Multiple feeding preventing apparatus and image forming device including the same and image forming method

An image scanning method of an image scanning device, the method including: feeding multiply fed documents in a first path and scanning, by a scanning unit of the image scanning device, a first document of the multiply fed documents; outputting the first document through an exit unit; reversely driving the exit unit after the first document is output to reversely feed a second document of the multiply fed documents in a second path, and scanning the second document; and forming images of the first document and the second document, wherein the second path is used to reversely feed the second document to an upstream side of the scanning unit, in view of a feeding direction of the multiply fed documents.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No. 10-2008-0110497, filed Nov. 7, 2008 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Aspects of the present invention relate to a method and apparatus for scanning each of a plurality of sheets one by one in order to capture an image of each of the plurality of sheets, without multiple feeding of the sheets and an image forming device and method including the same.

2. Description of the Related Art

When documents are multiply fed in a scanning device (such as a multi-function printer, a scanner, a copy machine, etc.), conventional duplex automatic document feeders (DADFs) do not detect the multiple feeding and scan the multiply fed document. Thus, when a plurality of documents are multiply fed, a user has difficulty in determining if the documents have been multiply fed. Moreover, even when the user determines that the documents have been multiply fed, the user must re-feed the documents and rescan the documents.

A retard roller is used to prevent documents from being multiply fed. Specifically, a feeding roller that feeds sheets stored in a document storage case by using a pick-up roller and rotates in a feeding direction. The retard roller rotates in a reverse direction and is used to separate a plurality of documents. When a sheet of paper is fed, the retard roller does not reversely rotate due to a torque limiter. However, when two or more sheets of paper are fed (i.e., when a document or a paper is multiply fed), since a friction coefficient between the retard roller and the sheets is greater than a friction coefficient between the sheets, the retard roller reversely rotates and separates the sheets.

However, the retard roller, the pick-up roller, and the feeding roller are additionally required to prevent the documents from being multiply fed. Furthermore, a controller to control the coupling pressure between the feeding roller and the retard roller and the torque of the retard roller is additionally required. Moreover, the retard roller does not fully prevent documents or papers from being multiply fed.

Therefore, an apparatus and method to detect multiple feeding of documents and scanning the documents one by one, irrespective of a device such as the retard roller and the torque limiter, are required.

SUMMARY OF THE INVENTION

Aspects of the present invention provide an apparatus and method to detect a multiple feeding of a plurality of sheets and scanning the sheets one by one, irrespective of a device, such as a retard roller or a torque limiter. That is, aspects of the present invention provide an apparatus and method to detect multiple feeding of documents by using a simple device or method. Furthermore, aspects of the present invention provide an apparatus and method to output a scanned image of a first document by removing a part of an image of a second document that is included in the scanned image of the first document among a plurality of multiply fed documents.

According to an aspect of the present invention, there is provided an image scanning method of an image scanning device, the image scanning method including: feeding multiply fed documents in a first path and scanning, by the scanning unit, a first document of the multiply fed documents; outputting the first document through an exit unit of the image scanning device; reversely driving the exit unit after the first document is output to reversely feed a second document of the multiply fed documents in a second path, and scanning the second document; and forming images of the first document and the second document, wherein the second path is used to reversely feed the second document to an upstream side of the scanning unit, in view of a feeding direction of the multiply fed documents.

According to an aspect of the present invention, the method may further include: when at least a part of a scanned image of the second document is included in a scanned image of the first document, removing the at least part of the scanned image of the second document from the scanned image of the first document.

According to an aspect of the present invention, the method may further include: comparing a spaced distance between the multiply fed first and second documents with a minimum distance used for reverse feeding of the exit unit.

According to an aspect of the present invention, the exit unit may be reversely driven if the spaced distance is greater than or equal to the minimum distance.

According to an aspect of the present invention, the scanning unit may include first and second scanning units to scan the multiply fed documents, wherein the first scanning unit scans the first document, and the second scanning unit scans the second document that is reversely fed in the second path.

According to an aspect of the present invention, the first scanning unit and the second scanning unit may be disposed above and below the first path.

According to an aspect of the present invention, the first scanning unit and/or the second scanning unit may include a charge-coupled device (CCD) and/or a contact image sensor (CIS).

According to an aspect of the present invention, the second document may be scanned after having been reversely fed twice in the second path.

According to an aspect of the present invention, the second path may be a duplex feeding path used to scan both sides of the multiply fed documents.

According to an aspect of the present invention, the spaced distance may be determined according to a feeding speed of the multiply fed documents and according to a difference between a time when a sensor of the image scanning device detects the first document and a time when the sensor detects the second document.

According to an aspect of the present invention, the sensor may determine whether the documents are multiply fed according to a change in a difference of a distance between the sensor and the documents while the documents pass the sensor.

According to an aspect of the present invention, the minimum distance may be determined according to a size of the exit unit, a pressure applied to the exit unit, and/or a hardness of the exit unit.

According to another aspect of the present invention, there is provided an image scanning device including: a scanning unit to scan a plurality of documents; a first feeding unit disposed on a first path used to feed the documents; an exit unit to output the documents; and a second feeding unit to feed the documents and being disposed on a second path, wherein the second path is used to feed the documents in an upstream side of the scanning unit in view of a feeding direction of the documents, when the documents are multiply fed through the first feeding unit in the first path, the reading unit scans a first document of the multiply fed documents, the exit unit is reversely driven after the exit unit outputs the first document so that the second feeding unit reversely feeds a second document of the multiply fed documents, and the scanning unit scans the second document.

According to an aspect of the present invention, the device may further include a controller, when at least a part of a scanned image of the second document is included in a scanned image of the first document, removing the at least part of the scanned image of the second document from the scanned image of the first document.

According to an aspect of the present invention, the controller may compare a spaced distance between the multiply fed first and second documents with a minimum distance used for reverse feeding of the exit unit.

According to an aspect of the present invention, the controller may reversely drive the exit unit if the spaced distance is greater than or equal to the minimum distance.

According to an aspect of the present invention, the scanning unit may include first and second scanning units, wherein the first scanning unit scans the first document, and the second scanning unit scans the second document that is reversely fed in the second path.

According to an aspect of the present invention, the first scanning unit and the second scanning unit may be disposed in above and below, respectively, the first path.

According to an aspect of the present invention, the first scanning unit an/or the second scanning unit may include a CCD and/or a CIS.

According to an aspect of the present invention, the second document may be scanned after having been reversely fed twice in the second path.

According to an aspect of the present invention, the second path may be a duplex feeding path used to scan both sides of the multiply fed documents.

According to an aspect of the present invention, the spaced distance may be determined according to a feeding speed of the multiply fed documents and according to a difference between a time when a sensor detects the first document and a time when the sensor detects the second document.

According to an aspect of the present invention, the sensor may determine whether the documents are multiply fed according to a change in a difference of a distance between the sensor and the documents.

According to an aspect of the present invention, the minimum distance may be determined according to a size of the exit unit, a pressure applied to the exit unit, and/or a hardness of the exit unit.

According to another aspect of the present invention, there is provided an image scanning method of an image scanning device, the method including: when a plurality of documents are multiply fed, feeding the multiply fed documents in a path and scanning, by a scanning unit of the device, a first document of the multiply fed documents; outputting the first document through an exit unit of the image scanning device; reversely driving the exit unit after the first document is output, reversely feeding a second document of the multiply fed documents toward an upstream side of the scanning unit in view of a feeding direction of the multiply fed documents, and scanning the second document; and forming images of the first document and the second document.

According to an aspect of the present invention, the method may further include when at least a part of a scanned image of the second document is included in a scanned image of the first document, removing the at least part of the scanned image of the second document from the scanned image of the first document.

According to an aspect of the present invention, the method may further include comparing a spaced distance between the multiply fed first and second documents with a minimum distance used for reverse feeding of the exit unit.

According to an aspect of the present invention, the exit unit may be reversely driven if the spaced distance is greater than or equal to the minimum distance.

According to an aspect of the present invention, the scanning unit may be disposed above or below a point where the multiply fed documents are scanned on the feeding path.

According to an aspect of the present invention, the scanning unit may include a CCD and/or a CIS.

According to an aspect of the present invention, the spaced distance may be determined according to a feeding speed of the multiply fed documents and a difference between a time when a sensor detects the first document and a time when the sensor detects the second document.

According to an aspect of the present invention, the sensor may determine whether the documents are multiply fed according to a change in a difference of a distance between the sensor and the documents.

According to an aspect of the present invention, the minimum distance may be determined according a size of the exit unit, a pressure applied to the exit unit, and/or a hardness of the exit unit.

According to yet another aspect of the present invention, there is provided an image scanning device including: a scanning unit to scan a plurality of documents; a feeding unit disposed on a feeding path used to feed the documents; and an exit unit to output the documents, wherein when the documents are multiply fed through the first feeding unit in the first path, the scanning unit scans a first document of the multiply fed documents through the feeding unit disposed on the feeding path, the exit unit is reversely driven after the exit unit outputs the first document so as to reversely feed a second document of the multiply fed documents toward an upstream side of the scanning unit in view of the feeding unit of the multiply fed documents in the feeding path, and the scanning unit scans the second document.

According to an aspect of the present invention, the device may further include a controller, when at least a part of a scanned image of the second document is included in a scanned image of the first document, removing the at least part of the scanned image of the second document from the scanned image of the first document.

According to an aspect of the present invention, the controller may compare a spaced distance between the multiply fed first and second documents with a minimum distance used for reverse feeding of the exit unit.

According to an aspect of the present invention, the controller may reversely drive the exit unit if the spaced distance is greater than or equal to the minimum distance.

According to an aspect of the present invention, the scanning unit may be disposed above or below the feeding path.

According to an aspect of the present invention, the scanning unit may include a CCD and/or a CIS.

According to an aspect of the present invention, the spaced distance may be determined according to a feeding speed of the multiply fed documents and according to a difference between a time when a sensor detects the first document and a time when the sensor detects the second document.

According to an aspect of the present invention, the sensor may determine whether the documents are multiply fed according to a change in a difference of a distance between the sensor and the documents.

According to an aspect of the present invention, the minimum distance may be determined according to a size of the exit unit, a pressure applied to the exit unit, and/or a hardness of the exit unit.

According to still another aspect of the present invention, there is provided a document outputting method of a document outputting device including a feeding unit, the method including: determining whether the feeding unit multiply feeds documents in a first path; outputting a first document of the fed documents through an exit unit of the document outputting device; and when the feeding unit is determined to multiply feed the documents, controlling the exit unit to reversely feed a second document of the multiply fed documents to an upstream side of the first path, in view of a feeding direction of the multiply fed documents, after the first document is output.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIGS. 1 and 2are diagrams of a scanning unit of an image forming device (such as a scanner, a copier, or a multi-function device) and two sheets feeding paths according to an embodiment of the present invention. Referring toFIG. 1, a document scanning path includes a first path in which a plurality of documents (i.e., sheets of paper, transparencies, envelopes, etc.) move through a feeding roller112, a ledge roller118, a scan roller120, a scan module124, and an exit roller130. Furthermore, the document scanning path also includes a second path in which the documents that are reversely fed through the exit roller130move through a duplex roller132toward an upstream side of the scan module124in view of a document feeding direction. A duplex sensor134detects whether a document (such as a paper, a transparency, an envelope, etc.) is reversely fed via the second path, such that if the document is reversely fed via the second path, the duplex sensor134scans the rear side of the document.

A document scanning process via the first path will now be described in more detail. If a user places the documents on a document storage case (or a document feeder) and executes a scan or copy command in order to scan the documents, the documents are fed from the document storage case to the feeding roller112(1inFIG. 1). A ledge sensor116detects an arrangement state of the documents before the documents pass through the ledge roller118. If the ledge sensor116detects that the documents are not orderly arranged, the ledge roller118does not rotate so that the documents are not fed any more and can be orderly arranged by alerting the user to fix the documents. Thereafter, the ledge roller118rotates so that the documents are fed to the scan roller120(2inFIG. 1). The scan module124scans the documents to capture images thereof (3inFIG. 1). A scan sensor122is additionally installed on the upstream side of the scan module124in view of the document feeding direction, though all aspects are not limited thereto. In this case, the scan sensor124notifies a controller140of the image forming device that the documents enter the scan module124. The documents that have been scanned by the scan module124are output through the exit roller130. The scan module124, which optically scans an original image such as a printout, converts the original image into a digital image (such as a PDF, TIFF, or other digital format). For example, the scan module124may use a charge-coupled device (CCD), a contact image sensor (CIS), and/or a photomultiplier tube as an image sensor.

Hereinafter, a process of scanning or copying the documents will now be described when the documents are multiply fed (e.g., two sheets at once) from the document storage case through the feeding roller112. A detection sensor114to detect the multiple feeding of the documents is provided between the feeding roller112and the ledge roller118. When the detection sensor114detects multiple feeding of the documents, the detection sensor114generates a signal to inform the controller140of the image forming device about the multiple feeding of the documents. While not required in all aspects, the controller140can include a processor or microprocessor executing a computer program stored in a computer-readable medium, such as a storage unit (not shown) of the image forming device.

FIGS. 5A through 5Care diagrams to explain multiple feeding of documents detected by the detection sensor114according to an embodiment of the present invention. Referring toFIG. 5A, when two sheets of documents are multiply fed, a document placed on a relatively downstream side is a first document (first sheet), and a document placed on a relatively upstream side is a second document (second sheet) in view of the document feeding direction. For example, when the first and second documents that are spaced from each other by a predetermined distance pass the detection sensor114(for example, if the detection sensor114is located below the feeding path, when the first and second documents pass above the detection sensor114), the detection sensor114detects a distance H1between the first document and the detection sensor114when the first document is fed as inFIG. 5B, and a distance H2between the second document and the detection sensor114when the second document moves as the first document is fed as shown inFIG. 5C. Therefore, the detection sensor114detects the multiple feeding of the first and second documents due to a difference between the distances H1and H2(ΔH=H1−H2).

Although the detection sensor114detects the multiple feeding of the first and second documents due to the difference between the distances H1and H2in the shown embodiment, a variety of methods of detecting the multiple feeding of documents that are known to one of ordinary skill in the art may be applied to the present invention. Also, a spaced distance X between the first and second documents may be obtained by a distance ΔT between a time T1when the first document is detected and a time T2when the second document is detected and a feeding speed V of the first and second documents. The spaced distance X is related to a minimum distance S, which will be described later, and is used by the exit roller130to reversely feed the second document.

Referring back toFIGS. 1 and 2, the multiply fed documents are detected by the detection sensor114and enter into the scan module124through the ledge roller118and the scan roller120(1through3inFIG. 1). Although the scan module124is disposed in a downstream direction of the first path inFIG. 1, it is understood that aspects of the present invention are not limited thereto. For example, the scan module124may be disposed in an upstream direction of the first path according to a feeding direction of the first and second documents. The first document is scanned by the scan module124and is output through the exit roller130(4inFIG. 1). A gate roller126and a gate sensor128are additionally disposed between the scan module124and the exit roller130in the illustrated embodiment, though all embodiments are not limited thereto.

When the first document is output through the exit roller130(4inFIG. 1), the second document that is disposed on an upstream side of the first document by a predetermined spaced distance is not wholly output due to the engagement of nip portions of the exit roller130, and is reversely fed by a reverse driving of the exit roller130(5inFIG. 1). The reversely fed second document moves along the second path by the control of the gate roller126and the gate sensor128disposed at a point where the first and second paths diverge toward the upstream side of the scan module124in view of the document feeding direction. The first and second documents may move in the second path by using a document guide that guides the document feeding direction, such as a flapper, in addition to the gate roller126and the gate sensor128. The second document that moves toward the upstream side of the scan module124(6inFIG. 2) is not scanned through the scan module124since a scanned side of the second document does not face the scan module124(i.e., when the second document passes the scan module124, the scanned side is facing the duplex roller132). Therefore, the second document moves toward the upstream side of the scan module124again along the second path by another reverse driving of the exit roller130(5inFIGS. 1 and 6inFIG. 2), is scanned by the scan module124(7inFIG. 2), and is output through the exit roller130(8inFIG. 2).

FIG. 6is a diagram to explain the minimum distance S used by the exit roller130to reversely feed the documents according to an embodiment of the present invention. The minimum distance S is a distance used by the exit roller130to reversely feed the multiply fed documents in a lengthwise direction. Referring toFIG. 6, when the spaced distance X between the multiply fed first and second documents is greater than or equal to the minimum distance S, since the second document is engaged by the exit roller130by a length greater than the minimum distance S used to reversely feed the second document when the exit roller130outputs the first document, the second document is reversely fed. When the spaced distance X is less than the minimum distance S, since the second document is not sufficiently engaged by the exit roller130when the exit roller130outputs the first document, the second document is not reversely fed so that the exit roller130outputs the first and second documents together. In this case, a user manually puts the second document in the document storage case (or document feeder) in order to scan the second document according to a process described above. Furthermore, the controller140of the image forming device may receive information about the spaced distance X from the detection sensor114to detect the multiple feeding of the first and second documents, compare the information with the minimum distance S, and determine whether to reversely drive the exit roller130. While not required, if the detector sensor114indicates a multiple fed document but the minimum distance S is greater than the spaced distance X, the controller140might indicate a feed error to the user as the second document was likely not scanned.

Meanwhile, the minimum distance S varies according to embodiments of the present invention (for example, according to the size and characteristics of the exit roller130). Specifically, the greater the diameter of the exit roller130and the more the pressure (on the nip portions) applied to the exit roller130increases, the more the area of the exit roller130contacting the documents increases, so that the minimum distance S increases. Also, if the hardness of the exit roller130increases, although the same diameter and pressure are applied to the exit roller130, since the area of the exit roller130contacting the documents increases, the minimum distance S decreases. For example, if the diameter of the exit roller130is 15 mm, pressure of 3.0 kg/f is applied to the exit roller1330, and the hardness of the exit roller130is 70, the minimum distance S may be 9 mm.

Even if the documents multiply fed in the second path are all scanned inFIGS. 1 and 2, the second path may also be used as a duplex scan path in order to scan both sides of the documents.

Meanwhile, when the multiply fed documents are scanned or copied as shown inFIGS. 1 and 2, the second document that overlaps the first document may be scanned when the first document (first sheet) is scanned. In more detail, since at least a part of the image of the second document may be included in a scanned image of the first document, the at least partial image of the second document included in the scanned image of the first document is removed. In this regard, a method of determining a scanned image of the second document or a pattern thereof and removing a part related to the image of the second document from the scanned image of the first document may be considered. For example, when a rear image overlaps a front image, since it is possible to compare and analyze the scanned images of the first and second documents by using an operation of removing the overlapped image (a show through removal (STR) operation), it is possible to remove at least a part of the image of the second document from the scanned image of the first document by comparing next images.

Furthermore, in addition to the case where a part of the image of the second document is included in the scanned image of the first document, a part2000aof the second document corresponding to a distance spaced apart X from the first document may be included in the scanned image of the first document as shown inFIG. 10. In this case, a part where two images of the first and second documents are different from each other is determined as a scanned image1000of the first document, and the part2000aof the scanned image of the second document is removed from the scanned image1000of the first document.

FIGS. 3 and 4are diagrams of the scan module124disposed in an upper direction124band a lower direction124aof the first path according to an embodiment of the present invention. UnlikeFIGS. 1 and 2illustrating an embodiment where the scan module124is disposed in one direction of the first path, the scan module124is disposed in the upper direction124band the lower direction124aof the first path inFIGS. 3 and 4. Although the second document moves twice in the second path so that the scan module124scans the second document inFIGS. 1 and 2, the second document may move once in the second path so that the scan module124disposed in the upper direction124bcan scan the second document. The description of the apparatus and method shown inFIGS. 3 and 4is similar to that described with reference toFIGS. 1 and 2and thus the description will not be repeated here.

FIGS. 7 and 8are diagrams of a single feeding path according to an embodiment of the present invention. UnlikeFIGS. 1 through 4, the multiply fed first and second documents are scanned via a single feeding path. Referring toFIGS. 7 and 8, when the first document is output through the exit roller130, the second document disposed in the upstream side of the first document by at least the predetermined spaced distance is not output, reversely moves toward the upstream side of the scan module124via the single feeding path by the reverse driving of the exit roller130, moves to the scan module124, and is scanned by the scan module124. The description of the apparatus and method shown inFIGS. 7 and 8is similar to that described with reference toFIGS. 1 and 2and thus the description will not be repeated here.

FIGS. 9A and 9Bare flowcharts illustrating a method of scanning or copying multiply fed documents according to an embodiment of the present invention. Referring toFIGS. 9A and 9B, in operation910, a plurality of documents are fed into an image forming device. In operation912, it is determined whether the documents are multiply fed during a document feeding process. If it is determined that the documents are multiply fed (operation912), the image forming device determines whether a spaced distance X between multiply fed first and second documents (i.e., first and second sheets) is greater than a minimum distance S in operation914. If the image forming device determines that the spaced distance X is greater than the minimum distance S (operation914), the image forming device scans the fed documents in operation916and outputs the scanned documents in operation918.

In operation920, the image forming device determines whether the first document is output. If the image forming device determines that the first document is not output (operation920), operation918is performed until the image forming device determines that the first sheet is output in operation920. Meanwhile, if the image forming device determines that the first document is output (operation920), the image forming device reversely drives an exit roller (i.e., performs reverse feeding) in operation922, and feeds the second document along a duplex path in operation924. Accordingly, the image forming device scans the second document in operation926, forms an image on one or more sheets of print media by using the scanned image of the first document and the scanned image of the second document in operation928, and outputs the one or more sheets of print media on which the image is formed in operation930.

If the image forming device determines that the documents are not multiply fed (operation912) or the spaced distance X is smaller than the minimum distance S (operation914), the image forming device scans the fed document in operation932.

While described in the context of an image forming device, it is understood that aspects of the invention can be used in apparatuses that do not print data, such as scanners.