JP2007070090A - Sheet supply device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable adjustment of paper feeding performance without replacing a paper feeding roller in a sheet supply device. <P>SOLUTION: A crescentic opening part 68A of a shaft hole 68 of the paper feeding roller 54 is externally inserted into a shaft 57 rotatably supported above a paper placement plate part 53. A high friction part 64 made of rubber having a friction coefficient larger than that of recording paper 52 is provided on the peripheral face of the paper feeding roller 54, and slip parts 65a, 65b having a friction coefficient smaller than that of the recording paper 52 is provided in the circumferentially front and back sides of the high friction member 64. Dimension of a step part 64a on the border of the high friction part 64 and the slip part 65a is set smaller than that of a step part 64b on the border of the high friction part 64 and the slip part 65b. In both axial end parts of the opening part 68A, recessed parts 69 capable of being engaged with pins 57a of the shaft 57 are formed, and the paper feeding roller 54 can be reversely fitted backwards and forwards in the circumferential direction. Due to the selection of the fitting direction of the paper feeding roller 54, the sheet supply device can be adjusted to have an appropriate paper feeding function. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet feeding apparatus that sequentially feeds sheets stacked in a sheet feeding tray by rotation of a sheet feeding roller, and an image forming apparatus including the sheet feeding apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a sheet supply device for sequentially feeding sheets such as sheets stacked in a sheet feeding tray is provided. This sheet supply apparatus is provided with a paper feed roller that feeds stacked sheets from the top by rotation. A separation member is pressed against the lower portion of the sheet feed roller, and when the sheet is sent out, the sheet is rolled at the pressure contact portion between the sheet feed roller and the separation member.

  In this sheet supply apparatus, when the sheets stacked in the sheet feeding tray are sent out, the second and subsequent sheets are easily conveyed along with the uppermost sheet, and the sheets are likely to be double-fed.

For this reason, a paper feeding device is disclosed in which a conveying unit having a large coefficient of friction with a sheet is provided on the outer peripheral surface of the sheet feeding roller, and a slip unit having a small coefficient of friction with the sheet is provided at the rotation leading portion of the conveying unit. (For example, refer to Patent Document 1). By feeding out the stacked sheets by the rotation of the slip portion of the rotation leading portion and the conveying portion inside the rotation portion, the sheets can be separated and fed even if the set position of the leading edge of the sheet is shifted.
Japanese Patent Laid-Open No. 2002-87608

  In the paper feeding device described in Patent Document 1, the level difference formed at the boundary between the slip part and the conveyance part greatly influences the paper feeding performance, and the paper feeding performance greatly changes as the level difference changes. As a result of investigations by the inventors, when the level difference is large, the level difference makes it easy to feed out the paper (the tendency to convey becomes large), and when the level difference is small, the stacked paper becomes easy to be rolled (the tendency to roll up becomes large). In recent years, there are various types of recording media such as paper, and there are recording media that are difficult to transport and recording media that are difficult to roll, and it is required to change the paper feeding performance depending on the type of recording medium. However, to change the paper feed performance, it is necessary to replace the paper feed roller.

  SUMMARY An advantage of some aspects of the invention is that it provides a sheet supply device and an image forming apparatus that do not require replacement of a paper feed roller and can set paper feed performance corresponding to the type of sheet. Objective.

  In order to solve the above-described problems, a sheet feeding apparatus according to the first aspect of the present invention is a half-moon shaped sheet that is detachably mounted on a rotating shaft and rotates to feed sheets stacked on a sheet stacking unit. A paper feed roller having a high friction portion having a large friction coefficient with the sheet on a peripheral surface of the paper feed roller, and a sheet having a higher end than the high friction portion at a circumferential end of the paper feed roller. A friction coefficient is small, a low friction part having a smaller diameter than the outer diameter of the high friction part is provided, and the step difference between the low friction part and the high friction part is different between before and after the circumferential direction of the paper feed roller. It is a feature.

  According to the first aspect of the present invention, the half-moon-shaped paper feed roller is detachably mounted on the rotating shaft, and the high friction portion on the circumferential surface of the paper feed roller and the low friction portion on the circumferential end portion. Are different in the front and back in the circumferential direction of the paper feed roller. By rotating the paper feed roller, the low friction part at the end in the circumferential direction and the inner level difference and the high friction part rotate while abutting against the sheet, and the uppermost sheet of the stacked sheets is fed out and turned. . Since the paper feed roller is detachably mounted on the rotation shaft, the mounting direction of the paper feed roller to the rotation shaft can be selected in the reverse direction before and after the circumferential direction. Accordingly, it is possible to change the size of the step between the low friction portion and the high friction portion on the front side in the rotation direction of the paper feed roller. The size of the step is an important parameter in the paper feed performance, and it is difficult to roll when the conveyance tendency is large, and difficult to convey when the conveyance tendency is large. Such sheet feeding performance is determined by the size of the step, and the size of the step can be changed by selecting the mounting direction of the sheet feeding roller to the rotating shaft. For this reason, it is possible to adjust the sheet feeding performance to an appropriate value according to the type of sheet. Further, it is not necessary to replace the paper feed roller, and the cost can be prevented from increasing.

  The sheet supply device according to a second aspect of the present invention is the sheet supply device according to the first aspect, wherein the shaft hole of the paper feed roller includes an opening portion that is extrapolated from a radial direction of the rotation shaft, The hole wall of the shaft hole is characterized in that an engaging portion that is engaged with the engaged portion formed on the rotating shaft is formed.

  According to the second aspect of the present invention, the opening portion of the paper feed roller is extrapolated from the radial direction of the rotation shaft, and the engagement portion formed on the hole wall of the shaft hole is the engagement portion formed on the rotation shaft. The paper feed roller can be detachably mounted on the rotating shaft. For this reason, it is possible to attach the paper feed roller to the rotating shaft in the reverse direction before and after the circumferential direction, and it is easy to attach the paper feed roller.

  A sheet feeding apparatus according to a third aspect of the present invention is the sheet feeding apparatus according to the first or second aspect, wherein the end of the high friction portion causes the sheet to travel when the sheet feeding roller rotates. It is characterized in that it is set in a shape and position that does not obstruct.

  According to the invention described in claim 3, when the mounting direction of the paper feed roller to the rotation shaft is changed in the reverse direction before and after the circumferential direction, even if the paper feed roller rotates, by the end of the high friction portion, Seat travel is not hindered. For this reason, the sheet can be fed smoothly.

  According to a fourth aspect of the present invention, an image forming apparatus includes the sheet feeding device according to any one of the first to third aspects.

  According to the fourth aspect of the present invention, since the sheet feeding device according to any one of the first to third aspects is provided, the mounting direction of the paper feed roller to the rotating shaft is set to the front and rear in the circumferential direction. It is possible to select and install in the reverse direction. For this reason, the size of the step between the high friction portion and the low friction portion before and after the circumferential direction of the paper feed roller can be changed, and the paper feed performance can be appropriately adjusted according to the type of sheet. In addition, it is not necessary to replace the paper feed roller, and an increase in cost can be prevented.

  In the sheet supply device and the image forming apparatus according to the present invention, the size of the step between the high friction portion and the low friction portion of the paper feed roller is changed by mounting the paper feed roller on the rotation shaft in the reverse direction in the circumferential direction. The sheet feeding performance can be adjusted to an appropriate value according to the type of sheet. In addition, it is not necessary to replace the paper feed roller, and an increase in cost can be prevented.

  Embodiments of a sheet supply apparatus and an image forming apparatus according to the present invention will be described below with reference to the drawings.

  FIG. 1 shows an image forming apparatus 1 including a sheet supply device 50 according to the first embodiment of the present invention.

  The image forming apparatus 1 is a tandem type digital color printer, and image data sent from an exposure apparatus for a document (not shown), a personal computer, or the like is sent to an IPS (Image Processing System) 12 to obtain a predetermined image. Processing is performed. Image data that has been subjected to predetermined image processing by the IPS 12 is also reproduced by the IPS 12 in four color reproduction materials of yellow (Y), magenta (M), cyan (C), and black (K) (8 bits each). As described below, the image forming units 13Y, 13M, 13C, and 13K for image forming units of yellow (Y), magenta (M), cyan (C), and black (K) are converted into gradation data. Is sent to a ROS (Raster Output Scanner) 14, which performs image exposure with laser light LB in accordance with original reproduction color material gradation data of a predetermined color.

  Inside the image forming apparatus 1, four image forming units 13Y, 13M, 13C, and 13K of yellow (Y), magenta (M), cyan (C), and black (K) are spaced at a constant interval in the horizontal direction. Are arranged in parallel. These four image forming units 13Y, 13M, 13C, and 13K are all configured in the same manner. The photosensitive drum 15 that is rotationally driven and the charging roll 16 that uniformly charges the surface of the photosensitive drum 15 are provided. ROS 14 that exposes an image corresponding to a predetermined color on the surface of the photosensitive drum 15 to form an electrostatic latent image, and the electrostatic latent image formed on the photosensitive drum 15 with toner of a predetermined color. The developing unit 17 for developing and a cleaning device 18 for cleaning the surface of the photosensitive drum 15 are configured.

  The ROS 14 is configured in common to the four image forming units 13Y, 13M, 13C, and 13K, and modulates four semiconductor lasers (not shown) in accordance with original reproduction color material gradation data for each color, and these semiconductor lasers. Are configured to emit laser beams LB-Y, LB-M, LB-C, and LB-K according to the gradation data. Of course, the ROS 14 may be individually configured for each of a plurality of image forming units. The laser beams LB-Y, LB-M, LB-C, and LB-K emitted from the semiconductor laser are irradiated to the polygon mirror 19 through an f-θ lens (not shown), and are deflected and scanned by the polygon mirror 19. The The laser beams LB-Y, LB-M, LB-C, and LB-K deflected and scanned by the polygon mirror 19 pass through an imaging lens (not shown) and a plurality of mirrors to an exposure point on the photosensitive drum 15. Then, scanning exposure is performed obliquely from below.

  Since the ROS 14 scans and exposes an image on the photosensitive drum 15 from below, the ROS 14 includes toner and the like from the four image forming units 13Y, 13M, 13C, and 13K located above. May fall and become soiled. Therefore, the periphery of the ROS 14 is hermetically sealed by a rectangular parallelepiped frame 20, and four laser beams LB-Y, LB-M, LB-C, and LB-K are provided on the upper portion of the frame 20, respectively. Transparent glass windows 21Y, 21M, 21C, and 21K as shield members are provided for exposure on the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K.

  From the IPS 12, image data of each color is supplied to the ROS 14 provided in common to the image forming units 13Y, 13M, 13C, and 13K of each color of yellow (Y), magenta (M), cyan (C), and black (K). Are output sequentially. The laser beams LB-Y, LB-M, LB-C, and LB-K emitted from the ROS 14 according to the image data are scanned and exposed on the surface of the corresponding photosensitive drum 15 to form an electrostatic latent image. . The electrostatic latent image formed on the photoconductor drum 15 is developed by toners of yellow (Y), magenta (M), cyan (C), and black (K), respectively, by developing units 17Y, 17M, 17C, and 17K. Developed as an image.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images sequentially formed on the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K On the intermediate transfer belt 25 of the transfer unit 22 arranged over the image forming units 13Y, 13M, 13C, and 13K, the images are transferred in multiple by the four primary transfer rolls 26Y, 26M, 26C, and 26K. These primary transfer rolls 26Y, 26M, 26C, and 26K are disposed on the back side of the intermediate transfer belt 25 corresponding to the photosensitive drums 15 of the image forming units 13Y, 13M, 13C, and 13K. A transfer bias power source (not shown) is connected to the primary transfer rolls 26Y, 26M, 26C, and 26K, and a transfer bias having a polarity opposite to a predetermined toner polarity (positive polarity in the present embodiment) is set at a predetermined timing. Applied.

  The intermediate transfer belt 25 is wound around the drive roll 27, the tension roll 24, and the backup roll 28 with a constant tension, and is rotated by a motor (not shown) by a drive roll 27 shown in the drawing. Circulation is driven around at a predetermined speed.

  The yellow (Y), magenta (M), cyan (C), and black (K) toner images transferred onto the intermediate transfer belt 25 in a multiple manner are transferred to the backup roll 28 by a secondary transfer roll 29. The recording paper 30 that has been secondarily transferred onto the recording paper 30 as a sheet and onto which the toner images of these colors have been transferred is conveyed to a fixing device 31 positioned above. The secondary transfer roll 29 is in pressure contact with the side of the backup roll 28 and is configured to secondary-transfer toner images of each color onto a recording paper 30 that is conveyed from below to above. The recording paper 30 onto which the toner images of each color have been transferred is subjected to a fixing process by heat and pressure by a fixing device 31 and then discharged onto a discharge tray 33 provided on the upper portion of the image forming apparatus 1 by a discharge roll 32. Is done.

  The recording paper 30 having a predetermined size from the paper feed cassette 34 is once transported to a registration roll 38 via a paper transport path 37 by a paper feed roller 35 and a pair of paper separating and transporting rollers 36 and stopped. . The paper transport path 37 of the fed recording paper 30 is directed upward in the vertical direction. The recording paper 30 supplied from the paper feed cassette 34 is sent to the secondary transfer position of the intermediate transfer belt 25 by a registration roll 38 that rotates at a predetermined timing.

  When the image forming apparatus 1 makes a full-color double-sided copy, the recording sheet 30 having an image fixed on one side is not directly discharged onto the discharge tray 33 by the discharge roll 32 but is not shown. To switch the transport direction and transport the paper to the duplex transport unit 40 via the pair of paper transport rollers 39. In the double-sided conveyance unit 40, the recording paper 30 is conveyed again to the registration roll 38 with the pair of conveyance rollers (not shown) provided along the conveyance path 41 being reversed. Then, after the image is transferred and fixed on the back surface of the recording paper 30, it is discharged onto the discharge tray 33.

  Further, residual toner, paper dust, and the like are removed from the surface of the photosensitive drum 15 after the toner image transfer process is completed by the cleaning device 18 to prepare for the next image forming process. The cleaning device 18 includes a cleaning blade (not shown), and removes residual toner, paper dust, and the like on the photosensitive drum 15 by the cleaning blade. Further, residual toner, paper dust, and the like are removed from the surface of the intermediate transfer belt 25 after the toner image transfer process is completed by the cleaning device 43 to prepare for the next image forming process. The cleaning device 43 includes a cleaning brush 43a and a cleaning blade 43b, and the cleaning brush 43a and the cleaning blade 42 remove residual toner, paper dust, and the like on the intermediate transfer belt 25.

  In addition, toner cartridges 44Y, 44M, 44C, and 44K that store yellow, magenta, cyan, and black toners are respectively provided in the upper part of the inside of the image forming apparatus 1. The color toner is supplied.

  Further, a manual feed tray 47 capable of stacking arbitrary sheets is attached to the side surface (the left side surface in FIG. 1) of the image forming apparatus 1. The manual feed tray 47 is provided with a sheet supply device 50 for feeding the recording paper 52 as a sheet. A sheet fed from a manual feed tray 47 by a later-described feed roller 54 is transported to a registration roll 38 by a pair of transport rollers 60 disposed on the downstream side. The recording sheet 52 is different in type and size from the recording sheet 30 described above.

  As shown in FIGS. 2 and 3, the sheet supply device 50 includes a paper placement plate portion 53 for placing the recording paper 52 inside the manual feed tray 47. The paper placement plate portion 53 includes a biasing member (not shown) at the lower portion thereof, and the front end portion of the recording paper 52 is placed on a paper feed roller 54 (to be described later) with the recording paper 52 being placed as necessary. It is configured to be movable upward so as to be in pressure contact. Further, the paper placing plate portion 53 feeds the recording paper 52 in a state where the recording paper 52 is placed with reference to one end portion in the width direction (right end portion in the illustrated example), so-called “side edge feed”. A side guide 55 that aligns the end portions of the paper is fixed to one end portion in the width direction of the paper placement plate portion 53.

  Further, the sheet supply device 50 includes a plurality of (two in the illustrated example) substantially half-moon-shaped sheet feeding rollers 54 for feeding the recording sheet 52 to the upper back side of the sheet placing plate portion 53; A plurality (two in the illustrated example) of auxiliary rollers 56 are provided on the outside of the paper feed roller 54, respectively. The two paper feed rollers 54 are fixedly attached to a shaft 57 that is driven to rotate. A gear 61 is connected to the axial end of the shaft 57, and the gear 61 meshes with a transmission gear 62 that transmits a driving force from a motor (not shown).

  As shown in FIGS. 4A and 5, the paper feed roller 54 is made of a material (for example, rubber) having a friction coefficient larger than that of the recording paper 52 in the vicinity of the central portion of the circumferential surface formed in a substantially half moon shape. The high friction part 64 formed by is provided. Further, slip portions 65 a and 65 b made of a material having a smaller frictional engagement than the recording paper 52 are provided at the front end portion and the rear end portion in the circumferential direction of the high friction portion 64. The slip portions 65a and 65b are made of, for example, synthetic resin, and have a friction coefficient smaller than that of the high friction portion 64 made of rubber or the like.

  As shown in FIG. 5, in the paper feed roller 54, the slip portions 65a and 65b are smaller in diameter than the outer diameter of the high friction portion 64, and the high friction portion 64 protrudes in the radial direction from the slip portions 65a and 65b. . A stepped portion 64a is formed at the boundary between the high friction portion 64 and the slip portion 65a, and a stepped portion 64b is formed at the boundary between the high friction portion 64 and the slip portion 65b. At that time, the radius of the slip portion 65a is set larger than the radius of the slip portion 65b, and the dimension of the step portion 64b is larger than the step portion 64a. Further, as shown in FIG. 5A, the stepped portion 64a is formed in the vicinity of a position on the inner side of about ¼ from the tip of the slip portion 65a of the paper feed roller 54. The slip portion 65a is formed in an arc shape with a predetermined length L1 at the front end portion of the paper feed roller. The stepped portion 64b is formed in the vicinity of the rear end of the paper feed roller 54 in the circumferential direction, and the slip portion 65a is formed in an arc shape with a predetermined length L2 at the rear end of the paper feed roller 54 in the circumferential direction. ing. This length L2 is set shorter than the length L1.

  The high friction part 64 is integrally assembled on the peripheral surface of the paper feed roller 54 by being fitted into a recess 65c formed between the slip part 65a and the slip part 65b.

  As shown in FIG. 4, the shaft hole 68 of the paper feed roller 54 has an opening 68 </ b> A that is externally inserted into the columnar shaft 57 on the opposite side of the half-moon-shaped peripheral surface. As shown in FIG. 4B, two pins 57a projecting in a direction perpendicular to the axis are provided on the peripheral surface of the shaft 57. As shown in FIG. 6, the paper feed roller 54 is formed with recesses 69 that can engage with the two pins 57a on both sides in the axial direction of the opening 68A. As shown in FIGS. 5 (A) and 5 (B), the paper feed roller 54 has the opening 68A extrapolated from the radial direction of the shaft 57 with the front and rear in the circumferential direction reversed, and the pin 57a is engaged with the recess 69. Thus, the mounting direction can be reversed before and after the circumferential direction. As the shaft 57 rotates, the peripheral surface of the paper feed roller 54 rotates in the direction of the arrow and comes into contact with the recording paper 52 so that the leading end of the recording paper 52 is intermittently fed as will be described later. It is configured. A plurality of notches are provided in the shaft hole 68 of the paper feed roller 54, and elastic deformation is possible.

  As shown in FIG. 3, the two auxiliary rollers 56 are formed in a ring shape from synthetic resin or the like, and the radius of the auxiliary roller 56 is set smaller than the radius of the slip portions 65a and 65b of the paper feed roller 54. ing. On the inner side of the auxiliary roller 56, a plurality of snap fits 56a are formed to be engaged with grooves 57b formed on the peripheral surface of the shaft 57. In the present embodiment, two snap fits 56a are formed diagonally (the back side of the shaft 57 is omitted in FIG. 3). Then, the inner side of the annular portion of the auxiliary roller 56 is inserted into the shaft 57, the snap fit 56a is elastically deformed, and is engaged with the groove portion 57b of the shaft 57, whereby the auxiliary roller 56 is fixed to the peripheral surface of the shaft 57. .

  The auxiliary roller 56 is positioned so as to come into contact with the side surface of the paper feed roller 54 when it is fixed to the peripheral surface of the shaft 57. As a result, the feed roller 54 is restricted from moving in the circumferential direction by the engagement of the pin 57 a of the shaft 57 and the recess 69, and the side surface of the feed roller 54 contacts the auxiliary roller 56. Directional movement is restricted.

  Similarly, a plurality (three in the figure) of auxiliary rollers 58 are attached to a shaft 57 at a position away from the left auxiliary roller 56 in FIG. The auxiliary roller 58 applies an auxiliary conveying force to the recording paper 52 located on the opposite side of the paper supply roller 54.

  Further, as shown in FIGS. 2 and 7, a separation pad 59 is configured to come into pressure contact with the two paper feed rollers 54 and the auxiliary roller 56. As shown in FIG. 7, the separation pad 59 is swingably mounted in a direction in which the separation pad 59 comes into contact with and separates from the paper feed roller 54 around the support shaft 80 on the upstream side in the paper feed direction. A spring 82 wound around the shaft 80 is configured to come into pressure contact with the paper feed roller 54 with a predetermined pressing force. A stopper 84 that restricts swinging is provided above the separation pad 59.

  Next, the operation of the sheet supply apparatus 50 will be described.

  In the sheet supply apparatus 50, as shown in FIGS. 5A and 5B, the mounting direction of the sheet feeding roller 54 to the shaft 57 can be selected in the reverse direction before and after the circumferential direction. That is, as shown in FIG. 5A, when the slip portion 65a is attached so as to be positioned at the tip in the rotation direction (arrow direction), and as shown in FIG. The case of mounting so as to be located at the tip in the direction of the arrow can be selected (see FIGS. 7 and 8). As a result, the sheet feeding performance of the sheet feeding device 50 can be changed depending on the type of the recording sheet 52 and the like.

  The paper feed roller 54 is attached to the shaft 57 by extrapolating the opening 68A from the radial direction of the shaft 57 toward the selected direction and engaging the recess 69 of the shaft hole 68 with the pin 57a. . Due to the engagement between the pin 57a and the recess 69, the movement of the paper feed roller 54 in the circumferential direction is restricted. At this time, as shown in FIG. 6, since the recesses 69 are formed on both sides of the opening 68A in the axial direction of the paper feed roller 54, the paper feed roller 54 is attached to the shaft 57 in the reverse direction in the circumferential direction. be able to. Further, the auxiliary roller 56 is inserted into a position adjacent to the paper feed roller 54 of the shaft 57, and the snap fit 56a is engaged with the groove 57b, whereby the axial movement of the paper feed roller 54 is restricted.

  As shown in FIG. 7, when the recording paper 52 is fed by the sheet feeding device 50, the paper placement plate portion 53 is not shown in a state where the recording paper 52 is placed on the paper placement plate portion 53. By urging upward by the urging member, the leading end of the recording paper 52 is pressed against the auxiliary roller 56. In this state, when the paper feed roller 54 is rotationally driven by the shaft 57, the leading end portion of the recording paper 52 is fed by the feeding force of the paper feed roller 54, and the recording paper 52 is fed.

  At this time, when the paper feed roller 54 rotates, the slip portion 65a of the paper feed roller 54 contacts the recording paper 52, and further, the step portion 64a and the high friction portion 64 contact. Since the stepped portion 64a formed at the boundary between the slip portion 65a and the high friction portion 64 is smaller than the stepped portion 64b shown in FIG. Easy to whisper. The slip portion 65a and the step portion 64a can move the uppermost recording paper 52 of the recording paper 52 stacked on the paper placement plate portion 53 to a predetermined position where it abuts against the separation pad 59. The sheets 52 can be reliably separated and fed one by one.

  Further, when the paper feed roller 54 rotates in the direction of the arrow, the slip portion 65 b and the step portion 64 b on the rear end side are set to shapes and positions that do not hinder the feeding of the recording paper 52. For this reason, the recording paper 52 is sent out smoothly.

  Further, since the high friction part 64 protrudes in the radial direction from the slip part 65a, even if the high friction part 64 is worn slightly, the frictional force of the high friction part 64 does not decrease as long as it does not become smaller than the radius of the slip part 65a. The recording paper 52 can be reliably fed.

  On the other hand, as shown in FIG. 8, in the case where the feeding direction of the paper feed roller 54 is reversed in the circumferential direction, when the paper feed roller 54 is driven to rotate, the slip portion 65b of the paper feed roller 54 causes the recording paper 52, and the stepped portion 64b and the high friction portion 64 abut. At that time, the circumferential length of the slip portion 65b is shorter than the slip portion 65a shown in FIG. 7, and the size of the step portion 64b is larger than the step portion 64a shown in FIG. ), It becomes easy to send out the recording paper 52. Thereby, even if it is a slippery recording paper, the recording paper 52 can be reliably separated and fed.

  Further, when the paper feed roller 54 rotates in the direction of the arrow, the slip portion 65a and the stepped portion 64a on the rear end side are set to shapes and positions that do not hinder the feeding of the recording paper 52. For this reason, the recording paper 52 is sent out smoothly.

  In such a sheet supply apparatus 50, the paper feed parameters can be adjusted by selecting the mounting direction of the paper feed roller 54 in the reverse direction before and after the circumferential direction. As a result, the paper feed parameters can be adjusted appropriately according to the type of the recording paper 52, and the recording paper 52 can be reliably separated and fed. Further, since the paper feed parameters can be easily adjusted without replacing the paper feed roller 54, an increase in cost can be prevented.

  In addition, the magnitude | size of level | step-difference part 64a, 64b is not limited to the structure of the said embodiment, A shape and a position can be set suitably. Further, the shape and length of the slip portions 65a and 65b are not limited to the configuration of the above embodiment, and the shape and length can be set as appropriate.

  In the above embodiment, the concave portion 69 of the paper feed roller 54 is engaged with the pin 57a of the shaft 57. However, the present invention is not limited to this configuration. Any structure can be used as long as the paper feed roller 54 can be attached to the shaft 57 with the front and rear in the circumferential direction reversed.

1 is a schematic configuration diagram illustrating an image forming apparatus including a sheet supply apparatus according to a first embodiment of the present invention. 1 is a perspective view showing a configuration of a sheet supply device used in an image forming apparatus. FIG. 6 is a perspective view illustrating a configuration in the vicinity of a sheet feeding roller and a shaft of the sheet supply apparatus. (A) is a perspective view showing a configuration of a paper feed roller, and (B) is a side view showing a shaft. (A) And (B) is sectional drawing which shows the structure which made the attachment direction to the shaft of a feed roller into the reverse direction before and behind the circumferential direction. It is sectional drawing which shows the state which cut | disconnected the paper feed roller and the shaft to the axial direction. FIG. 6 is a configuration diagram illustrating a state in which a sheet feeding roller is attached to a sheet supply apparatus. FIG. 8 is a configuration diagram illustrating a state in which a sheet feeding roller is attached to the sheet supply device in the reverse direction in the circumferential direction with respect to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 13Y Image forming unit 15 Photosensitive drum 50 Sheet supply apparatus 52 Recording paper 53 Paper mounting board part 54 Paper feed roller 55 Side guide 56 Auxiliary roller 57 Shaft 57a Pin (engaged part)
57b Groove portion 58 Auxiliary roller 59 Separation pad 60 Conveying roller 64 High friction portion 64a Step portion (step)
64b Stepped part (step)
65a Slip part (low friction part)
65b Slip part (low friction part)
68 Shaft hole 68A Opening 69 Recess (engagement part)

Claims (4)

A half-moon-shaped paper feed roller that is detachably mounted on the rotary shaft and rotates to feed the sheets stacked on the sheet stacking means;
The peripheral surface of the paper feed roller has a high friction part having a large friction coefficient with the sheet, and a friction coefficient with the sheet is smaller than that of the high friction part at the circumferential end of the paper feed roller. A low friction part having a smaller diameter than the outer diameter of the high friction part is provided,
The sheet feeding apparatus according to claim 1, wherein the step difference between the low friction part and the high friction part is different between before and after the circumferential direction of the paper feed roller.   The shaft hole of the paper feed roller has an opening that is externally inserted from the radial direction of the rotating shaft, and the hole wall of the shaft hole is engaged with an engaged portion formed on the rotating shaft. The sheet feeding apparatus according to claim 1, wherein a joining portion is formed.   3. The sheet feeding apparatus according to claim 1, wherein an end portion of the high friction portion is set in a shape and a position that do not interfere with traveling of the sheet when the sheet feeding roller rotates.   An image forming apparatus comprising the sheet feeding device according to claim 1.

Images