to discriminate between a bundle of documents and a folded document are set based on the detection result of step S101. Here, a discrimination is made depending on whether the document length is 210 mm or more (whether the size is small or large). If the size is large (not less than 210 mm), the process advances to step S105to set the continuous ON time T serving as a threshold to 200 msec and set the intermittent ON count N to 5. If the size is small (less than 210 mm), the process advances to step S106to set the continuous ON time T serving as a threshold to 100 msec and set the intermittent ON count N to 3. At this time, as for the document size determination, if both the detection units SR9and SR10are ON in step S101, it is determined that the document length is 210 mm or more, and the size is large. If only the detection unit SR9is ON, it is determined that the document length is less than 210 mm, and the size is small. In step S107, measurement of the continuous ON time T and the intermittent ON count N of the deformation detection sensor SR6is started.

In step S108, it is determined whether the continuous ON time T is equal to or more than the threshold set in step S105or S106. If the continuous ON time T of the deformation detection sensor SR6is equal to or more than the threshold, the document is determined to be a bundle of bound documents, and the process advances to step S110. If the continuous ON time T of the deformation detection sensor SR6is less than the threshold, the process advances to step S109. In step S109, it is determined whether the intermittent ON count N within a predetermined time is equal to or more than the threshold set in step S105or S106. If the intermittent ON count N of the deformation detection sensor SR6is equal to or more than the threshold, the document is determined to be a bundle of bound documents, and the process advances to step S110. If the intermittent ON count N of the deformation detection sensor SR6is less than the threshold, the document is determined to be a folded document, and the process advances to step S114.

In this embodiment, the discrimination between the bundle of documents and the folded document is made based on two conditions, that is, the continuous ON time T and the intermittent ON count N of the deformation detection sensor SR6. However, the discrimination may be done based on only the continuous ON time T. However, if the discrimination is done based on the two conditions, the detection accuracy can further be improved.

In step S110, control to stop the job is performed. In this control, for example, the feed clutch42is disconnected to cut off the transmission of the driving force of the conveyance motor to the feed roller32a. The conveyance of the document D by the separation unit32thus stops.

In step S111, it is determined whether the user inputs a retry request. If a retry request is input, the process advances to step S112to reduce the conveyance speed of the document D. Then, the process returns to step S102to perform feeding again. If a retry request is not input, the process advances to step S113to perform processing associated with a staple error, and the processing ends. In step S113, for example, the retard roller32bmay be separated from the feed roller32aby the driving unit25. In addition, the user is notified of the occurrence of the error. The notification can be made by a voice or display by a display device.

In step S114, the reading operation is executed. After that, the process returns to step S100. If the document detection sensor SR8detects the next document, the same processing as described above is performed. If the next document is not detected, the processing ends.

As described above, even with the arrangement for detecting the floating of a document, it is possible to suppress an error of detecting a folded document as a bundle of documents bound by a staple or the like and accurately detect the bundle of bound documents.

In addition, since such a detection error can be prevented, reading can be done by a normal flow reading operation without stopping conveyance of a folded document. It is therefore possible to prevent conveyance of a folded document capable of normally being read from stopping and prevent the user from being promoted to set the document again.

Although conveying the documents D by the separation unit32is stopped based on the detection result of the detection unit SR6in the first embodiment, conveying sheets can be stopped in the whole apparatus1when the bundle of bound documents is detected. In this case, each conveying section in the apparatus1can simultaneously be stopped, or each conveying section in the apparatus1can be stopped in order from a conveying section which is conveying a sheet. In a case that there is a sheet which is normally conveyed at the downstream side of the sheet-conveying position of the separation unit32when the conveying documents D by the separation unit32should be stopped, each conveying section in the apparatus1can be stopped after discharging the sheet.

Second Embodiment

A guide member configured to guide a deformation of a sheet passing through a separation unit32may be provided.FIGS. 13A and 13Bshow an example of a guide member50. The guide member50is provided on a cover member21.

The guide member50will be described. The guide member50is provided to guide a deformed portion of a sheet passing through the separation unit32into an orientation corresponding to detection by a detection unit SR6. In this embodiment, since the detection unit SR6is a photosensor, the deformed portion of the sheet is guided such that it crosses an optical path L6. This will be described in detail with reference toFIGS. 13A and 13B.

If the trailing edge in the conveyance direction is bound by a plurality of staples ST along the edge, as shown inFIG. 6A, the end of the bundle of documents floats in a wavy pattern almost evenly in the widthwise direction, as shown inFIG. 7A, and the planar direction of a floating document D becomes almost parallel to a widthwise direction Y. In a case in which the optical path L6is almost parallel to the widthwise direction Y, if the document D is thin, the document D may be unable to sufficiently interfere with light on the optical path L6, the detection unit SR6may be unable to detect the floating of the document D, and the bundle of documents may be passed.FIG. 13Aschematically shows a case in which the optical path L6is parallel to the widthwise direction Y. As shown inFIG. 13A, if the optical path L6is almost parallel to the widthwise direction Y, the planar direction of the document D and the optical path L6are almost parallel, and the light on the optical path L6may not be shielded by the document D.

The guide member50obliquely tilts the portion that floats in a loop shape to make the planar direction of the document D cross the optical path L6so that the document D can easily shield the light on the optical path. This can improve the accuracy of detecting the deformation of the document D. When the accuracy of detecting the deformation of the document D improves, conveyance of the bundle of bound documents can correctly be stopped. It is therefore possible to prevent damage to the bundle of documents.

FIG. 13Bshows the guide form of the deformed portion of the document D by the guide member50. In this embodiment, the guide member50is a plate-shaped member projecting from the end of the cover member21to the upstream side (the side of a stacking unit30) in the sheet-conveyance direction. The guide member50is located at a position closer to a lateral side than the center of a conveyance path RT1(or to a lateral side than the center of a stack surface30a), and abuts against an end of a bundle of documents deformed into a loop shape and traveling in the conveyance direction. When the end of the bundle of documents, which floats in a wavy pattern almost evenly in the widthwise direction, abuts against the guide member50, traveling is relatively delayed on the abutting side but relatively progresses on the non-abutting side. As a result, the floating portion tilts with respect to the widthwise direction. The position of the guide member50can be set such that, for example, it abuts against a region corresponding to ¼ of the width of the document D from one side edge of the document D in the widthwise direction.

As a result, the planar direction of the document D crosses the optical path L6, the light on the optical path is shielded by the document D, and the floating of the document D is detected by the detection sensor SR6.

Although the guide member50promotes to detect the floating of the document D by the detection sensor SR6, a folded document may be erroneously detected as a bundle of bound documents. However, a bundle of bound documents can be precisely detected by discriminating between a bundle of documents and a folded document based on the detection time or the detection count as the first embodiment. Further, since such an erroneous detection can be prevented, the flow reading mode can be conducted without stopping conveying a folded document. It is therefore possible to prevent conveyance of a folded document capable of normally being read from stopping and prevent the user from being promoted to set the document again.

The guide member50may be provided independently of the cover member21. However, when the guide member50is provided using the cover member21, the number of parts can be reduced. When the guide member50is formed integrally with the cover member21, the number of parts can further be reduced.

The guide member50can have any shape as long as the deformed portion of the document D can be guided in the above-described way, and the arrangement point can also appropriately be changed. In this embodiment, the guide member50is provided for the detection sensor SR6. However, a guide member having the same function as the guide member50may be provided for another detection sensor.

In addition, the guide member50can be applied to a sensor other than a transmission-type photosensor like the detection unit SR6. In this case as well, it need only guide the deformed portion of the sheet to improve the detection accuracy of the sensor.

Modification of Second Embodiment

In the control according to the first embodiment, if a bundle of documents bound on the trailing edge is detected by the detection unit SR6, the separation unit32is stopped to stop feeding of the bundle of documents. The user can open the cover member21and extract the bundle of documents. However, the guide member50projects from the end of the cover member21and may therefore be an obstacle when the user extracts the bundle of documents. For example, the loop portion of the bundle of documents may be caught on the guide member50. If the cover member21is forcibly opened in this state, the bundle of documents may be damaged.

FIG. 14shows an example of the arrangement of a guide member60according to a modification. The guide member60has, at one end, an abutting portion60athat abuts against the document D. The abutting portion60aforms a movable member that can reciprocally move in the conveyance direction of the sheet. The guide member60is movable. For this reason, when the user opens the cover member21and extracts the bundle of documents, the abutting portion60ais retreated to the side of the cover member21, thereby avoiding a situation in which the guide member60becomes an obstacle when opening the cover member21.

In the modification, the guide member60is configured to move coordinately with the opening operation and the closing operation of the cover member21. Hence, the user can displace the guide member60without separately operating the cover member21and the guide member60. The structure will be described below with reference toFIGS. 15A to 17Bin addition toFIG. 14.FIGS. 15A to 16Aare operation explanatory views showing the operation of the guide member60obliquely from above through the cover member21.FIG. 15Ashows a case in which the cover member21is closed.FIG. 15Bshows a state in which the cover member21starts opening.FIG. 16Ashows a state in which the cover member21is slightly opened.FIGS. 16B to 17Bare operation explanatory views showing the operation of the guide member60from the outside of the feeding device2.FIGS. 16B to 17Bcorrespond to the states of the cover member21shown inFIGS. 15A to 16A, respectively.

The guide member60is pivotally supported by the cover member21at an axial portion61a. The guide member60may be configured to translate in the conveyance direction. However, when the guide member60is configured to pivot, the abutting portion60acan be moved more largely by a smaller moving amount (pivot amount) of the guide member60. A projecting portion62projecting downward is formed at the other end of the guide member60. The projecting portion61bis provided to abut against a leaf spring62supported by a frame63of the main body20.

The leaf spring62tilts obliquely downward in the conveyance direction of the sheet, and applies a biasing force in the conveyance direction to the projecting portion61babutting against the leaf spring62. By this biasing force, the guide member60is given a pivotal habit in a direction in which the abutting portion60aprojects from an end of the cover member21.

On the other hand, a coil spring64is provided between the guide member60and the cover member21. By the biasing force of the coil spring64, the guide member60is given a pivotal habit in a direction in which the abutting portion60aretreats from the end of the cover member21into the apparatus.

The behavior of the guide member60coordinated with the opening operation of opening the cover member21from a closed state will sequentially be explained.FIGS. 15A and 16Bshow a case in which the cover member21is in a closed state. In this state, the projecting portion61babuts against the leaf spring62. The biasing force of the leaf spring62is set to be larger than that of the coil spring64, and the abutting portion60aprojects from the end of the cover member21. In this state, the abutting portion60afunctions like the guide member50according to the first embodiment, and guides the deformed portion of the sheet into an orientation corresponding to detection by a detection unit SR6.

FIGS. 15B and 17Ashow a case in which the cover member21starts opening. If the cover member21starts opening, the guide member60starts separating upward from the main body20. For this reason, the projecting portion61bstarts separating from the leaf spring62, the biasing force of the leaf spring62stops acting on the projecting portion61b, and the biasing force of the coil spring64becomes larger. For this reason, the guide member60starts pivoting as shown inFIG. 13B, and the abutting portion60astarts retreating from the end of the cover member21to the downstream side.

FIGS. 16A and 17Bshow a state in which the cover member21is slightly opened, that is, a state in which the opening of the cover member21has progressed as compared to the state shown inFIGS. 15B and 17A. The projecting portion61bis completely separated from the leaf spring62, and the pivotal movement of the guide member60further progresses by the biasing force of the coil spring64. The abutting portion60aretreats from the end of the cover member21into the apparatus.

In this way, the guide member60pivots coordinately with the opening operation of the cover member21, and the abutting portion60aretreats. For this reason, even if the bundle of documents is caught on the abutting portion60a, the catch is eliminated automatically by opening the cover member21. If the cover member21is returned to the closed state after removal of the bundle of documents, the projecting portion61babuts against the leaf spring62again. By the biasing force, the guide member60returns to the state shown inFIGS. 15A and 16B, and thus returns to the state in which the abutting portion60aprojects from the cover member21. Note that the above-described moving mechanism of the guide member60is merely an example, and another mechanism that exhibits the same function as described above can also be employed.

Third Embodiment

Optical paths L5and L6may be set in a direction to tilt with respect to a widthwise direction Y.

<Tilt of Optical Path>

An advantage obtained when the optical paths L5and L6are tilted will be described with reference toFIGS. 18A to 18C.FIG. 18Ais an explanatory view schematically showing the arrangement of light-emitting units15aand16aand light-receiving units15band16b.

In this embodiment, the light-emitting unit15aand the light-receiving portion15bare arranged at positions shifted in a conveyance direction X and face each other in a direction tilting with respect to the widthwise direction Y. Hence, the optical path L5tilts in the conveyance direction X by an angle θ5with respect to the widthwise direction Y. Similarly, the light-emitting unit16aand the light-receiving portion16bare arranged at positions shifted in the conveyance direction X and face each other in a direction tilting with respect to the widthwise direction Y. Hence, the optical path L6tilts in the conveyance direction X by an angle θ6with respect to the widthwise direction Y.

If an end in the conveyance direction is bound by a plurality of staples ST along the edge, as shown inFIG. 6A or 6C, the end of the bundle of documents floats in a wavy pattern almost evenly in the widthwise direction, as shown inFIG. 7A or 8A, and the planar direction of a floating document D becomes almost parallel to the widthwise direction Y. In a case in which the optical paths L5and L6are set to be almost parallel to the widthwise direction Y, if the document D is thin, the document D may be unable to sufficiently interfere with light on the optical paths. It may be impossible to detect the floating of the document D, and the bundle of documents bound by the staples ST may be passed. On the other hand, if the optical paths L5and L6are tilted with respect to the widthwise direction Y, the detection ranges of detection units SR5and SR6widen, and the floating document D can sufficiently interfere with the light on the optical paths. As a result, the accuracy of detecting the deformation of the document can be improved independently of the thickness of the document.

FIG. 18Bschematically shows a case in which the optical path L6is parallel to the widthwise direction Y, andFIG. 18Cschematically shows a case in which the optical path L6tilts with respect to the widthwise direction Y. As shown inFIG. 18B, if the optical path L6is parallel to the widthwise direction Y, and optical path L6and the planar direction of the document D that floats due to the binding become almost parallel. Even if the document D shields the light on the optical path, the detection unit may be unable to detect this, and the stapled document D may be passed. If the optical path L6is tilted as shown inFIG. 18C, the planar direction of the document D crosses the optical path L6, and the light on the optical path is shielded more easily by the document D. The accuracy of detecting the deformation of the document D can thus be improved regardless of the thickness, and the conveyance of the bound document can be stopped.

The optical path L6has been described with reference toFIGS. 18B and 18C. This also applies to the optical path L5. The angles θ5and θ6may be different or the same. If the angles θ5and θ6are too small, the improvement of the detection accuracy is small. If the angles are too large, a disadvantage for the sensor layout may occur. Hence, the angles θ5and θ6can be angles within the range of, for example, 1° (inclusive) to 45° (inclusive). At this time, lenses (not shown) configured to tilt the optical paths L5and L6or components used to support or arrange the light-emitting units15aand16aand the light-receiving units15band16bto tilt the optical paths L5and L6are defined as optical path forming units.

In this embodiment, the direction to tilt the optical paths L5and L6with respect to the widthwise direction Y is the conveyance direction X. However, it may be the vertical direction. The optical paths may tilt in both the conveyance direction X and the vertical direction. In this embodiment, both the optical paths L5and L6are tilted. However, only one of them may be tilted.

Although tilting the optical paths L5and L6promotes to detect the floating of the document D by the detection sensors SR5and SR6, a folded document may be erroneously detected as a bundle of bound documents. However, a bundle of bound documents can be precisely detected by discriminating between a bundle of documents and a folded document based on the detection time or the detection count of the detection sensor SR6as the first embodiment. Further, since such an erroneous detection can be prevented, the flow reading mode can be conducted without stopping conveying a folded document. It is therefore possible to prevent conveyance of a folded document capable of normally being read from stopping and prevent the user from being promoted to set the document again.

Other Embodiments

This application claims the benefit of Japanese Patent Applications No. 2016-114680, filed Jun. 8, 2016, No. 2016-114683, filed Jun. 8, 2016, and No. 2016-114684, filed Jun. 8, 2016, which are hereby incorporated by reference herein in their entirety.