JP2013074544A - Document reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a U-turn type document reader configured to read two sides and capable of reducing the number of components.SOLUTION: A document is delivered from a document tray and passed through an introduction path to enter a reading conveyance path in a forward direction. On the conveyance path, the document is conveyed in forward and backward directions, a first surface is read during conveyance in the forward direction, and a second surface is read during conveyance in the backward direction. Document reading means reads the first surface of the document on the basis of the detection timing of a document detection sensor of the document being conveyed in the forward direction. A switching roller capable of switching a rotational direction is installed on the reading conveyance path. The switching roller switches the rotational direction on the basis of the detection timing of the document detection sensor of the document being conveyed in the backward direction.

Description

  The present invention relates to an original reading apparatus, and more particularly to an improvement of an original reading apparatus that performs double-sided reading of an original.

  2. Description of the Related Art An original reading apparatus that can automatically convey an original and read both sides of the original is widely used. As a document reading apparatus capable of duplex scanning, for example, a two-pass one-scanner method is known in which a document is scanned on both sides using a single image sensor by reversing the front and back of the document during automatic conveyance.

  This two-pass one-scanner duplex scanning includes a switchback method in which a document is passed twice in the same direction with respect to an image sensor by performing a switchback for switching the conveyance direction during conveyance of the document (for example, Patent Documents). 1) A U-turn method in which a conveyance path is crossed using a U-turn path and a document is passed twice in the opposite direction with respect to one image sensor can be considered.

JP 2010-252250 A

  When the U-turn system is adopted, the document transport path becomes complicated, and a large number of path switching devices are required. For example, devices such as a solenoid for switching the conveyance path, a counter for measuring the conveyance distance of the document, and a document detection sensor for obtaining the switching timing of the conveyance path are required.

  In particular, since the document enters from two directions at the reading position of the image sensor, a document detection sensor for determining the reading timing is required. Further, a mechanism for conveying the document in two directions is also required. For this reason, there is a problem that the number of parts increases and the product cost and product size increase.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an original reading apparatus that performs U-turn double-sided reading and can further reduce the number of parts. To do.

  According to a first aspect of the present invention, there is provided a document reading apparatus capable of conveying a document in a forward direction and a reverse direction, and introducing the document fed from a document tray into the reading conveyance path in a forward direction. A path, a U-turn path for causing the document that has passed through the reading conveyance path in the forward direction to U-turn and entering the reading conveyance path in a reverse direction, and a document for discharging the document that has passed through the reading conveyance path in the reverse direction. A paper discharge path, a document detection sensor arranged on the reading conveyance path and detecting the document, and arranged on the reading conveyance path, reading the first surface of the document during forward conveyance, Document reading means for reading the second surface of the document at the time of conveyance, and a switching roller provided on the reading and conveying path and capable of switching the rotation direction, the document reading means is for the document being conveyed in the forward direction. The document detection section The first surface of the document is read based on the detection timing by the scanner, and the switching roller switches the rotation direction based on the detection timing of the document being conveyed in the reverse direction by the document detection sensor. The transport direction is configured to be switched from the reverse direction to the forward direction.

  According to such a configuration, the document can be passed in two directions with respect to the document reading means by switching the rotation direction of the switching roller disposed on the reading and conveying path, and the number of rollers for conveying the document can be reduced. Can be reduced. In addition, the document detection sensor is disposed at a position where the document passes twice, and is used to obtain the reading timing of the first surface of the document when transporting in the forward direction, and when the document is transported in the reverse direction, It is used to obtain the timing for returning the transport direction from the reverse direction to the forward direction. For this reason, a number of parts can be reduced and a product can be reduced in size.

  A document reading apparatus according to a second aspect of the present invention is arranged at an intersection where the discharge path and the U-turn path intersect in addition to the above-described configuration, and causes the document on the U-turn path to enter the reading conveyance path during reverse rotation. A discharge roller that conveys the original on the discharge path to the discharge port during normal rotation, and the discharge roller detects the original being conveyed in the reverse direction based on the detection timing by the original detection sensor. It is configured to switch the rotation direction to rolling.

  According to such a configuration, since the document detection sensor is also used for obtaining the timing for switching the rotation direction of the discharge roller, the number of document detection sensors can be further reduced. Further, a discharge roller for discharging the document to the discharge port is also used for transporting the document on the U-turn path. Therefore, the number of parts can be further reduced.

  In addition to the above-described configuration, the document reading apparatus according to the third aspect of the present invention is configured such that the switching roller switches the rotation direction based on the detection timing of the document trailing edge being conveyed in the reverse direction by the document detection sensor. The transport direction is configured to be switched from the reverse direction to the forward direction.

  According to a fourth aspect of the present invention, there is provided a document reading device that, in addition to the above-described configuration, transfers a next document from the document tray based on a detection timing of the document being conveyed in the reverse direction by the document detection sensor. It is comprised so that it may comprise.

  According to such a configuration, the document detection sensor is also used for obtaining the feeding timing for feeding the next document from the document tray, so that the number of parts can be further reduced.

  According to a fifth aspect of the present invention, in addition to the above configuration, the document reading device switches the rotation direction based on the detection timing of the document being conveyed in the forward direction by the document detection sensor. The conveyance direction is configured to be switched from the forward direction to the reverse direction.

  According to such a configuration, the switching timing of the rotation direction of the switching roller twice is determined by the document detection sensor. For this reason, the number of parts can be further reduced.

  According to a sixth aspect of the present invention, there is provided a document reading apparatus capable of conveying a document in a forward direction and a reverse direction, and introducing the document fed from a document tray into the reading conveyance path in a forward direction. A path, a U-turn path for causing the document that has passed through the reading conveyance path in the forward direction to U-turn and entering the reading conveyance path in a reverse direction, and a document for discharging the document that has passed through the reading conveyance path in the reverse direction. A discharge path for conveying the document, a document detection sensor disposed on the U-turn path and detecting the document, and disposed on the reading conveyance path, reading the first surface of the document during forward conveyance, Document reading means for reading the second surface of the document during conveyance, and a switching roller provided on the reading conveyance path and capable of switching the rotation direction, the document reading means at a detection timing by the document detection sensor. Accordingly, the second surface of the document being conveyed in the reverse direction is read, and the switching roller switches the rotation direction based on the detection timing by the document detection sensor, thereby changing the document conveyance direction from the reverse direction. Configured to switch in direction.

  According to such a configuration, the document can be passed in two directions with respect to the document reading means by switching the rotation direction of the switching roller disposed on the reading and conveying path, and the number of rollers for conveying the document can be reduced. Can be reduced. In addition, the document detection sensor is used to determine the reading timing of the second surface of the document and is also used to determine the timing for returning the document transport direction by the switching roller from the reverse direction to the forward direction. For this reason, a number of parts can be reduced and a product can be reduced in size.

  A document reading apparatus according to a seventh aspect of the present invention includes a registration roller that is arranged on the U-turn path and corrects the skew of the document by reducing the document conveyance speed, in addition to the above-described configuration. However, the conveyance speed is increased based on the detection timing of the document detection sensor.

  According to such a configuration, the document detection sensor is used in common to obtain the timing for increasing the rotation speed of the registration roller after completion of the skew correction of the document. For this reason, the number of parts can be further reduced. In addition, since the skew of the document can be corrected before reading the second side of the document, for example, even when the skew occurs when the document is made a U-turn, the scanned image of the second side of the document is read. It is possible to suppress the occurrence of displacement in the case.

  The document reading apparatus according to the present invention can pass the document in two directions with respect to the document reading means by switching the rotation direction of the switching roller disposed on the reading and conveying path, and the number of rollers for conveying the document can be reduced. Can be reduced. In addition, the document detection sensor is disposed at a position where the document passes twice, and is used to obtain the reading timing of the first surface of the document when transporting in the forward direction, and when the document is transported in the reverse direction, It is used to obtain the timing for returning the transport direction from the reverse direction to the forward direction. For this reason, a number of parts can be reduced and a product can be reduced in size.

  Further, since the document detection sensor is also used for obtaining the timing for switching the rotation direction of the discharge roller, the number of document detection sensors can be further reduced. Further, a discharge roller for discharging the document to the discharge port is also used for transporting the document on the U-turn path. Therefore, the number of parts can be further reduced.

1 is an external view illustrating a configuration example of a document reading apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating a configuration example of a main part of the multifunction peripheral 100 of FIG. 1. FIG. 3 is an explanatory diagram showing a state in which a document is read using the ADF apparatus 10 of FIG. 2. FIG. 3 is an explanatory diagram showing a state in which a document is read using the ADF apparatus 10 of FIG. 2. FIG. 3 is an explanatory diagram showing a state in which a document is read using the ADF apparatus 10 of FIG. 2. FIG. 3 is an explanatory diagram showing a state in which a document is read using the ADF apparatus 10 of FIG. 2. FIG. 3 is an explanatory diagram showing a state in which a document is read using the ADF apparatus 10 of FIG. 2. FIG. 3 is an explanatory diagram showing a state in which a document is read using the ADF apparatus 10 of FIG. 2. FIG. 3 is an explanatory diagram showing a state in which a document is read using the ADF apparatus 10 of FIG. 2. FIG. 2 is a functional block diagram illustrating a configuration example of a main part of the MFP 100 in FIG. 1. 6 is a flowchart showing an example of processing when the leading edge of a long document is detected by the document detection sensor DS4. 5 is a flowchart illustrating an example of processing when the trailing edge of a long document is detected by the document detection sensor DS4. 6 is a flowchart showing an example of processing when the leading edge or trailing edge of a long document is detected by the document detection sensor DS5. 5 is a flowchart showing an example of processing when a leading edge of a short document is detected by a document detection sensor DS4. 6 is a flowchart showing an example of processing when the leading edge or trailing edge of a short document is detected by the document detection sensor DS5. 10 is a flowchart showing an example of processing when the trailing edge of a long document or a short document is detected by the document detection sensor DS6. 10 is a flowchart illustrating an example of an operation when a leading edge of a long document is detected by the document detection sensor DS5 according to the second embodiment. 10 is a flowchart illustrating an example of an operation when a leading edge or a trailing edge of a short document is detected by the document detection sensor DS5 according to the second embodiment.

Embodiment 1 FIG.
FIG. 1 is an external view showing a configuration example of a document reading apparatus according to an embodiment of the present invention. A multifunction machine 100 is shown as an example of a document reading apparatus. A multifunction peripheral (MFP) 100 includes an ADF (Auto Document Feeder) apparatus 10 that automatically conveys a document when reading an image, and an MFP main body 30 that performs image reading, printing, facsimile transmission / reception, and the like.

  The operation panel 31 of the MFP main body 30 is provided with an operation input unit 31a such as a start key and a numeric keypad for a user to input an operation, and a display 31b for displaying and outputting an operation state to the user. . For example, the user can designate either single-sided reading or double-sided reading of a document by performing an operation input to the operation input unit 31a.

  Further, a contact glass (not shown) is formed on the upper surface of the MFP main body 30, and the ADF device 10 is disposed on the contact glass so as to be opened and closed. That is, the multi-function device 100 can read a document by either a flat bed method for reading a document placed on a contact glass or an ADF method for reading a document being automatically conveyed by the ADF device 10.

  The ADF apparatus 10 includes a document tray 11 and a discharge tray 12, and a conveyance path is formed in the interior. The documents in the document tray 11 are separated and fed one by one, conveyed along the conveyance path, and discharged to the discharge tray 12. This conveyance path is formed so as to pass over the contact glass of the MFP main body 30, and the original is read by the MFP main body 30 when passing over the contact glass.

  FIG. 2 is a cross-sectional view illustrating a configuration example of a main part of the multifunction peripheral 100 of FIG. 1, and mainly illustrates the internal structure of the ADF apparatus 10. A1 to A11 in the figure are document conveying paths. B2 is an original reading position, and B1 and B3 to B8 are branch points, junctions or intersections of two or more conveyance paths.

<Original Reading Unit 32>
The document reading unit 32 is an image sensor that reads an image of a document that passes through the reading position B2, and constitutes a scanner unit including a projector 32a and a line sensor 32b. Irradiation light from the projector 32a is reflected by the original on the contact glass, and is detected by a line sensor 32b in which a large number of light receiving elements are linearly arranged. A two-dimensional image can be read by relatively moving the document or the line sensor 32b in a direction crossing the arrangement direction. When performing image reading by the ADF method, the scanner unit is stopped and image reading is performed on the document being conveyed.

  This multi-function machine 100 employs a two-pass one-scanner method, and performs both-side reading of a document using a single document reading unit 32. The 2-pass 1-scanner method is a double-sided reading method in which the front and back sides of a document are reversed and the document is read twice by the same document reading unit 32. In a general two-pass one-scanner type document reading apparatus, a document is switched back so that the front and back sides of the document are reversed and merged in front of the document reading unit 32 through another conveyance path. Pass twice in the same direction. On the other hand, in the multi-function device 100, the front and back of the document are reversed by making a U-turn of the document, and the document reading unit 32 is passed twice. At this time, the direction in which the document passes through the document reading unit 32 is reversed in the first time and the second time.

<Transport paths A1 to A11>
In the ADF apparatus 10, transport paths A1 to A11 are formed, and the document transport paths are different for single-sided scanning, double-sided scanning of a short document, and double-sided scanning of a long document. When performing single-sided scanning, the document is transported in the order of transport paths A1, A2, A3, A4, A9, and A10. This conveyance path is called a single-sided path. Further, when performing double-sided scanning of a short document, it is conveyed in the order of A1, A2, A3, A4, A9, A11, A7, A2, A8, A4, A9, and A10. This conveyance path will be referred to as a short original duplex path. When a long original is scanned on both sides, it is conveyed in the order of A1, A2, A3, A4, A5, A6, A7, A2, A8, A4, A9, and A10. This conveyance path is referred to as a long original double-sided path.

  The conveyance path A1 and the conveyance path A2 constitute a horizontal U-shaped conveyance path, and a document conveyed on the conveyance path A1 from right to left in the drawing passes through the reading position B2 from left to right. The conveyance path A1 is an introduction path that conveys the document fed from the document tray 11 to the branch point B1, and is commonly used for any conveyance path.

  The conveyance path A2 is a reading conveyance path capable of conveying the document bidirectionally, and the document reading unit 32 reads the document passing through the reading position B2 on the conveyance path A2. In the conveyance path A2, the document that has entered from the conveyance path A1 is conveyed to the branch point B3, and enters the conveyance path A3 side. In addition, the document that has entered from the transport path A7 is transported to the branch point B1 and enters the transport path A8 side. Here, the transport direction from the branch point B1 through the reading position B2 to the branch point B3 is defined as the forward direction, and the transport direction from the branch point B3 to the branch point B1 is defined as the reverse direction.

  If the upper surface of the document stored in the document tray 11 is the first surface and the lower surface is the second surface, the first surface of the document passing through the reading position B2 in the forward direction is read, and the reading position in the reverse direction. Reading of the second side of the document passing through B2 is performed.

  The conveyance paths A3, A4, A5, A6, and A7 constitute a long document U-turn path in which, in this order, a long document that has passed through the conveyance path A2 in the forward direction is U-turned to reverse the front and back. The document that has passed through the document U-turn path enters the conveyance path A2 in the reverse direction from the branch point B3. The conveyance path A3 is a conveyance path that conveys the document that has passed through the conveyance path A2 in the forward direction from the branch point B3 to the junction B4 almost linearly. The conveyance path A4 is a conveyance path that linearly conveys the document that has passed through the conveyance path A3 or the conveyance path A8 to the branch point B5 and enters the conveyance path A9 or the conveyance path A5. The conveyance path A5 is a laterally U-shaped conveyance path that conveys the document that has passed through the conveyance path A4 to the intersection B8 and enters the conveyance path A6, and reverses the front and back by conveying the document clockwise. The conveyance path A6 is a conveyance path that linearly conveys the document that has passed through the conveyance path A5 to the junction B7. The conveyance path A7 is a conveyance path that conveys the document that has passed through the conveyance path A6 substantially linearly to the branch point B3 and enters the conveyance path A2 in the reverse direction.

  The conveyance paths A3, A4, A9, A11, and A7 constitute a U-turn path for a short document in which a short document that has passed through the conveyance path A2 in the forward direction is U-turned to reverse the front and back. The document that has passed through the document U-turn path enters the transport path A2 in the reverse direction from the branch point B3, as with the document that has passed through the long document U-turn path. The conveyance path A9 is a conveyance path that conveys the document that has passed through the conveyance path A4 to the branch point B6 and enters the conveyance path A10 or the conveyance path A11. The conveyance path A11 is a conveyance path that conveys the document that has passed through the conveyance path A9 to the junction B7. The conveyance paths A9 and A11 are conveyance paths corresponding to the upper half and the lower half of the horizontal U-shape, respectively, and reverse the front and back by conveying the document clockwise.

  The transport paths A8, A4, A9, and A10 constitute a discharge path for transporting a long document or a short document that has passed through the transport path A2 in the reverse direction to the discharge port 24 in this order. The conveyance path A8 is a conveyance path that conveys the document that has passed through the conveyance path A2 in the reverse direction from the branch point B1 to the junction B4 in a substantially linear manner. The conveyance path A <b> 10 is a conveyance path that conveys the document that has passed through the conveyance path A <b> 9 almost linearly to the intersection B <b> 8 and discharges it from the discharge port 24. That is, at the intersection B8, the discharge path and the long document U-turn path intersect.

<Document Tray 11>
The document tray 11 includes a document table 13 on which documents are stacked and placed, and a document stopper 14 for positioning these documents. The document on the document table 13 is positioned at the leading end (left end in the figure) in the feeding direction by the document stopper 14, and the vicinity of the top end of the document is in contact with the feeding roller 15.

  In the multifunction peripheral 100, the original is fed and conveyed by the feeding roller 15 and a plurality of conveying rollers. Here, the feeding roller 15, the separation roller 16a, the retard roller 16b, and the registration roller 17 are driven by the first conveyance motor, and the plurality of conveyance rollers 18, the switching roller 19, the registration roller 20, and the discharge roller 23 are second conveyance. It shall be driven by a motor.

<Feeding roller 15>
The feeding roller 15 is a document feeding unit that feeds the document in the document tray 11 to the conveyance path. The feeding roller 15 and the separation roller 16a are rotationally driven in the document feeding direction, and the retard roller 16b is rotationally driven in the return direction. Therefore, the documents in the document tray 11 are sequentially fed from the top to the transport path A1 by the feeding roller 15, and when the documents are fed in a double feed state, the separation roller 16a and the retard that are rotated in reverse to each other. Only the uppermost document is separated by the roller 16b and conveyed in the feeding direction.

<Registration roller 17>
The registration roller 17 is a conveyance roller that can be rotated asynchronously with the carry-in roller 15 and the separation roller 16a, and is disposed on a conveyance path A1 sandwiched between the separation roller 16a and the branch point B1. The registration roller 17 can be stopped while the feeding roller 15 and the separation roller 16a are driven. By stopping the registration roller 17, the conveyance speed at the leading edge of the document being conveyed can be drastically reduced, and the document can be slackened to correct skewing. Here, it is assumed that the registration roller 17 is stopped by interrupting the driving force transmitted from the first transport motor using the clutch.

<Conveying roller 18>
The transport roller 18 includes a drive roller that is rotationally driven and a driven roller that is disposed to face the drive roller across the transport path. A large number of conveying rollers 18 are arranged in the conveying paths A1 to A11 at intervals shorter than the shortest document length, and the documents are conveyed on the conveying path by these conveying rollers 18. Here, it is assumed that the transport rollers 18 rotate in synchronization with each other.

  The second conveyance motor drives the conveyance roller 18, the registration roller 20, the switching roller 19, and the discharge roller 23, respectively. At this time, the switching roller 19, the registration roller 20, and the discharge roller 23 are driven asynchronously with the transport roller 18.

<Switching roller 19>
The switching roller 19 is a conveyance roller capable of switching the rotation direction, and is disposed on a conveyance path A2 sandwiched between the reading position B2 and the branch point B1 here. The switching roller 19 conveys the document in the forward direction during normal rotation and conveys the document in the reverse direction during reverse rotation. The rotation direction of the switching roller 19 is reversed by, for example, switching on and off of a clutch that transmits the rotational force to the switching roller 19.

<Registration roller 20>
The registration roller 20 is a conveyance roller that can reduce the rotation speed asynchronously with the other conveyance rollers 18, and is disposed on the conveyance path A <b> 7. For example, the registration roller 20 is in a state in which the rotation speed is lowered by blocking the driving force transmitted from the second transport motor using a clutch. By reducing the rotation speed, it is possible to sharply reduce the conveyance speed at the leading edge of the document and correct the skew of the document.

<Discharge roller 23>
The discharge roller 23 is a conveyance roller whose rotation direction can be switched, and is disposed at an intersection B8 between the conveyance path A5 and the conveyance path A10. The discharge roller 23 discharges the document on the conveyance path A10 from the discharge port 24 to the discharge tray 12 during normal rotation. At the time of reverse rotation, the document on the conveyance path A5 is caused to enter the conveyance path A6. The rotation direction of the discharge roller 23 is reversed by using, for example, a solenoid and a clutch.

<Branching claws 21 and 22>
The branch claws 21 and 22 are conveyance path switching means for selecting one of the two or more conveyance paths as a document conveyance destination, and are constituted by, for example, a claw-shaped rotating member and a solenoid (not shown). In this case, the conveyance destination is selected by causing the solenoid to rotate the rotating member.

  The branch claw 21 is a transport path switching unit that guides the document on the transport path A4 to one of the transport paths A5 and A9, and is arranged at the branch point B5. Specifically, when guiding the document to the long document U-turn path, the document is caused to enter the conveyance path A5 side. On the other hand, when the document is guided to the short document U-turn path or the discharge path, the document is caused to enter the conveyance path A9 side.

  The branch claw 22 is a transport path switching unit that guides the document on the transport path A9 to one of the transport paths A10 and A11, and is arranged at the branch point B6. Specifically, when the document is guided to the short document U-turn path, the document is caused to enter the conveyance path A11 side. On the other hand, when the document is guided to the discharge path, the document is caused to enter the conveyance path A10 side.

  If the upper surface of the document stored in the document tray 11 is the first surface and the lower surface is the second surface, in the long document duplex path and the short document duplex path, the document is scanned in the order of the first surface and the second surface. It is read twice, and in the single-sided pass, only the first side of the original is read. That is, when the long original double-sided path is selected, the original is conveyed in the forward direction on the conveyance path A2 via the conveyance path A1, and the original reading unit 32 reads the reading position B2 on the conveyance path A2. The first surface is read at. Thereafter, the document is conveyed in the reverse direction on the conveyance path A2 via the long document U-turn path including the conveyance paths A3, A4, A5, A6, and A7, and the second surface is read. After reading the second surface, the document is discharged from the discharge port 24 through a discharge path including transport paths A8, A4, A9, and A10. In the long original double-sided path, the path length of the U-turn path is shorter than that of the short original double-sided path, and double-sided reading of an original having a longer original length can be performed.

  In the double-sided path for short originals, the original is for a long original except that the original is conveyed on a short original U-turn path including conveyance paths A3, A4, A9, A11, and A7 instead of the long original U-turn path. It is transported on the same transport path as the duplex path. The double path for a short document has a shorter path length on the U-turn path than the double-side path for a long document, and can shorten the conveyance time on the U-turn path. For this reason, in the case of an original with a short original length, it is possible to improve the conveyance efficiency of the original compared to the double-sided path for long originals.

  In the single-sided path, the conveyance path to the reading of the first side is the same as the double-sided path for long originals and the double-sided path for short originals. It discharges to the discharge port 24 through A10 in order.

<Document detection sensors DS1 to DS6>
The ADF apparatus 10 is provided with a plurality of document detection sensors DS1 to DS6. The document detection sensors DS1 and DS2 are provided on the document tray 11 and detect the document placed on the document table 13. On the other hand, the document detection sensors DS3 to DS5 detect arrival or passage of the document being conveyed at different detection positions. An optical sensor can be used for these document detection sensors DS1 to DS5.

  The document detection sensor DS1 is a document placement detection unit that detects whether or not a document is placed on the document tray 11. For example, the presence or absence of a document can be determined by embedding a reflective optical sensor in the document table 13 near the document stopper 14 and detecting the vicinity of the leading edge of the document.

  The document detection sensor DS2 is document length detection means for detecting the length of the document in the feed direction. For example, by embedding an optical sensor in the document table 13 behind the document detection sensor DS1, it is possible to determine whether or not the document length is a predetermined length or more. In this case, if two or more originals having different sizes are stacked and placed, the maximum original length is detected. Further, if two or more document detection sensors DS2 are arranged at different positions in the feeding direction, it is possible to detect that the document length is within a predetermined range.

  The document detection sensors DS3 to DS6 are transport state detection means for monitoring a predetermined detection position on the transport path and detecting the position of the document being transported, and detecting the arrival or passage of the document with respect to the detection position. Yes. That is, when the leading edge of the document is detected, it can be determined that the document has reached the detection position. When the trailing edge of the document is detected, the document has passed the detection position. Can be determined. Further, for example, the position of the document being transported can be specified by measuring the transport distance after the document is detected by the document detection sensors DS3 to DS6.

  The document detection sensor DS3 is disposed on the transport path A1 sandwiched between the separation roller 16a and the registration roller 17, and detects a document that is fed from the document tray 11 to the transport path A1 by the feeding roller 15. The document detection sensor DS3 is used, for example, to obtain timing for driving the stopped registration roller 17.

  The document detection sensor DS4 is disposed on the conveyance path A2, and is disposed at a position sandwiched between the branch point B1 and the switching roller 19 here. The document detection sensor DS4 is a sensor for obtaining the timing of reading start and reading end of the first surface by the document reading unit 32, and the front and rear ends of the document immediately before reaching or passing through the reading position B2 when transporting in the forward direction. Detected. Further, at the time of conveyance in the reverse direction, the leading and trailing edges of the document immediately after reaching or passing through the reading position B2 are detected.

  The document detection sensor DS5 is disposed on the transport path A7 and detects a document being transported. Here, the document detection sensor DS5 is disposed on the conveyance path A7 sandwiched between the junction B7 and the registration roller 20, and detects the document immediately before reaching the registration roller 20 and the reading position B2. This document detection sensor DS5 is a sensor for obtaining the timing of the start and end of reading of the second surface by the document reading unit 32, and is also used for obtaining the timing of the end of skew correction by the registration roller 20. .

  The document detection sensor DS6 is disposed upstream of the discharge roller 23 on the conveyance path A10, and detects the trailing edge of the document discharged from the discharge port 24.

  In the multi-function device 100, the U-turn method performs double-sided reading of the document without switching back the document, so that high-speed conveyance of the document can be realized. A document detection sensor DS4 is disposed on the conveyance path A2 through which the document passes twice, and is used for obtaining the reading timing of the first surface of the document when transporting in the forward direction, and a switching roller when transporting in the reverse direction. It is used to obtain the timing for switching the rotation direction of 19 from reverse rotation to normal rotation. For this reason, the number of parts of the multifunction peripheral 100 can be reduced, and the product can be downsized.

  3 to 9 are explanatory views showing a state in which a document is read using the ADF apparatus 10 of FIG. In the ADF apparatus 10, one of the three reading methods of single-sided scanning, double-sided scanning for short originals, and double-sided scanning for long originals is selected by the user. When the user selects either single-sided scanning or double-sided scanning and double-sided scanning is selected, one of the two scanning methods is selected based on the document size detected by the document detection sensor DS2. You may do it.

<Single-sided scanning>
FIGS. 3A and 3B are explanatory diagrams for single-sided reading, in which the conveyance states of documents on the conveyance paths A1 to A11 are shown in chronological order. In single-sided scanning, the document is transported forward in the transport path A2 through the transport path A1, passes through the reading position B2, and then discharged in order through the transport paths A3, A4, A9, and A10. That is, the document passes through the reading position B2 only once and is discharged to the discharge tray 12. In this case, the document is guided to the conveyance path A9 side by the branch claw 21 at the branch point B5, and is guided to the conveyance path A10 side by the branch claw 22 at the branch point B6. In single-sided reading, the switching roller 19 and the discharge roller 23 are driven only in forward rotation, and the rotation direction is not switched. Further, as shown in (b) in the figure, the transfer of the subsequent document is started before the preceding document is discharged.

<Double-sided scanning of short documents>
FIGS. 4A to 6H are explanatory diagrams of double-sided reading of a short document, in which the transport states of the document on the transport paths A1 to A11 are shown in chronological order. As shown in FIG. 4A, the document is conveyed in the forward direction along the conveyance path A2 via the conveyance path A1, and reaches the reading position B2.

  Next, as shown in FIG. 4B, the document is transported on a short document U-turn path composed of transport paths A3, A4, A9, A11, and A7. In this case, the document is guided to the conveyance path A9 side by the branch claw 21 at the branch point B5, and is guided to the conveyance path A11 side by the branch claw 22 at the branch point B6. As shown in FIG. 4B, when the leading edge of the document reaches the reference position E1 on the conveyance path A7, the rotation direction of the switching roller 19 is switched from normal rotation to reverse rotation. The arrival of the document front end at the reference position E1 is determined, for example, by measuring the transport distance after the document front end detection by the document detection sensor DS4.

  Further, as shown in FIG. 4C, the skew of the original is corrected by the registration roller 20. The correction of the skew is performed by bringing the leading edge of the document being conveyed into contact with the registration roller 20 whose rotational speed has been lowered and loosening the document. After correcting the skew, the rotation speed of the registration roller 20 is increased, and the document enters the conveyance path A2 in the reverse direction.

  As shown in FIGS. 5D to 6G, the document that has passed through the transport path A2 is transported through a discharge path including transport paths A8, A4, A9, and A10. In this case, as shown in FIG. 5E, when the trailing edge of the document passes the reference position E2, the feeding of the next document by the feeding roller 15 is started. At the branch point B5, the document is guided from the transport path A4 to the transport path A9 by the branch claw 21, and when the leading edge of the document reaches the reference position E3 on the transport path A9 as shown in FIG. In addition, the rotation direction of the switching roller 19 is switched again from the reverse rotation to the normal rotation. Further, at the branch point B6, the document is guided from the transport path A9 to the transport path A10 by the branch claw 22, and is discharged to the discharge tray 12 (FIG. 6G). Further, as shown in FIG. 6H, the next original is conveyed in the forward direction on the conveyance path A2 by the switching roller 19 driven to rotate forward, and the first surface is read.

<Double-sided scanning of long documents>
FIGS. 7A to 9I are explanatory diagrams for double-sided reading of a long document, and document conveyance states on the conveyance paths A1 to A11 are shown in time series. As in the case of double-sided scanning of a short document, the document is conveyed in the forward direction on the conveyance path A2 and reaches the reading position B2 (FIG. 7A).

  Next, as shown in FIGS. 7B to 8D, the document is transported on a long document U-turn path composed of transport paths A3, A4, A5, A6, and A7. In this case, at the branch point B5, the document is guided to the conveyance path A5 side by the branch claw 21. Further, as shown in FIG. 7B, when the leading edge of the document reaches the reference position E4 on the conveyance path A5, the rotation direction of the discharge roller 23 is switched from normal rotation to reverse rotation. The timing for switching the rotation direction of the discharge roller 23 may be earlier, but, for example, when a solenoid is used to switch the rotation direction of the discharge roller 23, the power consumption during reverse rotation of the solenoid is greater than during forward rotation. Can be considered. In this case, power consumption can be reduced by delaying the switching timing to reverse rotation.

  Further, as shown in FIG. 7C, when the trailing edge of the document passes the reference position E5 on the conveyance path A3, the rotation direction of the switching roller 19 is switched from normal rotation to reverse rotation. The passage of the reference position E5 at the trailing edge of the document is determined, for example, by measuring the conveyance distance of the trailing edge of the document from the detection position of the document detection sensor DS4. Further, as shown in FIG. 8D, the skew of the original is corrected by the registration roller 20. After correcting the skew, the rotation speed of the registration roller 20 is increased, and the document enters the conveyance path A2 in the reverse direction.

  As shown in FIGS. 8E to 9G, the document that has passed through the transport path A2 is transported through a discharge path including transport paths A8, A4, A9, and A10. In this case, the document is guided to the conveyance path A9 side by the branch claw 21 at the branch point B5, and the document is guided to the conveyance path A10 side by the branch claw 22 at the branch point B6.

Further, as shown in FIG. 8F, when the leading edge of the document reaches the reference position E6 on the conveyance path A9, the rotation direction of the discharge roller 23 is switched from reverse rotation to normal rotation. Further, as shown in FIG. 9G, when the trailing edge of the document passes the reference position E2, the feeding of the next document by the feeding roller 15 is started. This reference position E2 is the same as the reference position at which the transfer of the short document is started. Further, as shown in FIG. 9H, when the trailing edge of the document passes the reference position E7 on the transport path A2, the rotation direction of the switching roller 19 is switched from reverse rotation to normal rotation. The reference position E7 may be configured to coincide with the detection position of the document detection sensor DS4. Thereafter, as shown in FIG. 9 (i), the next document is conveyed in the forward direction on the conveyance path A2 by the switching roller 19 driven to rotate forward, and the first surface is read.
<Functional configuration of MFP 100>

  FIG. 10 is a functional block diagram showing an example of the configuration of the main part of the multifunction peripheral 100 of FIG. This multi-function machine 100 includes a document detection sensor DS4 to DS6, a document detection sensor DS2, a transport position specifying unit 41, a transport control unit 42, a document reading unit 32, a transfer control unit 43, a switching roller 19, a registration roller 20, and a discharge roller. 23 and the feeding roller 15.

  The document detection sensors DS4 to DS6 are document detection means for detecting a document being conveyed, and output a leading edge detection signal and a trailing edge detection signal, respectively, when the leading edge and trailing edge of the document are detected. The document detection sensor DS4 monitors the detection position on the transport path A2, and detects each document transported in the forward direction or the reverse direction on the transport path A2. Here, it is assumed that the document detection sensor DS4 is disposed in the vicinity of the reading position B2 on the transport path A2, and detects the document immediately before entering the reading position B2 when transporting in the forward direction.

  The document detection sensor DS5 monitors the detection position on the transport path A7 and detects a document being transported on the short document U-turn path or the long document U-turn path. Here, it is assumed that the document detection sensor DS5 is disposed in the vicinity of the registration roller 20 and the reading position B2 on the conveyance path A7, and detects the document immediately before reaching the registration roller 20 and the reading position B2.

  The document detection sensor DS6 is disposed upstream of the discharge roller 23 on the conveyance path A10, and detects the trailing edge of the document discharged from the discharge port 24.

  The document detection sensor DS2 is a document length detection unit that detects the length of the document placed on the document table 13 in the feeding direction. If two or more originals of different sizes are stacked and placed, the maximum original length is detected.

  The transport position specifying unit 41 is a position specifying unit that specifies the position of the document being transported based on the detection timings of the document detection sensors DS4 to DS6. Specifically, after inputting the leading edge detection signal and trailing edge detection signal of the document detection sensors DS4 to DS6, the document position is calculated by measuring the transport distance from these detection positions. Here, the second transport motor is a stepping motor, and the transport distance of the document is measured by counting the number of steps supplied to the stepping motor. Further, by subtracting the document length detected by the document detection sensor DS2, the position of the trailing edge of the document can be specified based on the leading edge detection signals of the document detection sensors DS4 and DS5, and vice versa. it can. Note that the conveyance distance may be measured by measuring the document conveyance time using a timer.

  Further, when the document position is specified based on the conveyance distance, the document position can be specified more accurately if the conveyance distance from the document detection position is short. For this reason, the transport position specifying unit 41 specifies the document position based on the detection timing of the document detection sensor closer to the document being transported.

  The conveyance control unit 42 is a control unit that controls the switching roller 19, the registration roller 20, and the discharge roller 23 based on document detection timings by the document detection sensors DS 4 to DS 6. The transport control unit 42 generates a control signal for switching the rotation directions of the switching roller 19 and the discharge roller 23 based on the document position specified by the transport position specifying unit 41. Further, based on this document position, the skew correction by the registration roller 20 is terminated and a control signal for increasing the rotation speed is generated.

  The switching roller 19 is a conveyance roller that is provided on the conveyance path A2 and can switch the rotation direction. The switching roller 19 performs an operation of switching the rotation direction based on a control signal from the conveyance control unit 42. For example, after the first side of the long original is read, an operation of switching the rotation direction from normal rotation to reverse rotation is performed based on the passage of the rear end of the original with respect to the reference position E5 (FIG. 7C) on the conveyance path A3. By switching the rotation direction, the transport direction on the transport path A2 is switched from the forward direction to the reverse direction. Specifically, the transport position specifying unit 41 measures the transport distance of the rear end of the document from the detection position based on the detection timing of the document detection sensor DS4, and determines the passage of the document with respect to the reference position E5.

  Further, the switching roller 19 performs an operation of switching the rotation direction from reverse rotation to normal rotation based on the passage of the original with respect to the reference position E7 (FIG. 9 (h)) on the conveyance path A2 after reading the second side of the long original. Do. That is, the rotation direction is switched based on the detection timing of the document detection sensor DS4 as in the case of switching to reverse rotation. In particular, it is desirable to determine the passage of the reference position E7 based on the trailing edge detection signal of the document detection sensor DS4. In this case, compared with the case where the leading edge of the document is detected, the transport distance of the document becomes shorter, so that the passage of the document can be more accurately determined.

  The registration roller 20 is a conveyance roller that is disposed on the conveyance path A7 and can correct the skew of the document by reducing the document conveyance speed. Specifically, based on the detection timing of the document detection sensor DS5, the document transport speed at the leading edge of the document is sharply lowered to loosen the document and correct skew of the document. In this case, the slackness generated in the document is eliminated by increasing the rotation speed of the registration roller 20 thereafter.

  After the skew correction is completed, the registration roller 20 increases the document conveyance speed based on the detection timing of the document detection sensor DS5, and causes the document to enter the conveyance path A2 in the reverse direction. Here, it is assumed that the document conveyance speed is increased after a certain period of time has elapsed from the detection timing of the document leading edge by document detection sensor DS5.

  The discharge roller 23 is a conveyance roller that is disposed at the intersection B <b> 8 and whose rotation direction can be switched similarly to the switching roller 19. The discharge roller 23 causes the document on the long document U-turn path to enter the transport path A2 in the reverse direction during reverse rotation, and discharges the document on the discharge path from the discharge port 24 during normal rotation.

  The discharge roller 23 performs an operation of switching the rotation direction based on a control signal from the conveyance control unit 42. For example, in order to allow the long original after the first surface reading to enter the conveyance path A2 in the reverse direction, the rotation direction is changed based on the arrival of the original on the reference position E4 (FIG. 7B) on the conveyance path A5. Switch from forward rotation to reverse rotation. In this case, the transport position specifying unit 41 measures the transport distance of the front end of the document from the detection position based on the detection timing of the document detection sensor DS4, and determines the arrival of the document at the reference position E4.

  Further, in order to discharge the long original after the second side reading to the discharge port 24, the rotation direction is changed from reverse to normal based on the arrival of the original at the reference position E6 (FIG. 8 (f)) on the conveyance path A9. Switch to rollover. Here, it is assumed that the transport position specifying unit 41 determines the arrival of the document at the reference position E6 based on the detection timing of the document detection sensor DS4.

  The document reading unit 32 is a scanner unit that is provided on the conveyance path A2 and reads a document that passes through the reading position B2. The document reading unit 32 reads the first surface of the document being conveyed in the forward direction based on the detection timing of the document by the document detection sensor DS4. That is, the conveyance position specifying unit 41 measures the conveyance amount after the input of the leading edge detection signal and the trailing edge detection signal of the document detection sensor DS4, so that the leading edge of the document reaches the reading position B2 and the passage of the trailing edge respectively. Determine. Further, based on the determination result, the document reading unit 32 reads the document from when the leading edge of the document reaches the reading position B2 until the trailing edge passes through the reading position B2.

  Further, the document reading unit 32 reads the second surface of the document being conveyed in the reverse direction based on the detection timing of the document detection sensor DS5. In this case, similarly to the reading of the first surface, the document is read from the time when the leading edge of the document reaches the reading position B2 until the trailing edge passes the reading position B2.

  The feeding control unit 43 is a control unit that controls the feeding roller 15 based on the detection timing of the document by the document detection sensor DS4, and the feeding roller based on the document position specified by the transport position specifying unit 41. 15 generates a control signal for starting transfer.

  The feed roller 15 is a document feed unit that feeds the next document from the document tray 11 based on a control signal from the feed control unit 43. For example, when a short document or a long document is conveyed, the next document is started to be fed based on the passage of the trailing edge of the document with respect to the reference position E2. In this case, the transport position specifying unit 41 determines the passage of the trailing edge of the document with respect to the reference position E2 based on the detection timing of the document detection sensor DS4, as shown in FIGS. 5 (e) and 9 (g). The document detection sensor DS4 does not detect the document trailing edge during passage of the document trailing edge reference position E2. Therefore, the transport position specifying unit 41 calculates the trailing edge position of the document by subtracting the document length from the detection position when the document detection sensor DS4 detects the leading edge of the document. Further, the passage of the document rear end with respect to the reference position E2 is determined by measuring the transport distance from the calculated rear end position. Further, the reference position E2 may be configured to coincide with the reading position B2.

  From the viewpoint of improving the document transport efficiency, it is desirable to shorten the document transport interval as much as possible. However, in order to prevent the originals from contacting each other, it is necessary to carry in the original so that the leading edge of the next original reaches the branch point B1 after the rear end of the previous original passes the branch point B1 toward the conveyance path A8. There is. For this reason, the feeding roller 15 sets the feeding timing of the original so that the originals do not come into contact with each other, including the time taken to separate the double feed state by the separation roller 16a and the retard roller 16b and the skew correction by the registration roller 17. Has been decided. Specifically, even when the separation of the double feed state and the correction of the skew feed are completed in the minimum time, the timing at which the next document reaches the branch point B1 after the leading edge of the previous document passes the branch point B1. Transfer the manuscript.

  In particular, when the original is fed based on the detection timing of the original detection sensor DS4 closer to the branch point B1 than the original detection sensors DS5 and DS6, the deviation of the conveyance interval due to the measurement error of the conveyance distance is further increased. Can be small. For this reason, it is possible to shorten the conveyance interval while accurately suppressing contact between the originals.

  According to the present embodiment, by switching the rotation direction of the switching roller 19 disposed on the transport path A2, the document can be passed through the document reading unit 32 in two directions, and the document transport roller. The number of can be reduced. In addition, the document detection sensor DS4 is disposed at a position where the document passes twice, and is used for obtaining the reading timing of the first surface of the document when transporting in the forward direction, and by the switching roller 19 when transporting in the reverse direction. This is used to obtain the timing for returning the document transport direction from the reverse direction to the forward direction. For this reason, a number of parts can be reduced and a product can be reduced in size.

<Flowchart of operation at document detection>
FIGS. 11 to 13 show an example of conveyance control of a long document by the document detection sensor DS4 or DS5, and FIGS. 14 and 15 show an example of conveyance control of a short document by the document detection sensors DS4 and DS5. FIG. 16 shows an example of conveyance control of a long document or a short document by the document detection sensor DS6.

  Steps S101 to S106 in FIG. 11 are flowcharts illustrating an example of processing when the leading edge of a long document is detected by the document detection sensor DS4. The process of this flowchart is started when a leading edge detection signal is output from the document detection sensor DS4 during double-sided reading of a long document. First, the transport position specifying unit 41 determines the number of leading edge detections for the same document (step S101). If the original is detected for the first time, that is, if the original is being transported in the forward direction, the original reading unit is detected when the transport position specifying unit 41 determines that a predetermined amount of transport has been performed from the detection position. 32 starts reading the first side of the document. Further, when the transport position specifying unit 41 determines that the leading edge of the document has been transported from the detection position to the reference position E4 on the transport path A5, the discharge roller 23 is configured so that the document on the long document U-turn path can be transported. Switches the direction of rotation from normal rotation to reverse rotation, and the process ends (step S103). On the other hand, if the document is detected for the second time, when the conveyance position specifying unit 41 determines that a predetermined amount of conveyance has been performed from the detection position, the conveyance control unit 42 removes the document from the conveyance path A9 side. The branch claw 21 at the branch point B5 is switched so as to be guided to (Step S104). At this time, the branching claw 22 at the branching point B6 is in a state of guiding the document to the conveyance path A10 side. Therefore, the document that has passed through the conveyance path A2 in the reverse direction is guided to the discharge path side.

  Further, when the transport position specifying unit 41 determines that the leading edge of the document has been transported from the detection position to the reference position E6 on the transport path A9, the discharge roller 23 can discharge the document on the discharge path from the discharge port 24. Then, the rotation direction is switched from reverse rotation to normal rotation (step S105). Further, the transport position specifying unit 41 specifies the trailing edge position of the document by subtracting the document length from the leading edge position of the document detected by the document detection sensor DS4, and the trailing edge position of the document is the reference position on the transport path A2. If it is determined that E2 has been passed, the feeding roller 15 starts feeding the next document and ends the process (step S106).

  Steps S201 to S204 in FIG. 12 are flowcharts showing an example of processing when the trailing edge of the long document is detected by the document detection sensor DS4. The process of this flowchart is started when a trailing edge detection signal is output from the document detection sensor DS4 when reading both sides of a long document. First, the transport position specifying unit 41 determines how many times the trailing edge has been detected for the same document (step S201). If the original is detected for the first time, the original reading unit 32 finishes reading the first surface of the original when the conveyance position specifying unit 41 determines that the predetermined amount of conveyance has been performed from the detection position. (Step S202). Further, when the conveyance position specifying unit 41 determines that the trailing edge of the document has been conveyed from the detection position to the reference position E5 on the conveyance path A3, the switching roller 19 changes the rotation direction so as to convey the document in the reverse direction. Switching from normal rotation to reverse rotation ends the processing (step S203).

  On the other hand, if the document is detected for the second time, when the transport position specifying unit 41 determines that the rear end of the document has been transported from the detection position to the reference position E7 on the transport path A2, the switching roller 19 Then, the rotation direction is switched from the reverse rotation to the normal rotation so that the next original is conveyed in the forward direction, and the process is terminated (step S204).

  Steps S301 to S305 in FIG. 13 are flowcharts showing an example of processing when the leading edge or trailing edge of the long document is detected by the document detection sensor DS5. The process of this flowchart is started when a leading edge detection signal or a trailing edge detection signal is output from the document detection sensor DS5 during double-sided reading of a long document. First, the transport position specifying unit 41 determines which of the leading edge and the trailing edge of the document has been detected (step S301). When the leading edge of the document is detected, the registration roller 20 reduces the rotation speed, and the leading edge of the document being conveyed is brought into contact with the registration roller 20, thereby correcting the skew of the document (step S302). Further, when the conveyance position specifying unit 41 determines that a predetermined time has elapsed since the leading edge detection signal of the document detection sensor DS5 has been input, the conveyance control unit 42 increases the rotation speed of the registration roller 20 to the conveyance path A2. The document is advanced in the reverse direction (step S303). Further, when the conveyance position specifying unit 41 determines that a predetermined amount of conveyance has been performed from the detection position, the document reading unit 32 starts reading the second surface of the document and ends the process (step S304).

  On the other hand, when the trailing edge of the document is detected, the document reading unit 32 finishes reading the second surface of the document when the conveyance position specifying unit 41 determines that the predetermined amount of conveyance has been performed from the detection position. (Step S305).

  Steps S401 to S403 in FIG. 14 are flowcharts showing an example of processing when the document detection sensor DS4 detects the leading edge of a short document. The processing of this flowchart is started when a leading edge detection signal is output from the document detection sensor DS4 when reading both sides of a short document. First, the transport position specifying unit 41 determines how many times the trailing edge has been detected for the same document (step S401). If the original is detected for the first time, when the conveyance position specifying unit 41 determines that a predetermined amount of conveyance has been performed from the detection position, the original reading unit 32 starts reading the original and performs processing. The process ends (step S402). On the other hand, if the document is detected for the second time, the transport position specifying unit 41 specifies the trailing edge position of the document by subtracting the document length from the leading edge position of the document detected by the document detection sensor DS4. When it is determined that the trailing edge position of the document has passed the reference position E2, the feeding roller 15 starts feeding the next document and ends the process (step S403).

  Further, the operation based on the trailing edge detection signal of the document detection sensor DS4 at the time of duplex reading of a short document is the same as the operation based on the trailing edge detection signal of the document detection sensor DS4 at the time of duplex scanning of a long document in FIG. Therefore, the description is omitted.

  Steps S501 to S506 in FIG. 15 are flowcharts showing an example of processing when the leading edge or trailing edge of the short document is detected by the document detection sensor DS5. The processing of this flowchart is started when a leading edge detection signal or a trailing edge detection signal is output from the document detection sensor DS5 during double-sided reading of a short document. First, the transport position specifying unit 41 determines which of the leading edge and the trailing edge of the document has been detected (step S501). Processing when the leading edge of the document is detected is the same as steps S302 to S304 in FIG. When the trailing edge of the document is detected, the conveyance control unit 42 guides the document to the conveyance path A10 side when the conveyance position specifying unit 41 determines that a predetermined amount of conveyance has been performed from the detection position. The branch claw 22 at the branch point B6 is switched (step S505). By this switching, the document that has passed through the conveyance path A2 in the reverse direction is guided onto the discharge path and discharged from the discharge port 24. When the conveyance position specifying unit 41 determines that a predetermined amount of conveyance has been performed from the detection position, the document reading unit 32 ends reading of the second surface of the document (step S506).

  Steps S601 to S604 in FIG. 16 are flowcharts illustrating an example of processing when the document detection sensor DS6 detects the trailing edge of a long document or a short document. The processing of this flowchart is started when a trailing edge detection signal is output from the document detection sensor DS6 when both sides of a long document or a short document are read. First, the transport position specifying unit 41 determines whether the trailing edge of the document has been detected (step S601). When the trailing edge of the document is detected, the transport position specifying unit 41 determines the document length of the document on the document table 13 based on the detection result of the document detection sensor DS2 (step S602). If the original on the platen 13 is a long original, a predetermined amount of conveyance is performed from the detection position, and conveyance control is performed when the conveyance position specifying unit 41 determines that the trailing edge of the original is discharged from the discharge port 24. The unit 42 switches the branching claw 21 at the branch point B5 so as to guide the next document to the long document U-turn path side, and the process ends (step S603).

  On the other hand, if the document on the document table 13 is a short document, the transport position specifying unit 41 transports a predetermined amount from the detection position, and the transport position specifying unit 41 determines that the rear end of the document is discharged from the discharge port 24. When the determination is made, the conveyance control unit 42 switches the branch claw 22 at the branch point B6 so as to guide the next document to the conveyance path A11 side (step S604). At this time, the branching claw 21 at the branching point B5 is in a state of guiding the document to the conveyance path A9 side. Therefore, the document that has passed through the conveyance path A2 in the opposite direction is guided to the upper side of the short document U-turn path.

  According to the present embodiment, since the document detection sensor DS4 is also used for obtaining the timing for switching the rotation direction of the discharge roller 23, the number of document detection sensors can be reduced. Further, a discharge roller 23 for discharging the document to the discharge port 24 is also used for transporting the document on the U-turn path. Therefore, the number of parts can be reduced.

  In addition, since the document detection sensor DS4 is also used for obtaining the feeding timing for feeding the next document from the document tray 11, the number of parts can be further reduced. Further, the document detection sensor DS4 determines the switching timing of the rotation direction of the switching roller 19 twice. For this reason, the number of parts can be further reduced.

  In the present embodiment, the configuration in which the feeding roller 15 feeds the next document based on the detection timing of the leading edge of the document by the document detection sensor DS4 has been described. However, the present invention is not limited to this. For example, the configuration may be such that the next document is fed based on the detection timing of the trailing edge of the document by the document detection sensor DS4.

Embodiment 2. FIG.
In the first embodiment, an example has been described in which the switching roller 19 is switched from reverse rotation to forward rotation and the original is fed based on the detection timing of the original detection sensor DS4. On the other hand, in the present embodiment, a case will be described in which the switching roller 19 is switched from reverse rotation to normal rotation and the original is fed based on the detection timing of the original detection sensor DS5. Since the configuration other than the switching roller 19 and the feeding roller 15 is the same as that of the first embodiment, the description thereof is omitted.

  Specifically, when the long original is conveyed, the switching roller 19 performs an operation of switching the rotation direction from reverse rotation to normal rotation based on the passage of the original with respect to the reference position E7 on the conveyance path A2. By this switching, the transport direction on the transport path A2 is switched from the reverse direction to the forward direction. In this case, in the present embodiment, the rotation direction is switched based on the detection timing of the document detection sensor DS5. That is, the conveyance position specifying unit 41 determines that the document trailing edge has been conveyed from the detection position to the reference position E7 based on the trailing edge detection signal of the document detection sensor DS5. In the present embodiment, the reference position E7 may be configured to coincide with the detection position of the document detection sensor DS4.

  Further, the feeding roller 15 starts feeding the next document based on the passage of the trailing edge of the document with respect to the reading position B2 when the long document is conveyed. In this case, based on the detection timing of the document detection sensor DS5, the transport position specifying unit 41 determines the passage of the trailing edge of the document with respect to the reading position B2, and the feeding roller 15 starts feeding the document.

  FIG. 17 is a flowchart showing an example of the operation when the leading edge of the long document is detected by the document detection sensor DS5 of the present embodiment. This flowchart is started when a leading edge detection signal or a trailing edge detection signal is output from the document detection sensor DS5 during duplex reading of a long document. First, the transport position specifying unit 41 determines which of the leading edge and the trailing edge of the document has been detected (step S701). The processing when the leading edge of the document is detected is the same as steps S302 to S304 in FIG. When the trailing edge of the document is detected, the document reading unit 32 finishes reading the second surface of the document when the transport position specifying unit 41 determines that a predetermined amount of transport has been performed from the detection position (step S705). ). When the conveyance position specifying unit 41 determines that the trailing edge of the document has been conveyed from the detection position to the reference position E2, the feeding roller 15 starts feeding the next document (step S706). Further, when the conveyance position specifying unit 41 determines that the document trailing edge has been conveyed from the detection position to the reference position E7 on the conveyance path A2, the switching roller 19 rotates in the rotation direction so as to convey the document in the forward direction. Is switched from reverse rotation to normal rotation, and the process is terminated (step S707).

  FIG. 18 is a flowchart showing an example of the operation when the leading or trailing edge of the short document is detected by the document detection sensor DS5 of the present embodiment. Since operations other than step S805 are the same as steps S701 to S707 in FIG. 17, description thereof will be omitted and the operation of step S805 will be described. That is, when the trailing edge of the document is detected, the conveyance control unit 42 guides the document to the conveyance path A10 side when the conveyance position specifying unit 41 determines that a predetermined amount of conveyance has been performed from the detection position. Thus, the branch claw 22 at the branch point B6 is switched (step S805). By this switching, the document that has passed through the conveyance path A2 in the reverse direction is guided to the discharge path and discharged from the discharge port 24. Thereafter, the process proceeds to step S806.

  Further, the operation based on the leading edge detection signal or trailing edge detection signal of the document detection sensor DS4 at the time of double-sided reading according to the present embodiment does not transfer the document (step S106 in FIG. 11 and step S403 in FIG. 14). Except for the fact that the switching roller 19 is not switched from reverse rotation to forward rotation (step S204 in FIG. 12), the flow chart is the same as the flowchart shown in FIGS. Similarly, the operation based on the original detection of the original detection sensor DS6 is the same as steps S601 to S604 in FIG.

  According to the present embodiment, by switching the rotation direction of the switching roller 19 disposed on the transport path A2, the document can be passed through the document reading unit 32 in two directions, and the document transport roller. The number of can be reduced. In addition, the document detection sensor DS5 is used for determining the reading timing of the second surface of the document, and is also used for determining the timing for returning the document transport direction by the switching roller 19 from the reverse direction to the forward direction. For this reason, the number of parts can be reduced. Therefore, the product cost can be reduced, or an increase in product size can be suppressed.

  In addition, the document detection sensor DS5 is commonly used to obtain timing for increasing the rotation speed of the registration roller 20 after the skew correction of the document is completed. For this reason, the number of parts can be further reduced. In addition, since the skew of the document can be corrected before reading the second side of the document, for example, even when the skew occurs when the document is made a U-turn, the scanned image of the second side of the document is read. It is possible to suppress the occurrence of displacement in the case.

  In the first and second embodiments, the example in which the skew of the original is corrected by the registration rollers 17 and 20 has been described. However, the present invention is not limited to this. For example, the skew correction of the document may be corrected only by the registration roller 17.

  In the first and second embodiments, the configuration has been described in which the document detection sensor DS2 detects the maximum length of the document placed on the document table 13, but the present invention is not limited to this. For example, the document length may be measured by measuring the document conveyance amount from when the leading edge detection signal of the document detection sensor DS4 is generated until the trailing edge detection signal is generated.

  In the first and second embodiments, the configuration in which the branching claw 21 is switched so as to guide the document to the conveyance path A5 side based on the detection timing of the document detection sensor DS6 when reading both sides of a long document has been described. Further, the description has been given of the configuration in which the branching claw 22 is switched so that the document is guided to the conveyance path A11 side based on the detection timing of the document detection sensor DS6 when reading both sides of the short document. However, the present invention is not limited to the configuration in which the branch claws 21 and 22 are switched based on the detection timing of the document detection sensor DS6. For example, the configuration may be such that the branch claws 21 and 22 are switched based on the detection timing of the document detection inspection DS4 or DS5.

DESCRIPTION OF SYMBOLS 10 ADF apparatus 11 Document tray 12 Discharge tray 13 Document stand 14 Document stopper 15 Feed roller 16a Separation roller 16b Retard roller 17, 20 Registration roller 18 Transfer roller 19 Switching roller 21, 22 Branch claw 23 Discharge roller 24 Discharge port 30 MFP main body Unit 32 Document Reading Unit 41 Transport Position Specifying Unit 42 Transport Control Unit 43 Feeding Control Unit 100 Multifunction Devices A1 to A11 Transport Paths DS1 to DS6 Document Detection Sensor

Claims (7)

A reading conveyance path capable of conveying the document in the forward direction and the reverse direction;
An introduction path through which the document fed from the document tray enters the reading conveyance path in a forward direction;
A U-turn path for U-turning the document that has passed through the reading conveyance path in the forward direction and entering the reading conveyance path in a reverse direction;
A discharge path for transporting the document that has passed through the reading transport path in the reverse direction to a discharge port;
An original detection sensor disposed on the reading conveyance path for detecting the original;
An original reading means disposed on the reading and conveying path for reading the first surface of the original when transporting in the forward direction and reading the second surface of the original when transporting in the reverse direction;
A switching roller provided on the reading conveyance path and capable of switching a rotation direction;
The original reading means reads the first surface of the original based on the detection timing of the original being conveyed in the forward direction by the original detection sensor,
The switching roller switches the document transport direction from the reverse direction to the forward direction by switching the rotation direction based on the detection timing of the document being transported in the reverse direction by the document detection sensor. Reader. Located at the intersection where the discharge path and the U-turn path intersect, the original on the U-turn path enters the reading conveyance path during reverse rotation, and the original on the discharge path is conveyed to the discharge port during normal rotation Equipped with a discharge roller
2. The document reading apparatus according to claim 1, wherein the discharge roller switches the rotation direction from reverse rotation to normal rotation based on a detection timing of the document being conveyed in the reverse direction by the document detection sensor.   The switching roller switches the document transport direction from the reverse direction to the forward direction by switching the rotation direction based on the detection timing of the document trailing edge being transported in the reverse direction by the document detection sensor. The document reading device according to claim 1.   2. The document reading apparatus according to claim 1, further comprising document feeding means for feeding a next document from the document tray based on a detection timing of the document being conveyed in the reverse direction by the document detection sensor. .   The switching roller switches the document transport direction from the forward direction to the reverse direction by switching the rotation direction based on the detection timing of the document being transported in the forward direction by the document detection sensor. Item 2. The document reading device according to Item 1. A reading conveyance path capable of conveying the document in the forward direction and the reverse direction;
An introduction path through which the document fed from the document tray enters the reading conveyance path in a forward direction;
A U-turn path for U-turning the document that has passed through the reading conveyance path in the forward direction and entering the reading conveyance path in a reverse direction;
A discharge path for transporting the document that has passed through the reading transport path in the reverse direction to a discharge port;
An original detection sensor disposed on the U-turn path for detecting the original;
An original reading means disposed on the reading and conveying path for reading the first surface of the original when transporting in the forward direction and reading the second surface of the original when transporting in the reverse direction;
A switching roller provided on the reading conveyance path and capable of switching a rotation direction;
The document reading means reads the second surface of the document being conveyed in the reverse direction based on the detection timing by the document detection sensor,
The document reading apparatus, wherein the switching roller switches the document transport direction from the reverse direction to the forward direction by switching the rotation direction based on the detection timing of the document detection sensor. A registration roller that is disposed on the U-turn path and corrects the skew of the document by reducing the conveyance speed of the document;
The document reading apparatus according to claim 6, wherein the registration roller increases the conveyance speed based on a detection timing of the document detection sensor.

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