JP5725666B2 - Sheet conveying apparatus, image forming apparatus including the same, and image reading apparatus - Google Patents

Description

  The present invention relates to a sheet conveying apparatus, an image forming apparatus including the sheet conveying apparatus, and an image reading apparatus, and more particularly, to a sheet conveying apparatus that separates sheets one by one and feeds them from a rotary feeding member, and an image forming apparatus including the sheet conveying apparatus. The present invention relates to an apparatus and an image reading apparatus.

  Conventionally, as a method of feeding while separating sheets stacked on a sheet feeding tray one by one, a combination of a rotation feeding member such as a sheet feeding roller and a separation roller given reverse rotation torque It has been known. In this method, the front feed roller is brought into contact with the uppermost sheet among the sheets stacked on the paper feed tray, the sheet is pulled out from the paper feed tray by the rotation of the front feed roller, and then the leading edge of the sheet is reached. Is plunged into the nip formed by the paper feed roller and separation roller. The feed roller rotates in the direction to feed the sheet further forward, but the separation roller is given a rotational torque in the direction opposite to the sheet feed direction via the torque limiter, and the feed roller is fed to the feed roller. It is in pressure contact.

  When a single sheet is fed into the nip of the separation roller and paper feed roller, the rotational torque that exceeds the limit value of the torque limiter acts on the separation roller from the paper feed roller, so the separation roller is driven by the paper feed roller. The sheet is fed downstream by a paper feed roller. On the other hand, when two or more sheets are fed into the nip portion, the limit value of the torque limiter is large with respect to the frictional force between the overlapping sheets, so that slip occurs between the uppermost sheet and the sheet below it. Occur. The separation roller rotates in a direction opposite to the sheet feeding direction, and pushes back one or more sheets excluding the uppermost sheet that is in direct contact with the sheet feeding roller toward the sheet feeding tray. As a result, only the uppermost sheet that is in contact with the sheet feeding roller is fed by the rotation of the sheet feeding roller, thereby preventing multiple sheets from being fed.

  In such a separation feeding method, it is necessary to accurately control the reverse conveying force acting on the lowermost sheet from the separation roller in order to prevent double feeding of two or more overlapping sheets. Is done.

  In view of this, the sheet conveying apparatus described in Patent Document 1 detects the amount of rush of sheets that are double-fed to the nip portion. If the amount of entry of the second sheet into the nip is small, it is determined that there is no possibility that the second sheet will be double-fed together with the first sheet, and the sheet feeding roller is rotated as it is. On the other hand, when the rush amount of the second sheet exceeds a predetermined value, the second sheet is increased by increasing the reverse rotational torque transmitted from the driving source such as a motor to the separation roller. The force to push the sheet back toward the paper feed tray is increased, preventing the double feeding of the sheets.

  However, when feeding repeatedly, the frictional force on the surface of the separation roller changes due to wear of the feed roller and separation roller, and the friction of the separation roller depends on the temperature and humidity around the nip of the separation roller and feed roller. Since the force changes, the force (separation force) for returning the sheet in the direction of the sheet feeding tray varies according to repeated feeding and the surrounding temperature and humidity environment. Therefore, in the sheet conveying device described in Patent Document 1, it is difficult to stably feed a sheet because the separation force of a plurality of sheets fluctuates when feeding repeatedly or when the temperature and humidity environment around the nip changes. There was an inconvenience.

  In view of this, a related technique is known in which feeding is performed stably even with repeated feeding and changes in the temperature and humidity environment. For example, in the sheet conveyance device described in Patent Document 2, when the frictional force of the sheet feeding roller and the separation roller is reduced due to long-term use and slipping occurs between the two rollers and the sheet, the separation roller is separated from the sheet feeding roller. Since the rotational speed decreases, the rotational speed of the separation roller is detected. Based on the detection result of the rotation detecting means for detecting the rotation speed of the separation roller, the pressure contact force by the urging member that presses the separation roller against the paper feed roller is adjusted.

Japanese Patent Laying-Open No. 2005-239297 (paragraphs [0053] and [0054], FIG. 6) JP-A-4-371426 (paragraphs [0011] to [0015], FIG. 1)

  In the sheet conveying apparatus described in Patent Document 2, the rotation detection unit includes a light projecting unit and a light receiving unit that face a plurality of through holes provided in the circumferential direction, and determines the number of through holes through which light passes while rotating. The number of rotations of the separation roller is detected by counting. When the detected number of rotations is not large with respect to the reference number of rotations, it is assumed that the friction coefficient of the separation roller is reduced, and the pressing force by the urging member is increased. However, the sheet conveying apparatus described in Patent Document 2 cannot detect the rotation unevenness of the separation roller, and is insufficient to accurately detect the rotation state.

  The present invention has been made to solve the above-described problems, accurately detects the rotation state of the separation roller, and stably feeds even with repeated feeding and changes in the temperature and humidity environment. An object of the present invention is to provide a sheet conveying apparatus, an image forming apparatus including the sheet conveying apparatus, and an image reading apparatus.

  In order to achieve the above object, a sheet conveying apparatus according to a first aspect of the present invention includes a rotary feeding member that feeds a sheet from a sheet accommodating portion that accommodates a sheet, and a nip portion that is in pressure contact with the rotary feeding member. A separation roller that separates the overlapped sheets at the nip portion, a separation force adjusting portion that changes a force for separating the overlapped sheets by the separation roller, and a shaft that rotates with the separation roller, and that rotates with respect to the rotation axis direction. A detected member formed with a cylindrical end portion in which the protruding amount of the direction end face continuously changes, and a detecting member that detects a continuous displacement amount of the cylindrical end portion, and when the separation roller rotates A rotation detection means for detecting a rotation state of the separation roller based on a change in a detection amount of the detection member, and a detection by the rotation detection means when the detected member rotates normally. A reference data storage unit for storing reference data indicating a change in the detected amount; and the separation based on a deviation of the detected amount data indicating the change in the detected amount actually detected by the rotation detecting unit with respect to the reference data. And a control unit capable of executing a separation force correction mode for changing the separation force of the force adjusting unit.

  According to a second aspect of the present invention, in the sheet conveying apparatus, the separation force correction mode is executed before a sheet is fed by the rotary feeding member.

  According to a third aspect of the present invention, in the above sheet conveying apparatus, the reference data storage unit stores a plurality of reference data corresponding to the type of the sheet, and the control unit feeds the sheet by the rotary feeding member. In some cases, the separation data correction mode is executed by selecting the reference data corresponding to the type of sheet to be fed from the reference data storage unit.

  According to a fourth aspect of the invention, there is provided an image forming apparatus including the sheet conveying apparatus having the above-described configuration.

  According to a fifth aspect of the invention, there is provided an image reading apparatus provided with the sheet conveying apparatus having the structure described above.

  According to the first invention, when the separation roller rotates, if the detection amount data input from the rotation detection unit to the control unit is within a predetermined range with respect to the reference data, the separation roller is fed satisfactorily. As a matter of course, the separation force of the separation force adjusting unit is not changed. On the other hand, if the detected amount data exceeds the predetermined range with respect to the reference data, it is assumed that the separation roller is worn or the frictional force of the separation roller is reduced due to changes in the temperature / humidity environment. Change so that the separation force of the part increases. As a result, stable feeding can be achieved even with repeated feeding and changes in the temperature and humidity environment around the separation roller.

Schematic showing an image forming apparatus provided with a sheet conveying apparatus according to an embodiment of the present invention The perspective view which shows the sheet conveying apparatus which concerns on embodiment Schematic showing the periphery of a sheet feeding roller and a separation roller of a sheet conveying apparatus according to an embodiment The perspective view which shows the separating force adjustment part of the sheet conveying apparatus which concerns on embodiment. The perspective view which shows the rotation detection means of the sheet conveying apparatus which concerns on embodiment Schematic which shows the structure and control part of the rotation detection means which concern on embodiment The figure which shows the light reception amount data and reference | standard data of the rotation detection means which concern on embodiment

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. Further, the use of the invention and the terms shown here are not limited thereto.

  FIG. 1 is a schematic view showing an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 includes a rectangular parallelepiped apparatus main body 1a, and an image forming unit 10 is disposed at a substantially central portion in the apparatus main body 1a. The image forming unit 10 includes a photoconductor 11 that is an image carrier, and further, around the photoconductor 11 in order along the rotation direction (the arrow direction in the drawing), a charging unit 13, an exposure unit 12, and a developing unit. The unit 2, the transfer roller 54, the cleaning unit 14, and the charge removal unit 15 are provided. The supply of toner to the developing unit 2 is performed from a toner container (not shown). The cleaning unit 14 collects toner remaining on the surface of the photoconductor 11, and the charge removal unit 15 removes residual charges on the surface of the photoconductor 11.

  When the surface of the photoconductor 11 is uniformly charged by the charging unit 13 with a predetermined polarity and potential, the exposure unit 12 is arranged on the photoconductor 11 on the basis of image data of a document read by a document reading device (not shown). Then, an electrostatic latent image of the original image is formed.

  The developing unit 2 supplies charged toner to the surface of the photoconductor 11 and develops the electrostatic latent image on the photoconductor 11 to form a toner image. The toner image is transferred onto the sheet by the transfer roller 54. After the toner image is transferred onto the sheet, the toner remaining on the surface of the photoconductor 11 is cleaned and collected by the cleaning unit 14, and the residual charge on the surface of the photoconductor 11 is removed by the charge removing unit 15.

  The sheet feeding device 20 includes sheet cassettes 22 to 25 that are sheet storage units. The paper feed cassettes 22 to 25 are arranged in the vertical direction at the bottom of the apparatus main body 1a. Each of the paper feed cassettes 22 to 25 is detachably disposed on the front surface of the apparatus main body 1a, and is pulled out from the apparatus main body 1a to replenish the sheet, and is pushed in and inserted into the apparatus main body 1a after replenishing the sheet. The sheet is placed on the sheet stacking plate 28 of the sheet feeding cassette 22, and the sheet on the sheet stacking plate 28 is sent out to the sheet conveying unit 70 by the pickup roller 29.

  The sheet conveying unit 70 is for conveying a sheet within the apparatus main body 1a, and includes a sheet feeding conveyance path 71, an image forming conveyance path 72, a post-fixing conveyance path 73, a branch conveyance path 74, and a reverse discharge. A transport path 77, a reverse transport path 75, and a re-transport path 76 are provided.

  The sheet feeding conveyance path 71 is a conveyance path from the sheet feeding apparatus 20 to the registration roller pair 53, and extends upward from the sheet feeding apparatus 20 on the right side of the apparatus main body 1a and is curved to the left from the middle. The registration roller pair 53 is disposed on the right side of the transfer roller 54 and sends the sheet toward the transfer roller 54 in synchronization with the timing of transferring the toner image to the sheet.

  The image forming conveyance path 72 is a conveyance path from the registration roller pair 53 to the fixing unit 18 and extends in the substantially horizontal direction of the apparatus main body 1a and is curved upward from the middle. An image forming unit 10 and a fixing unit 18 are arranged in the image forming conveyance path 72, and a toner image is transferred onto the sheet by the image forming unit 10, and the toner image transferred to the sheet is transferred onto the sheet by the fixing unit 18. To be established.

  The post-fixing conveyance path 73 is a conveyance path extending upward from the fixing unit 18 to the branch conveyance path 74. In the post-fixation conveyance path 73, the sheet on which the toner image is fixed is conveyed to the branch conveyance path 74.

  The branch conveyance path 74 is a conveyance path for conveying the sheet on which the toner image is fixed to the reverse discharge conveyance path 77 or the second discharge tray 67. Specifically, the branch conveyance path 74 is curved rightward from the conveyance roller pair 61. And a conveyance path that reaches the reverse discharge conveyance path 77 via the conveyance roller pair 62 and a conveyance path that curves leftward from the conveyance roller pair 61 and discharges the sheet to the second discharge tray 67 by the second discharge roller pair 63. And a conveyance path that extends in the horizontal direction from the conveyance roller pair 62 to the second discharge roller pair 63 and discharges the sheet in the reverse discharge conveyance path 77 to the second discharge tray 67.

  The reverse discharge conveyance path 77 is a conveyance path for discharging the sheet to the first discharge tray 66 or conveying the reversed sheet to form a toner image on the back surface of the sheet.

  The reverse conveyance path 75 reverses the conveyance direction of the sheet and conveys the sheet whose conveyance direction is reversed to the reverse discharge conveyance path 77, branches from the conveyance path 73 after fixing, and a pair of reverse rollers 57 to the right. Further, it extends upward in a U shape from the pair of reverse rollers 57 and joins the reverse discharge conveyance path 77.

  The re-conveying path 76 conveys the sheet reversed by the reversing conveying path 75 from the reversing discharge conveying path 77 to the image forming conveying path 72, and is formed by branching downward from the reversing discharging conveying path 77. It merges with the conveyance path 71.

  When the sheet supplied from the sheet feeding device 20 is conveyed upward in the sheet feeding conveyance path 71 and further conveyed to the transfer roller 54 at the conveyance timing by the registration roller pair 53, the toner is transferred by the transfer roller 54. The image is transferred to the sheet. The sheet on which the toner image is transferred is conveyed to the fixing unit 18 on the image forming conveyance path 72, and when heated and pressed by the fixing unit 18, the toner image is melted and fixed on the sheet. The sheet on which the toner image is fixed passes through the post-fixing conveyance path 73 and the branch conveyance path 74 and is discharged to the first discharge tray 66 by the conveyance roller pair 62 and the first discharge roller pair 64. Alternatively, the sheet on which the toner image is fixed is discharged to the second discharge tray 67 by the second discharge roller pair 63 through the post-fixing transfer path 73 and the branch transfer path 74.

  In the case of duplex printing, the sheet fixed by the fixing unit 18 is conveyed from the post-fixing conveyance path 73 to the reverse conveyance path 75. After the leading edge of the sheet passes through the reverse roller pair 57 in the reverse conveyance path 75, the reverse roller pair 57 is reversely rotated at a predetermined timing, so that the sheet is switched back, and the printing surface of the sheet is turned upside down. In this state, it is sent to the reverse discharge conveyance path 77. The reversed sheet is conveyed again from the reverse discharge conveyance path 77 to the sheet feeding conveyance path 71 via the re-conveyance path 76. The sheet conveyed to the image forming conveying path 72 via the paper feeding conveying path 71 is branched and conveyed when the toner image is transferred to the back surface thereof by the image forming unit 10 and the toner image is melted and fixed by the fixing unit 18. The paper is discharged to the first discharge tray 66 or the second discharge tray 67 through the conveyance path selected in the path 74.

  FIG. 2 is a perspective view showing a sheet feeding device 20 which is a sheet conveying device. In the following description, the configuration and operation of the paper feed cassette 22 shown in FIG. 1 and its periphery will be described. However, the configuration and operation of the paper feed cassettes 23 to 25 and their periphery will be described with reference to the paper feed cassette 22 and its periphery. This is the same and will not be described.

  The sheet feeding cassette 22 is formed in a flat box shape with an upper surface opened by a front surface portion 22a, a rear surface portion 22e, and both side surfaces thereof, and stacks and stores sheets from the upper surface side. When guide ribs 22f (the other guide rib 22f is not visible) provided on both side surfaces of the paper feed cassette 22 are engaged with a rail (not shown) of the apparatus main body 1a (see FIG. 1) and slid horizontally in the direction of arrow A, While the paper feed cassette 22 is mounted on the apparatus main body 1a, when the guide rib 22f is slid horizontally in the direction of arrow B, the paper feed cassette 22 is pulled out from the apparatus main body 1a.

  The paper feed cassette 22 includes a sheet stacking plate 28, a pair of width direction cursors 31 and 31, and a lift plate 33. The mounting frame (formed on the apparatus main body 1a) is provided with a pickup roller 29, a feed roller 36 that is a rotary feeding member, a separation roller 37 (see FIG. 3) described later, and a plurality of transport roller pairs 26. Is done.

  The sheet stacking plate 28 is supported in the sheet feeding cassette 22 so that the upstream side in the sheet conveyance direction C can be rotated in the vertical direction around a rotation shaft (not shown). A sheet bundle is placed on the sheet stacking plate 28. The pair of width direction cursors 31, 31 are arranged in the sheet feeding cassette 22 so as to sandwich the sheet stacking plate 28, and come into contact with the side surface of the sheet bundle from both sides in the sheet width direction. The sheet bundles placed on the sheet stacking plate 28 are positioned by the width direction cursors 31 and 31 and the rear end regulating cursor 34 provided on the bottom surface of the sheet feeding cassette 22 so as to be movable in the transport direction C.

  The lift plate 33 is disposed below the sheet stacking plate 28 and is rotated by a sheet feeding cassette side gear (not shown). The paper feed cassette 22 is mounted on the apparatus main body 1a, and the paper feed cassette side gear meshes with the apparatus main body side gear connected to a lifting motor (not shown). When the lift plate 33 is gradually raised by the rotational drive of the lifting motor in one direction, the sheet stacking plate 28 that comes into contact with the tip of the lift plate 33 is raised. When the sheet stacking plate 28 is raised, the sheet placed on the sheet stacking plate 28 is pressed against the pickup roller 29. On the other hand, when the lift plate 33 is gradually lowered by the rotational drive of the lifting motor in the other direction, the sheet stacking plate 28 is lowered.

The pickup roller 29 sends one or more sheets on the upper side of the sheet bundle placed on the sheet stacking plate 28 to the sheet feeding roller 36. When a plurality of sheets are fed, the paper feed roller 36 and the separation roller 37 (see FIG. 3) separate only the topmost one of the plurality of sheets and feed it to the transport roller pair 26. .
Transport.

  The configuration around the paper feed roller 36 and the separation roller 37 will be described in detail with reference to FIG. FIG. 3 is a schematic view around the paper feed roller 36 and the separation roller 37.

  The paper feed roller 36 and the pickup roller 29 are rotatably supported by the swing member 41 at positions separated from each other in the sheet conveyance direction C. The swing member 41 is supported by the apparatus main body 1 a so as to be rotatable in the vertical direction around the rotation axis of the paper feed roller 36. Further, one end of a coiled compression spring 42a is connected to the vicinity of the pickup roller 29 on the upper surface of the swing member 41, and the other end of the compression spring 42a is fixed to the apparatus main body 1a. As a result, the swing member 41 is biased toward the sheet stacking plate 28.

  Further, a protruding piece 41 a is formed at the end of the swing member 41 on the pickup roller 29 side. The protruding piece 41 a can move between a position facing the sheet rising detection member 50 and a position separating from the position where the swinging member 41 rotates about the rotation axis of the sheet feeding roller 36. The protruding piece 41a moves to a position where it opposes and blocks the light of the detection unit 50a of the sheet rising detection member 50, so that the upper surface of the sheet placed on the sheet stacking plate 28 is in a state of being raised to a predetermined delivery position. Detected. As a result, the driving of the lifting motor 55 that has raised the sheet stacking plate 28 is stopped. Then, the pickup roller 29 rotates counterclockwise to send the uppermost sheet of the sheet stack of the sheet stacking plate 28 to the sheet feeding roller 36.

  A separation roller 37 is disposed below the paper feed roller 36, and the separation roller 37 is pressed against the paper feed roller 36 by a pressure spring 38 through a pressure lever 86 and the like (see FIG. 4) described later. By bringing the separation roller 37 into pressure contact with the paper feed roller 36, a nip portion N is formed between the rollers 36 and 37.

  The separation roller 37 incorporates a torque limiter 43 having a torque limiter shaft 43a. The torque limiter shaft 43 a is driven to rotate by a drive source (not shown), and the torque of the drive source is transmitted to the separation roller 37 via the torque limiter 43. The separation roller 37 rotates in the same direction as the paper feed roller 36 by the rotation of the torque limiter shaft 43a.

  When one sheet is nipped by the nip portion N and the sheet feeding roller 36 rotates, the torque of the separation roller 37 received from the sheet feeding roller 36 at the nip portion N via the sheet is transmitted from the torque limiter shaft 43a. Since the torque is greater than the torque, the separation roller 37 is driven to rotate by the paper feed roller 36, and the sheet is fed from the paper feed roller 36.

  On the other hand, when the sheet feeding roller 36 rotates with a plurality of sheets overlapped and sandwiched at the nip portion N, the torque of the separation roller 37 received from the sheet feeding roller 36 at the nip portion N via the sheet is a torque limiter. Since the torque is smaller than the torque transmitted from the shaft 43 a, the separation roller 37 stops or rotates in the same direction as the paper feed roller 36 (direction for returning the sheet) without being driven by the paper feed roller 36. Only the uppermost sheet of the plurality of sheets is fed from the sheet feeding roller 36 by the rotation of the sheet feeding roller 36 and the rotation of the separation roller 37 in the direction of stopping or returning.

  The transport roller pair 26 includes a transport roller 26a and a transport roller 26b that is pressed against the transport roller 26a by a coiled compression spring 42c. When the conveyance roller 26a is driven to rotate, the conveyance roller 26b is driven to rotate, whereby the sheet fed from the sheet feeding roller 36 is conveyed to the sheet feeding conveyance path 71 (see FIG. 1).

  In the above configuration, when the sheet feeding roller 36 rotates, the torque of the separation roller 37 received from the sheet feeding roller 36 through the sheet at the nip portion N is the friction between the sheet feeding roller 36 and the separation roller 37 and the sheet. Fluctuates under the influence of force. This frictional force is largely due to the pressing force of the nip portion N and the friction coefficient of both the rollers 36 and 37, but when the outer peripheral surfaces of the paper feeding roller 36 and the separation roller 37 are worn out due to repeated use of the paper feeding device 20, The friction coefficient between the rollers 36 and 37 and the sheet is lowered. Further, the friction coefficient between the rollers 36 and 37 and the sheet varies depending on the temperature and humidity environment in which the sheet feeding device 20 is used. The frictional force between the separation roller 37 and the sheet decreases due to the decrease in the friction coefficient. As the frictional force between the separation roller 37 and the sheet is reduced in this way, a decrease in the number of rotations or rotation unevenness due to the separation roller 37 slipping with respect to the paper feed roller 36 or the like occurs. The force that separates the sheets decreases, and as a result, the possibility that a plurality of sheets are fed from the sheet feeding roller 36 increases.

  Therefore, in the present embodiment, a separation force adjusting unit that changes the separation force that separates the overlapped sheets at the nip portion N is provided, and a rotation detection unit that detects the rotation state of the separation roller 37 such as the rotation speed and rotation unevenness is provided. Provided. FIG. 4 is a perspective view showing the configuration of the separation force adjusting unit, and FIG. 5 is a perspective view showing the configuration of the rotation detecting means.

  As shown in FIG. 4, the separation force adjusting unit includes a motor 81 with a worm gear 82 fixed to the drive shaft, a wheel gear 83 that meshes with the worm gear 82, and a rack that meshes with a pinion provided integrally with the wheel gear 83. The formed actuating member 84, the pressurizing spring 38 (see also FIG. 3) spanning the actuating member 84 and the pressurizing lever 86, and the separating roller 37 (see FIG. 3) by the urging force of the pressurizing spring 38 are integrated. A pressure lever 86 for pressing the supporting member 87 to be held is provided.

  When the worm gear 82 rotates in one direction due to the rotational drive of the motor 81, the operating member 84 moves to the right in FIG. 4 via the wheel gear 83 and the rack. The pressure spring 38 is pulled by the movement of the actuating member 84 in the right direction. As a result, the urging force of the pressure spring 38 increases, so that the pressure applied from the pressure lever 86 to the support member 87 increases. As a result, the pressure contact force of the separation roller 37 to the paper feed roller 36 increases.

  On the other hand, when the worm gear 82 rotates in the reverse direction by the reverse rotation drive of the motor 81, the operating member 84 moves to the left in FIG. 4 via the wheel gear 83 and the rack. The pressure spring 38 is contracted by the movement of the actuating member 84 in the left direction. As a result, the urging force of the pressure spring 38 is reduced, so that the pressure applied from the pressure lever 86 to the support member 87 is reduced. As a result, the pressure contact force of the separation roller 37 to the paper feed roller 36 is reduced. In this way, by changing the pressure contact force of the separation roller 37, the separation force for separating the overlapping sheets at the nip portion N can be adjusted.

  As shown in FIG. 5, the rotation detection means is provided opposite to the detection color member 91, which is a detection member provided integrally with one end portion in the axial direction of the separation roller 37, and the detection color member 91. And a light detection member 92 that is a detection member that detects the rotation state of the separation roller 37 that rotates via the member 91.

  FIG. 6 shows a detailed configuration of the rotation detection unit and a control unit that adjusts the separation force adjustment unit based on data detected by the rotation detection unit. FIG. 6 is a schematic view of the configuration of the rotation detecting means in cross section and the control unit.

  The detection collar member 91 is formed in a cylindrical shape, and one end in the axial direction thereof is integrally attached to the separation roller 37, and rotates together with the separation roller 37 when the separation roller 37 rotates. The other end of the detection collar member 91 in the axial direction is provided with a cylindrical end 91 a that forms an end surface that is inclined in a side view with respect to a plane perpendicular to the rotation axis of the detection collar member 91. The cylindrical end portion 91a is formed such that the distance from the vertical plane is continuously different in the circumferential direction (the rotation direction of the detection collar member 91). Specifically, the cylindrical end portion 91a is formed such that the distance from the vertical surface (the amount of protrusion in the rotation axis direction) changes by a predetermined amount with respect to the change in the position on the circumference (rotation angle). ing.

  The light detection member 92 is U-shaped in cross-sectional view, and has a light projecting portion 92a and a light receiving portion 92b on the opposing inner surfaces of the U-shape. The light projecting portion 92a is provided so as to extend linearly in the axial direction of the detection collar member 91, and irradiates light linearly. The light projecting unit 92a is configured, for example, by arranging a plurality of light emitting diodes in a straight line. The light receiving unit 92b is provided with a length substantially equal to that of the light projecting unit 92a and extending linearly in the axial direction, and receives light emitted from the light projecting unit 92a. The light receiving unit 92b is configured by arranging a plurality of phototransistors, photodiodes, and the like in a straight line, for example. The light projecting unit 92 a is disposed on the outer peripheral side of the detection color member 91, and the light receiving unit 92 b is disposed on the inner peripheral side of the detection color member 91. The light detection member 92 is disposed so that the cylindrical end portion 91a of the detection collar member 91 is within the light irradiation range in the longitudinal direction of the light projecting portion 92a. The light projecting unit 92 a may be arranged on the inner peripheral side of the detection color member 91, and the light receiving unit 92 b may be arranged on the outer peripheral side of the detection color member 91.

  In the state shown in FIG. 6, the cylindrical end portion 91 a of the detection collar member 91 is disposed at the position where the light emitting portion 92 a and the light receiving portion 92 b are overlapped with the largest amount (the position with the largest protrusion amount). When 92a irradiates light, the light quantity which the light-receiving part 92b receives becomes the smallest. In the state where the detection collar member 91 is rotated by 180 ° from the state shown in FIG. 6, the cylindrical end portion 91a is disposed at the smallest overlapping position (the position where the protruding amount is the smallest) with respect to the light projecting portion 92a and the light receiving portion 92b. Thus, when the light projecting unit 92a emits light, the light amount received by the light receiving unit 92b is the largest. When the detection color member 91 rotates from the 0 ° position to the 180 ° position, the amount of light received by the light receiving portion 92b gradually increases, and when the detection color member 91 rotates from the 180 ° position to the 360 ° position, the light reception by the light receiving portion 92b. The amount gradually decreases and returns to the amount of light received in the state shown in FIG. 6 at the 360 ° position.

  Therefore, in the present embodiment, by detecting the amount of light received by the light receiving unit 92b when the separation roller 37 is rotated once, the rotation state of the separation roller 37 and the rotation state such as rotation unevenness are grasped, and according to the rotation state. Thus, the separation force of the separation roller 37 is changed. Specifically, the control unit 95 controls the rotational drive of the motor 81 (see also FIG. 4) of the separation force adjusting unit based on the received light amount data of the light receiving unit 92b and the reference data in the normal rotation of the detection color member 91. Yes.

  The control unit (control unit) 95 includes a microcomputer, a storage unit such as a RAM and a ROM, a program and data stored in the RAM and a ROM, received light amount data input from the light detection member 92, and reference data. Calculation is performed based on the reference data input from the storage unit 96, and the rotational driving amount of the motor 81 of the separation force adjusting unit is controlled.

  The reference data storage unit 96 includes a storage unit that stores reference data. The reference data is that when the separation roller 37 is driven to rotate without slipping with respect to the rotation of the paper feed roller 36, that is, when the detection collar member 91 makes one rotation at a predetermined rotation speed (when it rotates normally), the cylinder This is data based on the amount of received light corresponding to a change in a predetermined amount of the protrusion amount in the rotation axis direction of the cylindrical end portion 91a (axial end surface) with respect to a change in the predetermined rotation angle of the end portion 91a. The reference data S is represented by a sine curve (solid line) shown in FIG. In FIG. 7, the horizontal axis represents time, and the vertical axis represents the amount of received light. When the detection collar member 91 normally rotates once, the time from time t1 to time t2 shown in FIG. The amount of received light changes along the curve of the reference data S.

  The received light amount data T (broken line) shown in FIG. 7 is an example of output data of the light detection member 92 when the separation roller 37 is rotated, and the received light amount data T of the separation roller 37 is between time t1 and time t2. Thus, there is a deviation with respect to the amount of received light of the reference data S. This is because if the feeding is repeated, the rotational speed is reduced or uneven due to wear or the like, or the frictional force of the separation roller 37 changes due to the temperature / humidity change around the separation roller 37. It shows that the number is reduced and rotation unevenness occurs.

  Therefore, before the sheet feeding roller 36 starts feeding the sheet, the control unit 95 executes the separation force correction mode. In the separation force correction mode, when the paper feed roller 36 is driven to rotate, the separation roller 37 is driven to rotate by the rotation of the paper feed roller 36, and the light detection member 92 detects the rotation state of the separation roller 37, and based on the detection result. The separation force is adjusted. Specifically, when the separation roller 37 rotates once, the light detection member 92 detects the amount of light received as the detection color member 91 rotates, and the light reception amount data T is input from the light detection member 92 to the control unit 95. . The control unit 95 calculates a deviation amount W of the received light amount data T with respect to the reference data S of the reference data storage unit 96 based on, for example, integration of each light amount data. If the deviation amount W is within a predetermined range, the motor 81 is not driven because an appropriate separating force is obtained. In other words, the separation force adjusting unit does not operate the pressure spring 38 and does not change the pressure contact force of the separation roller 37 against the paper feed roller 36. On the other hand, when the deviation amount W exceeds the predetermined range, the motor 81 is driven by a predetermined amount in a direction in which an appropriate separation force is obtained, and the pressure contact force of the separation roller 37 with respect to the paper feed roller 36 is changed. When the separation roller 37 is worn or the frictional force of the separation roller 37 is reduced due to changes in the temperature / humidity environment, the pressing force of the separation roller 37 against the paper feed roller 36 is changed. Moreover, the structure which changes the magnitude | size of a press-contact force according to the magnitude | size of the deviation amount W exceeding the predetermined range may be sufficient. Alternatively, the separation force may be adjusted by repeating detection by the light detection member 92, and the separation force correction mode may be stopped when the deviation amount W falls within a predetermined range. As a result, the sheet can be stably fed even with repeated feeding and changes in the surrounding temperature and humidity environment.

  In the above-described embodiment, the separation force correction mode is executed before sheet feeding. However, it is also possible to execute the separation force correction mode during sheet feeding. In this case, the reference data S for each sheet type, such as plain paper or cardboard, is stored in the reference data storage unit 96, and according to the type of sheet sent from the pickup roller 29 (see FIG. 3), The corresponding reference data S is selected from the reference data storage unit 96 to execute the separation force correction mode. As a result, regardless of the type of sheet, the sheet can be stably fed even against repeated sheet feeding and changes in the surrounding temperature and humidity environment.

  In the above-described embodiment, an example in which the present invention is applied to the sheet feeding device 20 has been described. However, the present invention is not limited to this, and for example, a document conveying device (sheet conveying device) that separates and conveys sheet-like documents one by one. You may apply to an image reading apparatus provided with.

  In the above-described embodiment, the separation force adjustment unit changes the pressure contact force of the separation roller 37 against the paper feed roller 36 in order to adjust the separation force. However, the present invention is not limited to this, and the separation force adjustment is performed. The part may be configured to change the torque limit value of the torque limiter 43. In this case as well, the same effects as in the above embodiment can be obtained.

  Moreover, in the said embodiment, although the light reception amount data T when the separation roller 37 carried out 1 rotation was compared with the reference | standard data S, the structure which determined the appropriateness of separation power was shown, However, this invention is not limited to this. Alternatively, the separation roller 37 may be rotated two or more times, and the average value of the received light amount data T for each rotation may be compared with the reference data S to determine whether the separation force is appropriate.

  In the above-described embodiment, the rotation detection unit has a configuration in which the light projecting unit 92a made of a light emitting diode or the like and the light receiving unit 92b made of a phototransistor, a photodiode, or the like are arranged so as to face each other. However, the rotation detecting means is configured such that the light projecting portion 92a irradiates light to the cylindrical end portion 91a of the detection collar member 91, and the light receiving portion 92b receives light reflected by the cylindrical end portion 91a. Also good. Further, the light projecting unit 92a may irradiate laser light instead of the light emitting diode. Further, the rotation detecting means may be configured to measure the amount of displacement by contacting a measuring element such as a dial gauge with the cylindrical end 91 a of the detecting collar member 91 instead of the light detecting member 92.

  The present invention can be used in an image forming apparatus and an image reading apparatus, and in particular, a sheet conveying apparatus that separates sheets one by one and feeds them from a rotary feeding member, an image forming apparatus including the same, and an image It can be used for a reading device.

1 Image forming apparatus 20 Paper feeding device (sheet conveying device)
22-25 Paper feed cassette (sheet storage)
26 Conveying roller pair 28 Sheet stacking plate 29 Pickup roller 36 Paper feed roller (rotating feeding member)
37 Separation roller 38 Pressure spring 41 Oscillating member 41a Protrusion piece 43 Torque limiter 43a Torque limiter shaft 50 Sheet rising detection member 70 Sheet conveying unit 81 Motor (separation force adjusting unit)
82 Worm gear (separation force adjusting part)
83 Wheel gear (separation force adjusting part)
84 Actuating member (Separation force adjusting part)
86 Pressurizing lever (separation force adjusting part)
87 Support member 91 Detection collar member (detected member, rotation detection means)
91a Cylindrical end 92 Light detection member (detection member, rotation detection means)
92a Light projecting unit 92b Light receiving unit 95 Control unit (control means)
96 Reference data storage S Reference data T Received light amount data

Claims (5)

A rotation feeding member that feeds a sheet from a sheet accommodating portion that accommodates the sheet;
A separation roller that presses against the rotary feeding member to form a nip portion and separates the overlapped sheets at the nip portion;
A separation force adjusting unit that changes a force for separating the overlapped sheets by the separation roller;
A member to be detected that is provided so as to be rotatable together with the separation roller and has a cylindrical end portion in which the protruding amount of the axial end surface with respect to the rotation axis direction continuously changes, and a continuous displacement amount of the cylindrical end portion are detected. A rotation detecting means for detecting a rotation state of the separation roller based on a change in a detection amount of the detection member when the separation roller rotates,
A reference data storage unit that stores reference data indicating a change in the detection amount detected by the rotation detection unit when the detected member rotates normally;
It is possible to execute a separation force correction mode in which the separation force of the separation force adjustment unit is changed based on a deviation of the detected amount data indicating the change in the detected amount actually detected by the rotation detection unit with respect to the reference data. A sheet conveying apparatus comprising: a control unit.   The sheet conveying apparatus according to claim 1, wherein the separation force correction mode is executed before the sheet is fed by the rotary feeding member. The reference data storage unit stores a plurality of reference data according to the type of sheet,
The control means is configured to execute the separation force correction mode by selecting the reference data corresponding to the type of the sheet to be fed from the reference data storage unit when feeding the sheet by the rotary feeding member. The sheet conveying apparatus according to claim 1.   An image forming apparatus comprising the sheet conveying device according to claim 1.   An image reading apparatus comprising the sheet conveying apparatus according to claim 1.

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