JP4579179B2 - Paper feeder - Google Patents

Description

  The present invention relates to an improvement of a paper feeding device configured to feed paper one by one from a paper bundle stored in a stacked state and feed it to a target position.

  Conventionally, a sheet feeder 100 as shown in FIG. 8 is known. The paper feeding device 100 is configured to feed paper P1 one by one from a paper bundle P stored in a paper storage unit in an image forming apparatus such as a copying machine, a facsimile machine, or a printer. The sheet P1 is fed to an image forming unit in the image forming apparatus so that an image subjected to image forming processing (specifically, a toner image formed on the peripheral surface of the photosensitive drum) is transferred. It has become.

  The sheet feeding device 100 includes a pickup roller 101 whose circumferential surface is in contact with the upper surface downstream end (right side in FIG. 8) of the sheet bundle P placed on the urging plate 109 that is urged upward. A sheet feeding roller 102 disposed opposite to the downstream side of the pickup roller 101, and a retard roller 103 disposed opposite to each other so that the circumferential surfaces thereof are in contact with each other immediately below the sheet feeding roller 102. Has been. Each of these rollers 101, 102, and 103 is rotatable about an axis extending in a direction perpendicular to the paper conveyance direction (direction perpendicular to the paper surface of FIG. 8).

  Then, the uppermost sheet P1 fed out from the sheet bundle P by the pickup roller 101 is fed to and rotated by the sheet feeding roller 102 driven by the driving force transmitted from a predetermined driving source. It is conveyed toward the downstream side while being sandwiched by the driven retard roller 103.

  At the position where the paper feed roller 102 is provided, a plurality of upper guide members 104 arranged in a direction perpendicular to the paper transport direction are provided, while at the position where the retard roller 103 is provided. A plurality of lower guide members 105 facing the upper guide member 104 are provided below the upper guide member 104. The upper guide member 104 is formed with an arcuate bulging edge portion 104 a that extends upward with an edge on the downstream side of the paper feed roller 102 bulging outward. Is formed with an arcuate recessed edge 105a that is recessed so as to correspond to the arcuate shape of the upper guide member 104, and between the arcuate bulging edge 104a and the arcuate recessed edge 105a. A paper feed path 106 for guiding the paper P1 to the image forming unit is formed. Incidentally, the reason why the paper feed path 106 has a steep upward slope is that the image forming unit exists at a position directly above the paper feed device 100.

  A pair of transport rollers 107 that are driven and rotated around the axis is provided above the sheet feed path 106, and the sheet P 1 that has moved up the sheet feed path 106 by driving the sheet feed roller 102 is conveyed by the pair of transport rollers 107. The paper is fed toward the image forming unit while being sandwiched.

  The retard roller 103 is provided on the shaft to prevent the second sheet P1 from the upper left when the pick-up roller 101 simultaneously feeds two sheets P1 from the sheet bundle P. The driving force from the driving source is transmitted in the same direction as the paper feed roller 102 through the torque limiter 108.

  The torque limiter 108 is configured such that when an external force equal to or greater than a predetermined strength (reference external force) is applied in the circumferential direction of the retard roller 103, the retard roller 103 rotates around the axis while a force less than the reference external force is applied. Is a special driving force transmission means which prevents the retard roller 103 from rotating.

  The reference external force of the torque limiter 108 is slightly smaller than the frictional force between the paper P1 and the peripheral surface of the retard roller 103 when the paper P1 is pressed and sandwiched between the paper feed roller 102 and the retard roller 103. In addition, the frictional force between the paper P1 on the paper feed roller 102 side and the paper P1 on the retard roller 103 side in a state where the two papers P1 are sandwiched between the paper feed roller 102 and the retard roller 103. It is set large.

  Therefore, when only one uppermost sheet P1 (uppermost sheet P11) is fed out from the sheet bundle P by the driving rotation of the pickup roller 101 (FIG. 8A), the uppermost sheet P11 is fed. The paper passes through the nip portion N between the paper roller 102 and the retard roller 103 and is directed toward the conveying roller pair 107 via the paper feed path 106 by the driving force of the paper feed roller 102. At this time, the retard roller 103 is driven clockwise by the movement of the uppermost sheet P11 because the frictional force between the retard roller 103 and the uppermost sheet P11 is larger than the reference external force of the torque limiter 108. Rotate towards.

  On the other hand, if the two sheets P1 (the uppermost sheet P11 and the next sheet P12) are fed out from the sheet bundle P by driving the pickup roller 101 (FIG. 8B), the uppermost sheet P11 is In the same manner as when only one sheet is fed out, the sheet is conveyed toward the sheet feed path 106 by the driving rotation of the sheet feed roller 102 through the nip portion N between the sheet feed roller 102 and the retard roller 103. On the other hand, as shown in FIG. 8B, the next paper P12 is once sandwiched between the uppermost paper P11 and the retard roller 103. In this state, the next paper P12 and the uppermost paper are placed. Since the frictional force with P11 is smaller than the reference external force of the torque limiter 108 of the retard roller 103, the retard roller 103 does not rotate.

As such a sheet feeding device 100, for example, the one described in Patent Document 1 or Patent Document 2 is known.
JP 7-179237 A JP-A-7-206197

  By the way, in the conventional sheet feeder 100 as shown in FIG. 8, the sheet feed path 106 formed on the downstream side of the nip portion N between the sheet feed roller 102 and the retard roller 103 has an extremely steep slope. The route is set to go upward. For this reason, the uppermost sheet P11 that has passed through the nip portion N reaches the conveying roller pair 107 and is pulled upward by the driving rotation of the conveying roller pair 107.

  When the uppermost sheet P11 is pulled upward, a force is also applied to lift the sheet feeding roller 102 whose lower peripheral surface is in contact with the uppermost sheet P11. When such a force is repeatedly applied to the paper feed roller 102, the pressure applied to the paper feed roller 102 from the retard roller 103 when the uppermost paper P11 is passed through the nip portion N becomes weak.

  When the pressing force of the retard roller 103 against the paper feed roller 102 is weakened, the frictional force between the retard roller 103 and the paper P1 may be smaller than the reference external force as a result. In such a case, the retard roller Since 103 does not rotate, only the same portion of the peripheral surface of the retard roller 103 is brought into sliding contact with the paper P1, thereby causing a disadvantage that the peripheral surface of the retard roller 103 is unevenly worn.

  The present invention has been made in order to eliminate the conventional inconvenience, and provides a sheet feeding device capable of reliably preventing uneven wear of a retard roller while preventing two sheets from being fed. It is an object.

  According to the first aspect of the present invention, a paper feed roller that feeds paper by driving rotation from a paper tray in which a bundle of paper sheets composed of a plurality of stacked sheets is stored, and peripheral surfaces of the paper feed roller are in contact with each other. And a retard roller having a torque limiter disposed so as to be in contact with each other, wherein a nip portion for sandwiching a sheet is formed between the sheet feed roller and the retard roller. A paper feed path that guides conveyance of the sheet fed from the nip portion is formed on the downstream side of the section, and a guide that guides the sheet to the retard roller side from the tangential direction of the nip portion is formed in the sheet feed path. Means are provided.

  According to this configuration, when the uppermost sheet fed from the sheet bundle reaches the nip portion formed between the sheet feed roller and the retard roller, the sheet feed roller is nipped between the sheet feed roller and the retard roller. The sheet is fed toward a predetermined target location on the downstream side through the sheet feeding path by the driving rotation of the.

  The paper feed path is provided with guide means for guiding the paper to the retard roller side rather than the tangential direction of the nip part, so that the uppermost sheet fed to the paper feed path through the nip part is Since the sheet is oriented to the retard roller by the guide means (it is in a state of being wound slightly for a relatively long time), conventionally, the sheet is pulled upward with a steep gradient, so that the sheet feed roller is pulled upward. However, the pressing and clamping force against the paper at the nip portion is reduced, and thereby the retard roller does not rotate, and the peripheral surface of the retard roller is unevenly worn. Such inconvenience does not occur because the sheet is conveyed while being wound around the retard roller for a relatively long time.

  In addition, when two sheets (the top sheet and the next sheet) of the sheets are fed out simultaneously, the top sheet and the next sheet reach the nip portion between the feed roller and the retard roller at the same time. When the sheet feeding roller is lifted, the contact state of the next sheet with the peripheral surface of the retard roller becomes unstable, and the occurrence of inconvenience that the original two-sheet feeding blocking function is impaired is effectively prevented.

  According to a second aspect of the present invention, in the first aspect of the invention, the retard roller is disposed below the paper feed roller, and the paper feed path extends laterally from the nip portion; An upward path extending upward from a downstream end of the lateral path, and the guide means is configured to be configured so that the sheet led out from the nip portion is in sliding contact with the lateral path. It is characterized by comprising an upper wall surface.

  According to such a configuration, the sheet led out from the nip portion is intended to pass through the upward path while being in sliding contact with the upper wall surface of the lateral path as a guide unit that guides the sheet toward the retard roller rather than the tangential direction of the nip section. Since the sheet is fed to the position, a predetermined winding amount of the sheet around the retard roller is secured.

  Therefore, the rotation of the retard roller is ensured, and uneven wear of the retard roller is surely prevented, and even when two sheets are fed out from the sheet bundle, these two sheets are fed. In a state where the nip portion formed between the roller and the retard roller has been reached, the sheet next to the uppermost sheet is pressed against the retard roller by the uppermost sheet. For this reason, the next sheet is surely pressed and brought into contact with the retard roller, so that the function of not sending out the next sheet provided in the retard roller is surely performed.

  According to a third aspect of the present invention, in the second aspect of the present invention, a conveying roller on which an upper surface of a sheet is wound is provided at a continuous position between the lateral path and the upward path. To do.

  According to such a configuration, the sheet fed from the sheet bundle and fed to the sheet feeding path via the nip portion between the sheet feeding roller and the retard roller is fed to the target position through the horizontal path and the upward path. The upper surface is in contact with the peripheral surface of the conveyance roller, and the conveyance roller is rotated around the axis by following the movement of the sheet, so that the sheet is fed without damaging the surface side. It is transported more smoothly in the road.

  According to a fourth aspect of the present invention, in the first aspect of the invention, the retard roller is disposed below the paper feed roller, and the paper feed path extends laterally from the nip portion; A sheet conveyance guide member that has an upward path extending upward from the downstream end of the horizontal path and guides the conveyance of the sheet on the inner corner side between the horizontal path and the upward path. The paper transport guide member is a roller support rotatable around a fulcrum shaft extending in the paper width direction orthogonal to the paper transport direction, and the roller support at each end in the paper transport direction of the roller support. An upstream guide roller and a downstream guide roller provided rotatably around an axis parallel to the fulcrum shaft, and the guide means is the upstream roller.

  According to this configuration, the sheet fed from the sheet bundle and fed to the sheet feeding path through the nip portion between the sheet feeding roller and the retard roller is fed toward the target position through the horizontal path and the upward path. In doing so, the paper located in the upward path presses the downstream guide roller outward from the upward path, whereby the roller support rotates about the fulcrum axis.

  This rotation causes the upstream guide roller to enter the lateral path, so that the paper in the lateral path is pressed downward by the upstream guide roller. By this pressing, the paper in the lateral path is in a state in which a predetermined amount of wrapping around the peripheral surface of the retard roller is secured.

  As a result, the rotation of the retard roller is ensured, and uneven wear of the retard roller is surely prevented, and when two sheets (the uppermost sheet and the next sheet) are fed out simultaneously from the sheet bundle, the uppermost sheet The contact state of the next sheet sandwiched between the retard roller and the retard roller is very good, and the retard roller can reliably perform the function of preventing the next sheet from moving to the lateral path. Thus, it is possible to reliably prevent two sheets of paper from being fed.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the retard roller is pivotally supported via the torque limiter around a non-rotating axis that pivotally supports the retard roller. It is characterized by being.

  According to such a configuration, it is not necessary to provide a member such as a drive motor or a driving force transmission mechanism as compared with the case where the retard roller is driven and rotated as in the prior art, and the number of side parts is reduced, and thus the manufacturing cost is reduced. Contributes to the reduction of

  According to the first aspect of the present invention, since the paper feed path is provided with guide means for guiding the paper to the retard roller side with respect to the tangential direction of the nip portion, the paper feed path is provided via the nip portion. Since the uppermost sheet fed out is oriented to the retard roller by the guide means, the sheet can be conveyed in a state of being wound around the retard roller for a relatively long time. Therefore, the paper that has come out of the nip portion is moved upward with a steep gradient as in the conventional case, and the paper feeding roller is pulled upward by being pulled upward, so that the pressure holding force against the paper at the nip portion is reduced. Thus, it is possible to effectively prevent the disadvantage that the retard roller does not rotate and the peripheral surface of the retard roller is unevenly worn.

  In addition, when two sheets of paper are fed out simultaneously from the sheet bundle, when the uppermost paper and the next paper reach the nip portion between the paper feed roller and the retard roller at the same time, It is possible to effectively prevent the occurrence of inconvenience that the contact state of the sheet with the peripheral surface of the retard roller becomes unstable and the original two-sheet feeding prevention function is impaired.

  According to the second aspect of the present invention, the sheet led out from the nip portion is in an upward path while being in sliding contact with the upper wall surface of the lateral path as guide means for guiding the sheet to the retard roller side with respect to the tangential direction of the nip portion. The sheet is fed to the target position through this, and a predetermined amount of winding of the sheet around the retard roller is ensured. Therefore, the rotation of the retard roller is ensured, and uneven wear of the retard roller can be surely prevented. .

  Even when two sheets are fed out from the sheet bundle, the two sheets reach the nip formed between the sheet feeding roller and the retard roller, and the top sheet is Since the next sheet is pressed against the retard roller by the uppermost sheet, the next sheet is securely pressed against the retard roller, so that the retard roller feeds the next sheet. The original function of eliminating can be surely performed.

  According to the third aspect of the present invention, the sheet fed from the sheet bundle and fed to the sheet feeding path through the nip portion between the sheet feeding roller and the retard roller is fed to the target position through the horizontal path and the upward path. In this state, the upper surface is in contact with the peripheral surface of the conveyance roller, and the conveyance roller is rotated around the axis along with the movement of the sheet, so that the surface side of the sheet is damaged. The paper can be smoothly conveyed without such inconvenience.

  According to the fourth aspect of the present invention, the sheet fed from the sheet bundle and fed to the sheet feeding path through the nip portion between the sheet feeding roller and the retard roller passes through the lateral path and the upward path to the target position. At this time, the paper located in the upward path presses the downstream guide roller from the upward path toward the outside, and the roller support rotates around the fulcrum shaft. Therefore, the upstream guide roller enters the lateral path, and the sheet in the lateral path is pressed downward by the upstream guide roller. By this pressing, the sheet in the lateral path is in a state in which a predetermined amount of wrapping around the circumferential surface of the retard roller is ensured, so that the contact state of the sheet with the circumferential surface of the retard roller can be made extremely stable. .

  According to the fifth aspect of the present invention, the retard roller is pivotally supported via the torque limiter around the non-rotating shaft that concentrically supports the retard roller, so that the retard roller is driven as in the prior art. Compared with the case of rotating, there is no need to provide a member such as a drive motor or a driving force transmission mechanism, which can contribute to a reduction in the number of side parts and a reduction in manufacturing cost.

  FIG. 1 is an explanatory diagram of a side cross-sectional view showing an outline of an internal structure of an example of a printer 10 to which an embodiment of a paper feeding device 40 according to the present invention is applied. FIG. FIG. 1B shows a state where 31 is stored in the storage position T1, and FIG. 1B shows a state where the paper storage unit 31 is pulled out to the drawing position T2. In FIG. 1, the Y-Y direction is referred to as the front-rear direction, in particular, the -Y direction is referred to as the front, and the + Y direction is referred to as the rear.

  As shown in FIG. 1, the printer 10 stores sheets P1 to be subjected to printing processing, and also feeds out sheets P1 one by one from the stored bundle of sheets P1 (sheet bundle P) or manually feeds the sheets P1. A sheet cassette (sheet tray) 30 configured to be able to be transferred, an image forming unit 20 that performs an image transfer process on the sheet P1 supplied from the sheet cassette 30, and transfer by the image forming unit 20 A fixing unit 27 that performs a fixing process on the processed paper P <b> 1 is provided at a position above the partition plate 112 in the apparatus main body 11. The paper P1 subjected to the fixing process by the fixing unit 27 is discharged to a paper discharge tray 117 formed on the top of the apparatus main body 11.

  The image forming unit 20 performs a transfer process on the paper P1 based on image information transmitted from a computer or the like, and is provided so as to be rotatable around a drum core extending in the left-right direction (direction orthogonal to the paper surface of FIG. 1). A charger 22, an exposure device 23, a developing device 24, a transfer roller 25, and a cleaning device 26 are arranged in a clockwise direction from a position immediately above the photosensitive drum 21 along the peripheral surface of the photosensitive drum 21 thus formed. It is formed by being.

  The photosensitive drum 21 is for forming an electrostatic latent image and a toner image along the electrostatic latent image on the peripheral surface, and a smooth and tough amorphous silicon layer is laminated on the peripheral surface. It is suitable for forming these images.

  The charger 22 forms a uniform charge on the peripheral surface of the photosensitive drum 21 rotating clockwise around the drum center. In this embodiment, the photosensitive member is subjected to corona discharge from a wire. A corona discharge type that applies a charge to the peripheral surface of the drum 21 is employed. Instead, the peripheral surface of the photoconductive drum 21 rotates while being driven while being in contact with the peripheral surface of the photoconductive drum 21. You may employ | adopt the charging roller system which provides an electric charge to a surrounding surface.

  The exposure device 23 irradiates the peripheral surface of the rotating photosensitive drum 21 with laser light to which intensity is applied based on image data transmitted from an external device such as a computer, and the photosensitive drum 21 is thereby radiated. An electrostatic latent image is formed on the peripheral surface of the photosensitive drum 21 by erasing the electric charge in the portion where the laser light on the peripheral surface is checked.

  The developing device 24 supplies the toner in the developer to the peripheral surface of the photosensitive drum 21 to attach the toner to the portion where the electrostatic latent image is formed on the peripheral surface. A toner image is formed on the peripheral surface. In the present invention, a so-called two-component system composed of toner and carrier is used as the developer. The toner is a fine powder having a particle diameter of 6 to 12 μm in which additives such as a colorant, a charge control agent and wax are dispersed in a binder resin.

The carrier is magnetic particles having a particle size of 60 to 200 μm such as magnetite (Fe ₃ O ₄ ), and is used for charging the toner. The toner is a consumable that is appropriately replenished from the toner cartridge 241 to the developing device 24, whereas a predetermined amount of the carrier is loaded in the developing device 24 in advance, and is used without being consumed. In the present invention, the toner cartridge 241 is loaded with toner and a carrier (that is, a developer), and both the toner and the carrier are supplied to the developing device 24 at the same time.

  The transfer roller 25 transfers a positively charged toner image formed on the peripheral surface of the photosensitive drum 21 to the paper P1 with respect to the paper P1 sent to a position immediately below the photosensitive drum 21. A negative charge having a polarity opposite to that of the toner image is applied to the paper P1.

  Accordingly, the sheet P1 that has reached the position immediately below the photosensitive drum 21 is pressed and sandwiched between the transfer roller 25 and the photosensitive drum 21, and the toner image on the circumferential surface of the photosensitive drum 21 that is positively charged is negatively charged. It is peeled off toward the surface of P1, and a transfer process is performed.

  The cleaning device 26 is for removing the toner remaining on the peripheral surface of the photosensitive drum 21 after the transfer process to the paper P1 and cleaning it. The peripheral surface of the photosensitive drum 21 cleaned by the cleaning device 26 is again directed to the charger 22 for the next image forming process.

  The fixing unit 27 performs a fixing process by heating the toner image of the paper P1 that has been subjected to the transfer process in the image forming unit 20, and includes a heat roller 271 in which an energizing heating element such as a halogen lamp is mounted. And a pressure roller 272 having a peripheral surface opposed to the lower portion of the heat roller 271. Then, the paper P1 after the transfer process is composed of a heat roller 271 that is driven to rotate clockwise around the roller center and a pressure roller 272 that is driven to rotate counterclockwise around the roller center. By passing through the nip portion between them, the heat from the heat roller 271 is obtained and the fixing process is performed. The sheet P1 subjected to the fixing process is discharged to the discharge tray 117 through the discharge conveyance path 273.

  The paper cassette 30 includes a paper storage unit 31 for storing a paper bundle P that is detachably attached to the apparatus main body 11, and a paper feed guide unit 38 provided at the front end of the paper storage unit 31. And is configured.

  The paper feed guide unit 38 is erected at the front end of the paper storage unit 31. The sheet feeding guide unit 38 is supported by a front wall 381 that guides the sheet P1 fed from the sheet bundle P stored in the sheet storage unit 31 toward the image forming unit 20, and a top portion of the front wall 381. And a manual feed tray 382.

  In the apparatus main body 11, a transport roller pair 12 is provided at a position directly above the front wall 381 in a state where the paper cassette 30 is set at the storage position T1, and an upper portion of the transport roller pair 12 is provided. A sheet feeding conveyance path 13 toward the photosensitive drum 21 is provided, and a registration roller pair 14 is provided at a substantially intermediate position in the front-rear direction of the sheet feeding conveyance path 13 and is fed from the sheet feeding device 40. The paper P1 is fed to the nip portion between the photosensitive drum 21 and the transfer roller 25 through the transport roller pair 12, the paper feed transport path 13, and the registration roller pair 14.

  The manual feed tray 382 can be pulled forward from the top of the front wall 381. Then, by pulling out the manual feed tray 382 forward with the paper cassette 30 positioned at the storage position T1 (FIG. 1A), the paper P1 is manually fed along the drawn manual feed tray 382. Paper can be fed toward the registration roller pair 14.

  In the present embodiment, the sheet feeding device 40 according to the present invention extends across the lower portion of the partition plate 112 in front of the apparatus body 11 and the front wall 381 side of the sheet feeding guide portion 38 in the sheet cassette 30. Is formed.

  Prior to the description of the paper feeding device 40, first, the paper cassette 30 will be described in detail with reference to FIG. FIG. 2 is a perspective view showing an embodiment of the paper cassette 30. In FIG. 2, the XX direction is referred to as the left-right direction and the Y-Y direction is referred to as the front-rear direction. In particular, the -X direction is referred to as the left, the + X direction is referred to as the right, the -Y direction is referred to as the front, and the + Y direction is referred to as the rear.

  As shown in FIG. 2, the paper cassette 30 includes a paper storage unit 31 that stores the paper bundle P and a paper feed for guiding the paper P1 formed at the front end of the paper storage unit 31 to the image forming unit 20. And a guide unit 38. The sheet storage unit 31 includes an arc-shaped front plate 32 whose front surface is bulged outwardly (in front) in a plan view, and a lower edge portion on the back surface (rear surface) side of the arc-shaped front plate 32. And a pair of side plates 34 extending in the front-rear direction projecting upward from the left and right side portions of the bottom plate 33, and having an open top surface. It has a rectangular shallow box shape.

  A pair of guided projecting pieces 341 projecting in opposite directions are provided at appropriate positions of the side plates 34, while the pair of side plates 111 (FIG. 1B) of the apparatus main body 11 are provided. The guide grooves 111a extending in the front-rear direction corresponding to the guided protrusions 341 are respectively recessed, and the sheet storage portion 31 has the guided protrusions 341 in the guide grooves 111a (FIG. 1B). Between the storage position T1 (FIG. 1 (A)) stored in the apparatus main body 11 by forward and reverse movement while being guided, and the drawing position T2 (FIG. 1 (B)) protruding outward from the apparatus main body 11. The position can be changed with.

  The bottom plate 33 is provided with a longitudinally moving guide recess 331 extending in the longitudinal direction at a central position in the lateral direction on the upper surface side, and can be moved back and forth while being guided by the longitudinally guiding guide recess 331. A position regulating member 35 is provided. The front / rear position restricting member 35 is for restricting the rear end position of the sheet bundle P (FIG. 1) placed on the bottom plate 33, and a horizontal plate 351 that slides in the front / rear movement guide recess 331. And a vertical plate 352 erected from the rear end portion of the horizontal plate 351. Then, the vertical plate 352 can be moved in accordance with the paper size to be brought into contact with the rear end of the paper bundle P.

  In addition, the bottom plate 33 is provided with a pair of left and right movement guide recesses 332 at a front position on the upper surface thereof, and a pair of left and right movement guide recesses 332 that are movable in the left and right directions while being guided by the left and right movement guide recesses 332. A left-right position restricting member 36 is provided. These left and right position restricting members 36 are for restricting the left and right positions of the sheet bundle P (FIG. 1) placed on the bottom plate 33, and include a horizontal plate 361 that slides in the left and right motion guide recess 332. The horizontal plate 361 has a vertical plate 362 erected from opposite edges in the left-right direction. Then, the sheet bundle P can be held between the pair of vertical plates 362 by moving these left and right position regulating members 36 in the opposite direction by the same amount according to the sheet size.

  Accordingly, the sheet bundle P placed on the bottom plate 33 of the sheet storage unit 31 is sandwiched between the front / rear position restricting member 35 and the pair of left / right position restricting members 36 so that the front end is a vertical surface of the lower guide member 442 described later. In this state, the sheet is positioned in the sheet storage unit 31.

  Further, an urging plate 37 that urges the front half of the sheet bundle P placed in a state of not interfering with the left and right position regulating member 36 upward is provided at a position substantially in the front half of the bottom plate 33. Yes. The urging plate 37 is pivotally supported around a support shaft 371 (FIG. 1) extending in the left-right direction at the rear end side, and is urged upward by a coil spring 372 (FIG. 1). The uppermost sheet P1 of the sheet bundle P loaded in the sheet storage unit 31 is a pickup roller whose upper surface of the front end portion will be described later in a state where the sheet storage unit 31 is stored in the apparatus main body 11 (FIG. 1A). 41 abuts. Accordingly, the uppermost sheet P1 of the sheet bundle P is driven and rotated by the pickup roller 41, so that the image forming unit 20 passes through the nip N between the sheet feeding roller 42 and the retard roller 43, which will be described later, and the front wall 381. The paper is sequentially fed toward the front.

  FIG. 3 is a partially cutaway perspective view showing the first embodiment of the paper feeding device 40 according to the present invention. 4 is a cross-sectional view taken along the line I-I of the paper feeding device 40 shown in FIG. 3. FIG. 4A shows the paper bundle P with respect to the nip N between the paper feeding roller 42 and the retard roller 43. FIG. 4B shows a state in which two sheets P1 are fed out from the sheet bundle P with respect to the nip portion N between the paper feed roller 42 and the retard roller 43. FIG. Each is shown. 3 and 4 are the same as those in FIG. 2 (X is the left-right direction (-X: leftward, + X: rightward), Y is the front-rear direction (-Y: forward, + Y). : Back)).

  First, as shown in FIG. 3, the sheet cassette 30 faces the front end upper surface of the sheet bundle P stored in the sheet storage unit 31 in a state where the sheet cassette 30 is set at the storage position T <b> 1 (see FIG. 1A). The pickup roller 41 provided in the apparatus main body 11, the paper feed roller 42 provided on the paper cassette 30 side so as to face the pickup roller 41 in the front, and the paper feed roller 42 and the peripheral surfaces thereof at the lower part. A retard roller 43 provided on the side of the sheet cassette 30 in a state of being opposed to contact each other, and a sheet P1 from the nip portion N between the sheet feed roller 42 and the retard roller 43 toward the transport roller pair 12. And a paper feed path 45 formed in the guide member 44.

  The pickup roller 41, the paper feed roller 42, and the retard roller 43 are all formed of a so-called elastomer such as rubber or flexible synthetic resin material, and thereby the frictional force with the paper P1 is very large. Therefore, it is difficult to slip between the paper P1.

  The pickup roller 41 is externally fitted so as to be concentrically and integrally rotatable around a pickup roller shaft 411 installed between predetermined frames (not shown) so as to traverse the apparatus main body 11 in the left-right direction. The pickup roller 41 is driven to rotate counterclockwise by rotation around the axis of the pickup roller shaft 411 driven by a drive motor (not shown), whereby the sheet bundle with which the peripheral surface of the pickup roller 41 is in contact. The uppermost sheet P1 of P is fed out toward the nip N between the sheet feeding roller 42 and the retard roller 43.

  The paper feed roller 42 is fitted around the paper feed roller shaft 421 so as to be concentrically and integrally rotatable around a central portion of the paper feed roller shaft 421 provided between a pair of left and right frames (not shown). The paper feed roller 42 rotates integrally with the paper feed roller shaft 421 when the paper feed roller shaft 421 rotates counterclockwise around its axis by driving of a drive motor (not shown).

  The circumferential surface of the retard roller 43 is in contact with the peripheral surface of the paper feed roller 42 at a position directly below the paper feed roller 42. The retard roller 43 is externally fitted so as to be concentrically rotatable around the retard roller shaft 431 at the central portion of the retard roller shaft 431 installed and fixed between a pair of left and right frames (not shown). The retard roller shaft 431 is fixed to the frame (not shown) so as not to rotate about the axis.

  In the retard roller 43, a torque limiter 432 (FIG. 4) interposed between the retard roller 43 and the retard roller shaft 431 is provided. Incidentally, the torque limiter 432 is interposed between two objects provided close to each other so as to be able to rotate concentrically, and when one or more torque is applied to one object, This is a type of clutch device that is configured such that one object and the other object do not rotate relative to each other even when a torque less than a predetermined torque is applied to the other object while the other object rotates relative to the other object.

  When the torque limiter 432 is applied to the peripheral surface of the retard roller 43 to a force greater than a predetermined force (reference external force) in the circumferential direction, the retard roller 43 rotates while a force less than the reference external force is applied. In such a case, it is designed not to rotate.

  Specifically, the reference external force is set to be smaller than the frictional force between the paper P1 and the peripheral surface of the retard roller 43 and larger than the frictional force between the superimposed papers P1. By setting the reference external force in this manner, uneven wear of the peripheral surface of the paper feed roller 42 is suppressed, and when the two sheets P1 are fed out simultaneously by the pickup roller 41, the lower sheet P1 is fed. In this state, only the upper sheet P1 is fed. Details of this operation will be described later.

  The paper feed roller 42 and the retard roller 43 are mounted on a guide member 44 provided at a position behind the front wall 381 in the paper cassette 30. The guide member 44 includes an upper guide member 441 through which the sheet feed roller shaft 421 is mounted and a lower guide member 442 through which the retard roller shaft 431 is mounted. The upper guide member 441 is provided symmetrically with respect to the paper feed roller 42. Similarly, the lower guide member 442 is provided symmetrically with respect to the retard roller 43.

  As shown in FIG. 4, the upper guide member 441 has a substantially rectangular shape in a side view, and a paper feed roller shaft 421 passes through a lower part of the rear thereof, whereby a part of the paper feed roller 42 is part of the upper guide member 441. It protrudes downward from the lower end of the.

  An upper inclined edge 441a is formed at the corner portion of the rear end lower portion of the upper guide member 441 so as to incline backward from a position almost directly below the paper feed roller shaft 421, and the upper inclined edge 441a. A lower end surface (upper wall surface of the lateral path 451) 441b is formed extending substantially horizontally from the front end portion to the front of the front wall 381, and is parallel to the front wall 381 upward from the lower end surface 441b. A front end surface 441c extending in the direction is formed.

  A convex arcuate sliding contact portion (guide means) 443 having an arc shape is formed at a position where the lower end surface 441b and the front end surface 441c of the upper guide member 441 intersect, and the sheet feeding roller 42 and the retard roller 43 are formed. The sheet P1 that has passed through the nip portion N and reaches the conveying roller pair 12 is pulled up by driving the conveying roller pair 12 so that the upper surface thereof is in sliding contact with the convex arcuate sliding contact portion 443.

  As shown in FIG. 4, the lower guide member 442 has a substantially rectangular shape when viewed from the side, and a retard roller shaft 431 passes through the upper rear portion of the lower guide member 442 so that a part of the retard roller 43 is at the upper end of the lower guide member 442. It protrudes upward from. In this state, the peripheral surface of the retard roller 43 is in contact with the peripheral surface of the paper feed roller 42.

  A lower inclined edge 442a is formed at the corner of the upper rear end of the lower guide member 442 so as to incline downward from the position almost directly above the retard roller shaft 431. The lower inclined edge 442a An upper end surface 442b that is parallel to the lower end surface 441b of the upper guide member 441 is formed from the front end portion to the front, and the center of curvature is a convex circle of the upper guide member 441 between the upper end surface 442b and the front wall 381. A concave arc-shaped portion 444 that is concentric with the center of curvature of the arc-shaped sliding contact portion 443 and has a radius of curvature larger than that of the convex arc-shaped sliding contact portion 443 is formed.

  The sheet feeding path 45 is for conveying the sheet P1 that has passed through the nip N between the sheet feeding roller 42 and the retard roller 43 toward the pair of conveying rollers 12, and includes an upper guide member 441 and a lower guide. It is formed between the member 442 and between the upper guide member 441 and the front wall 381. The sheet feeding path 45 is directed upward from a lateral path 451 formed between the lower end surface 441b of the upper guide member 441 and the upper end surface 442b of the lower guide member 442, and the downstream end (front end) of the lateral path 451. And an upward path 452 formed between the front end surface 441c of the upper guide member 441 and the front wall 381.

  Next, based on FIG. 4A, a nip tangent line L extending forward from a nip portion N formed between the paper feed roller 42 and the retard roller 43 (a dashed line in FIG. 4A). Will be explained. In the present invention, the nip tangent L is orthogonal to a straight line connecting the center of the paper feed roller 42 (ie, the axis of the paper feed roller shaft 421) and the center of the retard roller 43 (ie, the axis of the retard roller shaft 431). In this way, the straight line extends forward from the nip portion N, and the sheet P1 fed out from the sheet bundle P toward the nip portion N moves along the nip tangent L.

  In the present embodiment, the sheet P1 is directed toward the retard roller 43 with respect to the tangential direction of the retard roller 43 at the nip portion N (that is, the nip tangent line L starting from the nip portion N is directed forward). Is provided with a convex arcuate sliding contact portion 443 which is a part of the lower end surface 441b as guide means according to the present invention, and the sheet P1 is pulled upward by driving the conveying roller pair 12 In this state, the sheet P1 positioned between the nip portion N and the retard roller 43 is positioned below the nip tangent line L.

  By doing so, the sheet P1 that is pulled by the conveying roller pair 12 and passes through the sheet feeding path 45 can be slightly wound around the retard roller 43, whereby the sheet P1 is wound on the sheet feeding roller 42. The sheet P1 can be prevented from being lifted upward, and so-called two-sheet feeding in which two sheets P1 are simultaneously fed out from the sheet bundle P can be prevented.

  Hereinafter, the operation of the sheet feeding device 40 capable of preventing the two-sheet feeding will be described with reference to FIG. FIG. 5 is an explanatory diagram for explaining the operation of the paper feeding device 40. FIG. 5A shows a case where the uppermost sheet P1 is fed out from the sheet bundle P. FIG. FIG. 5D shows a case where the uppermost sheet P1 (uppermost sheet P11) and the next sheet P1 (next sheet P12) are fed out from the sheet bundle P substantially at the same time. 5B shows a state in which the next paper P12 reaches the nip N immediately after the uppermost paper P11 passes through the nip N between the paper feed roller 42 and the retard roller 43, and FIG. FIG. 5D shows a state in which the next sheet P12 bites into the nip portion N, and FIG. 5D shows a state in which the uppermost sheet P11 has reached the conveyance roller pair 12. In addition, the direction display by Y in FIG. 5 is the same as that in FIG. 4 (−Y: forward, + Y: backward).

  First, when only one uppermost sheet P1 is fed from the sheet bundle P by driving the pickup roller 41, the fed sheet P1 is fed by the sheet feeding roller 42 as shown in FIG. Guided by the drive rotation around the roller shaft 421, it passes through the nip portion N between the paper feed roller 42 and the retard roller 43, passes through the paper feed path 45, and is sandwiched between the transport roller pair 12, and the transport roller pair 12. It will be in the state pulled up by drive rotation of.

  In this state, since the frictional force between the sheet bundle P and the peripheral surface of the retard roller 43 is larger than the reference external force of the torque limiter 432, when the sheet P1 moves in the nip portion N, the retard roller 43 Against the resistance of the torque limiter 432, it is rotated clockwise around the retard roller shaft 431 along with this movement. Therefore, when the retard roller 43 does not rotate, there is a disadvantage that the peripheral surface of the retard roller 43 is unevenly worn. However, when the retard roller 43 rotates in accordance with the movement of the paper P1, the retard roller 43 is unbalanced. Wear is effectively prevented.

  Further, as described above, the sheet P1 between the nip portion N and the convex arcuate sliding contact portion 443 is positioned lower than the nip tangent L (that is, the gradient of the sheet P1 is greater than the gradient of the nip tangent L). Therefore, the sheet P1 is tensioned in the sheet feed path 45 by being pulled by the conveying roller pair 12, and is slightly wound around the retard roller 43. By reliably contacting the peripheral surface of the retard roller 43, the occurrence of inconvenience such as slippage of the paper P1 with respect to the retard roller 43 is reliably prevented.

  Next, as shown in FIG. 5B, when two sheets P1 are fed out from the sheet bundle P almost simultaneously by driving the pickup roller 41 (in the example shown in FIG. 5B, the topmost position). First, the uppermost sheet P11 is fed to the second sheet P1 (next sheet P12) from the uppermost position after a slight time lag after the sheet P1 (uppermost sheet P11) is unwound. When the paper reaches the nip portion N between the roller 42 and the retard roller 43 and slightly passes through the nip portion N, the next sheet P12 reaches the nip portion N.

  The process until the next sheet P12 reaches the nip portion N is the same as in the case of feeding one sheet shown in FIG. 5A, and the retard roller 43 rotates counterclockwise around the sheet feed roller shaft 421. Rotate around the retard roller shaft 431 and rotate clockwise around the paper feed roller 42 rotating toward

  Next, when the next paper P12 reaches the nip portion N, the next paper P12 reaches the nip portion N formed slightly between the paper feed roller 42 and the retard roller 43 due to inertia, as shown in FIG. The biting state (the biting state is exaggerated in FIG. 5C) is pressed and held between the uppermost sheet P11 and the retard roller 43.

  In this state, the driving rotation of the paper feed roller 42 around the paper feed roller shaft 421 in the counterclockwise direction is transmitted to the retard roller 43 via the uppermost paper P11 and the next paper P12. Since the reference external force 432 is set to be larger than the frictional force between the uppermost sheet P11 and the next sheet P12, the retard roller 43 does not rotate. As a result, only the uppermost sheet P11 is fed at the nip portion N. It moves while slipping (sliding) with respect to the next paper P12 in accordance with the driving rotation of the paper roller 42. Accordingly, the uppermost sheet P11 and the next sheet P12 are simultaneously fed from the nip portion N toward the sheet feeding path 45, that is, two sheets are reliably prevented from being fed.

  The uppermost sheet P11 led out from the nip portion N to the lateral path 451 of the paper feed path 45 is guided upward by the concave arcuate part 444 of the lower guide member 442 and passes through the upward path 452 to convey the roller pair 12. Thereafter, as shown in FIG. 5D, the paper is fed toward the image forming unit 20 in a state where it is pulled upward by the conveying roller pair 12.

  In this state, since the sheet P1 existing between the nip portion N and the convex arcuate sliding contact portion 443 is set lower than the nip tangent line L as described above, the uppermost sheet P11 is conveyed. By being pulled by the roller pair 12, the tension in the paper feed path 45 is slightly applied, but the paper is wound around the retard roller 43 via the next paper P 12, and this causes the next paper P 12 to contact the circumferential surface of the retard roller 43. The contact state is ensured. Accordingly, inadequate contact of the next paper P12 with the retard roller 43 causes a disadvantage that the next paper P12 is fed into the paper feed path 45 along with the uppermost paper P11. Effectively prevented.

  As described above in detail, the paper feeding device 40 according to the present invention has the pickup roller 41 that feeds the paper P1 one by one from the paper cassette 30 in which the paper bundle P made up of a plurality of paper P1 in the stacked state is stored. The sheet feeding roller 42 that is driven to rotate to feed the sheet P1 that is disposed opposite to the downstream side of the pickup roller 41, and the lower surface of the sheet feeding roller 42 so that the peripheral surfaces thereof are in contact with each other. In addition, since the retard roller 43 having the torque limiter 432 is provided, and the nip portion N that sandwiches the paper P1 is formed between the paper feed roller 42 and the retard roller 43, the rotation of the pickup roller 41 is driven. The uppermost sheet P11 fed out from the sheet bundle P by the sheet reaches the nip portion N formed between the pickup roller 41 and the sheet feeding roller 42. That when, is fed toward the image forming unit 20 by the driving rotation of the paper feed roller 42 while being nipped by the feed roller 42 and the retard roller 43.

  A paper feed path 45 is formed on the downstream side of the nip portion N to guide the conveyance of the uppermost sheet P11 fed from the nip portion N. Guide means for guiding to the retard roller side with respect to the tangential direction of the nip portion (in the first embodiment, the convex arcuate sliding contact portion 443 provided in the upper guide member 441, and in the second embodiment provided in the upper guide member 441). In the third embodiment, since the rear guide roller 472 provided on the paper transport guide member 47 is provided, the uppermost paper P11 sent to the lateral path 451 through the nip portion N is As in the prior art, the sheet feed roller 42 is lifted upward by being pulled upward by the conveying roller pair 12 on the downstream side of the nip portion N with a steep gradient, and thus the nip. Pressing clamping force against the sheet P1 at the N can be reliably prevented the occurrence of inconvenience such as decrease.

  Therefore, when two sheets (the uppermost sheet P11 and the next sheet P12) of the sheet bundle P are simultaneously fed out from the sheet bundle P, the uppermost sheet P11 and the next sheet P12 are nipped between the sheet feeding roller 42 and the retard roller 43. When the sheet N reaches the part N at the same time, the feeding state of the next sheet P12 with respect to the peripheral surface of the retard roller 43 becomes unstable due to the lifting of the sheet feed roller 42, and the next sheet P12 is prevented from being fed by stopping the retard roller 43 from being driven. Therefore, it is possible to reliably prevent the so-called two-sheet feeding, in which two sheets of paper P1 are simultaneously fed to the target location.

  The paper feed path 45 includes an upward path 452 extending so as to extend upward from the downstream end of the lateral path 451. In particular, in the first embodiment, the lateral path 451 and the upward path 452 are provided. A convex arcuate sliding contact portion 443 having an arc shape in which the upper surface of the paper P1 is in sliding contact is formed at the joining position with the uppermost paper P11. The upper surface of the uppermost sheet P11 is slid with respect to the convex arcuate sliding contact portion 443 and smoothly fed out while being pulled upward by the driving of, and wound around the retard roller 43 of the uppermost sheet P11. The condition is stable.

  Therefore, even if two sheets P1 are fed out from the sheet bundle P by driving the pickup roller 41, the two sheets P1 reach the nip portion N formed between the sheet feeding roller 42 and the retard roller 43. In this state, since the next paper P12 which is the next paper P1 of the top paper P11 is pressed against the retard roller 43 by the top paper P11, the next paper P12 is surely pressed against the retard roller 43. This makes it possible to reliably perform the function of preventing the next paper P12 from the retard roller 43 from being sent out.

  In addition, the retard roller 43 is pivotally supported around the retard roller shaft 431 via a torque limiter 432 interposed between the retard roller 43 and the retard roller shaft 431, so that the retard roller 43 is retarded as in the prior art. Compared with the case where the roller 43 is driven and rotated, it is not necessary to provide a member such as a drive motor or a driving force transmission mechanism, which can contribute to a reduction in the number of side parts and a reduction in manufacturing cost.

  FIG. 6 is an explanatory view in a side view showing a sheet feeding device 40 ′ according to the second embodiment of the present invention. In FIG. 6, the direction display by Y is the same as in FIG. 1 (−Y: forward, + Y: backward).

  In the sheet feeding device 40 ′ according to the second embodiment, the convex arcuate sliding contact portion 443 described above is formed at the corner portion of the lower front portion of the upper guide member 441 at the boundary between the lateral path 451 and the upward path 452 in the sheet feeding path 45. Instead of this, a conveyance roller 46 is provided. The transport roller 46 is rotatably supported around a transport roller shaft 461 that passes through the upper guide member 441, and a part of the peripheral surface thereof faces the concave arcuate portion 444 of the lower guide member 442. Other configurations are the same as those of the paper feeding device 40 of the first embodiment.

  According to the sheet feeding device 40 ′ of the second embodiment, the sheet is fed from the sheet bundle P by driving the pickup roller 41, and is fed to the sheet feeding path 45 through the nip portion N between the sheet feeding roller 42 and the retard roller 43. When the sheet P1 passes through the horizontal path 451 and the upward path 452 and the leading end is nipped by the transport roller pair 12 and pulled upward, the upper surface thereof is in contact with the peripheral surface of the transport roller 46. As a result, the transport roller 46 is rotated around the transport roller shaft 461 following the movement of the paper P1, so that the paper P1 is transported more smoothly in the paper feed path 45 without damaging the surface side.

  FIG. 7 is an explanatory view in a side view showing a paper feeding device 40 ″ according to the third embodiment of the present invention. FIG. 7A shows that the paper transport guide member 47 is set to a paper non-pressing posture U1. 7B shows a state in which the paper transport guide member 47 is set to the paper pressing posture U2. In FIG. 7, the direction display by Y is the same as in the case of FIG. Y: forward, + Y: backward).

  The sheet feeding device 40 ″ of the third embodiment is premised on the provision of the pickup roller 41, the sheet feeding roller 42, the retard roller 43, the guide member 44, and the sheet feeding path 45, and further includes a sheet conveying guide member. 47 is added.

  The sheet conveyance guide member 47 is disposed obliquely at a corner in front of the lower portion of the upper guide member 441 so as to face the concave arcuate portion 444 of the lower guide member 442. The sheet conveying guide member 47 includes a swing plate (roller support) 471 disposed forward and swinging about a fulcrum shaft 474 that is penetrated by the upper guide member 441, and the swing plate. A rear guide roller (guide means) 472 rotatably supported around the rear shaft 475 on the rear side of the 471, and a front guide roller rotatably supported about the front shaft 476 on the front side of the swing plate 471. 473.

  The fulcrum shaft 474 is penetrated to a position slightly rearward from the center position in the front-rear direction of the swing plate 471, so that the front portion of the paper transport guide member 47 is heavier than the rear portion of the fulcrum shaft 474. Yes. Therefore, the sheet conveyance guide member 47 is gravity-driven so as to be directed clockwise around the fulcrum shaft 474, and is normally prevented from rotating by a stopper (not shown). As shown in FIG. 7A, the surface is set to a sheet non-pressing posture U1 slightly immersed in the lateral path 451.

  The front guide roller 473 has a portion behind the front shaft 476 that is substantially immersed in the upward path 452. Accordingly, in a state where the sheet P1 is lifted up the upward path 452 and pulled upward by the conveying roller pair 12, the front guide roller 473 is pressed rearward from the tension of the sheet P1 ascending the upward path 452. As shown in FIG. 7B, the sheet conveying guide member 47 is rotated counterclockwise around the fulcrum shaft 474, and as a result, the peripheral surface of the rear guide roller 472 is immersed in the lateral path 451 in a considerable amount. The posture is set to a paper pressing posture U2 in which the paper P1 in the horizontal path 451 bids downward.

  According to the sheet feeding device 40 ″ of the third embodiment configured as described above, the sheet is fed from the sheet bundle P by driving the pickup roller 41 and fed through the nip portion N between the sheet feeding roller 42 and the retard roller 43. As shown in FIG. 7A, the sheet P1 sent to the sheet path 45 reaches the conveying roller pair 12 through the horizontal path 451 and the upward path 452, and moves upward by the driving rotation of the conveying roller pair 12. At this time, the sheet P1 positioned in the upward path 452 presses the front guide roller 473 rearward, whereby the swing plate 471 rotates counterclockwise around the fulcrum shaft 474. Rotate in the direction.

  Due to this rotation, the rear guide roller 472 enters the horizontal path 451, so that the paper P <b> 1 in the horizontal path 451 is pressed downward by the rear guide roller 472. By this pressing, the sheet P1 in the lateral path 451 is positioned below the nip tangent L in the lateral path 451 by the lowering of the rear guide roller 472 as a guide means, and is wound around the circumferential surface of the retard roller 43 Therefore, the contact state of the paper P1 with the peripheral surface of the retard roller 43 can be made extremely stable.

  Accordingly, when two sheets P1 (the top sheet P11 and the next sheet P12) are simultaneously fed out from the sheet bundle P, the next sheet P12 held between the top sheet P11 and the retard roller 43 is applied to the retard roller 43. The contact state becomes extremely good, and the retard roller 43 can reliably perform the function of preventing the next paper P12 from moving to the lateral path 451, thereby further reliably feeding the two sheets of the paper P1. Can be blocked.

  Further, according to the sheet feeding device 40 ″ of the third embodiment, only when the sheet P1 is sent out to the sheet feeding path 45, the sheet P1 is pulled by the pair of conveying rollers 12 so as to reach the sheet conveying guide member 47. Torque in the counterclockwise direction is applied around the fulcrum shaft 474 via the front guide roller 473, whereby the paper transport guide member 47 swings. Thereafter, as shown in FIG. 7B, the paper P1 There is also an advantage that can be transported in the shortest distance in the paper feed path 45.

  The present invention is not limited to the above embodiment, and includes the following contents.

  (1) In the above embodiment, the printer 10 has been described as an example of the image forming apparatus to which the paper feeding devices 40, 40 ′, and 40 ″ are applied. However, in the present invention, the image forming apparatus is the printer 10. The present invention is not limited to this, and can be applied to a copying machine and a facsimile machine.

  (2) In the above embodiment, the paper cassette 30 for storing the paper P1 to be transferred is used as the paper tray. However, the present invention is limited to the paper cassette 30 being the paper tray. Instead, it may be a document tray for feeding a document to a document reading device in a copying machine or a facsimile machine.

  (3) In the above embodiment, the retard roller 43 is pivotally supported by the retard roller shaft 431 so as to be freely rotatable via the torque limiter 432. Instead of this, the driving force of a predetermined drive motor is The retard roller 43 may be transmitted to the retard roller 43 via the retard roller shaft 431 and the torque limiter 432 so that the retard roller 43 is driven and rotated so that the paper P1 is directed in the direction opposite to the feeding direction. In this way, when two sheets P1 are simultaneously fed out by the driving rotation of the pickup roller 41, the next sheet P1 of the uppermost sheet P1 is positively reversed in the feeding direction by the driving rotation of the retard roller 43. Since the sheet is pushed back in the direction, feeding of two sheets can be prevented more reliably.

  (4) In the first embodiment described above, the convex arcuate sliding contact portion 443 of the upper guide member 441 is employed as a guide means for winding the paper P1 around the retard roller 43 with a predetermined winding amount. Instead of this, the lower end surface 441b of the upper guide member 441 (that is, the upper wall surface of the lateral path 451) itself is set so as to be positioned below the nip tangent L from the nip portion N toward the lower guide member 442. Or a lower end surface 441b is formed with a bulging portion bulging a part of the lower end surface 441b, and the bottom surface of the bulging portion is set to be positioned below the nip tangent line L. Also good.

  When the lower end surface 441b of the upper guide member 441 is set so as to be positioned below the nip tangent line L from the nip portion N toward the lower guide member 442, the lower end surface 441b itself relates to the present invention. In the case where a bulging portion is formed on the lower end surface 441b of the upper guide member 441, and a portion of the bulging portion is bulged downward, this bulging portion is referred to as the guiding means according to the present invention. Become.

  Incidentally, the convex arcuate sliding contact portion 443 in the first embodiment is a category of the upper wall surface (lower end surface 441b) of the lateral path 451 set so that the paper P1 led out from the nip portion N according to the present invention is in sliding contact. Is included.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side cross-sectional view illustrating an outline of an internal structure of an example of a printer to which an embodiment of a paper feeding device according to the present invention is applied, and (A) is a state in which a paper storage unit is stored in a storage position. , (B) respectively show a state where the paper storage unit is pulled out to the pull-out position. It is a perspective view which shows one Embodiment of a paper cassette. 1 is a partially cutaway perspective view showing a first embodiment of a paper feeder according to the present invention. FIG. 4 is a cross-sectional view taken along a line II of the paper feeding device shown in FIG. 3, in which (A) shows a state in which one sheet is fed from a sheet bundle to a nip portion between a paper feeding roller and a retard roller; ) Shows a state in which two sheets are fed out from the sheet bundle to the nip portion between the sheet feeding roller and the retard roller. FIG. 6 is an explanatory diagram for explaining the operation of the sheet feeding device, in which (A) shows the top sheet from the sheet bundle, and (B) to (D) show the top sheet from the sheet bundle. The case where the first sheet and the next sheet are fed out substantially simultaneously is shown. It is explanatory drawing of the side view which shows the paper feeder of 2nd Embodiment which concerns on this invention. It is explanatory drawing of the side view which shows the paper feeder of 3rd Embodiment which concerns on this invention. It is explanatory drawing of the side view for demonstrating the conventional paper feeding apparatus, (A) is the state in which only the top sheet was drawn out from the sheet bundle by the drive rotation of the pickup roller, (B), 2 shows a state in which two sheets are fed out from the sheet bundle P by driving the pickup roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Printer 11 Apparatus main body 111 Side plate 111a Guide groove 112 Partition plate 117 Paper discharge tray 12 Carrying roller pair 13 Paper feed conveyance path 14 Registration roller pair 20 Image forming unit 21 Photosensitive drum 22 Charger 23 Exposure device 24 Developing device 241 Toner cartridge 25 Transfer roller 26 Cleaning device 27 Fixing section 271 Heat roller 272 Pressure roller 273 Paper delivery path 30 Paper cassette (paper tray)
31 Paper storage portion 32 Arc-shaped front plate 33 Bottom plate 331 Front / rear motion guide recess 332 Left / right motion guide recess 34 Side plate 341 Guided protrusion 35 Front / rear position restriction member 351 Horizontal plate 352 Vertical plate 36 Left / right position restriction member 361 Horizontal plate 362 Vertical plate 37 Energizing plate 371 Support shaft 372 Coil spring 38 Paper feed guide portion 381 Front wall 382 Manual feed tray 40 Paper feed device 41 Pickup roller 411 Pickup roller shaft 42 Paper feed roller 421 Paper feed roller shaft 43 Retard roller 431 Retard roller shaft 432 Torque limiter 44 Guide member 441 Upper guide member 441a Upper inclined edge 441b Lower end surface (upper wall surface of lateral path)
441c Front end surface 442 Lower guide member 442a Lower inclined edge 442b Upper end surface 443 Convex arcuate sliding contact portion (guide means)
444 Concave arc-shaped portion 45 Paper feed path 451 Lateral path 452 Upward path 46 Conveyance roller (guide means)
461 Transport roller shaft 47 Paper transport guide member 471 Swing plate (roller support)
472 Back guide roller (guide means)
473 Front guide roller 474 Support shaft 475 Back shaft 476 Front shaft N Nip portion P Paper bundle P1 Paper P11 Topmost paper P12 Next paper T1 Storage position T2 Pull-out position U1 Paper non-pressing posture U2 Paper pressing posture

Claims (5)

A paper feed roller that feeds paper by driving rotation from a paper tray in which a stack of paper sheets made up of a plurality of stacked sheets is stored, and is disposed so as to face each other so that the peripheral surfaces thereof are in contact with each other. In a paper feed device comprising a retard roller having a torque limiter, wherein a nip portion is formed between the paper feed roller and the retard roller to sandwich paper.
A paper feed path is formed on the downstream side of the nip portion to guide the conveyance of the sheet fed from the nip portion,
The sheet feeding device, wherein the sheet feeding path is provided with guide means for guiding the sheet to the retard roller side from the tangential direction of the nip portion.   The retard roller is disposed below the paper feed roller, and the paper feed path extends from the nip portion in a lateral direction and extends upward from a downstream end of the lateral path. 2. The guide path according to claim 1, wherein the guide means is configured by an upper wall surface of the lateral path set so that the sheet led out from the nip portion is in sliding contact. Paper feeder.   The sheet feeding device according to claim 2, wherein a conveyance roller around which an upper surface of the sheet is wound is provided at a continuous position between the lateral path and the upward path. The retard roller is disposed below the paper feed roller, and the paper feed path extends from the nip portion in the lateral direction and extends upward from the downstream end of the lateral path. A paper transport guide member that guides the transport of the paper is provided on the inner corner side between the horizontal path and the upward path,
The paper transport guide member is rotatable about a fulcrum shaft extending in the paper width direction perpendicular to the paper transport direction, and parallel to the fulcrum shaft at each end of the roller support in the paper transport direction. The sheet feeding device according to claim 1, further comprising an upstream guide roller and a downstream guide roller provided so as to be rotatable around a central axis, wherein the guide means is the upstream roller.   5. The sheet feeding device according to claim 1, wherein the retard roller is pivotally supported via the torque limiter around a non-rotating axis that pivotally supports the retard roller. .

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