JP6444169B2 - Feeding device - Google Patents

Description

  The present invention relates to a feeding device that feeds sheets one by one.

  Patent Document 1 discloses a mechanism for automatically stopping rotation of a conveyance roller that conveys a sheet when a cover is opened during feeding in an automatic document feeder (hereinafter referred to as ADF). Specifically, when the user opens the cover of the device to remove a paper jam, the lever held by the cover interrupts the coupling of the drive gear group against the spring bias and is driven from the drive motor. A mechanism for releasing the connection of the driving force to the roller is disclosed.

JP-A-10-236688

  However, in Patent Document 1, the force for interrupting the lever into the coupling portion is generated by releasing the reaction force of the lever spring attached to the lever when the cover is opened. For this reason, a slight time lag may occur between the cover opening operation by the user and the cutting of the driving force with respect to the driving roller.

  The present invention has been made to solve the above problems. Therefore, an object of the present invention is to provide a feeding device capable of immediately interrupting the rotational force of the drive motor and stopping the transport operation without a time lag when the cover of the transport unit is opened by the user. That is.

  Therefore, the present invention opens a drive source, a conveyance unit that conveys a sheet, a transmission unit that transmits a driving force of the drive source to the conveyance unit via a plurality of gears, and opens the conveyance unit. A cover that can be coupled and separated in the axial direction of rotation, and a biasing gear that biases the coupling in a direction that separates the coupling with rotation. And a restricting means that abuts the coupling portion and restricts the coupling portion in a connecting direction, and the coupling portion is coupled by the restricting means when the cover is closed. When the driving force of the driving source is transmitted to the transport unit and the cover is opened, the coupling unit is released from the regulation by the regulating means and separated by the biasing force by the biasing gear configuration, The driving force of the driving source is characterized in that it does not transmitted to the transport unit.

  According to the present invention, when the cover of the transport unit is opened by the user, the rotational force of the drive motor can be immediately interrupted, and the transport operation can be stopped without a time lag.

External perspective view of an image forming apparatus provided with an image reading device as a component Sectional drawing for demonstrating the internal structure of an image reader A perspective view for explaining an internal configuration of the image reading apparatus The figure which shows the state which open | released the original document pressure plate part and the original reading conveyance part The figure for demonstrating the structure of a conveyance drive system Block diagram for explaining a control configuration of an image forming apparatus The figure which shows the connection structure of the gear train from a drive motor The figure for demonstrating the drive transmission state of the forward direction in the rotation position of a document conveyance part. The figure for demonstrating the drive transmission state of the reverse direction in the rotation position of a document conveyance part. The figure for demonstrating the state in case a user performs the paper jam removal operation | work The figure for demonstrating the function when the obstruction | occlusion of an original conveyance part is inadequate

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the following example, a description will be given of an example of a feeding device that conveys documents one by one in order to read an image by an image reading unit. However, the feeding device of the present invention can be used not only as an image reading device but also as a feeding device for another application such as a printer or a facsimile. Further, such an apparatus can also be used as a part of a component of a multifunction machine that combines various functions such as a scanner, a printer, a facsimile machine, and a copying machine.

(First embodiment)
FIG. 1 is an external perspective view of an image forming apparatus provided with an image reading apparatus that can be used in the present invention as a component. The image forming apparatus 100 is configured such that the function as the image reading apparatus 200 is overlaid on the upper layer, and the function as the printer unit 300 is overlaid on the lower layer in the gravity direction (Z direction). For example, an image read by the image reading apparatus 200 may be printed by the printer unit 300, so that it can function as a copying machine. At this time, the operation unit 800 is used by the user to input various commands for reading processing and printing processing and to confirm information of the image forming apparatus 100.

  The image reading apparatus 200 feeds a plurality of sheet-like originals one by one and reads an image, and a flat scan read (reading process for a book with a predetermined page opened). FSR) two reading methods can be used. When reading a document by the ASF method, the user opens the folded document stacking tray 14 and loads a sheet-shaped document thereon. When the reading process is started, the document reading / conveying unit 1 feeds the stacked sheets one by one from the top, conveys them, performs the reading process, and discharges them to the document discharge tray 18. On the other hand, when reading a document by the FSR method, the user rotates the entire document loading platen 40 upward using a handle H provided on the front surface in the X direction, opens a page to be read, and sets it on the glass surface 22. .

  2A, 2 </ b> B, and 3 are a cross-sectional view and a perspective view for explaining the internal configuration of the image reading apparatus 200. When the ASF scanning process is started and the document presence / absence sensor 16 confirms that a sheet is set on the document stacking tray 14, the document stopper 15 is released as the pickup roller 3 rotates, and the document lifter is released. 6 goes up. As a result, the surface of the sheet stacked on the document stacking tray 14 comes into contact with the pickup roller 3, and is carried into the document reading / conveying unit 1 along with the rotation thereof. At this time, the uppermost sheet in contact with the pickup roller 3 is carried into the document reading and conveying unit 1 as it is with the rotation of the separation roller 5, but progress of the sheets other than the uppermost sheet is prevented by the separation pad 4. Further, the separation roller 5 rotates at a lower peripheral speed than a first conveyance roller 7 and a second conveyance roller 9 which will be described later, and a predetermined roller is provided between the first sheet and the second sheet. An interval is secured.

  The sheet carried into the document reading / conveying unit 1 is conveyed in a U-shape along the document conveying path 12 while being sandwiched between the first conveying roller 7 and its pinch roller and the second conveying roller 9 and its pinch roller. The A contact image sensor (CIS) 30 for reading an image is disposed between the first conveyance roller 7 and the second conveyance roller 9 and at the lowest position in the conveyance path. The CIS 30 has a light emitting portion and a light receiving portion, and has a mechanism for detecting reflected light on the sheet surface of light emitted from the LED on a sensor element by a self-focusing rod lens array and detecting it as image information. The sheet being conveyed is read by the CIS 30 at a timing when it passes between the reading white plate 8 and the ADF glass 23. When the sheet reading process is not performed, the reading white plate 8 is used as a white reference for the CIS 30. On the other hand, when the reading process is being performed, the reading white plate 8 presses the sheet against the ADF glass 23 from the back to smooth the surface facing the CIS 30.

  The sheet after the reading process is performed is guided obliquely upward along the guide 702 and then discharged to the document discharge tray 18. The sheet discharge guide 19 guides the sheet being discharged to the document discharge tray 18 and also has a role of suppressing the floating of the already discharged sheet.

  The document edge sensor 17 detects the leading edge and the trailing edge of the sheet being conveyed, and the detection result is used for conveyance and reading processing. For example, the reading process by the CIS 30 is started when the document edge sensor 17 detects the leading edge of the document and then the document is conveyed by a predetermined amount, and the reading process by the CIS 30 is performed by the timing when the document edge is detected and the trailing edge is detected. finish. If the conveying operation is continued until the document presence / absence sensor 16 detects that there is no sheet on the document stacking tray 14, reading processing for a plurality of sheets can be performed in order and without delay.

  FIG. 4 is a diagram illustrating a state where the document stacking pressure plate unit 40 and the document reading / conveying unit 1 are opened in the image forming apparatus 100 according to the present embodiment. The original loading platen 40 can be rotated together with the exterior cover as shown in the figure when reading the original by the FSR method. On the other hand, when a trouble such as a paper jam occurs in the document reading / conveying unit 1, the document reading / conveying unit 1 is opened together with the exterior cover as illustrated.

  When reading a document by the FSR method, the user uses the handle H provided on the front surface in the X direction to rotate the document stacking pressure plate 40 upward about the hinge P to open the page to be read on the glass surface 22. Set it facing. At both ends in the X direction of the original loading platen 40, convex portions 40a and 40b for positioning on the apparatus main body are provided at positions facing the concave sections 2a and 2b of the apparatus main body. Further, a pressure contact plate 41 for smoothing the document surface placed on the glass surface 22 is provided at a portion facing the glass surface 22 of the document stacking pressure plate portion 40.

  Refer to FIG. 2 again. Document reading by the FSR method is performed by the book document reading unit 2 disposed below the document discharge tray 18. After the user sets the page to be read while being pressed against the glass surface 22, when the original loading platen 40 is returned and the reading process is started, the CIS 30 moves at a predetermined speed in the -Y direction. While moving, the original is read through the glass surface 22. When such a reading process is completed, the CIS 30 returns to a fixed position as shown in FIGS.

  5A and 5B are diagrams for explaining the configuration of the transport drive system. The conveyance motor M of the present embodiment is a brush type DC drive motor and is accompanied by a rotary encoder M3. Specifically, a circular code wheel film M1 printed with a slit pattern is attached to the rotation shaft of the drive motor M, and an encoder sensor M2 is provided in a part of the rotation path. The encoder sensor M2 detects the slit of the code wheel film M1, so that the rotational speed of the drive motor M can be recognized. Furthermore, pulse width modulation control (PWM) is performed based on the output signal from the rotary encoder M3, and drive control for the drive motor M can be executed.

  The driving force of the conveyance motor M is transmitted to the separation roller 5, the pickup roller 3, the first conveyance roller 7, and the second conveyance roller 9 via the gear train M4. Thus, in this embodiment, all the gear trains related to sheet conveyance are arranged on the rear side (the −X direction side surface) of the apparatus.

  FIG. 6 is a block diagram for explaining a control configuration of the image forming apparatus 100 used in the present embodiment. The main control board 301 includes a microprocessor unit (MPU) 306, a read image processing unit 307, a print image processing unit 308, an image encoding unit 309, etc., and main control for controlling the entire apparatus via the system bus 303. An IC 302 is provided. The read image processing unit 307 performs predetermined image processing on the image data read by the image reading apparatus 200. The print image processing unit 308 performs predetermined processing on the image data to be printed, and generates image data that can be printed by the print unit 300. The image encoding unit 309 performs mutual conversion between encoded data and image data.

  The power supply unit 340 supplies power necessary for each mechanism such as the image reading apparatus 200, the printing unit 300, and the operation panel 800 in addition to the main control board 301.

  The main control IC 302 uses the power supplied from the power supply unit 340 and performs various processes according to the program code, initial value data, and table data stored in the EEPROM 304 while using the RAM 305 as a work area. In addition to the operation unit 800 described above, the image reading device 200 and the printer unit 300 are also controlled by the main control board 301.

  The operation unit 800 includes a display unit 321 that provides various types of information to the user via the operation panel interface 323, and a command input unit 322 that receives commands from the user. On the other hand, various information and messages can be provided to the user from the speaker 326 via the audio output unit 325.

  The image reading apparatus 200 includes a read image correction unit 312 that performs correction processing such as shading on an image read by the CIS 30 in addition to the CIS 30 and the document driving / conveying unit 1 described above. The print unit 300 includes a print signal output unit 317 that supplies image data generated by the print image processing unit 308 to the print head 316 and a print head 316 that prints an image according to the image data. In addition, a printing system driving unit 318 for conveying a sheet serving as a print medium and moving the print head 316 is also provided.

  The communication connection unit 327 is connected to the communication network 328 and the telephone 329, and inputs and outputs voice and encoded data. For example, an external interface unit 331 such as a USB standard is connected to an external device 332 such as a personal computer. A non-volatile memory 333 including a flash memory is a spare storage area for preventing work data and image data from being erased during a power failure or the like. The wireless LAN module 334 performs image input / output via an access point outside the apparatus.

  Hereinafter, various processes that can be executed by the image forming apparatus 100 according to the present embodiment as a multifunction peripheral will be described in detail. The following processes are all executed by the main control IC 302 in accordance with a program stored in the EEPROM 304.

(PC scan processing)
This is processing for providing image data obtained by reading a document to a PC connected as an external device 332. Image data read by the CIS 30 is subjected to a predetermined correction process such as shading correction by the read image correction unit 312. Thereafter, the read image processing unit 307 performs predetermined image processing and develops it in the RAM 305. Further, the image data is compressed and encoded in the JPEG format by the image encoding unit 309, and the encoded image data is output to a PC (external device) 332 via the external interface 331.

(Copy process)
This is processing for outputting an image read by the image reading apparatus 200 from the printer unit 300. Image data read by the CIS 30 is subjected to a predetermined correction process such as shading correction by the read image correction unit 312. Thereafter, the read image processing unit 307 performs predetermined image processing and develops it in the RAM 305. Next, the image encoding unit 309 compresses and encodes the data into, for example, the JPEG format, and is stored in the RAM 305 again. The accumulated image data is sequentially sent to the print image processing unit 308 and converted into printable image data by the print unit 300. Further, the print head 316 performs a printing operation via the print signal output unit 317 to obtain an output product.

(Facsimile transmission processing)
This is processing for outputting an image read by the image reading apparatus 200 from the telephone 329. Image data read by the CIS 30 is subjected to a predetermined correction process such as shading correction by the read image correction unit 312. Thereafter, the read image processing unit 307 performs predetermined image processing and develops it in the RAM 305. Next, the image encoding unit 309 compresses and encodes the data into, for example, the MR (Modified Read) format and stores the data in the RAM 305 again. The communication connection unit 327 transmits / receives a facsimile communication procedure signal and starts transmitting the stored image data. Even after the start of transmission, the reading process in the image reading apparatus 200 continues, and transmission is continued while sequentially accumulating image data.

(Facsimile reception processing)
In this process, an image received by the communication network 328 is printed by the printing unit 300. When an incoming call on the communication network 328 is detected, the communication connection unit 327 transmits and receives a facsimile communication procedure signal, and then starts receiving image data. The received image data is demodulated by the image encoding unit 309 and developed in the RAM 305. The developed image data is sequentially sent to the print image processing unit 308 and converted into printable image data by the print unit 300. Further, the print head 316 performs a printing operation via the print signal output unit 317 to obtain an output product.

(Print processing)
In this process, image data received from the external device 332 is printed by the printing unit 300. Commands and reception parameters transmitted from the external device 332 and received by the external interface unit 331 are interpreted by the MPU 306 and developed as image data by the image encoding unit 309 in the RAM 305. The developed image data is sequentially sent to the print image processing unit 308 and converted into printable image data by the print unit 300. Further, the print head 316 performs a printing operation via the print signal output unit 317 to obtain an output product.

  Hereinafter, the cutting structure of the driving force of the conveyance roller, which is a characteristic structure of the present invention, will be described. FIG. 7 is a diagram illustrating a connection configuration of a gear train M4 that is a transmission unit of a driving force from a driving motor M that is a driving source. The drive motor M is rotated by a worm gear M41 fixed to the shaft of the drive motor M, a drive gear M42 meshing with the worm gear M41, and a coupling gear M43 rotating coaxially with the drive gear M42. It is transmitted to the gear M44. The plurality of gears can be rotated in the forward direction and the reverse direction, respectively, in accordance with the forward / backward rotation switching of the drive motor M. The drive gear M42 and the coupling gear M43 are provided with coupling portions M421 and M431 having tooth shapes that mesh with each other so that they can be coupled and separated in the X direction. That is, when the coupling parts M421 and M431 are coupled, the driving force is transmitted to the coupling gear M43 and the feed gear M44 rotates, but when both are separated in the X direction, the feed gear M44 does not rotate. Yes.

  The drive motor M and the gear train M4 are supported by a fixed plate M45. On the other hand, the coupling restricting portion M46 fixed in the apparatus restricts the position of the coupling gear in the X direction to a position where it is coupled to the drive gear M42 by bringing the restricting surface M461 into contact with the coupling gear M43. doing. When performing reading processing by the ASF method, the drive motor M rotates in the clockwise direction when viewed in the Y direction, and the drive gear M42 rotates in the clockwise direction when viewed in the -X direction via the worm gear M41. . For this reason, the feed gear M44 connected to the drive gear M42 via the coupling gear M43 rotates in the counterclockwise direction when viewed in the −X direction, that is, in the transport direction.

  However, when the user rotates the document conveying section 1 as shown in FIG. 4 to remove a paper jam or the like, the drive motor M and the gear train M4 rotate together with the fixed plate M45, but the coupling restriction section M46 It remains on the main unit. That is, when the document conveying unit 1 is rotated, there is no restriction on the coupling gear M43 toward the drive gear M42.

  FIGS. 8A to 8C are diagrams for explaining the drive transmission state at the rotation position of the document conveying unit 1. 8A shows a state in which the document conveying unit 1 is closed, FIG. 8B shows a state in which the document conveying unit 1 is slightly rotated, and FIG. 8C shows a state in which the document conveying unit 1 is almost completely opened. Each of these shows a state where a paper jam can be removed.

  In the present embodiment, the coupling part M421 and the coupling part M431 are configured to engage with each other on a substantially vertical surface in forward rotation, and between the coupling part M421 and the coupling part M431 by rotational driving. No axial force (X direction) is generated. On the other hand, the coupling gear M43 and the feed gear M44 are helical gears and have a twist angle of 20 °. Therefore, when the drive motor M rotates in the transport direction (forward direction), the coupling gear M43 has an axial force FF1 (that is, from the drive gear M42 in the X direction as shown in FIG. 8A). Force in the direction of separation). However, the position of the coupling gear M43 is regulated by the coupling regulation part M46 as described above. Therefore, the coupling gear M43 can maintain the rotation at the position shown in FIG. 8A, transmit the rotational force to the feed gear M44, and maintain the conveying operation.

  When the document conveying unit 1 is slightly opened, as shown in FIG. 8B, the coupling gear M43 is disengaged from the regulating surface M461 of the coupling regulating unit M46, and in the + X direction by the action of the axial force FF1. Moving. However, the coupling regulation part M46 has a shape in which a guide slope M462 is formed at an upper position continuous with the regulation surface M461. Therefore, the coupling gear M43 gradually moves in the + X direction along the contact surface M432 while abutting the contact surface M432 on the guide slope M462. At this time, a force FU in the + Z direction is generated from the vertical drag of the guide slope M462, and assists the user in trying to lift the document transport unit 1. That is, it is possible to further reduce the burden of the rotation operation by the user. On the other hand, if the user tries to return the document conveying unit 1 to the original position but stops at an incomplete position as shown in FIG. 8B, the document is conveyed at the timing when the next document conveyance is started. Part 1 is pushed up by a force FU in the + Z direction. As a result, the user can recognize that the document conveying unit 1 has been pushed back incompletely.

  When the document conveying section 1 is opened to such an extent that the paper jam can be removed, the coupling gear M43 is released from the coupling regulating section M46 and completely connected to the drive gear M42 as shown in FIG. 8C. To separate. For this reason, the rotation of the drive gear M42 is not transmitted to the coupling gear M43, the feed gear M44 does not rotate, and the conveying operation stops.

  As described above, when the driving roller M rotates in the forward direction (conveying direction), when the user rotates the document conveying unit 1, the rotational force of the driving motor M is instantly separated by the axial separation of the helical gear. It is interrupted and the conveyance operation can be stopped without generating a time lag.

  FIGS. 9A to 9C are diagrams illustrating drive transmission states at the rotation position of the document conveying unit 1 when the drive motor M rotates in the reverse direction (the direction opposite to the conveyance). 9A shows a state in which the document conveying unit 1 is closed, FIG. 9B shows a state in which the document conveying unit 1 is slightly opened, and FIG. 9C shows a state in which the document conveying unit 1 is almost completely opened. Each state is shown.

  At the time of initializing the apparatus, the drive motor M temporarily rotates in the reverse direction (the direction opposite to the conveyance) in order to perform the operation of returning the document lifter 6 to the initial position. That is, the drive motor M rotates counterclockwise when viewed in the Y direction, and the drive gear M42 rotates counterclockwise when viewed in the -X direction via the worm gear M41. For this reason, the feed gear M44 connected to the drive gear M42 via the coupling gear M43 rotates in the clockwise direction when viewed in the −X direction, that is, in the direction opposite to the conveying direction.

  In the present embodiment, the coupling parts M421 and M431 are configured to mesh at an angle of about 60 ° in the reverse rotation. For this reason, when the drive motor M rotates in the reverse direction, the coupling gear 43 has an axial force FF3 as shown in FIG. 9A (that is, a direction separated from the drive gear M42 in the X direction). Force) is generated.

  On the other hand, as already described, the coupling gear 43 and the feed gear 44 are helical gears having a twist angle of 20 °. Therefore, when the drive motor M rotates in the reverse direction, the coupling gear 43 has an axial force FF2 (that is, a force in the direction coupled to the drive gear M42) as shown in FIG. Occur. Here, when comparing FF2 and FF3, since the coupling angle 60 ° between the coupling part M421 and the coupling part M431 is larger than the torsion angle 20 ° between the coupling gear M43 and the feed gear M44, Is larger than FF2. Therefore, as a result, a force corresponding to (FF3-FF2) acts on the coupling gear M43 in the + X direction.

  However, the position of the coupling gear M43 is regulated by the coupling regulation part M46 as described above. Therefore, the coupling gear M43 can maintain the rotation at the position shown in FIG. 9A and transmit the rotational force to the feed gear M44.

  When the document conveying unit 1 is slightly rotated, as shown in FIG. 9B, the coupling gear M43 is disengaged from the regulating surface M461 of the coupling regulating unit M46, and the axial force (FF3-FF2). It moves in the + X direction by action. However, a guide slope M462 is formed in an upper position continuous with the regulation surface M461 in the coupling regulation portion M46, and the coupling gear M43 is in contact with the contact slope M432 while contacting the guide slope M462. Gradually move in the + X direction. At this time, a force FU in the + Z direction is generated from the vertical drag of the guide slope M462, and the user assists in the operation of lifting the document conveying unit 1. That is, it is possible to further reduce the burden of the rotation operation by the user. On the other hand, when the user closes the document conveying unit 1 and stops at an incomplete position as shown in FIG. 9B, the document conveying unit 1 moves in the + Z direction at the timing when the next initial operation is started. Is pushed up by the force FU. As a result, the user can recognize that the document conveying unit 1 has been pushed back incompletely.

  When the document conveying section 1 is opened to such an extent that the paper jam can be removed, the coupling gear M43 is released from the coupling regulating section M46 as shown in FIG. Separate completely in the direction. For this reason, the rotation of the drive gear M42 is not transmitted to the coupling gear M43, the feed gear M44 does not rotate, and the conveying operation stops.

  As described above, when the driving roller M rotates in the reverse direction (the direction opposite to the conveying direction), when the user rotates the document conveying unit 1, the rotational force of the driving motor M is applied to the coupling unit. Immediately shut off by axial separation. Therefore, the conveying operation can be stopped without generating a time lag.

  That is, according to the present embodiment, the meshing angle of the coupling portion and the torsion angle between the coupling gear M43 and the feed gear M44 can be determined regardless of whether the drive motor M rotates in the forward direction or in the reverse direction. The coupling gear M43 is adjusted so as to be biased in the + X direction. For this reason, in any direction, it is possible to reduce the burden of the rotation operation of the document conveying unit 1 by the user, and to make an equal notification when the push-back is incomplete.

  FIGS. 10A and 10B are diagrams for explaining a state in which the document conveying unit 1 is opened and the user performs a paper jam removing operation.

  When the user pulls out a document jammed in the document transport path 12, the rotation direction of the transport roller contacting the document differs depending on whether the pulling direction is the document stacking tray 14 side or the document discharge tray 18 side. When the user pulls out the document to the document discharge tray 18 side, the first transport roller and the second transport roller rotate in the forward direction. That is, as shown in FIG. 10A, the feed roller M44 rotates clockwise as viewed in the −X direction. For this reason, a force in the + X direction acts on the coupling gear 43 due to the action of the helical gear with the feed gear 44.

  On the other hand, when the user pulls out the document to the document stacking tray 14 side, the first transport roller and the second transport roller rotate in the reverse direction. That is, as shown in FIG. 10B, the feed roller M44 rotates counterclockwise as viewed in the −X direction. For this reason, a force in the −X direction acts on the coupling gear 43 due to the action of the helical gear with the feed gear 44 and tries to move in the direction of coupling with the drive gear M42. However, when they are coupled, a larger force in the + X direction is generated in the coupling portion between the drive gear M42 and the coupling gear M43. That is, the user does not transmit the driving force of the drive motor M to the feed gear M44 regardless of whether the user pulls out the document to the document stacking tray 14 side or the document discharge tray 18 side. Can be done safely.

  FIGS. 11A and 11B are diagrams for explaining functions when the document conveying unit 1 is not sufficiently closed. When the document conveying section 1 is securely closed, as shown in FIG. 11A, the cover locking claw 101 attached to the document conveying section 1 and the document stacking pressure plate section 40 are arranged in the direction of the arrow in the figure. The cover fixing plates 102 that are biased by are engaged with each other. In the figure, a cross-sectional view as viewed from the side surface on the −X direction side is shown, but such cover holding means such as the cover lock claw 101 and the cover fixing plate 102 are provided at both ends in the X direction intersecting the transport direction. Has been. As shown in FIG. 11A, when the cover lock claw 101 is completely engaged with the cover lock claw 101 positioned below, the document conveying section 1 and the document stacking pressure plate section 40 are continuous as shown in FIG. A plane is formed.

  When the document conveying unit 1 is slightly lifted with respect to the document stacking pressure plate unit 40, the cover lock claw 101 and the cover fixing plate 102 may be balanced with each other. Even in this case, if the drive motor M rotates in either direction, the document conveying unit 1 is pushed up to the state shown in FIG. 11B by the force FU in the + Z direction. As a result, a continuous plane as shown in FIG. 2 cannot be obtained between the document conveying unit 1 and the document stacking pressure plate unit 40, and the user clearly recognizes that the push-back of the document conveying unit 1 is incomplete. I can do it.

  At this time, the force FU in the + Z direction as shown in FIG. 11B is a force generated only on the side where the drive motor M and the gear train M4 exist. Therefore, in the present embodiment, the engagement force between the cover lock claw 101 provided on the + X direction side where the gear train does not exist and the cover fixing plate 102 is used as the cover lock provided on the −X direction side where the gear train exists. The engaging force between the claw 101 and the cover fixing plate 102 is slightly weaker. As a result, when the pushing back of the document conveying unit 1 is incomplete, the both ends of the holding force X direction with respect to the cover can be aligned and lifted to the same extent.

  On the other hand, when the coupling gear M43 is disconnected from the drive gear M42, the load applied to the drive motor M is reduced, and the rotational speed of the drive motor M detected by the rotary encoder M3 is also increased. Using this detection result, the main control IC 302 determines that the document conveying unit 1 is not closed and displays that fact on the display unit 321 or actively uses the PWM control to activate the drive motor M. You may stop.

  With the above-described configuration, it is possible to notify the user that the document conveying unit 1 is not closed, and to avoid a conveyance operation in that state, thereby preventing an inadvertent paper jam.

  In the above embodiment, the force FF3 generated by the engagement of the coupling portion is generated only in the case of reverse rotation. This is because the forward rotation that is the transport direction is assumed to be a long-time rotation and there is concern about wear of the coupling portion. However, in this invention, you may make it utilize force FF3 which generate | occur | produces by engagement of a coupling part at the time of forward rotation.

  Further, in the above, the meshing angle of the coupling portion and the coupling gear M43 and the feed gear M44 are set so that the force in the + X direction acts on the coupling gear M43 in both the forward rotation and the reverse rotation. Defines the torsion angle. However, the present invention is not limited to such a biasing gear configuration. Even in the configuration in which the urging force in the + X direction acts only in any one of the rotation directions, it is possible to obtain the effect of the present invention that the conveyance operation is immediately stopped without generating a time lag.

1 Document reading and conveying section
3 Pickup roller
5 Separation roller
7 First transport roller
9 Second transport roller
M drive motor
M4 gear train
M43 coupling gear
M44 feed gear
M46 regulation means
M421 coupling part
M431 coupling part

Claims (10)

A driving source;
A transport unit for transporting the sheet;
A transmission unit that transmits the driving force of the driving source to the transport unit via a plurality of gears;
A cover that can be opened to open the transport unit;
With
The transmission unit is
A coupling part that can be coupled and separated in the axial direction of rotation;
An urging gear configuration for urging the coupling portion in a direction to separate with rotation;
A regulating means that abuts on the coupling part and regulates the coupling part in a direction in which the coupling part is coupled;
Have
When the cover is closed, the coupling unit is coupled by the regulating means and transmits the driving force of the driving source to the transport unit,
When the cover is opened, the coupling part is released from the restriction by the restriction means and separated by the urging force of the urging gear structure, and the driving force of the driving source is not transmitted to the transport part. A feeding device.   The biasing gear configuration includes a helical gear having a torsion angle that generates a force in a direction in which the coupling part is separated during rotation between the coupling part and a gear coupled to the coupling part. The feeding device according to claim 1.   The feeding device according to claim 1, wherein the biasing gear configuration is configured to mesh with each other, provided on the coupling portion, and formed with slopes that generate a force in a direction of separation when rotating. . The biasing gear configuration includes a helical gear having a torsion angle that generates a force in a direction in which the coupling part separates during rotation between the coupling part and a gear coupled to the coupling part, and the coupling And a meshing structure formed with slopes that generate forces in a direction to separate when rotating, and
2. The torsion angle and the inclined surface are determined so as to urge the coupling portion in a direction in which the coupling portion is separated along with the rotation regardless of the rotation direction of the drive source. The feeding device described.   The said restriction | limiting means has a shape which cancels | releases restrictions with respect to the said coupling part gradually when the said cover is opened, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. Feeding device.   6. The urging gear structure urges the coupling unit in a direction to separate the coupling unit when the transport unit is rotated in a state where the cover is opened. 6. Item 1. The feeding device according to item 1. Further comprising holding means for holding the cover when the cover is closed at both ends in a direction intersecting the direction of conveying the sheet,
The holding force of the holding means located closer to the drive source and the transmission unit is stronger than the holding force of the holding means located farther from the drive source and the transmission unit. 7. The feeding device according to any one of items 6 to 6. Encoder means for detecting rotation of the drive source;
The feeding device according to any one of claims 1 to 7, wherein whether or not the cover is opened is determined based on a result obtained from the encoder means.   The feeding apparatus according to claim 1, further comprising a reading unit that reads an image of a sheet conveyed by the conveyance unit.   The reading unit is used for both image reading of a sheet conveyed by the conveying unit and image reading while moving with respect to a sheet placed on a glass surface. 9. The feeding device according to 9.