Document Feeder

Abstract

To prevent the occurrence of multi-feeding when a plurality of documents are loaded, in a mode for rotating a retard roller in a direction to feed documents in a document conveyance direction.SOLUTION: A document conveying device includes a lift board, a pick-up roller, a lift motor, a retard roller, and a control unit. In a manual paper feed mode, the control unit rotates the retard roller in a direction to feed documents in a document conveyance direction. After the start of rotation of the pick-up roller, the control unit causes the lift motor to start lowering the lift board while the pick-up roller feeds the documents.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to an original transport device that feeds and transports a set original. [Background technology]

[0002] There are image reading devices (for example, multifunction devices) that are equipped with a document transport device. The document transport device sends out the set documents one by one. Image data is generated by reading the sent documents. In the document transport device, multiple documents may be fed and transported overlapping with each other. In some cases, the documents are transported overlapping with most of them, and in other cases, the documents in front and the following documents are transported overlapping with each other. To eliminate overlaps, a separation mechanism may be provided. The separation mechanism includes, for example, a separation roller. The separation roller rotates in the direction that sends the documents in the opposite direction (upstream direction) to the document transport direction. The separation roller separates the overlapped documents and sends back the unnecessary documents. The separation roller helps to eliminate overlaps.

[0003] An example of an apparatus equipped with a separation mechanism including a separation roller is described in Patent Document 1. Specifically, Patent Document 1 describes a sheet feeding apparatus that has a separation mode in which sheets are separated and fed one by one from a stack of multiple sheets, and a non-separation mode in which sheets are not separated and fed, and that switches from the non-separation mode to the separation mode after a feeding operation in the non-separation mode is completed. The feeding mode is automatically switched to reduce the burden on the user (Patent Document 1: Claim 1, paragraph

[0006] ). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-041118 A Summary of the Invention [Problem to be solved by the invention]

[0005] There are documents in which multiple sheets are stacked. For example, such documents include delivery slips for packages (home delivery). Delivery slips often have carbon paper for copying stacked on top of them. There are also documents with removable sheets (e.g., sticky notes, stickers) attached to them, or documents with photos attached to them. With such documents, if the separation roller is rotated in a direction that transports the document in the opposite direction to the document transport direction, sheets that are attached to the document and that should not be removed may peel off. In other words, if the separation roller is made to perform an operation to eliminate double feeding, the document may be damaged.

[0006] Therefore, a mode in which the separation roller does not perform a separation operation (non-separation mode in Patent Document 1) may be made available in the document transport device. In the non-separation mode, the separation roller rotates in a direction that sends the document in the transport direction. In other words, the rotation direction of the separation roller is reversed between the non-separation mode and the separation mode.

[0007] However, in the non-separation mode, the function to eliminate overlapping of documents does not work. When multiple documents are set, in the non-separation mode, there is a problem that the documents are likely to be fed and transported in an overlapping or continuous state. In other words, in the non-separation mode, there is a problem that continuous feeding is likely to occur.

[0008] In Patent Document 1, in the non-separation mode, the separation roller is simply rotated in a direction that sends the document in the document transport direction. In the device described in Patent Document 1, documents are likely to be transported in a continuous manner. It is necessary to frequently perform processing to eliminate errors caused by continuous feeding (for example, jam processing). In addition, in the device described in Patent Document 1, in the non-separation mode, the detection of multiple feeds is disabled (not performed) (Patent Document 1: paragraphs

[0054] and

[0055] ). Therefore, in the non-separation mode, even if continuous feeding occurs, the transport is not stopped, so when an error occurs, the degree of damage to the document may become greater. The technology described in Patent Document 1 is not useful for solving the above problems.

[0009] The present invention has been made in consideration of the problems with the conventional technology described above, and aims to prevent continuous feeding (multiple feeding) from occurring in a manual feed mode in which the retard roller is rotated in a direction that sends the document in the document transport direction, even when multiple documents are set. [Means for solving the problem]

[0010] In order to solve the above problem, the document transport device according to claim 1 includes a lift plate, a pickup roller, a lift motor, a retard roller, and a control unit. Documents are set on the lift plate. The pickup roller contacts the top document of the documents set on the lift plate. The pickup roller rotates to feed the document in the document transport direction. The lift motor raises and lowers the lift plate. When starting to feed the document, the lift motor raises the lift plate until the top document contacts the pickup roller. The retard roller is provided downstream of the pickup roller in the document transport direction. The retard roller contacts the document sent out by the pickup roller. When a normal mode is selected, the control unit rotates the retard roller in a direction to feed the document in a direction opposite to the transport direction. When a manual feed mode is selected, the control unit rotates the retard roller in a direction to feed the document in the transport direction. When the manual feed mode is selected, the control unit causes the lift motor to start lowering the lift plate while the pickup roller is feeding the document after the pickup roller starts rotating. Effect of the Invention

[0011] According to the present invention, in the manual feed mode in which the retard roller is rotated in a direction that sends the document in the document transport direction, even if a plurality of documents are set, the occurrence of continuous feeding can be prevented. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating an example of a multifunction peripheral according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of a document transport device and an image reading unit according to the embodiment. [Diagram 3] FIG. 2 is a diagram illustrating an example of a document transport device and an image reading unit according to the embodiment. [Figure 4] 2 illustrates an example of an internal view of a document transport device according to an embodiment, as viewed from above. [Diagram 5] 5A and 5B are diagrams illustrating an example of transmission of drive force of a feed motor according to an embodiment. [Figure 6] 5A and 5B are diagrams illustrating an example of transmission of drive force of a feed motor according to an embodiment. [Figure 7] 11A and 11B are diagrams illustrating an example of a flow of transport and reading in a normal mode according to the embodiment. [Figure 8] 11A and 11B are diagrams illustrating an example of a flow of conveying and reading in a single-sheet reading mode according to the embodiment. [Figure 9] 11A and 11B are diagrams illustrating an example of a flow of transport reading in a continuous reading mode according to the embodiment. [Figure 10] 6 is a timing chart showing an example of an operation in a manual insertion mode according to the embodiment. [Figure 11] FIG. 11 is a diagram showing an example of a mode selection screen according to the embodiment. [Figure 12] 11A and 11B are diagrams illustrating an example of a flow of automatic change from a continuous scanning mode to a single-sheet scanning mode according to the embodiment. [Figure 13] 11A and 11B are diagrams illustrating an example of a flow of automatic change from a single-sheet reading mode to a continuous reading mode according to the embodiment. [Figure 14] FIG. 13 is a diagram illustrating an example of an operation when automatic mode change is not permitted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An example of a document transport device 1 according to an embodiment will be described below with reference to Figs. 1 to 14. In the following description, an example of a multifunction peripheral 100 equipped with a document transport device 1 will be described. However, each element such as the configuration and arrangement described in each embodiment does not limit the scope of the invention and is merely an explanatory example.

[0014] (Multifunction machine 100) An example of a multifunction peripheral 100 according to an embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing an example of a multifunction peripheral 100 according to an embodiment.

[0015] As shown in FIG. 1, the multifunction peripheral 100 includes a document transport device 1, a main control unit 2, a storage unit 3, an image reading device 4, an operation panel 5, and a printing unit 6.

[0016] The main control unit 2 controls the operation of the multifunction device 100. The main control unit 2 controls the operation of each unit of the multifunction device 100 for jobs such as copying and sending. The main control unit 2 is a board including a control circuit 20, an image data generating circuit 21, an image processing circuit 22, and a communication unit 23. The control circuit 20 is, for example, a CPU. The control circuit 20 performs processing and calculations related to jobs.

[0017] The image data generation circuit 21 generates read image data based on the analog image signal output by the image reading device 4 after reading an original. The image data generation circuit 21 includes, for example, an amplifier circuit, an offset circuit, and an A / D conversion circuit as circuits for processing the analog image signal. The A / D conversion circuit converts the analog image signal adjusted by the amplifier circuit and offset circuit into digital data (image data). The image processing circuit 22 performs image processing. The image processing circuit 22 processes the read image data and generates image data for printing or transmission. The image processing circuit 22 is, for example, an ASIC (an integrated circuit designed and developed for image processing).

[0018] The communication unit 23 includes a communication circuit and a communication memory. The communication unit 23 communicates with the computer 200 and the FAX machine 300. The computer 200 is, for example, a PC or a server. The operation panel 5 accepts the setting of the destination. The main control unit 2 causes the communication unit 23 to transmit image data based on the reading of the original to the set destination (scan transmission, FAX transmission). The communication unit 23 also receives printing data from the computer 200 and the FAX machine 300. The main control unit 2 causes the printing unit 6 to print based on the received printing data (print job, FAX reception printing).

[0019] The storage unit 3 includes multiple types of storage devices. For example, the storage unit 3 includes a RAM 31, a ROM 32, and a storage 33 (HDD or SSD) as storage devices. The main control unit 2 controls each unit based on the programs and data in the storage unit 3.

[0020] The operation panel 5 accepts settings made by the user. The operation panel 5 includes a display panel 51, a touch panel 52, and hard keys 53. The main control unit 2 causes messages and setting screens to be displayed on the display panel 51. The main control unit 2 also causes operation images to be displayed on the display panel 51. The operation images are, for example, buttons, keys, and tabs. Based on the output of the touch panel 52, the main control unit 2 recognizes the operation image that has been operated. The hard keys 53 include a start key and a numeric keypad. The touch panel 52 and the hard keys 53 accept setting operations made by the user (operations related to jobs). For example, the operation panel 5 accepts the selection of a document reading mode. Based on the output of the operation panel 5, the main control unit 2 recognizes the setting contents.

[0021] The printing unit 6 includes a paper feed unit 61, a paper transport unit 62, an image forming unit 63, and a fixing unit 64. The paper feed unit 61 includes a paper feed cassette and a pickup roller. The paper feed cassette stores paper. The pickup roller feeds paper. During a print job, the main control unit 2 causes paper to be supplied to the paper feed unit 61. The paper transport unit 62 includes a paper transport roller pair for transporting paper, and a paper transport motor. The paper transport roller pair transports the paper. The paper transport motor rotates the paper transport roller pair. The main control unit 2 causes the paper to be transported to the paper transport unit 62.

[0022] The image forming unit 63 includes, for example, a photosensitive drum, a charging device, an exposure device, a developing device, and a transfer roller. The main control unit 2 causes the image forming unit 63 to form a toner image based on image data. The main control unit 2 causes the image forming unit 63 to transfer the toner image to the transported paper. The fixing unit 64 includes a heater, a fixing rotor, and a fixing motor. The heater heats the fixing rotor. The fixing motor rotates the fixing rotor. The paper is transported while in contact with the fixing rotor. This causes the toner image to be fixed to the paper. The main control unit 2 causes the fixing unit 64 to fix the transferred toner image to the paper. The paper transport unit 62 ejects the printed paper outside the machine.

[0023] (Document feeder 1, image reader 4) The document conveying device 1 and the image reading device 4 according to the embodiment will be described with reference to Fig. 2. Fig. 2 and Fig. 3 are diagrams showing an example of the document conveying device 1 and the image reading device 4 according to the embodiment.

[0024] The image reading device 4 includes a contact glass 41 for transporting and reading and a document table 42 (contact glass for table reading). The contact glass 41 for transporting and reading and the document table 42 are arranged on the upper surface of the image reading device 4. When performing transporting and reading, the user sets one or more documents on the lift plate 8 (document tray 11). When a document is set on the document transport device 1 (lift plate 8), the main control unit 2 causes the image reading device 4 to perform transporting and reading. Transporting and reading is the reading of a document transported by the document transport device 1.

[0025] When no document is set on the lift plate 8 (document tray 11), the main control unit 2 causes the image reading device 4 to perform table reading. Table reading is the reading of a document set on the document table 42. When performing table reading, the user sets the document on one surface (the upper surface) of the document table 42.

[0026] The image reading device 4 includes a carriage 43, a moving belt 44, a first reading pulley 45, a second reading pulley 46, and a carriage motor 47 (see FIG. 3). The carriage 43 is a CIS type scanning unit. The image reading device 4 may include a CCD type reading unit.

[0027] The moving belt 44 is endless. The moving belt 44 is looped around each pulley. The moving belt 44 and the carriage 43 are connected. When moving the carriage 43, the main control unit 2 rotates the carriage motor 47. The carriage motor 47 rotates the first reading pulley 45 or the second reading pulley 46. This causes the moving belt 44 to rotate. The carriage motor 47 can rotate forward and reverse. In accordance with the rotation of the moving belt 44, the carriage 43 moves in the horizontal direction (the sub-scanning direction, a direction perpendicular to the main scanning direction, the left and right direction in Figure 2). The carriage 43 moves to the other side (lower side) of each contact glass.

[0028] The carriage 43 includes a light source 48, a lens, and an image sensor 49 (see FIG. 3). When reading an original, the main control unit 2 turns on the light source 48. The light source 48 irradiates light onto the original through the transport and reading contact glass 41 or the original table 42. The light source 48 is, for example, an LED. The lens guides the reflected light from the original to each light receiving element of the image sensor 49. The image sensor 49 reads the original placed on the original table 42 or the original transported over the transport and reading contact glass 41. The image sensor 49 is a line sensor. The image sensor 49 includes multiple light receiving elements (photoelectric conversion elements, pixels).

[0029] The light receiving elements receive light reflected by the document. Each light receiving element outputs an analog image signal according to the amount of light received (amount of reflected light). The analog image signal is input to the main control unit 2. The image data generating circuit 21 of the main control unit 2 generates read image data based on the input analog image signal.

[0030] During transport reading, the main control unit 2 moves the carriage 43 (the position of the reading line of the image sensor 49) below the transport reading contact glass 41. The carriage 43 reads the original passing over the transport reading contact glass 41. During table reading, the main control unit 2 moves the carriage 43 at a predetermined speed in the sub-scanning direction below the document table 42. During the movement, the carriage 43 reads the original set on the document table 42.

[0031] The document transport device 1 is provided above the image reading device 4. The document transport device 1 transports a document set toward the reading position (contact glass 41 for transport and reading). The document transport device 1 transports documents one sheet at a time. The document transport device 1 opens and closes in the vertical direction, with the back side of the paper surface in FIG. 2 as a fulcrum. The document transport device 1 also functions as a cover that holds down each contact glass of the image reading device 4 from above.

[0032] As shown in FIG. 2, the document transport device 1 includes, from the upstream side in the document transport direction, a document tray 11, a pickup roller 12, a separation transport section 7, a pair of registration rollers 13, multiple transport rollers 14a, 14b, and 14c, a pair of discharge rollers 14d, and a document discharge tray 15.

[0033] The document tray 11 is a portion where documents are set. The pickup roller 12 (corresponding to a paper feed rotating body), the rotating body included in the separation and transport section 7, the pair of registration rollers 13, the multiple transport rollers 14a, 14b, and 14c, and the pair of discharge rollers 14d are rotating bodies that transport the documents. The sent documents are finally discharged to the document discharge tray 15.

[0034] 3, the document transport device 1 includes a transport control unit 10 (corresponding to a control unit), a document set sensor 16, a paper feed motor 17, a document transport motor 18, a lift motor 81, and an upper limit detection sensor 82. The paper feed motor 17 and the document transport motor 18 are motors for rotating a rotating body that transports a document. The paper feed motor 17, the document transport motor 18, and the lift motor 81 can be, for example, a stepping motor.

[0035] The transport control unit 10 and the main control unit 2 are connected by a signal line and can communicate with each other. The transport control unit 10 is, for example, a board. For example, the transport control unit 10 includes a transport control circuit 10a (CPU), a memory 10b (RAM, ROM), and a motor control circuit 10c. The motor control circuit 10c is, for example, a motor driver IC. The motor control circuit 10c controls the rotation, stopping, and rotation speed of each motor in the document transport device 1.

[0036] The document tray 11 is provided with a restriction cursor pair 11a that restricts the document. The restriction cursor pair 11a can move in a direction perpendicular to the document transport direction. The restriction cursor pair 11a moves in tandem. The restriction cursor pair 11a slides and moves to sandwich the document between the restriction cursor pair 11a. This prevents the document from being misaligned in the direction perpendicular to the transport direction.

[0037] The downstream portion of the document tray 11 in the document transport direction serves as a lift plate 8. The lift plate 8 is a part of the document tray 11. Setting a document on the document tray 11 also means setting the document on the lift plate 8.

[0038] In the document tray 11, a document set sensor 16 is provided on the lift plate 8. The document set sensor 16 is, for example, an optical sensor. The document set sensor 16 has a different output level when a document is set and when no document is set. The output of the document set sensor 16 is input to the transport control unit 10 (transport control circuit 10a) described below. The transport control unit 10 (transport control circuit 10a) recognizes whether or not a document is set on the document tray 11 (lift plate 8). When the transport control unit 10 recognizes that a document has been set, it notifies the main control unit 2 of that fact. In addition, when the transport control unit 10 recognizes that the document has disappeared from the document tray 11, it also notifies the main control unit 2 of that fact.

[0039] When reading is performed with a document set on the document tray 11 (when transporting and reading), the main control unit 2 gives a document transport instruction to the transport control unit 10. Based on this instruction, the transport control unit 10 controls the operation of the document transport device 1.

[0040] A rotating shaft 80 is provided at the upstream end of the lift plate 8 in the document transport direction. The document transport device 1 includes a lift motor 81. The lift motor 81 is a motor for raising and lowering the lift plate 8. The lift motor 81 rotates the rotating shaft 80. In response to the rotation of the lift motor 81, the downstream end of the lift plate 8 in the document transport direction rises or falls. Alternatively, a lifting member may be provided below the lift plate 8. The lifting member includes a shaft and a lifting plate attached to the shaft. The shaft is rotatably supported. The axial direction of the shaft is perpendicular to the document transport direction. The lift motor 81 may rotate this shaft. When the lift motor 81 is rotated to one side, the shaft rotates in a direction in which the lifting plate lifts the lift plate 8 from below. When the lift motor 81 is rotated to the other side, the shaft rotates in a direction in which the lifting plate lowers the lift plate 8. In this manner, the lift plate 8 may be raised and lowered using the lifting member.

[0041] The upper limit detection sensor 82 detects when the lift plate 8 has risen to the upper limit position. of A sensor is provided on the pickup roller 12. The pickup roller 12 is provided above the lift plate 8. The pickup roller 12 is capable of swinging up and down. A support member 12a is provided to support the pickup roller 12 so that the pickup roller 12 can swing. For example, the support member 12a is hooked onto the rotation shaft of the second paper feed roller 72.

[0042] The upper limit detection sensor 82 is, for example, a transmissive optical sensor. When the lift plate 8 rises, the set document comes into contact with the pickup roller 12. As the lift plate 8 continues to rise, the pickup roller 12 is lifted up along with the document. When the pickup roller 12 is lifted up to its upper limit, a protrusion provided on the support member 12a blocks the light path of the upper limit detection sensor 82. The output level of the upper limit detection sensor 82 changes depending on whether or not the lift plate 8 (pickup roller 12) is at its upper limit position. The output of the upper limit detection sensor 82 is input to the transport control unit 10. Based on the output of the upper limit detection sensor 82, the transport control unit 10 recognizes whether or not the lift plate 8 (pickup roller 12) is at its upper limit position.

[0043] The separation and transport unit 7 includes a first paper feed roller 71, a second paper feed roller 72, a paper feed belt 73, and a retard roller 70. The paper feed belt 73 is wound around the first paper feed roller 71 and the second paper feed roller 72. The transport control unit 10 rotates the paper feed motor 17. This causes the first paper feed roller 71 to rotate, and the paper feed belt 73 to rotate. The paper feed belt 73 transports the document sent from the pickup roller 12 downstream in the document transport direction.

[0044] When the feed motor 17 is a stepping motor, the transport control unit 10 inputs pulses to the feed motor 17. The rotation angle of the feed motor 17 per pulse is fixed. Therefore, the pickup roller 12 feeds the document by a predetermined amount per pulse. The first feed roller 71, the second feed roller 72, and the feed belt 73 transport the document by a predetermined amount per pulse.

[0045] The retard roller 70 is provided below the paper feed belt 73. The retard roller 70 is in contact with the paper feed belt 73. The paper feed motor 17 also rotates the retard roller 70. The rotation direction of the retard roller 70 differs depending on the mode (details will be described later).

[0046] Along the document transport path 110, there are provided a pair of registration rollers 13, transport rollers 14a, 14b, 14c, and a pair of discharge rollers 14d. These transport the document. The document is finally discharged to a document discharge tray 15. A document transport motor 18 rotates the pair of registration rollers 13, the transport rollers 14a, 14b, 14c, and the pair of discharge rollers 14d. When transporting the document, the transport control unit 10 rotates the document transport motor 18.

[0047] The pair of resist rollers 13 is provided downstream of the paper feed belt 73 in the document transport direction. A feed sensor 19 is provided between the paper feed belt 73 (first paper feed roller 71, retard roller 70, pickup roller 12) and the pair of resist rollers 13. The feed sensor 19 is, for example, an optical sensor. The output level of the feed sensor 19 differs between when the document is detected and when the document is not detected.

[0048] The output of the feed sensor 19 is input to the transport control unit 10. Based on the output of the feed sensor 19, the transport control unit 10 recognizes that the leading edge of the document has reached the feed sensor 19 (the installation position of the feed sensor 19, the detection area of ​​the feed sensor 19), that the document is passing through, and that the trailing edge has passed the feed sensor 19.

[0049] Based on the output of the feed sensor 19, the transport control unit 10 may control the rotation of the pair of registration rollers 13. For example, the transport control unit 10 stops the pair of registration rollers 13 from when it recognizes that the leading edge of the document has reached the feed sensor 19 until a predetermined bending time has elapsed. The leading edge of the document hits the stopped pair of registration rollers 13. While the document remains stopped, the transport control unit 10 continues transport by the first feed roller 71 (feed belt 73) and the pickup roller 12. This causes the document to bend. Due to the elasticity of the bent document, the leading edge of the document follows the nip of the pair of registration rollers 13. This improves the skew of the document.

[0050] Further, a multi-feed detection sensor 111 is provided near the downstream side of the registration roller pair 13 in the document transport direction (between the registration roller pair 13 and transport roller 14a). The multi-feed detection sensor 111 is, for example, an ultrasonic sensor. The multi-feed detection sensor 111 includes a transmitter and a receiver. The transmitter and receiver are provided so as to sandwich the transported document in the upper and lower directions. The transmitter emits ultrasonic waves when the document is transported. When a multi-feed occurs, the level of the ultrasonic waves received by the receiver is lower than when only one document is transported. The output of the receiver is input to the transport control unit 10. The transport control unit 10 can determine whether a multi-feed has occurred based on the magnitude of the output of the receiver.

[0051] The pair of registration rollers 13, the transport rollers 14a, 14b, and 14c, and the pair of discharge rollers 14d transport the original along the original transport path 110. The original is finally discharged to the original discharge tray 15. The original transport motor 18 rotates the pair of registration rollers 13, the transport rollers 14a, 14b, and 14c, and the pair of discharge rollers 14d. When transporting the original, the transport control unit 10 rotates the original transport motor 18.

[0052] (Drive of each roller) Next, an example of driving of each roller in the document transport device 1 according to the embodiment will be described with reference to Fig. 4 to Fig. 6. Fig. 4 shows an example of a view of the inside of the document transport device 1 according to the embodiment as seen from above. Figs. 5 and 6 are diagrams showing an example of the transmission of drive of the paper feed motor 17 according to the embodiment.

[0053] An arrow D in FIG. 4 indicates the document transport direction. As shown in FIG. 4, the portion of pickup roller 12 that contacts the document and paper feed belt 73 are located approximately in the center in a direction perpendicular to document transport device 1. In FIG. 4, the portion of pickup roller 12 that contacts the document and paper feed belt 73 are almost invisible due to cover 74. In FIG. 4, first paper feed roller 71 includes a rotating shaft 71a that extends in a direction perpendicular to the document transport direction. Rotating shaft 71a is rotatably supported. Paper feed motor 17 rotates rotating shaft 71a.

[0054] A first pulley 71p is attached to the rotating shaft 71a. A second pulley 12p is attached to the pick-up roller 12. A linking belt 75 is stretched between these pulleys. When the rotating shaft 71a (first paper feed roller 71) rotates, the linking belt 75 rotates. The pick-up roller 12 also rotates in conjunction with the rotating shaft 71a.

[0055] In the document transport device 1, the paper feed motor 17 rotates the pickup roller 12, the first paper feed roller 71, the second paper feed roller 72, the paper feed belt 73, and the retard roller 70. The paper feed motor 17 can rotate in both a first direction (forward direction) and a second direction (reverse direction). In order to rotate the pickup roller 12, the first paper feed roller 71, the second paper feed roller 72, the paper feed belt 73, and the retard roller 70, the document transport device 1 includes a drive mechanism 9.

[0056] The drive mechanism 9 includes a first drive mechanism 9a, a second drive mechanism 9b, and a third drive mechanism 9c. The first drive mechanism 9a, the second drive mechanism 9b, and the third drive mechanism 9c transmit the drive force of the paper feed motor 17.

[0057] 5 and 6 are diagrams showing an example of gears included in each drive mechanism 9. In Figs. 5 and 6, the rectangle in the upper left corner indicates the paper feed motor 17. A motor gear is attached to the rotating shaft 17a of the paper feed motor 17. A transmission belt 90a is wound around the end of the basic gear 90 and the motor gear. When the motor gear (paper feed motor 17) rotates, the basic gear 90 rotates. In Figs. 5 and 6, the basic gear 90 is illustrated enlarged for convenience. A first drive mechanism 9a, a second drive mechanism 9b, and a third drive mechanism 9c are connected to the basic gear 90.

[0058] Specifically, the first driving mechanism 9a is a mechanism for rotating the first paper feed roller 71 and the pickup roller 12. The first driving mechanism 9a includes a first gear 91. The first gear 91 is attached to a rotation shaft 71a of the first paper feed roller 71. The first gear 91 meshes with a base gear 90. Therefore, when the paper feed motor 17 rotates, the first driving mechanism 9a rotates the first paper feed roller 71.

[0059] As described above, the first pulley 71p is provided on the rotating shaft 71a of the first paper feed roller 71. The second pulley 12p is provided on the rotating shaft 12a of the pick-up roller 12. The pick-up roller 12 rotates together with the first paper feed roller 71 due to the interlocking belt 75 wound around the first pulley 71p and the second pulley 12p.

[0060] The second drive mechanism 9b is also a mechanism for rotating the first paper feed roller 71 and the pickup roller 12. The second drive mechanism 9b includes a second gear 92 and a third gear 93. The second gear 92 meshes with the base gear 90. The third gear 93 meshes with the second gear 92. The third gear 93 is attached to the rotation shaft 71a of the first paper feed roller 71. When the paper feed motor 17 rotates, the second drive mechanism 9b rotates the first paper feed roller 71.

[0061] Further, the third drive mechanism 9c is a mechanism for rotating the retard roller 70. The third drive mechanism 9c includes a fourth gear 94, a fifth gear 95, and a sixth gear 96. The base gear 90 meshes with the fourth gear 94. The fourth gear 94 meshes with the fifth gear 95. The fifth gear 95 meshes with the sixth gear 96. The sixth gear 96 is attached to the rotation shaft 70a of the retard roller 70. When the paper feed motor 17 rotates, the third drive mechanism 9c rotates the retard roller 70.

[0062] The first drive mechanism 9a and the second drive mechanism 9b are both mechanisms for rotating the first feed roller 71 and the pickup roller 12 in a direction that sends the document in the document transport direction. The third drive mechanism 9c is a mechanism that switches the rotation direction of the retard roller 70 in accordance with the rotation direction of the feed motor 17.

[0063] 1. When rotating the feed motor 17 in the forward direction An example of the transmission of drive when the feed motor 17 is rotated in the first direction (forward direction) will be described with reference to Fig. 5. In Fig. 5, the left side indicates the document transport direction. The lower side of Fig. 5 corresponds to the front side of the document transport device 1, and the upper side corresponds to the rear side of the document transport device 1.

[0064] 5, the first direction is the counterclockwise direction (CCW). When the paper feed motor 17 is rotated in the first direction, the base gear 90 also rotates in the counterclockwise direction (CCW).

[0065] When the basic gear 90 rotates counterclockwise (CCW), the first gear 91 of the first drive mechanism 9a rotates clockwise (CW). As a result, the first paper feed roller 71 and the pickup roller 12 also rotate clockwise (CW). The clockwise direction is the direction in which the first paper feed roller 71, the second paper feed roller 72, the paper feed belt 73, and the pickup roller 12 rotate so as to feed the document toward the downstream side in the document transport direction. In this case, the first gear 91 rotates the rotation shaft 71a of the first paper feed roller 71 in the clockwise (CW) direction.

[0066] When the basic gear 90 rotates in the counterclockwise direction (CCW), the second gear 92 of the second drive mechanism 9b rotates in the clockwise direction (CW). The third gear 93 of the second drive mechanism 9b, which meshes with the second gear 92, rotates in the counterclockwise direction (CW). The third gear 93 tries to rotate the rotation shaft 71a of the first paper feed roller 71 in the counterclockwise direction (CCW).

[0067] Here, the third gear 93 incorporates a first one-way clutch 97. When the third gear 93 tries to rotate in the counterclockwise (CCW) direction, the first one-way clutch 97 does not transmit torque to the rotating shaft 71a. When the paper feed motor 17 is rotated in the first direction (forward direction), the transmission of the driving force in the second driving mechanism 9b is cut off by the first one-way clutch 97.

[0068] When the basic gear 90 rotates in the counterclockwise direction (CCW), the fourth gear 94 of the third drive mechanism 9c rotates in the clockwise direction (CW). The fifth gear 95 of the third drive mechanism 9c, which meshes with the fourth gear 94, rotates in the counterclockwise direction (CCW). The sixth gear 96 of the third drive mechanism 9c, which meshes with the fifth gear 95, rotates in the clockwise direction (CW). The sixth gear 96 rotates the rotation shaft 70a of the retard roller 70 in the clockwise direction (CW).

[0069] The retard roller 70 faces the paper feed belt 73 (see FIG. 2). Therefore, in this case, the retard roller 70 rotates so as to send the document back in the opposite direction (upstream) to the document transport direction. In other words, when the paper feed motor 17 is rotated in the first direction, the third drive mechanism 9c rotates the retard roller 70 in a direction that sends the document upstream in the document transport direction.

[0070] 2. When rotating the feed motor 17 in the reverse direction An example of the transmission of drive when the feed motor 17 is rotated in the second direction (reverse direction) will be described with reference to Fig. 6. In Fig. 6, the left direction indicates the document transport direction. The lower side of Fig. 5 corresponds to the front side of the document transport device 1, and the upper side corresponds to the rear side of the document transport device 1.

[0071] 6, the second direction is a clockwise direction (CW). When the feed motor 17 is rotated in the second direction, the basic gear 90 also rotates in a clockwise direction (CW). When the basic gear 90 rotates in a clockwise direction (CW), the first gear 91 of the first drive mechanism 9a rotates in a counterclockwise direction (CCW). The first gear 91 tries to rotate the rotation shaft 71a of the first feed roller 71 in a counterclockwise direction (CCW).

[0072] Here, the first gear 91 incorporates a second one-way clutch 98. When the first gear 91 (the rotating shaft 71a of the first paper feed roller 71) tries to rotate in the counterclockwise (CCW) direction, the second one-way clutch 98 does not transmit torque to the rotating shaft 71a. When the paper feed motor 17 is rotated in the second direction (reverse direction), the transmission of the driving force in the first drive mechanism 9a is cut off by the second one-way clutch 98.

[0073] When the basic gear 90 rotates in the clockwise direction (CW), the second gear 92 of the second drive mechanism 9b rotates in the counterclockwise direction (CCW). The third gear 93 of the second drive mechanism 9b, which meshes with the second gear 92, rotates in the clockwise direction (CW). The third gear 93 tries to rotate the rotating shaft 71a of the first paper feed roller 71 in the clockwise direction (CW). In this case, the first one-way clutch 97 of the third gear 93 transmits torque to the rotating shaft 71a. When the paper feed motor 17 is rotated in the second direction (reverse direction), the third gear 93 of the second drive mechanism 9b rotates the rotating shaft 71a of the first paper feed roller 71 in the clockwise direction (CW).

[0074] As a result, the first feed roller 71 and the pickup roller 12 also rotate in a clockwise direction (CW). The clockwise direction is the direction in which the first feed roller 71, the second feed roller 72, the feed belt 73, and the pickup roller 12 rotate to feed the document in the document transport direction.

[0075] When the basic gear 90 rotates in the clockwise direction (CW), the fourth gear 94 of the third drive mechanism 9c rotates in the counterclockwise direction (CCW). The fifth gear 95 of the third drive mechanism 9c, which meshes with the fourth gear 94, rotates in the clockwise direction (CW). The sixth gear 96 of the third drive mechanism 9c, which meshes with the fifth gear 95, rotates in the counterclockwise direction (CCW). The sixth gear 96 rotates the rotation shaft 80 of the retard roller 70 in the counterclockwise direction (CCW).

[0076] The retard roller 70 faces the paper feed belt 73 (see FIG. 2). The counterclockwise direction is the direction in which the retard roller 70 rotates in the direction in which the document is fed in the document transport direction. In other words, when the paper feed motor 17 is rotated in the second direction, the retard roller 70 rotates in the direction in which the document is fed in the document transport direction.

[0077] The directions in which the feed motor 17 feeds the document are as follows. (1) When the feed motor 17 rotates in the first direction (forward direction) Pickup roller 12, first paper feed roller 71, second paper feed roller 72, paper feed belt 73 → rotate in a direction to feed the document in the document transport direction (downstream direction) Retard roller 70 -> Rotates in a direction to return the document to the upstream direction (opposite the document transport direction) in the document transport direction. (2) When the feed motor 17 rotates in the second direction (reverse direction) Pickup roller 12, first paper feed roller 71, second paper feed roller 72, paper feed belt 73 → rotate in a direction to feed the document in the document transport direction (downstream direction) Retard roller 70: Rotates in a direction to feed the document downstream in the document transport direction.

[0078] In this manner, in the document transport device 1, the pickup roller 12, the first paper feed roller 71, the second paper feed roller 72, and the paper feed belt 73 rotate in a direction to feed the document downstream in the document transport direction, regardless of the rotation direction of the paper feed motor 17. The rotation direction of the retard roller 70 changes depending on the rotation direction of the paper feed motor 17.

[0079] (Select the reading mode) Next, an overview of the selection of the reading mode will be described. In the multifunction device 100 (original transport device 1), either a normal mode or a manual feed mode can be selected as the mode used when transporting and reading an original (transport and read). For example, the mode can be selected on the operation panel 5.

[0080] The normal mode is a mode in which the retard roller 70 is rotated in a direction (return direction) that sends the document in the opposite direction to the document transport direction. In other words, the normal mode is a mode in which the document is transported while separating (sorting) overlapping documents. The manual feed mode is a mode in which the retard roller 70 is rotated in a direction that sends the document downstream in the document transport direction (direction that sends the document in the document transport direction). The manual feed mode is a mode in which the document is transported without sorting the document.

[0081] There is one document consisting of multiple overlapping sheets. For example, a slip for Takkyubin (registered trademark) has a carbon paper for transfer attached to a backing paper. There are also cases where a document with a peelable paper such as a sticky note attached needs to be read. The retard roller 70 separates the overlapping documents by friction between its surface and the document. When a document with a slip or sticky note attached is rubbed with the retard roller 70, a force is applied to the document. As a result, the attached sheet (paper) may peel off. Also, there are cases where it is preferable not to rub a document with a perforation for cutting with the retard roller 70. If the user does not want the retard roller 70 to separate the documents, the user can use the manual feed mode.

[0082] (Transport reading in normal mode) Next, an example of the flow of conveying and reading in the normal mode according to the embodiment will be described with reference to Fig. 7. Fig. 7 is a diagram showing an example of the flow of conveying and reading in the normal mode according to the embodiment.

[0083] The start in Fig. 7 is the point at which the operation panel 5 accepts the selection of normal mode and also accepts an instruction to start a job involving reading. For example, the operation panel 5 accepts the operation of the start button as a start instruction. Jobs such as copy and scan transmission are jobs involving reading. Since this is a transport and reading job, the user sets the document in the document tray 11 before issuing an instruction to start. Based on the output of the document set sensor 16, the transport control unit 10 and the main control unit 2 recognize that the document has been set.

[0084] First, the main control unit 2 instructs the transport control unit 10 to start transport and reading in normal mode (Step #11). In response to this instruction, the transport control unit 10 causes the lift motor 81 to raise the lift plate 8 to its upper limit (Step #12). After the lift plate 8 starts to rise, when it recognizes that the lift plate 8 (pickup roller 12) has reached its upper limit based on the output of the upper limit detection sensor 82, the transport control unit 10 stops the lift motor 81.

[0085] The document transport device 1 includes a lower limit detection sensor 112 that detects when the lift plate 8 is at the lower limit. For example, the lower limit detection sensor 112 is a switch that contacts the bottom surface of the lift plate 8. The output of the lower limit detection sensor 112 is input to the transport control unit 10. Based on the output of the lower limit detection sensor 112, the transport control unit 10 recognizes that the lift plate 8 has been lowered to the lower limit. Before the start of a job, the transport control unit 10 lowers the lift plate 8 to the lower limit. For example, when the transport control unit 10 recognizes that the lift plate 8 is not at the lower limit and that no documents are set, the transport control unit 10 rotates the lift motor 81 to lower the lift plate 8 to the lower limit.

[0086] After the lift plate 8 starts to rise, the transport control unit 10 starts rotating the feed motor 17 in the first direction (forward direction) (step #13). This causes the pickup roller 12, the first feed roller 71, the second feed roller 72, and the feed belt 73 to rotate in a direction that feeds the document in the document transport direction. The document feed starts. The retard roller 70 rotates in a direction that sends the document back in the opposite direction to the document transport direction.

[0087] The retard roller 70 has a built-in torque limiter. When only one document is fed, the rotation load exceeds the torque set by the torque limiter. As a result, the retard roller 70 is driven by the paper feed belt 73. In other words, the rotation direction of the retard roller 70 is the direction that feeds the document in the document transport direction.

[0088] Based on the output of the feed sensor 19, the transport control unit 10 recognizes that the leading edge of the document has reached the feed sensor 19 (step #14). Then, the transport control unit 10 starts measuring the passing time T9 (step #15). Specifically, the passing time T9 is the time from when it is recognized that the leading edge of the document has reached the feed sensor 19 to when it is recognized that the trailing edge of the document has passed through the feed sensor 19.

[0089] The transport control unit 10 checks whether the rear end of the document has passed through the feed sensor 19 (Step #16). If the rear end has not passed through (No in Step #16), the transport control unit 10 checks whether the measured passing time T9 has exceeded a predetermined allowable time (Step #17). The allowable time is predetermined according to the document size. The allowable time is a time for determining whether a continuous feed error has occurred.

[0090] The allowable time is the time obtained by dividing the length of one document in the transport direction by the ideal (specified) document transport speed, plus a specified margin. When continuous feeding occurs, the trailing edge of the previous document and the leading edge of the next document are transported overlapping each other. In this case, the feed sensor 19 cannot detect the passage of the previous document, even if it has passed.

[0091] The operation panel 5 accepts the setting of the size of the original document. Based on this setting, the transport control unit 10 may recognize the length of one original document in the transport direction. Also, an original size sensor for detecting the length of the original document in the transport direction may be provided in the original tray 11. In this case, the transport control unit 10 recognizes the length of the original document in the transport direction based on the output of the original size sensor.

[0092] If the allowable time has not been exceeded (No in step #17), the transport control unit 10 executes step #16 (return to step #16). If the allowable time has been exceeded (Yes in step #17), the transport control unit 10 determines that a continuous feed error has occurred (step #18). If the time until the trailing end passage detection is too long, the transport control unit 10 determines that a continuous feed error has occurred. Then, the transport control unit 10 stops all transport of the original (step #19). In other words, the transport control unit 10 stops all motors for transporting the original in the original transport device 1. Then, the transport control unit 10 causes the display panel 51 to display a message indicating the occurrence of a continuous feed error (step #110). After that, the transport control unit 10 ends this flow chart (END). If the user wants to start over, he or she starts over from setting the original.

[0093] On the other hand, when the passage of the rear end is recognized (Yes in step #16), the conveyance control unit 10 stops the paper feed motor 17 (step #111). That is, the pickup roller 12, the first paper feed roller 71, the second paper feed roller 72, the paper feed belt 73, and the retard roller 70 are stopped.

[0094] The transport control unit 10 transports the document that has passed the feed sensor 19 to the discharge tray. The image reading device 4 reads the transported document. Then, the transport control unit 10 checks whether or not there is a document remaining on the document tray 11 (lift plate 8) (Step #112). If there is not (No in Step #112), the transport control unit 10 ends this flowchart (END). If there is, the transport control unit 10 starts Step #13 after a predetermined inter-paper time has elapsed (return to Step #13).

[0095] (Single sheet reading mode) Next, an example of the flow of conveying and reading in the single-sheet reading mode of the manual feed mode according to the embodiment will be described with reference to Fig. 8. Fig. 8 is a diagram showing an example of the flow of conveying and reading in the single-sheet reading mode according to the embodiment.

[0096] In the multifunction device 100 (original transport device 1), two manual feed modes can be used. One of the manual feed modes is a single-sheet reading mode. The other is a continuous reading mode. The single-sheet reading mode is a mode for reading originals one sheet at a time. The continuous reading mode is a mode for continuously and automatically reading multiple sheets of originals in the manual feed mode.

[0097] In the following, an example of the flow of conveying and reading in the single-sheet reading mode will be described with reference to Fig. 8. After the explanation of the single-sheet reading mode, an example of the flow of conveying and reading in the continuous reading mode will be described.

[0098] The start of Fig. 8 is the point in time when the operation panel 5 receives an instruction to start a job involving reading, with the single sheet reading mode selected. For example, the operation panel 5 receives the operation of the start button as the start instruction. Before giving the start instruction, the user sets the document in the document tray 11. Multiple documents may be set in the document tray 11. Based on the output of the document set sensor 16, the transport control unit 10 and the main control unit 2 recognize that the document has been set.

[0099] First, when starting transport and reading in the single sheet reading mode of the manual feed mode, the transport control unit 10 causes the lift motor 81 to raise the lift plate 8 to the upper limit (step #21). This is the same as in the normal mode. After the lift plate 8 starts to rise, the transport control unit 10 starts rotating the feed motor 17 in the second direction (reverse direction) (step #22). This causes the pickup roller 12, the first feed roller 71, the second feed roller 72, and the feed belt 73 to rotate in a direction that sends the document downstream in the document transport direction. The retard roller 70 also rotates in a direction that sends the document downstream in the document transport direction.

[0100] In the manual feed mode, the transport control unit 10 slows the transport speed of the document compared to the normal mode (both in the single sheet reading mode and the continuous reading mode). For example, the transport control unit 10 sets the transport speed in the manual feed mode to about half the transport speed in the normal mode. The transport control unit 10 may change the rotation speed of the paper feed motor 17 between the normal mode and the manual feed mode.

[0101] The conveyance control unit 10 may rotate the sheet feed motor 17 at the same speed in the manual feed mode and the normal mode. In this case, the number of teeth of the gear included in the first driving mechanism 9a and the number of teeth of the gear included in the second driving mechanism 9b are set so that the conveyance speed in the manual feed mode is approximately half the conveyance speed in the normal mode.

[0102] Based on the output of the feed sensor 19, the transport control unit 10 recognizes that the leading edge of the document has reached the feed sensor 19 (Step #23). Then, the transport control unit 10 controls the lift motor 81 to lower the lift plate 8 by a predetermined lowering amount (Step #24).

[0103] That is, while pickup roller 12 is feeding the document, transport control unit 10 causes lift motor 81 to start lowering lift plate 8. After the descent starts, pickup roller 12 and the document are no longer in contact. Furthermore, even if pickup roller 12 does not stop immediately after the fed document passes pickup roller 12, the next document is not sent out. That is, even if retard roller 70 feeds the document in the document transport direction, continuous feeding errors are less likely to occur.

[0104] After the feed motor 17 (pickup roller 12) starts rotating, the transport control unit 10 may start lowering the lift plate 8 before the feed sensor 19 recognizes that the leading edge of the document has arrived. If the nip between the retard roller 70 and the feed belt 73 grips the document, the document is transported even if the pickup roller 12 does not come into contact with the document. Therefore, the transport control unit 10 may cause the lift motor 81 to start lowering the lift plate 8 after a predetermined waiting time has elapsed since the pickup roller 12 started rotating. In this case, the waiting time is a time obtained by dividing the distance from the pickup roller 12 (the part of the pickup roller 12 that contacts the document) to the retard roller 70 (the nip between the retard roller 70 and the feed belt 73) by the ideal transport speed of the document.

[0105] Further, the feed motor 17 rotates the pickup roller 12. A stepping motor can be used for the feed motor 17. When a stepping motor is used, the rotation amount of the feed motor 17 and the pickup roller 12 per pulse is fixed. Therefore, the transport control unit 10 may input a predetermined number of descent start pulses from the start of rotation of the pickup roller 12 to the feed motor 17, and cause the lift motor 81 to start lowering the lift plate 8. In this case, the number of descent start pulses is a value obtained by dividing the distance from the pickup roller to the retard roller by the amount of movement of the document per pulse. If the obtained value is not an integer, the value after the decimal point may be rounded up.

[0106] The amount of movement of the document per pulse is determined in advance. The amount of movement of the document per pulse may be the amount of movement of the circumferential surface of pickup roller 12 when one pulse is input to paper feed motor 17. Taking some slip into consideration, the amount of movement of the document per pulse may be a value obtained by subtracting a margin from the amount of movement of the circumferential surface of pickup roller 12 when one pulse is input to paper feed motor 17.

[0107] When the lift plate 8 has been lowered by a predetermined amount, the transport control unit 10 stops the lift motor 81. The predetermined amount of lowering can be, for example, a length within a range of 10 mm to 20 mm. For example, the amount of lowering can be about 15 mm. For example, when the lift motor 81 is a stepping motor, the transport control unit 10 inputs a predetermined number of pulses to the lift motor 81. The predetermined number of pulses is the number of pulses that lowers the lift plate 8 by a predetermined amount of lowering. The amount of lowering is the amount of change in height of the end edge of the upper surface of the lift plate 8 that is downstream in the transport direction of the document.

[0108] The amount of lowering can be set so that the distance from the lower end of the circumferential surface of the pick-up roller 12 to the document one document below the topmost document is equal to or greater than a predetermined separation distance. In other words, the document is firmly separated from the lower end of the circumferential surface of the pick-up roller 12. The amount of lowering is set to a value that prevents the document on the lift plate 8 from falling below a predetermined lower limit height. The document is prevented from sagging too much.

[0109] Furthermore, when it is recognized that the leading edge of the document has reached the feed sensor 19, the transport control unit 10 starts measuring the passage time T9 (step #25). The passage time T9 is the time from when it is recognized that the leading edge of the document has reached the feed sensor 19 to when it is recognized that the trailing edge of the document has passed through the feed sensor 19.

[0110] The transport control unit 10 checks whether the rear end of the document has passed through the feed sensor 19 (Step #26). If it has not passed through (No in Step #26), the transport control unit 10 checks whether the measured required passage time T9 has exceeded the allowable time (Step #27). However, since the transport speed is about half, the allowable time in the manual feed mode is about twice as long as in the normal mode.

[0111] If the allowable time has not been exceeded (No in step #27), the transport control unit 10 executes step #26 (return to step #26). If the allowable time has been exceeded (Yes in step #27), the transport control unit 10 determines that a continuous feed error has occurred (step #28). If the detection of the passage of the rear end is delayed, the transport control unit 10 determines that a continuous feed error has occurred. Then, the transport control unit 10 stops all transport of the originals (step #29). In other words, the transport control unit 10 stops all motors for transporting originals in the original transport device 1. Then, the transport control unit 10 causes the display panel 51 to display a message indicating the occurrence of a continuous feed error (step #210). After that, the transport control unit 10 ends this flow chart (END). If the user wants to start over, he or she starts over from setting the originals.

[0112] On the other hand, if the passage of the rear end is recognized (Yes in step #26), the transport control unit 10 stops the paper feed motor 17 (step #211). That is, the pickup roller 12, the first paper feed roller 71, the second paper feed roller 72, the paper feed belt 73, and the retard roller 70 are stopped. The transport control unit 10 transports the document that has passed the feed sensor 19 to the discharge tray. The image reading device 4 reads the transported document. Then, the transport control unit 10 ends this flowchart (END).

[0113] The single-sheet reading mode is a mode that takes into consideration the fact that a job start is instructed (the start button is operated) for each sheet of document, and the documents are read one by one. Note that multiple sheets of documents may be set in the document tray 11 even in the single-sheet reading mode. If the user wishes to continue reading in the single-sheet reading mode, the user instructs to start the job again. This restarts the flow chart in FIG. 8.

[0114] (Continuous read mode operation flow) Next, an example of the flow of conveying and reading in the continuous reading mode according to the embodiment will be described with reference to Fig. 9. Fig. 9 is a diagram showing an example of the flow of conveying and reading in the continuous reading mode according to the embodiment.

[0115] The start of Fig. 9 is the point at which the operation panel 5 receives an instruction to start a job involving reading (operation of the start button) with the continuous reading mode selected. The user sets the document in the document tray 11 before issuing the start instruction. In the continuous reading mode, multiple documents are set. Based on the output of the document set sensor 16, the transport control unit 10 and the main control unit 2 recognize the document set.

[0116] First, when starting conveyance and reading in the continuous reading mode of the manual insertion mode, the conveyance control unit 10 causes the lift motor 81 to raise the lift plate 8 to the upper limit (step #31). This is the same as in the normal mode and the single sheet reading mode.

[0117] Steps #32 to #311 in the continuous reading mode (FIG. 9) are similar to steps #22 to #211 in the single sheet reading mode (FIG. 8). Therefore, for steps #32 to #311, the description of steps #22 to #211 will be used and a description thereof will be omitted.

[0118] When the passage of the rear end of the document through the feed sensor 19 is recognized (Yes in step #36) and the feed motor 17 is stopped (step #311), the transport control unit 10 checks whether or not there is a document set on the lift plate 8 (document tray 11) (step #312). Specifically, the transport control unit 10 checks the output of the document set sensor 16.

[0119] If there is no set document (No in step #312), the transport control unit 10 ends this flowchart (END). If there is a set document (Yes in step #312), the transport control unit 10 executes step #31 (return to step #31).

[0120] That is, the transport control unit 10 re-raises the lift plate 8 that was lowered by the descent amount. The transport control unit 10 rotates the lift motor 81. The transport control unit 10 re-raises the lift plate 8 until the topmost document comes into contact with the pickup roller 12 (pickup roller 12 and lift plate 8 up to the upper limit). After re-raising, the transport control unit 10 performs step #32 and starts feeding. That is, the transport control unit 10 rotates the pickup roller 12, the first paper feed roller 71, the second paper feed roller 72, the paper feed belt 73, and the retard roller 70. The transport control unit 10 rotates these rotating bodies in a direction that sends the document in the document transport direction.

[0121] (Manual feed mode operation) Next, an example of operation in the manual insertion mode according to the embodiment will be described with reference to Fig. 10. Fig. 10 is a timing chart showing an example of operation in the manual insertion mode according to the embodiment.

[0122] Among the timing charts in Fig. 10, the top chart is a chart showing the operation of lift motor 81. The middle chart is a chart showing the operation of paper feed motor 17. The bottom chart is a diagram showing an example of the output level of feed sensor 19. In the example of Fig. 10, feed sensor 19 outputs a high level when it detects a document, and outputs a low level when it does not detect a document.

[0123] Time point T1 in Fig. 10 is the time point when the lift plate 8 starts to rise. The transport control unit 10 rotates the lift motor 81 in the direction in which the lift plate 8 rises. The transport control unit 10 accelerates the lift motor 81 and rotates it at a predetermined speed. Time point T2 is the time point when the transport control unit 10 recognizes that the lift plate 8 has reached its upper limit. The transport control unit 10 starts to stop the lift motor 81.

[0124] Time point T3 is the time point when the conveyance control unit 10 starts rotating the paper feed motor 17. The conveyance control unit 10 rotates the paper feed motor 17 in the second direction (reverse direction). Therefore, in FIG. 10, the state in which the paper feed motor 17 rotates is illustrated at a low level.

[0125] Time point T4 is the time point when the transport control unit 10 recognizes that the leading edge of the document has reached the feed sensor 19 based on the output of the feed sensor 19. At this time, the transport control unit 10 rotates the lift motor 81. The transport control unit 10 rotates the lift motor 81 in the direction in which the lift plate 8 moves down.

[0126] Time T5 is the time when the conveyance control unit 10 has completed stopping the rotation of the lift motor 81. This descent causes the lift plate 8 to descend by a predetermined amount. Time T6 is the time when the conveyance control unit 10 temporarily stops the rotation of the paper feed motor 17. After it is recognized that the leading edge of the document has reached the feed sensor 19, the conveyance control unit 10 continues to rotate the paper feed motor 17. As the paper feed motor 17 continues to rotate, the leading edge of the document strikes the registration roller pair 13, which is in a stopped state, and the document is bent. Excessive bending is also undesirable. Therefore, after it is recognized that the leading edge of the document has reached the feed sensor 19, the conveyance control unit 10 stops the paper feed motor 17 at time T6, when the bending creation time has elapsed.

[0127] Time T7 is the time when the conveyance control unit 10 resumes the rotation of the paper feed motor 17. At this time, the conveyance control unit 10 also rotates the paper feed motor 17 in the second direction. At time T7, the conveyance control unit 10 also starts the rotation of the registration roller pair 13.

[0128] Time T8 is the time when feed sensor 19 detects the passage of the rear end of the document. Based on the output of feed sensor 19, transport control unit 10 recognizes that the rear end of the document has passed feed sensor 19. Based on this recognition, transport control unit 10 stops paper feed motor 17.

[0129] (Select Mode) Next, an example of the mode selection screen 54 according to the embodiment will be described with reference to Fig. 11. Fig. 11 is a diagram showing an example of the mode selection screen 54 according to the embodiment.

[0130] A user can select which mode to use from among the normal mode, the single-sheet reading mode, and the continuous reading mode. Fig. 11 shows an example of a mode selection screen 54 related to reading. When the operation panel 5 accepts an operation to display the mode selection screen 54, the control unit causes the mode selection screen 54 to be displayed on the display panel 51. The user selects a mode before starting a job to read a document.

[0131] When an instruction to start execution of a job is given without selecting a mode, the main control unit 2 instructs the transport control unit 10 to transport and read in the default mode. Based on this instruction, the transport control unit 10 feeds and transports the document in the default mode. The default mode is determined in advance. The operation panel 5 may accept the selection of the default mode. For example, the normal mode is set as the default mode.

[0132] The mode selection screen 54 is provided with a normal mode selection button B1, a single sheet reading mode selection button B2, a continuous reading mode selection button B3, and an automatic change permission check box C1.

[0133] When a user wishes to transport a document in normal mode, the user operates the normal mode selection button B1. When a user wishes to transport a document in single-sheet reading mode, the user operates the single-sheet reading mode selection button B2. When a user wishes to transport a document in continuous reading mode, the user operates the continuous reading mode selection button B3. Based on the output of the operation panel 5, the main control unit 2 recognizes the selected mode. When starting to read the document, the main control unit 2 notifies the transport control unit 10 of the selected mode.

[0134] In this manner, the operation panel 5 accepts the selection of whether to use the normal mode or the manual feed mode. The transport control unit 10 causes the document to be read in the selected mode.

[0135] The automatic change permission checkbox C1 is a checkbox for selecting whether or not to permit automatic mode changing during manual feed mode. If automatic change is permitted, the user operates the automatic change permission checkbox C1 to check it. If automatic change is not permitted, the user operates the automatic change permission checkbox C1 to uncheck it. Based on the output of the operation panel 5, the main control unit 2 recognizes whether or not the checkbox is checked.

[0136] When starting to read an original, the main control unit 2 notifies the transport control unit 10 of whether or not to automatically change the mode. If a notification is received that the automatic change is permitted, the transport control unit 10 automatically changes (selects) the mode when the transport reading and manual feed mode are selected. If a notification is received that the automatic change is not permitted, the transport control unit 10 maintains the mode selected on the mode selection screen 54.

[0137] When the normal mode is selected (when the normal mode selection button B1 is operated) and multiple documents are set on the lift plate 8, the transport control unit 10 rotates the retard roller 70 in a direction that sends the documents, for all documents, in the opposite direction to the transport direction of the documents.

[0138] (Automatic change from continuous scanning mode to single scanning mode) Next, an example of a flow of automatic change from the continuous reading mode to the single sheet reading mode according to the embodiment will be described with reference to Fig. 12. Fig. 12 is a diagram showing an example of a flow of automatic change from the continuous reading mode to the single sheet reading mode according to the embodiment.

[0139] There are two cases when the start in FIG. 12 occurs. The first is when feeding and reading begins in continuous reading mode in manual feed mode with automatic change permitted. In other words, it is when feeding of the first document begins in continuous reading mode with automatic change permitted. The second is when feeding of the first document begins after automatic change (automatic selection) to continuous reading mode is made by automatic change.

[0140] The transport control unit 10 checks whether or not there is a document (remains) on the lift plate 8 (Step #41). When there is no document remaining on the lift plate 8 (No in Step #41), the transport control unit 10 ends the process of this flowchart (END).

[0141] Next, the transport control unit 10 checks whether a continuous feed error has occurred in the document being fed (step #42). In other words, the transport control unit 10 checks whether the trailing edge of the document currently being fed has passed the feed sensor 19 within the allowable time.

[0142] If no continuous feeding error has occurred (No in step #42), the transport control unit 10 maintains the continuous reading mode (step #43). Then, the transport control unit 10 automatically starts feeding the next document in the continuous reading mode (step #44). Specifically, the transport control unit 10 automatically lifts the lift plate 8 and restarts the rotation of the feed motor 17. Then, the transport control unit 10 executes step #41 (return to step #41).

[0143] If a continuous feeding error occurs (Yes in step #42), feeding documents in the continuous reading mode may not be desirable. Therefore, the transport control unit 10 automatically changes the mode to the single-sheet reading mode (automatically selects the single-sheet reading mode) (step #45). Since the single-sheet reading mode has been automatically selected, the transport control unit 10 ends the processing of this flowchart, which is based on the continuous reading mode (END).

[0144] (Automatic change to continuous scanning mode from single sheet scanning mode) Next, an example of a flow of automatic change from the single sheet reading mode to the continuous reading mode according to the embodiment will be described with reference to Fig. 13. Fig. 13 is a diagram showing an example of a flow of automatic change from the single sheet reading mode to the continuous reading mode according to the embodiment.

[0145] There are two cases where the start of Fig. 13 occurs. The first is when automatic mode change is permitted and transport and reading in single sheet reading mode in manual feed mode begins. In other words, it is when document feeding begins in single sheet reading mode with automatic change permitted. The second is when document feeding begins after automatic change to single sheet reading mode has been made by automatic change.

[0146] The transport control unit 10 checks whether or not there is a document (remains) on the lift plate 8 (Step #51). When there is no document remaining on the lift plate 8 (No in Step #51), the transport control unit 10 ends the process of this flowchart (END).

[0147] Next, the transport control unit 10 checks whether a continuous feed error has occurred in the document being fed (step #52). In other words, the transport control unit 10 checks whether the trailing edge of the document currently being fed has passed the feed sensor 19 within the allowable time.

[0148] If a continuous feeding error occurs (Yes in step #52), feeding of documents in the continuous reading mode may not be desirable, so the conveyance control unit 10 maintains the single sheet reading mode (step #53).

[0149] After the continuous feeding error has been resolved, when the operation panel 5 receives a command to start reading, the transport control unit 10 starts feeding the next document in single-sheet reading mode (step #54). Specifically, when the start button is operated, the transport control unit 10 lifts the lift plate 8 and starts rotating the feed motor 17. Then, the transport control unit 10 executes step #51 (return to step #51).

[0150] If no consecutive feeding error has occurred (No in step #52), the transport control unit 10 adds 1 to the number of successful feeding attempts (step #55). The number of successful feeding attempts is stored in, for example, the RAM 31 of the transport control unit 10. When there are no documents on the lift plate 8 or when a predetermined reset time has elapsed since the previous feeding of a document, the transport control unit 10 resets the number of successful feeding attempts (sets it to zero).

[0151] The transport control unit 10 checks whether the number of successful paper feeds has reached a predetermined number (step #56). In other words, in a state where multiple originals are set in the single-sheet reading mode, the transport control unit 10 checks whether the originals have been fed without problems a predetermined number of times in succession.

[0152] When the number of successful feeding attempts has not reached the predetermined number (No in step #56), when the operation panel 5 receives a reading start instruction, the transport control unit 10 starts feeding the next document in the single-sheet reading mode (step #57). In other words, when the number of successful feeding attempts has not reached the predetermined number (No in step #56), the transport control unit 10 maintains the single-sheet reading mode. After step #57, the transport control unit 10 executes step #51 (return to step #51).

[0153] When the number of successful paper feeds reaches a predetermined number (Yes in step #56), it is determined that there is no problem in switching to the continuous reading mode. Therefore, the conveyance control unit 10 automatically changes the mode to the continuous reading mode (automatic selection) (step #57). Since the continuous reading mode has been selected, the conveyance control unit 10 ends the processing of this flowchart, which is based on the single sheet reading mode (END).

[0154] (If you do not allow automatic mode changes) Next, an example of the operation when automatic mode change is not permitted will be described with reference to Fig. 14. Fig. 14 is a diagram showing an example of the operation when automatic mode change is not permitted.

[0155] The operation panel 5 accepts the selection of whether to use the normal mode or the manual feed mode. In other words, the operation panel 5 accepts the selection of using only the normal mode. When the normal mode is selected, the transport control unit 10 maintains the feeding and transport of the document in the normal mode from the first page to the last page.

[0156] Also, the operation panel 5 accepts the selection of using only the continuous reading mode. In other words, the operation panel 5 accepts the operation of the continuous reading mode selection button B3 when the automatic change permission checkbox C1 is not checked as the selection of using only the continuous reading mode. In this case, the transport control unit 10 does not automatically change to the single sheet reading mode during the continuous reading mode.

[0157] Also, the operation panel 5 accepts the selection of using only the single sheet reading mode. In other words, the operation panel 5 accepts the operation of the single sheet reading mode selection button B2 when the automatic change permission checkbox C1 is not checked as the selection of using only the single sheet reading mode. In this case, the transport control unit 10 does not automatically change to the continuous reading mode during the single sheet reading mode.

[0158] In this manner, the document transport device 1 according to the embodiment includes a lift plate 8, a pickup roller 12, a lift motor 81, a retard roller 70, and a control unit (transport control unit 10). Documents are set on the lift plate 8. The pickup roller 12 comes into contact with the top document among the documents set on the lift plate 8. The pickup roller 12 rotates to feed the document in the document transport direction. The lift motor 81 raises and lowers the lift plate 8. When starting paper feeding, the lift motor 81 raises the lift plate 8 until the top document comes into contact with the pickup roller 12. The retard roller 70 is provided downstream of the pickup roller 12 in the document transport direction. The retard roller 70 comes into contact with the document sent out by the pickup roller 12. When the normal mode is selected, the control unit rotates the retard roller 70 in a direction that feeds the document in the opposite direction to the document transport direction. When the manual feed mode is selected, the control unit rotates the retard roller 70 in a direction that feeds the document in the document transport direction. When the manual feed mode is selected, the control unit causes the lift motor 81 to start lowering the lift plate 8 while the pickup roller 12 is feeding the document after the pickup roller 12 starts rotating.

[0159] While the document is being fed, the lift plate 8 can be lowered. By lowering the lift plate 8, the document is no longer in contact with the pickup roller 12. Even if the pickup roller 12 does not stop immediately after the fed document passes through the pickup roller 12, the next document will not be sent out.

[0160] Also, a gap can be created between the document being transported (the top document) and the second document from the top. The second and subsequent documents from the top can be prevented from being dragged by the document being transported (the top document). It is possible to reduce the number of documents from the second and subsequent documents being fed into the retard roller 70 while the top document is being transported. In the manual feed mode, the retard roller 70 rotates in a direction that feeds the document in the document transport direction. Even if the retard roller 70 does not perform the function of preventing continuous feeding and double feeding, the occurrence of continuous feeding and double feeding of documents can be suppressed.

[0161] Also, the pickup roller 12 will no longer press down on the set document. If the pickup roller 12 presses down on the top document, documents below the top document may be dragged by the top document. By lowering the lift plate 8, the force with which the pickup roller 12 presses down on the document stack can be weakened.

[0162] The control unit causes the lift motor 81 to start lowering the lift plate 8 after the time has elapsed, which is calculated by dividing the distance from the pickup roller 12 to the retard roller 70 by the ideal transport speed of the document from the start of rotation of the pickup roller 12. The lift plate 8 can be lowered from the point when the retard roller 70 catches the leading edge of the document. In other words, even if the pickup roller 12 and the topmost document are separated, the lift plate 8 can be lowered only when the topmost document can continue to be fed. The lift plate 8 can start to be lowered immediately when there is no problem in lowering it.

[0163] The document transport device 1 includes a feed sensor 19. The feed sensor 19 is provided downstream of the retard roller 70 in the document transport direction. Based on the output of the feed sensor 19, the control unit recognizes that the leading edge of the document has reached the feed sensor 19. When it recognizes that the leading edge of the document has reached the feed sensor 19, the control unit causes the lift motor 81 to start lowering the lift plate 8. When the lift plate 8 is lowered and transport of the document can continue, the lift plate 8 can start to be lowered. Even when the lift plate 8 is lowered, the document can be sent downstream in the document transport direction without any problems.

[0164] Alternatively, in the case where the feed motor 17 is a stepping motor, the control unit may input a predetermined number of descent start pulses to the feed motor 17 from the start of rotation of the pickup roller 12, and cause the lift motor 81 to start lowering the lift plate 8. In this case, the number of descent start pulses is a value obtained by dividing the distance from the pickup roller 12 to the retard roller 70 by the amount of document movement per pulse. Even in this manner, the lift plate 8 can start to be lowered at a point where the document transport can continue even if the lift plate 8 is lowered. Even if the lift plate 8 is lowered, the document can be sent downstream in the document transport direction without any problems.

[0165] Based on the output of the feed sensor 19, the control unit recognizes that the trailing edge of the document has passed the feed sensor 19. When it recognizes that the trailing edge of the document has passed the feed sensor 19, the control unit stops the rotation of the pickup roller 12 and the retard roller 70. When one document has been properly fed out from the lift plate 8, the feed sensor 19 recognizes the trailing edge passing. When it is determined that one document has been properly fed out, the rotation of the pickup roller 12 and the retard roller 70 can be stopped. Because the lift plate 8 is lowered, even if the pickup roller 12 continues to rotate after the document has passed the pickup roller 12, the next document will not be fed in the document transport direction. The pickup roller 12 and the retard roller 70 can be rotated just enough.

[0166] The control unit measures the required passing time T9 from when it recognizes that the leading edge of the document has reached feed sensor 19 until it recognizes that the trailing edge of the document has passed feed sensor 19. Based on the length of required passing time T9, the control unit detects that a continuous document feed error has occurred. When it detects the occurrence of a continuous document feed error, the control unit stops the rotation of pickup roller 12 and retard roller 70. It is possible to detect a continuous document feed error that has already occurred. When continuous document feed occurs, the document may jam (be jammed). It is possible to stop the transport of the document to prevent the document from being damaged by a jam.

[0167] After the pickup roller 12 starts rotating, when the lift plate 8 is lowered while the pickup roller 12 is feeding the document, the control unit lowers the lift plate 8 by a predetermined lowering amount. The lift plate 8 can be lowered just enough. It is possible to prevent the lift plate 8 from being lowered too much while preventing continuous feeding.

[0168] The amount of lowering is a value within a range in which the distance from the lower end of the circumferential surface of the pickup roller 12 to the document one document below the topmost document is equal to or greater than a predetermined separation distance, and the document on the lift plate 8 does not fall below a predetermined lower limit height. The pickup roller 12 and the document can be sufficiently separated. If the topmost document sags too much, the document must be transported while being pulled up. If the document sags too much, the image quality of the image data obtained by reading may be degraded. Since the lift plate 8 is not lowered too much, the topmost document (document being transported) can be prevented from sagging too much.

[0169] In the manual feed mode, the control unit slows down the document transport speed compared to the normal mode. Since the document transport speed is suppressed in the manual feed mode, damage to the document when an error occurs can be reduced or eliminated.

[0170] The document transport device 1 includes a feed motor 17, a first drive mechanism 9a, a second drive mechanism 9b, and a third drive mechanism 9c. The feed motor 17 rotates the pickup roller 12 and the retard roller 70. When the feed motor 17 rotates in a first direction, the first drive mechanism 9a rotates the pickup roller 12 in a direction that feeds the document in the document transport direction. When the feed motor 17 rotates in a second direction opposite to the first direction, the second drive mechanism 9b rotates the pickup roller 12 in a direction that feeds the document in the document transport direction. When the feed motor 17 rotates in the first direction, the third drive mechanism 9c rotates the retard roller 70 in a direction that feeds the document in the opposite direction to the document transport direction. When the feed motor 17 rotates in the second direction, the third drive mechanism 9c rotates the retard roller 70 in a direction that feeds the document in the document transport direction. The pickup roller 12 and the retard roller 70 can be rotated in the correct direction in each mode. By using the first drive mechanism 9a, the second drive mechanism 9b, and the third drive mechanism 9c, only one motor, the feed motor 17, is required to rotate the pickup roller 12 and the retard roller 70.

[0171] The document transport device 1 also includes a document set sensor 16 and an operation panel 5. The document set sensor 16 detects whether or not a document is set on the lift plate 8. The operation panel 5 accepts the selection of a mode. When the normal mode is selected, the control unit rotates the pickup roller 12 in a direction to feed the document in the document transport direction, and rotates the retard roller 70 in a direction to feed the document in the opposite direction to the document transport direction. When the manual feed mode is selected, the control unit rotates the pickup roller 12 and the retard roller 70 in a direction to feed the document in the document transport direction. After the pickup roller 12 starts to rotate, the control unit causes the lift motor 81 to start lowering the lift plate 8 while the pickup roller 12 is feeding the document. The control unit stops the pickup roller 12 and the retard roller 70 after the rear end of the document passes through the retard roller 70. Furthermore, when the continuous reading mode of the manual feed mode is selected, the control unit recognizes whether or not a document is set on the lift plate 8 based on the output of the document set sensor 16. If there is a document set on the lift plate 8 at the time when the pickup roller 12 and the retard roller 70 are stopped, the control unit raises the lift plate 8 again until the topmost document comes into contact with the pickup roller 12. After the lift is complete, the control unit rotates the pickup roller 12 and the retard roller 70 in a direction that sends the document in the document transport direction, and automatically resumes feeding in the manual feed mode.

[0172] The lift plate 8 can be lowered while the document is being fed. By lowering the lift plate 8, the document being transported does not come into contact with the pickup roller 12. Also, a gap can be created between the document being transported (the topmost document) and the second document from the top. This can prevent documents other than the second document from the top from being dragged by the document being transported. This can reduce the occurrence of continuous feeding.

[0173] In addition, in the continuous reading mode, multiple originals can be fed one by one continuously in the manual feed mode. In the process of feeding the originals one by one, the lift plate 8 automatically rises and falls and the rollers automatically rotate. There is no need to issue an instruction to raise the lift plate 8 again or to start the original transport (reading) each time a single original is transported. Multiple originals can be automatically read in the manual feed mode without the occurrence of double feeding or continuous feeding.

[0174] The control unit measures the required passing time T9 from when it recognizes that the leading edge of the document has reached the feed sensor 19 until it recognizes that the trailing edge of the document has passed the feed sensor 19. Based on the length of the required passing time T9, the control unit detects that a continuous document feed error has occurred. When it detects that a continuous document feed error has occurred in the continuous reading mode, the control unit automatically selects the single-sheet reading mode. The single-sheet reading mode is one of the manual feed modes. In the single-sheet reading mode, the control unit lifts the lift plate 8 and feeds one sheet of document in the manual feed mode after the operation panel 5 receives an instruction to start single-sheet reading.

[0175] It is difficult to completely eliminate the occurrence of continuous feed errors. Therefore, when a continuous feed error is detected during scanning in continuous scan mode, the manual feed mode can be automatically changed from continuous scan mode to single sheet scan mode. Single sheet scan mode is a mode in which documents are scanned one sheet at a time. To prevent continuous feed errors, the mode can be automatically switched to one in which scanning can be performed while checking each sheet.

[0176] When a predetermined number of documents have been conveyed without a continuous feed error occurring in the single-sheet reading mode, the control unit automatically selects the continuous reading mode. When it is determined that the possibility of a continuous feed error occurring in the continuous reading mode is low, the control unit can automatically switch from the single-sheet reading mode to the continuous reading mode.

[0177] The operation panel 5 accepts the selection of using only the continuous reading mode. When the selection of using only the continuous reading mode is made, the control unit does not automatically change to the single sheet reading mode while in the continuous reading mode. Some users do not want the mode to be automatically switched to the single sheet reading mode. Users who do not want the automatic switching can continue to use only the desired mode (only the continuous reading mode).

[0178] The operation panel 5 accepts the selection of using only the single sheet reading mode. When the selection of using only the single sheet reading mode is made, the control unit does not automatically select the continuous reading mode while in the single sheet reading mode. Some users do not want the mode to be automatically switched to the continuous reading mode. Users who do not want the automatic switching can continue to use only the desired mode (only the single sheet reading mode).

[0179] The operation panel 5 accepts the selection of whether to use the normal mode or the manual feed mode. The control unit causes the document to be read in the selected mode. The user can select whether to use the normal mode or the manual feed mode. The document can be read in the selected mode.

[0180] The multi-feed detection sensor 111 is included for detecting multi-feeding of documents. The output of the multi-feed detection sensor 111 is input to the control unit. When feeding in normal mode, the control unit determines whether or not a multi-feed has occurred based on the output of the multi-feed detection sensor 111. When feeding in manual feed mode, the control unit does not determine whether or not a multi-feed has occurred based on the output of the multi-feed detection sensor 111. The manual feed mode is intended for feeding and transporting documents made up of multiple overlapping sheets, such as slips. In the manual feed mode, even if a single document made up of multiple overlapping sheets is fed and transported, it will not be erroneously detected as a multi-feed.

[0181] Although an embodiment of the present invention has been described above, the scope of the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention. [Industrial Applicability]

[0182] The present invention can be used in a document transport device that uses a lift plate to bring a pickup roller into contact with a document. [Explanation of symbols]

[0183] 1 Original transport device 10 Transport control unit (control unit) 12 Pickup roller 16 Document set sensor 17 Feed motor 19 Feed sensor 111 Double feed detection sensor 5 Operation panel 70 Retard roller 8 Lift plate 81 Lift motor 9a First drive mechanism 9b Second drive mechanism 9c Third drive mechanism T9 transit time

Claims

1. a lift plate on which the document is placed; a pickup roller that is supported to be swingable, that comes into contact with a topmost document among the documents set on the lift plate, and that rotates to feed the document in a document transport direction; a lift motor that raises and lowers the lift plate and raises the lift plate until the top document comes into contact with the pickup roller when paper feeding is started; a retard roller that is provided downstream of the pickup roller in a conveying direction of the document and that comes into contact with the document fed by the pickup roller; When a normal mode is selected, the retard roller is rotated in a direction in which the document is fed in a direction opposite to a conveying direction of the document; When a manual feed mode is selected, the retard roller is rotated in a direction in which the document is fed in a transport direction of the document; and a control unit that, when the manual feed mode is selected, causes the lift motor to start lowering the lift plate after the pickup roller starts rotating while the pickup roller is feeding the document.

2. The document transport device according to claim 1, characterized in that the control unit causes the lift motor to start lowering the lift plate after a time has elapsed that is obtained by dividing the distance from the pickup roller to the retard roller by an ideal transport speed for the document from the start of rotation of the pickup roller.

3. a feed sensor provided downstream of the retard roller in a conveying direction of the document; The control unit is Based on the output of the feed sensor, the leading edge of the document reaches the feed sensor. Recognizing what has been achieved 3. The document transport device according to claim 1, wherein when the leading edge of the document reaches the feed sensor, the lift motor starts to lower the lift plate.

4. a feed motor that rotates the pickup roller; the feed motor is a stepping motor, the control unit inputs a predetermined number of descent start pulses to the paper feed motor from the start of rotation of the pickup roller, and after the input, when a time corresponding to the number of descent start pulses has elapsed, causes the lift motor to start lowering the lift plate; 2. The document transport device according to claim 1, wherein the number of descent start pulses is a value obtained by dividing a distance from the pickup roller to the retard roller by an amount of movement of the document per pulse.

5. a feed sensor provided downstream of the retard roller in a conveying direction of the document; The control unit is Based on an output of the feed sensor, it is recognized that the trailing edge of the document has passed the feed sensor; 5. The document transport device according to claim 1, wherein when it is recognized that the trailing edge of the document has passed the feed sensor, the rotation of the pickup roller and the retard roller is stopped.

6. The control unit is measuring a time required for passing the document from when it is recognized that the leading edge of the document has reached the feed sensor to when it is recognized that the trailing edge of the document has passed the feed sensor; Detecting that a continuous feeding error has occurred for the original based on the length of the passing time; 6. The document transport device according to claim 3, wherein when the occurrence of the continuous paper feed error is detected, the rotation of the pickup roller and the retard roller is stopped.

7. 7. The document transport device according to claim 1, wherein when the lift plate is lowered while the pickup roller is feeding a document after the pickup roller starts rotating, the control unit lowers the lift plate by a predetermined amount.

8. The amount of descent is the distance from the lower end of the circumferential surface of the pickup roller to the document immediately below the top document is equal to or greater than a predetermined separation distance; 8. The document transport device according to claim 7, wherein the height of the document on the lift plate is set to a value within a range not lower than a predetermined lower limit height.

9. 9. The document transport device according to claim 1, wherein the control unit controls the document transport speed in the manual feed mode to be slower than that in the normal mode.

10. a paper feed motor that rotates the pickup roller and the retard roller; a first drive mechanism that rotates the pickup roller in a direction to feed the document in a document transport direction when the feed motor rotates in a first direction; a second drive mechanism that rotates the pickup roller in a direction to feed the document in a document transport direction when the paper feed motor rotates in a second direction opposite to the first direction; The document transport device described in any one of claims 1 to 9, further comprising a third drive mechanism that rotates the retard roller in a direction that feeds the document in a direction opposite to the document transport direction when the paper feed motor is rotated in the first direction, and rotates the retard roller in a direction that feeds the document in the document transport direction when the paper feed motor is rotated in the second direction.

Images