JP5564447B2 - Joint mechanism, sheet feeding device, and image forming apparatus - Google Patents

Description

  The present invention relates to a joint mechanism in which a drive shaft and a driven shaft are coupled, and in particular, a sheet feeding device that couples a driven shaft and a driving shaft of a conveyance roller that transports a sheet by a joint mechanism, and the sheet feeding device. The present invention relates to an image forming apparatus provided.

  An image forming apparatus such as a copying machine includes a sheet feeding device that conveys a document sheet such as a document having an image to a predetermined reading position, a reading device that reads a document image of the document sheet at the reading position, and obtains image data; And an image forming unit that forms an image based on the image data on a recording sheet. As a sheet feeding device, for example, one disclosed in Patent Document 1 is known.

  In general, for example, a sheet feeding device is connected to a sheet feeding roller that conveys a document sheet toward a reading position and a sheet feeding shaft (driven shaft) of the sheet feeding roller to rotate the sheet feeding shaft. A shaft, a motor connected to the drive shaft, and a coupling for connecting the paper feed shaft and the drive shaft are included. The drive shaft, paper feed shaft, and coupling constitute a joint mechanism.

  The drive shaft is provided with a first engagement pin that projects in the radial direction of the drive shaft, and the paper feed shaft is provided with a second engagement pin that projects in the radial direction of the paper feed shaft. An engagement groove extending in the axial direction is formed in the coupling wall of the coupling. Then, the drive shaft and the paper feed shaft are connected by engaging the first engagement pin and the second engagement pin with the engagement groove of the coupling. Thereby, the driving force from the motor is transmitted to the paper feed shaft via the drive shaft, and the paper feed roller rotates.

JP 09-089889 A

  However, in the joint mechanism configured as described above, a gap is interposed between the drive shaft and the paper feed shaft. Therefore, the shaft end surface of the drive shaft and the shaft end surface of the paper feed shaft are likely to come into contact with each other due to the rotation operation of the paper feed roller and the drive shaft. When the shaft end faces come into contact with each other, a sound is generated. Such sounds are uncomfortable for the user.

  Therefore, in view of the above circumstances, the present invention provides a joint mechanism capable of preventing the generation of sound due to contact between the shaft end surface of the drive shaft and the shaft end surface of the driven shaft, and a seat including the joint mechanism. An object of the present invention is to provide a sheet feeding device and an image forming apparatus including the sheet feeding device.

In order to achieve the above object, a joint mechanism according to the present invention has a first shaft end surface, a drive shaft that is rotated by a predetermined drive source, and a first shaft that faces the first shaft end surface through a predetermined gap. A driven shaft that has a biaxial end surface and is driven to rotate by being coupled to the drive shaft; a coupling that couples the drive shaft and the driven shaft; the first shaft end surface and the second shaft end surface; Contact prevention means for preventing the first shaft end surface and the second shaft end surface from coming into contact with each other, wherein the drive shaft extends from the drive shaft to the axial direction of the drive shaft. A first engaging pin protruding in a direction orthogonal to the driven shaft, wherein the driven shaft protrudes from the driven shaft in a direction perpendicular to the axial direction of the driven shaft, and faces the first engaging pin in the axial direction; A cylinder having a second engagement pin, the coupling being provided on the drive shaft; The shaft end of the drive shaft is received inside at one end in the axial direction, and the shaft end of the driven shaft is received inside at the other end. A groove portion extending in the axial direction from the other end portion toward the one end portion, and the first engagement pin and the second engagement pin are engaged with the groove portion; The driven shaft is connected to the driven shaft so as to be integrally rotatable, and the contact preventing means is disposed on the drive shaft or the driven shaft so as to occupy the gap, and covers the first shaft end surface or the second shaft end surface A pair of engagement pieces extending in the axial direction so as to face each other from the cover portion, and fixing the cover portion to the drive shaft or the driven shaft, and a pair formed on the pair of engagement pieces, respectively. possess a Goana, wherein the drive shaft or the driven shaft A pair of cut surfaces formed in a predetermined distance from the first or second shaft end surface in the axial direction and extending in parallel to each other, and formed through the shaft end portion from one to the other of the pair of cut surfaces. Through-holes, and both ends of the first engagement pin or the second engagement pin are press-fitted into the through-holes so as to protrude from the peripheral surface of the drive shaft or the driven shaft, A pair of engagement pieces are arranged to face the pair of cut surfaces, and the both end portions are respectively inserted into the pair of engagement holes, whereby the contact prevention means is fixed to the drive shaft or the driven shaft. It is characterized by being.

According to the joint mechanism of the present invention, the contact preventing means is interposed between the first shaft end surface of the drive shaft and the second shaft end surface of the driven shaft. Therefore, the first shaft end surface and the second shaft end surface are prevented from coming into contact with the rotation operation of the driven shaft or the rotation operation of the drive shaft. Thereby, generation | occurrence | production of the sound resulting from the contact between a 1st shaft end surface and a 2nd shaft end surface is prevented. Further, according to this configuration, since the contact preventing means has the cover portion that covers the first shaft end surface or the second shaft end surface, it is easy to prevent contact between the first shaft end surface and the second shaft end surface. It is. Further, according to this configuration, the contact prevention means has the engagement hole that engages with the first engagement pin of the drive shaft or the second engagement pin of the driven shaft. It is easy to attach to the first shaft end surface or the second shaft end surface. In addition, since each of the first engagement pin and the second engagement pin is constituted by a pin, and the engagement hole is constituted by a hole with which the pin can be engaged, the structure can be simplified. In addition, the configuration in which the first engagement pin or the second engagement pin is inserted through the engagement hole and the cover portion is attached is less than the configuration in which the cover portion is attached using an adhesive or a double-sided tape. Can be prevented. Furthermore, according to this structure, the engagement hole is formed in the engagement piece.

  In a preferred embodiment of the present invention, the contact preventing means is an elastic member.

  According to this configuration, since the contact preventing means is an elastic member, even if the drive shaft moves toward the driven shaft or the driven shaft moves toward the drive shaft, the movement of the drive shaft or the driven shaft Is absorbed by the elastic member.

  In another preferred embodiment of the present invention, the contact preventing means is made of an insulating material.

  According to this configuration, since the contact preventing means is formed of an insulating material, for example, even when static electricity is charged on the driven shaft due to the rotation of the driven shaft, the static electricity moves to the drive shaft. Is suppressed. As a result, it is possible to suppress the occurrence of noise caused by static electricity in the drive system, and in particular, malfunction or damage of electronic components mounted in the drive system.

In still another preferred embodiment of the present invention, the joint mechanism further includes a spring member that is provided on the drive shaft and biases the coupling from the drive shaft side toward the driven shaft side.

According to this configuration, the spring member is provided on the drive shaft, and biases the coupling from the drive shaft side toward the driven shaft side.

  A sheet feeding apparatus according to the present invention includes a drive shaft, a driven shaft that is driven to rotate by the drive shaft, a sheet feed roller that conveys a sheet by the rotation of the driven shaft, the drive shaft, and the driven shaft. The joint mechanism having the above-described configuration is used as the joint mechanism.

  Since the sheet feeding apparatus according to the present invention uses the joint mechanism having the above-described configuration, even if the driven shaft moves toward the drive shaft due to the rotation operation of the sheet feeding roller, the contact of the joint mechanism is prevented. Since the movement of the driven shaft is prevented by the means, the generation of sound is prevented.

  An image forming apparatus according to the present invention includes a sheet feeding device that conveys a document sheet having a document image to a reading position, a reading device that reads the document image at the reading position to obtain image data, and the image data An image forming unit that forms an image on a recording sheet, and the sheet feeding device configured as described above is used as the sheet feeding device.

  According to the joint mechanism, the sheet feeding apparatus including the joint mechanism, and the image forming apparatus including the sheet feeding apparatus according to the present invention, the intermediate mechanism is interposed between the shaft end surface of the drive shaft and the shaft end surface of the driven shaft. The contact prevention means prevents the generation of sound due to contact between the shaft end surface of the drive shaft and the shaft end surface of the driven shaft, and the electronic component malfunctions or is damaged due to noise caused by static electricity. It is possible to prevent this.

1 is a perspective view illustrating an appearance of an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view showing an external appearance of an automatic document feeder. 2 is a cross-sectional view illustrating an internal structure of the image forming apparatus. FIG. FIG. 3 is a cross-sectional view of a main part of the automatic document feeder. 2 is an enlarged perspective view showing a portion of a document feeding unit of an automatic document feeder. FIG. FIG. 3 is a perspective view of the document feeding unit viewed from the lower surface side. FIG. 6 is a perspective view of the upper cover unit of the automatic document feeder viewed from the lower surface side. FIG. 8 is a perspective view of a state in which an inner guide member is removed from the upper cover unit of FIG. 7. FIG. 7 is a partially enlarged view of FIG. 6 and shows a joint portion. It is a perspective view which shows the state which removed the coupling from the joint part. It is a perspective view which shows the state in which the contact prevention member was attached to the drive shaft. It is a perspective view of a contact prevention member. It is a perspective view of the shaft end part to which the contact prevention member in a drive shaft is attached.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing an appearance of an image forming apparatus 1 according to an embodiment of the present invention, FIG. 2 is a perspective view showing an appearance of an automatic document feeder 3, and FIG. 3 is an internal view of the image forming apparatus 1. It is sectional drawing which shows a structure. Here, the in-body discharge type copier is illustrated as the image forming apparatus 1, but the image forming apparatus 1 may be a printer, a facsimile machine, or a multifunction machine having these functions.

  The image forming apparatus 1 includes a main body 2 having a substantially rectangular parallelepiped housing structure and an in-cylinder space (in-cylinder paper discharge unit 24), and an automatic document feeder 3 (on the upper surface of the main body 2). Sheet feeding device) and an additional paper feeding unit 4 assembled on the lower side of the apparatus main body 2.

  The apparatus main body 2 performs an image forming process on the sheet. The apparatus main body 2 includes a substantially rectangular parallelepiped lower casing 21, a substantially rectangular parallelepiped upper casing 22 disposed above the lower casing 21, and a connection that connects the lower casing 21 and the upper casing 22. And a housing 23. The lower housing 21 accommodates various devices for image formation, and the upper housing 22 accommodates various devices for optically reading a document image. An in-cylinder space surrounded by the lower casing 21, the upper casing 22, and the connecting casing 23 serves as an in-cylinder discharge unit 24 that can store a sheet after image formation. The connection housing 23 is disposed on the right side surface of the apparatus main body 2 and is provided with a discharge port 961 for discharging the sheet to the in-body discharge unit 24.

  The in-cylinder space used as the in-cylinder sheet discharge unit 24 is open to the outside on the front surface and the left side surface of the apparatus main body 2. The user can insert his / her hand through these open portions and take out the sheet after image formation from the in-body sheet discharge unit 24. A bottom surface 241 of the in-cylinder space is partitioned by the upper surface of the lower housing 21 and a sheet discharged from the discharge port 961 is stacked thereon.

  An operation panel unit 25 protrudes from the front surface of the upper housing 22. The operation panel unit 25 includes an operation key 251 including a numeric keypad and a start key, an LCD touch panel 252 and the like, and receives input of various operation instructions from the user. The user can input the number of sheets to be printed and the like and input the print density and the like through the operation panel unit 25.

  A paper feed cassette 211 that houses a recording sheet on which image forming processing is performed is mounted on the lower housing 21. The additional sheet feeding unit 4 also includes sheet feeding cassettes 41 and 42 that store recording sheets on which image forming processing is performed. These sheet feeding cassettes 211, 41, and 42 are cassettes provided for automatic sheet feeding, and can accommodate a large number of recording sheets according to size. Further, the paper feed cassettes 211, 41, and 42 can be pulled out from the front of the lower housing 21 or the additional paper feed unit 4. In FIG. 3, only the paper feed cassette 211 of the lower housing 21 is illustrated.

  A multi-tray unit M is installed on the right side of the apparatus main body 2 for allowing the user to manually feed paper. The multi-tray unit M includes a paper feed tray 43 on which a manually fed recording sheet is placed, and a paper feeding unit 44 that carries the recording sheet into an image forming unit in the lower housing 21. The paper feed tray 43 is attached to the lower housing 21 at its lower end so as to be openable and closable, and is closed when not in use. When the user manually feeds paper, the user opens the paper feed tray 43 and places a recording sheet thereon.

  The automatic document feeder 3 is attached to the upper surface of the apparatus body 2 so as to be rotatable at the rear side. In FIG. 3, the description of the automatic document feeder 3 is omitted. The automatic document feeder 3 automatically feeds a document sheet to be copied toward a predetermined document reading position (position where the first contact glass 222 is assembled) in the apparatus body 2. On the other hand, when the user manually places the document sheet on a predetermined document reading position (position of the second contact glass 223), the automatic document feeder 3 is opened upward.

  Referring to FIG. 2, the automatic document feeder 3 includes a main body housing 30, a document feed tray 31, a document transport unit 32, a document discharge tray 33, and a document reversing tray 31B. The main body housing 30 is a housing that houses various mechanisms provided in the automatic document feeder 3, and has a front wall portion 301 and a rear wall that protrude upward from the left side portion that houses the document conveying portion 32. A portion 302 is provided, and a substantially flat low layer portion is provided on the right side portion.

  The document feed tray 31 is a tray on which a document sheet fed to the image reading position is placed, and is attached to the main body housing 30 so as to extend from the feeding port 30H of the main body housing 30. . The document feed tray 31 is provided with a pair of cursors 311 for adjusting the width of the placed document sheet.

  The document transport unit 32 includes a transport path and a transport mechanism for transporting the document sheet on the document feed tray 31 to the document discharge tray 33 via the image reading position. The document conveying unit 32 includes an upper cover unit 32 </ b> U that is fitted into an opening between the front wall portion 301 and the rear wall portion 302 of the main body housing 30. These details will be described in detail later based on FIG.

  The document discharge tray 33 is a tray from which a document sheet after a document image is optically read is discharged. An upper surface of the lower layer portion on the right side of the main body housing 30 is a document discharge tray 33. The document reversing tray 31B is a tray from which a document sheet is temporarily ejected when a document sheet having document images on both sides is read.

  Next, the internal structure of the apparatus main body 2 will be described with reference to FIG. In the lower casing 21, toner containers 99Y, 99M, 99C, and 99K, an intermediate transfer unit 92, an image forming unit 93, an exposure unit 94, and the above-described paper feed cassette 211 are accommodated in this order from the top.

  The image forming unit 93 includes four image forming units 10Y and 10M that form yellow (Y), magenta (M), cyan (C), and black (K) toner images in order to form a full-color toner image. 10C, 10K. Each of the image forming units 10Y, 10M, 10C, and 10K includes a photosensitive drum 11, and a charger 12, a developing device 13, a primary transfer roller 14, and a cleaning device 15 that are arranged around the photosensitive drum 11. .

  The photosensitive drum 11 rotates about its axis, and an electrostatic latent image and a toner image are formed on its peripheral surface. As the photoreceptor drum 11, a photoreceptor drum using an amorphous silicon (a-Si) material can be used. The charger 12 uniformly charges the surface of the photosensitive drum 11. The peripheral surface of the photosensitive drum 11 after charging is exposed by the exposure unit 94 to form an electrostatic latent image.

  The developing device 13 supplies toner to the peripheral surface of the photosensitive drum 11 in order to develop the electrostatic latent image formed on the photosensitive drum 11. The developing device 13 is for a two-component developer, and includes stirring rollers 16 and 17, a magnetic roller 18, and a developing roller 19. The stirring rollers 16 and 17 charge the toner by circulating and conveying the two-component developer while stirring. A two-component developer layer is carried on the peripheral surface of the magnetic roller 18, and toner formed by transferring toner to the peripheral surface of the developing roller 19 due to a potential difference between the magnetic roller 18 and the developing roller 19. The layer is supported. The toner on the developing roller 19 is supplied to the peripheral surface of the photosensitive drum 11 and the electrostatic latent image is developed.

  The primary transfer roller 14 forms a nip portion with the photosensitive drum 11 across the intermediate transfer belt 921 provided in the intermediate transfer unit 92, and the toner image on the photosensitive drum 11 is primary transferred onto the intermediate transfer belt 921. To do. The cleaning device 15 cleans the peripheral surface of the photosensitive drum 11 after the toner image is transferred.

  The yellow toner container 99Y, the magenta toner container 99M, the cyan toner container 99C, and the black toner container 99K respectively store toner of each color, and image forming units 10Y, 10M, and 10C corresponding to the respective colors of YMCK. Each color toner is supplied to the 10K developing device 13 through a supply path (not shown).

  The exposure unit 94 includes various optical system devices such as a light source, a polygon mirror, a reflection mirror, and a deflection mirror, and is provided on the peripheral surface of the photosensitive drum 11 provided in each of the image forming units 10Y, 10M, 10C, and 10K. The electrostatic latent image is formed by irradiating light based on the image data of the document image.

  The intermediate transfer unit 92 includes an intermediate transfer belt 921, a driving roller 922, and a driven roller 923. On the intermediate transfer belt 921, toner images are overcoated from the plurality of photosensitive drums 11 (primary transfer). The overcoated toner image is secondarily transferred to the recording sheet supplied from the paper feed cassette 211 by the secondary transfer unit 98. A driving roller 922 and a driven roller 923 that rotate the intermediate transfer belt 921 are rotatably supported by the lower housing 21.

  The paper feed cassette 211 (41, 42) stores a sheet bundle in which a plurality of recording sheets are stacked. A pickup roller 212 is disposed at the upper right side of the paper feed cassette 211. By driving the pickup roller 212, the uppermost recording sheet of the sheet bundle in the sheet feeding cassette 211 is fed out one by one and carried into the carry-in conveyance path 26. On the other hand, the manually fed recording sheet placed on the paper feed tray 43 is carried into the carry-in conveyance path 26 by driving the paper feed roller 45 of the paper feed unit 44.

  On the downstream side of the carry-in conveyance path 26, a sheet conveyance path 28 that extends to the discharge port 961 through the secondary transfer unit 98, a fixing unit 97 and a paper discharge unit 96 described later is provided. The upstream portion of the sheet conveyance path 28 is formed between an inner wall formed in the lower housing 21 and an inner wall that forms the inner surface of the reverse conveyance unit 29. The outer surface of the reverse conveyance unit 29 constitutes one side of a reverse conveyance path 291 that reversely conveys the sheet during duplex printing. A registration roller pair 27 is disposed on the upstream side of the sheet transfer path 28 from the secondary transfer unit 98. After the sheet is temporarily stopped by the registration roller pair 27 and skew correction is performed, the sheet is sent to the secondary transfer unit 98 at a predetermined timing for image transfer.

  A fixing unit 97 and a paper discharge unit 96 are accommodated in the connection housing 23. The fixing unit 97 includes a heating roller and a pressure roller, and performs a fixing process by heating and pressing the recording sheet on which the toner image is secondarily transferred in the secondary transfer unit 98. The recording sheet with the color image that has been subjected to the fixing process is discharged from the discharge port 961 toward the in-body discharge unit 24 by a discharge unit 96 disposed downstream of the fixing unit 97.

  A first contact glass 222 and a second contact glass 223 are fitted on the upper surface of the upper housing 22. The first contact glass 222 is provided for reading a document sheet automatically fed from the automatic document feeder 3. The second contact glass 223 is provided for reading a manually placed document sheet.

  A scanning mechanism 224 and an image sensor 225 for optically reading document information on a document sheet are accommodated in the upper housing 22. The scanning mechanism 224 includes a light source, a moving carriage, a reflection mirror, and the like, and guides reflected light from the document to the image sensor 225. The image sensor 225 photoelectrically converts the reflected light into an analog electrical signal. The analog electric signal is converted into a digital electric signal by an A / D conversion circuit (not shown) and then input to the exposure unit 94.

  Next, the internal structure of the automatic document feeder 3 will be described in detail with reference to FIGS. FIG. 4 is a cross-sectional view of a main part (original conveying section 32) of the automatic document feeder 3. The document transport unit 32 includes first to fifth transport paths 341 to 345 that serve as transport paths for document sheets, and first to fifth transport roller pairs disposed at appropriate positions of the first to fifth transport paths 341 to 345. 351 to 355 and a document feeding unit 5 that feeds a document sheet placed on the document feed tray 31 into the document transport unit 32. 5 is an enlarged perspective view of the document feeding unit 5, FIG. 6 is a perspective view of the document feeding unit 5 viewed from the lower surface side, and FIG. 7 is a view of the upper cover unit 32U described above from the lower surface side. FIG. 8 is a perspective view of the upper cover unit 32U in a state where the guide member 321 on the inner surface is removed.

  The first, second, and third transport paths 341, 342, and 343 discharge the document sheet from the feeding port 30H to the document discharge tray 33 via the optical reading position X of the document image. A conveyance path that is curved in a U-shape that extends to the paper discharge port 30E is configured. On the other hand, the fourth and fifth conveyance paths 344 and 345 are switchback conveyance paths used for reversing the original sheet when reading an original sheet having an original image on both sides.

  The first conveyance path 341 is a conveyance path that continues to the document feed tray 31 and extends to the left from the feeding port 30H slightly downward, and the document sheet sent out from the document feeding unit 5 first passes therethrough. It is a transport path. The upper conveyance surface of the first conveyance path 341 is defined by a guide member 321 (see FIG. 7) of the upper cover unit 32U. The second conveyance path 342 is an arcuate conveyance path that extends from the downstream end of the first conveyance path 341 to a position facing the first contact glass 222 that is the document reading position X. One transport surface of the second transport path 342 is also defined by the guide member 321 of the upper cover unit 32U. The third conveyance path 343 is a conveyance path extending slightly upward from the position facing the first contact glass 222 to the right to the paper discharge outlet 30E. A contact surface guide 36 that slides the document sheet against the first contact glass 222 is disposed at a position facing the first contact glass 222.

  The fourth conveyance path 344 is a conveyance path that branches from the third conveyance path 343 and extends to the upper right. A sorting lever 37 is disposed at a branch portion between the third transport path 343 and the fourth transport path 344. The sorting lever 37 guides the original sheet to the third transport path 343 in the case of normal single-sided reading. However, when double-sided reading of the original sheet is performed, the original sheet that has been subjected to single-sided reading needs to be reversed. When there is, the document sheet is guided to the fourth conveyance path 344. The fifth conveyance path 345 is a substantially horizontal conveyance path that communicates with the fourth conveyance path 344 and the first conveyance path 341 and the document reversing tray 31B. The fifth conveyance path 345 receives a document sheet to be turned upside down from the fourth conveyance path 344. This is a transport path for switchback transport to one transport path 341.

  The first, second, third, fourth, and fifth transport roller pairs 351, 352, 353, 354, and 355, respectively, drive rollers 351A, 352A, 353A, and 354A that generate a rotational driving force for transporting the original sheet. And 355A and driven rollers 351B, 352B, 353B, 354B, and 355B that are in contact with and rotate.

  The first conveyance roller pair 351 is disposed between the first conveyance path 341 and the second conveyance path 342 and feeds the document sheet toward the second conveyance path 342 that is largely curved. The second transport roller pair 352 is disposed immediately upstream of the document reading position X, and feeds the document sheet to the document reading position X. The third conveyance roller pair 353 is arranged immediately downstream of the document reading position X, and sends the document sheet after image reading to the third conveyance path 343 or the fourth conveyance path 344. The fourth transport roller pair 354 is disposed in the vicinity of the paper discharge port 30 </ b> E and discharges the original sheet toward the original discharge tray 33. The fifth conveyance roller pair 355 is a pair of rollers capable of normal rotation and reverse rotation, and is disposed in the fifth conveyance path 345, and executes the switchback conveyance of the document sheet by utilizing the document reversing tray 31B.

  The document feeding unit 5 includes a pickup roller 51, a document feeding roller 52 disposed downstream of the pickup roller 51 in the sheet conveyance direction, and a feeding direction of a document sheet placed on the document feeding tray 31. It includes a pair of stoppers 53 that restrict the tips, a holder 50 that holds these members, a drive mechanism 56, a joint portion 60, and a torsion coil spring 57 that applies a rotational force to the holder 50. As shown in FIGS. 7 and 8, the document feeding unit 5 is assembled to the upper cover unit 32U.

  The holder 50 is a box-shaped member that includes a flat plate-like upper plate 500 and a front plate 501, a rear plate 502, and a middle plate 503 made of rib members integrated with the upper plate 500. The front plate 501 and the rear plate 502 are provided with a front cylindrical portion 504 and a rear cylindrical portion 505 that are coaxially arranged. The holder 50 swings around the cylindrical center of the front cylindrical portion 504 and the rear cylindrical portion 505.

  The pickup roller 51 is given a rotational force that rotates about its axis, and feeds the original sheets placed on the original paper feed tray 31 one by one toward the original conveyance section 32 (first conveyance path 341). The rotation shaft of the pickup roller 51 is rotatably supported on the right end side of the rear plate 502 and the middle plate 503. The pick-up roller 51 is configured so that the front cylindrical portion 504 and the rear cylindrical portion 505 of the holder 50 swing around the center of the cylinder, and the feeding position that contacts the upper surface of the document sheet on the document feed tray 31 and the document sheet The position is changed between a retreat position spaced upward from the upper surface.

  As shown in FIG. 5, a separating pad 313 is disposed at a position facing the pickup roller 51 at the downstream end 312 of the document feeding tray 31. When the pickup roller 51 is at the paper feed position, a nip portion is formed between the pickup roller 51 and the rolling pad 313.

  The document feed roller 52 transports one document sheet sent from the pickup roller 51 further toward the first transport path 341. A driven rotation shaft 521 (driven shaft) of the document feed roller 52 is rotatably supported by the front plate 501 and the rear plate 502 of the holder 50. When a document sheet feeding operation is performed, a rotational driving force is applied to the driven rotating shaft 521, and the document feeding roller 52 rotates. As shown in FIG. 4, a driven roller 350 is disposed in the main body housing so as to face the document feeding roller 52. The front cylindrical portion 504 and the rear cylindrical portion 505 of the holder 50 described above are attached so as to be rotatable around the axis of the driven rotation shaft 521. In other words, the axis of the driven rotating shaft 521 and the cylinders of the front cylindrical part 504 and the rear cylindrical part 505 of the holder 50 are coaxial, so that the document feed roller 52 can move even if the holder 50 swings. It does not move up and down and always forms a driven roller 350 and a paper feed nip.

  The pair of stoppers 53 are respectively attached to the outer surface sides of the front plate 501 and the rear plate 502 of the holder 50 so as to be positioned approximately in the middle between the pickup roller 51 and the document feed roller 52. The stopper 53 includes an engaging portion 531 that engages with the holder 50, a stopper piece 532 that stops the leading edge of the document sheet placed on the document feeding tray 31, and the engaging portion 531. And a pin 533 that is rotatably supported with respect to. The stopper piece 532 is stopped by the engaging portion 531 with respect to the clockwise rotation when viewed from the front, and can be rotated only in the counterclockwise direction.

  When the pickup roller 51 is in the retracted position, the stopper piece 532 protrudes to the downstream end 312 of the document feeding tray 31 and restricts the leading edge of the document sheet in the sheet feeding direction, as shown in FIG. On the other hand, when the holder 50 swings and the pickup roller 51 is in the paper feed position, the stopper piece 532 is lifted at the lower end of the stopper piece 532 as the right end of the holder 50 is lowered, and the leading edge of the original sheet is fed. To remove the restrictions. When a jam occurs during conveyance of the document sheet and the user performs an operation of pulling out the document sheet in the direction opposite to the paper feeding direction, the stopper piece 532 rotates counterclockwise around the pin 533. For this reason, the document sheet pulling-out operation is not hindered.

  A first wheel 541 having a large number of grooves formed on the outer peripheral surface is fixed to the rotation shaft of the pickup roller 51. A second wheel 542 having a similar groove is fixed to the driven rotation shaft 521 of the document feed roller 52 (see FIG. 6). These first and second wheels 541 and 542 are arranged at positions on the rear side of the pickup roller 51 and the document feed roller 52, respectively. An endless belt 55 for power transmission is stretched over the first and second wheels 541 and 542. On the inner peripheral surface of the endless belt 55, a number of protrusions that engage with grooves provided in the first and second wheels 541 and 542 are formed. When a rotational driving force in the direction of feeding the original sheet to the driven rotation shaft 521 of the document feeding roller 52 (positive rotational driving force; clockwise rotational driving force when viewed from the front) is given, the rotational force is It is transmitted to the rotating shaft of the pickup roller 51 through the endless belt 55. As a result, both the pickup roller 51 and the document feed roller 52 rotate synchronously.

  The drive mechanism 56 is a mechanism for transmitting a forward or reverse rotational driving force to the driven rotational shaft 521 of the document feed roller 52. As shown in FIG. 6, the drive mechanism 56 includes a motor 7, a drive shaft 562, and a drive input unit 563. The motor 7 generates a rotational driving force in the forward direction and the reverse direction. As the motor 7, a DC motor, a stepping motor, or the like can be used. A rotational driving force is applied to the drive input unit 563 from the motor 7 via a gear mechanism (not shown). Since the drive shaft 562 is integrated with the drive input unit 563, the drive shaft 562 is rotated by the rotational driving force.

  The joint unit 60 mechanically connects the drive shaft 562 of the drive mechanism 56 and the driven rotation shaft 521 of the document feed roller 52 to transmit the rotational driving force of the drive shaft 562 to the driven rotation shaft 521. As the driving force is transmitted by the joint unit 60, the driven rotation shaft 521 is driven to rotate, and the document feed roller 52 is rotated. As the driven rotation shaft 521 rotates, the pickup roller 51 rotates via the endless belt 55 and sends out the original sheet. Details of the joint portion 60 will be described later with reference to FIGS.

  The torsion coil spring 57 is inserted into a boss 571 integrated with the driven rotary shaft 521 with a constant holding force, and includes a forward direction engagement portion and a reverse direction engagement portion for the holder 50. The torsion coil spring 57 is a member that connects the holder 50 and the driven rotating shaft 521 in a spring clutch manner, and transmits the rotational force of the driven rotating shaft 521 to the holder 50 in a range where the swing of the holder 50 is not restricted. The member fulfills the function of not transmitting the rotational force of the driven rotary shaft 521 to the holder 50 in a state where the swing of the holder 50 is restricted. A torque limiter can be used in place of the torsion coil spring 57.

  When a rotational drive force in the positive direction is applied to the driven rotary shaft 521, the torsion coil spring 57 rotates integrally with the driven rotary shaft 521 by the holding force, and the positive direction engaging portion transmits the rotational force to the holder 50. As a result, the holder 50 rotates clockwise around the axis of the driven rotation shaft 521, and the pickup roller 51 moves to a paper feed position that contacts the upper surface of the original sheet placed on the original feed tray 31. . After the pickup roller 51 is abutted against the document feed tray 31, the winding force of the torsion coil spring 57 on the driven rotation shaft 521 is loosened, and the driven rotation shaft 521 (boss 571) is idled with respect to the torsion coil spring 57. Become. Thereby, the rotational force of the driven rotating shaft 521 is not transmitted to the holder 50 after being moved to the paper feeding position.

  The same applies to the case where a reverse rotational driving force is applied to the driven rotary shaft 521. In this case, the reverse direction engaging portion engages with the holder 50, and the holder 50 is rotated counterclockwise around the axis of the driven rotation shaft 521. As a result, the pickup roller 51 moves to a retracted position spaced upward from the upper surface of the original sheet. 4 and 5 show a state where the pickup roller 51 is moved to the retracted position. After the holder 50 is abutted against the top plate 320 of the upper cover unit 32U, the driven rotary shaft 521 is idled with respect to the torsion coil spring 57, and after being moved to the retracted position, the driven rotary shaft 521 is moved. Is not transmitted to the holder 50.

  Next, the joint part 60 is demonstrated with reference to FIGS. FIG. 9 is a partially enlarged view of FIG. 6 and shows the joint portion 60. As described above, the joint portion 60 connects the drive shaft 562 of the drive mechanism 56 and the driven rotation shaft 521 of the document feed roller 52, and includes a contact prevention member 61 (contact prevention means) and a coupling 62. And a pressing spring 63. FIG. 10 is a perspective view showing a state where the coupling 62 is removed from the joint portion 60. 11 is a perspective view showing a state in which the contact prevention member 61 is attached to the drive shaft 562, FIG. 12 is a perspective view of the contact prevention member 61, and FIG. 13 is a contact prevention member 61 in the drive shaft 562. It is a perspective view of the shaft end to which is attached. In the present embodiment, the joint unit 60, the drive shaft 562 of the drive mechanism 56, and the driven rotation shaft 521 of the document feed roller 52 constitute a joint mechanism.

  The contact prevention member 61 is a member that prevents the shaft end surface of the drive shaft 562 (hereinafter referred to as the first shaft end surface 565) and the shaft end surface of the driven rotation shaft 521 (hereinafter referred to as the second shaft end surface 523) from contacting each other. It is. The first shaft end surface 565 and the second shaft end surface 523 are opposed to each other via a predetermined gap G, and the contact prevention member 61 is interposed in the gap G, so that the first shaft end surface 565 and the second shaft The contact with the end surface 523 is prevented. The contact preventing member 61 is an elastic member formed from a material such as resin or rubber. Moreover, it is preferable that the material of the contact prevention member 61 is a material provided with insulation.

  Specifically, as shown in FIG. 12, the contact prevention member 61 includes a cover portion 610 that covers the first shaft end surface 565 and a pair of engagements for fixing the cover portion 610 to the shaft end portion of the drive shaft 562. And a piece 613 (third engagement portion).

  The cover portion 610 is a portion having a flat shape, and includes a first surface 611 that covers the first shaft end surface 565 in contact with the first shaft end surface 565, and a second surface opposite to the first surface 611. 612. The first surface 611 is a surface orthogonal to the axial direction of the drive shaft 562, and the second surface 612 is a surface orthogonal to the axial direction of the driven rotation shaft 521. The first surface 611 has a shape that can cover substantially the entire first shaft end surface 565. The second surface 612 is a surface that contacts the second shaft end surface 523. Since the distance between the first surface 611 and the second surface 612, that is, the thickness of the cover portion 610 corresponds to the size of the gap G, the cover portion 610 is disposed so as to occupy the gap G. The thickness dimension of the cover portion 610 is a dimension in the axial direction of the drive shaft 562.

  The pair of engaging pieces 613 protrude from the edge of the cover 610 so as to face each other and to extend in parallel to each other. Each engagement piece 613 extends in the axial direction of the drive shaft 562. Each engagement piece 613 is formed with an engagement hole 615 extending from the edge of the cover 610 to the tip in the protruding direction.

  The drive shaft 562 to which the contact prevention member 61 is attached has a pair of cut surfaces 566 at the shaft end as shown in FIG. Each cut surface 566 is formed by cutting the shaft end portion in the axial direction by a predetermined distance from the first shaft end surface 565. The pair of cut surfaces 566 are formed so as to extend in parallel with each other across the axis. The distance between one cut surface 566 and the other cut surface 566 is set to be substantially equal to the distance between the pair of engagement pieces 613 of the contact prevention member 61. A through hole 567 is formed from one cut surface 566 to the other cut surface 566.

  The contact preventing member 61 is attached to the shaft end portion of the drive shaft 562 as follows. That is, the pair of engaging pieces 613 of the contact preventing member 61 are slid along the corresponding cut surfaces 566, and the cover portion 610 is abutted against the first shaft end surface 565. Thereby, the engagement hole 615 of one engagement piece 613, the through-hole 567, and the engagement hole 615 of the other engagement piece 613 are located in a line. Then, the first engagement pin 564 (first engagement portion) is press-fitted in the order of one engagement hole 615, the through hole 567, and the other engagement hole 615, thereby preventing contact as shown in FIG. The member 61 is fixed to the shaft end portion of the drive shaft 562. At this time, the cover portion 610 is in close contact with the first shaft end surface 565 and covers substantially the entire first shaft end surface 565. The first engagement pins 564 extend from the drive shaft 562 in a direction orthogonal to the axial direction of the drive shaft 562, and both end portions protrude from the peripheral surface of the drive shaft 562 in opposite directions. Instead of the procedure for fixing the contact prevention member 61 as described above, after the first engagement pin 564 is press-fitted into the through hole 567, the pair of engagement pieces 613 of the contact prevention member 61 having elasticity is expanded. By passing one end portion of the first engagement pin 564 through one engagement hole 615 and passing the other end portion of the first engagement pin 564 through the other engagement hole 615, the contact preventing member 61 is passed. May be fixed.

  The coupling 62 is a cylindrical member, and receives the shaft end portion of the drive shaft 562 formed with the first shaft end surface 565 at one end portion, and receives the second shaft at the other end portion. The shaft end portion of the driven rotation shaft 521 formed with the end surface 523 is received.

  The coupling 62 has a shape that can be engaged with each of the first engagement pin 564 of the drive shaft 562 and the second engagement pin 522 (second engagement portion) of the driven rotation shaft 521. Specifically, the second engagement pin 522 extends from the driven rotation shaft 521 in a direction orthogonal to the axial direction of the driven rotation shaft 521, and both end portions thereof are opposite to each other from the peripheral surface of the driven rotation shaft 521. It protrudes. A groove portion 621 extending in the axial direction is formed in the cylindrical wall of the coupling 62. The groove portion 621 is a groove portion 621 extending from the end portion on the driven rotation shaft 521 side toward the end portion on the drive shaft 562 side by a predetermined distance. The coupling 62, the drive shaft 562, and the driven rotation shaft 521 are disposed concentrically. Then, the first engagement pin 564 of the drive shaft 562 and the second engagement pin 522 of the driven rotation shaft 521 are fitted into the groove portion 621, so that the coupling 62, the drive shaft 562, and the driven rotation shaft 521 are engaged. And the drive shaft 562 and the driven rotating shaft 521 are mechanically coupled.

  The rotational driving force of the drive shaft 562 is transmitted to the driven rotational shaft 521 as follows. That is, when the drive shaft 562 rotates, the first engagement pin 564 rotates accordingly. Since the first engagement pin 564 is fitted in the groove portion 621 of the coupling 62, the coupling 62 rotates with the rotation of the first engagement pin 564. Since the second engagement pin 522 is fitted in the groove 621, the second engagement pin 522 rotates with the rotation of the coupling 62. Thereby, the driven rotating shaft 521 rotates. Thus, the rotational driving force transmitted from the drive shaft 562 to the driven rotation shaft 521 rotates the document feed roller 52 and the pickup roller 51.

  The pressing spring 63 presses the coupling 62 toward the first engaging pin 564 so that the first engaging pin 564 fitted in the groove 621 of the coupling 62 is pressed by the terminal end 622 of the groove 621. . The pressing spring 63 has a coil that surrounds the drive shaft 562, one end of the coil is abutted against a stopper portion 564 provided on the peripheral surface of the drive shaft 562, and the other end is a drive shaft in the coupling 62. It contacts the end surface on the 562 side. The pressing spring 63 causes a biasing force to act on the coupling 62 so that the coupling 62 moves from the drive shaft 562 side to the driven rotation shaft 521 side. Due to this urging force, the first engagement pin 564 comes into contact with the end 622 of the groove 621.

  According to the automatic document feeder 3 according to the present embodiment described above, the cover portion 610 of the contact preventing member 61 of the joint portion 60 includes the first shaft end surface 565 of the drive shaft 562 and the second shaft of the driven rotation shaft 521. The first shaft end surface 565 and the second shaft end surface 523 are interposed so as to occupy a gap G between the end surface 523 and the end surface 523. Therefore, the first shaft end surface 565 and the second shaft end surface 523 are prevented from coming into contact with the rotation operation of the driven rotation shaft 521 (the rotation operation of the document feed roller 52) and the rotation operation of the drive shaft 562. . Thereby, generation | occurrence | production of the sound resulting from the contact between the 1st shaft end surface 565 and the 2nd shaft end surface 523 is prevented.

  Moreover, since the cover portion 610 covers the first shaft end surface 565, it is easy to prevent contact between the first shaft end surface 565 and the second shaft end surface 523. In addition, since the generation of sound is prevented by the configuration in which the first shaft end surface 565 is interposed between the first shaft end surface 565 and the second shaft end surface 523, the structure of the contact prevention member 61 can be simplified. .

  Further, according to the automatic document feeder 3 according to the present embodiment, the drive shaft 562 is driven in accordance with the rotation operation of the driven rotation shaft 521 (rotation operation of the document feed roller 52) and the rotation operation of the drive shaft 562. Even if it moves toward the rotating shaft 521 or the driven rotating shaft 521 moves toward the driving shaft 562, the contact preventing member 61 is an elastic member, so that the driving shaft 562 and the driven rotating shaft 521 are not moved. Absorbed by the elastic member. Thereby, generation | occurrence | production of a sound is prevented.

  Furthermore, according to the automatic document feeder 3 according to the present embodiment, the driven rotation shaft 521 is caused by, for example, the rotation operation of the driven rotation shaft 521 or the frictional contact between the document feeding roller 52 and the document sheet. Even when static electricity is charged, the contact preventing member 61 is made of an insulating material, and thus the static electricity is suppressed from moving to the drive shaft 562. As a result, it is possible to suppress the occurrence of noise caused by static electricity in the drive system, and in particular, malfunction or damage of electronic components mounted in the drive system. The thickness dimension of the cover portion 610 of the contact preventing member 61 is set to be larger than the distance that static electricity can move from the driven rotation shaft 521 to the drive shaft 562.

  Furthermore, according to the automatic document feeder 3 according to the present embodiment, the first engagement pins 564 (first engagement portions) are connected to the engagement holes 615 (the engagement holes 615 of the pair of engagement pieces 613 of the contact prevention member 61). The cover portion 610 can be easily attached to the first shaft end surface 565 simply by passing through the third engagement portion. In addition, since the first engaging portion is constituted by a pin and the third engaging portion is constituted by a hole in which the pin can be engaged, the structure can be simplified. Further, the configuration in which the first engaging pin 564 is inserted through the engagement hole 615 and the cover portion 610 is attached is the first configuration of the cover portion 610 as compared with the configuration in which the cover portion 610 is attached using an adhesive or a double-sided tape. Dropping from the shaft end surface 565 can be prevented.

  In the present embodiment described above, the configuration in which the contact prevention member 61 is attached to the shaft end portion of the drive shaft 562 and the first shaft end surface 565 is covered by the cover portion 610 has been described, but instead of this configuration, the contact prevention member A configuration may be adopted in which 61 is attached to the shaft end of the driven rotation shaft 521 and the second shaft end surface 523 is covered by the cover 610. Even in that case, the above-described effects can be obtained.

1 Image forming apparatus 3 Automatic document feeder (sheet feeder)
52 Document Feeding Roller 521 Driven Rotating Shaft (Driven Shaft)
522 Second engagement pin (second engagement portion)
523 Second shaft end surface 56 Drive mechanism 562 Drive shaft 564 First engagement pin (first engagement portion)
565 First shaft end surface 60 Joint portion 61 Contact prevention member (contact prevention means)
610 Cover portion 613 Engagement piece 615 Engagement hole (third engagement portion)
62 Coupling 621 Groove 63 Pressing Spring

Claims (6)

A drive shaft having a first shaft end surface and rotated by a predetermined drive source;
A driven shaft having a second shaft end surface facing the first shaft end surface through a predetermined gap, and being driven and rotated by being connected to the drive shaft;
A coupling for connecting the drive shaft and the driven shaft;
Contact preventing means interposed between the first shaft end surface and the second shaft end surface to prevent the first shaft end surface and the second shaft end surface from contacting each other;
With
The drive shaft has a first engagement pin that protrudes from the drive shaft in a direction perpendicular to the axial direction of the drive shaft,
The driven shaft has a second engagement pin that protrudes from the driven shaft in a direction perpendicular to the axial direction of the driven shaft and faces the first engagement pin in the axial direction;
The coupling is a cylindrical member provided in the drive shaft, and receives the shaft end portion of the drive shaft inside at one end portion in the axial direction, and internally at the other end portion. Receiving a shaft end of the driven shaft, and further comprising a groove extending in the axial direction from the other end toward the one end,
When the first engagement pin and the second engagement pin engage with the groove portion, the drive shaft and the driven shaft are coupled so as to be integrally rotatable,
The contact preventing means is disposed on the drive shaft or the driven shaft so as to occupy the gap, and covers the first shaft end surface or the second shaft end surface and faces the cover portion from each other. the axial direction extends, possess a pair of engagement pieces for securing the cover portion to the drive shaft or the driven shaft, and engaging holes which are formed respectively on the pair of engaging pieces, and
The drive shaft or the driven shaft is formed with a predetermined distance from the first or second shaft end surface in the axial direction and extends in parallel to each other, and a shaft extending from one to the other of the pair of cut surfaces. A through hole formed through the end,
Both ends of the first engagement pin or the second engagement pin are press-fitted into the through hole so as to protrude from the peripheral surface of the drive shaft or the driven shaft, and the pair of engagement pieces are the pair of engagement pieces. The joint is characterized in that the contact preventing means is fixed to the drive shaft or the driven shaft by being disposed so as to face the cut surface of each other and the both end portions thereof being inserted through the pair of engagement holes, respectively. mechanism. The joint mechanism according to claim 1,
The contact preventing means is a joint mechanism which is an elastic member. The joint mechanism according to claim 1 or 2,
The contact preventing means is a joint mechanism formed of an insulating material. In the joint mechanism as described in any one of Claims 1-3 ,
A joint mechanism provided on the drive shaft, further comprising a spring member that urges the coupling from the drive shaft side toward the driven shaft side. A drive shaft;
A paper feed roller that has a driven shaft that is driven to rotate by the drive shaft, and that conveys a sheet by the rotation of the driven shaft;
A joint mechanism for connecting the drive shaft and the driven shaft;
With
A sheet feeding device in which the joint mechanism according to any one of claims 1 to 4 is used as the joint mechanism. A sheet feeding device for conveying a document sheet having a document image to a reading position;
A reading device that reads the original image at the reading position to obtain image data;
An image forming unit for forming an image based on the image data on a recording sheet;
With
An image forming apparatus using the sheet feeding device according to claim 5 as the sheet feeding device.

Images