JP2006137531A - Paper feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sheet from moving backward to a position where separation and feeding cannot be performed by avoiding a backward movement due to a stop of a feeding roller without providing a separation roller moving mechanism. To provide an inexpensive paper feeding device capable of reliably feeding paper to a desired position.
SOLUTION: A recording sheet P on an elevating tray 31 in an MPT cover 30 is transferred to an MPT conveying path m through which the recording sheet passes toward a relay conveying roller pair 24 and a gate roller pair 25 on the apparatus main body side. In an image forming apparatus (sheet feeding device) that includes a restriction pad 31c and a retard roller 34, which are brought into pressure contact with the outer peripheral surface 33a of the feeding roller 33 and separated and fed, a recording sheet to be separated and fed is transferred to a pair of relay conveying rollers. When the feeding roller stops after the delivery, the elevating tray is lowered before the feeding roller stops, and the leading edge of the recording sheet is separated from the outer peripheral surface.
[Selection] Figure 4

Description

  The present invention relates to a sheet feeding device, and more specifically, a set sheet is removed from a position where a plurality of sheets are separated and fed one by one to a position where the sheet cannot be recalled. The present invention relates to a device that can reliably separate and feed paper to a desired position.

  2. Description of the Related Art Conventionally, a sheet feeding device that sets a plurality of sheets in a stacked state, separates and feeds the sheets one by one, and feeds them to a desired position has been widely used. The original (paper) mounted on the image reading apparatus is fed to the image reading position, or the recording paper mounted on the image forming apparatus is fed to the image recording position.

  This type of paper feeder includes a feed roller that feeds the press-contacting paper downstream, and a direction in which a plurality of sheets can be stacked and set so that the leading end contacts and separates from the outer peripheral surface of the feed roller. And a retard roller (separation roller) that is driven to rotate by a load exceeding the set value by being in pressure contact with the outer peripheral surface of the feed roller on the downstream side in the rotational direction from the tip of the lift plate. ). In this paper feeding device, the outer peripheral surface of the feeding roller can be brought into pressure contact with the leading edge of the paper on the lifting plate to directly call the paper, and the paper is sandwiched between the retard roller and one sheet. They are separated and fed downstream. For this reason, in this paper feeding device, it is possible to save space and reduce costs by omitting the so-called pickup roller that calls the paper on the lifting plate.

In such a configuration of the paper feeding device, the paper is fed downstream by dragging the paper while the paper is sandwiched between the retard roller and the lifting plate. Even after delivery to the roller pair, it becomes a heavy load. For this reason, in the paper feeding device mounted in the image forming apparatus, after the recording paper is delivered to the roller pair on the downstream side of the feeding roller, the lifting plate and the retard roller are sequentially separated from the feeding roller. Has been proposed (see, for example, Patent Document 1). In addition, in the paper feeding device mounted on the image reading device, it is disclosed that the lifting plate and the retard roller are separated from the feeding roller after the document is delivered to the pair of rollers on the downstream side of the feeding roller and the like. (For example, refer to Patent Document 2).
Japanese Patent Laid-Open No. 11-334917 Japanese Utility Model Publication No. 5-89344

  However, in such a conventional sheet feeding device, the lifting plate generally has a function of lifting and lowering the leading edge of the sheet so as to be sandwiched between the feeding roller, but the feeding plate also feeds to the retard roller. If a mechanism for separating the roller from the roller is provided, a special mechanism must be installed as described in the above document, resulting in an increase in cost.

  Here, the feeding roller rotates in the paper feeding direction while rotating the retard roller, whereas the paper fed by the feeding roller is firmly supported by the downstream conveying roller pair and the gate roller pair. And is fed to a desired position. From this, it is possible to reduce the possibility that the paper feeding accuracy of the paper is lowered after the delivery to the pair of conveying rollers and the pair of gate rollers.

  However, when the paper feeding device tries to feed paper to the processing position on the apparatus main body side, the paper feeding roller may be stopped for convenience of processing on the apparatus main body side. In order to open a gap (so-called paper gap) between the feed rollers, the feeding roller is temporarily stopped. In particular, in the case of a paper feeding device mounted on an image forming apparatus, the recording paper is placed downstream before feeding the recording paper to the image recording position so as to match the image formation timing of the main body. Is temporarily stopped while being held between the pair of gate rollers on the side. At this time, in the case of a paper feeding device designed so that the path to the processing position by the apparatus main body is shortened in order to reduce the size of equipment in recent years, the recording paper does not come out of the nipping position by the feeding roller and the retard roller. May pause in a state.

  However, when the feed roller stops while the retard roller and the lifting plate are in pressure contact with the feed roller, a load is applied to the feed roller that causes the retard roller to reverse a little due to the reaction at the time of stoppage. At this time, if the leading edge of the paper on the lifting plate is in pressure contact with the outer peripheral surface of the feeding roller, a retreating force is applied to the leading edge of the paper and accumulates. A so-called back-slip occurs in which the outer peripheral surface of the feed roller is retracted so that it cannot be fed out.

  Accordingly, the present invention sets the paper without retreating to a position where it cannot be separated and fed by avoiding the retreat due to the stop of the feed roller without providing a mechanism for moving the separation roller. It is an object of the present invention to provide an inexpensive sheet feeding device that can reliably separate and feed sheets and feed them to a desired position.

  A first invention of a paper feeding device that solves the above problems includes a separation feeding unit that separates a plurality of sheets set at a loading position one by one and feeds them downstream, and the separation feeding unit. A transport unit that transports the paper sent from the feeding unit further downstream and feeds it to the processing position on the apparatus body side, and guides the paper sent from the stacking position to the processing position by the separation feeding unit and the transport unit. And a control unit that feeds paper from the stacking position to the processing position in accordance with the processing timing of the apparatus main body by controlling the driving of each part of the apparatus. The section includes a feed roller that feeds the press-contacted paper to the downstream transfer path, and a driven rotation or rotation restriction according to a frictional force between the feed roller and the paper while the paper is pressed against the feed roller. To separate the paper fed by the feed roller into one sheet A separation roller and a moving mechanism configured to stack a bundle of a plurality of sheets and moving a leading end portion of the sheets in a direction to contact and separate from an outer peripheral surface of a feeding roller upstream of the separation roller. The separation feeding unit is designed to have an apparatus configuration in which the separation roller is always in pressure contact with the feeding roller, and the control unit is configured to feed the leading edge of the sheet from the feeding roller at a timing when the feeding roller stops. The moving mechanism is driven and controlled so that the parts are separated from each other.

  In the present invention, at the timing when the feeding roller stops while the separation roller is in pressure contact, the leading edge of the upstream sheet can be moved away from the outer peripheral surface of the feeding roller, and the stop Even if the feeding roller reverses due to the reaction of the separating roller at that time, it is possible to prevent the sheet in front of the pressure contact position between the feeding roller and the separating roller from receiving a retreating force. Therefore, it is possible to prevent the sheet from being retracted every time the feeding roller is stopped, and being unable to separate and feed.

  According to a second invention of a paper feeding device that solves the above problem, in addition to the specific matters of the first invention, the transfer path is a paper fed from a pressure contact position between a feeding roller of the separation feeding unit and the separation roller. Is designed to have a path length that starts feeding paper to the processing position on the apparatus main body side by the transport unit, and the control unit controls the paper in accordance with the processing timing on the apparatus main body side. In order to feed the paper to the processing position, the transfer of the paper received from the separation feeding unit is temporarily stopped before the paper is removed from the pressure contact position between the feeding roller and the separation roller of the separation feeding unit. The feeding roller of the separation feeding unit is also stopped.

  In the present invention, since the sheet transfer path is short, even when the sheet feeding roller temporarily stops before the sheet comes out from the pressure contact position between the feeding roller and the separation roller, a force to retract the sheet in front of the pressure contact position is provided. It can be avoided in advance. Therefore, even during paper feeding, it is possible to avoid the accumulation of the backward force on the paper to be separated and fed next, and it is possible to reliably prevent the separation and feeding from being delayed.

  According to a third aspect of the paper feeding device that solves the above problem, in addition to the specific matter of the second aspect, the control unit is configured to feed the paper conveyed by the conveying unit to the feeding roller and the separating roller of the separating and feeding unit. The feed roller is also stopped after the pressure contact position is removed.

  In the present invention, even when the paper feed roller and the separation roller are temporarily stopped after the paper is removed from the press contact position, it is possible to prevent the paper in front of the press contact position from being subjected to a backward force. be able to. Therefore, for example, even when the feeding roller stops so as to open a gap between the sheets to be fed, it is possible to avoid the accumulation of the backward force on the sheet to be separated and fed next, and separation feeding is impossible. It is possible to reliably prevent the delay in the process.

  According to a fourth aspect of the paper feeding device that solves the above problem, in addition to the specific matters of the first invention, the control section feeds the paper to the processing position in accordance with the processing timing of the apparatus main body side. Therefore, when the transfer of the sheet received from the separation feeding unit is temporarily stopped before the sheet is removed from the pressure contact position between the feeding roller and the separation roller of the separation feeding unit, The driving of the moving mechanism is controlled so that the leading edge of the paper is separated from the feeding roller until the paper is removed from the pressure contact position.

  In the present invention, since the paper transport path is short, the paper feed roller temporarily stops before the paper comes out from the pressure contact position between the feed roller and the separation roller, and the paper feed path also after the paper comes out from the pressure contact position. When the feeding roller is temporarily stopped, it is possible to prevent the sheet to be separated and fed next from being evacuated and receiving the force to retract the sheet. Therefore, it is possible to avoid the accumulation of the backward force on the paper without wastefully moving the paper to be separated and fed by being brought into pressure contact with the feed roller, and it is reliable that the separation and feeding will be disabled later. Can be prevented with high performance.

  As described above, according to the present invention, without providing a mechanism for moving the separation roller, the feeding roller is stopped in a state where the separation roller is in pressure contact, and at the stop timing of the feeding roller, It is possible to prevent the sheet from being retracted by the feeding roller that is reversed by the reaction of the separating roller at the time of stopping, and to prevent the sheet from being accumulated and the separation feeding from becoming impossible. it can. Therefore, the set paper can be separated and fed with high reliability and fed to a desired position with an inexpensive configuration that only operates an existing mechanism that presses the leading edge of the paper to the outer peripheral surface of the feed roller. it can.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best embodiment of the invention will be described with reference to the drawings. 1 to 7 are views showing an example of an image forming apparatus equipped with an embodiment of a paper feeding device according to the present invention.

  In FIG. 1, an image forming apparatus 10 is a printer that is used by connecting to an external device such as a personal computer that creates and outputs an image such as a character. The image forming apparatus 10 includes image data such as a character that forms an image. An image recording apparatus that records and forms on one or both sides of a recording sheet by an electrophotographic method, and separates and feeds a plurality of stacked recording sheets one by one and conveys and feeds them to the image recording apparatus. And a sheet conveying device that unloads the recording sheet on which an image is recorded and stacks the recording sheet.

  The image recording apparatus will be briefly described. The laser beam scanning apparatus 11 that scans the laser beam L based on the image data, and the static beam based on the image data that is irradiated and scanned with the laser beam L from the laser beam scanning apparatus 11. A photosensitive drum (carrying member) 12 on which an electrostatic latent image is exposed and formed on the surface; a charger 13 for charging the outer peripheral surface of the photosensitive drum 12 so that an electrostatic latent image can be formed by irradiation with laser light L; The toner of yellow (Y), cyan (C), magenta (M), and black (K) is accommodated, and the accommodated toner is transferred and attached to the electrostatic latent image on the photosensitive drum 12 by the developing roller 14c. Thus, the developing cartridge 14a for each color for developing toner (only one portion is shown) and the developing cartridge 14a are stored in the installation space 14b for each color and face the photosensitive drum 12. A rotary developing device 14 that switches the developing cartridge 14a to be operated (developed), and a toner image (monochrome image or color image) that receives a toner image of each color developed on the photosensitive drum 12 and can be transferred and recorded on a recording sheet. ) And an intermediate transfer belt (intermediate transfer medium) 15 and the recording paper that has been transported and fed are pressed against each other (nip) so as to be sandwiched between the intermediate transfer belt 15 and conveyed downstream, and the intermediate transfer The transfer roller 16 that transfers the toner image carried by the belt 15 onto the recording paper that is nipped and conveyed, and the recording paper that has been transferred with the toner image transferred thereon are heated and pressed to fix the toner image and the recording paper is Further, the fixing roller pair 17 that is nipped and conveyed downstream, and the toner remaining on the photosensitive drum 12 are transferred to the blade 18a. Ri and the waste toner tank 18 recovered and storing, likewise, includes a waste toner tank 19 for storing the toner remaining on intermediate transfer belt 15 and collected by a blade, a. Note that the intermediate transfer belt 15 and the transfer roller 16 and the fixing roller pair 17 of the image recording apparatus also have a function of conveying a recording sheet, and thus constitute a part of a sheet conveying apparatus described below. .

  Briefly, the paper transporting device is detachably set at the bottom of the device main body 10, and a paper cassette 21 for storing a plurality of recording papers stacked on the lifting plate 21 a on the bottom surface, and the raising and lowering of the paper cassette 21. A pickup roller 22 that calls out (draws out) the uppermost recording sheet and feeds it to the conveyance path f by rotating to press against the separation pad 21b while being pressed against the bundle of recording sheets raised by the plate 21a, and the pickup roller 22 Receives the recording sheet sent out from the sheet cassette 21 and receives the recording sheet nipped and conveyed by the first relay conveying roller pair 23 for nipping and conveying the recording sheet to the downstream conveying path f. Further, a second relay transport roller pair 24 that sandwiches and transports it to the downstream transport path f, and this second relay transport roller pair 2. Receives a recording sheet transported into the transport path f, and is nipped and transported (paper feed) to a recording formation (transfer) position of an image by the intermediate transfer belt 15 and the transfer roller 16 of the image recording apparatus (so-called registration roller). The pair 25 and the recording paper on which the fixed image is formed on one side by being conveyed from the gate roller pair 25 through the conveyance path f between the intermediate transfer belt 15 and the transfer roller 16 and between the fixing roller pair 17 are received. The first and second paper discharge roller pairs 26 and 27 are loaded onto the paper discharge table 29 on the upper part of the apparatus main body 10 and discharged and stacked. This sheet conveying apparatus is arranged in a re-conveying path r for reversing the recording sheet on which the image is formed on one side and sending it to the conveying path f on the upstream side of the gate roller pair 25 and the path r. The third intermediate transport roller pair 28 receives the recording sheet sent into the re-transport path r when the first and second paper discharge roller pairs 26 and 27 are reversed. Thus, the image can be formed on both sides of the recording paper by passing it to the gate roller pair 25.

  As a result, the image forming apparatus 10 transfers the toner image obtained by developing the electrostatic latent image by attaching toner on the surface of the photosensitive drum 12 to one side or both sides of the recording paper via the intermediate transfer belt 15. Thus, a color image formed by superimposing yellow (Y), cyan (C), magenta (M), and black (K) toner on the surface of the intermediate transfer belt 15 can be transferred onto a recording sheet. Or a monochrome image formed with black (K) toner can be transferred to a recording sheet to form an image.

  Further, the sheet conveying device of the image forming apparatus 10 is provided with an opening / closing cover (exterior cover) 100 on the side surface in FIG. 1 so that the inside of the apparatus main body 10 can be opened and closed. A multipurpose tray cover (multipurpose cover) 30 on which various types of recording sheets to be interrupted from other than 21 are stacked is integrally provided to be openable and closable. The sheet conveying apparatus includes an MPT conveying path m for sending recording sheets stacked on the multipurpose tray cover (hereinafter abbreviated as MPT cover) 30 to the conveying path f on the upstream side of the gate roller pair 25. And the MPT feeding roller 33 disposed in the MPT transport path m separates and feeds the recording paper one by one to the second intermediate transport roller pair 24 and the gate roller pair 25. By transferring, the sheet can be fed to an image recording position by the intermediate transfer belt 15 and the transfer roller 16 of the image recording apparatus, and an image can be formed on the recording sheet.

  Specifically, in this image forming apparatus 10, an opening / closing cover (exterior cover) 100 on the side is pivotally supported by a rotating shaft provided at both lower ends. As shown in FIG. 2, the link members 102 to 105 that are attached to both sides in the paper width direction of the recording sheet to be conveyed and constitute the link mechanism and the traction spring 106 do not rotate and fall indefinitely. It is supported by. As a result, the opening / closing cover 100 removes the lock mechanism (not shown) and rotates the upper end in the direction (the left-right direction in FIG. 1) to move the upper end toward and away from the apparatus main body 10. For example, by rotating the clockwise direction in FIG. 1 to open the inside of the apparatus main body 10, the conveyance paths f and r of the sheet conveying apparatus are opened (exposed) and jammed during conveyance. It is possible to perform operations such as removing the recorded paper. The photosensitive drum 12 of the image recording apparatus, the developing cartridge 14a in the rotary developing device 14 and the like can be maintained by opening and closing a front opening / closing cover (not shown).

  The link members 102 and 103 of the link mechanism have base end portions 102a and 103a rotatably attached to the apparatus main body 10 side and the opening / closing cover 100 side, respectively, and distal end portions 102b and 103b are connected to be relatively rotatable. Thus, the opening / closing cover 100 is allowed to approach and separate from the apparatus main body 10. Thereby, the opening / closing cover 100 can be closed in a state where the link members 102 and 103 are folded as shown in FIG. 2A, and when opened, as shown in FIG. By rotating the link members 102 and 103 so as to separate the base end portions 102a and 103a, the link members 102 and 103 can be suspended and supported on the apparatus main body 10 side, and can be held at a set opening (rotation) angle. .

  In the link member 102, the outer peripheral surface of the base end portion 102a is formed on the cam surface 102c, and the link members 104 and 105 are connected to the cam surface 102c to restrict the rotation of the link members 102 and 103. Adjustment is made so that the rotation (opening) of the opening / closing cover 100 stops in multiple stages.

  More specifically, the link member 104 pivotally supports the rotating shaft 17c of one roller 17b of the fixing roller pair 17, and the upper portion of the rotating shaft 17c is pivotally attached to the apparatus main body 10 with the rotating fulcrum 104a. A traction spring 106 that applies a pressing force by urging the fixing roller 17b in the direction of approaching the other fixing roller 17a at a tip portion that is spaced below the rotation shaft 17c from the rotation fulcrum 104a. It is attached. The link member 105 is pivotally attached to the apparatus main body 10 with an intermediate portion serving as a rotation fulcrum 105a, and one end portion 105b of the link member 105 is pulled by a traction spring 106. The other end portion 105 c is in sliding contact with the cam surface 102 c of the link member 102.

  The cam surface 102c of the link member 102 changes its link by changing the distance between the position of sliding contact with the other end portion 105c of the link member 105 and the base end portion 102a of the rotation fulcrum according to the amount of rotation. The member 105 is designed to rotate, and when the opening / closing cover 100 is closed, the traction spring 106 allows the link member 104 to be pulled and rotated in a direction in which the fixing roller 17b is pressed against the fixing roller 17a. When opening the opening / closing cover 100, the link member 104 is rotated in a direction to separate the fixing roller 17b from the fixing roller 17a against the urging force (elastic force) of the traction spring 106, and the fixing roller pair 17 (17a, 17b) is released to release the nip pressure for nipping the recording paper. The opening / closing cover 100 does not naturally return from the open state to the closing direction because the urging force of the traction spring 106 overcomes the rotational force due to its own weight.

  As a result, the opening / closing cover 100 is connected to the cam surface 102c of the link member 102 and pulled by the traction spring 106 so as to rotate in the opening direction when the lock with the apparatus main body 10 is released. The link members 104 and 105 are restricted from trying to rotate the link members 102 and 103 and are held at the rotation positions. Therefore, the opening / closing cover 100 is held at a position where the upper part is slightly opened, and can be prevented from suddenly rotating and dropping to the fully opened state shown in FIG. .

  On the other hand, as shown in FIG. 3, the MPT cover 30 is integrally provided so as to be located inside leaving the peripheral edge of the opening / closing cover 100, and like the opening / closing cover 100, For the MPT that is pivotally supported by a moving shaft and is rotated in a direction (left and right direction in FIG. 1) in which the upper end of the opening / closing cover 100 is moved toward and away from the opening / closing cover 100. The conveyance path m can be opened and closed. The MPT cover 30 is maintained by the closing mechanism 50 so that the outer surface of the MPT cover 30 is substantially the same as that of the opening / closing cover 100. The closing mechanism 50 is formed by cutting out the wall surface 100 a of the recess of the opening / closing cover 100. The engagement piece 100b is formed in a single piece, and the engagement long hole 30d is formed by cutting out the side wall 30a of the MPT cover 30. In other words, the MPT cover 30 is simply opened and closed by opening and closing the MPT cover 30 by holding the gripping portion (not shown) disposed on the upper end side in the direction of approaching / separating from the opening / closing cover 100. 3), the engagement piece 100b of the opening / closing cover 100 can be engaged and disengaged in the engagement elongated hole 30d by moving forward and backward in the direction of the paper surface of FIG. And can be opened.

  When the MPT cover 30 is rotated in a direction in which the upper end portion is separated from the opening / closing cover 100 (clockwise direction in FIG. 3), the set recording paper is guided to the MPT transport path m side. In addition, the lower end portion is supported by the opening / closing cover 100 so that the outer upper end portion is located at a high place, and as shown in FIG. 4 and FIG. 31 and the extension tray 32, the feed roller 33 and the retard roller (separation roller) 34 are opened (exposed) so as to be usable, and the recording paper P set on the elevating tray 31 and the extension tray 32 is fed. 33 and the retard roller 34 can separate and feed one by one to the MPT conveyance path m to form an image. That is, the elevating tray 31, the extension tray 32, the feeding roller 33, and the retard roller 34 constitute a separation feeding unit, the relay conveyance roller pair 24 and the gate roller pair 25 constitute a conveyance unit, and the conveyance paths f and m are It constitutes a transfer route.

  The elevating tray 31 is pivotally supported by a rotating shaft 30b provided on the inner surface side of the side wall 30a of the MPT cover 30 so that a rear end portion 31a separated from the apparatus main body 10 side is rotatable. A limit pad 31c at the center of the tip 31b is installed on the 10-side feed roller 33 so as to be close to and away from the feed roller 33. As shown in FIG. 3, the elevating tray 31 has a lift plate 35 that is connected to the apparatus main body 10 and moves up and down, and is positioned between the MPT cover 30 on the lower surface side. Depending on the rotation angle of an eccentric cam 36 (shown in FIG. 5) that is always biased upward by a biasing member (not shown) (for example, a torsion spring) and that is rotated by a controller (control unit) 40 described later. By being pushed down against the biasing force of the biasing member, it moves up and down. That is, the elevating tray 31, the lift plate 35 and the eccentric cam 36 constitute a moving mechanism, and the leading end portion P 1 of the recording paper P placed on the upper surface of the elevating tray 31 is close to the outer peripheral surface 33 a of the feeding roller 33.・ Can be separated. Further, the elevating tray 31 can restrict the recording paper P to be pressed against the outer peripheral surface 33a of the feeding roller 33 by the restriction pad 31c, and the restriction pad 31c is the last sheet of recording paper P. Is set to a frictional surface that allows the outer peripheral surface 33a of the feeding roller 33 to be dragged.

  Further, the elevating tray 31 is provided with a pair of side guides 37 that are separated in the width direction of the recording paper P to be set (the vertical direction in FIG. 5). The side guides 37 stand on the upper surface side of the elevating tray 31. It is provided so as to be slidable in the width direction while maintaining the installed posture. Further, the side guide 37 extends to the pair of racks 39 that extend in the width direction of the recording paper P on the back side of the elevating tray 31 and are separated in the length direction of the recording paper P (left-right direction in FIG. 5). The racks 39 are connected to each other, and the racks 39 mesh with the pinions 38 disposed at the center thereof. As a result, the side guide 37 slides evenly in the width direction of the recording paper P on the lifting tray 31 and regulates the sides thereof, thereby separating the recording paper P in the MPT transport path m in an appropriate posture. Designed to feed.

  The extension tray 32 is inserted and accommodated in a space S defined between the back side of the elevating tray 31 and the MPT cover 30, and when the recording paper P is placed on the elevating tray 31, It is designed to be pulled out from the rear end portion P2 side of the recording paper P. When the extension tray 32 is pulled out, the extension tray 32 is used for MPT in a posture that substantially coincides with the extension surface of the elevating tray 31 (shown by a one-dot chain line in FIG. 4) having the tip 31b approaching the outer peripheral surface 33a of the feed roller 33. Supported by the cover 30. The extension tray 32 is formed on both sides while preventing the protrusion 32a at the tip end from being caught by the rib 30c standing on the side wall 30a of the MPT cover 30 when being pulled out. The extended side 32b is supported by the rib 30c of the MPT cover 30 so as to have a desired posture. Further, an auxiliary tray 32d is pivotally supported by a pivot shaft 32c on the rear end side of the extension tray 32, and when the long recording paper P is placed on the lifting tray 31, the auxiliary tray 32d is pivotally supported by the pivot shaft 32c. The mounting surface can be extended by rotating the auxiliary tray 32d.

  The feed roller 33 is disposed at a position corresponding to the restriction pad 31c at the center of the front end portion 31b of the elevating tray 31, and is rotated by a controller 40 described later. In FIG. 4, the recording paper P is rotated clockwise, and the recording paper P on the lifting tray 31 whose front end P1 is pressed against the outer peripheral surface 33a is called out (drawn) and sent out to the MPT transport path m.

  The retard roller 34 is rotatably supported in a state where the feed roller 33 and the outer peripheral surfaces 33a and 34a are in pressure contact with each other, and a fixed shaft 34b fixed to the apparatus main body 10 so as not to rotate. It is attached so as to rotate integrally with the torque limiter 34c. When the outer peripheral surfaces 33a and 34a of the feed roller 33 and the retard roller 34 are in direct pressure contact with each other, or when the torque limiter 34c is in direct pressure contact with the recording paper P dragged by the feed roller 33, the torque limiter 34c While the retard roller 34 is driven to rotate by the feeding roller 33 by the frictional force, the recording paper P that is pressed against the recording roller P is stopped by being stopped by the frictional force between the recording papers P dragged by the feeding roller 33. .

  As shown in FIG. 6, the controller 40 creates and outputs an image such as a character. For example, the controller 40 is connected to a personal computer PC and exchanges various control data and image data, and various data according to a program prepared in advance. By executing processing control and drive control of each part of the apparatus, the respective parts of the image forming apparatus 10 are collectively controlled to record and form an image on the recording paper P and print it out.

  The controller 40 includes, for example, a motor group 41 that drives each part of the apparatus, and step clutches 42 and 43 that are connected via a gear train (not shown) so that driving force can be transmitted from the drive shaft of the motor 41. It is connected so that it can be disconnected. The step clutch 42 is connected to a driving gear (not shown) that rotationally drives various driving rollers such as the pickup roller 22 and the feeding roller 33, and the controller 40 applies the driving force of the motor 41 to the feeding roller 33. The transmission can be connected / disconnected by the step clutch 42 to drive / stop the feeding roller 33 in the MPT conveyance path m, for example. Further, the step clutch 43 is connected to a drive gear (not shown) for rotating the eccentric cam 36, and the controller 40 connects and disconnects transmission of the driving force of the motor 41 to the eccentric cam 36 by the step clutch 43. Then, the eccentric cam 36 can be driven and stopped, and the elevating tray 31 can be raised and lowered via the lift plate 35.

  That is, when the controller 40 detects that the MPT cover 30 is opened with respect to the opening / closing cover 100 by a sensor (not shown), the controller 40 drives the motor group 41 to move the lift plate 35 through the step clutch 43. By rotating the eccentric cam 36 so as to be pressed down, the front end portion 31b of the elevating tray 31 is lowered to separate the recording paper P from the outer peripheral surface 33a of the feeding roller 33 so that it can be stacked thereon. In this state, when the start key is pressed from an operation unit (not shown), the controller 40 starts driving the motor group 41 and rotates the eccentric cam 36 so as to release the pressing of the lift plate 35. By raising the tray 31, the leading end P1 of the set recording paper P is pressed against the outer peripheral surface 33a of the feeding roller 33, and then the feeding roller 33 is rotationally driven via the step clutch.

  Thus, when the feeding roller 33 calls the recording paper P on the lifting tray 31 and sends it to the MPT transport path m, the limiting pad 31c at the center of the leading end 31b of the lifting tray 31 is placed on the lowermost recording paper P. While being pressed and sent out as it is, it is restricted from the lower side, and even if a plurality of recording papers P are sent to and from the retard roller 34, the recording paper P other than the uppermost is the outer peripheral surface 34 a of the retard roller 34. And only the uppermost recording paper P can be separated and fed one by one.

  At this time, as shown in FIG. 7, the controller 40 starts a driving operation of the image recording apparatus and the sheet conveying apparatus on the apparatus main body 10 side, and outputs a sensor signal (Vsync) for detecting one rotation of the intermediate transfer belt 15. The recording paper P on the elevating tray 31 is separated and fed so as to be synchronized with the reference image recording (transfer) and fed to the image recording position by the intermediate transfer belt 15 and the transfer roller 16. The raising / lowering of the raising / lowering tray 31 and the rotation of the feeding roller 33 according to the transfer amount of the recording paper P sent to the MPT conveying path m continuous to the conveying path f of the relay conveying roller pair 24 and the gate roller pair 25. Is controlled as follows.

  Specifically, first, the eccentric cam 36 is rotated at a timing delayed by a preset period from a sensor signal (Vsync) that detects one rotation of the intermediate transfer belt 15 before the image recording and forming process. By raising the elevating tray 31 (lift plate 35), the leading end P1 of the recording paper P stacked on the loading surface is brought into pressure contact with the outer peripheral surface 33a of the feeding roller 33 to feed the recording paper P. Prepare. Thereafter, the rotation of the feeding roller 33 is started at a timing delayed by a sufficient time t1 from the start of the raising of the lifting tray 31 to the completion thereof, and the recording paper P on the lifting tray 31 is started. Are separated and fed one by one in cooperation with the limiting pad 31c and the retard roller 34 at the leading end 31b, thereby passing the recording paper P from the MPT transport path m into the normal transport path f.

  Next, when the recording paper P fed to the transport path f is detected by a paper detection sensor (not shown) disposed in front of the relay transport roller pair 24, the relay transport roller pair 24 starts to rotate. Thus, the recording paper P passed through the transport path f is nipped and transported. At this time, from the detection timing of the recording paper P by the paper detection sensor in front of the relay transport roller pair 24, the relay transport roller pair 24 starts to rotate and is delayed by a time t2 sufficient for nipping and transporting the recording paper P. At this time, the eccentric cam 36 is further rotated to lower the elevating tray 31 so that the unrecorded recordings stacked on the mounting surface until the next recording sheet P starts to be separated and fed. The leading end P 1 of the paper P is separated from the outer peripheral surface 33 a of the feeding roller 33. As a result, the bundle of recording sheets P waiting to be fed on the lifting tray 31 stands by in a state of being temporarily separated from the feeding roller 33 and the retard roller 34. Note that t3 in FIG. 7 is a time lag from when the paper detection sensor of the relay conveyance roller pair 24 detects the recording paper P until rotation of the relay conveyance roller pair 24 is started. Further, in FIG. 7, the time for raising or lowering the lifting / lowering tray 31 is due to the shape of the outer peripheral surface of the eccentric cam 36 slidably contacting the lift plate 35. This is due to the difference in the required rotation angle.

  When the recording paper P nipped and conveyed by the relay conveyance roller pair 24 is detected by a paper detection sensor (not shown) arranged in front of the gate roller pair 25, the nipping conveyance of the recording paper P is detected by the relay conveyance roller pair. 24, the rotation of the feeding roller 33 is stopped until the next recording sheet P starts to be separated and fed, and the feeding roller 33 is rotated around the recording sheet P being nipped and conveyed (driven rotation). Let That is, the feeding roller 33 stops driving before the trailing edge P2 of the recording paper P comes out of the pressure contact position with the retard roller 34, and when the active rotation of the feeding roller 33 stops, The load for directly rotating the retard roller 34 in pressure contact with the outer peripheral surface 33a is released. Therefore, the retard roller 34 is in a direction opposite to the feeding direction of the recording paper P (clockwise direction in FIGS. 3 and 4) because the torque limiter 34c tends to return to the natural body with respect to the fixed shaft 34b. Slightly reverse. However, the bundle of recording papers P waiting to be fed on the lifting tray 31 is not in a state where the leading end P1 is brought into contact with the retard roller 34 by being lowered. As a result, even if the recording paper P waiting on the lifting tray 31 has a structure in which the feeding roller 33 and the retard roller 34 are kept in pressure contact with each other, the recording paper P is accumulated due to the reverse movement due to the reverse rotation of the retard roller 34. There is no occurrence of slippage after the front end portion P1 retreats to a position where it cannot press against the outer peripheral surface 33a of the feed roller 33.

  On the other hand, the relay conveyance roller pair 24 and the gate roller pair 25 after the recording paper P is detected by the paper detection sensor in front of the gate roller pair 25 does not distinguish between the recording paper P that has been passed through the conveyance path. The intermediate conveyance roller pair 24 is nipped and conveyed and fed to the image recording position, and the relay conveyance roller pair 24 only has a time t4 during which the leading edge of the recording paper P can sufficiently abut the nip portion of the gate roller pair 25. By continuing the nipping and conveying as it is, the skew (skew) of the recording paper P is corrected and then temporarily stopped.

  After this, the relay conveyance roller pair 24 and the gate roller pair 25 wait for a time t5 to synchronize the toner image on the intermediate transfer belt 15 with the transfer timing, and then the intermediate transfer belt 15 and the transfer roller 16 Rotation drive is started so as to feed the recording paper P to the image recording formation position between them, and the nipping and conveying operation to the image recording formation position is continued, and the trailing edge of the recording paper P is continued. When it is detected that the part P2 has been removed, the rotational drive is stopped.

  Here, when there are a plurality of recording papers P on which image recording and forming processing is performed, the fact that the rear end portion P2 of the recording paper P has come out of the press contact position of the relay conveyance roller pair 24 and the gate roller pair 25, respectively. A similar control operation for separating and feeding the next recording paper P from the up-and-down tray 31 is started before the detection by the paper detection sensor in front of the image. In FIG. Is shown.

  As described above, in this embodiment, while the retard roller 34 is kept in pressure contact with the feed roller 33, at the timing of stopping the feed roller 33, the elevating tray 31 is lowered to stand by with the feed roller 31. Since the pressure contact state with the leading end portion P1 of the recording paper P is eliminated, even if the retard roller 34 is slightly reversed by the reaction when the feeding roller 33 is stopped, the recording paper P on the lifting tray 31 is retracted. It is possible to prevent the recording paper P from being moved backward and accumulated so that the outer peripheral surface 33a of the feeding roller 33 cannot be pressed against the outer peripheral surface 33a. Therefore, only by adjusting the timing for moving the existing lift tray 31 up and down, the recording paper P to be imaged next is surely brought into pressure contact with the outer peripheral surface 33a of the feed roller 33, so that the tip 31b of the lift tray 31 is The restriction pad 31c and the retard roller 34 can be separated and fed with high reliability, and can be fed to an image recording position.

  As another aspect of the present embodiment, in the above-described embodiment, the lifting tray 31 is lowered from the middle of the conveyance of the recording paper P by the relay conveyance roller pair 24 and the gate roller pair 25 until the separation and feeding of the next recording paper P is started. The feed roller 33 is also stopped, but for example, after the recording paper P is delivered to the relay conveyance roller pair 24, the feed roller 33 continues to rotate and together with the gate roller pair 25 and the like. Even in the case of being configured to be temporarily stopped, the lifting tray 31 may be lowered immediately before the feeding roller 33 is stopped. Also in this case, the same effect can be obtained, and the recording paper P can be sent out together with the relay conveyance roller pair 24 and the gate roller pair 25. However, when the recording paper P is not of a type that requires a large number of delivery loads, the raising / lowering of the raising / lowering tray 31 is complicated, and therefore it is preferable to perform drive control as in the above-described embodiment.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

  For example, in the above-described embodiment, the case where the MPT cover 30 is opened and applied to the separation feeding portion of the recording paper P to be placed will be described as an example. However, the present invention is not limited to this. The present invention can also be applied to the case where a similar configuration is adopted for the mechanism.

  In the above-described embodiment, an example of an image forming apparatus that mounts a sheet conveying device and forms an image on a recording sheet by an electrophotographic recording type image recording apparatus is described, but the present invention is not limited thereto. Needless to say, the present invention may be applied to a paper feeding device in the paper conveying device of the apparatus, and may also be applied to an image forming apparatus that employs, for example, an ink jet recording system as an image recording system.

1 is a diagram illustrating an example of an image forming apparatus equipped with an embodiment of a sheet feeding device according to the present invention, and is a front perspective view illustrating a schematic overall configuration thereof. It is a figure explaining the opening / closing mechanism of the exterior cover, (a) is a state figure at the time of the closing, (b) is a state figure at the time of the opening. It is a figure which shows the state which open | released the MPT cover so that the multipurpose tray (MPT) installed in the exterior cover can be utilized, and is a partial cross-sectional side view of the cover. It is a see-through | perspective side view which shows the multipurpose tray. It is a top view which shows the multipurpose tray. FIG. 6 is a related block diagram for explaining control of recording paper feeding from the multi-purpose tray. 7 is a timing chart for explaining sheet feeding control of a recording sheet from the multi-purpose tray.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Laser beam scanning device 12 Photosensitive drum 14 Rotary developing device 14a Developing cartridge 15 Intermediate transfer belt 16 Transfer roller 17 Fixing roller pair 21 Paper cassette 22 Pickup rollers 23, 24, 28 Relay conveyance roller pair 25 Gate roller pair 26, 27 Paper discharge roller pair 29 Paper discharge table 30 Multipurpose tray (MPT) cover 31 Lift tray 31c Restriction pad 32 Extension tray 33 Feed roller 34 Retard roller 34b Fixed shaft 34c Torque limiter 35 Lift plate 36 Eccentric cam 40 Controller 41 Motors 42 and 43 Step clutch f Transport path m MPT transport path P Recording paper r Re-transport path

Claims (4)

A separation feeding unit that separates a plurality of sheets set at the loading position one by one and feeds them downstream, and further conveys the sheet sent from the separation feeding unit to the downstream side By controlling the driving of each part of the apparatus, a transport unit that feeds the processing position on the apparatus main body side, a separation feeding unit and a transport path that guides the sheet sent from the stacking position to the processing position by the transport unit A control unit that feeds paper from the stacking position to the processing position in accordance with processing timing on the main body side,
The separation feeding unit includes a feeding roller that feeds the press-contacting paper to a downstream transfer path, and a driven rotation or rotation limitation according to a frictional force between the feeding roller and the paper while pressing the paper against the feeding roller. The separation roller that separates the sheet fed by the feeding roller into one sheet, and a feeding roller that is configured to be capable of stacking a bundle of a plurality of sheets and that feeds the leading end of the sheet upstream of the separation roller And a moving mechanism for moving in a direction to make contact with and away from the outer peripheral surface of
The separation feeding unit is designed in a device configuration in which the separation roller is constantly pressed against the feeding roller,
The control unit drives and controls the moving mechanism so that the leading edge of the sheet is separated from the feeding roller at the timing when the feeding roller stops. The transfer path is a path length at which feeding of the sheet to the processing position on the apparatus main body side by the conveyance unit is started before the sheet to be fed is removed from the pressure contact position between the feeding roller and the separation roller of the separation feeding unit. Designed to
The control unit separates the transfer of the sheet received from the separation feeding unit from the feeding roller of the separation feeding unit so that the conveyance unit feeds the sheet to the processing position in accordance with the processing timing on the apparatus main body side. The paper feeding device according to claim 1, wherein when the paper is temporarily stopped before the paper is removed from the pressure contact position of the roller, the paper feeding roller of the separation feeding unit is also stopped.   3. The control unit according to claim 2, wherein the control unit stops the feeding roller even after the sheet conveyed by the conveying unit has come out of a pressure contact position between the feeding roller of the separation feeding unit and the separation roller. Paper feeder.   The control unit separates the transfer of the sheet received from the separation feeding unit from the feeding roller of the separation feeding unit so that the conveyance unit feeds the sheet to the processing position in accordance with the processing timing on the apparatus main body side. When the paper is temporarily stopped before the paper comes out from the pressure contact position of the roller, the leading edge of the paper seems to be separated from the feeding roller from the time before the paper pause until the paper comes out from the pressure contact position. The sheet feeding device according to claim 1, wherein driving of the moving mechanism is controlled.

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