JP2013074545A - Document reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a document reader capable of reducing the power consumption of a switching mechanism in a rotational direction of a conveyance roller.SOLUTION: A document length measuring unit 81 measures a document length. A switching roller 19 or 23, which can switch a rotational direction to one of a forward rotation state and a backward rotation state, conveys a document. A rotational direction control unit 84 controls the rotational direction. The switching roller 19 or 23 consumes greater power in the backward rotation state than that in the forward rotation state. Further, the rotational direction control unit 84 controls the rotational direction on the basis of the document length so as to shorten time for setting the backward rotation state when the document length is short.

Description

  The present invention relates to a document reading apparatus, and more particularly to an improvement of a document reading apparatus that can switch the rotation direction of a transport roller for transporting a document.

  2. Description of the Related Art Document reading apparatuses that can automatically convey two or more documents and sequentially read these documents are widely used. An original reading apparatus that can read both sides of an original by automatic conveyance is also 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.

  In double-sided scanning of the 2-pass 1-scanner method, a switchback method for switching the conveyance direction during conveyance of a document, and a U-turn path and a switchback method for allowing the document to pass through the image sensor twice in the same direction are used. Thus, a U-turn system is conceivable in which the conveyance paths are crossed and the document passes through one image sensor twice in the opposite direction.

  For example, in U-turn double-sided scanning, a conveyance roller capable of switching the rotation direction is arranged around the image sensor, and by switching this rotation direction, an original is passed twice in the reverse direction with respect to one image sensor. ing.

  Patent Document 1 describes a document reading apparatus that performs switchback double-sided reading. In this document reading device, the position of some gears is changed using a solenoid to increase or decrease the number of gears that transmit the rotational driving force of the motor, thereby switching the rotation direction of the conveying roller.

JP 2009-286632 A

In the configuration described in Patent Document 1, the rotation direction of the conveyance roller is switched without switching the rotation direction of the drive motor by switching the rotation direction of the conveyance roller using a solenoid. For this reason, it is necessary to continue driving the solenoid during the period in which the transport roller rotates in either direction, and there is a problem in that power consumption increases.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a document reading apparatus capable of reducing power consumption by a mechanism for switching a rotation direction of a conveyance roller.

  An original reading apparatus according to a first aspect of the present invention includes an original length measuring unit that measures an original length, a switching roller that conveys an original and can switch a rotation direction between a normal rotation state and a reverse rotation state, and the rotation direction. A rotation direction control means for controlling the rotation direction, and the switching roller consumes more power in the reverse rotation state than in the normal rotation state, and the rotation direction control means determines the original length based on the original length. If it is short, the rotation direction is controlled so that the time for the reverse rotation state is short.

  According to such a configuration, since the rotation direction of the switching roller is controlled so that the time for the reverse rotation state is shortened when the document length is short, the period of the reverse rotation state with high power consumption can be further shortened. . For this reason, power consumption due to switching of the rotation direction of the switching roller can be reduced.

  A document reading apparatus according to a second aspect of the present invention includes, in addition to the above configuration, a drive motor that generates a rotational force and a plurality of gears, and the rotational force of the drive motor is applied to the switching roller so that the rotational directions are different from each other. Based on a control signal from the first and second rotational force transmitting means and the rotational direction control means for transmitting the rotational force transmitted by the first rotational force transmitting means to the switching roller and the rotational force An electromagnetic clutch for switching the shut-off state for shutting off, and a selection clutch for shutting off the rotational force by the second rotational force transmission means in the transmission state, wherein the electromagnetic clutch is consumed in the transmission state compared to the shut-off state. The electric power is large, and the first rotational force transmitting means is configured to rotate the switching roller in the reverse rotation state.

  According to such a configuration, in the transmission state, the rotational force from the first rotational force transmission means is transmitted to the switching roller by the electromagnetic clutch, and the switching roller is in the reverse rotation state. On the other hand, in the shut-off state, the rotational force by the first rotational force transmission means is interrupted by the electromagnetic clutch, and the rotational force by the second rotational force transmission means is transmitted to the switching roller, so that the switching roller is in the normal rotation state. . In this case, since the rotation direction of the switching roller is controlled so that the period of the reverse rotation state is shortened if the document length is short, the period of the transmission state in which the power consumption of the electromagnetic clutch is large can be further shortened.

  A document reading apparatus according to a third aspect of the present invention includes, in addition to the above configuration, a drive motor that generates a rotational force, a plurality of gears, and a rotational force transmission unit that transmits the rotational force of the drive motor to the switching roller. And a solenoid for switching between the first and second connected states having different rotational directions based on a control signal of the rotational direction control means, wherein the solenoid varies the number of gears for transmitting the rotational force. Thus, the first and second connected states are switched, and the power consumption of the solenoid is larger in the first connected state than in the second connected state, and the rotational force transmitting means is in the reverse rotation state as the switching roller. Configured to rotate.

  According to such a configuration, the direction of the rotational force transmitted from the drive motor is reversed by changing the number of gears that transmit the rotational force using a solenoid. For this reason, since the rotation direction of the switching roller can be switched with a simple configuration, the document reading apparatus can be downsized and the product cost can be reduced. Further, since the rotation direction of the switching roller is controlled so that the period of the reverse rotation state is shortened when the document length is short, the period of the second connection state in which the power consumption of the solenoid is large can be further shortened.

  According to a fourth aspect of the present invention, there is provided a document reading apparatus which, in addition to the above-described configuration, makes a U-turn on a document reading means for reading a document conveyed on a reading path and a document after reading on the first surface, and again returns to the reading path in the reverse direction. And a discharge path for discharging the document after reading the second surface, and the switching roller is configured to be disposed in the reading path.

  According to a fifth aspect of the present invention, there is provided a document reading apparatus, in addition to the above configuration, a document reading means for reading a document conveyed on a reading path, and a U-turn for the document after reading the first surface, and again in the reverse direction to the reading path. A U-turn path for entering the paper and a discharge path for discharging the original after reading the second surface, wherein the switching roller is disposed between the U-turn path and the discharge path. It is comprised so that it may be arrange | positioned at the cross | intersection part.

  A document reading apparatus according to a sixth aspect of the present invention is capable of switching between an open state and a closed state in addition to the above-described configuration, and in the closed state, a re-transfer that suppresses re-transfer of the document discharged from the discharge path And a shutter control means for controlling the open / close state so as to be in the closed state in the reverse rotation state, and the re-reduction suppression shutter has a power consumption in the closed state as compared with the open state. Largely, the shutter control means is configured to switch the open / close state based on the original length so that if the original length is short, the time for the closed state is shortened.

  According to such a configuration, since the re-feeding suppression shutter suppresses the re-feeding of the document that has been discharged, the document is transported even when the rotation direction of the switching roller is switched before the document leaves the switching roller. It is possible to suppress re-feeding into the road. In addition, since the open / close state is switched so as to be in the closed state in the case of the reverse rotation state, the time for the close state can be varied based on the document length, similarly to the switching of the rotation direction of the switching roller. Therefore, the period during which the power consumption is closed can be shortened.

  A document reading apparatus according to a seventh aspect of the present invention includes document detection means for detecting a document being conveyed in addition to the above-described configuration, and the document length measurement means is configured such that the leading edge of the document reaches the detection position of the document detection means. The document length is measured based on the time from the end of the document until the trailing edge of the document passes the detection position.

  According to such a configuration, the document length is measured based on the time from when the leading edge of the document reaches the detection position of the document detection means until the trailing edge of the document passes the detection position. For this reason, even when originals with different original lengths are mixedly loaded, the original length of each original can be measured. Accordingly, the document length can be measured with higher accuracy, and the period during which the switching roller is in the reverse rotation state with high power consumption can be further shortened.

  According to an eighth aspect of the present invention, there is provided a document reading apparatus, in addition to the above configuration, a document length measuring unit for measuring a document length, a front and rear end specifying unit for specifying a leading end position and a trailing end position of a document, a document transporting and rotating Rotation direction control that controls the rotation direction and switches the rotation direction from the normal rotation state to the reverse rotation state based on the tip position based on a switching roller that can switch the direction between the normal rotation state and the reverse rotation state. And the switching roller consumes more power in the reverse rotation state than in the normal rotation state, and the rotation direction control means is in the reverse rotation state if the document length is short based on the rear end position. So that the time required to return from the reverse rotation state to the normal rotation state is made different.

  According to such a configuration, since the rotation direction is switched from the normal rotation state to the reverse rotation state based on the leading edge position of the document, the rotation direction can be switched before the leading edge of the document reaches the switching roller. Also, since the time until the rotation direction is returned from the reverse rotation state to the normal rotation state is made different so that the time for the reverse rotation state is shortened if the document length is short, the period of the reverse rotation state with high power consumption is further shortened. be able to. For this reason, the power consumption by switching the rotation direction of the switching roller can be reduced.

  Since the document reading apparatus according to the present invention controls the rotation direction of the switching roller so that the time for the reverse rotation state is shortened when the document length is short, the period of the reverse rotation state with high power consumption can be further shortened. . For this reason, power consumption due to switching of the rotation direction of the switching roller can be reduced.

  Further, since the rotation direction is switched from the normal rotation state to the reverse rotation state based on the leading edge position of the document, the rotation direction can be switched before the leading edge of the document reaches the switching roller. Also, since the time until the rotation direction is returned from the reverse rotation state to the normal rotation state is made different so that the time for the reverse rotation state is shortened if the document length is short, the period of the reverse rotation state with high power consumption is further shortened. be able to. For this reason, the power consumption by switching the rotation direction of the switching roller can be reduced.

1 is an external view showing a configuration example of a document reading device according to an embodiment of the present invention, and shows a multifunction peripheral 100 as an example of a document reading device. FIG. 2 is a cross-sectional view illustrating a configuration example of a main part of the multifunction peripheral 100 of FIG. 1. FIG. 6 is an explanatory diagram of single-sided scanning, and shows the state of document transport on transport paths A1 to A11 in chronological order. FIG. 5 is an explanatory diagram of double-sided scanning of a short document, in which document transport states on transport paths A1 to A11 are shown in chronological order. FIG. 5 is an explanatory diagram of double-sided scanning of a short document, in which document transport states on transport paths A1 to A11 are shown in chronological order. FIG. 5 is an explanatory diagram of double-sided scanning of a short document, in which document transport states on transport paths A1 to A11 are shown in chronological order. FIG. 5 is an explanatory diagram of double-sided scanning of a long document, and shows the document conveyance state on the conveyance paths A1 to A11 in time-series order. FIG. 5 is an explanatory diagram of double-sided scanning of a long document, and shows the document conveyance state on the conveyance paths A1 to A11 in time-series order. FIG. 5 is an explanatory diagram of double-sided scanning of a long document, and shows the document conveyance state on the conveyance paths A1 to A11 in time-series order. FIG. 2 is an explanatory diagram illustrating an example of a main part of the multifunction peripheral 100 of FIG. 1. It is explanatory drawing which showed the selection clutch 62 of FIG. FIG. 2 is an explanatory diagram illustrating an example of a main part of the multifunction peripheral 100 of FIG. 1. FIG. 2 is an explanatory diagram illustrating an example of a main part of the multifunction peripheral 100 of FIG. 1. FIG. 2 is a functional block diagram illustrating a configuration example of a main part of the MFP 100 in FIG. 1. It is the flowchart which showed an example of operation | movement of the switching roller 19 at the time of double-sided reading. It is the flowchart which showed an example of operation | movement of the switching roller 19 at the time of double-sided reading. 5 is a flowchart showing an example of the operation of the switching roller 23 when reading a long original on both sides. 6 is a time chart showing the relationship between the switching of the rotation direction of the switching roller 23 and the switching of the open / closed state of the re-feeding suppression shutter 24; It is the functional block diagram which showed one structural example about the principal part of the multifunction device 200 by Embodiment 2 of this invention.

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 transport path A2 is a reading path capable of transporting a document bidirectionally, and the document reading unit 32 reads a document that passes through a reading position B2 on the transport 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 conveyance paths A8, A4, A9, and A10 constitute a discharge path for conveying the long document or the short document that has passed through the conveyance path A2 in the reverse direction to the discharge port 25 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 25. 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 or 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 drive motor, and the plurality of transport rollers 18, the switching roller 19, and the switching roller 23 are driven by the second drive motor. It shall be driven.

<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 driving motor using an electromagnetic 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 drive motor drives the conveyance roller 18, the switching roller 19, and the switching roller 23, respectively. At this time, the switching roller 19 and the switching 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 in the forward rotation state, and conveys the document in the reverse direction in the reverse rotation state. The rotation direction of the switching roller 19 is reversed by using, for example, a solenoid and an electromagnetic clutch.

<Switching roller 23>
The switching roller 23 is a transport roller capable of switching the rotation direction, and is disposed at an intersection B8 between the transport path A5 and the transport path A10. In the forward rotation state, the switching roller 23 discharges the document on the conveyance path A10 from the discharge port 25 to the discharge tray 12. In the reverse rotation state, the document on the transport path A5 enters the transport path A6. The direction of rotation of the switching roller 23 is reversed by, for example, switching on and off the electromagnetic clutch that transmits the rotational force to the switching roller 23.

<Re-transfer suppression shutter 24>
The re-transfer suppression shutter 24 is a re-transfer suppression unit that is disposed in the vicinity of the switching roller 23 and suppresses the re-transfer of the document discharged from the discharge port 25. For example, when the document is in contact with the switching roller 23 when the document is discharged, the document is prevented from being fed again to the conveyance path A7 side by the reverse rotation of the switching roller 23.

<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 25 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, but thereafter, the originals do not make a U-turn, and the conveyance paths A3, A4, A9, It discharges to the discharge port 25 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, it is assumed that the document detection sensor DS5 detects the document immediately before reaching the reading position B2. The document detection sensor DS5 is a sensor for obtaining the timing of the reading start and the reading end of the second surface by the document reading unit 32.

  The document detection sensor DS6 is disposed upstream of the switching roller 23 on the conveyance path A10, and detects the trailing edge of the document discharged from the discharge port 25.

  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. In particular, since the switching roller 19 can convey the document bidirectionally, high-speed conveyance of the document on the reading path can be realized without increasing the number of components such as the conveyance roller and increasing the size of the multifunction peripheral 100. it can.

  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 switching 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 6G are explanatory diagrams for 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. Further, 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 the normal rotation state to the reverse rotation state. 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. Thereafter, the document enters the transport path A2 in the reverse direction.

  As shown in FIGS. 4C to 5F, 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. 5D, 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. The reference position E2 may be configured to coincide with the reading position B2.

  At the branch point B5, the document is guided from the transport path A4 to the transport path A9 by the branch claw 21. Further, as shown in FIG. 5E, when the trailing edge of the document passes the switching roller 19, the rotation direction of the switching roller 19 is switched again from the reverse rotation state to the normal rotation state. At the branch point B6, the original 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. 5F). Further, as shown in FIG. 6G, 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 9H are explanatory diagrams for the double-sided reading of a long document, and the 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 E3 on the conveyance path A5, the rotation direction of the switching roller 23 is switched from the normal rotation state to the reverse rotation state.

  Further, as shown in FIG. 7C, 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 the normal rotation state to the reverse rotation state. The arrival of the document front end at the reference position E1 is determined, for example, by measuring the transport distance of the document front end from the detection position of the document detection sensor DS5. Thereafter, the document enters the transport path A2 in the reverse direction.

  Further, as shown in FIGS. 8D to 8F, 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. 8E, when the trailing edge of the document passes the switching roller 23, the rotation direction of the switching roller 23 is switched from the reverse rotation state to the normal rotation state. Further, as shown in FIG. 8F, 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.

  Also, as shown in FIG. 9G, when the trailing edge of the document passes the switching roller 19, the rotation direction of the switching roller 19 is switched from the reverse rotation state to the normal rotation state. Thereafter, as shown in FIG. 9 (h), 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.

  FIG. 10 is an explanatory diagram showing an example of a main part of the multifunction peripheral 100 of FIG. The rotational force transmission unit 50 is a rotational force transmission unit that transmits the rotational force of the drive motor 51 to the switching roller 23, and includes the drive motor 51, fixed gears 52 to 59, 61, an electromagnetic clutch 60, and a selection clutch 62. .

  The drive motor 51 is a drive unit that generates a rotational force, and rotates the shaft 51a. This drive motor 51 consists of a stepping motor, for example. The fixed gears 52 to 59, 61 are disk-shaped gears that rotate about the rotation axis. The electromagnetic clutch 60 is a coupler that transmits or interrupts the rotational force transmitted from the fixed gear 59 to the fixed gear 61. For example, in a state where power is supplied to the electromagnetic clutch 60, the driving side and the driven side of the electromagnetic clutch 60 come into contact with each other by the electromagnetic force generated by the internal coil, and the rotational force from the fixed gear 59 is fixed. It is transmitted to the gear 61. On the other hand, in a state where the power supply to the electromagnetic clutch 60 is not performed, the driving side and the driven side are not in contact with each other due to the biasing force of the internal elastic member, and the rotational force from the fixed gear 59 is cut off. Hereinafter, a state in which power supply to the electromagnetic clutch 60 is performed is referred to as a transmission state, and a state in which power supply to the electromagnetic clutch 60 is not performed is referred to as a cutoff state.

  The selection clutch 62 is a coupler that selectively transmits the rotational force from the fixed gear 58 or 61 to the switching roller 23. Here, it is assumed that the selection clutch 62 is composed of a torque limiter that transmits only a predetermined or less rotational force.

  As indicated by the upper broken line in FIG. 10, the shaft 51a of the drive motor 51, the fixed gears 52, 53, 54, 55, 56, 57, 58 and the selection clutch 62 are connected in this order. For this reason, the rotational force of the drive motor 51 is transmitted in this order, and the switching roller 23 is driven forward. That is, the plurality of fixed gears 52 to 58 and the selection clutch 62 constitute a normal rotation side torque transmission unit for driving the switching roller 23 to rotate in the normal direction.

  Furthermore, as indicated by the broken lines on the lower side of FIG. 10, the fixed gears 54 and 59, the electromagnetic clutch 60, the fixed gear 61, and the selection clutch 62 are connected in this order. That is, the rotational force transmitted from the drive motor 51 to the fixed gear 54 is transmitted to the selection clutch 62 via the fixed gear 59, the electromagnetic clutch 60, and the fixed gear 61. In this case, since the number of gears passing through is different from that of the forward rotation torque transmission unit, the switching roller 23 is driven in reverse. That is, the plurality of fixed gears 52 to 54, 59, 61, the electromagnetic clutch 60, and the selection clutch 62 constitute a reverse rotation torque transmission unit for driving the switching roller 23 in the reverse rotation direction. The forward rotation torque transmission unit and the reverse rotation force transmission unit are each composed of a plurality of gears, and transmit the rotation force of the drive motor 51 to the switching roller 23 so that the rotation directions of the switching roller 23 are different from each other. And second rotational force transmission means.

  Therefore, in the transmission state in which the power supply to the electromagnetic clutch 60 is performed, the rotational directions of the stationary gear 58 of the normal rotation side rotational force transmission unit and the fixed gear 61 of the reverse rotation side rotational force transmission unit are different from each other. The rotational force is transmitted to the selection clutch 62. In this case, since the rotational force exceeding the upper limit is applied to the selection clutch 62, the rotational force from the fixed gear 58 is interrupted. For this reason, the switching roller 23 is reversely driven by the rotational force transmitted from the fixed gear 61.

  On the other hand, in the shut-off state in which power supply to the electromagnetic clutch 60 is not performed, the rotational force transmitted by the fixed gear 59 of the reverse-rotation-side rotational force transmitting unit is cut off by the electromagnetic clutch 60. For this reason, the rotational force is transmitted to the selection clutch 62 only from the fixed gear 58 of the forward rotation side rotational force transmission unit. In this case, since the rotational force applied to the selection clutch 62 is smaller than the upper limit, the rotational force of the fixed gear 58 is transmitted to the switching roller 23 via the selection clutch 62, and the switching roller 23 is driven to rotate forward.

  That is, in the transmission state in which the switching roller 23 is driven in the reverse direction, power is supplied to the electromagnetic clutch 60, so that the power consumption is larger than in the cutoff state in which the switching roller 23 is driven in the forward direction.

  FIG. 11 is an explanatory view showing the selection clutch 62 of FIG. The selection clutch 62 is a coupler that transmits only a predetermined or less rotational force to the inner shaft 623, and includes, for example, a torque limiter. The selection clutch 62 includes an external housing 621, a coil spring 622, and an inner shaft 623. The external housing 621 is a member having a cylindrical shape, and is connected to the fixed gear 58 of the forward rotation side torque transmission unit. The rotational force of the fixed gear 58 is transmitted to the external housing 621.

  The inner shaft 623 has the same rotation axis as the switching roller 23 and rotates in conjunction with the switching roller 23. The inner shaft 623 is connected to the fixed gear 61 of the reverse rotation side torque transmission unit, and the torque of the fixed gear 61 is transmitted. In addition, the external casing 621 is connected via a coil spring 622. The coil spring 622 is an elastic member that is spirally wound around the outer peripheral surface of the inner shaft 623, and fastens the inner shaft 623 with a certain contraction force. Further, both ends of the coil spring 622 are fixed to the external housing 621, respectively, and the coil spring 622 rotates in conjunction with the external housing 621.

  In the transmission state in which the rotational force from the fixed gear 61 is transmitted, the rotational force of the fixed gear 58 is transmitted to the external housing 621, and a rotational force having a rotational direction different from that of the fixed gear 58 is generated from the fixed gear 61. It is transmitted to the shaft 623. Therefore, a force exceeding the tightening force of the coil spring 622 against the inner shaft 623 is applied between the outer housing 621 and the inner shaft 623. For this reason, the coil spring 622 idles and the rotational force of the fixed gear 58 is not transmitted to the inner shaft 623. Therefore, the switching roller 23 is driven in reverse by the rotational force of the fixed gear 61.

  On the other hand, in the shut-off state in which the rotational force from the fixed gear 61 is not transmitted, only the rotational force of the fixed gear 58 is transmitted, so that the rotational force applied between the external housing 621 and the inner shaft 623 is the coil spring 622. The tightening force becomes smaller. For this reason, the inner shaft 623 rotates together with the external housing 621 by the tightening force of the coil spring, and the rotational force of the fixed gear 58 is transmitted to the switching roller 23. Accordingly, the switching roller 23 is driven forward by the rotational force of the fixed gear 58.

  FIG. 12 is an explanatory view showing an example of a main part of the multifunction peripheral 100 of FIG. 1 and shows a rotational force transmission unit 70 that transmits the rotational force of the drive motor 51 to the switching roller 19. FIG. 12A shows a connected state of the rotational force transmitting unit 70 in the forward rotation state, and FIG. 12B shows a connected state of the rotational force transmitting unit 70 in the reverse state.

  The rotational force transmission unit 70 includes two or more gears, and is rotational force transmission means that transmits the rotational force of the drive motor 51 to the switching roller 19. As illustrated in FIG. 12A, the rotational force transmission unit 70 includes an electromagnetic clutch 71, a solenoid SND 1, a fixed gear 72, moving gears 73 to 75, a plate 76, and a shaft 19 a of the switching roller 19. The electromagnetic clutch 71 is a coupler that transmits or interrupts the rotational force transmitted from the drive motor. The solenoid SND1 is a driving unit that moves the movable iron core SND1a in a linear direction according to the supply state of power. For example, when the power is supplied, the movable iron core SND1a is sucked, and when the power supply is stopped, the movable iron core SND1a is projected by a biasing means such as a spring (not shown). The fixed gear 72 is a gear that rotates around the rotation shaft 72A. The moving gears 73 to 75 are respectively arranged on the plate 76. The plate 76 is a plate-like member whose upper end is connected to the movable iron core SND1a of the solenoid SND1, and is configured to be rotatable around the rotation shaft 72A of the fixed gear 72. Further, when the plate 76 rotates, the moving gears 73 to 75 on the plate 76 move.

  In the connected state of FIG. 12A, the power supply to the solenoid SND1 is not performed, and the movable iron core SND1a of the solenoid SND1 protrudes by an urging force such as a spring. Further, as shown by a broken line in FIG. 12A, the electromagnetic clutch 71, the fixed gear 72, the moving gears 73 and 74, and the shaft 19a are connected in this order. Further, the moving gear 75 is connected to the moving gear 74. The drive motor 51 is connected to the electromagnetic clutch 71. For this reason, the rotational force of the drive motor 51 is transmitted in the order of the electromagnetic clutch 71, the fixed gear 72, the moving gears 73 and 74, and the shaft 19a, and the switching roller 19 is driven to rotate forward.

  Solenoid SND1 performs the operation | movement which attracts | sucks the movable iron core SND1a of solenoid SND1, if a power supply is performed. In this case, the plate 76 connected to the movable iron core SND1a rotates clockwise around the rotation shaft 72A, and the moving gears 73 to 75 arranged on the plate 76 move leftward. Further, the moving gear 75 is connected between the moving gear 74 and the shaft 19a, resulting in the connected state of FIG. At this time, the arrangement of the electromagnetic clutch 71, the fixed gear 72, and the shaft 19a is the same as in FIG.

  In this connected state, as indicated by the broken line in FIG. 12B, the electromagnetic clutch 71, the fixed gear 72, the moving gears 73, 74, 75, and the shaft 19a are connected in this order, and the rotational force of the drive motor 51 is in this order. Communicated. That is, compared with the state of FIG. 12A, the number of gears connected between the drive motor 51 and the shaft 19a is increased by one, so the rotation direction of the shaft 19a is reversed and the switching roller 19 is driven in reverse. Is done. In this way, the rotational force transmitting unit 70 can switch between two connected states having different rotational directions, and the number of gears that transmit the rotational force varies depending on the biasing force of the solenoid SND1, so that the two connected states are changed. Switching. In this case, in the connected state in which the switching roller 19 is in the reverse rotation state, power is supplied to the solenoid SND1, so that the power consumption is larger than in the connected state in which the switching roller 19 is in the normal rotation state. Further, when the power supply to the solenoid SND1 is stopped, the attracted movable core SND1a is projected again. In this case, the plate 76 rotates counterclockwise to return to the state of FIG.

  Here, in order to prevent the gear from being damaged due to switching of the connected state, the supply of power to the solenoid SND1 is started after the rotational force transmitted from the drive motor 51 is interrupted by stopping the power supply to the electromagnetic clutch 71. An operation or a stop operation shall be performed.

  FIG. 13 is an explanatory diagram illustrating an example of a main part of the multifunction peripheral 100 of FIG. 1, in which the re-reduction suppression shutter 24 is illustrated. FIG. 13A shows an open state where re-reduction is not suppressed, and FIG. 13B shows a closed state where re-reduction is suppressed.

  The re-transfer suppression shutter 24 is a re-transfer suppression unit that is disposed in the vicinity of the switching roller 23 and suppresses the re-transfer of the document discharged from the discharge port 25. The re-feed suppression shutter 24 can be switched between an open state and a closed state. In the closed state, the re-feed suppression shutter 24 suppresses the re-transfer of the document discharged from the discharge path, and suppresses the re-transfer in the open state. Absent. As shown in FIG. 13A, the re-reduction suppression shutter 24 includes a front end portion 24a, an arm portion 24b, and a rotating shaft 24c. The front end portion 24a is formed with an extrusion surface for extruding the document in contact with the switching roller 23 to the discharge port 25 side. The arm part 24b is a U-shaped member having a tip part 24a formed at one end and the other end connected to the rotating shaft 24c. Moreover, the front-end | tip part 24a and the arm part 24b are formed so that rotation is possible centering | focusing on the rotating shaft 24c.

  In the forward rotation state, the switching roller 23 discharges the document transported on the transport path A <b> 10 from the discharge port 25 to the discharge tray 12. At this time, the document may be in contact with the switching roller 23 and may not be discharged from the discharge port 25. If the rotation direction of the switching roller 23 is switched to the reverse rotation state while the document is in contact with the switching roller 23, the document may be brought into the conveyance path again and contact with another document to cause a paper jam. is there.

  In order to suppress this re-transfer, the re-transfer suppression shutter 24 rotates from the open state shown in FIG. 13 (a) to the closed state shown in FIG. 13 (b), and is formed at the distal end portion 24a. An operation of pushing out the document to the discharge port 25 side by the pushing surface is performed. At this time, since the position of the switching roller 23 and the re-reduction suppression shutter 24 in the depth direction is different, they do not contact each other when the re-reduction suppression shutter 24 rotates. In addition, the re-transfer suppression shutter 24 is rotated by a solenoid (not shown). That is, in a state where power is supplied to the solenoid, the re-retention suppression shutter 24 is rotated and closed by the action of the solenoid. On the other hand, when power is not supplied to the solenoid, the re-retention suppression shutter 24 returns to the open state by the biasing force of an elastic member (not shown). That is, the power consumption in the closed state is larger than that in the open state.

  FIG. 14 is a functional block diagram showing a configuration example of the main part of the multifunction peripheral 100 of FIG. The multifunction machine 100 includes a document detection sensor DS2, DS4 to DS6, a document length measurement unit 81, a passage time calculation unit 82, a tip position specifying unit 83, a document reading unit 32, a rotation direction control unit 84, a shutter control unit 85, and a solenoid SND1. , The switching roller 19, the electromagnetic clutch 60, the switching roller 23, the solenoid SND 2, and the re-reduction suppression shutter 24.

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

  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 reading position B2 on the conveyance path A7 and detects the document immediately before reaching the reading position B2.

  The document detection sensor DS6 is disposed upstream of the switching roller 23 on the transport path A10, and detects the trailing edge of the document discharged from the discharge port 25.

  The document length measuring unit 81 is a measuring unit that measures the document length. Here, it is assumed that the document length is measured based on the detection result of the document detection sensor DS2. Further, by comparing the measured document length with a threshold value, it is determined whether the document being conveyed is a long document or a short document.

  The passage time calculation unit 82 is a calculation unit that calculates the passage time of the document based on the document length measured by the document length measurement unit 81. For example, the period during which the switching roller 19 or 23 is in the reverse rotation state is calculated. Specifically, after the switching roller 19 or 23 is switched to the reverse rotation state, a period until the trailing edge of the document passes through the switching rollers 19 and 23 is calculated. Further, after the re-feed suppression shutter 24 is switched from the open state to the closed state, a period until the trailing edge of the document passes through the re-feed suppression shutter 24 is calculated. Here, the drive motor 51 is a stepping motor, and the period during which the switching rollers 19 and 23 are in the reverse rotation state or the period during which the re-reduction suppression shutter 24 is in the closed state is calculated as the number of steps supplied to this stepping motor. It shall be.

  The leading edge position specifying unit 83 is position specifying means for specifying the document position on the conveyance path based on the detection results of the document detection sensors DS4 to DS6. Specifically, the position of the leading edge of the document is calculated by measuring the transport distance from the detection position after inputting the leading edge detection signals of the document detection sensors DS4 to DS6. Here, it is assumed that the transport distance of the document is measured by counting the number of steps supplied to the drive motor 51. Further, by adding the document length detected by the document detection sensor DS2, the position of the document trailing edge can be specified based on the leading edge detection signal of the document detection sensor DS4, and vice versa. Note that the conveyance distance may be measured by measuring the document conveyance time using a timer.

  The rotation direction control unit 84 is a control unit that controls the rotation direction of the switching roller 19 or 23, and generates a control signal for switching the rotation direction. Specifically, the operation of switching the rotation direction of the switching roller 19 is performed by starting or stopping the power supply to the solenoid SND1. In addition, the operation of switching the rotation direction of the switching roller 23 is performed by starting or stopping the power supply to the electromagnetic clutch 60.

  The switching rollers 19 and 23 consume more power in the reverse rotation state than in the normal rotation state. Therefore, the rotation direction control unit 84 controls the rotation direction of the switching rollers 19 and 23 so as to shorten the period during which the switching roller 19 or 23 is in the reverse rotation state. Specifically, after the rotation direction of the switching rollers 19 and 23 is switched to the reverse rotation state, if the passage time calculated by the passage time calculation unit 82 has elapsed, the rotation direction of the switching rollers 19 and 23 is changed from the reverse rotation state to the normal state. It is returned to the rolling state. In particular, if the document length is shortened, the passing time is also shortened. For this reason, when the document length is shortened, the rotation directions of the switching rollers 19 and 23 are respectively controlled so as to shorten the period of the reverse rotation state.

  The solenoid SND1 performs an operation of switching the rotation direction of the switching roller 19 based on the control signal of the rotation direction control unit 84. More specifically, based on the control signal of the rotation direction control unit 84, the power supply to the solenoid SND1 is started or stopped, thereby switching the connection state of the rotational force transmission unit 70 in FIG. In this case, in a state where power is not supplied to the solenoid SND1, the switching roller 19 is driven to rotate forward. In addition, when the solenoid SND1 is supplied with power, the switching roller 19 is driven in reverse.

  The electromagnetic clutch 60 performs an operation of switching the rotation direction of the switching roller 23 based on the control signal of the rotation direction control unit 84. Specifically, based on a control signal from the rotation direction control unit 84, a transmission state in which power supply to the electromagnetic clutch 60 is performed and a shut-off state in which power supply to the electromagnetic clutch 60 is not performed are switched. In this case, in the transmission state, the switching roller 23 is in the reverse rotation state, and in the cutoff state, the switching roller 23 is in the normal rotation state.

  The shutter control unit 85 is a control unit that controls the open / close state of the re-reduction suppression shutter 24, and generates a control signal for switching the open / close state of the re-transfer suppression shutter 24. Specifically, an operation of switching the open / close state of the re-retention suppression shutter 24 is performed by starting or stopping the power supply to the solenoid SND2.

  More specifically, when the switching roller 23 is in the reverse rotation state, the open / close state is switched so that the re-reduction suppression shutter 24 is closed. Specifically, the re-reduction suppression shutter 24 is switched to the closed state before the switching roller 23 is switched to the reverse rotation state, and the re-reduction suppression shutter 24 is switched to the open state after the switching roller 23 is switched to the normal rotation state. .

  The re-transfer suppression shutter 24 consumes more power in the closed state than in the open state. For this reason, the shutter control unit 85 controls the open / close state so that the closed period is as short as possible. Further, as described above, the rotation direction control unit 84 controls the rotation direction of the switching roller 23 so that the time for the reverse rotation state is shortened when the document length is short. Therefore, like the rotation direction control unit 84, the shutter control unit 85 controls the open / close state based on the document length so that the time for the closed state is shortened if the document length is short. By adopting such a configuration, while the switching roller 23 is in the reverse rotation state, the period during which the re-rolling suppression shutter 24 is in the closed state can be shortened.

  The solenoid SND2 performs an operation of switching the open / close state of the re-reduction suppression shutter 24 based on the control signal of the shutter control unit 85. That is, the power supply state to the solenoid SND2 is switched based on the control signal of the shutter control unit 85. In this case, when the power supply to the solenoid SND2 is started, the re-feeding suppression shutter 24 is switched to the open state by the solenoid SND2. On the other hand, when the power supply to the solenoid SND2 is stopped, the re-feeding suppression shutter 24 is switched to the closed state by an elastic member (not shown).

  The document reading unit 32 is a scanner unit that reads a document transported on the transport path A2. The document reading unit 32 reads the first surface of the document being conveyed in the forward direction and reads the second surface of the document being conveyed in the reverse direction.

  By adopting such a configuration, the rotation direction control unit 84 controls the rotation direction of the switching roller 19 or 23 so that the time for the reverse rotation state is shortened if the document length is short. The period during which the reverse state is achieved can be further shortened. For this reason, power consumption due to switching of the rotation direction of the switching roller 19 or 23 can be reduced.

  Steps S101 to S112 in FIGS. 15 and 16 are flowcharts showing an example of the operation of the switching roller 19 at the time of duplex reading. The process of this flowchart is started when the user instructs the double-sided reading of the document. First, the document length measuring unit 81 measures the document length based on the detection result of the document detection sensor DS2 (step S101). Next, the switching roller 19 in the forward rotation state causes the document to enter the reading position B2 in the forward direction (step S102). Further, as shown in FIGS. 4B and 7C, the leading edge position specifying unit 83 determines whether or not the leading edge of the document has reached the reference position E1 on the transport path A7 (step S103). If it is determined that the leading edge of the document has reached the reference position E1, the electromagnetic clutch 71 cuts off the rotational force from the drive motor 51 and stops the switching roller 19 (step S104). Next, the rotation direction control unit 84 starts supplying power to the solenoid SND1, and switches the rotation direction of the switching roller 19 to the reverse rotation state (step S105). Thereafter, the electromagnetic clutch 71 transmits the rotational force from the drive motor 51 to the switching roller 19 to drive the switching roller 19 in reverse (step S106).

  Also, the switching roller 19 in the reverse state conveys the document in the reverse direction (step S107). At this time, the rotation direction control unit 84 determines the passage of the trailing edge of the document with respect to the switching roller 19 (step S108). If it is determined that the trailing edge of the document has passed the switching roller 19, the electromagnetic clutch 71 cuts off the rotational force from the drive motor 51 and stops the switching roller 19 (step S109). Further, the rotation direction control unit 84 stops the power supply to the solenoid SND1, and switches the rotation direction of the switching roller 19 to the normal rotation state (step S110). Further, the electromagnetic clutch 71 transmits the rotational force from the drive motor 51 to the switching roller 19 (step S111). Also, the presence / absence of the next document is determined, and if there is no next document, the process is terminated (step S112). On the other hand, if there is a next original, the processes in steps S101 to S111 are repeated.

  Steps S201 to S210 in FIG. 17 are flowcharts showing an example of the operation of the switching roller 23 when reading a long original on both sides. The process of this flowchart is started when the user instructs the double-sided reading of the document, as in FIGS. 15 and 16. First, the document length measuring unit 81 measures the document length based on the detection result of the document detection sensor DS2 (step S201).

  Next, as shown in FIG. 7B, the leading edge position specifying unit 83 determines whether or not the leading edge of the document has reached the reference position E3 on the transport path A5 (step S202). When the leading end of the document reaches the reference position E3, the shutter control unit 85 starts power supply to the solenoid SND2 and switches the re-reduction suppression shutter 24 to the closed state (step S203). Moreover, the rotation direction control part 84 starts the power supply to the electromagnetic clutch 60, and switches the switching roller 23 to a reverse rotation state (step S204). Further, the switching roller 23 in the reverse state conveys the original on the conveyance path A5 which is a long original U-turn path (step S205). At this time, the rotation direction control unit 84 determines the passage of the trailing edge of the document with respect to the switching roller 23 (step S206).

  When the trailing edge of the document passes through the switching roller 23, the rotation direction control unit 84 stops the power supply to the electromagnetic clutch 60 and puts it into a shut-off state, thereby switching the switching roller 23 to the normal rotation state (step S207). Further, the shutter control unit 85 stops the power supply to the solenoid SND2, thereby switching the re-reduction suppression shutter to the open state (step S208). Thereafter, the switching roller 23 in the normal rotation state conveys the document on the conveyance path A10 to the discharge port 25 (step S209). Also, the presence / absence of the next original is determined, and if there is no next original, the process is terminated (step S210). On the other hand, if there is a next original, the processes in steps S201 to S209 are repeated.

  FIG. 18 is a time chart showing the relationship between the switching of the rotation direction of the switching roller 23 and the switching of the open / close state of the re-reduction suppression shutter 24. The vertical axis indicates the rotation direction of the switching roller 23 and the open / closed state of the re-reduction suppression shutter 24, and the horizontal axis indicates time.

In the multi-function device 100, while the switching roller 23 is in the reverse rotation state, the open / close state is switched so that the re-reduction suppression shutter 24 is closed. That is, after the re Kukomi suppression shutter 24 at time t ₁ is switched from the open state to the closed state at time t ₂ the rotational direction of the switching roller 23 is switched to the reverse rotation state from the normal rotation state. Further, after the original length original U-turn path is conveyed by the switching roller 23 of the reversing state, the rotational direction of the switching roller 23 is switched to the reverse rotation state at time t _3, then re Kukomi suppressed at time t ₄ the shutter 24 is switched from the closed state to the open state. A period in which the switching roller 23 from time t ₂ to time t ₃ is reversed state, re Kukomi suppression shutter 24 from time t ₁ to time t ₄ is the time period in which the closed state, respectively based on the original length Be changed.

  By adopting such a configuration, when the switching roller 23 is switched from the normal rotation state to the reverse rotation state, the re-reduction suppression shutter 24 is in the closed state, and thus is in contact with the switching roller 23. It is possible to prevent the original being fed back into the conveyance path by the switching roller 23 in the reverse rotation state. Further, when the re-reduction suppression shutter 24 is switched from the closed state to the open state, the switching roller 23 is in the forward rotation state. For this reason, even if the original comes into contact with the re-feed suppression shutter 24, it is possible to prevent the original from being transferred again to the conveyance path by the switching roller 23 in the normal rotation state.

  According to the present embodiment, in the transmission state of the electromagnetic clutch 60, the rotational force by the fixed gear 59 of the reverse rotation side torque transmission unit is transmitted to the switching roller 23 by the electromagnetic clutch 60, and the switching roller 23 is in the reverse rotation state. On the other hand, in the shut-off state, the rotational force by the fixed gear 59 of the reverse rotation side torque transmission unit is interrupted by the electromagnetic clutch 60, and the rotational force by the fixed gear 58 of the normal rotation side torque transmission unit is transmitted to the switching roller 23. The switching roller 23 is in the forward rotation state. In this case, since the rotation direction of the switching roller 23 is controlled so that the period of the reverse rotation state is shortened if the document length is short, the period of the transmission state in which the power consumption of the electromagnetic clutch 60 is large can be further shortened. it can.

  Further, the direction of the rotational force transmitted from the drive motor 51 is reversed by changing the number of gears that transmit the rotational force using the solenoid SND1. For this reason, since the rotation direction of the switching roller 19 can be switched with a simple configuration, the multifunction device 100 can be downsized and the product cost can be reduced. Further, since the rotation direction of the switching roller 19 is controlled so that the period of the reverse rotation state is shortened if the document length is short, the period of the connection state in which the power consumption of the solenoid SND1 is larger among the two connection states. Can be made shorter.

  Further, since the re-feeding suppression shutter 24 suppresses the re-feeding of the document that has been discharged, even if the rotation direction of the switching roller 23 is switched before the document leaves the switching roller 23, the document is returned to the transport path again. It is possible to suppress the retraction. Further, since the open / closed state is switched so as to be in the closed state in the case of the reverse rotation state, similarly to the switching of the rotation direction of the switching roller 23, the time for the closed state can be varied based on the document length. Therefore, it is possible to shorten the period during which the power consumption is closed as compared with the open state.

  In the present embodiment, the configuration in which the document length measurement unit 81 measures the document length based on the detection result of the document detection sensor DS2 has been described. However, the present invention is not limited to this. For example, the time from when the leading edge of the document reaches the detection position of the document detection sensor DS4 until the trailing edge of the document passes the detection position is measured, and the document length is measured based on this time. Also good.

  By adopting such a configuration, the length of the document is measured based on the time from when the leading edge of the document reaches the detection position of the document detection sensor DS4 until the trailing edge of the document passes the detection position. . For this reason, even when originals with different original lengths are mixedly loaded, the original length of each original can be measured. Accordingly, the document length can be measured with higher accuracy, and the period during which the switching roller 19 or 23 is in the reverse rotation state with high power consumption can be further shortened.

Embodiment 2. FIG.
In the first embodiment, the example in which the rotation direction control unit 84 controls the switching direction of the switching rollers 19 and 24 based on the document length has been described. In contrast, in the present embodiment, an example in which the switching direction of the switching rollers 19 and 24 is controlled based on the leading edge position and the trailing edge position of the document will be described.

  FIG. 19 is a functional block diagram showing an example of the configuration of the main part of the MFP 200 according to the second embodiment of the present invention. Compared with the case of FIG. 14, it is different in that a front / rear end position specifying unit 91 and a rotation direction control unit 92 are provided instead of the tip position specifying unit 83 and the rotation direction control unit 84. About the same structure as FIG. 14, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The front / rear end position specifying unit 91 is position specifying means for specifying the leading edge position and the trailing edge position of the document on the transport path based on the detection results of the document detection sensors DS4 to DS6. Specifically, after the leading edge detection signal or trailing edge detection signal of the document detection sensors DS4 to DS6 is input, the leading edge position or trailing edge position of the document is calculated by measuring the transport distance from the detection position. Here, it is assumed that the transport distance of the document is measured by counting the number of steps supplied to the drive motor 51.

  The rotation direction control unit 92 is a control unit that controls the rotation direction of the switching roller 19 or 23, and generates a control signal for switching the rotation direction. Specifically, similarly to the rotation direction control unit 84, the operation of switching the rotation direction of the switching roller 19 is performed by starting or stopping the power supply to the solenoid SND1. In addition, the operation of switching the rotation direction of the switching roller 23 is performed by starting or stopping the power supply to the electromagnetic clutch 60.

  Further, the rotation directions of the switching rollers 19 and 23 are controlled so as to shorten the period during which the switching rollers 19 and 23 are in the reverse rotation state. Specifically, after the rotation direction of the switching rollers 19 and 23 is switched from the normal rotation direction to the reverse rotation state based on the leading edge position of the document, the rotation direction of the switching rollers 19 and 23 is based on the trailing edge position of the document. Is switched from the reverse rotation state to the normal rotation state.

  For example, if a predetermined amount of conveyance is performed after detection of the document leading edge by the document detection sensor DS4, it is determined that the document leading edge has reached the reference position E1 (FIG. 7C), and the rotation direction of the switching roller 19 is rotated forward. Switch from state to reverse state. Further, if a predetermined amount of conveyance is performed after detection of the trailing edge of the document by the document detection sensor DS5, it is determined that the document trailing edge has passed the switching roller 19, and the rotation direction of the switching roller 19 is changed from the reverse rotation state to the normal rotation state. Shall return

  Similarly, if a predetermined amount of conveyance is performed after the detection of the document leading edge by the document detection sensor DS4, it is determined that the document leading edge has reached the reference position E3, and the rotation direction of the switching roller 23 is switched from the normal rotation state to the reverse rotation state. . If a predetermined amount of conveyance is performed after the document detection sensor DS4 detects the trailing edge of the document, it is determined that the document trailing edge has passed the switching roller 23, and the rotation direction of the switching roller 23 is changed from the reverse rotation state to the normal rotation state. It shall be returned.

  According to the present embodiment, the rotation direction of the switching roller 19 or 23 is switched to the reverse rotation state based on the detection timing of the leading edge of the document, and the rotation of the switching rollers 19 and 23 based on the detection timing of the trailing edge of the document. Switch the direction to forward rotation. For this reason, the time until the rotation direction of the switching rollers 19 and 23 is returned from the reverse rotation state to the normal rotation state can be made different so that the time for the reverse rotation state is shortened if the document length is short.

  Further, since the rotation direction control unit 92 switches the rotation direction from the normal rotation state to the reverse rotation state based on the leading edge position of the document, the rotation direction can be switched before the leading edge of the document reaches the switching rollers 19 and 23. it can. Also, since the time until the rotation direction is returned from the reverse rotation state to the normal rotation state is made different so that the time for the reverse rotation state is shortened if the document length is short, the period of the reverse rotation state with high power consumption is further shortened. be able to. For this reason, the power consumption by switching of the rotation direction of the switching rollers 19 and 23 can be reduced.

12 Discharge tray 18 Conveying rollers 19 and 23 Switching rollers 21 and 22 Branch claw 24 Re-feed suppression shutter 25 Discharge port 32 Document reading unit 50 and 70 Rotational force transmission unit 51 Drive motor 51a Shafts 52 to 59, 61 and 72 Fixed gear 60, 71 Electromagnetic clutch 62 Selection clutch 73-75 Moving gear 76 Plate 81 Document length measurement unit 82 Passing time calculation unit 83 Tip position specifying unit 84, 92 Rotation direction control unit 85 Shutter control unit 91 Front / rear end position specifying unit 100, 200 MFP 621 External housing 622 Coil spring 623 Inner shafts A1 to A11 Transport paths DS1 to DS6 Document detection sensors SND1, SND2 Solenoid

Claims (8)

A document length measuring means for measuring the document length;
A switching roller that conveys the document and can switch the rotation direction between the normal rotation state and the reverse rotation state;
A rotation direction control means for controlling the rotation direction,
The switching roller has a larger power consumption in the reverse rotation state than in the normal rotation state,
The document reading apparatus, wherein the rotation direction control means controls the rotation direction based on the document length so that if the document length is short, the time for the reverse state is shortened. A drive motor that generates rotational force;
A plurality of gears, and first and second rotational force transmitting means for transmitting rotational force of the drive motor to the switching roller so that the rotational directions are different from each other;
An electromagnetic clutch for switching between a transmission state for transmitting the rotational force by the first rotational force transmission means to the switching roller and a cutoff state for blocking the rotational force based on a control signal of the rotational direction control means;
A selection clutch that cuts off the rotational force of the second rotational force transmission means in the transmission state;
The electromagnetic clutch consumes more power in the transmission state than in the disconnected state,
The document reading apparatus according to claim 1, wherein the first rotational force transmitting unit rotates the switching roller in the reverse rotation state. A drive motor that generates rotational force;
A rotational force transmitting means comprising a plurality of gears and transmitting the rotational force of the drive motor to the switching roller;
A solenoid that switches between the first and second connection states having different rotation directions based on a control signal of the rotation direction control means;
The solenoid switches the first and second connection states by changing the number of gears that transmit the rotational force,
The power consumption of the solenoid is larger in the first connection state than in the second connection state, and the rotational force transmitting means rotates the switching roller in the reverse rotation state. Document reading device. An original reading means for reading an original conveyed on the reading path;
A U-turn path for U-turning the original after reading the first surface and re-entering the reading path from the opposite direction;
A discharge path for discharging the original after reading the second side;
4. The document reading apparatus according to claim 1, wherein the switching roller is disposed in the reading path. An original reading means for reading an original conveyed on the reading path;
A U-turn path for U-turning the original after reading the first surface and re-entering the reading path from the opposite direction;
The switching roller is disposed, and includes a discharge path for discharging the original after reading the second surface,
The document reading apparatus according to claim 1, wherein the switching roller is disposed at an intersection between the U-turn path and the discharge path. An open state and a closed state can be switched, and in the closed state, a re-feed suppression shutter that suppresses the re-feed of the document discharged from the discharge path;
Shutter control means for controlling the open / close state so as to be in the closed state in the reverse rotation state,
When the re-reduction suppression shutter is in the closed state, power consumption is larger than that in the open state.
6. The document reading apparatus according to claim 5, wherein the shutter control unit switches the open / close state based on the document length so that the time for the closed state is shortened when the document length is short. A document detecting means for detecting a document being conveyed;
The document length measuring means measures the document length based on the time from when the leading edge of the document reaches the detection position of the document detection means until the trailing edge of the document passes the detection position. 2. The document reading apparatus according to claim 1, wherein A document length measuring means for measuring the document length;
Leading and trailing edge specifying means for specifying the leading edge position and trailing edge position of the document;
A switching roller that conveys the document and can switch the rotation direction between the normal rotation state and the reverse rotation state;
Rotation direction control means for controlling the rotation direction and switching the rotation direction from the forward rotation state to the reverse rotation state based on the tip position;
The switching roller has a larger power consumption in the reverse rotation state than in the normal rotation state,
The rotation direction control means varies the time from the reverse rotation state to the normal rotation state so that the time for the reverse rotation state is shortened if the document length is short, based on the rear end position. A document reading apparatus characterized by the above.

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