JP5798803B2 - Document conveying apparatus and image reading apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus that reads an original and an original conveying apparatus mounted on the image reading apparatus, and more particularly to an original conveying control that conveys an original to a reading position where a reading unit is arranged.

  2. Description of the Related Art Conventionally, as a document reading device for reading a document image, a document transported by a belt or a roller is stopped on a platen glass and scanned with a scanning optical system to read an image, that is, a so-called document fixed reading method, and moved. There are generally known two types of documents in which a document image is read by a reading optical system in which the document is stationary, a so-called sheet-through reading method.

  In particular, the latter sheet-through reading method reads the document while moving it to a predetermined reading position, so the processing time of the document is short, the document transport mechanism is simple, and the number of parts is low, realizing low costs. There is an advantage that you can.

  The document conveying device provided in the sheet-through reading type document reading device includes a paper feed tray on which a document is placed, a liftable roller for feeding the document on the paper feed tray, and a fed document as one. Separating means comprising a sheet feeding roller and a friction separating member that separates and feeds sheets, and a leading edge of a fed document that has been separated into one sheet abuts to align the leading edge of the document and sends it to a reading position A conveyance unit including a roller pair and a conveyance roller pair that conveys the document that has passed through the reading position downstream, and a discharge roller pair that discharges the document to a discharge tray.

  The paper feed roller is stopped after the leading edge of the document is brought into contact with the pair of registration rollers and aligned. The pair of registration rollers conveys the document while pulling it out from the nip portion of the paper feed roller and the separating member, and passes the reading position. .

  In such a conventional document conveying device, when the document is released from the nip of the roller disposed upstream of the reading position, that is, when the trailing edge of the document passes through the nip portion of the sheet feeding roller and the separating member, the conveying means The load fluctuates and speed variation occurs. In particular, a small-size document having a short length is transported only by the registration roller pair when the leading end does not reach the transport roller pair when it is pulled out from the nip portion between the paper feed roller and the separating member. In other words, small-size originals are pulled out from the nip between the paper feed roller and the separating member during reading in an unstable conveyance state, resulting in uneven document speed, document blur, and document skew. Significant distortion occurred.

  For example, Patent Document 1 discloses a solution to such a problem. In Patent Document 1, a document on a document tray is fed by a forward feed roller and a paper feed roller. Then, after the leading edge of the document is abutted and aligned with the registration roller pair, the paper feed roller is stopped, and then the registration roller pair is driven to supply the document to the reading position. Thereafter, after a predetermined time has elapsed from the time when the registration roller pair is driven, the forward feed roller and the paper feed roller are moved at a document conveyance speed (V1) larger than the document conveyance speed (V2) of the registration roller pair. To drive. As a result, a bend (loop) is formed in the document between the paper feed roller and the registration roller pair, and fluctuations in the document speed that occur when the rear end of the document moves away from the paper feed roller are absorbed by the deflection of the document.

JP 2005-15100 A

  However, in Patent Document 1, it is necessary to drive the paper feed roller during the time for forming a certain amount of deflection, and the trailing edge of the document fed by the pair of registration rollers is fed to all size documents. Since the forward feed roller and the paper feed roller are driven until they pass through the nip position between the paper roller and the separating member, there is a possibility that double feed and conveyance failure may occur in all size originals.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an original conveying apparatus that can reduce defective conveyance of an original and stably convey an original and obtain a good read image.

  In order to achieve the above object, the document conveying apparatus of the present invention drives the pair of conveying rollers while the sheet feeding roller is stopped, and passes the trailing edge of the document through the nip portion between the sheet feeding roller and the separating member. The first transport mode and the second transport mode in which the paper feed roller and the transport roller pair are driven to pass the trailing edge of the document through the nip portion between the paper feed roller and the separation member are determined according to the length of the document. Control means to select and execute was provided.

  In addition, the image reading apparatus of the present invention drives the pair of conveying rollers to convey the document, stops the sheet feeding roller, and passes the nip portion between the sheet feeding roller and the separation member, and the conveying roller. The pair is driven to transport the original and the paper feed roller is stopped, and then the paper feed roller is re-driven at the same speed as the original transport speed of the pair of transport rollers to feed the original to the nip portion between the paper feed roller and the separating member. Control means for selecting and executing the second conveyance mode to be passed according to the length of the document is provided.

  Depending on the length of the document, the drive of the paper feed roller when the trailing edge of the document passes through the nip portion between the paper feed roller and the separation member is controlled. A good read image can be obtained while suppressing the conveyance failure of the document.

1 is a cross-sectional view illustrating a document conveying device according to the present invention and a document reading device on which the document conveying device is mounted. FIG. FIG. 4 is a drive diagram illustrating a drive mechanism of a paper feed system in the document feeder according to the present invention. It is a fragmentary sectional view which shows the delay mechanism of the feeding roller which concerns on this invention. FIG. 3 is a control block diagram of the document feeder according to the present invention. It is a main control flowchart figure of the single-sided reading operation | movement in the original conveying apparatus which concerns on this invention. It is a control flowchart figure which shows the registration process in the original conveying apparatus which concerns on this invention. It is a control flowchart figure which shows the 1st conveyance process in the original conveying apparatus which concerns on this invention. It is a control flowchart figure which shows the 2nd conveyance process in the original conveying apparatus which concerns on this invention. FIG. 6 is a schematic diagram illustrating a document conveyance state of a first conveyance process in the document conveyance device according to the present invention. FIG. 6 is a schematic diagram illustrating a document conveyance state of a first conveyance process in the document conveyance device according to the present invention. FIG. 4 is a front view showing a hinge cover of a hinge device that connects a document conveying device and a document reading device, and a perspective view showing a hinge cover attached state.

  Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a document conveying device according to the present invention and a document reading apparatus main body on which the document conveying device is mounted.

  In FIG. 1, A is a document conveying device mounted on the reading device main body H. The document conveying device A is disposed so as to cover the upper surface of the document reading device main body H, and is attached to the upper surface of the document reading device main body 1 by a hinge device 14 so as to be freely opened and closed.

  The document reading device main body H irradiates the conveyed document with light from a light source 3 such as a lamp via a contact glass 1, reflects the reflected light by a plurality of mirrors 4, and passes through a condenser lens 5 to CCD 6. A document image photoelectrically converted by a reading means such as is read. That is, the upper surface of the contact glass 1 constitutes a reading unit of the document reading apparatus main body H. The document reading device main body H also includes a contact glass 2 having an area on which a document can be placed. The document placed on the contact glass 2 by opening and closing the document conveying device A is composed of a light source 3 and a mirror 4. By moving the light source unit in the sub-scanning direction, an image of the document can be read through the contact glass 2.

  The document feeder A feeds out a document in contact with the uppermost surface of the document on the sheet feed tray 20, a sheet discharge tray 12 that stores the read document, and a sheet feed tray 10 on which a plurality of documents can be placed. A feed roller 20 that can be moved up and down, a feed roller 21 that feeds the fed document, a separation member 32 that is pressed against the feed roller 21 to prevent double feeding of the document, and a leading edge of the document. A pair of registration rollers 23 to be supplied onto the contact glass 1 after being abutted and aligned, and a pair of transport rollers 24 provided on the downstream side of the contact glass 1 for transporting a document passing through the contact glass 1 are provided. It has been. A pair of discharge rollers 25 is provided on the downstream side of the pair of transport rollers 24 to discharge the document to the discharge tray 12.

  By driving and controlling each of the rollers described above, the document on the paper feed tray 10 is transported along a U-shaped transport path from the paper feed tray 10 to the paper discharge tray 12.

  Next, the drive configuration of each roller will be described. Each roller is driven by one drive motor MT that can be rotated forward and backward. The drive transmission mechanism of the drive motor MT includes a plurality of gears, pulleys, and a timing belt wound around the pulleys, and is disposed on the rear side of the document conveying device together with the drive motor MT.

  As shown in FIG. 9, the drive transmission mechanism includes a feed transmission drive mechanism for transmitting drive to the feeding roller 20 and the feed roller 21, a drive roller for the registration roller pair 23, and a drive roller for the transport roller pair 24. A drive transmission mechanism for the conveyance system for transmitting the drive to the drive roller, and a drive transmission mechanism for the paper discharge system for transmitting the drive to the drive rollers of the paper discharge roller pair 25. The drive transmission mechanisms of the paper feed system, the transport system, and the paper discharge system are connected to a single drive motor MT as a drive means.

  FIG. 2 is a drive mechanism diagram showing a drive transmission mechanism of the paper feed system. The drive transmission mechanism of the paper feed system includes a first electromagnetic clutch CL1 as a clutch means as shown in FIG. 2, and the drive from the drive motor MT is extended by controlling the first electromagnetic clutch CL1. The driving of the feeding roller 20 and the paper feed roller 21 is controlled by transmitting or blocking to the roller 20 and the paper feed roller 21. In addition, the drive transmission mechanism of the transport system includes a second electromagnetic clutch CL2, and by controlling the second electromagnetic clutch CL2, the drive from the drive motor MT is transferred to the registration roller pair 23 and the transport roller pair 23. Transmission and cut-off are performed, and driving is controlled by the registration roller pair 23 and the conveyance roller pair 24. The drive transmission mechanism of the paper discharge system transmits the drive of the drive motor MT directly to the paper discharge roller pair 35 and drives forward and reverse by the forward and reverse drive of the drive motor MT.

  The shaft 50 of the feed roller 30 is rotatably supported by the support holder 19 as shown in FIG. One end of the support holder 19 is rotatably supported by the shaft 21 a of the paper feed roller 21. Further, the support holder 19 is drivingly connected to the shaft 21a of the paper feed roller 21, and the support holder 19 is configured to rotate in the vertical direction by forward and reverse rotation of the shaft 21a. As a result, the feeding roller 20 moves up and down to a feeding position where the feeding roller 20 comes into contact with the document and a standby position separated from the document. Further, a plurality of gears Z 1, Z 2, Z 3, Z 4, Z 5 for transmitting the rotation of the shaft 21 a of the paper feed roller 31 to the shaft 50 of the feeding roller 20 are attached to the support holder 19.

  Here, the feeding roller 20 is provided with a delay mechanism, and is driven after the paper feed roller 21 is driven by a predetermined amount. FIGS. 3A and 3B are partial sectional views showing a delay mechanism of the feeding roller 20, FIG. 3A shows a state where the drive is not transmitted to the feeding roller 20, and FIG. A state in which driving is transmitted to the feeding roller 20 is shown.

  As shown in FIGS. 3A and 3B, a transmission member 51 is fixedly attached to the shaft 50 of the feeding roller 20. An engagement piece 52 is formed in the transmission member 51 in the extending direction of the shaft 50.

  One end of the feeding roller 20 is cylindrical, and an engagement member 53 is rotatably attached to the shaft 50 inside the feeding roller 20. The engagement member 53 is formed with an engagement groove 54 with which the engagement piece 52 of the transmission member 51 is engaged. The engagement groove 54 is formed on the one surface 54 a that contacts the side portion of the engagement piece 52 and on this surface. The other surface 54b that faces each other and an inclined tapered surface 54c that comes into contact with the tip of the engagement piece 52 are formed. Further, a tooth-like ratchet claw 55 is provided on the end surface of the engagement member 53 on the opposite side of the engagement groove 54, and this ratchet claw 55 is arranged in a tooth-like ratchet groove of the feeding roller 20 depending on the rotation direction of the shaft 50. Engage with 20a.

  Next, the delay operation will be described. As shown in FIG. 3A, the drive motor is driven from a state in which the ratchet pawl 55 of the engaging member 53 is not engaged with the latch groove 20a of the feeding roller 20, and the shaft 21a of the paper feeding roller 21 is moved in the document feeding direction. When rotated, the rotational drive of the shaft 21a is transmitted to the shaft 50 of the feeding roller 20 via a plurality of gears Z1 to Z5. As the shaft 50 rotates, the transmission member 51 also rotates in the direction of the arrow shown in FIG. Then, the rotation of the transmission member 51 causes the tip of the engagement piece 52 to slide and urge the inclined surface 54 c of the engagement groove 54, and the engagement member 53 moves to the latituting groove 20 a side of the feeding roller 20. As a result, as shown in FIG. 3B, the ratchet pawl 55 of the engagement member 53 and the ratchet groove 20 a of the feeding roller 20 are engaged, and the side portion of the engagement piece 52 of the transmission member 51 is one surface of the engagement groove 54. The drive of the shaft 50 is transmitted to the feeding roller 20 via the transmission member 51 and the engagement member 53. That is, the feeding roller 20 rotates with respect to the paper feed roller 21 with a rotation amount corresponding to the distance between the one surface 54 a and the other surface 54 b of the engagement groove 54. In the present embodiment, the delay amount in the delay mechanism is set to an amount corresponding to the set number of pulses (pulse B) for driving the paper feed roller 21 in the second transport process described later.

  On the other hand, in the document transport operation described later, the document is aligned by abutting the leading end against the registration roller pair 23, and then the document transport is started by the registration roller pair 23. At this time, the engaging member 53 of the delay mechanism is engaged with the ratchet pawl 20a of the feeding roller 20 as shown in FIG. Then, following the movement of the document conveyed by the registration roller pair 23, the feeding roller 20 rotates in the arrow direction shown in FIG. As a result, the ratchet groove 20a of the feeding roller 20 moves the engagement member 53 toward the transmission member 51, and the meshing with the ratchet pawl 55 is released. At this time, the engaging member 53 abuts on the tip of the engaging piece 52 of the transmission member 51 where the tapered surface 54c of the engaging groove 54 is stopped, and is in the same direction as the feeding roller 20 along the tapered surface 54c (FIG. 3). It rotates in the direction of the arrow shown in (b). That is, the engaging member 53 moves while rotating, and the other surface 54 b of the engaging groove 54 comes into contact with the side portion of the engaging piece 52 of the transmission member 51 and stops. At this time, the ratchet groove 20 a of the feeding roller 20 is completely disengaged from the ratchet pawl 55 of the engaging member 53, and idles so as to ride on the end of the ratchet pawl 55. As a result, the delay mechanism is returned to the state shown in FIG. 3A, and when the paper feed roller 21 starts to drive again, the feeding roller 20 is driven with a delay from the paper feed roller 21. .

  FIG. 4 is a control block diagram showing the configuration of the control system of the document conveying device. A control system of the document conveying apparatus will be described with reference to FIGS.

  The paper feed tray 10 is provided with an empty sensor S1 that detects that a document is placed on the paper feed tray 10. In addition, a registration sensor S2 for detecting an end portion of a fed document is disposed in front of the registration roller pair 33, and a read sensor S3 is disposed between the registration roller pair 33 and the contact glass 1.

  Each of these sensors S1, S2, and S3 is connected to a control board (control unit) 100 on which a CPU that controls driving of the entire apparatus is mounted as shown in FIG. 4, and based on detection signals from the respective sensors. Thus, the drive motor MT, the first electromagnetic clutch CL1, and the second electromagnetic clutch CL2 are controlled.

  A pair of regulating members 11 that move in the width direction of the document and regulate both ends in the width direction of the document are provided on the sheet feeding tray, and the pair of regulating members 11 on the sheet feeding tray 10 move. As a result, the resistance value of the slide volume VR is displaced. The output voltage from the slide volume VR is stored in the RAM as 10-bit digital data by an AD conversion circuit provided in the control unit 100. Then, the length in the width direction of the document is detected by 10-bit data.

  A first sensor S5 and a second sensor S6 for detecting the length of the document in the sheet feeding direction are arranged in the sheet feeding tray 10 with an interval in the document feeding direction. Then, the first and second sensors S5 and S6 classify into a plurality of document groups having different lengths in the width direction depending on the detected document length. That is, if both the first and second sensors S5 and S6 detect the original, the original on the paper feed tray 10 is LG (T), B4 (T), A3 (T), LD (T). It is determined that it is either. If the second sensor S6 does not detect the original and the first sensor S5 detects the original, the original on the paper feed tray 10 is any of B5 (T), LT (T), and A4 (T). It is determined that Furthermore, if the first and second sensors S5 and S6 have not detected the original, the original on the paper feed tray 10 is ST (Y), A5 (Y), B5 (Y), A5 (T), A4 ( Y), LT (Y), or ST (T).

  As described above, the document whose size is different in the width direction is the length in the width direction of the document detected by the output value of the slide volume VR whose output value is displaced with the movement of the pair of regulating members 11. The document size is specified by the information. The ROM stores in advance document width and length data corresponding to the specified document size, and the document transport operation using the data corresponding to each document size as the actual document width and document length. Is controlling.

  In the present embodiment, detection means for detecting the width, length, document size, and the like of the document by the first and second sensors S5 and S6 and the slide volume VR provided in the paper feed tray 10 is provided. The size input from the operation panel of the document reading apparatus main body H may be acquired as size information, and the width, length, document size, etc. of the document may be detected from this size information.

  Next, the document conveying operation of the document conveying apparatus having the above configuration will be described. FIG. 5 is a control flowchart of the document feeder. 6 is a control flowchart showing the registration process, FIG. 7 is a control flowchart showing the first transfer process, and FIG. 8 is a control flowchart showing the second transfer process. The apparatus according to the present embodiment includes a single-sided reading mode for reading one side of an original and a double-sided reading mode for reading both sides of an original. Here, a single-sided document conveying operation in the single-sided reading mode will be described with reference to FIGS. A description will be given based on the control flowcharts of FIGS.

  When a paper feed command is received from the image forming apparatus main body H, it is confirmed whether or not the empty sensor S1 detects the original, that is, whether or not the original is placed on the paper feed tray 10 (ST1 to ST2). When it is detected that an original is placed on the paper feed tray 10, the original size is specified (ST3). In the document size specifying process in step 3 (ST3), as described above, the document size is specified from the length in the document width direction and the length in the document feed direction.

  When the document size is specified, the drive motor MT is driven to rotate forward, and at the same time, the first electromagnetic clutch CL1 is turned on (ST4 to ST5). As a result, the feeding roller 20 and the paper feed roller 21 are driven to rotate, and the original on the paper feed tray 10 is fed. When the registration sensor S2 detects the leading edge of the document, registration processing is executed (ST6 to ST7).

  In the registration process, as shown in FIG. 6, first, the second electromagnetic clutch is turned off, and the registration roller pair 23 is stopped (ST20). Simultaneously, counting of the number of drive pulses of the drive motor MT is started, and when the number of pulses reaches a predetermined number of pulses (pulse A), the first electromagnetic clutch CL1 is turned off (ST21 to ST22). As a result, the feeding roller 20 and the paper feeding roller 21 are temporarily stopped. At this time, the leading edge of the document is abutted against the nip portion of the registration roller pair 23 to form a bend, the leading edge of the document is aligned, and the inclination of the document is corrected.

  After the registration process (ST7) is executed, the document length PLX detected in the document size detection process (ST3) is the distance from the nip position of the paper feed roller 21 and the separation member 22 to the nip position of the conveying roller pair 24. It is determined whether or not it is longer than LA (see FIG. 9). In the present embodiment, the document length LPX is the standard length of the specified size of the document.

  Then, if the document length LPX is longer than the distance LA, the first transport process is executed (ST8, ST9), and if it is shorter, the second transport process is executed (ST8, ST10). In the present embodiment, documents of a size shorter than the distance LA from the nip position of the paper feed roller 21 and the separation member 22 to the nip position of the conveying roller pair 24 are ST (Y) and A5 (Y), and the distance An original having a size longer than LA is an original having a size other than ST (Y) and A5 (Y).

  FIG. 9 is a schematic diagram illustrating a state in which a document having a length PL1 larger than the distance LA from the nip position P1 between the paper feed roller 21 and the separating member 22 to the nip position P2 of the transport roller pair 24 is transported. FIGS. 10A and 10B show a state in which a document having a length PL2 smaller than the distance LA from the nip position of the sheet feeding roller 21 and the separating member 22 to the nip position of the conveying roller pair 24 is conveyed. It is a schematic diagram.

  In the first transport process, as shown in the control flowchart of FIG. 7, the second electromagnetic clutch CL2 is turned on with the leading edge of the document abutting against the nip portion of the registration roller pair 23 (ST30). As a result, the registration roller pair 23 and the conveyance roller pair 24 are driven. At this time, since the first electromagnetic clutch CL <b> 1 is OFF, the document is conveyed while being pulled out from the nip portion of the stopped paper feed roller 21 and separation member 22, and passes over the contact glass 1. Then, as shown in FIG. 9, the rear end of the document is pulled out from the nip portion formed by the paper feed roller 21 and the separation member 22 while being nipped by the registration roller pair 23 and the conveyance roller pair 24. As described above, the document whose length PL1 is larger than the distance LA from the nip position P1 of the feeding roller 21 and the separating member 22 to the nip position P2 of the pair of transport rollers 24 has a trailing edge at the trailing end. When the sheet is pulled out from the nip portion by the paper feed roller 21 and the separating member 22, the nip is conveyed by the registration roller pair 23 and the conveyance roller pair 24 arranged with the contact glass 1 interposed therebetween. Speed fluctuations and flapping are minimized.

  On the other hand, in the second conveyance process, when the trailing edge of the document passes through the nip position between the paper feed roller 21 and the separation member 22, the paper feed roller 21 is rotated by a predetermined amount at a constant speed with the resist roller pair 23, and the resist roller The document conveyance by the pair 23 is assisted.

  In the second transport process, as shown in the control flowchart of FIG. 8, first, the second electromagnetic clutch CL2 is turned on with the leading edge of the document abutting against the nip portion of the registration roller pair 23 (ST40). As a result, the registration roller pair 23 and the conveyance roller pair 24 are rotationally driven, and the document is conveyed toward the contact glass 1. Thereafter, as shown in FIG. 10A, the lead sensor S3 detects the leading edge of the document and simultaneously starts counting the number of drive pulses of the drive motor MT. The document is conveyed while being pulled out of the nip position between the sheet feeding roller 21 and the separating member 22 by the registration roller pair 23 until the number of pulses reaches the selected number of pulses (pulse X). At this time, the feeding roller 20 contacts the upper surface of the document conveyed by the registration roller pair 23 and rotates following the document.

  When the number of pulses reaches the selected number of pulses (pulse X), the first electromagnetic clutch CL1 is turned on (ST41 to ST43). As a result, as shown in FIG. 10B, when the predetermined position on the trailing edge side of the document reaches the nip position between the sheet feeding roller 21 and the separating member 22, the sheet feeding roller 21 is the same speed as the registration roller 23. Drive to send. At that time, since the feeding roller 20 is not rotated by the delay mechanism described above, the feeding roller 20 is fed even if the trailing edge of the document conveyed by driving the registration roller pair 23 and the paper feeding roller 21 passes the position of the feeding roller 20. The next original on the paper tray 10 is not fed out. With such a configuration, it is possible to prevent conveyance failures such as document double feeding and document jam.

  Then, the first electromagnetic clutch CL1 is turned on to drive the paper feed roller 21, and simultaneously, the drive motor MT starts counting the number of drive pulses. When the number of pulses reaches the set number of pulses (pulse B), the first electromagnetic The clutch CL1 is turned off to stop the paper feed roller 21 (ST44 to ST25). In this process, as shown in FIG. 10B, the trailing edge of the document passes through the nip portion between the paper feed roller 21 and the separation member 22 while being fed to the paper feed roller 21. As a result, the document can be passed through the nip portion between the paper feed roller 21 and the separation member 22 in a stable state without causing a speed variation, and the speed variation and fluttering when the document leaves the nip position is minimized. It can be suppressed to decrease.

  The selection pulse number (pulse X) is stored in advance in the ROM as the number of pulses corresponding to each document size, and the pulse number corresponding to the document size is set as the selection pulse number (pulse X). . The distance LX corresponding to the selected number of pulses (pulse X) is the original length LP2, the distance L1 from the rear end of the original to a predetermined position of the original, the pressure contact position P1 between the paper feed roller 21 and the separation member 22, and the read sensor S3 When the distance LB reaching the document detection position P3 is set, LX = PL2-L1-LB is calculated (see FIG. 10A). In the present embodiment, the set pulse number (pulse B) is set such that a predetermined position of the document is 5 mm from the trailing edge of the document, and the trailing edge of the document reaches the pressure contact position between the paper feed roller 21 and the separating member 22. Thereafter, the sheet feeding roller 21 is stopped after the feed amount corresponding to 5 mm is driven. That is, in the present embodiment, the number of set pulses (pulse B) is set to the number of drive pulses corresponding to 10 mm.

  The original on which the first conveyance process or the second conveyance process has been performed is discharged to the discharge tray 12 by the conveyance roller pair 24 and the discharge roller pair 25 after the original image is read at the reading position of the contact glass 1. The When the trailing edge of the document is detected by the registration sensor S2 during this conveyance process, the empty sensor S1 checks whether there is a document on the paper feed tray 20 (ST11 to ST12).

  If there is a document on the paper feed tray 10, the first electromagnetic clutch CL1 is turned on to start feeding the next document. If there is no document on the paper feed tray 10 and the document being conveyed is recognized as the final document, the drive motor MT starts counting drive pulses, and the number of pulses reaches a predetermined number of pulses (pulse C). At that time, the drive motor MT is stopped, the first and second electromagnetic clutches CL1 and CL2 are turned off, and all transport operations are completed (ST13 to ST14). The predetermined number of pulses (pulse C) is the number of driving pulses corresponding to the distance at which the document is reliably discharged from the position of the registration sensor S2 to the discharge tray 12.

  Here, on the rear side of the cover member 13 that covers the document conveying device A, a hinge cover 41 that covers the hinge device 14 is provided. The hinge cover 41 prevents a hand or object from being sandwiched between the hinge devices 14 and prevents the grease of the hinge devices 14 from being scattered outside.

  FIG. 11A is a developed view showing the hinge cover 41 in a flat shape, and FIG. 11B is a partial cross-sectional view showing a state in which the hinge cover 41 is attached to the cover member 13 of the document feeder A. The hinge cover 41 is made of an elastic film member, as shown in FIG. 11 (a), a main body 41a, a bent portion 41b that is bent with respect to the main body 41a along the broken line in FIG. 11 (a), The folded portion 41b is formed by a folded portion 41c extending from substantially the center of the folded portion 41b, a circular stop portion 41d at the tip of the folded portion 41c, and a cutout portion 41e in which a part of the body portion 41a is cut away. A double-sided tape 42 is attached to the bent portion 41 b of the hinge cover 41.

  11B, the hinge cover 41 has a bent portion 41b attached to the back surface of the cover member 13 by the double-sided tape 42, and the body portion 41a of the attached hinge cover 41 is the rear of the hinge device 14. It covers the side. Then, the folded portion 41c is bent and deformed in the attached state, folded back toward the main body portion 41a, and a circular stopper 41d at the tip thereof is inserted into and engaged with the cutout portion 41e of the main body portion 41a. The engagement between the stopper 41d and the notch 41e prevents the bending angle between the main body 41a and the bent portion 41b from being increased, and the main body 41a can always be positioned at a position covering the hinge device 14. .

  According to the above embodiment, when the document is not conveyed by the two roller pairs of the registration roller pair 23 and the conveyance roller pair 24, the document is fed until at least the rear end of the document passes the paper feed roller 21. Since the paper roller 21 is driven and the original is auxiliary conveyed, the original conveyance is not unstable, and the nip position between the paper feeding roller 21 and the separation member 22 can be passed in a stable state. Thus, speed fluctuation and fluttering when the document leaves the nip position can be minimized.

  In addition, since the document transport speed of the paper feed roller 21 is the same as the document transport speed of the registration roller pair 23, the paper feed roller 21 ejects the document strongly, and the document flutters between the paper feed roller 21 and the registration roller pair 23. It is possible to prevent a document conveyance failure due to the formation of a bend in between.

  Further, auxiliary conveyance by the paper feed roller 21 is performed only for a short time from when the position of the rear end side of the original reaches the nip position between the paper feed roller 21 and the separation member 22 until the rear end of the original passes through the nip position. Since this is done, it is possible to prevent document double feed and conveyance failure.

  In addition, since a delay mechanism is provided in the drive transmission system of the feeding roller 20, the feeding roller 20 is not driven even if the paper feeding roller 21 is slightly rotated, so that the trailing edge of the original and the leading edge of the next original overlap. Thus, the next original is not fed out to the nip position between the paper feed roller 21 and the separating member 22, and it is possible to prevent double feeding and conveyance failure.

H Document reading apparatus A Document conveying apparatus 1 Contact glass 10 Paper feeding tray 20 Feeding roller 21 Paper feeding roller 22 Separating member 23 Registration roller pair 24 Conveying roller pair 50 Shaft 51 Transmission member 52 Engaging piece 53 Engaging member 54 Engaging groove S3 Lead sensor S5 First sensor S6 Second sensor VR Volume MT Drive motor CL1 First electromagnetic clutch CL2 Second electromagnetic clutch 100 Control board (control unit)

Claims (7)

A paper feed tray for placing a document, a feed roller for feeding the document on the paper feed tray, a paper feed roller for feeding the fed document, and a separating member that presses against the paper feed roller and separates the document A pair of conveyance rollers that conveys the original separated into a reading position for reading the original, and a pair of feed rollers that are arranged downstream of the reading position and convey the original that has passed through the reading position . In the document feeder,
Detection means for detecting the length of the document, and control means for controlling driving of the paper feed roller , the transport roller pair, and the feed roller pair for transporting the document,
The control means includes
A first transport mode in which the transport roller pair is driven in a state where the paper feed roller is stopped, and a rear end of the document passes through the nip portion of the paper feed roller and the separating member; A second conveyance mode for driving the pair of conveyance rollers to pass the trailing edge of the document through the nip portion of the sheet feeding roller and the separating member;
If the length of the document detected by the detection means is longer than the distance from the paper feed roller to the pair of feed rollers, the first transport mode is selected, and the length of the document is from the paper feed roller. And a selecting unit that selects the second transport mode when the distance to the feed roller is shorter than the distance to the feed roller .   2. The control unit according to claim 1, wherein the control unit controls the paper feed roller and the transport roller pair so that the document transport speed by the paper feed roller and the document transport speed by the transport roller pair are the same. The document feeder described. The paper feed roller in the second transport mode is driven when a predetermined position on the rear end side of the document reaches a nip portion between the paper feed roller and the separation member, and the rear end of the document is the paper feed roller. 3. The document conveying device according to claim 1 , wherein the document conveying device is controlled to stop after passing through a nip portion of the separating member. The document conveying apparatus according to claim 1 , further comprising a delay unit configured to rotate the feeding roller after the sheet feeding roller is rotated by a certain amount. The control means stops the paper feed roller after abutting and aligning the leading edge of the document with the stopped first transport roller pair, and then drives the transport roller to perform the first transport mode or The document conveying apparatus according to claim 1 , wherein conveyance of the document is controlled so as to execute the second conveyance mode. A paper feed tray for placing a document, a feed roller for feeding the document on the paper feed tray, a paper feed roller for feeding the fed document, and a separating member that presses against the paper feed roller and separates the document A pair of conveying rollers for conveying the original separated into a reading position for reading the original, a reading means for reading the original passing through the reading position, and passing through the reading position disposed downstream of the reading position. An image reading apparatus comprising a pair of feed rollers for conveying a prepared document ,
A detection unit that acquires document length information and specifies a sheet length from the length information; and a control unit that controls driving of the paper feed roller, the transport roller pair , and the feed roller pair. ,
The control means includes
A first conveyance mode in which the conveyance roller pair is driven to convey the document and the paper supply roller is stopped to pass through the nip portion between the paper supply roller and the separating member; and the conveyance roller pair is driven. After the document is transported and the paper feed roller is stopped, the paper feed roller is re-driven at the same speed as the document transport speed of the pair of transport rollers, and the document is moved through the nip portion between the paper feed roller and the separating member. A second transport mode for passing;
If the length of the document specified by the detection means is longer than the distance from the paper feed roller to the pair of feed rollers, the first transport mode is selected, and the length of the document is from the paper feed roller. An image reading apparatus comprising: a selecting unit that selects the second transport mode when the distance to the feed roller is shorter than the distance to the feed roller . The image reading apparatus according to claim 6 , further comprising a delay unit configured to rotate the feeding roller after the sheet feeding roller is rotated by a certain amount.

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