JP2007112521A - Document feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for enhancing feeding accuracy of a document feeding means provided on a document feeding passage in a document feeder in which drive force is transmitted from a single drive source to a plurality of drive portions through a predetermined drive force transmission mechanism. <P>SOLUTION: An ADF 3 is provided with a single motor 67; drive force transmission mechanisms 120, 150 for performing transmission of drive force from the motor 67 to feed rollers 35A-D and a switch back roller 43; and drive force transmission mechanisms 70, 170 for performing transmission of drive force from the motor 67 to a separation roller 34 and a guide flap 50 respectively. The drive force transmission mechanisms 70, 120, 150, 170 shares a drive gear 69 provided on a drive output shaft of the motor 67 and a transmission gear 71 engaged with the drive gear 69. The drive force transmission mechanisms 120, 150 have a gear row branched from the transmission gear 71 and the drive force transmission mechanisms 70, 170 have a gear row branched from the transmission gears 72, 73 in a downstream side in a drive force transmission direction from the transmission gear 71. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a document conveying means provided in a document conveying path, a switchback conveying means provided in a switchback conveying path, and other driving parts from a single driving source via a predetermined driving force transmission mechanism. The present invention relates to a document conveying device to which a driving force is transmitted.

  2. Description of the Related Art Conventionally, in an image reading apparatus mounted on a copying apparatus, a scanner apparatus, a multi-function apparatus having both a copying function and a scanner function, an ADF (Auto Document) that conveys a document from a sheet feeding tray to a sheet discharging tray via a conveying path. A device having a document feeder called a “Feeder” is known. Further, in order to read a document printed on both sides of the first surface and the second surface, the leading edge and the trailing edge of the document are reversed by conveying the document in a switchback manner during the conveyance, so that both sides of the document are read. There is known a document conveying apparatus that conveys the document (for example, see Patent Document 1).

  FIG. 33 shows a conveyance path of a conventional document conveying apparatus capable of reading on both sides. As shown in the figure, a document P placed on the sheet feed tray 100 with the first surface (first page) facing upward is fed to the conveyance path 102 by the sheet feed roller 101. In the transport path 102, the document P is transported to transport rollers 103 provided as appropriate, and when passing through the reading position X, the first surface of the document P is read by an image reading means such as a CCD or CIS. When the sensor detects the trailing edge of the document P after the first surface is read, the paper discharge roller 104 is stopped in a state where the vicinity of the trailing edge of the document is nipped.

  As shown in FIG. 34, the document P is conveyed to the switchback path 105 by rotating the paper discharge roller 104 in the reverse direction. The document P enters again from the switchback path 105 to the upstream side of the reading position X of the conveyance path 102. As a result, the leading edge and the trailing edge of the document P are reversed. Then, the document P is transported by the transport roller 103 and when the document P passes through the reading position X, the second surface of the document P is read by the image reading unit. When the sensor detects the trailing edge of the document P after the second surface is read, the paper discharge roller 104 is stopped again with the vicinity of the trailing edge of the document nipped, and then the document P reverses the switchback path 105. Sent. The document P that has entered the conveyance path 102 again from the switchback path 105 is in a state in which the leading edge and the trailing edge are reversed again, that is, the first surface is opposed to the reading position X. Then, the document P is transported through the transport path 102 and discharged onto the paper discharge tray 106 with the first surface facing downward. As a result, both sides of the first side and the second side of the original P are read, and the original P is discharged to the discharge tray 106 in the order of being stacked on the paper feed tray 100.

  The paper feed roller 101, the transport roller 103, and the paper discharge roller 104 are rotated in a predetermined direction by the driving force transmitted from the motor. The paper feed roller 101 and the conveyance roller 103 are always rotated in one direction, that is, in a direction in which the document P is fed from the upstream side to the downstream side of the conveyance path 102. On the other hand, the paper discharge roller 106 is rotated in both forward and reverse directions to perform switchback conveyance. For example, as shown in FIG. 34, when the document P is nipped between the transport roller 103 and the paper discharge roller 104, the document feed direction of the transport roller 103 matches the document feed direction of the paper discharge roller 104. Need to be. When a document is nipped between the conveyance roller 103 and the discharge roller 104 immediately upstream of the reading position X, the document feed direction of the conveyance roller 103 and the document feed direction of the discharge roller 104 are the same. It must be done. Therefore, for example, a motor for driving the transport roller 103 and a motor for driving the paper discharge roller 104 are provided separately. Can be switched.

  Further, a configuration is conceivable in which driving force is transmitted from a single motor to the paper feed roller 101, the transport roller 103, the paper discharge roller 104, and the like by a driving force transmission mechanism mainly including a gear train. In such a configuration, in order to distribute the driving force from the motor to the paper feed roller 101 or the like, a gear train for transmitting the driving force from the predetermined gear to the paper feed roller 101 or the like is branched (Patent Document 2, (See FIG. 5).

JP-A-8-85649 JP-A-3-268568

  As described above, when the driving force is transmitted from the single motor to the plurality of driving parts such as the sheet feeding roller 101 by the respective gear trains, the gear trains that transmit the driving force to the respective driving parts are: It is branched from a predetermined gear downstream in the driving force transmission direction from the driving gear provided on the rotating shaft of the motor. In general, an appropriate backlash is formed between meshing gears in consideration of manufacturing tolerances and deformation such as thermal expansion in order to smoothly rotate the gears. This backlash causes problems such as a decrease in rotational accuracy, a shock during acceleration / deceleration, vibration at low speed rotation, and unstable rotation. As the number of gears in the gear train increases, backlash accumulates and the above-described problems appear more remarkably.

  In addition, when the driving force is distributed from a single motor and transmitted by each gear train, several gears close to the driving gear are transmitted to each driving force transmission mechanism that transmits the driving force to each driving part. Will be shared. The shared gear is transmitted with load fluctuations generated in the respective drive parts through the respective gear trains, and the gear may rotate by the amount of backlash. As a result, load fluctuations in a certain driving part affect driving of other driving parts. For example, in the case of the paper feed roller 101 and the conveyance roller 103, the influence appears as a fluctuation in conveyance speed.

  For example, if the conveyance speed fluctuates while a document is being conveyed on the reading position X of the conveyance path 102, there arises a problem that the read image is deteriorated. When reading an image of a document at a high resolution, if the memory area for storing image data is insufficient, the document conveyed on the reading position is temporarily stopped, and the conveyance is resumed when the memory area is released. Control is performed. At this time, even if the motor is stopped due to the gear backlash described above, the conveying roller 103 does not stop immediately but slightly rotates and the document is conveyed. Therefore, the control of stopping and restarting image reading in consideration of this is performed. Although it is necessary, if the backlash becomes large and unstable, it is difficult to control image reading, and the read image deteriorates before and after the conveyance stops. Further, a shock generated during acceleration / deceleration when the conveyance roller 103 is stopped and restarted may affect the document conveyance accuracy.

  On the other hand, the discharge roller 104 for switchback conveyance of the document P is stopped and reversed after the rear end of the document P in the conveyance direction passes through the branch position between the conveyance path 102 and the switchback path 105. The timing for stopping and reversing the discharge roller 104 is managed based on the number of rotations of the motor after the document sensor provided in the conveyance path 102 detects the trailing edge of the document P in the conveyance direction. Therefore, if the gear backlash increases in the driving force transmission mechanism to the paper discharge roller 104, it becomes difficult to control the paper discharge roller 104 with high accuracy. As a result, before the trailing edge of the document P in the transport direction passes through the branch position to the switchback path 105, the motor is stopped or reversed, or the trailing edge of the document P to be switched back is transported in the discharge roller 104. The problem of passing through and exiting occurs. In particular, when the distance from the document sensor to the paper discharge roller 104 is long and the distance from the branch position of the switchback path 105 to the paper discharge roller 104 is short, the above-described problem is likely to occur.

  The present invention has been made in view of such circumstances, and in an original conveying apparatus in which driving force is transmitted from a single driving source to a plurality of driving parts via a predetermined driving force transmitting mechanism, the original conveying path is provided. It is an object of the present invention to provide means for improving the conveyance accuracy of the document conveyance means provided and the switchback conveyance means provided in the switchback conveyance path.

  (1) A document transport device according to the present invention includes a document transport path that connects a document placement section and a document discharge section through a reading position, and the document transport path provided in the document transport path from the document placement section. A document transport means for transporting the document to the scanning unit, a switchback transport path connected to a predetermined position of the document transport path, and a front end and a rear end of the document from the downstream side of the reading position. And a single drive source for applying a driving force to the document conveying means, the switchback conveying means, and other driving parts; and A first driving force transmission mechanism that transmits a driving force from the driving source to the document conveying means; a second driving force transmission mechanism that transmits a driving force from the driving source to the switchback conveying means; Each drive A third driving force transmission mechanism that transmits the driving force to each of the first driving force transmission mechanism, the second driving force transmission mechanism, and the third driving force transmission mechanism from the driving source. And a transmission gear meshing with the drive gear. The first driving force transmission mechanism and the second driving force transmission mechanism are branched from the transmission gear and the document conveying means. The third driving force transmission mechanism branches from a predetermined transmission gear downstream of the transmission gear in the driving force transmission direction to transmit the driving force to each driving part. It has the gear or gear train to perform.

  The document feeder has a single drive source. A driving force is transmitted from the single driving source to the document conveying means via the first driving force transmission mechanism. The original fed to the original conveying path is conveyed by the original conveying means to which the driving force is applied so as to pass the reading position. A driving force is transmitted from a single driving source to the switchback conveying means via the second driving force transmission mechanism. By the switchback conveying means to which the driving force is applied, the leading edge and the trailing edge of the document that has passed the reading position are reversed and returned to the document conveying path. The driving force is transmitted from the single driving source to the plurality of other driving parts via the third driving force transmission mechanism. Each driving part to which the driving force is applied performs a predetermined operation.

  The first driving force transmission mechanism, the second driving force transmission mechanism, and the third driving force transmission mechanism share a driving gear provided on a driving output shaft from a single driving source and a transmission gear that meshes with the driving gear. To do. The first driving force transmission mechanism and the second driving force transmission mechanism transmit the driving force to the document conveying means or the switchback conveying means by a gear or a gear train branched from the transmission gear. The third driving force transmission mechanism transmits the driving force to each of the other driving parts by a gear or a gear train branched from a predetermined transmission gear downstream of the transmission gear in the driving force transmission direction. Only the backlash between the drive gear and the transmission gear exists in the transmission gear meshed with the drive gear. On the other hand, on the downstream side in the driving force transmission direction from the transmission gear, there is an accumulation of backlash corresponding to the number of additional gears. By transmitting the driving force to the document conveying means or the switchback conveying means as a gear train that branches the first driving force transmitting mechanism and the second driving force transmitting mechanism from the transmission gear, a driving force transmission with less backlash can be achieved. Realized. Further, since the backlash of the transmission gear is small, it is possible to suppress the load fluctuation generated in the other driving parts from affecting the transport by the document transport unit and the switchback transport unit via the transmission gear.

  (2) The driving part to which the driving force is transmitted by the third driving force transmission mechanism is provided in the original document placing section and feeds the original document to the original document conveyance path, and a predetermined part of the original document conveyance path. It is preferable to include guide means for switching the transport route at the position.

  The feeding unit feeds the document placed on the document placement unit to the document transport path. Since the document fed to the document transport path is transported along the document transport path by the document transport unit, the feed unit is not involved in transporting the document at the reading position, and transports when feeding the document. A slight change in speed does not adversely affect document conveyance and image reading.

  The guiding means switches the conveyance path at a predetermined position on the document conveyance path. The transport path to be switched is, for example, a switchback transport path. The guide unit only needs to complete the switching to the desired transport path before the leading end of the document in the transport direction reaches the predetermined position, and a slight change in the speed of the switching operation adversely affects the operation of the guide unit. There is no effect. Therefore, at least the feeding unit and the guide unit can be a driving force transmission mechanism with more backlash than the document conveying unit and the switchback conveying unit.

  (3) The third driving force transmission mechanism may be branched from the second driving force transmission mechanism.

  The backlash in the first driving force transmission mechanism affects the conveyance accuracy of the document conveyance unit, and causes deterioration of the read image. In particular, when conveying an original suitable for high-resolution image reading, a conveyance error corresponding to several lines of the line image sensor affects the read image. On the other hand, the switchback conveyance unit is not required to have the conveyance accuracy as high as that of the document conveyance unit. Therefore, even if the third driving force transmission mechanism that transmits the driving force to the other driving parts is branched from the second driving force transmission mechanism, the load fluctuation generated in the other driving parts causes the malfunction of the switchback conveying means. It does not have a significant impact. In addition, since the driving force transmission path from the driving source is concentrated in the two directions of the first driving force transmission mechanism and the second driving force transmission mechanism, the configuration of the gear train is simplified.

  (4) The document conveying means is a pair of conveying rollers that are provided at different positions on the document conveying path and convey the document by sandwiching and rotating the document, and the first driving force transmission mechanism. The gear train may transmit a driving force in order from the pair of transport rollers on the downstream side in the transport direction to the transport roller on the upstream side in the transport direction.

  Documents conveyed through the document conveyance path are sandwiched in order from the conveyance roller pair on the upstream side in the conveyance direction. The original is sandwiched between the next pair of transport rollers on the downstream side in the transport direction before being separated from the pair of transport rollers previously sandwiched. If there is a large backlash in the driving force transmission path to the next transport roller pair, the rotation of the transport roller pair becomes unstable when the document is held between the next transport roller pair. If a document held between a pair of conveyance rollers upstream from the reading position is nipped by a pair of conveyance rollers downstream from the reading position, the rotation of the pair of conveyance rollers downstream becomes unstable. In response to this, the conveyance of the original at the reading position becomes unstable, which adversely affects the read image.

  The gear train of the first driving force transmission mechanism transmits the driving force in order from the conveyance roller pair on the downstream side in the conveyance direction to the upstream side in the conveyance direction, so the conveyance roller pair on the downstream side in the conveyance direction is the conveyance roller on the upstream side in the conveyance direction. Less affected by gear train backlash than the pair. Accordingly, the original document that is nipped and conveyed in order by the conveyance roller pair is always nipped by the conveyance roller pair that is less affected by backlash and rotates stably. Thereby, the conveyance of the original in the original conveyance path, particularly the conveyance of the original in the reading position is stabilized.

  Thus, according to the document conveying device according to the present invention, the first driving force transmission mechanism sharing the driving gear provided on the driving output shaft from the single driving source and the transmission gear meshing with the driving gear, In the second driving amount transmission mechanism and the second driving force transmission mechanism, the first driving force transmission mechanism and the second driving force transmission mechanism are arranged so that the document conveying means or the switchback conveyance is performed by a gear or a gear train branched from the transmission gear. The third driving force transmission mechanism transmits the driving force to the other driving parts by a gear or gear train branched from a predetermined transmission gear downstream of the transmission gear in the driving force transmission direction. Therefore, the first driving force transmission mechanism and the second driving force transmission mechanism can realize driving force transmission with less backlash, and load fluctuations generated in other driving parts affect the document conveying means. Rukoto is suppressed. Thereby, the conveyance accuracy of the document conveying unit and the switchback conveying unit is improved.

  Embodiments of the present invention will be described below with reference to the drawings as appropriate. In addition, this embodiment is only an example of this invention, and it cannot be overemphasized that embodiment can be changed suitably in the range which does not change the summary of this invention.

  FIG. 1 shows an external configuration of an image reading apparatus 1 according to an embodiment of the present invention, and FIG. 2 shows a main internal configuration of the image reading apparatus 1. The image reading device 1 is, for example, a copy device, a facsimile device, a scanner device, a multi-function device (MFD: Multi Function Device) that is integrally provided with a copy function, a facsimile mechanism, a scanner function, etc. This is realized as an image reading unit for performing the above.

  As shown in FIGS. 1 and 2, the image reading apparatus 1 has an auto document feeder (ADF) that is an automatic document feeder mechanism with respect to a document table 2 that functions as an FBS (Flatbed Scanner). A document cover 4 having 3 is attached so as to be openable and closable via a hinge on the back side (back of the paper surface). This ADF 3 corresponds to the document feeder according to the present invention.

  An operation panel 5 is provided on the front side of the document table 2. The operation panel 5 includes various operation keys 11 and a liquid crystal display unit 12. The user inputs a desired command using the operation panel 5. For example, the operation key 11 is used to input “start” indicating the start of reading of a document and “stop” indicating stop of reading. The image reading apparatus 1 receives these predetermined inputs and performs a predetermined operation. The image reading apparatus 1 is operated not only by a command input to the operation panel 5 but also by a command connected to the computer and transmitted from the computer via a printer driver, a scanner driver, or the like.

  As shown in FIG. 2, the platen glass 20, 21 is disposed on the top surface of the document table 2 facing the document cover 4. When the document cover 4 is opened, the platen glasses 20 and 21 are exposed as the upper surface of the document table 2. When the document cover 4 is closed, the entire upper surface of the document table 2 including the platen glasses 20 and 21 is covered. An image reading unit 22 (image reading means) is built in the document placing table 2 so as to face the platen glasses 20 and 21.

  The platen glass 20 is used to place a document when the image reading apparatus 1 is used as an FBS, and is made of, for example, a transparent glass plate. An opening for exposing the platen glass 20 is formed at the center of the upper surface of the document placing table 2, and an area of the platen glass 20 exposed from the opening becomes an original reading area in the FBS.

  The platen glass 21 is a reading position when the ADF 3 of the image reading apparatus 1 is used, and is made of, for example, a transparent glass plate. An opening for exposing the platen glass 21 is formed at the reading position of the document table 2. The platen glass 21 exposed from the opening is extended in the depth direction of the image reading apparatus 1 corresponding to the length of the image reading unit 22 in the main scanning direction.

  A positioning member 23 is interposed between the platen glass 20 and the platen glass 21. The positioning member 23 is a long flat plate-like member that extends in the depth direction of the image reading apparatus 1, similarly to the platen glass 21. The positioning member 23 is used as a document positioning reference when a document is placed on the platen glass 20 which is a document placement surface in the FBS. Therefore, on the upper surface of the positioning member 23, a display indicating the center position and both end positions of various document sizes such as A4 size and B5 size is written. On the upper surface of the positioning member 23, a guide surface is formed that deflects the document passing over the platen glass 21 by the ADF 3 and returns it to the ADF 3.

  The image reading unit 22 is a so-called image sensor that irradiates a document with light from a light source through the platen glasses 20 and 21, collects reflected light from the document on a light receiving element by a lens, and converts it into an electrical signal. As the image reading unit 22, for example, a close contact type CIS (Contact Image Sensor) image sensor, a reduction optical system CCD (Charge Coupled Device) image sensor, or the like can be used. The image reading unit 22 is provided so as to be able to reciprocate below the platen glasses 20 and 21 by a belt drive mechanism that is a scanning mechanism, and reciprocates in parallel with the platen glasses 20 and 21 by receiving the driving force of the carriage motor. .

  The document cover 4 is provided with an ADF 3 that continuously conveys documents from a paper feed tray 30 (document placement unit) to a sheet discharge tray 31 (document ejection unit) through a document conveyance path 32. In the conveyance process by the ADF 3, the document passes through the reading position on the platen glass 21, and the image reading unit 22 standing under the platen glass 21 reads the image of the document.

  As shown in FIGS. 1 and 2, the document cover 4 is provided with a paper feed tray 30 and a paper discharge tray 31 in two upper and lower stages with the paper feed tray 30 as an upper side. A document for reading an image by the ADF 3 is placed on the paper feed tray 30. A plurality of originals are placed on the paper supply tray 30 so that the front end in the paper supply direction is inserted into the original conveyance path 32 in a stacked state with the first surface facing upward. The protective wall 26 is formed by bending the back side of the sheet feeding tray 30 downward. The lower end of the protective wall 26 is connected to the upper surface of the document cover 4. The protective wall 26 prevents the document on the paper discharge tray 31 from falling when the document cover 4 is opened with respect to the document table 2. A cutout 27 is formed in a part of the casing of the ADF 3 below the front side of the apparatus of the paper feed tray 30. The cutout 27 enhances the visibility of the document discharged from the discharge tray 31 from the front side of the apparatus. In particular, a small-size document is difficult to be visually recognized by the paper feed tray 30, but the space between the paper feed tray 30 and the paper discharge tray 31 is widened by the notch 27. Especially enhanced.

  The paper discharge tray 31 is located at the lower side of the paper feed tray 30 in the vertical direction, and is integrally formed on the upper surface of the document cover 4. The document that has been image-read and discharged from the ADF 3 is held so as to be stacked on the discharge tray 31 with the first side facing down while being separated from the document on the sheet feed tray 30. Both side portions 28 of the paper discharge tray 31 on the front side and the rear side of the apparatus have slopes that bulge upward toward both sides. By the both side portions 28, when the document discharged to the paper discharge tray 31 is taken out, the document can be pulled out by sliding along the slopes of the both side portions 28 while pressing the document from above. It is easy to take out the document from the tray 31.

  As shown in FIG. 2, in the ADF 3, a document having a substantially U shape in the horizontal direction in a longitudinal sectional view so as to connect a paper feed tray 30 and a paper discharge tray 31 via a reading position on the platen glass 21. A conveyance path 32 is formed. The document conveyance path 32 is continuously formed as a passage having a predetermined width through which a document can pass by members, guide plates, guide ribs, and the like constituting the ADF main body. In this way, the paper feed tray 30 and the paper discharge tray 31 are provided in two upper and lower stages, and the document conveyance path 32 having a substantially U shape in the horizontal direction in the longitudinal sectional view is formed so as to connect them. The width of the ADF 3 can be reduced to reduce the size.

  The document transport path 32 extends from the paper feed tray 30 to one end side (the left side in the figure) of the document cover 4 and is then curved so as to be reversed downward to reach the reading position on the platen glass 21. A longitudinal sectional view extending from the sheet to the sheet discharge tray 31 is a substantially U shape in the horizontal direction. The document conveyance path 32 can be broadly divided into a substantially U-shape and curved so that the upper part 32A and the lower part 32C forming two straight upper and lower linear parts, and the upper part 32A and the lower part 32C are continuous. It consists of three parts with the curved part 32B. The document conveyance path 32 is used as a document conveyance path in common with single-sided reading and double-sided reading of a document by the ADF 3.

  In the document conveyance path 32, a feeding means (other drive part) for feeding documents from the paper feed tray 30 to the document conveyance path 32, and a document fed to the document conveyance path 32, the discharge tray 31. Document conveying means for conveying to the document is disposed. Specifically, as shown in the drawing, the suction roller 33 and the separation roller 34 provided in the document conveyance path 32 correspond to a feeding unit, and the conveyance rollers 35A, 35B, 35C, and 35D and a pinch roller 37 that press-contacts them. Corresponds to the document conveying means. A driving force is transmitted from a single motor 67 (drive source, see FIG. 3) to each roller constituting the document conveying means, and a driving force transmission mechanism to each roller will be described later.

  As shown in the drawing, a suction roller 33 and a separation roller 34 are provided in the vicinity of the uppermost stream of the document conveyance path 32. The suction roller 33 is rotatably provided at the distal end portion of the arm 29 that is pivotally supported by the shaft 111 (see FIG. 9) that pivotally supports the separation roller 34. The separation roller 34 is rotatably provided at a position spaced from the suction roller 33 in the paper feeding direction so as to be in contact with the opposing surface of the document conveyance path 32. The suction roller 33 and the separation roller 34 are rotated by the driving force transmitted from the motor 67, and the arm 29 is also moved up and down by the driving force transmitted from the motor 67. The suction roller 33 and the separation roller 34 have the same diameter and are rotated at the same peripheral speed. A separation pad that presses against the roller surface of the separation roller 34 and separates the document by friction is disposed at a position facing the separation roller 34.

  The conveyance rollers 35A, 35B, 35C, and 35D are disposed at different positions on the document conveyance path 32, respectively. In the present embodiment, a conveyance roller 35A is disposed immediately downstream of the separation roller 34, a conveyance roller 35B is disposed in the upper portion 32A of the document conveyance path 32, and the lower portion 32C of the document conveyance path 32 is. A conveying roller 35C is disposed immediately upstream of the reading position, and a conveying roller 35D is disposed in the lower portion 32C of the document conveying path 32 and immediately downstream of the reading position. The transport rollers 35A, 35B, 35C, and 35D and the pinch roller 37 pressed against them correspond to the transport roller pair according to the present invention. This arrangement is an example, and the number and arrangement of the transport rollers 35A, 35B, 35C, and 35D can be changed as appropriate.

  A pinch roller 37 is provided at a position facing each of the transport rollers 35A, 35B, 35C, and 35D. Each pinch roller 37 is pressed against the roller surface of each conveying roller 35 by its shaft being elastically biased by a spring. If each conveyance roller 35A, 35B, 35C, 35D rotates, it will follow and the pinch roller 37 will also rotate. Each pinch roller 37 presses the document against each conveyance roller 35, and the rotational force of each conveyance roller 35A, 35B, 35C, 35D is transmitted to the document.

  The paper discharge roller 36 is disposed in the vicinity of the most downstream side of the document conveyance path 32, and is rotated by a driving force transmitted from a motor in the same manner as the conveyance rollers 35A, 35B, 35C, and 35D. A pinch roller 37 is also provided at a position facing the paper discharge roller 36, and the pinch roller 37 is elastically biased by a spring and pressed against the paper discharge roller 36.

  A switchback path 39 (switchback conveyance path) is coupled to the coupling position 38 of the lower portion 32C of the document conveyance path 32. The switchback path 39 retransmits a document whose first surface has been read at the reading position from the downstream side to the upstream side of the document conveyance path 32 by reversing the leading end and the trailing end when performing double-sided reading. Is to do. The switchback path 39 extends obliquely upward from the connection position 38 toward the upper side of the paper feed tray 30, and intersects the upper portion 32 </ b> A of the document conveyance path 32. The document that is switched back and conveyed from the intersection position 40 between the upper portion 32A and the switchback path 39 is returned to the document conveyance path 32.

  A terminal end 41 of the switchback path 39 is opened on the upper surface of the ADF 3. A document support portion 42 is formed on the side of the paper feed tray 30 from the end 41 of the switchback path 39 so as to continue from the end 41. The document support portion 42 is for supporting the document protruding from the end 41 of the switchback path 39, and forms the upper cover 6 (see FIG. 1) of the ADF 3 above the paper feed roller 33 and the separation roller 34. ing. The upper cover 6 is formed so as to cover the entire ADF 3 including the paper feed roller 33 and the separation roller 34 and can be opened and closed. The document support portion 42 configured as the upper cover 6 extends from the terminal end 41 toward the paper feed tray 30 side to the upstream side from the paper feed position by the paper feed roller 33 and the separation roller 34. As a result, in duplex reading, the document that enters the switchback path 39 and protrudes from the terminal end 41 to the outside of the ADF 3 is supported on the document support unit 41. The document does not hang down further downstream (left side in the figure), and the original is prevented from being disturbed at the paper feed position. Further, when the upper cover 6 is opened, a part of the document transport path 32 and the switchback 39 in the ADF 3 is exposed, and maintenance work such as jam processing can be performed.

  A switchback roller 43 is disposed immediately downstream from the crossover position 40 of the switchback path 39 on the end 41 side. The switchback roller 43 is driven to rotate in both forward and reverse directions when the driving force from the motor 67 is transmitted. A pinch roller 44 is provided at a position facing the switchback roller 43. The pinch roller 44 is in pressure contact with the roller surface of the switchback roller 43 with its shaft elastically biased by a spring, and rotates in accordance with the rotation of the switchback roller 43. The document is pressed against the switchback roller 43 by the pinch roller 44, and the rotational force of the switchback roller 43 is transmitted to the document. The switchback roller 43 and the pinch roller 44 correspond to switchback conveying means for switchback conveying an original in the present invention.

  In the present embodiment, the switchback path 39 connected to the connecting position 38 on the downstream side of the reading position of the document transport path 32 is crossed with the upper portion 32A of the document transport path 32, and ends from the cross position 40. Although the switchback roller 43 is provided on the 41 side, the conveyance path of the switchback path 39 is arbitrary, and is connected to a predetermined position of the document conveyance path 32 so that the leading edge and the trailing edge of the document are arranged downstream from the reading position. Can be changed as appropriate, as long as it is reversed and returned to the upstream side of the reading position.

  As shown in FIG. 2, a guide flap 46 and a guide flap 47 for guiding the document to a desired conveyance path are disposed at the crossing position 40. The guide flap 46 is disposed so as to be rotatable within a predetermined range with a corner portion between the reading position side of the document conveying path 32 and the connecting position 38 side of the switchback path 39 at the intersection position 40 as a rotation axis. The guide flap 46 is a blade-shaped flat plate, and its tip protrudes to the crossing position 40. In the figure, only one guide flap 46 is shown, but a plurality of guide flaps 46 having the same shape are provided at predetermined intervals in the width direction of the document conveyance path 32 (the vertical direction in FIG. 2 and the apparatus depth direction). The plurality of guide flaps 46 are rotated together.

  The guide flap 46 can be rotated upward from the position shown in FIG. Further, the guide flap 46 is restricted from rotating from the position shown in FIG. 2 to the lower side in the drawing by contacting the guide member of the document conveyance path 32 or the switchback path 39, for example. When the guide flap 46 is at the position shown in FIG. 2, the conveyance path from the paper feed tray 30 side (right side in the figure) to the reading position side (left side in the figure) of the document conveyance path 32 continues at the crossover position 40. The conveyance path from the conveyance path 32 to the connection position 38 side (the lower side in the figure) of the switchback path 39 is closed. As a result, the document that has reached the crossing position 40 from the paper feed tray 30 side of the document conveyance path 32 is allowed to enter the reading position side of the document conveyance path 32, and to the connection position 38 side of the switchback path 39. Entering is stopped. Further, the document that has reached the crossover position 40 from the terminal end 41 side (the upper side in the figure) of the switchback path 39 is allowed to enter the reading position side of the document transport path 32, and the connection position 38 side of the switchback path 39. Entry to is stopped.

  By rotating the guide flap 46 upward in the drawing, the conveyance path from the connection position 38 side to the terminal end 41 side of the switchback path 39 continues, and the document conveyance path 32 from the connection position 38 side of the switchback path 39. The conveyance path to the reading position side is closed. As a result, the document that has reached the crossover position 40 from the connection position 38 side of the switchback path 39 is allowed to enter the terminal end 41 side of the switchback path 39 and enters the reading position side of the document transport path 32. It is restrained.

  Switching of the conveyance path by the guide flap 46 is performed by contacting the original. The guide flap 46 is always in the position shown in FIG. 2 due to its own weight or under the urging force of an elastic member such as a spring. When the document conveyed on the switchback path 39 from the coupling position 38 toward the crossing position 40 contacts the guide flap 46, the guide flap 46 is rotated so as to be pushed upward in the drawing. On the other hand, the document conveyed to the crossover position 40 from the terminal end 41 side of the switchback path 39 abuts on the guide flap 46, but the guide flap 46 does not rotate downward from the position shown in FIG. Since the document is regulated, the document is guided by the guide flap 46 and enters the upper portion 32A of the document transport path 32 to the reading position side. The blade shape of the guide flap 46 is easily changed in posture by the contact of the document conveyed from the connection position 38 side of the switchback path 39 to the crossover position 40, and is conveyed from the terminal end 41 side of the switchback path 39 to the crossover position 40. A shape is adopted in which a document to be guided is easily guided to the reading position side of the document transport path 32. As described above, if the posture of the guide flap 46 is changed by the contact of the document, it is not necessary to positively change the posture of the guide flap 46 by applying a driving force from the motor 67. A guide flap 46 can be realized.

  The guide flap 47 is disposed so as to be rotatable within a predetermined range with a corner between the paper feed tray 30 side of the document transport path 32 and the terminal end 41 side of the switchback path 39 at the intersection position 40 as a rotation axis. The guide flap 47 is a blade-shaped flat plate, and its tip protrudes to the crossing position 40. Although only one guide flap 47 is shown in the figure, a plurality of guide flaps 47 having the same shape are provided at predetermined intervals in the width direction of the document conveying path 32, and the plurality of guide flaps 47 are rotated together. Moved.

  The guide flap 47 can be rotated from the position shown in FIG. 2 to the left side in the drawing. The guide flap 47 is restricted from rotating from the position shown in FIG. 2 to the right side in the figure by contacting the guide member of the document transport path 32 or the switchback path 39, for example. When the guide flap 47 is in the position shown in FIG. 2, the conveyance path from the terminal end 41 side of the switchback path 39 to the reading position side of the document conveyance path 32 continues, and from the connection position 38 side of the switchback path 39. The conveyance path to the paper feed tray 30 side of the document conveyance path 32 is closed. As a result, the document that has reached the crossover position 40 from the end 41 side of the switchback path 39 is allowed to enter the reading position side of the document transport path 32 and is prevented from entering the paper feed tray 30 side. The Also, the document that has reached the crossover position 40 from the connection position 38 side of the switchback path 39 is allowed to enter the terminal end 41 side of the switchback path 39 and enters the paper feed tray 30 side of the document transport path 32. To be stopped.

  When the guide flap 47 is rotated to the left in the figure, the conveyance path from the paper feed tray 30 side to the reading position side of the document conveyance path 32 continues and the switchback is performed from the paper feed tray 30 side of the document conveyance path 32. The conveyance path to the end 41 side of the path 39 is closed. As a result, the document that has reached the crossover position 40 from the paper feed tray 30 side of the document transport path 32 is allowed to enter the reading position side of the document transport path 32 and enters the end 41 side of the switchback path 39. To be stopped.

  Switching of the conveyance path by the guide flap 47 is performed by contacting the original. The guide flap 47 is always in the position shown in FIG. 2 due to its own weight or under the urging force of an elastic member such as a spring. When the document transported from the paper feed tray 30 side of the document transport path 32 contacts the guide flap 47, the guide flap 47 is rotated so as to be pushed leftward in the drawing. On the other hand, even if the document conveyed from the coupling position 38 side of the switchback path 39 to the crossing position 40 abuts against the guide flap 47, the guide flap 47 rotates from the position shown in FIG. Therefore, the document is guided by the guide flap 47 and enters the terminal end 41 side of the switchback path 39. The blade shape of the guide flap 47 is likely to change its posture due to the contact of the document transported from the paper feed tray 30 side of the document transport path 32 to the crossover position 40, and from the connection position 38 side of the switchback path 39 to the crossover position 40. A shape in which the conveyed document is easily guided to the end 41 side of the switchback path 39 is employed. As described above, if the posture of the guide flap 47 is changed by the contact of the document, it is not necessary to positively change the posture of the guide flap 47 by applying a driving force from a motor or the like. A guide flap 47 can be realized.

  As shown in FIG. 2, a guide flap 50 is disposed at the connection position 38. The guide flap 50 is disposed so as to be rotatable about a position between the document conveyance path 32 and the switchback path 39 as a rotation axis. When the driving force is transmitted from the motor 67, the guide flap 50 is shown in FIG. It is rotated downward from the position shown in the figure. The guide flap 50 rotates, for example, from the position shown in FIG. 2 to the upper side in the drawing, or to the lower side in the drawing by contacting the guide member of the document conveyance path 32 or the switchback path 39. Further, it is restricted from rotating further downward in the figure after reaching the position for guiding the document to the switchback path 39. When the guide flap 50 is at the position shown in FIG. 2, the conveyance path from the reading position side (left side in the figure) of the document conveyance path 32 to the discharge tray 31 side (right side in the figure) continues at the connection position 38. As a result, the document that has passed through the reading position is guided through the lower portion 32 </ b> C of the document transport path 32 toward the discharge tray 31 at the connection position 38. When the guide flap 50 is rotated downward from the position shown in FIG. 2, the conveyance path from the downstream side of the reading position of the lower portion 32C of the document conveyance path 32 to the switchback path 39 continues. As a result, the document that has passed the reading position is guided through the connection position 38 so as to enter the switchback path 39. In this way, the guide flap 50 is disposed so that the document can be guided to either the document conveyance path 32 or the switchback path 39 at the connection position 38. In the drawing, only one guide flap 50 is shown, but a plurality of guide flaps 50 of the same shape are provided at predetermined intervals in the width direction of the document conveying path 32, and the plurality of guide flaps 50 are integrated. Is rotated. This guide flap 50 corresponds to the guide means (other drive part) in the present invention.

  As shown in FIG. 2, the document transport path 32 and the switchback path 39 are provided with a plurality of sensors for detecting document transport. Specifically, a first front sensor 52 and a second front sensor 53 are disposed on the upstream side and the downstream side of the separation roller 34 in the document conveyance path 32, respectively, and on the upstream side of the reading position. A rear sensor 54 is provided. A switchback sensor 55 is disposed between the connection position 38 and the crossover position 40 of the switchback path 39. Each of these sensors is a so-called optical sensor that detects the rotation of the detector that appears and disappears in the document conveyance path 32 or the switchback path 39 as on / off of the photo interrupter.

  When a document is placed on the paper feed tray 30, the first front sensor 52 is turned on. Whether the document is placed on the paper feed tray 30 is detected by turning on / off the first front sensor 52. The second front sensor 53 disposed immediately downstream of the separation roller 34 is for detecting the leading edge or trailing edge of the document fed to the document conveying path 32 by turning on / off thereof. For example, the number of rotations of the conveyance rollers 35A, 35B, 35C, and 35D after the second front sensor 53 detects the trailing edge of the document is monitored by the number of steps of the encoder or the motor 67, and the document on the document conveyance path. The position of the front end or the rear end is determined.

  The rear sensor 54 disposed immediately upstream of the reading position is for detecting the leading edge and the trailing edge of the document conveyed on the document conveyance path 32 by turning on / off thereof. By monitoring the number of rotations of the transport rollers 35A, 35B, 35C, and 35D after the rear sensor 54 detects the leading edge or trailing edge of the document, the leading edge or trailing edge of the document is read. It is determined whether or not the position has been reached. Image reading of the image reading unit 22 is controlled based on a signal from the rear sensor 54. Image reading is started when the leading edge of the document reaches the reading position, and image reading is started when the trailing edge of the document reaches the reading position. Is terminated.

  A switchback sensor 55 disposed between the connection position 38 and the crossing position 40 of the switchback path 39 detects the leading edge or the trailing edge of the document conveyed on the switchback path 39 by turning on / off thereof. belongs to. For example, by monitoring the number of rotations of the transport rollers 35A, 35B, 35C, and 35D and the switchback roller 43 after the switchback sensor 55 detects the trailing edge of the document, the number of steps of the encoder or motor 67 is used to monitor the document. It is determined whether the rear end has passed the crossover position 40 or not. By disposing the switchback sensor 55 at a relatively close position upstream of the switchback roller 43 in the conveyance direction, the switchback roller 43 is conveyed more than the rear end of the document is monitored based on a detection signal from the rear sensor 54 or the like. Accuracy can be increased.

  FIG. 3 shows the configuration of the control unit 60 of the image reading apparatus 1. The control unit 60 controls not only the ADF 3 but also the entire operation of the image reading apparatus 1. As shown in the drawing, the control unit 60 is configured as a microcomputer including a CPU 61, a ROM 62, a RAM 63, and an EEPROM (Electrically Erasable and Programmable ROM) 64, and an ASIC (Application Specific Integrated Circuit) via a bus 65. 66.

  The ROM 62 stores a program for controlling various operations of the image reading apparatus 1 and the ADF 3. The RAM 63 is used as a storage area or work area for temporarily storing various data used when the CPU 61 executes the program. The EEPROM 64 is a storage area for storing various settings, flags, and the like that should be stored even after the power is turned off.

  The ASIC 66 generates a phase excitation signal or the like for energizing the motor 67 in accordance with a command from the CPU 61, applies the signal to the drive circuit 68 of the motor 67, and energizes the motor 67 via the drive circuit 68. Thus, the rotation control of the motor 67 is performed. The motor 67 is rotated in both forward and reverse directions, so that the suction roller 33, the separation roller 34, the transport rollers 35 </ b> A, 35 </ b> B, 35 </ b> C, 35 </ b> D, the paper discharge roller 36, the switchback roller (SB roller) 43, and the guide flap 50. A driving force is applied and the ADF 3 is a single driving source.

  The drive circuit 68 drives the motor 67, receives an output signal from the ASIC 66, and forms an electrical signal for rotating the motor 67. In response to the electrical signal, the motor 67 rotates in a predetermined rotational direction, and the rotational force of the motor 67 is supplied to the suction roller 33 and the separation roller via the driving force transmission mechanisms 70, 110, 120, 151, and 170, which will be described later. 34, the transfer rollers 35A, 35B, 35C, and 35D, the paper discharge roller 36, the switchback roller (SB roller) 43, and the guide flap 50.

  Connected to the ASIC 66 is an image reading unit 22 that reads an image of a document conveyed to a reading position by the ADF 3. Based on the control program stored in the ROM 62, the image reading unit 22 reads an image of the document. Although not shown in the figure, a drive mechanism for reciprocating the image reading unit 22 is also operated in response to an output signal from the ASIC 66.

  A first front sensor 52, a second front sensor 53, a rear sensor 54, and a switchback sensor 55 are connected to the ASIC 66. The CPU 61 receives on / off of each sensor, and causes the ASIC 66 to output a predetermined output signal based on a control program stored in the ROM 62 to operate the motor 67 and the image reading unit 22.

  A paper feed solenoid 88 and a switchback solenoid (SB solenoid) 161 are connected to the ASIC 66. Based on the control program stored in the ROM 62, the CPU 61 causes the ASIC 66 to output an output signal at a predetermined timing to operate the paper feed solenoid 88 and the switchback solenoid 161.

  Hereinafter, a driving force transmission mechanism from the motor 67 to the suction roller 33, the separation roller 34, the transport rollers 35A, 35B, 35C, and 35D, the paper discharge roller 36, the switchback roller 43, and the guide flap 50 will be described. The shafts of the separation roller 34, the conveyance rollers 35 </ b> A, 35 </ b> B, 35 </ b> C, 35 </ b> D, the paper discharge roller 36, the switchback roller 43, and the guide flap 50 are extended in the width direction of the document conveyance path 32. The separation roller 34, the conveyance rollers 35 </ b> A, 35 </ b> B, 35 </ b> C, and 35 </ b> D, the paper discharge roller 36, the switchback roller 43, and the guide flap 50 are provided at predetermined positions on each axis according to the width of the document conveyance path 32. Of course, each roller or the like may be provided over substantially the entire axial direction of each axis, or a plurality of rollers or the like may be coaxially arranged at predetermined intervals in the width direction of the document conveyance path 32.

  As shown in FIG. 1, the ADF 3 provided on the upper surface of the document cover 4 has a document conveyance path 32 and each roller accommodated in a housing. A motor 67 for applying a driving force to each roller and a driving force transmission mechanism are also accommodated in the casing of the ADF 3. The motor 67 and the driving force transmission mechanism are provided on one end side in the width direction of the document conveyance path 32 of the ADF 3. A driven gear is provided on one end side of each shaft of the separation roller 34, the transport rollers 35 </ b> A, 35 </ b> B, 35 </ b> C, 35 </ b> D, the paper discharge roller 36, the switchback roller 43, and the guide flap 50. Each roller is driven by transmitting driving force from the motor 67 to each driven gear via each driving force transmission mechanism. In the present embodiment, the motor 67, each driving force transmission mechanism, the separation roller 34, the transport rollers 35A, 35B, 35C, and 35D, the paper discharge roller 36, the switchback roller 43, and the guide flap 50 are arranged at one end side. Each driven gear provided is accommodated in a space 7 on the back side of the device of the housing of the ADF 3. Each gear shown below is a spur gear in which teeth parallel to the axis are formed on the outer periphery unless otherwise limited.

  4 to 8 show the driving force transmission mechanism 70 from the motor 67 to the separation roller 34. The driving force transmission mechanism 70 corresponds to the third driving force transmission mechanism in the present invention. The driving force transmission mechanism 70 transmits the driving force in the feeding direction to the separation roller 34 as the motor 67 rotates clockwise (CW: clock wise), and counterclockwise (CCW: counter clock wise) from CW rotation. By switching to rotation, transmission of the driving force to the separation roller 34 is cut off. The CW rotation and the CCW rotation are opposite directions of rotation of the motor 67 and correspond to forward rotation and reverse rotation, respectively.

  As shown in FIG. 4, four transmission gears 71, 72, 73, 74 are sequentially meshed with a drive gear 69 provided on the drive shaft of the motor 67, and the driving force is transmitted to the planetary gear device 75. ing. The transmission gear 71 is a transmission gear shared by the first driving force transmission mechanism, the second driving force transmission mechanism, and the third driving force transmission mechanism according to the present invention. In this embodiment, the transmission gear 71 is driven by the separation roller 34. A driving force transmission mechanism 70 that transmits force, a driving force transmission mechanism 120 that transmits driving force to the conveying rollers 35A to 35D, a driving force transmission mechanism 150 that transmits driving force to the switchback roller 43, and a driving force to the guide flap 50 Is shared by the driving force transmission mechanism 170. The transmission gear 72 of the driving force transmission mechanism 70 is used as the sun gear 72 in the driving force transmission mechanism 150 that transmits the driving force to the switchback roller 43 and the driving force transmission mechanism 170 that transmits the driving force to the guide flap 50. Shared as a transmission gear. Further, the transmission gear 73 of the driving force transmission mechanism 70 is shared as a transmission gear of the driving force transmission mechanism 170 that transmits the driving force to the guide flap 50. In this way, the third driving force transmission mechanism according to the present invention is branched from the second driving force transmission mechanism. In response to the CW rotation or CCW rotation of the motor 67, the sequentially engaged transmission gears 71, 72, 73 rotate in a predetermined direction, and the driving force is transmitted so that the transmission gear 74 rotates CCW or CW.

  FIG. 6 shows the configuration of the planetary gear device 75. In the planetary gear device 75, a support arm 78 is rotatably provided coaxially with the shaft 77 of the sun gear 76, and two planetary gears 79 and a planetary gear 80 that respectively mesh with the sun gear 76 are pivotally supported on the support arm 78. Being done.

  The sun gear 76 is a two-stage gear in which a large-diameter gear 76L and a small-diameter gear 76S are coaxially and integrally configured. The support arm 78 has arm portions 81 and 82 extending in two radial directions from the shaft 77, and the planetary gears 79 and 80 are respectively pivoted by bearing portions 83 and 84 formed at the tips of the arm portions 81 and 82. It is something to support. The planetary gears 79 and 80 supported by the support arm 78 are engaged with the gear 76S of the sun gear 76, respectively. When the sun gear 76 rotates, the planetary gears 79 and 80 respectively meshed with the gear 76S rotate. Further, the support arm 78 also rotates in the same direction in response to the rotation of the sun gear 76. That is, when the sun gear 76 rotates, the planetary gears 79 and 80 revolve around the sun gear 76 while rotating respectively.

  A locking recess 85 is formed in the vicinity of the shaft 77 of the support arm 78. When the locking recess 85 is locked by the locking mechanism 86, the support arm 78 is stopped at a predetermined position regardless of the rotation of the sun gear 76. The posture in which the support arm 78 is locked to the locking mechanism 86 is a disengagement posture described later.

  The locking mechanism 86 includes a locking member 87 and a paper feed solenoid 88. The locking member 87 includes an arm portion 90 extending in a radial direction from the shaft 89 toward the support arm 78, a locking claw 91 formed in a hook shape at the tip of the arm portion 90, and a radial direction from the shaft 89. And a passive portion 92 extending to the center. The locking claw 91 can be engaged with the locking recess 85 of the support arm 78, and is engaged with and disengaged from the locking recess 85 when the arm 90 is rotated about the shaft 89. The passive portion 92 is connected to the shaft 93 of the paper feed solenoid 88. The sheet feed solenoid 88 is actuated by electromagnetic force when electric power is supplied (turned on), linearly drives the shaft 93 in a direction to immerse the main body in the main body, and is cut off (off) by electromagnetic force. Disappears, and the shaft 93 is elastically returned in the direction of protruding from the main body. The drive of the shaft 93 is transmitted to the passive portion 92, and the locking member 87 is rotated about the shaft 89 to assume a predetermined posture. With the sheet feed solenoid 88 turned off, the locking member 87 is in a posture in which the locking claw 91 can engage with the locking recess 85 of the support arm 78 as shown by a solid line in FIG. With the sheet feeding solenoid 88 turned on, the locking member 87 is in a posture to disengage the locking claw 91 from the locking recess 85 as shown by a two-dot chain line in FIG.

  As shown in FIG. 4, the transmission gear 74 meshes with the gear 76 </ b> L of the sun gear 76 of the planetary gear device 75. When the driving force is transmitted from the motor 67 and the transmission gear 74 rotates in a predetermined direction, the sun gear 76 is rotated in a predetermined direction. For example, as shown in FIG. 4, when the drive gear 69 rotates CW, the transmission gear 74 rotates CW and the sun gear 76 rotates CCW. Since the support arm 78 is rotatable when the paper feed solenoid 88 is on, the planetary gears 79 and 80 revolve by CW rotation. The paper feed solenoid 88 only needs to be turned on when the latching claw 91 is detached from the latching recess 85, and even if the paper feed solenoid 88 is turned off after the support arm 78 is rotated from the detached posture, The locking claw 91 does not engage with the locking recess 85.

  As shown in FIG. 5, a transmission gear 94 is disposed adjacent to the planetary gear device 75. The transmission gear 94 can be separated from the planetary gears 79 and 80 of the planetary gear device 75. As shown in the figure, the planetary gears 79 and 80 revolve around the CCW rotation, whereby the planetary gear 79 meshes with the transmission gear 94 and the planetary gear 80 moves away from the transmission gear 94. The transmission gear 94 is a two-stage gear in which a large-diameter gear 94L and a small-diameter gear 94S are coaxially and integrally configured. The planetary gears 79 and 80 can be engaged with and separated from the large-diameter gear 94L. The small-diameter gear 94S meshes with a driven gear 95 provided on a shaft 111 (see FIG. 9) that supports the separation roller 34. The gear configuration from the transmission gear 94 to the driven gear 95 is not particularly limited, and the number and diameter of the transmission gears can be appropriately changed according to the distance from the transmission gear 94 to the driven gear 95.

  When the planetary gear 79 revolved by the CCW rotation meshes with the transmission gear 94, the revolution of the planetary gear 79 is stopped. Then, the planetary gear 79 rotates by CW rotation upon receiving the driving force from the sun gear 76. In response to this, the transmission gear 94 rotates CCW and the driven gear 95 rotates CW. As the driven gear 95 rotates CW, the shaft 111 that supports the separation roller 34 is rotated in the paper feeding direction.

  As shown in FIG. 7, when the drive gear 69 is switched from CW rotation to CCW rotation, the transmission gear 74 rotates CCW and the sun gear 76 rotates CW. As shown in FIG. 5, in a state where the planetary gear 79 is engaged with the transmission gear 94, the locking claw 91 does not engage with the locking recess 85 even if the paper feed solenoid 88 is off. Therefore, since the support arm 78 is rotatable, the planetary gears 79 and 80 revolve by CW rotation. As the planetary gears 79 and 80 revolve, the support arm 78 rotates, so that the locking recess 85 of the support arm 85 can be engaged with the locking claw 91. At this time, if the paper feed solenoid 88 is off, the locking claw 91 is engaged with the locking recess 85 as shown in FIG. 7, and the rotation of the support arm 78 is restricted. In this state, both the planetary gears 79 and 80 are not meshed with the transmission gear 94. The posture of the support arm 78 that separates the planetary gears 79 and 80 from the transmission gear 94 is referred to as a separation posture in this specification. When the locking claw 91 is engaged with the locking recess 85, the support arm 78 is locked in a non-rotatable manner, and then the support arm 78 is held in the disengaged position until the paper feed solenoid 88 is turned on. The

  As shown in FIG. 8, when the paper feed solenoid 88 is turned on, the planetary gears 79 and 80 revolve with the CW rotation based on the CW rotation of the sun gear 76. When the planetary gear 80 revolved by the CW rotation meshes with the transmission gear 94, the revolution of the planetary gear 80 is stopped. Then, the planetary gear 80 rotates by CCW rotation upon receiving the driving force transmitted from the sun gear 76. In response to this, the transmission gear 94 rotates CW and the driven gear 95 rotates CCW. As the driven gear 95 rotates CCW, the shaft 111 that supports the separation roller 34 is rotated in the direction opposite to the paper feeding direction. Such transmission gears 72, 73, 74, 94 and the planetary gear device 86 correspond to the gear train of the third driving force transmission mechanism of the present invention.

  Hereinafter, the driving force transmission mechanism 110 from the shaft 111 that supports the separation roller 34 to the suction roller 33 will be described. As shown in FIG. 2, the suction roller 33 is pivotally supported on the distal end side of the arm 29 and is disposed on the opposite side of the feeding direction from the separation roller 34. As described above, the driving force of the motor 67 is transmitted to the shaft 111, and the driving force is transmitted from the shaft 111 to the arm 29, the suction roller 33 and the separation roller 34.

  FIG. 9 shows the driving force transmission mechanism 110 from the shaft 111 to the suction roller 33. The driving force transmission mechanism 110 includes a one-round clutch 112 provided on a shaft 111, a gear 113 formed integrally with the separation roller 34, a gear 115 fixed to the shaft 114 of the suction roller 33, and a gear 113 to a gear. And a transmission gear 116 for transmitting driving force to 115. The separation roller 34 is rotatably supported on the shaft 111. The one-round clutch 112 and the gear 113 are respectively provided on both sides in the axial direction of the separation roller 34. In FIG. 9, the one-round clutch 112 is provided on the rear side of the separation roller 34 in the figure, and the front side is illustrated. Since the gear 113 is provided, the one-round clutch 112 on the back side of the separation roller 34 is indicated by a dotted line.

  The one-round clutch 112 includes a pin 117 protruding in the radial direction from the shaft 111 and a locking piece 118 protruding in the axial direction from the separation roller 34. The pin 117 protrudes in the radial direction of the shaft 111 on the side of the separation roller 34, and rotates with the rotation of the shaft 111. The locking piece 118 protrudes in the axial direction from the side surface of the separation roller 34. The position of the locking piece 118 with respect to the radial direction of the separation roller 34 is within the range of the protruding length of the pin 117, and the pin 117 and the locking piece 118 can be engaged. As shown in the figure, when the pin 117 is engaged with the locking piece 118, the rotation of the shaft 111 is transmitted to the separation roller 34 via the pin 117 and the locking piece 118, and the separation roller 34 is connected to the shaft 111. It is rotated in the same direction.

  Since the separation roller 34 is rotatable with respect to the shaft 111, the separation roller 34 is rotatable in a direction in which the locking piece 118 is separated from the pin 117. Then, when the separation roller 34 rotates about one turn with respect to the shaft 111, the locking piece 118 reaches the position of the pin 117 again and engages. As a result, the separation roller 34 can rotate idly for approximately one round regardless of the transmission of the driving force from the shaft 111.

  A transmission gear 116 is interposed between the gear 113 provided on the separation roller 34 and the gear 115 fixed to the shaft 114 of the suction roller 33. The transmission gear 116 meshes with the gear 113 and the gear 115. Since the gear 113 is integral with the separation roller 34, the gear 113 is rotated as the separation roller 34 rotates. The transmission gear 116 is rotated by the rotation of the gear 113, and the gear 115 is rotated by the rotation of the transmission gear 116. Since the gear 115 is fixed to the shaft 114 of the suction roller 33, the suction roller 33 is rotated with the rotation of the gear 115. That is, the separation roller 34 and the suction roller 33 are always rotated in the same direction. By such a driving force transmission mechanism 110, the driving force is transmitted from the shaft 111 that rotatably supports the separation roller 34 to the separation roller 34 and the suction roller 22.

  As shown in FIG. 9, the base end side of the arm 29 is rotatably supported by a shaft 111, and a driving force is transmitted from the shaft 111 to move up and down. A slip clutch (not shown) is provided between the shaft 111 and the base end side of the arm 29. The rotation of the shaft 111 is transmitted to the arm 29 by the slip clutch. In the slip clutch, when a load of a predetermined torque or more is applied, the clutch plate slips and the driving force transmission is cut off. When the shaft 111 rotates CW, a rotational force is transmitted to the arm 29 via the slip clutch, and the arm 29 rotates in a direction in which the suction roller 33 is lowered. On the other hand, if the shaft 111 rotates in the CCW direction, the arm 29 rotates in a direction in which the suction roller 33 is raised. As shown in FIG. 2, when the arm 29 rotates in a direction to lower the suction roller 33, the suction roller 33 comes into contact with the guide surface of the document transport path 32 or the document on the paper feed tray 30. As a result, a load is generated with respect to the rotation of the arm 29, the slip clutch slides, and the shaft 111 can further rotate in a state where the arm 29 is stationary. If the arm 29 rotates in the direction in which the suction roller 33 is raised, the arm 29 comes into contact with the casing of the ADF 3. As a result, a load is generated with respect to the rotation of the arm 29, the slip clutch slides, and the shaft 111 can further rotate in a state where the arm 29 is stationary. In this way, the driving force is transmitted from the shaft 111 to the arm 29 via the slip clutch, and the arm 29 is swung so that the suction roller 33 is lowered or raised with respect to the guide surface of the document conveying path 32.

  10 to 12 show the driving force transmission mechanism 120 from the motor 67 to the transport rollers 35A, 35B, 35C, and 35D. The driving force transmission mechanism 120 transmits a driving force from the upstream side to the downstream side of the document conveyance path 32 to the conveyance rollers 35A, 35B, 35C, and 35D regardless of the rotation direction of the motor 67. . This driving force transmission mechanism 120 corresponds to the first driving force transmission mechanism according to the present invention.

  As shown in FIG. 10, the transmission gear 71 is meshed with a driving gear 69 provided on the driving shaft of the motor 67, and the driving force is transmitted to the planetary gear device 122. As described above, the transmission gear 71 includes the driving force transmission mechanism 120 that transmits the driving force to the separation roller 34, the driving force transmission mechanism 150 that transmits the driving force to the switchback roller 43, and the driving force transmission mechanism 120. The driving force transmission mechanism 170 that transmits the driving force to the guide flap 50 is shared. In response to the CW rotation or CCW rotation of the motor 67, the driving force is transmitted so that the transmission gear 71 rotates CCW or CW.

  In the planetary gear device 122, a support arm 125 is rotatably provided coaxially with the shaft 124 of the sun gear 123, and two planetary gears 126 and a planetary gear 127 respectively meshing with the sun gear 123 are pivotally supported on the support arm 125. Being done.

  The sun gear 123 is a two-stage gear in which a large-diameter gear 123L and a small-diameter gear 123S are coaxially and integrally configured. The planetary gears 126 and 127 pivotally supported by the support arm 125 mesh with the gear 123S of the sun gear 123, respectively. When the sun gear 123 rotates, the planetary gears 126 and 127 respectively meshed with the gear 123S rotate. Further, the support arm 125 also rotates in the same direction in response to the rotation of the sun gear 123. That is, when the sun gear 123 rotates, the planetary gears 126 and 127 revolve around the sun gear 123 while rotating respectively.

  The transmission gear 71 meshes with the gear 123 </ b> L of the sun gear 123 of the planetary gear device 122. When the driving force is transmitted from the motor 67 and the transmission gear 71 rotates in a predetermined direction, the sun gear 123 rotates in the predetermined direction. For example, as shown in FIG. 10, when the drive gear 69 rotates CCW, the transmission gear 71 rotates CW, the sun gear 123 rotates CCW, and the planetary gears 126 and 127 revolve around CCW rotation.

  As shown in the figure, a transmission gear 128 and a transmission gear 129 are disposed adjacent to the planetary gear device 122. The transmission gear 128 is a two-stage gear in which a large-diameter gear 128L and a small-diameter gear 128S are coaxially and integrally configured. Similarly, the transmission gear 129 is a two-stage gear in which a large-diameter gear 129L and a small-diameter gear 129S are coaxially and integrally configured. The planetary gear 126 of the planetary gear device 122 can be engaged with and disengaged from the gear 128 </ b> L of the transmission gear 128. The planetary gear 127 of the planetary gear device 122 can be separated from the gear 129L of the transmission gear 129. Further, the gear 128L and the gear 129L are meshed with each other.

  As shown in FIG. 10, the planetary gears 126 and 127 revolve by CCW rotation, so that the planetary gear 126 meshes with the gear 128 </ b> L of the transmission gear 128. On the other hand, the planetary gear 127 is detached from the transmission gear 129. When the planetary gear 126 revolved by the CCW rotation meshes with the transmission gear 128, the revolution of the planetary gears 126 and 127 is stopped. Then, the planetary gear 126 rotates by the CW rotation upon receiving the driving force from the sun gear 123. In response to this, the transmission gear 128 rotates CCW. The transmission gear 129 that meshes with the transmission gear 128 rotates CW.

  As shown in FIG. 11, when the drive gear 69 rotates CW, the transmission gear 71 rotates CCW, the sun gear 123 rotates CW, and the planetary gears 126 and 127 revolve around CW rotation. As the planetary gears 126 and 127 revolve by CW rotation, the planetary gear 127 meshes with the gear 129L of the transmission gear 129. On the other hand, the planetary gear 126 is separated from the transmission gear 128. When the planetary gear 127 revolved by the CW rotation is engaged with the transmission gear 129, the revolution of the planetary gears 126 and 127 is stopped. Then, the planetary gear 127 rotates by CCW rotation upon receiving the driving force from the sun gear 123. In response to this, the transmission gear 129 rotates CW. The transmission gear 128 that meshes with the transmission gear 129 rotates CCW. Thus, regardless of whether the drive gear 69 is CW rotation or CCW rotation, the transmission gear 128 is transmitted with the CCW rotation driving force, and the transmission gear 129 is transmitted with the CW rotation driving force. .

  FIG. 12 shows transmission of driving force from the transmission gears 128 and 129 to the respective transport rollers 35A, 35B, 35C, and 35D and the paper discharge roller 36. Five transmission gears 130, 131, 132, 133, and 134 are sequentially meshed with the gear 128S of the transmission gear 128. The transmission gear 133 is engaged with a driven gear 135 provided on the shaft of the conveying roller 35A, and the transmission gear 134 is engaged with a driven gear 136 provided on the shaft of the paper discharge roller 36. As described above, the transmission gear 128 is CCW rotated regardless of the rotation direction of the drive gear 69, and the driving force is sequentially transmitted from the transmission gear 128 to the five transmission gears 130, 131, 132, 133, and 134. In response, the driven gear 135 rotates CW and the driven gear 136 rotates CCW. As the driven gear 125 rotates CW, the transport roller 35A is rotated in the transport direction. Further, when the driven gear 126 rotates in the CCW direction, the paper discharge roller 36 is rotated in the transport direction.

  Three transmission gears 137, 138, and 139 are sequentially meshed with the gear 129S of the transmission gear 129. Then, the driven gear 140 provided on the shaft of the conveying roller 35D is engaged with the gear 129S, the driven gear 141 provided on the shaft of the conveying roller 35C is engaged with the transmission gear 138, and the conveying roller 139 is engaged with the conveying roller 139. A driven gear 142 provided on the shaft of 35B is meshed. As described above, the transmission gear 129 is CW-rotated regardless of the rotation direction of the drive gear 69, and the driving force is sequentially transmitted from the transmission gear 129 to the three transmission gears 137, 138, and 139. In response to this, the driven gears 140 and 141 rotate CCW and the driven gear 142 rotates CW. As the driven gears 140 and 141 rotate CCW, the transport rollers 35D and 35C are rotated in the transport direction. As the driven gear 142 rotates CW, the transport roller 35B is rotated in the transport direction. In this way, the driving force in the transport direction is transmitted to the transport rollers 35A, 35B, 35C, and 35D and the paper discharge roller 36 in the rotational direction of the drive gear 69.

  The planetary gear device 122 and the transmission gears 128 to 134 and 137 to 139 correspond to the gear train of the first driving force transmission mechanism in the present invention. As shown in FIG. 12, in the gear train constituted by the transmission gears 128, 129, and 137 to 139, the conveyance roller 35 </ b> D arranged on the downstream side from the reading position is directed upstream in the conveyance direction of the document conveyance path 32. Then, the driving force is transmitted in the order of the transport roller 35C and the transport roller 35B. A driving force is transmitted to the transport roller 35A disposed on the most upstream side in the transport direction of the document transport path 32 by a gear train including the transmission gears 128 and 130 to 133. Driving force is transmitted through the four transmission gears 130 to 133, and the driving force is transmitted through the gear train having the largest number of gears among the transport rollers 35A, 35B, 35C, and 35D. That is, the order of transmission of the driving force in the transport rollers 35A, 35B, 35C, and 35D is lower.

  As will be described later, the document transported through the document transport path 32 is narrowed in order from the transport roller 35A and the pinch roller on the upstream side in the transport direction by the transport rollers 35B, 35C and 35D and the pinch rollers 37 on the downstream side in the transport direction. Be held. The original document held between the conveyance roller 35 </ b> A and the pinch roller 37 is held between the next conveyance roller 35 </ b> B and the pinch roller 37 on the downstream side in the conveyance direction before being separated from the conveyance roller 35 </ b> A and the pinch roller 37. Similarly, before being separated from the conveyance roller 35B and the pinch roller 37, it is sandwiched between the next conveyance roller 35C and the pinch roller 37 on the downstream side in the conveyance direction, and before being separated from the conveyance roller 35C and the pinch roller 37, the conveyance direction. It is held between the next conveyance roller 35D and the pinch roller 37 on the downstream side.

  As described above, in the driving force transmission mechanism 120, the driving force is sequentially transmitted from the conveyance roller 35D on the downstream side in the conveyance direction to the upstream side in the conveyance direction, so that, for example, the driving force is transmitted on the downstream side in the conveyance direction. The transport roller 35D is less affected by backlash of the gear train than the transport roller 35C on the upstream side in the transport direction. Similarly, the transport roller 35C is less affected by gear train backlash than the transport roller 35B, and the transport roller 35B is less affected by gear train backlash than the transport roller 35A. Therefore, an original document that is nipped in order by the conveyance rollers 35A, 35B, 35C, and 35D and the pinch roller 37 is always held between conveyance rollers that are less affected by backlash and rotate stably. Become.

  For example, the conveyance roller 35C disposed immediately upstream from the reading position of the document conveyance path 32 and the conveyance roller 35D disposed immediately downstream from the reading position are conveyed by the conveyance roller 35C and the pinch roller 37 and read. The leading edge of the document that has passed through the position is sandwiched between the conveyance roller 35D and the pinch roller 37, but the conveyance roller 35D is less affected by backlash than the conveyance roller 35C and is stable in rotation. When the leading end in the transport direction is held between the transport roller 35D and the pinch roller 37, the transport of the document does not become unstable. Thereby, the conveyance of the document at the reading position of the document conveyance path 32 is stabilized.

  13 to 15 show the driving force transmission mechanism 150 and the driving force cutting mechanism 151 from the motor 67 to the switchback roller 43. The driving force transmission mechanism 150 transmits the driving force in the retracting direction or the returning direction to the switchback roller 43 based on the rotation direction of the motor 67. The driving force cutting mechanism 151 cuts transmission of driving force from the motor 67 to the switchback roller 43 when the rotation direction of the motor 67 is switched from the return direction of the switchback roller 43 to the pulling direction. The drawing direction is a direction in which the document is drawn from the document conveyance path 32 to the switchback path 39, and the return direction is a direction in which the document is returned from the switchback path 39 to the document conveyance path 32. The driving force transmission mechanism 150 corresponds to the second driving force transmission mechanism according to the present invention.

  As shown in FIG. 13, the transmission gear 71 is meshed with a drive gear 69 provided on the drive shaft of the motor 67, and the driving force is transmitted to the planetary gear device 153. As described above, the transmission gear 71 includes the driving force transmission mechanism 150, the driving force transmission mechanism 70 that transmits the driving force to the separation roller 34, the driving force transmission mechanism 150 that transmits the driving force to the switchback roller 43, and The driving force transmission mechanism 170 that transmits the driving force to the guide flap 50 is shared. In response to the CW rotation or CCW rotation of the motor 67, the driving force is transmitted so that the transmission gear 71 rotates CCW or CW.

  In the planetary gear device 153, a support arm 156 is rotatably provided coaxially with the shaft 155 of the sun gear 72, and the planetary gear 157 and the planetary gear 158 that mesh with the sun gear 72 are supported on the support arm 156, respectively. Being done.

  The sun gear 72 is a two-stage gear in which a large-diameter gear 72L and a small-diameter gear 72S are coaxially and integrally configured. The sun gear 72 is the transmission gear 72 in the driving force transmission mechanism 70, and the large-diameter gear 72 </ b> L plays the role of the transmission gear 72. The support arm 156 is rotatably provided on the shaft 155 and supports the planetary gears 157 and 158 respectively. The planetary gears 157 and 158 that are pivotally supported by the support arm 156 mesh with the gear 72S of the sun gear 72, respectively. When the sun gear 72 rotates, the planetary gears 157 and 158 respectively engaged with the gear 72S rotate. Further, the support arm 156 also rotates in the same direction in response to the rotation of the sun gear 72. That is, when the sun gear 72 rotates, the planetary gears 157 and 158 revolve around the sun gear 72 while rotating.

  A locking projection 159 is formed near the tip where the support arm 156 pivotally supports the planetary gear 157. When the locking projection 159 is locked to the driving force cutting mechanism 151, the support arm 156 that rotates CCW relative to the shaft 155 of the sun gear 72 is stopped at a predetermined position. As shown in FIG. 13, the posture in which the support arm 156 is locked to the driving force cutting mechanism 151 is a disengagement posture described later.

  The driving force cutting mechanism 151 includes a locking member 160 and a switchback solenoid 161. The locking member 160 includes an arm portion 163 extending in a radial direction from the shaft 162 toward the support arm 156, a locking claw 164 formed in a hook shape at the tip of the arm portion 163, and a radial direction from the shaft 162. And a passive portion 165 extending to the center. The locking claw 164 can be engaged with the locking projection 159 of the support arm 156, and is engaged with and disengaged from the locking projection 159 when the arm portion 163 is rotated about the shaft 162. The passive portion 165 is connected to the shaft 166 of the switchback solenoid 161. The switchback solenoid 161 is actuated by electromagnetic force when electric power is supplied (turned on), linearly drives the shaft 166 in a direction to be immersed in the main body, and the electromagnetic force is cut off (turned off). Disappears, and the shaft 166 is elastically restored linearly in the direction of projecting from the main body. The driving of the shaft 166 is transmitted to the passive portion 165, and the locking member 160 is rotated about the shaft 162 to assume a predetermined posture.

  With the switchback solenoid 161 turned off, the locking member 160 is in a posture in which the locking claw 164 can be engaged with the locking projection 159 of the support arm 156 as shown by the solid line in FIG. The locking member 160 can rotate clockwise from this engagement posture, and is biased by a spring or the like to maintain the engagement posture unless receiving external force. The locking projection 159 rotates with the rotation of the support arm 156, and the rotation direction is a substantially radial direction of the locking member 160 in the engagement posture. Therefore, even if the rotational force of the support arm 156 is transmitted to the locking member 160 via the locking projection 159, the locking member 160 does not rotate from the engagement posture against the urging force of a spring or the like. With the switchback solenoid 161 turned on, the locking member 160 is in a posture to disengage the locking claw 164 from the locking projection 159 as shown by a two-dot chain line in FIG.

  As shown in FIG. 13, the transmission gear 71 meshes with the gear 156 </ b> L of the sun gear 72 of the planetary gear device 153. When the driving force is transmitted from the motor 67 and the transmission gear 71 rotates in a predetermined direction, the sun gear 72 rotates in the predetermined direction. For example, as shown in FIG. 13, when the drive gear 69 rotates CCW, the transmission gear 71 rotates CW and the sun gear 72 rotates CCW. In response to this, the planetary gears 157 and 158 revolve by CCW rotation. As the planetary gears 157 and 158 revolve, the support arm 156 rotates, so that the locking projection 159 of the support arm 156 can be engaged with the locking claw 164. At this time, if the switchback solenoid 161 is off, the locking claw 164 engages with the locking projection 159 and the rotation of the support arm 156 is restricted as shown in FIG. In this state, both the planetary gears 157 and 158 are not meshed with the transmission gear 167. The posture of the support arm 156 in which both the planetary gears 157 and 158 are separated from the transmission gear 167 is referred to as a detached posture in this specification. When the locking claw 164 is engaged with the locking projection 159, the CCW rotation of the support arm 156 is restricted until the switchback solenoid 161 is turned on, and the support arm 156 is held in the detached posture. .

  As shown in FIG. 13, the transmission gear 167 is disposed at a position adjacent to the planetary gear device 153. The transmission gear 167 can be separated from the planetary gears 157 and 158 of the planetary gear device 153. The transmission gear 167 is a two-stage gear in which a large-diameter gear 167L and a small-diameter gear 167S are coaxially and integrally configured. The planetary gears 157 and 158 can be engaged with and disengaged from the large-diameter gear 167L. The small-diameter gear 167S meshes with a driven gear 168 provided on the shaft of the switchback roller 43. The gear configuration from the transmission gear 167 to the driven gear 168 is not particularly limited, and the number and diameter of the transmission gears can be appropriately changed according to the distance from the transmission gear 167 to the driven gear 168.

  As shown in FIG. 14, when the drive gear 69 rotates CW, the transmission gear 71 rotates CCW and the sun gear 72 rotates CW. In response to this, the planetary gears 157 and 158 revolve by CW rotation. As the planetary gears 157 and 158 revolve, the support arm 156 rotates. When the support arm 156 rotates CW, the locking projection 159 moves away from the locking claw 164. Therefore, even if the switchback solenoid 161 is off, the support arm 159 can perform CW rotation. As the planetary gears 157 and 158 revolve by CW rotation, the planetary gear 157 meshes with the transmission gear 167.

  When the planetary gear 157 revolved by the CW rotation meshes with the transmission gear 167, the revolution of the planetary gear 157 is stopped. Then, the planetary gear 157 rotates by CCW rotation upon receiving the driving force transmitted from the sun gear 72. In response to this, the transmission gear 167 rotates CW and the driven gear 168 rotates CCW. As the driven gear 168 rotates CCW, the switchback roller 43 is rotated in the return direction.

  When the switchback solenoid 161 is turned on from the state shown in FIG. 13, the locking member 160 is rotated and the locking claw 164 is detached from the locking projection 159. Accordingly, the support arm 156 can perform CCW rotation, and the planetary gears 157 and 158 revolve by CCW rotation. As shown in FIG. 15, the planetary gear 158 revolved by CCW rotation meshes with the transmission gear 167, whereby the revolution of the planetary gear 158 is stopped. Then, the planetary gear 158 receives the driving force from the sun gear 72 and rotates by CW rotation. In response to this, the transmission gear 167 rotates CCW, and the driven gear 168 rotates CW. As the driven gear 168 rotates in the CW direction, the switchback roller 43 is rotated in the retracting direction. Note that the switchback solenoid 161 only needs to be turned on when the latching claw 164 is detached from the latching projection 159, and the switchback solenoid 161 is turned off after the support arm 156 rotates CCW from the detached posture. However, the locking claw 164 does not engage with the locking projection 159.

  By switching the rotation of the drive gear 67 from CCW rotation to CW rotation, the support arm 156 can perform CW rotation from the state shown in FIG. 15 where the planetary gear 158 and the transmission gear 167 are engaged. When the support arm 156 rotates CW, the planetary gear 157 and the transmission gear 167 are engaged with each other as shown in FIG. Then, when the rotation of the drive gear 67 is switched from the CW rotation to the CCW rotation, the support arm 156 rotates CCW from the state shown in FIG. 14, and as shown in FIG. The disengagement posture is engaged. The planetary gear device 153 and the transmission gear 167 correspond to the gear train of the second driving force transmission mechanism according to the present invention.

  16 and 17 show the driving force transmission mechanism 170 from the motor 67 to the guide flap 50. FIG. The driving force transmission mechanism 170 changes the posture of the guide flap 50 based on the rotation direction of the motor 67. The driving force transmission mechanism 170 corresponds to the third driving force transmission mechanism according to the present invention.

  As shown in FIG. 16, transmission gears 71, 72, 73 are sequentially meshed with a driving gear 69 provided on the driving shaft of the motor 67, and the driving force is transmitted from the transmission gear 73 to the planetary gear device 174. ing. As described above, the transmission gear 71 includes the driving force transmission mechanism 170 that transmits the driving force to the separation roller 34, the driving force transmission mechanism 120 that transmits the driving force to the transport rollers 35A to D, in addition to the driving force transmission mechanism 170. The driving force transmission mechanism 150 that transmits the driving force to the switchback roller 43 is shared. The transmission gear 72 is shared as the transmission gear of the driving force transmission mechanism 70 that transmits the driving force to the separation roller 34 and as the sun gear 72 in the driving force transmission mechanism 150 that transmits the driving force to the switchback roller 43. The The transmission gear 73 is shared as a transmission gear of the driving force transmission mechanism 70 that transmits the driving force to the separation roller 34. Upon receiving the CW rotation or CCW rotation of the motor 67, the driving force is transmitted so that the transmission gear 73 rotates CCW or CW.

  The planetary gear unit 174 is provided with a support arm 177 that is rotatable coaxially with the shaft 176 of the sun gear 175, and two planetary gears 178 and 179 that respectively mesh with the sun gear 175 are supported by the support arm 177. Become.

  The sun gear 175 is a two-stage gear in which a large-diameter gear 175L and a small-diameter gear 175S are coaxially and integrally configured. The planetary gears 178 and 179 supported by the support arm 177 mesh with the gear 175S of the sun gear 175, respectively. When the sun gear 175 rotates, the planetary gears 178 and 179 respectively engaged with the gear 175S rotate. Further, the support arm 177 rotates in the same direction in response to the rotation of the sun gear 175. That is, when the sun gear 175 rotates, the planetary gears 178 and 179 revolve around the sun gear 175 while rotating respectively.

  The transmission gear 73 meshes with the sun gear 175 of the planetary gear device 174. When the driving force is transmitted from the motor 67 and the transmission gear 73 rotates in a predetermined direction, the sun gear 175 is rotated in a predetermined direction. For example, as shown in FIG. 16, when the drive gear 69 rotates CW, the transmission gear 73 rotates CCW, the sun gear 175 rotates CW, and the planetary gears 178 and 179 revolve with CW rotation.

  As shown in the figure, a transmission gear 180 and a transmission gear 181 are arranged adjacent to the planetary gear device 174. The transmission gear 180 is a two-stage gear in which a large-diameter gear 180L and a small-diameter gear 180S are coaxially and integrally configured. The planetary gears 178 and 179 of the planetary gear device 174 can be engaged with and disengaged from the gear 180L of the transmission gear 180. Further, the gear 180 </ b> S of the transmission gear 180 and the transmission gear 181 are meshed, and the transmission gear 181 is meshed with a driven gear 182 provided on the shaft of the guide flap 50.

  As shown in FIG. 16, planetary gears 178 and 179 revolve by CW rotation, whereby planetary gear 178 meshes with gear 180 </ b> L of transmission gear 180. On the other hand, the planetary gear 179 is detached from the transmission gear 180. When the planetary gear 178 revolved by the CW rotation is engaged with the transmission gear 180, the revolution of the planetary gears 178 and 179 is stopped. Then, the planetary gear 178 rotates by CCW rotation upon receiving the driving force transmitted from the sun gear 175. In response to this, the transmission gear 180 rotates CW. The transmission gear 181 meshing with the transmission gear 180 rotates CCW, and the driven gear 182 meshing with the transmission gear 181 rotates CW. By the CW rotation of the driven gear 182, the guide flap 50 is rotated so as to swing upward, and, as shown in FIG. This is the position to guide the document.

  As shown in FIG. 17, when the drive gear 69 rotates CCW, the transmission gear 73 rotates CW, the sun gear 175 rotates CCW, and the planetary gears 178 and 179 revolve by CCW rotation. As the planetary gears 178 and 179 revolve by CCW rotation, the planetary gear 179 meshes with the gear 180L of the transmission gear 180. On the other hand, the planetary gear 178 is detached from the transmission gear 180. When the planetary gear 179 revolved by CCW rotation meshes with the transmission gear 180, the revolution of the planetary gears 178 and 179 is stopped. Then, the planetary gear 179 receives the driving force transmitted from the sun gear 175 and rotates by CW rotation. In response to this, the transmission gear 180 rotates CCW. The transmission gear 181 meshing with the transmission gear 180 rotates CW, and the driven gear 182 meshing with the transmission gear 181 rotates CCW. When the driven gear 182 rotates CCW, the guide flap 50 is rotated so as to swing downward from the position shown in FIG. 2, and the switchback path 39 from the reading position side of the document conveying path 32 at the connection position 38. It will be a position to guide the manuscript. The transmission gears 72 and 73, the planetary gear device 174, the transmission gears 180 and 181 correspond to the gear train of the third driving force transmission mechanism according to the present invention.

  Although not shown in the figure, a slip clutch is provided between the shaft provided with the driven gear 182 and the guide flap 50. The rotation of the shaft is transmitted to the guide flap 50 by the slip clutch. In the slip clutch, when a load of a predetermined torque or more is applied, the clutch plate slips and the driving force transmission is cut off. The guide flap 50 is swung in a posture for guiding a document to each conveyance path, and is regulated so as not to be rotated beyond each posture by contacting a guide member or the like. Therefore, after the guide flap 50 is in the predetermined guide posture, the slip clutch is slipped by restricting the rotation of the guide flap 50, and the driven gear is in a state where the guide flap 50 is stationary in the predetermined guide posture. The shaft provided with 182 is further rotatable. The gear configuration from the transmission gear 180 to the driven gear 182 is not particularly limited, and the number and diameter of the transmission gears can be appropriately changed according to the distance from the transmission gear 180 to each driven gear 182.

  The driving force is transmitted from the single motor 67 to the separation roller 34, the suction roller 33, the conveying rollers 35A to 35D, the switchback roller 43, and the guide flap 50 by the driving force transmission mechanisms 70, 110, 120, 150, and 170 described above. Is transmitted. In the driving force transmission mechanisms 70, 120, 150, and 170, the driving gear 69 provided on the driving output shaft of the motor 67 and the transmission gear 71 that meshes with the driving gear 69 are shared. The driving force transmission mechanism 120 transmits the driving force to the transport rollers 35A to 35D by a gear train branched from the transmission gear 71. The driving force transmission mechanism 150 transmits the driving force to the switchback roller 43 by a gear train branched from the transmission gear 71. On the other hand, the driving force transmission mechanisms 70 and 170 transmit the driving force to the separation roller 34 and the guide flap 50 by a gear train branched from the transmission gears 72 and 73 downstream in the driving force transmission direction from the transmission gear 71. .

  Only the backlash between the drive gear 69 and the transmission gear 71 exists in the transmission gear 71 meshed with the drive gear 69. On the other hand, on the downstream side in the driving force transmission direction from the transmission gear 71, there is an accumulation of backlash corresponding to the overlapping of the transmission gears 72 and 73. By transmitting the driving force to each of the transport rollers 35A to 35D as a gear train that branches the driving force transmission mechanism 120 from the transmission gear 71, a driving force transmission with less backlash is realized. Similarly, driving force transmission with less backlash is realized by transmitting the driving force to the switchback roller 43 as a gear train in which the driving force transmission mechanism 150 is branched from the transmission gear 71. Further, since the backlash of the transmission gear 71 is small, for example, the load fluctuation generated when the separation roller 34 rotates after feeding the document and contacting the separation pad, and the guide flap 50 has a predetermined guide posture. After that, the load fluctuation caused by the slipping clutch slipping is suppressed from affecting the rotation of the transport rollers 35A to 35D and the switchback roller 43 via the transmission gear 71.

  The driving force transmission mechanisms 70 and 170 are branched from the driving force transmission mechanism 150, and no other driving force transmission mechanism is branched from the driving force transmission mechanism 120. Therefore, it is particularly suppressed that load fluctuations in the separation roller 34 and the guide flap 50 affect the transport rollers 35A to 35D. In addition, the driving force transmission path branched from the transmission gear 71 is concentrated in two directions of the driving force transmission mechanism 120 and the driving force transmission mechanism 150, so that the configuration of the gear train is simplified.

  The guide flap 50 to which the driving force is transmitted from the motor 67 by the driving force transmission mechanism 170 is for switching the conveyance path at the connection position 38 of the document conveyance path 32, and the leading end in the document conveyance direction is the connection position. It is sufficient that the switching to the desired transport path is completed before the arrival. In addition, a slight change in the operation speed of the guide flap 50 does not adversely affect the action of the guide flap 50 guiding the document along a predetermined conveyance path. Therefore, it is considered that the driving force transmission mechanisms 70 and 170 have no adverse effect on the driving force transmission having a larger backlash effect than the driving force transmission mechanisms 120 and 150, or are extremely small.

Hereinafter, an image reading operation by the image reading apparatus 1 will be described.
The image reading apparatus 1 can be used as an FBS or an ADF 3, but the use of the FBS is not particularly related to the present invention, and a detailed description thereof will be omitted. When the ADF 3 is used, the document cover 4 is closed with respect to the document table 2. Opening / closing of the document cover 4 is detected by a sensor or the like provided on the document table 2 and is controlled so that the ADF 3 can be used when the document cover 4 is closed. Then, the document Gn to be read is placed on the paper feed tray 30. The original Gn is placed on the paper feed tray 30 so-called face-up so that the reading surface (first surface) is on the upper side. Further, the document Gn may be one sheet or a plurality of sheets. For example, when reading images of a plurality of documents Gn of the same size, the first document G1 is placed on the sheet feed tray 30 so that the first surface of the first document G1 faces upward, that is, face up. Placed.

  When reading start is input to the image reading apparatus 1, the motor 67 is driven, and the suction roller 33, the separation roller 34, the transport rollers 35A, 35B, 35C, and 35D, the paper discharge roller 36, and the switchback roller 43 are predetermined. It is rotationally driven at the timing. Further, the arm 29 is lowered, and the suction roller 33 comes into pressure contact with the original G1 on the paper feed tray 30. Then, the sheets are separated one by one from the uppermost document G 1 that directly receives the rotational force of the suction roller 33 and the separation roller 34, and sent to the document conveyance path 32. The fed document Gn is guided to the document conveyance path 32 and conveyed to the reading position, and the image reading unit 22 waiting under the reading position reads the image of the document Gn. Then, the document Gn after the image reading is discharged to the paper discharge tray 31. In such an image reading operation, the conveyance path of the original Gn differs depending on whether single-sided reading of the original Gn is performed or double-sided reading. Whether to perform single-sided reading or double-sided reading of the document Gn is determined by a preset single-sided reading mode or double-sided reading mode before a reading start is input.

  FIG. 18 is a flowchart showing the operation of the image reading apparatus 1 in the single-sided reading mode. FIG. 19 is a flowchart showing the operation of the image reading apparatus 1 in the double-sided reading mode. FIG. 20 is a timing chart showing the operation of the image reading apparatus 1 in the single-sided reading mode. FIG. 21 is a timing chart showing the operation of the image reading apparatus 1 in the single-sided reading mode. FIG. 22 to FIG. 26 are schematic views showing the conveyance state of the original Gn in the single-sided reading mode. FIG. 27 to FIG. 32 are schematic views showing the conveyance state of the document Gn in the duplex reading mode. In the figure, the surface indicated by “1” in the document Gn is the first surface read first in the duplex reading, and the surface indicated by “2” is the second surface read later. The surface and the second surface are in a front-back relationship.

  Before the start of single-sided reading, as shown in FIG. 22, the guide flap 50 is in a position where the conveyance path at the connection position 38 is continuous from the reading position side of the document conveyance path 32 to the discharge tray 31 side. The guide flap 46 is in a position where the conveyance path at the crossing position 40 is continued from the paper feed tray 30 side of the document conveyance path 32 to the reading position side when the document Gn is not in contact. The guide flap 47 is in a position where the conveyance path at the crossover position 40 is continued from the terminal end 41 side of the switchback path 39 to the reading position side of the document conveyance path 32 when the document Gn is not in contact.

  When reading start is input to the image reading apparatus 1 (S1 (Y)), it is detected by the first front sensor 52 whether or not the document Gn is placed on the paper feed tray 30 (S2). When the control unit 60 determines that the document Gn is not placed on the paper feed tray 30 (S2 (N)), an error message “No document” is displayed on the liquid crystal display unit 12 of the image reading apparatus 1. Perform (S3). If the document Gn is placed on the paper feed tray 30, the motor 67 is driven by CW rotation. In the present embodiment, it is assumed that the motor 67 rotates CW at the start of reading. However, whether the motor 67 is rotated CW or CCW at the start of reading is arbitrary, and the rotation direction of the motor 67 is relative. Concept.

  The controller 60 drives the motor 67 by CW rotation and turns on the paper feed solenoid 88. As a result, as shown in FIGS. 4 and 5, the planetary gear device 75 of the driving force transmission mechanism 70 is unlocked by the locking mechanism 86, and the planetary gears 79, 80 are based on the rotation of the sun gear 76. Is revolved by CCW rotation to transmit the driving force to the transmission gear 94. As a result, the driven gear 95 rotates CW. As the driven gear 95 rotates CW, the driving force is transmitted to the arm 29 and the arm 29 is lowered. As a result, the suction roller 33 comes into pressure contact with the document G1 on the paper feed tray 30. In addition, the CW rotation of the driven gear 95 is transmitted to the suction roller 33 and the separation roller 34 by the driving force transmission mechanism 110, and the suction roller 33 and the separation roller 34 rotate in the feeding direction, whereby the document G1 is fed to the document conveyance path 32. It is carried to. When a plurality of documents Gn are placed on the sheet feed tray 30, the document G2 directly below the document G2 may be double-fed along with the document G1 at the uppermost position. It is restrained by the separation pad provided at the facing position. In this way, the document G1 is fed (S4).

  In the document conveyance path 32, the driving force from the motor 67 is transmitted to the conveyance rollers 35 </ b> A, 35 </ b> B, 35 </ b> C, 35 </ b> D and the paper discharge roller 36 by the driving force transmission mechanism 120, and each roller is downstream from the upstream side of the document conveyance path 32. The original Gn is conveyed to the side, that is, rotated in the conveyance direction. The document G1 fed from the sheet feed tray 30 to the document transport path 32 is nipped by the transport roller 35A and the pinch roller 37 and is transmitted with a rotational force, so that the document G1 is transported to the intersection position 40 through the document transport path 32. . The second front sensor 53 is turned on when the document G1 is fed to the document transport path 32.

  Since the guide flap 47 closes the conveyance path from the paper feed tray 30 side of the document conveyance path 32 to the intersection position 40, the document G 1 conveyed to the intersection position 40 abuts on the guide flap 47. As shown in FIG. 23, the guide flap 47 rotates to the left in the drawing so as to be pushed by the document G1 conveyed through the document conveyance path 32. As a result, the conveyance path from the paper feed tray 30 side to the reading position side of the document conveyance path 32 continues and the conveyance path to the terminal end 41 side of the switchback path 39 is closed. In addition, the conveyance path to the connection position 38 side of the switchback path 39 is closed by the guide flap 46. Therefore, the document G1 that has reached the crossing position 40 from the paper feed tray 30 side of the document transport path 32 is guided by the guide flap 46 and the guide flap 47, and does not enter any direction of the switchback path 39. The document is conveyed to the reading position side of the document conveyance path 32.

  The peripheral speeds of the transport rollers 35A, 35B, 35C, 35D and the paper discharge roller 36, which are rotated by the driving force transmitted from the motor 67 by the driving force transmitting mechanism 120, are driven by the driving force transmitting mechanisms 70, 110 from the motor 67. Is set so as to be faster than the peripheral speed of the separating roller 34 that rotates. As shown in FIG. 23, the original G1 fed from the paper feed tray 30 to the original conveyance path 32 is nipped and conveyed by the conveyance roller 35A and the pinch roller 37 while being pressed against the separation roller 34. As shown in FIG. 9, the separation roller 34 is allowed to idle for approximately one turn in the feeding direction by the one-turn clutch 112. Therefore, as shown in FIG. 24, the separation roller 34 that is in pressure contact with the original G1 is rotated by the original G1 conveyed at a predetermined speed by the conveying roller 35A and idles so as to advance in the feeding direction from the shaft 111. .

  As shown in FIG. 25, when the first original G1 is completely fed from the paper feed tray 30 to the original conveyance path 32, the original G1 is separated from the separation roller. As a result, the idling of the separation roller 34 that has been rotated by the original G1 is stopped. As shown in FIG. 24, due to the idling of the separation roller 34, the locking piece 118 of the separation roller 34 advances in the feeding direction with respect to the pin 117 of the shaft 111. A driving force is transmitted to the shaft 111 from the motor 67, but the separation roller 34 does not rotate until the pin 117 rotates to a position where it engages with the locking piece 118. Therefore, the second original G2 that is in pressure contact with the separation roller 34 is not fed to the original conveyance path 32 until the separation roller 34 rotates. On the other hand, the document G1 fed to the document transport path 32 is transported through the document transport path 32 by the rotation of the transport rollers 35A and 35B. As a result, as shown in FIG. 25, a predetermined gap is formed in the transport direction between the first document G1 and the second document G2. If the shaft 111 rotates until the pin 117 engages with the locking piece 118, the rotation of the shaft 111 is transmitted to the separation roller 34 by the pin 117 and the locking piece 118, and the separation roller 34 rotates in the feeding direction. To do. Thereby, as shown in FIG. 26, the second original G2 is fed to the original conveyance path 32. In this manner, each document Gn can be fed to the document transport path 32 continuously and at high speed with a predetermined gap without driving the paper feed solenoid 88 for each document Gn. 25, the second front sensor 53 is turned off when the trailing edge of the document G1 passes as shown in FIG. 25, and then turned on when the leading edge of the document G2 passes as shown in FIG. Become.

  As shown in FIG. 26, the original G1 is conveyed so as to be reversed downward by the curved portion 32B of the original conveying path 32, and the rear sensor 54 detects the leading end of the original G1 in the conveying direction and is turned on. Since the front end of the document G1 in the conveyance direction reaches the reading position after a predetermined time has been detected by the rear sensor 54, the control unit 60 operates the image reading unit 22 when the front end of the document G1 in the conveyance direction reaches the reading position. The image of the original G1 is read (S5). The document G1 passes through the reading position with the first surface facing the image reading unit 22, and the image reading unit 22 reads the image on the first surface of the document G1. The rear sensor 54 is turned off when detecting the rear end of the document G1 in the conveyance direction. The control unit 60 ends the image reading of the document G1 by the image reading unit 22 after the rear sensor 54 is turned off and a predetermined time has elapsed.

  Since the motor 67 is CW rotation, as shown in FIG. 27, the guide flap 50 guides the document G1 to the discharge tray 31 side of the document transport path 32 at the connection position 38. The paper discharge roller 36 and the pinch roller 37 nip the original G1 and discharge it from the original conveyance path 32 to the paper discharge tray 31 (S6). If the rear sensor 54 detects the leading edge of the second original G2 in the conveyance direction and is turned on, the control unit 60 operates the image reading unit 22 to read an image of the original G2 after a predetermined time has elapsed. Further, after the idling of the original G2, the separation roller 34 that has been stopped for a predetermined time rotates, whereby the third original G3 is fed to the original conveying path 32. By repeating these operations, the ADF 3 sequentially feeds the originals G1, G2, G3,... On the paper feed tray 30 to the original conveyance path 32, and the image reading unit 22 makes the original originals G1, G2, and so on. The images G3,... Are read, and the read originals G1, G2, G3,.

  As shown in FIG. 20, after the last document Gk placed on the paper feed tray 30 is discharged from the document transport path 32, the control unit 60 switches the rotation of the motor 67 from CW rotation to CCW rotation and feeds it. The paper solenoid 88 is turned on. Whether or not the document Gk placed on the paper feed tray 30 is the last document is determined by the first front sensor 52 when the second front sensor 53 detects the trailing edge of the document Gk and is turned off. Judgment is made by whether or not it is off. If the first front sensor 52 is off, the original Gk is the last original placed on the paper feed tray 30, and if it is on, it is determined that the next original exists on the paper feed tray 30. When the rotation of the motor 67 is switched from CW rotation to CCW rotation and the paper feed solenoid 88 is turned on, the driving force is transmitted from the planetary gear device 75 as shown in FIG. The shaft 111 rotates in the direction opposite to the feeding direction. The rotation of the shaft 111 is transmitted to the arm 29, and the arm 29 is raised so that the paper feed roller 33 is separated from the guide surface of the document conveyance path 32. As a result, the original Gn to be read next can be inserted beyond the lower side of the paper feed roller 33 until it contacts the separation roller 34. Thereafter, the control unit 60 stops the motor 67 and the image reading in the single-sided reading mode is completed.

  Next, double-sided reading will be described. Before the document Gn is fed, as shown in FIG. 22 in the description of the single-sided reading mode, the guide flap 50 continues the conveyance path at the connection position 38 from the reading position side of the document conveyance path 32 to the discharge tray 31 side. It is in the position to do. The guide flap 46 is at a position where the conveyance path at the crossover position 40 is continued from the paper feed tray 30 side to the reading position side of the document conveyance path 32, and the guide flap 47 is at the position of the switchback path 39 at the crossover position 40. It is in a position to continue from the end 41 side to the reading position side of the document conveyance path 32.

  When reading start is input to the image reading apparatus 1 (S11), it is detected by the first front sensor 52 whether or not the document Gn is placed on the paper feed tray 30 (S12). When the control unit 60 determines that the document Gn is not placed on the paper feed tray 30 (S12 (N)), an error message “No document” is displayed on the liquid crystal display unit 12 of the image reading apparatus 1. Perform (S13). If the document Gn is placed on the paper feed tray 30, the motor 67 is driven by CW rotation. A CW rotation command to the motor 67 is stored in the RAM 63 as rotation direction information.

  The controller 60 drives the motor 67 by CW rotation and turns on the paper feed solenoid 88. As a result, as shown in FIGS. 4 and 5, the planetary gear device 75 of the driving force transmission mechanism 70 is unlocked by the locking mechanism 86, and the planetary gears 79, 80 are based on the rotation of the sun gear 76. Is revolved by CCW rotation to transmit the driving force to the transmission gear 94. As a result, the driven gear 95 rotates CW. As the driven gear 95 rotates CW, the driving force is transmitted to the arm 29 and the arm 29 is lowered. As a result, the suction roller 33 comes into pressure contact with the document G1 on the paper feed tray 30. In addition, the CW rotation of the driven gear 95 is transmitted to the suction roller 33 and the separation roller 34 by the driving force transmission mechanism 110, and the suction roller 33 and the separation roller 34 rotate in the feeding direction, whereby the document G1 is fed to the document conveyance path 32. It is carried to. When a plurality of documents Gn are placed on the sheet feed tray 30, the document G2 directly below the document G2 may be double-fed along with the document G1 at the uppermost position. It is restrained by the separation pad provided at the facing position. In this way, the document G1 is fed to the document transport path 32 (S14).

  In the document conveyance path 32, the driving force from the motor 67 is transmitted to the conveyance rollers 35 </ b> A, 35 </ b> B, 35 </ b> C, 35 </ b> D and the paper discharge roller 36 by the driving force transmission mechanism 120, and each roller is downstream from the upstream side of the document conveyance path 32. The original Gn is conveyed to the side, that is, rotated in the conveyance direction. The document G1 fed from the sheet feed tray 30 to the document transport path 32 is nipped by the transport roller 35A and the pinch roller 37 and is transmitted with a rotational force, so that the document G1 is transported to the intersection position 40 through the document transport path 32. . The second front sensor 53 is turned on when the document G1 is fed to the document transport path 32.

  Since the guide flap 47 closes the conveyance path from the paper feed tray 30 side of the document conveyance path 32 to the intersection position 40, the document G 1 conveyed to the intersection position 40 abuts on the guide flap 47. In the description of the single-sided reading mode, as shown in FIG. 23, the guide flap 47 rotates to the left in the drawing so as to be pushed by the original G1 conveyed through the original conveying path 32. As a result, the conveyance path from the paper feed tray 30 side to the reading position side of the document conveyance path 32 continues and the conveyance path to the terminal end 41 side of the switchback path 39 is closed. In addition, the conveyance path to the connection position 38 side of the switchback path 39 is closed by the guide flap 46. Therefore, the document G1 that has reached the crossing position 40 from the paper feed tray 30 side of the document transport path 32 is guided by the guide flap 46 and the guide flap 47, and does not enter any direction of the switchback path 39. The document is conveyed to the reading position side of the document conveyance path 32.

  As described in the single-sided reading mode, the peripheral speeds of the transport rollers 35A, 35B, 35C, and 35D and the paper discharge roller 36 are set to be higher than the peripheral speed of the separation roller 34. The separation roller 34 is idled by the original G1 being nipped between the conveying roller 35A and the pinch roller 37 while being pressed, and thereby the conveying direction to the first original G1 and the second original G2. A predetermined gap is formed. As shown in FIG. 21, the control unit 60 switches the rotation of the motor 67 from the CW rotation to the CCW rotation before the document G2 is fed, that is, before the separation roller 34 that has been idle is rotated again. The controller 60 determines the elapsed time after the second front sensor 53 detects the leading edge of the document G1 and turns it on, or after the trailing edge of the document G1 turns off and the amount of rotation of the motor 67, etc. Thus, the timing for switching the rotation of the motor 67 can be determined.

  When the rotation of the motor 67 is switched from CW rotation to CCW rotation, as shown in FIG. 7, the support arm 78 of the planetary gear device 75 is locked by the locking mechanism 86 and held in the disengagement posture. As a result, transmission of the driving force to the driven gear 95 is cut, and the shaft 111 that supports the separation roller 34 stops.

  As shown in FIGS. 10 to 12, the driving force transmission mechanism 120 is configured so that each of the transport rollers 35 </ b> A, 35 </ b> B, 35 </ b> C, 35 </ b> D and the paper discharge roller regardless of whether the rotation of the motor 67 is CW rotation or CCW rotation. The driving force in the conveying direction is transmitted to 36. Therefore, even after the rotation of the motor 67 is switched, the original G1 is conveyed along the original conveyance path 32 toward the reading position by the conveyance roller 35B or the like.

  In the driving force transmission mechanism 150, when the rotation of the motor 67 is switched from CW rotation to CCW rotation, the driving cutting mechanism 151 holds the planetary gear device 153 in the disengagement posture and cuts the driving force transmission to the driven gear 168. To do. Thereby, the switchback roller 43 stops. The driving force transmission mechanism 170 is switched so that the guide flap 50 is guided to the switchback path 39 at the coupling position 38 by switching the rotation of the motor 67 from CW rotation to CCW rotation. Note that the guide flap 47 returns to the position shown in FIG. 2 when the trailing edge of the document G1 passes through the crossover position 40.

  As shown in FIG. 28, the document G1 is conveyed by the curved portion 32B of the document conveyance path 32 so as to be reversed downward, and the rear sensor 54 detects the leading end of the document G1 in the conveyance direction and is turned on. Since the front end of the document G1 reaches the reading position after a predetermined time has been detected by the rear sensor 54, if the front end of the document G1 in the transport direction reaches the reading position, the control unit 60 operates the image reading unit 22, The image of the original G1 is read (S15). The document G1 passes through the reading position with the first surface facing the image reading unit 22, and the image reading unit 22 reads the image on the first surface of the document G1. The rear sensor 54 is turned off when detecting the rear end of the document G1 in the conveyance direction. The control unit 60 ends the image reading of the first surface of the document G1 by the image reading unit 22 after the rear sensor 54 is turned off and a predetermined time has elapsed. The image data of the first side of the original G1 read by the image reading unit 22 is stored in a predetermined area of the RAM 63.

  As shown in FIG. 29, the leading end of the document G1 read from the first surface is guided by the guide flap 50 and enters the switchback path 39 from the document transport path 32 through the connection position 38. The switchback sensor 55 is turned on by detecting the leading end of the document G1 entering the switchback path 39 in the conveyance direction. In response to the switchback sensor 55 being turned on, the control unit 60 turns on the switchback solenoid 161. As a result, when the document G1 is pulled into the switchback path 39, the support arm 156 of the planetary gear unit 153 is released by the drive cutting mechanism 151, and the motor 67 rotates the CCW as shown in FIG. The planetary gear device 153 that has received the driving force transmission transmits the driving force of CW rotation to the driven gear 168, and the switchback roller 43 rotates in the retracting direction.

  Since the guide flap 46 closes the conveyance path from the switchback path 39 to the crossover position 40, the leading edge of the document G 1 entering the switchback path 39 in the conveyance direction reaches the crossover position 40. Abut. As shown in FIG. 29, the guide flap 46 rotates upward in the drawing so as to be pushed up to the front end in the conveyance direction of the document G1 conveyed through the switchback path 39. As a result, the conveyance path from the connection position 38 side of the switchback path 39 to the terminal end 41 side of the switchback path 39 continues, and the conveyance path to the reading position side of the document conveyance path 32 is closed. The guide flap 47 closes the conveyance path of the document conveyance path 32 toward the paper feed tray 30 side. Therefore, the leading end in the transport direction of the document G1 that has reached the crossing position 40 from the connection position 38 side of the switchback path 39 is guided by the guide flap 46 and the guide flap 47, and does not enter the document transport path 32. It is conveyed to pass 39. The leading end of the document G1 in the transport direction is nipped by the switchback roller 43 and the pinch roller 44, and the switchback path 39 is transported to the end 41 side by the rotation of the switchback roller 43 in the drawing direction.

  As shown in FIG. 30, after the rear end of the document G1 in the transport direction has completely entered the end 41 side beyond the crossover position 40 of the switchback path 39, the control unit 60 changes the rotation of the motor 67 from CCW rotation to CW rotation. Switch to rotation. The switchback sensor 55 detects the trailing edge of the document G1 conveyed through the switchback path 39 and is turned off. After a predetermined time has elapsed, the trailing edge of the document G1 passes through the crossing position 40. Therefore, the control unit 60 determines that the trailing end of the document G1 in the transport direction is the crossover position 40 of the switchback path 39 based on the detection signal of the switchback sensor 55 and the transport distance or transport time of the transport roller 35D and the switchback roller 43. It is determined that the vehicle has completely entered the terminal 41 side beyond When the rotation of the motor 67 is switched, the document G1 that is nipped between the switchback roller 43 and the pinch roller 44 and protrudes from the terminal end 41 is returned to the crossover position 40.

  When a part of the document G1 protrudes from the end 41 of the switchback path 39 to the outside of the ADF 3, a part of the protruded document G1 is supported by the document support part 42. Further, when the document G1 passes through the crossing position 40 and is separated from the guide flap 46, the guide flap 46 rotates downward and returns to the position shown in FIG.

  When the motor 67 is switched from CCW rotation to CW rotation, the planetary gear device 153 of the driving force transmission mechanism 150 rotates the support arm 156 CW to drive the driving force of the motor 67 to the driven gear 168 as shown in FIG. And the driven gear 168 rotates CCW. As a result, the switchback roller 43 rotates in the return direction. In response to this, the document G1 is switchback conveyed so as to return to the crossover position 40 through the switchback path 39 (S16).

  As shown in FIGS. 10 to 12, the driving force transmission mechanism 120 is configured so that each of the transport rollers 35 </ b> A, 35 </ b> B, 35 </ b> C, 35 </ b> D and the paper discharge roller regardless of whether the rotation of the motor 67 is CW rotation or CCW rotation. The driving force in the conveying direction is transmitted to 36. Accordingly, even after the rotation of the motor 67 is switched, the transport rollers 35A, 35B, 35C, and 35D and the paper discharge roller 36 rotate in the transport direction.

  When the rotation of the motor 67 is switched from CW rotation to CCW rotation, the driving force transmission mechanism 70 holds the planetary gear device 75 in the disengagement posture and transmits the driving force to the driven gear 95. Disconnected. After that, since the paper feed solenoid 88 is not operated, the planetary gear device 75 is held in the disengagement posture even when the motor 67 rotates CW. When the rotation of the motor 67 is switched from CCW rotation to CW rotation, the driving force transmission mechanism 170 guides the guide flap 50 from the reading position side of the document conveyance path 32 to the discharge tray 31 side at the connection position 38. It can be switched to the position to

  As shown in FIG. 31, the document G <b> 1 returned from the switchback path 39 comes into contact with the guide flap 46 at the crossover position 40. The guide flap 46 is restricted so as not to rotate downward from the position shown in the drawing. Therefore, the conveyance path from the terminal end 41 side of the switchback path 39 to the reading position side of the document conveyance path 32 continues, and the conveyance path to the connection position 38 side of the switchback path 39 is closed. Further, the guide flap 47 closes the conveyance path to the paper feed tray 30 side of the document conveyance path 32. Therefore, the document G1 is guided by the guide flap 46 and the guide flap 47, and does not enter the connection position 38 side of the switchback path 39 or the paper feed tray 30 side of the document transport path 32, and the end of the switchback path 39. It is conveyed from the 41 side to the reading position side of the document conveying path 32. When the original G1 is returned from the switchback path 39 to the upstream side of the reading position of the original conveyance path 32, the front and rear ends of the original G1 are reversed from the state where the original G1 was first conveyed in the original conveyance path 32. Thus, the document conveyance path 32 is retransmitted. In this way, the original G1 is switched back and conveyed. Then, the document G1 is transported through the document transport path 32 with the second surface facing the reading position.

  The control unit 60 switches the rotation of the motor 67 from the CW rotation to the CCW rotation when the leading end in the conveyance direction of the document G1 that has been switched back reaches the predetermined position upstream of the reading position of the document conveyance path 32. The driving force transmission mechanism 120 transmits the driving force in the conveyance direction to each of the conveyance rollers 35A, 35B, 35C, and 35D and the paper discharge roller 36 regardless of the rotation direction of the motor 67. Therefore, the rotation of the motor 67 is switched. Thereafter, the original G1 is conveyed toward the reading position on the original conveyance path 32 by the conveyance roller 35B and the like.

  When the rotation of the motor 67 is switched from CW rotation to CCW rotation, the driving force transmission mechanism 150 is rotated by the support arm 156 of the planetary gear device 153 in the CCW direction and is locked by the drive cutting mechanism 151 to be in a detached posture. Thereby, the driving force transmission from the planetary gear device 153 to the driven gear 168 is cut off, and the switchback roller 43 stops. Accordingly, the rotation of the motor 67 is switched while the leading end side of the document G1 in the transport direction is nipped by the transport roller 35B and the pinch roller 37 and the rear end side of the document G1 in the transport direction is nipped by the switchback roller 43 and the pinch roller 44. However, the switchback roller 43 does not rotate in the retracting direction. The switchback roller 43 from which the driving force transmission from the motor 67 is cut off is rotated in the return direction by the original G1 conveyed by the rotation of the conveying roller 35B.

  Since the feed solenoid 88 is not operated after the locking mechanism 86 holds the planetary gear device 75 in the disengagement posture, the planetary gear device 75 is connected to the driving force transmission mechanism 70 even if the motor 67 rotates CCW. It is held in the separation posture. When the rotation of the motor 67 is switched from CW rotation to CCW rotation, the driving force transmission mechanism 170 is switched to a position for guiding the document from the document conveyance path 32 to the switchback path 39 at the connection position 38. .

  When the front end of the document G1 in the transport direction is detected by the rear sensor 54 and the front end of the transport direction reaches the reading position, as shown in FIG. 32, the control unit 60 sends the image reading unit 22 to the second surface of the document G1. The image is read (S17). The leading end of the document G1 in the transport direction after the second surface is read is guided by the guide flap 50, and enters the connection position 38 from the document transport path 32 to the switchback path 39. When the rear end of the conveyance direction of the document G1 is detected by the rear sensor 54 and the rear end reaches the reading position, the control unit 60 ends the image reading of the second surface of the document G1 by the image reading unit 22. The image data of the second surface of the original G1 read by the image reading unit 22 is stored in a predetermined area of the RAM 63.

  When the switchback sensor 55 detects the leading edge of the document G1 that has entered the switchback path 39 and is turned on, the control unit 60 turns on the switchback solenoid 161. As a result, when the document G1 is pulled into the switchback path 39, the support arm 156 of the planetary gear unit 153 is released by the drive cutting mechanism 151, and the motor 67 rotates the CCW as shown in FIG. The planetary gear device 153 that has received the driving force transmission transmits the driving force of CW rotation to the driven gear 168, and the switchback roller 43 rotates in the retracting direction.

  As shown in FIG. 29, the leading end of the document G1 in the transport direction that has reached the crossover position 40 pushes the guide flap 46 upward in the drawing, and enters the crossover position 40 toward the end 41 of the switchback path 39. Then, similarly to FIG. 30, after the trailing end of the document G1 in the transport direction has completely entered the end 41 side beyond the crossing position 40 of the switchback path 39, the controller 60 rotates the rotation of the motor 67 by CCW. Is switched to CW rotation, the switchback roller 43 is rotated in the returning direction, and the original G1 is returned to the crossover position 40. In the same manner as in FIG. 31, the document G1 returned from the switchback path 39 is guided by the guide flap 46 and the guide flap 47, and from the end 41 side of the switchback path 39 to the reading position side of the document transport path 32. It is conveyed to. As a result, the document G1 is retransmitted on the document conveyance path 32 in a state where the leading end and the rear end are reversed again, that is, in a state where the document G1 is first fed to the document conveyance path 32 (S18).

  The driving force transmission mechanism 120 transmits the driving force in the conveyance direction to each of the conveyance rollers 35A, 35B, 35C, and 35D and the paper discharge roller 36 regardless of the rotation direction of the motor 67, so that each of the conveyance rollers 35A, 35B, 35C and 35D and the paper discharge roller 36 rotate in the transport direction. The driving force transmission mechanism 70 is in a state where the locking mechanism 86 holds the planetary gear device 75 in the disengagement posture, and cuts off the driving force transmission to the driven gear 95. When the rotation of the motor 67 is switched from CCW rotation to CW rotation, the driving force transmission mechanism 170 guides the guide flap 50 from the reading position side of the document conveyance path 32 to the discharge tray 31 side at the connection position 38. It can be switched to the position to

  Thereafter, the document G1 passes the reading position with the first surface facing the document G1, is guided to the connection position 38 by the guide flap 50 toward the discharge tray 31, and the first surface is lowered by the discharge roller 36. Is discharged to the paper discharge tray 31 (S19). If the next document G2 is set on the paper feed tray 30 (S20 (Y)), that is, if the first front sensor 52 is on, the control unit 60 turns on the paper feed solenoid 88 to engage The stop of the support arm 78 of the planetary gear device 75 by the stop mechanism 86 is released, and the driving force is transmitted from the motor 67 to the driven gear 95 by the driving force transmission mechanism 70 to rotate the separation roller 34 in the feeding direction. . As a result, the original G2 on the paper feed tray 30 is fed to the original conveyance path 32, and image reading on both sides of the original G2 is performed in the same manner as described above.

  Then, similarly to the single-sided reading mode, after discharging the last document Gk placed on the paper feed tray 30 from the document transport path 32 to the paper discharge tray 31, the control unit 60 changes the rotation of the motor 67 from the CW rotation. While switching to CCW rotation, the paper feed solenoid 88 is turned on. As a result, as shown in FIG. 8, the driving force is transmitted from the planetary gear device 75, the driven gear 95 rotates CCW, and the shaft 111 rotates in the direction opposite to the feeding direction. The rotation of the shaft 111 is transmitted to the arm 29, and the arm 29 is raised so that the paper feed roller 33 is separated from the guide surface of the document conveyance path 32. As a result, the original Gn to be read next is returned to an initial state where it can be inserted beyond the lower side of the paper feed roller 33 until it contacts the separation roller 34. Thereafter, the control unit 60 stops the motor 67, and the image reading in the duplex reading mode is completed.

  In the present embodiment, it is assumed that a plurality of documents Gn placed on the paper feed tray 30 are discharged to the paper discharge tray 31 while maintaining the order, and the duplex reading operation by the image reading apparatus 1 is performed. However, if it is not necessary to match the order of the originals Gn placed on the paper feed tray 30 and the order of the originals Gn discharged to the paper discharge tray 31, the first position of the original Gn at the reading position is described. After the original Gn is conveyed with the two surfaces facing each other, the connection position 38 is conveyed to the discharge tray 31 side without causing the original Gn to enter the switchback path 39 again, and the original Gn is transferred to the discharge tray 31. It is good also as discharging. As a result, the order of the originals Gn is not maintained on the paper discharge tray 31, but the last switchback conveyance can be omitted, so that the time required for reading both sides of the original Gn can be shortened.

  As described above, according to the image reading apparatus 1, the driving force transmission mechanisms 70, 120, which share the driving gear 69 provided on the driving output shaft of the single motor 67 and the transmission gear 71 meshed with the driving gear 69. In 150 and 170, the driving force transmission mechanisms 120 and 150 transmit the driving force to the respective transport rollers 35 </ b> A to 35 </ b> D or the switchback roller 43 by the gear train branched from the transmission gear 71, and the driving force transmission mechanisms 70 and 170. However, since the driving force is transmitted to the separation roller 34 and the guide flap 50 by the gear train branched from the transmission gears 72 and 73 downstream in the driving force transmission direction from the transmission gear 71, the driving force transmission mechanism 120, At 150, driving force transmission with less backlash is realized. Further, by branching the driving force transmission mechanisms 70 and 170 from the driving force transmission mechanism 150, it is possible to suppress the load fluctuation generated in the separation roller 34 or the guide flap 50 from affecting the rotation speed of the transport rollers 35A to 35D. The Thereby, the conveyance accuracy of the document by the conveyance rollers 35A to 35D and the pinch roller 37 is improved.

  In the present embodiment, in each of the driving force transmission mechanisms 70, 120, 150, 170, the transmission gears 71, 72, 73 are branched from the transmission gears 71, 72, 73, respectively. The path for transmitting the driving force to the switchback roller 43 is a gear train composed of a plurality of gears. However, these are not limited to the gear train, and may be a single gear.

  Further, in the present image reading apparatus 1, a switchback path 39 for retransmitting the original Gn to the original conveyance path 32 is extended from the connection position 38 on the downstream side of the reading position of the original conveyance path 32, and upstream of the reading position. However, the transport path of the switchback path 39 is an example, and the present invention is limited to the transport path of the document transport path 32 and the switchback path 39 described in the embodiment. Of course, it is not. Therefore, the guide flap 46 and the guide flap 47 can be appropriately changed according to the transport path of the switchback path, and instead of the guide flaps 46 and 47, for example, an elastically deformable film may be adopted as the guide member. .

FIG. 1 is a perspective view showing an external configuration of an image reading apparatus 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing the internal configuration of the image reading apparatus 1. FIG. 3 is a block diagram illustrating a configuration of the control unit 60. FIG. 4 is a diagram illustrating a configuration of the driving force transmission mechanism 70. FIG. 5 is a diagram illustrating a configuration of the driving force transmission mechanism 70. FIG. 6 is a diagram illustrating the configuration of the planetary gear device 75 and the locking mechanism 86. FIG. 7 is a diagram illustrating a configuration of the driving force transmission mechanism 70. FIG. 8 is a diagram illustrating a configuration of the driving force transmission mechanism 70. FIG. 9 is a diagram illustrating a configuration of the driving force transmission mechanism 110. FIG. 10 is a diagram illustrating a configuration of the driving force transmission mechanism 120. FIG. 11 is a diagram illustrating a configuration of the driving force transmission mechanism 120. FIG. 12 is a diagram illustrating a configuration of the driving force transmission mechanism 120. FIG. 13 is a diagram illustrating a configuration of the driving force transmission mechanism 150. FIG. 14 is a diagram illustrating a configuration of the driving force transmission mechanism 150. FIG. 15 is a diagram illustrating a configuration of the driving force transmission mechanism 150. FIG. 16 is a diagram illustrating a configuration of the driving force transmission mechanism 170. FIG. 17 is a diagram illustrating a configuration of the driving force transmission mechanism 170. FIG. 18 is a flowchart showing the operation in the single-sided reading mode. FIG. 19 is a flowchart showing the operation in the duplex reading mode. FIG. 20 is a timing chart of the single-sided reading mode. FIG. 21 is a timing chart of the duplex reading mode. FIG. 22 is a schematic diagram showing an image reading operation in the single-sided reading mode. FIG. 23 is a schematic diagram illustrating an image reading operation in the single-sided reading mode. FIG. 24 is a diagram illustrating a state where the separation roller 34 is idling. FIG. 25 is a schematic diagram illustrating an image reading operation in the single-sided reading mode. FIG. 26 is a schematic diagram illustrating an image reading operation in the single-sided reading mode. FIG. 27 is a schematic diagram illustrating an image reading operation in the single-sided reading mode. FIG. 28 is a schematic diagram showing an image reading operation in the duplex reading mode. FIG. 29 is a schematic diagram showing an image reading operation in the duplex reading mode. FIG. 30 is a schematic diagram showing an image reading operation in the duplex reading mode. FIG. 31 is a schematic diagram showing an image reading operation in the duplex reading mode. FIG. 32 is a schematic diagram showing an image reading operation in the duplex reading mode. FIG. 33 is a schematic diagram showing document conveyance for double-sided reading by a conventional document conveyance device. FIG. 34 is a schematic diagram showing document conveyance for double-sided reading by a conventional document conveyance device.

Explanation of symbols

3 ... ADF (document feeder)
30 ... Paper feed tray (document placement section)
31 ... Paper discharge tray (document discharge part)
32 ... Document transport path 34 ... Separation roller (feeding means, drive part)
35A, 35B, 35C, 35D ... Conveying roller (original conveying means)
37... Switchback roller (document conveying means)
39: Switchback path (switchback transport path)
43 ... Switchback roller (switchback conveying means)
44 ... Pinch roller (switchback conveying means)
50 ... Guide flap (guide means, drive part)
67 ... Motor (drive source)
69... Driving gear 70... Driving force transmission mechanism (third driving force transmission mechanism)
71-73 ... Transmission gear 120 ... Driving force transmission mechanism (first driving force transmission mechanism)
150: Driving force transmission mechanism (second driving force transmission mechanism)
170: Driving force transmission mechanism (third driving force transmission mechanism)

Claims (4)

A document conveying path that connects the document placing portion and the document discharge portion via the reading position;
A document conveying means provided in the document conveying path for conveying the document from the document placing portion to the document discharge portion;
A switchback conveyance path connected to a predetermined position of the document conveyance path;
A switchback conveying means provided in the switchback conveying path, which reverses the leading edge and the trailing edge of the document from the downstream side of the reading position and returns them to the upstream side of the reading position;
A single driving source for applying a driving force to the document conveying means, the switchback conveying means, and other driving parts;
A first driving force transmission mechanism for transmitting driving force from the driving source to the document conveying means;
A second driving force transmission mechanism for transmitting a driving force from the driving source to the switchback conveying means;
A third driving force transmission mechanism that transmits driving force from the driving source to each of the other driving parts,
The first driving force transmission mechanism, the second driving force transmission mechanism, and the third driving force transmission mechanism include a driving gear provided on a driving output shaft from the driving source and a transmission gear that meshes with the driving gear. Share,
The first driving force transmission mechanism and the second driving force transmission mechanism have a gear or a gear train that branches from the transmission gear and transmits the driving force to the document conveying means,
The third driving force transmission mechanism includes a gear or a gear train that branches from a predetermined transmission gear downstream in the driving force transmission direction from the transmission gear and transmits a driving force to each driving portion.   The driving portion to which the driving force is transmitted by the third driving force transmission mechanism is provided in the document placing portion and feeds the document to the document transport path, and is transported at a predetermined position on the document transport path. The document conveying apparatus according to claim 1, further comprising a guide unit that switches a route.   The document conveying apparatus according to claim 1, wherein the third driving force transmission mechanism is branched from the second driving force transmission mechanism. The document conveying means is a pair of conveyance rollers that are respectively provided at different positions on the document conveyance path and convey the document by nipping and rotating the document.
4. The gear train of the first driving force transmission mechanism transmits a driving force in order from a conveying roller pair on the downstream side in the conveying direction to a conveying roller pair on the upstream side in the conveying direction. 5. Document transport device.

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